Materials Literature
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The dark electrical conductivity, Hall coefficient, space charge limited current, and illumination and temperature dependences of the photocurrent of TlGaS 2 single crystals in the temperature regions of 100–350, 200–350, 200–290 and 100–350 K, respectively, have been measured and analysed. The Hall coefficient measur…
Decomposition of sputtered PtOx layers has been studied by x-ray absorption spectroscopy. X-ray absorption fine structure measurements demonstrated that as-deposited films possess a composition of PtOx (x=1.1–1.7). Upon annealing, the metallic platinum phase is formed. The formation of the metallic Pt phase starts at…
In this Letter we present direct observation of the Fe helimagnetism in an Y2Fe17 single crystal under pressure. Combined neutron diffraction and magnetization measurements under pressure showed that the collinear ferromagnetic phase of Y2Fe17 is substituted by the pressure induced helical incommensurate phases. The c…
We report on the formation of switchable holographic transmission gratings in polymer-dispersed liquid-crystal cells by use of the 633-nm wavelength of a He-Ne laser. We present results for the structure, diffraction efficiency, and switching characteristics of the gratings.
Abstract The ring‐opening polymerization of trimethylene carbonate (TMC) using homoleptic lanthanide guanidinate complexes [RNC(NR′ 2 )NR] 3 Ln as single component initiators has been fully investigated for the first time. The substituents on guanidinate ligands and center metals show great effect on the catalytic act…
Abstract The toughening mechanisms of polypropylene filled with elastomer and calcium carbonate (CaCO 3 ) particles were studied. Polypropylene/elastomer/CaCO 3 composites were prepared on a twin‐screw extruder with a particle concentration of 0–32 vol %. The experiments included tensile tests, notched Izod impact tes…
We present a solid state electrochromic device based on poly (phenylene vinylene) light-emitting polymers and explore device performance as a function of salt type, salt concentration, and polymer layer thickness. Salts employing organic anions display improved optical contrasts. Higher salt concentrations and thicker…
This article reviews different types of membranes for guided tissue regeneration.They are used to cover defects and stimulate regeneration of osseous defects in periodontal pockets.A membrane should be biocompatible, enable cell exclusion separating the gingival flap from the fibrine clot and guard space for the new a…
The primary relaxation time scale tau(T) derived from the glass forming supercooled liquids (SCLs) is discussed within ergodic-cluster Gaussian statistics, theoretically justified near and above the glass-transformation temperature T(g). An analysis is given for the temperature-derivative data by Stickel et al. on the…
Electron-phonon coupling in oligo(para-phenylene)s is addressed in terms of the off-resonance Raman intensities of two distinct modes at 1220 and 1280 cm(-1). On the basis of Albrecht's theory, vibrational coupling and Raman intensities are calculated from first-principles quantum-chemical methods. A few-state model i…
The backscattering of medium energy electrons from solid surfaces is investigated by analysis of a linearized Boltzmann-type kinetic equation. A closed expression is derived for the Green's function in an infinite medium valid for a spherically symmetric potential describing the interaction with the ionic subsystem. T…
We report the synthesis and photophysical investigation of a series of rotaxanes in which the physical confinement of the donor and acceptor (DA) pair leads, in some cases, to emissive exciplexes. As a comparison, we examined the photoinduced charge-transfer processes in the same DA mixtures under intermolecular condi…
An ultrathin nanoscopic multilayer film has been fabricated through the electrostatic layer-by-layer self-assembly of negatively charged 5,10,15,20-tetrakis(3,4,5-trihydroxyphenyl)porphyrin (DHP) and oppositely charged polyethylenimine (PEI). UV-vis spectra showed a continuous and uniform deposition process of PEI and…
We report studies of the frequency-dependent shear modulus, ${G}^{*}(\ensuremath{\omega})={G}^{\ensuremath{'}}(\ensuremath{\omega})+i{G}^{\ensuremath{'}\ensuremath{'}}(\ensuremath{\omega})$, of the liquid crystal octylcyanobiphenyl (8CB) confined in a colloidal aerosil gel. With the onset of smectic order, ${G}^{\ensu…
The electronic structure of the recently isolated silver copper oxide Ag(2)Cu(2)O(4) is analyzed along with its precursor Ag(2)Cu(2)O(3) and similar binary oxides, Ag(2)O, AgO, CuO, and NaCuO(2), using X-ray photoemission (XPS) and X-ray absorption (XAS) measurements. The results for Ag(2)Cu(2)O(4) reveal an electroni…
Recent controversy about the space group of the low temperature superlattice phase of $\mathrm{Pb}({\mathrm{Zr}}_{0.52}{\mathrm{Ti}}_{0.48}){\mathrm{O}}_{3}$ is settled. It is shown that the $R3c$ space group for the superlattice phase cannot correctly account for the peak positions of the superlattice reflections pre…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTNonhydrolytic Layer-by-Layer Surface Sol−Gel Modification of Powdered Mesoporous Silica Materials with TiO2Wenfu Yan, Shannon M. Mahurin, Steven H. Overbury, and Sheng DaiView Author Information Chemical Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008,…
Trehalose-glycerol mixtures are known to be effective in the long time preservation of proteins. However, the microscopic mechanism of their effective preservation abilities remains unclear. In this article we present a molecular dynamics simulation study of the short time, less than 1 ns, dynamics of four trehalose-g…
Abstract The synthesis of novel arborescent ( arb ; randomly branched, “tree‐like,” and often called “hyperbranched”) block copolymers comprised of rubbery polyisobutylene (PIB) and glassy polystyrene (PSt) blocks ( arb ‐PIB‐ b ‐PSt) is described. The syntheses were accomplished by the use of arb ‐PIB macroinitiators…
The next step forward, transforming polymer nanocomposites from filled-polymer replacements to designed and engineered materials, necessitates the development of techniques to transform the random or ill-defined nanoscale morphologies into compositionally and spatially engineered hierarchal structures, paralleling tha…