Materials Literature
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High-resolution x-ray scattering and ac-calorimetric measurements have been carried out near the nematic--smectic-${\mathit{A}}_{1}$ phase transition of the pure liquid-crystal compound octyloxyphenylnitrobenzoyl- oxy benzoate (${\mathrm{DB}}_{8}$${\mathrm{ONO}}_{2}$). Several forms of the structure factor S(q) for fi…
This report describes the design and construction of apparatus to measure the specific heat capacity of solid materials in the temperature range IB-32°C. The apparatus is designed to minimize heat losses from the sample in order to measure the specific heat to an accuracy of better than :to.2% at the 95% confidence le…
Experimental results of very large, long-wavelength photocurrent gains in amorphous silicon-based Schottky barrier structures are reported. It is shown that these occur for devices in the space-charge current regime operated at forward bias voltages past the flatband condition. The analysis of microelectronic and phot…
ABSTRACf The results of electron-microprobe analyses of 38 samples of allanite from granitic rocks and calcite veins in the Grenville province of southeastem Ontario'and southwestem Quebec are presented. Allanite from granitic rocks show a w.ider rang e o!ffn contentsthanttrosefromcarbonateveins.Thesamplesofallanitest…
Abstract Crystallization of polymers plays an important role in polymer processing because the structure developed during crystallization influences the mechanical and physical properties of the polymer product. The crystallization of polymers takes place under nonisothermal crystallization is essential for optimizing…
Modern scanning electron microscopy yields structural information down to 2 to 5 nm from thin, beam transparent biological specimens. This paper examines the possibilities of garnering this level of structural information from bulk, frozen-hydrated samples. Freeze-fractured, frozen-hydrated yeast cells, frequently tak…
Abstract Due to the ever growing and more complex demands on the properties of polymer materials, raw material producers and plastic processing industries are more and more interested in the continuous synthesis and modification of polymers. In this article the production of polystyrene and styrene–isoprene copolymers…
Abstract We have investigated the effect of added Si0 2 on the photochemistry of anthracene, 1, in cyclohexane. Adsorption of 1 onto the Si0 2 surface from cyclohexane follows a Freundlich adsorption isotherm indicating interactions between 1 and the surface over a distribution of adsorption sites. In the absence of o…
Up-conversion emission spectra of fluorophosphate glasses doped with Tm3+ and co-doped with Tm3+ and Yb3+ ions were obtained under two different excitation wavelengths (657 and 683 nm). Both samples show a stronger emission centered at 450 nm than the ones centered at 478 and 363 nm when 3F2 level of Tm3+ is excited a…
Abstract The electrochemical oxidation of anodic cobalt, nickel, and zinc in acetonitrile containing both 2‐pyrrole‐[N‐( o ‐hydroxyphenyl)methylimines] (H 2 L) and a bidentate ligand (1, 10‐phenanthroline(phen) or 2,2′‐bipyridine(bipy)) yielded compounds of general formula M(HL) 2 · phen and M(HL) 2 · bipy (M = Co, Ni…
Phase equilibria in the system ZrO 2 ─InO 1.5 have been investigated in the temperature range from 800° to 1700°C Up to 4 mol%, InO 1.5 is soluble in t ‐ZrO 2 at 1500°C. The martensitic transformation temperature m → t of ZrO 2 containing InO 1.5 is compared with that of ZrO 2 solid solutions with various other trival…
Abstract The interest for star‐shaped polymers arises from their unique structure and enhanced segment density. This paper will review the different methods of preparation for star‐shaped polymers. Two cases of special interest will be considered in greater detail: the core‐first method which gives access to end‐funct…
Two ultra-high-temperature materials, hafnium carbide and hafnium diboride, were oxidized in the temperature range 1400 to 2100 C. The two materials oxidized in distinctly different ways. The carbide formed a three-layer system consisting of a layer of residual carbide, a layer of reduced (partially oxidized) hafnium…
The local structure of a Na 2 O─SiO 2 oxide glass and a Na 2 O─iO 2 ─Si 3 N 4 oxynitride glass has been investigated by the pulsed neutron diffraction method. In the oxide glass, the first peak of radial distribution function (RDF) curves appeared at 0.1627 nm corresponding to Si─O boxh length. In the oxynitride glass…
Abstract The permeation and separation characteristics of poly(vinyl chloride) (PVC) and poly[(vinyl chloride)‐ co ‐(vinyl acetate)] (poly(VC‐ co ‐VAc)) membranes were investigated for aqueous organic acid solutions by pervaporation and evapomeation. The PVC membrane preferentially incorporates organic acids and predo…
Abstract Cyclopentanone condensed with phenylhydrazones 5 , or oximes 6 , in the presence of zinc dust, sodium propionate and propionic acid at 150° to give cyclopenta[ b ]pyrroles 7 in good yields. This chemistry was extended to the synthesis of pyrrolic products from 1‐indanone, 2‐indanone and 2‐methylcyclopentanone…
A computation of power transformer parameters with a numerical method using finite elements is presented. The modeling, based on the calculation of the 3-D electromagnetic field, allows a novel approach to the study of the high-frequency phenomena that propagate along the transformer windings. These parameters include…
Increased likelihood of armed forces operations occurring in hostile climatic regions have increased the need for highly specialized protective clothing systems. Protection is needed under a variety of conditions which often present conflicting requirements. Protective military clothing provides broad design possibili…
Abstract Pipes of isotactic polybutene‐1 (PB) have been exposed to internal water and external air in pressure tests at 105°C. The pipes exposed to different internal pressures exhibited different failure mechanisms, referred to as stages I, II, and III. Samples taken from these pipes have been analyzed by infrared (I…
The authors discuss the 3-D electromagnetic modeling of a transformer to evaluate eddy current losses in the tank. To achieve this, several numerical methods are used with two 3-D field computation packages. Conventional volume elements and shell elements are used for the modeling of thin conducting regions. Surface e…