Materials Literature
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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…
Abstract The limits n αmax and n βmin of the two‐phase region of PdH n can only roughly be estimated from the shape of the equilibrium isotherms p H2 ( n ). Other methods applied so far do not yield more accurate results. More precise values can be obtained, however, from measurements of the magnetic susceptibility x…
The aluminum (2p) electron spectra of several anhydrous and “hydrous” aluminum oxides have been recorded, and the binding energies have been measured. A simple electrostatic model is employed to explain the observed shift in binding energy and relate it to differences in structure and hydrogen bonding. Two conclusions…
The systems , , and were studied. It was found that the solid solubility of Ce 3+ in varies with the atmosphere during firing. Only 2 mole per cent (m/o) of Ce 3+ can be dissolved in the yttrium aluminum garnet in air while almost 6% Ce 3+ enters the garnet lattice when fired at 1450°C under a hydrogen atmosphere. Com…
The efficiency of Mn(IV) luminescence in fluorine coordination is discussed in the context of the chemical bonding in the center. It is possible that the lower degree of σ‐antibonding in the orbitals, and the greater degree of π‐antibonding in the orbitals, compared with the effect observed in oxides, contributes to a…
Previous work on transverse impact of single textile fibers is reviewed and extended to model orthogonal weaves in which fiber crossovers are simplified as pin. joints. A dynamic finite-element computer technique previously developed for single fibers is extended to model the woven panel, and this method is shown to p…
Chatelain hypothesized that orientation of liquid crystals by interaction with the substrate is due to an adsorbed layer of fatty contaminants, but substrate topography has also been postulated as a causal factor. Experiments with chemically cleaned surfaces rubbed without contamination now confirm the importance of t…
A simple expression for the magnetoresistance of the antiferromagnetic metals due to the electron-spin scattering by the s - d interaction is obtained using the molecular field approximation for the spin system. The expression includes the ferromagnetic case. It is shown that in the antiferromagnetic case the positive…
The P2Co4(H2O)2W18O6810– anion contains four edge-linked coIIO6 octahedra with coplanar cobalt atoms, in addition to two fragments of the Keggin structure.
Die seit der Vollendung des tschechischen Manuskripts dieses Buches verlaufene Zeit lieB einige Erganzungen des Textes zwecks Erfassung des neuesten Standes unserer Kenntnisse auf dem Gebiete der magnetischen Oxide als unerlaBlich erschei-