Materials Literature
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Abstract A 29 Si MAS-NMR one-pulse and ﹛ 1 H﹜ CP comparative study of sepiolite, folded sepiolite, aluminated sepiolite, and palygorskite was conducted. The three main resonances of sepiolite at -92.0 ± 0.1, —94.3 + 0.1, and — 97.8 ± 0.1 p.p.m. were assigned with respect to the position of the Si atoms within the thre…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDinuclear Gold(II) Complexes Containing Two Different Bridging Ligands. Crystal Structure of [Au2{.mu.-(CH2)2PPh2}{.mu.-S2CN(CH2Ph)2}Br2]Manuel Bardaji, M. Concepcion Gimeno, Peter G. Jones, Antonio Laguna, and Mariano LagunaCite this: Organometallics 1994, 13, 9, 3415–3419P…
Barium titanate (BaTiO 3 ) ceramics with high degrees of a‐ and c ‐axis orientation were fabricated by combining hydrothermal synthesis of fibrous particles, formation of green compacts with aligned extruded rods in the mold, and normal sintering. The orientation of crystal axes in such ceramics gives rise to high die…
Image analysis presents a quick, reliable, unbiased technique for determining cotton fiber maturity. This research entails developing sampling techniques for cotton fiber cross sections and creating a computer program to measure fiber characteristics directly by image analysis. A 10 minute (approximate) fiber/ resin e…
Vesuvianite can contain significant amounts of boron (up to-4 wtTo B2O). The crystal stnrctures of five boron-bearing vesuvianite crystals have been refined using MoKo X-ray data. Although the crystals are significantly biaxiat (2y < 20o), very careful examination of the diffraction data shows no deviation from…
In this Brief Report we use a self-consistent mean-field (SCF) method to predict the surface excess (${\mathit{z}}^{\mathrm{*}}$) and surface volume fraction (${\mathrm{\ensuremath{\varphi}}}_{1}$) of the surface active component in a binary polymer blend. The SCF results are in excellent agreement with the measured $…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructure of the Complex Metal Hydride BaReH9N. T. Stetson, K. Yvon, and P. FischerCite this: Inorg. Chem. 1994, 33, 20, 4598–4599Publication Date (Print):September 1, 1994Publication History Published online1 May 2002Published inissue 1 September 1994https://pubs.acs.org/do…
We report results on the response of a family of displacement sensors, which are based on the magnetostrictive delay line (MDL) technique, using current conductors orthogonal to the MDL. Such sensing technique is based on the change of the magnetic circuit at the acoustic stress point of origin due to the displacement…
The first part of this paper discusses the molecular design of selected examples of structural units containing taper shaped exo-receptors and various crown ether, oligooxyethylenic, and H-bonding based endo-receptors, which self-assemble into cylindrical channel-like architectures via principles resembling those of t…
Nanosize oxides and mixed oxides were produced in a rectangular counterflow diffusion flame burner. Their formation and growth mechanisms in the burner are reviewed. This paper correlates flame temperature, residence time and precursor concentration to the particle size, morphology and crystalline structure of these n…
The room-temperature photoluminescence spectrum of SiO2 glass: 0.1% Cr prepared by sol–gel method is reported. It consists of a broad band centered at 14 900 cm−1 with a width of 4200 cm−1 and a lifetime in the μs order and is attributed to the d–d transition of Cr5+ ions (3d1 electron configuration). Absorption and e…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and Properties of Stereoregular Polyamides Derived from L-Tartaric Acid: Poly[(2S,3S)-2,3-Dimethoxybutylene alkanamide]sJ. J. Bou, I. Iribarren, and S. Munoz-GuerraCite this: Macromolecules 1994, 27, 19, 5263–5270Publication Date (Print):September 1, 1994Publicatio…
A polyphase titanate ceramic incorporating sodium‐free simulated high‐level nuclear waste was doped with 0.91 wt% of 244 Cm to accelerate the effects of long‐term self‐irradiation arising from α decays. The ceramic included three main constituent minerals: hollandite, perovskite, and zirconolite, with some minor phase…
A quantitative theoretical model that describes the amount of evanescent field that is absorbed by an infinite cladding has been developed. The validity of this model has been confirmed by a series of experiments to determine the typical dependence of the abosrption on each parameter (fiber length, fiber diameter, lig…
Abstract Vaterite, a CaCO 3 polymorph, is a rare mineral that is said to be metastable under all known conditions. According to the literature, vaterite precipitated from carbonate solution recrystallizes spontaneously to calcite or aragonite. Yet vaterite has been identified in hard tissues of organisms, in gallstone…
Four well‐defined monodisperse oligo( p ‐phenylenevinylene)s (see Figure, n = 3 to 6) have been used in solid‐state voltammetric investigations as model compounds for the related polymer. The redox behavior in solution and in the solid state is compared and an interpretation of the controversial “current plateau” prop…
Abstract 1 H NMR and 13 C NMR have been used to study the end groups and tacticity in PMMA macromonomers and oligomers. These macromonomers are terminated almost exclusively in one vinylidene group per chain. The end group signals from the macromonomers are identified in both the 13 C and 1 H NMR spectra. The spectra…
In this paper we introduce a method to study surface torsional anchoring of both chiral-molecule-doped and pure nematic liquid crystal (NLC) without using any extra field. By measuring the transmission of the twisted or supertwisted NLC cells, the actual twist angles in NLC cells are obtained, which differ from the an…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTLack of Superaromaticity in Carbon NanotubesJ. AiharaCite this: J. Phys. Chem. 1994, 98, 39, 9773–9776Publication Date (Print):September 1, 1994Publication History Published online1 May 2002Published inissue 1 September 1994https://pubs.acs.org/doi/10.1021/j100090a009https:/…
The in situ β‐Si 3 N 4 /α′‐SiAlON composite was studied along the Si 3 N 4 –Y 2 O 3 : 9 AlN composition line. This two phase composite was fully densified at 1780°C by hot pressing Densification curves and phase developments of the β‐Si 3 N 4 /α′‐SiAlON composite were found to vary with composition. Because of the coo…