Materials Literature
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We have used surface extended x-ray absorption fine structure (SEXAFS) to study the local geometry around barium atoms on thermionic cathodes. On the surfaces of tungsten and tungsten-osmium alloy dispenser cathodes Ba is bonded to oxygen with a well-defined short-range order. The Ba-O distance is similar (2.62\ifmmod…
We determined the crossover frequency ${\mathrm{\ensuremath{\omega}}}_{\mathrm{co}}$ between phonon and fracton regimes from the study of the low-frequency inelastic light scattering in superionic borate glasses of the type (AgI${)}_{\mathit{x}}$(${\mathrm{Ag}}_{2}$O\ensuremath{\cdot}${\mathrm{B}}_{2}$${\mathrm{O}}_{3…
Abstract In our recent overview of liquid crystalline polyesters of trans ‐4,4′‐stilbenedicarboxylic acid (SDA) and aliphatic glycols, 1 we reported that “… the 1,3‐propanediol polyester did not exhibit thermotropic liquid crystallinity (no stir opalescence or DSC endotherm above T m ), perhaps because of the relative…
In previous work, the authors have shown that electrical aging of polyethylene under ac voltage was due to the build-up of a space charge which was accompanied by light emission. Study of the electroluminescence allowed us to estimate the quantity of charges trapped in the material when ac voltage was applied to the p…
Semielliptical surface flaws of different sizes were introduced into Al 2 O 3 by Knoop microhardness indentation. The specimens were fractured by four‐point bending and the profiles of the indentation flaws were determined by observing the fracture surfaces with a scanning electron microscope. The relation between the…
Analytical studies of the collapse of (1) hemispherical, point initiated, (2) hemispherical, surface initiated and (3) conical, point initiated warheads, using the HELP and EPIC hydrocodes predicted tubular or layered jets. Each shaped charge geometry studied revealed a different flow pattern during the jet formation…
Abstract Multilayer composite films consisting of polyolefins, either polypropylene, linear low density or medium density polyethylene, a thin adhesive layer, and a polyamide in various ratios were prepared using two basically different processes. The first, a conventional blown film process in which the extrudate is…
Abstract The adsorption and reaction of thiophene and methylthiophenes in the interlayer of Cu 2+ - and Fe 3+ -montmorillonites were investigated by resonance Raman spectroscopy. Thiophene and 3-methylthiophene polymerized to form cations of polythiophene and polymethylthiophene respectively, which were characterized…
The cation and anion exchange capacities (CEC and AEC) as functions of pH were measured for 12 soil samples from various parts of Quebec. In addition to the index cation Ca, Al was measured in the replacing solutions in order to evaluate the contribution of Al to pH-dependent CEC at low pH. Although all of the soils p…
Abstract The title compound was prepared by reacting a corresponding mixture of Na 2 Te 2 , copper and tellurium at 700 °C. NaCu 3 Te 2 forms crystals of metallic lustre which are rapidly decomposed in humid atmosphere. It crystallizes with a rhombohedral structure, space group R3m, with a = 4.276(3) Å, c = 23.78(1) Å…
Abstract Some viologen crystals bearing a p-toluenesulfonate anion as a counter ion were shown to exhibit reversible photoreductions (photochromism) either in air or under vacuum, whereas in a poly(N-vinyl-2-pyrrolidone) matrix all investigated viologens indicated reversible photocolor developments. Amphoteric ions su…
<div class="htmlview paragraph">OVER THE NEXT SEVERAL YEARS, electrochromic mirrors will be introduced for use on automobiles, initially as interior mirrors and later for the exterior. Electrochromic mirrors have variable reflectivity and this offers an opportunity to select a reflectance level that avoids glare…
Abstract Die Aufnahme von Wasserstoff aus Medien kann bei Stählen mit ferritischen Gefügeanteilen zu Schädigungen führen. Die Wechselwirkung von absorbiertem Wasserstoff und Stahl wird einerseits durch die Wasserstoffaktivität, andererseits durch belastungs‐ und gefügeabhängige Grenzwerte bestimmt. Die Arten wassersto…
The equations for the oxidation of a silicon cylinder or sphere or of a cylindrical hole or spherical cavity in silicon are solved exactly in the quasi‐static limit. In all cases, oxidation is complete after a finite time. If the initial oxidized layer is sufficiently thin and the initial radius is sufficiently large,…
The interaction between rat mammary gland thioesterase II and fatty acid synthetase has been studied by a variety of physicochemical techniques. Pyrene-labeled thioesterase II does not exhibit increased fluorescence anisotropy when mixed with fatty acid synthetase, suggesting that the enzymes do not readily form a com…
High-resolution transmission electron microscopy (HRTEM) reveals a wide variety of deviations from perfect crystalline periodicity within many mineral groups. Among the defects, the linear and planar ones are particularly abundant in synthetic and natural phyllosilicates which show a quasi-one-dimensional structural o…
Analogs of the 2',5'-linked adenylate trimer diphosphate (pp5'A2'p5'A2'p5'A or 2-5A) containing 8-bromoadenosine in the first, second, third, first and third, or second and third nucleotide positions (from the 5' terminus) were synthesized and found to vary dramatically in their ability to bind to and activate the RNa…
The threshold field for flexoelectric instability in nematic liquid crystals, and the upper limit of the maximum tilt angle connected with this instability are rigorously evaluated. The nematic liquid crystal, with positive dielectric anisotropy, is assumed to be in the homeotropic configuration, without external fiel…
Abstract The radiation induced grafting of N‐vinylpyrrolidone in aqueous solution onto poly(vinylidene fluoride) (PVF 2 ) films by preirradiation technique using 160 keV electrons has been investigated. Among the grafting parameters, the most important are storage time after irradiation, grafting time, grafting temper…
The aim of this work was to find the quantitative dependences between fracture toughness K lc and the volume fraction of retained austenite in the matrix of quenched high‐speed steels. The tests were carried out on three model alloys of a different content quotient of Mo: W which, after quenching, were gradually super…