Materials Literature
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A type of intrinsic luminescence in crystals has been revealed. The excitation threshold of well-known fast intrinsic luminescence of CsI (300 nm band) has been obtained from the excitation spectrum measured in the photon-energy range 5--125 eV at 300 K using synchrotron radiation. The excitation starts from an energy…
A sample preparation technique, suitable for x-ray-absorption measurements of liquid and supercooled metals is described. The method is based on an application of the emulsion technique, consisting in a dispersion of micrometric droplets in an inert rigid matrix. It has been applied to Hg and Ga resulting in a very fi…
Abstract Concentration‐dependent ternary interaction parameters are experimentally determined for the polyamide homopolymers, Nylon‐6, ‐66, ‐610, and for the Nylon‐66/610/6 terpolymer in formic acid‐water systems. The binodal envelope, the tie lines, and the crystallization isotherms at 25°C are given for each of the…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis, Structure, and Properties of Two New Vanadium(III) Phosphates: VPO4.cntdot.H2O and V1.23(PO4)(OH)0.69(H2O)0.31.cntdot.0.33H2OJ. T. Vaughey, William T. A. Harrison, Allan J. Jacobson, David P. Goshorn, and Jack W. JohnsonCite this: Inorg. Chem. 1994, 33, 11, 2481–2…
The interactions and orientational correlations of charged rodlike colloidal particles in a salt-free suspension are calculated using an ‘‘ab initio’’ approach which combines molecular dynamics for the rods and classical density functional theory for the counterions. Both fluid and liquid-crystalline phases are invest…
Vanadium pentoxide gels and sols, V2O5, nH2O, exhibit a ribbon-like structure. They form colloidal suspensions (also called Zocher phases or ‘tactophases’) which are clearly shown here to present a homogeneous lyotropic nematic phase for concentrations larger than ≈0·12mol 1−1. Classical threaded textures were observe…
Electron diffraction and high-resolution electron microscopic techniques are applied to reveal the mechanisms of crystallization of free standing 75-nm-thick thin films of ferroelectric lead-zirconate-titanate (PZT). Sol-gel methods, followed by pyrolysis at 350 °C, were used to provide a common starting point after w…
Abstract The reduction of CO2 with H2O was investigated on the single crystals of TiO2(100) and TiO2(110); the former TiO2(100) exhibiting a higher efficiency in the formation of CH4 and CH3OH than TiO2(110). Measurements of the intermediate species formed on the TiO2(100) single crystal were carried out using a high…
Decorticated kenaf stalks were retted by bacterial and chemical processes. Bacterial retting was done in troughs at a temperature of 30 ± 2°C. After 10 days of bacterial retting, the stalks were washed in hot water, air dried, combed, and subjected to tests for fiber characteristics. Chemical retting was done by boili…
We consider both the spatial domain and spectral domain forms of the Green's function, appropriate in the electromagnetic diffraction of a plane wave incident in the xy plane on a singly periodic structure, or grating, oriented along the x axis. For the spectral domain form, we exhibit for an obliquely incident plane…
Abstract Propylene oxide was anionically polymerised in bulk at 80°C under a range of initial conditions, from zero hydroxyl content to a mole ratio of hydroxyl to potassium catalyst of 10. The double bond content of the polymers was measured by 1 H NMR spectroscopy over a wide range of conversions, and values of the…
We present theoretical and experimental studies of the molecular second order nonlinear optical responses of donor–acceptor substituted conjugated compounds which consist of heteroaromatic moieties in place of the traditional benzenoid moieties. Electric-field-induced second harmonic generation measurement at a fundam…
New approaches to the interpretation of contrast-variation data from monodisperse systems using spherical harmonics are presented. A general method is given for evaluating the particle shape and internal structure and expressions for the scattering from the density fluctuations inside a particle with a known shape are…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChemical Vapor Surface Modification of Porous Glass with Fluoroalkyl-Functional Silanes. 1. Characterization of the Molecular LayerHiroaki Tada and Hirotsugu NagayamaCite this: Langmuir 1994, 10, 5, 1472–1476Publication Date (Print):May 1, 1994Publication History Published o…
Fibrous monolithic ceramics were fabricated in the SiC/BN system. The microstructure consists of high‐aspect‐ratio polycrystalline cells of SiC separated by cell boundaries of BN. The fibrous monolith with aligned cells fails noncatastrophically in flexure, with delamination cracking along the BN cell boundaries. Inde…
Abstract This study was conducted to evaluate the effects of Mg on the cation‐exchange relationships and structural stability of sodic soils. Samples of prairie soils (Haploborolls) from Saskatchewan, Canada, were equilibrated with sodic solutions [sodium adsorption ratio (SAR = Na/(Ca + Mg) 0.5 , where concentrations…
Abstract The effect of film thickness on in‐plane molecular orientation and stress in polyimide films prepared from pyromellitic dianhydride with 4,4′‐oxydianline was investigated using a prism coupling technique to measure the refractive index. Film thickness was controlled by varying both solution concentration and…
Abstract The phase segregation and subsequent minor phase coarsening of a commercial impact polypropylene copolymer was studied. The major components of the impact polypropylene copolymer studied were 82.4 wt % polypropylene homopolymer and 17.6 wt % ethylene‐propylene rubber (EPR). The system was artificially manipul…
The effects of environment on cyclic and static fatigue behavior were investigated with hot‐pressed silicon nitride materials. Tests were conducted at ambient temperature on standard compact tension specimens, and a dc electric potential technique was used to monitor crack lengths in situ. The results indicate that th…
We report the formation of thin anisotropic phase gratings in a nematic liquid-crystalline film by use of lateral (fringing) electric fields induced by transparent interdigitated electrodes. These gratings yield high diffraction efficiency (>30%) with a strong dependence on the readout beam incidence angle. In additio…