Materials Literature
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Abstract Processing of ceramics is reviewed from a broad perspective, with emphasis on the predominant powder‐based methods, but with considerable attention to other methods. Major stages of the powder process, from preparation, modification, and handling, to sintering or pressure densification (or postdensification)…
Cyclic diguanylic acid acts as a regulator for cellulose synthase activity in the bacterium Acetobacter xylinum. We report the x-ray crystal structure of the regulator at atomic resolution. The structure contains two independent molecules that adopt almost identical conformations. The two molecules form self-intercala…
ABSTRACT The galvanic corrosion potentials of thirty‐eight different waters were measured on site, using ‘Oliphant’ corrosion cells, for lead‐tin solder coupled to copper. A wide range in corrosion potential was found, and the chloride‐sulphate ratio had the most significant effect on corrosion potential. Tests to red…
Surface diffusion in sapphire and sintering of Al 2 O 3 have been studied under identical firing conditions (1593°C, N 2 ) as a function of MgO solute additions. The effect of MgO on surface diffusion has been investigated directly using the technique of multiple scratch smoothing on the (1123) surface of sapphire. Fo…
The bending beam method for measurements of stress in thin films deposited on an elastic substrate in the form of a thin stripe has been improved by the introduction of a laser beam deflection system and of a laser spot position detector. With this improvement, stress measurements have been performed in situ during th…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and structural characterization of a polyoxovanadate coordination complex with a hexametalate core: [(n-C4H9)4N]2[V6O13{O2NC(CH2O)3}2]Qin Chen and Jon ZubietaCite this: Inorg. Chem. 1990, 29, 8, 1456–1458Publication Date (Print):April 1, 1990Publication History Pub…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhysical gels of aqueous poly(vinyl alcohol) solutions: a small-angle neutron-scattering studyWen Li Wu, Mitsuhiro Shibayama, Saroj Roy, Hidenobu Kurokawa, Laurence D. Coyne, Shunji Nomura, and Richard S. SteinCite this: Macromolecules 1990, 23, 8, 2245–2251Publication Date…
Abstract The chemical microstructural analysis (CMA) developed by Rowland and his school was applied to Valonia and bacterial cellulose and the results compared to those obtained with cellulose from cotton linters. It was found that the surface reactivity of Valonia was very small, roughly one half of that found for b…
Among the available methods in theoretical shell morphology. moving‐frame method, produce the broadest range of shell shapes and appear to emulate most closely the biological processes involved in shell morphogenesis and growth. In addition, moving‐frame methods can easily be enhnneed in both respects by adding operat…
Abstract In this article we describe an x‐ray photoelectron spectrometer that can either be used as an ultra‐high vacuum instrument ( p < 10 −10 mbar) or, after insertion of a movable aperture, to analyse materials at ambient pressures up to 1 mbar. We will describe the basic design of the instrument, and the metho…
Five acetic acid-sensitive mutants of Acetobacter aceti subsp. aceti no. 1023 were isolated by mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. Three recombinant plasmids that complemented the mutations were isolated from a gene bank of the chromosome DNA of the parental strain constructed in Escherichia coli by…
An instrument capable of detecting and locating partial discharge sites and faults in shielded power cables was developed on behalf of a group of US electric utilities. The instrument uses state-of-the-art electronic hardware and advanced digital signal processing techniques. The partial discharge signals are reconstr…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructural and magnetic studies on macrocyclic dicopper(II) complexes. Influence of electron-withdrawing axial ligands on spin exchangeSanat K. Mandal, Laurence K. Thompson, Michael J. Newlands, Eric J. Gabe, and Kamalaksha NagCite this: Inorg. Chem. 1990, 29, 7, 1324–1327Pu…
This paper presents some of the major results which have contributed to the present understanding of the behaviour of the α-β transition of quartz, one century after its discovery by Le Chatelier in 1889. Most properties of the low temperature α phase can be explained in the frame of the Landau theory of first-order t…
Infrared spectroscopic studies of lead and alkaline‐earth aluminosilicate glasses in the series x MO‐ x Al 2 O 3 (1 ‐ 2 x )SiO 2 M = Mg, Ca, Sr, Ba, and Pb; 0.05 x 0.275] were carried out in the range 2000 to 200 cm −1 . Three major absorption bands were observed in the 1100‐, 800‐, and 500‐cm −1 regions. The frequenc…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhthalocyaninato polysiloxanes substituted with crown ether moietiesO. E. Sielcken, L. A. Van de Kuil, W. Drenth, J. Schoonman, and R. J. M. NolteCite this: J. Am. Chem. Soc. 1990, 112, 8, 3086–3093Publication Date (Print):April 1, 1990Publication History Published online1 M…
Future space power needs are extrapolated to be at least three to four orders of magnitude more than is currently available. This long-term reliable power will be required on missions such as the Space Station, Pathfinder, Space Plane, and high-powered satellites, and for national defense. Electrical insulation and di…
Phase transitions in ferroelastic and other crystals with large elastic anomalies (i.e. co-elastic crystals) follow Landau-type behaviour over extended temperature intervals. No or only weak anomalies occur near the transition point and Landau-type behaviour occurs down to the saturation temperature below which the or…
The observation of a new critical point in liquid-crystal phase transitions is reported. Detailed tilt-angle, polarization, and susceptibility measurements of a ferroelectric liquid-crystal compound in the presence of an applied dc electric field show that a first-order phase transition between the polarized smectic-A…
Abstract A theory based on classical nucleation theory is developed for bubble nucleation in polymer solutions. The theory requires information on solubility, diffusivity, concentration, surface tension, temperature, and degree of supersaturation. The effects of supersaturation and of the presence of large molecules i…