Materials Literature
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Abstract Clay minerals in shales from cores at Site 808, Nankai Trough, have been studied using X-ray diffraction (XRD), scanning transmission electron microscopy (STEM), and analytical electron microscopy (AEM) to compare the rates and mechanisms of illitization with those of coeval bentonites, which were described p…
The structures of M 2 O 3 –TeO 2 (M = Al and Ga) glasses have been investigated by means of 125 Te, 27 Al, and 71 Ga NMR spectroscopies. The structural units of respective cations in M 2 O 3 –TeO 2 glasses were quantitatively analyzed. The fractions of TeO 4 trigonal bipyramid, AlO 6 and GaO 6 octahedra decreased and…
The synthesis of lanthanide(III) alkoxides has been described as a series of reactions for which the control of product purity is difficult. The possibility of using amide complexes, in the presence of alcohol, to produce alkoxides was investigated in homogeneous and heterogeneous media. The polymerization of ε-caprol…
Recent crystallographic evidence of nonplanarity of several prosthetic groups in heme proteins has prompted the design of conformationally distorted synthetic porphyrins in order to assess the consequences of the nonplanarity observed in vivo. The crystal structure of the sterically crowded Fe(III) 2,3,7,8,12,13,17,18…
X-ray crystal structures of three forms of human mitochondrial branched-chain aminotransferase (BCAT) were solved by molecular-replacement methods, using Escherichia coli BCAT as the search model. The enzyme is a homodimer and the polypeptide chain of each monomer has two domains. The small domain is composed of resid…
Space charge dynamics in low-density polyethylene (LDPE) films were observed by the pulsed electroacoustic (PEA) method during breakdown tests at various temperatures. In order to investigate the intrinsic electrical breakdown, the applied electric field was increased to 300 kV/mm in 150 ms, and kept constant until br…
Motivated in part by recent experiments on liquid crystals with bent-core molecules, which are observed to display a spontaneous chiral symmetry breaking, we introduce a field theory of a 3rd-rank tensor order parameter T^{ijk} to describe the isotropic-to-tetrahedratic phase transition that we predict to take place i…
The pore sizes of hydrogen-methyl-siloxane-based porous spin-on-glass (SOG) thin films having different k values ( k =1.8–2.5) are comparatively studied using different nondestructive instrumental ways and also with reference to sorption porosimetry. The pore size and its spread are found to increase with increasing p…
Abstract Tetraaryl-substituted cerium(IV) double-decker porphyrin (2D), tetraaryl-substituted lanthanum(III) double-decker porphyrin (3D), and diaryl-substituted lanthanum(III) triple-decker porphyrins (4T•Me and 4T•MeO) were newly synthesized and their porphyrin ring rotation rates were systematically estimated by me…
The solvent behaviour of flash-cooled protein crystals was studied in the range 100--180 K by X-ray diffraction. If the solvent is within large channels it crystallizes at 155 K, as identified by a sharp change in the increase of unit-cell volume upon temperature increase. In contrast, if a similar amount of solvent i…
Thick films of poly(benzylsilsesquioxane) (BnSiO 3/2 ) particles, prepared by the sol–gel process, were deposited onto indium‐tin‐oxide‐coated glass substrates by electrophoresis for the application to the micropatterning of the films. BnSiO 3/2 particles were thermally softened and sintered at ∼50°C, which was above…
High sp3 fraction tetrahedral amorphous carbon (ta-C) films can be prepared using the filtered cathodic vacuum arc (FCVA). A by-product of the deposition process are small micrometer sized graphitic particles which are also incorporated into the film. The particle coverage of FCVA films is typically <5%, and th…
A detailed analysis is given of the conditions for the generation of misfit-induced defects (misfit wedge disclinations and disclination dipoles, periodical arrays of misfit wedge disclinations, and misfit-dislocation walls (MDWs)) in a two-phase cylindrical composite misfitting system. It is shown that the nucleation…
The spectroscopic properties of P2O5–Y2O3–Er2O3 and P2O5–Li2O–Al2O3–Y2O3–Er2O3 ultraphosphate glasses have been investigated. The concentration quenching rates of Er3+ in these two systems are lower compared with those in other oxide glasses. The spectral broadening of the measured fluorescence of 83.33P2O5–(16.67−x)E…
The factors influencing the cationization of microcrystalline cellulose with 3-chloro-2-hydroxypropyl triethylammonium chloride in the presence of NaOH were investigated. The course of the reaction was followed by estimating the nitrogen content of the cationized product while its structural features were confirmed by…
In this paper the synthesis and characterization of CdTe nanocrystals are presented. Opposite to what has been observed with Cd1–yMnyS, it has been impossible to include manganese ions in CdTe matrices. Only large rods of telluride were seen. ZnTe could also not be formed and again only Te rods were perceived. This cl…
The Rietveld method has proved to be a very effective means to characterize and quantify the crystalline phases and the amorphous phase in glass ceramic materials using X-ray powder diffraction data. The technique was applied to a borosilicate glass of the type used for high-level nuclear-waste containment, in order t…
Microbial biomineralization in a weathered volcanic ash deposit from the 1914 to 1915 A.D. eruption of Sakurajima volcano was investigated by transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX). The solution chemistry of pore water was also analyzed to elucidate saturation conditions. In…
Tributyltin derivatives of 2-bromo-3-octylthiophene and 5-bromo-4-octyl-2,2′-bi(thiophene) have been selectively prepared. Condensation reactions in the presence of Pd2(dba)3(CHCl3)/4 PPh3 led to high yields (ca. 90%) of regioregular poly(3-octylthiophene) (Mw = 21.4 × 104, Mw/Mn = 1.48) and poly[4-octylbi(thiophene)]…
PII is a signal transduction protein that is part of the cellular machinery used by many bacteria to regulate the activity of glutamine synthetase and the transcription of its gene. The structure of PII was solved using a hexagonal crystal form (form I). The more physiologically relevant form of PII is a complex with…