Materials Literature
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Multiorganometallic compounds were used to prepare high‐purity submicron‐size lead lanthanum zirconate‐titanate (PLZT) powders which can be consolidated at low sintering temperatures to high‐density piezoelectric and electrooptic ceramic bodies. Simultaneous hydrolytic decomposition of lead isoamyloxide, lanthanum iso…
Measurements have been made of electron backscattering in a range of incident beam energy from 0·5 to 10 keV. The variation of backscattering coefficient η with energy and angle of incidence, and the energy spectrum of backscattered electrons at incidence and take-off angles of 45°, have been measured. Results from ca…
HOMSY, CHARLES A. SC.D.; CAIN, THOMAS E. M.D.; KESSLER, FRED B. M.D.; ANDERSON, M. SIDNEY M.D.; KING, JOE W. M.D. Author Information
"Problems of Non-linear Optics." Optica Acta: International Journal of Optics, 19(11), pp. 951–952
The main purpose of this article is to describe the electrical and magnetic properties of extrinsic semiconductors when the concentration of donors varies, particularly for concentrations near that for which a metal-insulator transition takes place. Since the donor centres are distributed at random in space, the combi…
Abstract Glutamate synthase catalyzes the TPNH-dependent conversion of α-ketoglutarate and l-glutamine to glutamate (Tempest, D. W., Meers, J. L., and Brown, C. M. (1970) Biochem. J. 117, 405). Levels of glutamate synthase are similar in Escherichia coli grown on 4 mm or 100 mm NH4Cl, but significantly lower levels of…
An explanation is provided for the phonon conductivity results of trivalent rare-earth-doped gallium and aluminium garnets in the temperature range 2-300 \ifmmode^\circ\else\textdegree\fi{}K. It is found that in GdAlG and GdGaG where the magnetic energy levels are so separated that an electronic transition between the…
A domain model is proposed for nepheline to explain the weak, paired, non-Bragg reflexions. Within the domains the nepheline structure is described in terms of a supercell, consisting of three subcells and stacked in AAA … sequence along c . The domains themselves are in regular sequence corresponding to ABCA … ACBA ……
Integrated intensity measurements of the (100) and (101) x-ray diffraction peaks of hexagonal selenium at pressures up to 52 kbar have permitted a determination of the atomic positions so that the bond distances and chain angle have been obtained at high pressure. The near-neighbor bond distances along the Se chain re…
Abstract Rigid urethane foams were prepared from hydroxymethylated linseed oil and its esters of glycerol, trimethylolpropane and pentaerythritol. These polyols were made by selective hydroformylation with a rhodium‐triphenylphosphine catalyst followed by catalytic hydrogenation with Raney nickel. Although the hydroxy…
Abstract A diffusion equation for the distribution of ionic impurities in a polymer under a dc field has been solved analytically for the conditions that neither injection nor absorption of impurity ions takes place at either electrode and that the ions do not interact. By using the solution of the diffusion equation,…
Infrared absorption spectra of 12 sodium silicate glasses of varying composition (10 to 45 mole% Na2O) are examined at varying pressures to 58.8 kbar. The pressure dependences of all the infrared absorption frequencies studied are found to be positive. Grüneisen γ's are evaluated from the pressure dependence of the in…
A system for designation of various types of mutual orientation of crystals and the processes during which they are formed is proposed. The neutral terms oriented overgrowth, oriented intergrowth and oriented inclusions, and in special cases polycrystal and single-crystal films, are considered to be sufficient for des…
The mechanisms of dezincification of single phase alpha and beta brasses were studied using X-ray diffraction, electron microprobe, metallographic, atomic absorption, and electrochemical techniques. The two mechanisms of dezincification which had been previously reported, (1) dissolution of both alloy constituents fol…
Raman spectra of polycrystalline crystobalite were measured over the frequency interval of the fundamental optical modes from 77°K to 538°C. Spectra recorded above and below the α–β transition temperature were strikingly different. The strong bands measured at 416 and 230 cm−1 with α cristobalite at 25°C were not obse…
The lattice parameters of the α-phase (disordered bcc), the metastable α''-phase (Fe 3 Al type) and the stable β-phase (Cu 3 Au type) in the Fe-Ga system containing 15∼30% Ga were determined and a phase diagram is proposed according to X-ray and magnetic measurements. The magnetic properties of these phases were inves…
When conducting particles are added to a nonconducting matrix, conductivity increases abruptly at a critical concentration. The theory of infinite chains is used to predict the variation of conductivity with particle concentration. Factors which determine the critical concentration are discussed.
Highly dense translucent polycrystalline bodies of stoichiometric aluminum silicate (mullite) were obtained by vacuum‐hot‐pressing of high‐purity submicron mixed oxide powders. The powders were prepared by the hydrolytic decomposition of mixed metal alkoxides. X‐ray diffraction and electron microscopy indicated that t…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSubtilisin. Stereochemical mechanism involving transition-state stabilizationJon D. Robertus, Joseph Kraut, Richard A. Alden, and Jens J. BirktoftCite this: Biochemistry 1972, 11, 23, 4293–4303Publication Date (Print):November 1, 1972Publication History Published online1 May…
A procedure is given which determines the best rigid-body rotation and translation that matches a given set of measured atomic coordinates to a fixed set of guide coordinates and minimizes the weighted sum of squared deviations.