Materials Literature
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The development, characterization, and exploitation of novel materials based on the assembly of molecular components is an exceptionally active and rapidly expanding field. For this reason, the topic of molecule-based materials (MBMs) was chosen as the subject of a workshop sponsored by the Chemical Sciences Division…
Applications of structural databases in the protein crystallographic structure determination process are reviewed, using mostly examples from work carried out by the authors. Four application areas are discussed: model building, model refinement, model validation and model analysis.
The use of self‐reinforcement by larger elongated grains in silicon nitride ceramics requires judicious control of the microstructure to achieve high steady‐state toughness and high fracture strength. With a distinct bimodal distribution of grain diameters, such as that achieved by the addition of 2% rodlike seeds, th…
We present results on the magnetic reversal process in epitaxial Sm-Co(11\ifmmode\bar\else\textasciimacron\fi{}00)/TM (TM=Fe,Co) bilayer films prepared via magnetron sputtering. The magnetically hard Sm-Co films have 20-T uniaxial anisotropy and coercivities >3 T at room temperature, that double on cooling, as dete…
We describe a database of protein structure alignments for homologous families. The database HOMSTRAD presently contains 130 protein families and 590 aligned structures, which have been selected on the basis of quality of the X-ray analysis and accuracy of the structure. For each family, the database provides a struct…
Large cell-sized anodic porous alumina with long-range ordering was fabricated using phosphoric acid solution. Self-ordering of the anodic alumina took place under long-period constant voltage anodization at 195 V, which generated the self-ordered anodic porous alumina with a cell size of 500 nm.
The properties of cellulose microcrystals and their colloidal suspensions obtained by acid treatments of native cellulose have been investigated. Bleached softwood kraft pulp was treated with 65% (w/w) sulfuric acid or 4 N hydrochloric acid and the resulting particle morphology and flow properties of the aqueous suspe…
The formation of continuous mesoporous silica films with large periodic cage and pore structures is reported here. The authors use low-cost commercially available triblock copolymers and poly(ethylene oxide) non-ionic surfactants as the structure-directing agents in conjunction with dip-coat processing. In the Figure…
We discuss the deformation of a curved interface between solid phases, assuming small strains in the bulk phases and neglecting accretion at the interfaces. Such assumptions are relevant to the deformation of solid microstructures when atomic diffusion and the formation of defects such as dislocations are negligible.…
The synthesis, spectroscopy, and fluorescence quenching behavior of pentiptycene-derived phenyleneethynylene polymers, 1 − 3, are reported. The incorporation of rigid three-dimensional pentiptycene moieties into conjugated polymer backbones offers several design advantages for solid-state (thin film) fluorescent senso…
Poly(acrylic acid)-silica composites have been prepared by two different methods and thermally characterized. The glass transition temperature (Tg) of the PAA-SiO2 system prepared by mixture method was found to be 120°C irrespective of the type and amounts of silica involved in this work. However, the Tg varied betwee…
A comparative study has been made of the crosslinking of plasticized PVC by grafting of γ-aminopropyltriethoxysilane (ASi) and sodium γ-mercaptopropyltrimethoxysilane (NaMSi) during processing. The influence of type of reagent and concentration, and the rheological behavior were investigated to obtain a crosslinked ma…
Nitric oxide is formed during the combustion of fossil fuels and is subsequently oxidized in the atmosphere to NO 2 . The increasing knowledge of pollution problems arising from NO x had led to the introduction of stringent environmental regulations concerning NO x emissions that in most cases, cannot be met by the on…
The essential work of the fracture (EWF) method was employed to determine the fracture performance of thermoplastic polypropylene (PP) elastomers. Three types of elastomeric polypropylene (ELPP) of homo- and copolymer nature based on different catalysts were involved in this study. Tests were carried out in both I and…
Poly(oxyethylene)-dicarboxylic acids were obtained in high yields by room temperature oxidation of poly(ethylene glycol)s of molecular weights in the 4000–100,000 range using Jone's reagent (CrO3 and H2SO4) as the oxidizing agent. Oxidation by-products from the reaction mixture were eliminated by adsorbing chromium sa…
The effects of shear flow, temperature, and gel concentration on the rheological behavior of the ultrahigh-molecular-weight polyethylene (UHMWPE) gel in gel spinning process were investigated. The gel point was determined using parallel plate rheometry in rotation mode with controlled stress. Likewise, the flow curves…
Two crystalline structures for nylon 5,6 have been studied by transmission electron microscopy, electron diffraction, and X-ray diffraction. A γ form or an α-like phase can be obtained as a function of the method used to prepare the sample. Structural modeling and energy calculations have been carried out for the seco…
The photooxidative degradation of a TiO 2 -blended poly(vinyl chloride) (PVC) film and other PVC specimens was carried out under UV light and under solar exposure to test the feasibility that such polymeric materials can be mineralized. The effects of the degree of polymerization and the presence of a plasticizer ( o…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTDirect Evidence for Confinement of Junctions to Lines in an 3 Miktoarm Star Terpolymer Microdomain StructureStella Sioula, Nikos Hadjichristidis, and Edwin L. ThomasView Author Information Department of Chemistry, University of Athe…
The applicability of the Hoffman−Weeks (HW) linear extrapolation for the determination of equilibrium melting temperatures of polymers is critically reviewed. In the first paper of this series, it is shown that the linear extrapolation of observed melting temperatures cannot, in general, provide a reliable estimate of…