Materials Literature
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Possible losses of trace elements during dehydration of marine zoological material with a high water content were studied by means of radioactive tracers, using the oyster Crassostrea gigas as an example. It is probable that no losses occurred with chromium, iron, manganese, cobalt and zinc, but serious losses of sele…
Analytical methods are given which enable one to describe geometrically layers of large curvature in a smectic phase. Dupin cyclides in focal domains are taken as examples. The curvature energy of focal domains is calculated. The difference between normal focal domains (built on an ellipse and an hyperbola), and parab…
The possibility of the smectic A to C phase transition is discussed, using a model based on the dipole-dipole interaction of the polar bonds of the molecules, which are supposed to rotate randomly around their long axis in both the A and C phases. Two different choices of the two-particle distribution function are use…
Thin gold films were vapor deposited onto KCl single crystals under a variety of substrate temperatures, residual gas pressures, and deposition rates. The films were subsequently examined by high‐resolution transmission‐electron microscopy. The use of the defocus contrast technique revealed a large number of small (10…
Abstract Significance of symmetry in representing real‐ and reciprocal‐space properties of a crystal and of its constituents is discussed in terms of symmetry eigenfunctions. The formation of the site‐symmetrized multipole expansion for the 32 crystal point symmetries is shown, and the mutual relations between the rea…
Abstract A computer program is described that permits the refinement of the static charge deformation in a flexible atom‐centered multipole expansion, together with positional and vibrational parameters, against X‐ray and neutron data. Other options allow for rigid‐body constraints on some or all of the atomic vibrati…
Abstract Shake‐up phenomena in a series of para ‐substituted polystyrenes have been studied by ESCA. Comparison with other spectroscopic data and with theoretical calculations within the sudden approximation, equivalent cores model, and CNDO SCF MO formalism identifies the shake‐up structures as arising predominantly…
Evidence is provided that silver zeolites can be used for the decomposition of water into hydrogen and oxygen; the process consists of a photochemically induced reduction of the zeolite, followed by an oxidative thermal desorption of hydrogen.
Permittivity, dielectric loss tangent, radial coupling coefficient, and radial frequency constant have been measured as a function of composition for pressure‐sintered Li. r Na 1‐x NbO 3 in the range 0.015≤x≤0.15. An anomaly in each of these properties when plotted as a function of composition is associated with a str…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis of binary gold carbonyls, Au(CO)n (n = 1 or 2). Spectroscopic evidence for isocarbonyl(carbonyl)gold, a linkage isomer of bis(carbonyl)goldD. McIntosh and G. A. OzinCite this: Inorg. Chem. 1977, 16, 1, 51–59Publication Date (Print):January 1, 1977Publication Histor…
Because of their high symmetry, most of the silica polymorphs contain only a few nonequivalent Si–O distances. However, the structure of coesite contains two nonequivalent silicate tetrahedra, eight Si–O bonds, five Si–O–Si and twelve O–Si–O angles, thus making it an excellent candidate for testing Si–O bonding theory…
The interaction of a number of nitrogen containing molecules (NO, NH3 and N2H4) with copper has been investigated by electron spectroscopy. Nitric oxide is shown to be molecularly adsorbed in a linearly bonded configuration at 85 K; this adlayer is unstable above 120 K, resulting in an exclusively oxygen adlayer at 29…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTReductive coupling of adjacent ligands in a seven-coordinate molybdenum(II) isocyanide complexC. T. Lam, P. W. R. Corfield, and S. J. LippardCite this: J. Am. Chem. Soc. 1977, 99, 2, 617–618Publication Date (Print):January 1, 1977Publication History Published online1 May 200…
The temperature dependences of the second moments M2 of the proton magnetic resonance absorption spectra and of the proton spin–lattice relaxation times T1 of perovskite layer compounds (CnH2n+1NH3)2CdCl4 with n=1–3 and (NH3– (CH2)n–NH3) CdCl4 with n=2−5 have been studied together with the frequency dispersion of T1.…
Infrared reflection spectra and Raman spectra at several temperatures between 2 K and 350 K have been observed for triglycine sulphate and the isomorphous compound triglycine selenate. A complete group theoretical enumeration of the phonon modes is given and the observed frequencies have been tabulated for different t…
A sample of p-Hexyl-Oxy-Benzylidne-p'-Amino-2-Chloro-Propyle-Cinnamate, Chiral liquid crystal, is oriented in the ferroelectric smectic C-phase by a square wave field ± E; its permanent polarization orients itself from + P to — P in a time adjustable with E. This time is chosen to obtain an induced transient current,…
The lecture provides a survey on the actual status of the heat and light stabilization of PVC with special emphasis on the mode of action of the stabilizers. In the first part a brief treatment of the most important facts of the thermal degradation of PVC are given, followed by a discussion of some proved specific fun…
X-ray diffraction experiments of a single crystal of magnetite at 84 K were carried out to investigate the crystal symmetry below the transition temperature. A new lattice deformation which makes the crystal symmetry lower than rhom-bolaedral was clarified. The extra reflections which appear in the low temperature pha…
The static dielectric constants of the following compounds have been measured as functions of temperature in their nematic and isotropic phases: (i) 4'-n-alkyl-4-cyanobiphenyls, (ii) tras-p-n-alkoxy-α-methyl p'-cyanophenyl cinnamates and (iii) CBOOA. All these exhibit a very large positive dielectric anisotropy becaus…
Freeze-fracture electron microscopy has been used to examine defect structures such as confocal domains, screw dislocations, disclinations, and walls in lamellar phospholipid phases containing known amounts of water (from about 5 to 65% by weight). In a concurrent study (Costello and Gulik-Krzywicki 1976) all samples…