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  • PACS. 61.10.Eq X-ray scattering (including small-angle scattering) - 61.10.Ht X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc. - 61.16.Bg Transmission, reflection and scanning electron microscopy (including EBIC)  (1)
  • alumina  (1)
  • hard metals  (1)
  • Springer  (2)
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  • Springer  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials synthesis and processing 8 (2000), S. 145-153 
    ISSN: 1573-4870
    Keywords: Quartz ; alumina ; hard metals ; toxicity ; free radicals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The release of free radicals from mechanically ground mineral dusts in aqueous suspensions has been employed to predict the possible pathogenic potential of the dusts when inhaled. Two separate free radical-generating reactions have been considered: formation of the •OH radical from hydrogen peroxide via a "Fentonlike" reaction and of a carbon centered radical, following cleavage of a carbon–hydrogen bond. The particulate examined were: variously contaminated quartz dusts, whose well-documented pathogenicity varies from one to the other source; iron- and titanium-doped alumina pigments, prepared via a mechanochemical reaction, whose pathogenic potential is unknown, and hard metal mixtures, obtained from tungsten carbide (WC) and one metal dust, namely Fe, Co, or Ni, the cobalt mixture only being a renown hazardous material. Quartz obtained by grinding coarse particles in grinding chambers composed of steel, widia, corundum, and agate, retain some characteristics of the wall chamber material, which deeply affects its capability to generate radicals and may explain the variability of quartz hazard. Insertion of ions in the mechanochemically prepared pigments imparts to the particle suspected free radical-generating properties. Among the hard metal mixtures examined, the most active is the cobalt one.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-6079
    Keywords: PACS. 61.10.Eq X-ray scattering (including small-angle scattering) - 61.10.Ht X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc. - 61.16.Bg Transmission, reflection and scanning electron microscopy (including EBIC)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: The structure of Rh/pumice catalysts prepared by the SMAD (Solvated Metal Atoms Dispersion) technique at different metal loadings has been investigated by EXAFS (Extended X-ray Absorption Fine Structure Spectroscopy), XPS (X-ray Photoelectron Spectroscopy), SAXS (Small-Angle X-ray Scattering), WAXS (Wide-Angle X-ray Scattering) and TEM (Transmission Electron Microscopy). According to EXAFS and XPS, a fraction of the Rh atoms is oxidised, but a noticeable part is also present as Rh 0. The Rh oxidation is attributed to the interaction of the Rh atoms with the hydroxyls of the support; after the formation of the oxide, the nucleation of metallic rhodium becomes possible. The WAXS data do not show evidence of rhodium fcc crystallites; the metal-bearing particles are probably amorphous and/or very small, as results from the SAXS and TEM data analysis. The disagreement between the latter two techniques, resulting in a small-angle determination of the average size of the particles that is about half that of TEM in the catalyst with the higher Rh loading, is acknowledged and discussed. Preliminary catalytic tests are described, demonstrating the suitability of using a low surface area support for the preparation of SMAD catalysts.
    Type of Medium: Electronic Resource
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