Materials Literature
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Pyrolytic films, in thicknesses up to 30,000Aå, were produced by the reaction at 900°C. These films were characterized by use of transmission electron microscopy, electron microprobe analysis, measurement of dielectric, and optical properties. It was found that the films were orthorhombic with a fine grained structure…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTGeneral method for the synthesis of 3- and 3,4-substituted furans. Simple syntheses of perillene and dendrolasinMichael E. Garst and Thomas A. SpencerCite this: J. Am. Chem. Soc. 1973, 95, 1, 250–252Publication Date (Print):January 1, 1973Publication History Published online…
The liquid phase adsorption and reaction of a range of organo-sulfur compounds with ground iron powder were studied in the temperature range 25–170 C. The reactivity of organic disulfides was found to increase along the series: Monosulfides and mercaptans were found to be less reactive than the corresponding disulfide…
The nature of the oxygen species adsorbed on slightly reduced CeO2/SiO2 supported catalysts has been investigated using oxygen enriched with 17O2. The observed hyperfine splitting was found to be associated with the central component of the g tensor; it indicated that the corresponding orbital contained the unpaired e…
Certain compositions within the quaternary lead-lanthanum-titanate-zirconate (PLZT) system exhibit neither a "true" ferroelectric nor a "true" paraelectric behavior and are therefore best characterized as quasi-ferroelectric. The dielectric, hysteresis, and optical properties of quasi-ferroelectric PLZT ceramics have…
A convenient, large-scale method for separation of the aand b series metal-free chlorophyll derivatives is described, utilising the Girard ‘T’ reagent with subsequent chromatography. Efficient procedures for conversion of phaeophytin-a(3) into rhodoporphyrin-XV dimethyl ester (1) and the corresponding 2-vinyl compound…
The crystal structure of triglycine sulfate has been refined at 19°C and 37°C in the ferroelectric phase and at 57°C in the paraelectric phase, by using the data collected by a four-circle automatic diffractometer. Positions of 14 hydrogen atoms out of the 17 have been determined and those of the non-hydrogen atoms re…
Each of the formate, acetate, monochloroacetate, trichloroacetate, phenylacetate, and benzoate complexes iron (III), prepared and characterized for study is triangular trinuclear in structure and contains six bridging carboxylate ligands and a central bridging oxygen. Magnetic susceptibility measurements from room tem…
We present results of a self-consistent band calculation of the ground-state energy and charge orderings based on a tight-binding scheme in magnetite. The calculation is greatly simplified by making use of the large intra-atomic Coulomb interactions between electrons on the Fe ions, previous estimates of the crystal f…
The vibronic theory of ferroelectric phase transitions is reviewed and the essential contribution of electron-phonon interaction into the microscopic origin of the ferroelectricity is demonstrated. In the narrow-gap (semiconducting) systems the soft mode is caused by interband vibronic interaction and the temperature…
In order to characterize the ultrastructural alterations of cells, vasculature and fibrils that occur on the pressure side of the periodontal ligament when teeth are subjected to orthodontic forces of a magnitude generally used in clinical practice, eleven premolar teeth were moved buccally by means of a fixed applian…
A rate theory of the growth of irradiation-produced interstitial loops in uniaxially stressed materials which also contain voids, coherent and/or incoherent precipitates and network dislocations is derived and the resulting creep behaviour is determined. Allowance is made for the preferential nucleation of loops orien…
A class of crystalline substances is recognized in which changes of chemical composition are accompanied neither by forming a step-wise succession of phases nor by forming nonstoicheiometric or solid solution phases with disordered, defect structures. Instead, every composition orders into a superlattice and the diffr…
The solvent acid‐base properties of melts containing 50–70 mole per cent at temperatures of 175°–355°C are fully described by the use of three equilibrium constants At 175°C the K values on the mole fraction scale are , respectively. The Δ H and Δ S values for each equilibrium were found to be temperature independent…
Abstract Reduction of insoluble collagens from bone, skin, and tendon with NaB3H4 produced several radioactive substances which were isolated from acid hydrolysates of the protein. One of these substances, aldol-histidine, was most abundant in cow skin collagen and also appeared in reconstituted fibrils of purified co…
The microscopic theories which have been proposed for lyotropic liquid crystals are studied, in particular in connection with the model gas of hard rods. For sufficiently long rods most theories are equivalent to that of Onsager; for shorter rods no theory seems to have a very good claim to accuracy. The theory of Flo…
An oxide film on a metal surface will thicken only if metal, or oxygen, or both, migrate across it. The relative magnitude of the metal and oxygen migrations can be determined using markers, and the possible results are reviewed for the ideal case of a homogeneous oxide grown to uniform thickness on a plane metal surf…
Résumé. 2014 On décrit les propriétés thermodynamiques et les diagrammes T-x de l’équilibre liquide-solide dans les systèmes ternaires II-VI et IV-VI par un modèle de solution régulière asso-ciée, dérivé de celui utilisé par Jordan pour le liquide et dans l’hypothèse d’une solution régulière pour le solide. Pour les s…
Two main systems of approach used to determine if algae can reliably indicate water quality are discussed in this paper. One approach is to observe and analyze natural communities. The effect of a pollutant can be estimated by shifts in species composition and structure of the community in this type of study. The seco…
The dihedral angle between the rings of biphenyl is determined to be 32 ± 2° in the molten and solution states. Observed vibrational frequency shifts on going from the planar configuration held in the crystal to the non-planar solution state are compared with computed frequency shifts. To improve the accuracy in the c…