Events | Seminar

  • seminar
    Date:
    25 January
    2022
    Tuesday
    Hours:
    13:30
    -
    14:30

    M.Sc thesis defense: "Examination of Interfacial Lithium Ion Transport through Computational and Experimental Techniques"

    participants: David Columbus
    Dr. Michal Leskes's group
  • seminar
    Date:
    23 January
    2022
    Sunday
    Hours:
    11:00
    -
    12:00

    Stormy weather: past and future hazards from a weather system perspective

    participants: Jennifer Catto
    University of Exeter

    Abstract

    Natural hazards such as extreme wind, rainfall and ocean waves can have severe impacts on built and natural environments, contributing to the occurrence of disastrous events in some cases. These hazards are often caused by weather systems such as cyclones, fronts and thunderstorms. We have used a number of objective techniques to identify these weather system types, in order to understand the links between the weather systems and hazards in observations. We have then used this understanding to evaluate climate models and to better understand the response of the weather systems and the high impact hazards to a warmer climate.
  • seminar
    Date:
    18 January
    2022
    Tuesday
    Hours:
    14:00
    -
    15:00

    A Single Molecule View of Signaling Complexes in Health and Disease

    participants: Prof. Eilon Sherman
    Racah Institute of Physics The Hebrew University
  • seminar
    Date:
    16 January
    2022
    Sunday
    Hours:
    11:00
    -
    12:00

    Direct Imaging of Planet Formation

    participants: Sivan Ginzburg
    California Institute of Technology

    Abstract

    The vast majority of detected planets are observed indirectly, using their small perturbation on the light emitted by the host stars. In recent years, however, the world's largest ground based telescopes have succeeded in directly imaging the light coming from some planets themselves. I will present our comprehensive theory for the mass, luminosity, and spin of gas giant planets during their final stages of formation - when they simultaneously contract and accrete gas from a disk. I will apply this theory to the luminosity and spectrum obtained by the novel direct-imaging technique, highlighting the recently discovered PDS 70 system, where two planets were directly observed during formation for the first time.
  • seminar
    Date:
    11 January
    2022
    Tuesday
    Hours:
    14:00
    -
    15:00

    Matchmaking Taste Receptors and Their Ligands

    participants: Prof. Masha Niv
    The Institute of Biochemistry, Food Science and Nutrition Faculty of Agriculture, Food and Environment The Hebrew University
  • seminar
    Date:
    11 January
    2022
    Tuesday
    Hours:
    11:00
    -
    12:00

    "Experimental Data-driven Paradigms for Unfolding Complexity in Chemical Systems"

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Yevgeny Rakita Shlafstein
    Columbia University: Data Science Institute with Applied Physics and Applied Mathematics Johns Hopkins University: Materials Science and Engineering

    Abstract

    With the growing complexity of functional materials and chemical systems, we often nd ourselves limited in our ability to fully represent the set of descriptors of a chemical system. In complex chemical systems, nding a complete crystallographic model that folds all the interatomic correlations using a small set of structural descriptors may not always be feasible or practical. Alternatively, one can take a data-driven approach and measure the relative changes in structural or chemical features (e.g, structural correlations, oxidation states). An experimental data-driven approach does not require complete models and enjoys the rapidly evolving machine-learning tool-set, which excel at classifying relational datasets and, if also labelled by an observed property, can provide predictive power that links system's descriptors with observed properties. I will focus on two types of complexities: (1) Hierarchical complexity, in which di erent types of structural or chemical correlations change change with the probed correlation length. For example, in ferroic materials di erent prop- erties (e.g., mechanical, dielectric, optoelectronic) may depend di erently on short- and long- range structural correlations. In multi-component alloys local chemical correlations (random- distribution, ordering, clustering) can a ect corrosion and plasticity, but altogether show a single average structural phase. Since selected materials' properties depend on correlations at a speci c hierarchical level, it is important to be able to isolate those from one another. (2) Evolutionary complexity, where the order changes over space and/or time. Nucleation, crys- tal growth, intercalation - are examples for processes that involve evolutionary complexity and can also be found in batteries, heterogeneous catalysis and photovoltaics. Isolating and track- ing order-related correlations in heterogeneous kinetically-stabilized or dynamically changing systems is, therefore, important for their more complete understanding, design and control. Total scattering and Pair Distribution Function (PDF) analysis are key methods for unfolding structural correlations at di erent correlation lengths. Using 4D-STEM to generate nm-resolution spatially-resolved electron-PDF data taken from hot-rolled Ni-laminated bulk-metallic-glass [1], I demonstrate how both hierarchical and evolutionary complexity can be uncovered and studied. Par- tially assisted with a machine-learning classi cation toolbox, we show how di erent aspects of the structural and chemical order, such as chemical-short-range-order, can be directly visualized as a function of position. In a di erent example [2] I show how an evolutionary complex systems can be manipulated to achieve a desired chemical state. In this example we demonstrate an active reaction control of Cu redox state from real-time feedback from in-situ synchrotron measurements. While complexity can lead to a lack of control over a chemical system, it is essentially adding tuning-knobs that, once isolated, understood and controlled, can unlock new materials with desired functionalities. [1] Y. Rakita, et al., Mapping Structural Heterogeneity at the Nanoscale with Scanning Nano-structure Electron Mi- croscopy (SNEM), arXiv:2110.03589 (2021). [2] Y. Rakita, et al., Active reaction control of Cu redox state based on real-time feedback from in situ synchrotron measurements, JACS 142, 18758 (2020). DOI: 10.1021/jacs.0c09418. 1
  • seminar
    Date:
    11 January
    2022
    Tuesday
    Hours:
    11:00

    Three arguments for increasing weather persistence in boreal summer – and why we should care.

    participants: Dim Coumou

    Abstract

    Persistent summer weather can have significant socio-economic impacts. Prolonged hot-dry conditions may lead to crop yield losses, while consecutive rainy days (e.g. associated with stalling cyclones) can cause flooding. Both observational and climate model analyses indicate that global warming weakens the hemispheric-wide circulation in boreal summer, yet it is still largely unclear what this weakening implies for the persistence of regional weather conditions. Here, I present multiple lines of evidence supporting that weather persistence in summer has been increasing over the last 40 years over most mid-latitude regions and will continue to do so under future global warming. Methodologically, we use a persistence metric rooted in dynamical systems theory, which does not require partitioning instantaneous atmospheric states in an arbitrary number of clusters. This makes it ideally suited to detect subtle changes in atmospheric motions including weather-persistence. I discuss relevant recent literature and argue that there is now substantial evidence for increasing weather persistence over mid-latitude regions, providing enhanced extreme weather risks for society.
  • seminar
    Date:
    4 January
    2022
    Tuesday
    Hours:
    14:00
    -
    15:00

    The σ₂ receptor: From a pharmacological curiosity to structure-based drug discovery

    participants: Dr. Assaf Alon
    Harvard Medical School
  • seminar
    Date:
    2 January
    2022
    Sunday
    Hours:
    11:00
    -
    12:00

    "Nanostructured functional materials as electrocatalysts for sustainable resources"

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Hannah-Noa Barad
    Max Planck Institute for Intelligent Systems, Stuttgart

    Abstract

    baradhn@is.mpg.de In the quest for improving sustainability of earth’s resources, discovery of new catalysts is a press-ing issue. There are several reasons for that, among which are: First, presently the most efficient and stable catalysts for the chemical processes that we use to transform raw resources into products with the desired functions (materials or energy type), contain expensive and non-abundant elements such as Pt, Ir, and Ru. This explains the efforts to find abundant, accessible, low-cost, stable alternatives that will yield functionality comparable to exist-ing catalysts. For example, for water splitting, many new materials with different compositions have shown promising results as catalysts. However, they are mostly prepared by wet chemical synthesis, which results in chemical waste and can be too slow for industrial use. Second, the morphology of the materials is important, because it affects their catalytic properties as higher surface areas yield more catalytic active sites, surface energetics change, leading to improved reaction rates, and other differences that affect catalytic activity. These reasons emphasize the motivation to accelerate the process of finding new materials with varying nanostructures and optimized functionality, by sys-tematic exploration of several parameter spaces. Glancing angle deposition (GLAD) is a physical vapor deposition (PVD) shadow growth technique where the substrate is positioned at an oblique angle to the vapor source and can be manipulated with regard to substrate tilt angle and rotation, during the deposition. The thin films obtained by GLAD have unique nano-structures, which depend on ballistic shadowing of the substrate, and are formed as nano-structured films, leading to 3D nano-fabrication. I will present the first original results I obtained of using GLAD to form different types of material compositions and nanostructures as functional catalysts for sustainable resources. Nano-scale mor-phology and material composition are varied simultaneously using an adapted shadow growth GLAD system,[1] which eliminates the commonly used wet chemical steps for nanostructure synthe-sis. In a well-controlled one-step growth, I quickly and directly attain a large number of different nano-columnar structures, including nanorods, nano-barcodes, and nano-zigzags, with varying ma-terial compositions, on a single large-area substrate. GLAD also serves to form nanoporous ultra-thin mesh structures, in a novel dry synthesis method.[2] Both nanostructure types were studied for their electrocatalytic performance in the O2 evolution as well as CH3OH oxidation reactions and show high activity and stability. The insights I gained, show a dependence of catalytic activity on composition and nanostructuring, which the standard experimental techniques cannot achieve or explore, thus illustrating the importance and impact that GLAD has, and will have, on developing sustainable catalysts. [1] H.-N. Barad, M. Alarcón-Correa, G. Salinas, E. Oren, F. Peter, A. Kuhn, P. Fischer, Mater. To-day 2021, In Press, DOI 10.1016/j.mattod.2021.06.001. [2] H. Kwon, H.-N. Barad, A. R. S. Olaya, M. Alarcon-Correa, K. Hahn, G. Richter, G. Wittstock, P. Fischer, ArXiv211105608 Phys. 2021.
  • seminar
    Date:
    27 December
    2021
    Monday
    Hours:
    10:00
    -
    11:00

    Ph.D thesis: (Zoom)- "Electro(chemo)mechanical properties of non-stoichiometric oxides

    participants: Evgenyi Makagon

    Abstract

    Zoom Link: https://weizmann.zoom.us/j/91582672181?pwd=WFR1NVhKZGtra2w1WG9CcGFLSGU0Zz09 Non-stoichiometric oxides are a group of materials that are extremely popular in the energy storage and conversion industry. Their functionality relies heavily on point defects and their various properties show significant dependency on point defect type and concentration. This work deals with three such properties: mechanical, electromechanical and electro-chemo-mechanical while looking into two case study materials: 1. Acceptor-doped proton conducting BaZrO3, a promising electrolyte for protonic ceramic fuel cells as it combines high bulk proton conductivity with good chemical stability. The protonic conductivity is achieved by dissociative water incorporation into oxygen vacancies formed by acceptor dopants on Zr4+ sites. Doping was found to cause linear decrease in elastic modulus with increasing dopant concentration while the size of the dopant was proved to be a key factor. Water incorporation into the vacancies decreases the moduli even further. An unexpectedly large strain electrostriction coefficient of ≈ 5·10-16 m2/V2 was observed which makes BaZrO3 the first non-classical electrostrictor with a perovskite structure. The electromechanical response was observed to follow elastic moduli trend with respect to dopant size, giving a clear indication that electrostrictive response is related to point defect induced lattice distortions. 2. Acceptor doped oxygen conducting CeO2. The first known all solid-state electro-chemo-mechanical actuators operating at room temperature were demonstrated. These devices are based on nanocrystalline (Ti-oxide/Ce0.8Gd0.2O1.9) and (V-oxide/Ce0.8Gd0.2O1.9) composite layers. Under applied bias these composites undergo an electrochemical reaction generating change in specific volume and, thereby, mechanical work. The nanocrystalline composites are the key part of these devices and they are specifically designed to provide the fastest oxygen ion diffusion coefficient observed in a solid at room temperature. This achievement paves a way to a new field of studies: all solid-state chemotronics. The findings presented in this work link together three properties of non-stoichiometric ion conducting oxides: elastic deformation, electromechanical response and solid-state electrochemistry.
  • seminar
    Date:
    26 December
    2021
    Sunday
    Hours:
    11:00

    The impact of friction on the stability of ice sheets

    participants: Roiy Sayag

    Abstract

    Ice sheets can dramatically impact the state of climate. This is due to their capacity to modify the planetary energy balance through variations in the ice cover and mass. A major question is how rapidly could such modification occur and to what extent ? This question can be addressed by investigating phenomena that involve relatively large mass flux of ice into the ocean, such as ice calving and rifting, ice streams, and melting. Many of these processes involve interactions between the ice sheet and the underlying bedrock or ocean. We model ice sheets as buoyancy-driven flows of nonlinear (non Newtonian) fluid and explore the resulted flow dynamics and stability due to different friction conditions along the base of the ice. I will show results from scaled laboratory experiments and theoretical modelling of several flows under different friction conditions that evolve patterns reminiscent to those that emerge in glacier ice flows. Specifically, the basal friction that we consider ranges from no-slip conditions, in which radially symmetric flows are stable, to free-slip conditions, in which such flows are unstable, developing patterns reminiscent to ice rifts and ice bergs. Under mixed conditions of friction, an initially radially symmetric flow can be either stable, or develop patterns reminiscent to ice streams. Our insights may have implications to predicting ice flow on Earth and possibly on other planetary objects.
  • seminar
    Date:
    22 December
    2021
    Wednesday
    Hours:
    15:00
    -
    16:00

    M.Sc thesis: "Computational approach to excited state dynamics at the interfaces of layered transition-metal dichalcogenide heterostructures"

    Location: The David Lopatie Hall of Graduate Studies
    participants: Amir Kleiner

    Abstract

    Single layers of transition metal dichalcogenides are semiconducting 2D materials which present unique electronic, excitonic and spin properties. Heterostructures composed of these materials show highly intriguing excited-state phenomena, along with a large degree of atomistic and structural tunability stemming from the underlying quantum selection rules dominating these phenomena. A predictive understanding of the effect of structural complexity on the nature of excited-state properties and interaction dynamics is crucial in order to design efficient devices for various applications, within the fields of photovoltaics, photocatalytics, optoelectronics, spintronics, and material-based quantum computing. In this research, we propose a study of the electronic and excitonic properties in heterostructures based on layered transition metal dichalcogenides and the role of structural complexities in their time-resolved relaxation mechanisms. For this, we will analyze decay processes induced by excitonic interactions with lattice vibrations, as well as other excitons and charged particles in the crystals. We will utilize predictive, Green’s-function based ab-initio methods implemented through advanced software and apply highly advanced computations using high-performance computing clusters worldwide. We will develop computational models based on these predictive approaches and on our findings to study the underlying mechanisms dominating the involved excitation processes and the light-matter interactions leading to them. Our research will be constantly driven and validated by collaborations with relevant experimental research.
  • seminar
    Date:
    21 December
    2021
    Tuesday
    Hours:
    14:00
    -
    15:00

    Ubiquitin-proteasome System Contribution to Hypoxia-induced Mitochondria Quality Control

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Michael Glickman
    Faculty of Biology, Technion
  • seminar
    Date:
    19 December
    2021
    Sunday
    Hours:
    11:00

    Lessons from the past: Climate variability in the Levantine corridor during the Pliocene-Pleistocene transition

    participants: Nicolas Waldman

    Abstract

    The study of past warm climates with high atmospheric CO2 concentrations provides important tools for understanding present trends and developing mitigation strategies for future scenarios. The Pliocene is the last long lasting warm interval characterized by similar global climate circulation patterns and continental settings as today. Reconstructing Pliocene climate change from well-dated geological archives provides valuable insights into the climate forcing and pathways that modulated the transfer of heat and humidity and disentangle regional impacts without anthropogenic influence. To address this challenge, the current presentation shows initial results from a comprehensive study that amalgamates high-resolution multi-proxy analyses from both marine and lacustrine records from the Levant region aiming to provide an important reference for future climate and environment change scenarios under high atmospheric CO2 concentrations.
  • seminar
    Date:
    14 December
    2021
    Tuesday
    Hours:
    15:00
    -
    16:00

    Zoom: Embarking on a Thermal Journey in Low Dimensions with a 21st Century Thermometer: Graphene Nonlocal Noise

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Jonah Waissman
    Dept. Physics and Applied Physics, Harvard University

    Abstract

    Zoom Link: https://weizmann.zoom.us/j/95894806650?pwd=c21JSFRhcUZaalROaUlBWnh4T25yZz09 Low-dimensional materials, such as 2D monolayers, 1D nanowires, and 0D quantum dots and molecules, are rich with new phenomena. The reduced dimensionality, strong interactions, and topological effects lead to new emergent degrees of freedom of fundamental interest and promise for future applications, such as energy-efficient computation and quantum information. Thermal transport, which is sensitive to all energy-carrying degrees of freedom and their interactions, provides a discriminating probe to study these materials and identify their emergent excitations. However, thermal measurement in low dimensions is dominated by the lattice, requiring an approach to isolate the electronic contribution. In this talk, I will discuss how the measurement of nonlocal voltage fluctuations in a multiterminal device can reveal the electronic heat transported across a low-dimensional bridge. We use 2D graphene as an electronic noise thermometer, demonstrating quantitative electronic thermal conductance measurement over a wide temperature range in an array of dimensionalities: 2D graphene, 1D nanotubes, 0D localized electron chains, and 3D, microscale bulk materials. I will discuss ongoing work revealing electron hydrodynamics, interaction-mediated plasmon hopping, spin waves in a magnetic insulator, and a crossover from phonon to spin transport in a bulk spin liquid candidate material.
  • seminar
    Date:
    14 December
    2021
    Tuesday
    Hours:
    14:00
    -
    15:00

    From Molecules to Organs: Bayesian Metamodeling Across Representations and Scales

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Barak Raveh
    School of Computer Science and Engineering The Hebrew University of Jerusalem
  • seminar
    Date:
    7 December
    2021
    Tuesday
    Hours:
    14:00
    -
    15:00

    Protein Solubility and Aggregation: Mechanisms and Design

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Elizabeth Meiering
    Department of Chemistry University of Waterloo, Canada
  • seminar
    Date:
    7 December
    2021
    Tuesday
    Hours:
    11:00
    -
    12:00

    Dispersion vs. Steric Hindrance: Reinvestigating Classic Steric Factors

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Ephrath Solel
    Institute of Organic Chemistry, Justus Liebig University

    Abstract

    London dispersion (LD) interactions, the attractive part of the van-der-Waals interaction1,2 hold somewhat of a unique position in the chemical world. Although their role in influencing macroscopic phenomena (such as the higher boiling points of larger alkanes) is well recognized, they are usually overlooked when discussing molecular phenomena. Substituents in reactions are generally considered as a source of “steric hindrance” and not as “steric attractors”, better termed dispersion energy donors (DEDs). As such, their influence on reaction outcomes was quantified and presented by classic steric factors such as the A-value. We have shown, using computational quantum mechanical tools, that these well recognized steric factors have also an attractive LD component that balance part of the steric repulsion. By focusing on the LD component we can explain various non-intuitive trends between substituents, such as the inconsistency between the size of the halogens and their A-values.3 In addition, a systematic analysis of both the steric and dispersion interactions of the same molecules allows us to quantify the relative weights of the two effects and form a new DED scale.4 Such corrected steric and LD factors could later be applied to explore the role of LD interactions also in other reactions. Our computations show that LD interactions have a significant influence on the overall relative stabilities and energetics in cyclohexane chair conformers, and also in related concerted reactions, and must not be ignored in reaction design.    Bibliography (1) Eisenschitz, R.; London, F. Z. Phys. 1930, 60, 491–527. (2) London, F. Trans. Faraday Soc. 1937, 33, 8–26. (3) Solel, E.; Ruth, M.; Schreiner, P. R. London Dispersion Helps Refine Steric A-Values: The Halogens. J. Org. Chem. 2021, 86 (11), 7701–7713. (4) Solel, E.; Ruth, M.; Schreiner, P. R. London Dispersion Helps Refine Steric A‑Values: Dispersion Energy Donor Scales. J. Am. Chem. Soc. 2021, Accepted.
  • seminar
    Date:
    5 December
    2021
    Sunday
    Hours:
    11:00

    Transient response of the tropical rain belt to volcanic eruptions

    participants: Ori Adam
  • seminar
    Date:
    30 November
    2021
    Tuesday
    Hours:
    14:00
    -
    15:00

    Folding and Quality Control of Membrane Proteins

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Nir Fluman
    Dept. of Biomolecular Sciences Weizmann Institute of Science
  • seminar
    Date:
    29 November
    2021
    Monday
    Hours:
    11:00
    -
    12:00

    Prof. Israel Rubinstein 2nd Memorial Lecture- "From Materials Electrolyte Innovations to New Sustainable Battery Chemistries

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Jean-Marie Tarascon
    College de France, Paris; Director of the French Research Network on Electrochemical Energy Storage
  • seminar
    Date:
    21 November
    2021
    Sunday
    Hours:
    11:00

    TBA

    participants: Raluca Rufu
  • seminar
    Date:
    16 November
    2021
    Tuesday
    Hours:
    11:00

    Chemical and Biological Physics Guest Seminar

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Eyal Karzbrun
    U. California, Santa Barbara

    Abstract

    Our organs exhibit complex and precise shapes which emerge during embryonic development. While biology has focused on a genetic study of organ formation, we have a limited understanding of the mesoscale mechanical forces which shape organs. A central question is how the physical form of an organ self-organizes from the collective activity of its constituents - thousands of fluctuating microscopic biological cells. Establishing a physical framework for understanding organ shape across scales requires a tight interplay between experiment and theory. However, organ development occurs within the embryo, an extraordinarily complex and coupled system with limited experimental access. To address this challenge, we developed a minimal quantitative system to study the dynamics of organ shape formation in a dish. By combining materials science with stem-cell research tools, we recreated the formation of the human neural tube - the first milestone in brain development. Experiments and vertex-model simulations reveal that a wetting transition can explain the complex dynamics of neural tube formation. Our approach paves the way for a predictive understanding of human organ formation in health and disease.
  • seminar
    Date:
    14 November
    2021
    Sunday
    Hours:
    11:15

    Chemical and Biological Physics Guest Seminar

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Alexandra Tayar
    U. California, Santa Barbara

    Abstract

    Non-equilibrium thermodynamics is a contemporary research subject that crosses fields from stellar evolution, nonlinear turbulence to biological organisms. Active matter is a subclass of non-equilibrium materials, where symmetry is broken locally and energy is consumed at the constituent level. The scale of the energy input is elementary in revealing new rich non-equilibrium physics. Currently, there is no unifying thermodynamical framework to describe non-equilibrium systems and energy propagation across scales. Therefore, it is instrumental to develop new programmable active systems that allow for a quantitative parameter space study. Biological building blocks offer reproducibility, uniformity, monodispersity, programmability at the molecular scale, and high efficiency of energy consumption. Using these design principles, we assembled new men made DNA-based active systems that exhibit spontaneous flows of materials and self-organization at the mesoscale. We study the phase behavior of soft materials in particular liquid phase separation in a non-equilibrium environment. Unexpectedly, we found that the coexistence region of phase separation shifts due to the non-equilibrium nature of the environment in low-shear regime that cannot be explained by existing theoretical frameworks. We further study the propagation of active forces across length scales, measuring molecular arrangement and mechanical loads that power active turbulent like dynamic. The unique capabilities of the developed system provide insight into possible mechanisms by which nanometer-sized molecular machines drive macroscale chaotic flows.
  • seminar
    Date:
    14 November
    2021
    Sunday
    Hours:
    11:00

    A Simple Model For Interpreting Temperature Variability And Its Higher-Order Changes

    participants: Talia Tamarin
  • seminar
    Date:
    10 November
    2021
    Wednesday
    Hours:
    11:00
    -
    12:00

    Ph.D thesis defense: “Structural and optoelectronic properties of surface-guided halide perovskite nanowires”

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Ella Sanders
    Dept. Molecular Chemistry and Materials Science

    Abstract

    Metal halide perovskites (MHPs) have re-emerged as exceptional semiconductor materials for photovoltaics and optoelectronics, gaining tremendous attention in the fields of materials and energy harvesting over the past decade. Their unique properties, alongside their relatively cheap and easy production, make them excellent candidates as materials for the next-generation optoelectronic technologies. Besides their technological advantage, their soft ionic lattice and anharmonic potential, that are part of the underlying reasons for their unusual and outstanding performance, challenge the well-established models of classical semiconductor physics and provoke many scientific research opportunities and questions. In order to intrinsically study these outstanding behaviors, a simple system is requires, diminishing complexities that can arise when examining the popularly studied polycrystalline thin films that contain multiple defects, mainly grain boundaries. Over the past decade, our group has been developing and mastering the surface-guided growth of horizontal semiconductor NWs, which can be employed to grow arrays of epitaxial single crystal MHP NWs. These NWs offer a unique opportunity as a simple model-system for investigating the intrinsic properties of MHPs, due to their single crystal nature and quasi one-dimensional structure. These are especially suitable for the investigation of how lattice strain affects the materials’ properties, considering their inherent heteroepitaxial strain. The aim of this PhD work was to gain insight on the growth of surface-guided CsPbBr3 NWs, as a representative of the MHP family, and study the effect of epitaxial strain on their structure and properties. To achieve this goal, we first developed the crystal growth of the surface-guided CsPbBr3 NWs on sapphire, by a few different vapor-phase methods. We inspected their growth in situ using simple optical microscopy to try to learn how these unique materials grow. These were followed by integration of the NWs into nanodevices in order to examine their optoelectronic properties, with a special emphasis on the influence of strain on their performance. We finally exemplified a high-throughput study using an automated optical system that can probe many NWs in a short amount of time, to develop a charge-carrier behavior model based on a large amount of data. Studying the epitaxially strained surface-guided CsPbBr3 NWs provides important insight into the crystal growth and optoelectronic properties of MHPs
  • seminar
    Date:
    7 November
    2021
    Sunday
    Hours:
    11:00

    On the tropospheric response to transient stratospheric momentum torques

    participants: Idan White
  • seminar
    Date:
    2 November
    2021
    Tuesday
    Hours:
    14:00
    -
    15:00

    Why Chirality Is Essential for Life

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Ron Naaman
    Department of Chemical and Biological Physics Weizmann Institute
  • seminar
    Date:
    31 October
    2021
    Sunday
    Hours:
    11:00

    Promenades through Nobels' landscapes: From disorder & fluctuations to organization in Earth’s climate and other complex systems

    participants: Michael David Chekroun
    Department of Earth and Planetary Sciences Weizmann Institute of Science
  • seminar
    Date:
    24 October
    2021
    Sunday
    Hours:
    15:00

    Chemical and Biological Physics PhD Seminar

    participants: Alon Luski
    PhD with Prof Ed Narevicius
  • seminar
    Date:
    17 October
    2021
    Sunday
    Hours:
    11:00

    TBA

    participants: Yossi Ashkenazy
    Department of Solar Energy & Environmental Physics The Jacob Blaustein Institutes for Desert Research Ben-Gurion University of the Negev
  • seminar
    Date:
    13 October
    2021
    Wednesday
    Hours:
    14:00
    -
    15:30

    Chemical and Biological Physics Guest Seminar

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof Yossi Paltiel
    Applied Physics Department and the Center for Nano science and Nanotechnology, Hebrew University, Jerusalem

    Abstract

    Using the chiral induced spin selectivity (CISS) effect we were able to induce local spin impurities on magnetic and superconducting material. Dynamic control of spin impurities was also achieved. The CISS is an electronic phenomenon in which electron transmission through chiral molecules depends on the direction of the electron spin. Thus charge displacement and transmission in chiral molecules generates a spin-polarized electron distribution. This effect; is metastable and may generate local magnetic defect that can be enhanced or removed by electric dipole. Also selective process may organize the molecules adsorption. In my talk I will show that when chiral molecules are adsorbed on the surface of thin ferromagnetic film, they induce magnetization perpendicular to the surface, without the application of current or external magnetic field. On s wave superconductors that are not magnetic, chiral molecules generate states that are similar to magnetic impurities, as well as change the order parameter of the superconductor. This metastable breaking of time reversal symmetry enables to: 1. achieve magnetic mapping with nanoscale resolution. 2. develop magnetic materials controlled at the nanoscale. 3. develop chiral gated controlled devices.
  • seminar
    Date:
    4 October
    2021
    Monday
    Hours:
    18:00
    -
    19:00

    Protein Folding and Dynamics webinar

    participants: Peter Wright
    The Scripps Research Institute
  • seminar
    Date:
    27 July
    2021
    Tuesday
    Hours:
    14:00
    -
    15:30

    "IDP-membrane interactions in neurodegeneration and neuronal function”

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. David Eliezer
    Weill Cornell Medicine Graduate School of Medical Sciences, NY, USA
  • seminar
    Date:
    25 July
    2021
    Sunday
    Hours:
    10:00
    -
    11:00

    A few lessons that nanoparticles can teach us about non-equilibrium properties of crystallization

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Assaf Ben Moshe
    Dept Molecular Chemistry and Materials Science, WIS

    Abstract

    The fact that many crystals are not in equilibrium is quite obvious and not very surprising. Yet, this often complicates our attempts to understand some of their most fundamental properties, such as for instance, their overall morphology. To further add to this complexity, non-equilibrium properties are nowadays studied in crystals made out of building blocks that consume energy and actively propel (i.e., active matter). Despite some complications that exist when trying to make analogies between the behavior of bulk crystals and their nanoscale analogs, the latter offer many advantages when studying kinetic aspects of crystal formation, in both “conventional” as well as “active” crystals. In my talk I will present two different cases where nanocrystals are used in order to shed light on some of these aspects. The first story dates all the way back to the 19th century and the seminal work by Louis Pasteur on crystals that exhibit chiral macroscopic shapes when made out of chiral building blocks. Using a model system of tellurium nanocrystals, I was able to show that the reason for chiral shape formation in crystals composed of chiral building blocks might not always be as trivial as expected. In the second part of the talk, I will present the first steps I took on an ongoing journey to understand the diffusion of extremely small (sub 10 nm) chemically propelled nanocrystals. This is meant to pave the way to ultimately use them as building blocks for non-equilibrium active crystalline matter.
  • seminar
    Date:
    6 July
    2021
    Tuesday
    Hours:
    11:00
    -
    12:00

    Intermolecular Interactions: Surfaces, Molecules and Molecular Solids

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Dr. A. Daniel Boese
    University of Graz, Graz, Austria
  • seminar
    Date:
    6 July
    2021
    Tuesday
    Hours:
    10:00
    -
    11:00

    Halite deposition in the Dead Sea: Direct observations and lessons for thick halite sequences in the geological record

    participants: Ido Sirota
    Institute of Earth Sciences The Hebrew University of Jerusalem

    Abstract

    Layered halite sequences were deposited in deep hypersaline basins throughout the geological record. These sequences are of research interest for hydrocarbon extraction, mineral exploration, tectonics and structural geology and paleoclimate research. Modern analogs and the processes leading to deposition of thick halite sequences were studied only through analyses of the common modern, shallow environments, which are fundamentally different in their nature from halite-depositing, deep waterbodies. Thus, the spatiotemporal evolution of halite sequences remained ambiguous. I will present, first, a study of the active precipitation of halite layers from the only modern analog in the world for deep, halite-precipitating basin; the hypersaline Dead Sea. Then the implications of these results to the geological record will be emphasized. Novel in situ observations in the Dead Sea link seasonal hydroclimatic conditions, thermohaline stratification, halite saturation, and the characteristics of the actively forming halite layers. The main findings of this study are: (a) Halite deposition dynamics is directly related to the development of the thermohaline stratification and it is primarily temperature controlled; it is counter-intuitive to the common approach that focus on the role of the hydrological budget in the study of hypersaline environments. (b) A pronounced depth dependency of the degree of halite saturation and halite deposition. (c) A well-defined seasonality of halite deposition on the deep lakefloor. (d) Preferential halite accumulation at the deep, hypolimnetic lake floor (>25m depth) due to intensive halite dissolution at the shallow epilimnetic lakefloor, and its re-deposition at depth, in a process termed “halite focusing”. (e) Halite accumulates at high rates in the deep lakefloor, doubling (or even more) the expected thickness without halite focusing. (f) Freshwater inflows further amplify halite thickness at the drier parts of the lake. These findings provide insights and quantify the processes required for reconstructing past hypersaline environments from halite sequences, in the Dead Sea and worldwide.
  • seminar
    Date:
    29 June
    2021
    Tuesday
    Hours:
    10:00
    -
    11:00

    Inferring Mars' Surface Winds by Analyzing the Global Distribution of Barchan Dunes using a Convolutional Neural Network

    participants: Lior Rubanenko
    Department of Geological Sciences Stanford University

    Abstract

    Sand seas on Mars are riddled with eolian landforms created by accumulating sand particles. When the sand supply is limited and the wind is approximately unidirectional, these landforms take the shape of crescentic barchan dunes, whose slip-faces are approximately perpendicular to the dominant wind direction, and their horns are oriented downwind. The morphology of barchan dunes is thus routinely used to infer wind conditions on Mars by manually analyzing aerial or satellite imagery. Despite the effectiveness of this technique on a local scale, employing it on a global scale remained challenging thusfar - as manually outlining individual dunes globally is impractical, and automatic detection methods have been largely ineffective at accurately segmenting dunes in images. Here we use Mask R-CNN, an instance segmentation convolutional neural network, to detect and outline dunes globally on Mars in images obtained by the Mars Reconnaissance Orbiter Context Camera (MRO CTX). We measure the morphometrics of dunes from their detected outlines, and infer the direction of the winds that formed them. By comparing the global wind distribution we derived to a global climate model, we study Mars' past and recent climate, and constrain global sand mobility thresholds which offer insight into the erosion and dust lifting capabilities of the atmosphere of the Red Planet.
  • seminar
    Date:
    27 June
    2021
    Sunday
    Hours:
    14:00
    -
    15:00

    Phosphine Carboxylate - a Water Sensitive Compound Prepared in Aqueous Solution”

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Roy Emanuel Shreiber
    Dept. Molecular Chemistry and Materials Science, WIS

    Abstract

    Phosphine carboxylate, H2PCO2-, was prepared and isolated for the first time. This heavier analogue of carbamate was found to be a carbon dioxide adduct on the edge of stability. The mechanism of phosphine carboxylate formation was found to proceed by a chain reaction that alternates between the acidified HPCO and the newly found cyclic hemi-acidified H(PCO)2-. This mechanism sheds light on the electrophilic reactivity of PCO- and similar molecules as well as their acid-base reactivity. Acidification of phosphine carboxylate forms phosphine carboxylic acid, an analogue of carbamic and carbonic acids that has surprising kinetic stability. Nucleophilic reactivity of phosphine carboxylate forms stabilized organic-soluble esters that may be used as building blocks in organic synthesis
  • seminar
    Date:
    20 June
    2021
    Sunday
    Hours:
    11:00
    -
    12:00

    Hybrid Talk: “POLYSACCHARIDE HYDROGELS CROSS-LINKED VIA PEPTIDE-DENDRIMERS”

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Ronit Bitton
    Dept. Chemical Engineering, BGU
  • seminar
    Date:
    25 May
    2021
    Tuesday
    Hours:
    10:00

    TBA

    participants: Elan Levy
  • seminar
    Date:
    20 May
    2021
    Thursday
    Hours:
    14:00
    -
    15:00

    M.Sc thesis defense: “Preparation of multifunctional protein- polysaccharide fibrillar thin films with tunable mechanical and electrical properties”

    participants: Asaf Rosenberg
    Dept Molecular Chemistry and Materials Science, under the supevision of

    Abstract

    Zoom Link: https://weizmann.zoom.us/j/96221353497?pwd=OWppT1ExY1Ewcm8zSGt4MzcvNWNiUT09 The central aim of the research is to understand how the molecular and nanoscale interactions between two natural biopolymers, fiber-forming protein-silk and conductive polysaccharide-pectin, shaping the physical properties of macro-scale composite material.
  • seminar
    Date:
    18 May
    2021
    Tuesday
    Hours:
    15:00
    -
    16:00

    Stir and mix: studying upper ocean dynamics from theory to application

    participants: Abigail Bodner
    Environmental and Society Brown University

    Abstract

    Near the ocean surface, mixing and turbulence modulate the transfer of heat, momentum, carbon and other properties, between the atmosphere and ocean interior. Accurate representation of these processes in General Circulation Models (GCMs) is crucial for simulating atmosphere-ocean interactions. However, all of these processes, generally known as boundary layer turbulence and submesoscale mixing, are on scales smaller than the grid used in GCMs, even at the highest possible resolution. Current submesoscale parameterizations represent the bulk of mixing developed across submesoscale fronts– the sharp interface between waters of different densities– but it has been shown to be too simplistic and unfitting in many circumstances. The presence of turbulence has been missing from these dynamics, and in this talk I will discuss the long-lasting problem of how to correctly include them. 
Building toward a more complete understanding of these processes, a theoretical approach of perturbation analysis is used to include the effects of turbulence as a correction to classic frontogenesis (frontal sharpening) theory. This approach is next extended into a more realistic environment, using a suite of high resolution, turbulence resolving, numerical simulations. It is found that a variety of turbulent processes resulting from winds, waves, convection, and instabilities affect the formation of fronts. Furthermore, this analysis exposes severe limitations in existing techniques to predict potential vorticity dynamics in highly turbulent regimes. Lastly, I will discuss modifying the submesoscale parameterization in GCMs to represent the complex interactions with boundary layer turbulence.
  • seminar
    Date:
    6 May
    2021
    Thursday
    Hours:
    09:15
    -
    10:15

    Zoom Lecture: “NMR of RNA: dynamics or in-cells”

    participants: Prof. Katja Petzold
    Dept. of Medical Biochemistry and Biophysics, Karolinska Institute, Stockholm

    Abstract

    Zoom Lecture: https://weizmann.zoom.us/j/98819686427?pwd=algvMEJUNHdvaFppNS9xVzlTUkhYQT09 Passcode: 551107 Many functions of RNA depend on rearrangements in secondary structure that are triggered by external factors, such as protein or small molecule binding. These transitions can feature on one hand localized structural changes in base-pairs or can be presented by a change in chemical identity of e.g. a nucleo-base tautomer. We use and develop R1ρ-relaxation-dispersion NMR methods for characterizing transient structures of RNA that exist in low abundance (populations <10%) and that are sampled on timescales spanning three orders of magnitude (µs to s). The characterization of three different types of transient structures is going to be presented. 1) The HIV-1 dimerization initiation site (DIS) undergoes large secondary structure rearrangements that provide the basis for a molecular zipper, which can be crucial for genome packaging (Nature 2012). 2) The GU wobble base-pair undergoes a change from standard wobble GU geometry to appear like a Watson-Crick base-pair stabilized by Keto-Enol tautomerization (Nature 2015). 3) a microRNA – mRNA complex changes conformation to activate the RISC complex (Nature 2020). I will furthermore give an outlook on recent efforts to measure in-cell NMR of nucleic acids in functional complexes and ribosome dynamics. www.petzoldlab.com
  • seminar
    Date:
    4 May
    2021
    Tuesday
    Hours:
    10:00

    What causes the leakiness of the North Atlantic Deep Western Boundary Current?

    participants: Aviv Solodoch
    Department of Atmospheric and Oceanic Sciences UCLA

    Abstract

    The Atlantic Meridional Overturning Circulation (AMOC) is a circulation pattern of great climatic importance. Its northward heat flux at the upper water column moderates European winter climate, and its descending branch captures atmospheric CO2 into the deep ocean, hence buffering the anthropogenically induced rise in global temperature. The Deep Western Boundary Current (DWBC) has classically been considered to be the main AMOC conduit southward at depth. However, tracer data have shown in recent decades that the DWBC "leaks" most of its material to the ocean interior in a small region of the North Atlantic, and that this leaked material continues southward in different, complex routes. These pathways and their causes are still little-explored and not well understood. In this talk I will present analysis of the DWBC leakiness properties and dynamics, based on existing datasets of passively drifting floats, a new high resolution regional numerical model, and theoretical analysis. Several alternative mechanisms of leakiness are considered, and a novel finding is that a leading cause for the leakiness is inertial separation of the current from the seafloor, near underwater capes. The role of eddies and their interaction with the separation process is investigated as well. Implications for the robustness of the deep AMOC pathways are discussed.
  • seminar
    Date:
    27 April
    2021
    Tuesday
    Hours:
    10:00
    -
    11:00

    Deposition of Gypsum Deltas at the Holocene Dead Sea by outsalting and paleoclimatic insights

    participants: Nurit Weber
    Department of Earth and Planetary Sciences Weizmann Institute of Sciences

    Abstract

    The rapid retreat of the Dead Sea during the past decades led the exposure of unique structures of massive gypsum and aragonite crusts: large capes pointing towards the open lake (termed here “gypsum deltas”) and numerous small gypsum mounds scattered on the lake’s exposed shores. Geological field relations, 14C and 34S measurements and thermodynamic calculations provide evidence that the gypsum deltas and the mounds were formed during time-intervals of low lake stands (~420±10 m below mean sea level), when sulfate-rich Ca-chloride brines discharged from the coastal aquifer via saline springs, mixed with the Dead Sea brine and precipitated the gypsum. This mixing process describes a mechanism of “gypsum outsalting”, which is completely different from the conventional view of gypsum as a product of evaporative deposition. Condition for enhanced saline springs discharge and “gypsum outsalting” occurred in the mid to late Holocene period (~ 6.6 to 0.6 ka), and were mainly intensive at the latest stages of regional aridity cycles when lake level was still low and the Dead Sea salinity was at its highest. The ages of formation of the gypsum structures coincide with times of North Atlantic cooling events and grand solar minima suggesting a direct impact of the latter on the Dead Sea hydrology and high sensitivity of the regional hydrology (controlling lake level) to global solar-related events. The frequency of appearance of the gypsum structures seems to follow the Hallstat Cycle that approached minimum at ~3000 2000 years ago.
  • seminar
    Date:
    26 April
    2021
    Monday
    Hours:
    14:00

    Physics-guided machine-learning parameterizations of subgrid processes for climate modeling

    participants: Janni Yuval
    Earth, Atmospheric and Planetary Sciences MIT school of Science

    Abstract

    Global climate models represent small-scale processes, such as clouds and convection, using subgrid models known as parameterizations. Traditional parameterizations are usually based on simplified physical models, and inaccuracies in these parameterizations are a main cause for the large uncertainty in climate projections. One alternative to traditional parameterizations is to use machine learning to learn new parameterizations which are data driven. However, machine-learning parameterizations might violate physical principles and often lead to instabilities when coupled to an atmospheric model. I will show how machine learning algorithms, such as neural networks and random forests, can be used to learn new parameterizations from the output of a three-dimensional high-resolution atmospheric model, while obeying physical constraints such as energy conservation. Implementing these parameterizations in the atmospheric model at coarse resolution leads to stable simulations that replicate the climate of the high-resolution simulation, and capture important statistics such as precipitation extremes. I will also discuss how machine-learning parameterizations can give further insights into the parameterization problem. Specifically, I will show that failures of machine-learning parameterizations can be used to better understand the relationship between large-scale fields and subgrid processes.
  • seminar
    Date:
    25 April
    2021
    Sunday
    Hours:
    11:00
    -
    12:00

    “Elastic-mediated interactions between cells”

    participants: Prof. Shelly Tzlil
    Faculty of Mechanical Engineering, Technion

    Abstract

    Zoom Link: https://weizmann.zoom.us/j/97324532197?pwd=MGoxSGhJODNWQ2ZGT1p4elJjMG9lZz09 Cell-cell communication is essential for growth, development and function. Cells can communicate mechanically by responding to mechanical deformations generated by their neighbors in the extracellular matrix (ECM). The ECM is a non-linear viscoelastic material and therefore mechanical communication is expected to be frequency-dependent. In my talk, I will describe our work on the characteristics and implications of mechanical communication over the ECM.
  • seminar
    Date:
    20 April
    2021
    Tuesday
    Hours:
    00:00

    The hydrological paradox - why the whole is less than the sum of its parts?

    participants: Erwin Zehe
    KIT

    Abstract

    Hydrological systems are inherently non-linear and exhibit an enormous structural and functional heterogeneity. Strikingly, we can nevertheless successfully simulate stream flow generation and the water balance of river catchments with rather simple models that are largely incompatible with the frequently reported subscale process heterogeneity and non-linearity. Here we argue that subscale structural heterogeneity and randomness must not prevent the emergence of functional simplicity. On the contrary, we found simplicity to emerge at rather small scales, reflecting self-organization in hydrological functioning not despite but due to subscale small-scale heterogeneity and the dissipative nature of hydrological process. While we acknowledge that hydrological landscapes are heterogeneous, they are by no means a random product. Catchments exhibit a considerable spatial organisation, which manifests through structured patterns of topography, soil, vegetation, self-similar surface and subsurface drainage networks and most prominently through ubiquitous preferential flow phenomena. While this organized “catchment from” does strongly determine present storage, cycling and release of water, energy and chemical species, this catchment form has in turn been shaped by of water, energy, and nutrients of the past. Is this “co-evolution” just chance or manifested self-organization? This question has been inspiring many scientists to search for thermodynamic principles that link form and function in the Earth system. Here we will present evidence that a thermodynamic and information theoretic perspective opens up new avenues for (i) diagnosing and explaining self-organization in hydrological dynamics, (i) upscaling of constituting relations and (i) using thermodynamic optimality for hydrological predictions.
  • seminar
    Date:
    13 April
    2021
    Tuesday
    Hours:
    16:00
    -
    17:00

    Larger tsunamis from megathrust earthquakes where slab dip is reduced

    participants: Bar Oryan
    Lamont Doherty Earth Observatory Columbia University

    Abstract

    A subset of megathrust earthquakes produce anomalously large tsunamis for their magnitude. All of these recorded ‘tsunami earthquakes’ in the past 50 years had extensional aftershocks in the upper plate. These include the two largest and most destructive earthquakes of that period, the 2004 Sumatra–Andaman and the 2011 Tohoku events. Evidence from the region of Tohoku indicates that normal fault slip in the upper plate during the earthquake may have contributed to the tsunami size. Here we present a numerical model that shows how a reduction of the dip of a subducting slab, on a timescale of millions of years, can result in an extensional fault failure above a megathrust earthquake on timescales of seconds to months. Slab dip reduction bends the upper plate so that the shallow part fails in extension when a megathrust rupture relieves compressional stress. This results in a distribution of extensional aftershocks comparable to that seen above the Tohoku megathrust. Volcanic arc migra- tion and uplift data for Tohoku and several other tsunami earthquakes is consistent with slab dip reduction. The collection of more such data might identify other areas of tsunami hazard related to slab dip reduction.
  • seminar
    Date:
    11 April
    2021
    Sunday
    Hours:
    11:00
    -
    12:00

    “Engineering personalized tissue implants: From 3D printing to bionic organs”

    participants: Prof. Tal Dvir
    Faculty of Life Sciences, TAU

    Abstract

    Zoom LInk: https://weizmann.zoom.us/j/95962123886?pwd=ZWV6WkwxKzlNU00zRU1ER3JIWkg4Zz09 In this talk I will describe cutting-edge bio and nanotechnologies for engineering functional tissues and organs, focusing on the design of new biomaterials mimicking the natural microenvironment, or releasing biofactors to promote stem cell recruitment and tissue protection. In addition, I will discuss the development of patient-specific materials and 3D-printing of personalized vascularized tissues and organs. Finally, I will show a new direction in tissue engineering, where, micro and nanoelectronics are integrated within engineered tissues to form cyborg tissues and bionic organs.
  • seminar
    Date:
    6 April
    2021
    Tuesday
    Hours:
    00:00

    Advances of remote sensing in agriculture and forestry for climate change adaptation

    participants: Tarin Paz-Kagan
    Volcani Institute

    Abstract

    Forests and agricultural orchards are becoming increasingly susceptible to drought, ‎insect ‎‎outbreaks, and disease due to climate change worldwide. Thus, forest ‎and ‎agricultural systems management needs to be proactively targeted to improve their ‎resilience to anthropogenic and ‎climate change. The potential of remote sensing ‎data for ‎agriculture and forestry has long been recognized. The global coverage and repositories of different ‎types ‎of satellite data extending integrating with developing UAVs and ‎sensor ‎capabilities provide a unique database, which allows us to develop, test, and ‎implement ‎innovative measures to adapt agriculture and forest to the foreseen climate ‎scenarios. ‎However, there is still a considerable gap between data and information. ‎Remote sensing ‎applications integrated with innovative artificial intelligence techniques ‎could make ‎fundamental discoveries for sustainable environmental management. Thus, ‎the seminar ‎aims to present advanced remote-sensing applications for agriculture and ‎forest to climate ‎change adaptation. Four case studies will be presented, including (1) ‎mapping woody ‎species distribution and richness along the climatic gradient; (2) ‎developing canopy ‎geometry traits to characterize and monitor tree structure using LiDAR ‎applications; and (3) ‎Incorporation winter tree physiology in deciduous orchard into ‎forecast- models of bloom ‎and yield, and (4) leaf to landscape approach to study ‎forest responses to drought.
  • seminar
    Date:
    16 March
    2021
    Tuesday
    Hours:
    10:00
    -
    11:00

    Supported Nanocomposites for Water Decontamination

    participants: Ines Zucker
    Tel Aviv University

    Abstract

    Contamination of drinking water sources by a variety of organic and inorganic compounds demands more efficacious and reliable treatment technologies. However, conventional water treatment technologies remain chemically demanding, energy intensive, and ineffective in removing key trace contaminants. As such, nanotechnology-based approaches have been increasingly explored to enhance or replace traditional remediation methods because of the high reactivity and tunable-properties of nanomaterials. In her talk, Dr. Zucker will provide an overview on the current status of nano-enabled water decontamination, including promising opportunities and barriers for implementation. Specifically, the application of molybdenum disulfide (MoS2) for heavy metal removal will be extensively discussed as a case study, where material properties, removal mechanisms, and large-scale applications are optimized.
  • seminar
    Date:
    14 March
    2021
    Sunday
    Hours:
    11:00
    -
    12:00

    Nucleation fronts initiate frictional motion

    participants: Prof. Jay Fineberg

    Abstract

    Zoom LInk: https://weizmann.zoom.us/j/97917323609?pwd=OGpCVzNKWGlCSS9lbTIyS0FtN1lHUT09 Recent experiments have demonstrated that rapid rupture fronts, akin to earthquakes, mediate the transition to frictional motion. Moreover, once these dynamic rupture fronts ("laboratory earthquakes" ) are created, their singular form, dynamics and arrest are well-described by fracture mechanics. Ruptures, however, need to be created within initially rough frictional interfaces, before they are able to propagate. This is the reason that ``static friction coefficients” are not well-defined; frictional ruptures can nucleate for a wide range of applied forces. A critical open question is, therefore, how the nucleation of rupture fronts actually takes place. We experimentally demonstrate that rupture front nucleation is prefaced by slow nucleation fronts. These nucleation fronts, which are self-similar, are not described by fracture mechanics. They emerge from initially rough frictional interfaces at a well-defined stress threshold, evolve at characteristic velocity and time scales governed by stress levels, and propagate within a frictional interface to form the initial rupture from which fracture mechanics take over. These results are of fundamental importance to questions ranging from earthquake nucleation and prediction to processes governing material failure.
  • seminar
    Date:
    4 March
    2021
    Thursday
    Hours:
    09:30
    -
    10:30

    “Beyond mapping: perturbation as the key to understanding function”

    participants: Dr. Michal Ramot
    Dept Neurobiology, WIS

    Abstract

    Zoom link: https://weizmann.zoom.us/j/94322871667?pwd=NXkvODRXWVZlbW9hSEtScHN1M0F4dz09 passcode: 870711 Neuroimaging has allowed us to map the correlations between brain activation, and external stimuli or behaviour. Yet these correlations can only hint at the function of the brain regions involved. In order to more casually investigate these relationships between brain and behaviour, we must perturb the brain, and see what changes this brings about in behaviour. I will provide a framework for doing so through covert neurofeedback. This technique allows us to perturb brain networks by reinforcing desired network states directly, through a reward orthogonal to the networks being trained. Yet a prerequisite for such a test of function and causality, is a strong hypothesis regarding the purported link between a specific network and behaviour. We must therefore also develop better behavioural tools, in order to establish such links.
  • seminar
    Date:
    2 March
    2021
    Tuesday
    Hours:
    16:00
    -
    17:00

    TBA

    participants: Kevin Uno
    Lamont-Doherty Earth Observatory Columbia University
  • seminar
    Date:
    28 February
    2021
    Sunday
    Hours:
    11:00
    -
    12:00

    Modeling formation of caveolar superstructures

    participants: Prof.Michael Koslov
    Department of Physiology and Pharmacology, TAU

    Abstract

    Zoom Link: https://weizmann.zoom.us/j/92668474661?pwd=d01aQVZkWnhiT0NRQlFkVE5XeWRjdz09 Caveolae, the flask-shaped pits covered by caveolin-cavin coats, are abundant features of the plasma membrane of many cells. Besides appearing as single membrane indentations, caveolae are organized as superstructures in the form of rosette-like clusters. Here we propose that clustering of caveolae is driven by forces originating from the elastic energy of membrane bending deformations and membrane tension. We substantiate this mechanism by computational modeling, which recovers the unique shapes observed for the most ubiquitous caveolar clusters consisting of two, three, four and five caveolae.
  • seminar
    Date:
    18 February
    2021
    Thursday
    Hours:
    09:30
    -
    10:30

    Room Temperature 13C-DNP in Diamond Powder

    participants: Dr. Daphna Shimon
    Institute of Chemistry, HUJI

    Abstract

    Zoom Link: Zoom: https://weizmann.zoom.us/j/91742036303?pwd=cWJuOFBEZUpYU3p6bHBjUEduRllxdz09 Passcode: 771770 Electron and nuclear spins in diamond have long coherence and relaxation times at room temperature, making them a promising platform for applications such as biomedical and molecular imaging and nanoscale magnetic field sensing. While the optically-active nitrogen-vacancy (NV) defect has received a great deal of attention, the substitutional nitrogen (or P1) center also exhibits long coherence and relaxation times. These P1 centers are typically present at significantly larger concentrations (about an order magnitude larger) than NVs, allowing us to explore the role of P1-P1 interactions in mediating DNP. The system can, in principle, show DNP via the solid effect (SE), cross effect (CE) and Overhauser effect (OE) depending on the P1 concentration and the field. Here, we show enhancement of natural abundance 13C nuclei found within the diamond, using the unpaired electron of the P1 center (concentration 110-130 ppm) in particles with a 15-25 μm diameter, under static conditions at room temperature and 3.4 T. We discuss the DNP spectrum, the active DNP mechanisms and what we can learn about the diamond powder from DNP.
  • seminar
    Date:
    16 February
    2021
    Tuesday
    Hours:
    10:00

    Styles and rates of landscape evolution away from tectonic-plate boundaries: examples from southern Africa

    participants: Shlomy Vainer
  • seminar
    Date:
    15 February
    2021
    Monday
    Hours:
    14:30
    -
    15:30

    Ph.D thesis defense: Tuning the shape memory effect in polyurethanes by amorphous and crystalline mechanisms"

    participants: Asaf Nisenbaum

    Abstract

    Zoom Link: https://weizmann.zoom.us/j/92088510918?pwd=bW11Rk1TKzEzeFdES3NJS1VCaTE4Zz09
  • seminar
    Date:
    14 February
    2021
    Sunday
    Hours:
    11:00
    -
    12:00

    “Transcription Factors Binding and the Regulation of Gene Expression: Lessons from Single-Molecule Experiments”

    participants: Prof. Ariel Kaplan
    Faculty of Biomedical Engineering, Technion

    Abstract

    Zoom Link: https://weizmann.zoom.us/j/94661424796?pwd=U0Z1YjdsbGUrV29STEZlMVhweUtXUT09 All our cells contain the same genetic information, encoded in the sequence of nucleotides that compose our DNA. The identity of different cells, and their response to different stimuli, is therefore controlled by processes regulating which subset of genes is “expressed” at a specific cell and a specific time. The first step in gene expression regulation is the binding of a special family of proteins, called transcription factors, to specific sequences in regulatory regions in the DNA. Packaging of the DNA into the dense structure of chromatin, and chemical modifications of the DNA, provide the cell with the possibility of dynamically modulating expression but add additional layers of complexity to the process in ways that are not fully understood. In my talk, I will report on our work using single-molecule optical tweezers assays to study how the thermodynamics and kinetics of transcription factor binding are modulated by these different layers of information. .
  • seminar
    Date:
    2 February
    2021
    Tuesday
    Hours:
    10:00

    Adventures in the Critical Zone: from carbon fluxes to wildfires

    participants: Antonello Provenzale

    Abstract

    The Hadley circulation is a key element of the climate system. It is traditionally defined as the zonally averaged meridional circulation in the tropics, therefore treated as a zonally symmetric phenomenon. However, differences in temperature between land and sea cause zonal asymmetries on Earth, dramatically affecting the circulation. This longitudinal dependence of the meridional circulation evokes questions about where and when the actual large scale tropical circulation occurs. Here, we look into the connection between the longitudinally dependent meridional circulation, and the actual large scale transport of air in the tropics using a coupled Eulerian and Lagrangian approach. Decomposing the velocity field into rotational and divergent components, we identify how each component affects the actual circulation. We propose an alternative definition for the circulation, that describes the actual path of air parcels in the tropics, as a tropical atmospheric conveyor belt. We further investigate this definition, analyzing the circulation under climate change and its effect on precipitation changes. We show that in order to predict future climate, the regionality and three-dimensionality of the large-scale tropical circulation must be taken into account. We find that the changes in the circulation vary significantly over longitude, and are overlooked when analyzing the zonally averaged meridional circulation. The circulation is strengthening and expanding in the center of the Pacific, a region where the circulation barely existed in past. On the other hand, the circulation is weakening in the Indo-Pacific region, where it was the most significant in the past. These differences appear as a shift in the region of ascent of the conveyor belt, that is revealed when analyzing the decomposed vertical wind. The pattern of weakening of the ascent in the Indo-Pacific and strengthening in the center of the Pacific explains the projected changes in precipitation. The Indo-Pacific region is drying, while the precipitation in the center of the Pacific is intensifying.
  • seminar
    Date:
    31 January
    2021
    Sunday
    Hours:
    14:00
    -
    15:00

    Simulating Chemistry from Atoms to Devices: Next-Generation Reactive Molecular Dynamics

    participants: Dr. David Furman
    Dept. Chemistry, University of Cambridge

    Abstract

    Zoom Link: https://weizmann.zoom.us/j/97142508810?pwd=S2Voc3BMYnh6RmFTYUxLbUFjQXRGZz09 Until recently, computational studies of chemical reactivity were exclusively dealt with using quantum mechanical approaches, which severely limited the system's size and accessible time scales for simulation. To bypass the need to solve Schrodinger's equation, and facilitate large-scale simulations for up to millions of atoms, both accurate and efficient models of the chemical bond have to be constructed. I will present recent advances in the field of modeling chemical reactions in large-scale, complex systems (i.e. "dirty chemistry"), with a particular focus on ReaxFF reactive molecular dynamics. Prominent applications from recent years will be highlighted, including: (a) discovery of the underlying operation principles of a novel laser-based mass-spectrometry technique, and (b) prediction of the surprising chemistry that leads to the formation of several key precursors to biomolecules of life upon the collapse of a "primordial bubble". Finally, I will present a new ReaxFF formulation that opens exciting new avenues for orders of magnitude more accurate simulations for long time scales.
  • seminar
    Date:
    31 January
    2021
    Sunday
    Hours:
    11:00
    -
    12:00

    Live imaging of chromatin distribution reveals novel principles of nuclear architecture and chromatin compartmentalization”.

    participants: Prof. Talila Volk
    Dept. Molecular Genetics, WIS

    Abstract

    Zoom Link: https://weizmann.zoom.us/j/91657907719?pwd=M2F2WlRKWGRuUHlxN0tNWFhZVUVzZz09 The genetic material of live organisms is packed and stored within the nucleus. It contains DNA wrapped around the nucleosomes, which then organized into chromatin fibers that partition into distinct compartments, which eventually fill the entire nucleus. Chromatin three dimensional topology is essential for proper accessibility of transcription factors, which control tissue-specific gene expression programs. Whereas chromatin partition into specific domains has been described in cells in culture conditions, information regarding chromatin 3 dimensional distribution in tissues within live organisms is still missing. We have imaged the chromatin in muscle fibers of live, intact Drosophila larvae, and revealed its 3 dimensional structure. Our results demonstrate novel 3 dimensional architecture of the chromatin which is evolutionary conserved, and has important implications on the regulation of gene expression.
  • seminar
    Date:
    28 January
    2021
    Thursday
    Hours:
    09:30
    -
    10:30

    “Low-field MRI: new perspectives”

    participants: Prof. Najat Salameh

    Abstract

    Zoom: Link: https://weizmann.zoom.us/j/98957854014?pwd=ZTEyazd6cThxUE90L3ZJbkdkbkFWQT09 passcode: 159170 Magnetic Resonance Imaging (MRI) is a non-ionizing, non-invasive imaging modality that has become key in modern medicine. Its high value resides in a broad range of soft tissue contrasts or biomarkers that can be tuned to enable the identification and follow-up of many pathophysiological or metabolic processes. Such developments were made possible thanks to almost forty years of hardware and software development, yet access to MRI nowadays remains exclusive, bound to radiology suites in hospitals, and restricted to less than half of the world population. This limited accessibility is mostly due to its one-fits-all design and its prerequisites for intense magnetic field strength that impact cost, siting infrastructure, and clinical compatibility. One way to improve accessibility in MRI is to lower the magnetic field strength that will naturally influence cost, siting, and compatibility. Further, lowering the field strength can translate in smaller footprint designs which geometry and contrast could purposely be tuned to certain targeted applications. Indeed, relaxation mechanisms are known to change with the surrounding magnetic field, with larger T1 dispersion at low field that have for the most part been unexplored. Although very promising, many challenges arise linked to the lower intrinsic nuclear spin polarization inherent to low field technologies, calling for original and innovative approaches to reach clinical relevance. During this seminar, Prof. Najat Salameh will describe those challenges and possible solutions by presenting the current landscape of low field imaging and recent progress made at the Center for Adaptable MRI Technology, Basel University.
  • seminar
    Date:
    26 January
    2021
    Tuesday
    Hours:
    11:00

    Marine electrical imaging reveals novel freshwater transport mechanism in Hawaiʻi

    participants: Eric Attias
    Hawaiʻi Institute of Geophysics and Planetology University of Hawaiʻi

    Abstract

    Conventional hydrogeologic models employed to compute ocean island sustainable yields and aquifer storage neglect the nearshore and onshore submarine environment’s complexity. However, the onshore aquifer at the island of Hawaiʻi exhibits a significant volumetric discrepancy between high-elevation freshwater recharge and coastal discharge. This study presents a novel transport mechanism of freshwater moving from onshore to onshore via a multilayer formation of water-saturated layered basalts with interbedded low-permeability layers of ash/soil, as revealed by marine-controlled source electromagnetic (CSEM) imaging. We propose that this newly discovered transport mechanism of fresh water may be the governing mechanism in other volcanic islands. Additionally, our water column CSEM imaging detects multiple vertical freshwater plumes extending from the seafloor to the ocean surface. These findings provide valuable information to elucidate hydrogeologic and oceanographic rocesses affecting biogeochemical cycles in coastal waters worldwide.
  • seminar
    Date:
    19 January
    2021
    Tuesday
    Hours:
    18:00
    -
    19:00

    New perspectives on interlayer excitons in two-dimensional heterostructures

    participants: Dr. Ouri Karni

    Abstract

    Zoom: https://weizmann.zoom.us/j/96278790117?pwd=T1ZjaHlxQjlEQkFIbE12UDJCazNwZz09 Two-dimensional layered (van-der-Waals) heterostructures, made by stacking different monolayers of semiconducting transition-metal dichalcogenides, have been drawing much attention as versatile platforms for studying fundamental solid-state phenomena and for designing opto-electronic devices. Interlayer excitons, electron-hole pairs that bind to each other across the interlayer spacing in these heterostructures, hold promise as key tools for probing the interlayer interface structure, and for exploring many-body interactions(1). With long lifetimes, spin polarization, and electric tunability, interlayer excitons are also promising as flexible information carriers(2, 3). However, they were mostly studied through the scope of their visible light emission, missing essential properties such as their momentum-space image or their absorption strength, necessary for rigorous study of their many-body interactions and potential applications. In this talk I will present our recent studies aimed at measuring such unknown interlayer exciton properties and their dependence on the heterostructure. I will show a new interlayer exciton in WSe2/MoS2 heterostructures which we discovered based on its light emission in infra-red wavelengths, rather than in the visible range(4). I will demonstrate its properties as inferred from its optical interrogation. Then, I will present the quantitative measurement of the elusive optical absorption spectrum of interlayer excitons using electric-field modulation spectroscopy, essential for coherent coupling of light to those excitons(5). Finally, I will reveal how time- and angle-resolved photoemission spectroscopy is used to image the interlayer exciton in momentum-space, yielding its size and binding energy, so far inaccessible through optics(5).
  • seminar
    Date:
    19 January
    2021
    Tuesday
    Hours:
    11:00

    In situ identification of 48-56.0 million old proteins in chert with unusually high stiffness

    participants: Filipe Natalio
    Scientific Archaeology Unit Weizmann Institute of Science
  • seminar
    Date:
    17 January
    2021
    Sunday
    Hours:
    11:00
    -
    12:00

    Quantitative Prediction of Nanoparticle Assembly for Personalized Nanomedicine

    participants: Prof. Yosi Shamay
    Dept Biomedical Engineering, Technion

    Abstract

    Zoom Link: https://weizmann.zoom.us/j/92447973616?pwd=UWJkRWdraGFVQjdPb3ByWis1bDk2Zz09 Development of targeted nanoparticle for personalized cancer therapeutics often requires complex synthetic schemes involving both supramolecular self-assembly and multiple chemical modifications. These processes are generally difficult to predict, execute, and control. I will describe a new method to accurately and quantitatively predict self-assembly of kinase inhibitors drug molecules into nanoparticles based on their molecular structures. The drugs assemble with the aid of new kind of excipient comprised of highly conjugated sulfated molecule into particles with ultra-high drug loadings of up to 90%. Using quantitative structure-nanoparticle assembly prediction (QSNAP) calculations and machine learning, a new algorithm was developed as highly predictive indicators of both nano-self assembly and nanoparticle size with unprecedented accuracy.
  • seminar
    Date:
    14 January
    2021
    Thursday
    Hours:
    09:30
    -
    10:30

    ‘Identification of Dynamic Components in the Liquid-Liquid Phase Separation of CPEB4 by EPR Spectroscopy’

    participants: Dr. Manas Seal
    Dept Chemical and Biological Physics, WIS

    Abstract

    Link: https://weizmann.zoom.us/j/96046369379?pwd=emp0U0wwcmpNQlhsMisrNmp0bjRDdz09 Passcode: 693143 The molecular mechanisms and associated structures and dynamics of liquid-liquid phase separation (LLPS) proteins that form membrane-less organelles in cells have attracted considerable interest in recent years. EPR spectroscopy along with site directed spin labelling (SDSL) using nitroxide spin labels is a well-established technique to study dynamics of proteins. In this seminar I will discuss the dynamic properties of the spin labelled low complexity N-terminal domain of cytoplasmic polyadenylation element binding-4 protein (CPEB4NTD) in its LLPS and non-LLPS states. We found the coexistence of three CPEB4NTD populations with distinct spin label rotational correlation times before and after LLPS. We identified population I as the predominant protein species in the dilute phase, with fast motions that agree with expected dynamic properties of monomeric CPEB4NTD. We assigned population III to a compact ensemble that undergo slow motions, and population II to a looser ensemble experiencing intermediate motions. LLPS, which took place with increasing temperature is associated with increased population of II at the expense of III, while population I remains constant. At the end based on these findings, I will present a three-component equilibrium model that postulates the existence of LLPS-competent CPEB4NTD species (II and III) prior to macroscopic phase separation.
  • seminar
    Date:
    6 January
    2021
    Wednesday
    Hours:
    14:30
    -
    15:30

    M.Sc thesis defense: Band gaps of crystalline solids from a Wannier-localized, optimally tuned screened range-separated hybrid functional

    participants: Guy Ohad

    Abstract

    https://weizmann.zoom.us/j/93597285944?pwd=S0FJdHJ6eVpFTGJ3dHJHa3c1amJyUT09 Abstract: A long-standing challenge within density functional theory (DFT) is the development of functionals that accurately predict the band gap and electronic structure of crystalline solids. A promising candidate for this task is the screened range-separated hybrid (SRSH) functional, which has been shown to yield accurate results for finite systems when one of the parameters in the functional, the range-separation parameter, is selected a priori. In the bulk limit, however, this parameter cannot be selected non-empirically based on the ionization potential theorem, owing to the delocalized electronic orbitals. Recently, we have developed a new method for the non-empirical tuning of the range-separation parameter, that is based on the removal of an electron in a state that corresponds to a Wannier function. We have applied the method to a set of systems ranging from narrow band gap semiconductors to large band gap insulators, obtaining fundamental band gaps in excellent agreement with experiment.
  • seminar
    Date:
    5 January
    2021
    Tuesday
    Hours:
    11:00

    Nanoinclusions in diamonds: trapped fluids and solid molecular N2 and CO2

    participants: Oded Navon
    Institute of Earth Sciences The Hebrew University of Jerusalem

    Abstract

    Diamonds are perfect boxes for delivering samples of fluids and volatile species from the mantle to the surface. While mineral inclusions are often a few >30 micrometer in size and allow easy analysis, fluid inclusions are mostly <1 micrometer. Still, careful analysis allowed us to define carbonatitic, saline and silicic melts in the inclusions. Recently, transmission electron microscopy allowed us to look into even smaller inclusions, 10-30 nm in size where we found solid molecular nitrogen and solid molecular CO2. Contrary to the melts that are low volume mantle melts, the N2 and CO2 are interpreted as exsolutions of N and O atoms that were taken as single atoms in the diamond matrix and later migrated and joined to form tiny octahedrons full of N2 and CO2. Geologically, the solids are an oddity of nature, but the melts can play an important roll in the extraction of trace elements from the mantle and into the crust.
  • seminar
    Date:
    3 January
    2021
    Sunday
    Hours:
    11:00
    -
    12:00

    PCR-free sensing of Covid-19, metastatic mRNA biomarkers and towards single-cell proteomic

    participants: Prof. Amit Meller
    Department of Biomedical Engineering, Technion

    Abstract

    Zoom Link: https://weizmann.zoom.us/j/98521602060?pwd=T1B1TEJqcXEwUW50QzBEaXd3RS9XZz09 SARS-CoV-2 outbreak of the coronavirus disease (COVID-19) has underlined the acute need for extremely sensitive, accurate, fast, point-of-care mRNA quantification sensors. Here I will show how solid-state nanopores can be used to digitally count target mRNA molecules from both biological and clinical Covid-19 samples surpassing the accuracy and gold-standard” RT-qPCR. Additionally, we applied our method for the sensing of cancer metastatic mRNA biomarkers MACC1 and S100A4 at early stage of the diseases, suggesting a potential use of the method in early precision medicine diagnostics. Moving beyond nucleic acids, I will discuss our on-going efforts towards the use of plasmonic nanopore devices for the single protein molecules identification based on partial labelling of only two or three amino acids. This research opens up vast directions for single-cell proteomics of even rarely expressed proteins.
  • seminar
    Date:
    31 December
    2020
    Thursday
    Hours:
    09:30
    -
    10:30

    1H LF NMR Sensor Application for Monitoring of PUFA-rich Healthy Food Autoxidation

    participants: Prof. Zeev Wiesman
    Department of Biotechnology Engineering Ben Gurion University of the Negev

    Abstract

    Abstract: The present seminar will review our work in 1H LF NMR energy relaxation time technology and its application in chemical and morphological characterization and monitoring of oxidation of polyunsaturated fatty acids (PUFA) found in many important commercial products such as edible oils, foods, and biological systems. PUFA’s aggregates are related simultaneously with material’s functionality and degradation. The multiple double bonds and allylic carbons characteristics of the PUFA’s molecular structure are responsible for its oxidation susceptibility and can result in the degrade of the product’s functionality and formation of toxic substances. Wherein individual PUFA molecules have specific structures their material functionality and stability against oxidation are strongly depended on their aggregate structures such as in oils or within aqueous emulsions and specific arrangements within these structures with other components such as antioxidants is an important material parameter. The oxidation degree of PUFA’s rich materials can be measured via different methods such as volumetric, spectroscopic and chromatographic technologies. The traditional technologies based on titrimetric techniques have many drawbacks. These methods need strict time regimes during individual stages of analyzes, control of the intensity of the agitation and control of reaction components including light and atmospheric oxygen exposure. Other disadvantage of these traditional methodologies is the requirement of a large amount of solvents, being environmental unfriendly. In order to overcome the disadvantages of the traditional technologies used to monitor oxidation we are suggesting the use 1H LF NMR relaxation. This technology does not require organic solvents, complex samples preparation and the sample is preserved after analysis. The 1H LF NMR generates 2D T1 (spin-lattice) vs. T2 (spin-spin) energy relaxation time domain that is able together with self-diffusion test to characterize chemical and morphologically complex aggregate materials such as PUFA in liquid or solid assembly or in presence of interfacial forces of water. In addition, these spectra can efficiently monitor oxidation and assess antioxidants efficacy. We demonstrate the work we have done to date on the 1H LF NMR data processing optimization and the application of this technology in the characterization and monitoring of oxidation on oils on fatty acids saturated, monounsaturated and polyunsaturated. This sensor application is of relevant contributions for diverse fields such as food industries, pharmaceuticals, cosmetics and biofuels. The seminar is divided into three parts: a) Optimization of the ILT data processing technology of 1H LF NMR energy relaxation time. This study showed the efficiency of the regularization parameters for data reconstruction, and a relative high accuracy of the primal dual convex objectives (PDCO) solutions in comparison to the graphic results of real data. b) Developing of intelligent NMR relaxation sensor applications of fatty acids (FA) with saturated chains, MUFA and PUFA-rich oils for their chemical and physical/morphological characterization and monitoring of their autoxidation. Detailed fingerprinting chemical and morphological maps were generated for saturated FAs, MUFAs, PUFAs and their oxidation polymerized final products. It was possible to propose peak assignments to the various spin-lattice (T1) and spin –spin (T2) energy relaxation time proton populations (TD) based on the molecular segmental motions of the different fatty acids chemical and structural segments (e.g., glycerol; double bonds; aliphatic chains; and tails) to generate an explicatory dictionary of T1 and T2 values with chemical and physical/morphological structures and their changes due to oxidation. c) Developing of intelligent 1H LF NMR energy relaxation time domain sensor application for PUFA-rich oil-in-water emulsions characterization and monitoring autoxidation. Emulsions based on linseeds, very rich in α-linolenic acid PUFA (18:3) and structural oleosin protein and other emulsification agents naturally producing nano-scale oxidation stable oil bodies, were formed from linseed in water. The linseed emulsions enriched with PUFA-rich fish oil were analyzed under thermal oxidation conditions, using 1H LF NMR T1-T2 energy relaxation time reconstruction for determining the oil bodies composition and structure and oxidative stability.
  • seminar
    Date:
    27 December
    2020
    Sunday
    Hours:
    11:00

    A coupled Eulerian-Lagrangian analysis of the large-scale tropical atmospheric circulation and its implication for climate change

    participants: Dana Reiter
    Department of Earth and Planetary Sciences Weizmann Institute of Science

    Abstract

    The Hadley circulation is a key element of the climate system. It is traditionally defined as the zonally averaged meridional circulation in the tropics, therefore treated as a zonally symmetric phenomenon. However, differences in temperature between land and sea cause zonal asymmetries on Earth, dramatically affecting the circulation. This longitudinal dependence of the meridional circulation evokes questions about where and when the actual large scale tropical circulation occurs. Here, we look into the connection between the longitudinally dependent meridional circulation, and the actual large scale transport of air in the tropics using a coupled Eulerian and Lagrangian approach. Decomposing the velocity field into rotational and divergent components, we identify how each component affects the actual circulation. We propose an alternative definition for the circulation, that describes the actual path of air parcels in the tropics, as a tropical atmospheric conveyor belt. We further investigate this definition, analyzing the circulation under climate change and its effect on precipitation changes. We show that in order to predict future climate, the regionality and three-dimensionality of the large-scale tropical circulation must be taken into account. We find that the changes in the circulation vary significantly over longitude, and are overlooked when analyzing the zonally averaged meridional circulation. The circulation is strengthening and expanding in the center of the Pacific, a region where the circulation barely existed in past. On the other hand, the circulation is weakening in the Indo-Pacific region, where it was the most significant in the past. These differences appear as a shift in the region of ascent of the conveyor belt, that is revealed when analyzing the decomposed vertical wind. The pattern of weakening of the ascent in the Indo-Pacific and strengthening in the center of the Pacific explains the projected changes in precipitation. The Indo-Pacific region is drying, while the precipitation in the center of the Pacific is intensifying.
  • seminar
    Date:
    22 December
    2020
    Tuesday
    Hours:
    11:00

    Reducing the Uncertainty of Extreme Weather and Climate Predictions

    Location: Sussman Family Building for Environmental Sciences
    participants: Assaf Hochman
    Department of Tropospheric Research, Institute of Meteorology and Climate Research Karlsruhe Institute of Technology, Eggenstein - Leopoldshafen

    Abstract

    Weather and climate extremes such as cold spells, heat waves, heavy precipitation or windstorms have long been considered challenging to adequately predict a few days in advance. Even at shorter time scales, it is sometimes difficult to estimate the magnitude and impact area accurately. Therefore, they have been selected as one of the grand challenges by the World Climate Research Program. Several studies suggest that extreme temperatures or heavy precipitation events may become more frequent and more intense with climate change, making this topic even more pertinent. The ability to predict the development of any dynamical system (a system that evolves in time), depends on: 1) its persistence, meaning that a persistent system will be easier to predict and 2) the number of options the system can develop into/from, meaning that systems with a small number of options will be easier to predict. Recent advances in dynamical systems theory allow to efficiently compute these metrics from model data. Our earlier findings show that the dynamical systems metrics can serve as an extremely informative qualitative method for evaluating the predictability and dynamics of synoptic systems over the Eastern Mediterranean. The talk will discuss this novel dynamic approach and its recent applications in extreme weather forecasting, as well as in climate model projections over the Eastern Mediterranean.
  • seminar
    Date:
    20 December
    2020
    Sunday
    Hours:
    11:00
    -
    12:00

    Zoom Lecture: The extracellular matrix in bacterial biofilms. From peptides and proteins to whole biofilms

    participants: Dr. Liraz Chai
    Institute of Chemistry, HUJI

    Abstract

    Zoom Link: https://weizmann.zoom.us/j/98510631069?pwd=QzVFbzNxMHZETWwrM0xjbVBmV3FDdz09 Biofilms are aggregates of cells that form on surfaces and interfaces. A major characteristic of biofilms is the self-secretion of an extracellular matrix, that is composed of biopolymers, mainly proteins, polysaccharides, and nucleic acids. Using a variety of biophysical methods, we study the basic interactions between matrix components that lead to the formation of a 3D network. In this talk I will describe our recent findings, going all the way from peptides through full-length proteins to whole biofilms.
  • seminar
    Date:
    17 December
    2020
    Thursday
    Hours:
    09:30
    -
    10:30

    The hyperpolarized brain: What can we add to cerebral metabolism with hyperpolarized MR probes?

    participants: Dr. Mor Mishkovsky
    Laboratory of Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne (EPFL)
  • seminar
    Date:
    8 December
    2020
    Tuesday
    Hours:
    10:00

    Seismic sensing with optical fibers – principles and applications

    participants: Ariel Lellouch
    Stanford University

    Abstract

    During the last decade, seismic sensing with optical fibers has become a reality. By analyzing the effect of seismic deformation on the fiber’s optical response, state-of-the-art Distributed Acoustic Sensing (DAS) now offers a 1-meter sensor resolution for tens of kilometers of fiber. In other words, a single DAS system can record up to 40,000 data channels at once – two orders of magnitude more than the entire earthquake-monitoring seismic network in Israel. In this talk, I will first introduce the underlying operating principles of DAS acquisition. These measurements are very different from conventional seismic sensors and need to be analyzed accordingly. Subsequently, most of the talk will revolve around DAS applications in various scenarios. We utilize the ambient seismic field, recorded on a standard telecommunication fiber deployed around the Stanford campus, to analyze subsurface properties. The same fiber can also be used to measure changes in traffic patterns due to the COVID-19 lockdown. With downhole DAS arrays deployed in deep vertical wells, we can study previously undetected low-magnitude earthquakes. Finally, we utilize DAS data recorded inside an unconventional gas field to unveil reservoir properties with unprecedented resolution.
  • seminar
    Date:
    6 December
    2020
    Sunday
    Hours:
    11:00
    -
    12:00

    Zoom lecture: Nanoscale Optical Imaging Of Individual And Densely Packed Microgel Colloids

    participants: Prof. Frank Scheffold
    Department of Physics, University of Fribourg

    Abstract

    Zoom Link: https://weizmann.zoom.us/j/95267372668?pwd=dEhvRlA3SGtvVTQ1QnVmZ3JJdTZEQT09 Thermosensitive microgels are widely studied hybrid systems combining properties of polymers and colloidal particles uniquely. This study explores the frequency-dependent linear viscoelastic properties of dense suspensions of micron-sized microgels in conjunction with an analysis of the local particle structure and morphology-based on superresolution microscopy. By identifying the dominating mechanisms that control the elastic and dissipative response, we can explain these widely studied soft particle assemblies' rheology. Interestingly, our results suggest that the polymer brush-like corona's lubrification reduces friction between the microgel contacts.
  • seminar
    Date:
    2 December
    2020
    Wednesday
    Hours:
    15:00
    -
    16:00

    The impact of non-canonical DNA structures on protein-DNA interactions

    participants: Dr. Ariel Afek
    Duke Center for Genomic and Computational Biology Duke University NC, USA
  • seminar
    Date:
    24 November
    2020
    Tuesday
    Hours:
    11:00

    What caused megadroughts in North and South America?

    Location: Sussman Family Building for Environmental Sciences
    participants: Nathan Steiger
    Hebrew University of Jerusalem
  • seminar
    Date:
    23 November
    2020
    Monday
    Hours:
    16:00

    Putting Proteins Together: Reconstitution of Mechanisms Driving Cilia Motility and Fertilization

    participants: Dr. Iris Grossman-Haham
    Dept. of Cellular and Molecular Pharmacology University of California, San Francisco
  • seminar
    Date:
    23 November
    2020
    Monday
    Hours:
    14:00
    -
    15:30

    Zoom: MSc thesis defense: Guided CdTe Nanowires: Synthesis, Structure, Optoelectronics and Bandgap Narrowing

    participants: Yarden Daniel
    Supervision of Prof. Ernesto Joselevich

    Abstract

    https://weizmann.zoom.us/j/99592122461?pwd=MjM4ZDN0ZDFVeGZOYkdqQi9CUy9uUT09 Semiconductor nanowires (NWs) are quasi 1D nanostructures, exhibiting distinctive physical properties suitable for efficient bottom-up design of nanodevices. A challenging limiting step of their integration into planar functional systems is the difficulty to align them on horizontal surfaces. One simple and elegant way to avoid post growth assembly of NWs is to grow them horizontally in the first place. Over the past decade, our group has established the surface guided growth of horizontal semiconductor NWs aligned by crystalline substrates with controlled crystallographic orientations, directions and position. As the NWs are comprised of different semiconductors, they are optically active is different spectral regimes including the UV and visible range. However, optical activity in the pivotal infrared (IR) regime is not yet exhibited for guided NWs and a systematic exploration of it can pave the way for effective devices for telecommunication and night vision technologies. CdTe, a narrow band-gap II-VI semiconductor (~1.5 eV), is an attractive candidate owing to its promising optical and electrical properties, making it an attractive material for solar cells and near IR (NIR) photodetectors. Its alloys with mercury, known as MCT (HgxCd1-xTe) are already central components of efficient IR photodetectors due to continuous bandgap narrowing with growing percentage of mercury. In this work, we present the vapor-liquid-solid (VLS) growth and self-alignment of surface guided CdTe NWs with a wurtzite crystal structure on flat and faceted sapphire substrate (α-Al2O3). The NWs were integrated into fast IR photodetectors showing high on/off ratio of up to ~104 and, to the best of our knowledge, the shortest response times (~100 ms) to IR irradiation with respect to other CdTe based photodetectors. Attempts to create HgxCd1-xTe through cation exchange show initial conversion (~2%) of the crystal, though with significant bandgap narrowing of ~ 55 meV. These findings pave the way for simple and elegant fabrication of CdTe NWs’ based NIR nano-photodetectors, which can be expended to a wide range of Mid-IR and Far-IR photodetectors with small size through bandgap engineering.
  • seminar
    Date:
    22 November
    2020
    Sunday
    Hours:
    11:00
    -
    12:00

    Zoom Lecture: Aggregation in intrinsically disordered proteins and associative polymers"

    participants: Prof. Yitzhak Rabin, BIU
    Bar Ilan University

    Abstract

    We model intrinsically disordered proteins (IDPs) as associative polymers (APs). We study the kinetics of gelation in solutions of amphiphilic polymers that contain strongly associating stickers connected by long soluble chain segments. We explore the relation between primary sequence and droplet morphology in APs in poor solvent. We find that gelation of APs can be suppressed by grafting them to surfaces, a possible way to control aggregation of IDPs. Zoom Link: https://weizmann.zoom.us/j/99868477151?pwd=U3hFTWhjZ05nT3Ryd1ZHOXJ6Z3Y1Zz09
  • seminar
    Date:
    17 November
    2020
    Tuesday
    Hours:
    16:15

    Insights on Processes in Polar Supercooled Cloud Lifecycles from Observations and Cloud Resolving Model Simulations

    participants: Israel Silber
    Department of Meteorology and Atmospheric Science Pennsylvania State University

    Abstract

    Supercooled clouds substantially impact polar surface energy budgets but large-scale models often underestimate their occurrence, which motivates accurately establishing metrics of basic processes. A polar stratiform cloud’s lifecycle is determined by a set of complex interactions and feedbacks between different micro-physical and macro-physical processes, some of which are not fully understood or quantified, leading to uncertainty in climate predictions. These polar clouds are commonly presupposed as being turbulent as a result of intense cloud-top longwave radiative cooling, while experiencing desiccation dominated by precipitating ice. In this talk, I examine some of these underlying assumptions and provide applicable guidance for large-scale model evaluation. I first present observations of persistent formation of drizzle drops at cloud temperatures below -25 °C detected over McMurdo Station, Antarctica. These supercooled drizzle observations supported by large-eddy simulations (LES) used to examine the cloud’s formation and evolution under initially stable, nonturbulent conditions, suggest that drizzle can be common over polar regions and serve as the main cloud moisture sink even well below the freezing temperature. A persistent nonturbulent cloud state suggested by the LES leads to the examination of nonturbulent cloud occurrence in observational datasets from Arctic and Antarctic ground-based sites. Such stable, nonturbulent conditions, surmised to preferentially occur early in cloud lifecycles, are estimated to prevail in a quarter of cloud occurrences over these polar sites. I use LES sensitivity tests to examine how short to intermediate period gravity waves, which are supported by such stable conditions, may catalyze turbulence formation when aerosol particles available for activation are sufficiently small. The observational datasets are also utilized to examine ice precipitation processes, and show that the vast majority of polar supercooled clouds are at least weakly precipitating ice at the cloud base even when they are not seeded from above, consistent with commonly observed supercooled cloud longevity. These results indicate that supercooled cloud layers are a sustained source of ice precipitation, and suggest that ground-based statistics offer valuable guidance for large-scale models. Finally, as an example of how some of these observational and modeling results may be used to evaluate the representations of polar clouds in large-scale models, I briefly describe using the GISS E3 climate model in single-column model (SCM) mode applied to the supercooled drizzle case study.
  • seminar
    Date:
    14 October
    2020
    Wednesday
    Hours:
    15:00
    -
    16:00

    Zoom Ph.D defense: “A First Principles Perspective on Stability, Dynamics, and Defect Chemistry in Halide Perovskites”

    participants: Ayala Cohen
    Dept. Materials and Interfaces, under the supervision of Prof. Leeor Kronik

    Abstract

    Zoom Link: https://weizmann.zoom.us/j/93181739182?pwd=YTd0K1drTmZSdnB0bElFZVI4K0NXdz09
  • seminar
    Date:
    10 September
    2020
    Thursday
    Hours:
    09:00

    Why are there colors in the ocean?

    participants: Derya Akkaynak
    Harbor Branch Oceanographic Institution Florida Atlantic University
  • seminar
    Date:
    23 August
    2020
    Sunday
    Hours:
    14:00
    -
    15:00

    Structure Sensitivity in Catalysis

    participants: Dr. Charlotte Vogt
    Niels Stensen Post-Doctoral Fellow at HUJI and the Weizmann Institute for Science

    Abstract

    Some fundamental concepts of catalysis are as of yet not fully explained but are of paramount importance for the development of improved supported metal catalysts for chemical industries and environmental remediation. Structure (in)sensitivity is such a fundamental physical concept in catalysis, which relates the rate of a catalytic reaction per unit surface area to the size of a nanoparticle. If this rate per unit surface area changes with catalyst particle size, a reaction is termed structure sensitive. Conversely if it does not - a reaction is termed structure insensitive. Historically, many fundamental physical concepts explaining the behavior of metal nanoparticular catalysts have been formulated by studying single crystal facets with surface science techniques which has left a considerable gap in our basic knowledge of catalysts at work. By using and developing state-of-the-art operando (micro)spectroscopic techniques, inter alia operando high-temperature high-pressure FT-IR, in-situ high-resolution STEM, and quick-X-ray absorption spectroscopy (quick-XAS) with millisecond time resolution, over the last few years I have been exploring the fundamental physical concepts behind fundamental structure-activity relationships of catalytic reactions by studying non-model catalysts at work. For example, by applying these methods to study a structure sensitive reaction (carbon dioxide hydrogenation) to a structure insensitive one (ethene hydrogenation) we show that the same geometric and electronic effects that we find to explain structure sensitivity make it unlikely for structure insensitivity to exist (while we do observe it empirically). However, interestingly, in the case of the structure insensitive ethene hydrogenation reaction, such size-dependent nanoparticle restructuring effects as the decrease of the reversibility of adsorbate-induced restructuring and the increase of carbon diffusion with increasing particle size are observed by quick-XAS (see Figure 1). While for the structure sensitive CO2 hydrogenation no such perturbation was observed. We further show that this particle size dependent restructuring induced by ethene hydrogenation can make a structure sensitive reaction structure insensitive. Hence, we may postulate that structure insensitive reactions should rather be termed apparently structure insensitive, which changes our fundamental understanding of the age-old empirical observation of structure insensitivity.
  • seminar
    Date:
    14 June
    2020
    Sunday
    Hours:
    11:00
    -
    12:00

    Zoom Lecture: Designing In Situ Architectures in 3D Cell-Laden Hydrogels

    participants: Prof. Dror Seliktar
    Faculty of Biomedical Engineering, Technion Institute of Technology

    Abstract

    One of the key advantages in using light-sensitive hydrogel biomaterials is the ability to spatially structure cell scaffolds with three-dimensional mechanical cues that guide cellular morphogenesis. However, this has proven difficult because of the high toxicity associated with the cross-linking interactions. To overcome this challenge, we developed a new paradigm in micro-patterning using a reversible temperature-induced phase transition from liquid to solid vis-à-vis lower critical solubility temperature (LCST). This facilitates reduced transport kinetics of the polymer chains in solution, thus enabling crosslinking that is truly compatible with cell-laden 3D culture. Cellularized constructs were patterned to reveal a difference in morphogenesis between chemically crosslinked “stiffer” and physically crosslinked “softer” regions. Emphasizing the importance of mechanical heterogeneity in cellular morphogenesis, the results validate cutting-edge technology that can provide scientists with a robust set of tools for engineering cell and tissue growth in three dimensions.
  • seminar
    Date:
    7 June
    2020
    Sunday
    Hours:
    11:00
    -
    12:00

    Maritime silver trade in the Levant during the Iron Age and its effect on human pollution

    Location: Sussman Family Building for Environmental Sciences
    participants: Yigal Erel
    The Hebrew University of Jerusalem & University of Haifa, Israel
  • seminar
    Date:
    31 May
    2020
    Sunday
    Hours:
    11:00
    -
    12:00

    Life and death in a pinch of salt: chronology, sedimentology, and geobiology of the Messenian Salinity Crisis deposits in the deep Levant Basin

    Location: Sussman Family Building for Environmental Sciences
    participants: Aaron Meilijson
    University of Haifa

    Abstract

    The Messinian Salinity Crisis (MSC; 5.97-5.33 Ma) is considered an extreme environmental event driven by changes in climate and tectonics, which affected global ocean salinity and shaped the biogeochemical composition of the Mediterranean Sea. Yet, after more than 50 years of research, MSC chronology and events remains controversial. Recently drilled offshore wells in the Levant Basin retrieved for the first time a complete sedimentary record of the deep-basin Mediterranean MSC salt deposits and the underlying Pre-Evaporite unit. Analysis of this dataset changes the way these deposits have been perceived since the 1970’s, when they were first penetrated in their uppermost part during DSDP expeditions. Using sedimentology, chemistry, seismic interpretation, biostratigraphy, and astronomical tuning we show that Messinian salt deposition in the Eastern Mediterranean began during stage 1, and not stage 2 of the MSC. In contrast to the present paradigm, salt was deposited synchronously with gypsum deposition in the marginal and intermediate-depth basins. This occurred significantly earlier than the 50 kyr interval coined as the ‘MSC acme event’, ~300 kyr after the crisis began. The one-kilometer-thick lower part of the evaporitic unit is composed of essentially pure halite, except for a thin transitional anhydrite layer at its base. The halite is undisturbed and homogeneous, lacking diverse features apparent in more proximal sections, indicating a deep-sea depositional environment. We find that distinct, meters-thick non-evaporitic intervals interbedded with the halite, previously thought to be clastic layers, are diatomites. While XRD analysis confirms an increase in clastic components in these sediments, they are composed primarily of well-preserved marine and freshwater planktonic diatoms. The occurrence of marine planktonic diatoms in these intervals indicates the input of Atlantic waters into the Mediterranean Basin during the deposition of the massive halite unit. In the second part of this talk I will couple lipid biomarker analysis with faunal and taxonomic evaluation of the diatom assemblages to try and answer the following question: why do we see this extreme abundance of diatoms, but a complete absence of calcareous-shelled forms of life within the MSC salt deposits? This study demonstrates that brine formation, salt precipitation, and faunal extinction occurred at least in part in a deep, non-desiccated basin, with a restricted yet open Mediterranean-Atlantic connection that allowed inflow of oceanic water. A coeval onset of basinal halite and marginal gypsum precipitation calls for a revaluation of global-scale climatic and oceanographic models of the MSC, while substantially altering our understanding of the mechanisms governing the deposition of salt giants.
  • seminar
    Date:
    31 May
    2020
    Sunday
    Hours:
    11:00
    -
    12:00

    Bacterial deposition and attachment to soft surfaces: mitigation, measurements, mechanism and open questions

    participants: Prof. Viatcheslav (Slava) Freger
    Department of Chemical Engineering, Technion

    Abstract

    Zoom Lecture: https://weizmann.zoom.us/j/95418425823 Deposition and attachment are key steps in colonization and fouling of surfaces by bacteria and other microorganisms, undesired in most applications. Soft hydrophilic surfaces are attractive as potential low-fouling coatings, however, deposition on such surfaces open questions regarding microscopic mechanism of attachment and its relation to deposition kinetics, not addressed in the current picture. In the talk, I will highlight our effort to understand deposition and attachment of bacteria and microparticles on low-fouling surfaces and develop appropriate characterization techniques and models.
  • seminar
    Date:
    17 May
    2020
    Sunday
    Hours:
    11:00
    -
    12:00

    Zoom Lecture: The fascinating frictional properties of layered materials: Insights from atomistic modeling

    participants: Prof. Michael Urbakh
    School of Chemistry, Tel Aviv University

    Abstract

    Zoom Lecture: : https://weizmann.zoom.us/j/91487772614 Structural superlubricity may provide a viable route to the reduction of friction and wear. In this talk I will present results of fully atomistic numerical simulations of static and dynamical properties of graphite/hexagonal boron nitride (h-BN) heterojunctions, performed adopting a recently developed inter-layer potential. We found that structural superlubricity at interfaces between graphite and h-BN persists even for the aligned contacts sustaining external loads. A negative friction coefficient, where friction is reduced upon increasing normal load, is predicted. It is demonstrated that further control over the physical properties of 2D layered materials can be gained via tuning the aspect-ratio of nanoribbons. The sliding dynamics of the edge-pulled nanoribbons is found to be determined by the interplay between in-plane ribbon elasticity and interfacial lattice mismatch. Our results are expected to be of general nature and should be applicable to other van der Waals heterostructures.
  • seminar
    Date:
    3 May
    2020
    Sunday
    Hours:
    11:00
    -
    12:00

    Mechanical sensing in cell fate decision making: from nuclei to embryos"

    participants: Dr. Amnon Buxboim
    The Alexander Silberman Institute of Life Sciences, Hebrew University

    Abstract

    Zoom lecture https://weizmann.zoom.us/j/96236417861 Mechanical sensing in cell fate decision making: from nuclei to embryos. Cells constantly probe extracellular mechanics by assessing the resistance to applied forces via adhesion, cytoskeletal, and nuclear mechanotransducers and the emerging signals direct cell-fate decisions during development and regenerative processes. The conversion of forces into biochemical cues depends on the rheological properties of subcellular elements and multicellular systems, which have been optimized during metazoan evolution. In my talk, I will present micropipette nuclear aspiration measurements of cells that express or lack the expression of different combinations of A- and B-type lamin proteins. By evaluating the mechanical contributions of assembled and disassembled lamin filamentous, and the interactions with stabilized condensed chromatin, we propose a nuclear viscoelastic model that supports a shockabsorbing response for protecting the genetic material from instantaneousimpact and a viscoelastic regime that permits slow dissipation under constant load. In a living organism, the genetic material is also protected by a physical decoupling mechanisms of the cell nucleus, which is affected by nuclear stiffening during ageing. If time permits, I will also discuss the development in situ rheological systems for performing non-invasive measurements of oocytes and embryos during preimplantation development. We combine rheology of the whole oocyte and the internal cytoplasmic mass. These stress-strain relationships are correlated with oocyte fertilization capacity, where negative outcome is underlined by impaired cytoskeletal organization.
  • seminar
    Date:
    30 April
    2020
    Thursday
    Hours:
    11:00

    Chemical and Biological Physics Guest Seminar

    Location: Perlman Chemical Sciences Building
    participants: Professor Masahiro Yamashita
    Tohoku University

    Abstract

    Spintronics is a key technology in the 21st century. Although bulk magnets composed of transition metals are normally used, in our study, we use Single-Molecule Magnets (SMMs) to overcome “Moore`s Limitation”. For realizing the single-molecule memory device by using spin-polarized STM, we have succeeded to write and read the spin orientations of TbPc2 as up and down, respectively. For realizing the quantum computer, the spin Qubits and coherence at room temperature are very important. For this purpose, we synthesized monomer-Porphyrin V(IV) complex (0D) and MOF-Porphyrin V(IV) complexes (3D). The 3D complex shows Rabi nutation even at room temperature due to the rigid lattice of MOF. We have succceded the encapsulation of Metal Fulleren SMMs into SWCNT, which is new spintronics.
  • seminar
    Date:
    27 April
    2020
    Monday
    Hours:
    11:00
    -
    12:15

    2020 G.M.J. SCHMIDT MEMORIAL LECTURE - Plasmonic Cavities: What are they and How they teach us quantum optics

    participants: Prof. Gilad Haran
  • seminar
    Date:
    26 April
    2020
    Sunday
    Hours:
    14:00
    -
    15:00

    Chemical and Biological Physics Special Seminar

    Location: Perlman Chemical Sciences Building
    participants: Prof. Masahiro Yamashita
    Tohoku University, Japan

    Abstract

    Spintronics is a key technology in the 21st century. Although bulk magnets composed of transition metals are normally used, in our study, we use Single-Molecule Magnets (SMMs) to overcome “Moore`s Limitation”. For realizing the single-molecule memory device by using spin-polarized STM, we have succeeded to write and read the spin orientations of TbPc2 as up and down, respectively. For realizing the quantum computer, the spin Qubits and coherence at room temperature are very important. For this purpose, we synthesized monomer-Porphyrin V(IV) complex (0D) and MOF-Porphyrin V(IV) complexes (3D). The 3D complex shows Rabi nutation even at room temperature due to the rigid lattice of MOF. We have succceded the encapsulation of Metal Fulleren SMMs into SWCNT, which is new spintronics
  • seminar
    Date:
    5 April
    2020
    Sunday
    Hours:
    11:00

    TBA

    Location: Sussman Family Building for Environmental Sciences
    participants: Colin Price
  • seminar
    Date:
    2 April
    2020
    Thursday
    Hours:
    14:00

    Ben May Center for Chemical Theory and Computation, lecture

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Kurt Binder
    Johannes Gutenberg Universitaet Mainz, Germany

    Abstract

    Basic concepts related to interfaces between coexisting phases in thermal equilibrium can be traced back to the classic work of Gibbs, van der Waals, Landau, Cahn and Hilliard. Yet, these concepts still pose problems that are not well understood. The concept of an (intrinsic) interfacial profile is a key one for computing the interfacial free energy, but turns out to be ill-defined due to the inherent difficulties in separating the intrinsic profile from capillary wave broadening. A related problem is the failure of the idea of a free energy of homogeneous states inside the two-phase coexistence region in systems with short range forces. These difficulties can be avoided by computer simulation methods. Yet, the latter suffer from subtle finite size effects, which will be demonstrated in this lecture by extensive Monte Carlo simulations for 2D and 3D Ising models. It will be shown that one can understand them in terms of fluctuation phenomena associated with interfaces, such as translational degrees of freedoms of domains and "domain breathing". Correcting for these finite size effects, one can obtain accurate estimates for interfacial free energies, also for off-lattice models of fluids. Finally, it will be demonstrated that these concepts can be carried over to the study of curved interfaces (of droplets or bubbles, respectively), allowing the estimation of Tolman's length.
  • seminar
    Date:
    29 March
    2020
    Sunday
    Hours:
    11:00

    TBA

    Location: Sussman Family Building for Environmental Sciences
    participants: Bar Oryan
  • seminar
    Date:
    18 March
    2020
    Wednesday
    Hours:
    11:00
    -
    12:00

    Canceled: Nanoscale Electronic Phenomena in Ferroelectric Thin Films

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Alexei Gruverman
    Department of Physics and Astronomy, University of Nebraska

    Abstract

    This seminar consists of two parts. The first part is related to the investigation of mechanism of tunable domain wall (DW) conductivity in the ferroelectric LiNbO3 thin films with sub-µm thickness, Using a combination of scanning transmission electron microscopy (STEM) and local probe techniques we generate and delineate the electrically-charged 180º DWs and test their conducting behavior using local probe spectroscopy and imaging under electrical bias. More importantly, electrical tunability of DW conductivity by sub-coercive voltage is realized through the changes in DW conformity. The obtained results provide tangible evidence that the charged DWs can be used as multilevel logic elements in analog computing devices. The second part discusses the dynamic switching behavior in the HfO2-based films investigated by a combination of local probe microscopy and pulse switching techniques. Application of HfO2-based materials to ferroelectric memory and logic devices has generated considerable interest as they allow overcoming significant problems associated with poor compatibility of perovskite ferroelectrics with CMOS processing. High-resolution studies of the time- and field-dependent evolution of the domain structure in La:HfO2 thin film capacitors provides an insight into the mechanism of imprint - one of the main degradation effects hindering integration of ferroelectric HfO2 into CMOS-compatible memory technology.
  • seminar
    Date:
    17 March
    2020
    Tuesday
    Hours:
    10:30

    Seismic sensing with optical fibers – principles and applications

    Location: Sussman Family Building for Environmental Sciences
    participants: Ariel Lellouch
    Department of Geophysics Stanford University

    Abstract

    During the last decade, seismic sensing with optical fibers has become a reality. By analyzing the effect of seismic deformation on the fiber’s optical response, state-of-the-art Distributed Acoustic Sensing (DAS) now offers a 1-meter sensor resolution for tens of kilometers of fiber. In other words, a single DAS system can record up to 40,000 data channels at once – two orders of magnitude more than the entire earthquake-monitoring seismic network in Israel. In this talk, I will first introduce the underlying operating principles of DAS acquisition. These measurements are very different from conventional seismic sensors and need to be analyzed accordingly. Subsequently, most of the talk will revolve around DAS applications in various scenarios. We use the ambient seismic field, recorded on a standard telecommunication fiber deployed around the Stanford campus, to analyze subsurface properties. We also acquired DAS data from a downhole fiber deployed in the SAFOD well and utilized it to reconstruct the earth’s structure and detect earthquakes. Finally, we study DAS data from an unconventional gas field and show how to conduct a simple analysis that unveils reservoir properties.
  • seminar
    Date:
    15 March
    2020
    Sunday
    Hours:
    11:00

    Potential role of cloud microorganisms in atmospheric chemistry

    Location: Sussman Family Building for Environmental Sciences
    participants: Anne-Marie Delort
    Institut de Chimie de Clermont-Ferrand, CNRS, Université Clermont Auvergne

    Abstract

    We have shown that microorganisms (bacteria, yeast and fungi) were present in clouds and were metabolically active. As a consequence a new scientific question rose: are they able to modify the chemical composition of clouds and be an alternative route to radical chemistry? In the past we have mainly studied the biotransformation of simple carbon compounds (acetate, succinate, formate, methanol, formaldehyde), and oxidants (H2O2). We showed that biodegradation rates were within the same range of order than photo-transformation rates. More recently we investigated their potential biodegradation activity towards atmospheric pollutants. Using GCxGC-HRMS technique we were able to detect and identify over 100 semi-volatile compounds in 3 cloud samples collected at the puy de Dôme station (1465 m, France). Among these compounds, 10 priority pollutants from the US EPA list were identified and quantified. We focused our work on the biodegradation of phenol and catechol in clouds using two strategies. 1) A metatranscriptomic analysis showed in cloud activity of microorganisms. We detected transcripts of genes coding for phenol monooxygenases (and phenol hydroxylases) and catechol 1,2-dioxygenases. These enzymes were likely from Gamma-proteobacteria (Acinetobacter and Pseudomonas genera). 2) 145 bacterial strains isolated from cloud water were screened for their phenol degradation capabilities, 93% of them (mainly Pseudomonas and Rhodococcus strains) were positive. These findings highlighted the possibility of phenol degradation by microorganisms in clouds. To go further we measured the biodegradation rates of Phenol and Catechol by one of the most active strain (Rhodococcus enclensis) and compared them with the transformation rates resulting from the reactivity of °OH and NO3°radicals. In the cloud water phase, both phenol transformation rates were within the same range of order, while biodegradation of catechol was ten times quicker than chemical transformation. The experimentally derived biodegradation rates were included in a multiphase box model to compare the chemical loss rates of phenol and catechol in both the gas and aqueous phases to their biodegradation rate in the aqueous phase under atmospheric conditions. In conclusion our results suggest that cloud microorganisms could play a role in atmospheric chemistry.
  • seminar
    Date:
    8 March
    2020
    Sunday
    Hours:
    11:00
    -
    12:00

    Engineering 3D vascularized tissue constructs: effects of biomaterials and mechanical forces.

    Location: Perlman Chemical Sciences Building
    participants: Prof. Shulamit Levenberg
    Department of Biomedical Engineering, Technion

    Abstract

    Engineering vascularized constructs represents a key challenge in tissue engineering. Sufficient vascularization in engineered tissues can be achieved through coordinated application of improved biomaterial systems with proper cell types. We have shown that vessel network maturity levels and morphology are highly regulated by matrix composition and analyzed the vasculogenic dynamics within the constructs. We also explored the effect of mechanical forces on vessels organization and demonstrated that morphogenesis of 3D vascular networks is regulated by tensile forces. Revealing the cues controlling vascular network properties and morphology can enhance tissue vascularization and improve graft integration prospects.
  • seminar
    Date:
    8 March
    2020
    Sunday
    Hours:
    11:00

    TBA

    Location: Sussman Family Building for Environmental Sciences
    participants: Antonello Provenzale
  • seminar
    Date:
    5 March
    2020
    Thursday
    Hours:
    13:00

    Building Atomic Models of Biomolecules in CCP-EM - Dr. Colin Palmer

    Location: Isaac Wolfson Building
  • seminar
    Date:
    5 March
    2020
    Thursday
    Hours:
    13:00
    -
    14:30

    Building Atomic Models of Biomolecules in CCP-EM - Dr. Colin Palmer

    Location: Isaac Wolfson Building
    participants: Building Atomic Models of Biomolecules in CCP-EM - Dr. Colin Palmer
  • seminar
    Date:
    5 March
    2020
    Thursday
    Hours:
    11:00
    -
    12:00

    Using Coot for Cryo-EM Model Building, Refinement and Validation

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Paul Emsley
    Laboratory of Molecular Biology Cambridge, England
  • seminar
    Date:
    5 March
    2020
    Thursday
    Hours:
    09:30
    -
    10:30

    MR spectroscopy at 7 tesla – initial experiences in Glasgow

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr Graeme Keith
    Imaging Centre of Excellence, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow.

    Abstract

    Much has been written of the potential of ultra-high field MR scanners, such as 7 tesla, due to their inherently higher signal-to-noise ratio (SNR). This native boost is of great use in making techniques that operate in a low SNR regime, such as spectroscopy, more viable. Application of spectroscopic techniques at 7 tesla also come with a secondary, yet perhaps more important benefit in increased spectral resolution. This can allow for the quantitative investigation of metabolites that are difficult to resolve and measure reliably at lower field strengths. This seminar will relate early experiences in spectroscopy from the Siemens Terra 7T system at the University of Glasgow. This will include the optimisation of single voxel techniques for clinical studies, such as the measurement of glutamate in neuroinflammatory conditions, as well as an update on development work, such as a spectral 2D correlated spectroscopy (COSY) acquisition for investigation of glioma tumours, including a focus on 2-hydorxyglutarate. It will also cover the development of a novel MR spectroscopic imaging (MRSI) technique based on the EPSI sequence, which will allow for high resolution, full spectral bandwidth 7T acquisitions in a clinically viable time, by application of compressed sensing methods
  • seminar
    Date:
    3 March
    2020
    Tuesday
    Hours:
    14:00
    -
    15:00

    Hierarchy in the innate immunity kingdom - Assembly mechanism of high order signaling machines

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Liron David
    Harvard Medical School
  • seminar
    Date:
    3 March
    2020
    Tuesday
    Hours:
    11:00
    -
    12:00

    Multidomain Peptide Assemblies for the Design of Adaptive Supramolecular Polymers and Synthetic Vaccines

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Dr. Pol Besenius
    Department of Chemistry, Johannes Gutenberg University Mainz

    Abstract

    Spatial and temporal control are critical properties to advance functional macromolecular materials in order to mimic key features of living systems. In my lecture, I will discuss our methodology in developing multicomponent supramolecular polymerization strategies in water. Using peptide-polymer conjugates we are able to address non-equilibrium states in the preparation of thermoresponsive hydrogel materials. Here, we make use of charge regulated ß–sheet selfassembly of oligopeptides and introduce reactive oxygen species (ROS) responsive subdomains to tune the time-domain of supramolecular polymerization. Using multicomponent assembly protocols, we currently explore the co-presentation of different epitopes and immunostimulating agents at the surface of supramolecular polymers. I will briefly discuss this modular supramolecular platform for immunotherapy applications and the development of multifunctional antitumor vaccines.
  • seminar
    Date:
    2 March
    2020
    Monday
    Hours:
    11:00
    -
    12:15

    When molecular science meets 2D materials: orchestrating multiple functions

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Paolo Samori
    Université de Strasbourg, France
  • seminar
    Date:
    1 March
    2020
    Sunday
    Hours:
    11:00

    TBA

    Location: Sussman Family Building for Environmental Sciences
    participants: Yakov Weiss
    The Hebrew University of Jerusalem
  • seminar
    Date:
    27 February
    2020
    Thursday
    Hours:
    14:00
    -
    15:00

    IDPs are in fact intrinsically disordered phospho-proteins

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. François-Xavier Theillet
    CNRS, Paris-Saclay France
  • seminar
    Date:
    27 February
    2020
    Thursday
    Hours:
    11:00
    -
    12:00

    An informal short talk about the new Coronavirus

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Ron Diskin
    Department of Structural Biology Chemistry faculty
  • seminar
    Date:
    23 February
    2020
    Sunday
    Hours:
    14:00
    -
    15:00

    Buckyball Maracas: Fullerene Nanocontainers that Stabilize Unusual Atoms and Clusters Inside

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Luis Echegoyen
    President of the American Chemical Society. University of El Paso, TX

    Abstract

    For the past two years we have been involved in the synthesis and characterization of new Uranium-based endohedral fullerenes and have obtained X-Ray crystal structures for several of these compounds. Some are mono-uranium species, U@C2n, while some are di-uranium compounds (see structure at the left), U2@C2n.1 Very recently we isolated two new mono-uranium compounds that violate the Isolated Pentagon Rule (IPR) with a C76 and a C80 cage possessing fused five-membered rings (pentalenes) on their surfaces.2 Still other endohedral structures are much more interesting and totally unanticipated, with formula U2X@C2n, where X= C, O, S or N and 2n= 72, 78 or 80, which reveal interesting metal-cage interactions and totally unprecedented clusters trapped inside. Some of the carbide compounds have been crystallized and the encapsulated U2C cluster (in U=C=U@C80) exhibits unprecedented bonding with totally unanticipated properties (see structure to the right).3 Finally, we have found that bis-porphyrin capsules exhibit exquisitely selective supramolecular binding for several of these uranium-based endohedral fullerene compounds.4 The synthesis, purification and characterization of these interesting endohedral fullerenes will be presented and discussed, along with very recent results about uranium-based endohedrals. References 1. Zhang, X.; Wang, Y.; Morales-Martínez, R.; Zhong, J.; de Graaf, C.; Rodríguez-Fortea, A.; Poblet, J. M.; Echegoyen, L.; Feng, L.; Chen, N., J. Am. Chem. Soc. 2018, 140 (11), 3907-3915. 2. Cai, W.; Abella, L.; Zhuang, J.; Zhang, X.; Feng, L.; Wang, Y.; Morales-Martínez, R.; Esper, R.; Boero, M.; Metta-Magaña, A.; Rodríguez-Fortea, A.; Poblet, J. M.; Echegoyen, L.; Chen, N., J. Am. Chem. Soc. 2018, 140 (51), 18039-18050. 3. Zhang, X.; Li, W.; Feng, L.; Chen, X.; Hansen, A.; Grimme, S.; Fortier, S.; Sergentu, D.-C.; Duignan, T. J.; Autschbach, J.; Wang, S.; Wang, Y.; Velkos, G.; Popov, A. A.; Aghdassi, N.; Duhm, S.; Li, X.; Li, J.; Echegoyen, L.; Schwarz, W. H. E.; Chen, N., Nature Comm. 2018, 9 (1), 2753. 4. Fuertes-Espinosa, C.; Gómez-Torres, A.; Morales-Martínez, R.; Rodríguez-Fortea, A.; García-Simón, C.; Gándara, F.; Imaz, I.; Juanhuix, J.; Maspoch, D.; Poblet, J. M.; Echegoyen, L.; Ribas, X., Angew. Chem. Int. Ed. 2018, 57 (35), 11294-11299.
  • seminar
    Date:
    23 February
    2020
    Sunday
    Hours:
    11:00

    Exploring the limits of Earth’s habitability by scientific ocean drilling: The impact of temperature on microbial life and carbon flow in deep sub-seafloor sediments

    Location: Sussman Family Building for Environmental Sciences
    participants: Verena Heuer
    National Academy of Science University of Bremen
  • seminar
    Date:
    23 February
    2020
    Sunday
    Hours:
    11:00
    -
    12:00

    Laser-induced graphene polymer composite membranes as electrically active filters for contaminant removal

    Location: Perlman Chemical Sciences Building
    participants: Dr. Christopher J. Arnusch
    Department of Desalination and Water Treatment, Zuckerberg Institute for Water Research

    Abstract

    The control/elimination of microorganisms, viruses and micropollutants is relevant in many water treatment systems. We developed Laser-induced graphene (LIG), a three-dimensional, porous, electrically conductive graphene material generated by irradiation of polymer substrates composites, which have strong antifouling and antimicrobial properties. This method to “laser-print” electrically conductive antifouling graphene coatings on membranes holds promise for advanced water treatment and purification
  • seminar
    Date:
    13 February
    2020
    Thursday
    Hours:
    10:00
    -
    11:00

    M.Sc thesis defense: "The origin of anharmonic atomic motion in halide perovskite crystals"

    Location: Perlman Chemical Sciences Building
    participants: Adi Cohen

    Abstract

    Halide perovskites (ABX3) attracted much of attention in the last years due to their excellent photovoltaic activity. They are unique in the sense that they exhibit long carrier lifetime despite having many apparent structural defects. Recent studies in our group concluded that this unique behavior is due to strong coupling between the electronic band structure and the strongly anharmonic motion of the atoms within the crystal. Therefore, it is imperative to understand the source of anharmonic atomic motion in this class of materials. Studies have indicated the B-cation lone pair to be a possible source for strong anharmonic behavior in the perovskite crystals. In order to understand the anharmonic behavior and its origin, I investigated a series of perovskites with different lone pair stereoactivity. Using low frequency Raman spectroscopy, I quantified the level of anharmonicity and determined the influence of the B-cation lone pair on the structural dynamics.
  • seminar
    Date:
    12 February
    2020
    Wednesday
    Hours:
    11:00
    -
    12:00

    Exciton and trions in Van der Waals materials and their dynamics under different non-uniform strain configurations

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Moshe Harats
    Faculty of Physics, Freie University Berlin

    Abstract

    Abstract: In recent years, Van der Waals (2D) materials, have attracted increasing attention due to their distinctive physical properties. As layered materials, they have been considered for flexible electronics as they can sustain strain higher than 10% without breaking down, although they are only 1-3 atom thick. Their superior mechanical properties led to a renewed interest in the mechanics of thin membranes linked to condensed matter physics. In this talk we will show how we can apply non-uniform strain to a suspended Van der Waals material (WS2) and alter the dynamics of excitons and trions. Surprisingly, we find that as we increase the non-uniformity of the strain, we are able to convert the excitons into trions with almost 100% efficiency without any electrostatic gating. Our results explain inconsistencies in previous experiments and pave the way towards new types of optoelectronic devices.
  • seminar
    Date:
    11 February
    2020
    Tuesday
    Hours:
    11:00
    -
    12:00

    Planar and Twisted π-Conjugated Materials

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Ori Gidron
    Institute of Chemistry, The Hebrew University of Jerusalem

    Abstract

    Planarity plays a crucial role in determining the electronic and optical properties of π-conjugated backbones. Here I will discuss two examples of non-planar and planar systems: twisted acenes and planar furan-based macrocycles. In the first part, I will demonstrate how twisting affects the electronic, optical and chiroptical properties of acenes. We have introduced a series of twisted acenes, having an anthracene backbone diagonally tethered by an n-alkyl bridge, which induces different degrees of twisting. This helically-locked system allows us to systematically monitor the effect of twisting on electronic and optical properties of anthracene. The effect of twisting on chiroptical properties, charge delocalization and π-conjugation will also be demonstrated. In the second part, I will present bifuranimide as a stable furan containing analog, which resulted in the introduction of the first macrocyclic furans. These π-conjugated macrocycles were found to be completely planar, in contrast with thiophene macrocycles which are highly-twisted. The prospects of macrocyclic furans as π-conjugated analogs of crown-ethers and synthons for cycloarenes by multiple Diels–Alder cycloadditions will be discussed.
  • seminar
    Date:
    9 February
    2020
    Sunday
    Hours:
    11:00

    Utilization of machine learning techniques to retrieve aerosol and cloud properties from remote sensing measurements

    Location: Sussman Family Building for Environmental Sciences
    participants: Michal Segal Rosenheimer
    Tel Aviv University
  • seminar
    Date:
    9 February
    2020
    Sunday
    Hours:
    11:00
    -
    12:00

    From contraction waves to rupture resistance – biological tissues as active solids

    Location: Perlman Chemical Sciences Building
    participants: Dr. Shahaf Armon
    Dept. Physics of Complex Systems, WIS

    Abstract

    Following our recent observations of contraction waves in the primitive epithelium of Placozoa, we develop a model of tissues as sheets of contractile cells. The simple model assumes only a strain-threshold for contraction, and explains/predicts a variety of unique and surprising phenomena, e.g.: contraction waves in response to external stress, spontaneously-compressed steady-state, emerged limit-cycles, mechanical frustration and active resistance to rupture. In the talk I will present both the experimental observations and the model results. This model of “active cohesion” may be relevant to any epithelial tissue, to manufacturing of synthetic active materials, and to models of evolution of multicellularity.
  • seminar
    Date:
    6 February
    2020
    Thursday
    Hours:
    09:00
    -
    10:00

    “Entropy and ceramics: A valuable partnership”

    Location: Perlman Chemical Sciences Building
    participants: Dr. Corey Oses
    Dept Mechanical Engineering and Materials Science, Duke University
  • seminar
    Date:
    3 February
    2020
    Monday
    Hours:
    14:00
    -
    15:00

    Peptide-Coated Platinum Nanoparticles as Antitumor Agents

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Michal Shoshan
    Group leader in Bioinorganic Chemistry Department of Chemistry, University of Zurich
  • seminar
    Date:
    2 February
    2020
    Sunday
    Hours:
    11:00

    Developing Models to Estimate Crop Water Consumption based on Remote Sensing and Meteorological Data

    Location: Sussman Family Building for Environmental Sciences
    participants: Offer Rozenstein
    Volcani
  • seminar
    Date:
    28 January
    2020
    Tuesday
    Hours:
    14:00
    -
    15:00

    Toward HCV vaccine - Structural studies of HCV E2 envelop glycoprotein that facilitates rational design of HCV vaccine.

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Netanel Tzarum
    HUJI
  • seminar
    Date:
    28 January
    2020
    Tuesday
    Hours:
    11:00
    -
    12:00

    Catalyst Images, Imaging and Imagination: Visualizing Molecules and Atoms in Action on Catalytic Surfaces

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Bert M. Weckhuysen
    Inorganic Chemistry and Catalysis, Utrecht University

    Abstract

    Catalysts play a pivotal role in modern society since they enable the production of chemicals and fuels that we rely on every day. The search for new and improved solid catalysts to speed up and access novel chemical reactions is a never-ending challenge, but has become increasingly important due to the environmental challenges that we are currently facing. For this purpose, constant improvements in synthesis methods are required in general, but more specifically, improvements in characterization methods in terms of spatiotemporal resolution is the key toward tailored catalytic reactions. In an ideal case, a real time visualization of the reactants, intermediates and reaction products on the surface of the catalyst is possible, allowing for a molecular movie of the catalytic reaction in space and time. Certain characterization techniques exist that are sensitive enough to measure the reactants at the reaction surface of the catalyst (e.g. vibrational spectroscopy). However, in order to really understand the catalytic behaviour, we need to move toward single molecules and atoms at the (sub-) nanometer scale. Improvements in this direction have already led to an increased understanding of the catalytic processes, but the combination of nanometer resolution in space and pico- to nanosecond resolution in time has remained largely elusive in the world of heterogeneous catalysis.  In this lecture, I will discuss the state-of-the-art of time- and space-resolved spectroscopy and microscopy methods for catalysis research, and discuss the movement in the field toward the visualization of individual molecules at catalyst surfaces to construct the ultimate “molecular movie of sustainability” (Figure 1). Special emphasis will be on the compatibility of operando characterization techniques with the desired reaction environment (e.g. liquid or gas phase) and what we can do to ensure the spatiotemporal resolution is not hampered by the reaction requirements of the catalytic reactions. I will touch upon a variety of techniques, ranging from (time-resolved and surface-enhanced) vibrational spectroscopy, single molecule fluorescence, scanning probe techniques combined with optical and vibrational spectroscopy, as well as X-ray spectroscopy and microscopy.
  • seminar
    Date:
    28 January
    2020
    Tuesday
    Hours:
    11:00

    Chemical and Biological Physics Dept Seminar

    Location: Perlman Chemical Sciences Building
    participants: Dr Rinat Ankri
    Postdoctoral Fellow, UCLA, CA

    Abstract

    Biomolecular imaging at the preclinical stage is an essential tool in various biomedical research areas such as immunology, oncology or neurology. Among all modalities available to date, optical imaging techniques play a central role, while fluorescence, in particular in the NIR region of the spectrum, provides high sensitivity and high specificity with relatively cheap instrumentation. Several whole-body optical pre-clinical NIR imaging systems are commercially available. Instruments using continuous wave (CW or time-independent) illumination allow basic small animal imaging at low cost. However, CW techniques cannot provide fluorescence lifetime contrast, which allows to probe the microenvironment and affords an increased multiplexing power. In the first part of my talk I will introduce our single photon, time-gated, phasor-based fluorescence lifetime Imaging method which circumvents limitations of conventional techniques in speed, specificity and ease of use, using fluorescent lifetime as the main contrast mechanism. In the second part of my talk I will present the tracking and multiplexing of two different cell populations, based on their different lifetimes (following their fluorescent dyes-loading). Despite major advantages of optical based NIR imaging, the reason that NIR imagers are not clinically used, is that only very few such fluorescent molecules absorb and emit in the NIR (or in the shortwave infrared, SWIR region), and even fewer have favorable biological properties (and FDA approval). I will introduce small lung cancer and dendritic cells tracking using small polyethylene glycol/phosphatidylethanolamine (PEG–PE) micelles loaded with NIR dyes (using commercial dyes as well as dyes synthesized in Prof. Sletten’s lab, UCLA Chemistry Dept.). Micelles’ endocytosis into cells affords efficient loading and exhibits strong bio stability, enabling to track the loaded cells for several days using these formulations, even though dyes were diluted by cells division (leading to reduced dye concentration within the dividing cells). Moreover, fluorescent lifetime contrast (achieved through our time-gated imaging method), significantly improved these cells detection. These advances in NIR fluorescence based imaging open up new avenues toward NIR and SWIR imaging for biomedical applications, such as tracking and monitoring cells during immunotherapy and/or drug delivery (treatment monitoring) for various types of disease.
  • seminar
    Date:
    26 January
    2020
    Sunday
    Hours:
    14:00
    -
    15:00

    Chemical and Biological Physics Guest Seminar

    Location: Perlman Chemical Sciences Building
    participants: Dr Menahem (Hemi) Rotenberg
    The James Franck Institute, the University of Chicago

    Abstract

    Bioelectronics for cellular interrogation requires a minimally invasive introduction of an electrical probe to the cell. Despite tremendous developments in the field of electroceuticals in the past decades, the available technologies are still associated with major limitations. Micropipette electrodes, micro- and nanoelectrode arrays, and nano-field effect transistors allow intracellular access with extremely high spatial resolution. However, these technologies are substrate-bound, do not allow reconfigurable recording or stimulation, and lack deep tissue access, which limits their use to in vitro application. Optogenetics can offer numerous mechanistic insights into cellular processes, but its spatial resolution is limited, especially for 3D tissues. Moreover, it requires genetic modification, which limits its potential therapeutic applications. In this talk, I will present my recent studies of developing new approaches for bio-interfaces using silicon micro- and nanostructures for non-genetic optical modulation, spanning from sub cellular interrogation with extremely high spatial resolutions to whole organ optical modulation. For sub-cellular interrogation, we used tailored made photovoltaic silicon nanowires with p-i-n core-shell design. These nanowires were hybridized with living myofibroblasts and used as free sanding cell-silicon hybrids with leadless optical modulation capabilities. We used focused laser to perform intracellular electrical interrogation with high, sub-cellular spatial resolution. Thereafter, we used these hybrids to tackle a long-standing debate regarding electrical coupling between myofibroblasts and cardiomyocytes in vivo, by interrogating specific myofibroblasts within the 3D volume of the cardiac tissue. We also show this technology’s utility for neuronal investigation by hybridizing myelinating oligodendrocytes and interfacing them with neurons, allowing the investigation of calcium transients’ role in the myelination process with unprecedented spatial control. For whole organ interface we used flexible single crystalline silicon membranes, that were able to adhere and wrap around the heart and sciatic nerve. We used optical stimulation to perform heart pacing at different location on the heart, and sciatic nerve excitation. These results demonstrate potential biomedical applications for cardiac resynchronization therapy and sciatic nerve neuro-regenerative treatments.
  • seminar
    Date:
    26 January
    2020
    Sunday
    Hours:
    11:00

    Quantifying Holocene rainfall and evaporation in East Asia

    Location: Sussman Family Building for Environmental Sciences
    participants: Yoni Goldsmith
    Hebrew University of Jerusalem
  • seminar
    Date:
    26 January
    2020
    Sunday
    Hours:
    11:00
    -
    12:00

    Mechanical interaction between cells in fibrous environments

    Location: Perlman Chemical Sciences Building
    participants: Dr. Ayelet Lesman
    School of Mechanical Engineering, Faculty of Engineering, Tel-Aviv University

    Abstract

    Tissues are made up of cells and an extracellular matrix (ECM), a cross-linked network of fibers that exhibits complex mechanics. Cells actively alter the ECM structure and mechanics by applying contractile forces. These forces can propagate far into the matrix and allow for remote cellular sensing. We study experimentally and computationally how cell-generated forces are transmitted in fibrous environments, the associated physical mechanisms, and the ability of the propagated forces to support mechanical interaction between distant cells. Also, we demonstrate how the dynamic changes in the ECM structure can lead to improve transport of molecules traveling between the cells, facilitating mechano-biochemical interactions. Such long-range force interactions through the ECM can drive large-scale cooperative biological processes, such that occur during wound healing and morphogenesis. Our work can also provide design parameters for biomaterials used in tissue engineering applications.
  • seminar
    Date:
    22 January
    2020
    Wednesday
    Hours:
    11:00

    Chemical and Biological Physics Guest Seminar

    Location: Perlman Chemical Sciences Building
    participants: Dr Matan Mussel
    NIH, USA

    Abstract

    Soft matter systems offer a useful framework to study minimal models for living cells, helping to explain and quantify various aspects of biological functions in terms of macroscopic variables, symmetries, and universal properties. In this talk I will describe two such materials with particular focus on phenomena that arise when the system is near a phase transition. In the first part, I will describe a theoretical model of sound in lipid membranes near phase transition that corresponds to observations of nonlinear sound pulses in lipid monolayers as well as action potentials in living cells. Key properties are sigmoidal response to stimulation amplitude, and annihilation upon collision. I will explain the role of the phase diagram in producing the nonlinear properties and how sound in lipid membranes propagates thermal, electrical, and chemical variations in addition to the well-known mechanical changes. In the second part of the talk, I will describe a volume phase transition induced by the exchange of mono- and divalent cations in a polyelectrolyte hydrogel model. Ion-exchange and volume phase transition play a key role in several physiological functions where biopolymers are exposed to both mono- and multivalent counterions. These functions include, for instance, the packaging of DNA, andthe storage and release of cell secretory products. Our observations suggest that although the state diagram of the model system depends on many parameters of the gel and surrounding fluid, the volume phase transition exhibits universal properties. Osmotic swelling pressure measurements further reveal that both the second and third virial coefficients decrease with increasing divalent cation concentration until the volume transition is reached.
  • seminar
    Date:
    21 January
    2020
    Tuesday
    Hours:
    14:00
    -
    15:00

    Connecting the Dots: Multiple-substrate orchestration in bacterial type IV secretion systems

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Amit Meir
    Yale University
  • seminar
    Date:
    21 January
    2020
    Tuesday
    Hours:
    11:00
    -
    12:00

    Towards Advanced Materials: From Unique Peptidomimetics to High-Performance Thermosets

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Revital Kaminker
    UC Santa Barbara

    Abstract

    High-performance materials with elevated operating temperatures and robust mechanical properties, are essential for a wide variety of emerging applications, such as in functional adhesives, automobiles, aerospace, and coatings. Polyhexahydrotriazines (PHT) are new promising high-performance thermosets exhibiting enhanced thermal and mechanical properties.1 The performance and utility of PHT-based materials is further enhanced by the ability to design new material properties based on changes in the molecular structure.2 We demonstrated a new solvent-free approach for the fabrication of PHT based on low-melting-point diamines enabling the production of adhesives with comparable properties to well-established epoxy adhesives. Furthermore, these versatile materials could be degraded at different rates in acidic conditions based on the nature of the starting diamine molecular structure. Controlling the degradation is extremely valuable in composites and adhesives in order to be able to recycle and rework the materials. In the second part of my talk I will show how the ability to control and adapt peptide conformation is crucial for the rational design and control of their function.3,4 We demonstrated by end-to-end distance measurements using Double Electron-Electron Resonance (DEER) EPR method that we can tune the conformations of the backbone while maintaining the sequence of the side-chains. Interestingly, tuning of the backbone has an effect on peptide propensity to aggregate or stabilize nanoparticles. Such knowledge is critical for designing new materials for various biotechnological applications. 1. J. M. García, G. O. Jones, K. Virwani, B. D. McCloskey, D. J. Boday, G. M. ter Huurne, H. W. Horn, D. J. Coady, A. M. Bintaleb, A. M. S. Alabdulrahman, F. Alsewailem, H. A. A. Almegren, J. L. Hedrick. Science 2014, 344, 732–735. 2. R. Kaminker, E. B. Callaway, N. D. Dolinski, S. M. Barbon, M. Shibata, H. Wang, J. Hu, C. J. Hawker. Solvent-Free Synthesis of High-Performance Polyhexahydrotriazine (PHT) Thermosets. Chem. Mater. 2018, 30, 8352–8358. 3. R. Kaminker, I. Kaminker, W. R. Gutekunst, Y. Luo, S.-H. Lee, J. Niu, C. J. Hawker, S. Han. Tuning Conformation and Properties of Peptidomimetic Backbones through Dual N/Cα-Substitution. Chem. Commun. 2018, 54, 5237–5240. 4. R. Kaminker, A. Anastasaki, W. R. Gutekunst, Y. Luo, S.-H. Lee, C. J. Hawker. Tuning of Protease Resistance in Oligopeptides through N-alkylation. Chem. Commun. 2018, 54, 9631–9634.
  • seminar
    Date:
    19 January
    2020
    Sunday
    Hours:
    11:00

    Soil Spectroscopy throughout the Years: Availabilities and Capabilities

    Location: Sussman Family Building for Environmental Sciences
    participants: Eyal Ben-Dor
    Department of Geography Porter School of Environment and Earth Sciences Faculty of Exact Sciences Tel Aviv University Israel

    Abstract

    The soil spectroscopy discipline has been progressed over the past two decades quite remarkably. Many portable point spectrometers became available through that time where recently also image spectrometers have become quite popular. The technology was used in the laboratory, field, and airborne levels and provided a new capability for a rapid and quantitative view of a large number of samples. At the same time platforms were also developed to carry the new family of sensors for remote sensing applications of large areas using ground and airborne vehicles ( manned and un-manned) and recently even satellites. This progress has led to a large number of activities in exploiting the spectroscopy for many applications within the soil science discipline. As the data acquisition increases and the soil spectral database has been enlarged, a new technique to compile soil spectral database together with methods to effectively analyze them has also been developed. To that end, activities to deal with the data mining process using big databases were successfully adopted from other disciplines while also designed especially for the soil spectroscopy activity. The results demonstrated that soil spectroscopy could be used for many applications from different domains such as soil mapping, precision agriculture, and laboratory work and can progress the soil science discipline quite forward. In this talk, we will review the history of soil spectroscopy from the first spectrometer and platform to the present situation. A particular emphasis will be given to the recent applications that have been developed in our group and to the future capability of this critical technology from all perspectives and to the new horizon it may open as expressed by space agencies such as NASA, ESA, ASI, JAXA, ISA and DLR.
  • seminar
    Date:
    16 January
    2020
    Thursday
    Hours:
    09:30
    -
    10:30

    Solid State NMR of low abundant quadrupolar nuclei achieved through extended coherence lifetimes

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Daniel Jardon-Alvarez
    Dept. Materials and Interfaces, WIS

    Abstract

    Less is more! By using extremely low power refocusing π pulses in echo train sequences the coherence lifetime, T2, of the central transition of half-integer quadrupolar nuclei can be largely extended. This effect is particularly impactful in systems dilute in NMR active nuclei, where sources of decoherence are scarce. Crucial to this lifetime extension is the avoidance of coherence transfer to short-lived non-symmetric “killing” transitions. For 17O in polycrystalline α-quartz we were able to retain coherent magnetization for over four minutes on the transverse plane. This translates into enormous sensitivity gains for echo train acquisition after addition of the long living echoes. By combining satellite population transfer schemes with a low power CPMG on 17O in quartz, we obtain over a 1000-fold sensitivity enhancement compared to a spectrum from a free induction decay acquired at a more typical rf field strength. This enhancement allows the acquisition of a highly resolved 17O spectrum within less than one hour, despite its low natural abundance and a spin-lattice relaxation time of approximately 900 s. In this talk I will present a thorough analysis of the effects of pulse power on the echo intensity, coherence lifetime and line shape integrity. Finally, we apply this approach on various crystalline and glassy inorganic solids, including other low sensitivity nuclei, such as 33S and 45Ca, showing that it can be beneficial for a large number of systems.
  • seminar
    Date:
    15 January
    2020
    Wednesday
    Hours:
    11:00
    -
    12:00

    Surface Modification by Molecular/Atomic Layer Deposition of Functional Thin Films

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Malachi Noked
    Chemistry Department, Bar Ilan University

    Abstract

    Atomic/Molecular layer deposition (ALD/MLD) are based on the use of hetero- and homo-bifunctional organic or metal-organic compounds that vaporize, chemisorb onto and react with an appropriately functionalized surface. Both ALD and MLD allow temporal separation of any number of precursors, each of which produces self-limiting adsorption/reaction on the surface so that typical uptake is limited to ~one monolayer of any given precursor. This leads to growth controlled at the monolayer level and self-limiting reactions that have shown extreme conformality, even into ultra-high-aspect-ratio and porous substrates. In my talk I will show how utilization of carefully chosen M/ALD process enables functionalization of interfaces. I will show to sides of the coins for surface modification; namely turning “inert” interface into functional interface/interphase (e.g. inert interface into enantioselective interface) or by changing active interface into inert interface (e.g. protection layer on reactive surface in batteries). In the enantioselective example I will address a question with both fundamental and applicative significance: can we grow molecularly thin films from the vapor phase, which maintain a desirable chemical property originated from the source precursor. This question can be exemplified by a variety of chemical properties, such as MLD of enantioselective thin films from chiral building blocks (e.g. volatile amino acids), thin film deposition of molecular traps, and more.
  • seminar
    Date:
    14 January
    2020
    Tuesday
    Hours:
    14:00
    -
    15:00

    Characterization of calcium ion cellular pathways in sea urchin larvae

    Location: Helen and Milton A. Kimmelman Building
    participants: Keren Kahil
    Labs of Prof. Lia Addadi & Prof. Steve Weiner Dept. of Structural Biology, WIS
  • seminar
    Date:
    14 January
    2020
    Tuesday
    Hours:
    11:00
    -
    12:00

    Introduction to process -way-of-thinking via case study of three stages telescoping (Domino)- type process

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Eran Fogler
    ADAMA agricultural solutions, Ramat Hovav, Israel

    Abstract

    The implementation of an organic reaction on industrial scale requires not only the adjustment of scale, but not less importantly a different way of looking at it. In addition to focusing on the reaction parameters, focusing on the process is essential. This add the process-way-of-thinking to the scope of the industrial chemist. In this talk a process-way-of-thinking will be presented via a case study containing: 1. New chemistry (to the best of our knowledge) for synthesis of organic compound containing sulfur.[1] 2. Implementation of this chemistry in a scalable manner. 3. Some industrial considerations required upon scale up. 4. Application of the above in a telescoping (domino) type process. [1] PCT/US2018/060659
  • seminar
    Date:
    14 January
    2020
    Tuesday
    Hours:
    11:00
    -
    12:00

    Chemical and Biological Physics Guest Seminar

    Location: Perlman Chemical Sciences Building
    participants: Dr Pavel Jelinek
    Institute of Physics, Czech Academy of Sciences, Prague

    Abstract

    Low dimensional materials offer very interesting material and physical properties due to reduced dimensionality. Nowadays, mostly 2D materials are the focus of attention. However, 1D systems often show far more exotic behavior, such as Tomanaga-Luttinger liquid, Peierls distortion, etc.. In this talk, we will present different classes of 1D molecular chains formed on metallic surfaces by on-surface synthesis, which physical and chemical properties were investigated by low temperature UHV scanning probe microscopy supported by theoretical analysis. First, we will introduce a novel strategy to synthesize [1] a new class of intrinsically quasi-metallic one-dimensional (1D) -conjugated polymers featuring topologically non-trivial quantum states. Furthermore, we unveiled the fundamental relation between quantum topology, -conjugation and metallicity of polymers [2]. Thus, we will make a connection between two distinct worlds of topological band theory (condensed matter physics) and -conjugation polymer science (chemistry). We strongly believe this may stimulate new ways of thinking towards a design of novel organic quantum materials. In second part, we will demonstrate unusual mechanical and electronic properties of hydrogen bonded chains formed on a metallic surface driven by quantum nuclaar effects within the chain. We will show, that the concerted proton tunneling not only enhances the mechanical stability of the chain, but it also gives rise to new in-band gap electronics states localized at the ends of the chain. [1] A. Grande-Sanchez et al. Angew. Chem. Int. Ed. 131, 6631-6635 (2019). [2] B. Cierra et al arXiv preprint arXiv:1911.05514
  • seminar
    Date:
    12 January
    2020
    Sunday
    Hours:
    14:00

    Chemical and Biological Physics Guest Seminar

    Location: Perlman Chemical Sciences Building
    participants: Prof. Peter Hamm
    U. of Zurich
  • seminar
    Date:
    12 January
    2020
    Sunday
    Hours:
    11:00

    Orbital modulation of geological activity

    Location: Sussman Family Building for Environmental Sciences
    participants: Francis Nimmo
    Department of Earth and Planetary Sciences University of California Santa Cruz

    Abstract

    Many planetary bodies experience tides, which produce time-varying stresses. Seismic activity on the Moon is modulated by tides, and there are hints of similar effects on Earth (but not, so far, Mars). In this talk I'll describe two other places where tides modulate geological activity at different periods: Io, a highly volcanic moon of Jupiter; and Enceladus, a small icy moon of Saturn. In both cases we can use remote-sensing observations of the modulation to make inferences about the properties of these bodies' interiors. One could imagine similar approaches being used for tidally-distorted exoplanets (e.g. the TRAPPIST system).
  • seminar
    Date:
    12 January
    2020
    Sunday
    Hours:
    11:00
    -
    12:00

    "Modeling growth of biological tissues"

    Location: Perlman Chemical Sciences Building
    participants: Dr. Oz Oshri
    Dept. Mechanical Engineering, BGU

    Abstract

    Growth of biological tissues and shape changes of thin synthetic sheets are commonly induced by stimulation of isolated regions (inclusions) in the system. These inclusions apply internal forces on their surroundings that, in turn, promote 2D layers to acquire complex 3D configurations. We focus on a fundamental building block of these systems, and consider a circular plate that contains an inclusion with dilative strains. We derive an analytical model that predicts the 2D-to-3D shape transitions in the system and compare the results with numerical simulations. Then, we utilize this model to analyze the interaction between two inclusions that undergo buckling instability.
  • seminar
    Date:
    7 January
    2020
    Tuesday
    Hours:
    11:00
    -
    12:00

    A hydrogen-bonded framework toolkit for molecular structure determination

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Michael D. Ward
    Department of Chemistry and Molecular Design Institute, New York University

    Abstract

    Single crystal X-ray diffraction is arguably the most definitive method for molecular structure determination, but the inability to grow suitable single crystals can frustrate conventional X-ray diffraction analysis. Building on a prolonged examination of hydrogen-bonded frameworks and inclusion compounds derived from guanidinium organosulfonates, we have devised an approach to molecular structure determination that relies on a versatile toolkit of these host frameworks, which form crystalline inclusion compounds with target guest molecules in a single-step crystallization. This approach complements the so-called crystalline sponge method that relies on diffusion of the target into the cages of a metal-organic framework, while circumventing many of its challenges. The peculiar properties of the host frameworks enable rapid stoichiometric inclusion of a wide range of target molecules with full occupancy, typically without disorder and accompanying solvent, affording well-refined structures. Moreover, anomalous scattering by the framework sulfur atoms enables reliable assignment of absolute configuration of stereogenic centers. An ever-expanding library of organosulfonates provides a toolkit of frameworks for capturing specific target molecules for their structure determination. This presentation will describe examples of this approach to structure determination, preceded by an account of the unusual properties and resilience of these hydrogen-bonded frameworks, their substantial diversity of framework architectures, and their utility in other applications.
  • seminar
    Date:
    5 January
    2020
    Sunday
    Hours:
    11:00

    The Critical Role of Chronology in Understanding Past Climate Change: Precisely Reconstructing Holocene Climate at Mono Lake, California

    Location: Sussman Family Building for Environmental Sciences
    participants: Susan R. H. Zimmerman
    Atmospheric, Earth and Energy Division Lawrence Livermore National Laboratory

    Abstract

    Recent droughts and floods in California have drawn attention to the vulnerability of our water-supply system to present and future climate variability. A recent analysis of climate-model simulations suggests that wet and dry conditions in California may be predictably linked to tropical and high-latitude conditions, a hypothesis that should be testable using paleoclimate records. Abundant paleoclimate evidence indicates that natural whiplash between wet and dry conditions characterized California’s climate throughout the last 4000 years, especially during the Medieval Climate Anomaly (~AD 950 to 1250), but the chronologies of the records are not precise enough to correlate to tropical and high-latitude records in order to test the model prediction. Our recent work at Mono Lake, a climatically sensitive lake on the arid eastern side of the Sierra Nevada mountain range, has focused on exploring and developing radiocarbon dating of pollen purified by flow cytometry as a tool for high-resolution dating of lake records. Our results suggest that pollen can be reliably separated and dated, but (like everything in lakes) must be interpreted within the specific geologic system where it was produced, deposited, and preserved. If pollen dating proves robust in many lake systems, it may provide the high-precision chronologies required for spatial mapping of past terrestrial climate changes.
  • seminar
    Date:
    5 January
    2020
    Sunday
    Hours:
    11:00
    -
    12:00

    When people disappear - Stories and fairytales

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Professor Daniel H. Wagner

    Abstract

    In the history of many families, all that remains about the fate of an ancestor for whom all traces were lost are rumors, often in conflicting versions. One of the most gratifying pleasures of a genealogical quest is to unveil the true story. Selected examples taken from the lecturer’s personal history will demonstrate this.
  • seminar
    Date:
    2 January
    2020
    Thursday
    Hours:
    11:00

    Should multiple agents work together or split their job to control populations of harmful species?

    Location: Sussman Family Building for Environmental Sciences
    participants: Adam Lampert

    Abstract

    The management of harmful species, including invasive species, pests, parasites, and diseases, is a major global challenge. Harmful species cause severe damage to ecosystems, biodiversity, agriculture, and human health. In particular, the management of harmful species often requires cooperation among multiple agents, such as land‐owners, agencies, and countries. Each agent may have incentives to contribute less to the treatment, leaving more work for other agents, which may result in inefficient treatment. A central question is, therefore, how should a policymaker allocate the treatment duties among the agents? Specifically, should the agents work together in the same area, or should each agent work only in a smaller area designated just for her/him? I will present a dynamic game-theoretic model, where a Nash equilibrium corresponds to a possible set of contributions that the agents could adopt over time. In turn, the allocation by the policymaker determines which of the Nash equilibria could be adopted, which will allow us to compare the outcome of various allocations. I will show that fewer agents abate the harmful species population faster, but multiple agents can better control the population to keep its density lower. This is proven in a general theorem and demonstrated numerically for two case studies. Therefore, following an outbreak, the better policy would be to split and assign one or a few agents to treat the species in a given location; but if controlling the harmful species population at some low density is needed, the agents should work together in all the locations.
  • seminar
    Date:
    31 December
    2019
    Tuesday
    Hours:
    14:30
    -
    15:00

    Intricate Assembly Mechanism of Mucin Glycoproteins Revealed by Cryo-electron Microscopy of Polymers

    Location: Helen and Milton A. Kimmelman Building
    participants: Gabriel Javitt
    Prof. Deborah Fass lab Dept. of Structural Biology Weizmann Institute
  • seminar
    Date:
    31 December
    2019
    Tuesday
    Hours:
    14:00
    -
    14:30

    Reversible-Covalent Proteolysis-Targeting Chimeras (PROTACs): opening the door for new targets

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Ronen Gabizon
    Dr. Nir London lab Dept. of Organic Chemistry Weizmann Institute
  • seminar
    Date:
    30 December
    2019
    Monday
    Hours:
    11:00

    A mechanism for positive lapse-rate feedback in polar regions

    Location: Sussman Family Building for Environmental Sciences
    participants: Prof. Rodrigo Caballero
    Department of Meteorology (MISU) Stockholm University

    Abstract

    Observations and climate simulations show that polar regions warm faster than the rest of the globe in response to radiative forcing. Feedback diagnostics in models show that a large fraction of this enhanced polar warming is due to strong positive lapse-rate feedback. However, there is little mechanistic understanding for why this feedback is positive and what controls its strength. Here, I discuss a mechanism for high-latitude lapse rate feedback and show it functioning in a set of simplified GCM simulations. The mechanism hinges crucially on low cloud response. In this sense, high-latitude lapse-rate feedback is a cloud feedback in disguise.
  • seminar
    Date:
    30 December
    2019
    Monday
    Hours:
    09:00
    -
    10:00

    NMR structure and dynamics studies of oligo- and polysaccharides

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Daron Freedberg
    Center for Biologics Evaluation and Research, U.S. Food and Drug Administration

    Abstract

    Glycans are ubiquitous in nature and participate in a wide variety of biological processes, that span from mediating cell-cell interactions to modulating protein stability and folding. Glycan involvement in diverse biological functions can be rationalized by the equally extensive potential for structural diversity. They vary not only in monosaccharide composition and primary sequence, like proteins and nucleic acids, but also the monosaccharides can vary in ring sizes, linkage types, and functional group modifications. Therefore, their structural complexity has the potential for encoding a myriad of functions. However, it is this “structural richness” that hampers progress in stablishing structure-function relationships, simply because tools and strategies for structure determination are lacking. We are delineating three-dimensional glycan solution structure to gain insight into how they function, which should facilitate development of glycan-based vaccines, drug delivery systems, and antibiotics of the future. To this end, we use heteronuclear multidimensional NMR to determine conformations and dynamics of 15N, 13C enriched oligo- and polysaccharides. We have detected interresidue hydrogen bonds and used RDCs to delineate the relative orientations of the rigid monosaccharide building blocks. However, RDC measurements are fraught with errors from strong coupling effects. Thus, we have developed methods to accurately measure one-bond 1H-13C splittings and 13C-13C splittings as well as RDCs. I will illustrate the application of these methods for bacterial polysaccharide model systems and show how we applied them to support the two-residue per turn helical structure of 2-8 tetrasialic acid and the smaller conformationally stable dimer in solution at low temperatures.
  • seminar
    Date:
    29 December
    2019
    Sunday
    Hours:
    11:00
    -
    12:00

    Bistable behavior of nonpsherical colloids near a charged surface

    Location: Perlman Chemical Sciences Building
    participants: Prof. Yoav Tsori
    Department of Chemical Engineering, Ben Gurion University

    Abstract

    We investigate theoretically a model system of colloids in water. The colloid size is neither very small compared to the Debye length, nor very large. We look at the orientation of the colloid near a surface, and find bistable behavior. This may have implications for flow in microfluidic channels, and for crystallization near surfaces.
  • seminar
    Date:
    25 December
    2019
    Wednesday
    Hours:
    11:00
    -
    12:00

    “2D, 3D, 4D printing: The next industrial revolution”

    Location: Perlman Chemical Sciences Building
    participants: Prof. Shlomo Magdassi
    The Institute of Chemistry , The Hebrew University of Jerusalem

    Abstract

    Additive manufacturing, which is fabrication through printing processes, has gained a lot of interest in the academy and industry, and is considered as the next industrial revolution. The synthesis and formulations of new inks compositions will be presented, along with their applications in various fields. New materials and processes for 2, 3, and 4D printing will be introduced, for fabrication of objects composed of hybrid materials, ceramics, glass, shape memory polymers, elastomers and hydrogels. Examples of applications of these materials will be presented, such as in soft robotics, drug delivery systems, 3D electrical circuits, responsive connectors, and medical devices.
  • seminar
    Date:
    24 December
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    Depsipeptides and RNA: from molecules to early interactome

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Moran Frenkel-Pinter
    NASA Postdoctoral Fellow | Hud, Grover and Williams Labs NSF/NASA Center for Chemical Evolution Georgia Institute of Technology | School of Chemistry and Biochemistry 901 Atlantic Drive | Atlanta, GA 30332
  • seminar
    Date:
    24 December
    2019
    Tuesday
    Hours:
    10:30

    Water-use strategies leading to resilience of pine trees to global climatic change

    Location: Sussman Family Building for Environmental Sciences
    participants: Yakir Preisler
    Department of Earth and Planetary Sciences Weizmann Institute of Science Department of Plant Sciences and Genetics in Agriclture The Hebrew University of Jerusalem
  • seminar
    Date:
    22 December
    2019
    Sunday
    Hours:
    11:00

    Study of S isotope values of specific organic and inorganic S compounds in immature organic rich sediments

    Location: Sussman Family Building for Environmental Sciences
    participants: Lubna Shawar
    The Hebrew University of Jerusalem

    Abstract

    The preservation of the organic matter (OM) occurs as a result of post-depositional abiotic sulfurization, condensation and polymerization processes that convert the OM into stable macromolecular material termed kerogen. Different sulfurization processes, pathways and rates affect the 34S values of organic and inorganic S compounds. These sulfurization processes are affected by the redox conditions and paleo-environmental conditions (e.g. organic matter and Fe availability). Therefore, studying the organic and inorganic S distribution and their associated 34S values could be useful for understanding the paleo-environmental history associated with the deposition of ancient organic rich sediments. Until recently, only bulk phases of S could be measured for their 34S values, usually excluding organic S. A new method was developed that allows for S isotope analysis of specific organic S compounds (OSCs) at the sub- nanogram level. In my talk I will give an overview about the utility of compound specific S isotope analysis (CSSIA) for the study of different geochemical environments (e.g., immature organic rich sediments). Applying CSSIA to immature organic rich sediments from the Monterey and Ghareb formations I will show the combination of biomarkers and their S isotope composition in a single analysis. This provides a more detailed and in-depth understanding of the S and C cycles than bulk measurements of organic and inorganic S species alone.
  • seminar
    Date:
    19 December
    2019
    Thursday
    Hours:
    15:00

    Chemical and Biological Physics Guest Seminar

    Location: Perlman Chemical Sciences Building
    participants: Prof. Aharon Brodutch
    University of Toronto

    Abstract

    Quantum theory has been incredibly successful at explaining known phenomena and making new predictions that have led to some of the most important scientific and technological breakthroughs in the past century. Quantum computers are arguably the boldest prediction of the theory, but the level of control required to build them is extremely challenging. The requirements for building universal fault tolerant quantum computers (i.e computers that can run any quantum algorithm with high accuracy) are far beyond current capabilities, but less powerful (intermediate) quantum machines are already available, with some accessible online. The minimal requirements for such intermediate machines to significantly outperform ordinary (classical) computers is currently an open area of research. One approach to study the capabilities of intermediate quantum machines, is to study how small subsystems become correlated (and entangled) during a computation. I will provide an overview of work in this direction with some surprising results on the possible role of quantum entanglement. These results provide new insights into quantum theory and quantum technology.
  • seminar
    Date:
    19 December
    2019
    Thursday
    Hours:
    09:30
    -
    10:30

    Simulating the whole of magnetic resonance

    Location: Perlman Chemical Sciences Building
    participants: Prof. Ilia Kuprov
    University of Southampton, UK

    Abstract

    In a couple of years from now, we will finish kernel programming for Spinach – a spin dynamics simulation library that supports all types of magnetic resonance spectroscopy, from Gd3+ DEER, through DNP and NMR, and all the way to singlet state diffusion MRI, including chemical kinetics, optimal control, and advanced relaxation theories. This level of generality hinges on: 1. The ability to treat classical degrees of freedom (diffusion, hydrodynamics, radiofrequency and microwave phases, stochastic tumbling, etc.) at the same conceptual level as spin degrees of freedom – the corresponding classical equations of motion must be integrated into the density matrix formalism. 2. The ability to survive enormous Kronecker products. A well digitised medical phantom would have at least a hundred points in each of the three directions, meaning a dimension of at least 1003 = 106 for the spatial dynamics generator matrices. At the same time, a typical radical contains upwards of ten coupled spins, meaning a Liouville space dimension of at least 410. Direct products of spin and spatial dynamics generators would then have the dimension in excess of 1012 even before chemical kinetics is considered. 3. Code parallelisation over cluster architectures, including the possibility of using a GPU on each node of the cluster. The principal problem is parallelisation mode switching between powder averages, indirect dimensions of pulse sequences, frequency points of frequency domain simulations, etc. – each simulation type would in general require a different mode of parallelisation and GPU utilisation. This report is about solving all of this, and on where the dark art of simulating a time-domain magnetic resonance experiment stands at the moment. Two recent innovations are the abandonment of Liouville equation in favour of Fokker-Planck equation as the core formalism, and the use of tensor structured objects that never open Kronecker products. A separate story is recent GPUs: NVidia Tesla V100 performs ~1013 double-precision multiplications per second – an astounding amount of computing power that is surprisingly easy to use.
  • seminar
    Date:
    18 December
    2019
    Wednesday
    Hours:
    11:00
    -
    12:00

    At the Interface between Organic and Inorganic Matter: Interactions and Design of Simple Functional Coatings

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Meital Reches
    Institute of Chemistry, HUJI

    Abstract

    Several natural processes are mediated by the interactions between organic and inorganic materials. The immune response towards an implant inserted into the body is mediated by proteins. Composite materials are formed by the interactions of organic materials (usually proteins) and minerals. Biofouling, the process in which organisms attached to surfaces, is also mediated by organic molecules. Understanding the nature of interactions between organic and inorganic materials will bring to the development of improved implants, new composites and antifouling materials. This lecture will present single-molecule force spectroscopy measurements of the interactions between individual biomolecules (either amino acid residues or short peptides) and inorganic surfaces in aqueous solution. Using this method, we were able to measure low adhesion forces and could clearly determine the strength of interactions between individual amino acid residues and inorganic substrates. Our results with peptides also shed light on the factors that control the interactions at the organic-inorganic interface. Based on our knowledge from single molecule experiments, we designed a short peptide (tripeptide) that can spontaneously form a coating that resists biofilm formation. Our results clearly demonstrate the formation of a coating on various surfaces (glass, titanium, silicon oxide, metals and polymers). This coating prevents the first step of antifouling, which involves the adsorption of bioorganic molecules to the substrate. In addition, it significantly reduces the attachment of various organisms such as bacteria and fungi to surfaces. Another variation of this peptide can encourage the adhesion of mammalian cells while preventing biofilm formation.
  • seminar
    Date:
    17 December
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    Metal-binding as a new approach for peptoids folding and self assembly

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Galia Ma'ayan
    Technion, Haifa
  • seminar
    Date:
    16 December
    2019
    Monday
    Hours:
    14:00
    -
    15:00

    "A Stochastic approach to thermal density functional theory"

    Location: Perlman Chemical Sciences Building
    participants: Dr. Yael Cytter
    Faculty of Chemistry, HUJI

    Abstract

    abstract Warm dense matter (WDM) is state of matter characterized by temperatures of the order of 10,000 K and nuclear densities of magnitude significantly higher than those found in ordinary condensed matter. WDM is found in many fields of physics, chemistry, planetary sciences, and even industry: stellar and planetary science, laser-induced chemical processes in solids and on surfaces as well as plasma physics. Nowadays, using intense lasers, WDM properties can be investigated in the laboratory, thus requiring attention to theoretical research for interpretation and understanding of the results. The theoretical description of the regime is complex, being the intermediate between condensed matter physics (i.e., quantum description) and plasma physics (classical thermodynamics). WDM is often described theoretically using finite-temperature Kohn-Sham (KS) density functional theory (DFT) calculations, with reasonably good agreement to experiments. These calculations in finite (non-zero) temperatures are costly due to the large number of fractionally occupied KS orbitals that are involved. The computational cost exhibits cubic scaling with temperature. Stochastic density functional theory (sDFT), developed recently [1,2,3] appears to be a viable approach to WDM since it is “orbital-free” and yet fully KS. The sDFT approach uses the Fermi Dirac occupation operator to calculate the energy, and finds the electronic density and other expectation values by executing the trace in a stochastic way using random orbitals; in doing so, it skips over the step of calculating the KS orbitals. We further use the stochastic trace formula to calculate the conductivity based on Kubo-Greenwood formula. In the talk, convergence of the free energy will be discussed, as well as calculations of equations of states and statistical convergence of the conductivity when calculated based on stochastic thermal DFT. Transition to metallization in he-h systems was seen in temperature of ~60kK using the stochastic approach. [1] R. Baer, D. Neuhauser, E. Rabani, Phys. Rev. Lett. 111, 106402 (2013) [2] Y. Cytter, E. Rabani, D. Neuhauser, and R. Baer Phys. Rev. B 97, 115207 (2018) [3] Yael Cytter, Eran Rabani, Daniel Neuhauser, Martin Preising, Ronald Redmer, and Roi Baer Phys. Rev. B 100, 195101 (2019)
  • seminar
    Date:
    15 December
    2019
    Sunday
    Hours:
    19:00
    -
    20:30

    “Yad Vashem” More than just a name

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Rachel Karni

    Abstract

    Archival documents from the Ukraine have only recently become available in Israel. These amazing documents (from the years 1880-1936) have enabled the preparation of pages of testimony for Yad Vashem – pages which serve as the sole memory for Jews who perished in the Holocaust. Rachel Karni has spent much time over the last three years researching the town that her mother came from. From the information gathered, she has been able to compile pages of testimony for people about whom almost nothing, except their names and the fact that they had been murdered, had been known previously. Rachel will speak about the results of her very interesting detective work. The methodology she employed can be replicated for other places. Originally from New Jersey, USA, Rachel lives in Merkaz Shapira and was, for many years, the head of the English Department at the Shafir Religious High School.
  • seminar
    Date:
    15 December
    2019
    Sunday
    Hours:
    11:00

    Evaporation from the ocean: A new Lagrangian model and its application to observations

    Location: Sussman Family Building for Environmental Sciences
    participants: Natan Paldor
    The Hebrew University of Jerusalem
  • seminar
    Date:
    15 December
    2019
    Sunday
    Hours:
    11:00
    -
    12:00

    Topological defects in the actin cytoskeleton as organizing centers of Hydra morphogenesis

    Location: Perlman Chemical Sciences Building
    participants: Prof. Kinneret Keren
    Physics Department, Technion

    Abstract

    Morphogenesis is one of the most remarkable examples of biological self-organization. Despite substantial progress, we still do not understand the organizational principles underlying the convergence of this process, across scales, to form viable organisms. We focus on the mechanical aspects of morphogenesis using Hydra, a small multicellular fresh-water animal, as a model system. Hydra has a simple body plan and is famous for its ability to regenerate its whole body from small tissue segments. I will show that the nematic order of the supra-cellular actin fibers in regenerating Hydra defines a coarse-grained field, whose dynamics provide an effective description of the morphogenesis process, with the topological defects in the nematic order acting as effective organizing centers. I will further describe our attempts to directly probe the influence of mechanics on morphogenesis, by applying various external mechanical constraints on regenerating Hydra.
  • seminar
    Date:
    12 December
    2019
    Thursday
    Hours:
    10:00
    -
    11:00

    In vivo multimodality imaging of immune-vascular interactions in cardiovascular disease

    Location: Perlman Chemical Sciences Building
    participants: Prof. Katrien Vandoorne
    Eindhoven University of Technology (The Netherlands), Department of Biomedical Engineering, Soft Tissue Engineering

    Abstract

    Cardiovascular disease is a result of genetic and environmental risk factors that together generate arterial and cardiac pathologies. Blood vessels connect multiple organ systems throughout the entire body allowing organs to interact via circulating messengers. Multimodality imaging achieves integration of these interfacing systems’ distinct processes, quantifying interactions that contribute to cardiovascular disease. Noninvasive multimodality imaging techniques are emerging tools that can further our understanding of this complex and dynamic interplay. Multichannel multimodality imaging including optics, CT, PET and MRI, are particularly promising because they can simultaneously sample multiple biomarkers. As the opportunities provided by imaging expand, mapping interconnected systems will help us decipher the complexity of cardiovascular disease and monitor novel therapeutic strategies.
  • seminar
    Date:
    10 December
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    Tracking proteins' conformations inside cells with Gd(III) spin labels

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Daniella Goldfarb
    Department of Chemical and Biological Physics, WIS
  • seminar
    Date:
    10 December
    2019
    Tuesday
    Hours:
    11:00
    -
    12:00

    Molecular errors and evolvability

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Joanna Masel
    Ecology and Evolutionary Biology, The University of Arizona, USA
  • seminar
    Date:
    9 December
    2019
    Monday
    Hours:
    14:00
    -
    15:00

    Trapped on the ribosome: exploring the chemical biology of translational control

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Jack Taunton
    Dept. of Cellular and Molecular Pharmacology, University of California, San-Francisco
  • seminar
    Date:
    5 December
    2019
    Thursday
    Hours:
    09:30
    -
    10:30

    Augmented methods for measuring one-bond heteronuclear spin pairs over a wide range of MAS frequencies

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Mukul Jain
    WIS-TATA institute of Fundamental Research, Hyderabad

    Abstract

    Measuring quantitative distances are important for studying the structural properties of molecules at an atomic scale. Dipole-dipole coupling encodes for distance information between spin pairs. Additionally, the anisotropy of dipole-dipole coupling is also very sensitive to the sub-microsecond dynamics occurring in the molecules, and therefore can be used to estimate it. Rotational Echo Double Resonance (REDOR) and Correlation of Dipolar coupling and Chemical shift (DIPSHIFT) experiments are the most preferred experiments for measuring distances between a heteronuclear spin pair using Magic angle spinning (MAS) solid-state NMR. But these experiments can be used only for a small range of coupling strengths depending on the MAS frequency of the experiment. In the talk, I will discuss the latest developments we have made for measuring a wide range of coupling strengths using REDOR over a wide range of MAS frequencies. Further, I will also show that REDOR and DIPSHIFT are different realizations of a same experiment and this unification comes naturally out of our augmented REDOR sequence. Further, I will discuss a method to perform REDOR experiments with low radiofrequency amplitude pulses at MAS frequencies larger than 80~kHz. This method extends the application of REDOR and DIPSHIFT at very fast MAS frequencies, where the radiofrequency amplitude requirement becomes too high for nuclei other than 1H. Overall, the methods discussed here allow for measuring dipole-dipole coupling between heteronuclear spin-pairs over a wider range of MAS frequencies. References: 1. T. Gullion and J. Schaefer, Journal of Magnetic Resonance, 1989. 2. M. G. Munowitz et al., Journal of American Chemical Society, 1981. 3. M. Hong et al., Journal of Magnetic Resonance, 1997. 4. P. Schanda et al., Journal of Magnetic Resonance, 2019. 5. M. G. Jain et al., Journal of Chemical Physics, 2017. 6. M. G. Jain et al., Journal of Chemical Physics, 2019. 7. M. G. Jain et al., Journal of Magnetic Resonance, 2019.
  • seminar
    Date:
    3 December
    2019
    Tuesday
    Hours:
    15:00
    -
    16:00

    The Braginsky Center for the Interface between the Sciences and the Humanities

    Location: Dolfi and Lola Ebner Auditorium
    participants: Prof. Yadin Dudai
    Department of Neurobiology, WIS

    Abstract

    From the vantage point of the Science of Memory, human cultures can be considered as 'biocultural supraorganisms' that can store distributed experience-dependent, behaviorally-relevant representations over hundreds and thousands of years. I will describe cognitive and artefactual instruments that mediate encoding, consolidation, storage and retrieval of such cross-generational collective engrams in large human populations. Investigation of this type of long-duration memory is made possible by combining archeology, history and cognitive science. I will focus on a model system for the analysis of long-duration cultural memory. This is the memory of the Jewish culture, that can be traced back ca. 3300 yr (i.e. ca. 130 generations) ago. I will zoom in on the core memory of this culture, i.e., the minimal set of cross-generational mnemonic items considered by members of that culture to define their collective origin, history and distinctiveness. Identifying a core memory item and tracing its fate over time can facilitate mechanistic understanding of remote as well as more recent collective memory. I will present data and hypotheses concerning the encoding, transformation, persistence and reactivation of an early component of the core memory, that had amalgamated fact with fiction in its first ca. 1000 yrs before being put in writing ca. 2300 yrs ago in an information-dense text of only 63 Hebrew words. Its high-fidelity persistence relied on evolving procedural reactivations. Potential implications of this persistence mechanism for understanding remote memory in individuals will be discussed. In recent generations reactivation of this memory and its updating play a role in splitting Jewish cultural memory into sub-narratives that differ, inter alia, in geographical distribution and cultural signature. This enables data-based analysis of ongoing transformation of collective memory in a large distributed human population
  • seminar
    Date:
    3 December
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    Molecular basis of neuronal self-avoidance

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Rotem Rubinstein
    Tel-Aviv University
  • seminar
    Date:
    3 December
    2019
    Tuesday
    Hours:
    11:00
    -
    12:00

    The Importance of Mechanistic Understanding for Developing Novel Umpolung Reactions and Solar Induced Processes

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Alex M. Szpilman
    Department of Chemical Sciences, Ariel University
  • seminar
    Date:
    1 December
    2019
    Sunday
    Hours:
    11:00

    Using cosmogenic 21Ne to quantify sediment residence time in large-scale fluvial systems throughout the geological record

    Location: Sussman Family Building for Environmental Sciences
    participants: Michal Ben-Israel
    The Hebrew University of Jerusalem

    Abstract

    Rivers are the most effective agent of erosion on earth, transporting massive amounts of detrital and dissolved matter into depositional basins, making them a significant part of the rock cycle. To better understand the relationship between denudation of continents and the rivers that drain them, numerous studies examine the pathways of sediment transport through large drainage systems. However, due to the complex nature of sediment storage and transport dynamics in large-scale fluvial systems, the amount of time sediment spends in the sedimentary system is poorly constrained. We measured cosmogenic 21Ne to quantify the exposure time of sediments within large-scale fluvial systems in large rivers: the modern Colorado river, the Miocene Hazeva River (~18 Ma), and the Lower Cretaceous (~130 Ma) Kurnub fluvial system. We observe that fluvial transport dynamics in large rivers are complex and that sediment transport time varies significantly and can last between very rapid (faster than our analytical measurement limitation ~103 yr) and 105 yr. To better understand the nature of fluvial transport dynamics in large rivers, we constructed a stochastic model that simulates repeated episodes of burial and exposure and examines the changes in concentrations of cosmogenic 26Al, 10Be, and 21Ne. We compared the simulated results to the concentrations measured in the Colorado River, and we predict that the total that sediment spent both buried and exposed – the residence time in large rivers is ~103-105 years. These observations suggest that the time-scales of sediment transport in large rivers have not changed significantly over the past 130 Myr and have remained significantly fast compared to other processes in the rock-cycle.
  • seminar
    Date:
    28 November
    2019
    Thursday
    Hours:
    09:30
    -
    10:30

    Preclinical Imaging using Electron Paramagnetic Resonance

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Boris Epel
    Department of Radiation & Cellular Oncology, University of Chicago

    Abstract

    Electron Paramagnetic Resonance (EPR) Imaging is a well-established method for the study of spatial distribution and local environment of electron paramagnetic centers and spin probes. One of the most important applications of modern EPR imaging is in vivo oximetry in which soluble spin probes with oxygen-dependent relaxation rates are used. Partial oxygen pressure (pO2) levels in tumors are major determinants of the response to cancer therapy. I will present the results of the in vivo oxygen guided radiation targeting study. This study combines pO2 images and conformal radiation delivery using 3D-printed blocks to achieve high precision treatment of tumor hypoxic areas. The study demonstrates that the dose to well-oxygenated tumor volumes in fibrosarcoma tumors in mice can be considerably reduced without compromising the outcome.
  • seminar
    Date:
    27 November
    2019
    Wednesday
    Hours:
    13:30
    -
    14:30

    A Photodynamical Model for Uniform and Precise Planetary Parameters Determination in Kepler Systems

    Location: Sussman Family Building for Environmental Sciences
    participants: Gidi Yoffe
    Department of Earth and Planetary Sciences Weizmann Institute of Science
  • seminar
    Date:
    26 November
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    Structural design principles for specific RGS-G protein interactions

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Mickey Kosslof
    Haifa University
  • seminar
    Date:
    26 November
    2019
    Tuesday
    Hours:
    11:00
    -
    12:00

    Controlling fluorescence in photochromic systems: From on–off switching to full-color reproduction

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Joakim Andréasson
    Department of Chemistry and Chemical Engineering Chalmers University of Technology

    Abstract

    Energy transfer through the Förster mechanism, often referred to as FRET, depends critically on the overlap between the emission of the donor chromophore and the absorption of the acceptor chromophore. When photochromic molecules (molecular photoswitches) are isomerized between the two forms, the absorption spectra typically experience dramatic changes. Also, some photoswitches display emission exclusively in one isomeric form. This opens up the possibility to switch the capacity to act as both donor- and acceptor units, and hence, also to control energy transfer processes with concomitant changes in the fluorescence pattern. In addition to the abovementioned spectral features, the rate of the FRET process is highly dependent on the distance between the donor and the acceptor. This parameter can also be varied using molecular photoswitches, in the making/breaking of supramolecular complexes, which in turn dramatically changes the donor-acceptor distance and the FRET efficiencies. In this presentation, I will give examples of how the both these approaches can be used to tune the emissive properties of photochromic constructs. From trivial fluorescence “on-off” switching, via directional switching, to systems displaying full-color reproduction.
  • seminar
    Date:
    26 November
    2019
    Tuesday
    Hours:
    11:00
    -
    12:00

    Internal Waves in the Ocean - what we know, and what we don't

    Location: Sussman Family Building for Environmental Sciences
    participants: Yuri V Lvov
    Rensselaer Polytechnic Institute
  • seminar
    Date:
    24 November
    2019
    Sunday
    Hours:
    11:00

    Isotopic diagenesis of biogenic silica in marine sediments and implications for Cenozoic climate

    Location: Sussman Family Building for Environmental Sciences
    participants: Anastasia Yanchilina
    Department of Earth and Planetary Sciences Weizmann Institute of Science

    Abstract

    The oxygen isotopic signature of marine deep-sea cherts was previously used to reconstruct past ocean temperature and bottom water δ18O through the Cenozoic and Mesozoic periods. Oxygen isotopes of deep-sea cherts, which were never exposed to meteoric water, exhibit a wide range of values indicating that the evolution and maturation of biogenic amorphous opal (opal-A) to opal-CT and microquartz chert is accompanied by isotopic changes. We measured δ18O of diatom opal-A, opal-CT, and microquartz chert from deep sea cores retrieved from the Japan Sea. The δ18O of opal-CT and microquartz chert phases correspond to the depth in the sediments where these transitions occur, ~400 m and 40 °C for opal-A to opal-CT and ~500 m and 60 °C for opal-CT to microquartz chert. The δ18O values of opal-CT and microquartz chert appear to reflect equilibrium formation temperatures of silica, corresponding to the geothermal gradient and the local porewater δ18O. The δ18O of opal-CT and microquartz chert are controlled by the geothermal gradient and compositions of pore waters during polymorphic transformations deep within the sediment, indicating that the δ18O of these phases cannot be used to determine temperature or composition of seawater during diatom growth. Opal-A is the most susceptible phase for isotope alteration. We separated opal-A (i.e., diatoms, radiolaria, and siliceous sponge spicules) of Cenozoic age and measured its isotope composition. The results do not indicate any significant change in δ18O. This will be discussed within the general framework of global climatic change.
  • seminar
    Date:
    20 November
    2019
    Wednesday
    Hours:
    11:00
    -
    12:00

    Application of Electron Crystallography Methods in Metallurgy

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Louisa Meshi
    Dept. of Materials Engineering, Ben-Gurion University of the Negev

    Abstract

    Due to the direct correlation among the physical properties and crystal structure of materials, study of the latter is crucial for fundamental understanding of the properties. In the era of nano-science, objects of interest are getting smaller and traditional single-crystal and powder X-ray diffraction methods cannot be applied for characterization of their atomic structures due to the unavailability of single crystals and/or small quantity and size of these crystals in the multiphase specimens. Thus, electron crystallography (EC) (which is defined as a combination of electron diffraction and imaging methods) is sometimes the only viable tool for the analysis of their structure. In the previous century, electron diffraction (ED) was considered to be unsuitable for structure determination due to the problems of data quality arising from dynamical effects. At the last decades, researchers have shown that influence of dynamical effects can be substantially reduced if beam precession (PED) is used and/or data collection is performed in the off-axis conditions - enabling solution of atomic structures with various complexity (from inorganics to proteins). Our group focuses on development and application of EC methods for structure solution of nano-sized precipitates and characterization of structural defects in steels and light alloys. This study is technologically essential since precipitates and defects dictate physical properties of these structural materials. It must be noted that, atomic structures of intermetallics were not solved previously using solely ED methods. Reason for that is in the nature of intermetallic compound's structures. Contrarily to other complex materials, the atomic distances and angles of intermetallics are not fixed and coordination polyhedra are usually unknown. Thus, structure solution of these compounds is harder to validate. In the present seminar, contribution of our group in the development of routine structure solution path for aluminides (as an example of intermetallics) will be presented. In addition, characterization of structural defects, influencing the performance of the studied materials, will be shown.
  • seminar
    Date:
    19 November
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    Integrating 3D structure into Systems Biology

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Barry Honig
    Columbia University
  • seminar
    Date:
    19 November
    2019
    Tuesday
    Hours:
    11:00
    -
    12:00

    Chemical Physiology of Antibody Conjugates and Natural Products

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Goncalo Bernardes
    Department of Chemistry, University of Cambridge, UK

    Abstract

    Our research uses chemistry principles to address questions of importance in life sciences and molecular medicine. This lecture will cover recent examples of emerging areas in our group in: (i) methods developed for site-selective chemical modification of proteins at cysteine, disulfide and lysine and their use to build stable and functional protein conjugates for in vivo applications [1–4] (ii) bioorthogonal cleavage reactions for targeted drug activation in cells [5,6] (iii) by identifying on- and off-targets for anti-cancer entities using our own machine intelligence platform, unveiling the underlying molecular mechanisms of target recognition and linking drug target binding to modulation of disease, we explore the use of natural products as selective cancer modulators [7] Recent Publications: 1. Bernardim B; Cal PMSD; Matos MJ; Oliveira BL; Martínez-Sáez N; Albuquerque IS; Corzana F; Burtoloso ACB; Jiménez-Osés G; Bernardes GJL* Stoichiometric and Irreversible Cysteine-selective Protein Modification using Carbonylacrylic Reagents. Nat. Commun. 2016, 7, 13128. 2. Martínez-Saez N; Sun S; Oldrini D; Sormanni P; Boutureira O; Carboni F; Compañón I; Deery MJ; Vendruscolo M; Corzana F; Adamo R; Bernardes GJL* Oxetane Grafts Installed Site-Selectively on Native Disulfides to Enhance Protein Stability and Activity In Vivo. Angew. Chem. Int. Ed. 2017, 47, 14963–14967. 3. Freedy AM; Matos MJ; Omar Boutureira O; Corzana F; Guerreiro A; Somovilla VJ; Rodrigues T; Nicholls K; Xie B; Jiménez-Osés G; Brindle KM; Neves AA; Bernardes GJL* Chemoselective Installation of Amine Bonds on Proteins Through Aza-Michael Ligation. J. Am. Chem. Soc. 2017, 139, 18365–18375. 4. Matos MJ; Oliveira BL; Martínez-Sáez N; Guerreiro A; Cal PMSD; Bertoldo J; Maneiro M; Perkins E; Howard J; Deery MJ; Chalker JM; Corzana F; Jiménez-Osés G; Bernardes GJL* Chemo and regioselective lysine modification on native proteins. J. Am. Chem. Soc. 2018, 140, 4004–4017. 5. Stenton BJ; Oliveira BL; Matos MJ; Sinatra L; Bernardes GJL* A Thioether-directed Palladium-cleavable Linker for Targeted Bioorthogonal Drug Decaging. Chem. Sci. 2018, 9, 4185–4189. 6. Sun S; Oliveira BL; Jiménez-Osés G; Bernardes GJL* Radical-mediated thiol-ene strategy for photoactivation of thiol-containing drugs in cancer cells. Angew. Chem. Int. Ed. 2018, DOI: 10.1002/anie.201811338. 7. Rodrigues T; Werner M; Roth J; da Cruz EHG; Marques MC; Akkapeddi P; Lobo SA; Koeberle A; Corzana F; da Silva Júnior EN; Werz O; Bernardes GJL* Machine intelligence decrypts β-lapachone as an allosteric 5-lipoxygenase inhibitor. Chem. Sci. 2018, 9, 6885–7018.
  • seminar
    Date:
    18 November
    2019
    Monday
    Hours:
    10:00
    -
    11:00

    Chemical and Biological Physics Dept Seminar

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Omar Arana
    Liquid phase separation of proteins controlled by pH

    Abstract

    In the past decade, liquid phase separation has been proposed as a mechanism for intracellular organization. It has been shown that many proteins phase-separate and form liquid-like drops. These liquid-like compartments provide a distinct biochemical environment inside of the cell and sometimes form as a response to changes in the intracellular environment. In particular, a decrease in the pH of the cytosol of yeast cells leads to widespread macromolecular assembly. Inspired by this experimental observation, we construct a minimal model to study this pH-responsive mechanism. The model consists of a macromolecular mixture in which macromolecules can exist in different charge states and have a tendency to phase-separate. In order to assess the effect of pH on phase separation, we introduce protonation and deprotonation reactions, which are controlled by the pH of the mixture. Using this model, we construct phase diagrams at the isoelectric point of the system and then study what happens when the pH is moved away from the isoelectric point. We find that under most conditions, the broadest region of phase separation is located at the isoelectric point. Interestingly, our minimal model also predicts reentrant behavior as a function of pH. We conclude by discussing the predictions of our model in light of experimental observations on protein phase separation, showing that they are in agreement.
  • seminar
    Date:
    17 November
    2019
    Sunday
    Hours:
    11:00

    A universal rank-order transform to extract signals from noisy data

    Location: Sussman Family Building for Environmental Sciences
    participants: Alex Kostinski
    Michigan Technological University
  • seminar
    Date:
    13 November
    2019
    Wednesday
    Hours:
    11:00
    -
    12:00

    Application of Electron Crystallography Methods in Metallurgy

    Location: Perlman Chemical Sciences Building
    participants: Prof. Louisa Meshi
    Department of Materials Engineering, Ben-Gurion University of the Negev

    Abstract

    Due to the direct correlation among the physical properties and crystal structure of materials, study of the latter is crucial for fundamental understanding of the properties. In the era of nano-science, objects of interest are getting smaller and traditional single-crystal and powder X-ray diffraction methods cannot be applied for characterization of their atomic structures due to the unavailability of single crystals and/or small quantity and size of these crystals in the multiphase specimens. Thus, electron crystallography (EC) (which is defined as a combination of electron diffraction and imaging methods) is sometimes the only viable tool for the analysis of their structure. In the previous century, electron diffraction (ED) was considered to be unsuitable for structure determination due to the problems of data quality arising from dynamical effects. At the last decades, researchers have shown that influence of dynamical effects can be substantially reduced if beam precession (PED) is used and/or data collection is performed in the off-axis conditions - enabling solution of atomic structures with various complexity (from inorganics to proteins). Our group focuses on development and application of EC methods for structure solution of nano-sized precipitates and characterization of structural defects in steels and light alloys. This study is technologically essential since precipitates and defects dictate physical properties of these structural materials. It must be noted that, atomic structures of intermetallics were not solved previously using solely ED methods. Reason for that is in the nature of intermetallic compound's structures. Contrarily to other complex materials, the atomic distances and angles of intermetallics are not fixed and coordination polyhedra are usually unknown. Thus, structure solution of these compounds is harder to validate. In the present seminar, contribution of our group in the development of routine structure solution path for aluminides (as an example of intermetallics) will be presented. In addition, characterization of structural defects, influencing the performance of the studied materials, will be shown.
  • seminar
    Date:
    12 November
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    Bio-structural insights from solid state NMR: The small (Lithium) and the large (Phage)

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Amir Goldbourt
    Tel Aviv University
  • seminar
    Date:
    10 November
    2019
    Sunday
    Hours:
    14:00

    Kepler's Multiple Planet Systems

    Location: Sussman Family Building for Environmental Sciences
    participants: Jack Lissauer
    NASA Ames Research Center

    Abstract

    More than one-third of the 4000+ planet candidates found by NASA’s Kepler spacecraft are associated with target stars that have more than one planet candidate, and such “multis” account for the vast majority of candidates that have been verified as true planets. The large number of multis tells us that flat multiplanet systems like our Solar System are common. Virtually all of the candidate planetary systems are stable, as tested by numerical integrations that assume a physically motivated mass-radius relationship. Statistical studies performed on these candidate systems reveal a great deal about the architecture of planetary systems, including the typical spacing of orbits and flatness. The characteristics of several of the most interesting confirmed Kepler & TESS multi-planet systems will also be discussed.
  • seminar
    Date:
    7 November
    2019
    Thursday
    Hours:
    14:30
    -
    15:30

    Special Seminar

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Kyoko Nozaki
    Department of Chemistry and Biotechnology. School of Engineering, The University of Tokyo

    Abstract

    Transition-metal mediated bond cleavage and formation has made a great contribution in synthetic organic chemistry. A metal-ligand cooperativity often plays essential roles in the bond cleavage and formation reactions. Shvo and Casey studied the heterolytic cleavage/formation of H–H bond mediated by cyclopentadienone metal complexes with simultaneous oxidation/reduction of the central metal. Here in this presentation, this cooperativity is applied to the new type of bond cleavage/formation reactions such as C–O, C–H, and B–H Bonds.
  • seminar
    Date:
    7 November
    2019
    Thursday
    Hours:
    09:30
    -
    10:30

    How Metal Ions in the Brain Tip the Toxic Balance of the Killer Prion Protein: Insights from NMR and EPR”

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Glenn L. Millhauser
    Department of Chemistry & Biochemistry University of California, Santa Cruz

    Abstract

    A prion is a misfolded form of the cellular prion protein, PrPC. Although the role of PrP in neurodegeneration was established over 30 years ago, there is little understanding of the protein’s normal function, and how misfolding leads to profound disease. Recent work shows that PrPC coordinates the cofactors Cu2+ and Zn2+, and regulates the distribution of these essential metal ions in the brain. Moreover, these metals stabilize a previously unseen fold in PrPC, the observation of which provides new insight into the mechanism of prion disease. To date, Cu2+ coordination was thought to be limited to residues within the protein’s N-terminal domain. However, new NMR and EPR experiments suggest that histidine residues in the C-terminal domain assist in stabilizing the Cu2+-promoted PrPC fold. This talk will describe combined NMR, EPR, mutagenesis and physiological studies that provide new insight into the PrPC fold and function.
  • seminar
    Date:
    6 November
    2019
    Wednesday
    Hours:
    11:00
    -
    12:00

    Boron subphthalocyanines and subnaphthalocyanines for organic photovoltaics

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Tim Bender
    Department of Chemical Engineering and Applied Chemistry University of Toronto

    Abstract

    For some time, our group has been focused on the design, synthesis and application of derivatives of boron subphthalocyanines (BsubPcs), a macrocyclic molecule with chelated central boron atom. Our focal point has been and continues to be equally balanced between the basic and applied chemistry of BsubPcs, their application as light absorbing and electronic conducting materials in organic photovoltaics (OPVs)/solar cells. For this presentation I will outline how we have developed BsubPcs for their application in OPVs and other organic electronic devices. For OPVs, we have developed an approach to their development whereby their basic and applied chemistry is justified by a development cycle which includes their physical chemistry and characterization, their immediate integration into OPVs and based on their indoor stability are placed in the ambient environment to truly address their ultimate application in organic solar cells. Integrated into this cycle is a computational modeling methodology that is used to screen potential BsubPcs for their application in organic electronic devices including OPVs/organic solar cells. Most recently we have identified a pathway to BsubPcs whereby all carbons are bio-sourced and I will highlight how the computational model justified the time and resource commitment to their synthesis and development. In addition to BsubPcs, we have taken an equal approach to extended -conjugated derivatives of BsubPcs, boron subnaphthalocyanines (BsubNcs); BsubNcs being unique and beneficial materials for OPV application. We have shown that BsubNcs actually become randomly chlorinated during their synthetic preparation and actually then form a mixed alloy composition of chlorinated materials, which we have designated as Cl-ClnBsubNcs. The mixed alloy composition is unique, and has been determined to be a mixture of 24 (more or less) chlorinated BsubNcs despite being a mixture that uniquely forms single crystals. The formation of single crystals is enabled by the chlorine atoms occupying vacancies within the solid state structure, the vacancies being the so-called “bay position” of the BsubNcs structure. During this presentation I will highlight how odd the mixed alloy composition of organic materials is and how hard it has been to separate the mixed alloyed composition. I will also highlight how we are moving forward with purposefully making mixed alloyed compositions of our macrocyclic compounds BsubPcs and BsubNcs fully justified by the potential performance increase in organic solar cells. Co-authors/investigators will be identified during this presentation. #-- Some Relevant References. [1] “Outdoor Performance and Stability of Boron Subphthalocyanines Applied as Electron Acceptors in Fullerene-Free Organic Photovoltaics.” Josey, D.; et al, ACS Energy Lett., 2017, 2(3), 726–732. DOI: 10.1021/acsenergylett.6b00716. [2] “Boron Subphthalocyanines as Electron Donors in Outdoor Lifetime Monitored Organic Photovoltaic Cells.” Garner, R.K.; et al, Solar Energy Materials and Solar Cells, 2018 176, 331-335. DOI: 10.1016/j.solmat.2017.10.018 [3] “8.4% efficient fullerene-free organic solar cells exploiting long-range exciton energy transfer” Cnops, K.; et al., Nature Comm., 5, Article number: 3406, DOI:10.1038/ncomms4406. [4] “The mixed and alloyed chemical composition of chloro-(chloro)n-boron subnaphthalocyanines dictates their physical properties and performance in organic photovoltaics.” Dang, J.D.; et al, J. Mat. Chem. A., 2016, 4, 9566-9577. DOI: 10.1039/C6TA02457B [5] “Phenoxy-(chloro)n-boron subnaphthalocyanines; alloyed mixture, electron-accepting functionality, enhanced solubility for bulk heterojunction organic photovoltaics” Dang, J.D.; et al, ACS Omega, 2018, 3(2), 2093–2103. DOI: 10.1021/acsomega.7b01892. [6] “The Mixed Alloyed Chemical Composition of Chloro-(chloro)n-Boron Subnaphthalocyanines Dictates Their Performance as Electron-Donating and Hole-Transporting Materials in Organic Photovoltaics” Garner, R.K.; et al, ACS Appl. Energy Materials, 2017, 1(3), 1029-1036. DOI: 10.1021/acsaem.7b00180. [7] "Outdoor Stability of Chloro-(Chloro)n-Boron Subnaphthalocyanine and Chloro-Boron Subphthalocyanine as Electron Acceptors in Bilayer and Trilayer Organic Photovoltaics" Josey, D.; et al, ACS Applied Energy Materials, 2019, 2(2), 979–986. DOI:10.1021/acsaem.8b01918
  • seminar
    Date:
    5 November
    2019
    Tuesday
    Hours:
    14:00

    Cooperative folding of polyglutamine helices in transcriptional regulators

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Xavier Salvatella
  • seminar
    Date:
    3 November
    2019
    Sunday
    Hours:
    11:00
    -
    12:00

    Transmission Electron Microscopy in Motion

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Frances M. Ross
    Department of Materials Science and Engineering, MIT

    Abstract

    We can watch crystals grow in the electron microscope by adding atoms one at a time onto a clean surface. The movies tell us about kinetics and thermodynamics but can also be entertaining, frustrating, or both at the same time. I will attempt to share the joy of this type of “in situ” microscopy as we aim to understand how atoms assemble into nanowires or nanocrystals and use the information to control the formation of more complicated nanostructures with new properties
  • seminar
    Date:
    3 November
    2019
    Sunday
    Hours:
    11:00

    Ocean Worlds of the Outer Solar System: Life as we know it or life as we don’t?

    Location: Sussman Family Building for Environmental Sciences
    participants: Alex Hayes
    Associate Professor, Director, Cornell Center for Astrophysics and Planetarty Science, Director of the Spacecraft Planetary Image Facility

    Abstract

    Recent discoveries have shown that habitable environments likely exist in subsurface water oceans within the outer planet moons of Europa and Enceladus. On Titan, the largest moon of Saturn, lakes and seas of liquid hydrocarbon exist in addition to a vast subsurface water ocean. These places represent ideal locations for hydrothermal environments that could sustain life as we know it and, in Titan’s case, perhaps even life as we don’t. The next generation of uncrewed planetary spacecraft will be designed to search for the signs of life in one or more of these worlds. This lecture will begin with a brief review of the discoveries that have motivated a renewed importance for Ocean World exploration, before diving into Titan's lakes and seas to discuss recent findings related to its hydrocarbon-based hydrologic cycle and setting the stage for the newly selected Dragonfly quadcopter set to explore Titan in the mid 2030s.
  • seminar
    Date:
    31 October
    2019
    Thursday
    Hours:
    09:30
    -
    10:30

    Characterization of Biomolecule and Structure Changes using Polarization Transfer from Hyperpolarized Water

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Jihyun Kim
    Department of Chemistry ,Texas A&M University

    Abstract

    Nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical tool for the characterization of protein structure and intermolecular interactions. However, NMR is not readily applicable to determine fast structural changes and weak interactions between molecules because of low signal sensitivity and time requirements to record multi-dimensional NMR spectra. To overcome these limits, the hyperpolarization technique of dissolution dynamic nuclear polarization (D-DNP) is combined with NMR. Not all molecules can be directly hyperpolarized. Instead, polarization transfer from hyperpolarized small molecules to a target of interest can be utilized as a means of obtaining polarization, as well as for detecting intermolecular interactions between these molecules Here, hyperpolarized water-assisted NMR spectroscopy was developed to measure intermolecular interactions with water. Firstly, the use of DNP hyperpolarization was demonstrated for the accurate determination of intermolecular cross-relaxation rates between hyperpolarized water and fluorinated target molecules.[1] Because hyperpolarized water acts as a source spin with a large deviation of the population from the equilibrium, the 19F signal on the target molecules is enhanced through NOE, allowing obtain an entire NOE buildup curve in a single, rapid measurement. When the hyperpolarized water-assisted NMR experiment is applied to a protein, water hyperpolarization can be transferred to amide protons on the protein through proton exchange. Further, this polarization spreads within the protein through intramolecular NOE to nearby protons including aliphatic groups.[2] By utilizing this polarization transfer, this method extends to measure enhanced 2D NMR spectra of the protein under folded and refolding conditions.[3] With the ability to rapidly measure protein signals that were enhanced through transferred polarization from hyperpolarized water, NMR spectra can be acquired within the timescale of the protein folding. Compared to the folded protein experiment, signals attributed to exchange-relayed NOEs are not observable in the refolding experiment (Figure 1b). These differences are explained by the absence of long-range contacts with nearby exchangeable protons such as OH protons
  • seminar
    Date:
    29 October
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    Mass spectrometry reveals the chemistry of formaldehyde cross-linking in structured proteins

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Nir Kalisman
    Dept. of Biological Chemistry The Hebrew University
  • seminar
    Date:
    29 October
    2019
    Tuesday
    Hours:
    11:00
    -
    12:30

    "New Directions for Electricity and Fuels from Sunlight

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Harry Atwater
    Howard Hughes Professor and Professor of Applied Physics and Materials Science Director, Joint Center for Artificial Photosynthesis California Institute of Technology

    Abstract

    The recent rapid, global growth of photovoltaics has moved scientific research frontiers for solar energy conversion towards new opportunities including i) ultrahigh efficiency photovoltaics (η > 30%) and ii) direct synthesis of energy-dense chemical fuels from sunlight, including hydrogen and products from reduction of carbon dioxide. I will illustrate several examples of how design of materials for light harvesting, charge transport and catalytic selectivity can enable advances in electricity and fuel synthesis. Photonic design has opened new directions for high efficiency photovoltaics and luminescent solar concentrators. Semiconductors coupled to water oxidation and reduction catalysts have enabled approaches to photoelectrochemical solar-to-hydrogen generation with >19% efficiency using artificial photosynthetic structures. Solar-driven reduction of carbon dioxide presents both an enormous opportunity and challenge because of the need for selectivity in generating useful multi-carbon products by multiple electron and multi-proton transfer steps. Present work and future directions in selective photocatalytic and photo-electrocatalytic materials for artificial photosynthesis aimed at catalytic reduction of carbon dioxide will be discussed.
  • seminar
    Date:
    24 October
    2019
    Thursday
    Hours:
    14:00
    -
    15:00

    What limits the performance of halide perovskite solar cells

    Location: Perlman Chemical Sciences Building
    participants: Arava Zohar

    Abstract

    Halide Perovskites, HaPs, make up a group of semiconducting materials with excellent light absorption and good electrical charge transport properties, which is remarkable given their low-temperature solution preparation. In my Ph.D. research, I investigated fundamental optoelectronic properties of HaP semiconductors to elucidate dominant charge transport mechanisms, with emphasis on providing design tools for high-efficiency solar cells to help transform the renewable, solar energy landscape. I will show how I characterized Fermi level positions and studied the self-doping mechanism of different HaP materials by using a suite of in situ measurements. My main conclusion was that halide vacancy defects (surface, interface, or bulk) and electron sharing between oxygen and the HaP surface, drive Fermi level changes. The former had been postulated but not experimentally shown, until my work. By elucidating the electric field distribution and photovoltage losses I could show that Br-based HaP device efficiency is limited mainly by a (relatively) high defect density at the anode/semiconductor interface.
  • seminar
    Date:
    22 October
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    On the surface but not superficial: Towards a deeper understanding of membrane remodeling

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Ori Avinoam
    Department of Biomolecular Sciences WIS
  • seminar
    Date:
    22 October
    2019
    Tuesday
    Hours:
    11:30
    -
    12:00

    Towards Mass Spectrometry-Based Quantitative Clinical Proteomics

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Jose Luis Capelo Martinez
    FCT University NOVA of Lisbon – PORTUGAL

    Abstract

    The use of proteomics in the clinical arena has been traditionally hampered by low sample throughput and by difficulties in quantifying proteins in complex proteomes in an absolute manner. The use of ultrasonic energy to speed complex proteomics workflows for protein quantification along with thea advent of High Resolution Mass Spectrometry have made possible to treat and to analyze tens of samples a day, thus making mass spectrometry-based clinical proteomics a modern practical tool to be explored.
  • seminar
    Date:
    22 October
    2019
    Tuesday
    Hours:
    11:00
    -
    11:30

    Sensing and Recognition using Molecules and Nanomaterials: From toxic elements to Biomarkers

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Carlos Lodeiro
    FCT University NOVA of Lisbon – PORTUGAL

    Abstract

    We, humans and animals, feel the outside world thanks to our 5 senses. We hear, we see, we smell, we touch, and we taste. The success of our lives often depends on how sharp our senses are. In a scientific environment, sensing and feeling is also important. In chemistry, in biology, in medicine, in forensics, as in other areas, feeling, recognising, is crucial. In the present seminar, I will show some examples of the use of chromophores such as porphyrins, emissive peptides, rhodamines, liquid crystals-based metal complexes, fluorescein and others, free or supported in polymers, paper, and gold, silver, platinum nanoparticles, or messoporous structured nanomaterials for hunting and capture of molecules, ions and biomarkers for Proteomics Applications.
  • seminar
    Date:
    26 September
    2019
    Thursday
    Hours:
    11:00
    -
    12:00

    Solar Photovoltaics: Recent Progress & Future Potential

    Location: Perlman Chemical Sciences Building
    participants: Prof. Martin Green
    Australian Centre for Advanced Photovoltaics University of New South Wales, Sydney

    Abstract

    The last five years have seen major reductions in silicon solar module prices, with these dropping at a compounded rate approaching 20%/year over this period, with even more dramatic reductions in bids for bulk electricity supply through Power Purchase Agreements, to values as low as US$16.88/MWh. On the technology front, there have been substantial improvements in module energy conversion efficiency through displacement of established cell technology by the UNSW-invented and -developed PERC cell, complemented by the introduction of multi-busbar, half-cell and shingled modules. The introduction of PERC cells also allows low-cost fabrication of bifacially responsive modules, set to further boost effective efficiencies. These developments position photovoltaics to make a major impact on global CO2 omissions. A recent international study describes a technological path to a zero-carbon future by 2050 by transformation across all major energy sectors including not only electricity, but also heat, transport and industrial processes. This transformation is driven primarily by solar, with 63TW capacity calculated as required globally by this date, complemented by 8TW of wind, in the process creating 35 million direct energy jobs.
  • seminar
    Date:
    24 September
    2019
    Tuesday
    Hours:
    11:00

    Chemical and Biological Physics Guest Seminar

    Location: Perlman Chemical Sciences Building
    participants: Dr. Robert Weatherup
    University of Manchester, UK

    Abstract

    Probing the chemical reactions occurring at electrochemical and catalytic interfaces under realistic conditions is critical to selecting and designing improved materials for energy storage, corrosion prevention, and chemical production. Soft X-ray spectroscopies offer powerful element- and chemical-state-specific information with the required nm-scale interface sensitivity, but have traditionally required high vacuum conditions, impeding studies of interfaces under realistic liquid- and gas-phase environments.1 Here we introduce several membrane-based approaches developed in recent years in order to bridge this pressure gap, enabling operando x-ray photoelectron and absorption spectroscopy (XPS/XAS) of solid-liquid and solid-gas interfaces at atmospheric pressures.2–5 These rely on reaction cells sealed with X-ray/electron-transparent membranes, that can sustain large pressure drops to the high-vacuum measurement chamber.2,3 Thin (<100 nm) silicon nitride membranes are commercially available and transparent to even soft X-rays, whilst graphene membranes have thicknesses below the inelastic mean free path of photoelectrons (typically < 2 nm) and yet remain highly impermeable to gases and liquids.4 We show how these membrane-based approaches can be applied to study the chemical evolution of solid-liquid interfaces under electrochemical control, including the oxidation/reduction of Ni electrodes,5 and the solid-electrolyte interphase formation on Li-ion battery anodes. The extension of soft x-ray spectroscopies to liquid and atmospheric pressure gas environments is expected to be valuable for the study of a wide range of interfacial reactions across the electrochemical and catalytic sciences.
  • seminar
    Date:
    22 September
    2019
    Sunday
    Hours:
    19:30
    -
    21:00

    When people disappear - Stories and fairytales

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Professor Daniel H. Wagner
    Prof. Daniel Wagner has been researching his Polish roots since 1995. He is the author of 35 genealogical papers and the editor of a book about scientific tools in genealogy. He is a member of IGRA, and a member of the Management Committee of the International Institute for Jewish Genealogy and the Paul Jacobi Center.

    Abstract

    In the history of many families, all that remains about the fate of an ancestor for whom all traces were lost are rumors, often in conflicting versions. One of the most gratifying pleasures of a genealogical quest is to unveil the true story. Two examples taken from the lecturer’s personal history will demonstrate this.
  • seminar
    Date:
    22 September
    2019
    Sunday
    Hours:
    14:00
    -
    15:00

    The Long and Winding Road: From HIV Reverse Transcriptase Structure to Five Therapeutic Drugs, and New Insights into Viral Assembly and Maturation

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Eddy Arnold
    Board of Governors Professor and Distinguished Professor of Chemistry and Chemical Biology, Rutgers University
  • seminar
    Date:
    22 September
    2019
    Sunday
    Hours:
    11:00

    Ben May Center for Chemical Theory and Computation, Inaugural lecture

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof Daan Frenkel
    University of Cambridge

    Abstract

    A holy grail of nano-technology is to create truly complex, multi-component structures by self-assembly. Most self-assembly has focused on the creation of "structural complexity". In my talk, I will discuss "Addressable Complexity": the creation of structures that contain hundreds or thousands of distinct building blocks that all have to find their place in a 3D structure. Experiments on “DNA bricks” have demonstrated the feasibility of making such structures. Simulation and theory yield surprising insights that suggest design principles for brick structures. Interestingly, the design principles are different for DNA origami.
  • seminar
    Date:
    18 September
    2019
    Wednesday
    Hours:
    11:00

    Forecast Skill and the Impact of Equatorial Waves in Two Operational Weather Prediction Systems

    Location: Sussman Family Building for Environmental Sciences
    participants: George N. Kiladis
    Physical Sciences Division, Earth System Research Laboratory National Oceanic and Atmospheric Administration Boulder, Colorado

    Abstract

    Equatorially trapped waves account for a large portion of the perturbations within the tropical atmosphere and ocean. In the atmosphere, these disturbances are coupled to convection and determine a significant amount of rainfall variability on synoptic to intraseasonal time scales. Numerical models used for both weather and climate forecasting universally still have great difficulty simulating these convectively coupled disturbances. We assess the quantitative precipitation forecasts (QPF) skill of NOAA's Global Forecast System (GFS) and the European Centre for Medium Range Weather Forecasting Integrated Forecast System (IFS) operational models used for short term forecasts out to 10 days. Forecast skill was assessed by comparison with virtually independent GPM and CMORPH satellite precipitation estimates. Skill was quantified using a variety of metrics including pattern correlations for various latitude bands, temporal correlation at individual grid points, and space-time spectra of forecast precipitation over the global tropics and extratropics. Results reveal that, in general, initial conditions are reasonably well estimated in both forecast systems, as indicated by relatively good scores for the 6-12 hour forecasts. Since precipitation estimates are not directly assimilated into these systems, this indicates that the initialization of dynamical and thermodynamical fields is able to produce a reasonable QPF field, at least for the larger scales. We present evidence that the specification of the mass circulation rather than the moisture field is the primary source of this initial skill. Model skill is substantially better overall in the extratropics, however, tropical QPF in both systems is not considered useful by typical metrics much beyond a few days. A portion of this lack of tropical skill in can be traced back to inadequate treatment of equatorial wave activity coupled to convection. It is also demonstrated that extratropical forecast skill is positively correlated to preceding tropical skill, strongly suggesting that improvements in the treatment of tropics will lead to improved extratropical forecasts on the weekly and longer timescale.
  • seminar
    Date:
    15 September
    2019
    Sunday
    Hours:
    11:00

    Chemical and Biological Physics Dept Special Seminar

    Location: Perlman Chemical Sciences Building
    participants: Prof. Randall Goldsmith
    University of Wisconsin
  • seminar
    Date:
    9 September
    2019
    Monday
    Hours:
    11:00
    -
    12:00

    Applications of Hadamard Transform in NMR Spectroscopy

    Location: Perlman Chemical Sciences Building
    participants: Dr. Eriks Kupce
    Bruker Biospin
  • seminar
    Date:
    5 September
    2019
    Thursday
    Hours:
    10:30

    Imaging and Spectroscopy at 10nm Spatial Resolution using s-SNOM

    Location: Perlman Chemical Sciences Building
    participants: Imaging and Spectroscopy at 10nm Spatial Resolution using s-SNOM
  • seminar
    Date:
    3 September
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    Dissecting the Axoneme Structure: New Insights into an Old Organelle

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Ron Orbach
    Dept. of Molecular Biophysics & Biochemistry Yale University
  • seminar
    Date:
    3 September
    2019
    Tuesday
    Hours:
    11:00
    -
    12:00

    Learning to Love CO2: Carboxylation, Catalysis, and Desalination

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Ji-Woong Lee
    Department of Chemistry, University of Copenhagen

    Abstract

    Currently, more than 40 gigatonnes of CO2 are released annually into the atmosphere as a result of fossil fuel combustion, causing ocean acidification and climate unpredictability. Anthropogenic CO2 emission is seemingly hard to diminish in the near future and, therefore, CO2 -capture and sequestration or CO2 -functionalization can be viable solutions to address this issue. To use CO2 as a chemical feedstock, namely as a C1 building block, it is essential to equip the process with a nucleophilic catalyst or a highly active reagent, as exemplified by Grignard carboxylation reactions and some recent progress in metal-catalyzed reactions. In this seminar, I will display how we can utilize CO2 not only as a chemical feedstock and a catalyst but also as a stimulus for a desalination process. The obtained knowledge in CO2 activation and desalination will be beneficial in supramolecular chemistry, biology, CO2functionalization catalysis and CO2 sequestration processes.
  • seminar
    Date:
    6 August
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    Why are there knots in proteins?

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Sophie Jackson
    Department of Chemistry University of Cambridge United Kingdom
  • seminar
    Date:
    21 July
    2019
    Sunday
    Hours:
    11:00
    -
    12:00

    An update on anti-TB drug discovery program against multi-drug resistant Tuberculosis

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. V. Samuel Raj
    SRM University, Delhi-NCR, Sonepat, India
  • seminar
    Date:
    17 July
    2019
    Wednesday
    Hours:
    11:00
    -
    12:00

    More surprises in f-electron magnetism

    Location: Perlman Chemical Sciences Building
    participants: Prof. Alexander B. Shick
    Institute of Physics CAS, Prague

    Abstract

    Surface supported single magnetic atoms, the so-called "single-atom magnets", open new opportunities in a quest for t he ultimate size limit of magnetic information storage. Initially, the research mainly focused on 3d-atoms on surfaces. Recently, the attention was turned to the 4f-atoms, culminating in the experimental discovery of magnetically stable Ho atom on MgO(001) substrate, and Dy atom on graphene/Ir(111). I address the electronic and magnetic character of 4f-atoms on metal and Graphene substrate making use of a combination of the DFT+U with the exact diagonalization of Anderson impurity model (DFT+U+ED). The spin and orbital magnetic moments of Dy@Ir(111) and Dy/Graphene/Ir(111) are evaluated and compared with experimental XMCD data. The magnetic anisotropy energy is estimated, and the magnetic stability is discussed. The role of 5d-4f interorbital exchange polarization in modification of the 4f-shell energy spectrum is emphasized.
  • seminar
    Date:
    14 July
    2019
    Sunday
    Hours:
    11:00
    -
    12:00

    Trio correlation between cell mechanics, phagocytic capacity, and cancer aggressiveness

    Location: Perlman Chemical Sciences Building
    participants: Prof. Ofra Benny
    Faculty of Medicine, HUJI

    Abstract

    A comprehensive study showing a trio correlation between cell mechanics, phagocytic capacity, and cancer aggressiveness is presented. Mechanical properties of particles are shown to have a critical effect on the interactions with malignant cancer cells. Our findings offers new directions for mechanical based specificity in cancer treatment, and could lead to uptake measurement as a diagnostic tools for precision medicine.
  • seminar
    Date:
    11 July
    2019
    Thursday
    Hours:
    11:00

    Quantitative measurements of modulus and viscoelastic properties on the nanoscale: Challenges and new techniques

    Location: Perlman Chemical Sciences Building
    participants: Dr. Dalia Yablon
  • seminar
    Date:
    9 July
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    Enhanced single-molecule imaging through mechanistic analysis of blinking and point-spread function engineering?

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Peter Dedecker
    KU LEUVEN, BELGIUM
  • seminar
    Date:
    9 July
    2019
    Tuesday
    Hours:
    11:00

    Atomically controlled growth of functional, technologically important semiconductor systems

    Location: Perlman Chemical Sciences Building
    participants: Prof. Ana G Silva
    Growth of GaN films with high quality interfaces to SiC wafers by atomically controlled co-deposition of Ga reacting with atomic N produced by microwave excitation of nitrogen gas is reported. All the steps and processes involved require very high temperatures (ca. 900 – 1000). To obtain atomic control and high-quality interfaces, depositions at very low deposition rates have been used. This talk is focused on surface and interface studies using high-resolution photoelectron spectroscopy with photon energies optimizing the surface sensitivity, and/or the photoelectric cross sections. Thus, maximum of information about as many aspects of the growth processes and structure of the systems, is provided at the new ASTRID II facility (high brilliance and stability). The growth processes are characterized in-situ by photoelectron core-level and valence band spectroscopy).
  • seminar
    Date:
    2 July
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    Balancing protein stability and strain for folding and function

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Elizabeth Meiering
    University of Waterloo Canada
  • seminar
    Date:
    30 June
    2019
    Sunday
    Hours:
    11:00

    Influence of terrestrial plants and phytoplankton on photochemical air-pollution

    Location: Sussman Family Building for Environmental Sciences
    participants: Eran Tas
    Hebrew University of Jerusalem
  • seminar
    Date:
    27 June
    2019
    Thursday
    Hours:
    10:00
    -
    11:00

    Measuring nanometre distances in biomolecules using EPR Spectroscopy

    Location: Perlman Chemical Sciences Building
    participants: Dr. Janet Lovett
    School of Physics & Astronomy, University of St. Andrews

    Abstract

    EPR spectroscopy can be used to measure nanometre-scale distances within biomolecules and other soft matter, through determining the dipolar coupling between paramagnetic centres. These can be placed site-specifically within the molecules-of-interest as spin labels. Some experiments that measure the dipolar coupling will be introduced, and results including new spin labels and applications of the methodology will be discussed.
  • seminar
    Date:
    26 June
    2019
    Wednesday
    Hours:
    13:00

    Chemical and Biological Physics Dept Seminar

    Location: Perlman Chemical Sciences Building
    participants: Prof. Per Hedegaard
    Niels Bohr Institute, Copenhagen
  • seminar
    Date:
    25 June
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    Development of small-molecule inhibitors targeting bacterial replication and translations

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Barak Akabayov
    Ben Gurion University
  • seminar
    Date:
    25 June
    2019
    Tuesday
    Hours:
    11:00
    -
    12:00

    Geochemical Dynamics of Atmospheric Oxygen

    Location: Sussman Family Building for Environmental Sciences
    participants: Dan Schrag
    Harvard University
  • seminar
    Date:
    24 June
    2019
    Monday
    Hours:
    11:00
    -
    12:30

    Virus Structure: How Structural Biology Can Inform Function and Therapy

    Location: Arthur and Rochelle Belfer Building for Biomedical Research
    participants: Prof. David Stuart
    MRC Professor of Structural Biology, Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford,
  • seminar
    Date:
    24 June
    2019
    Monday
    Hours:
    11:00
    -
    12:00

    Chemical and Biological Physics Dept Seminar

    Location: Perlman Chemical Sciences Building
    participants: Corrado Rainone
    Institute of Physics, University of Amsterdam
  • seminar
    Date:
    23 June
    2019
    Sunday
    Hours:
    14:00
    -
    15:00

    Strongly interacting phonons at finite temperature

    Location: Perlman Chemical Sciences Building
    participants: Dr. Olle Hellman
    Fritz Haber Institute

    Abstract

    Thermal motions of atoms is an ever-present phenomenon in all of solid state physics. Phonons, quanta of heat, is the quasiparticule used to describe thermal motion in solids. Under normal conditions phonons are the dominant mechanism that govern transport and the largest contribution to entropy. I want to understand how phonons evolve in time, temperature, and how they behave when they interact strongly with each other or other quasiparticles. The inherent disorder in thermal motions makes theoretical predictions challenging. I will present methodological developments in finite temperature first principles simulations, specifically targeting strongly anharmonic systems. The method employs model Hamiltonians that explicitly depend on temperature. I will present applications pertaining to thermal conductivity, inelastic neutron spectra and phase stabilities, reproducing non-trivial temperature dependencies.
  • seminar
    Date:
    23 June
    2019
    Sunday
    Hours:
    11:00

    A Forward Model for the Architecture of Inner Planetary Systems

    Location: Sussman Family Building for Environmental Sciences
    participants: Eric Ford
    Department of Astronomy and Astrophysics Penn State
  • seminar
    Date:
    23 June
    2019
    Sunday
    Hours:
    11:00
    -
    12:00

    Cell Penetration and Membrane Fusion: Two Sides of the Same Coin

    Location: Perlman Chemical Sciences Building
    participants: Prof. Pavel Jungwirth
    Institute of Chemistry, Academy of Sciences, Prague

    Abstract

    Cell penetrating peptides have a unique potential for targeted drug delivery. While ATP-driven endocytosis is known to play a major role in their internalization, there has been also ample evidence for the importance of passive translocation for which the direct mechanism, where the peptide is thought to directly pass through the membrane via a temporary pore, has been widely advocated. In this talk, I will question this view and demonstrate that arginine-rich cell penetrating peptides can instead enter vesicles and cells by inducing multilamellarity and fusion, analogously to the action of calcium ions. Allolio C., Magarkar A., Jurkiewiczf P., Baxová K., Javanainen M., Mason P.E., Sachl R., Cebecauer M., Hof M., Horinek D., Heinz V., Rachel R., Zieglerg C.M., Schrofel A., Jungwirth P.: Arginine-rich cell-penetrating peptides induce membrane multilamellarity and subsequently enter via formation of a fusion pore. Proceedings of the National Academy of Sciences USA 115 (2018) 11923.
  • seminar
    Date:
    20 June
    2019
    Thursday
    Hours:
    15:00
    -
    16:00

    Charge scaling as a "free lunch" approach to electronic polarization in modelling aqueous electrolytes

    Location: Perlman Chemical Sciences Building
    participants: Prof. Pavel Jungwirth
    Institute of Chemistry, Academy of Sciences, Prague

    Abstract

    In order to make modelling of aqueous electrolytes more accurate, we explore the recently suggested approach for effectively accounting for electronic polarization effects using ionic charge rescaling. Based on this approach we develop a new and accurate parametrization of ions. Comparison to neutron scattering and ab initio molecular dynamics simulations demonstrates that the charge scaling approach allows for an accurate description of concentrated aqueous salt solutions including divalent ions. The present approach should thus find broad use in efficient and accurate modelling of polyvalent ions in aqueous environments, such as those encountered in biological and technological applications.
  • seminar
    Date:
    20 June
    2019
    Thursday
    Hours:
    11:00
    -
    12:00

    Optoelectronic properties of surface-guided nanowires with controlled crystal structures and orientations

    Location: Helen and Milton A. Kimmelman Building
    participants: Regev Ben Zvi
    PHd Student, Dept. Materials and Interfaces
  • seminar
    Date:
    20 June
    2019
    Thursday
    Hours:
    10:00
    -
    11:00

    Single and multi-frequency saturation methods for molecular and microstructural contrast in human MRI”

    Location: Perlman Chemical Sciences Building
    participants: Prof. Elena Vinogradov
    UT Southwestern Medical Center

    Abstract

    Magnetic Resonance Imaging (MRI) provides excellent quality images of soft tissues and is an established modality for diagnosis, prognosis and monitoring of various diseases. Majority of MRI scans in clinical practice today report on anatomy, morphology and sometimes physiology. The new area of active studies is aimed at developing MRI contrast methods for the detection of the events at the microstructural and molecular level employing endogenous properties. Here, we will discuss methods that employ single- and multi-frequency saturation to detect events on microstructural and molecular level. First, we will describe principles and translational aspects of Chemical Exchange Saturation Transfer1(CEST). CEST employs selective saturation of the exchanging protons and subsequent detection of the water signal decrease to create images that are weighted by the presence of a metabolite or pH2. We will describe aspects of translating CEST to reliable clinical applications and discuss its potential uses in human oncology, specifically breast cancer. Second, we will describe a method called inhomogeneous Magnetization Transfer3 (ihMT), which employs dual-frequency saturation to create contrast originating from the residual dipolar couplings and thus specific to microstructure. We will focus on the application of ihMT to the detection of myelin in brain and spinal cord. Finally, we will discuss a novel exchange-sensitive method based on the balanced steady-state free precession (bSSFP) sequence as an alternative way for chemical exchange detection (bSSFPX4). Using an effective field description, similarities between bSSFP and CW application can be explored and utilized for in-vivo MRI contrast. [1] K. Ward, et.al., JMR,143,79-87 (2000). [2] J. Zhou, et.al., Nature Medicine, 9,1085-1090 (2003). [3] G. Varma, et.al., MRM, 73, 614-622 (2015). [4] S. Zhang, et.al., JMR, 275, 55-67 (2017).
  • seminar
    Date:
    16 June
    2019
    Sunday
    Hours:
    11:00

    Geoethics: what is geoethics and what it has to do with us?

    Location: Sussman Family Building for Environmental Sciences
    participants: Nir Orion
    Department of Science Teaching Weizmann Institute of Science
  • seminar
    Date:
    13 June
    2019
    Thursday
    Hours:
    14:00

    Chemical and Biological Physics Dept Seminar

    Location: Perlman Chemical Sciences Building
    participants: Prof. Phil Pincus
    University of California, Santa Barbara
  • seminar
    Date:
    12 June
    2019
    Wednesday
    Hours:
    15:00
    -
    16:00

    Design and validation of a head coil for MRI at 7T

    Location: Perlman Chemical Sciences Building
    participants: Dr. Shajan Gunamony
    Senior Research Fellow, University of Glasgow

    Abstract

    Radio frequency (RF) coil design for ultra-high field MRI scanners is an active field of research. We have recently developed an 8-channel transmit, 32-channel receive 7T head coil at the University of Glasgow. We focused on an open-faced design to make the setup less claustrophobic and more acceptable in a clinical environment. Furthermore, the coil can be used in both the scanner modes. I will also present our internal validation process which allows home-built RF coils to be used in vivo.
  • seminar
    Date:
    12 June
    2019
    Wednesday
    Hours:
    11:00
    -
    12:00

    Halide Perovskites as a polymorphous network with a distribution of local motifs

    Location: Perlman Chemical Sciences Building
    participants: Prof. Alex Zunger
    Dept. Materials Science and Engineering, University of Colorado

    Abstract

    While octahedral tilting or B atom displacements as a single repeated structural motif are well known in perovskites, we find that removing the standard restriction to such a minimal unit cell size leads in some perovskites to the formation of a ‘polymorphous network’, manifesting a distribution of different tilt angles and different B-atom displacement in different octahedra. The distribution of local motifs emerges already from the (density functional) minimization of the static, T=0 internal energy of a large supercell, constrained to have the global cubic lattice vectors. This a-thermal distribution represents a correlated set of displacements and is very different from the time-dependent uncorrelated entropic thermal disorder calculated by Molecular Dynamics, or from the single sharp monomorphous values of these deformation parameters . This suggests that the widely discussed single formula unit cubic Pm-3m structure of halide perovskites does not really exist, except as a macroscopically averaged fictitious structural model. Because X-ray diffraction has a rather long coherence length, such polymorphous systems were often fit in structure refinement models by a macroscopically averaged (“fictitious monomorphous”) cubic Pm-3m unit cells. Significantly, compared to the monomorphous assumption, the cubic polymorphous network affects Pair Distribution Function (PDF), total energies, up to 300% larger band gaps, leads to the reversal of the predicted sign of the mixing enthalpies of the solid solutions from negative (ordering-like; not seen experimentally) to positive (experimentally observed phase-separating).Also, the polymorphous networks have a much larger (by ~50%) calculated dielectric constant, yet a relatively narrow energy range of vacancy transition levels and sharp absorption onset.defect physics. The polymorphous approximant could thus serve as a useful practical structure to use with standard band structure approaches to predict properties, replacing the fictitious monomorphous structures .
  • seminar
    Date:
    11 June
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    The Ventilated Thermocline in the Tropical Pacific and Its Relationship to Decadal Variability in Global Warming

    Location: Sussman Family Building for Environmental Sciences
    participants: Dan Schrag
    Harvard University
  • seminar
    Date:
    10 June
    2019
    Monday
    Hours:
    11:00
    -
    12:00

    Van der Waals Dispersion Forces in Nanostructures

    Location: Perlman Chemical Sciences Building
    participants: Dr. Tim Gould
    University of Griffith, Brisbane

    Abstract

    Low-dimensional nanostructures, which have at least one nano-scale length scale and at least one long length scale and include technologically promising cases like layered materials and nanowires, can exhibit unusual van der Waals dispersion forces. These manifest via "non-additive" contributions to the dispersion energy, which are excluded from models, such as D3, which sum over contributions across different constituent atoms. This talk will discuss the origin, role, and general weirdness of such effects. We will discuss the Dobson scheme for describing such effects and show some systems where conventional approaches to dispersion miss important qualitative and quantitative physics. New methods which capture some or all of these effects will be described. The importance of dispersion forces will be contextualised. Finally, we will digress into a new frontier of method development – easy modelling of low-lying excited states.
  • seminar
    Date:
    5 June
    2019
    Wednesday
    Hours:
    11:00
    -
    12:00

    Non-Hydrolytic Sol-Gel Synthesis of Micro/Mesoporous Silicate and Phosphate Materials

    Location: Perlman Chemical Sciences Building
    participants: Prof. Jiri Pinkas
    Masaryk University, Department of Chemistry, Brno

    Abstract

    Synthetic methods based on sol-gel chemistry are attractive solution-based routes to many simple and complex materials. The non-hydrolytic procedures are viable alternatives to classical aqueous techniques and these condensation reactions are inherently suitable for fabrication of mixed-metal and multimetallic oxidic and hybrid inorganic-organic systems. We developed novel non-hydrolytic sol-gel routes to several classes of porous xerogels, such as silicophosphates and -phosphonates, aluminophosphates, Al, Ti, Zr, and Sn silicates, hybrid aromatic organosilicates, and organosilicophosphates. The polycondensation reactions are based on elimination of small molecules, such as trimethylsilyl ester of acetic acid, dialkylacetamides, silylamines, ethers or alcohols. These elimination reactions provide microporous xerogels with high surface areas. Control of porosity and pore size is achieved by several methods, such as choice of suitable precursors, application of bridging groups, or addition of Pluronic templates. Residual organic groups on the surface allow for chemical modification and anchoring of various groups. Calcination in air provides xerogels that are stable at temperatures up to 500 C and show superior catalytic activity and selectivity in various catalytic reactions. The prepared xerogels were characterized by solid-state 13C, 27Al, 29Si, 31P NMR, IR, surface area analysis, DRUV-vis, TGA and XRD
  • seminar
    Date:
    4 June
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    From Membrane to Nucleus: the Molecular Logic of Notch Signal Transduction

    Location: Wolfson Building for Biological Research
    participants: Prof. Stephen Blacklow
    Harvard Medical School
  • seminar
    Date:
    4 June
    2019
    Tuesday
    Hours:
    11:00
    -
    12:00

    Phosphorus-Element Bond-Forming Reactions

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Christopher C. Cummins
    Department of Chemistry, MIT

    Abstract

    Reactive Intermediates & Group Transfer Reactions. We design and synthesize molecular precursors that can be activated by a stimulus to release a small molecule of interest. The molecular precursors themselves are isolated as crystalline solids; they are typically soluble in common organic solvents and can be weighed out and used as needed. For example, the molecule P2A2 (A = anthracene or C14H10) is a molecular precursor to the diatomic molecule P2. Compounds having the formula RPA serve to transfer the phosphinidene (PR) group either as a freely diffusing species (R = NR’2, singlet phosphinidene) or else by inner sphere mechanisms (R = alkyl, triplet phosphinidene). Using the RPA reagents we are developing reactions analogous to cyclopropanation and aziridination for delivery of the PR group to olefins with the formation of three-membered P-containing rings, phosphiranes. Metaphosphates and Phosphorylating Methodology. Crystalline metaphosphate salts with lipophilic counter cations are useful starting materials applicable in polar organic media. “Metaphosphate” refers to the inorganic ion PO3(-) which, unlike its chemical cousin, nitrate, exists not as a monomeric species but rather as oligomeric rings: [(PO3)n]n-. These cyclic phosphates can be converted into electrophilic phosphorylating agents (a) by treatment with peptide coupling reagents, or (b) by conversion into their crystalline acid forms and subsequent dehydration. Such activated cyclic phosphates can be used directly for oligophosphorylation of C, N, and O nucleophiles. Phosphorylation of the Wittig reagent leads to a new phosphorus ylide with a cyclic phosphate as the C-substituent and a non-hydrolyzable P-C bond, allowing for conjugation of oligophosphate groups to a biomolecule of interest by aldehyde olefination. Sustainable Phosphorus Chemistry. The industrial “thermal process” by which the raw material phosphate rock is upgraded to white phosphorus is energy intensive and generates CO2. We seek alternative chemical routes to value-added P-chemicals from phosphate starting materials obtained either by the agricultural “wet process” or by phosphorus recovery and recycling from waste streams. Trichlorosilane is a high production volume chemical for its use in the manufacture of silicon for solar panels. We show that trichlorosilane is a reductant for phosphate raw materials leading to the bis(trichlorosilyl) phosphide anion [P(SiCl3)2]- as a versatile intermediate en route to compounds containing P-C bonds.
  • seminar
    Date:
    3 June
    2019
    Monday
    Hours:
    11:00
    -
    12:00

    Prof. Jenny Nelson, Imperial College London

    Location: Perlman Chemical Sciences Building
    participants: Prof. Jenny Nelson
    Dept. Physics, Imperial College London
  • seminar
    Date:
    2 June
    2019
    Sunday
    Hours:
    11:00

    The role of clouds in extratropical climate change and variability

    Location: Sussman Family Building for Environmental Sciences
    participants: David Thompson
  • seminar
    Date:
    30 May
    2019
    Thursday
    Hours:
    10:00
    -
    11:00

    Chemical and Biological Physics Guest Seminar

    Location: Perlman Chemical Sciences Building
    participants: Dr. Alexandre Kabla
    University of Cambridge. UK

    Abstract

    Cell migration and cell mechanics play a crucial role in a number of key biological processes, such as embryo development or cancer metastasis. Understanding the way cells control their own material properties and mechanically interact with their environment is key. At a more fundamental level, there is need better measure, describe and monitor cell and tissue mechanics before we can formulate testable hypotheses. In this talk, I will report experimental studies on the mechanical response of two different multicellular structures: epithelial monolayers and early embryonic tissues. In both cases, the material exhibits a strong time-dependent response over a broad distribution of time-scales. The combination of mechanical characterisation with biological perturbations offers new insight into the mechanisms exploited by cells and tissue to control their mechanical properties. This insight is however limited by the lack of consistency in experimental protocols and modelling strategies used in the field. We recently developed a systematic approach to capture material properties from mechanical behaviours and made progress assessing the model’s generality over a broad range of biological systems
  • seminar
    Date:
    28 May
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    Structural biology studies of a large DNA repair complex

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Michael Latham
    Texas Tech University
  • seminar
    Date:
    28 May
    2019
    Tuesday
    Hours:
    11:00
    -
    12:00

    Systems-Level Control of Structural Hierarchy

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Robert Macfarlane
    Department of Materials Science and Engineering, MIT

    Abstract

    Structural hierarchy is a powerful design concept where specific geometric motifs are used to influence material structure across multiple size regimes. These complex levels of organization are typically achieved in the laboratory by conceptually breaking a material down into the smallest components that can be manipulated (e.g. individual molecules, macromolecules, or nanoparticles), and manipulating the thermodynamics of chemical bonding between those components to control how they build up into larger length scale patterns. Conversely, complex assemblies in natural systems are commonly achieved through a more holistic approach where assembly behaviors at the molecular, nano, and macroscopic scales are interlinked. This means that not only does structural information contained in molecular building blocks filter upwards to dictate material form at the nano to macroscopic levels, but also that the environment created by the larger length scale features can affect the behavior of individual components. Here, we will discuss two different methods to synthesize materials in a systems-focused approach that mimics nature's ability to general complex structural motifs across a wide range of size regimes. The first uses nanoscale design handles to deliberately control the multivalent assembly of particle-grafted supramolecular binding moieties, where control over both molecular and nanostructure of material building blocks is then used to manipulate the mesoscale structure of the resulting materials. The second uses macroscopic interfaces to dictate the assembly behavior of DNA-grafted nanoparticles, generating superlattice architectures with controlled sizes, shapes, and orientations. Together, these techniques allow for systems-level approaches to materials design, expanding our ability to program hierarchical ordering at the molecular, nano, and macroscale simultaneously.
  • seminar
    Date:
    26 May
    2019
    Sunday
    Hours:
    11:00
    -
    12:00

    Fluid Flow Far From Equilibrium: From Shear Thinning to the Glass Transition

    Location: Perlman Chemical Sciences Building
    participants: Prof. Mark Robbins
    Dept. Physics, Johns Hopkins University

    Abstract

    The talk will describe nonlinear rheology in extreme conditions that change fluid structure and flow mechanisms. Elongational flow of entangled polymers produces near complete molecular alignment but only changes the viscosity by an order of magnitude and does not destroy the confining tube. A transition in the mechanism of shear thinning in lubricants from alignment to thermal activation is shown to be generic and allows simulations to examine whether the viscosity diverges at a finite glass transition temperature.
  • seminar
    Date:
    26 May
    2019
    Sunday
    Hours:
    11:00
    -
    12:00

    Mixing and Unmixing in Planets

    Location: Sussman Family Building for Environmental Sciences
    participants: David Stevenson
  • seminar
    Date:
    21 May
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    Structural and Biophysical Characterization of Chloride Intracellular Channels Inherent Flexibility

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Yoni Haitin
    Tel-Aviv University
  • seminar
    Date:
    21 May
    2019
    Tuesday
    Hours:
    11:00
    -
    12:00

    Controlling peptide and protein conformation with synthetic scaffolds

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Dr. Tom N. Grossmann
    Department of Chemistry and Pharmaceutical Sciences, VU University Amsterdam, The Netherlands

    Abstract

    The synthesis and the design of complex molecular scaffolds with defined properties present central challenges in current chemical research. Such molecules can provide access to novel therapeutics, catalysts and materials. Often, it is essential for these scaffolds to adopt defined three-dimensional structures. Preferably, the degree of flexibility in these systems can be fine-tuned in a defined and controllable manner. The folding properties of peptides and proteins provide an excellent basis for the design of molecules with defined structural properties, in particular when combined with non-natural small molecular scaffolds. The research of the Grossmann lab centers around the synthesis of peptide-derived molecules and the engineering of proteins using organic chemistry approaches. The lecture will highlight design principles and synthetic strategies that enable the conformational control of relatively small and flexible peptidomimetics[1,2] as well as large and globular enzymes.[3] In addition, reversible constraints that allow the design of peptide-based molecular switches[4] will be presented. References: [1] A Glas et al. Angew. Chem. Int. Ed. 2014, 53, 2489–2493 [2] P Cromm et al. Nature Commun. 2016, 7, 11300. [3] M Pelay-Gimeno et al. Angew. Chem. Int. Ed. 2018, 57, 11164-11170. [4] C Mueller et al. Angew. Chem. Int. Ed. 2018, 57, 17079-17083
  • seminar
    Date:
    19 May
    2019
    Sunday
    Hours:
    11:00

    Fluvial response to base-level fall: insights from the main perennial tributaries of the Dead Sea

    Location: Sussman Family Building for Environmental Sciences
    participants: Elad Dente
    Hebrew University of Jerusalem
  • seminar
    Date:
    19 May
    2019
    Sunday
    Hours:
    11:00
    -
    12:00

    From Simplicity to Complexity: Strategic Design & Applications

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Zackaria Nairoukh
    WWU Münster, Germany
  • seminar
    Date:
    19 May
    2019
    Sunday
    Hours:
    11:00
    -
    12:00

    Polymer-mediated nanoparticle assembly: Controlling ordering from the molecular level to the micron scale

    Location: Perlman Chemical Sciences Building
    participants: Prof. Roy Shenhar
    Institute of Chemistry and the Center for Nanoscience and Nanotechnology

    Abstract

    Block copolymer-guided assembly of nanoparticles leads to the formation of nanocomposites with periodic arrangement of nanoparticles, which are important for applications such as photonic devices and sensors. However, linear block copolymers offer limited control over the internal arrangement of nanoparticles inside their hosting domains as well as the long-range ordering of the entire nanocomposite film. The first part of the talk will focus on the molecular level: how the chemical design of the polymeric system – both compositional and architectural – could be used to tailor chemical interactions and manipulate chain conformation, which, in turn, influence the local nanoparticle distribution inside the domains they segregate in. In the second part I will show how the utilization of topographically patterned substrates could be used not only to align block copolymer domains along a macroscopic coordinate but also to obtain isolated patterns on non-regular features.
  • seminar
    Date:
    15 May
    2019
    Wednesday
    Hours:
    11:00
    -
    12:00

    Grain Boundary Dynamics

    Location: Perlman Chemical Sciences Building
    participants: Prof. David Srolovitz
    Dept. Materials Science and Engineering, City University of Hong Kong

    Abstract

    Grain boundaries (GBs) are the 2D interfaces between crystals of the same material with different orientations. The dynamics of GBs is central to both microstructure evolution and the mechanics of polycrystals. GB dynamics are largely controlled by the motion of line defects that are constrained to lie in the GB. These line defects, known as disconnections, have both dislocation character (Burgers vector) and step character (step height). Possible Burgers vectors and step heights are completely determined by crystallography (i.e., crystal structure and the relative orientations of the two grains). In this talk, I will discuss disconnections, their crystallography, their nucleation and motion, and present a statistical mechanics-based description of a wide range of GB properties based on disconnection dynamics. In particular, I will discuss the thermal roughening of GBs, the migration of GBs, GB shear coupling, and how GBs interact with with applied stresses and compare these predictions with both molecular dynamics and experimental results. I will end by describing the remaining challenges in developing a quantitative approach to the microstructure evolution of polycrystalline materials.
  • seminar
    Date:
    14 May
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    Molecular basis for pH- and zinc-dependent protein quality control at the ER-Golgi interface

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Kenji Inaba
    Professor of Biochemistry & Structural Biology Institute of Multidisciplinary Research for Advanced Materials, Tohoku University Sendai, Japan
  • seminar
    Date:
    12 May
    2019
    Sunday
    Hours:
    11:00
    -
    12:00

    Spontaneous shape transitions of developing tissues

    Location: Perlman Chemical Sciences Building
    participants: Prof. Anne Bernheim
    Department of Chemical Engineering, Ben Gurion University

    Abstract

    Shape transitions in developing organisms can be driven by active stresses, notably, active contractility generated by myosin motors. We study the contraction and buckling of actomyosin networks isolated from bounding surfaces as a model system for studying shape transitions in developing tissues. This system offers a well-controlled way to study the role of physical constraints and boundary conditions mechanically induced spontaneous shape transition.
  • seminar
    Date:
    12 May
    2019
    Sunday
    Hours:
    11:00

    Improving the detection of biological aerosols in the atmosphere - pollen, spores, and nitrated proteins

    Location: Sussman Family Building for Environmental Sciences
    participants: Alex Huffman
    University of Denver
  • seminar
    Date:
    7 May
    2019
    Tuesday
    Hours:
    11:00
    -
    12:00

    Supramolecular Sensing Ensembles: More Information through Communication

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Frank Biedermann
    Institute for Nanotechnology (INT), Karlsruhe Institute for Technology, Karlsruhe, Germany

    Abstract

    The detection of spectroscopically silent analytes in water is often accomplished by utilization of reactive probes that form chromophoric analyte-dye conjugates. Unfortunately, similar but distinctly different analytes usually do not provide unique spectroscopic features, such that chromatographic separation steps have to be employed, causing significant additional costs and hinder applications. Supramolecular indicator-dye displacement assays can overcome certain limitations of reactive-probes, e.g., they allow for an in situ detection of even non-functionalizable analytes and are of great utility for reaction monitoring. However, their analyte differentiation capabilities are again restricted. Here, we present new strategies involving supramolecular sensing ensembles that allow for improved analyte differentiation through spectroscopic fingerprints. We show that this strategy is applicable to both non-covalent analyte-receptor binding schemes and to reactive-probe assays.
  • seminar
    Date:
    5 May
    2019
    Sunday
    Hours:
    11:00
    -
    12:00

    Structure-Activity Relationship by Kinetics for Drug Discovery in Protein Misfolding Diseases

    Location: Perlman Chemical Sciences Building
    participants: Prof. Michele Vendruscolo
    Dept. Chemistry, Cambridge University
  • seminar
    Date:
    5 May
    2019
    Sunday
    Hours:
    11:00

    The pathway of atmospheric water from ocean evaporation to rainout in extratropical weather systems

    Location: Sussman Family Building for Environmental Sciences
    participants: Heini Wernli
    ETH
  • seminar
    Date:
    1 May
    2019
    Wednesday
    Hours:
    11:00
    -
    12:00

    Excitons in Flatland: Exploring and Manipulating Many-body Effects on the Optical Excitations in Quasi-2D Materials

    Location: Perlman Chemical Sciences Building
    participants: Dr. Diana Qiu
    Dept. Physics, University of California at Berkeley

    Abstract

    Since the isolation of graphene in 2004, atomically-thin quasi-two-dimensional (quasi-2D) materials have proven to be an exciting platform for both applications in novel devices and exploring fundamental phenomena arising in low dimensions. This interesting low-dimensional behavior is a consequence of the combined effects of quantum confinement and stronger electron-electron correlations due to reduced screening. In this talk, I will discuss how the optical excitations (excitons) in quasi-2D materials, such as monolayer transition metal dichalcogenides and few-layer black phosphorus, differ from typical bulk materials. In particular, quasi-2D materials are host to a wide-variety of strongly-bound excitons with unusual excitation spectra and massless dispersion. The presence of these excitons can greatly enhance both linear and nonlinear response compared to bulk materials, making them ideal candidates for optoelectronics and energy applications. Moreover, due to enhanced correlations and environmental sensitivity, the electronic and optical properties of these materials can be easily tuned. I will discuss how substrate engineering, stacking of different layers, and the introduction or removal of defects can be used to tune the band gaps and optical selection rules in quasi-2D materials.
  • seminar
    Date:
    28 April
    2019
    Sunday
    Hours:
    11:00

    The stinging mechanism of jellyfish

    Location: Sussman Family Building for Environmental Sciences
    participants: Uri Shavit
    Technion
  • seminar
    Date:
    16 April
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    Exploring the evolutionary origin of histone-based chromatin organisation

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Tobias Warnecke
    Molecular Systems Group MRC London Institute of Medical Sciences (LMS) & Imperial College London
  • seminar
    Date:
    16 April
    2019
    Tuesday
    Hours:
    11:00
    -
    12:00

    Ultrafast Excited State Dynamics in Twisted Aromatics

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Mahesh Hariharan
    School of Chemistry, IISER Thiruvananthapuram, Kerala, India
  • seminar
    Date:
    15 April
    2019
    Monday
    Hours:
    11:00
    -
    12:15

    "Bulk Metallic Glasses: A High, but Narrow Path to Success"

    Location: Max and Lillian Candiotty Building
    participants: Prof. Jan Schroers
    Yale University

    Abstract

    Bulk metallic glasses combine plastic like processing with superb high-strength metal properties. Their processing opportunities originate from their high thermal stability, which has been explored for novel metal processing methods such as fused filament fabrication to 3D print, stretch blowmolding to fabricate previously unachievable shapes for metals, and micro- nanofabrication. As BMGs are metastable, processing has to avoid crystallization, structural relaxation, and reduction of fictive temperature. We show here that minute structural changes, realized through processing conditions, can cause drastic effects on mechanical properties. Specifically, we reveal a flaw tolerance behavior of metallic glasses, a critical volume fraction of crystallinity for embrittlement, and a mechanical glass transition behavior. We will offer a mechanistic understanding based on local atomistic events controlling brittleness and ductility in metallic glasses. Utilizing suggested metallic glass paradigm requires careful considerations of all these phenomena to form high-strength metals like plastics with consistently high fracture toughness.
  • seminar
    Date:
    14 April
    2019
    Sunday
    Hours:
    14:00
    -
    15:00

    M.Sc thesis: Electronic Structure of Halide Perovskites from a Screened Range-separated Hybrid Functional

    Location: Perlman Chemical Sciences Building
    participants: Galit Cohen
    Dept. Materials and Interfaces
  • seminar
    Date:
    14 April
    2019
    Sunday
    Hours:
    11:00

    From patterns to function in dryland ecosystems

    Location: Sussman Family Building for Environmental Sciences
    participants: Ehud Meron
    Ben Gurion University
  • seminar
    Date:
    10 April
    2019
    Wednesday
    Hours:
    11:00
    -
    12:00

    Cut along dotted line: kirigami materials and device applications

    Location: Perlman Chemical Sciences Building
    participants: Prof. Max Shtein
    Professor of Materials Science and Engineering, Chemical Engineering; University of Michigan

    Abstract

    Simple 2-dimensional cut and fold patterns can be transformed into 3-dimensional shapes upon stretch-ing. We use this simple approach to develop mechanical metamaterials with several interesting proper-ties and applications. I will describe ways of tuning properties via geometric structure, and discuss ex-amples of how this can be used to achieve superior performance in mechanics, photonics, electronics, sensors, and other areas. References: “Dynamic kirigami structures for integrated solar tracking.” Nature Comm. 6, 8092 (2015) “A kirigami approach to engineering elasticity in nanocomposites through patterned defects.” Na-ture Mater., 14 (2015) 785 “An Electric Eel-Inspired Artificial Soft Power Source from Stacked Hydrogels.” Nature, 552 (2017) 214
  • seminar
    Date:
    10 April
    2019
    Wednesday
    Hours:
    11:00
    -
    12:00

    Synthetic Reactions Assisted by Photons

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Masahiro Murakami
    Department of Synthetic Chemistry and Biological Chemistry, Kyoto University
  • seminar
    Date:
    8 April
    2019
    Monday
    Hours:
    11:00
    -
    12:00

    Growth mechanisms of quasi-1D semiconductors and oxides deduced from real-time electron microscopy

    Location: Perlman Chemical Sciences Building
    participants: Dr. Kolibal Miroslav
    CEITEC (the Central European Institute of Technology, Brno

    Abstract

    One-dimensional materials represent an attractive class of nanostructures, mainly because of their geometry which inherently implies applications such as electrodes for sensing purposes or conduction channels in nanoscale electronics. Different mechanisms may be utilized to prepare nanowires, e.g. stress-driven one-dimensional diffusion, metal-catalyzed growth (VLS) etc. The most important role in identifying and description of the growth mechanisms is played by real-time microscopies, mostly TEM. However, although very powerfull in terms of image resolution, TEM is also limited in use, especially because of very strict sample geometry requirements. In this seminar talk, I will present our real-time in-situ scanning electron microscopy experiments of nanowire growth. Two different material systems will be presented – germanium nanowires catalyzed by Au nanoparticles and WOx nanowires. As for the latter case, our experiments reveal a very unusual oxidation mechanism of tungsten disulfide nanotubes, resulting in tungsten oxide nanowire formation. The talk will summarize studies on quasi-1D systems conducted at IPE and CEITEC BUT.
  • seminar
    Date:
    8 April
    2019
    Monday
    Hours:
    10:00

    Digitally draining the oceans (so we can see what’s inside)

    Location: Sussman Family Building for Environmental Sciences
    participants: Derya Akkaynak
    Princeton University
  • seminar
    Date:
    7 April
    2019
    Sunday
    Hours:
    11:00
    -
    12:00

    Metal oxide growth within block copolymers – mechanism, challenges and opportunities

    Location: Perlman Chemical Sciences Building
    participants: Prof. Tamar Segal-Peretz
    Department of Chemical Engineering, Technion

    Abstract

    Self-assembly of block copolymers (BCP) is a well-known method for nanostructure fabrication at the 5-50 nm scale. Recently, sequential infiltration synthesis (SIS) was developed from atomic layer deposition (ALD) chemistry for selective growth of inorganic materials within polymers. In this talk, I will discuss SIS mechanism and growth process development as well as our work on combining BCP self-assembly with SIS for nanoparticle structuring, 3D imaging with TEM tomography, ultrafiltration membranes, and advanced 3D nanofabrication.
  • seminar
    Date:
    7 April
    2019
    Sunday
    Hours:
    11:00

    What planet formation tells us about planetary interior structure

    Location: Sussman Family Building for Environmental Sciences
    participants: Alona Vazan
    Hebrew University
  • seminar
    Date:
    4 April
    2019
    Thursday
    Hours:
    11:00

    Chemical and Biological Physics Guest Seminar

    Location: Perlman Chemical Sciences Building
    participants: Dr. Thorsten Auth
    Forschungszentrum Julich

    Abstract

    The cytoskeleton is a highly dynamic three-dimensional network of polar filamentous proteins and molecular motors. It provides structural stability for biological cells and it also generates and transmits mechanical forces. For example, in mesenchymal cell motility actin filaments polymerize at their plus ends, which exerts pushing forces on the cell membrane. Here, we present a generic two-dimensional model for an active vesicle, where self-propelled filaments attached to semiflexible polymer rings form mechanosensitive self-propelled agents. We find universal correlations between shape and motility. To probe the internal dynamics of flexocytes, we study the effect of substrate patterning on their mechanical response. The active vesicles reproduce experimentally observed shapes and motility patterns of biological cells. They assume circular, keratocyte-like, and neutrophil-like shapes and show both persistent random and circling motion. Interestingly, explicit pulling forces only are sufficient to reproduce this cell-like behavior. Also for the reflection of the vesicles at walls and the deflection of their trajectories at friction interfaces we find parallels to the behavior of biological cells. Our model may thus serve as a filament-based, minimal model for cell motility.
  • seminar
    Date:
    3 April
    2019
    Wednesday
    Hours:
    14:00

    Optics in the Air

    Location: Sussman Family Building for Environmental Sciences
    participants: Joseph Shaw
    Director, Optical Technology Center Montana State University

    Abstract

    This talk will use photographs and diagrams to illustrate and explain some of the beautiful optical phenomena observable in nature, such as ice‐crystal halos, rainbows, and sky colors, and will relate them to ongoing research into the spectral and spatial distribution of polarization in the atmosphere. Our group at Montana State University has pioneered all‐sky imaging methods to study skylight polarization and relate it to properties of airborne particles, clouds, and the underlying surface. Brief results from a deployment of all‐sky polarization imagers at the August 2017 solar eclipse will be shown and related to a more general discussion of atmospheric optical effects that can be seen by eye. The talk takes its title from my 2017 book, which describes optical phenomena in nature, especially as seen through airplane windows.
  • seminar
    Date:
    1 April
    2019
    Monday
    Hours:
    14:00
    -
    15:00

    Imaging phase transitions with scanning SQUID

    Location: Perlman Chemical Sciences Building
    participants: Prof. Beena Kalisky
    Dep. of Physics and Institute of Nanotechnology and Advanced Materials, Bar Ilan University

    Abstract

    We use a local magnetic imaging technique, scanning SQUID microscopy, to map the spatial distribution of electronic states near surfaces and interfaces. We track conductivity, superconductivity and magnetism in systems undergoing phase transitions, where the local picture is particularly meaningful. I will describe two measurements: At the superconductor-insulator transition in NbTiN we map superconducting fluctuations and detect a non-trivial behavior near the quantum critical point. Near the metal to insulator transition at the 2D LaAlO3/SrTiO3 interface, we find that the conduction landscape changes dramatically and identify the way different types of defects control the behavior.
  • seminar
    Date:
    31 March
    2019
    Sunday
    Hours:
    15:30
    -
    16:30

    Molecules in Large and Small Pores as Observed by NMR Spectroscopy. Pore Structure, Tortuosity and Molecular Interactions

    Location: Perlman Chemical Sciences Building
    participants: Prof. Istvan Furo
    Department of Chemistry, KTH Royal Institute of Technology, Stockholm

    Abstract

    The seminar summarizes three recent studies (1,2,3) since that share some common elements: they concern porous materials and the method used is NMR spectroscopy. Yet, the aims differ. In the first study (1), the unknown is the pore structure. In particular, pore structure in hydrogels is difficult to access as water cannot be removed without affecting the pores and in the presence of water the well-honed gas sorption and mercury porosimetries just do not work. The method we invented to remedy this situation is called size-exclusion quantification (SEQ) NMR and it can be seen as the multiplexed analogue of inverse size exclusion chromatography. In effect, we sample by diffusion NMR the size distribution in a polydisperse polymer solution before and after it had been equilibrated with a porous matrix. Size-dependent polymer ingress reveals the pore structure. The method has several advantages over possible alternatives, not least its speed. In the second study (2), we sample the self-diffusion of neat water and other molecules like dimethyl sulfoxide (DMSO) and their mixtures by NMR diffusion experiments for those fluids imbibed into controlled pore glasses (CPG, pore size range 7.5 to 73 nm). Their highly interconnected structure is scaled by pore size and exhibits pore topology independent of size. Relative to the respective diffusion coefficients obtained in bulk phases, we observe a reduction in the diffusion coefficient that is independent of pore size for the larger pores and becomes stronger toward the smaller pores. Geometric tortuosity governs the behavior at larger pore sizes, while the interaction with pore walls becomes the dominant factor toward smaller pore diameters. Deviation from the trends predicted by the popular Renkin equation and variants (4) indicates that the interaction with the pore wall is not just a simple steric one. In the third study (3), the porous material is hydrated cellulose. In that matrix, we identify by using 2H MAS NMR two different groups of water molecules being in slow exchange with each other. Water molecules in one of the groups exhibit anisotropic molecular motions with a high order parameter. Based on, among other things, the observed behavior with increasing vapor pressure, we argue that this water is an integral structural element of the cellulose fibril, that itself is an aggregate of the basic units, the cellulose nanofibrils.
  • seminar
    Date:
    31 March
    2019
    Sunday
    Hours:
    14:00
    -
    15:00

    What makes a good solar cell?

    Location: Perlman Chemical Sciences Building
    participants: Prof. Thomas Kirchartz
    Forschungszentrum Jülich

    Abstract

    For the purpose of identifying novel absorber materials based on experimental or computational material screening, it is useful to identify the basic ingredients required to make a good solar cell out of the combination of different absorber and contact materials. Figures of merit are needed that quantify whether a certain material is likely to perform well as a solar cell. To answer the question, which parameters are most important, we look into the key properties of good solar cells such as high absorption coefficient, mobility and charge carrier lifetime and study their interdependences and how they determine the efficiency at different thickness of the solar cell. Finally, we study some microscopic parameters such as the effective mass or electron-phonon coupling in a device to identify key microscopic properties that are likely to lead to a combination of high absorption, high mobilities and long lifetimes and thereby high photovoltaic efficiencies
  • seminar
    Date:
    31 March
    2019
    Sunday
    Hours:
    11:00

    Physical modelling of canopy flows

    Location: Sussman Family Building for Environmental Sciences
    participants: Yardena Raviv
    Biological Institute
  • seminar
    Date:
    26 March
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    SOD1 structure - Toward understanding of ALS pathogenesis

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Stas Engel
    Ben Gurion University
  • seminar
    Date:
    24 March
    2019
    Sunday
    Hours:
    11:00
    -
    12:00

    Interfacial rheology - why, what, and how

    Location: Perlman Chemical Sciences Building
    participants: Prof. Moshe Gottlieb
    Dept of Chemical Engineering, Ben Gurion University

    Abstract

    The idea that complex liquid-air interfaces laden with surfactants, colloids, or polymer molecules, possess rheological properties that differ from those of the bulk sub-phase has been suggested 150 years ago. Yet, even today we are still struggling with the means to properly measure these properties. In this talk we will first explore the reasons to worry at all about the properties of the interface, examine some of the consequences of interfacial rheology, and revisit a century old technique - the unjustifiably named “Langmuir trough”, pointing out some experimental peculiarities.
  • seminar
    Date:
    24 March
    2019
    Sunday
    Hours:
    11:00

    Multiphase Chemistry of Organic Aerosols and Reactive Oxygen Species in the Atmosphere

    Location: Sussman Family Building for Environmental Sciences
    participants: Manabu Shiraiwa
    UCI
  • seminar
    Date:
    19 March
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    Degron discovery: Hunt for the elusive dark matter of protein quality control

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Tommer Ravid
    HUJI
  • seminar
    Date:
    17 March
    2019
    Sunday
    Hours:
    11:00

    Reductionist vs. Emergence-based approaches to the study of complex systems: Examples from cloud systems

    Location: Sussman Family Building for Environmental Sciences
    participants: Graham Feingold
    NOAA
  • seminar
    Date:
    14 March
    2019
    Thursday
    Hours:
    10:00
    -
    11:00

    Nonlinear light-matter interaction: from superconducting qubits to spins in diamond

    Location: Perlman Chemical Sciences Building
    participants: Prof. Eyal Buks
    Faculty of Electrical Engineering, Technion

    Abstract

    The talk is devoted to the study of the light-matter interaction in the nonlinear regime using three different cavity quantum electrodynamics (CQED) systems. The matter under study is a Josephson flux qubit in the first experiment [1], a spin ensemble of diphenylpicrylhydrazyl (DPPH) molecules in the second one, and different spin ensembles in a diamond lattice in the third one [3]. In all three experiments the matter under study interact with photons (light) confined in a superconducting microwave resonator (cavity). A variety of nonlinear effects are explored, including super-harmonic resonances, multi-photon resonances, effective cavity heating and cooling and motional narrowing induced by quantum-jumps. The effect of nonlinearity on spin detection sensitivity will be discussed. 1. Eyal Buks, Chunqing Deng, Jean-Luc F.X. Orgazzi, Martin Otto and Adrian Lupascu, Phys. Rev. A 94, 033807 (2016). 2. Hui Wang, Sergei Masis, Roei Levi, Oleg Shtempluk and Eyal Buks, Phys. Rev. A 95, 053853 (2017). 3. Nir Alfasi, Sergei Masis, Roni Winik, Demitry Farfurnik, Oleg Shtempluck, Nir Bar-Gill and Eyal Buks, Phys. Rev. A 97 (2018).
  • seminar
    Date:
    13 March
    2019
    Wednesday
    Hours:
    11:00
    -
    12:00

    The Lab on a Beam: From Learning Physics to Atomic Manipulation in Scanning Transmission Electron Microscopy

    Location: Perlman Chemical Sciences Building
    participants: Dr. Sergei Kalinin
    Institute for Functional Imaging of Materials (IFIM), Oak Ridge National Lab

    Abstract

    Atomically-resolved imaging of materials has become the mainstay of modern materials science, as enabled by advent of aberration corrected scanning transmission electron microscopy (STEM). However, the wealth of quantitative information contained in the fine details of atomic structure or spectra remains largely unexplored. In this talk, I will present the new opportunities enabled by physics-informed big data and machine learning technologies to extract physical information from static and dynamic STEM images. The deep learning models trained on theoretically simulated images or labeled library data demonstrate extremely high efficiency in extracting atomic coordinates and trajectories, converting massive volumes of statistical and dynamic data into structural descriptors. I further present a method to take advantage of atomic-scale observations of chemical and structural fluctuations and use them to build a generative model (including near-neighbor interactions) that can be used to predict the phase diagram of the system in a finite temperature and composition space. Similar approach is applied to probe the kinetics of solid-state reactions on a single defect level and defect formation in solids via atomic-scale observations. Finally, synergy of deep learning image analytics and real-time feedback further allows harnessing beam-induced atomic and bond dynamics to enable direct atom-by-atom fabrication. Examples of direct atomic motion over mesoscopic distances, engineered doping at selected lattice site, and assembly of multiatomic structures will be demonstrated. These advances position STEM towards transition from purely imaging tool for atomic-scale laboratory of electronic, phonon, and quantum phenomena in atomically-engineered structures.
  • seminar
    Date:
    12 March
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    What makes tetra-ubiquitin a preferred signal for targeting proteins to the proteasome?

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Michael Glickman
    Technion
  • seminar
    Date:
    12 March
    2019
    Tuesday
    Hours:
    11:00
    -
    12:00

    Towards Increased Complexity in Dynamic Covalent Systems and Metal-Organic Cages

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Anna McConnell
    Otto-Diels-Institut für Organische Chemie Christian-Albrechts-Universität zu Kiel

    Abstract

    Anna McConnell, Otto Diels Institute of Organic Chemistry, Christian-Albrechts-Universität zu Kiel The supramolecular toolbox enables the self-assembly of supramolecular architectures from relatively simple building blocks through reversible, weak non-covalent interactions. Supramolecular architectures with increased complexity are appealing targets for not only the synthetic challenge but also for the potential to access new types of chemistry and functionality. Efforts towards increasing the complexity of both the supramolecular architecture and stimuli-responsive behaviour[1] in dynamic covalent and metal-organic cage systems will be presented. In one approach, the post-assembly reduction of achiral iminoboronates gives access to three isomeric products containing two stereogenic centres and two of these products interconvert through unusual lability of the covalent B-N bonds.[2] In another approach, progress towards the development and characterisation of spin-crossover cages[3] with increased complexity will be discussed. References [1] A. J. McConnell, C. S. Wood, P. P. Neelakandan, J. R. Nitschke, Chem. Rev. 2015, 115, 7729-7793. [2] E. N. Keyzer, A. Sava, T. K. Ronson, J. R. Nitschke, A. J. McConnell, Chem. Eur. J. 2018, 24, 12000-12005. [3] A. J. McConnell, Supramol. Chem. 2018, 30, 858-868.
  • seminar
    Date:
    12 March
    2019
    Tuesday
    Hours:
    10:00
    -
    11:00

    Spectral editing techniques for chemical exchange saturation transfer imaging

    Location: Perlman Chemical Sciences Building
    participants: Prof. Jiadi Xu
    Kennedy Krieger Institute and Johns Hopkins School of Medicine

    Abstract

    Chemical exchange saturation transfer (CEST) imaging is a relatively new MRI technology allowing the detection of low concentration endogenous cellular proteins and metabolites indirectly through water. CEST MRI is still under development and one major impediment for more widespread application is limited specificity due to spectral overlap of CEST signal from other metabolites and proteins. In this presentation, I will demonstrate several novel CEST spectral editing techniques developed by our group to extract information from CEST images, such as one variable delay multi pulse (VDMP) CEST that acts an exchange rate filter to separate CEST effects from the confounding factors, one ultra-short echo (UTE)-CEST method that can monitor in vivo protein aggregation process and one polynomial and Lorentzian line-shape fitting (PLOF) CEST that can detect creatine and phosphocreatine in tissue with high specialty. Their applications on the stroke and Alzheimer’s disease models will be covered. At last, I will explore one artificial neural network approach to overcome the challenges of implementing the CEST technique on 3T clinical MRI scanners.
  • seminar
    Date:
    11 March
    2019
    Monday
    Hours:
    13:00

    The Israel Young Academy

    Location: Jacob Ziskind Building
    participants: Professor Eran Bouchbinder
    Department of Chemical and Biological Physics

    Abstract

    Professor Eran Bouchbinder recently completed his term as Chair of the Israel Young Academy. To mark the event and to learn more about the Israel Young Academy, Eran will describe the role of the Young Academy in the Israeli academic society
  • seminar
    Date:
    11 March
    2019
    Monday
    Hours:
    11:00
    -
    12:00

    Making the right disulfides-- the role of redox and protein structure

    Location: Arthur and Rochelle Belfer Building for Biomedical Research
    participants: Prof. Neil Bulleid
    Director of the Institute of Molecular Cell & Systems Biology University of Glasgow
  • seminar
    Date:
    10 March
    2019
    Sunday
    Hours:
    11:00
    -
    12:00

    Charge Regulation in Colloid Solutions and other Complex Fluids

    Location: Perlman Chemical Sciences Building
    participants: Prof. David Andelman
    School of Physics, TAU

    Abstract

    The phenomenon of charge regulation was introduced by Ninham and Parsegian almost 50 years ago and was successfully applied in many studies to charged surfaces in contact with an electrolyte. We revisit the charge-regulation mechanism within the Poisson-Boltzmann theory, and apply it to mobile macro-ions in a bathing salt solution. Our findings are, in particular, relevant for solutions of proteins, whose exposed amino acids can undergo charge dissociation/association processes to/from the bathing solution, and can be considered as solution of charged regulated macro-ions
  • seminar
    Date:
    10 March
    2019
    Sunday
    Hours:
    11:00

    The interior of Jupiter revealed by Juno

    Location: Sussman Family Building for Environmental Sciences
    participants: Jamila Miguel
    Leiden
  • seminar
    Date:
    7 March
    2019
    Thursday
    Hours:
    10:00
    -
    11:00

    Pulsed Dipolar EPR Spectroscopy: From Model Systems to In-Cell

    Location: Perlman Chemical Sciences Building
    participants: Prof. Olav Schiemann
    Institute for Physical and Theoretical Chemistry, University of Bonn

    Abstract

    Understanding the function of biomolecules on a molecular level requires knowledge about their structure and conformational changes during function. Site directed spin labeling (SDSL) in combination with pulsed dipolar EPR spectroscopy (PDS) enables to gather such information on the nanometer length scale. In the talk, it will be shown that this approach enables the localization of metal ions within the fold of biomolecules, also of those metal ions with large zero-field splitting, where the high-field approximation breaks down. It will also be shown that this cannot only be done in vitro but also within cells. Last but not least, an example will be given where a conformational change of a protein is not only followed on the length- but also on the microsecond time resolution using PDS/SDSL.
  • seminar
    Date:
    5 March
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    Structural Basis for Serum Amyloid A Function in Lipid Homeostasis and Immune Response: A Novel Function for an Ancient Protein

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Olga Gursky
    Boston University School of Medicine
  • seminar
    Date:
    5 March
    2019
    Tuesday
    Hours:
    11:00
    -
    12:00

    Adventures of bambusuril chemistry

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Vladimir Sindelar
    Department of Chemistry & RECETOX Masaryk University

    Abstract

    Bambus[n]urils (BU[n]) are macrocyclic molecules discovered by our group and first published in 2010.1,2 They consist of n glycoluril units connected by n methylene bridges. Only four- (n = 4) and six- (n = 6) membered homologues of BU[n] have been isolated so far. Most attention is paid to BU[6] (Figure 1) as this macrocycle is one of the most potent anion receptors for many inorganic anions in water and organic solvents. In this lecture, some important aspects of bambusuril chemistry will be highlighted. The synthesis of BU[6]s will be discussed with emphasis on a template effect, the installation of various substituents on the bambusuril framework, and removal of a templating anion from the BU[6] cavity. Driving forces responsible for the outstanding ability of BU[6] to bind anions in water will be explained and some recent examples of BU[6] applications including anion sensing and anion transport will be given. Finally, approaches leading to chiral bambusurils will be discussed and the first examples of such macrocycles will be presented as well as their use in enantiomer recognition. Figure 1. Structure of bambus[6]urils. References [1] J. Svec, M. Necas and V. Sindelar, Angew. Chem. Int. Ed., 2010, 49, 2378. [2] T. Lizal and V. Sindelar, Isr. J. Chem. 2018, 58, 326.
  • seminar
    Date:
    3 March
    2019
    Sunday
    Hours:
    11:00

    Sensitivity Analysis and Uncertainty Quantification in Hydrogeological Modeling

    Location: Sussman Family Building for Environmental Sciences
    participants: Alberto Guadagnini
    Politenico di Milano
  • seminar
    Date:
    28 February
    2019
    Thursday
    Hours:
    14:00
    -
    15:00

    Mn(II) EPR tracks the hydrolysis state and ATP/ADP dependent conformation in yeast Hsp90 chaperone

    Location: Perlman Chemical Sciences Building
    participants: Dr. Angeliki Giannoulis
    Department of Chemical and Biological Physics, WIS

    Abstract

    Hsp90 plays a central role in cell homeostasis by assisting folding and maturation of many client proteins. In order to perform this chaperoning activity Hsp90 hydrolyzes ATP, which requires Mg(II) as cofactor and the hydrolysis is coupled to large global conformational changes. Hsp90 is homo-dimeric with each monomer consisting of three consecutive domains (CTD, MD, NTD). The ATPase site is found in each of the two NTDs, while the CTDs constitute the dimerization site. X-ray crystallography and FRET have provided insights on the conformational cycle of Hsp90 which involves transition from a nucleotide-free ‘open’ to a nucleotide-bound ‘closed’ conformation by dimerization of the NTDs. However, there are still open questions on whether the chaperone shifts global conformation as a consequence of hydrolysis. Here, we investigate the ATPase site and the concomitant conformational changes at various nucleotide-bound states (pre-hydrolysis, intermediate high energy and post- hydrolysis states) in yeast Hsp90 using EPR techniques. To do so, we substituted the Mg(II) cofactor with paramagnetic Mn(II) and performed hyperfine and pulsed dipolar EPR experiments, to probe short and long range interactions, respectively. Specifically, we tracked ATP hydrolysis by exploring the Mn(II) coordination by the nucleotide phosphates using 31P electron nuclear double resonance (ENDOR) spectroscopy. The interaction of the Mn(II) with protein residues in the different hydrolysis states was investigated by 14/15N ELDOR-detected nuclear magnetic resonance (EDNMR). Last, we measured the distance between the two Mn(II) cofactors in each of the monomers using double electron–electron resonance (DEER/PELDOR) spectroscopy. Here, we measured a well-defined Mn(II)-Mn(II) distance of 4.3 nm in the pre-hydrolysis state, which changes both in width and mean distance in the post-hydrolysis state providing experimental evidence to the existence of two different ‘closed’ conformations for the ATP and ADP bound states. Within our approach one can probe both local and global interactions from a single sample via exploitation of intrinsic sites (here Mg(II)->Mn(II)) that can potentially yield new structural insights previously challenging to observe with FRET and EPR using site-specific spin labeling.
  • seminar
    Date:
    28 February
    2019
    Thursday
    Hours:
    11:00
    -
    12:00

    DLTS defects characterization of process and irradiation induced defects in 4H-SiC

    Location: Perlman Chemical Sciences Building
    participants: Prof. Mmantsae Diale
    Dept. of Physics, University of Pretoria

    Abstract

    4H-SiC epitaxial layers were irradiated using various radioactive sources and particle accelerators. The electronic properties of induced defects were characterized by means of deep-level transient spectroscopy (DLTS) and Laplace DLTS. This presentation is a review of various observations due to processing various particles used in irradiation of 4H-SiC. From the results it was evident that the same defects were induced by various radiation sources. Irradiation induced the acceptor level of the Z1 center and the donor level of the Z2 center. The concentration of the native defects, which originate from impurities encountered in the growth process increased. DLTS spectra observed after irradiation were exhibited sitting on skewed baselines which in some instances inhibited accurate Laplace-DLTS resolution.
  • seminar
    Date:
    28 February
    2019
    Thursday
    Hours:
    11:00
    -
    12:00

    "DLTS defects characterization of process and irradiation induced defects in 4H-SiC”

    Location: Perlman Chemical Sciences Building
    participants: Prof. Mmantsae Diale
    Dept. Of Physics, University of Pretoria

    Abstract

    4H-SiC epitaxial layers were irradiated using various radioactive sources and particle accelerators. The electronic properties of induced defects were characterized by means of deep-level transient spectroscopy (DLTS) and Laplace DLTS. This presentation is a review of various observations due to processing various particles used in irradiation of 4H-SiC. From the results it was evident that the same defects were induced by various radiation sources. Irradiation induced the acceptor level of the Z1 center and the donor level of the Z2 center. The concentration of the native defects, which originate from impurities encountered in the growth process increased. DLTS spectra observed after irradiation were exhibited sitting on skewed baselines which in some instances inhibited accurate Laplace-DLTS resolution.
  • seminar
    Date:
    28 February
    2019
    Thursday
    Hours:
    10:00
    -
    11:00

    Publishing in Nature Communications

    Location: Perlman Chemical Sciences Building
    participants: Dr. Bo Liu
    Associate Editor, Nature Communications

    Abstract

    In this talk, I will introduce the Nature Communications journal, the editorial office in Shanghai, the editorial process and insiders’ view on the Nature Communications. Bo joined Nature Communications in March 2017. Following his undergraduate studies in Zhejiang University, China, he obtained his PhD in Physics at National University of Singapore. He then carried out his postdoctoral research at Graphene Research Center in Singapore and University of Washington. He currently handles manuscripts on solar cells and halide perovskite photophysics. Bo is based in the Shanghai office.
  • seminar
    Date:
    27 February
    2019
    Wednesday
    Hours:
    11:00
    -
    12:00

    Diamond quantum technologies: magnetic sensing, hyperpolarization and noise spectroscopy

    Location: Perlman Chemical Sciences Building
    participants: Prof. Nir Bar-Gill
    Dept. of Applied Physics, Racah Institute of Physics, HUJI

    Abstract

    Nitrogen Vacancy (NV) centers in diamond have emerged over the past few years as well-controlled quantum systems, with promising applications ranging from quantum information science to magnetic sensing. In this talk, I will first introduce the NV center system and the experimental methods used for measuring them and controlling their quantum spin dynamics. I will mention the application of magnetic sensing using NVs through the realization of a magnetic microscope [1]. I will then describe our work on nuclear hyperpolarization, potentially relevant for enhanced MRI contrast, and research into open quantum systems and quantum thermodynamics [2]. Finally, I will present related control sequences, which can be used to perform optimized quantum noise spectroscopy, allowing for precise characterization of the environment surrounding a quantum sensor [3]. 1. E. FARCHI ET. AL., SPIN 7, 1740015 (2017). 2. HOVAV, Y., NAYDENOV, B., JELEZKO, F. AND BAR-GILL, N., PHYS. REV. LETT. 120, 6, 060405 (2018) 3. Y. ROMACH ET. AL., PHYS. REV. APPLIED 11, 014064 (2019).
  • seminar
    Date:
    26 February
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    Diffusion-Enhanced Photon Inference (DEPI) for accurate retrieval of distance distributions in single-molecule FRET experiments

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Eitan Lerner
    HUJI
  • seminar
    Date:
    26 February
    2019
    Tuesday
    Hours:
    11:00
    -
    12:00

    Chemical and Biological Physics and Organic Chemistry Seminar

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof Michael J. Therien
    Duke University ‎

    Abstract

    The trion, a three-body charge-exciton bound state, offers unique opportunities to simultaneously manipulate charge, spin and excitation in one-dimensional single-walled carbon nanotubes (SWNTs) at room temperature. Effective exploitation of trion quasiparticles requires fundamental insight into their creation and decay dynamics. Such knowledge, however, remains elusive for SWNT trion states, due to the electronic and morphological heterogeneity of commonly interrogated SWNT samples, and the fact that transient spectroscopic signals uniquely associated with the trion state have not been identified. Here length-sorted SWNTs and precisely controlled charge carrier-doping densities are used to determine trion dynamics using femtosecond pump-probe spectroscopy. Identification of the trion transient absorptive hallmark enables us to demonstrate that trions (i) derive from a precursor excitonic state, (ii) are produced via migration of excitons to stationary hole-polaron sites, and (iii) decay in a first-order manner. Importantly, under appropriate carrier-doping densities, exciton-to-trion conversion in SWNTs can approach 100% at ambient temperature. We further show that ultrafast pump-probe spectroscopy, coupled with these fundamental insights into trion formation and decay dynamics, enables a straightforward approach for quantitatively evaluating the extent of optically-driven free carrier generation (FCG) in SWNTs: this work provides fundamental new insights into how quantum yields for optically-driven FCG [Φ(Enn → h+ + e−)] in SWNTs may be modulated as functions of the optical excitation energy and medium dielectric strength. Collectively, these findings open up new possibilities for exploiting trions in SWNT optoelectronics, ranging from photovoltaics, photodetectors, to spintronics.
  • seminar
    Date:
    24 February
    2019
    Sunday
    Hours:
    15:00
    -
    16:00

    Halide perovskites: A new class of semiconductors with emergent properties

    Location: Perlman Chemical Sciences Building
    participants: Prof. Aditya Mohite
    Dept. of Chemical and Biomolecular Engineering, Rice University

    Abstract

    Halide (hybrid) perovskites (HaP) have emerged as a new class of semiconductors that truly encompass all the desired physical properties for building optoelectronic and quantum devices such as large tunable band-gaps, large absorption coefficients, long diffusion lengths, low effective mass, good mobility and long radiative lifetimes. In addition, HaPs are solution processed or low-temperature vapor grown semiconductors and are made from earth abundant materials thus making them technologically relevant in terms of cost/performance. As a result, proof-of-concept high efficiency optoelectronic devices such as photovoltaics and LEDs have been fabricated. In fact, photovoltaic efficiencies have sky rocketed to 23% merely in the past five years and are nearly on-par with mono-crystalline Si based solar cells. Such unprecedented progress has attracted tremendous interest among researchers to investigate the structure-function relationship and understand as to what makes Halide hybrid perovskites special? In my talk, I will attempt to answer some of the key questions and in doing so share the results from our work on HaPs over the past four years in understanding structure induced properties of HaPs. I will also highlight fundamental bottlenecks that exist going forward which present opportunities to create platforms to understand the interplay between light, fields and structure on the properties of perovskite-based materials.
  • seminar
    Date:
    24 February
    2019
    Sunday
    Hours:
    14:00
    -
    15:00

    An insight into symmetry properties of halide perovskites

    Location: Perlman Chemical Sciences Building
    participants: Prof. Jacky Even
    FOTON Institut, CNRS, INSA Rennes

    Abstract

    3D halide perovskites have emerged as a new class of semiconductors, but some basic optoelectronic properties of 3D bulk halide perovskites are still shrouded in mystery. The talk will start from a simplified representation of the halide perovskite lattice allowing to progressively account for various advanced topics.
  • seminar
    Date:
    24 February
    2019
    Sunday
    Hours:
    11:00

    Scattering of radiation by porous and amorphous atmospheric aerosol

    Location: Sussman Family Building for Environmental Sciences
    participants: Caryn Erlick-Haspel
    Hebrew University
  • seminar
    Date:
    24 February
    2019
    Sunday
    Hours:
    11:00
    -
    12:00

    Network Formation of Oppositely Charged Polyelectrolytes

    Location: Perlman Chemical Sciences Building
    participants: Prof. Eyal Zussman
    NanoEngineering group, Department of Mechanical Engineering, Technion-

    Abstract

    Mixing semi-dilute solutions of oppositely charged polyelectrolytes generally yields compositions spanning complexes (solid) to coacervates (elastic liquid) to dissolved solutions with increasing salt concentration. In this work we show how to form a strong network of oppositely charged polyelectrolytes by using an interplay of hydrogen, hydrophobic, and electrostatic interactions.
  • seminar
    Date:
    21 February
    2019
    Thursday
    Hours:
    10:00
    -
    11:00

    NMR Across the Periodic Table: Observing "Invisible" Nuclides in Solid Materials

    Location: Perlman Chemical Sciences Building
    participants: Prof. Robert Schurko
    Department of Chemistry and Biochemistry, University of Windsor, Ontario

    Abstract

    Recent developments in pulse sequences and NMR hardware have opened up many "exotic" nuclides in the periodic table to experimentation by solid-state NMR. Many of these nuclides are classified as unreceptive, and have been avoided by NMR spectroscopists and chemists in general, due to factors such as low Larmor frequencies, low natural abundances, inconveniently short or long relaxation times, etc. In addition, there are numerous systems in which these nuclides have extremely broad NMR patterns resulting from large anisotropic chemical shielding or quadrupolar interactions. Such nuclei have long been classified as "invisible", since their NMR spectra cannot be observed using standard NMR pulse sequences. In this lecture, I will show that there are several robust strategies one can apply to acquire high quality solid-state NMR spectra of a variety of nuclei, including 10B, 14N, 27Al, 35/37Cl, 47/49Ti, 59Co, 63/65Cu, 69/71Ga, 91Zr, 93Nb, 139La, 195Pt, and 209Bi. Ultra-wideline NMR spectra, when coupled with X-ray crystallography and ab initio methods, provide powerful probes of molecular structure in inorganic, organic and organometallic materials. New advances in dynamic nuclear polarization (DNP) NMR for the acquisition of ultra-wideline NMR spectra will also be discussed
  • seminar
    Date:
    20 February
    2019
    Wednesday
    Hours:
    10:00
    -
    11:00

    Protein assemblies ejected directly from native membranes yield complexes for mass spectrometry

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Dror Chorev
    Oxford University, UK
  • seminar
    Date:
    19 February
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    Translocation Mechanisms of Protein-Antibiotics

    Location: Helen and Milton A. Kimmelman Building
    participants: Dr. Ruth Cohen Khait
    Oxford University, UK
  • seminar
    Date:
    19 February
    2019
    Tuesday
    Hours:
    11:00
    -
    12:00

    Molecule-metal interface - analysis and optimization

    Location: Perlman Chemical Sciences Building
    participants: Prof. Piotr Cyganik
    Smoluchowski Institute of Physics, Jagiellonian University, Krakow

    Abstract

    A few nanometer thin interface which is formed between the metal and the organic structure controls bonding strength, stability and charge transfer between these two quite different types of materials. To understand and optimize formation of that interface at the nanoscale we used Self-Assembled Monolayers (SAMs) which are considered a model system for the analysis of the interaction of organic molecules with the metal substrate. In this presentation we will focus on application of a new experimental approach based on ion beam-induced desorption which we used to address this problem demonstrating for the first time the effect of oscillations in stability of consecutive chemical bonds at the molecule-metal interface. As a next step we will analyze the consequence of this effect for the thermal stability of a model SAM systems and, finally, we will discuss how this effect can contribute to the charge transport at the molecule-metal interface
  • seminar
    Date:
    17 February
    2019
    Sunday
    Hours:
    11:00

    Geostrophic Turbulence and the Formation of Large Scale Structure

    Location: Sussman Family Building for Environmental Sciences
    participants: Edgar Knobloch
    Department of Physics University of California, Berkley
  • seminar
    Date:
    14 February
    2019
    Thursday
    Hours:
    11:00

    Chemical and Biological Physics Guest Seminar

    Location: Perlman Chemical Sciences Building
    participants: Prof. Dr. Richard Berndt
    Institute of Experimental and Applied Physics Christian-Albrechts-‎University, Kiel, Germany

    Abstract

    Using low-temperature scanning tunneling microscopy we investigate molecular and atomic structures at single crystal surfaces to explore their electron transport properties from the tunnelling range to ballistic transport. The experiments aim at maximizing the control over the junction properties and probe conductances, forces, shot-noise, and the emission of photons. We are particularly interested in molecules that exhibit switching behaviour of, e.g., their conformations or spin states. Results from metallic and molecular junctions will be presented.
  • seminar
    Date:
    12 February
    2019
    Tuesday
    Hours:
    14:00
    -
    15:00

    Posing a contortionist E3 ubiquitin ligase for stepwise regulation of cell division

    Location: Wolfson Building for Biological Research
    participants: Prof. Brenda Schulman
  • seminar
    Date:
    11 February
    2019
    Monday
    Hours:
    14:00
    -
    15:00

    Plasmonic photo-catalysis - “Hot electrons” or just heating?”

    Location: Perlman Chemical Sciences Building
    participants: Prof. Yonatan Dubi
    Department of Chemistry & The Ilze-Katz Institute for Nano-Scale Science and Technology, BGU

    Abstract

    What happens to electrons in a metal when they are illuminated? This fundamental problem is a driving force in shaping modern physics since the discovery of the photo-electric effect. In recent years, this problem resurfaced from a new angle, owing to developments in the field of nano-plasmonics, where metallic nanostructures give rise to resonantly enhanced local electromagnetic fields (surface plasmons). Presumably, these plasmons can transfer their energy to the electrons in the metal very efficiently, creating “hot electrons”, i.e. energetic electrons out of equilibrium. Such energetic electrons have been demonstrated to be useful in a variety of ways, most recently in catalysis of chemical reactions. Or have they? In this talk we argue that what appears to be hot-electron-mediated photo-catalysis is really a simple heating effect. We present a theory for plasmonic hot-electron generation, which takes into account non-equilibrium as well as thermal effects. Specifically, we consider the effect of both photons and phonons on the electron distribution function, and calculate self-consistently the full electron distribution and the increase in electron and lattice temperatures above ambient conditions (as observed experimentally), thus going well beyond the limit of existing theories. Calculating the efficiency of hot-electron generation, we find that it is extremely small, and most power goes into heating. We use this theory to re-interpret data from central experiments claiming hot-electron generation, and find that the data fits remarkably a simple theory of heating. Finally, we suggest control experiments to further test our conclusions, and discuss the prospect of using the hot electrons for photocatalysis.
  • seminar
    Date:
    11 February
    2019
    Monday
    Hours:
    11:00
    -
    12:00

    Chemical tools for manipulating the topology of polymer networks

    Location: Helen and Milton A. Kimmelman Building
    participants: Prof. Jeremiah A. Johnson
    Department of Chemistry, Massachusetts Institute of Technology
  • seminar
    Date:
    10 February
    2019
    Sunday
    Hours:
    14:00
    -
    15:00

    Recovering exact conditions at semi-local DFT cost to