Materials Literature
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We report a study of the viscoelastic and elastic properties of a nematic liquid crystal as measured by static and dynamic light scattering. Experimental values are reported for the splay/twist/bend elastic and viscoelastic ratio as well as for the Mięsowicz viscosity ratio η1/η3 of APAPA in the nematic region as a fu…
Une néphéline de composition (□0.04K0.48Na0.48)Na3[Al0.99Si1.01O4]4 a été synthétisée à partir d'un mélange d'oxydes dans NaF fondu à 1 000 °C/1 jour. Pour mesurer les intensités avec un diffractomètre X automatique à monocristal, on a choisi un fragment cristallin présentant un rapport I(230):I(320) minimum. Après co…
We have studied the cholesterization of discotic and calamitic lyotropic ferronematics by addition of brucine sulphate. The techniques used are optical microscopy for the textures and X-ray diffraction for the structures. The results concerning the pitch and the rotatory power of oriented samples containing or not fer…
The first monoarene complexes of gallium(I) were obtained by reaction of Ga2X4 (X = Cl, Br), suspended in toluene, with hexamethylbenzene. In 1b, C-1 and C-4 of the arena ligand are shifted towards the GaI; 1b can thus be regarded both as a π-complex as well as nido-cluster.
The previous X-ray-crystallographic determination of the relative configuration of P-1894B, a potent prolyl hydroxylase inhibitor isolated from the culture broth of Streptomyces albogriseolus, was extended by means of chemical and spectral studies. The absolute configuration of P-1894B (1) was established from the abs…
Indium-tin-oxide single crystals with 0–9 atomic% of Sn/In are produced by flux method, and their electrical properties are measured. At about 2 atomic% of Sn/In, the resistivity is 2×10 -4 Ω-cm and the electron concentration is 3×10 20 /cm 3 at room temperature. Further increase of Sn/In ratio does not change the ele…
Feldspars.- 1. Average Structures of Alkali and Plagioclase Feldspars : Systematics and Applications.- 2. Phase Relations of Plagioclase Feldspars.- 3. The Modulated Structure of the Intermediate Plagioclases and Its Change with Composition.- 4. Spectroscopy of Feldspars.- 5. Thermal Expansion of Alkali Feldspars.- 6.…
Ni/SiO2 catalysts prepared by impregnation and deposition–precipitation have been subjected to cyclic treatments in hydrogen at 500 °C and oxygen at 450 °C to test their resistance to sintering. The activity of the catalysts in benzene hydrogenation was tested after each cycle. The resulting behaviour was found to dep…
A simple test procedure to differentiate between sources of pregelatinized starch NF has been developed. The procedure is based on the swelling characteristics of the materials. Three pregelatinized starch NF products were distinguished by observing their sedimentation volumes. Microscopic differences in the particle…
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…