Materials Literature
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Abstract Five new optically active crown ethers and six optically active dipodands are reported. The crown ethers were synthesized by using (+)-(1S,4R,5S,8R)-2,3:6,7-dibenzobicyclo[3.3.1]nona-2,6-diene-4,8-diol and (+)-(1S,4R,5S,8R)-4,8-bis(hydroxymethyl)-2,3:6,7-dibenzobicyclo[3.3.1]nona-2,6-diene as a chiral subunit…
Chlorided Pt/Al2O3 catalysts have been subjected to a series of consecutive oxidation / reduction cycles and the quality of Pt dispersion after each reduction stage monitored by infrared study of adsorbed CO. Low-temperature (613 or 723 K) oxidation treatments failed to improve Pt dispersion after subsequent reduction…
The anomalous high-index faces (hkl) of the mineral calaverite (Au1 - xAgxTe2) measured goniometrically in the year 1931 by Goldschmidt, Palache & Peacock [Neues Jahrb. Mineral (1931), 63, 1-58] are re-interpreted and related to the wave vector q of the displacive incommensurate modulation which was recently found in…
The reactivity towards carbon monoxide of a series of Zn–Cr non-stoichiometric spinels (NSS) with an excess of zinc, active in the synthesis of methanol and higher alcohols, has been investigated by infrared spectroscopy and adsorption microcalorimetry. A fraction of the total CO taken up is irreversibly oxidized to s…
The physical properties of a carpet, especially the mechanical and optical properties, largely determine its performance as a floorcovering. The mechanical properties influence the walking comfort and are closely linked to the changes in appearance during wear. New instrumental techniques, notably those using digital…
Seven novel fungitoxic sesquiterpenoids, chokols A, B, C, D, E, F and G, were isolated from stromata of Epichloe typhina on Phleum pratense. Their structures were determined by spectroscopic methods. The absolute configuration of chokol E was elucidated by its CD spectrum with Eu(fod)3 and a chemical correlation with…
Quality, appearance, and tactile properties of textiles arise from the choices of fibre type, linear density, staple length and degree of crimp, yarn linear density, mass, and twist, and fabric mass, weave type, density, and type of finishing, and especially the types of fibre assembly chosen. Information on how these…
Abstract Graft polymerization of maize starch with acrylic acid using potassium persulphate as free radical initiator was investigated under different conditions. Variables studied included initiator concentration, acrylic acid concentration, starch/water ratio and polymerization temperature. The carboxyl content of t…
Our recent studies of ferroelectric chiral smectic and super-twisted nematic (ST) multiplexed-matrix liquid-crystal displays (LCDs) and a thin-film-transistor (TFT) active-matrix twisted nematic (TN) LCD are presented, mainly in terms of liquid-crystal material and cell optimization. This is based on a consideration o…
ABSTRACT: Analytical transmission electron microscopy (ATEM) was used to obtain chemical analyses of single illite crystals from Upper Carboniferous reservoir sandstones ofthe Bothamsall Oilfield, East Midlands, UK, and from Rotliegendes (Permian) sandstones of the North Sea. All samples were found to be highly alumin…
The scheme previously proposed by the authors on the basis of the Taylor model to deal with the deformation of polycrystals caused by the stress induced martensitic transformation (SIM) has been futher extended to describe the recovery stress associated with the reverse transformation upon unloading. According to this…
The unusually highly puckered macrocyclic core of the title compound confirms proposed conformational changes which are essential for the facile aerial oxidation of phenolic porphyrins, such as meso-tetrakis(3,5-di-t-butyl-4-hydroxyphenyl)porphyrin (1).
Irradiation of the benzene solution of l-(2-vinylpheny1)-2-(2-furyllethenes (71 resulted in the formation of furo(3.2-bl-6.7benzobicyclo[3.2.llocta-2,6-dienes (101 as the main product.The structure of the products was determined by spectroscopic data.Intramolecular photochemical cycloadditions of o-divinylbenzene (1)…
Some CaO–SiO2–H2O gels of controlled composition have been synthesised by the hydrolysis of mixed alkoxide precursors and by direct reaction between colloidal SiO2 and Ca(OH)2. The gels were equilibrated with water at 25 °C after different ageing treatments, and the water compositions analysed. A mathematical model de…
Ultrafine particles (UFP) of Fe-Ni, Fe-Cu and Fe-Si alloys were produced by arc melting, vaporization and deposition of iron alloys in 50%H2-50%Ar atmosphere (“hydrogen plasma-metal” reaction) at 0.1 MPa pressure. The morphology, chemical composition and crystal structure of particles obtained were determined by TEM o…
The occurrence of a three dimensional hexagonal blue phase BPH (possible space groups P6222 and P6422) in materials with negative dielectric anisotropy ϵa = ϵ∥ - ϵ⊊ has been detected by the investigation of Kossel diagrams. This is the first observation of a field-induced transition between different blue phase modifi…
The synthesis and single-crystal X-ray structure characterization of tetrameric cubane clusters of copper(1) halides with the hindered N-base ligand 2-(diphenylmethy1)pyridine are reported. The chloride, bromide and iodide structures are isomorphous , crystallizing in the tetragonal space group 141/ a, a ˜ 23, c ˜ 12…
It is shown experimentally that several types of glyceride additives improve the dielectric breakdown strength of polyethylene at the semiconducting electrode. The highest breakdown strength is more than twice the original one in terms of 1% Weibull breakdown strength. The average normal component, cos theta , is intr…
Analytical results are obtained for mobility functions that describe the hydrodynamic interactions for transverse motions of two unequal viscous drops. In conjunction with the results of an earlier paper on axisymmetric motions, the motion induced by external forces in an arbitrary direction, i.e., the solution of the…
The magnetostrictivity (d) and magnetostriction ( lambda ) of high coupling magnetomechanical amorphous ribbons and wires are determined without the use of a direct magnetomechanical measurement. The method relies on an easily measured magnetic property (permeability) of the magnetostrictive material obtained under th…