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

Department of Materials Science, University of Patras, 26504 Rio Patras, Greece, Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vass. Constantinou Avenue, 116 35 Athens, Greece, Institut de Biologie Moleculaire et Cellulaire, UPR9021 CNRS, Immunologie et Chimie Therapeutiques, 67084 Strasbourg, France, and Dipartimento di Scienze Farmaceutiche, Universita di Trieste, Piazzale Europa 1, 34127 Trieste, Italy

Chemistry of Carbon Nanotubes

Carbon nanotube–polymer composites: Chemistry, processing, mechanical and electrical properties

and Applications of Fullerenes, Carbon Dots, Nanotubes, Graphene, Nanodiamonds, and Combined Superstructures Vasilios Georgakilas,† Jason A. Perman,‡ Jiri Tucek,‡ and Radek Zboril*,‡ †Material Science Department, University of Patras, 26504 Rio Patras, Greece ‡Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacky University in Olomouc, 17 listopadu 1192/12, 771 46 Olomouc, Czech Republic

Broad family of carbon nanoallotropes: classification, chemistry, and applications of fullerenes, carbon dots, nanotubes, graphene, nanodiamonds, and combined superstructures.

The utilization of plant oil renewable resources as raw materials for monomers and polymers is discussed and reviewed. In an age of increasing oil prices, global warming and other environmental problems (e.g. waste) the change from fossil feedstock to renewable resources can considerably contribute to a sustainable development in the future. Especially plant derived fats and oils bear a large potential for the substitution of currently used petrochemicals, since monomers, fine chemicals and polymers can be derived from these resources in a straightforward fashion. The synthesis of monomers as well as polymers from plant fats and oils has already found some industrial application and recent developments in this field offer promising new opportunities, as is shown within this contribution. (138 references.)

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Plant oil renewable resources as green alternatives in polymer science

Polymer composites containing variable amounts of multiwalled carbon nanotubes (MWNTs) have been prepared using solution dispersion and melt-shear mixing Various polymer composites with 1 wt % MWNTs have been found to dissolve homogeneously in organic solvents The amount of polymer coated or wrapped MWNTs dissolved in the solution was quantified using UV−vis absorbance at 500 nm and the concentration ratio of [MWNTs]solution/[MWNTs]composite was close to 1 A nonspecific polymer adsorption through multiple-weak molecular interactions of CH groups with MWNTs in the composites has been identified through FTIR spectroscopy The composites of polybutadiene with different wt % of MWNTs showed slight changes in the CH bending vibrations, indicating the presence of intermolecular CH−π interactions The dissolution of various polymer composites containing low concentration of MWNTs in organic solvents was attributed to polymer coating on the MWNTs via noncovalent and nonspecific CH−π interactions The dissoluti

/pdf/noncovalent-and-nonspecific-molecular-interactions-of-3l2dvcz21t.pdf

Noncovalent and Nonspecific Molecular Interactions of Polymers with Multiwalled Carbon Nanotubes

Single- and multiwalled carbon nanotubes have been covalently functionalized with free-base porphyrin. The quantity of porphyrin linked to the surface was determined from thermogravimetric and UV−vis analysis. A reversible protonation equilibrium between the attached porphyrin and the residual acid groups of the carbon nanotubes has been identified. Steady-state fluorescence emission spectrum of the solutions of porphyrin-linked carbon nanotubes shows that the porphyrins act as energy absorbing and electron transferring antennae, and the carbon nanotubes act as efficient electron acceptors. The porphyrin-linked carbon nanotubes show 95−100% emission quenching, indicating a fast photoinduced electron transfer.

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Durairaj Baskaran

Papers

Noncovalent and Nonspecific Molecular Interactions of Polymers with Multiwalled Carbon Nanotubes

Carbon nanotubes with covalently linked porphyrin antennae: photoinduced electron transfer.

Anionic vinyl polymerization—50 years after Michael Szwarc

Strategic developments in living anionic polymerization of alkyl (meth)acrylates

Hyperbranched polymers from divinylbenzene and 1,3-diisopropenylbenzene through anionic self-condensing vinyl polymerization