Yury Gogotsi

Bio: Yury Gogotsi is an academic researcher from Drexel University. The author has contributed to research in topics: MXenes & Carbon. The author has an hindex of 171, co-authored 956 publications receiving 144520 citations. Previous affiliations of Yury Gogotsi include Qatar Airways & Clemson University.

An Atomistic Carbide-Derived Carbon Model Generated Using ReaxFF-Based Quenched Molecular Dynamics

Abstract: We report a novel atomistic model of carbide-derived carbons (CDCs), which are nanoporous carbons with high specific surface areas, synthesis-dependent degrees of graphitization, and well-ordered, tunable porosities. These properties make CDCs viable substrates in several energy-relevant applications, such as gas storage media, electrochemical capacitors, and catalytic supports. These materials are heterogenous, non-ideal structures and include several important parameters that govern their performance. Therefore, a realistic model of the CDC structure is needed in order to study these systems and their nanoscale and macroscale properties with molecular simulation. We report the use of the ReaxFF reactive force field in a quenched molecular dynamics routine to generate atomistic CDC models. The pair distribution function, pore size distribution, and adsorptive properties of this model are reported and corroborated with experimental data. Simulations demonstrate that compressing the system after quenching changes the pore size distribution to better match the experimental target. Ring size distributions of this model demonstrate the prevalence of non-hexagonal carbon rings in CDCs. These effects may contrast the properties of CDCs against those of activated carbons with similar pore size distributions and explain higher energy densities of CDC-based supercapacitors.

Understanding Defect-Stabilized Noncovalent Functionalization of Graphene

Abstract: The noncovalent functionalization of graphene by small molecule aromatic adsorbates, phenanthrenequinone (PQ), is investigated systematically by combining electrochemical characterization, high-resolution interfacial X-ray scattering, and ab initio density functional theory calculations. The findings in this study reveal that while PQ deposited on pristine graphene is unstable to electrochemical cycling, the prior introduction of defects and oxygen functionality (hydroxyl and epoxide groups) to the basal plane by exposure to atomic radicals (i.e., oxygen plasma) effectively stabilizes its noncovalent functionalization by PQ adsorption. The structure of adsorbed PQ molecules resembles the graphene layer stacking and is further stabilized by hydrogen bonding with terminal hydroxyl groups that form at defect sites within the graphene basal plane. The stabilized PQ/graphene interface demonstrates persistent redox activity associated with proton-coupled-electron-transfer reactions. The resultant PQ adsorbed structure is essentially independent of electrochemical potentials. These results highlight a facile approach to enhance functionalities of the otherwise chemically inert graphene using noncovalent interactions.

Humidity Exposure Enhances Microscopic Mobility in a Room-Temperature Ionic Liquid in MXene

Abstract: Present and future electrochemical devices employing advanced electrode and electrolyte materials are expected to operate in diverse environments, where they are exposed to variable conditions, such as changing humidity levels. Such conditions can possibly alter the microscopic mechanisms that influence the electrochemical performance. Here, using quasi-elastic neutron scattering and molecular dynamics simulations, we investigate the influence of humidity exposure on a room-temperature ionic liquid, [EMIm+][Tf2N–], in Ti3C2Tx MXene. Absorbed water enhances the microscopic mobility of confined [EMIm+][Tf2N–], even though the ionic liquid itself is not very hygroscopic. The absorbed water molecules predominantly reside on the termination groups of the more hydrophilic MXene layers, thereby displacing the ions from the surface and facilitating their motions in the MXene matrix.

The Rising and Receding Fortunes of Electrochemists.

Abstract: Electrochemists This is the golden age of electrochemistry. Never before has this discipline found itself at the nexus of so many developing technologies: batteries, capacitors, fuel cells; solar-to-electrical energy conversion at liquid junctions; nanocrystalline solar cells; and organic solar cells. New electrochemical energy-harvesting technologies are also being explored for thermal energy harvesting, and these are just the electrochemistry-related technologies pertaining to energy. Capacitive water deionization and electrochemical sensors and actuators are being widely explored, and the use of electrochemical methods in electronic manufacturing, coatings, and the synthesis of materials (including aluminum) remains as important as ever. Energy is an international priority and an abundance of research funding has been made available for applied electrochemistry. Prominent programs just the United States include The Energy Innovation Hubs, grants from the ARPA-E, many of the Energy Frontier Research Centers (EFRCs), and others. This funding is directed at all of the energy-related topics listed above. This infusion of resourcesparticularly from the U.S. Department of Energyhas attracted new practitioners into these areas. Not surprisingly, at ACS Nano we have witnessed rapid increases in the submission of manunscripts related to electrochemical energy science. Our goal at ACS Nano is to publish the best work across these areas to give insight into the opportunities ahead, as new energy-generation and storage solutions increasingly use nanoscale science and engineering. Ironically, fundamental electrochemical investigations have not been buoyed by these rising seas. In our view, the need for research that elucidates fundamental aspects of electrochemistry in support of its applications in energy has never been greater. We would welcome greater efforts and a consequent larger number of insightful submissions in this area. We, as a community, are just starting to appreciate that so-called “electrical double-layer capacitors” adsorb ions (often partially desolvated) to store energy, and that there is no room for the formation of a classical Helmholtz layer in microporous carbon electrodes. Textbook schematics of the double layer at metal surfaces that show highly oriented water dipoles contradict the latest research findings, suggesting that layers of water at metal surfaces have frustrated structures. Understanding the effects of ion charge, radius, and hydration energy on adsorption interactions of ions on oxide surfaces is much more complex. These are amongst the pressing fundamental issues that should be addressed by electrochemists.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Fast parallel algorithms for short-range molecular dynamics

Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Materials for electrochemical capacitors

Abstract: Electrochemical capacitors, also called supercapacitors, store energy using either ion adsorption (electrochemical double layer capacitors) or fast surface redox reactions (pseudo-capacitors). They can complement or replace batteries in electrical energy storage and harvesting applications, when high power delivery or uptake is needed. A notable improvement in performance has been achieved through recent advances in understanding charge storage mechanisms and the development of advanced nanostructured materials. The discovery that ion desolvation occurs in pores smaller than the solvated ions has led to higher capacitance for electrochemical double layer capacitors using carbon electrodes with subnanometre pores, and opened the door to designing high-energy density devices using a variety of electrolytes. Combination of pseudo-capacitive nanomaterials, including oxides, nitrides and polymers, with the latest generation of nanostructured lithium electrodes has brought the energy density of electrochemical capacitors closer to that of batteries. The use of carbon nanotubes has further advanced micro-electrochemical capacitors, enabling flexible and adaptable devices to be made. Mathematical modelling and simulation will be the key to success in designing tomorrow's high-energy and high-power devices.