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

Nitrogen plasma treatment of the dow Cyclotene 3022 surface and its reaction with evaporated copper

High-temperature stability of the mechanical and optical properties of Si-B-C-N films prepared by magnetron sputtering

Diamond-like carbon (DLC) coatings are frequently considered for biomedical applications due to their attractive tribo-mechanical properties combined with good biocompatibility. In the present work, DLC coatings have been deposited on 316L stainless steel (SS) substrates. The duplex approach consisted of surface nitriding in a radio frequency (RF) discharge for the reinforcement of SS-DLC bonding prior to DLC deposition (0.5 µm thick). Chemical composition and morphology of the nitrided SS were assessed by XPS and SEM, while depth-sensing indentation, ball-on-flat tribometry, and microscratch testing were used to determine the tribo-mechanical performance of the nitrided SS and of DLC coated SS samples. We found that the formation of a thick (∼1–2 µm), hard (15 GPa) metal nitride layer at the SS surface has a strong influence on enhancing the coating adhesion (critical load of 6.5 N) and wear resistance of DLC (wear factor 3–8 × 10−8 mm3 · N−1 · m−1 compared to 10−5 mm3 · N−1 · m−1 for nitrided SS).

Tribo-Mechanical Properties of DLC Coatings Deposited on Nitrided Biomedical Stainless Steel

Interaction of Cr, Ti, Al, Ag, Au, and Cu with Teflon PFA (polytetrafluoroethylene‐ co‐perfluoroalkoxy vinyl ether) and FEP (fluoroethylene propylene), and the effect of x‐ray irradiation on the metal/polymer interfaces, were studied using in situ x‐ray photoelectron spectroscopy (XPS) and mass spectrometry. Cr, Ti, and Al were found to react with both PFA and FEP, leading to polymer surface graphitization and formation of carbide and fluoride species, which are enhanced at higher metal thicknesses. On the other hand, evaporation of Au, Ag and Cu causes only a slight loss of fluorine, but no chemical interaction occurs. Post‐deposition x‐ray irradiation does not promote metal–polymer interactions, but it leads, in the case of reactive metals, to a pronounced increase of the C–CFn peak intensity, which rises with the metal thickness. A mechanism based on radical recombination reaction and accumulation of the small fragments, inside the metal film and/or near the metal/polymer interface, is proposed to explain this behavior. The metal XPS signal decreases upon x‐ray exposure, which is interpreted by diffusion of metals into the polymer matrix. The relative change in XPS signal is enhanced at longer x‐ray irradiations, but decreases at a higher metal thickness. This effect is most pronounced for Cu, Cr, and FEP.

Ludvik Martinu

Papers

Nitrogen plasma treatment of the dow Cyclotene 3022 surface and its reaction with evaporated copper

High-temperature stability of the mechanical and optical properties of Si-B-C-N films prepared by magnetron sputtering

Tribo-Mechanical Properties of DLC Coatings Deposited on Nitrided Biomedical Stainless Steel

X‐ray photoelectron spectroscopy study of x‐ray irradiated metal/fluoropolymer interfaces

Micromechanical characterisation of plasma treated polymer surfaces