Materials Literature
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Abstract Copolymerizations of ethylene with propene, ethylene with 1‐hexene, and propene with 1‐hexene were performed at 40°C under atmospheric pressure by using the aspecific catalyst composed of TiCl 3 /MgCl 2 and Al(C 2 H 5 ) 3 and the isospecific Solvay‐type catalyst composed of TiCl 3 and Cp 2 Ti(CH 3 ) 2 . In ca…
A new technique to obtain the refractive index and thickness of a thin film simultaneously is presented. The reflectances of p-polarized light and s-polarized light are measured at various angles of incidence, and by a numerical procedure the film index and thickness are extracted from the measured reflectances. The m…
Described below are the results of our investigations of the electrical and electrochemical properties of thin films of polyethylene oxide (PEO) electrolytes [with and without 12‐Crown‐4 ether (12Cr4)] as a function of temperature and in the frequency regime 100 kHz–0.1 Hz. These measurements were made on electrolytes…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMechanistic studies of carbon dioxide insertion into metal hydrides and extrusion from the corresponding metal formates utilizing Group 6 metal carbonyl derivatives as reaction probesDonald J. Darensbourg, Holly Pickner Wiegreffe, and Philip W. WiegreffeCite this: J. Am. Che…
Spinel, MgAl 2 O 4 , has been observed to form on sapphire during sapphire dissolution into CaO‐MgO‐Al 2 O 3 ‐SiO 2 (CMAS) melts at 1450°. and 1550°C. Electron microprobe analysis was used to characterize the sapphire/melt interface for cases in which spinel did (indirect dissolution) or did not (direct dissolution) f…
The UDP-N-acetylmuramoyl-L-alanyl-D-glutamate:meso-2,6-diaminopimelate ligase was over-produced and purified from two plasmid-harbouring strains of Escherichia coli. The first strain, E. coli JM83(pHE5), gave a 15-fold over-production relative to parental strain. The enzyme could be partially purified (8.8-fold) by io…
The crystallization characteristics of a group of 96% Al 2 O 3 ceramics containing a high‐CaO boundary glass were examined using a combination of electron microscopy techniques. As many as six crystalline phases formed at the boundaries during anneals between 1000° and 1350°C. Devitrification was rapid, and little gla…
The ring contraction of a porphycene derivative yields an isocorrole derivative whose ring skeleton deviates significantly more from planarity than that of corrole. According to spectroscopic findings, however, the derivative is an aromatic compound. 1 and 3 are the parent compounds corrole and isocorrole, respectivel…
Abstract A series of thermally stable and semiconducting polyazomethines containing 1,3,4‐oxadiazole or 1,3,4‐thiadiazole ring in the polymer backbone were synthesized by the simple solution poly‐condensation of dialdehydes with the preformed nuclei with aromatic diamines under mild conditions. To elucidate the struct…
The close structural relationship of porphyrin system and porphycene system is strikingly demonstrated with the [22]porphyrin(2.2.2.2) 1/2: on grounds of strain [22]prophyrin(2.2.2.2) does not exist as the isomer with porphyrin symmetry (D2h) 1, but as stretched porphycene 2.
Abstract Neutralization of orotic acid (OrH 2 ) by lithium or magnesium hydroxide in aqueous medium yields the crystalline metal orotate hydrates Li(OrH). H 2 O ( 1 ) and Mg(OrH) 2 . (H 2 O) 6 ( 2 ). By single‐crystal X‐ray diffraction studies it has been shown that 1 (space group P 1) forms a layer structure, with li…
SUMMARY. The composition and abundance of diatom assemblages were studied together with physiographical and physicochemical variables in twenty‐eight springs in the Central Pyrenees during the period 1987–88. Characteristic groupings of diatom taxa are revealed by Principal Components Analysis. One group, made up of a…
Distinct evidence for the coexistence of a normal ferroelectric-paraelectric phase transition (NPT) at the Curie temperature and a diffuse phase transition (DPT) above the Curie temperature has been discovered in small-grained, nearly fully dense ${\mathrm{Pb}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{La}}_{2\ma…
The interspecific relationships of three euryhaline species of Cyelotella (Bacillariophyta) commonly encountered in large numbers in Choctawhatchee Bay, north-eastern Gulf of Mexico, and their relationships to the other species of the genus, are discussed with particular reference to the origin of euryhalinity in this…
The mutual arrangement of the Delaunay simplices (configurations of four nearest atoms) has been studied for molecular dynamic (MD) models of liquid and quenched rubidium obtained by M. Tanaka [J. Phys. Soc. Jpn. 55, 3108 (1986)]. The Delaunay simplices with large circumradii and low local density of atoms, the simpli…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPreparation and structural characterization of carbonylchlorocopperMikael Haakansson and Susan JagnerCite this: Inorg. Chem. 1990, 29, 26, 5241–5244Publication Date (Print):December 1, 1990Publication History Published online1 May 2002Published inissue 1 December 1990https:/…
Development of the grain‐boundary microstructure with heat treatment at 800° to 1500°C was examined for a group of 96% Al 2 O 3 ceramics containing a high‐MgO boundary phase. Using a combination of analytical and conventional electron microscopy techniques, eight different crystalline phases were detected at the bound…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCluster intermediates in an organometallic synthesis of palladium telluride PdTeJ. G. Brennan, T. Siegrist, S. M. Stuczynski, and M. L. SteigerwaldCite this: J. Am. Chem. Soc. 1990, 112, 25, 9233–9236Publication Date (Print):December 1, 1990Publication History Published onli…
In this article we studied the adsorption of serum albumin to substrata with a broad range of wettabilities from solutions with protein concentrations between 0.03 and 3.00 mg.mL-1 in a parallel-plate flow cell. Wall shear rates were varied between 20 and 2000 s-1. The amount of albumin adsorbed in a stationary state…
Crown ethers have been used for over twenty years as selective binding agents for alkali metal and alkaline earth ions. Although there have been many modifications to the crown ether core, none is so dramatic as to substitute heteroatoms into the positions normally occupied by carbon atoms. In this article we describe…