Materials Literature
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A new approach to the problem of the kinetic exchange for orbitally degenerate ions is developed. The constituent multielectron metal ions are assumed to be octahedrally coordinated, and strong crystal field scheme is employed, making it possible to take full advantage from the symmetry properties of the fermionic ope…
Extended x-ray absorption fine structure at the manganese $K$ edge has been used to study the first oxygen coordination shell at the manganese site as a function of temperature in mixed-valence perovskites. ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ ($x=0,$ 0.15, 0.33, 0.5, 0.66, and 1), ${\…
The kinetics of the lamellar→hexagonal→cubic transformations of mesoporous zirconia prepared by using a neutral organic amine as the amphiphile have been studied in phosphoric acid medium. The lamellar→hexagonal transformation is preceded by a loss of the template molecules and the hexagonal→cubic transformation proce…
The local electric fields on a semicontinuous metal film are shown to experience giant fluctuations in the visible and infrared spectral ranges when the dissipation in metallic grains is small. The field fluctuations result in strongly enhanced Raman scattering. The scattered local fields at the Stokes frequency are c…
Fracture of a large‐grained alumina polycrystal has been examined in situ by optical microscopy. Concurrently, local bridging stresses, as generated by friction or tension of unbroken ligaments in the wake of the crack path, were measured by piezospectroscopy. Stress measurements were performed both at fixed sites as…
A. J. Moore, M. R. Bryce, A. S. Batsanov, A. Green, J. A. K. Howard, A. Mckervey, P. Mcguigan, I. Ledoux, E. Ortí, R. Viruela, P. M. Viruela and B. Tarbit, J. Mater. Chem., 1998, 8, 1173 DOI: 10.1039/A708078F
Article Selective Transition-Metal Catalysis of Oxygen Delignification. Using Water-Soluble Salts of Polyoxometalate (POM) Anions. Part II. Reactions of α-[SiVW11O40]5- with Phenolic Lignin-Model Compounds was published on January 1, 1998 in the journal Holzforschung (volume 52, issue 3).
Enzymatic ring-opening polymerization of a 17-membered lactone, 16-hexadecanolide (HDL), was performed in bulk by using lipases of different origin as catalyst. Pseudomonas fluorescens lipase exhibited high catalytic activity toward the polymerization, producing the corresponding polymer in high yields. A higher polym…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTTwo-Dimensional Microphase Separation of a Block Copolymer in a Langmuir−Blodgett FilmJiro Kumaki and Takeji HashimotoView Author Information Hashimoto Polymer Phasing Project, ERATO, JST Keihanna Plaza, Seika, Kyoto 619-02, Japan Department of Polymer Chemistry Gradua…
Homogeneous IPN polymer hybrids of polystyrene gel and silica gel were prepared by applying an in-situ polymerization method to styrene monomer and divinylbenzene. The monomers were mixed in the sol–gel reaction mixture of tetramethoxysilane and subjected to radical polymerization, resulting in transparent glassy mate…
SummaryAn investigation has been undertaken to attempt to electrodeposit layered coatings of zinc, nickel and zinc-nickel alloy. A dual electrolyte approach has been applied with sequential layers being electrodeposited from the two baths. Coated steel substrates have been sectioned and examined using scanning electro…
An improved procedure for the preparation of the saddle-distorted porphyrin 2,3,5,7,8,10,12,13,15,17,18,20-dodecaphenylporphyrin (H2dpp) (yield = 75%) based on the Suzuki cross-coupling reaction between phenylboronic acid PhB(OH)2 and [2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraphenylporphyrin] has been developed.…
Hybrid organic-inorganic silica-based materials containing a labile bridging organic unit have been prepared. The elimination of the organic fragment is possible under very mild conditions at room temperature in the presence of a small amount (2%) of fluoride ion as catalyst. The silicas obtained after chemical treatm…
We show, for the first time to our knowledge, that highly nonlinear optically active as well as orientationally optimized crystalline materials for second-order nonlinear optics can be prepared by a proper design of short hydrogen-bonded molecular aggregates derived from a specially developed merocyanine dye. One of t…
This paper describes the study of the reliability of capacitor units installed and operated in a distribution system during the period 1980 through 1990. Failures of capacitor units in distribution substations can be very costly to the supply of reliable power to consumers. To enhance utility reliability, failure anal…
The compound Li 4 GeS 4 has been prepared as transparent, light yellow moisture-sensitive crystals. Li 4 GeS 4 belongs to the space group Pnma with a = 14.107(6) Å, b = 7.770(3) Å and c = 6.162(2) Å. The crystal structure was solved by direct-methods. The final R and R w -values are 1.85 and 1.65% for 866 observed ref…
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In most types of high voltage apparatus, a PD acceptance test is required. In contrast, the PD test is very rarely used as an acceptance test for new motor and generator windings. The closest that machine manufacturers come to a PD acceptance test is the power factor tip-up test (IEEE Standard 286), which is an indire…
A brief review is given of ferroelectric thin-film memory technology, emphasizing up-to-date comparisons among different materials, including lead zirconate-titanate (PZT), barium-strontium titanate (BST), and strontium bismuth tantalate (SBT) for both DRAMS and non-volatile RAMS.
A dioxoruthenium(VI) complex containing a D4-porphyrinato ligand por* {H2por* = 5,10,15,20-tetrakis[(1S,4R,5R,8S)-1,2,3,4,5,6,7,8-octahydro-1,4∶5,8-dimethanoanthracen-9-yl]porphyrin} has been prepared by oxidation of its ruthenium(II) carbonyl precursor with m-chloroperoxybenzoic acid and characterised by spectroscopi…