Materials Literature
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Quantum mechanical techniques based on density functional theory have been used to investigate the mechanism and energetics of proton transport in the perovskite-structured CaZrO 3 . The calculations demonstrate that the observed orthorhombic crystal structure (comprised of tilting [ZrO 6 ] octahedra) is reproduced ac…
The four A1-TO Gamma phonon frequencies in lithium tantalate are calculated in the frozen-phonon approach from first principles using the full-potential linearized augmented plane wave method. A good agreement with the experimental data available is found for all modes; reliable displacement pattern of different modes…
We measure electron localization in different materials by means of a ``localization tensor'', based on Berry phases and related quantities. We analyze its properties, and we actually compute such tensor from first principles for several tetrahedrally coordinated semiconductors. We discuss the trends in our calculated…
Selective replacement of the amorphous peptide domain of a spider silk with poly(ethylene glycol) gave N. clavipes silk-inspired polymers having similar solid-state structures and very good mechanical properties. The tendency of poly(alanine) having appropriate chain length to form beta-sheets and the facility with wh…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDesign and Characterization of Crystalline Thin Film Architectures at the Air−Liquid Interface: Simplicity to ComplexityIvan Kuzmenko, Hanna Rapaport, Kristian Kjaer, Jens Als-Nielsen, Isabelle Weissbuch, Meir Lahav, and Leslie LeiserowitzView Author Information Department o…
Porous CdS and SnS films with ordered nanohole array structures were produced from anodic porous alumina by a two-step replication process. The nanohole array structure was formed by electrodeposition of CdS or SnS onto a prepared negative structure of the porous alumina template. The porous metal sulfide films with u…
Magnetization and electrical resistivity measurements have been made on ${\mathrm{Fe}}_{2\ensuremath{-}x}{\mathrm{Ni}}_{x}\mathrm{TiSn}$ and ${\mathrm{Fe}}_{2\ensuremath{-}x}{\mathrm{Co}}_{x}\mathrm{TiSn}$ cubic solid solutions. The electrical resistivity reveals a strong influence of spin fluctuations for ${\mathrm{F…
The mode of microscopic deformation in rubber-modified amorphous polymers has been investigated by small-angle X-ray scattering during tensile deformation. Synchrotron experiments were performed for blends consisting of poly(methyl methacrylate) (PMMA) with a finely dispersed rubbery epoxy phase. These blends were pre…
The structures of sodium (+)-tartrato arsenate(III),[Na8As10(C4H2O6)8(C4H3O6)2(H2O)19]n(1), silver (+)-tartrato arsenate(III),[Ag9As10(C4H2O6)9(C4H3O6)(H4As2O5)(H2O)10](2) and rubidium citrato antimonate(III)[Rb2Sb4(C6H6O7)6(C6H7O7)2(H2O)2](3) have been determined by X-ray methods and refined to residuals of 0.085(1),…
The structural, thermal, and nonlinear optic (NLO) characterization of different polar materials is reported. These materials, which range from side-chain polymers to anisotropic networks and gels, were prepared by in situ photopolymerization of their precursors in the ferroelectric SmC* liquid crystal phase. The infl…
Computer modeling techniques provide a useful mechanism with which to model the morphology of defect crystals. In this work, a study of the incorporation of sodium and potassium cations into the morphologically important surfaces of gibbsite was conducted. Computation of the resulting changes in surfaces energies was…
The speciation and equilibria of sodium metatungstate, Na6[H2W12O40], has been determined by a combination of 183W n.m.r. spectroscopy and gravimetry over the p[H] range 4.5–10.0. The use of n.m.r. spectroscopy allowed the direct observation of polytungstate anions in aqueous solution and high concentration (0.25 mol…
We report the temperature-dependent infrared spectra of pure, deuterated, Zn-doped, and 2,6-dimethyl-substituted samples of the S = 1 / 2, one-dimensional Quantum Heisenberg Antiferromagnet (QHAF) copper pyrazine dinitrate (Cu(C 4 H 4 N 2 )(NO 3 ) 2 ). Of the more than 100 vibrational modes observed in the spectra, ne…
Poly(epsilon-caprolactone), PCL, is a commercial biodegradable and biocompatible polyester that can be bioassimilated by outdoor microorganisms. For biomedical and environmental applications, monitoring the fate of degradation products in vivo or under environmental conditions is one of the critical steps to evaluate…
Compositional variation of magnetoresistance (MR) ratio with silver excess stoichiometry in ${\mathrm{Ag}}_{2+\ensuremath{\delta}}\mathrm{Se}$ samples has been studied employing a synthetic approach to prepare instantly a series of bulk silver selenide compounds using microwave energy. Bulk density >99% is achieved…
We have previously reported the use of titanium alkoxide complexes as initiators for the living polymerization of isocyanates. In this paper, we present the synthesis of a trimetallic initiator, 2, comprised of three titanium alkoxides connected to a central organic core and the use of this catalyst to form three-arm…
Toughness enhancement of brittle amorphous polymers can be obtained via microstructural adjustments, resulting effectively in a removal of intrinsic strain softening on the mesoscale via a decrease in yield stress and an increase in strain hardening. Generally the introduction of a dispersed soft phase is required wit…
Oligomeric peptides can be designed which undergo one-dimensional self-assembly in solution to form beta-sheet tapes a single molecule in thickness and micrometers in length.(1) In this paper, we present the first systematic investigation of the size, shape, dynamics, and interactions of beta-sheet tapes formed by a s…
In this paper, we report differential scanning calorimetry studies of the temperature and molar mass dependences for the primary and secondary crystallization behavior of bisphenol A polycarbonate (BAPC). The molar mass dependence of the crystallization rate is found to be much stronger during primary than during seco…
We have investigated electrochemical switching of excited-state electronic energy migration in two optoelectronic gates with different architectures. Each gate consists of diarylethyne-linked subunits: a boron-dipyrrin (BDPY) input unit, a Zn-porphyrin transmission unit, a free-base-porphyrin (Fb-porphyrin) output uni…