Materials Literature
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An alternative procedure is developed to the smoothed linear fitting method of McDonald and Owen. The procedure is based on the detection of discontinuities by comparing, at any given position, three smooth fits. Diagnostics are used to detect discontinuities in the regression function itself (edge detection) or in it…
Polycrystalline films of ZnS with a slight excess of S have been grown on (100) Si by congruent sublimation from a single Knudsen cell. Intense blue emission is observed at 460 nm from room-temperature photoluminescence studies, and is ascribed to S-Zn vacancies acting as self-activated (SA) centres. The emission is q…
Cyclopropane fatty acid (CFA) synthase of Escherichia coli catalyzes a modification of the acyl chains of phospholipid bilayers. We report (i) identification of the CFA synthase protein, (ii) overproduction (> 600-fold) and purification to essential homogeneity of the enzyme, and (iii) the amino acid sequence of CFA s…
Coordination of Ru(NH_3)_5 groups to the four pyridine sites in cobalt meso-tetrakis(4-pyridyl)porphyrin adsorbed \non pyrolytic graphite electrodes produces the tetraruthenated complex which acts as a catalyst for the four-electron reduction of O_2 to H_2O. The adsorbed catalyst, prepared by this heterogeneous co…
The adhesion and interfacial bonding between nonreactive liquid metals and solid inocovalent oxides are studied on the basis of the experimental work of adhesion W data. An analysis of the experimental W values of different liquid metals on various solid oxides is first performed to put into evidence the dependences o…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructure of polymer-protected palladium-platinum bimetallic clusters at the oxidized state: extended x-ray absorption fine structure analysisMasafumi Harada, Kiyotaka Asakura, Yasumitsu Ueki, and Naoki ToshimaCite this: J. Phys. Chem. 1992, 96, 24, 9730–9738Publication Date…
The electronic structure of cubic ${\mathrm{KNbO}}_{3}$ and ${\mathrm{KTaO}}_{3}$ has been calculated using the self-consistent, scalar-relativistic linear-muffin-tin-orbital method. The calculated density of states (DOS) shows a strong similarity for both materials and is in good accordance to measured photoelectron…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTComparative investigation of the spin-crossover compounds Fe(btz)2(NCS)2 and Fe(phen)2(NCS)2 (where btz = 2,2'-bi-4,5-dihydrothiazine and phen = 1,10-phenanthroline). Magnetic properties and thermal dilatation behavior and crystal structure of Fe(btz)2(NCS)2 at 293 and 130 K…
Abstract Morpholine‐2,5‐dione derivatives having substituents with benzyl‐protected carboxylic acid, benzyloxycarbonyl‐protected amine and p ‐methoxy‐protected thiol groups, respectively, were prepared in 29–58% yield by cyclization of the corresponding N ‐[(2 RS )‐bromopropionyl]‐ L ‐amino acids. Polyesteramides with…
A phenomenological equation of motion for an unstable planar crystalline interface is derived and used to describe the early stages of hill and valley formation. We calculate the critical wave number for the growth of instabilities and the scattering structure function. Predictions for the temperature dependence of th…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInfluence of molecular weight on the melting and phase structure of random copolymers of ethyleneR. G. Alamo, E. K. M. Chan, L. Mandelkern, and I. G. Voigt-MartinCite this: Macromolecules 1992, 25, 24, 6381–6394Publication Date (Print):November 1, 1992Publication History Pub…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA single model displaying all the important centers and processes involved in catalysis by molybdoenzymes containing [MoVIO2]2+ active sitesZhiguang Xiao, Charles G. Young, John H. Enemark, and Anthony G. WeddCite this: J. Am. Chem. Soc. 1992, 114, 23, 9194–9195Publication D…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTRadiation-induced conductivity in polymerized and nonpolymerized columnar aggregates of phthalocyaninePieter G. Schouten, John M. Warman, Matthijs P. De Haas, Johan F. Van der Pol, and Jan W. ZwikkerCite this: J. Am. Chem. Soc. 1992, 114, 23, 9028–9034Publication Date (Print…
Using polarizing microscopy, we study the development of orientation and texture during slow shearing of liquid-crystalline solutions of poly(γ-benzyl-L-glutamate). Shearing of high molecular weight samples that are initially coarsely textured, or are uniformly oriented over regions of 1 mm2, produces a steady state s…
The recent demonstrations of visible light emission from porous silicon, both photoluminescence and electroluminescence, have caught the attention of the semiconductor research community. Such silicon‐based light emitting devices have considerable potential in the opto‐electronics industry. This article reviews the pr…
The vibrational modes in KNbO3 are analyzed using first principles total-energy calculations based on local density functional theory. Normal mode frequencies and eigenvectors are determined for the cubic perovskite structure with wave vectors at the center (Γ) and corner (R) of the Brillouin zone using the frozen-pho…
Using a lactose permease mutant devoid of Cys residue ("C-less permease"), we systematically replaced putative intramembrane charged residues with Cys. Individual replacements for Asp-237, Asp-240, Glu-269, Arg-302, Lys-319, His-322, Glu-325, or Lys-358 abolish active lactose transport. When Asp-237 and Lys-358 are si…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNanoarchitectures. 3. Aggregation of hexa(phenylacetylene) macrocycles in solution: a model system for studying .pi.-.pi. interactionsJinshan Zhang and Jeffrey S. MooreCite this: J. Am. Chem. Soc. 1992, 114, 24, 9701–9702Publication Date (Print):November 1, 1992Publication H…
Abstract Enantioselective epoxidation of unfunctionalized olefins with combined use of molecular oxygen, an oxidant, and pivalaldehyde, a reductant, was demonstrated in the presence of a catalytic amount of optically active Mn(III)-salen complexes. Dihydronaphthalene derivatives were converted into the corresponding o…
The evolution of irradiation damage cascades in a metal has been simulated by molecular dynamics, using a many-body potential. Over 100 cascades have been produced with random knock-on directions and primary knock-on atom (PKA) energies ranging from 60 to 2 keV. The cascade evolution has been followed for times typica…