Events | Seminar

  • seminar
    Date:
    25 June
    2024
    Tuesday
    Hours:
    11:00
    -
    12:00

    Molecular Manipulation of Heterogeneous Electrocatalysis Using Metal-Organic Frameworks

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Idan Hod
    Department of Chemistry at Ben-Gurion University of the Negev, BGU

    Abstract

    Electrocatalytically driven reactions that produce alternative fuels and chemicals are considered as a useful means to store renewable energy in the form of chemical bonds. in recent years there has been a significant increase in research efforts aiming to develop highly efficient electrocatalysts that are able to drive those reactions. Yet, despite having made significant progress in this field, there is still a need for developing new materials that could function both as active and selective electrocatalysts. In that respect, Metal–Organic Frameworks (MOFs), are an emerging class of hybrid materials with immense potential in electrochemical catalysis. Yet, to reach a further leap in our understanding of electrocatalytic MOF-based systems, one also needs to consider the welldefined structure and chemical modularity of MOFs as another important virtue for efficient electrocatalysis, as it can be used to fine-tune the immediate chemical environment of the active site, and thus affect its overall catalytic performance. Our group utilizes Metal-Organic Frameworks (MOFs) based materials as a platform for imposing molecular approaches to control and manipulate heterogenous electrocatalytic systems. In this talk, I will present our recent study on electrocatalytic schemes involving MOFs, acting as: a) electroactive unit that incorporates molecular electrocatalysts, or b) non-electroactive MOF-based membranes coated on solid heterogenous catalysts.
  • seminar
    Date:
    16 June
    2024
    Sunday
    Hours:
    11:00

    On Microbes and Mountains: Unraveling the Links Between Microbial Weathering and Large-Scale Surface Processes

    Location: Sussman Family Building for Environmental Sciences
    participants: Michal Ben-Israel
    University of California

    Abstract

    Microorganisms play a crucial role in the weathering processes that transform rock into soil through chemical and physical mechanisms essential for nutrient cycling, nitrogen fixation, carbon storage, and organic matter decomposition. This intricate relationship between microbial life and landscapes forms the backbone of ecosystem dynamics and biogeochemical processes. Microbes influence rock weathering and soil production, adapting to their surroundings and creating distinct communities across various landscapes. These complex interactions and feedback mechanisms are pivotal to understanding the co-evolution of microbial communities and landscapes over time. However, existing research on microbial contributions to weathering and soil production has predominantly focused on relatively short timescales and small spatial scales. Understanding the interplay between the evolution of microbial communities and their role in weathering processes over geomorphic timescales within transient landscapes is important for a more complete understanding of how landscapes evolve as well as the impact of geomorphic changes on microbial community establishment and evolution. The main objective of this study is to elucidate the long-term dynamics of microbial communities and their role in weathering processes over millennial timescales. To achieve this, we focused on recently deglaciated basins in the Eastern Sierra Nevada, CA, examining bacterial community composition in three phases of the weathering process: exposed rock at the surface, saprolite—the weathered rock found beneath soil, and soil. Sampling along an elevational transect, we collected 25 samples of rock, soil, and saprolite, and evaluated their bacterial composition using 16S rRNA and metagenomic sequencing. Results show that both soil and saprolite samples exhibited diverse and similar microbial communities, indicating a developmental relationship between these habitats despite distinct geochemical compositions. In contrast, rock habitats are less diverse, and their composition resembles those of young deglaciated landscapes. Our findings point to a link between microbial community composition and rock-to-soil weathering processes, suggesting that the majority of weathering processes occur within the soil column (saprolite and soil), with exposed rock maintaining a steady state. The stability of these microbial communities over extended timescales suggests a potentially significant role for microbial weathering in landscape evolution. This finding underscores the importance of considering microbial contributions in future geomorphic studies, as they may play a key role in shaping the Earth's surface. Moving forward, we plan on coupling a long-term, landscape-scale geomorphic perspective with 'omics approaches from microbial ecology to comprehensively understand the complex relationships between microbial life and landscapes, ultimately advancing our knowledge of ecosystem dynamics and health.
  • seminar
    Date:
    4 June
    2024
    Tuesday
    Hours:
    14:00
    -
    15:00

    Synthetic Biology Platforms to Study Biological Systems and for Biomedical Applications

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Lior Nissim
    The Faculty of Medicine Hebrew University
  • seminar
    Date:
    2 June
    2024
    Sunday
    Hours:
    11:00

    The Role of Cloud Morphology in Aerosol-Cloud Interactions 

    Location: Sussman Family Building for Environmental Sciences
    participants: Tom Goren
    Bar Ilan University

    Abstract

    Aerosol-cloud interactions are extensively studied to understand the climatic effect of anthropogenic aerosols, as the latter can change the radiative properties of clouds. Despite the clear presence of different cloud morphologies (i.e., the spatial variation of cloud thickness), the impact of aerosol-cloud interactions under different cloud morphologies is often overlooked. I will show that accounting for cloud morphology is essential for a better process understanding and for an accurate assessment of the radiative forcing due to aerosol-cloud interactions.
  • seminar
    Date:
    29 May
    2024
    Wednesday
    Hours:
    14:00
    -
    15:00

    Measuring conformational equilibria in allosteric proteins with time-resolved tmFRET

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Sharona Gordon
    Professor of Physiology & Biophysics, University of Washington School of Medicine
  • seminar
    Date:
    28 May
    2024
    Tuesday
    Hours:
    14:00
    -
    15:00

    How to Enhance Sex Determination?

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Nitzan Gonen
    The Mina and Everard Goodman Faculty of Life Sciences Institute of Nanotechnology and Advanced Materials, Bar-Ilan University
  • seminar
    Date:
    21 May
    2024
    Tuesday
    Hours:
    14:00
    -
    15:00

    Molecular-level insights into light-induced reactions in biological systems from multiscale simulations

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Igor Shapiro
    Hebrew University
  • seminar
    Date:
    19 May
    2024
    Sunday
    Hours:
    11:00

    Floods in a warming climate: what are the missing puzzle pieces?

    Location: Sussman Family Building for Environmental Sciences
    participants: Efrat Morin
    The Hebrew University of Jerusalem

    Abstract

    Flood is the outcome of complex processes interacting at a range of scales. Flood generation and its magnitude depend on different precipitation and surface properties. As the climate becomes warmer globally, precipitation patterns are changing and, consequently, altering flood regimes. Resolving the expected changes in flood properties requires examining projections of precipitation features most correlated with floods. While the redistribution of mean annual precipitation amounts is generally known, the trends in many other essential factors controlling floods are yet to be resolved. For example, flash flood magnitude is sensitive to space-time rainstorm properties such as areal coverage or storm speed. Still, knowledge of how these properties are affected by global warming is lacking. Maximal rain rates for duration relevant to the watershed’s response time are also crucial parameters controlling the flood discharge. There is some understanding of how extreme rain rates change, but the magnitude and sign depend on the rain duration considered. Changes in frequency and the intra-seasonal distribution of precipitation events also affect flood regimes. Finally, watersheds of different properties are sensitive to different precipitation features, and thus, different watersheds may respond differently to global warming. In this talk, we will present the complexity of flood response under global warming and then focus on two questions: 1) how does global warming affect heavy precipitation events (HPEs) in the eastern Mediterranean, and 2) how these effects are imprinted in the resulting floods in small-medium Mediterranean watersheds. We simulated 41 eastern Mediterranean HPEs with the high-resolution weather research and forecasting (WRF) model. Each event was simulated twice: under historical conditions and at the end of the 21st-century conditions (RCP8.5 scenario) using the “pseudo global warming” approach. Comparison of precipitation patterns from the paired simulations revealed that heavy precipitation events in our region are expected to become drier and more spatiotemporally concentrated, i.e., we expect higher rain rates on smaller coverage areas and shorter storm durations that, in total, yield lower amounts of rainfall. These effects have some contradicting signs, and their full hydrological impact on streamflow peak discharge and volume was further explored. Ensembles of spatially-shifted rainfall data from the simulated HPEs were input to a high-resolution distributed hydrological model (GB-HYDRA) representing four small-medium-size watersheds (18–69 km2) in the eastern Mediterranean (Ramot Menashe). Flow volume is significantly reduced in future HPEs, while the change in flood peak is more complicated due to the combined effect of precipitation amount (decreasing) and precipitation rate (increasing). For the watersheds examined in this research, which are mostly agricultural, flood peaks at the watershed outlets are mostly reduced. The dynamics of flood generation at sub-watersheds of different sizes and properties are further examined in this research to understand scenarios for lowering or increasing flood peaks. This study emphasizes that detecting and quantifying global warming impact on space-time precipitation patterns is essential for flood regime projection.
  • seminar
    Date:
    12 May
    2024
    Sunday
    Hours:
    11:00

    Lake Kinneret in a Changing Environment

    Location: Sussman Family Building for Environmental Sciences
    participants: Yael Amitai
    Israel Oceanographic and Limnological Research, The Yigal Alon Kinneret Limnological Laboratory

    Abstract

    Located in a highly sensitive subtropical climate area and a densely populated area, Lake Kinneret is poised to undergo both natural and human-induced transformations in the coming decades. The lake is thermally stratified throughout most of the year and mixes thoroughly each winter when the epilimnion (upper layer) water temperature reaches equilibrium with the hypolimnion (bottom layer) water temperature by surface cooling and turbulence. Both the stratified and the fully mixed periods has a significant role in the Kinneret’s ecological system. Observation shows that air above the Lake is warming in a rate of 0.4oC/decade, while the epilimnion and hypolimnion are warming in a rate of 0.3oC/decade and 0.1oC/decade, respectively, for the last 50 years. Therefore, stratification strength and duration is anticipated to change and impact the lake’s ecosystem. Additionally, the sequence of drought periods and the expected future rise in water demands from Lake Kinneret formed the basis for the government's decision to channel desalinated water, via the natural course of the Tzalmon Stream, to the lake to ensure its operational functionality at high levels. Using a 3D hydrodynamic model forced by short and long-term forecasts the above scenarios are examined and analyzed. A simulation forced by regional atmospheric RCP4.5 climate change scenario spanning from 2010-2070 show continuous warming followed by abrupt cooling of the lake water around the year 2065. This result, presumably due to enhanced latent heat loss, suggest a restrain the dramatic anticipated change in the lake stratification.
  • seminar
    Date:
    7 May
    2024
    Tuesday
    Hours:
    14:00
    -
    15:00

    Chemical Probes Reveal Mechanisms of Action of Antifungal Drugs and Guide Modifications to Improve Performance

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Micha Fridman
    School of Chemistry Tel-Aviv University
  • seminar
    Date:
    7 May
    2024
    Tuesday
    Hours:
    11:00

    Data Drought in the Humid Tropics: How to Overcome the Cloud Barrier in Greenhouse Gas Remote Sensing

    Location: Sussman Family Building for Environmental Sciences
    participants: Yinon Bar-On
    California Institute of Technology

    Abstract

    Quantifying land-atmosphere fluxes of carbon-dioxide (CO2) and methane (CH4) is essential for evaluating carbonclimate feedbacks. Greenhouse gas satellite missions aim to provide global observational coverage of greenhouse gas concentrations and thus improve inversions of landatmosphere exchange fluxes. However, in key regions such as the humid tropics current missions obtain very few valid measurements. Leveraging recent advances in the global analysis of high-resolution optical imagery on cloudcomputing platforms and deep learning algorithms for cloud segmentation, we quantitatively diagnose the sources for low data yields in the tropics. We find that the main cause for low data yields are frequent shallow cumulus clouds. We find that increasing the spatial resolution of observations to 200 m would increase yields by 2–3 orders of magnitude and allow regular measurements in the wet season. Thus, the key to effective tropical greenhouse gas observations likely lies in regularly acquiring high-spatial resolution data.
  • seminar
    Date:
    16 April
    2024
    Tuesday
    Hours:
    14:00
    -
    15:00

    High Throughput Approaches to Study the Roles of RNA Structures in Long RNAs

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Igor Ulitsky
    Department of Immunology and Regenerative Biology, Faculty of Biology, WIS
  • seminar
    Date:
    9 April
    2024
    Tuesday
    Hours:
    14:00
    -
    15:00

    What Funga can teach us about DNA repair

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Shay Covo
    Department of Plant Pathology and Microbiology Faculty of Agriculture, Food & Environment The Hebrew University of Jerusalem
  • seminar
    Date:
    7 April
    2024
    Sunday
    Hours:
    11:00

    Benthic side control on the chemical composition of the ocean

    Location: Sussman Family Building for Environmental Sciences
    participants: Zvi Steiner
    GEOMAR Helmholtz Centre

    Abstract

    The sediment – bottom-water interface is suggested as a key control on the chemical composition of the ocean by studies of trace elements in the ocean water-column, yet data regarding trace element fluxes and interactions taking place in the top ten cm of abyssal sediments are scarce. To bridge this gap, I analysed the trace and major element composition of porewater and sediment of red-clay sediment from the abyssal North Pacific, and hydrothermally influenced sediment from the Mid-Atlantic Ridge. The top sediment at both study regions is aerobic, nevertheless, there is large variability in the porewater concentrations of many elements at the top five cm. The North Pacific red-clay sediment is a source of cobalt, nickel, copper, arsenic, vanadium and barium to the deep-ocean, the magnitude of these fluxes is consistent with fluxes calculated based on the water-column distribution of most elements, and are equivalent to the global supply of these elements by rivers. The hydrothermally influenced sediment is a strong source of copper, zinc and cobalt up to three km from the vent due to oxidation of sulfide minerals. Close to the vents, the sediment is high in iron oxyhydroxides that adsorb the oxyanions vanadate, arsenate and phosphate, acting as a sink for these elements. The results of this study highlight the importance of red-clay sediment in shaping the chemical composition of the ocean, and suggest an important role for hydrothermally influenced sediment in modulating the contributions of hydrothermal vents to ocean biogeochemistry.
  • seminar
    Date:
    31 March
    2024
    Sunday
    Hours:
    11:00

    Large scale circulation adjustments to aerosol-cloud interactions and its radiative effect

    Location: Sussman Family Building for Environmental Sciences
    participants: Guy Dagan
    Hebrew University of Jerusalem

    Abstract

    The impact of anthropogenic aerosols on clouds is a leading source of uncertainty in estimating the effect of human activity on the climate system. The challenge lies in the scale difference between clouds (~1-10 km) and general circulation and climate (~1000 km). To address this, we utilize three different novel sets of simulations that allow to resolve convection while also including a epresentation of large-scale processes. Our findings demonstrate that aerosol-cloud interaction intensifies tropical overturning circulation. Employing a weak temperature gradient approximation, we attribute variations in circulation to clear-sky humidity changes driven by warm rain suppression by aerosols. In two sets of simulations accounting for sub-tropical-tropical coupling, we show that aerosol-driven sub-tropical rain suppression leads to increased advection of cold and moist air from the sub-tropics to the tropics, thus enhancing tropical cloudiness. The increased tropical cloudiness has a strong cooling effect by reflecting more of the incoming solar radiation. The classical “aerosol-cloud lifetime effect” is shown here to have a strong remote effect (sub-tropical aerosols increase cloudiness in the tropics), thus widening the concept of cloud adjustments to aerosol perturbation with important implications for marine cloud brightening.
  • seminar
    Date:
    27 March
    2024
    Wednesday
    Hours:
    11:00
    -
    12:00

    Exploring Inorganic and Organic Biomass for generation of Fuels and Chemical Commodities

    Location: Perlman Chemical Sciences Building
    participants: Dr. José Geraldo Nery
    São Paulo State University - UNESP

    Abstract

    Biomass is characterized as "material of biological origin, excluding material embedded in geological formations or fossilized." It serves as a valuable resource for energy production and as a foundational material for the synthesis of various commodity and specialty materials. The composition of biomass is notably more diverse and intricate than that of crude oil, resulting in significant distinctions between a conventional petroleum refinery and a biomass refinery, often referred to as a biorefinery. Unlike crude oil, which is typically abundant in gaseous, liquid, and solid hydrocarbons featuring a high carbon-to-oxygen (C/O) ratio, biomass primarily consists of complex biomacromolecules with a considerably lower C/O ratio. The conversion of biomass into commodity chemicals presents a promising approach to diminish society's reliance on fossil fuel resources—the predominant challenge of the 21st century. This challenge necessitates the development of tools and technologies to facilitate the transition from a predominantly petroleum-based to an alternative bio-based chemical industry. The objective of this seminar is to showcase the recent advancements we have made in enhancing bio-based platform molecules for the production of commodity or specialty chemicals. We achieve this through the utilization of C2 to C6 bio-based platforms, exemplified by polyols (e.g., glycerol), furanoids (e.g., furfural), and carboxylic acids (e.g., levulinic acid).
  • seminar
    Date:
    25 March
    2024
    Monday
    Hours:
    16:00

    EPS AI discussion seminar - Neural General Circulation Models for weather and climate predictions

    participants: Janni Yuval
  • seminar
    Date:
    21 March
    2024
    Thursday
    Hours:
    14:00
    -
    15:00

    Chemistry and the Information beyond the Genome Sequence

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Andreas Marx
    Department of Chemistry and Konstanz Research School Chemical Biology, University of Konstanz Germany
  • seminar
    Date:
    20 March
    2024
    Wednesday
    Hours:
    11:00
    -
    12:00

    Employing the Hegelian Aufhebung Principle for Predicting New Catalytic Pathways

    Location: Perlman Chemical Sciences Building
    participants: Prof. Anatoly Frenkel
    Stony Brook University and Brookhaven National Laboratory

    Abstract

    Understanding mechanisms of work for a wide range of applied nanomaterials begins with identifying “active units” in operating conditions, zooming in on the “active sites” and ends with a model explaining their role for functioning of the material or device. There are two main hurdles that we are particularly interested in overcoming: 1) heterogeneity of active species and sites and 2) their dynamics that can be directly responsible for their mechanisms. One possible method, ideally suitable for capitalizing on these challenges for rational design of new catalytic pathways, is the Aufhebung (sublation) principle from the Hegelian dialectics. It describes the process of advancing knowledge by integrating the two opposites: the thesis and antithesis. We adopt this principle to leverage the inherent heterogeneity of catalytic active species and active sites in metal catalysts for understanding and predicting new catalytic pathways for CO and CO2 conversion reactions. Starting with atomically dispersed (the thesis) Pt on ceria support, we use multimodal, operando characterization for monitoring formation of nanoparticles (the antithesis), identify reaction active species and unique active sites at the metal-support interface. With this knowledge, we design the “single-atoms” catalysts (synthesis) possessing the same active sites and enhanced stability in reaction conditions. I will highlight the role of oxygen vacancies for enhancing the dynamicity of Pt atoms and opening new reaction pathways for direct and reverse water gas shift reactions and CO oxidation reaction.
  • seminar
    Date:
    19 March
    2024
    Tuesday
    Hours:
    14:00
    -
    15:00

    New approaches to glycan synthesis and glycan-based biosensing

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Mattan Hurevich
    Institute of Chemistry Hebrew University
  • seminar
    Date:
    11 March
    2024
    Monday
    Hours:
    15:00

    EPS AI discussion seminar - Applications of Self Organizing Maps for the classification of cyclones in the Mediterranean

    participants: Yonatan Givon
    Earth and Planetary Sciences Weizmann Institute of Science

    Abstract

    The use of SOM in atmospheric science has grown popular over the recent years. The SOM's strength lies in its ability to project the continuum of a given dynamical system to an easily understood spectrum of dominant states. The SOM relies on a neural network, where each grid-point in each node (cluster) is assigned with a specific weight for a given input parameter. The SOM then operates competitively, shifting individual members between the nodes to minimize internal node variability while maximizing the distances between the nodes. Here, two novel SOM applications are demonstrated, recently used to classify Mediterranean cyclones from an upper-level PV perspective. Each approach yields the potential to enhance the understanding of different aspects of Mediterranean cyclone's predictability and is readily applicable to other regions of interest.
  • seminar
    Date:
    10 March
    2024
    Sunday
    Hours:
    16:00
    -
    17:00

    Chemical and Biological Physics Guest seminar

    Location: Perlman Chemical Sciences Building
    participants: Prof. Oleg Vasyutinskii
    Peter the Great St. Petersburg Polytechnic University

    Abstract

    The lecture presents recent results obtained in the laboratory of Prof. Oleg Vasyutinskii in the Ioffe Institute, St.Petersburg, Russia along several directions of application of modern laser techniques for investigation of the dynamics of molecules relevant for biology and medicine. The particular directions under discussion will be as follows. • Investigation of energy transfer in the excited states of molecular probes in solutions by means of polarized fluorescence spectroscopy. • Pump-and-probe polarization modulation spectroscopy for investigation of sub-picosecond dynamics in excited biomolecules. • Dynamics of singlet oxygen generation and degradation in solutions and on organic surfaces.
  • seminar
    Date:
    5 March
    2024
    Tuesday
    Hours:
    14:00
    -
    15:00

    Machine learning for protein functional site annotation and peptide binder design

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Jerome Tubiana
    Blavatnik School of Computer Science, Tel Aviv University
  • seminar
    Date:
    26 February
    2024
    Monday
    Hours:
    15:00

    EPS AI discussion seminar - Towards a Unified Conversational Model for Remote Sensing Imagery

    Location: Sussman Family Building for Environmental Sciences
    participants: Salman Khan (MBZUAI)
  • seminar
    Date:
    25 February
    2024
    Sunday
    Hours:
    11:00

    EPS Departmental Seminar; Challenges and opportunities in global storm resolving climate models

    Location: Sussman Family Building for Environmental Sciences
    participants: Ilai Guendelman
    Princeton University
  • seminar
    Date:
    20 February
    2024
    Tuesday
    Hours:
    14:00
    -
    15:00

    Principles of protein-protein interactions in 11 years of lab-evolution

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Emmanuel Levy
    Dept. of Chemical and Structural Biology Weizmann Institute
  • seminar
    Date:
    12 February
    2024
    Monday
    Hours:
    15:00

    EPS AI discussion seminar- Machine Learning for Flood Forecasting: Research to Ope

    Location: Sussman Family Building for Environmental Sciences
    participants: Grey Nearing
  • seminar
    Date:
    11 February
    2024
    Sunday
    Hours:
    11:00

    The geologic history of marine dissolved organic carbon from iron (oxyhydr)oxides

    Location: Sussman Family Building for Environmental Sciences
    participants: Nir Galili
  • seminar
    Date:
    7 February
    2024
    Wednesday
    Hours:
    15:00
    -
    16:00

    Chemical and Biological Physics Guest seminar

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Ron Tenne
    University of Konstanz

    Abstract

    While colloidal quantum dots (CQDs) are already an important building block in electro-optical devices, in the realm of quantum science and technology, they are often considered inferior with respect to emitters such as solid-state defects and epitaxial quantum dots. Despite their single-photon emission [1], demonstrations of quantum coherence and control are largely still lacking. The main obstacle towards these is spectral diffusion – stochastic fluctuations in the energy of photons emitted from an individual CQD even at cryogenic temperatures. In this talk, I will present our recent work providing, for the first time, direct and definitive proof that these fluctuations arise from stochastic electric fields in the particle’s nano environment [2]. However, the high sensitivity of CQDs to electric fields, through the quantum-confined Stark effect, can also be perceived as a feature, rather than a bug. I will present future concepts for coherent control of a single photon’s temporal wavefunction through an electric bias. Relying on tools from the terahertz and femtosecond-laser toolboxes [3,4], spectroscopy and control at fast-to-ultrafast (millisecond-to-femtosecond) timescales, will play a detrimental role in fulfilling the unique potential that CQDs hold in the field of quantum optics,. [1] R. Tenne, U. Rossman, B. Rephael, Y. Israel, A. Krupinski-Ptaszek, R. Lapkiewicz, Y. Silberberg, and D. Oron, Super-Resolution Enhancement by Quantum Image Scanning Microscopy, Nature Photonics 13, 116 (2019). [2] F. Conradt, V. Bezold, V. Wiechert, S. Huber, S. Mecking, A. Leitenstorfer, and R. Tenne, Electric-Field Fluctuations as the Cause of Spectral Instabilities in Colloidal Quantum Dots, Nano Lett. 23, 9753 (2023). [3] P. Henzler et al., Femtosecond Transfer and Manipulation of Persistent Hot-Trion Coherence in a Single CdSe/ZnSe Quantum Dot, Physical Review Letters 126, 067402 (2021). [4] P. Fischer, G. Fitzky, D. Bossini, A. Leitenstorfer, and R. Tenne, Quantitative Analysis of Free-Electron Dynamics in InSb by Terahertz Shockwave Spectroscopy, Physical Review B 106, 205201 (2022).
  • seminar
    Date:
    30 January
    2024
    Tuesday
    Hours:
    14:30
    -
    15:30

    Modeling protein complexes in the age of deep learning

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Dina Schneidman
    School of Computer Science and Engineering The Hebrew University
  • seminar
    Date:
    17 January
    2024
    Wednesday
    Hours:
    11:00
    -
    12:00

    Design principles for new anode compositions: Exploring Earth-Abundant Transition Metal Oxides for Li-ion Batteries

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Arava Zohar
    Materials Department and Materials Research Laboratory, University of California

    Abstract

    Innovative battery electrode materials are essential for unlocking the full potential of Li-ion batteries in various aspects of modern life. A primary focus is identifying novel materials with greater elemental diversity that offer improved stability, rapid charge capabilities, and high performance. Promising candidates, like early transition metal oxides, are earth-abundant and present opportunities for next-generation anode materials due to their redox voltage and more than a single stable oxidation state. Exploring fundamental design principles for improved de/lithiation mechanisms will influence battery functionality and advance energy storage capabilities. The first part will delve into the impact of the insulator-metal transition during lithiation, focusing on two distinctive Wadsley-Roth (WR) structures. Our findings underscore the critical role of disorder within these structures in determining kinetics and retained capacities for these anodes. The second part proposes a novel strategy leveraging the induction effect to reduce the operation voltage of Mo-oxide-based anodes. This reduction opens the door for Mo-based oxide anodes as an alternative to graphene. Understanding these key aspects can guide the search for alternatives to existing anodes for advancing the development of Li-ion batteries with enhanced performance in the energy storage field.
  • seminar
    Date:
    14 January
    2024
    Sunday
    Hours:
    15:00
    -
    16:00

    “Enhancing Specificity with ultrafast functional MRI”

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Noam Shemesh, Ph.D
    Director, Champalimaud preclinical MRI Centre (CMC) Champalimaud Centre for the Unknown Lisbon, Portugal
  • seminar
    Date:
    7 January
    2024
    Sunday
    Hours:
    15:00

    Chemical and Biological Physics Guest seminar

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr Noam Shemesh
    Champalimaud Research Champalimaud Foundation, Lisbon

    Abstract

    In living systems, the tissue micro-architecture consists of myriad cellular and subcellular elements whose density, size/shape distributions, composition, and permeability, endow the tissue with its biological functionality. Dynamic transport mechanisms are further critical for maintaining homeostasis and supporting diverse physiological functions such as action potentials and biochemical signaling. Still, how these biophysical properties change over time and how they couple to activity, remains largely unknown. This is mainly due to the difficulty in mapping these properties in-vivo, longitudinally, and with sufficient specificity. Magnetic Resonance Imaging (MRI), with its capacity for longitudinal studies and wealth of microscopic information leading to multiple contrast mechanisms, provides an outstanding opportunity to decipher these phenomena. In this talk I will discuss our recent advances in diffusion and functional MRI, including novel pulse sequences and biophysical modeling of diffusion processes in the microscopic tissue milieu, which provide, for the first time, the sought-after specificity for density, size, and permeability of particular (sub)cellular elements in tissues. I will show new experiments in rodents proving unique power-laws predicted from biophysical models, revealing axon density and size, as well as cell body density and size, along with validations against ground-truth histology and applications in animal models of disease. Evidence for exchange between the intracellular and extracellular space will also be given, along with a first approach for quantitatively mapping permeability in tissue. I will also introduce correlation tensor MRI (CTI), a new approach for source-separation in diffusional kurtosis, that offers surrogate markers of neurite beading effects, thereby further enhancing specificity, especially in stroke. Finally, I will touch upon dynamic modulations of neural tissue microstructure upon neural activity, and provide evidence for the existence of a neuro-morphological coupling in diffusion-weighted functional MRI signals. Future vistas and potential applications will be discussed.
  • seminar
    Date:
    3 January
    2024
    Wednesday
    Hours:
    15:00
    -
    16:00

    Chemical and Biological Physics Guest seminar

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr Ran Finkelstein
    Caltech

    Abstract

    Large arrays of trapped neutral atoms have emerged over the past few years as a promising platform for quantum information processing, combining inherent scalability with high-fidelity control and site-resolved readout. In this talk, I will discuss ongoing work with arrays of Alkaline-earth atoms. These divalent atoms offer unique properties stemming largely from their long-lived metastable states, which form the basis of the optical atomic clock. I will describe the design of a universal quantum processor based on clock qubits and its application in quantum metrology, and I will address the challenge of generating and benchmarking highly entangled states in an analog quantum simulator. First, we realize scalable local control of individual clock qubits, which we utilize to extend the Ramsey interrogation time beyond the coherence time of a single atom [1]. To realize a universal quantum processor, we demonstrate record high-fidelity two-qubit entangling gates mediated by Rydberg interactions, which we combine with dynamical reconfiguration to entangle clock probes in GHZ states and perform Ancilla-based detection [2]. We then use the narrow clock transition to measure and remove thermal excitations of atoms in tweezers (a technique known as erasure conversion) and generate hyperentangled states of motion and spin [3]. In the second part of the talk, I will describe a different approach for generating large scale entangled states in an analog quantum simulator configuration [4], including error mitigation [5] and benchmarking of a 60-atom simulator [6]. Together, these show the great promise and the large variety of experiments accessed with this emerging platform. [1] A. Shaw*, R. Finkelstein*, R. Tsai, P. Scholl, T. Yoon, J. Choi, M. Endres, Multi-ensemble metrology by programming local rotations with atom movements, arxiv:2303.16885, Nature Physics in press (2023). [2] R. Finkelstein, R. Tsai, A. Shaw, X. Sun, M. Endres, A universal quantum processor for entanglement enhanced optical tweezer clocks, in preparation. [3] P. Scholl*, A. Shaw*, R. Finkelstein*, R. Tsai, J. Choi, M. Endres, Erasure cooling, control, and hyper-entanglement of motion in optical tweezers, arXiv:2311.15580 (2023). [4] J. Choi, A. Shaw, I. Madjarov, X. Xie, R. Finkelstein, J. Covey, J. Cotler, D. Mark, H.Y. Huang, A. Kale, H. Pichler, F. Brandão, S. Choi, and M. Endres, Preparing random states and benchmarking with many-body quantum chaos, Nature 617 (2023) [5] P. Scholl, A. Shaw, R. Tsai, R. Finkelstein, J. Choi, M. Endres, Erasure conversion in a high-fidelity Rydberg quantum simulator, Nature 622 (2023). [6] A. Shaw, Z. Chen, J. Choi, D.K. Mark, P. Scholl, R. Finkelstein, A. Elben, S. Choi, M. Endres, Benchmarking highly entangled states on a 60-atom analog quantum simulator, arXiv:2308.07914 (2023).
  • seminar
    Date:
    2 January
    2024
    Tuesday
    Hours:
    11:15
    -
    12:15

    Enhanced Growth in Atomic Layer Deposition of Transition Metals: The Role of Surface Diffusion and Nucleation Sites

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Amnon Rothman
    Chemical Engineering, Stanford University

    Abstract

    Noble metal thin films have attracted significant interest owing to their distinctive properties and structures, which make them ideal for applications in microelectronics, catalysis, energy, and photovoltaics. While several parameters influence the properties of these metals for such applications, the deposition process remains a critical factor. Atomic Layer Deposition (ALD) stands out as a prevalent deposition technique due to its surface-sensitive nature. The ALD process is characterized by its self-limiting surface reactions, promoting a layer-by-layer growth mechanism and allowing for precise control over film thickness and conformality. However, challenges arise in achieving continuous, pinhole-free noble metal ALD layers on oxide surfaces, often resulting in low film quality. These challenges can be traced back to the lack of adequate nucleation sites and the poor wettability of the low-surface energy substrates. The research studied the impact of substrate surface functionalization using organometallic molecules, such as trimethylaluminum (TMA) and diethylzinc (DEZ), on the nucleation and growth of Ru layers. The results reveal an enhancement in both nucleation density and the average diameter of the Ru nanoparticles deposited, and these improvements were attributed to an increase in both nucleation sites and elevated surface diffusivity. The latter effect is speculated to result from a reduction in the substrate's surface free energy. The study also examines the influence of substrate surface characteristics, including surface termination and crystallinity, on the nucleation and growth of Ru metal via ALD. The morphologies of the resulting Ru thin films are studied using scanning electron microscopy (SEM), atomic force microscopy (AFM), and grazing incidence small angle x-ray scattering (GISAXS). These analytical results are integrated with an experimental model to elucidate the differences in growth mechanisms observed across substrates. The findings underscore the importance of substrate choice in the ALD process and broaden our understanding of Ru metal growth. This research serves as an important step in optimizing the ALD process for various applications by tailoring substrate selection.
  • seminar
    Date:
    26 December
    2023
    Tuesday
    Hours:
    14:00
    -
    15:00

    The structure of protein complexes underlies co-translational assembly

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Saurav Mallik
    Prof. Emmanuel Levy's lab Dept. of Chemical & Structural Biology WIS
  • seminar
    Date:
    26 November
    2023
    Sunday
    Hours:
    11:00

    Cancelled

    Location: Sussman Family Building for Environmental Sciences
    participants: Jianmin Chen
  • seminar
    Date:
    19 November
    2023
    Sunday
    Hours:
    11:00
    -
    12:00

    cancelled

    Location: Sussman Family Building for Environmental Sciences
    participants: Erwin Zehe
  • seminar
    Date:
    5 November
    2023
    Sunday
    Hours:
    11:00

    TBA

    Location: Sussman Family Building for Environmental Sciences
    participants: Paul O'Gorman
  • seminar
    Date:
    17 October
    2023
    Tuesday
    Hours:
    11:00

    Chemical and Biological Physics Guest seminar

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Timur O. Shegai
    Chalmers University of Technology, Sweden

    Abstract

    Strong light-matter interactions are at the core of many electromagnetic phenomena. In this talk, I will give an overview of several nanophotonic systems which support polaritons – hybrid light-matter states, as well as try to demonstrate their potential usefulness in applications. I will start with transition metal dichalcogenides (TMDs) and specifically discuss one-dimensional edges in these two-dimensional materials (1-2). I will show that TMDs can be etched along certain crystallographic axes, such that the obtained edges are nearly atomically sharp and exclusively zigzag-terminated, while still supporting polaritonic regime. Furthermore, I will show that Fabry-Pérot resonators, one of the most important workhorses of nanophotonics, can spontaneously form in an aqueous solution of gold nanoflakes (3-4). This effect is possible due to the balance between attractive Casimir-Lifshitz forces and repulsive electrostatic forces acting between the flakes. There is a hope that this technology is going to be useful for future developments in self-assembly, nanomachinery, polaritonic devices, and perhaps other disciplines. References: 1) Nat. Commun., 11, 4604, (2020) 2) Laser & Photonics Rev., 17, 2200057, (2023) 3) Nature 597, 214-219, (2021) 4) Nat. Phys. 19, 271-278, (2023)
  • seminar
    Date:
    15 October
    2023
    Sunday
    Hours:
    11:00

    TBA

    Location: Sussman Family Building for Environmental Sciences
    participants: Dr. Katinka Bellomo
  • seminar
    Date:
    19 September
    2023
    Tuesday
    Hours:
    14:00
    -
    15:00

    How did the protoribosomes form the first peptide bonds – chemical and structural studies

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Tanaya Bose
    Yonath Lab, Dept. of Chemical and Structural Biology, Weizmann Institute
  • seminar
    Date:
    10 September
    2023
    Sunday
    Hours:
    11:00

    Quantifying the Global and Regional Contribution of Terrestrial Carbon Pools to the Land Sink

    Location: Sussman Family Building for Environmental Sciences
    participants: Yinon Bar-On
    California Institute of Technology

    Abstract

    Terrestrial sequestration of carbon has mitigated ≈30% of anthropogenic carbon emissions. However its distribution across different pools—live or dead biomass, and soil and sedimentary organic carbon— which has important implications for future climate change mitigation, remains uncertain. By analyzing global observational datasets of changes in terrestrial carbon pools, we are able to partition carbon that has been sequestered on land between 1992-2019 into live biomass and non-living organic carbon pools. We compare our observation-based estimates against predictions of global vegetation models and identify key processes that are not included in most models that can help align the models with observations. We find that most terrestrial carbon gains are sequestered as non-living organic matter, and thus more persistent than previously appreciated, with a substantial fraction linked to human activities such as river damming, wood harvest, and garbage disposal in landfills.
  • seminar
    Date:
    7 September
    2023
    Thursday
    Hours:
    11:00
    -
    12:00

    “Lessons From Nature: How to Get the Best out of Materials”

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Mato Knez
    Ikerbasque, Basque Foundation for Science

    Abstract

    Processes in nature are often long-lasting, but they have a common goal, i.e., to advance structures or constructions. Especially for the composition of materials, it is worth having a closer look and mimic the natural concept for improving the properties of the known materials and in this way opening doors for new application fields. Among the concepts in nature there is the hybridization of materials, i.e., the blend of organic and inorganic materials with the goal of outperforming both constituting components. The engineering of such hybrid materials can be done in synthetic wet-chemical or in physical ways and often the results, i.e., the properties of the materials, will differ, even if their composition is identical. This may result from different qualities of interactions between the constituting materials. The quality of interactions can be controlled by the choice of the chemicals and/or the choice of hybridization process. Two recently developed approaches for hybridization base on vapor phase chemistry and are derived from atomic layer deposition (ALD) and result in hybrid thin film growth (molecular layer deposition, MLD) or subsurface hybridization of polymers (vapor phase infiltration, VPI). Both approaches open a plethora of new options for materials design for future applications. In this talk, some approaches of our group will be discussed that show great promise of vapor phase-grown hybrid films for innovation in technological fields beyond the microelectronics industry. Examples, where mechanical and electronic properties of polymeric materials have been significantly improved through nanoscale coatings and infiltration, will be shown. Furthermore, new concepts towards self-healing of semiconducting thin films, enabled by hybrid materials, will be shown. In most cases, the chemical or physical properties of the initial substrate are altered, typically improved, and new functionalities are added.
  • seminar
    Date:
    4 September
    2023
    Monday
    Hours:
    10:00
    -
    11:00

    High-speed atomic force microscopy captures a rare oligomeric state of an ion channel

    Location: Nella and Leon Benoziyo Building for Biological Sciences
    participants: Dr. Shifra Lansky
    Cornell University, New York

    Abstract

    Transient receptor potential (TRP) channels are a large, eukaryotic ion-channel superfamily that control diverse physiological functions. To date, more than 210 structures from over 20 TRP-channels have been determined, all are tetramers. Using high-speed atomic force microscopy (HS-AFM), a pioneering technique capable of “filming” single-molecule proteins, we discovered a rare and transient pentameric state for TRPV3, and determined the pentamer structure using single-particle cryo-EM. Our results suggest that the pentamer relates to the pore-dilated state, a structurally-elusive state characterized by increased conductance and permeability to small molecules. These findings lay the foundation for many new directions in ion-channel research, and demonstrate the strength of HS-AFM in discovering transient and rare states of proteins.
  • seminar
    Date:
    30 August
    2023
    Wednesday
    Hours:
    11:00
    -
    12:00

    Ultra-Repellent Aerophilic Surfaces Underwater”

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Alexander B. Tesler
    Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany

    Abstract

    Wetting describes the ability of liquids to maintain contact with a solid surface, a phenomenon that is ubiquitous in nature.1 However, in engineering and medical applications, contact of solid surfaces with aqueous media leads to undesirable phenomena such as corrosion, chemo- and biofouling, which have extremely negative economic, health, and environmental impacts. Therefore, control of wetting on solid surfaces is key to mitigating its detrimental effects. The latter can be achieved by minimizing the contact of the solid substrate with aqueous media, so-called superhydrophobic surfaces (SHS). Although SHS have been studied for decades to overcome wetting challenges,2 they are still rarely used in engineering applications. When immersed underwater, a special type of SHS can trap air on its surface, so-called air plastron, also known as an aerophilic surface. To date, plastrons have been reported to be impractical for underwater engineering due to their short lifetime. Here, I will describe aerophilic surfaces made of titanium alloy (Ti) with an extended lifetime of plastron conserved for months underwater.3 The extended methodology was developed to unambiguously describe the wetting regime on such aerophilic surfaces since conventional goniometric measurements are simply impractical. My aerophilic surfaces drastically reduce the adhesion of blood, and when immersed in aqueous media, prevent the adhesion of bacteria, and marine organisms such as barnacles, and mussels. Applying thermodynamic stability theories, we describe a generic strategy to achieve long-term stability of plastron on aerophilic surfaces for demanding and hitherto unattainable applications. (1) Quéré, D. Wetting and Roughness. Annual Review of Materials Research 2008, 38 (1), 71-99. (2) Cassie, A. B. D.; Baxter, S. Wettability of porous surfaces. Transactions of the Faraday Society 1944, 40, 546-551. (3) Tesler, A.B.;* Kolle, S.; Prado, L.H.; Thievessen, I.; Böhringer, D.; Backholm, M.; Karunakaran, B.; Nurmi, H.A.; Latikka, M.; Fischer, L.; Stafslien, S.; Cenev, Z.M.; Timonen, J.V.I.; Bruns, M.; Mazare, A.; Lohbauer, U.; Virtanen, S.; Fabry, B.; Schmuki, P.; Ras, R.H.A.; Aizenberg, J.; Goldmann, W.H. Long-Lasting Aerophilic Metallic Surfaces Underwater. Nature Materials 2023, accepted. *Corresponding author
  • seminar
    Date:
    15 August
    2023
    Tuesday
    Hours:
    14:00
    -
    15:00

    Intra-host evolution of HIV env after broadly-neutralizing antibody infusion

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Frida Belinky
    Virus Persistence and Dynamics Section Immunology Laboratory Vaccine Research Center National Institute of Allergy and Infectious Diseases National Institutes of Health
  • seminar
    Date:
    23 July
    2023
    Sunday
    Hours:
    11:00

    Using weather regimes in the context of sub-seasonal forecasting for the Extratropics: the role of synoptic-scale processes in regime predictability, modulation by the MJO and stratosphere, and link to surface weather

    participants: Christian Grams
    Karlsruhe Institute of Technology

    Abstract

    Sub-seasonal forecasting aims to predict the mean weather conditions on weekly time-scales 2-6 weeks ahead. In the midlatitudes, lLarge-scale, quasi-stationary, recurrent, and persistent flow patterns, so-called weather regimes, explain sub-seasonal weather variability in the European region. However, forecast skill and predictability for regimes are mostly very poor on sub-seasonal forecast horizons. In this presentation we shed light on how synoptic-scale processes, affect the predictability and forecast skill of North Atlantic-European weather regimes. We focus on the upper-tropospheric divergent outflow due to latent heat release in ascending air streams, so-called warm conveyor belts (WCBs). We find evidence that a misrepresentation of diabatic WCB outflow at onset of regimes characterised by blocking anticyclones is likely the cause for vanishing regime skill on sub-seasonal time scales. At the same time results suggest that a correct representation of WCB activity might be a window of forecast opportunity for regimes. We further discuss how the occurrence of regimes is modulated by the state of the winter stratosphere and the MJO, which provide another window of forecast opportunity for weather regimes on sub-seasonal time scales. Interestingly, we find again that WCB activity related to synoptic-scale weather systems modulate the MJO teleconnections towards North America and Europe. We conclude that knowledge about physical and dynamical processes on synoptic scales is key for exploiting the potential windows of forecast opportunity for weather regimes on sub-seasonal time scales.
  • seminar
    Date:
    20 July
    2023
    Thursday
    Hours:
    11:00
    -
    12:00

    Solvent-Enhanced Symmetry-breaking and Singlet-Fission in the Covalently-Bound Tetracene Dimer and Calculation of Electronic States in TIPS-Pentacene

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Hans Lischka
    Department of Chemistry & Biochemistry Texas Tech University

    Abstract

    In recent years, covalently bound dimers of chromophores have attracted significant interest as singlet fission (SF) material because of better control of coupling of different electronic states to the gateway 1(TT) by means of intramolecular vibrational modes.1 It has been shown that charge transfer (CT) plays a crucial role in mediating the S1-1(TT) interaction and their influence can be conveniently tuned by solvent polarity. Motivated by the experimental and theoretical work of Alvertis et al.,1 we have investigated the electronic states relevant to the SF for the covalently bound tetracene dimer with the goal to provide a broader picture of the occurring photodynamical processes.2 For that purpose, the second-order algebraic diagrammatic construction (ADC(2)) method in combination with the conductor-like screening model (COSMO) has been used. Vertical excitations and potential energy curves for excitonic and CT states along low-frequency symmetric and antisymmetric normal modes have been computed. These results have been combined with those obtained by density functional theory/multireference configuration interaction (DFT/MRCI) calculations for the 1(TT) state since its doubly-excited wavefunction is not accessible to the ADC(2) method. In the second part of the talk, DFT/MRCI calculations on dimer and trimer TIPS-Pn will be presented with the goal of a first theoretical understanding of the photodynamics of the 1(TT) state monitored by time-resolved mid-IR absorption spectroscopy.3
  • seminar
    Date:
    11 July
    2023
    Tuesday
    Hours:
    11:00
    -
    12:00

    Unconventional semiconductors and device architectures enabled by molecular design, doping and film morphology engineering

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Antonio Facchetti
    Department of Chemistry and the Materials Research Center, Northwestern University

    Abstract

    Organic/printed electronics is a technology enabling the fabrication of mechanically flexible/stretchable electronic circuits and devices using low-temperature, possibly by additive, solution processing methodologies. In this presentation we report the development of novel materials, as well as thin-film processing and morphology engineering, for flexible and stretchable organic and inorganic thin film transistors, electrolyte gated transistors and circuits. On material development, we present that “soft” small-molecules and polymers can be synthesized by co-polymerizing naphthalenediimide (NDI) or diketopyrrolopyrrole (DPP) units with proper co-monomer building blocks or properly designed additives. Furthermore, we also report the fabrication of stretchable inorganic metal oxide fiber network by spry coating metal salts+thermally labile polymer formulations. New transistor architectures using semiconductor film porosity as the key element for enhancing mechanical flexibility and tune charge transport are also demonstrated. These films, combined with elastomeric pre-stretching, enables unprecedentedly stable current-output characteristic upon mechanical deformation, which are used for sensing analytes, strain, light, temperature and physiological parameters. Finally, we report our recent work on molecular n-doping of organic semiconductors using a novel strategy involving catalysts.
  • seminar
    Date:
    9 July
    2023
    Sunday
    Hours:
    11:00

    A Neolithic Tsunami Event along the Eastern Mediterranean Littoral: A Transdisciplinary Research at the Coast of Dor Israel

    Location: Sussman Family Building for Environmental Sciences
    participants: Gilad Steinberg
    University of California San Diego

    Abstract

    Tsunami events in antiquity had a profound influence on coastal societies. Six thousand years of historical records and geological data show that tsunamis are a common phenomenon affecting the eastern Mediterranean coastline. However, the possible impact of older tsunamis on prehistoric societies has not been investigated. Here we report, based on optically stimulated luminescence chronology, the earliest documented Holocene tsunami event, between 9.91 to 9.29 ka (kilo-annum), from the eastern Mediterranean at Dor, Israel. Tsunami debris from the early Neolithic is composed of marine sand embedded within fresh-brackish wetland deposits. Global and local sea-level curves for the period, 9.91–9.29 ka, as well as surface elevation reconstructions, show that the tsunami had a run-up of at least ~16 m and traveled between 3.5 to 1.5 km inland from the palaeo-coastline. Submerged slump scars on the continental slope, 16 km west of Dor, point to the nearby “Dor complex” as a likely cause. The near absence of Pre-Pottery Neolithic A-B archaeological sites (11.70–9.80 cal. ka) suggests these sites were removed by the tsunami, whereas younger, late Pre-Pottery Neolithic B-C (9.25–8.35 cal. ka) and later Pottery-Neolithic sites (8.25–7.80 cal. ka) indicate resettlement following the event. The significant run-up of this event highlights the disruptive impact of tsunamis on past societies along the Levantine coast.
  • seminar
    Date:
    27 June
    2023
    Tuesday
    Hours:
    14:00
    -
    15:00

    Functional studies of lysine ac(et)ylation using genetically encoded post-translational modifications

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Eyal Arbely
    Department of Chemistry Ben Gurion University
  • seminar
    Date:
    22 June
    2023
    Thursday
    Hours:
    11:00
    -
    12:00

    Quo Vadis Small Molecule Drug Discovery?

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Ingo Hartung
    Head of Medicinal Chemistry & Drug Design Global Research & Development Merck Healthcare KGaA
  • seminar
    Date:
    18 June
    2023
    Sunday
    Hours:
    11:00
    -
    12:00

    TBA

    Location: Sussman Family Building for Environmental Sciences
    participants: Tal Benaltabet
    The Hebrew University of Jerusalem
  • seminar
    Date:
    15 June
    2023
    Thursday
    Hours:
    11:00

    Chemical and Biological Physics Guest Seminar

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr Gideon Segev
    School of Electrical Engineering, Tel Aviv University

    Abstract

    Even though highly selective ion pumps can be found in every living cell membrane, artificial, membrane-based ion selective separation is a longstanding unmet challenge in science and engineering. The development of a membrane-based ion separation technology can drive a dramatic progress in a wide range of applications such as: water treatment, bio-medical devices, extraction of precious metals from sea water, chemical sensors, solar fuels and more. In this seminar I will discuss our theoretical and experimental demonstration of ion pumps based on an electronic flashing ratchet mechanism. Electronic flashing ratchets are devices that utilize modulation in a spatially varying electric field to drive steady state current. Like peristaltic pumps, where the pump mechanism is not in direct contact with the pumped fluid, electronic ratchets induce net current with no direct charge transport between the power source and the pumped charge carriers. Thus, electronic ratchets can be used to pump ions in steady state with no electrochemical reactions between the power source and the pumped ions resulting in an “all electric” ion pump. Ratchet-based ion pumps (RBIPs) were fabricated by coating the two surfaces of nano-porous alumina wafers with gold forming nano-porous capacitor-like devices. The electric field within the nano-pores is modulated by oscillating the capacitors voltage. Thus, when immersed in solution, ions within the pores experience a modulating electric field resulting in ratchet-based ion pumping. The RBIPs performance was studied for various input signals, geometries, and solutions. RBIPs were shown to drive ionic current densities of several μA/cm2 even when opposed by an electrostatic force. A significant ratchet action was observed with input signal amplitudes as low as 0.1V thus demonstrating that RBIPs can drive an ionic current with no associated redox reactions. Simulations show that frequency dependent flux inversions in ratchet systems may pave the way towards ion selective RBIPs.
  • seminar
    Date:
    13 June
    2023
    Tuesday
    Hours:
    14:00
    -
    15:00

    Translational Chemical Biology

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Xiaoguang Lei
    Peking University
  • seminar
    Date:
    13 June
    2023
    Tuesday
    Hours:
    10:00
    -
    11:00

    Joint Chemical and Biological Physics and Molecular Chemistry and Materials Science Guest Seminar

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr Yair Litman
    University of Cambridge

    Abstract

    ydrogen transfer reactions play a prominent role in nature and many technological applications. Despite appearing to be simple reactions, they constitute complex processes where nuclear quantum effects (NQE) such as zero-point energy and nuclear tunneling play a decisive role even at ambient temperature. In this talk, I will show how state-of-the-art methodologies based on the path integral formulation of quantum mechanics in combination with the density functional approximation provide the unique possibility to theoretically address these effects in complex environments. The first part of the talk will focus on the porphycene molecule in the gas phase and adsorbed on metallic surfaces. The porphycene molecule constitutes a paradigmatic example of a molecular switch and has recently received great attention due to its intriguing hydrogen dynamics. I will demonstrate how a correct treatment of NQE, as well as the inclusion of multidimensional anharmonic couplings, are essential to obtain qualitatively correct results regarding the non-trivial temperature dependence of the hydrogen transfer rates and vibrational spectra [1-3]. Finally, I shall also mention some of our recent results for hydrogen diffusion on metals for which non-adiabatic effects, in addition to NQE, play a significant role and can lead to “quantum localization” [4-6]. [1] Y. Litman, J. O. Richardson, T. Kumagai, and M. Rossi, J. Am. Chem. Soc. 141, 2526 (2019) [2] Y. Litman, J. Behler, and M. Rossi, Faraday Discuss. 221, 526 (2020) [3] Y. Litman and M. Rossi, Phys. Rev. Lett. 125, 216001 (2020) [4] Y. Litman, E. S. Pos. C. L. Box, R. Martinazzo, R. J. Maurer, and M. Rossi, J. Chem. Phys. 156, 194106 (2022) [5] Y. Litman, E. S. Pos. C. L. Box, R. Martinazzo, R. J. Maurer, and M. Rossi , J. Chem. Phys. 156, 194107 (2022) [6] O. Bridge, R. Martinazzo, S. C. Althorpe, Y. Litman, in preparation (2023)
  • seminar
    Date:
    11 June
    2023
    Sunday
    Hours:
    11:00
    -
    12:00

    TBA

    Location: Sussman Family Building for Environmental Sciences
    participants: Yael Leshno
  • seminar
    Date:
    11 June
    2023
    Sunday
    Hours:
    11:00
    -
    12:00

    Soft Matter and Biomaterials: Membrane remodelling in viral infection and migrasome formation

    Location: Perlman Chemical Sciences Building
    participants: Dr. Raya Sorkin
    School of Chemistry, TAU

    Abstract

    Fundamental understanding of physiological processes that occur at biological membranes, such as membrane fusion, necessitates addressing not only the biochemical aspects, but also biophysical aspects such as membrane mechanical properties and membrane curvature. In this talk, I will show how we combine membrane model systems, micropipette aspiration, optical tweezers and confocal fluorescence microscopy to study membrane shaping and membrane fusion processes. I will describe a new tool we developed, where we form membrane bilayers supported on polystyrene microspheres which can be trapped and manipulated using optical tweezers. Using this approach, we demonstrate successful measurements of the interaction forces between the Spike protein of SARS CoV-2 and its human receptor, ACE2. We further use bead-supported membranes interacted with aspirated vesicles to reveal the inhibitory effect of membrane tension on hemifusion. I will also describe a particular case of membrane shaping during the formation of the newly discovered organelle termed migrasome. We show that tetraspanin proteins involved in migrasome formation strongly partition into curved membrane tethers, and we reveal a novel, two-step process of migrasome biogenesis.
  • seminar
    Date:
    11 June
    2023
    Sunday
    Hours:
    10:00
    -
    11:00

    Probing nanocrystal photophysics with spectator excitons

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

    Abstract

    Femtosecond pump-probe experiments on nanocrystals are interpreted primarily in terms of state filling of the states involved in the intense band edge absorption features, and bi-exciton shifting which changes the resonance energy of the probe pulse due to presence of pump induced excitations. Results have been interpreted to show 1) that “hot” excitons will relax to the lowest available levels in the conduction band in ~1 ps, and 2) that said intense band edge exciton transition will be bleached linearly with excitons until the underlying states are completely filled. In the talk we describe a new approach involving “spectator excitons” to test these accepted views. It consists of comparing pump-probe experiments on pristine samples, with equivalent scans conducted on the same sample after it has been saturated in cold mono-excitons. We show how this method has uncovered previously unrecognized spin blockades in the relaxation of hot multi-exciton states in CdSe NCs, and simply detects stimulated emission signals even in presence of overlapping absorption. We report specific difficulties of applying this approach on perovskite crystals leading to controversial determination that in quantum confined CsPbBr3 bi-exciton interactions are positive (repulsive) and describe recent time resolved emission data which challenges this result.
  • seminar
    Date:
    7 June
    2023
    Wednesday
    Hours:
    10:30
    -
    11:30

    “How atoms jiggle and wiggle in energy materials”

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. David Egger
    Dept. Physics, Technical University of Munich

    Abstract

      Energy materials are crystalline, solid-state substances with technological applications in energy-conversion or storage devices that include solar cells and batteries. In our work, we are particularly interested in scenarios where these systems show unusual structural dynamical effects. These effects trigger many puzzling questions in regard to updated structure-property relations and improved theoretical understandings of these solids. In my talk, I will present our recent findings regarding theoretical treatments of structural dynamics in energy materials and how we may use them to improve our understanding of their finite-temperature properties. The results will focus on halide perovskite as well as nitride semiconductors and solid-state ion conductors, which we typically investigate in tandem with experiment.
  • seminar
    Date:
    6 June
    2023
    Tuesday
    Hours:
    14:00
    -
    15:00

    Microbiome Metabolites: Syntheses and Surprises

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Karl Gademann
    Department of Chemistry University of Zurich
  • seminar
    Date:
    6 June
    2023
    Tuesday
    Hours:
    10:00
    -
    11:00

    Chemical and Biological Physics Guest Seminar

    Location: Perlman Chemical Sciences Building
    participants: Prof Magali Lingenfelder
    Max Planck-EPFL Laboratory for Molecular Nanoscience and Technology, Ecole Polytechnique Federale de Lausanne (EPFL)

    Abstract

    Our society faces a critical challenge in shifting from a reliance on carbon-based energy to sustainable renewable sources. A key step towards achieving clean energy lies in developing efficient catalysts that can convert chemical energy into electricity or use electrons to generate chemical energy. In our research group, we tackle these challenges by creating customized materials that draw inspiration from nature (biomimicry) and combine principles from interfacial chemistry and surface physics. For this presentation, I focus on the process of photosynthesis as inspiration for the design, characterization, and dynamic nature of functional interfaces that drive energy conversion processes such as CO2 electroreduction and water splitting. I will also discuss the application of cutting-edge scanning probe microscopy, which allows us to visualize dynamic electrochemical processes at the nanoscale (operando imaging). Additionally, I will highlight our use of unconventional strategies that leverage chiral molecules and abundant two-dimensional materials to enhance electrocatalytic conversion processes. (References : Nanoletters, 2021, 21, 2059; Nature Comm., 2022, 13, 3356, IJC 62, 11, 2022).
  • seminar
    Date:
    4 June
    2023
    Sunday
    Hours:
    11:00
    -
    12:00

    Paleoclimate reconstruction using speleothems in dry and cold regions.

    Location: Sussman Family Building for Environmental Sciences
    participants: Anton Vaks
    GSI, Israel
  • seminar
    Date:
    30 May
    2023
    Tuesday
    Hours:
    14:00
    -
    15:00

    Electrosome assembly: a first look at the structural principles underlying ion channel biogenesis

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Daniel Minor
    Departments of Biochemistry & Biophysics University of California San Francisco
  • seminar
    Date:
    30 May
    2023
    Tuesday
    Hours:
    11:00
    -
    12:00

    Homogeneous (De)hydrogenative Catalysis for a Circular Economy

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Amit Kumar
    School of Chemistry, University of St. Andrews, St. Andrews, KY169ST, UK

    Abstract

    The development of sustainable methods for the closed-loop production and recycling of plastics is an important challenge of current times. Reactions based on catalytic (de)hydrogenation are atom-economic, and sustainable routes for organic transformations.1 Using the following examples, this lecture will discuss the application of homogeneous (de)hydrogenative catalysis for the synthesis and degradation of polymers to enable a circular economy: (a) synthesis of polyamides/nylons from the ruthenium catalysed dehydrogenative coupling of diamines and diols and its reverse reaction i.e. hydrogenative depolymerisation of nylons,2 (b) synthesis of polyureas from the ruthenium/manganese catalysed dehydrogenative coupling of diamines3,4 and methanol, and its reverse reaction, i.e. hydrogenative depolymerisation of polyureas (Figure 1B)5, (c) Synthesis of polyethyleneimines from manganese catalysed coupling of ethylene glycol and ethylenediamine or the self-coupling of ethanolamine,6 and (d) Synthesis of polyureas and polyurethanes from the dehydrogenative coupling of diformamides and diamines/diols and its reverse reaction i.e. hydrogenative depolymerisation of polyureas and polyurethanes to diformamides and diamines/diols.7 Some applications of some of the polymers made using dehydrogenative processes in the field of batteries will also be discussed.8
  • seminar
    Date:
    28 May
    2023
    Sunday
    Hours:
    11:00
    -
    12:00

    Studying the role of fluids in the mantle through natural samples and experiments

    Location: Sussman Family Building for Environmental Sciences
    participants: Ronit Kesel
    Institute of Earth Sciences, The Hebrew University of Jerusalem

    Abstract

    Mantle fluids are the primary carriers of key volatile elements that make the Earth’s long-term planetary habitability possible. The interaction of such volatile-rich fluids with the mantle rocks, especially the sub-cratonic lithospheric mantle leads to alteration of the mantle as well as its melting. High-density fluids encased inside diamonds are the best natural representation of mantle fluid compositions, suggesting their compositions are saline, silicic or carbonatitic. However, the origin and role in the mantle as well as their role in altering the mantle are still unclear. In my research, we approach these questions by experimentally simulating the interaction of volatile-rich fluids with mantle rocks at known pressure and temperature relevant to the mantle. Examining different mixtures of volatiles (H2O and CO2) and mantle rocks (peridotite and eclogite), we attempt to understand the origin of each type of fluid found in diamonds as well as study the effect of such interaction on the mantle chemistry and mineralogy. Compiling many experimental studies reveals that fluids ranging from silicic to low-Mg carbonatitic are formed in systems of eclogite+H2O+CO2, the more CO2 in the system, the more carbonatitic the fluid is. Fluids ranging from low-Mg carbonatitic to high-Mg carbonatitic in nature are the results of the formation of fluids in the peridotite-H2O-CO2 system. The more CO2 in the system, the more high-Mg carbonatitic the fluid composition is. These results suggest that the various fluids found in the mantle result from changes in the bulk composition of the mantle rocks. The mantle rocks are significantly affected during percolation of such fluids through them. For example, experimentally interacting silicic fluid with peridotite demonstrated the formation of various metasomatic peridotites as a function of pressure and temperature, composing of amphibole and mica. The mineral assemblages, chemistry, and P-T conditions in the experiments are similar to those found in metasomatic xenoliths from Kimberly, South Africa, and surrounding localities.
  • seminar
    Date:
    23 May
    2023
    Tuesday
    Hours:
    14:00
    -
    15:00

    Advances of Liquid Biopsy Diagnostics and Structural Models in the Development of Data-Driven AI in Future Hospitals

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Milana Frenkel-Morgenstern
    Azrieli Faculty of Medicine Bar-Ilan University
  • seminar
    Date:
    21 May
    2023
    Sunday
    Hours:
    11:00
    -
    12:00

    Determining past lake temperatures in saline lake systems using fluid inclusions: an example from the Dead Sea

    Location: Sussman Family Building for Environmental Sciences
    participants: Niels Brall
    The Hebrew University of Jerusalem

    Abstract

    In recent decades, various temperature proxies have been developed and further established in the scientific community, at both low and high accuracy, however, not every method can be applied without restriction to all minerals or rocks. Evaporitic rocks, for example, are abundant chemical sediments at the Earth's surface that are deposited from supersaturated brines in marine, terrestrial, and lacustrine environments. Halite is the most abundant rock-forming mineral in this group, which during crystal formation entraps tiny water droplets (fluid inclusions, FIs) that store the chemical composition of the parent brine at a specific pressure-temperature dependent density. Such FIs are therefore excellent records of the original physicochemical conditions of the source brine. Brillouin spectroscopy (BS) is a novel laser-based technique that uses density fluctuations in FIs to directly measure entrapment temperatures and thus the initial brine temperature during crystal growth. In this seminar, the BS method will be introduced and two application cases will be presented using salt layers from the Dead Sea which were deposited during two interglacial periods. In addition to the basic principles, both the recommended sampling strategy and pitfalls along with associated limitations will be presented. The conclusion will be that the salt layers commonly deposited in the Dead Sea basin consist of two types that formed preferentially in summer (coarse-grained crystals) and winter (fine-grained crystals), which is mainly controlled by the degree of salt saturation of the lake water. Furthermore, it will be shown how (1) lake bottom temperatures have fluctuated seasonally (summer/winter), and that (2) paleo temperature trends can be reconstructed for an entire halite layer that was deposited during holomictic periods in the Dead Sea basin. This method is particularly promising for evaporites that formed near the surface if the material has not been affected by external processes such as tectonic burial/uplift, erosion, or mineral replacement.
  • seminar
    Date:
    21 May
    2023
    Sunday
    Hours:
    11:00
    -
    12:00

    “ Programmatic and Deep Learning Analysis Pipelines for 4D-STEM Materials Science Experiments”

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Colin Ophus
    Lawrence Berkeley National Laboratory, Berkeley

    Abstract

    Scanning transmission electron microscopy (STEM) is one of the most popular materials science methods to characterize the structure and chemistry of nanoscale samples, owing to its high resolution and many flexible operating modes. In a conventional STEM experiment, we focus the electron beam down to a probe from nanometer to sub-angstrom scale, and scan it over the sample surface while recording diffracted signals which are transmitted through the specimen. STEM can also record analytic signals such as x-rays generated by the electron beam to measure composition, or energy loss of the transmitted electrons to probe the electronic structure of samples. Conventional STEM imaging detectors experiments produce only a few intensity values at each probe position, but modern high-speed detectors allow us to measure a full 2D diffraction pattern, over a grid of 2D probe positions, forming a four dimensional (4D)-STEM dataset. These 4D-STEM datasets record information about the local phase, orientation, deformation, and other parameters, for both crystalline and amorphous materials. 4D-STEM datasets can contain millions of images and therefore require highly automated and robust software codes to extract the target properties. In this talk, I will introduce our open source py4DSTEM analysis toolkit, and show how we use these codes to perform data-intensive studies of material properties over functional length scales. I will also demonstrate some applications of modern machine learning tools, to perform measurements on electron diffraction patterns where property signals have been scrambled by multiple scattering of the electron beam.
  • seminar
    Date:
    15 May
    2023
    Monday
    Hours:
    11:00
    -
    12:00

    KENDREW LECTURE: Computational Structural Biology in the Era of Deep Learning

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. John Moult
    Institute of Bioscience and Biotechnology Research Department of Cell Biology and Molecular Genetics University of Maryland
  • seminar
    Date:
    14 May
    2023
    Sunday
    Hours:
    11:00
    -
    12:00

    Projecting the impacts of climate change on human society

    Location: Sussman Family Building for Environmental Sciences
    participants: Ram Fishman
    Tel Aviv University
  • seminar
    Date:
    10 May
    2023
    Wednesday
    Hours:
    11:00
    -
    12:00

    "Simulations for materials in energy"

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Nuria Lopez
    Institute of Chemical Research of Catalonia (ICIQ)

    Abstract

    Finding new materials for the conversion of CO2 into useful products is a complex task. Simulations can provide mechanistic and stability insights trying to accelerate the process. In my talk I will present the different degrees of complexity that we try to address in the simulations and which are the major challenges in the field.
  • seminar
    Date:
    7 May
    2023
    Sunday
    Hours:
    11:00
    -
    12:00

    Determining the age of the Kalahari Group, Southern Africa, using complex solutions for cosmogenic isotope concentrations

    Location: Sussman Family Building for Environmental Sciences
    participants: Ari Matmon
    The Hebrew university of Jerusalem
  • seminar
    Date:
    2 May
    2023
    Tuesday
    Hours:
    14:00
    -
    15:00

    Conspiring with the Enemy: A Unique Mechanism in Class A JDPs Stabilizes Oncogenic p53 Mutants

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Guy Zoltsman
    Dept. of Chemical & Structural Biology Weizmann Institute
  • seminar
    Date:
    30 April
    2023
    Sunday
    Hours:
    11:00
    -
    12:00

    Soft Matter and Biomaterials Seminar: Cytoskeletal dynamics generate active liquid-liquid phase separation.

    Location: Perlman Chemical Sciences Building
    participants: Dr. Alexandra Tayar
    Dept. Chemical and Biological Physics, WIS

    Abstract

    Liquid-Liquid phase separation (LLPS) has been of fundamental importance in the assembly of thermally driven materials and has recently emerged as an organizational principle for living systems. Biological phase separation is driven out of equilibrium through complex enzyme composition, chemical reactions, and mechanical activity, which reveals a gap in our understanding of this fundamental phenomenon. Here we study the impact of mechanical activity on LLPS. We design a DNA-based LLPS system coupled to flows through molecular motors and a cytoskeleton network. Active stress at an interface of a liquid droplet suppressed phase separation and stabilized a single-phase regime well beyond the equilibrium binodal curve. The phase diagram out of equilibrium revealed a 3-dimensional phase space that depends on temperature and local molecular activity. Similar dynamics and structures are observed in simulations, suggesting that suppression of liquid phase separation by active stress is a generic feature of liquid phase separation.
  • seminar
    Date:
    30 April
    2023
    Sunday
    Hours:
    11:00
    -
    12:00

    Oceanic Internal Gravity Waves: sources, sinks, and interactions with the eddy field. 

    Location: Sussman Family Building for Environmental Sciences
    participants: Roy Barkan
    Tel Aviv University

    Abstract

    The global oceanic overturning circulation and the transport of heat and dissolved gases are strongly controlled by upper ocean turbulent mixing that is driven by the breaking of internal gravity waves (IWs). Understanding the life cycle of oceanic IWs, from generation to dissipation, is therefore crucial for improving the representation of ocean mixing in climate models, which do not resolve the IW field.  Oceanic IWs are observed to have a continuous energy distribution across spatial and temporal scales – an internal wave continuum – despite being forced primarily at near-inertial and tidal frequencies at large scales. The formation of the IW continuum and the associated energy transfer to dissipative scales have been traditionally attributed to wave-wave interactions and to Doppler shifting of wave frequencies by currents. Here, we provide evidence from realistic numerical simulations that oceanic eddies rapidly diffuse storm-forced wave energy across spatiotemporal scales, thereby playing a dominant role in the formation of the IW continuum and the corresponding spatiotemporal distribution of energy dissipation. We further demonstrate that winds can play an important role in damping oceanic IWs through current feedback.  This results in a substantial reduction in wind power input at near inertial frequencies and a net energy sink for internal tides.
  • seminar
    Date:
    27 April
    2023
    Thursday
    Hours:
    11:00
    -
    12:00

    Activation and arrest of thermal pressurization in localized faults

    Location: Sussman Family Building for Environmental Sciences
    participants: Nir Badt
    The University of Pennsylvania

    Abstract

    Thermal Pressurization (TP) is expected to be a dominant frictional weakening mechanism during earthquakes. However, due to experimental limitations there is a lack of direct evidence for the activation of TP in controlled laboratory conditions and most of our knowledge is derived from field studies and theoretical predictions. We present experiments performed by a rotary-shear apparatus where TP is activated in localized faults in Frederick diabase under constant normal stress of 50 MPa, confining pressure of 45 MPa and initial pore water pressure of 25 MPa. We show that by changing the permeability of the host rock we can control the shear stress drop during a TP event in the experimental fault. The TP events are short-lived in bare-surface faults as the opening of existing fractures around the fault plane drains the excess pore fluid. Wider, gouge-filled faults show more persistent frictional weakening, but at a slower rate, which is attributed to the compressibility of the gouge. In addition, we test the effects of transient fault dilation on the duration of a TP event through an expansion of the prevailing TP model, using a one-dimensional numerical simulation. We conclude that dynamic changes to the hydraulic diffusivity around the fault plane and persistent fault dilation, due to geometrical irregularities, are the most likely mechanisms to arrest TP during an earthquake.
  • seminar
    Date:
    24 April
    2023
    Monday
    Hours:
    14:00
    -
    15:00

    Approaching non-equilibrium: from machine learning to non-adiabatic dynamics

    Location: Perlman Chemical Sciences Building
    participants: Dr. Sergei Tretiak
    Theoretical Division & Center for Integrated Nanotechnologies (CINT), Los Alamos National Laboratory

    Abstract

    Machine learning (ML) became a premier tool for modeling chemical processes and materials properties. For instance, ML interatomic potentials have become an efficient alternative to computationally expensive quantum chemistry simulations. In the case of reactive chemistry designing high-quality training data sets is crucial to overall model accuracy. To address this challenge, we develop a general reactive ML interatomic potential through unbiased active learning with an atomic configuration sampler inspired by nanoreactor molecular dynamics. The resulting model is then applied to study five distinct condensed-phase reactive chemistry systems: carbon solid-phase nucleation, graphene ring formation from acetylene, biofuel additives, combustion of methane and the spontaneous formation of glycine from early-earth small molecules. In all cases, the results closely match experiment and/or previous studies using traditional model chemistry methods. Altogether, explosive growth of user-friendly ML frameworks, designed for chemistry, demonstrates that the field is evolving towards physics-based models augmented by data science. I will also overview some applications of Non-adiabatic EXcited-state Molecular Dynamics (NEXMD) framework developed at several institutions. The NEXMD code is able to simulate tens of picoseconds photoinduced dynamics in large molecular systems. As an application, I will exemplify ultrafast coherent excitonic dynamics guided by intermolecular conical intersections. Here X-ray Raman signals are able to sensitively monitor the coherence evolution. The observed coherences have vibronic nature that survives multiple conical intersection passages for several hundred femtoseconds at room temperature. These spectroscopic signals are possible to measure at XFEL facilities and our modeling results allow us to understand and potentially manipulate excited state dynamics and energy transfer pathways toward optoelectronic applications. References: 1. N. Fedik, R. Zubatyuk, N. Lubbers, J. S. Smith, B. Nebgen, R. Messerly, Y. W. Li, M. Kulichenko, A. I. Boldyrev, K. Barros, O. Isayev, and S. Tretiak “Extending machine learning beyond interatomic potentials for predicting molecular properties” Nature Rev. Chem. 6, 653 (2022). 2. G. Zhou, N. Lubbers, K. Barros, S. Tretiak, B. Nebgen, “Deep Learning of Dynamically Responsive Chemical Hamiltonians with Semi-Empirical Quantum Mechanics,” Proc. Nat. Acad. Sci. USA, 119 e2120333119 (2022) 3. S. Zhang, M. Z. Makos, R. B. Jadrich, E. Kraka, B. T. Nebgen, S. Tretiak, O. Isayev, N. Lubbers, R. A. Messerly, and J. S. Smith “Exploring the frontiers of chemistry with a general reactive machine learning potential,” (2023) https://chemrxiv.org/engage/chemrxiv/article-details/6362d132ca86b84c77ce166c 4. A. De Sio, E. Sommer, X. T. Nguyen, L. Gross, D. Popović, B. Nebgen, S. Fernandez-Alberti, S. Pittalis, C. A. Rozzi, E. Molinari, E. Mena-Osteritz, P. Bäuerle, T. Frauenheim, S. Tretiak, C. Lienau, “Intermolecular conical intersections in molecular aggregates” Nature Nanotech. 16, 63 – 68 (2021). 5. V. M. Freixas, D. Keefer, S. Tretiak, S. Fernandez-Alberti, and S. Mukamel, “Ultrafast coherent photoexcited dynamics in a trimeric dendrimer probed by X-ray stimulated-Raman signals,” Chem. Sci., 13, 6373 – 6384 (2022).
  • seminar
    Date:
    18 April
    2023
    Tuesday
    Hours:
    14:00
    -
    15:00

    Structural Biology Response to Biomedical Threats

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Wladek Minor
    Department of Molecular Physiology and Biological Physics University of Virginia
  • seminar
    Date:
    16 April
    2023
    Sunday
    Hours:
    11:00
    -
    12:00

    Protein Phase Transitions

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Tuomas Knowles
    Dept. of Chemistry, Cavendish Laboratory, University of Cambridge

    Abstract

    Proteins are the fundamental building blocks of life. They form high performance materials and carry out cellular functions. They are able to fulfil these roles by assembling together to form sophisticated structures and architectures, which in many cases extend to mesoscopic liquid or solid phases. This talk focuses on understanding the transitions between these phases, their fundamental material properties and the way that the modulate biological function and malfunction. I will then discuss two areas opened up by the control of protein assembly. I will first focus on the understanding of the mechanism of protein aggregation and the discovery of molecules that can ameliorate malfunctioning protein self-assembly in a range of age-associated disease states. I will then outline some of our efforts to control protein self-assembly to form silk-inspired sustainable materials
  • seminar
    Date:
    2 April
    2023
    Sunday
    Hours:
    14:00

    Chemical and Biological Physics Guest Seminar

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof Prineha Narang
    UCLA

    Abstract

    In this talk, I will present theoretical and computational chemistry approaches to describe excited-states in quantum matter, and predicting emergent states created by external drives. Understanding the role of such light-matter interactions in the regime of correlated electronic systems is of paramount importance to fields of study across chemical and condensed matter physics, and ultrafast dynamics1. The simultaneous contribution of processes that occur on many time and length-scales have remained elusive for state-of-the-art calculations and model Hamiltonian approaches alike, necessitating the development of new methods in computational chemistry. I will discuss our work at the intersection of ab initio cavity quantum-electrodynamics and electronic structure methods to treat electrons, photons and phonons on the same quantized footing, accessing new observables in strong light-matter coupling. Current approximations in the field almost exclusively focus on electronic excitations, neglecting electron-photon effects, for example, thereby limiting the applicability of conventional methods in the study of polaritonic systems, which requires understanding the coupled dynamics of electronic spins, nuclei, phonons and photons. With our approach we can access correlated electron-photon and photon-phonon dynamics2–7, essential to our latest work on driving quantum materials far out-of-equilibrium to control the coupled electronic and vibrational degrees-of-freedom 8–19. In the second part of my talk, I will demonstrate how the same approach can be generalized in the context of control of molecular quantum matter and quantum transduction. As a first example, I will discuss a cavity-mediated approach to break the inversion symmetry allowing for highly tunable even-order harmonic generation (e.g. second- and fourth-harmonic generation) naturally forbidden in such systems. This relies on a quantized treatment of the coupled light-matter system, similar to the driven case, where the molecular matter is confined within an electromagnetic environment and the incident (pump) field is treated as a quantized field in a coherent state. When the light-molecule system is strongly coupled, it leads to two important features: (i) a controllable strong-coupling-induced symmetry breaking, and (ii) a tunable and highly efficient nonlinear conversion efficiency of the harmonic generation processes 20–22. Both of these have implications for molecular quantum architectures. Being able to control molecules at a quantum level gives us access to degrees of freedom such as the vibrational or rotational degrees to the internal state structure. Finally, I will give an outlook on connecting ideas in cavity control of molecules with quantum information science.
  • seminar
    Date:
    2 April
    2023
    Sunday
    Hours:
    11:00
    -
    12:00

    Fluorescent nucleosides, nucleotides and oligonucleotides

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Yitzhak Tor
    University of California San Diego
  • seminar
    Date:
    2 April
    2023
    Sunday
    Hours:
    11:00

    Global warming accelerates soil heterotrophic respiration

    Location: Sussman Family Building for Environmental Sciences
    participants: Alon Nissan
    ETH Zurich

    Abstract

    Carbon efflux from soils is the largest terrestrial carbon source to the atmosphere, yet it remains one of the most uncertain fluxes in the Earth’s carbon budget. A dominant component of this flux is heterotrophic respiration, influenced by several environmental factors, most notably soil temperature and moisture. We developed a mechanistic model from micro to global scale to explore how changes in soil water content and temperature affect soil heterotrophic respiration. Simulations, laboratory measurements, and field observations validate the new approach. Estimates from the model show that heterotrophic respiration has been increasing since the 1980s at a rate of about 2% per decade globally. Using future projections of surface temperature and soil moisture, the model predicts a global increase of about 40% in heterotrophic respiration by the end of the century under the worst-case emission scenario, where the Arctic region is expected to experience a more than two-fold increase, driven primarily by declining soil moisture rather than temperature increase.  
  • seminar
    Date:
    29 March
    2023
    Wednesday
    Hours:
    11:00
    -
    12:00

    Emerging research landscape of altermagnetism

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Tomas Jungwirth
    Institute of Physics, Czech Academy of Sciences, Czech Republic School of Physics and Astronomy, University of Nottingham, UK

    Abstract

    Magnetism is one of the largest, most fundamental, and technologically most relevant fields of condensed-matter physics. Traditionally, two elementary magnetic phases have been distinguished - ferromagnetism and antiferromagnetism. The spin polarization in the electronic band structure reflecting the magnetization in ferromagnetic crystals underpins the broad range of time-reversal symmetry-breaking responses in this extensively explored and exploited type of magnets. By comparison, antiferromagnets have vanishing net magnetization. Recently, there have been observations of materials in which strong time-reversal symmetry-breaking responses and spin-polarization phenomena, typical of ferromagnets, are accompanied by antiparallel magnetic crystal order with vanishing net magnetization, typical of antiferromagnets [1]. A classification and description based on spin-symmetry principles offers a resolution of this apparent contradiction by establishing a third distinct elementary magnetic phase, dubbed altermagnetism [2]. We will start the talk with an overview of the still emerging unique phenomenology of this unconventional d-wave (or higher even-parity wave) magnetic phase, and of the wide array of altermagnetic materials. We will then show how altermagnetism can facilitate a development of ultra-fast and low-dissipation spintronic information technologies, and can have impact on a range of other modern areas of condensed matter physics and nanoelectronics. References [1] L. Šmejkal, A. H. MacDonald, J. Sinova, S. Nakatsuji, T. Jungwirth, Nature Reviews Mater. 7, 482 (2022). [2] L. Šmejkal, J. Sinova & T. Jungwirth, Phys. Rev. X (Perspective) 12, 040501 (2022).
  • seminar
    Date:
    29 March
    2023
    Wednesday
    Hours:
    11:00
    -
    12:00

    Emerging research landscape of altermagnetism

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Tomas Jungwirth
    Institute of Physics, Czech Academy of Sciences

    Abstract

    Magnetism is one of the largest, most fundamental, and technologically most relevant fields of condensed-matter physics. Traditionally, two elementary magnetic phases have been distinguished - ferromagnetism and antiferromagnetism. The spin polarization in the electronic band structure reflecting the magnetization in ferromagnetic crystals underpins the broad range of time-reversal symmetry-breaking responses in this extensively explored and exploited type of magnets. By comparison, antiferromagnets have vanishing net magnetization. Recently, there have been observations of materials in which strong time-reversal symmetry-breaking responses and spin-polarization phenomena, typical of ferromagnets, are accompanied by antiparallel magnetic crystal order with vanishing net magnetization, typical of antiferromagnets [1]. A classification and description based on spin-symmetry principles offers a resolution of this apparent contradiction by establishing a third distinct elementary magnetic phase, dubbed altermagnetism [2]. We will start the talk with an overview of the still emerging unique phenomenology of this unconventional d-wave (or higher even-parity wave) magnetic phase, and of the wide array of altermagnetic materials. We will then show how altermagnetism can facilitate a development of ultra-fast and low-dissipation spintronic information technologies, and can have impact on a range of other modern areas of condensed matter physics and nanoelectronics. References [1] L. Šmejkal, A. H. MacDonald, J. Sinova, S. Nakatsuji, T. Jungwirth, Nature Reviews Mater. 7, 482 (2022). [2] L. Šmejkal, J. Sinova & T. Jungwirth, Phys. Rev. X (Perspective) 12, 040501 (2022).
  • seminar
    Date:
    28 March
    2023
    Tuesday
    Hours:
    14:00
    -
    15:00

    Intestinal mucin is a chaperone of multivalent copper

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Nava Reznik
    Fass Lab Dept. of Chemical & Structural Biology Weizmann Institute
  • seminar
    Date:
    26 March
    2023
    Sunday
    Hours:
    11:00

    From Oceanic Blooms to Dust Events: Exploring the Activity and Survival Strategies of Bioaerosols

    Location: Sussman Family Building for Environmental Sciences
    participants: Naama Lang-Yona
    Technion, Haifa
  • seminar
    Date:
    23 March
    2023
    Thursday
    Hours:
    10:00
    -
    11:00

    Chemical and Biological Physics Guest Seminar

    Location: Perlman Chemical Sciences Building
    participants: Prof Maxim Sukharev
    Arizona State University

    Abstract

    Molecular plasmonics has been a hot topic for the past several years. At the heart of the primary interest in plasmonics is the strong electromagnetic field localization at resonant frequencies corresponding to surface plasmon-polariton modes. Thanks to riveting advancements in nanofabrication technologies, we have achieved nearly 1 nm spatial resolution (and in some cases even below that!) and are able to fabricate a wide variety of nanosystems ranging from nanoparticles of various shapes to metasurfaces comprised of periodic arrays of nanoparticles and/or nanoholes of any imaginable geometry. Such systems have recently emerged as new platforms for strong light-matter interactions. Combined with molecular ensembles, these constructs exhibit a remarkable set of optical phenomena ranging from the exciton-plasmon strong coupling to the second harmonic generation altered by molecular resonances. In this talk I will discuss both linear and nonlinear optical properties of plasmonic materials coupled to quantum emitters of various complexity. I will also introduce a newly developed computational approach that can be used to efficiently simulate a large number of complex molecules driven by electromagnetic radiation crafted at plasmonic interfaces.
  • seminar
    Date:
    19 March
    2023
    Sunday
    Hours:
    11:00

    Groundwater-surface water interactions in coastal environments and the impact of hydrogeological changes.

    Location: Sussman Family Building for Environmental Sciences
    participants: Anner Paldor
    Tel Aviv University
  • seminar
    Date:
    16 March
    2023
    Thursday
    Hours:
    15:00
    -
    16:00

    Joint Chemical and Biological Physics and Molecular Chemistry and Materials Science Guest Seminar

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof Michael Pittelkow
    University of Copenhagen, Denmark

    Abstract

    I will discuss the synthesis and properties of a range of aromatic-, anti-aromatic- and helical aromatic molecules.1 The talk will feature molecules with 'weird' magnetic properties, helical chirality and abnormal reactivity due to close proximity. I will discuss some of the unusual properties (and some of the very trivial and unsurprising properties) of these large well-defined conjugated molecules. I will describe the journey from fundamental studies of the acid-mediated oligomerization of simple 1,4-benzoquinones to the controlled synthesis of heterocyclic [8] circulenes (featuring an antiaromatic planar cyclooctatetraene) and even a larger planar [9] helicene. In the simplest picture two units of benzoquinone gives a dihydroxy-dibenzofuran + water, thus forming a new furan ring. This sets up a 1+1=3 ‘logic’ for elongation of the -system. The synthetic methodology has allowed us to prepare a range of fully conjugated helicenes, including the longest known optically resolved chiral [13] helicenes. The helicenes and circulenes have been explored in a range of properties including as the blue fluorescent component in OLEDs, as G-quadruplex binding ligands and in fundamental studies of antiaromaticity and chirality.
  • seminar
    Date:
    15 March
    2023
    Wednesday
    Hours:
    15:00
    -
    16:00

    Chemical and Biological Physics Guest Seminar

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof Per Hedegard
    Niels Bohr Institute, University of Copenhagen

    Abstract

    The so-called CISS phenomenon refers to the observation, that when electrons are transported through a chiral molecule, as e.g. a helix, then they will emerge spin polarized even though when entering they are not spin polarized. Often this effect is observed using magnetized leads. Remarkably, it seems that many experiments break the Onsager reciprocity principle. Onsager’s principle is very deep and depends on very few assumptions about the system - mainly about behavior under time reversal. I will present a possible solution to this conundrum
  • seminar
    Date:
    15 March
    2023
    Wednesday
    Hours:
    11:00
    -
    12:00

    Towards resolving dynamics of molecular machines using time-resolved cryo-EM

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Rouslan Efremov
    VIB-VUB Center for Structural Biology Belgium
  • seminar
    Date:
    14 March
    2023
    Tuesday
    Hours:
    14:00
    -
    15:00

    Structure-based prediction of protein-protein and protein compound interactions on a proteome-wide scale

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Barry Honig
    Columbia University
  • seminar
    Date:
    12 March
    2023
    Sunday
    Hours:
    11:00

    TBA

    Location: Sussman Family Building for Environmental Sciences
    participants: Boswell Wing
    Colorado
  • seminar
    Date:
    12 March
    2023
    Sunday
    Hours:
    11:00
    -
    12:00

    Soft Matter and Biomaterials: “The Secret Ultrafast Motions of Protein Nanomachines”

    Location: Perlman Chemical Sciences Building
    participants: Prof. Gilad Haran
    Dept. Chemical and Biological Physics, WIS

    Abstract

    Multiple proteins function as nanomachines, and carry out multiple specific tasks in the cell by alternating chemical steps with conformational transitions. Single-molecule FRET spectroscopy is a powerful tool for studying the internal motions of proteins. In recent years, we have been using this technique to study a range of protein machines, surprisingly finding in each case microsecond-time-scale internal dynamics. What is the role of these fast motions in the much-slower functional cycles of these machines?
  • seminar
    Date:
    5 March
    2023
    Sunday
    Hours:
    00:00

    TBA

    Location: Sussman Family Building for Environmental Sciences
    participants: Ann Pearson
  • seminar
    Date:
    28 February
    2023
    Tuesday
    Hours:
    14:00
    -
    15:00

    Fast and Processive Artificial Molecular Motors and Rotors Made of DNA

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Eyal Nir
    Department of Chemistry Ben-Gurion University
  • seminar
    Date:
    28 February
    2023
    Tuesday
    Hours:
    11:00
    -
    12:00

    Intrinsically Chiral and Multimodal Click Chemistry

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Han Zuilhof
    Department of Organic Chemistry, Wageningen University, The Netherlands

    Abstract

    Click chemistry has revolutionized many facets of the molecular sciences, with the realization of reactions that are ‘‘modular, wide in scope, give very high yields, generate only inoffensive byproducts that can be removed by nonchromatographic methods and are stereospecific”. Yet surprisingly little attention has been given to the development of intrinsically chiral click reactions (potentially enantiospecific, rather than ‘only’ enantioselective due to chiral auxiliary groups), while the modularity of many click reactions is best compared to one-dimensional LEGO. Of course, much could be done within the constraints – hence forementioned revolution – but it drove attention towards an extension of available click chemistries. Kolb, H. C.; Finn, M.; Sharpless, K. B., Click chemistry: diverse chemical function from a few good reactions. Angew. Chem. Int. Ed. 2001, 40, 2004-2021. The talk will focus on the resulting investigations in the field of S(VI) exchange chemistry, with specific emphasis on two fields: a) the development of the intrinsically enantiospecific click reactions and their use to e.g. make synthetic polymers with 100% backbone chirality that combine stability & degradabbility, and b) the development of multimodular click chemistry and single-polymer studies by a combination of AFM, TEM, scanning Auger microscopy
  • seminar
    Date:
    26 February
    2023
    Sunday
    Hours:
    00:00

    TBA

    Location: Sussman Family Building for Environmental Sciences
    participants: Holly Michael
  • seminar
    Date:
    22 February
    2023
    Wednesday
    Hours:
    11:00
    -
    12:00

    Strong light-exciton interactions in 2D semiconductors

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Itai Epstein
    School of electrical engineering, TAU

    Abstract

    The remarkable properties of excitons in transition-metal-dichalcogenides (TMDs), together with the ability to readily control their charge carriers, have attracted a significant amount of interest in recent years. Despite the atomic dimensions of the hosting 2D semiconductors, TMD excitons exhibit strong interaction with light, both in absorption and photoemission processes, and practically dominate the optical response of these 2D materials. In this talk, I will introduce several approaches for achieving extremely strong light-exciton interactions. First, by optical and electrical manipulation of TMD excitons inside a van der Waals heterostructure cavity [1], second, via the formation of highly-confined, in-plane exciton polaritons [2], and third, through the realization of valley-polarized hyperbolic exciton polaritons [3]. These enhanced light–exciton interactions may provide a platform for studying excitonic phase-transitions, quantum nonlinearities and the enablement of new possibilities for 2D semiconductor-based optoelectronic devices. [1] I. Epstein et al, "Near-unity Light Absorption in a Monolayer WS2 Van der Waals Heterostructure Cavity", Nano letters 20 (5), 3545-3552 (2020). [2] I. Epstein et al, "Highly Confined In-plane Propagating Exciton-Polaritons on Monolayer Semiconductors", 2D Materials 7, 035031 (2020). [3] T. Eini, T. Asherov, Y. Mazor, and I. Epstein, "Valley-polarized Hyperbolic Exciton Polaritons in Multilayer 2D Semiconductors at Visible Frequencies", Phys. Rev. B 106, L201405 (2022).
  • seminar
    Date:
    19 February
    2023
    Sunday
    Hours:
    11:00

    flow, deformation and, reaction in porous media: the Coupling of Flow and Elastic Expansion in Porous Media

    Location: Sussman Family Building for Environmental Sciences
    participants: Yaniv Edery
  • seminar
    Date:
    19 February
    2023
    Sunday
    Hours:
    11:00
    -
    12:00

    Soft Matter and Biomaterials Seminar

    Location: Perlman Chemical Sciences Building
    participants: Prof. Avi Schroeder
    Dept. Chemical Engineering, Technion

    Abstract

    Medicine is taking its first steps toward patient-specific cancer care. Nanoparticles have many potential benefits for treating cancer, including the ability to transport complex molecular cargoes, including siRNA and protein, as well as targeting specific cell populations. The talk will explain the fundamentals of nanotechnology, from ‘barcoded nanoparticles’ that target sites of cancer where they perform a programmed therapeutic task. Specifically, liposomes diagnose the tumor and metastasis for their sensitivity to different medications, providing patient-specific drug activity information that can be used to improve the medication choice. The talk will also describe how liposomes can be used for degrading the pancreatic stroma to allow subsequent drug penetration into pancreatic adenocarcinoma and how nanoparticle’ biodistribution and anti-cancer efficacy are impacted by the patient’s sex and, more specifically, the menstrual cycle. The evolution of drug delivery systems into synthetic cells, programmed nanoparticles that have an autonomous capacity to synthesize diagnostic and therapeutic proteins inside the body, and their promise for treating cancer and immunotherapy, will be discussed. References: 1) Theranostic barcoded nanoparticles for personalized cancer medicine, Yaari et al. Nature Communications, 2016, 7, 13325 2) Collagenase nanoparticles enhance the penetration of drugs into pancreatic tumors, Zinger et al., ACS Nano, 13 (10), 11008-11021, 2019 3) Targeting neurons in the tumor microenvironment with bupivacaine nanoparticles reduces breast cancer progression and metastases, Science Advances, Kaduri et al., 7 (41), eabj5435, 2021 4) Nanoparticles accumulate in the female reproductive system during ovulation affecting cancer treatment and fertility, Poley et al., ACS nano, 2022
  • seminar
    Date:
    14 February
    2023
    Tuesday
    Hours:
    11:00
    -
    12:00

    Photoinduced regioselective functionalization of arenes at proximal and distal sites

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Debabrata Maiti
    Department of Chemistry & IDP in Climate Studies, IIT Bombay

    Abstract

    Over years’ transition metal-catalyzed C-H activation has propelled the field of organic synthesis for the construction of structurally complex and diverse molecules in resource-economical fashion. In this context, non-directed C-H activation has gained unprecedented attention for attaining region-specific C-H functionalizations in a step-economic mode. Unlike traditional Fujiwara-Moritani reaction, this approach relies on ligand assistance and thus uses arene as the limiting reagent. However, all existing non-directed C-H functionalizations utilize high thermal energy to induce the functional group which eventually put the regioselectivity at stake. In addition, use of super stoichiometric costly silver salts to regenerate the catalyst produces unwanted metal waste. In aid of developing a more sustainable and environmentally benign approach, we have established a photoredox catalytic system by a merger of palladium/organo-photocatalyst(PC) which forges highly regeiospecific C-H olefination of diverse arenes and heteroarenes. Visible light nullifies the requirement of silver salts and thermal energy in executing “region-resolved” Fujiwara-Moritani reaction.
  • seminar
    Date:
    12 February
    2023
    Sunday
    Hours:
    11:00
    -
    12:00

    “Life at Interfaces- Challenges and Opportunities in the Miniaturization of Bioinspired Robots”

    Location: Perlman Chemical Sciences Building
    participants: Dr. Bat-El Pinchasik
    School of Mechanical Engineering, Faculty of Engineering, TAU
  • seminar
    Date:
    7 February
    2023
    Tuesday
    Hours:
    11:00
    -
    12:00

    From Spin Materials to Electron Transfer Catalysis

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Swadhin K Mandal
    Department of Chemical Sciences, Indian Institute of Science Education and Research, Kolkata

    Abstract

    The major concerns about industrially used catalytic systems today are: i) the high cost of catalysts; ii) the toxicity of heavy transition metals; iii) difficulties in removing trace amounts of toxic-metal residues from the desired product; and, finally, iv) rare transition metal depletion, which does not meet the requirement of sustainable development. Developing environmentally friendly catalysts is an excellent option in this regard. Naturally, the most recent catalyst development trend heralded a new era of metal-free catalysis or catalysts based on earth-abundant, nontoxic, and low-cost metals. This talk will go over our recent advances [1-4] in using small molecules to systematically mimic transition metal-based catalysis. We designed electron transfer catalysis using the smallest polycyclic odd alternant hydrocarbon, phenalenyl (PLY)-based molecules, which was inspired by a completely different field of molecular spin materials [5]. This talk will focus on how to avoid transition metals when performing various cross-coupling catalysis.
  • seminar
    Date:
    5 February
    2023
    Sunday
    Hours:
    11:00

    Forecasting surface weather and storm tracks at one-month leads: role of the stratosphere and the Madden Julian Oscillation

    Location: Sussman Family Building for Environmental Sciences
    participants: Chaim Garfinkel
    The Hebrew University of Jerusalem

    Abstract

    The traditional approach to weather forecasting on one- to two-week timescales utilizes weather forecasting models, but on timescales longer than two weeks, the value of deterministic (or ensemble-based probabilistic) forecasts weakens. This is due to the presence of chaotic variability in the atmosphere. Yet certain modes of variability in the climate system have timescales longer than this two-week threshold, and the key to longer-scale prediction is to take advantage of these modes when they open up windows of opportunity. By understanding the impacts of these modes of variability on surface weather, the potential for improved forecasts on a monthly timescale can be demonstrated and eventually realized.  Two such classes of modes of variability are stratospheric variability (both in the tropical and polar stratosphere) and tropical tropospheric variability (e.g. the Madden-Julian Oscillation and El Nino). For example, both polar stratospheric sudden warmings and the Madden-Julian Oscillation have been shown to influence European and Mediterranean weather, but it is unclear (1) what mechanism(s) underlie these connections, (2) how far in advance the impacts can be predicted, (3) what governs the magnitude of the surface impact, and (4) how well models capture these connections. This talk will review progress made towards addressing these issues over the past several years in my group.
  • seminar
    Date:
    2 February
    2023
    Thursday
    Hours:
    14:00

    Silver mines, the rise of money and the advent of democracy

    Location: Sussman Family Building for Environmental Sciences
    participants: Prof. Francis Albarède
    École Normale Supérieure de Lyon, France

    Abstract

    Over the last 2½ millenia, the world economy depended on prevailing currencies: the Athenian owl (530- 168 BCE), the Roman denarius (211 BCE-250 AD), the Spanish piece-of-eight (16th to 18th C), and today the US dollar. These reference monies were accepted everywhere and all, at least in the beginning, were made of silver. What is so special about this metal? Silver is useless and rare, but still abundant enough to match the wealth of nations and of their long-distance trade. Silver ores are associated with rare and recent tectonic environments, the Mediterranean world, notably the periphery of the Aegean Sea and Southern Iberia, and the American cordillera, Peru and Mexico. In contrast, they were markedly scarce in South and East Asia. After the virtual destruction of soils by the Anatolian farmers at the end of the Bronze Age, the Near and Middle East societies depended almost exclusively on the agriculture of Egypt and Mesopotamia. The Late Bronze Age collapse (ca. 1200 BCE) corresponded to the migration of Greek people and resulted in the annihilation of all the empires outside of the flood plains. Silver by weight was nevertheless used to save populations from famine and trade wheat, barley and copper. Military innovations, hoplites and their phalanx, were, with silver mines, the main resources of the Greeks. Mercenaries received their wages in silver, notably through the tributes exacted in silver by the Achaemenid (Persion) kings. By minting silver, the returning Greek mercenaries emerged as strong middle classes . They soon claimed their share of the power, toppled the tyrants, and installed democracy in many poleis from Greece and Southern Italy. Modern economics teaches us that egalitarian distribution of wealth is unfortunately unstable and this case is well illustrated by Syracuse. At the beginning of the common era, the Roman Empire found itself the owner of centuries of silver extracted from Greece and from Iberia. This bullion was used to buy luxury products, frankincense from Arabia, spices and cotton from India, ivory and precious wood from Africa. Leakage of silver towards the Indian Ocean was so strong that coins were quickly debased by copper and by 250 AD most of the silver had been lost. The progressive replacement of silver by a bimetallic system, gold for the rich and bronze for the working class, progressively fractured the society and ushered the brutal Middle Age regimes. Silver famine had finally destroyed the democratic ideal of the Greeks. This is food for thought as disappearing mining resources may severely affect our current vision of societies.
  • seminar
    Date:
    1 February
    2023
    Wednesday
    Hours:
    11:00
    -
    12:00

    M.Sc thesis defense: “Fermi-polaron description of excitonic scattering processes in layered systems from first principles”

    Location: Perlman Chemical Sciences Building
    participants: Guy Voscoboynik
    M.Sc student of Dr. Sivan Refaely Abramson

    Abstract

    Layered materials exhibit unique charge and energy transfer characteristics, making them promising candidates for emerging photophysical and photochemical applications, and particularly in energy conversion and quantum information science. In two-dimensional systems, spatial confinement in a certain dimension causes reduced dielectric screening and enhanced Coulomb interaction compared to bulk materials. Upon light excitation, the relaxation processes of the charge and energy carriers, as well as their rearrangement in the lateral plane, allow for unique and structure-specific interaction dynamics of the electrons and holes in these systems and of their bound states - neutral and charged excitons. In particular, these dimensionality effects induce strong exciton-electron and exciton-hole interactions in doped or gated systems, where optical excitations coexist alongside electronic excitations. These interactions dominate the exciton decay and diffusion and introduce bound three-particle states in such systems. A many-particle theoretical picture of the formation and propagation of these states is crucial for proper tracking and understanding of the interaction pathways, crystal momentum effects, the involved particle-particle coupling and their relation to the underlying structure, dimensionality, and symmetry.
  • seminar
    Date:
    31 January
    2023
    Tuesday
    Hours:
    14:00
    -
    15:00

    Chemical Evolution: From Origins of Life to Biotechnology

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Moran Frenkel-Pinter
    Institute of Chemistry The Hebrew University of Jerusalem
  • seminar
    Date:
    31 January
    2023
    Tuesday
    Hours:
    11:00

    Chemical and Biological Physics Guest Seminar

    Location: Perlman Chemical Sciences Building
    participants: Prof Tahei Tahara
    Molecular Spectroscopy Laboratory, Riken, Japan
  • seminar
    Date:
    29 January
    2023
    Sunday
    Hours:
    11:00

    Insolation Forcing and Eastern Mediterranean aridity: Evidence from the Dead Sea and implications for climate projections

    Location: Sussman Family Building for Environmental Sciences
    participants: Yochanan Kushnir
    Lamont-Dohert Earth Observatory Columbia University

    Abstract

    The Mediterranean region stands out among other subtropical regions in its projected drying response to the global rise in atmospheric greenhouse gas concentrations. This drying trend has already emerged out of the normal, random climate variability in the sensitive Eastern Mediterranean (EM) region. To better understand the dynamical mechanisms responsible for this regional sensitivity, we turn to past protracted EM drying states during warm geological epochs. A unique view of the historical and pre-historical hydroclimate of the EM-Levant has been gleaned from the continued study of the sedimentary and geochemical record left by the lakes that filled the tectonic basin of the Dead Sea. We revisit the Late Quaternary sediment record retrieved during the 2010-2011 Dead Sea Deep Drilling Project (DSDDP). The sediments clearly indicate that the Levant was drier during past warm interglacials than during the adjacent glacials but nonetheless experienced large variations in the intensity of the regional aridity. During each interglacial, extended thick deposits of salts accumulated at the Lake bottom, during millennia of significant regional aridity and severely reduced Mediterranean rains. These dry states were interrupted by extended wet intervals, fed by rains that were supplied by a blend of tropical and Mediterranean moisture. To understand the underlying causes of the EM-Levant interglacial hydroclimate variations, we put the Dead Sea record in the context of the Northern Hemisphere orbital insolation variations and their impact on the global climate system. We show that the changes in EM hydroclimate portrayed by the DSDDP record during the interglacials, are entirely consistent with the response of the North Atlantic Ocean and the overlying atmosphere and surrounding land areas to the changes in the latitudinal insolation gradient, as determined by climate models and evident by surface temperature proxies. This perspective provides new information regarding the dynamical processes responsible for the ongoing, greenhouse gas forced, EM drying.
  • seminar
    Date:
    25 January
    2023
    Wednesday
    Hours:
    11:00
    -
    12:00

    "Molecules in a Quantum-Optical Flask"

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Tal Schwartz
    School of Chemistry, TAU

    Abstract

    "Molecules in a Quantum-Optical Flask" When confined to small dimensions, the interaction between light and matter can be enhanced up to the point where it overcomes all the incoherent, dissipative processes. In this "strong coupling" regime the photons and the material start to behave as a single entity, having its own quantum states and energy levels. In this talk I will discuss how such cavity-QED effects can be used in order to control material properties and molecular processes. This includes, for example, modifying photochemical reactions [1], enhancing excitonic transport up to ballistic motion close to the light-speed [2-3] and potentially tailoring the mesoscopic properties of organic crystals, by hybridizing intermolecular vibrations with electromagnetic THz fields [4-5]. 1. J. A. Hutchison, T. Schwartz, C. Genet, E. Devaux, and T. W. Ebbesen, "Modifying Chemical Landscapes by Coupling to Vacuum Fields," Angew. Chemie Int. Ed. 51, 1592 (2012). 2. G. G. Rozenman, K. Akulov, A. Golombek, and T. Schwartz, "Long-Range Transport of Organic Exciton-Polaritons Revealed by Ultrafast Microscopy," ACS Photonics 5, 105 (2018). 3. M. Balasubrahmaniyam, A. Simkovich, A. Golombek, G. Ankonina, and T. Schwartz, "Unveiling the mixed nature of polaritonic transport: From enhanced diffusion to ballistic motion approaching the speed of light," arXiv:2205.06683 (2022). 4. R. Damari, O. Weinberg, D. Krotkov, N. Demina, K. Akulov, A. Golombek, T. Schwartz, and S. Fleischer, "Strong coupling of collective intermolecular vibrations in organic materials at terahertz frequencies," Nat. Commun. 10, 3248 (2019). 5. M. Kaeek, R. Damari, M. Roth, S. Fleischer, and T. Schwartz, "Strong Coupling in a Self-Coupled Terahertz Photonic Crystal," ACS Photonics 8, 1881 (2021).
  • seminar
    Date:
    24 January
    2023
    Tuesday
    Hours:
    14:00
    -
    15:00

    Intrinsically disordered proteins can also exhibit millisecond conformational dynamics

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Eitan Lerner
    The Alexander Silberman Institute of Life Sciences The Hebrew University
  • seminar
    Date:
    24 January
    2023
    Tuesday
    Hours:
    12:30
    -
    13:30

    Electro-freezing of Super-Cooled Water within Electrolytic Cells

    Location: Perlman Chemical Sciences Building
    participants: Danielle Amit Awaskar
    M.Sc student of Profs. Igor Lubomirsky and Meir Lahav

    Abstract

    Ice melts at 0 [˚C], however, water can be super-cooled homogeneously down to ~-40 [˚C] without freezing. The ability to control the temperature of freezing of super-cooled water is highly important in many scientific sub-fields. Freezing can be induced at higher temperatures by the application of electric fields (known as electro-freezing). Despite the importance of the process of electro-freezing, its mechanism at the molecular level is still not fully understood. Recently, icing experiments performed by our group have demonstrated that electro-freezing comprises of the interactions of an electric field with specific ions of trigonal planar configuration, creating arm-chair hexagons that mimic the hexagons of the crystal ice. In my research, I investigated the effect of electro-freezing of super-cooled water on silver and copper electrodes. I found that the mechanism of electro-freezing of super-cooled water as induced by the silver electrodes is very complex and irreproducible. In contrast, the high icing temperature (~-4 [˚C]) on the copper (111) face is induced primarily by a mechanism of epitaxy.
  • seminar
    Date:
    22 January
    2023
    Sunday
    Hours:
    12:00

    Chemical and Biological Physics Guest Seminar

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr Ilya Svetlizky
    Harvard University

    Abstract

    Plastic (irreversible) deformation of crystals requires disrupting the crystalline order, which happens through nucleation and motion of topological line defects called dislocations. Interactions between dislocations lead to the formation of complex networks that, in turn, dictate the mechanical response of the crystal. The severe difficulty in atomic systems to simultaneously resolve the emerging macroscopic deformation and the evolution of these networks impedes our understanding of crystal plasticity. To circumvent this difficulty, we explore crystal plasticity by using colloidal crystals; the micrometer size of the particles allows us to visualize the deformation process in real-time and on the single particle level. In this talk, I will focus on two classical problems: instability of epitaxial growth and strain hardening of single crystals. In direct analogy to epitaxially grown atomic thin films, we show that colloidal crystals grown on mismatched templates to a critical thickness relax the imposed strain by nucleation of dislocations. Our experiments reveal how interactions between dislocations lead to an unexpectedly sharp relaxation process. I will then show that colloidal crystals can be strain-hardened by plastic shear; the yield strength increases with the dislocation density in excellent accord with the classical Taylor equation, originally developed for atomic crystals. Our experiments reveal the underlying mechanism for Taylor hardening and the conditions under which this mechanism fails.
  • seminar
    Date:
    22 January
    2023
    Sunday
    Hours:
    11:00

    Persistent and concurrent weather extremes in present and future climates

    Location: Sussman Family Building for Environmental Sciences
    participants: Kai Kornhuber
    Columbia University

    Abstract

    Recent severe summertime weather extremes in the Northern hemisphere extratropics such as the extraordinary 2021 North American Heatwave and the record-breaking floods in central Europe were in part driven by persistent circulation patterns in the tropospheric Jetstream. To what degree such circulation patterns will modulate extreme weather risk in a warming world is still uncertain and remains a highly debated topic in climate science. I will present results from recent studies that investigate physics of extraordinary extremes, future changes in weather persistence diagnosed by a feature tracking algorithm and future risks from concurrent extremes and associated impacts on crop production based on latest GGCMI-runs. A special emphasis will be placed on benchmarking the skill of CMIP5 and CMIP6 models to reproduce atmosphere dynamical mechanisms and associated extreme weather against reanalysis data short bio: Kai Kornhuber is an adjunct Associate Research Scientist at the Lamont-Doherty Earth Observatory, Columbia University in New York and a Senior Fellow on Climate Risks at the German Council on Foreign Relations. His research is concerned with physical drivers of extreme weather and climate events and associated societal impacts and risks under current and future climatic conditions. He is Founding Member of the EarthNetwork on Sustainable and Resilient Living in an Era of Increasing Disasters at Columbia’s Climate School, Co-Chair of the Compound Events Working Group at Risk-Kan, Steering Committee member of the HiWeather Project and a Co- Pi of the Project PERSEVERE within the BMBF Consortium.
  • seminar
    Date:
    22 January
    2023
    Sunday
    Hours:
    11:00
    -
    12:00

    Molecular and Cellular Dynamics Probed by High Speed Scanning Probe Microscopy

    Location: Perlman Chemical Sciences Building
    participants: Prof. Georg Fantner
    EPFL, Lausanne, Switzerland
  • seminar
    Date:
    18 January
    2023
    Wednesday
    Hours:
    14:00

    Chemical and Biological Physics Guest Seminar

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr Hillel Ori
    Harvard University

    Abstract

    Interfaces between systems with different properties are a common feature of Nature. However, the physics of interactions across such interfaces is often neglected. In this talk, I will focus on the case of biological tissue-tissue interfaces and show they can exhibit emergent electrical excitability, a phenomenon that has not been explored before. Using cultured cells and optical tools, I have found that interfaces between tissues with dissimilar electrophysiological properties can behave differently compared to the tissues on either side. In particular, the interface between non-excitable tissues can become excitable. Excitability of cells therefore depends on their position, not just the proteins they express. Moreover, my simulations reveal that interface excitability is extremely robust to parametric variation. I will briefly discuss the roots of this difference in the structures of the underlying dynamical systems, and will show examples of other excitable systems that can exhibit interfacial excitation, such as predator-prey dynamics and oscillating chemical reactions.
  • seminar
    Date:
    17 January
    2023
    Tuesday
    Hours:
    14:00
    -
    15:00

    Rational discovery of selective chemical probes of the polyamine deacetylase HDAC10

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Aubry Miller
    Cancer Drug Development German Cancer Research Center DKFZ, Germany
  • seminar
    Date:
    16 January
    2023
    Monday
    Hours:
    14:00

    Chemical and Biological Physics Guest Seminar

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr Ran Tivony
    University of Cambridge

    Abstract

    Cells carefully regulate the movement of solutes across their membrane using an intricate array of interconnected transport pathways. While beneficial for mediating essential cellular activities, the abundance of complex transport pathways severely limits the elucidation of particular translocation mechanisms in live-cell studies. We alleviate this impediment by taking a reductionist approach to incorporate specific transport pathways (e.g., transport proteins) in simplified artificial cell models, using giant unilamellar vesicles (GUVs) as a biologically-relevant chassis. To gain maximal control over the bioengineering process, we developed an integrated microfluidic platform capable of high-throughput production and purification of monodispersed GUV-based cell models. Using single-vesicle fluorescence analysis, we quantified the passive permeation rate of two biologically important electrolytes, protons (H+) and potassium ions (K+), and correlated their flux with electrochemical gradient buildup across the GUV lipid bilayer. Applying similar analysis principles, we also determined the H+/K+ selectively of two archetypal ion channels, gramicidin A and outer membrane porin F (OmpF). Altogether, our results provide an insight into the transport mechanism of ions across lipid bilayers and set a framework for elucidating protein-based transport in artificial cell models.
  • seminar
    Date:
    15 January
    2023
    Sunday
    Hours:
    11:00

    TBA

    Location: Sussman Family Building for Environmental Sciences
    participants: Adi Torfstein
    Hebrew University of Jerusalem
  • seminar
    Date:
    15 January
    2023
    Sunday
    Hours:
    11:00
    -
    12:00

    “Spherical polyelectrolytes and their self-assembly into colloidal crystals”

    Location: Perlman Chemical Sciences Building
    participants: Prof. Rafal Klajn
    Dept. Molecular Chemistry and Materials Science

    Abstract

    Self-assembly of inorganic nanoparticles (NPs) into ordered structures has led to a wide range of materials with unique optical, electronic, and catalytic properties. Various interactions have been employed to direct the crystallization of NPs, including van der Waals forces, hydrogen bonding, and magnetic dipolar interactions. Among them, Coulombic interactions have remained largely unexplored, owing to the rapid charge exchange between spherical NPs bearing high densities of opposite charges (superionic NPs). In this talk, I will describe a new method to assemble superionic NPs under conditions that preserve their native surface charge density. Our methodology was used to assemble oppositely charged NPs (“spherical polyelectrolytes”) into highly ordered assemblies exhibiting previously unknown morphologies.
  • seminar
    Date:
    12 January
    2023
    Thursday
    Hours:
    14:00
    -
    15:00

    GPCR structure and dynamics - Insights from Rhodopsin

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Oliver P. Ernst
    University of Toronto Canada
  • seminar
    Date:
    8 January
    2023
    Sunday
    Hours:
    11:00

    TBA

    Location: Sussman Family Building for Environmental Sciences
    participants: Dan Rabinowitz
    Tel Aviv University
  • seminar
    Date:
    3 January
    2023
    Tuesday
    Hours:
    14:00
    -
    15:00

    The Simple QTY Code for Protein Design

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Shuguang Zhang
    MIT Media Lab USA
  • seminar
    Date:
    2 January
    2023
    Monday
    Hours:
    13:00
    -
    14:00

    M.Sc thesis defense: “Probing the Composition and Structure of the Solid Electrolyte Interphase in Na Ion Anodes via DNP- Solid State NMR”

    Location: Helen and Milton A. Kimmelman Building
    participants: Yuval Steinberg
    M.Sc student of Dr. Michal Leskes

    Abstract

    The need for affordable large scale energy storage has risen dramatically with the increase in usage of renewable energy sources. In recent years, beyond Li batteries such as Na ion batteries (SIB), gained much interest due to limited Lithium resources. However, SIBs are still far from meeting the demands in terms of electrochemical performance, rendering research on SIBs very important. During battery cycling, chemical and electrochemical processes result in the formation of an interphase between the anode and electrolyte called the solid electrolyte interphase (SEI). The effect of the SEI on electrochemical performance cannot be overstated, as its composition and structure dictate interfacial ionic transport in the battery cell. Since the SEI is very thin (10-50 nm) and is composed of disordered, organic, and inorganic phases it is extremely difficult to characterize at the atomic-molecular level. In this seminar I will present methodology developed for probing the native SEI formed in SIBs by using nuclear magnetic resonance (NMR) and signal enhanced NMR by exogenous and endogenous dynamic nuclear polarization (DNP). Employing these techniques enabled us to gain information on the chemical composition of the SEI together with important insights into the SEI’s structural gradient formed with different Na electrolytes. Correlating the compositional and structural information acquired with the SEI’s function can assist in designing SIBs with improved performance and longer lifetime.
  • seminar
    Date:
    2 January
    2023
    Monday
    Hours:
    11:00
    -
    12:00

    Graphullerene: a new form of two-dimensional carbon

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Elena Meirzadeh
    Department of Chemistry, Columbia University

    Abstract

    The two natural allotropes of carbon, diamond and graphite, are extended networks of sp3- and sp2- hybridized carbon atoms, respectively. By mixing different hybridizations and geometries of carbon, one could conceptually construct countless synthetic allotropes. In this talk, I will introduce graphullerene, a new two-dimensional superatomic allotrope of carbon combining three- and four-coordinate carbon atoms. The constituent subunits of graphullerene are C60 fullerenes that are covalently interconnected within a molecular layer, forming graphene-like hexagonal sheets. The most remarkable thing about the synthesis of graphullerene is that the solid-state reaction produces large polyhedral crystals (hundreds of micrometers in lateral dimensions), rather than an amorphous or microcrystalline powder as one would typically expect from polymerization chemistry. Similar to graphite, the crystals can be mechanically exfoliated to produce molecularly thin flakes with clean interfaces—a critical requirement for the creation of heterostructures and optoelectronic devices. We find that polymerizing the fullerenes leads to a large change in the electronic structure of C60 and the vibrational scattering mechanisms affecting thermal transport. Furthermore, imaging few-layer graphullerene flakes using transmission electron microscopy and near-field nano-photoluminescence spectroscopy reveals the existence of moiré-like superlattices. The discovery of a superatomic cousin of graphene demonstrates that there is an entire family of higher and lower dimensional forms of carbon that may be chemically prepared from molecular precursors.
  • seminar
    Date:
    1 January
    2023
    Sunday
    Hours:
    11:00

    TBA

    Location: Sussman Family Building for Environmental Sciences
    participants: Yishai Weinstein
    Bar Ilan Univrsity
  • seminar
    Date:
    27 December
    2022
    Tuesday
    Hours:
    11:15
    -
    12:15

    “Intelligentsia of Nano-Architected Hierarchical Materials”

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Julia Greer
    California Institute of Technology

    Abstract

    Creation of reconfigurable and multi-functional materials can be achieved by incorporating architecture into material design. In our research, we design and fabricate three-dimensional (3D) nano-architected materials that can exhibit superior and often tunable thermal, photonic, electrochemical, biochemical, and mechanical properties at extremely low mass densities (lighter than aerogels), which renders them useful and enabling in technological applications. Dominant properties of such meta-materials are driven by their multi-scale nature: from characteristic material microstructure (atoms) to individual constituents (nanometers) to structural components (microns) to overall architectures (millimeters and above). Our research is focused on fabrication and synthesis of nano- and micro-architected materials using 3D lithography, nanofabrication, and additive manufacturing (AM) techniques, as well as on investigating their mechanical, biochemical, electrochemical, electromechanical, and thermal properties as a function of architecture, constituent materials, and microstructural detail. Additive manufacturing (AM) represents a set of processes that fabricate complex 3D structures using a layer-by-layer approach, with some advanced methods attaining nanometer resolution and the creation of unique, multifunctional materials and shapes derived from a photoinitiation-based chemical reaction of custom-synthesized resins and thermal post-processing. A type of AM, vat polymerization, has allowed for using hydrogels as precursors, and exploiting novel material properties, especially those that arise at the nano-scale and do not occur in conventional materials. The focus of this talk is on additive manufacturing via vat polymerization and function-containing chemical synthesis to create 3D nano- and micro-architected metals, ceramics, multifunctional metal oxides (nano-photonics, photocatalytic, piezoelectric, etc.), and metal-containing polymer complexes, etc., as well as demonstrate their potential in some real-use biomedical, protective, and sensing applications. I will describe how the choice of architecture, material, and external stimulus can elicit stimulus-responsive, reconfigurable, and multifunctional response
  • seminar
    Date:
    25 December
    2022
    Sunday
    Hours:
    11:00

    Lightning, Biology, and Evolution

    Location: Sussman Family Building for Environmental Sciences
    participants: Colin Price
    Tel Aviv University

    Abstract

    Most electrical activity in vertebrates and invertebrates occurs at extremely low frequencies (ELF), with characteristic maxima below 50 Hz. The origin of these frequency maxima is unknown and remains a mystery. We propose that over billions of years during the evolutionary history of living organisms on Earth, the natural electromagnetic resonant frequencies in the atmosphere, continuously generated by global lightning activity, provided the background electric fields for the development of cellular electrical activity. In some animals, the electrical spectrum is difficult to differentiate from the natural background atmospheric electric field produced by lightning. In this talk I will present evidence for the link between the natural ELF fields and those found in many living organisms, including humans.  Furthermore, recent experiments show links between the ELF fields and photosynthesis in plants.
  • seminar
    Date:
    25 December
    2022
    Sunday
    Hours:
    11:00
    -
    12:00

    RNA-Lipid Nanoparticles 2.0: From Gene Silencing to Genome Editing

    Location: Perlman Chemical Sciences Building
    participants: Prof. Dan Peer
    Laboratory of Precision NanoMedicine, Tel Aviv University

    Abstract

    Accumulating work points out relevant genes and signaling pathways hampered in human disorders as potential candidates for therapeutics. Developing nucleic acid-based tools to manipulate gene expression, such as siRNAs, mRNA and genome editing strategies, open up opportunities for personalized medicine. Yet, although major progress was achieved in developing RNA targeted delivery carriers, mainly by utilizing monoclonal antibodies (mAbs) for targeting, their clinical translation has not occurred. In part because of massive development and production requirements and high batch-to-batch variability of current technologies, which relies on chemical conjugation. Here we present a self-assembled modular platform that enables to construct theoretically unlimited repertoire of RNA targeted carriers. The platform self-assembly is based on a membrane-anchored lipoprotein, incorporated into RNA-loaded novel, unique lipid nanoparticles that interact with the antibody Fc domain. We show that a simple switch of 8 different mAbs, redirects specific uptake of siRNAs by diverse leukocyte subsets in vivo. The platform therapeutic potential is demonstrated in an inflammatory bowel disease model, by targeting colon macrophages to reduce inflammatory symptoms, and in Mantle Cell Lymphoma xenograft model, by targeting cancer cells to induce cell death and improve survival. In addition, I will discuss novel approach for delivering modified mRNA to specific cell types in vivo utilizing this platform. I will also share some data on mRNA vaccines for COVID19 and Finally, I will share new data showing very high efficiency genome editing in glioma and metastatic ovarian cancer. This modular delivery platform can serve as a milestone in turning precision medicine feasible.
  • seminar
    Date:
    21 December
    2022
    Wednesday
    Hours:
    15:00

    Chemical and Biological Physics Guest Seminar

    Location: Perlman Chemical Sciences Building
    participants: Prof David Petrosyan
    IESL, FORTH, Greece

    Abstract

    Atoms in the highly excited Rydberg states possess unique properties, including long lifetimes and huge dipole moments, which facilitate their use in various quantum technology applications. I will discuss recent progress in quantum simulations of many-body physics with strongly-interacting Rydberg atoms and coherent interfaces of Rydberg atoms with superconducting microwave resonators and optical photons, and present some of our results in this research.
  • seminar
    Date:
    20 December
    2022
    Tuesday
    Hours:
    14:00
    -
    15:00

    Extracellular Matrix Mechanics in Disease States

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Joshua M. Grolman
    Materials Science and Engineering Technion - Israel Institute of Technology
  • seminar
    Date:
    18 December
    2022
    Sunday
    Hours:
    14:00
    -
    15:00

    From atomic imaging and functionalizing of inorganic 2D materials to molecular imaging of organic 2D materials

    Location: Perlman Chemical Sciences Building
    participants: Prof. Ute Kaiser
    Ulm University, Materials Science Electron Microscopy

    Abstract

    In this lecture, the theoretical and technical base for atomic imaging of defects in inorganic 2D materials in the low-voltage transmission electron microscope SALVE will be discussed. Atomic defects can significantly change the properties of the material: Using 2D-TMDs and 2D-TMPTs and corresponding heterostructures, this is shown experimentally and verified by corresponding quantum mechanical calculations. We also use the electron beam for the targeted formation of new phases in the inorganic 2D matrix. Since the interaction cross-sections of electron beam and organic 2D materials differ strongly from the inorganic case, we explore highest-resolution imaging conditions for 2D polymers and various 2D MOFs and show that there is a trend towards lower voltage TEM as well. We may conclude that low-voltage TEM and low-dimensional materials are just made for each other.
  • seminar
    Date:
    18 December
    2022
    Sunday
    Hours:
    11:00
    -
    12:00

    Structure and Dynamics of Polyelectrolyte Complex Network under Electric Field

    Location: Perlman Chemical Sciences Building
    participants: Prof. Eyal Zussman
    Dept Mechanical Engineering, Technion

    Abstract

    Electrostatic interactions between polyelectrolyte (PE) charges and dissociated counterions provide PEs with intriguing properties and significantly determine their conformation and dynamics. This research shows how weak PE chains form a global network when they are oppositely charged and how strong electric fields lead to orientational order. The development of controlled drug release and responsive structures is demonstrated by the use of ordered PE with tunable intermolecular interactions.
  • seminar
    Date:
    14 December
    2022
    Wednesday
    Hours:
    11:00
    -
    12:00

    Engineering Imaging Technologies and Discovering Biomarkers to Characterize Disease States

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Barbara S. Smith
    School of Biological and Health Systems Engineering, Arizona State University

    Abstract

    Neurodegenerative diseases are often clinically, genetically, and pathologically heterogeneous. The clinical impact of understanding heterogeneity is perhaps best observed in cancer, where subtype-specificity within diagnoses, prognoses, and treatments have had a critical impact on clinical decision making and patient outcomes. A better understanding of how mechanisms are related to or drive heterogeneity within diseases such as Amyotrophic Lateral Sclerosis (ALS), will have a direct impact on patient outcomes, with a conscious effort to move towards precision medicine and targeted therapeutics for patients, which are urgently needed. For this reason, neuroscientists and oncologists have long aspired to achieve an understanding of the mechanisms governing pathophysiology. Our interdisciplinary work integrates technologies across a wide range of fields to surpass the current barriers in understanding disease pathophysiology. This talk will highlight a series of optical and photoacoustic imaging tools as well as multi-omics analysis that have been developed and studied in Dr. Smith’s lab to address the urgent need for non-invasive cancer detection and the characterization of neurological disorders. Through this work, we aim to develop translational technologies and methodologies to better characterize, understand, and detect disease pathogenesis, beyond current capabilities.
  • seminar
    Date:
    4 December
    2022
    Sunday
    Hours:
    15:00

    Origin of compact exoplanetary systems

    Location: Sussman Family Building for Environmental Sciences
    participants: Raluca Rufu SwRI, Boulder

    Abstract

    One of the most surprising discoveries in exoplanet science has been the existence of compact systems of Earth to super-Earth sized planets. These multi-planet systems have nearly circular, coplanar orbits located at distances of only ∼ 0.01 − 0.1 AU, a region devoid of planets in our Solar System. Although compact systems comprise a large fraction of known exoplanetary systems, their origin remains debated. Common to all prior models of compact system origin is the assumption that infall to the stellar disk ends before planets form. However, there is growing observational, theoretical, and meteoritical evidence of the early growth of mm-sized “pebbles” during the infall phase. We propose that accretion of compact systems occurs during stellar infall. As a cloud core collapses, solids are gradually accumulated in the disk, producing favorable conditions for the formation and survival of close-in planets. A key feature of this model is that the reduced gas-to-solids ratio in the planet accretion region can allow for the formation and survival of compact systems, even with Type-I migration. Accretion within infall-supplied disks has been studied in the context of gas planet satellite origin. Formation models predict that the total mass of the satellite system during this evolution maintains a nearly constant mass ratio ∼10^−4 compared to the host planet’s mass. The maximum mass ratio of compact exoplanetary systems compared to the stellar mass are similar to those of the giant satellite system, suggesting that accretion of compact systems may be similar to regular satellite formation.
  • seminar
    Date:
    1 December
    2022
    Thursday
    Hours:
    14:00
    -
    15:00

    “Investigating the Surface Dynamics of Ions at the Anode-Electrolyte Interface using NMR Spectroscopy”

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Shakked Schwartz
    M.Sc. student of Dr. Michal Leskes

    Abstract

    High-Performance, Rechargeable Li-ion Batteries (LIBs) are key to the global transition from fossil fuels to renewable energy sources. LIBs utilizing lithium metal as the anode are particularly exciting due to their exceptional energy density and redox potential, yet their advancement is hindered by growth of metallic filaments and unstable surface layers. Efficient cationic transport, which is crucial for battery performance, largely depends on the heterogeneous and disordered interphase formed between the anode and the electrolyte during cycling. Directly observing this interphase as well as the dynamic processes involving it is a great challenge. Here we present an approach to elucidate these dynamic processes and correlate them with the corresponding interfacial chemistry, focusing on the first step of cationic transport: surface adsorption. Employing Dark State Exchange Saturation Transfer (DEST) by 7Li NMR, we were able to detect the exchange of Li-ions between the homogenous electrolyte and the heterogeneous surface layer, highlighting the hidden interface between the liquid and solid environments. This enabled determination of the kinetic and energetic binding properties of different surface chemistries, advancing our understanding of cationic transport mechanisms in Li-ion batteries. 
  • seminar
    Date:
    30 November
    2022
    Wednesday
    Hours:
    14:00
    -
    15:00

    Chemical Biology Avenues to Illuminate Chromatin Modifications and Protein-protein Interactions

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Nir Hananya
    Department of Chemistry Princeton University
  • seminar
    Date:
    29 November
    2022
    Tuesday
    Hours:
    14:00

    Chemical and Biological Physics Guest seminar

    Location: Stone Administration Building
    participants: Prof Tommaso Bellini
    Universita degli Studi di Milano

    Abstract

    We introduce a variant of SELEX in-vitro selection to study the evolution of a population of oligonucleotides starting from a seed of random-sequence DNA 50mers (our evolving individuals) and introducing selectivity by an affinity capture gel formed by beads carrying DNA 20mers of fixed sequence that act as targets (our resources). We PCR amplify the captured strands and proceed to the next generation. Because of the simplicity of the process, we could investigate what plays the role of “fitness" in this synthetic evolution process. We find that, across generations, evolution is first driven by the need of binding to the capture gel, while, on a later stages it appear dominated by the emerging of motifs related to inter-individual interactions.
  • seminar
    Date:
    27 November
    2022
    Sunday
    Hours:
    11:00

    Chemical and Biological Physics Guest Seminar

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr Miri Adler
    Yale University

    Abstract

    Our organs and tissues are made of different cell types that communicate with each other in order to achieve joint functions. However, little is known about the universal principles of these interactions. For example, how do cell interactions maintain proper cellular composition, spatial organization and collective division of labor in tissues? And what is the role of these interactions in tissue-level diseases where the healthy balance in the tissue is disrupted such as excess scarring following injury known as fibrosis? In this talk, I will discuss my work in developing theoretical frameworks that explore the collective behavior of cells that emerges from cell-cell communication circuits. I will present work on the cell circuit that controls tissue repair following injury and how it may lead to fibrosis. I will discuss a new approach to explore how cell interactions can be used to provide symmetry breaking and optimal division of labor in tissues, and how this approach can help to interpret complex patterns in real data. I will introduce a new concept in complex networks – network hyper-motifs, where we explore how small recurring patterns (network motifs) are integrated within large networks, and how these larger patterns (hyper-motifs) can give rise to emergent dynamic properties. Finally, I will conclude with future directions that are aimed at revealing principles that unify our understanding of different tissues.
  • seminar
    Date:
    24 November
    2022
    Thursday
    Hours:
    14:00

    Chemical and Biological Chemistry Guest Seminar

    Location: Perlman Chemical Sciences Building
    participants: Dr Dan Gorbonos
    Max Planck Institute of animal behavior

    Abstract

    How animals navigate and perform directional decision making while migrating and foraging, is an open puzzle. We have recently proposed a spin-based model for this process, where each optional target that is presented to the animal is represented by a group of Ising spins, that have all-to-all connectivity, with ferromagnetic intra-group interactions. The inter-group interactions are in the form of a vector dot product, depending on the instantaneous relative, and deformed, angle between the targets. The deformation of the angle in these interactions enhances the effective angular differences for small angles, as was found by fitting data from several animal species. We expose here the rich variety of trajectories predicted by the mean-field solutions of the model, for systems of three and four targets. We find that depending on the arrangement of the targets the trajectories may have an infinite series of self-similar bifurcations, or have a space-filling property. The bifurcations along the trajectories occur on "bifurcation curves'', that determine the overall nature of the trajectories. The angular deformation that was found to fit experimental data, is shown to greatly simplify the trajectories. This work demonstrates the rich space of trajectories that emerge from the model.
  • seminar
    Date:
    24 November
    2022
    Thursday
    Hours:
    11:00
    -
    12:00

    M.Sc thesis defense: "Self-Integrating Memories Based on Guided Nanowires"

    Location: Helen and Milton A. Kimmelman Building
    participants: Omri Ron
    M.Sc student in Prof. Ernesto Joselevich's group

    Abstract

    Neuromorphic computing designs have an important role in the modern ‘big data’ era, as they are suitable for processing large amount of information in short time, eliminating the von Neumann (VN) bottleneck. The neuromorphic hardware, taking its inspiration from the human brain, is designed to be used for artificial intelligence tasks via physical neural networks, such as speech or image recognition, bioinformatics, visual art processing and much more. The memristor (memory + resistor), is one of the promising building blocks for this hardware, as it mimics the behavior of a human synapse, and can be used as an analog non-volatile memory. The memristor has been proven as a viable memory element and has been used for constructing resistive random access memory (RRAM) as a replacement for current VN hardware. However, the mechanism of operation and the conducting bridge formation mechanisms in electrochemical metallization memristors still require further investigation. A planar single-nanowire (NW) based memristor is a good solution for elucidating the mechanism of operation, thanks to the high localization of switching events, allowing in-situ investigation as well as post-process analysis. Our group, which has developed the guided-growth approach to grow guided planar NWs on different substrates, has used this method to integrate guided epitaxial NWs into functional devices such as field-effect transistors (FETs), photodetectors and even address decoders. However, the guided-growth approach has not been used for creating memristors up to date. In this work, I successfully synthesized guided NWs of two metal-oxides on flat and faceted sapphire substrates – ZnO and β-Ga2O3 were successfully grown in the VLS mechanism as surface guided NWs. I successfully grew planar guided β-Ga2O3 NWs on six different sapphire substrates, for the first time as far as we know. We characterized the newly grown β-Ga2O3 NWs with SEM, TEM, EDS and Raman spectroscopy. The monoclinic NWs grew along surprising directions on the flat sapphire surfaces and I demonstrated a new mode of growth – epitaxy favored growth on a faceted surface, when graphoepitaxy is also possible. I created electrochemical metallization memristors with the obtained NWs and successfully demonstrated the effect of resistive switching for β-Ga2O3 guided NW based devices. With the abovementioned achievements, we expanded the guided-growth approach on flat and faceted sapphire surfaces, and opened the opportunity for creating surface guided-NW based neuromorphic hardware.
  • seminar
    Date:
    23 November
    2022
    Wednesday
    Hours:
    11:00
    -
    12:00

    The Role of Active Encapsulation in Perovskite Solar Cells

    Location: Perlman Chemical Sciences Building
    participants: Prof. Shaibal Sarkar
    at Department of Energy Science and Engineering, IIT Bombay

    Abstract

    From a perovskite photovoltaic device standpoint, the Al2O3 ALD can be thought of as a thin film encapsulate to protect the underlined material from the extrinsic entities. However, as per the literature is concerned, the role of Al2O3 ALD in the perovskite photovoltaic devices is much beyond a mare passive component. This raises a severe ambiguity over the choice of surface (or interface) on which ALD needs to be done for optimized device performance, in terms of the device efficiency and stability. In my presentation, I would like to elucidate the characteristic differences between the surface limited and substrate enhanced ALD processes which is important to perovskite devices. The objective here is to discuss a unified correlation between the role of the Al2O3 ALD mechanism with the perovskite device performance by excluding popular overestimated assumption about the conformality on non-ideal surface, like perovskite or organic thin films. In addition, I would like to emphasize on the fact that how the ALD process can be used to passivate the buried interfacial defect and enhancing the VOC, PL and ELQE.
  • seminar
    Date:
    22 November
    2022
    Tuesday
    Hours:
    14:00
    -
    15:00

    Mechanism of virus capsid assembly and disassembly

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Uri Raviv
    Institute of Chemistry The Hebrew University of Jerusalem
  • seminar
    Date:
    22 November
    2022
    Tuesday
    Hours:
    11:00
    -
    12:00

    What is the Science behind Climate Change?

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Peter Rez
    Arizona State University Department of Physics

    Abstract

    Not a day goes by when we don’t hear about the “climate crisis”; some effects are well documented, like the rise in the average global temperature and the shrinking of the polar ice caps. Undoubtedly, carbon dioxide levels in the atmosphere have been increasing, but what does “science” say about the potential consequences? The combination of the atmosphere, oceans, cryosphere and biosphere is the ultimate non-linear coupled complex system. How well do we understand what might happen? In the first part of my talk, I shall review my exploration of the original literature to try and separate out speculation, hypothesis, results of computational models, and most significantly actual observations. In the second part of my talk, I shall discuss what will actually work to reduce carbon dioxide emissions (complete elimination or Net Zero is an impossibility). Although it has become fashionable for governments to impose mandates enshrined in laws, the only laws that matter are the laws of thermodynamics and Ohm’s law.
  • seminar
    Date:
    20 November
    2022
    Sunday
    Hours:
    11:00

    TBA - M. Magaritz Memorial Lecture: Climate Intervention

    Location: Sussman Family Building for Environmental Sciences
    participants: David Fahey
  • seminar
    Date:
    16 November
    2022
    Wednesday
    Hours:
    11:00
    -
    12:00

    “Macrocyclic compounds for green energy device applications: recent progress on boron subnaphthalocyanines and associated hybrids”

    Location: Perlman Chemical Sciences Building
    participants: Prof. Timothy Bender
    Dept. of Chemical Engineering & Applied Chemistry, University of Toronto
  • seminar
    Date:
    15 November
    2022
    Tuesday
    Hours:
    14:00
    -
    15:00

    "Synthetic Nucleic Acid Topology and Their Biological Applications”

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Yossi Weizmann
    Department of Chemistry Ben-Gurion University
  • seminar
    Date:
    15 November
    2022
    Tuesday
    Hours:
    11:00
    -
    12:00

    Redox reactivity of Ar2Ch2 (Ch = S, Se):from fundamentals to application in catalysis

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Inke Siewert
    Georg-August-Universität Göttingen, Germany

    Abstract

    Aromatic dichalcogenides exhibits a rich reductive and oxidative redox chemistry and the one and two electron reductions and oxidations of such Ar2Ch2 species appears at rather mild potentials. The successive 1e–-reductions often have very similar potentials as the one electron process results in the formation of an odd-electron bond, which stabilizes the radical anion, for example in hypothetical Ph2S2•− by about 30 kcal/mol. Inspired by the natural dithiol/disulfide 2H+/2e− couple, we investigated a 2,2′-bipyridine that is equipped with a disulfide/dithiolate unit in the backbone for storing multiple electrons and protons.[2] The synchronized transfer of electrons and protons is a critical step in many chemical and biological transformations. In particular, hydride and H atom transfer reactions are important in, for example, catalytic hydrogenation or small molecule activation reactions relevant to renewable energy storage. We examined in depth the fundamental 2e–, 2e–/2H+ and 1e–/H+ reactivity of the switch depending on the metalation. It appears that the Re compound overcomes the drawback of many metal-free hydride donors, which show a large gap between the first and second reduction process, and detrimental side reactions of the radical intermediate. Furthermore, we applied such Ar2Se2 in the anodic amination and esterification of nonactivated alkenes. Amination and esterfication reactions are of considerable importance since C–N and C–O bond motifs can be found in numerous organic compounds associated with biological, pharmaceutical, or material scientific applications. We developed versatile protocols for the electrochemical functionalization and a detailed kinetic and thermodynamic analysis gave valuable insights into the mechanism of the reaction as well as the impact of, e.g. solvent, additives, on the organocatalysis.
  • seminar
    Date:
    13 November
    2022
    Sunday
    Hours:
    14:00
    -
    15:00

    "Fgf8 dynamics and critical slowing down in somitogenesis"

    Location: Perlman Chemical Sciences Building
    participants: Prof. David Bensimon
    Chemistry and Biochemistry Department, UCLA

    Abstract

    Somitogenesis, the segmentation of the antero-posterior axis in vertebrates, is thought to result from the interactions between a genetic oscillator and a posterior-moving determination wavefront. I will introduce the current state of knowledge of that important stage in the development of vertebrate embryos. Surprisingly while the oscillator period is very sensitive to temperature changes, the size of the segments is not. I shall describe our results pertaining to the importance of the decrease in time of the Fgf8 gradient on the propagation of the wavefront and the observation that the somitogenetic period, embryo growth rate, PSM shortening rate and Fgf8 decay rate all slow down as 1/(T-Tc) with Tc=14.4°C, suggesting that critical slowing may affect the embryo metabolism resulting in a natural compensation of thermal effects on somite size.
  • seminar
    Date:
    13 November
    2022
    Sunday
    Hours:
    11:00

    Targeted observations of transient luminous events from the International Space Station during the ILAN-ES campaign

    Location: Sussman Family Building for Environmental Sciences
    participants: Yoav Yair
  • seminar
    Date:
    9 November
    2022
    Wednesday
    Hours:
    14:00
    -
    15:00

    Mechanistic impact of microsecond oligomerization on minutes/hours aggregation of huntingtin studied by NMR – relevance to potential treatment avenues for Huntington’s disease

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. G. Marius Clore
    NIH Bethesda, Maryland USA
  • seminar
    Date:
    8 November
    2022
    Tuesday
    Hours:
    09:30

    Climate change challenge and innovative approaches - from batteries to agriculture - towards a more sustainable future

    Location: Dolfi and Lola Ebner Auditorium
    participants: Steven Chu
    Stanford University
  • seminar
    Date:
    6 November
    2022
    Sunday
    Hours:
    14:00
    -
    15:00

    Zoom only: VISCOSITY OF DILUTE ELECTROLYTE SOLUTIONS

    Location: Perlman Chemical Sciences Building
    participants: Prof. Phillip Pincus
    Physics and Materials Departments University of California, Santa Barbara

    Abstract

    https://weizmann.zoom.us/j/97641167767?pwd=YURCbjI5VjdJZ2hmWXAwMTVCS1p3UT09 Nearly 100 years ago, Jones and Dole experimentally pointed out a puzzle associated with the incremental modification of the bulk viscosity of water induced by small concentrations of salt. The strange behavior relates to cation specificity. This puzzle remains unsolved. This talk will remind you about this problem and suggest a possible approach. I hope that I can engender some ideas from you.
  • seminar
    Date:
    6 November
    2022
    Sunday
    Hours:
    11:00
    -
    12:00

    Semiclassics: The true origins of the success of density functional theory

    Location: Perlman Chemical Sciences Building
    participants: Prof. Kieron Burke
    Department of Chemistry UC Irvine

    Abstract

    The successes and failures of approximate density functionals are due to their connection with semiclassical expansions. In the semiclassical limit, relative errors in local density approximations vanish. Carefully derived corrections to that limit have been shown to be far more accurate than our usual DFT approximations. I will discuss important new results in our 20-year-long quest to derive density functional approximations as expansions in hbar. These include both a new correction to the expansion of the exchange energy of atoms and an orbital-free calculation with sub-milli-Hartree accuracy. [1] Semiclassical Origins of Density Functionals Elliott, Peter, Lee, Donghyung, Cangi, Attila and Kieron Burke, Phys. Rev. Lett. 100, 256406 (2008). [2] Leading correction to the local density approximation for exchange in large-Z atoms Nathan Argaman, Jeremy Redd, Antonio C. Cancio, and Kieron Burke, Phys. Rev. Lett. 129, 153001 (2022). [3] Orbital-free functional with sub-milliHartree accuracy, Pavel Okun and Kieron Burke, in preparation.
  • seminar
    Date:
    25 October
    2022
    Tuesday
    Hours:
    10:00
    -
    11:00

    PRIMO - A TOOL TO ENGINEER CELLULAR MICROENVIRONMENTS

  • seminar
    Date:
    14 September
    2022
    Wednesday
    Hours:
    11:00
    -
    12:00

    TBA

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. John A. Tainer
    Department of Molecular and Cellular Oncology Division of Basic Science Research The University of Texas MD Anderson Cancer Center Houston, TX
  • seminar
    Date:
    28 August
    2022
    Sunday
    Hours:
    11:00
    -
    12:00

    “Chemistry of layered materials: graphene and beyond”

    Location: Perlman Chemical Sciences Building
    participants: Prof. Zdenek Sofer
    University of Chemistry and Technology, Prague
  • seminar
    Date:
    23 August
    2022
    Tuesday
    Hours:
    11:00
    -
    12:00

    "Ultrafast charge transfer in heterostructures of two-dimensional materials"

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Giulio Cerullo
    Department of Physics, Politecnico di Milano

    Abstract

    Heterostructures (HS) of two-dimensional materials offer unlimited possibilities to design new materials for applications to optoelectronics and photonics. In such HS the electronic structure of the individual layers is well retained because of the weak interlayer van der Waals coupling. Nevertheless, new physical properties and functionalities arise beyond those of their constituent blocks, depending on the type and the stacking sequence of layers. In this presentation we use high time resolution ultrafast transient absorption (TA) and two-dimensional electronic spectroscopy (2DES) to resolve the interlayer charge scattering processes in HS. We first study a WSe2/MoSe2 HS, which displays type II band alignment with a staggered gap, where the valence band maximum and the conduction band minimum are in the same layer. By two-colour pump-probe spectroscopy, we selectively photogenerate intralayer excitons in MoSe2 and observe hole injection in WSe2 on the sub-picosecond timescale, leading to the formation of interlayer excitons (ILX). The temperature dependence of the build-up and decay of interlayer excitons provide insights into the layer coupling mechanisms [1]. By tuning into the ILX emission band, we observe a signal which grows in on a 400 fs timescale, significantly slower than the interlayer charge transfer process. This suggests that photoexcited carriers are not instantaneously converted into the ILX following interlayer scattering, but that rather an intermediate scattering processes take place We then perform 2DES, a method with both high frequency and temporal resolution, on a large-area WS2/MoS2 HS where we unambiguously time resolve both interlayer hole and electron transfer with 34 ± 14 and 69 ± 9 fs time constants, respectively [2]. We simultaneously resolve additional optoelectronic processes including band gap renormalization and intralayer exciton coupling. Finally, we investigate a graphene/WS2 HS where, for excitation well below the bandgap of WS2, we observe the characteristic signal of the A and B excitons of WS2, indicating ultrafast charge transfer from graphene to the semiconductor [3]. The nonlinear excitation fluence dependence of the TA signal reveals that the underlying mechanism is hot electron/hole transfer, whereby a tail the hot Fermi-Dirac carrier distribution in graphene tunnels through the Schottky barrier. Hot electron transfer is promising for the development of broadband and efficient low-dimensional photodetectors. [1] Z. Wang et al., Nano Lett. 21, 2165–2173 (2021). [2] V. Policht et al., Nano Lett. 21, 4738–4743 (2021). [3] C. Trovatello et al., npj 2D Mater Appl 6, 24 (2022).
  • seminar
    Date:
    22 August
    2022
    Monday
    Hours:
    14:00
    -
    15:00

    CANCELED: Chemistry of layered materials: graphene and beyond

    Location: Perlman Chemical Sciences Building
    participants: Prof. Zdenek Sofer
    Univesity of Chemistry and Technology, Prague

    Abstract

    Canceled
  • seminar
    Date:
    17 August
    2022
    Wednesday
    Hours:
    11:00
    -
    12:00

    “Molecular Dopants and other Tools to Control Metal Halide Perovskite Systems”

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Antoine Kahn
    School of Engineering and Applied Science, Princeton
  • seminar
    Date:
    4 August
    2022
    Thursday
    Hours:
    11:00

    Chemical and Biological Physics Guest Seminar

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Alexey Chernikov
    TU Dresden (Technische Universitat Dresden)

    Abstract

    Coexistence of optical and electrical excitations in semiconductors has a long history of research. This scenario typically involves simultaneous presence of Coulomb-bound electron-hole pairs, known as excitons, and free charge carriers. Conceptually similar to related phenomena in the ultra cold atom gases, exciton-carrier mixtures strongly influence the properties of excited semiconductors and their response to external fields. It involves the formation of bound three-particle states known as charged excitons or trions, Fermi polarons, renormalization and screening effects, as well as the Mott-transition in the high-density regime. These phenomena offer fertile ground to merge the realms of optics and transport, motivated by the availability of excitations that are both electrically tunable and couple strongly to light. Van der Waals monolayer semiconductors and layered metal-halide perovskites recently emerged as particularly suitable platforms to study exciton-carrier mixtures due to exceptionally strong Coulomb interactions on the order of many 100’s of meV. In this talk, I will discuss a number of intriguing phenomena associated with coupling of excitons to free charge carriers in these systems. I will present experimental evidence for dressing of excited exciton states by continuously tunable Fermi sea. These quasiparticles are reminiscent of two-electron excitations of the negatively charged hydrogen ion and are subject to autoionization - a unique scattering pathway available for excited states. I will further illustrate the impact of free carriers on the exciton transport revealing non-monotonous density dependence and highly efficient propagation of charged exciton complexes. Finally, I will demonstrate electrically tunable trions in hybrid organic-inorganic semiconductors. These three-particle complexes feature unusually large binding energies combined with substantial mobility at elevated temperatures.
  • seminar
    Date:
    3 August
    2022
    Wednesday
    Hours:
    11:00
    -
    12:00

    Metal Catalyzed Carbonylation Reactions

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Howard Alper
    University of Ottawa

    Abstract

    Transition metal catalyzed carbonylation reactions of a wide range of organic compounds provide entry to some molecules of value to the pharmaceutical, commodity, and petrochemical industries. Examples to be presented include the preparation of indolizine derivatives by palladium-catalyzed oxidative alkoxycarbonylation, the synthesis of N-fused heterocycles via dearomatic carbonylation, the highly regioselective and chemoselective carbonylation of bifunctional organic reactants with haloarenes, styrenes, and alkynes. These transformations were successfully applied to the synthesis of natural products including Avenanthramide A
  • seminar
    Date:
    26 July
    2022
    Tuesday
    Hours:
    11:00
    -
    12:00

    Heterogeneity of electrocatalysts: Insights from molecular electrochemistry

    Location: Perlman Chemical Sciences Building
    participants: Prof. Lior Sepunaru
    Department of Chemistry & Biochemistry, University of California Santa Barbara

    Abstract

    Catalysis is a general process that speeds up the reaction rate without altering the process thermodynamics. It is often essential to study the kinetics of the reaction to infer the mechanism of catalysis, an insight that can help in catalyst design. However, bulk catalysis, and specifically electrocatalysis, cannot capture the inherent heterogeneity of seemingly identical catalysts. This talk aims to provide basic principles behind electrocatalysis and introduce a new way to study electrocatalysts at the single entity level. Together, we will review the latest progress in the field and conclude with future directions that can be applied to the vast majority of catalysts ranging from organic, bio, and inorganic materials.
  • seminar
    Date:
    20 July
    2022
    Wednesday
    Hours:
    14:00
    -
    15:00

    Ph.D thesis: Pushing the envelope of high field DNP-NMR methodology towards functional materials

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Asya Svirinovsky
    ph.D candidate under the supervision of Dr. Michal Leskes

    Abstract

    Functional materials are the main building blocks of advanced technologies based on energy storage and conversion systems essential for our modern life including batteries, solar cells, and heterogeneous catalysis. Improvements in materials performance and development of new materials rely on our ability to obtain structure-function correlation as well as understand degradation processes when the materials are integrated into a device. To this end, advanced analytical tools that can provide information at the atomic level are essential. Solid-state nuclear magnetic resonance (ssNMR) spectroscopy is well suited for this task, especially when equipped with high sensitivity by Magic Angle Spinning - Dynamic Nuclear Polarization (MAS-DNP). However, to date, the majority of materials studied by MAS-DNP were non-reactive and non-conductive materials with DNP from exogenous sources of polarization such as nitroxide radicals. This approach cannot be simply extended to functional materials as the properties that stem from the material’s functionality in the device, including electrical conductivity, chemical reactivity and defects, often pose challenges in the study of the materials by DNP. In this talk I will frame the challenges associated with the application of MAS-DNP to functional materials and describe approaches to address them. Results will be presented from three ubiquitous material systems spanning a range of applications: carbon allotropes, transition metal dichalcogenides (TMDs) and metallic microstructures. We systematically investigated the deleterious effect of materials’ conductivity and formulated means to reduce the effect. We explored the feasibility of utilizing inherent unpaired electrons for endogenous DNP and applied it to probe buried phases in all-solid-state lithium-metal battery and the surface chemistry in carbons. I will show that wealth of information achieved by DNP on various functional materials, can place DNP-NMR as a preferable tool for materials scientists. Our findings are expected to apply to many other systems where functional materials are dominant, making DNP a more general technique.
  • seminar
    Date:
    20 July
    2022
    Wednesday
    Hours:
    11:00
    -
    12:00

    "Adventures in Colloidal Nanocrystal Surface Chemistry"

    Location: Perlman Chemical Sciences Building
    participants: Prof. Richard L. Brutchey
    Department of Chemistry, University of Southern California, Los Angeles

    Abstract

    Colloidal nanocrystals possess high surface area-to-volume ratios; as a result, many nanocrystal properties are heavily influenced by their surfaces. At these surfaces exist a complex interface between the inorganic solid (governed by the crystal structure and particle morphology) and organic ligands. The organic ligands play a key role in controlling nucleation and growth, passivating under-coordinated surface sites, and providing steric stabilization for solvent dispersibility. Depending on the particular application of the nanocrystal, the native organic ligands may then need to be removed or exchanged. We use a complement of NMR spectroscopic techniques to understand the nature of the nanocrystal surface and ligand binding. Then, using principles of inorganic coordination chemistry, we rationally enact ligand exchange reactions on these surfaces to maximize nanocrystal functionality. This talk will briefly discuss the surface chemistry of three different platforms. (1) I will discuss how we experimentally developed an atomistic picture of perovskite nanocrystal surface termination, and then used that information to better understand how common surface treatments can “heal” halide perovskite nanocrystal surfaces. (2) I will discuss how different -donating, L-type ligands were installed on the surface of metal phosphide nanocrystals, and how they affected the hydrogen evolving ability of these electrocatalysts. (3) I will discuss a new strategy for thermally activating metal carbide nanocrystal CO2 reduction catalysts using labile ligands that decompose at significantly lower temperatures than the native ligands. This circumvents issues commonly encountered with high-temperature thermolysis (coking) or acid treatments (etching, poisoning) that are used to activate nanocrystal catalysts.
  • seminar
    Date:
    19 July
    2022
    Tuesday
    Hours:
    12:45
    -
    13:45

    Observing disordered protein ensembles inside the cell

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Shahar Sukenik
    Dept. of Chemistry and Chemical Biology University of California
  • seminar
    Date:
    6 July
    2022
    Wednesday
    Hours:
    11:00
    -
    12:00

    “Aspects of solar cell operation and reliability in High and low dimensions”

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Jean Francois Guillemoles
    Director of CNRS, Institut Photovoltaïque d'Ile-de-France (IPVF) , Paris

    Abstract

    The development of advanced photovoltaic devices, including those that might overcome the single junction efficiency limit, as well as the development of new materials, all rely on advanced characterization methods. Among all the existing methods optically based ones are very well adapted to quantitatively probe optoelectronic properties at any stage. We here present the use of multidimensional imaging techniques that record spatially, spectrally and time resolved luminescence images. We will discuss the benefits (and challenges) of looking into energy conversion systems from high dimensions perspective and those of dimensional reduction for improved intelligibility through some examples, mostly drawn from halide perovskite materials and device. These examples will help visit questions related to efficient transport and conversion in solar cells, as well as questions related to chemical and operational stability of the devices.
  • seminar
    Date:
    30 June
    2022
    Thursday
    Hours:
    11:00
    -
    12:00

    What you always wanted to know about nanoparticles, proteins and biomaterials, but never dared to ask

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Dr. Klaus D. Jandt
    Otto Schott Institute of Materials Research (OSIM) Friedrich Schiller University, Jena

    Abstract

    This lecture presents an overview on major research work of the Fellow’s group in the areas of polymer nanoparticles for drug delivery, control of protein adsorption on materials surfaces and protein nanofibers. In addition, the new excellence graduate school (Research Training Group) RTG 2723: Materials‐Microbe‐Microenvironments: Antimicrobial biomaterials with tailored structures and properties (M‐M‐M) funded by the German Science Foundation will be introduced. Polymer nanoparticles (PNP) became recently exceedingly popular through novel vaccination technologies but have also major potential for fighting inflammation and cancer. These drug release properties of the PNP depend on their structure. Yet, the literature reports little about the structure and the properties of most PNPs, except the chemical composition. The PNP’s crystallinity, thermal and mechanical properties are frequently ignored, even though they may play a key role in the drug delivery properties of the PNPs. Protein adsorption on biomaterials is the first process after implantation and determines much of the fate of the biomaterial, such as cell adhesion, blood coagulation or infection at the implant site. Despite decades of research, only rules of thumb exist to predict protein adsorption behavior. We present nanotechnological approaches to control protein adsorption using nanostructured semicrystalline polymers and crystal facets of TiO2. Selfassembled protein nanofibers consisting of one or more proteins, potentially allow to tailor the properties of biomaterials interfaces and to create bone mimetic structures. Finally, the new DFG‐RTG 2723: Materials‐Microbe‐Microenvironments: Antimicrobial biomaterials with tailored structures and properties (M‐M‐M) in Jena will be introduced. The aim of the RTG is to provide excellent training for approximately 40 international doctoral researchers in antimicrobial biomaterials in interdisciplinary tandem projects, connecting materials science and medical science. The RTG pursues a new strategy by developing antibiotic free biomaterials, where the antimicrobial action is based mainly on physical principles. The new RTG offers ample opportunity for fruitful cooperation and exchange with leading research institutions in Israel.
  • seminar
    Date:
    29 June
    2022
    Wednesday
    Hours:
    11:00
    -
    12:00

    Molecular design of solid catalysts

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Alexander Katz
    University of California, Berkeley

    Abstract

    This colloquium will be divided into two applications parts, dealing with synthesis of supported molecular catalysts and solid catalysts for photoprotection. In the first of these areas, we describe a mechanical approach for stabilizing supported weakly interacting active sites (i.e. those that interact non-covalently with the support) against aggregation and coalescence. We use silica as a prototypical example of a support, and an iridium pair-site catalyst incorporating bridging calixarene ligands as an active site. Atomic-resolution imaging of the Ir centers before and after ethylene-hydrogenation catalysis show the metals resisted aggregation and deactivation, remaining atomically dispersed and accessible for catalysis. When active sites are located at unconfined environments, the rate constants for ethylene hydrogenation are markedly lower compared with confining external-surface pockets [1], in line with prior observations of similar effects in olefin epoxidation catalysis [2,3]. Altogether, these examples represent new opportunities for enhancing reactivity on surfaces by synthetically controlling mechanical features of active site catalyst environments. In the second of these areas, reactive oxygen species (ROS) are associated with several human health pathologies and are invoked in the degradation of natural ecosystems as well as building materials that are used in modern infrastructure (e.g., paints and coatings, polymers, etc). Natural antioxidants such as vitamin E function as stoichiometric reductants (i.e. reaction with ROS synthesizes rancid oils). While enzymes such as superoxide dismutase working in tandem with catalase decompose decompose ROS to H2O and O2 through H2O2 as an intermediate, these enzymes are fragile and costly. Other non-stoichiometric commercial antioxidants that degrade ROS include hindered amine light stabilizers (HALS). Here, we demonstrate that cerium carbonate acts as a degradation catalyst for photogenerated ROS, and describe the performance and characterization of this new catalyst using X-ray photoelectron spectroscopy, and in comparison with HALS and stoichiometric reductants. Our results demonstrate catalytic antioxidant activity of cerium carbonate when dispersed in polymethylmethacrylate polymer. FTIR data demonstrate that a dispersion of 2 wt. % cerium carbonate within the polymer essentially stops degradation by photogenerated ROS, which otherwise cause oxidation of the polymer backbone, in the control polymer lacking cerium carbonate. Experiments with methylene blue dye in aqueous solution demonstrate that cerium carbonate decreases the rate of ROS degradation of dye, in the presence of UV irradiation and air by 16 fold. These effects become even more pronounced (over 600 fold decrease in rate of ROS dye degradation) when cerium carbonate is paired with a photoactive metal oxide. The mechanism involved in this latter case crudely mimics the enzyme tandem sequence referred to above. [1] C. Schöttle, E. Guan, A. Okrut, N. A. Grosso-Giordano, A. Palermo, A. Solovyov, B. C. Gates, A. Katz*, Journal of the American Chemical Society, J. Am. Chem. Soc. 2019, 141, 4010-4015. [2] N. A. Grosso-Giordano, C. Schroeder, A. Okrut, A. Solovyov, C. Schottle, W. Chasse, N. Marinkoyic, H. Koller, S. I. Zones, A. Katz, Journal of the American Chemical Society 2018, 140, 4956-4960. [3] N. A. Grosso-Giordano, A. S. Hoffman, A. Boubnov, D. W. Small, S. R. Bare, S. I. Zones, A. Katz, Journal of the American Chemical Society 2019, 141, 7090-7106. [4] M. K. Mishra, J. Callejas, M. Pacholski, J. Ciston, A. Okrut, A. Van Dyk, D. Barton, J. C. Bohling, A. Katz, ACS Applied Nano Materials 2021, 4, 11, 11590-11600.
  • seminar
    Date:
    28 June
    2022
    Tuesday
    Hours:
    14:00
    -
    15:00

    New methods to extract knowledge on epistasis from experimental evolutionary landscapes

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Dmitry Ivankov
    Center for Molecular and Cellular Biology Skoltech University Russia
  • seminar
    Date:
    21 June
    2022
    Tuesday
    Hours:
    14:00
    -
    15:00

    The love of fluorescent molecules for noble metals: Metal-induced modulation of single molecule fluorescence

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Joerg Enderlein
    Georg-August-University Goettingen, Germany
  • seminar
    Date:
    19 June
    2022
    Sunday
    Hours:
    11:00
    -
    12:00

    Impacts of the June 2021 Heat Dome on Pacific Northwest (USA) Trees and Forests

    Location: Sussman Family Building for Environmental Sciences
    participants: Chris Still
    Oregon State University

    Abstract

    Most of the Pacific Northwest (PNW, USA) and British Columbia experienced extraordinarily high air temperatures during an extreme heat wave event (“heat dome”) in late June of 2021. In many locations, alltime record high air temperatures (Tair) exceeding 40-45 °C were observed. In this talk I will present evidence of the widespread impacts of this extreme heat event. These impacts include foliar damage observed in many locations of this region, along with some tree mortality. Additionally, I will present data from dendrometers and eddy covariance towers in contrasting forest types highlighting the impacts on tree growth and ecosystem-atmosphere CO2, H2O, and energy fluxes. Better understanding the environmental drivers, biophysical and physiological mechanisms, and ecological consequences of heat damage incurred by forests is of broad relevance and societal importance.
  • seminar
    Date:
    15 June
    2022
    Wednesday
    Hours:
    10:00
    -
    11:00

    Zoom M.Sc thesis defense: The Investigation of Low-Temperature Proton Conduction in Rare- Earth- Hydroxides

    participants: Tahel Malka
    under the supervision of Prof. Igor Lubomirsky

    Abstract

    https://weizmann.zoom.us/j/95467631640?pwd=MHZBNThNQlRUeU1CM29kQXZZcGxOdz09 password:864419 Solid oxide fuel cells (SOFCs), especially proton conducting (PC)-based, and electrolyzes (SOEs), operating above 250°C, demonstrate rapid electrode kinetics, but are limited in their long term stability due to thermal stresses related to on/off cycling. Thermal stress could be reduced dramatically, for PC-SOFCs devices operating in the temperature range of 150-250°C, which would still benefit from fast electrode kinetics and would not require Pt-containing catalytic electrodes. However, a proton-conducting ceramic electrolyte, operating below 250°C hasn’t been identified yet. In this work I investigated the synthesis, preparation protocols and properties of La(OH)_3 and La_2 Ce_2 O_7 (LCO50) powder and ceramics to explore their suitability as proton conductors. Preparation of appropriate pellet samples of La(OH)_3 from the synthesized powder requires (i) elimination of the presence of carbonate oxides followed by (ii) hydration of the remaining La2O3 in boiling deionized water. Room temperature compaction of these powders into solid pellet samples requires prolonged dwell uniaxial pressure. Although the primarily protonic conductivity of the compacted sample reached only 3·10-11 S/cm at 90°C and is insufficient for practical applications; the grain boundaries are apparently not blocking, making it attractive to look for dopants that may potentially enhance the low temperature conductivity. Nominally anhydrous LCO50 has an unexpectedly high conductivity 10-11 S/cm at 110 °C, which is probably due to oxygen vacancies. LCO50 undergoes hydration with a large lattice expansion, which combined with low hydration enthalpy (5.2 kJ/mol) restricted compact crack-free sample. Hydration of LCO50 by 7.5% of the maximum possible showed to have non-blocking grain boundaries, and increases the conductivity by an order of magnitude, which has to be attributed to protonic conduction. Findings describe in this work, point that both investigated materials are promising candidates for further studies as proton conductors.
  • seminar
    Date:
    14 June
    2022
    Tuesday
    Hours:
    14:00
    -
    15:00

    Deep Learning Methods Reveal Structural Mechanisms of Protein-DNA Readout

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Remo Rohs
    The Department of Quantitative and Computational Biology University of Southern California
  • seminar
    Date:
    12 June
    2022
    Sunday
    Hours:
    11:00
    -
    12:00

    Biogeochemical cycling in subsurface systems

    Location: Sussman Family Building for Environmental Sciences
    participants: Dr. Maya Engel
    SLAC National Lab Stanford University

    Abstract

    Subsurface systems, such as alluvial aquifers and soils, store and govern the quality of groundwater by sustaining a unique balance of biogeochemical and hydrological processes. The complex characteristics of subsurface systems are demonstrated in both spatial and compositional sediment heterogeneities that ultimately control the rate and extent of elemental cycling. Different redox environments commonly form within the subsurface and may largely influence these cycles. Heavy metals, occurring naturally (geogenic) or as anthropogenic contaminants, are particularly sensitive to varying redox conditions, even if they are not directly redox active. In this seminar, I will show how sediment hotspots and interfaces influence elemental cycling, contaminant attenuation, and groundwater quality. I will present examples of how an alluvial aquifer system exhibiting redox heterogeneities may influence heavy metal mobility by preferential retention in fine-grained sediment lenses embedded within the coarse aquifer. Several mechanisms contribute to the retention in fine-grained sediments, and we also observe a significant impact of nitrate-rich conditions on the extent and phases of metal retention. Further, I will share our findings on the dynamic and unique composition of iron-rich colloids, detected in reducing zones of a floodplain subsurface. Our results demonstrate the presence of partially oxidized iron rich colloids in otherwise reducing conditions, thanks to a protective organic-silicon coating. The lifecycle and composition of these colloids may have direct effects on element cycling as they may serve as vectors for the transport of nutrients and organic matter into groundwater and surface water recipients. Lastly, I will present my future research visions, in a lab devoted to the study of biogeochemical heterogeneity and coupled elemental cycling under dynamic conditions.
  • seminar
    Date:
    7 June
    2022
    Tuesday
    Hours:
    14:00
    -
    15:00

    On discovery and sensitivity in (photo)catalysis

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Frank Glorius
    University of Münster, Germany

    Abstract

    Catalysis is a key technology, since it allows for increased levels of selectivity and efficacy of chemical transformations. While significant progress can be made by rational design or engineered step-by-step improvements, many pressing challenges in the field require the discovery of new and formerly unexpected results. Arguably, the question “How to discover?” is at the heart of the scientific process. In this talk, (smart) screening strategies for accelerated discovery and improved reproducibility will be presented, together with new photocatalytic transformations. In addition, two other exciting areas will be addressed: N-heterocyclic carbenes (NHCs) are powerful ligands in catalysis due to their strong electron-donating properties and their ability to form very stable bonds to transition metals. In addition, they can stabilize and modify nanoparticles or flat metals surfaces, outperforming established phosphine or thiol ligands regarding structural flexibility, electron-donating properties and stability. Current research is highly interdisciplinary and focusses on the basic understanding of the binding mode, mobility and the elucidation of the impact on the surface properties. Exciting applications in materials science, heterogeneous catalysts and beyond are within reach. Biological membranes and their constituents are some of the most important and fundamental building blocks of life. However, their exact role in many essential cellular processes as well as in the development of diseases such as cancer or Alzheimer's is still not very well understood. Thus, we design, synthesize and evaluate imidazolium-based lipid analogs that can integrate into biological membranes and can be used as probes for live cell imaging or to manipulate membranes.
  • seminar
    Date:
    7 June
    2022
    Tuesday
    Hours:
    11:00
    -
    12:00

    RNA and Protein: A Match made in the Hadean

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Loren D. Williams
    Center for the Origins of Life School of Chemistry and Biochemistry Georgia Tech, Atlanta
  • seminar
    Date:
    2 June
    2022
    Thursday
    Hours:
    14:00
    -
    15:00

    Emerging paradigms in G protein coupled receptors (GPCRs) signaling and their implications for drug discovery

    Location: Nella and Leon Benoziyo Building for Biological Sciences
    participants: Prof. Michel Bouvier
    Institute for Research in Immunology and Cancer (IRIC) of the Université de Montréal (UdeM)
  • seminar
    Date:
    31 May
    2022
    Tuesday
    Hours:
    14:00
    -
    15:00

    Integrated microfluidic tools for improving biological research and medical diagnostics

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Doron Gerber
    Faculty of Life Science Bar-Ilan University
  • seminar
    Date:
    30 May
    2022
    Monday
    Hours:
    11:00
    -
    12:00

    Neutralizing antibodies against pathogenic viruses

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: KENDREW LECTURE: Prof. Pamela Bjorkman
    California Institute of Technology
  • seminar
    Date:
    29 May
    2022
    Sunday
    Hours:
    11:00

    LESSONS FROM THE DEAD SEA, THE CLOSEST MODERN ANALOG FOR DEEP EVAPORITIC BASINS

    participants: Nadav Lensky
    Geological survey of Israel

    Abstract

    Thick halite sequences are common in the Earth’s geologic record; they were accumulated in deep perennial hypersaline water bodies, saturated to halite and subjected to negative water balance. For decades, evaporites research gained insights from exploring modern shallow hypersaline environments, including the relations between the hydroclimatic forcing and the deposited halite layers. However, there is a knowledge gap in understanding limnological controls on accreted halite sequences in deep water bodies. Such water bodies rarely exist today on Earth, but were common through Earth geological history. The Dead Sea is currently the closest and probably the only modern analog for such environments. Recently, based on direct field measurements, laboratory experiments, direct numerical simulations, and sedimentological investigation, we have shown that there are fundamental differences between deposition at deep basins versus shallow basins, specifically in the seasonal to multi-annual scales and variations of halite solubility with depth. We have found that during the dry summer the epilimnion is warmer, saltier and undersaturated to halite, and that double diffusion flux delivers dissolved salt from the epilimnion into the hypolimnion, resulting in the continuously supersaturated hypolimnion and seasonally undersaturated epilimnion. Thus the stratified structure of the lake’s water column results in focusing of halite deposits into the deep parts of the basin and thinned deposits, or entirely dissolved, in the marginal parts. We further explore the role of laterally variable hydroclimatic conditions to the spatiotemporal dynamics of evaporitic deposits in a deep hypersaline waterbody. We focus on the role of diluted buoyant plume, overlaying part of the Dead Sea surface that laterally spreads from freshwater inflow. The lateral surface salinity variations results in lateral variations in evaporation, double diffusion fluxes, and hence evaporitic layer thickness. These can contribute to the study of the depositional environments of halite units throughout the geological record, following the concept of “the present as key to the past”. At the end of the talk, I will share some management ideas regarding the future of the Dead Sea.
  • seminar
    Date:
    26 May
    2022
    Thursday
    Hours:
    11:30
    -
    12:30

    Chaperoning protein aggregation diseases

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Stefan Rudiger
    Bijvoet Center for Biomolecular Research Utrecht University
  • seminar
    Date:
    26 May
    2022
    Thursday
    Hours:
    11:00
    -
    12:00

    “Modeling Photo and Bias Induced Electron transfer and transport. An ab-initio perspective on kinetics”

    Location: Perlman Chemical Sciences Building
    participants: Prof. Barry Dunietz
    Dept. Chemistry and Biochemistry, Kent State University, OH

    Abstract

    Charge transfer and transport processes through molecular interfaces are ubiquitous and of a crucial role in determining functionality of biological systems and in enabling energy conversion applications. We study computationally such processes to understand structure-function relationships at the molecular level. We will discuss studies in the following two primary fields: (1) Photovoltaic and charge transfer properties of organic semiconductors materials. (2) Charge transport through voltage-biased molecular scale bridges. Importantly we establish predictive computational scheme that addresses key challenges. Our studies are employed in conjunction with experimental efforts to design materials and applications that control and tune relevant physical properties
  • seminar
    Date:
    24 May
    2022
    Tuesday
    Hours:
    14:00
    -
    15:00

    Real-time monitoring of replication fork progression in single live cells

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Amir Aharoni
    Dept. of Life Sciences Ben-Gurion University
  • seminar
    Date:
    22 May
    2022
    Sunday
    Hours:
    11:00
    -
    12:00

    Chemical and Biological Physics Guest Seminar

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof Dave Waldeck
    University of Pittsburgh
  • seminar
    Date:
    22 May
    2022
    Sunday
    Hours:
    11:00
    -
    12:00

    Chemical and Biological Physics Guest Seminar

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof Dave Waldeck
    University of Pittsburgh
  • seminar
    Date:
    19 May
    2022
    Thursday
    Hours:
    15:00
    -
    16:00

    Chemical and Biological Physics Guest Seminar

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Latha Venkataraman
    Columbia University

    Abstract

    Over the past decade, there has been tremendous progress in the measurement, modeling and understanding of structure-function relationships in single molecule circuits. Experimental techniques for reliable and reproducible single molecule junction measurements have led, in part, to this progress. In particular, the scanning tunneling microscope-based break-junction technique has enabled rapid, sequential measurement of large numbers of nanoscale junctions allowing a statistical analysis to readily distinguish reproducible characteristics. Although the break-junction technique is mostly used to measure electronic properties of single-molecule circuits, in this talk, I will demonstrate its versatile uses to understand both physical and chemical phenomena with single-molecule precision. I will discuss some recent experimental and analysis aimed at understanding quantum interference in single-molecule junctions. I will then show an example where molecular structure can be designed to utilize interference effects to create a highly non-linear device. Finally, I will discuss some new areas of research aiming to demonstrate that electric fields can catalyze chemical reactions.
  • seminar
    Date:
    18 May
    2022
    Wednesday
    Hours:
    14:00

    Chemical and Biological Physics Special Seminar

    Location: Perlman Chemical Sciences Building
    participants: Dmitrii E. Makarov
    Department of Chemistry and Oden Institute for Computational Engineering and Sciences University of Texas at Austin

    Abstract

    The mathematical analogy between information and thermodynamical entropy has recently led to promising developments in chemistry and physics, and information theory tools are increasingly important in chemical and biological data analysis. In this talk I will describe a few of our ideas at the intersection of physical chemistry, information theory, and computer science, with the focus on single-molecule data analysis. Single-molecule experimental studies have opened a new window into the elementary biochemical steps, function of molecular machines, and cellular phenomena. The information contained in single-molecule trajectories is however often underutilized in that oversimplified models such as one-dimensional diffusion or one-dimensional random walk are used to interpret experimental data. I will show that much finer details of single-molecule dynamics, such as conformational memory and static disorder, can be deduced from an analysis that is similar to Shannon’s analysis of printed English; in particular, this method relates conformational memory to the information-theoretical compressibility of single-molecule signals.
  • seminar
    Date:
    17 May
    2022
    Tuesday
    Hours:
    14:00
    -
    15:00

    A Link Between Mitochondrial Metabolism and Ca2+ Signaling or How Coffee Enhances Learning

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Israel Sekler
    The Dept. of Physiology and Cell Biology Faculty of Health Sciences Ben-Gurion University of the Negev
  • seminar
    Date:
    17 May
    2022
    Tuesday
    Hours:
    11:00

    TBA

    participants: Avishai Abu
    The Hebrew University of Jerusalem
  • seminar
    Date:
    16 May
    2022
    Monday
    Hours:
    11:00
    -
    12:00

    Atomically Precise Chemical, Physical, Electronic, and Spin Contacts

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Paul S. Weiss
    California NanoSystems Institute and Departments of Chemistry & Biochemistry, Bioengineering, and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA

    Abstract

    One of the key advances in nanoscience and nanotechnology has been our increasing ability to reach the limits of atomically precise structures. By having developed the “eyes” to see, to record spectra, and to measure function at the nanoscale, we have been able to fabricate structures with precision as well as to understand the important and intrinsic heterogeneity of function found in these assemblies. The physical, electronic, mechanical, and chemical connections that materials make to one another and to the outside world are critical. Just as the properties and applications of conventional semiconductor devices depend on these contacts, so do nanomaterials, many nanoscale measurements, and devices of the future. We discuss the important roles that these contacts can play in preserving key transport and other properties. Initial nanoscale connections and measurements guide the path to future opportunities and challenges ahead. Band alignment and minimally disruptive connections are both targets and can be characterized in both experiment and theory. I discuss our initial forays into this area in a number of materials systems.
  • seminar
    Date:
    15 May
    2022
    Sunday
    Hours:
    12:00
    -
    13:00

    Designing multifunctional molecular crystalline materials

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Luca Catalano
    Laboratory of Polymer Chemistry, Université libre de Bruxelles

    Abstract

    Molecular crystals are supramolecules “par excellence"1 as they are macroscopic objects composed by millions of molecules periodically disposed and held together by non-covalent interactions with specific physico-chemical properties dictated by their architectures. This offers a vibrant solid-state chemistry playground to build organic solids with tailored functionalities, such as novel luminescent materials,2 solid-state molecular machines,3 and multicomponent crystals with complex topologies.4 The inherent dynamic nature of the weak intermolecular forces that are driving organic crystals self-assembly is also conferring adaptive responsiveness, e.g., mechanical reconfiguration and shape-memory effect, to this class of materials making them ideal building blocks for the design and synthesis of multifunctional crystalline systems that can be exploited as actuators, flexible single-crystalline optoelectronic devices, and self-healing materials.5
  • seminar
    Date:
    8 May
    2022
    Sunday
    Hours:
    11:00

    TBA

    participants: Nili Harnik
    Tel Aviv University
  • seminar
    Date:
    3 May
    2022
    Tuesday
    Hours:
    14:00
    -
    15:00

    Beyond NGS: Single-molecule epigenomics

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Yuval Ebenstein
    School of Chemistry Tel-Aviv University
  • seminar
    Date:
    3 May
    2022
    Tuesday
    Hours:
    11:00

    TBA

    participants: Mathew Henry
  • seminar
    Date:
    28 April
    2022
    Thursday
    Hours:
    11:00
    -
    12:00

    “Spin-orbit coupling and Kondo resonance in Co adatom on Cu(100) surface: DFT+ED study”

    Location: Perlman Chemical Sciences Building
    participants: Prof. Alexander B. Shick
    Institute of Physics, the Czech Academy of Science, Prague

    Abstract

    The studies of magnetic atoms adsorbed on non-magnetic surfaces provide a fundamental insights into the quantum many-body phenomena at the nanoscale. They imprint non-trivial signatures in STM measurements, and can serve as a prototype for potential applications in quantum information technology. Our work aims at the investigation of the electronic structure, spin and orbital magnetic character for the Co adatom on the top of Cu(100) surface. We make use of DFT combined with exact diagonalization of the multi-orbital Anderson impurity model, including the spin-orbit coupling. For the Co atom d-shell occupation nd=8, a singlet many-body ground state and Kondo resonance are found, when the spin-orbit coupling is included in the calculations. The differential conductance is evaluated in a good agreement with the STM measurements. This comparison is the most direct way to demonstrate the validity of our theoretical approximation. Our results illustrate the very essential role which the spin-orbit coupling is playing in a formation of Kondo singlet for the multi-orbital impurity in low dimensions.
  • seminar
    Date:
    26 April
    2022
    Tuesday
    Hours:
    11:00

    TBA

    participants: Georg Wohlfahrt
    University of Innsbruck Department of Ecology
  • seminar
    Date:
    26 April
    2022
    Tuesday
    Hours:
    11:00
    -
    12:00

    Self-assembling structure and function using equilibrium and non-equilibrium statistical mechanics

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr, Matan Ya Ben Zion
    School of Physics, TAU

    Abstract

    Self-assembly and self-organization are two big challenges in the natural sciences. What are the rules governing the emergence of greater structures from unassuming elements? Does statistical-mechanics restrict their complexity? Biochemical processes can shape highly specific structures and function on the macro-scale using only molecular information. Although stereochemistry has been a central focus of molecular sciences since Pasteur, its synthetic province has been restricted to the nanometric scale. In my talk, I will describe how to propagate molecular information to self-assemble free-form architectures on the micron-scale and beyond. These architectures are a thousand times greater than their constituent molecules yet have a preprogrammed geometry and chirality. I will then show how to animate such synthetic microstructures into bacteria-like micro-swimmers. Previous artificial microswimmers relied on an external chemical fuel to drive their propulsion which restricted their operational concentration as they competed locally over fuel. I will demonstrate how to use material science and physical chemistry to self-assemble fuel-free micro-swimmers that are driven solely by light. The fuel independence allows the swimmers to stay active even at high densities, where they form turbulent flow structures (previously seen in living fluids), and cooperate to perform a greater task.
  • seminar
    Date:
    14 April
    2022
    Thursday
    Hours:
    13:30
    -
    14:30

    Probing single protein substrates within the chaperones ClpB and GroEL-ES

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Sander Tans
    Dept. of Bionanoscience Delft University of Technology The Netherlands
  • seminar
    Date:
    12 April
    2022
    Tuesday
    Hours:
    14:00
    -
    15:00

    Disaggregation of amyloid fibres by the human HSP70 chaperone machinery

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Anne Wentink
    Institute of Chemistry Leiden University Netherlands
  • seminar
    Date:
    12 April
    2022
    Tuesday
    Hours:
    11:00
    -
    13:00

    Ph.D thesis: “Structure and properties of naturally occurring materials from first principles.”

    Location: Perlman Chemical Sciences Building
    participants: Margarita Shepelenko
    under the supevision of Prof. Leeor Kronik
  • seminar
    Date:
    5 April
    2022
    Tuesday
    Hours:
    14:00
    -
    15:00

    The Impact of DNA damages on Protein-DNA Interactions

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Ariel Afek
    Dept. of Chemical and Structural Biology Weizmann Institute
  • seminar
    Date:
    27 March
    2022
    Sunday
    Hours:
    11:00

    Decadal Climate Predictions Using Sequential Learning Algorithms

    participants: Golan Bel
    Ben-Gurion University of the Negev

    Abstract

    Decadal Climate Predictions Using Sequential Learning Algorithms Ensembles of climate models are commonly used to improve climate predictions and assess the uncertainties associated with them. Weighting the models according to their performances holds the promise of further improving their predictions. Using an ensemble of climate model simulations from the CMIP5 decadal experiments, we quantified the total uncertainty associated with these predictions and the relative importance of model and internal uncertainties. Sequential learning algorithms (SLAs) were used to reduce the forecast errors and reduce the model uncertainties. The reliability of the SLA predictions was also tested, and the advantages and limitations of the different performance measures are discussed. The spatial distribution of the SLAs performance showed that they are skillful and better than the other forecasting methods over large continuous regions. This finding suggests that, despite the fact that each of the ensemble models is not skillful, the models were able to capture some physical processes that resulted in deviations from the climatology and that the SLAs enabled the extraction of this additional information. If time permits I will also present a method for estimating the uncertainties associated with ensemble predictions and demonstrate the resulting improved reliability. References: 1. Improvement of climate predictions and reduction of their uncertainties using learning algorithms, Atmospheric Chemistry and Physics 15, 8631-8641 (2015). 2. Decadal climate predictions using sequential learning algorithms, Journal of Climate 29, 3787-3809 (2016). 3. The contribution of internal and model variabilities to the uncertainty in CMIP5 decadal climate predictions, Climate Dynamics 49, 3221 (2017). 4. Quantifying the uncertainties in an ensemble of decadal climate predictions. Journal of Geophysical Research: Atmospheres 122, 13,191–13,200 (2017). 5. Learning algorithms allow for improved reliability and accuracy of global mean surface temperature projections. Nature Communications 11, 451 (2020).
  • seminar
    Date:
    20 March
    2022
    Sunday
    Hours:
    11:00

    Four disruptive technologies that are revolutionizing sensing of the oceans

    Location: Sussman Family Building for Environmental Sciences
    participants: Emmanuel Boss

    Abstract

    The maker movement (cheap electronics + sharing), automated microscopy, autonomous platforms and small footprint satellites have been revolutionizing oceanography, opening a variety of new avenues for research and requiring a different education model. In this talk I will summarize a few activities my lab has been involved in that are associated with these disruptive technologies and why I am very optimistic for the future of our field in the coming years.
  • seminar
    Date:
    14 March
    2022
    Monday
    Hours:
    10:00
    -
    11:00

    Ph.D thesis defense: Zoom: "Polymer beads as interfacial obstacles in fibre-reinforced composites"

    participants: Carol Rodricks
    under the supervision of Prof. Daniel Wagner

    Abstract

    Zoom Link: https://weizmann.zoom.us/j/93495966390?pwd=T3hDNXY1WFh6bFpIbDh3OEFxZlcwZz09 The fibre-matrix interface plays a vital role in the overall mechanical behaviour of a fibre-reinforced composite, but the classical approach to improving the interface through chemical sizing is limited by material properties. Achieving a simultaneous improvement in strength and toughness in a composite is a particular challenge since these properties are mutually exclusive, and the chemical modification of the interface often results in one property being improved at the expense of the other. In contrast, the geometrical modification of the fibre-matrix interface to allow for mechanisms such as mechanical interlocking of components is a promising approach to resolving this challenge. This study explores a novel type of topographical obstacle – polymer droplets at the fibre-matrix interface. Discrete epoxy droplets are deposited onto glass fibres and embedded in an epoxy matrix to form model composites. The effect of the interfacial epoxy droplets is investigated using single fibre experiments.
  • seminar
    Date:
    8 March
    2022
    Tuesday
    Hours:
    14:00
    -
    15:00

    Chromatin Transactions, One Molecule at a Time

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Prof. Ariel Kaplan
    Faculty of Biology Technion
  • seminar
    Date:
    8 March
    2022
    Tuesday
    Hours:
    11:00

    Stratosphere-troposphere coupling: from wave-mean flow feedbacks to sub-seasonal predictability

    participants: Thomas Birner

    Abstract

    It is by now well established that certain stratospheric flow configurations may alter tropospheric dynamical variability. Such flow configurations include the aftermath of sudden stratospheric warming events (SSWs) or strong polar vortex events (SPVs). Although the detailed mechanisms behind this stratosphere-troposphere coupling remain elusive, most aspects of it are well-known. For example, the coupling involves feedbacks between upward propagating planetary waves of tropospheric origin and the mean flow, the tropospheric response involves synoptic-scale eddy feedbacks, SSWs tend to project onto negative anomalies of the Arctic and North-Atlantic Oscillation (AO, NAO), whereas SPVs tend to project onto positive anomalies of the AO and NAO. Here I will highlight some recent results on 1) the potential role of a planetary wave source near the tropopause in troposphere-stratosphere coupling, 2) the stratospheric influence on the evolution of baroclinically unstable waves during their non-linear decay phase, 3) the improved quantification of the stratospheric modulation of AO extremes from extended-range ensemble forecasts.
  • seminar
    Date:
    8 March
    2022
    Tuesday
    Hours:
    10:00
    -
    11:00

    M.Sc thesis defense: "Data-Driven Force Fields for Large Scale Molecular Dynamics Simulations of Halide Perovskites"

    Location: Perlman Chemical Sciences Building
    participants: Oz Yosef Mendelsohn

    Abstract

    Zoom Link: https://weizmann.zoom.us/j/99290579488?pwd=cUIyV05SMUQ0VDErNUtma1RTL3BIQT09 In the last decade, halide perovskites (HaPs) have developed as promising new materials for a wide range of optoelectronic applications, notably solar energy conversion. Although their technology has advanced rapidly towards high solar energy conversion efficiency and advantageous optoelectronic properties, many of their properties are still largely unknown from a basic scientific standpoint. Due to the highly dynamical nature of HaPs, one of the main avenues for basic science research is the use of molecular dynamics (MD) simulations, which provide a full atomistic picture of those materials. One of the main limiting factors for such analysis is the time scale of the MD simulation. Because of the complexity of the HaP system, classical force field approaches do not yield satisfactory results and the most widely used force calculation approach is based on first-principles, namely on density functional theory (DFT). In recent years, a new type of force calculation approach has emerged, which is machine learned force fields (MLFF). These methods are based on machine learning (ML) algorithms. Their wide spread use is enabled by the ever-increasing computational power and by the availability of large-scale shared repositories of scientific data. Here, we have applied one MLFF algorithm, known as domain machine learning (GDML). After training a MLFF based on the GDML model, we observed that the MLFF fails in a dynamical setting while still showing low testing error. This has been found to be due to lack of full coverage of the simulation phase space. To address this issue, we have suggested the hybrid temperature ensemble (HTE) approach, where we create rare events that are training samples on the edge of the phase space. We achieve this by combing MD trajectories from a range of temperatures to a single dataset. The MLFF model, trained on the HTE dataset, showed increasing accuracy during the training process, while being dynamically stable for a long duration of MD simulation. The trained MLFF model also exhibited high accuracy for long-term simulations, showing remaining errors of the same magnitude of inherent errors in DFT calculation.
  • seminar
    Date:
    1 March
    2022
    Tuesday
    Hours:
    14:00
    -
    15:00

    Reversible amyloids, condensates, autoinhibition and membrane interactions of human ALIX

    participants: Dr. Lalit Deshmukh
    Dept. of Chemistry and Biochemistry University of California San Diego, USA
  • seminar
    Date:
    27 February
    2022
    Sunday
    Hours:
    11:00
    -
    12:00

    "Electrified Addition and Subtraction of H2 to Simplify Synthesis"

    Location: Gerhard M.J. Schmidt Lecture Hall
    participants: Dr. Samer Gnaim
    Beckman Center for Chemical Sciences The Scripps Research Institute

    Abstract

    Methodologies that rely on the addition and removal of molecular hydrogen from organic compounds are one of the most oft-employed transformations in modern organic chemistry, representing a highly relevant tactic in synthesis. Despite their overall simplicity, organic chemists are still pursuing sustainable and scalable processes for such transformations. In this regard, electrochemical techniques have long been heralded for their innate sustainability as efficient methods to perform redox reactions. In our first report, we discovered a new oxidative electrochemical process for the a,b-desaturation of carbonyl functionalities. The described desaturation method introduces a direct pathway to desaturated ketones, esters, lactams and aldehydes simply from the corresponding enol silanes/phosphates, and electricity as the primary reagent. This electrochemically driven desaturation exhibits high functional group tolerance, is easily scalable (1–100 g), and can be predictably implemented into synthetic pathways using experimentally or computationally derived NMR shifts. Our second report demonstrated the reductive electrochemical cobalt-hydride generation for synthetic organic applications inspired by the well-established cobalt-catalyzed hydrogen evolution chemistry. We have developed a silane- and peroxide-free electrochemical cobalthydride generation for formal hydrogen atom transfer reactions reliant on the combination of a simple proton source and electricity as the hydride surrogate. Thus, a versatile range of tunable reactivities involving alkenes and alkynes can be realized with unmatched efficiency and chemoselectivity, such as isomerization, selective E/Z alkyne reduction, hydroarylation, hydropyridination, strained ring expansion, and hydro-Giese.
  • seminar
    Date:
    27 February
    2022
    Sunday
    Hours:
    11:00

    Sediment geochemistry in large lakes, and what it can tell us about the ancient oceans

    participants: Sergei Katsev
    University of Minnesota, Duluth

    Abstract

    The Great Lakes of the Earth are freshwater seas, and many of the geochemical processes that take place in their bottom sediments parallel those that happen in marine environments. The conditions, however, are different enough to significantly modify the geochemical cycles of key elements. By analyzing those differences, we can not only understand the functioning of the planet's largest freshwater ecosystems, but can also gain insight into the elemental cycling (C, N, P, S...) in the oceans during the past geological epochs.
  • seminar
    Date:
    22 February
    2022
    Tuesday
    Hours:
    14:00
    -
    15:00

    Bringing Nucleic Acid Structures to Life through Structural Dynamics

    participants: Prof. Hashim Al-Hashimi
    Department of Biochemistry Duke University School of Medicine Durham, NC, USA
  • seminar
    Date:
    20 February
    2022
    Sunday
    Hours:
    11:00
    -
    12:00

    Reduced Rainfall in Future Heavy Precipitation Events Related to Contracted Rain Area Despite Increased Rain Rate

    Location: Sussman Family Building for Environmental Sciences
    participants: Moshe (Koko) Armon
    The Hebrew University
  • seminar
    Date:
    15 February
    2022
    Tuesday
    Hours:
    14:00
    -
    15:00

    Visualizing supercoiled DNA structure and interactions with base-pair resolution

    participants: Dr. Alice L.B. Pyne
    Dept. of Materials Science and Engineering University of Sheffield, UK
  • seminar
    Date:
    13 February
    2022
    Sunday
    Hours:
    16:00
    -
    17:00

    Ph.D thesis defense:" Advancing the optimally-tuned range-separated hybrid approach"

    participants: Georgia Prokopiou
    Ph.D student under the supervision of Prof. Leeor Kronik

    Abstract

    Zoom Link: https://weizmann.zoom.us/j/95952232097?pwd=OW9SL2JlNkNYQVJ1cW5FT05HcEh2QT09 The optimally-tuned range separated hybrid (OT-RSH) functional is a non-empirical method within density functional theory, which is known to yield accurate fundamental gaps for a variety of systems. Here we extend its applicability to magnetic resonance parameters, enhance its accuracy by designing OT-RSH based double-hybrid functionals, and increase its precision for solid-state calculations by designing and generating RSH pseudopotentials.
  • seminar
    Date:
    13 February
    2022
    Sunday
    Hours:
    11:00

    Distributed views across media: From space to ocean-depths

    participants: Yoav Schechner
    Technion

    Abstract

    By economy of scale, imaging sensors can now be deployed densely and operated in a coordinated manner at large numbers in space, air, underwater and on the ground. Such distributed imaging systems enable multi-view setups across heterogeneous media of importance to geoscience. These create new observation modes. One outcome is 4D volumetric spatiotemporal recovery of scatterers in the atmosphere, specifically cloud content (the core of the CloudCT space mission). This is in addition to computed tomography of underwater sediment suspension and atmospheric turbulence distributions. We describe several such systems - demonstrated in the field, including both distributed imaging and the basis of the algorithms to analyze the data.
  • seminar
    Date:
    8 February
    2022
    Tuesday
    Hours:
    11:00

    Amplified warming of extreme temperatures over tropical land

    participants: Michael P. Byrne
    Lecturer in Earth & Environmental Sciences – University of St Andrews Marie Skłodowska-Curie Research Fellow – University of Oxford

    Abstract

    Extreme temperatures have warmed substantially over recent decades and are expected to continue warming in response to future climate change. Warming of extreme temperatures is projected to be amplified over land, with severe implications for human health, wildfire risk and food production. Using simulations from coupled climate models, I show that hot days over tropical land warm substantially more than the average day. For example, warming of the hottest 5% of land days is a factor of 1.2 larger than the time-mean warming averaged across models. The climate-change response of extreme temperatures over tropical land is interpreted using a theory based on convective coupling and the weak temperature gradient approximation. According to the theory, warming is amplified for hot land days because those days are dry: this is termed the “drier get hotter” mechanism. Changes in near-surface relative humidity further increase tropical land warming, with decreases in land relative humidity particularly important. The theory advances physical understanding of the tropical climate and highlights climatological land-surface dryness as a key factor determining how extreme temperatures respond to climate change.
  • seminar
    Date:
    7 February
    2022
    Monday
    Hours:
    11:00
    -
    12:00

    Zoom: "Templating Silk Self-assembly with Metal Nanoparticles"

    participants: Daniel Hervitz
    M.Sc student under the supervision of Dr. Ulyana Shimanovich

    Abstract

    Zoom Link: https://weizmann.zoom.us/j/97777492731?pwd=YXZDR0lqYUtMbHVidUlIWkl2TGxjdz09 Protein-metal interactions play an important regulatory role in the modulation of protein folding and in enabling the “correct” biological function. In material science, protein self-assembly and metal-protein interaction have been utilized for the generation of multifunctional supramolecular structures beneficial for bio-oriented applications, including biosensing, drug delivery, antibacterial activity, and many more. Even though, the nature and the mechanisms of metal-protein interaction have been extensively studied and utilized for the functionalization of protein-based materials, mainly with metal-based nanoparticles, our understanding of how metals shape protein folds, the inter-and intramolecular interactions, the associative behavior, and evolve material characteristics of protein constructs, is limited. To address these highly challenging scientific questions, I have explored the self-assembling behavior of silk fibroin protein and its’ interaction with metal nanoparticles for the formation of multifunctional composites. The central goal of my research was to explore the full potential of metal nanoparticles (NP), in particular, copper oxide (CuO) to modify the self-assembly pathway of fiber-forming protein- silk fibroin. CuO NP has been chosen as a candidate for this study, due to its versatile properties and bio-relevant functionalities applicable for sensing, antibacterial function, and capability to regulate cellular activity. Thus, to address this challenge I first focused on the understanding of metal NP-induced structural transformations in natively folded protein and on probing whether these structural changes can be artificially imposed on the assembled, β-sheet rich protein complexes. My experimental results showed that CuO NPs are indeed capable of template the assembly of natively folded silk fibroin, on the one hand, and on the other hand, exhibited variations in NPs-silk fiber interaction when added at the post-synthetic stage. Yet, the fundamental questions of how RSF-CuO NPs self-assembly occurs remain to be addressed. The exploration of biomaterial applications for silks is only a relatively recent advance; therefore, the future for this family of structural proteins appears promising.
  • seminar
    Date:
    6 February
    2022
    Sunday
    Hours:
    12:00
    -
    13:00

    Zoom: "A Faster Path to Solar Fuels: New Approaches for Highly Efficient Materials for Photoelectrochemical Energy Conversion

    participants: Dr. Ronen Gottesman
    Institute for Solar Fuels, Helmholtz Center for Materials and Energy, Berlin

    Abstract

    Zoom: https://weizmann.zoom.us/j/95703489711?pwd=Tyt5cU1tV2YrMFhYUytBU001bm4yQT09 Viable, global-scale photoelectrochemical energy conversion of cheap, abundant resources such as water into chemical fuels (“solar fuels”) depends on the progress of semiconducting light-absorbers with good carrier transport properties, suitable band edge positions, and stability in direct-semiconductor/electrolyte junctions. Investigations concentrated mainly on metal-oxides that offer good chemical stability yet suffer from poor charge transport than non-oxide semiconductors (e.g., Si, GaAs). Fortunately, only a fraction of the possible ternary and quaternary combinations (together ~ 105 – 106 combinations) were studied, making it likely that the best materials are still awaiting discovery. Unfortunately, designing controlled synthesis routes of single-phase oxides with low defects concentration will become more difficult as the number of elements increases; and 2) there are currently no robust and proven strategies for identifying promising multi-elemental systems. These challenges demand initial focusing on synthesis parameters of novel non-equilibrium synthesis approaches rather than chemical composition parameters by high-throughput combinatorial investigations of synthesis-parameter spaces. This would open new avenues for stabilizing metastable materials, discovering new chemical spaces, and obtaining light-absorbers with enhanced properties to study their physical working mechanisms in photoelectrochemical energy conversion. I will introduce an approach to exploring non-equilibrium synthesis-parameter spaces by forming gradients in synthesis-parameters without modifying composition-parameters, utilizing two non-equilibrium synthesis components: pulsed laser deposition and rapid radiative-heating. Their combination enables reproducible, high-throughput combinatorial synthesis, resulting in high-resolution observation and analysis. Even minor changes in synthesis can impact significantly material properties, physical working mechanisms, and performances, as demonstrated by studies of the relationship between synthesis conditions, crystal structures of α-SnWO4, and properties over a range of thicknesses of CuBi2O4, both emerging light-absorbers for photoelectrochemical water-splitting that were used as model multinary oxides.
  • seminar
    Date:
    6 February
    2022
    Sunday
    Hours:
    11:00
    -
    12:00

    TEST TEST TEST

    participants: Dr. Test
    Test Univ
  • seminar
    Date:
    1 February
    2022
    Tuesday
    Hours:
    14:00
    -
    15:00

    Precise Patterning in the Mammalian Inner Ear

    participants: Prof. David Sprinzak
    School of Neurobiology, Biochemistry and Biophysics, Faculty of Life Sciences, TAU
  • seminar
    Date:
    1 February
    2022
    Tuesday
    Hours:
    11:00

    M. Magaritz Memorial Lecture: The storyline approach to the construction of useable climate information at the local scale.

    participants: Ted Shepherd
    Department of Meteorology University of Reading
  • seminar
    Date:
    30 January
    2022
    Sunday
    Hours:
    13:00
    -
    14:00

    Zoom: M.Sc thesis defense: "Investigation of the ceramic – polymer interface in composite solid electrolyte by Nuclear Magnetic Resonance Spectroscopy"

    participants: Chen Oppenheim
    M.Sc student of Dr. Michal Leskes

    Abstract

    https://weizmann.zoom.us/j/97328767376?pwd=MkZoQ0hmbVVRank0bzkxbGpqSUdYUT09 passcode: 891716 Lithium-ion batteries with liquid electrolytes are commonly employed for powering portable electronic devices. To expand the range of applications where Li ions batteries can be used (e.g., electric transportation), solid electrolytes are considered as a safer alternative to the liquid electrolytes and they may enable use of lithium metal anodes. In this study we focused on composite solid electrolytes which are based on solid polymer (Polyethylene Oxide) and ceramic particles (Li1.5Al0.5Ge1.5P3O12, LAGP). Previous studies revealed that the highest ionic conduction path in the composites is through the interface polymer - ceramic interface. However, the chemical nature of the interface and the reason for its higher conductivity remains unclear. We aim to gain molecular - atomic level insight into the nature of the polymer - ceramic interface from solid state NMR spectroscopy. Here, I will present the development of a solid - state NMR approach that can potentially be used to selectively probe the interface. To gain sensitivity and selectivity Dynamic Nuclear Polarization (DNP), a process in which high polarization from unpaired electrons is transferred to surrounding nuclear spins will be employed. Several metal ion dopants were tested for their DNP performance in LAGP powder, and Mn2+ ions were further examined in their efficacy in the composite electrolyte. The approach was tested for selectively enhancing the NMR signal of the PEO - LAGP interface. Electrochemical characterization and in - depth solid state NMR studies provided insight into the performance of the composite and degradation processes in the composite.
  • seminar
    Date:
    26 January
    2022
    Wednesday
    Hours:
    11:30
    -
    12:30

    M.Sc thesis defense: Characterization of anisotropic strain in anelstic materials by Raman spectroscopy

    participants: Daniel Freidson
    Prof. Igor Lubomirsky's group

    Abstract

    Zoom Link: https://weizmann.zoom.us/j/96430042316?pwd=cjJwdFUrSEE5VnU4eVNuY08wZ1F3QT09 Raman spectroscopy is used as a primary non-destructive tool for characterization of strain in thin films. It is based on the concept of the mode Grüneisen parameter, which is the ratio between the relative change in the energy of a given vibrational mode and the relative change in the unit cell volume. It has been recently reported (Kraynis et al.) that under biaxial strain, doped CeO2-films exhibit values of the mode Grüneisen parameter, which are up to 40% smaller than the bulk literature value. Doped CeO2-films are strongly anelastic, posing a question on the relation between Raman scattering frequency and anelastic strain. This work describes the way to separate anelastic and elastic contributions to the Grüneisen parameter of doped ceria thin films and show that this concept remains applicable, if only the elastic part of the strain must be taken into account. As a reference, I deposited a purely elastic yittria thin film by sputter deposition and calculated its Grüneisen parameter in a similar way. The experimental and literature values of the yittria Grüneisen parameter were found compatible, confirming that for purely elastic strain, Grüneisen parameter concept is fully applicable.
  • 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

    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:
    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:
    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:
    30 June
    2024
    Sunday
    Hours:
    11:00

    Data synthesis to assess the effects of climate change on agricultural production and food security

    Location: Sussman Family Building for Environmental Sciences
    participants: David Makowski
    INRAe & University Paris-Saclay

    Abstract

    Climate change is having an impact on agricultural production and food security. Rising temperatures, changes in rainfall patterns and extreme weather events can reduce crop yields, sometimes dramatically. However, climate change can also offer new opportunities, by generating more favorable climatic conditions for agricultural production in certain regions that were previously less productive. In order to assess the positive and negative impacts of climate change on agriculture and identify effective adaptation strategies, scientists have produced massive amounts of data during the last two decades, conducting local experiments in agricultural plots and using models to simulate the effect of climate on crop yields. In most cases, these data are not pooled together and are analyzed separately by different groups of scientists to assess the effects of climate change at a local level, without any attempt to upscale the results at a larger scale. Yet, if brought together, these data represent a rich source of information that are relevant to analyze the effect of climate across diverse environmental conditions. The wealth of data available has led to the emergence of a new type of scientific activity, involving the retrieval of all available data on a given subject and their synthesis into more robust and generic results. In this talk, I review the statistical methods available to synthesize data generated in studies quantifying the effect of climate change on agriculture. I discuss both the most classic methods - such as meta-analysis - and more recent methods based on machine learning. In particular, I show how this approach can be used to map the impact of climate change on a large scale (national, continental and global) from local data. I illustrate these methods in several case studies and present several research perspectives in this area.