Materials Literature
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The Bruggeman optical effective medium theory of the dielectric permeability ε e(ω) of inhomogeneous media is analysed for metal-dielectric compounds in relation to the non metal-metal transition. The influence of the constituent-material parameters (free-electron parameters and bound-state polarization) on both the r…
The vibration spectra of a cylindrical sample of colloidal crystals are studied We indicate the proper choice of the aspect ratio α = R/H which optimizes the quality of resonances. A new experimental set-up allows us to compare the theory with the experimental results and to deduce a precise value of the elastic modul…
Abstract not Available.
The influence of magnetism on the short-range order (SRO) and its temperature dependence is clearly pointed out in a Fe 0.9 V 0.1 alloy. Emphasis is placed on the metallurgical aspects of the study carried out by means of residual resistivity and nuclear magnetic resonance (NMR) measurements at low temperature. The or…
Mössbauer and e.s.r. spectroscopy have revealed that 2,3,9,10,16,17,23,24-octacarboxy-(1), 2,9,16,23-tetracarboxy-(2), and 2,9 (or 10)- and 2,16 (or 17)-bis(3′,4′-dicarboxybenzoyl)-phthalocyaninatoiron (3) are mixtures of high-spin iron (III) and low-spin iron (III) complexes and that intermediate-spin species may be…
Very fine whiskers grown via vapour-phase polymerization of 3,4,9,10-peryleneteracarboxylic dianhydride have a poly-peri-naphthalene structure.
Description Subjects covered fall into several categories: theoretical, numerical, and experimental aspects of the mechanics of fracture; high-cycle fatigue; material influences on fracture; and elasto-plastic fracture mechanics.
The dissolution profiles of chlorpropamide (CPM) polymorphs, especially the metastable form II reported by Al-Saieq et al., were investigated kinetically in detail by a dispersed amount method and a stationary disk method in comparison with those of the stable form. Form II showed a dissolution phenomenon involving si…
This encyclopedia is another in the series of carefully selected reprints from the world-renowned Kirk-Othmer Encylopedia of Chemical Technology, designed to provide specific audiences with articles grouped by a central theme. As a handy desk reference, it incorporates all the original articles related to textiles, fi…
Abstract High purity molybdenum single crystals were deformed in tension and compression along the symmetric double slip orientation [110] in the temperature range from 300 K down to 0.5 K with strain rates between 10 −3 and 10 −5 s −1 . The activation volume was measured by stress relaxation tests. The dislocation st…
A new microscopic theory is proposed for the electronic and lattice structures of crystal and defects of Se and Te. Consideration of the valence bond picture shows that electron correlation in valence p electrons produces a charge density wave (CDW) of vector nature, the vector CDW (VCDW), which has the period of thre…
Lithium sulfate monohydrate has been studied at 293, 80, and 20 K by neutron diffraction using the same ground spherical crystal. Li2SO4⋅H2O is monoclinic, space group P21, with lattice dimensions at 293 K of a=5.450(3), b=4.872(3), c=8.164(4) Å, β=107.31(3)°; at 80 K: a=5.449(2), b=4.832(2), c=8.141(2) Å, β=107.21(1)…
Abstract not Available.
We report the identification of the first truly ferroelectric liquid crystal in a compound which also shows chiral C, I and G' phases at higher temperatures. In the new phase the director can be oriented in a bistable way with an electric field V in a time τ such that V.ln τ is proportional to temperature. Furthermore…
An optical and electron metallographic study has been carried out on chill and sand cast M2 grade high speed steel in the as-cast condition and after reheating to temperatures typical of those for hot working for times up to 200 h. The as-cast material contains M2C, MC, and M6C particles, but the M2C decomposes rapidl…
Abstract The process of serial sectioning for electron microscopy has been refined such that loss of thin sections is kept below 0.1% and the series is continued at will. The method relies on microscopic control of all manipulative steps, Formvar casting on plate glass for coated slot grids, coating of the block with…
The formation of dimers upon gamma-irradiation of thymine, thymidine and thymidine-5'-monophosphate in N2O-saturated aqueous solution is reported. A method using capillary gas chromatography-mass spectrometry was developed for their separation and identification. Quantitative measurements reveal that about 50 per cent…
Abstract The impedance of poly(pyrrole) (PP) and poly( N ‐methylpyrrole) (PMP) films on platinum in an acetonitrile, LiClO 4 solution has been measured. At potentials more positive than a characteristic value, the electrodes exhibit porous behaviour and the impedance is determined by the double‐layer capacitance and t…
The properties of the nematic-isotropic interface of the nematic liquid crystal 7CB are studied by optical reflectometry. It is found that at the interface the director is tilted with respect to the vertical axis. Measurements are reported of the tilt angle θt, of the thickness of the interface, and of the anchoring e…
Fibrils of collagen reconstituted in vitro by dialysis against sodium formate are exposed to free oxy radicals generated by three different systems: (i) xanthine oxidase + hypoxanthine, (ii) gamma-rays originating from a cobalt bomb; (iii) pulse radiolysis in a particle accelerator. A degradation of the collagen fibre…