Materials Literature
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Abstract The rate theory of RA 2 +RB 3 polymerization has been developed to enable the concentrations of the smallest inelastic loops and the resulting reductions in elastic shear modulus at complete reaction to be evaluated. Reduction in modulus is expressed as M c /M° c , the effective molar mass of chains between e…
The effects of n-type dopant (P, As) concentration in silicon (100), temperature, and oxidizing species on native oxide growth in liquid water are described. The oxide growth on phosphorus (P)- and arsenic (As)-doped n + -Si surfaces (10 20 cm -3 ) in ultrapure water exhibits saturation of oxide thickness, suggesting…
Auger, ESCA, electron emission, evaporation, and desorption measurements were made on three different types of scandate surfaces. They are: (a) an impregnated top layer scandate cathode, (b) an unimpregnated top layer scandate cathode with a deposited barium or barium oxide adsorbate surface layer, and (c) a synthesiz…
Phenolic analogues of 2-[4-(2-piperidinoethoxy)phenyl]-3-phenyl-2H-1-benzopyran (1), a novel antiestrogen, were synthesized and evaluated for their structure-activity relationship. Incorporation of OH at position 7 was found to improve receptor affinity of the benzopyran while having no effect on its action as an anta…
Tetrahedrite and tennantite are extremely common in a variety of ore deposits, but the genetic information they record is difficult to decipher because of the limited understanding of their phase relations in multicomponent systems. Most natural compositions can be described by the general formula (Cu,Ag)1e@e,Zn,Cu)2(…
Abstract Clay mineral abundances in Mesozoic and Tertiary argillaceous strata from 15 exploration wells in the Inner and Outer Moray Firth, Viking Graben and East Shetland Basins of the northern North Sea have been determined in <0·2 µm fractions of cuttings samples. The clay assemblages of more deeply-buried sampl…
Based on a number of in- and out-of-reactor experiments at the Chalk River Nuclear Laboratories, a physically based model has been developed to predict the activity release of radioactive noble gases from defected UO2 fuel elements during steady-state reactor conditions. This model has been interfaced with the ELESIM…
The thermal denaturation of wild-type beta-galactosidase and two beta-galactosidases with substitutions at the active site was studied by kinetics, differential scanning calorimetry, electrophoresis, molecular exclusion chromatography, and circular dichroism. From the results, a model is developed for thermal denatura…
Methanolothermal reaction of Cs 2 CO 3 with SnSe, in the presence of SnSe at 160 C and 13 bar yields the selenostannates(IV) Cs 4 Sn 2 Se 6 and Cs,Sn 3 Se 7 . The structure of the latter phase was established by X-ray structural analysis. The crystal structure contains polyselenostannate(IV) sheet anions [Sn 3 Se 7 2-…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA planar oxocuprate(II) array via heterometallic alkoxide chemistryJohn A. Samuels, Brian A. Vaartstra, John C. Huffman, Kathleen L. Trojan, William E. Hatfield, and Kenneth G. CaultonCite this: J. Am. Chem. Soc. 1990, 112, 26, 9623–9624Publication Date (Print):December 1, 1…
Abstract The oxidation behaviour of SiC monocrystalline and polycrystalline samples differing by their structure and the impurity content, was studied in O 2 , in air and in O 2 + H 2 O atmospheres, between 1050 and 1400°C. Classical techniques for determining the oxidation kinetics and for analyzing the morphology, t…
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…