Integrated Calendar

The Israel Quantum Information Theory day brings together researchers, postdoctoral scholars and Ph.D. students from Israel working on the theory of quantum computation and information processing for a day of scientific talks, research discussions and social interaction.

Registration: https://tinyurl.com/2rxsuykb

TBA

The Poisson-Boltzmann theory stems from the pioneering works of Debye and Onsager and is considered even today as the benchmark of ionic solutions and electrified interfaces. It has been instrumental during the last century in predicting charge distributions and interactions between charged surfaces, membranes, electrodes as well as macromolecules and colloids. The electrostatic model of charged fluids, on which the Poisson-Boltzmann description rests and its statistical mechanical consequences have been scrutinized in great detail. Much less, however, is understood about its probable shortcomings when dealing with various aspects of real physical, chemical, and biological systems. After reviewing the Poisson-Boltzmann theory, I will discuss several extensions and modifications to the seminal works of Debye and Onsager as applied to ions and macromolecules in confined geometries. These novel ideas include the effect of dipolar solvent molecules, finite size of ions, ionic specificity, surface tension, and conductivity of concentrated ionic solutions.

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

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.

Quasicrystals are exotic materials that have symmetries that once thought to be impossible for matter. The first known examples were synthesized in the laboratory 30 years ago, but could Nature have beaten us to the punch? This talk will describe the decades-long search to answer this question, resulting in one of the strangest scientific stories you are ever likely to hear.