Materials Literature
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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…
A detailed x-ray-absorption fine-structure (XAFS) investigation of two mixed alkali halides ${\mathrm{Rb}}_{0.76}$${\mathrm{K}}_{0.24}$Br and ${\mathrm{RbBr}}_{0.62}$${\mathrm{Cl}}_{0.38}$ was performed. The concentrations of the mixtures had been chosen to produce a single homogeneous phase for each, and it was check…
Over the past decade the study of nonlinear optical processes in organic and polymer systems has enjoyed rapid and sustained growth. One indication of that growth is the increase in the number of articles published inrefereed society journals. The four-year period 1980–83 saw the publication of 124 such articles. For…
The paper reviews the electrical and optical mechanisms at work in sulfide-based thin-film electroluminescence display devices within the framework of general semiconductor physics. The electrical problem is twofold: (i) charge carriers are sourced at high electric field in a nominally insulating material, the carrier…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA New Structural Motif of Gold Clustering at Oxide Centers in the Dication [Au6O2(PMe3)6]2+Klaus Angermaier and Hubert SchmidbaurCite this: Inorg. Chem. 1994, 33, 10, 2069–2070Publication Date (Print):May 1, 1994Publication History Published online1 May 2002Published inissue…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffect of Ionic Strength on Protein Adsorption KineticsJ. J. Ramsden and J. E. PrenosilCite this: J. Phys. Chem. 1994, 98, 20, 5376–5381Publication Date (Print):May 1, 1994Publication History Published online1 May 2002Published inissue 1 May 1994https://pubs.acs.org/doi/10.1…
Aqueous gelatin solutions have been studied in a systematic and exhaustive manner in a neutral buffer medium, in the temperature range of 30–60 °C, by static (SLS) and dynamic laser light scattering. It has been clearly established that upon cooling the sol from 60 °C, the gelatin chains form thermoreversible aggregat…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFirst Transition Metal-Boryl Bond Energy and Quantitation of Large Differences in Sequential Bond Dissociation Energies of BoranesPaul R. Rablen, John F. Hartwig, and Steven P. NolanCite this: J. Am. Chem. Soc. 1994, 116, 9, 4121–4122Publication Date (Print):May 1, 1994Publi…
Actinide sorption on colloids may be described as a competition between the formation of complexes in solution and the build up of surface complexes. The role of particle and of carbonate concentrations on the sorption/desorption of <sup>241</sup>Am on montmorillonite, illite and hematite colloids is inves…
Abstract Formation of hydrogen bonds in various cellulose derivatives, 2,3‐di‐ O ‐ and 6‐ O ‐substituted cellulose ethers, were characterized by FTIR and solid‐state CP/MAS 13 C‐NMR. The polymers were synthesized by regioselective substitution of hydroxyl groups and had a uniform structure. Since their three hydroxyl…
The maximum-entropy method (MEM) has been tested on a limited set of noisy Fourier data from a known electron-density distribution (EDD). It is shown that maximizing the entropy of the EDD under the usual condition of fitting the variance of the data set does not necessarily lead to a satisfactory error distribution o…