Materials Literature
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The aim of this paper is to show that different assumptions for the interaction cross sections of low-energy electrons in polycrystalline aluminum targets lead to very different calculated values of secondary-electron yields, either in backscattering or in transmission. We emphasize the importance of the description o…
Diamond has been grown on single-crystal beryllium oxide by hot-filament chemical-vapor deposition. The diamond particles were characterized by Raman spectroscopy, and the morphology and microstructure investigated by scanning electron microscopy and plan-view and cross-sectional transmission electron microscopy. Diam…
The aqueous corrosion behavior of hot isostatically pressed Si 3 N 4 (HIPed‐Si 3 N 4 ) without additives was studied under hydrothermal conditions at 300°C and 8.6 MPa (86 atm). The accelerated weight loss in the HIPed‐Si 3 N 4 was attributed to uniform thinning of the specimen accompanied by dislodgement of Si 3 N 4…
Abstract The synthesis of stiff‐chain poly(1,4‐phenylene terephthalamide)s substituted by two as well as by four flexible side chains per repeating unit is described. The solubility of the materials bearing only two side chains is still very low. Appending of four side chains leads to polyamides which dissolve in comm…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCrystal-protein interactions: controlled anisotropic changes in crystal microtextureAmir Berman, Jonathan Hanson, Leslie Leiserowitz, Thomas F. Koetzle, Stephen Weiner, and Lia AddadiCite this: J. Phys. Chem. 1993, 97, 19, 5162–5170Publication Date (Print):May 1, 1993Publica…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotoperturbation of the 1A .dblharw. 5T spin equilibrium in an iron(II) complex in solution via ligand field excitationJohn J. McGarvey, Hans Toftlund, Ala H. R. Al-Obaidi, K. Paul Taylor, and Steven E. J. BellCite this: Inorg. Chem. 1993, 32, 11, 2469–2472Publication Date…
A model is worked out for the interpretation of the magnetic properties of polyoxovanadium clusters, containing both localized and delocalized vanadium(IV). The role of exchange and delocalization is worked out parametrically for two model systems containing four localized and two and four delocalized vanadium(IV) ove…
Powder X-ray diffraction data for corundum were collected by a variety of methods and reduced to structure amplitudes by two profile-fitting techniques. The resulting averaged powder-data set was merged with three different single-crystal data sets to assess the improvements possible over least-squares modelling of ex…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis of sulfido and oxo complexes of technetium(V) and rhenium(V) containing dithiolato and hydrotris(1-pyrazolyl)borato ligands. Crystal structures of dimeric bis(.mu.-ethane-1,2-dithiolato)bis(ethene-1,2-dithiolato)technetium(IV) and [hydrotris(1-pyrazolyl)borato](eth…
The smectic A (SA)-chiral smectic C (S*C) transition in binary mixtures of methylchloropentanoyloxy heptyloxybiphenyl (C7) and butyloxyphenyl decyloxybenzoate (10O.4) changes from first order to second order as a function of X, the mole per cent of 10O.4. High resolution heat capacity measurements show that the Cp beh…
dc and ac magnetic measurements combined with M\"ossbauer spectroscopy have been used to study the evolution of magnetic order below the critical temperature ${\mathit{T}}_{\mathit{c}}$ in polycrystalline powders of the intermetallic compounds ${\mathrm{YFe}}_{10}$${\mathrm{Mo}}_{2}$ and ${\mathrm{LuFe}}_{10}$${\mathr…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSurface nature of Grignard reagent formation. Chiral 1-methylspiro[2.5]octylmagnesium bromideC. Hamdouchi, M. Topolski, V. Goedken, and H. M. WalborskyCite this: J. Org. Chem. 1993, 58, 11, 3148–3155Publication Date (Print):May 1, 1993Publication History Published online1 Ma…
The effect of defect structure on electrical conductivity for Mn‐doped BaTiO 3 at high temperatures was studied experimentally and theoretically. The measured conductivity was proportional to P o2 −1/4 in the n ‐type region, and to P o2 +1/6 in the p ‐type region in the temperature range between 900° and 1000°C. The r…
Abstract Octabromotetraphenylporphyrin adopts a severe saddle-shaped distorted structure owing to the steric crowding of heavy bromine substituents. The rate enhancement of porphyrin metalation reaction is primarily due to the nonplanarity of the ring while the electronic effect diminishes the affinity of the porphyri…
The preparation and the conversion in ceramics of the precursor cross‐linked copolysilazane (CPSZ) of formula (ViSiHNH) x (MeSiHNH) y have been summarized in Part I. Part II will examine the evolution and the thermal behavior of CPSZ at high temperatures under argon atmosphere. Gaseous phase, graphite or alumina cruci…
ZnO varistors with and without ZnO crystalline seeds have been prepared through conventional ceramic processing. Their electrical nonuniformity has been carefully examined using microcontact measurements of single grain boundaries, current‐voltage ( I‐V ) characteristics, and dielectric temperature spectra of bulk sam…
Corrosion of prestressing steel in concrete has become a major technological problem in highways, buildings, and pipeline structures. While cathodic protection is recognized as an appropriate technique to mitigate corrosion of reinforcing steel in concrete, the possibility of environmental cracking (hydrogen embrittle…
Abstract Development of crystallinity in NEW‐TPI semicrystalline polyimide has been studied using differential scanning calorimetry (DSC), wide (WAXS), and small angle X‐ray scattering (SAXS). Crystallinity of the fully imidized powder, pellet, or film processed NEW‐TPI can occur from the melt, and depends upon the ho…
The basic properties of conducting polymers which can be coloured by reversible electrochemical doping processes, are briefly described. The application of these materials for the development of optical devices of technological importance, such as electrochromic displays and windows, is also illustrated and discussed.
Arthrobacter sp. strain NO-18 was first isolated from soil as a bacterium which could degrade the sodium acrylate oligomer and utilize it as the sole source of carbon. When 0.2% (wt/wt) oligomer was added to the culture medium, the acrylate oligomer was found to be degraded by 70 to 80% in 2 weeks, using gel permeatio…