Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
The kinetics of passivity breakdown and nucleation of pitting of preanodized aluminum by chloride ions has been investigated using aluminum supporting oxide films of reasonably well‐known thickness and structure. The kinetics of passivity breakdown at the steady‐state, critical pitting potential is influenced by chlor…
Abstract A thorough examination of some cationic copolymerization systems by a new method has shown that many published r values have to be corrected significantly and that some are erroneous and meaningless, because for these systems the conventional copolymer compositions equation does not hold. Available informatio…
Heme A, isolated from bovine heart muscle by procedures which include extractions into pyridine/chloroform and two-phase, liquid-liquid chromatography on Celite, has been converted to several derivatives. Examination of the proton nuclear magnetic resonance (PMR) spectra and other properties of these derivatives revea…
Preparation, properties, and applications of porous silicon film were investigated. Silicon single crystal is converted into porous silicon film by anodization in concentrated hydrofluoric acid at currents below the critical current density. When an n‐type silicon was anodized, the silicon surface was illuminated to g…
M\"ossbauer and other studies establish that in ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}\mathrm{Co}{\mathrm{O}}_{3}$ ($x>0.125$), ferromagnetic ${\mathrm{Sr}}^{2+}$ -rich clusters coexist with paramagnetic ${\mathrm{La}}^{3+}$ -rich regions in the same crystallographic phase, with the ferromagnetic compon…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis of new tetraphenylporphyrin molecules containing heteroatoms other than nitrogen. I. Tetraphenyl-21,23-dithiaporphyrinA. Ulman and J. ManassenCite this: J. Am. Chem. Soc. 1975, 97, 22, 6540–6544Publication Date (Print):October 1, 1975Publication History Published o…
Surface crystallization of a Au+-ion-implanted lithia-alumina-silica glass has been realized. Annealing of a glass sample implanted with 285-keV Au+ ions at 550 °C results in the growth of colloidal Au particles of 18–35-Å radius. The Au particles constitute sites for the precipitation of lithium metasilicate crystals…
Abstract Optical brighteners are used in detergents, textiles, paper, plastics, and paints. Most optical brighteners contain heterocycles such as coumarins, 2‐pyrazolines, naphthalimides, pyrazoles, triazoles, oxadiazoles, and triazines. In this article the syntheses, properties, and applications of new optical bright…
Abstract The light emission of ZnO under high one‐ and two‐quantumexcitation is investigated in the temperature region from 4 to 300 K. Emission bands are observed which can be attributed to the interactions of free excitons with phonons, free excitons and free electrons, and of bound excitons with phonons and free an…
Abstract The basic salts of this system were prepared and their structures and physico-chemical properties were studies by electron microscopy, chemical analysis, X-ray powder diffraction, thermal analysis, i.r. absorption spectra, BET absorption, and acidity-basicity measurements. The salts were found to be new compo…
The influence of the chemical structure of heat-resistant aromatic polymers on their physical properties is discussed mainly in relation to mechanical properties. Methods for determining the heat resistance of polymers and their mechanical performance are described, and the calculation of the principal physical charac…
The types of clay minerals formed by hydrothermal alteration of basaltic rocks in geothermal fields in Iceland have been a matter of interest for some time. The fine-grained nature and poor crystallinity of the minerals make investigation difficult. X-ray-diffraction analyses suggest the presence of numerous different…
X-ray photoemission line shapes of $2s$ and $2p$ electrons from Al, Mg, and Na have been analyzed in terms of the theory of Mahan and of Nozi\`eres and De Dominicis. The resultant singularity indices, 0.115, 0.13, and 0.19, respectively, require that all x-ray threshold exponents, save that for the Na $K$ edge, be pos…
A theory of the thermoelectric power associated with electronic phonon-assisted tunneling (hopping) motion between inequivalent sites has been developed. The general results have been applied to some prototype situations characteristic of hopping in disordered solids.
NMR and EPR measurements in V${\mathrm{O}}_{2}$ under uniaxial stress in the ${[110]}_{R}$ direction lead to a phase diagram entirely similar to that obtained in ${\mathrm{V}}_{1\ensuremath{-}x}{\mathrm{Cr}}_{x}{\mathrm{O}}_{2}$ alloys. Two intermediate phases ${M}_{2}$ and $T$ are observed, and, as established for ${…
Attenuation of the elastic component of an electron beam outside a surface is calculated. Significant attenuation is found in the case of RHEED experiments, explaining an earlier disagreement between theory and experiment observed by Menadue and Colella (see abstr. A9238 of 1972).
The skeletons of living specimens of the scleractinian coral Porites lobata have been found to contain up to 46 +/- 5 percent low-magnesium calcite even though free of gross detrital inclusions and boring or encrusting organisms. The calcite crystals occur in the interior of skeletal structures, have dimensions of 20…
Thermal conductivity measurements of a monocrystalline nonhomogeneous GaAs sample exhibit different conductivities with respect to the direction of heat flow across the sample. It is found that the same applied external temperature gradient causes two different distributions of the effective thermal conductivity coeff…
High-temperature phase transitions in KH 2 PO 4 near 110°C and 180°Chave been studied by X-ray diffraction. The extinction rule observed at 123°C is the same as that in the room-temperature phase. It is concluded that on heating through 187°C crystal system changes from tetragonal to monoclinic whose space group is P…
By use of a capacitance method, the thermal expansions of NaNO 2 ( T C =163.9°C, T N =165.2°C) along the a -, b - and c -axes were measured from -180°C to 240°C with the accuracy of 1×10 -6 cm in Δ l . Anomalies associated with the phase transitions were observed over the wide temperature range 100 to 200°C. The therm…