Materials Literature
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Abstract The molecular structures of thermotropic liquid crystalline polymers, which have been synthesized systematically in recent years, are described according to the model of decoupling the molecular motions of the mesogenic groups and the polymer chain by inserting a flexible spacer. The molecular structure is re…
Abstract
Article Kinetics of metalloporphyrin formation with particular reference to the metal ion assisted mechanism was published on January 1, 1983 in the journal Pure and Applied Chemistry (volume 55, issue 1).
In this final review, a series of polymers which include aromatic rings and/or inorganic chain atoms are treated. Heat capacities of poly(4,4′-isopropylidenediphenylene carbonate), polyphenylenediamides, polyheteroarylenes, poly(dimethyl siloxane), poly(diethyl siloxane), poly(trimethylsilyl ethylene), poly(dimethylph…
The effect of grinding on the degree of crystallinity of cephalexin (CEX) powder was investigated. The intensities of the X-ray diffraction peaks of crystalline CEX decreased with increasing grinding time in an agate shaker mill, and after 4 h showed the same halo pattern as the noncrystalline solid (NC) obtained by t…
For a semi-flexible, nematic polymer, the Landau-de Gennes expansion for the free energy of the homogeneous melt is derived. The theory contains three parameters : the degree of polymerization, the inherent elasticity of the polymer chain, and the quadrupolar mean field between monomers. The dependence on chain length…
We study thin layers of colloidal crystals made of polystyrene balls (1.1 μm diameter) in aqueous suspension. These thin layers are produced by confining colloidal crystals between two glass planes, which act as repulsive and perfectly smooth boundaries at colloidal scales. When the two planes form a wedge, a continuo…
Description d'un essai de compression par choc dans lequel un echantillon est chauffe rapidement en utilisant une bobine d'induction a haute frequence et refroidi par de l'eau apres chaque choc, le but etant d'obtenir experimentalement les caracteristiques de contrainte d'ecoulement des aciers a faible teneur en carbo…
Abstract not Available.
Nancy S. Petersen, Linda L. Cook, Martha L. Stocking, IRT versus Conventional Equating Methods: A Comparative Study of Scale Stability, Journal of Educational Statistics, Vol. 8, No. 2 (Summer, 1983), pp. 137-156
Polymolybdates(VI) have been photochemically reduced to Mov in aqueous solutions containing acetic acid. Carbon dioxide, methane, and succinic acid were isolated as decomposition products of the acetic acid but the quantum yield of their formation was ca. 20 times smaller than that of Mov formation. E.s.r, spin-trappi…
Pitting potential was used recently to asses the aggressiveness of the biological species in the microbial corrosion of aluminum alloys in fuel-water systems. This parameter is analyzed here in relation to the electrolyte composition of the medium, especially with reference to chloride, nitrate, and phosphate levels.…
Four novel liquid crystal classes are presented, namely bi-, tri-, and tetracyclic ethanes, pyridazines, and tetracyclic chloro-diesters. Each class exhibits distinct physical characteristics, such as low viscosities η − 12 cP, low elastic ratios k33/k11 ∼ 1, large mesomorphic ranges −40°C. 250°C, large negative diele…
Les etats de spin de plusieurs complexes de fer(II) ont ete caracterises a partir de la variation de la susceptibilite magnetique entre 4 et 300 K
Simultaneous masking functions (signal level at threshold versus masker level) were obtained for equally intense maskers presented individually and in pairs. The signal was a 2.0-kHz sinusoid. The pairs of maskers were (1) two sinusoids with frequencies 1.9 and 2.1 kHz, (2) two narrow bands of noise (50 Hz wide) cente…
Abstract The depression of glass transition temperature in polystyrene and styrene/divinylbenzene networks, by the addition of ethylbenzene, ethyl acetate, and m ‐diethylbenzene, respectively, has been investigated by differential scanning calorimetry. The predictive quality of the Couchman–Karasz treatment for the co…
Using a simple hydrogenic scattering model, the matrix element with full phase information is derived for the ejection of K-shell electrons from atoms by an energetic electron beam. The scattering kinematics are defined and polar diagrams of the angular dependence of the ejected electron intensity are presented. The e…
Previous measurements of transient photoluminescence (PL) in a-As2S3 have indicated that the PL spectrum is extremely sensitive to the excitation photon energy. In the present paper we show that this sensitivity is also manifest in the total-light decay (TLD), the spectrally integrated PL intensity as a function of ti…
The role of a minor silicate eutectic liquid phase as a transport medium in sintering hot–pressed silicon nitride (β Si3N4) ceramics was identified in the 1970s. A similar mechanism is applicable to hot–pressed Si–Al–O–N ceramic alloys which offer an advantage in control of the final liquid volume and hence in superio…
Torrance et al. have made the interesting observation that several mixed-stack organic compounds undergo transitions from neutral states to ionic states as the temperature or pressure is varied. We examine a simple model of such transitions including Coulomb interaction and hybridization of neutral and ionic states. I…