Materials Literature
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Abstract The generalised thermal parametric sensitivity criterion is applied to the thermal behaviour of the esterification of 2‐butanol with propionic anhydride in a batch reactor under isoperibolic conditions. The reaction is catalysed by sulphuric acid, and the study covered the effects of both catalyst concentrati…
We measured optical emission spectra during the deposition of Bi 2 Sr 2 Ca n -1 Cu n O x (BSCCO) films by an rf magnetron sputtering method with a BSCCO powder target. It was shown that the active particles produced are ionized oxygen molecules and CuO radicals when He+O 2 is used as a sputtering gas. The results of X…
In an attempt to replace the traditional cyanide process of extracting gold, a new technology using ammoniacal solutions has been developed. In this study, the electrochemical behavior of gold in ammoniacal solutions at temperatures above 100°C has been investigated. An electrochemical cell in an autoclave has been in…
We develop a weakly nonlinear morphological stability analysis for an infinitely long right circular cylinder growing from its pure undercooled melt. For a cylinder perturbed by a specific planform consisting of sinusoids, we perform an expansion in the planform amplitude A to calculate the nonlinear critical radius (…
The Vickers microhardness of non-melanic keratin was measured from the bills, claws and outer primaries of Common Starlings Sturnus vulgaris. Highly significant differences in hardness were found between all three keratin types. Bill keratin was the hardest and feather keratin the least hard; the relative molecular we…
The temperature dependence of the 15 N and 133 Cs NMR spin-lattice relaxation times, the 15 N spin-spin relaxation time, and the 15 N and 133 Cs spectra of CsNO 2 was observed in the plastic phase (209.2 < T < 673 K (m. p.)) and the low-temperature phase (Phase II). In Phase II we found the NO - 2 180°-flip, whi…
Abstract The chemical and structural stability of a Spanish sepiolite from Vallecas, Spain, was studied in 0.04 n NaOH (pH = 12.6), a saturated solution of Ca(OH) 2 (pH = 12.6) and deionized/distilled water (pH = 7). The chemical stability was evaluated by determining the concentrations of Mg, Si and Ca in the solid r…
Electrical resistivity and magnetization measurements have been carried out on synthetic single crystals of ${\mathrm{Fe}}_{3\mathrm{\ensuremath{-}}\mathit{z}}$${\mathrm{Al}}_{\mathit{z}}$${\mathrm{O}}_{4}$ in the range 0\ensuremath{\le}z0.06. The samples were annealed to achieve the ideal 3:4 ratio of cations to anio…
The spectral response and impact ionization coefficient ratio of Si/sub 1-x/Ge/sub x/ have been determined. Measurements were made on p/sup +/-i-n/sup +/ diodes grown by solid/gas source molecular beam epitaxy. The diodes are characterized by reverse breakdown voltages of 4-12 V and dark currents of 20-170 pA//spl mu/…
Abstract Novel substituted -6,8-dinitro-l′,3′,3′-trimethylspiro[2H-1-benzopyran-2,2′-indoline] derivatives have been synthesized in high yields, and their properties are investigated. The absorption maxima of the ring-open forms and the negative photochromic properties of spirobenzopyrans significantly depend on the s…
Abstract Eine erneute Untersuchung der Einkristalle von „HTiO”︁ und der Vergleich mit Messungen an TiB 2 ‐Kristallen hat gezeigt, daß es sich bei „HTiO”︁ um Titandiborid handelte.
Abstract trans-1,2-Bis(octaethylporphyrin-5-yl)ethene free base and its dinickel(II) complex exhibit narrow electrochemical band gaps (1.44 and 1.49 eV, respectively) and broad, solvent-dependent absorption bands at low energy, whilst the corresponding cis isomers undergo rapid redox-induced cis → trans isomerisation.
We investigate the motion of an interface between a nematic liquid crystal phase and the isotropic phase of the same fluid. In this simplified model we assume the nematic liquid crystal to have one order parameter only and also suppose the system to be isothermal and initially quenched into the metastable régime of th…
A 6 step synthesis of the title compound derives from a palladium catalyzed addition of terminal alkynes to acceptor alkynes.
Results of the TSL study of the main dosimetric peak region from BeO single crystals doped with boron or lithium impurities in different concentrations are presented. The TSL peculiarities at 420 K were interpreted in terms of the field fluctuation process model. It was suggested that in BeO over the region betwen 380…
Air flow in air jet weaving machines is complicated: it is unsteady, turbulent, and can be compressible or incompressible depending on the velocity. A separated flow model is developed to simulate air flow through the guide channel, which is half open and corrugated. Subsonic air flow in the guide channel is investiga…
Coordination of 4-OH-2,6-bis-(benzimidazol-2′-yl)pyridine (OH-bzimpy = H3L) with ironI(II) increases the acidity of the iminohydrogen atoms of the benzimidazole groups. The first three protonation constants (logKn) both for the free ligand, (OH-bzimpy) and the complex, [Fe(OH-bzimpy)2](ClO4)2 · 3H2O, were evaluated in…
Abstract The effects of EPDM admixture, mixing conditions and additional stabilization on the phase structure and impact strength of low‐density polyethylene/isotactic polypropylene (LDPE/PP) blends were studied. It was proved that EPDM is localized at the interface between LDPE and PP phases. The admixture of 5% EPDM…
Palladium membrane has been studied for sepration and purification of hydrogen isotopes because of its large permeability. In order to consider permeation of mixture of hydrogen isotopes, solubilities of protium and deuterium in palladium were studied in the temperature range of room temperature to 500°C using breakth…
Various mechanical and thermal properties of β′‐sialon ceramics, Si 6–z Al z O z N 8–z , prepared from aqueous slurries by a slip casting method were investigated as a function of Z values from 0 to 4. In the present study, Si 6–z Al z O z N 8–z occurred in the β′‐sialon crystalline phase only near Z = 1. The maximum…