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 …

I and i

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

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。

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

Thermoelectric materials, which can generate electricity from waste heat or be used as solid-state Peltier coolers, could play an important role in a global sustainable energy solution. Such a development is contingent on identifying materials with higher thermoelectric efficiency than available at present, which is a challenge owing to the conflicting combination of material traits that are required. Nevertheless, because of modern synthesis and characterization techniques, particularly for nanoscale materials, a new era of complex thermoelectric materials is approaching. We review recent advances in the field, highlighting the strategies used to improve the thermopower and reduce the thermal conductivity.

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Complex thermoelectric materials.

Giant Enhancement of Lattice Thermal Conductivity and Mechanical Properties of Hexagonal Boron Sheets Through Molybdenum Intercalation

Wear and Electrochemical Behavior of High-Nitrogen, Nickel-Free Austenitic Stainless Steel Produced by Hot Powder Forging

Process Considerations for selective doping of poly-Si thin films with spin-on dopants and nickel silicide formation for planar thermoelectric devices

Bismuth telluride-based alloys possess the highest efficiencies for the low-temperature-range (<500 K) applications among thermoelectric materials. Despite significant advances in the efficiency of p-type Bi2Te3-based materials through engineering the electronic band structure by convergence of multiple bands, the n-type pair still suffers from poor efficiency due to a lower number of electron pockets near the conduction band edge than the valence band. To overcome the persistent low efficiency of n-type Bi2Te3-based materials, we have fabricated multiphase pseudobinary Bi2Te3–Bi2S3 compounds to take advantages of phonon scattering and energy filtering at interfaces, enhancing the efficiency of these materials. The energy barrier generated at the interface of the secondary phase of Bi14Te13S8 in the Bi2Te3 matrix resulted in a higher Seebeck coefficient and consequently a higher power factor in multiphase compounds than the single-phase alloys. This effect was combined with low thermal conductivity achieved through phonon scattering at the interfaces of finely structured multiphase compounds and resulted in a relatively high thermoelectric figure of merit of ∼0.7 over the 300–550 K temperature range for the multiphase sample of n-type Bi2Te2.75S0.25, double the efficiency of single-phase Bi2Te3. Our results inform an alternative alloy design to enhance the performance of thermoelectric materials.

https://pubs.acs.org/doi/pdf/10.1021/acsami.3c01956

Room-Temperature Thermoelectric Performance of n-Type Multiphase Pseudobinary Bi2Te3–Bi2S3 Compounds: Synergic Effects of Phonon Scattering and Energy Filtering

Nickel-free high nitrogen austenitic stainless steel, with a composition according to ASTM F 2581, was produced by hot powder forging (HPF). To improve the sintering behavior and increase the density of this alloy, a biocompatible additive of Mn-11.5 wt% Si at 3, and 6 wt% was added to the alloying powder, and the effect of the additives on the physical and mechanical properties of the alloy was investigated. The structure of the specimens was examined by X-ray diffraction (XRD), metallography, optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy(TEM), selected area diffraction (SAD) and magnetometer. The densities of the samples were analyzed by the Archimedes and image analysis methods and the mechanical properties of the samples were determined by microhardness, hardness, compression and tensile tests. The XRD results demonstrate that the forged samples contain austenitic nanocrystalline and amorphous phases with no ferrite and martensitic phases in the structure. Densitometry proves that the sample with a 6 wt% additive consolidated to near 96% theoretical density. Hardness, microhardness, tensile and compression tests show that this alloy composition also has better mechanical properties than alloys containing 0 and 3 wt% additive. The results show that stainless steel 316L and forged nickel-free high nitrogen austenitic stainless steel behave similarly to soft magnetic materials, although the magnetic saturation of nickel-free steel is lower than that of 316L steel. This study proves that the alloy made by HPF has significantly better mechanical properties than conventional commercial 316L. The effect of the additive on the microstructure and other features is discussed in detail.

Daryoosh Vashaee

Papers

Giant Enhancement of Lattice Thermal Conductivity and Mechanical Properties of Hexagonal Boron Sheets Through Molybdenum Intercalation

Wear and Electrochemical Behavior of High-Nitrogen, Nickel-Free Austenitic Stainless Steel Produced by Hot Powder Forging

Process Considerations for selective doping of poly-Si thin films with spin-on dopants and nickel silicide formation for planar thermoelectric devices

Room-Temperature Thermoelectric Performance of n-Type Multiphase Pseudobinary Bi2Te3–Bi2S3 Compounds: Synergic Effects of Phonon Scattering and Energy Filtering

Microstructure, mechanical and magnetic properties of a nickel-free austenitic stainless steel fabricated by hot powder forging