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

THE large-scale use of photovoltaic devices for electricity generation is prohibitively expensive at present: generation from existing commercial devices costs about ten times more than conventional methods1. Here we describe a photovoltaic cell, created from low-to medium-purity materials through low-cost processes, which exhibits a commercially realistic energy-conversion efficiency. The device is based on a 10-µm-thick, optically transparent film of titanium dioxide particles a few nanometres in size, coated with a monolayer of a charge-transfer dye to sensitize the film for light harvesting. Because of the high surface area of the semiconductor film and the ideal spectral characteristics of the dye, the device harvests a high proportion of the incident solar energy flux (46%) and shows exceptionally high efficiencies for the conversion of incident photons to electrical current (more than 80%). The overall light-to-electric energy conversion yield is 7.1-7.9% in simulated solar light and 12% in diffuse daylight. The large current densities (greater than 12 mA cm-2) and exceptional stability (sustaining at least five million turnovers without decomposition), as well as the low cost, make practical applications feasible.

A low-cost, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films

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

The civilian, commercial, and defense sectors of most advanced industrialized nations are faced with a tremendous set of environmental problems related to the remediation of hazardous wastes, contaminated groundwaters, and the control of toxic air contaminants. For example, the slow pace of hazardous waste remediation at military installations around the world is causing a serious delay in conversion of many of these facilities to civilian uses. Over the last 10 years problems related to hazardous waste remediation have emerged as a high national and international priority.

Environmental Applications of Semiconductor Photocatalysis

The Advent of Molecular Photovoltaics and Hybrid Perovskite Solar Cells

Abstract The conversion of carbon dioxide to value-added products using renewable electricity would potentially help to address current climate concerns. The electrochemical reduction of carbon dioxide to propylene, a critical feedstock, requires multiple C–C coupling steps with the transfer of 18 electrons per propylene molecule, and hence is kinetically sluggish. Here we present the electrosynthesis of propylene from carbon dioxide on copper nanocrystals with a peak geometric current density of −5.5 mA cm −2 . The metallic copper nanocrystals formed from CuCl precursor present preponderant Cu(100) and Cu(111) facets, likely to favour the adsorption of key *C 1 and *C 2 intermediates. Strikingly, the production rate of propylene drops substantially when carbon monoxide is used as the reactant. From the electrochemical reduction of isotope-labelled carbon dioxide mixed with carbon monoxide, we infer that the key step for propylene formation is probably the coupling between adsorbed/molecular carbon dioxide or carboxyl with the *C 2 intermediates that are involved in the ethylene pathway. 

/pdf/electrochemical-synthesis-of-propylene-from-carbon-dioxide-26jc6n1z.pdf

Electrochemical synthesis of propylene from carbon dioxide on copper nanocrystals

The electron transfer (ET) from organic dye molecules to semiconductor-colloidal systems is characterized by a special energetic situation with a charge transfer reaction from a system of discrete donor levels to a continuum of acceptor states. If these systems show a strong electronic coupling they are amongst the fastest known ET systems with transfer times of less than 10 fs. In the first part a detailed discussion of the direct observation of an ET reaction with a time constant of about 6 fs will be given, with an accompanying argumentation concerning possible artifacts or other interfering signal contributions. In a second part we will try to give a simple picture for the scenario of such superfast ET reactions and one main focus will be the discussion of electronic dephasing and its consequences for the ET reaction. We show that the actual ET process can be understood as a kind of dispersion process of the initially located electron into the colloid representing a real motion of charge density from the alizarin to the colloid.

Beyond vibrationally mediated electron transfer: interfacial charge injection on a sub-10-fs time scale

Solar Cells: Ionic Liquid Control Crystal Growth to Enhance Planar Perovskite Solar Cells Efficiency (Adv. Energy Mater. 20/2016)

Diese Arbeit wurde vom Schweizerischen Nationalfonds (SNF) im Rahmen des Ambizione Energy Grant (PZENP2_166871) und vom Gaznat-EPFL Forschungsprogramm unterstutzt. M.B. und U.A. wurden durch die Forderungsprofessuren PP00P2_157615 und PP00P2_187185 des Schweizerischen Nationalfonds unterstutzt. Die Berechnungen wurden auf UBELIX, dem HPC-Cluster der Universitat Bern, durchgefuhrt. M.X. dankt dem China Scholarship Council (Nr. CSC201806160172) und dem Strategic Japanese–Swiss Science and Technology-Programm (514259) fur die Unterstutzung. Open access funding provided by Ecole Polytechnique Federale de Lausanne.

Michael Grätzel

Papers

The Advent of Molecular Photovoltaics and Hybrid Perovskite Solar Cells

Electrochemical synthesis of propylene from carbon dioxide on copper nanocrystals

Beyond vibrationally mediated electron transfer: interfacial charge injection on a sub-10-fs time scale

Solar Cells: Ionic Liquid Control Crystal Growth to Enhance Planar Perovskite Solar Cells Efficiency (Adv. Energy Mater. 20/2016)

Identifizierung von reaktiven Zentren und Oberflächenfallen in Chalkopyrit-Photokathoden