Materials Literature
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A new formulation of superspace symmetry in incommensurate structures which stresses its physical basis and avoids the "supercrystal" picture is presented. Superspace groups are introduced through the invariance properties of the Landau free-energy expansion for these types of materials, without making any reference t…
The modulated structure in the incommensurate phase of K 2 SeO 4 has been analyzed at 113 K by X-ray diffractometry based on the concept of four-dimensional space. The final R -factor was 0.046 for all 905 reflections and 0.087 for 326 satellite reflections. The modulation is characterized by the rotation of SeO 4 gro…
In corrosion tests with iron- and nickel-based alloys in simulated cooling gases of the primary circuit of high-temperature gas-cooled reactors (HTGR helium), different effects have been found. The materials may be carburized or decarburized, depending on gas composition, gas supply rate, and test temperature. The sur…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTArene exchange reactions of (arene)tricarbonylchromium complexesT. G. Traylor, Kevin Stewart, and Martin GoldbergCite this: J. Am. Chem. Soc. 1984, 106, 16, 4445–4454Publication Date (Print):August 1, 1984Publication History Published online1 May 2002Published inissue 1 Augu…
X-ray structure amplitudes [F~o[ for urea at 123 K have been derived experimentally for 318 reflections, IF[ > 3tr(Fo), sin 0/h < 1.15 ,~-~. Corresponding amplitudes [F'ol have also been calculated for a simulated crystal structure with the charge density derived from a 6-31G** wavefunction for the isolated urea molec…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStoichiometry and kinetics of p-methoxytoluene oxidation by electron transfer. Mechanistic dichotomy between side chain and nuclear substitutionC. J. Schlesener and j. K. KochiCite this: J. Org. Chem. 1984, 49, 17, 3142–3150Publication Date (Print):August 1, 1984Publication…
Cathodoluminescent properties of Eu 2+ ‐ or Ce 3+ ‐activated and phosphors are investigated at 300 K. It is found that exhibits a high energy efficiency (∼16 %) and an improved water‐resistance if residual oxide content is less than 1 m/o. Under these highly sulfurizing conditions, is confirmed to be completely miscib…
Pure Al foil specimens were galvanostatically anodized in a neutral phosphate solution , and the thickness and composition profile of the formed oxide films were examined as functions of the anode potential and current density (c.d.). Analysis of the films was made by chemical sectioning with a solution, combined with…
We report a high-resolution x-ray diffraction study of the freezing transitions of krypton on graphite for coverages above one monolayer. For pressure $P>430$ Torr there is a single continuous incommensurate-fluid-to-incommensurate-solid freezing transition. For $P<430$ Torr the freezing at fixed pressure is dou…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPyrazole/imidazole and pyrazolato/imidazolato complexes of pentacyanoferrate(II/III) and pentaammineruthenium(II/III). LMCT transitions of low-spin d5 complexesCraig R. Johnson, Wayne W. Henderson, and Rex E. ShepherdCite this: Inorg. Chem. 1984, 23, 18, 2754–2763Publication…
Abstract The influence of chemical structure on mechanical properties of polyurethane ionomers (PU ionomers) has been examined. NCO‐terminated prepolymers prepared from primarily 4,4‐methylene bis(phenyl isocyanate) (MDI) and poly(oxytetramethylene) glycol (PTMO) were chain extended with tertiary amine‐containing diol…
Abstract Polypyrrole films prepared by anodic polymerization of pyrrole on Pt or SnO2-coated glass show redox behavior in aqueous electrolyte solutions containing a supporting electrolyte alone. Transfer of electrolyte anions into and from the film is involved in the redox reaction similarly with acetonitrile solution…
Article Studies on clathrasils. IV. Crystal structure of dodecasil 1 H, a synthetic clathrate compound of silica was published on August 1, 1984 in the journal Zeitschrift für Kristallographie - Crystalline Materials (volume 166, issue 1-4).
Two systems were used to generate collagen fibrils in vitro by enzymic cleavage of intermediates in the conversion of procollagen to collagen. In one system fibrils were generated by using procollagen NH2-terminal proteinase to cleave pNcollagen, the intermediate which contains the NH2-terminal but not the COOH-termin…
Ellipsometry and ac impedance measurements were employed for in situ investigation of anodic oxide films on Ru and of oxide films formed by thermal decomposition of Ru chloride. An instrumental setup for experiment control, data acquisition, and data analysis in automated measurements of the ellipsometric parameters a…
Article Bergslagite, a mineral with tetrahedral berylloarsenate sheet anions was published on August 1, 1984 in the journal Zeitschrift für Kristallographie - Crystalline Materials (volume 166, issue 1-4).
Abstract Neu dargestellt wurde Na 5 [MnO 4 ] aus den binären Oxiden [500°C, 14 d, Ag‐Bömbchen] als braunes Pulver bzw. in Form roter Einkristalle [700°C, 3d]. Die orthorhombische Kristallstruktur (a = 5,822, b = 7,769, c = 6,005 Å, 609 I o (hkl), R = 0,030, MoKα, Zweikreisdiffraktometerdaten (Stasi, Fa. Stoe)) ist dur…
Abstract A design of a high‐temperature cell (used with a Spex‐1403 Ramalog spectrophotometer) for Raman studies with 90° geometry is given. Raman spectra of normal ( d 0 ) and denteriated ( d 12 ) tetramethylammonium chlorides in phases III and II are reported, together with their assignments. On the basis of the tem…
This paper describes HV laboratory tests to study the surface leakage current performance of desert-exposed insulators. It was found that inland desert meteorological conditions and contamination vary considerably from coastal desert areas. Leakage current studies on the simulated desert-polluted insulators exhibit so…
Abstract Dielectric loss measurements are reported for polystyrene, crosslinked polystyrene, polyacrylamide, branched polyacrylamide, and poly(methyl methacrylate) at 1 and 10 kHz f over the temperature range −85 to +100°C. Crosslinking and branching have a pronounced effect on the dielectric relaxation spectra of pol…