Materials Literature
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The structure of NaNbO3, phase T2 (immediately below the cubic phase), has been determined from lattice parameters and difference reflections. It is tetragonal C-face-centred, with a= 7·8698(8) Å, c=3·9428(4) Å at 600°c. It corresponds to condensation of an M3 soft-phonon mode from the cubic phase, in contrast to SrTi…
This paper reports field-induced realignment of a nematic liquid crystal. A thin nematic film, which has a negative dielectric anisotropy, is initially homeotropic. Application of a threshold field parallel to the optic axis distorts the nematic ordering and increases the film's birefringence in certain light-propagat…
This paper reports the results of extensive examination of 15 kV and 22 kV polyethylene insulated cables which had been in service for periods of time ranging from less than one year to eight years. Evidence of treeing and related insulation deterioration at normal operating voltage is presented. The investigation is…
The theory of plasmon satellites in experiments where ion cores are excited is developed in a manner which complements the work of one of the authors, which showed how the interaction of slow electrons with plasmons could be treated to all orders in perturbation theory in a certain approximation. Here the fast-electro…
Pyruvate formate-lyase has been demonstrated in Clostridium kluyveri, C. butylicum and C. butyricum. The properties of the clostridial enzyme have been studied in more detail in cell-free lysates of C. butyricum. The following activities were investigated: pyruvate cleavage to acetylBiochemisches Institut der Universi…
Resonance Raman spectra have been obtained from the MnO4 - and CrO4 2- ions in aqueous solutions and as solid. High intensity overtone progressions of the totally symmetric vibration v 1 were observed, allowing estimates of the anharmonicity constants and harmonic frequencies to be made for the v 1 breathing mode. Rel…
Analytical parameters have been recalculated for atomic scattering factors and incoherent scattered intensities of the elements of atomic numbers 2 to 36, based on the tables of Tavard, Nicolas & Rouault [J. Chim. Phys. (1967), 64, 540]. The fit has also been checked with the total scattered intensities.
Abstract A systematic method is described for determining the double‐force tensor of point defects in cubic crystals by analysing diffuse X‐ray scattering in the immediate vicinity of Bragg reflections (Huang‐scattering). Around a given reciprocal lattice point there may occur three types of isointensity surfaces depe…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCrystal structure and moleculsr stereochemistry of .mu.-oxo-bis[.alpha.,.beta.,.gamma.,.delta.-tetraphenylporphinatoiron(III)]A. B. Hoffman, D. M. Collins, V. W. Day, E. B. Fleischer, T. S. Srivastava, and J. L. HoardCite this: J. Am. Chem. Soc. 1972, 94, 10, 3620–3626Public…
The vapor in equilibrium with Ti2O3(s) and Ti3O5(s, β) at 1720°C was examined with a mass spectrometer equipped with a Knudsen cell high temperature inlet system. With 50-eV ionizing electrons, the ions TiO+, Ti+, and TiO2+ were observed. Ionization efficiency curves indicated that Ti+ resulted from dissociative ioniz…
The ground state spin arrangements in magnetic compounds of the NaCl type structure are studied by consideration of exchange interactions between nearest neighbors ( J 1 ) and between next-nearest neighbors ( J 2 ). Ferromagnetic arrangement as well as antiferromagnetic arrangements of the first kind, second kind, and…
A new form of sandwich core of high strength created by a topological transformation of a single plane is proposed herein. The resultant core is to be manufactured from a single sheet through a plastic forming. The purpose of this proposition is to present a sandwich core which has following principal characteristics;…
Wave-propagation effects induced in isotropic materials by either explosive or impact loading uniformly over a planar surface are much simpler than those produced in anisotropic solids in which significant transverse particle motion may occur. Such behavior in linearly elastic anisotropic solids has been investigated…
In twinned crystals the intensity contribution from the separate individuals can be estimated from the observed intensities without any knowledge of the actual structure, even when the two reciprocal lattices are completely superimposed. Once the separate intensity contributions are known the trial structure can be so…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLigand binding by metalloporphyrins. III. Thermodynamic functions for the addition of substituted pyridines to nickel(II) and zinc(II) porphyrinsS. J. Cole, G. C. Curthoys, E. A. Magnusson, and J. N. PhillipsCite this: Inorg. Chem. 1972, 11, 5, 1024–1028Publication Date (Pri…
A model Hamiltonian has been constructed for the ferroelectric transition in the perovskite structure in terms of localized-strain and soft-normal-mode coordinates and temperature-independent model parameters. No anharmonic interactions higher than fourth order are considered. The free energy for tetragonal, orthorhom…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStereochemistry of asymmetric silicon. XX. Hydroxylation and carbene insertion reactions of R3SiHL. H. Sommer, L. Arie Ulland, and G. A. ParkerCite this: J. Am. Chem. Soc. 1972, 94, 10, 3469–3471Publication Date (Print):May 1, 1972Publication History Published online1 May 20…
Abstract Thermal conductivity measurements were made on polyethylene samples which had been crystallized at different temperatures in order to vary density and lamellar crystal thickness. Tests were also made on polyethylenes which were oriented by mechanical shearing and by crystallization in a temperature gradient.…
Strength degradation and crack propagation in Al 2 O 3 are shown to depend on the initial strength and grain size of the material. The strengths of single‐crystal sapphire and polycrystalline Al 2 O 3 specimens with grain sizes of 10, 34, and 40 μ m decreased discontinuously at the critical quenching temperature. In c…
The degree of roughness of a metallic adherend is frequently a design option for an adhesive joint. But which direction should be taken for optimum joint strength? Should the surface be polished or macroscopically roughened, or is roughening inconsequential? In practice, roughening is generally recommended, but upon w…