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

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

Metal Oxides and Oxysalts as Anode Materials for Li Ion Batteries

Noble metal nanoparticles are capable of confining resonant photons in such a manner as to induce coherent surface plasmon oscillation of their conduction band electrons, a phenomenon leading to two important properties. Firstly, the confinement of the photon to the nanoparticle's dimensions leads to a large increase in its electromagnetic field and consequently great enhancement of all the nanoparticle's radiative properties, such as absorption and scattering. Moreover, by confining the photon's wavelength to the nanoparticle's small dimensions, there exists enhanced imaging resolving powers, which extend well below the diffraction limit, a property of considerable importance in potential device applications. Secondly, the strongly absorbed light by the nanoparticles is followed by a rapid dephasing of the coherent electron motion in tandem with an equally rapid energy transfer to the lattice, a process integral to the technologically relevant photothermal properties of plasmonic nanoparticles. Of all the possible nanoparticle shapes, gold nanorods are especially intriguing as they offer strong plasmonic fields while exhibiting excellent tunability and biocompatibility. We begin this review of gold nanorods by summarizing their radiative and nonradiative properties. Their various synthetic methods are then outlined with an emphasis on the seed-mediated chemical growth. In particular, we describe nanorod spontaneous self-assembly, chemically driven assembly, and polymer-based alignment. The final section details current studies aimed at applications in the biological and biomedical fields.

Gold Nanorods: From Synthesis and Properties to Biological and Biomedical Applications

Transparent conductors as solar energy materials: A panoramic review

The use of polymer instead of glass is increasingly frequent, ranging from ophthalmic applications to electronic devices, displays and others In the case of optical interference filters on plastic substrates (eg, antireflective coatings) the performance of the device is limited by the coating-substrate compatibility (eg, thermal expansion coefficient of the substrate about 100 times that of glass) In the present work, we demonstrate significantly improved resistance to temperature and humidity variation and higher elastic recovery of organic-inorganic SiO2 and ZrO2 coatings compared to their inorganic counterparts Specifically, organic-inorganic coatings prepared by ion beam assisted chemical vapour deposition (IBACVD) show a higher thermal expansion (10− 5 K− 1) close to that of polymer substrates (10− 4 K− 1 for CR-39) and a relatively high H/E ratio (as up to 016) We show that both individual organic-inorganic layers as well as complete antireflective stacks exhibit a higher durability following accelerated environmental tests including exposure to high temperature/high humidity, UV and solar radiation, as well as a saline solution

Stability and performance of organic-inorganic thin films on polymer substrates

Active Carbon, used for example in chemical protection devices such as gas mask canisters, can adsorb an extremely wide range of hazardous compounds. Unfortunately, this {open_quotes}universal{close_quotes} adsorption includes ubiquitous water molecules, which can results in saturation and premature loss of efficacy. The purpose of this work has been to treat active carbon granules and carbon-impregnated textile with appropriate low pressure plasmas, so as to render the carbon surface {open_quotes}hydrophobic{close_quotes} while minimally affecting its ability to adsorb toxic gases or vapors (simulated here by CCl{sub 4}). The best results have been achieved using plasma polymerization of fluorocarbon or organosilicon thin films onto the active carbon surface. While this results in some loss of BET surface area, water adsorption can be reduced two-fold or more, with < 10% loss in CCl{sub 4} uptake.

Modification of active carbon by hydrophobic plasma polymers

Evaluation of plasma-deposited protective coatings for spacecraft applications

The energy and the flux of impinging ions are important factors which determine the properties of deposited films and of exposed surfaces (microstructure, density, hardness, roughness, stress, chemical structure, adhesion etc.). In the present work, we use a multigrid retarding field analyzer to study ion bombardment characteristics in two different systems: a pulsed microwave plasma reactor, and a cold cathode ion source. We have found that the ion energy distribution functions (IEDF) possess specific features for each mode of operation: we evaluate the shape and the maximum and the mean ion energies of the IEDF for different gases such as Ar and N2. These ion characteristics are correlated with surface restructuring of differently treated polymers (polycarbonate and polyethylene terephthalate), analyzed by XPS.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/AE0425EA20C725A4E89EFB7192CD68DB/S1946427400173191a.pdf/div-class-title-effect-of-ion-bombardment-in-polymer-surface-modification-comparison-of-pulsed-high-frequency-plasma-and-ion-beam-div.pdf

Effect of ion Bombardment in Polymer Surface Modification: Comparison of Pulsed High Frequency Plasma and ion Beam

Optical properties of silicon-based coatings are investigated in which the refractive index n is varied gradually (SiOxNy with continuously changing x and y) or in discrete steps (SiO2/SiN1.3 multilayers). The films are prepared at room temperature in a dual- mode microwave/radiofrequency (MW/RF) plasma in which the substrates are placed on an RF powered substrate holder, while simultaneously exposed to a MW discharge. The films' composition is controlled by the working gas mixture using SiH4, NH3 and N2O, and their microstructure, such as packing density and interface roughness, is controlled independently by varying the energy and the flux of bombarding ions. The deposition process is monitored in-situ by optical emission spectroscopy measurements which are related to the compositional depth profiles provided by elastic recoil detection analysis.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Ludvik Martinu

Papers

Stability and performance of organic-inorganic thin films on polymer substrates

Modification of active carbon by hydrophobic plasma polymers

Evaluation of plasma-deposited protective coatings for spacecraft applications

Effect of ion Bombardment in Polymer Surface Modification: Comparison of Pulsed High Frequency Plasma and ion Beam

Properties of multilayer and graded index Si-based coatings deposited in dual-frequency plasma