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Compositional dependence of spontaneous emission probabilities between initial 4 F 3/2 and terminal 4 I J J = 9/2, 11/2, 13/2, 15/2) levels of Nd 3+ were studied for about 90 samples of silicate, borate, and phosphate glasses using the Judd–Ofelt theory. The effect of the covalency of the Nd–O bond on the magnitude of…
Human profilin is a 15-kDa protein that plays a major role in the signaling pathway leading to cytoskeletal rearrangement. Essentially complete assignment of the 1H, 13C, and 15N resonances of human profilin have been made by analysis of multidimensional, double- and triple-resonance nuclear magnetic resonance (NMR) e…
The phase separation of alloys with two or more components is studied, with emphasis on more than two components. Particular attention is given to differences between multicomponent and binary alloys.Specific topics of the paper include equilibrium theory, aspects of the dynamics, and numerical simulations. In the equ…
An automated structure-refinement program has been developed for X-ray powder diffraction data collected on disordered carbons. The program minimizes the difference between the observed and calculated diffraction profiles in a least-squares sense by optimizing model parameters analogously to the popular Rietveld refin…
Powder diffraction data for semiconductor and metallic states of vanadium dioxide are presented. The structures are refined by Rietveld methods using a monoclinic cell ( a = 5.7529Å, b = 4.5263Å, c = 5.3825Å, β = 122.61°) and space group P2 1 / c for the room temperature data, and a tetragonal cell ( a =4.5540Å, c = 2…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTColored multilayers from transparent submicrometer spheresC. D. Dushkin, K. Nagayama, T. Miwa, and P. A. KralchevskyCite this: Langmuir 1993, 9, 12, 3695–3701Publication Date (Print):December 1, 1993Publication History Published online1 May 2002Published inissue 1 December 1…
Azotobacter vinelandii UWD was grown in a fermentor with glucose medium with and without 0.1% fish peptone (FP) in batch and fed-batch cultures for the production of the natural bioplastic poly-beta-hydroxybutyrate (PHB). Strain UWD formed PHB five times faster than cell protein during growth in glucose and NH(4), but…
Four new synthetic routes to meso-tetraarylporphyrins using a MacDonald-type 2 + 2 condensation are described. Self-condensation of a 5-aryldipyrromethane (e.g., 17) with an aryl-substituted one-carbon bridging unit affords a mixture of tetraarylporphyrins due to acid-catalyzed redistribution reactions. The second and…
Abstract Crystal structures and electrical properties of BETS compounds with tetrahedral anions, MX4− (BETS = bis(ethylenedithio)tetraselenafulvalene; M = Ga, Fe, In; X = Cl, Br) were examined. Every κ-type salt is metallic below 50 K. λ-(BETS)2FeCl4, which is isomorphous to the superconductor GaCl4 salt, undergoes a…
The static and dynamic properties of \ensuremath{\beta}-Sn, SnO, and ${\mathrm{SnO}}_{2}$ are studied using the full-potential linear-muffin-tin-orbital method within the local-density approximation (LDA). Equilibrium lattice parameters and bulk moduli (including pressure variations) are in excellent agreement with ex…
A simple model for ferroelectric fatigue is developed from Landau theory. This model proposes that the general fatigue mechanism is due to the formation of mesoscopic structures of interacting charged lattice defects and opposing domains. It shows that the ionic defects may induce a self-trapping potential by polarizi…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTUnsymmetrical three-dimensional macromolecules: preparation and characterization of strongly dipolar dendritic macromoleculesKaren L. Wooley, Craig J. Hawker, and Jean M. J. FrechetCite this: J. Am. Chem. Soc. 1993, 115, 24, 11496–11505Publication Date (Print):December 1, 19…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSelf-consistent field theory of block copolymers with conformational asymmetryJ. D. Vavasour and M. D. WhitmoreCite this: Macromolecules 1993, 26, 25, 7070–7075Publication Date (Print):December 1, 1993Publication History Published online1 May 2002Published inissue 1 December…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOxide/support interaction and surface reconstruction in the sodium tungstate(Na2WO4)/silica systemZhi Cheng Jiang, Chang Jiang Yu, Xue Ping Fang, Shu Ben Li, and Hong Li WangCite this: J. Phys. Chem. 1993, 97, 49, 12870–12875Publication Date (Print):December 1, 1993Publicati…
Electron cross-sections were summarized for an accurate simulation of the track structure of high energy electrons up to a few MeV in water vapour. Elastic scattering was described by the Rutherford formula taking the screening effect into account. Partial and total ionization cross-sections were calculated using Selt…
Carbon-coated gadolinium carbide nanocrystallites are generated by a process based on the Kratschmer-Huffman carbon-arc method of preparing fullerenes, and a novel magnetic-field-gradient separation technique is used to separate them. This separation of nanocrystalline byproducts of the carbon arc process is a prerequ…
Abstract Novel polymers containing alternating perfluorocyclobutane and aromatic ether subunits are prepared from aryl poly(trifluorovinyl ether) monomers via the thermal [2π + 2π] dimerization of the trifluorovinyl ether functionality. A model study is described, which probes the nature of the perfluorocyclobutane ri…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMolecular electron density Lego approach to molecule buildingP. Duane Walker and Paul G. MezeyCite this: J. Am. Chem. Soc. 1993, 115, 26, 12423–12430Publication Date (Print):December 1, 1993Publication History Published online1 May 2002Published inissue 1 December 1993https:…
Abstract The structures of the series of oligothienyls (T4‐T5‐T6) have been determined and refined from X‐ray powder diffraction data using the Rietveld full‐profile analysis. Unlike polythiophene, all the molecules in the isomorphous series display no internal symmetry, being only approximately planar within 12°. Pac…
Excited-state decays of the special pair of Rhodobacter capsulatus and 10 mutants as a function of temperature are presented. The mutations are at the symmetry-related sites L181 and M208. All the decays are nonexponential, although the degree of nonexponentially depends strongly on the mutant and the temperature. We…