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.

Fast parallel algorithms for short-range molecular dynamics

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

As a fascinating conjugated polymer, graphitic carbon nitride (g-C3N4) has become a new research hotspot and drawn broad interdisciplinary attention as a metal-free and visible-light-responsive photocatalyst in the arena of solar energy conversion and environmental remediation. This is due to its appealing electronic band structure, high physicochemical stability, and “earth-abundant” nature. This critical review summarizes a panorama of the latest progress related to the design and construction of pristine g-C3N4 and g-C3N4-based nanocomposites, including (1) nanoarchitecture design of bare g-C3N4, such as hard and soft templating approaches, supramolecular preorganization assembly, exfoliation, and template-free synthesis routes, (2) functionalization of g-C3N4 at an atomic level (elemental doping) and molecular level (copolymerization), and (3) modification of g-C3N4 with well-matched energy levels of another semiconductor or a metal as a cocatalyst to form heterojunction nanostructures. The constructi...

Graphitic Carbon Nitride (g-C3N4)-Based Photocatalysts for Artificial Photosynthesis and Environmental Remediation: Are We a Step Closer To Achieving Sustainability?

There is still an ongoing effort to search for sustainable, clean and highly efficient energy generation to satisfy the energy needs of modern society. Among various advanced technologies, electrocatalysis for the oxygen evolution reaction (OER) plays a key role and numerous new electrocatalysts have been developed to improve the efficiency of gas evolution. Along the way, enormous effort has been devoted to finding high-performance electrocatalysts, which has also stimulated the invention of new techniques to investigate the properties of materials or the fundamental mechanism of the OER. This accumulated knowledge not only establishes the foundation of the mechanism of the OER, but also points out the important criteria for a good electrocatalyst based on a variety of studies. Even though it may be difficult to include all cases, the aim of this review is to inspect the current progress and offer a comprehensive insight toward the OER. This review begins with examining the theoretical principles of electrode kinetics and some measurement criteria for achieving a fair evaluation among the catalysts. The second part of this review acquaints some materials for performing OER activity, in which the metal oxide materials build the basis of OER mechanism while non-oxide materials exhibit greatly promising performance toward overall water-splitting. Attention of this review is also paid to in situ approaches to electrocatalytic behavior during OER, and this information is crucial and can provide efficient strategies to design perfect electrocatalysts for OER. Finally, the OER mechanism from the perspective of both recent experimental and theoretical investigations is discussed, as well as probable strategies for improving OER performance with regards to future developments.

Electrocatalysis for the oxygen evolution reaction: recent development and future perspectives

The efficiency of many energy storage technologies, such as rechargeable metal-air batteries and hydrogen production from water splitting, is limited by the slow kinetics of the oxygen evolution reaction (OER). We found that Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3–δ (BSCF) catalyzes the OER with intrinsic activity that is at least an order of magnitude higher than that of the state-of-the-art iridium oxide catalyst in alkaline media. The high activity of BSCF was predicted from a design principle established by systematic examination of more than 10 transition metal oxides, which showed that the intrinsic OER activity exhibits a volcano-shaped dependence on the occupancy of the 3d electron with an e g symmetry of surface transition metal cations in an oxide. The peak OER activity was predicted to be at an e g occupancy close to unity, with high covalency of transition metal–oxygen bonds.

https://science.sciencemag.org/content/sci/early/2011/10/26/science.1212858.full.pdf

A perovskite oxide optimized for oxygen evolution catalysis from molecular orbital principles.

The present invention relates to a medium and high-temperature carbon-air cell, which include a solid oxide fuel cell, a CO2 separation membrane and a carbon fuel. The solid oxide fuel cell is a tubular solid oxide fuel cell with one end closed, the carbon fuel is placed inside the tubular solid oxide fuel cell, and the CO2 separation membrane is sealed at the open end of the solid oxide fuel cell. In the carbon-air cell, with carbon as fuel and oxygen in the air as an oxidizing gas, electrochemical reactions occur. The carbon-air cell of the present invention has a novel structural design, and can achieve electricity generation with the solid oxide fuel cell without externally charging a gas, and at the same time, CO2 generated inside the solid oxide fuel cell can be discharged from the system through the CO2 separation membrane in time.

Medium and high-temperature carbon-air cell

/pdf/erratum-oxygen-permeation-behavior-through-ce0-9gd0-1o2-d-mrwsgusoke.pdf

Erratum: Oxygen permeation behavior through Ce0.9Gd0.1O2-d membranes electronically short-circuited by dual-phase Ce0.9Gd0.1O2-d-Ag decoration (Journal of Materials Chemistry A (2015) 3 (19033-19041))

Utilizing the charge-transfer model to design promising electrocatalysts

This chapter presents the definition, functions, and requirements of the interconnect materials for intermediate temperature solid oxide fuel cells (IT-SOFCs), including several interconnect materials for SOFCs. In the past, the most promising candidates have been LaCrO3- and YCrO3-based perovskite materials. Recently, metal-based materials and modified or coated alloys have also attracted attention. However, different interconnect materials are suitable for SOFCs with different temperature ranges. For high-temperature SOFCs, only limited types of perovskite-based oxides are applicable as interconnects. With the decrease in operation temperature to the intermediate range, i.e., 500–800 °C, metal-based interconnects can be used, thus making the SOFCs more versatile in stack construction. In this chapter, we focus on the development of LaCrO3 and YCrO3 perovskite-based interconnects and various metal-based interconnects primarily based on Cr, Ni, and Fe. Recently, several coating systems, such as spinel coating and perovskite coating, have been adopted for metal-based interconnects to reduce chromium volatilization and maintain a low electrical resistance, which might provide a new approach to designing and developing stable interconnects with low resistance. This chapter aims to provide useful guidelines for future research on interconnect materials for IT-SOFCs.

Zongping Shao

Papers

Medium and high-temperature carbon-air cell

Erratum: Oxygen permeation behavior through Ce0.9Gd0.1O2-d membranes electronically short-circuited by dual-phase Ce0.9Gd0.1O2-d-Ag decoration (Journal of Materials Chemistry A (2015) 3 (19033-19041))

Utilizing the charge-transfer model to design promising electrocatalysts

Interconnect Materials for IT-SOFCs

Inner wrinkled mesoporous hollow carbon spheres with nanopillars connected to double shells for excellent potassium storage