Materials Literature
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Prediction of the response of gas-filled microbubbles to ultrasound waves is complicated by the finite-amplitude distortion associated with large-amplitude acoustic fields. Typical finite-amplitude pulses in medical applications consist of a sharp positive spike followed by a smaller slowly varying negative pressure.…
High-efficiency high-bandwidth organic-on-inorganic (OI) semiconductor heterojunction photodetectors are discussed. The devices consist of a thin layer of the organic semiconductor perylenetetracarboxylic dianhydride (PTCDA) in contact with an inorganic semiconductor (Si) substrate. Indium tin oxide (ITO) is used as a…
Organic silanes and titanates were added to a system of polyethylene and silicon nitride intended for injection molding and to a model system of paraffin oil and silicon nitride. The effect of the additions on viscosity was studied. Results from the model system agree comparatively well with the results from the syste…
Abstract In Monitor Valley, Nevada, two Entisols and an Aridisol containing volcanic glass have silica cementation that is first manifest as microagglomerates and later as macroscopic (>2‐mm) durinodes and weakly cemented s‐matrix. The initial effect of silicification is cementation of silt and clay by opaline SiO…
A general treatment of the injection-limited currents (ILC) at the insulator intersurface, based on the continuity equation including source current, is presented. Various approximations are discussed of which the one-dimensional Onsager model is a particular case for a weak gradient source current or the injection di…
The disc-like compounds, 5,6,5′,6′,5″,6″,5‴,6‴-octadodecyltetrapyrazino[2,3-b:2′,3′-g:2″,3″-I:2‴,3‴-q]porphyrazine (C12PzH2) and the copper(II) complex (C12PzCu), which have now been synthesized, exhibit different columnar mesomorphism (Dhd for C12PzH2, Drd for C12PzCu).
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAromatization of tetralone derivatives by 5,10,15,20-tetrakis(pentafluorophenyl)porphyrinatoiron(III) chloride/iodosobenzene and cytochrome P-450cam: a model study on aromatase cytochrome P-450 reactionYoshihito Watanabe and Yuzuru IshimuraCite this: J. Am. Chem. Soc. 1989,…
The full experimental phase diagrams of mixtures of the nematic liquid crystal 4.4′-azoxyanisole, (PAA), and n-tetracosane and of PAA and n-octadecane are given. Equilibria of a nematic phase with an isotropic phase, of two isotropic phases, and a reentrant isotropic phase could be observed directly. The experimental…
The addition of Ga to Nd-Fe-B sintered and die-upset magnets in order to improve thermal stability was examined. The Ga addition increases the coercivity of Nd(Fe/sub 0.72/Co/sub 0.2/B/sub 0.08/)/sub 5.6/ sintered magnets markedly. Ga addition does not enhance coercivity of sintered magnets with lower Co substitution.…
The hydrogen exchange reaction of surface OD groups on MgO with H2(—OD + H2→—OH + HD) has been investigated in order to understand the relationship between the activity and the local structure of the surface hydroxyl groups by means of i.r. spectroscopy. OD groups on the Mg atom are composed of three types exhibiting…
A new laboratory wear test for simulating cutting tool wear is proposed in which the contact conditions in machining are reproduced by letting a tool material pin slide continuously against a fresh countermaterial surface. Wear tests with high speed steel (HSS) pins in the uncoated and TiN coated conditions have been…
Symmetry determination of three-dimensional (usual) crystals, four-dimensional (one-dimensionally incommensurate) crystals and five- and six-dimensional crystals (quasicrystals) by convergent-beam electron diffraction is described and demonstrated using real materials. Crystal structure refinement based on the dynamic…
Austenitic stainless steels (alloys 304, 316, 310) have been immersed in acidified 15M LiCl solutions at 90°C and analysed by Auger electron spectroscopy. The tarnish films formed on the 304 and 316 steels contain some oxygen, but otherwise have compositiondepth profiles similar to those of dealloyed metallic layers.…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSmall-angle light scattering from nematic liquid crystals: fluctuations of director field due to many-body interactions of disclinationsT. Hashimoto, A. Nakai, T. Shiwaku, H. Hasegawa, S. Rojstaczer, and R. S. SteinCite this: Macromolecules 1989, 22, 1, 422–429Publication Da…
Abstract The concepts of coherence and composition paths, originally developed for multicomponent chromatography, are used to establish a simple theory of transport in systems with precipitation and dissolution in the course of multicomponent, single‐phase flow in permeable media. Composition route construction in pha…
The glass-forming regions in the ternary systems LiX (X=F and Br)-Li2O-TeO2 were established in the present study. For X=Br the glass-forming region was found to be widened up to about 75mol% LiBr on the LiBr rich side compared to the system containing LiCl which was studied previously, while the region for X=F was re…
Veneer-faced low-density particleboards were made using four combinations of control and acetylatcd veneers and particles.These boards were tested for dimensional stability in both liquid water and water vapor, for decay resistance in standard soil-block tests with Tyrornyces palustris and Trametes versicolor, for str…
Mechanical behavior of Al2O3-based ceramics can be improved by dispersion of pure or partially stabilized ZrO2 particles. The effective toughening or strengthening effect, which is operating in these composite materials, is determined by microstructural characteristics (composition, processing conditions) and environm…
A pronounced synergetic effect has been found when LaMn1–xCuxO3(x= 0.3–0.5) was prepared by a freeze-drying method from metal acetates of each component; LaMn0.6Cu0.4O3 showed much higher catalytic activity for the reactions of CO–O2 and NO–CO in comparison with LaMnO3 and La2CuO4.
The electrochemical behaviour of polyaniline (PAn) in weak acid solutions such as pH 4 has been studied. It has been found that PAn gives a stable redox reaction involving electrolyte anions in a limited potential region, whereas it loses its electrochemical activity by being oxidized at more anodic potentials where d…