Materials Literature
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Abstract The structure of well ground cellulose I and cellulose II samples was studied by measuring the X‐ray scattering intensities and calculating the corresponding radial atomic density functions (RDFs). Experimentally obtained results have been compared with model calculations mainly varying the packing of nearest…
Abstract The catalytic power of Ca-nontronite, Ca-bentonite, and Ca-kaolinite in promoting the abiotic ring cleavage of pyrogallol (1,2,3-trihydroxybenzene) and the associated formation of humic polymers was studied in systems free of microbial activity. The presence of Ca-kaolinite and especially Ca-nontronite in the…
We determined the value of MR for detecting abnormalities of the uterus caused by in utero exposure to diethylstilbestrol in patients in whom such abnormalities were evident on hysterosalpingography. Of 200 women with a history of diethylstilbestrol exposure in utero, 12 had undergone hysterosalpingography as part of…
The utility of circularly polarized luminescence (CPL) spectroscopy in the study of lanthanide ion coordination chemistry has been described. A variety of optically active Tb(III) and Eu(III) compounds have been considered, containing chiral carboxylic acids, chiral amino acids, chiral aminopolycarboxylic acids, achir…
Abstract Dynamic mechanical thermal analysis and calorimetric studies are reported on blends of poly(ethylene oxide) (PEO) with poly( N ‐vinyl pyrrolidone) (PVP) between 80% and 40% PEO. DMTA curves show a peak corresponding to a phase of pure PEO and another peak which can be attributed to blended material. The calor…
Abstract The formation of kaolinite from Al hydroxy interlayered Garfield nontronite has been carried out at 225°C in hydrothermal conditions. The kaolinitization process, which proceeds through mixed-layer kaolinite/smectite intermediates, was followed by XRD, IR and ESR spectroscopy, chemical analysis and charge pro…
The d.c. flux decay test has been proposed as an alternative and attractive method of extracting synchronous machine parameters. With the machine stationary, direct current is passed through two phases and the decay of current is observed following the short-circuiting of the supply. Tests on two large turbinegenerato…
Anodicallyoxidized alumina has been investigated theoretically and experimentally concerning the anisotropy of its optical loss and refractive index. When the pores in the alumina film are filled with metallic materials, the film yields anisotropy of the optical loss and consequently acts as a polarizer. However, the…
Abstract Under the right conditions, high strengths are shown to be achievable in vibration welded polycarbonate to polyetherimide Joints. While welding of thermoplastic interfaces of the same material can be understood in terms of interchain diffusion at elevated temperatures, this mechanism is severely limited in th…
By inserting a lambda placMu bacteriophage into gene glmS encoding glucosamine 6-phosphate synthetase (GlmS), the key enzyme of amino sugar biosynthesis, a nonreverting mutant of Escherichia coli K-12 that was strictly dependent on exogenous N-acetyl-D-glucosamine or D-glucosamine was generated. Analysis of suppressor…
Abstract A quantitative simulation in the cluster approximation is made of an autolocalized hole in the amorphous SiO 2 network. A model is suggested in which the thermal excitation of holes from Anderson localized states of the top of the silica valence band above the mobility edge corresponds to the thermally stimul…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA new tetranuclear oxohydroxoiron(III) cluster: crystal structure, magnetic properties, and EXAFS investigation of [L4Fe4(.mu.-O)2(.mu.-OH)4]I4.cntdot.3H2O (L = 1,4,7-triazacyclononane)Stefan Drueke, Karl Wieghardt, Bernhard Nuber, Johannes Weiss, Emile L. Bominaar, A. Sawar…
Abstract CO 2 sorption and transport were investigated for the polyimide prepared from 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA) and 4,4′‐diaminodiphenyl sulfone (DDS). The morphology of films did not change on annealing above the glass transition temperature and remained amorphous unlike the polyimide prep…
Stephanodiscus species from central and northern Canadian lakes have been investigated and their morphology illustrated with the help of light and electron microscopy. Stephanodiscus vestibulis Håkansson, Theriot & Stoermer and Stephanodiscus hantzschii fo. tenuis (Hustedt) Håkansson & Stoermer are identified with cer…
The effects of the density ratio and the polymer’s curing rate on the characteristics of polymer dispersed nematic liquid crystal (NLC) films are reported. Measurements indicated that the slope of the electro-optical response curve, which determines the film’s multiplexing capability, is a strong function of the unifo…
A new lyotropic liquid crystal, potassium laurate, decylammonium chloride and water, which has two uniaxial phases and a biaxial nematic phase, is reported. A surface of the phase diagram and X-ray diffraction studies are presented. The chemical stability of this mixture is compared with the potassium laurate/decanol/…
PZT powder of the composition Pb(Zr0.53Ti0.47)O3 was modified by the incorporation of Sr2+, La3+ and Fe3+ as isovalent, supervalent and subvalent cations respectively using spray drying technique. Powders were calcined and converted into piezoelectric ceramics by cold compaction, sintering and poling. Finished ceramic…
Understanding the relationship between the molecular structure and the macroscopic properties of polymer solutions and gels, oil-water-surfactant emulsions, lyotropic and thermotropic liquid crystals, colloidal dispersions, detergents, and other such "microstructured fluids" is essential to the optimal use of these co…
Cladistic analysis of species of the diatom genus Gomphoneis indicates that possession of doubly punctate striae and marginal laminae is sufficient but not necessary for inclusion in the genus. This diagnosis is compared to previous interpretations of Gomphoneis. Within Gomphoneis two subgeneric groups are recognized.…
The sintering of glass can sometimes be impeded by crystallization. In the optimum process the glass should sinter to full density before the onset of crystallization. In an earlier paper we showed how sinter‐forging experiments can be used to investigate the coupling between densification and crystallization. Here we…