Materials Literature
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This work deals with the changes in mechanical properties of yttrium oxide ceramics induced by nonstoichiometry. The maximum fracture toughness, K lc , is observed at the stoichiometric composition. For an oxygendeficient ceramic, a decrease of K lc is observed from 3.5 to 2.3 MPa.m 1/2 . On the other hand, the Vicker…
In an effort to clarify the effects of molybdenum, which greatly retards the kinetics of temper embrittlement of alloy steels, the incidence of intergranular fracture and the segregation of phosphorus and other elements to grain boundaries were studied in a series of Fe-Mo-P alloys by means of fracture experiments in…
Abstract The production of a polymer containing basic functional groups via the reactive processing of polyethylene was investigated. Grafting of dimethylamino ethyl methacrylate, DMAEMA, to linear low‐density polyethylene in the melt was carried out, and the effects of initiator type, feed composition, and reaction t…
Effects of n -type dopants Si and Se on band-gap energy ( E g ) and on sublattice ordering for Ga 0.5 In 0.5 P grown by metalorganic vapor phase epitaxy, under conditions in which E g shows anomalously low E g values if the doping is not carried out, were studied by means of photoluminescence and transmission electron…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotoinduced electron transfer on a single .alpha.-helical polypeptide chainMasahiko Sisido, Ryo Tanaka, Yoshihito Inai, and Yukio ImanishiCite this: J. Am. Chem. Soc. 1989, 111, 17, 6790–6796Publication Date (Print):August 1, 1989Publication History Published online1 May 20…
Abstract High-resolution transmission electron microscopy (HRTEM) has shown regions of crystallites within noncrystalline matrices of three types of glass (volcanic glass, alkalic igneous glass, and synthetic, nuclear-waste-form glass) The volcanic glass fragments showed domains having 3-Å spacings. About 30% of the f…
Abstract Adsorption isotherms for water on homoionic (Ca 2+ , Li + , Na + , and K + ) exchanged forms of Crook County, Wyoming, montmorillonite (CMS Source Clay SWy-1) were measured between 25° and 70°C using a vacuum microbalance having automated control of water vapor pressure. From these adsorption data, integral e…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPuwainaphycin C, a cardioactive cyclic peptide from the blue-green alga Anabaena BQ-16-1. Use of two-dimensional carbon-13-carbon-13 and carbon-13-nitrogen-15 correlation spectroscopy in sequencing the amino acid unitsRichard E. Moore, Volker Bornemann, Walter P. Niemczura,…
The structures of the complexes of carboxypeptidase A with the amino acids D-phenylalanine and D-tyrosine are reported as determined by x-ray crystallographic methods to a resolution of 2.0 A. In each individual study one molecule of amino acids binds to the enzyme in the COOH-terminal hydrophobic pocket: the carboxyl…
The effect of gamma irradiation on the physicochemical properties of injectable human amnion collagen was investigated. Pepsin-extracted human amnion collagen was purified, reconstituted, and irradiated with varying doses of gamma irradiation (0.25 Mrads to 2.5 Mrads). Gamma irradiation had a significant impact on the…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMetalloporphyrin .pi.-cation radicals: intrinsically ruffled or planar core conformations? Molecular structure mesitylporphinatocopper(II) hexachloroantimonateHungsun Song, Christopher A. Reed, and W. Robert ScheidtCite this: J. Am. Chem. Soc. 1989, 111, 17, 6865–6866Publica…
Synthesis and accumulation of poly(β-hydroxy-alkanoate) in Rhizobium leguminosarum, R. leguminosarum biovar. trifolii, Rhizobium ‘galega’, Rhizobium ‘hedysarum’ and R. meliloti were studied. Poly(β-hydroxybutyrate) is accumulated up to 55% of the cell dry weight. At 30–50% air saturation R. meliloti accumulates 50% of…
Stoichiometric polycrystalline magnesium aluminate spinel has been irradiated at 25° and 650°C with 2.4‐MeV Mg + ions to a fluence of 1.4 × 10 21 ions/m 2 (∼35 dpa (displacement per atom) peak damage level). Microindentation hardness measurements and transmission electron microscopy combined with energy dispersive X‐r…
Abstract Results of an investigation of isothermal crystallization and thermal behavior of poly(ethylene oxide)/poly(ethyl methacrylate) (PEO/PEMA) blends are reported. The blend composition and the crystallization temperature strongly influence the crystallization process from the melt and the melting temperature of…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOrganolithic macromolecular materials derived from vinyl-functionalized spherosilicates: novel potentially microporous solidsPradyot A. AgaskarCite this: J. Am. Chem. Soc. 1989, 111, 17, 6858–6859Publication Date (Print):August 1, 1989Publication History Published online1 Ma…
A method of optimizing the thermally averaged structure of a defect in a crystal at a finite temperature is presented. The basic idea is to augment the interatomic forces that apply at OK with temperature-dependent contributions that arise from the minimization of the free energy at a finite temperature. The structure…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSolubilization, solutions, and processing of aromatic heterocyclic rigid rod polymers in aprotic organic solvents: poly(p-phenylene-2,6-benzobisthiazolediyl) (PBT)Samson A. Jenekhe, Paul O. Johnson, and Ashwini K. AgrawalCite this: Macromolecules 1989, 22, 8, 3216–3222Public…
A possible mechanism for regulating the lateral growth of collagen fibrils in vivo is considered. A growth inhibitor associated with a particular part of the long semiflexible collagen molecule restricts that part of the molecule to the surface of the growing assembly. Lateral accretion ceases when these inhibitors fo…
The presence of a compatibilizing agent permits the blending of otherwise incompatible polymers to yield polyblends or alloys with unique properties, generally not attainable from the individual components. Block and graft copolymers possessing segments with chemical structures or solubility parameters which are simil…
In this paper, a simple model for the charge transfer in thin-film, ac-driven electroluminescent structures of doped ZnS type is proposed. We first review the minimal assumptions needed to account for the carrier emission under high-field conditions and its subsequent feedback on the field strength; it opens the way t…