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

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346

Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology.

There is intense interest in graphene in fields such as physics, chemistry, and materials science, among others. Interest in graphene's exceptional physical properties, chemical tunability, and potential for applications has generated thousands of publications and an accelerating pace of research, making review of such research timely. Here is an overview of the synthesis, properties, and applications of graphene and related materials (primarily, graphite oxide and its colloidal suspensions and materials made from them), from a materials science perspective.

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Graphene and Graphene Oxide: Synthesis, Properties, and Applications

Herein we obtained a chemically bonded TiO2 (P25)-graphene nanocomposite photocatalyst with graphene oxide and P25, using a facile one-step hydrothermal method. During the hydrothermal reaction, both of the reduction of graphene oxide and loading of P25 were achieved. The as-prepared P25-graphene photocatalyst possessed great adsorptivity of dyes, extended light absorption range, and efficient charge separation properties simultaneously, which was rarely reported in other TiO2−carbon photocatalysts. Hence, in the photodegradation of methylene blue, a significant enhancement in the reaction rate was observed with P25-graphene, compared to the bare P25 and P25-CNTs with the same carbon content. Overall, this work could provide new insights into the fabrication of a TiO2−carbon composite as high performance photocatalysts and facilitate their application in the environmental protection issues.

P25-Graphene Composite as a High Performance Photocatalyst

Graphene oxide: preparation, functionalization, and electrochemical applications.

Chemical doping with foreign atoms is an effective method to intrinsically modify the properties of host materials. Among them, nitrogen doping plays a critical role in regulating the electronic properties of carbon materials. Recently, graphene, as a true two-dimensional carbon material, has shown fascinating applications in bioelectronics and biosensors. In this paper, we report a facile strategy to prepare N-doped graphene by using nitrogen plasma treatment of graphene synthesized via a chemical method. Meanwhile, a possible schematic diagram has been proposed to detail the structure of N-doped graphene. By controlling the exposure time, the N percentage in host graphene can be regulated, ranging from 0.11 to 1.35%. Moreover, the as-prepared N-doped graphene has displayed high electrocatalytic activity for reduction of hydrogen peroxide and fast direct electron transfer kinetics for glucose oxidase. The N-doped graphene has further been used for glucose biosensing with concentrations as low as 0.01 mM ...

Nitrogen-Doped Graphene and Its Application in Electrochemical Biosensing

Graphene has received widespread attention due to its unique electronic properties. Much of the research conducted so far has focused on electron mobility, which is determined by scattering from charged impurities and other inhomogeneities. However, another important quantity, the quantum capacitance, has been largely overlooked. Here, we report a direct measurement of the quantum capacitance of graphene as a function of gate potential using a three-electrode electrochemical configuration. The quantum capacitance has a non-zero minimum at the Dirac point and a linear increase on both sides of the minimum with relatively small slopes. Our findings -- which are not predicted by theory for ideal graphene -- suggest that charged impurities also influences the quantum capacitance. We also measured the capacitance in aqueous solutions at different ionic concentrations, and our results strongly indicate that the long-standing puzzle about the interfacial capacitance in carbon-based electrodes has a quantum origin.

Jinghong Li

Papers

P25-Graphene Composite as a High Performance Photocatalyst

Graphene oxide: preparation, functionalization, and electrochemical applications.

Nitrogen-Doped Graphene and Its Application in Electrochemical Biosensing

Measurement of the quantum capacitance of graphene.

Graphene and graphene oxide: biofunctionalization and applications in biotechnology