Materials Literature
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Anomalous low-temperature behaviour of Cu2O is observed by both Raman-spectroscopy using laser excitation frequencies near the resonance of the 1S ‘blue exciton’ and x-ray powder diffractometry using a high-resolution Guinier film camera. Changes in frequency of the Raman-allowed Γ25+(LO) phonon band, and also of inte…
Low concentrations (> or = 1 microM) of the gallium-porphyrin analogue ATX-70 significantly enhanced cellular toxicity in human leukemia HL-525 cells exposed to 50 kHz ultrasound. The mechanism of this ATX-70-dependent sonosensitization is unknown, but we have established the requirement of extracellular localization…
The compounds (C(6)N(2)H(10))CuX(4), where the cation is diprotonated 3-picolylamine and X = Cl(-) or Br(-), form an unusual variant of the normal antiferrodistortive A(2)CuX(4) lattice [(C(6)N(2)H(10))CuCl(4), orthorhombic, Pna2(1), a= 7.747(1), b = 24.960(2), and c = 17.041(1) Å, Z = 12; (C(6)N(2)H(10))CuBr(4), orth…
We compare the dielectric response of ionic glasses and dipolar liquids near the glass transition. Our work is divided into two parts. In the first section we examine ionic glasses and the two prominent approaches to analyzing the dielectric response. The conductivity of ion-conducting glasses displays a power law dis…
A comparative study of the influence of both mobile and randomly quenched impurities and their associated defect complexes on ferroelectric phase transformations in lead zirconate titanate ceramics has been performed by dielectric spectroscopy and transmission electron microscopy. These investigations have shown a str…
New power-inverter technology has made sharp voltage rises increasingly common in today's motor and magnet wire insulation applications. That is why voltage pulse performance is an important property of any high-voltage insulation material.
Abstract Enzymatic ring‐opening polymerization of a 6‐membered cyclic carbonate, 1,3‐dioxan‐2‐one, was investigated by using lipase as catalyst in bulk. Supported lipase derived from Candida antarctica catalyzed the polymerization to give the corresponding aliphatic polycarbonate. Unchanged monomer was recovered in th…
Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation C. Venet, B. Vergnes; Experimental characterization of sharkskin in polyethylenes. J. Rheol. 1 Ju…
The X-ray crystal structure of l-aspartate ammonia-lyase has been determined to 2.8 A resolution. The enzyme contains three domains, and each domain is composed almost completely of alpha helices. The central domain is composed of five long helices. In the tetramer, these five helices form a 20-helix cluster. Such clu…
The structure and crystallization kinetics of poly(ethylene oxide) (PEO) in the homopolymer and in two triblock copolymers of poly(ethylene oxide)−polystyrene−poly(ethylene oxide) (PEO−PS−PEO), crystallized from the ordered melt, have been studied respectively with X-ray diffraction, optical microscopy and differentia…
Recent observations of the disorder−order transition for colloidal hard spheres under microgravity revealed dendritic crystallites roughly 1−2 mm in size for samples in the coexistence region of the phase diagram. Order of magnitude estimates rationalize the absence of large or dendritic crystals under normal gravity…
The iron(II) spin-crossover compound [Fe(ptz)(6)](PF(6))(2) (ptz = 1-propyltetrazole) crystallizes in the triclinic space group P&onemacr;, with a = 10.6439(4) Å, b = 10.8685(4) Å, c = 11.7014(4) Å, alpha = 75.644(1) degrees, beta = 71.671(1) degrees, gamma = 60.815(1) degrees, and Z = 1. In [Fe(ptz)(6)](PF(6))(2), th…
The power loss of MnZn ferrites and its relation to average grain size and grain boundary properties was investigated. The power loss was found to be dependent on the average grain size and on the highly electrically resistive grain boundaries which are formed by introduction of aliovalent ions in the outer grain regi…
Using the technique of fluorescence piezospectroscopy, we determine the distribution of thermal residual stresses across the edges of three laminated alumina/zirconia composites. We develop a methodology for separating the measured stress state into microstresses that result from grain‐to‐grain thermal mismatch and ma…
The disappearance of ferroelectricity in Pb(Zr0.52,Ti0.48)O3 (PZT) thin-film capacitors, which is caused by heat treatment in a reductive ambience, is investigated. Bare PZT films are not damaged by annealing in a hydrogen-containing atmosphere (H2 annealing) up to 400 °C, whereas a PZT capacitor with Pt electrodes lo…
The diffracted orders generated by a plane-wave incident upon a multilayered dielectric grating can undergo strong intensity variations known as Wood’s anomalies or scattering resonances. To clarify these effects, we examine the field and power flux inside the grating region by using a rigorous modal solution of the s…
The reactivity toward dioxygen of two series of dicobalt cofacial diporphyrins in solution in an aprotic solvent is described. Some of these compounds are efficient electrocatalysts for the four-electron reduction of dioxygen when adsorbed on a graphite electrode immersed in aqueous acid. Their electrochemical and spe…
Reaction of beta-functionalized alcohols of type HOCR(2)CH(2)do (1a, do = OMe, R = Me; 1b, do = OMe, R = Et; 1c, do = NMe(2), R = Me) with Ln[N(SiMe(3))(3)](3) yields highly volatile (sublimation < 100 degrees C/10(-)(3) Torr) and n-hexane-soluble homoleptic alkoxide complexes [Ln(OCR(2)CH(2)do)(3)] (2a-d, Ln = Y, Lu)…
Raman spectroscopy between 11 and 680 K was used together with room-temperature x-ray-diffraction experiments for structural studies of ferroelectric Nd-modified lead zirconate titanate ceramics at the morphotropic phase boundary. The Nd addition was found to have a strong effect on the balance between tetragonal and…
We have developed a new route to silicon-centered phthalocyanines and phthalocyanine-like compounds that is robust and flexible, and of considerable potential usefulness. This route entails insertion of silicon into the metal-free macrocycle. It has been developed in the course of preparing four new and two known meta…