Materials Literature
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The molecular structures of the hydrolyzates of γ-aminopropyl-triethoxysilane (γ-APS) were studied by Fourier transform infrared spectroscopy (FT-IR). The molecular structure of γ-APS is a function of the pH of the solution and the drying conditions. In the partially cured film, cast from a 20% by weight γ-APS aqueous…
Transient and dc photoconductivity measurements are presented for two low-mobility dielectrics, poly (vinylidene fluoride) and polyethylene terephthalate. In each case, the data are analyzed using the present models for dispersive transport, and the inadequacies of these theories when applied to these low-mobility die…
Chemisorbed atomic oxygen is the crucial surface species which selectively oxidises ethylene to ethylene oxide; adsorbed dioxygen plays no direct role in this reaction.
A general method for describing multimodal atomic densities is presented. It is based on series expansions of a harmonic Gaussian probability density function. The most suitable expansion is of the Gram-Charlier type; its Fourier transform can be easily inserted in a structure factor equation. This statistical method…
Microscopic examination of (NH4)2Cr2O7 crystallites, previously decomposed to measured extents, has given strong evidence that reaction proceeds through the intervention of a melt. This reaction has previously been accepted as occurring in the solid phase and the use of higher magnifications than were applied previous…
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…