Materials Literature
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The possibility of creation of a structure of two domains with mutually opposite directions of spontaneous polarization is considered. These domains are divided by a domain wall of metal conductivity with a concentration of free electrons or holes of about 1021 cm-3, the thickness of the conducting layer being about 1…
The method of nuclear microanalysis of stable oxygen isotopes by the reactions was used to investigate the mechanisms of growth, dissolution, and transport associated with oxygen during the formation of relatively thin (≤7000Aå) porous anodic layers on aluminum. The average charge associated with an oxygen ion fixed i…
Abstract The nucleating activity of a large number of nucleating agents for the crystallization of polyolefins is not based on a high surface free energy of the substrate or on epitaxy, or on a minimum particle size just compatible with the thickness of the crystallizing polymer lamellae, or on any persistance of crys…
Structure and properties of disclination lines and disclination points in nematic and cholesteric liquid crystals are reviewed. An equivalence between the directorfield of nematics and electrostatic or magnetostatic fields in two-dimensions is pointed out. Dislination lines can be classified in singular and non-singul…
The electrical conductivity of sintered specimens of CaO ‐ doped CeO 2 [ 0.1 – 16.0 m / o ( mole per cent ) ] was measured over the temperature range 700°–1500°C and from 1 to 10 −22 atm of oxygen. All specimens of CaO ‐ doped CeO 2 exhibited mixed conduction. Two limiting case regions were observed. At low temperatur…
Core binding energies of a number of nitrogen bases and their adducts with BF3 are reported, and interpreted using both ab initio and semi-empirical molecular orbital calculations. The binding energies are found to reflect the change in molecular charge distribution which occurs on formation of the B—N σ bond. The cor…
The system has been studied by a combination of polarization microscopy, using a hot stage, and X-ray diffraction analysis. The sequence of condensed phases occurring at room temperature with increasing concentration of disodium chromoglycate (DSCG) is: (i) a mesophase N; (ii) a mesophase M; (iii) crystalline solid so…
Single-crystal X-ray studies have shown the trishexamethyldisilylamides of scandium(III) and europium(III) to have unusual pyramidal three-co-ordinate structures.
Abstract We have studied the homogeneous hydrogenation of a series of unsaturated polymeric substrates with diimide formed from the thermal decomposition of p ‐toluenesulfonylhydrazide (TSH) at elevated temperatures (110 to 160°C) and in aromatic solvents. At a TSH/olefin ratio of 2.0, homopolymers of butadiene, polyc…
Abstract The structure of spherical droplets of nematic and cholesteric materials floating in an isotropic liquid is experimentally investigated by microscopic observation with polarized light. In nematic droplets either a star configuration or a bipolar configuration have been observed depending on the nature of the…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTProton magnetic resonance investigation of antiferromagnetic oxo-bridged ferric dimers and related high-spin monomeric ferric complexesGerd N. La Mar, G. R. Eaton, R. H. Holm, and F. Ann. WalkerCite this: J. Am. Chem. Soc. 1973, 95, 1, 63–75Publication Date (Print):January 1…
X-Ray photoelectron spectroscopy has been used to study a series of chromium–oxygen compounds. It has been shown that the ionisation energy of the chromium 2p electrons is dependent primarily on the oxidation state of the chromium metal ion, but that small perturbations may be attributed to changes in crystal structur…
Dielectric, piezoelectric and elastic constants have been measured in single domain KNbO3, and electrooptic r-coefficients are estimated. Results allow a thorough verification of Devonshire's theory for the orthorhornbic phase. Good agreement is found for the dielectric and piezoelectric properties whereas fitting the…
The acidity and the concentrations of metal and chloride ions in the solution within a pit were measured for some austenitic stainless steels using an artificial pit activated galvanostatically in 0.5N NaCl solution at 70 C (158 F). The pH and the chloride ion concentration changed in a range of pH -0.13 to 0.80 and 3…
Abstract The morphology of a new family of copolyester thermoplastic elastomers is described and the physical properties of these polymers are interpreted in terms of their unusual two‐phase domain structure. The elastomers were synthesized by the equilibrium melt transesterification of dimethyl terephthalate with 1,…
The dipole relaxation behaviour in liquid crystals as a function of the molecular ordering has been interpreted theoretically. The decay function of the electric dipole polarization has been calculated in terms of the correlation function of the Wigner rotation matrices. The orientational potential energy function has…
The anodic dissolution of copper in chloride solutions was studied under laboratory conditions up to 101°C and up to 175°C in a specially designed cell that could be flanged into a pump loop. Under all conditions the anodic polarization curves demonstrated Tafel behavior with slopes equal to 2.3 RT/F. The anodic proce…
Six diatoms achieve dominance in 26 alkaline, saline lakes in East Africa. There is a pronounced tendency for these species to replace each other as alkalinity increases. Cyclotella meneghiniana is usually dominant in less concentrated lakes and Nitzschia frustulum is favored as the alkalinity exceeds 80 meq liter −1…
The dynamics of the distortion of a well-oriented nematic liquid crystal film in a perpendicular field around the Freedericks critical field value is studied both theoretically and experimentally. The experimental thermal and optical techniques have already been used for the description of the equilibrium properties o…
We have observed alignment of nematic, cholesteric and smectic liquid crystals in directions depending on the orientation of submicroscopic, parallel grooves in adjacent glass and fused quartz surfaces. The alignment can be explained on the basis of elastic strain energy in the bulk of the liquid crystal that would be…