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

The escalating level of atmospheric carbon dioxide is one of the most pressing environmental concerns of our age. Carbon capture and storage (CCS) from large point sources such as power plants is one option for reducing anthropogenic CO(2) emissions; however, currently the capture alone will increase the energy requirements of a plant by 25-40%. This Review highlights the challenges for capture technologies which have the greatest likelihood of reducing CO(2) emissions to the atmosphere, namely postcombustion (predominantly CO(2)/N(2) separation), precombustion (CO(2)/H(2)) capture, and natural gas sweetening (CO(2)/CH(4)). The key factor which underlies significant advancements lies in improved materials that perform the separations. In this regard, the most recent developments and emerging concepts in CO(2) separations by solvent absorption, chemical and physical adsorption, and membranes, amongst others, will be discussed, with particular attention on progress in the burgeoning field of metal-organic frameworks.

Carbon Dioxide Capture: Prospects for New Materials

This paper presents a review of living radical polymerization achieved with thiocarbonylthio compounds [ZC(=S)SR] by a mechanism of reversible addition–fragmentation chain transfer (RAFT). Since we first introduced the technique in 1998, the number of papers and patents on the RAFT process has increased exponentially as the technique has proved to be one of the most versatile for the provision of polymers of well defined architecture. The factors influencing the effectiveness of RAFT agents and outcome of RAFT polymerization are detailed. With this insight, guidelines are presented on how to conduct RAFT and choose RAFT agents to achieve particular structures. A survey is provided of the current scope and applications of the RAFT process in the synthesis of well defined homo-, gradient, diblock, triblock, and star polymers, as well as more complex architectures including microgels and polymer brushes.

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Living radical polymerization by the RAFT process

This article reviews the progress made in CO2 separation and capture research and engineering. Various technologies, such as absorption, adsorption, and membrane separation, are thoroughly discussed. New concepts such as chemical-looping combustion and hydrate-based separation are also introduced briefly. Future directions are suggested. Sequestration methods, such as forestation, ocean fertilization and mineral carbonation techniques are also covered. Underground injection and direct ocean dump are not covered.

Progress in carbon dioxide separation and capture: a review.

The continuous assembly of polymers (CAP) is used to fabricate tailored nanocoatings on a wide variety of substrates. Ring-opening metathesis polymerization (ROMP) is used to mediate the CAP process (CAPROMP) to assemble specifically designed macromolecules into nanoengineered crosslinked films. Different films composed of single or multiple macromolecules are used to tune the surface wetting characteristics on various planar substrates, including porous substrates such as filter paper and cotton, and non-porous subtrates such as aluminium foil and glass. By judicious selection of the macromolecules, these substrates, which are hydrophilic in nature, can be rendered (super)hydrophobic. The robustness of the ROMP catalysts and the reinitiation ability of the CAPROMP approach allow the production of layered multicomponent amphiphilic films with on-demand switchable wettability. Such functional nanocoatings can be potentially applied as self-cleaning surfaces, as waterproof woven fabrics, and for the next generation of microelectronic devices. The continuous assembly of polymers (CAP) is utilized to fabricate advanced functional nanocoatings with tunable film compositions on various substrates. The versatility of CAP is demonstrated by the formation of (super)hydrophobic coatings on hydrophilic substrates including paper, cotton, aluminium foil, and glass. Moreover, by simple alternate dipping in hydrophilic and hydrophobic macro-crosslinker solutions, novel stratified amphiphilic films can be assembled via CAP. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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Super)hydrophobic and Multilayered Amphiphilic Films Prepared by Continuous Assembly of Polymers

Insights into the mechanochromism of spiropyran elastomers

A rapid and facile preparation of novel macroporous silicone-based cryogels via photo-induced thiol–ene click chemistry

Wheat gluten-based renewable and biodegradable polymer materials with enhanced hydrophobicity by using epoxidized soybean oil as a modifier

The use of higher-functionality oligomers of glutaraldehyde on network formation was investigated and compared with glutaraldehyde monomer in step-growth reactions. The effect of using such oligomers in network formation depends on the stoichiometry, which alters either the branching or both the branching and crosslinking of the network. This was demonstrated in the properties of poly(vinyl alcohol) (PVA) networks crosslinked with glutaraldehyde using cryogenic scanning electron microscopy, water swelling studies, and protein transfer across membranes. General guidelines were given for the proper use of glutaraldehyde solutions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 780–792, 2005

Greg G. Qiao

Papers

Super)hydrophobic and Multilayered Amphiphilic Films Prepared by Continuous Assembly of Polymers

Insights into the mechanochromism of spiropyran elastomers

A rapid and facile preparation of novel macroporous silicone-based cryogels via photo-induced thiol–ene click chemistry

Wheat gluten-based renewable and biodegradable polymer materials with enhanced hydrophobicity by using epoxidized soybean oil as a modifier

Effect of “glutaraldehyde” functionality on network formation in poly(vinyl alcohol) membranes