Materials Literature
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Abstract The structure and properties of a preimidized photosensitive polyimide (Probimide PSPI, a copolyimide of benzophenonetetracarboxylic dianhydride with alkyl groups substituted aromatic diamines) were studied with variations of UV exposure energy and bake temperature by means of wide angle X‐ray diffraction, dy…
The surface of gallium arsenide has been bombarded with low energy fluorine ions in order to study their role in modifying the surface during a CHF3 reactive ion etch of oxide overlayers on GaAs. Compositional changes caused by the bombardment of GaAs with ions ranging in energy from 10 to 300 eV have been investigate…
Selective Catalytic Reduction (SCR) and oxidation catalyst technology have been applied to a stationary diesel and dual-fuel (natural gas and #2 diesel) engine for catalytic control of nitrogen oxides (NOx), carbon monoxide (CO), and nonmethane hydrocarbon (NMHC) emissions. At rated conditions, NOx emissions have been…
Some physical parameters of comb-shaped ferroelectric liquid-crystalline polymers were measured. Their rotational viscosities are two or three orders of magnitude larger than that of low molecular weight ferroelectric liquid crystals. Furthermore, they are found generally to be proportional to the second power of the…
Abstract Beim Erhitzen von Vanadium(V)‐oxid mit Rubidiumiodid auf ca. 500°C wird Vanadium partiell reduziert, es entsteht Rb 2 V 3 O 8 . Dieses kristallisiert in der Fresnoit‐Struktur. Kristalldaten: a = 892,29(7), c = 554,49(9) pm bei 20°C, tetragonal, Raumgruppe P4bm, Z = 2. Röntgenstrukturbestimmung mit 620 beobach…
Abstract IR-transmission spectra of 95TeO2·5Fe2O3 glass piece show a gradual decrease in the transmittance due to the crystallization initiating at the surface and spreading to the bulk. XRD, IR absorption spectra, and 57Fe-Mössbauer spectra show the formation of paratellurite (α-TeO2) and iron tellurite in the glass…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXT(Pyridinylmethylidene)dithioles: synthesis, structure, and reactivityKevin T. Potts, Susan A. Nye, and Kennith A. SmithCite this: J. Org. Chem. 1992, 57, 14, 3895–3901Publication Date (Print):July 1, 1992Publication History Published online1 May 2002Published inissue 1 July…
Direct phasing methods based on the probabilistic estimate of triplet and quartet structure invariants are used to determine the crystal structure of boric acid from room-temperature electron diffraction data published by Cowley [Acta Cryst. (1953), 6, 522–529] and also new low-temperature data collected at or below 1…
Abstract 1,3‐Diethynyl‐5,7‐dimethyladamantane, 1,3‐diethynyl‐5‐phenyladamantane, 1,3,5‐triethynyladamantane, and 3,3′‐diethynyl‐1,1′‐biadamantane, were synthesized and polymerized thermally at 210°C. The thermoset resins obtained were post‐cured at 300°C for 16 h to give materials that exhibited onsets of degradation…
In previous work, a two-dimensional waveguide model has been developed and examined extensively so that rigorous light scattering calculations for photolithography-related processes, such as stepper alignment, linewidth and overlay measurements, and resist bleaching, can be performed. The computation, however, is expe…
The binding energy for CO2 adsorbed on Cu(100) has been determined by use of temperature programmed desorption and was found to increase with increasing coverage from 25 to 30 kJ mol−1. The presence of surface oxygen did not significantly increase the CO2 binding energy. High-resolution electron energy-loss spectra re…
Crystal structures in small Al-rich Fe particles were studied by powder X-ray diffraction and transmission electron microscopy. The specimens of the small particles were made by evaporating an Al alloy material containing 5.0-33.3 at.% Fe in Xe gas at a pressure of 3.3 × 103 Pa. The small particles were 70-150 nm in d…
Experimental data on d.c. leakage currents in lead zirconate titanate thin films (210 nm) are presented. The data show a flat, ohmic response up to a thresh-hold of approximately 2.0 V, above which they satisfy a modified Childl's Law, with a perfectly quadratic dependence: I = aV2. This suggests that at 5 V operation…
The authors model the optical properties of metallic quantum wells with thicknesses in the range of a few nanometers. A simple picture that includes only single electron transitions predicts strong absorption lines at frequencies associated with allowed interband transitions. This strong absorption feature can be in t…
Abstract An equilibrium theory is proposed for crystallization of (A, B) binary copolymers whose comonomeric unit sequences are statistically described by conditional pair probabilities P AA , P AB , P BA , and P BB . These are linked to the product of the reactivity ratios by r = r A r B = (P AA P BB )/(P AB P BA ) .…
Abstract Dissolution of phosphate rock (PR) in soil is a necessary prerequisite for the P in the PR to become plant available. The dissolution of two PR materials, Gafsa (GPR) and Christmas Island A (CIPR), in six acid, Malaysian soils (pH in water 3.0–5.4) was examined in closed‐incubation and open‐leaching systems.…
The first part of this paper covers the questions: How can we obtain WBFs (waterproof breathable fabrics)? and What is available? A description of the technique to obtain such fabrics with a statement of general advantages and disadvantages is covered. There are three techniques: 1. High-density fabrics 2. Lamination:…
The piezo-, pyro- and dielectric properties of lanthanum modified lead zirconate titanate (PLZT) ceramics has been investigated as a function of Zr/Ti ratio for 4% La. The pyroelectric coefficients show a minima at the morphotropic phase boundary. The pyroelectric and dielectric properties show different transition te…
Composite repair patches are often cured under vacuum pressure only, and are therefore more porous than their autoclaved counterparts. Thus it is common practice to add extra plies to a composite patch, over and above the number in the original struc ture. However, there is little published work on how the number of e…
Abstract A short report of a new computer simulation of plastic deformation is given in a typical flexible chain glassy polymer–polypropylene. The model which makes no arbitrary assumptions about structure and modes of molecular segment relaxations is based on systematic static energy minimizations in a small periodic…