Materials Literature
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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolyhaloporphyrins: Unusual Ligands for Metals and Metal-Catalyzed OxidationsDavid Dolphin, Teddy G. Traylor, and Lily Y. XieView Author Information Department of Chemistry, University of British Columbia, Vancouver, Canada V6T 1Z1, and Department of Chemistry, University of…
We examine substrate/overlayer experiments and the equations commonly used to quantify overlayer thicknesses. Comparisons with accurate Monte-Carlo simulations show that using attenuation lengths (rather than inelastic mean free paths) eliminates most of the error due to elastic scattering without increasing the compl…
The structures of the four metal dioxides GeO 2 , SnO 2 , RuO 2 and IrO 2 (germanium, tin, ruthenium and iridium dioxides, respectively) have been redetermined by Rietveld refinement from neutron diffraction powder data. The four dioxides all adopt the rutile-type structure, space group P 42/ mnm (no. 136), with a = 4…
The access of guest species to the binding sites of adsorbent determines the metal‐binding capacity of materials, which is important for example in environmental remediation efforts. It is shown that MP‐HMS, the mercaptopropylsilane‐functionalized derivative of the molecualr sieve HMS, with its regular pore structure…
A new multidimensional scoring approach for identifying and distinguishing trimeric and dimeric coiled coils is implemented in the MultiCoil program. The program extends the two-stranded coiled-coil prediction program PairCoil to the identification of three-stranded coiled coils. The computations are based upon data g…
In this feature article, syntheses of nanosized particles by using colloidal assemblies as a template are described. We asked ourselves the following question: What parameters play a role in the control of the size, shape, and polydispersity? We know that parameters such as the shape of colloidal assemblies, the hydra…
The gas transport of hydrogen, oxygen, nitrogen, carbon dioxide, and methane gases in a series of poly(aryl ether ketone)s was examined. The polymer membranes have a wide range of permeability coefficients and permselectivity coefficients, showing excellent gas-transport properties. The enhanced interchain interaction…
Pineapple leaf fiber (PALF) which is rich in cellulose, relatively inexpensive, and abundantly available has the potential for polymer reinforcement. The present study investigated the tensile, flexural, and impact behavior of PALF-reinforced polyester composites as a function of fiber loading, fiber length, and fiber…
The transport properties of carbon dioxide, water, and different organic solvents in bacterial poly(3-hydroxybutyrate) (PHB) at 30°C were investigated. CO2 sorption was measured by the gravimetric method using a recording microbalance at subatmospheric pressures. Results were adequately interpreted in terms of Henry's…
Wood fiber-reinforced composites were prepared from poly(hydroxybutyrate) (PHB) and poly(hydroxybutyrate-co-hydroxyvalerate) (PHB/HV) copolymers containing 9 and 24% valerate. The effects of fibers on crystallization were investigated. Thermomechanical pulp, bleached Kraft fibers, and microcrystalline cellulose filler…
Pineapple leaf fiber (PALF) which is rich in cellulose, relatively inexpensive, and abundantly available has the potential for polymer reinforcement. The present study investigated the tensile, flexural, and impact behavior of PALF-reinforced polyester composites as a function of fiber loading, fiber length, and fiber…
The synthesis, properties and applications of polypyrrole (PPy), a representative of conducting polymers, are reviewed. Chemical and electrochemical methods for the preparation of PPy and PPy films and the effect of the reaction conditions on the properties of the polymer produced are discussed. The mechanisms of elec…
A sonoluminescing bubble has been modeled as a thermally conducting, partially ionized, two-component plasma. The model shows that the measured picosecond pulse widths are due to electron conduction and the rapidly changing opacity of the plasma and that these mechanisms are also responsible for the absence of an “aft…
We present a systematical method for obtaining analytical long-range embedded-atom potentials based on the lattice-inversion method. The potentials converge faster (exponentially) than Sutton and Chen's power-law potentials (Philos. Mag. Lett. 61, 2480(1990)). An interesting relationship between the embedded-atom meth…
Dense periodic arrays of holes and dots have been fabricated in a silicon nitride–coated silicon wafer. The holes are 20 nanometers across, 40 nanometers apart, and hexagonally ordered with a polygrain structure that has an average grain size of 10 by 10. Spin-coated diblock copolymer thin films with well-ordered sphe…
BACKGROUND: Genetically modified cells have been used in several animal models for the in vivo delivery of therapeutic proteins. One of the problems encountered is early cell death after the implantation of cells. MATERIALS AND METHODS: To improve the survival of implanted cells, we have developed a system in which tr…
Particle conservation equations for electrons and positive ions, together with Poisson"s equation to account for space-charge effects on the electric field, have been solved for the electrode sheath regions of electric arcs. For thermionic cathodes and the anode, we find that the ambipolar diffusion approximation is g…
Electron scattering cross sections (elastic, rotational and vibrational excitation) for a number of atomic and (relatively) simple molecular systems are examined. Particular reference is made to the level of agreeement which is obtained from the application of the completely different measurement philosophies embodied…
We have performed a relativistic treatment at low energy of electron–argon scattering which includes both polarisation and dynamic distortion effects. Our results are in excellent agreement with the experimentally derived momentum transfer cross section and scattering length, as well as with very recent measurements o…
Diffusion of symmetric diblock copolymer chains in macroscopically oriented lamellar block copolymers are studied in a molecular dynamics simulation. Results for diffusion constant both parallel $D_\parallel$ and perpendicular $D_\perp$ to the lamellar planes are compared to results in the disordered one phase region.…