Materials Literature
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The effects of Brønsted acidity on the spatial structure and electronic properties of platinum clusters supported on zeolite Y have been examined with X-ray absorption (XANES and EXAFS) and X-ray photoelectron spectroscopy. The clusters contain 10−25 Pt atoms on average, with a nearest-neighbor distance of 2.70 ± 0.01…
Damping of the exciton absorption band of deaerated ZnO sol is directly related to the amount of silver photochemically deposited on the ZnO surface; recovery of this exciton band is achieved after the solution is exposed to air and silver oxide is formed.
Diffusion coefficients of sodium and zinc ions have been measured in bilayers of commercial, partially neutralized poly(ethylene- co -methacrylic acid). The diffusion behavior shows a break at the melting temperature of the resin, suggesting that chain backbone motion is intimately related to ionic transport. The ioni…
Regioselective Michael addition of nitro and heterocyclic compounds to levoglucosenone, 1, is effectively catalyzed by amines and also by cathodic electrolysis. In comparison to the base-catalyzed reaction, it was found that under electrochemical conditions the reaction proceeds under milder conditions and with higher…
Abstract Rietveld method has been applied to refine the structure of magnesium substituted β -tricalcium phosphate at a magnesium content of about 14 mol%. The results of the refinements, which show a final agreement factor R wp = 0.12, are in agreement with an almost complete substitution in two of the five crystallo…
A combination of quartz crystal microweighing (QCM) and infrared reflection absorption spectroscopy (IRRAS) was used to investigate the formation of ultrathin polysiloxane films on iron oxide surfaces by the adsorption of alkyltrimethoxysilanes in a humid atmosphere. It was shown that in the absence of a catalyst, onl…
Every coated fabric is unique when it comes to flame retardation because there are so many variables that can affect its use and performance. The proper formula must be worked out for each one. In this paper I have attempted to outline the basic principals of flame retardant technology. Every coated fabric will re qui…
A constitutive equation applicable to HCP metals and certain high strength alloy steels is applied to commercial purity titanium and the alloy Ti-6Al-4V. Deformation twinning and strain aging influence the deformation behavior of titanium, but are less significant in the alloy. Adiabatic heating is significant in the…
The magnetic properties of SmCo/sub 5/, Sm(Co/sub bal/.Fe/sub 0.21/Cu/sub 0.06/Zr/sub 0.03/)/sub 7.6/, Sm(Co/sub bal/Fe/sub 0.25/Cu/sub 0.06/Zr/sub 0.03/)/sub 7.6/, Sm(Co/sub bal/Fe/sub 0.28/Cu/sub 0.06/Zr/sub 0.02/)/sub 7.6/, sintered magnets have been measured up to 350, 400 and 450/spl deg/C. For a fixed temperatur…
Studies on the formation of complexes of europium(III) ions in water with various sensitizers are reported. The sensitizers utilized are derivatives of 1,10-phenanthroline-2,9-dicarboxylic acid and 2,2′:6′,2″-terpyridine-6,6″-dicarboxylic acid. Both 1:1 and 2:1 complexes form, the latter being particularly efficient l…
Perovskite-type Nd 1- x Sr x CoO 3- y catalysts with various Sr mole fraction were prepared and investigated for the effect of Sr substitution on their catalytic activities in the oxidation of carbon monoxide. Utilizing the static and flow methods, kinetic studies have been carried out between 373 and 523 K. The initi…
The microstructure of hydrobiotite, interstratified biotite/vermiculite, was examined to demonstrate an atomic scale investigation of weathering of minerals by high-resolution transmission electron microscopy (HRTEM). Vermiculite basal spacing was collapsed to about 0.95 nm, compared to the unchanged biotite 1.0 nm sp…
A very large radial graded-index (GRIN) polymer was successfully prepared for the first time, to the best of our knowledge, by two methods: the curved mold method and the diffusion copolymerization method. Both methods gave a radial GRIN polymer with a diameter of 70 mm and a ∆n value greater than 0.02. Ray tracing th…
This paper deals with the mathematical modelling of the random scission of branched chains. The objective is to predict the reaction products as well as the molecular weigth distribution for processes such as the chemical modification of polyolefins by free radical mechanism. In comparison with linear chains, where th…
Under shear deformation direct transitions SiI → SiIV → SiIII are observed; orientation relationships (OR) between phases have been determined for these transitions. It is shown, that the complete set of OR between phases SiI and SiIV contains six variants. On the basis of the obtained experimental data, a P-T-[sgrave…
Numerical self-consistent-field theory (Scheutjens−Fleer theory) is used to describe the crossover from “dry” brush behavior, where the matrix from which the polymers adsorb is itself a high-molecular-weight polymer, to “wet” brush behavior, where the matrix is a small-molecule solvent. The free energy, f *, required…
An attempt was made to compare the desorption behavior of the surface oxygen complexes in an inert atmosphere with that in the O 2 -gasification atmosphere. For this purpose, the transient kinetics (TK) with switching 18 O 2 to 16 O 2 was carried out and from this TK experiment the in situ desorption behavior of 18 O…
New metal-free and metal-containing 2,3,7,8,12,13,17,18-octakis[(4-methoxycinnamoyl)oxyalkylthio]tetraazaporphyrins with different polymethylene chain lengths (3,6,8 or 11 methylene groups) were synthesized by esterification of 2,3,7,8,12,13,17,18-octakis(hydroxyalkylthio)tetraazaporphyrins, obtained from 1,2-dicyano-…
Structural, photophysical, and charge transport properties of n -hexyl substituted polysilylenes containing 5, 33 or 67% n -hexylsilyne branching points were investigated. According to WAXD, DSC, and vibrational studies, introduction of branching points partially reduces the high degree of crystallinity of linear poly…
The phase K3[SO4]F was found to be dimorphic, undergoing a reversible tetragonal (β) to cubic (α) phase transition at 585 °C. The room-temperature polymorph, β-K3[SO4]F, is isostructural with Ba3SiO5, as confirmed by Rietveld refinement of X-ray powder diffraction data: a= 7.2961(5), c= 10.854(1)Å, R= 0.0689 and Rwp=…