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  • 1
    Electronic Resource
    Electronic Resource
    Observation of vacancy type defects in Ga-doped ZnSe using a monoenergetic positron beam (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 59 (1991), S. 1482-1484 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We studied vacancy type defects in Ga-doped ZnSe films grown by molecular beam epitaxy using an energy-variable monoenergetic positron beam. We found that the concentration of negative charged vacancies, such as Zn vacancies, increases as the Ga atom concentration increases. This result indicates that the doping by Ga atoms induces the formation of Zn vacancies in a ZnSe film. We believe that these defects will cause the saturation of active carriers in n-type ZnSe films.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.105294
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Production of Metallogenium-like particles by heterotrophic manganese-oxidizing bacteria collected from a lake (1992)
    Springer
    Archives of microbiology 158 (1992), S. 100-106 
    Details
    ISSN: 1432-072X
    Keywords: Metallogenium ; Manganese-oxidizing bacteria ; pH dependence ; Bicarbonate ; Electron acceptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract As a model of chemically stratified structure of environment typical to the chemocline of lakes, a semisolid gradient medium was prepared to cultivate heterotrophic manganese-oxidizing bacteria originally collected from a lake. The bacteria growing under the conditions described produced extracellularly Metallogenium-like particles similar to those which are often detected in the chemocline of lakes. This suggested that the naturally occurring Metallogenium-like particles originated in activities of such heterotrophic manganese-oxidizing bacteria. The manganese oxidation activity usually appeared only at the stationary phase of bacterial growth. The oxidation of Mn2+ and the formation of Metallogenium-like particles by the bacteria were observed at neutral or slightly acidic pH. not under alkaline conditions, which is a conspicuous difference from the inorganic oxidation of Mn2+ by O2. Bacterial manganese oxidation was stimulated by bicarbonate (50 or 500 μM). An experiment of addition of H2O2 to the incubation tubes isolated from atmosphere failed to confirm the availability of externally added H2O2 as the electron acceptor, suggesting that the bacterial manganese oxidation required the presence of O2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00245212
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  • 3
    Electronic Resource
    Electronic Resource
    Evaluation of the Donnan model for polyelectrolytes using the composite Poisson-Boltzmann equations (1994)
    Springer
    Colloid & polymer science 272 (1994), S. 803-811 
    Details
    ISSN: 1435-1536
    Keywords: Donnan model ; Donnan potential ; polyelectrolyte ; counterion binding ; potential distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The validity of the macroscopic Donnan model for polyelectrolytes in an electrolyte solution is examined by taking into account the effects of the varying potential distribution across the boundary between a polyelectrolyte and the surrounding solution, using the composite Poisson-Boltzmann equations for the polyelectrolyte interior and the surrounding solution. Calculations are made for a planar polyelectrolyte of thickness 2d and a planar polyelectrolyte layer of thicknessd covering a rigid surface, both showing the identical potential distribution. A simple expression for a correction factor for these effects is derived which enables to evaluate various corrected quantities in the polyelectrolyte interior such as the average potential, the average ionic concentration, the average degree of dissociation and the apparent dissociation constant of ionizable groups in the polyelectrolyte. It is found that when κd≪1 (where κ indicates the Debye-Hückel parameter) the macroscopic Donnan model can safely be applied, while as κd decreases the effects of the varying potential distribution become appreciable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00652421
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