Materials Literature
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Versatile molecular precursors for the sol–gel synthesis of tungsten oxide thin films can be obtained via the reaction of tungsten oxychloride WOCl4 with alcohols. Oligomeric species [WOCl4 –x(OR)x]n are formed. Their molecular structure is analysed by infrared spectroscopy, nuclear magnetic resonance (NMR) spectrosco…
Electrophillic bromination occurs regiospecifically at the antipodal pyrrolenic ring of free-base porphyrins bearing substituents that fix the aromatic delocalization pathway; this new feature of porphyrin chemistry is not observed in the reactions of the corresponding metalloporphyrins as the pre-requisite bond fixat…
The levels of urease and asparaginase were elevated 25- and 20-fold, respectively, in extracts of Bacillus subtilis cells grown in medium containing nitrogen sources that are poor sources of ammonium (NH4+) compared with the levels seen in extracts of cells grown in medium containing nitrogen sources that are good sou…
An anatase precursor of V2O5/TiO2 catalysts contains nitrate and sulphate impurities, the former being destroyed by calcination at 673 K but surface sulphate remaining after calcination at 723 K. Two types of Lewisacidic site were distinguished by ammonia and pyridine adsorption. Slight surface Brønsted acidity was co…
An industrially feasible process for the polymerization of pyrrole or aniline on the surface of textile fibers and assemblies is discussed. Physical properties of the resulting fabrics are described as well as their stability under various condi tions. Fabrics coated with polypyrrole maintained the general physical pr…
Shape memory alloys have successfully entered the repertoire of serving themselves as different types of prostheses owing to their unique characteristics including the shape memory effect, superelasticity as well as high damping capacity since they were introduced in medical and dental fields more than 10 years ago. F…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFormation of reversed vesiclesHironobu Kunieda, Kazuyoshi Nakamura, and D. Fennell EvansCite this: J. Am. Chem. Soc. 1991, 113, 3, 1051–1052Publication Date (Print):January 1, 1991Publication History Published online1 May 2002Published inissue 1 January 1991https://pubs.acs.…
The field dependence of the dielectric response has been measured for lead magnesium niobate relaxors. The frequency dispersion of the temperature of the permittivity maximum, Tmax, was analyzed using the Vogel–Fulcher relationship. The field dependence of the permittivity at various temperatures was also modeled usin…
All articles of this category Addition of donor ligands such as pyridine N -oxide or 2-methylimidazole to the chiral (salen)manganese(III) complex catalyzed asymmetric epoxidation of unfunctionalized olefins was found to be effective for altering the enantioselectivity and the chemical yield. The highest asymmetric yi…
Solutions of Keggin-structure polyoxometalates have been studied by IR, Raman and UV spectroscopies, with various solvents and counterions. For the tetraalkylammonium compounds, cation–anion aggregates are observed. This model of cation–anion aggregates can be applied to the solutions of the acids in DMF and DMSO. The…
An Al70Ni15Co15 alloy, known to form a stable decagonal quasicrystal, was subjected to various heat treatments and studied with electron diffraction and high-resolution electron microscopy. The alloy quenched from 800°C forms a decagonal quasicrystal, which shows diffraction patterns with a large number of sharp spots…
The results of a study on the suppression of leakage current on room temperature vulcanizing (RTV) silicone rubber coated porcelain suspension insulators in a salt-fog chamber are reported. A comparative study of the performance of coatings on different parts of suspension insulators with RTV is reported. The results…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectrochemistry and electrochromic behavior of Langmuir-Blodgett films of octakis-substituted rare-earth metal diphthalocyaninesYunqi Liu, Kiyotaka Shigehara, Masahiko Hara, and Akira YamadaCite this: J. Am. Chem. Soc. 1991, 113, 2, 440–443Publication Date (Print):January 1…
Abstract Natural (untreated) clays are most probably amorphous on their outermost surface layers due to the continuous and natural process of partial dissolution and reprecipitation of the clay components at the solid‐aqueous interface. The pH‐dependent adsorption on Al and Si oxides, mordenite, kaolinite, and montmor…
Aggregate size and abundance were monitored in situ at a fixed station in the southern North Sea d u r ~n g a 6 wk investigation which covered the phytoplankton spring bloom and the pre-and post-bloom periods. Particle aggregates were abundant dunng the entire period of study. Biologically derived material, such a s a…
New layered perovskite compounds ${\mathrm{Sr}}_{\mathit{n}+1}$${\mathrm{V}}_{\mathit{n}}$${\mathrm{O}}_{3\mathit{n}+1}$ (n=1, 2, and 3) and ${\mathrm{SrVO}}_{3}$ (n=\ensuremath{\infty}) were synthesized, and the physical properties of the compounds with n=1, 2, and \ensuremath{\infty} were investigated. ${\mathrm{Sr}…
The synthesis of unsymmetrically or non-uniformly surface-functionalized dendritic macromolecules using a stepwise convergent-growth approach is described. By stepwise alkylation of the monomer unit, 3,5-dihydroxybenzyl alcohol, with unsubstituted and substituted benzylic bromides, followed by activation of the group…
The structure of Zn[C(CN)3]2 consists of two independent infinite rutile-related frameworks whose compiex entanglement resembles 3D knitting.
The crystallization of CaCO3 under compressed Langmuir monolayers of stearic acid [CH3(CH2)16CO2H], octadecylamine [CH3(CH2)17NH2], octadecanol [CH3(CH2)17OH] and cholesterol (C27H45OH) has been studied over a range of supersaturation conditions by optical and scanning electron microscopy and X-ray diffraction. At tot…
Molecular methods have been applied to analyze the expression of the Alcaligenes eutrophus poly(3-hydroxybutyrate) (PHB) synthase gene (phbC). The translational initiation codon was identified by analysis of the amino acid sequence of a PHB synthase-beta-galactosidase fusion protein. This protein was purified to almos…