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

This article reviews the basic theoretical aspects of graphene, a one-atom-thick allotrope of carbon, with unusual two-dimensional Dirac-like electronic excitations. The Dirac electrons can be controlled by application of external electric and magnetic fields, or by altering sample geometry and/or topology. The Dirac electrons behave in unusual ways in tunneling, confinement, and the integer quantum Hall effect. The electronic properties of graphene stacks are discussed and vary with stacking order and number of layers. Edge (surface) states in graphene depend on the edge termination (zigzag or armchair) and affect the physical properties of nanoribbons. Different types of disorder modify the Dirac equation leading to unusual spectroscopic and transport properties. The effects of electron-electron and electron-phonon interactions in single layer and multilayer graphene are also presented.

/pdf/the-electronic-properties-of-graphene-2siyzsnf5w.pdf

The electronic properties of graphene

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

Gas sensors operate by a variety of fundamentally different mechanisms1,2,3,4,5,6,7,8,9,10,11,12,13,14. Ionization sensors13,14 work by fingerprinting the ionization characteristics of distinct gases, but they are limited by their huge, bulky architecture, high power consumption and risky high-voltage operation. Here we report the fabrication and successful testing of ionization microsensors featuring the electrical breakdown of a range of gases and gas mixtures at carbon nanotube tips. The sharp tips of nanotubes generate very high electric fields at relatively low voltages, lowering breakdown voltages several-fold in comparison to traditional electrodes, and thereby enabling compact, battery-powered and safe operation of such sensors. The sensors show good sensitivity and selectivity, and are unaffected by extraneous factors such as temperature, humidity, and gas flow. As such, the devices offer several practical advantages over previously reported nanotube sensor systems15,16,17. The simple, low-cost, sensors described here could be deployed for a variety of applications, such as environmental monitoring, sensing in chemical processing plants, and gas detection for counter-terrorism.

/pdf/miniaturized-gas-ionization-sensors-using-carbon-nanotubes-59fz6qz9fs.pdf

Miniaturized gas ionization sensors using carbon nanotubes

Application of Carbon Nanotubes as Supports in Heterogeneous Catalysis

1. Bulk Metal and Ceramics Nanocomposites (Pulickel M. Ajayan).1.1 Introduction.1.2 Ceramic/Metal Nanocomposites.1.2.1 Nanocomposites by Mechanical Alloying.1.2.2 Nanocomposites from SolGel Synthesis.1.2.3 Nanocomposites by Thermal Spray Synthesis.1.3 Metal Matrix Nanocomposites.1.4 Bulk Ceramic Nanocomposites for Desired Mechanical Properties.1.5 Thin-Film Nanocomposites: Multilayer and Granular Films.1.6 Nanocomposites for Hard Coatings.1.7 Carbon Nanotube-Based Nanocomposites.1.8 Functional Low-Dimensional Nanocomposites.1.8.1 Encapsulated Composite Nanosystems.1.8.2 Applications of Nanocomposite Wires.1.8.3 Applications of Nanocomposite Particles.1.9 Inorganic Nanocomposites for Optical Applications.1.10 Inorganic Nanocomposites for Electrical Applications.1.11 Nanoporous Structures and Membranes: Other Nanocomposites.1.12 Nanocomposites for Magnetic Applications.1.12.1 Particle-Dispersed Magnetic Nanocomposites.1.12.2 Magnetic Multilayer Nanocomposites.1.12.2.1 Microstructure and Thermal Stability of Layered Magnetic Nanocomposites.1.12.2.2 Media Materials.1.13 Nanocomposite Structures having Miscellaneous Properties.1.14 Concluding Remarks on Metal/Ceramic Nanocomposites.2. Polymer-based and Polymer-filled Nanocomposites (Linda S. Schadler).2.1 Introduction.2.2 Nanoscale Fillers.2.2.1 Nanofiber or Nanotube Fillers.2.2.1.1 Carbon Nanotubes.2.2.1.2 Nanotube Processing.2.2.1.3 Purity.2.2.1.4 Other Nanotubes.2.2.2 Plate-like Nanofillers.2.2.3 Equi-axed Nanoparticle Fillers.2.3 Inorganic FillerPolymer Interfaces.2.4 Processing of Polymer Nanocomposites.2.4.1 Nanotube/Polymer Composites.2.4.2 Layered FillerPolymer Composite Processing.2.4.2.1 Polyamide Matrices.2.4.2.2 Polyimide Matrices.2.4.2.3 Polypropylene and Polyethylene Matrices.2.4.2.4 Liquid-Crystal Matrices.2.4.2.5 Polymethylmethacrylate/Polystyrene Matrices.2.4.2.6 Epoxy and Polyurethane Matrices.2.4.2.7 Polyelectrolyte Matrices.2.4.2.8 Rubber Matrices.2.4.2.9 Others.2.4.3 Nanoparticle/Polymer Composite Processing.2.4.3.1 Direct Mixing.2.4.3.2 Solution Mixing.2.4.3.3 In-Situ Polymerization.2.4.3.4 In-Situ Particle Processing Ceramic/Polymer Composites.2.4.3.5 In-Situ Particle Processing Metal/Polymer Nanocomposites.2.4.4 Modification of Interfaces.2.4.4.1 Modification of Nanotubes.2.4.4.2 Modification of Equi-axed Nanoparticles.2.4.4.3 Small-Molecule Attachment.2.4.4.4 Polymer Coatings.2.4.4.5 Inorganic Coatings.2.5 Properties of Composites.2.5.1 Mechanical Properties.2.5.1.1 Modulus and the Load-Carrying Capability of Nanofillers.2.5.1.2 Failure Stress and Strain Toughness.2.5.1.3 Glass Transition and Relaxation Behavior.2.5.1.4 Abrasion and Wear Resistance.2.5.2 Permeability.2.5.3 Dimensional Stability.2.5.4 Thermal Stability and Flammability.2.5.5 Electrical and Optical Properties.2.5.5.1 Resistivity, Permittivity, and Breakdown Strength.2.5.5.2 Optical Clarity.2.5.5.3 Refractive Index Control.2.5.5.4 Light-Emitting Devices.2.5.5.5 Other Optical Activity.2.6 Summary.3. Natural Nanobiocomposites, Biomimetic Nanocomposites, and Biologically Inspired Nanocomposites (Paul V. Braun).3.1 Introduction.3.2 Natural Nanocomposite Materials.3.2.1 Biologically Synthesized Nanoparticles.3.2.2 Biologically Synthesized Nanostructures.3.3 Biologically Derived Synthetic Nanocomposites.3.3.1 Protein-Based Nanostructure Formation.3.3.2 DNA-Templated Nanostructure Formation.3.3.3 Protein Assembly.3.4 Biologically Inspired Nanocomposites.3.4.1 Lyotropic Liquid-Crystal Templating.3.4.2 Liquid-Crystal Templating of Thin Films.3.4.3 Block-Copolymer Templating.3.4.4 Colloidal Templating.3.5 Summary.4. Modeling of Nanocomposites (Catalin Picu and Pawel Keblinski).4.1 Introduction The Need For Modeling.4.2 Current Conceptual Frameworks.4.3 Multiscale Modeling.4.4 Multiphysics Aspects.4.5 Validation.Index.

Nanocomposite science and technology

Carbon nanotubes have attracted the fancy of many scientists worldwide. The small dimensions, strength and the remarkable physical properties of these structures make them a very unique material with a whole range of promising applications. In this review we describe some of the important materials science applications of carbon nanotubes. Specifically we discuss the electronic and electrochemical applications of nanotubes, nanotubes as mechanical reinforcements in high performance composites, nanotube-based field emitters, and their use as nanoprobes in metrology and biological and chemical investigations, and as templates for the creation of other nanostructures. Electronic properties and device applications of nanotubes are treated elsewhere in the book. The challenges that ensue in realizing some of these applications are also discussed from the point of view of manufacturing, processing, and cost considerations.

Pulickel M. Ajayan

Papers

Miniaturized gas ionization sensors using carbon nanotubes

Application of Carbon Nanotubes as Supports in Heterogeneous Catalysis

Nanocomposite science and technology

Applications of Carbon Nanotubes

Catalytic performance of Pt nanoparticles on reduced graphene oxide for methanol electro-oxidation