Materials Literature
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Classical molecular dynamics simulations are used to examine the indentation of monolayers composed of linear hydrocarbon chains with 8, 13, or 22 carbon atoms that are chemically bound (or anchored) to a diamond (111) substrate. Indentation is accomplished using both a flexible and rigid single-wall, capped [10,10] n…
The spectral dependencies of quantum yields of photostimulated adsorption of oxygen on KBr and ZrO 2 specimens were assessed during photoexcitation into the F centers produced by preirradiation with UV light. The spectral limits of this adsorption were shifted to wavelengths longer than the absorption band edge of the…
A transition structure for the hydride transfer step in dihydrofolate reductase has been characterized in hybrid quantum-mechanical/molecular-mechanical (QM/MM) calculations involving a fully flexible active-site region by means of the GRACE software. The results are compared with in vacuo calculations and the importa…
The amplitudes and the polarizations of the different resonant reflections characterizing the modulation of the orientational order in smectic liquid crystals are derived from the molecular tensorial structure factor. In the case of a commensurate helicoidal modulation, our conclusions are consistent with the previous…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTFirst Synthesis of a Bidesmosidic Triterpene Saponin by a Highly Efficient ProcedureBiao Yu, Jianming Xie, Shaojiang Deng, and Yongzheng HuiView Author Information State Key Laboratory of Bioorganic and Natural Products Chemistry, Shanghai Institute of Organic Chemistr…
Crack growth in a homogeneous elastic solid under impact shear loading conditions is analyzed numerically, with the crack constrained to grow along a weak plane directly ahead of the initial crack tip. The configuration analyzed is a plane-strain model of that used in the experiments of Rosakis et al. (1999). A cohesi…
Organophosphoryl polyoxotungstate derivatives [gamma-SiW(10)O(36)(RPO)(2)](4)(-) (R = H (1), Et (2), n-Bu (3), t-Bu (4), C(2)H(4)COOH (5), Ph (6)) have been obtained by reaction of the divacant [gamma-SiW(10)O(36)](8)(-) anion with organophosphonic acids RPO(OH)(2) in acetonitrile. These new heteropolyanions have been…
Nanoscale domain engineering in ferroelectric crystals is demonstrated down to a lateral domain size of 25 nm in diameter using scanning force microscopy (SFM). The various modes of SFM are used to measure both the internal polarization field and external stray field arising from bound surface charges in ferroelectric…
Variations in the electrical and mechanical properties of silsesquioxane spin‐on‐glass thin films are examined as a function of curing time and temperature. Particular attention is paid to the trade‐off between producing low‐dielectric‐constant films, suitable for advanced microelectronic interconnection structures, a…
Aiming to clarify the mechanism of crystal nucleation of polymers, we have made a quantitative investigation about the conformational change of syndiotactic polystyrene (sPS) during the induction period (ca. 30 min) when crystallized at 120 °C, 25 K above the glass transition temperature T g = 95 °C, from the glassy s…
A simple and effective route to preparing bulk nanocrystalline (NC) pure Mg with an average grain size of 20 nm is first proposed by hydrogenation-disproportionation-desorption-recombination (HDDR) followed by spark plasma sintering (SPS) and hot extrusion (HE) techniques. NC Mg is thermodynamically super-stable again…
Siliceous hollow helicoids (Archimedian screw shapes) with spiraling mesoscale channels are the result of a new way of controlling the growth and form of hexagonal mesoporous silica. These novel helicoids (see Figure) are produced when a patch of the hexagonal silicate liquid-crystal film contracts on hydrolytic polyc…
A novel series of poly(arylidene-ether)s containing cyclopentanone was synthesized by polycondensation of 4, 4′-diformyl-α, ω-diphenoxyalkane and 4, 4′-diformyl-2, 2′-dimethoxy-α, ω-diphenoxyalkane with cyclopentanone. The polymers were characterized by elemental and spectral analyses, inherent viscosity, solubility a…
The structure and magnetostriction of (Tb1−xNdx)(Fe0.4Co0.6)1.9 (0<x<1) alloys have been investigated at room temperature and the magnetic properties determined over the temperature range 1.5–300 K. It was found that the matrix of (Tb1−xNdx)(Fe0.4Co0.6)1.9 is essentially that of a (Tb,Nd) (Fe,Co)2 phase…
In this paper, the crystal growth of sodium nitrate and potassium nitrate from aqueous solutions, in a perfectly stirred batch crystallizer, has been studied considering the effect of temperature, supersaturation degree, and the size of seed crystal growth rate. The mass transfer coefficients obtained correlated with…
Abstract Itoigawaite, SrAl 2 Si 2 O 7 (OH) 2 ·H 2 O, is a new member of the lawsonite group found in the Itoigawa-Ohmi district, central Japan. It is orthorhombic, Cmcm , a = 6.031(2), b = 8.945(2), c = 13.219(4) Å, Z = 4. The strongest lines in the X-ray powder diffraction pattern are 4.68 (s) (111), 4.26 (vs) (021),…
Abstract Intercalation of amino acids into 10.0-Å hydrated kaolinite was studied by powder X-ray diffraction (XRD), differential thermal analysis-thermal gravimetry (DTA-TG), and infrared (IR) spectroscopy. Intercalation was found to be dependent on the chain-length, pH, and the concentration of the amino acid zwitter…
Abstract Thermal dehydrochlorination of trans ‐6(4)‐chloro‐4(5)‐tetradecenes, models for PVC degradation, was studied by NMR spectroscopy both alone and in the presence of alkyl and zinc phosphites. The implications of these results on PVC degradation and stabilization are discussed.
Two chemical treatments were applied to hemp, sisal, jute and kapok natural fibres to create better fibre to resin bonding in natural composite materials. The natural fibres have been treated with varying concentrations of caustic soda with the objective of removing surface impurities and developing fine structure mod…
Abstract Sandstones and mudstones of the Skagerrak Formation from the Danish Sub-basin have been studied to assess the origin of the clay minerals, their diagenesis and their transformation/ conversion temperatures (compared to modelled maximum burial temperatures). Detrital smectite and vermiculite occur only at shal…