Materials Literature
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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…
Infrared spectroscopy was used to monitor and characterize solutions used in the preparation of PZT 53/47 powders, dried gels, and thin layers deposited on platinized silicon substrates. It was found that careful control of the chemistry of the precursor solutions, in particular the control of the formation of esters…
Not an electronic circuit, but a chemical formula of a huge metal complex is depicted here. The circles stand for metal centers, the zigzags for bridging ligands, and the dashes for terminal ligands. The Ru22 complex, which belongs to the class of cascade compounds (arborols/dendrimers), is the largest Werner-type com…
Abstract The luminescence and excitation spectra of electronic excitations localized near a single anion vacancy (e α ), a divacancy (e d ), and a vacancy quartet (e q ) are investigated. The shifts of spectral characteristics of these excitations with respect to those of the excitations in regular lattice sites (e r…
A method for calculating the vibrational densities of states of crystalline materials by use of molecular dynamics (MD) is presented. It consists mainly of starting the calculation with all atoms at rest in their equilibrium positions, except one which is given an initial velocity; the time evolution of this velocity…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolymer brushes in mixed solvents: chromatography and collapsePik Yin Lai and Avi HalperinCite this: Macromolecules 1992, 25, 24, 6693–6695Publication Date (Print):November 1, 1992Publication History Published online1 May 2002Published inissue 1 November 1992https://pubs.acs…
Abstract Carbon black is the most important reinforcing filler for rubbers. The incorporation of carbon black into rubber vulcanizates generally gives improved strength, extensibility, fatigue resistance, abrasion resistance, etc. In order to exert its beneficial influence on the properties of rubber vulcanizates, the…
Reactions of trans-Ti(TMEDA)2Cl2 (TMEDA = N,A,N,N'-tetramethylethylenediamine) with 2 equiv of RONa IR = Ph, 3,5-(t-Bu)2C6H3] formed the paramagnetic light-green linear trimeric Ti(III) derivative Ti3(PhO)9-(TMEDA)2 (1) and the pink dimeric complex [Ti(RO)Cl(TMEDA)]2(mu-OR)2[R = 3,5-(t-Bu)2C6H3](2),respectively. Compl…
In compiling the space-group-frequency table of observed structures, retention of all the 230 space groups is advocated. This is based on some of the fundamental aspects of chirality. For cases both with space-group chirality (case A, e.g. P41, P43 etc.) and without (case B, e.g. P21, P212121), possible asymmetric dis…
The carbon concentration trapped in films of austenite between parallel platelets of bainite is often found to be much larger than that in the larger blocks of austenite between sheaves of bainite. The effect of this non-uniform distribution of carbon on the overall transformation kinetics of bainite is examined theor…
By varying the incident laser wavelength, the intrinsic Raman spectrum of porous silicon formed on nondegenerate p-type silicon is identified and used to determine the dependence of the average pore size and porosity on the depth of the porous silicon layer. It is found that with increasing layer depth, the average po…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLow-spin tris(quinone oximates) of manganese(II,III). Synthesis, isomerism, and equilibriaPartha Basu and Animesh ChakravortyCite this: Inorg. Chem. 1992, 31, 24, 4980–4986Publication Date (Print):November 1, 1992Publication History Published online1 May 2002Published inissu…