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

Recent progress in quantum cutting phosphors

The Eu3+ charge transfer energy and the relation with the band gap of compounds

Counterfeiting of valuable documents, currency and branded products is a challenging problem that has serious economic, security and health ramifications for governments, businesses and consumers all over the world. It is estimated that counterfeiting represents a multi-billion dollar underground economy with counterfeit products being produced on a large scale every year. Counterfeiting is an increasingly high-tech crime and calls for high-tech solutions to prevent and deter the acts of counterfeiting. The present review briefly outlines and addresses the key challenges in this area, including the above mentioned concerns for anti-counterfeiting applications. This article describes a unique combination of all possible kinds of security ink formulations based on lanthanide doped luminescent nanomaterials, quantum dots (semiconductor and carbon based), metal organic frameworks as well as plasmonic nanomaterials for their possible use in anti-counterfeiting applications. Moreover, in this review, we have briefly discussed and described the historical background of luminescent nanomaterials, basic concepts and detailed synthesis methods along with their characterization. Furthermore, we have also discussed the methods adopted for the fabrication and design of luminescent security inks, various security printing techniques and their anti-counterfeiting applications.

Future prospects of luminescent nanomaterial based security inks: from synthesis to anti-counterfeiting applications

Recent advances on environmental corrosion behavior and mechanism of high-entropy alloys

In this paper, the (CoCrFeNi)95Nb5 high-entropy alloy (HEA) coating with a thickness of 500 μm on Q235 steel substrate was fabricated by plasma spraying. The microscopic results showed that a new Laves phase is formed in the (CoCrFeNi)95Nb5 HEA coating compared to the HEA powder, and elemental segregation occurs between the dendrites and the interdendrites of the coating, while the interdendritic phase enriches with the Cr and Nb. The phase composition change and elemental segregation behavior were mainly due to the faster cooling rate of the plasma spraying technique. At the junction of the coating and the substrate, the HEA coating bonded well to the substrate; in addition, the width of transition zone was merely 2 μm. The microhardness of the (CoCrFeNi)95Nb5 HEA coating was 321 HV0.5, which is significantly higher than that of the substrate. In terms of corrosion resistance, the (CoCrFeNi)95Nb5 HEA coating has good corrosion resistance in NaCl solution. Although the corrosion form was pitting corrosion, the pitting potential of the (CoCrFeNi)95Nb5 HEA coating was significantly higher than that of other coatings, which was mainly because of the dense passivation film formed by Cr and Nb on the surface of the coating. Once the passivation film was destroyed by Cl−, the selective corrosion occurred on the surface of the (CoCrFeNi)95Nb5 HEA coating. In summary, the (CoCrFeNi)95Nb5 HEA coating prepared by plasma spraying technology can significantly improve the corrosion resistance and mechanical properties of the Q235 steel substrate.

https://www.mdpi.com/1996-1944/12/5/694/pdf

Wenrui Wang

Papers

Microstructure and Corrosion Behavior of (CoCrFeNi)95Nb5 High-Entropy Alloy Coating Fabricated by Plasma Spraying

Effect of Mo and aging temperature on corrosion behavior of (CoCrFeNi)100-xMox high-entropy alloys

Photon cascade luminescence of Gd3+ in GdBaB9O16

The corrosion of Fe3Al alloy in liquid zinc

The corrosion of intermetallic alloys in liquid zinc