Materials Literature
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Metallosilicalite xerogels of the type MOx–SiO2 where M isTiIV, VV, MoVI, WVI and SeIV have been prepared by the sol–gel method and used as heterogeneous catalysts for the epoxidation, allylic oxidation and carbon–carbon bond cleavage of alkenes, the hydroxylation of phenols, and the oxidation of alcohols to ketones b…
Space vacuum is considered as an insulation component to achieve constructional and operational advantages over totally enclosed designs for the increasing demand for higher levels of electrical power and voltages in spaceborne electrical systems. The dielectric properties of space vacuum insulations are determined ma…
Chemically pure and stoichiometric lanthanide chromites, LnCrO3, where Ln = La, Pr, Nd, Sm, Gd, Dy, Ho, Yb, Lu and YCrO3 have been prepared by the calcination of the corresponding lanthanide bis(citrato)chromium {Ln[Cr(C6H5O7)2·nH2O} complexes at relatively low temperatures. Formation of the chromites was confirmed by…
A transverse magnetic field formulation of the finite-element method for solving lightwave propagation in optical guides has been implemented. The method requires that the interface boundary conditions for E/sub Z/ and H/sub Z/ be imposed, and this is performed by solving the vector wave equation in the null space of…
Frequency-dependent node-to-node impedance function (NIF) models of power system equipment based on systematic broad frequency range (50 Hz to 1 MHz) external driving point impedance measurements are described. Such models are needed to calculate and predict the radio frequency electromagnetic (EM) noise produced by t…
The synthesis and characterisation of a series of new π-donor substituted vinyl bipyridines and their rhenium, zinc and mercury complexes {donor = 4-R2N–C6H4–[R2N = Me2N, Bun2N, (Me)(OctnN)]; (η5-C5H5)Fe(η5-C5H4-)} with large nonlinear optical properties are presented; EFISH experiments at 1.34 µm show that complexati…
The third order nonlinear optical susceptibilities χ(3) of PbO-SiO2 and PbO-B2O3 glasses have been measured by the third harmonic generation (THG) method using silica glass as reference. It is found that the third order nonlinear susceptibilities χ(3) of each series of glasses increase with increasing lead content, co…
A microprocessor implementation of the field-oriented control scheme for the permanent magnet (PM) hysteresis synchronous motor is reported. The basic principle is to decouple the torque-current component from the flux-current component so that these two components can be independently controlled. A d-q axis model of…
A new dioxovanadium(V) phosphate, Ag2VO2PO4, has been synthesised hydrothermally at 230 °C and characterized by single-crystal X-ray diffraction. The compound crystallizes in the monoclinic space group C2/m with a= 12.431(3), b= 6.298(1), c= 6.300(2)Å, β= 90.38(2)°, Z= 4 and R= 0.026. The structure consists of layers…
A possibility of the application of mercury porosimetry in the investigation on porosity in corrosion products of the carbon steel along with the degree of sealing by the use of tannin rust converters is presented. The effect of the atmospheric humidity on the rust conversion including the time of that conversion on t…
This paper reports Fourier-transform infrared (FTIR) spectra and temperature-programmed desorption (TPD) studies of CO2, CO and H2 adsorbed on ZnO/SiO2, Cu/SiO2 and Cu/ZnO/SiO2 catalysts. The adsorption of CO2 on ZnO/SiO2 catalyst at 295 K produced weakly held hydrogencarbonate species and chemisorbed carbonate struct…
Abstract The hyperpolarizabilities of polyynes containing a donor and acceptor group situated at either end of the molecular have been calculated at the sum‐over‐states CNDOVSB level using geometries derived from crystallographic data and ab initio studies. The calculated values increase with increasing chain length,…
In this paper an anomalous form of long term corrosion behaviour observed in mild steel exposed to some atmospheres in Spain is described. In such atmospheres corrosion kinetics of the steel wasfound to deviate from the behaviour predicted by the well known bilogarithmic law. The authors speculate on the plausible cau…
A crystal structure determination on the monocaesium derivative of bis(homooxa)-p-tert-butylcalix[4]arene (L2), [Cs(L2– H)(OH2)3]·xH2O (x≈ 3)[orthorhombic, Pmnb, a= 26.666(5), b= 15.928(4), c= 11.499(9)Å, Z= 4, R= 0.071 for 1500 ‘observed’ reflections] showed that the caesium may be considered to be involved in polyha…
The standard enthalpies of formation of YB2, TaB2, and W2B5 have been determined by direct synthesis calorimetry at 1473 ± 2 K. The following values are reported: [math] (YB2) = -35.7 ± 2.6 kJ/g.atom; [math] (TaB2) = -53.3 ± 2.0 kj/g.atom; [math](W2B5) = -17.5 ± 1.1 kJ/g.atom. Two new techniques which facilitate compl…
We studied chemical kinetics of weathering in the humus horizons of young Andisols from northeastern Japan. Since there is no idealized chronosequence of Andisols, we selected eight pedons that have many similarities in the properties of parent material, soil moisture regime, vegetation, drainage, etc., but show signi…
A statistical analysis of the atomic environments of arginine side chains from 62 high resolution protein structures has been made. Using the definition of F.M. Richards (J. Mol. Biol., 82, 1-14, 1974), the protein data set was subdivided into 19 different atom types and their propensities to form atom contacts with t…
In this paper the possibility is demonstrated of producing microalloyed steels with Ti, V and Nb using electrodes composed of finished steels freely available on the open market. The addition of ferroalloys to the slag pool was carried out at intervals of 1 min and it was confirmed that this interval was sufficient to…
The absorption of plasma proteins is an important event at the blood-material interface, and strongly affects subsequent cellular interaction and thrombus formation. Although considerable efforts have been expended to elucidate the mechanism of protein adsorption and the role of absorbed protein layer at the blood-mat…
A new linear trinuclear copper(II) co-ordination compound of the formula [Cu3(H2ahmt)6Cl4]Cl2, where H2ahmt = 4-amino-3,5-bis(hydroxymethyl)-1,2,4-triazole, has been synthesized. The crystal and molecular structure has been solved at 298 K by single-crystal X-ray analysis. The compound crystallizes in the triclinic sp…