Materials Literature
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Abstract Fluorine doped silica samples have been investigated by Raman spectroscopy. The results obtained allow us to propose a model for dopant incorporation in the silica network, involving the formation of SiO 3 F tetrahedron. A relationship between the intensity of the ν(Si‐F) stretching vibration band and the ref…
X-ray diffraction studies on samples of 4′-Pentyloxy-4-Cyanobiphenyl and 4′-Octyloxy-4-Cyanobiphenyl over the entire mesomorphic range are reported in this paper. A magnetic field was used to align samples. The orientational distribution functions f(β) have been calculated from the angular distribution of X-ray intens…
Abstract The fracture behavior of human hair has been investigated with a view toward delineating fracture mechanisms that lead to different types of fracture under tensile loading. Principally, three types of fracture are encountered—smooth fractures, step fractures, and fractures involving undefined fibrillated ends…
The previously studied system GeO 2 ‐Bi 2 O 3 ‐TI 2 O was extended with the addition of PbO using air‐ and water‐quenched melted samples. Large areas of glass formation were found in the systems GeO 2 –Bi 2 O 3 –PbO and GeO 2 –PbO–Tl 2 O at all but the lowest GeO 2 contents. Glasses were examined by powder X‐ray diffr…
An attempt has been made to evaluate the optical gaps in Ge1-x S x and Ge k Sb m S n glassy systems using Manca's relation and the bond statistics of various models. The best agreement between calculated and experimental data is obtained for a chain-crossing model in the S-rich region and for a model due to Philipp in…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOxidation of aqueous sulfur dioxide. 2. High-pressure studies and proposed reaction mechanismsA. Huss Jr., P. K. Lim, and C. A. EckertCite this: J. Phys. Chem. 1982, 86, 21, 4229–4233Publication Date (Print):October 1, 1982Publication History Published online1 May 2002Publis…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPerformance of a commercial scale 14% hole area sieve trayTakashi Yanagi and Michiharu SakataCite this: Ind. Eng. Chem. Process Des. Dev. 1982, 21, 4, 712–717Publication Date (Print):October 1, 1982Publication History Published online1 May 2002Published inissue 1 October 198…
The signs of the Leslie viscosities α2 and α3 for nematics consisting of disk like molecules are discussed. It is predicted on theoretical grounds that for disk like molecules α3 is always positive while α2 should be able to exhibit both positive and negative values. This is the first time that the possibility of a po…
Abstract High‐density polyethylene was filled with chalk in various concentrations ranging from 10% to 60% by weight. Ethylene oxide oligomer M w = 300 was used as a liquid modifier for chalk in the amount 0 ÷ 20 wt % of the filler. The mechanical properties of these composites showed that high density polyethylene fi…
The studies of high pressure molecular luminescence reviewed, along with results for inorganic systems discussed elsewhere, provide evidence about the versatility and power of high pressure as a tool for characterizing electronic states, testing theories concerning electronic phenomena, and generally obtaining a bette…
Viscosity measurements have been performed on pure and doped liquid selenium. The influence of Tl, I, Te, Sb and Ge impurities is discussed in terms of local bonding. Two main factors dominate the viscosity behaviour: the mean chain length and the free volume. Monovalent or divalent elements induce a decrease in chain…
Free base Mg, ClAl, Zn, and Cu phthalocyanines (Pc’s) are successfully incorporated in Shpol’skii matrices, although they are practically insoluble in the open chain normal alkanes which are the conventional Shpol’skii solvents. In analogy with the porphyrins (P’s) the doublet spectra of the 0–0 transitions are observ…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTKinetics and mechanism of porphyrin-photosensitized reduction of methylviologenM. Rougee, T. Ebbessen, F. Ghetti, and R. V. BensassonCite this: J. Phys. Chem. 1982, 86, 22, 4404–4412Publication Date (Print):October 1, 1982Publication History Published online1 May 2002Publish…
An intergranular second phase, present as a film in a large‐grained MgAl 2 O 4 densified with LiF, was observed, on sequential heat treatment at 1500° C, to progressively reduce its area by first forming slender fingers which then break up into spheroid‐shaped islands. This “beading” process is an example of a Rayleig…
Abstract Experiments to produce polycarbosilazane resin and high‐strength silicon carbide–silicon nitride (Si x N y C z ) fibers as well as resin/fiber characteristics are reported. Polycarbosilazane resin was drawn into fibers from the melt and subsequently treated and pyrolyzed into Si x N y C z fibers. These materi…
The selective reflection is observed in a monodomain homeotropic cell of chiral smectic C liquid crystal (DOBA MBC). In conjunction with the refractive index, the structural helical pitch is determined as a function of temperature. The results agree well with our previous results obtained by diffraction technique as w…
The singularity index α of the asymmetric C(1s) x-ray photoelectron spectrum (XPS) of vitreous carbon is determined to be 0.19±0.01, independent of the interlayer separation of the graphitic layers. This result is interpreted within the framework of the many-electron theory; two mechanisms are suggested: (1) the modul…
The intensity and excitation wavelength dependence of the surface-enhanced Raman effect is measured on microlithographically prepared gold and aluminum particle surfaces. Comparison of enhancement relative to identically fabricated silver surfaces gives good agreement with particle-plasmon theories of surface-enhanced…
Abstract The kinetic aspects of the bisphenol‐A polycarbonate–polybutylene terephthalate exchange reaction are considered as a function of temperature and of the PC/PBTP ratio. The most likely mechanism is a direct reversible ester‐ester interchange reaction catalyzed by titanium residues present in commercial PBTP.
Polyaniline was electrodeposited on platinum and semiconducting (Cd‐chalcogenides, Si, GaAs , GaP ) electrodes from aqueous solution ( p H = 1 ) containing aniline. The electrochemical behavior of such films was examined in aqueous and nonaqueous solutions by cyclic voltammetry. Results show that the polyaniline film…