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  • 1
    Electronic Resource
    Electronic Resource
    Surface chemistry and structure of silicon oxycarbide gels and glasses (1997)
    Springer
    Journal of sol gel science and technology 8 (1997), S. 371-376 
    Details
    ISSN: 1573-4846
    Keywords: oxycarbide glass ; surface hydroxyls ; infra-red ; surface area
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In this study, the surface chemistry and structure of methyl-substituted silica gels and porous oxycarbide glasses were investigated. FTIR was used to measure the relative concentration of Si−CH3 and Si−OH as a function of the degree of methyl-substitution and the pyrolysis temperature. The gels and glasses were further heated, dehydrated or hydrated, in situ, within the FTIR spectrometer. In the temperature range of 800–850°C, high surface area oxycarbide glasses were created with no detectable surface hydroxyl groups. Oxycarbide glasses synthesized in argon at 700°C displayed a weak band for surface hydroxyl groups and reversible physisorption of water, while those synthesized at 850/900°C showed a complete absence of surface hydroxyl groups and the formation of vicinal silanols upon chemisorption of water. Isolated silanols were observed upon heat treatment in vacuum. Formation of aromatic carbon species was found to correlate with the decomposition of the methyl groups. The oxycarbide surface is quite stable to densification (presumably due to elemental carbon on the pore surfaces). In the absence of oxygen, porous silicon oxycarbide glass powders maintain surface areas 〉200 m2/g at 1200°C. However, oxidizing species in the atmosphere deplete the aromatic carbon species, and the glasses lose surface area.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02436867
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  • 2
    Electronic Resource
    Electronic Resource
    Variation in a wild groundnut species, Arachis duranensis Krapov. & W.C. Gregory (1996)
    Springer
    Genetic resources and crop evolution 43 (1996), S. 135-142 
    Details
    ISSN: 1573-5109
    Keywords: Arachis duranensis ; groundnut rust ; principal component analysis ; protein profile ; variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Forty-two accessions of Arachis duranensis, a wild groundnut species that has been reported as a source of resistance to several groundnut diseases, were studied for 30 quantitative traits including total protein content, oil content, and reaction to groundnut rust. Protein profiles were also investigated for variation at the molecular level. Principal component analysis was applied to 28 traits that showed significant variation. Of these, only five characters, namely, height of the main stem, length of apical leaflet on the main stem, length of isthmus between pods, width of seed, and reaction to groundnut rust, accounted for more than 61.4% of the total variation. Protein profiles of these accessions were broadly similar, except some accessions which differed in few bands. The importance of these variations in strategies for germplasm collection and breeding is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00126757
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    Paper (German National Licenses)
    Fulltext
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