Materials Literature
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Electrochemical oxidation of ω‐diamines on carbon fibers allows the bonding of these molecules to the carbon fibers. The conditions leading to this surface modification are described, and the influence of the different parameters is discussed. The structure of the bonded layer is studied by voltammetry, XPS, and SIMS.…
Providing the first comprehensive overview of the method of crystal growth in gels, Professor Henisch reviews the field, covering the underlying physics as well as the empirical experience of growth techniques accumulated over the past century. In addition, the book discusses the phenomenon of periodic precipitation,…
Studies of allophanes from New Zealand are reviewed, and a definition of the allophane group of minerals is suggested. Three types of allophane are identified, and their structures are discussed under headings Al-rich soil allophanes, Si-rich soil allophanes and stream deposit allophanes. Examples from New Zealand soi…
The resistance degradation of Al‐doped, Ni‐doped, and Fedoped SrTiO 3 single crystals is studied as a function of the temperature and the applied dc voltage. The individual influence of the acceptor dopants is discussed. Data of the mobility of oxygen vacancies are obtained from the determination of the time evolution…
Determination de la structure cristalline des sous-mailles des phases synthetiques analogues a la birnessite riches en Na, Mg et K. Cristallisation dans C2/m avec pour Na: a=5,175, b=2,850, c=7,337 A, β=103,18°; pour Mg: a=5,049, b=2,845, c=7,051 A, β=96,65°; pour K: a=5,149, b=2,843, c=7,176 A, β=100,76°. La structur…
A quantitative model for the dc voltage‐induced resistance degradation is based on the defect structural material constants and a numerical solution of the general transport problem for the mixed‐conducting perovskite‐type titanates. During degradation, a demixing of the initially homogeneous oxygen vacancy concentrat…
The rate of the resistance degradation of doped SrTiO 3 ceramics is investigated as a function of various external and material parameters. The effects of the mutually interrelated parameters dc voltage, dc electric field, and thickness of the dielectric are described by power laws. Electron microscopic potential cont…
We report on molecular-dynamics simulations of Lennard-Jones liquids sheared between two solid walls. The velocity fields, flow boundary conditions, and fluid structure were studied for a variety of wall and fluid properties. A broad spectrum of boundary conditions was observed including slip, no-slip, and locking. We…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSemiconductor crystallites: a class of large moleculesMichael L. Steigerwald and Louis E. BrusCite this: Acc. Chem. Res. 1990, 23, 6, 183–188Publication Date (Print):June 1, 1990Publication History Published online1 May 2002Published inissue 1 June 1990https://pubs.acs.org/d…
cAPK has provided many insights into the functioning of the diverse family of eukaryotic protein kinases. The fact that a particular amino acid in the catalytic core is conserved is an indication that the residue plays an important role; however, questions concerning function remain obscure. With the catalytic subunit…
A number of extensions to the multisolution approach to the crystallographic phase problem are discussed in which the negative quartet relations play an important role. A phase annealing method, related to the simulated annealing approach in other optimization problems, is proposed and it is shown that it can result i…
X-ray-photoelectron diffraction has been measured from an Al(001) single crystal for the free-electron-like valence band and the well-localized 2s core level, using Mg K\ensuremath{\alpha} radiation. Both show the same high anisotropy of 65% in the azimuthal distribution of the photoemitted electrons at 45\ifmmode^\ci…
The magnetic phases which have earlier been observed when a magnetic field is applied in the plane of the helical magnetic structure of Ho are identified with structures, intermediate between the helix and the fan, which we call helifans. A number of helifan structures have been calculated by a self-consistent mean-fi…
We propose a structure for the self-trapped exciton in \ensuremath{\alpha}-quartz on the basis of ab initio Hartree-Fock cluster calculations. It involves the displacement of a single oxygen atom in a direction nearly parallel to the hexagonal axis so that the shorter of its two silicon-oxygen bonds is lengthened. The…
Rapidly solidified Nd-Fe-B ribbons were crushed and mixed with a fine powder (10–100μm) of a pure element before hot working into fully dense anisotropic magnets. At the high temperatures and pressures required for densification some additives diffused throughout the ribbon matrix and presumably into the neodymium-ric…
An elementary introduction on direct and resonant low-energy (0-20 eV) electron scattering from molecules condensed on surfaces is given with reference to concepts developed from gas-phase investigations. It is shown that while elastic scattering can be described in terms of band-structure parameters, inelastic proces…
The random-loose-packing fraction of uniform spheres at the limit of zero gravitational force is determined to be 0.555\ifmmode\pm\else\textpm\fi{}0.005. This structure corresponds to a sphere packing at its rigidity-percolation threshold. The onset of dilatancy was also measured to be at approximately the same packin…
A large single crystal (18×40×15 mm3) of a new nonlinear optical material ‘‘chalcone derivative’’ has been grown by an evaporation method. This crystal was relatively easy to grow to a large size and was chemically stable. The cutoff wavelength was 430 nm. The calculated phase matching angles for the second-harmonic g…
Abstract The preparation process of amidoxime hollow fiber consists of three steps: (1) radiation‐induced graft polymerization of acrylonitrile (AN) onto porous hollow fiber (AN grafting), (2) chemical conversion of the cyano group into an amidoxime group (amidoximation), and (3) conditioning of the hollow fiber with…
Abstract The behavior of the secondary electron emission (SEE) from organic solids has been considered. It has been shown that the maximum SEE yields of many hydrocarbon compounds exponentially depend on the extinction coefficient of secondary electron defined by the π‐electron fraction in molecule, which is correlate…