Materials Literature
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Abstract The properties of polymer blends are largely determined by the morphological structure of the polymer combinations that are involved. In terms of extruder design, this means it is necessary to have models available for estimating the development of the morphology over the length of the screws. Since significa…
Pyrimidine bases are rapidly catabolized in growing plant tissues. The final enzyme of the catabolic pathway, beta-ureidopropionase (beta-UP; EC 3.5.1.6), was partially purified from the shoots of etiolated maize (Zea mays) seedlings. The enzyme had a K(m) for beta-ureidopropionate (the substrate derived from uracil)…
Intercalation complexes of the fluorescent dye coumarin and lamellar aluminosilicate hectorite have been prepared and studied. The nanocomplexes are characterized by molecular order and thermal stability. Optical quality films of multilayered nanocomposites of coumarin and hectorite were prepared by a layer-by-layer s…
The constitutional marriage between a classical thermotropic discotic molecule and carbohydrate-based amphiphiles (e.g., see Figure) is shown to result in hybrid compounds, where, for example, a triphenylene unit serves as the central core from which oligomethyleneoxy chains terminated with sugar residues radiate, whi…
Abstract We review recent attempts to elucidate the phenomenon of sonoluminescence in terms of fundamental principles. We focus mainly on the processes which generate the light, but other relevant facts, such as the bubble dynamics, must also be considered for the understanding of the physics involved. Our emphasis is…
The repressor proteins of the LacI/GalR family exhibit significant similarity in their secondary and tertiary structures despite less than 35% identity in their primary sequences. Furthermore, the core domains of these oligomeric repressors, which mediate dimerization, are homologous with the monomeric periplasmic bin…
A Green's function formalism is used to calculate self-consistently the temperature dependence of the layer polarization and the thickness dependence of the Curie temperature of thin ferroelectric transverse Ising films in the ferroelectric phase, T ≤ Tc.
A continuous culture experiment was conducted with the marine diatom Ditylum brightwellii to assess the photo-oxidative effects of transition from dim light to high light at three successive levels. The focus was on temporary stress by ambient UVA at the water surface, via a simulation of the periodic ascent of diatom…
A hydroxyapatite/collagen/chondroitin sulfate nanocomposite that partly mimicked the composition of cartilage was synthesized through a novel precipitation method, using a calcium hydroxide suspension and phosphoric acid solutions that contained several mixing ratios of type II collagen (Col) and chondroitin sulfate (…
Photoluminescence properties were measured for vacuum-deposited thin films of magnesium, chloroaluminum, bromoaluminum, and metal-free phthalocyanines (MgPc, AlClPc, AlBrPc, and H 2 Pc). For MgPc, AlClPc, and AlBrPc, besides the as-deposited films, phase-transformed films having red-shifted absorption bands at approxi…
Ionic motion in a double-well local potential can be cast theoretically in the language of cooperative magnetism. In this modern approach, the potential minima referred to are with respect to a generalized displacement co-ordinate describing the motion of all ions in a unit cell. The more traditional approach for pota…
This chapter discusses structural crystallography and phase transitions. If all atoms in a crystal were exactly at their official lattice sites and there were no order-disorder ambiguity as to the position of these sites, then all the measurable physical quantities associated with the crystal would be exactly periodic…
The surface properties of materials are often the important determinants of their usefulness, and many of the chemical treatments now in use are aimed at modifying these properties. The important properties of polymer materials such as adhesion, friction, wetting, penetrability and biological compatibility are strongl…
Synthetic diamond radiation detectors made of ultrahigh-purity type IIa diamond crystals were developed. The diamond crystals, which were grown by high-pressure and high-temperature synthesis, contained less nitrogen impurity than 0.1 ppm, i.e., 1/10 of conventional type IIa diamond crystals. Since the ultrahigh-purit…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTPhotoinduced 1,3-Proton Shift in Methyldithiepines as a Potential Way of Modulating HyperpolarizabilitiesYongqin Wan, Alexei Kurchan, and Andrei KutateladzeView Author Information Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208 %[email pro…
The thermal stability of amorphous carbon ( a -C and a -C:H) has been studied by ellipsometry and spectrophotometry in the visible and near-UV range (1.5–5.6 eV). The dielectric function of amorphous carbon has been derived and analyzed using the Kramers-Kronig technique. The conventional analytical approach is shown…
In this work we report preliminary results on the properties of a non-polar bicyclohexane nematic liquid crystal. Moreover, its binary mixtures both with a low viscosity phenylcyclohexane and with a normal polar nematic liquid have been investigated. The elastic, viscous and electro-optical properties of these compoun…
Single-crystal-to-single-crystal reactions of a series of bifunctional styrylyl]pyrylium salts have been investigated using long wavelength irradiation conditions. The dimerization of the reactive olefins in the solid state was followed by X-ray crystallography. The results demonstrate that a homogeneous photoreaction…
A recently developed technique which allows a study of the localization of plastic flow during high-speed torsion testing is briefly described. High-speed photographs showing successive stages in the deformation of three rolled homogeneous armour (RHA) steel specimens are presented. Three stages are identified corresp…
The suspension polymerization of styrene in water with hydroxyapatite and calcium carbonate as Pickering emulsifiers and sodium dodecylbenzenesulfonate (NaDDBS) and poly(vinylpyrrolidone) (PVP) as surfactants was investigated. The adsorption of NaDDBS and PVP at the surface of the solids, the surface tensions of the a…