Materials Literature
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Porous Vycor glass has been impregnated with selenium and tellurium by pressure forcing the nonwetting semiconductor melt into the interconnected pores. Dense semiconductor microstructures with a characteristic size of 50 Å can be fabricated by this technique. Measurements are reported which show the composite is suit…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAn AM1 theoretical study of the structure and electronic properties of porphyrinCharles H. ReynoldsCite this: J. Org. Chem. 1988, 53, 26, 6061–6064Publication Date (Print):December 1, 1988Publication History Published online1 May 2002Published inissue 1 December 1988https://…
The failure of metal structures in contact with natural, untreated waters is frequently ascribed to bacterial corrosion.1This study compares the corrosive effects of Vibrio natriegens (V.natriegens) when in batch and continuous flow culture. Evidence is presented for enhanced corrosion of carbon steel resulting from “…
ABSTRACT The marine diatom Ampbora coffeaeformis is positively chemotactic to glucose and sugars of similar structure. A free hydroxyl group is required at the 2-position of the ring; however, D-mannose (a toxic sugar) and L-glucose promote negative chemotaxis. Sugar metabolism is not necessary for a chemosen-sory res…
The electrochemistry and spectroelectrochemistry of mononuclear, binuclear and tetranuclear zinc neopentoxy-substituted phthalocyanines are presented. The binuclear and tetranuclear species show two oxidation waves to the radical cation indicating the existence of stable mixed-valence, half-oxidized species. The elect…
The Landau theory of cholesteric blue phases (BP) is reviewed. The emphasis is on basic concepts, including (1) why BP appear between the disordered and ordinary helicoidal phases at sufficiently short pitch, and (2) why there are several cholesteric BP with different structures. These and other results in agreement w…
This is a study of a group of Czochralski grown rare‐earth‐doped Y 2 SiO 5 single‐crystal cathodoluminescent phosphors. Such dopants as Ce 3+ , Tb 3+ , Eu 3+ , Sm 3+ , Tm 3+ , Gd 3+ , and some of their combinations were investigated. Activation by ( Ce 3 + + Gd 3 + ) , ( Tb 3 + + Gd 3 + ) , and by ( Tb 3 + + Eu 3 + )…
We present a detailed study of self-phase modulation in nematic liquid crystals, performing a quantitative comparison with the theory of diffraction. A quite satisfactory fit is obtained at low optical power by taking into account only orientational effects, as it is found that experimental observations are affected b…
Abstract Surface‐enhanced Raman scattering (SERS) of [HVO 4 ] 2− , [HPO 4 ] 2− and [HAsO 4 ] 2− has been studied on silver sol in H 2 O and 2 H 2 O; in H 2 O the spectra were recorded from pH 3 to 12 with excitation at 488.0, 514.5, 568.2 and 647.1 nm. Considerable enhancement was observed compared with conventional R…
Analogies between thermotropic and lyotropic Liquid Crystals were underlined at the earliest time of their investigation, since “smectic” is an old concept shared by the two domains. However, during the last decades, the differences between thermotropic and lyotropic systems were emphasized more than their similaritie…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIs there any beam yet? Uses of synchrotron radiation in the in situ study of electrochemical interfacesH. D. Abruna, J. H. White, M. J. Albarelli, G. M. Bommarito, M. J. Bedzyk, and M. McMillanCite this: J. Phys. Chem. 1988, 92, 25, 7045–7052Publication Date (Print):December…
Lead(II) carboxylates with even chain lengths from octanoate to octadecanoate have been investigated by differential scanning calorimetry, polarizing optical microscopy, X-ray diffraction, and dilatometry, together with Raman, infrared, and 207Pb N.M.R. spectroscopy. The reassignment of the high temperature mesophase…
Stability conditions for irreversible structural systems are formulated on the basis of the second law of thermodynamics. It is found that distinction must be made between stable equilibrium states and stable equilibrium paths. An equilibrium state is stable if any admissible deviation from it leads to a decrease of t…
Powder preforms of zirconia, containing 2.85 mol% yttria, were sinter‐forged in simple uniaxial compression at 1400°C by applying constant displacement rates to the specimens. Shear and densification strains and the uniaxial stress were measured as a function of time. In contrast with alumina and silicon nitride, zirc…
A new method for the molecular-dynamics simulation of bulk planar interfaces at high temperatures is presented. The method uses the basic Parrinello-Rahman (constant-stress) scheme, modified for the application to inhomogeneous systems. Since our computational cell contains only one interface with two-dimensional (2D)…
It was demonstrated recently that, in contrast to large cerebral arteries, distensibility of cerebral arterioles is increased in stroke-prone spontaneously hypertensive rats (SHRSP). The goals of this study were to examine composition of normal cerebral arterioles, and to determine whether chronic hypertension alters…
Myristoyl-CoA:protein N-myristoyltransferase (NMT), the enzyme that transfers the myristoyl (14:0) moiety from myristoyl CoA thioester to nascent proteins, is remarkably specific for both peptide and fatty acyl CoA substrates. To investigate the interaction of NMT with fatty acyl CoA substrates, we have synthesized 10…
The isotropic–nematic phase transition is investigated for several model liquid crystals using the density functional method. The models considered are hard ellipsoids of revolution (both prolate and oblate cases), hard spherocylinders, and two additional fluids characterized by pair potentials of a generalized Maier–…
Clearly distinguishable are the VIV and VV centers of the “outer shell” of the title anion 1, whose center forms a VO4 tetrahedron and a μ3-O atom. The nine μ2-O bridges between VIV centers (black) are protonated, the six between VIV and VV centers (hatched), on the other hand, are not. The formation of 1 confirms the…
The histidine permease of Salmonella typhimurium consists of four protein components, one located in the periplasm and three in the cytoplasmic membrane. Genetic evidence indicated that the periplasmic protein interacts with the membrane proteins during transport. We have utilized two different methods to demonstrate…