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  • 1
    Electronic Resource
    Electronic Resource
    Hydrous oxides of titanium: cation exchange properties and kinetics of exchange (1991)
    Springer
    Journal of materials science 26 (1991), S. 4937-4944 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The ion exchange properties of hydrous titania gels of different particle sizes, precipitated from titanous chloride through the agency of ammonium carbonate and hydroxide have been studied. Such studies were carried out under acidic and alkaline conditions with respect to Cu2+, Ni2+, Co2+ and Cr3+ ions. In the case of gels precipitated by ammonium carbonate, oxygen gas was used as the oxidizing agent whereas with ammonium hydroxide as precipitant, oxidation was performed with hydrogen peroxide. Ion exchange capacities were determined by visible spectrophotometry. Increasing the pH of preparation lead to an increase in exchange capacities of the hydroxide precipitated gels that are characterized to be mesoporous. Such an increase is not observed in the case of carbonate precipitated microporous gels. It is shown that in the latter case the NH 4 + ions generated by the initial interaction of (NH4)2CO3 with the acidic titanous chloride lead to the formation of titania exchangers that are predominantly in the ammonium form. The textural characteristics of the exchanger resulting from different conditions of preparation is a significant contributing parameter to the resulting data. Ageing of the microporous titania samples markedly reduces the exchanger capacity of the smaller Ni2+ ions but increases that of the bulkier Cr3+ as a result of the presence of some wide pores that appear upon agglomeration. The presence of Cr3+ ions in the hydroxo form in solution seems to inhibit its exchange with the appropriate surface species. Studies on the kinetics of exchange with respect to the Ni2+ ions seem to indicate that a particle diffusion mechanism is partly or completely responsible for the rate of exchange.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00549874
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Towards the numerical simulation of the horizontal slug front (1992)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 14 (1992), S. 127-146 
    Details
    ISSN: 0271-2091
    Keywords: Numerical simulation ; Slug flow ; Turbulence ; Dissipation ; Open surface ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Steps towards the numerical simulation of the flow behind the slug front in horizontal slug flow performed with a streamfunction-vorticity representation of the mean flow and an energy dissipation model for the turbulence are discussed. The flow field consists of two vortices, one saddle point and four stagnation regions. Attention is focused on the following boundary conditions: moving wall jet, moving wall, free jet velocity discontinuity and vertical liquid-gas open surface. A dissipation flux boundary condition is suggested to simulate the interaction of the turbulent eddies with the open surface. A method to assess the necessity to use a transport model equation for the dissipation rather than a geometric specification of a length is suggested. Three different ways to characterize the mixing zone length are proposed.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650140202
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  • 3
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    Surface and related studies in sulphated oxides of zirconium (2004)
    Springer
    Details
    Publication Date: 2004-02-01
    Print ISSN: 0022-2461
    Electronic ISSN: 1573-4803
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Springer
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  • 4
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    Mutation in PHC1 implicates chromatin remodeling in primary microcephaly pathogenesis (2013)
    Oxford University Press
    Details
    Publication Date: 2013-05-14
    Description: Primary microcephaly (PM) is a developmental disorder of early neuroprogenitors that results in reduction of the brain mass, particularly the cortex. To gain fresh insight into the pathogenesis of PM, we describe a consanguineous family with a novel genetic variant responsible for the disease. We performed autozygosity mapping followed by exome sequencing to detect the causal genetic variant. Several functional assays in cells expressing the wild-type or mutant gene were performed to understand the pathogenesis of the identified mutation. We identify a novel mutation in PHC1 , a human orthologue of the Drosophila polyhomeotic member of polycomb group (PcG), which significantly decreases PHC1 protein expression, increases Geminin protein level and markedly abolishes the capacity to ubiquitinate histone H2A in patient cells. PHC1 depletion in control cells similarly enhances Geminin expression and decreases histone H2A ubiquitination. The ubiquitination defect and accumulation of Geminin with consequent defect in cell cycle are rescued by over-expression of PHC1 in patient cells. Although patients with the PHC1 mutation exhibit PM with no overt progression of the disease, patient cells also show aberrant DNA damage repair, which is rescued by PHC1 overexpression. These findings reveal several cellular defects in cells carrying the PHC1 mutation and highlight the role of chromatin remodeling in the pathogenesis of PM.
    Print ISSN: 0964-6906
    Electronic ISSN: 1460-2083
    Topics: Biology , Medicine
    Published by Oxford University Press
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  • 5
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    Hydrous oxides of titanium: cation exchange properties and kinetics of exchange (1991)
    Springer
    Details
    Publication Date: 1991-01-31
    Print ISSN: 0022-2461
    Electronic ISSN: 1573-4803
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Springer
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