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

Structure of nanocrystalline BN and BN/C coatings on SiC

The dynamical structural response of MXenes during electrochemical ion intercalation is critical for their functionality in fast chemical actuation and high-power electrical energy storage but has yet to be observed. Here, the dynamically evolving layer spacing of a Ti3C2Tx MXene film was observed using time-resolved operando X-ray reflectivity during cyclic voltammetry for applied potentials between +0.3 and −0.7 V (vs Ag/AgCl) at sweep rates 1 ≤ v ≤ 500 mV/s. The pseudocapacitive electrochemical MXene response in the aqueous 0.1 M Li2SO4 electrolyte, including both capacitive and redox characteristics, is characterized by kinetically limited lithium intercalation and layer contraction. Two types of dynamical responses were observed: slow and fast lattice contraction regimes versus applied potential are correlated with the capacitive and redox features, respectively, with structural relaxation rates that scale as ∼v1/2 and ∼v, revealing two distinct dynamical structural responses during electrochemical ion intercalation. 

Operando X-ray Reflectivity Reveals the Dynamical Response of Ti3C2 MXene Film Structure during Electrochemical Cycling

Cataract surgery removes the diseased lens of the eye replacing it with an intraocular lens, restoring visual acuity. However, accommodation, the lens’ ability to provide dynamic change in focus, is lost. A number of accommodative intraocular lens (AIOL) designs have been considered although none have provided a truly effective clinical AIOL. Two-dimensional titanium carbide (Ti3C2T x ) MXene has been used as a transparent conductive electrode within an AIOL feasibility study. Nevertheless, the potential for Ti3C2T x to repress excessive inflammation and promote wound healing following cataract surgery has not been considered. Cataract surgery can trigger chronic inflammation and epithelial-mesenchymal transition (EMT) in residual lens epithelial cells (LECs), producing a fibrotic mass across the posterior capsule known as posterior capsule opacification (PCO). With a large surface area and capacity for surface functionalisation, MXene has properties enabling a dual purpose AIOL design with an additional therapeutic role in the repression of pathways leading to PCO development. In this study, Ti3C2T x MXene was investigated to determine its impact on pathways leading to chronic inflammation and EMT using an in vitro LECs model. Ti3C2T x MXene was synthesised and characterised using UV-vis spectroscopy, dynamic light scattering and scanning electron microscopy. Changes in markers linked to inflammation and EMT in Ti3C2T x -treated LECs were measured using enzyme linked immunosorbent assays, quantitative polymerase chain reaction, scratch assay, RNA sequencing for whole-cell gene expression profiling and lipidomics analysis. Ti3C2T x significantly reduced the expression of pro-inflammatory cytokines by interleukin 1 beta primed LECs and did not advocate EMT, promoting a positive resolution of the wound healing response. This study supports the role of Ti3C2T x within an AIOL design with the potential to repress key developmental pathways leading to PCO.

Positive resolution of the wound-healing response in lens epithelial cells by Ti3C2T x MXene coatings for use in accommodative intraocular lens devices

A method and apparatus for carrying out measurements on single cells, either one or many single cells at a time in order to characterize the cellular response to stimuli in a perfused liquid. The apparatus for performing the respirometry includes a double-barrel pipette probe.

A method and apparatus for measuring biological activity with single cell resolution

On-board hydrogen storage is a key requirement for fuel cell-powered cars and trucks. Porous carbon-based materials can in principle adsorb more hydrogen per unit weight at room temperature than liquid hydrogen at -176 oC. Achieving this goal requires interconnected pores with very high internal surface area, and binding energies between hydrogen and carbon significantly enhanced relative to H2 on graphite. In this project a systematic study of carbide-derived carbons, a novel form of porous carbon, was carried out to discover a high-performance hydrogen sorption material to meet the goal. In the event we were unable to improve on the state of the art in terms of stored hydrogen per unit weight, having encountered the same fundamental limit of all porous carbons: the very weak interaction between H2 and the carbon surface. On the other hand we did discover several strategies to improve storage capacity on a volume basis, which should be applicable to other forms of porous carbon. Further discoveries with potentially broader impacts include • Proof that storage performance is not directly related to pore surface area, as had been previously claimed. Small pores (< 1.5 nm) are much more effective in storing hydrogen than larger ones, such thatmore » many materials with large total surface areas are sub-par performers. • Established that the distribution of pore sizes can be controlled during CDC synthesis, which opens the possibility of developing high performance materials within a common family while targeting widely disparate applications. Examples being actively pursued with other funding sources include methane storage, electrode materials for batteries and supercapacitors with record high specific capacitance, and perm-selective membranes which bind cytokines for control of infections and possibly hemodialysis filters.« less

/pdf/carbide-derived-carbons-with-tunable-porosity-optimized-for-1zg0bkafm0.pdf

Yury Gogotsi

Papers

Structure of nanocrystalline BN and BN/C coatings on SiC

Operando X-ray Reflectivity Reveals the Dynamical Response of Ti3C2 MXene Film Structure during Electrochemical Cycling

Positive resolution of the wound-healing response in lens epithelial cells by Ti3C2T x MXene coatings for use in accommodative intraocular lens devices

A method and apparatus for measuring biological activity with single cell resolution

Carbide-Derived Carbons with Tunable Porosity Optimized for Hydrogen Storage