Space group and lattice constants of Ca10(PO4)6CO3
Ca10(PO4)6CO3 is an `apatite' with pseudo-hexagonal symmetry with monoclinic space group Pb and lattice constants a = 9.557 (3) A, b ≃ 2a, c = 6.872 (2) A and γ = 120.36±0.04°.
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Polyoxoanion-supported metal carbonyls: syntheses of the [(OC)3M(Nb2W4O19)]3- anions (M = rhenium and manganese)
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolyoxoanion-supported metal carbonyls: syntheses of the [(OC)3M(Nb2W4O19)]3- anions (M = rhenium and manganese)C. J. Besecker and W. G. KlempererCite this: J. Am. Chem. Soc. 1980, 102, 25, 7598–7600Publication Date (Print):December 1, 1980Publication History Published onlin…
Comparative study of various methods for thermogravimetric analysis of polystyrene degradation
Various methods of thermogravimetric analysis were compared in case of polystyrene degradation. The reaction order, the activation energy and the preexponential factor were evaluated from common TG curves experimentally obtained. In most cases a 5-mg sample of polystyrene with 110,000 molecular weight was decomposed a…
Structural Studies on Two High‐Mobility‐Group Proteins from Calf Thymus, HMG‐14 and HMG‐20 (Ubiquitin), and Their Interaction with DNA
High mobility group (HMG) protein 14, which, like HMG-17, has been implicated in the structure of 'active chromatin' is shown by 270-MHz NMR and by circular dichroism to be in a disordered conformation in free solution. At low ionic strength protein HMG-14 binds to DNA by weak attachment of the N-terminal half of the…
The application of electron spin resonance spectroscopy to studies of clay minerals: I. Isomorphous substitutions and external surface properties
Abstract Electron spin resonance (ESR) spectroscopy has contributed significantly to the identification and characterization of paramagnetic impurities associated with clays. Following a brief discussion of the general principles of the technique, a review is given of the application of ESR to the study of those param…
Formation and properties of Fe(II)Fe(III) hydroxy-carbonate and its possible significance in soil formation
Abstract Small amounts of Fe(III) induce precipitation of Fe(II) from carbonate solutions around neutral pH values. The reaction involves the formation of Fe(II)Fe(III) hydroxycarbonate, a green, layer-structured compound of the pyroaurite group of minerals. Variations in the concentration of Fe(II) in the solution ph…
Critical Phenomena and Anomalous Thermal Hysteresis Accompanying the Normal-Incommensurate-Commensurate Phase Transitions in Rb2ZnCl4
Measurements were made of the dielectric constant along the ferroelectric axis ε a , the spontaneous polarization P s and the heat capacity c p of Rb 2 ZnCl 4 crystals in the temperature range from -150^° C to 150°C. The normal-incommensurate transition point determined as the peak position of c p lies at 30.1°C, whic…
Fracture Mechanics Applied to Brittle Materials
This state-of-the-science publication on fracture test techniques for glass, ceramics, rocks, and cementitious composites is a compilation of 14 papers which were presented at the Eleventh National Symposium on Fracture Mechanics, which was held June 12-14,1978, at Virginia Polytechnic Institute and State University,…
Liquid Crystal Polymers. IV. Liquid Crystalline Aromatic Polyesters
Abstract Melt‐spun and injection‐moulded liquid crystalline polyesters have very high strength and stiffness and a very low coefficient of linear thermal expansion. The exceptional properties that characterise these polyesters are due to the presence of stiff, rod‐like polymeric chains, which become highly oriented du…
EDINP, the Edinburgh powder profile refinement program
A powder profile refinement program written specifically for the easy application of structural constraints is made generally available. It is based on ORFLS and written in Fortran IV. Details of the philosophy of the program are outlined, with emphasis on the areas where more research is necessary. Examples of usage…
Wool as a Biological Composite Structure
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTWool as a Biological Composite StructureHelmut Zahn, Josef Föhles, Magdalene Nlenhaus, Annette Schwan, and Manfred SpelCite this: Ind. Eng. Chem. Prod. Res. Dev. 1980, 19, 4, 496–501Publication Date (Print):December 1, 1980Publication History Published online1 May 2002Publis…
Secondary Emission from Polymers
The available data on secondary emission yields from electron bombarded polymers was reviewed to identify those features they have in common with metals and inorganic insulators. As in the case of the more widely studied materials it was found that when the yield δ obtained at a bombarding electron energy Eo, is divid…
Li12Si7, a Compound Having a Trigonal Planar Si4 Cluster and Planar Si5 Rings
Three-pointed planar Si4 stars with unelucidated bonding and planar Si5 rings have been found in Li12Si7. In the formulation shown below with x = 4 and y = 10 the star could be an excited tetrahedrane state as Si; for x = y = 8 the star would be Si and isoelectronic with the carbonate ion.
Increased yield of a desired isomer by equilibriums displacement on binding to silica gel, applied to meso-tetrakis(o-aminophenyl)porphyrin
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIncreased yield of a desired isomer by equilibriums displacement on binding to silica gel, applied to meso-tetrakis(o-aminophenyl)porphyrinJonathan LindseyCite this: J. Org. Chem. 1980, 45, 25, 5215Publication Date (Print):December 1, 1980Publication History Published online…
The Chemical Nature of Aluminum Corrosion: III . The Dissolution Mechanism of Aluminum Oxide and Aluminum Powder in Various Electrolytes
Attention was focused on the first steps in the pitting process, the adsorption of aggressive anions and the dissolution of aluminum oxide. The adsorption of chloride on alumina and aluminum powder are quite similar and show a saturation plateau at high chloride concentration; the amount of chloride adsorbed is propor…
Cation vacancies and the crystal chemistry of breakdown reactions in kimberlitic omphacites
The degree of alteration in clinopyroxenes from eclogitic inclusions in South African kimberlites is directly related to the deviation from stoichiometry of remnant unaltered areas in individual grains. Deviations from stoichiometry are reconciled by allowing up to 9% vacancy in the M2 site. The breakdown reaction acc…
Stress calculations for interfacial extrinsic and intrinsic dislocation arrays in anisotropic two-phase media
Explicit expressions are given for the stress fields of extrinsic or intrinsic boundary dislocation arrays on the basis of recent results concerning the elastic properties of interfacial dislocations. It is shown that these stress fields differ only by constant terms. Examples of α-β brass boundaries illustrate anisot…
Electron correlations and electron-lattice interactions in the metal-insulator, ferroelastic transition in VO2: A thermodynamical study
We present a model of the V${\mathrm{O}}_{2}$ phase transition which incorporates both electron-electron and electron-lattice interactions and accounts for the presence of two $d$ bands (${\ensuremath{\pi}}^{*}$ and ${d}_{\ensuremath{\parallel}}$) overlapping at the Fermi level of the metallic phase. Attention is give…
Photoluminescence and photoreduction of vanadium pentoxide supported on porous Vycor glass
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotoluminescence and photoreduction of vanadium pentoxide supported on porous Vycor glassMasakazu Anpo, Ichiro Tanahashi, and Yutaka KubokawaCite this: J. Phys. Chem. 1980, 84, 25, 3440–3443Publication Date (Print):December 1, 1980Publication History Published online1 May 2…
The influence of TiO2 on the structure and derivative properties of silicate melts
The influence of TiO, on the structure of silicate melts has been determined at I atm pressure by laser Raman spectroscopy. The following melt compositions were used: CaSiOr, CaMgSirOu, NarSiOr, NaAlSi3Os, CaAl2OE, and NarTiOr. Titanium is in four-fold coordination in all melts studied, as there are no Raman bands bel…