Materials Literature
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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAnionic polymerization of lactones. 14. Anionic block copolymerization of δ-valerolactone and L-lactide initiated with potassium methoxidePiotr Kurcok, Jan Penczek, Jan Franek, and Zbigniew JedlinskiCite this: Macromolecules 1992, 25, 9, 2285–2289Publication Date (Print):Apr…
A ruling engine for large and/or high-groove density gratings is developed. A hybrid driving method that uses a piezoelectric device and a screw-nut mechanism is adopted to achieve stop-and-go blank motion with a closed-loop control system. Several test gratings, including a ruled area of 300(width) x 200(groove lengt…
The compressional mechanism of a random fiber assembly is analyzed by an energy method. An infinitesimal fiber segment, which is bounded by two neighboring contact points, is chosen as the unit bending element. The geometry of this element is characterized by its arc length, curvature, and orientation. The change in b…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNature of the manganese(I)-dioxolene bonding as a function of the ligand oxidation state: UV-visible, IR, and resonance Raman spectroelectrochemical study of [Mn(CO)3Ln(Diox)]z (n = 0, 1; z = -2, -1, 0, +1) and [Mn(CO)2{P(OEt)3}m(Diox)]z (m = 1, 2; z = -1, 0, +1) complexesFr…
Transparent glasses with densities greater than 8 g/mL, which are resistant to nuclear radiation damage and can serve as a host for rare‐earth scintillators, are being developed. Glasses in the PbO–Bi 2 O 3 system are known to have some of the highest densities yet reported. In this study, a thorough reexamination of…
Dynamic water vapor and heat transport in the transient state was investigated for fabrics made of polyester, acrylic, cotton, and wool fibers. The overall dissipation rate of water vapor depends on both the vapor transport rate and the vapor absorption by fibers, which are mutually interrelated. Water vapor transport…
A standard model of glasses is shown to exhibit unexpected and remarkably simple elastic properties. For a sequence of networks of decreasing degree or coordination z, the number of zero-frequency vibrational modes (also called ``degrees of freedom'') increases as ${\mathit{e}}^{\mathrm{\ensuremath{-}}\mathit{z}/\math…
Boron carbide–boron nitride particulate composites were fabricated by vacuum hot‐pressing. Near‐theoretical densities of B 4 C were obtained, but percent theoretical densities decreased with increasing amounts of BN. The grain size of B 4 C and BN was not affected by composition, but the amount of twinning in B 4 C de…
A SiO 2 ─Al 2 O 3 ─CaO─CaF 2 ionomer glass was investigated using thermal analysis, X‐ray diffraction, and scanning electron microscopy. The purpose of this investigation was to control the susceptibility of the glass to acid attack. The differential thermal analysis trace exhibited a sharp glass transition at about 6…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSurface-enhanced Raman scattering of the acid-base forms of imidazole on silverDavid A. Carter and Jeanne E. PembertonCite this: Langmuir 1992, 8, 4, 1218–1225Publication Date (Print):April 1, 1992Publication History Published online1 May 2002Published inissue 1 April 1992ht…
We report a simple and quick synthesis of tetrapyrrolic macrocycle in dry media conditions, under microwave irradiation. Heating in microwave oven pyrrole and benzaldehyde adsorbed on a solid acidic support affords tetraphenylporphyrin within ten minutes with very simplified treatment and purification.
An experimental technique for measuring the time-varying response of an oscillating, acoustically levitated air bubble in water is developed. The bubble is levitated in a resonant cell driven in the (r,θ,z) mode of (1,0,1) at a frequency fd≊24 kHz. Linearly polarized laser light (Ar–I 488.0 nm) is scattered from the b…
The objectives of this study were to examine (1) interrelationships between various forms of extractable A1 and selected soil properties, (2) the contribution of extractable A1 to pH buffer capacity, and (3) investigate the use of extractable A1 to predict lime requirement. Aluminium was extracted from each of 60 Quee…
Abstract Blends of an aromatic polyethersulfone (commercial name Victrex) and a polyimide (commercial name Matrimid 5218), the condensation product of 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride and 5(6)‐amino‐1‐(4′‐aminophenyl)‐1,3,3′‐trimethylindane, were studied by differential scanning calorimetry, dynamic…
Low-energy electron diffraction (LEED) is a well established technique for evaluation of the surface atom arrangement. The information is derived from the elastically scattered electrons. Usually the thermal diffuse background between diffraction spots is assumed to be constant and subtracted as a constant. For spot p…
Analyses of unprotected loss-of-flow accidents for medium-size cores of current liquid-metal fast breeder reactors have shown that the accident proceeds into a transition phase where further meltdown is accompanied by recriticalities and secondary excursions. Assuming very pessimistic conditions concerning fuel discha…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructures in solution and in the solid state of the complexes of lanthanum(III) with 1,10-phenanthroline. X-ray crystallographic and proton, carbon-13, oxygen-17 and lanthanum-139 solution NMR studiesMonique Frechette, Ian R. Butler, Rosemary Hynes, and Christian DetellierC…
An extensive statistical accelerated aging experiment, involving a total of 180 unfilled type epoxy specimens, has been conducted to determine the number of voltage surges required to initiate electrical trees under various magnitudes, surge repetition rates, and polarity conditions. The specimens were tested one at a…
Two groups of weft-knitted fabrics, single and double knits, were selected to represent typical summer T-shirts and winter sportswear such as sweaters and other knit tops. Two kinds of analyses were performed: subjective overall handle and primary sensory factors were evaluated using a 99 point polar-word scale, and p…
The local rise of lattice temperature in n-MOSFETs is analyzed by the energy shift of the silicon optical phonon using Raman spectroscopy with submicrometer spatial resolution. When operating the devices in saturation, a source-drain temperature asymmetry is observed corresponding to the heat dissipation profile that…