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

Single-layer metal dichalcogenides are two-dimensional semiconductors that present strong potential for electronic and sensing applications complementary to that of graphene.

/pdf/electronics-and-optoelectronics-of-two-dimensional-2jbqr1unvw.pdf

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides.

The electronic properties of ultrathin crystals of molybdenum disulfide consisting of N=1,2,…,6 S-Mo-S monolayers have been investigated by optical spectroscopy Through characterization by absorption, photoluminescence, and photoconductivity spectroscopy, we trace the effect of quantum confinement on the material's electronic structure With decreasing thickness, the indirect band gap, which lies below the direct gap in the bulk material, shifts upwards in energy by more than 06 eV This leads to a crossover to a direct-gap material in the limit of the single monolayer Unlike the bulk material, the MoS₂ monolayer emits light strongly The freestanding monolayer exhibits an increase in luminescence quantum efficiency by more than a factor of 10⁴ compared with the bulk material

Atomically thin MoS2: a new direct-gap semiconductor

Ozone treated carbon electrodes can provide increased catalytic activity, such as in a dye-sensitized solar cell (DSSC) or other electrochemical device or other device that could benefit from an increased catalytic activity, such as lithium ion or other batteries, hydrogen fuel cells, or electroanalytical instruments Devices, methods of making, and methods of using are discussed

Ozone-treated carbon electrodes

Carbon nanotubes have been used to probe the properties of bilayer systems resembling living cell membranes. Such experiments could offer new insights into the working of cells.

Nanobiotechnology: looking inside cell walls.

The fields of electronics and mechanics have made impressive progress toward true quantum mechanical devices. Through improvements in device performance and measurement techniques, nanoelectromechanical systems (NEMS) have enabled high-sensitivity detection of charge, mass, and spin, and have steadily approached the quantum limit of mechanical motion ( 1 ). Similarly, the ability to manipulate individual electrons in quantum dots has led to developments in solid-state quantum computing ( 2 ). On pages 1107 and 1103 of this issue, Lassagne et al. ( 3 ) and Steele et al. ( 4 ) bring together these two fields to study the influence of charge transport on nanomechanical motion in high-performance carbon nanotube mechanical resonators that simultaneously act as quantum dots. They find that the resonant frequency and dissipation in the nanotubes are both highly sensitive to the charge state at the level of single electrons.

http://science.sciencemag.org/content/sci/325/5944/1084.full.pdf

Coupling Strongly, Discretely

Water vapor barriers used for graphene encapsulation can both exclude water from the environment and trap water in the device, preventing annealing from improving device performance. In this paper, the authors investigate the effects of vacuum annealing on encapsulated single layer graphene field effect transistors (SLG-FETs). The stability of GFETs is monitored for a period of up to six months, and different annealing times and atmospheres are tested to recover lost electronic performance. Fabricated encapsulated devices based on a parylene-C/aluminum passivation layers offer increased stability over exposed back-gated devices, but still suffer from a significant Dirac point shift over extended air exposure. Our results show that GFETs subjected to varying annealing times exhibit similar initial behavior, characterized by a substantial reduction of their doping profile due to desorption of oxygen/water molecules, but drastically different long term stability. This suggests that moderate vacuum annealing can dehydrate even encapsulated devices, whereas extended annealing times can damage the encapsulation layer.

Effect of vacuum thermal annealing to encapsulated graphene field effect transistors

Quantum computers can potentially achieve an exponential speedup versus classical computers on certain computational tasks, recently demonstrated in superconducting qubit processors. However, the capacitor electrodes that comprise these qubits must be large in order to avoid lossy dielectrics. This tactic hinders scaling by increasing parasitic coupling among circuit components, degrading individual qubit addressability, and limiting the spatial density of qubits. Here, we take advantage of the unique properties of van der Waals (vdW) materials to reduce the qubit area by >1000 times while preserving the capacitance while maintaining quantum coherence. Our qubits combine conventional aluminum-based Josephson junctions with parallel-plate capacitors composed of crystalline layers of superconducting niobium diselenide and insulating hexagonal boron nitride. We measure a vdW transmon T1 relaxation time of 1.06 μs, demonstrating a path to achieve high-qubit-density quantum processors with long coherence times, and the broad utility of layered heterostructures in low-loss, high-coherence quantum devices.

James Hone

Papers

Ozone-treated carbon electrodes

Nanobiotechnology: looking inside cell walls.

Coupling Strongly, Discretely

Effect of vacuum thermal annealing to encapsulated graphene field effect transistors

Miniaturizing Transmon Qubits Using van der Waals Materials.