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

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.

https://hal.archives-ouvertes.fr/hal-02417326/document

Materials for electrochemical capacitors

In this paper, radiating dipole antennas have been fabricated from rolled carbon films, which are typically used for supercapacitor electrodes. Return loss and radiation pattern measurements for onion-like carbon (OLC) and multi-walled carbon nanotubes (MWCNTs) antenna samples are presented and compared to a copper standard. The OLC antenna's radiation pattern measurements show a peak gain of −1.48 dBi, just less than 3 dB of a copper dipole antenna. Compared to antennas made from MWCNT films, the OLC samples show better radiation performance despite a lower measured conductivity.

Onion-like carbon and carbon nanotube film antennas

Effects of calcination environment (air and nitrogen) and temperature (400°-1000°C) on the structure, optical, photocatalytic, and mechanical properties of ultrathin sol-gel titanium dioxide (TiO 2 ) films were studied. X-ray diffraction and Raman analysis of the films have shown preferred rutile formation at high calcination temperatures and low oxygen pressures. Films calcined under nitrogen flow were optically absorbing and contained significant amounts of carbon due to the carbonization of the organic precursor, which also resulted in a porous structure. Although photocatalytic activity of the films calcined in different atmospheres showed similar temperature dependencies, nitrogen-calcined films performed better at high calcination temperatures and showed improved visible light activity. On the other hand, the mechanical properties of films calcined in air were superior to those calcined under nitrogen.

Effect of Calcination Temperature and Environment on Photocatalytic and Mechanical Properties of Ultrathin Sol–Gel Titanium Dioxide Films

Plasma pressure compaction of nanodiamond

MXenes are among the most widely researched materials due to a unique combination of high electronic conductivity and hydrophilic surface, confined in a 2D structure. Therefore, comprehensive characterization of individual MXene flakes is of great importance. Here we report on nanoscale Raman imaging of single-layer and few-layer flakes of Ti3C2Tx MXene deposited on a gold substrate using tip-enhanced Raman scattering (TERS). TERS spectra of MXene monolayers are dominated by an intense peak at around 201 cm-1 and two well-defined peaks at around 126 and 725 cm-1. Absolute intensities of these peaks decrease with increasing number of layers, though the relative intensity of the 126 and 725 cm-1 bands as compared to the 201 cm-1 band increases. The peak positions of the main MXene bands do not significantly change in flakes of different number of layers, suggesting weak coupling between the MXene layers. In addition, we observed stiffening of the 201 cm-1 vibration over the wrinkles in MXene flakes. Using TERS for nanoscale spectroscopic characterization of Ti3C2Tx allows fast Raman mapping with deep subdiffraction resolution at the laser power density on the sample about an order of magnitude lower as compared to confocal Raman measurements. Finally, we demonstrate very high environmental stability of stoichiometric single-layer MXenes and show that the intensity of TERS response from the single- and few-layer flakes of Ti3C2Tx can be used to track early stages of degradation, well before significant morphological changes appear.

Yury Gogotsi

Papers

Onion-like carbon and carbon nanotube film antennas

Effect of Calcination Temperature and Environment on Photocatalytic and Mechanical Properties of Ultrathin Sol–Gel Titanium Dioxide Films

Plasma pressure compaction of nanodiamond

Tip-Enhanced Raman Scattering Imaging of Single- to Few-Layer Ti3C2Tx MXene.

Hydrothermal behavior of diamond