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  • 1
    Electronic Resource
    Electronic Resource
    The impact of copper and cobalt orebodies upon the evolution of some plant species from Upper Shaba, Zaïre (1983)
    Springer
    Plant systematics and evolution 142 (1983), S. 207-221 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Caryophyllaceae ; Silene burchelli ; Silene cobalticola ; Cobalt uptake ; cobalt tolerance ; copper uptake ; copper tolerance-‚evolution ; flower morphology ; leaf anatomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The flora of the copper-cobalt ores of Upper Shaba, Zaïre, comprises some 220 taxa including 42 endemics. The origin of this flora is examined and an assessment has been made of its relationship with the flora of the high plateaux steppe-savannah (dilunguan flora). A first group consists of undifferentiated species limited to these two floras. A second group comprises cupriphilous taxa derived from closely-related and widely distributed species observed on the high plateaux and elsewhere. A third group consists of closely-related species or ecotypes confined to the areas. In theSilene burchelli complex (Caryophyllaceae) there is a gradual transition from the widespreadS. burchelli var.angustifolia on the high plateaux to a newly discoveredS. burchelli ecotype from a cupriferous outcrop at Luita, and toS. cobalticola from highly mineralized copper-cobalt deposits at Mindigi. This ecophyletic series provides a gradient of morphological anatomical, and physiological changes whose end members are distinct species. The subject of palaeoendemism and neoendemism in relation to metallophytes of Upper Shaba is also discussed. Colonisation of metalliferous soils by elements of the non-mineralised high plateau is believed to be a neoendemic process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00985899
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  • 2
    Electronic Resource
    Electronic Resource
    Studies on copper and cobalt tolerance in three closely related taxa within the genusSilene L. (Caryophyllaceae) from Zaïre (1983)
    Springer
    Plant and soil 73 (1983), S. 377-385 
    Details
    ISSN: 1573-5036
    Keywords: Silene burchelli ; Silene cobalticola ; Cobalt tolerance ; Cobalt uptake ; Copper tolerance ; Copper uptake ; Ecotype ; Exclusion mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Experiments were carried out on the tolerance to and uptake of copper and cobalt by three members of a phylogenetic series of taxa within the genusSilene from Zaïre which were reputed to represent a progression of increasing adaptation to metalliferous soils. Plants studied were the widespread and presumably non-tolerantSilene burchelli var.angustifolia (B), a more tolerant variant of this taxon (E) designated an ecotype, and the metallophyteS. cobalticola (C). Studies on the effects of both metals, singly and in combination, on seed germination, seedling and plant performance and yield, and metal uptake from soil cultures, confirmed in general the sequence B〈E〈C in relation to tolerance of both copper and cobalt. The experimental evidence also supports the ecotypic status of E and points to E and C being relatively more tolerant to copper than to cobalt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02184314
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  • 3
    Electronic Resource
    Electronic Resource
    Copper and cobalt uptake by metallophytes from Zaïre (1979)
    Springer
    Plant and soil 53 (1979), S. 535-539 
    Details
    ISSN: 1573-5036
    Keywords: Aeolanthus ; Cobalt uptake ; Copper uptake ; Haumaniastrum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Pot trials were carried out on plants ofHaumaniastrum katangense, Haumaniastrum robertii andAeolanthus biformifolius. These metallophytes from Zaïre were grown in substrates containing from 0–10,000 μg/g (0–1%) copper or cobalt. The tolerance of each species was determined and for cobalt was highest inH. robertii (4000 μg/g) and for copper was highest inAeolanthus biformifolius (9000 μg/g). Discontinuities in the plant-soil curves for each element indicate an exclusion mechanism operating for all three species at lower concentrations of the element in the soil. All species would grow in soils containing only traces of cobalt or copper and this indicated that uptake of heavy metals was not linked to a physiological requirement for either element. The plant-soil relationship for cobalt (P〈0.001) was sufficiently good for all three species for them to be useful in biogeochemical prospecting for this element.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02140724
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  • 4
    Electronic Resource
    Electronic Resource
    Characterization of polyester/polycarbonate blends by size exclusion chromatography and melt rheometry (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 59-62 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A major obstacle to the study of polymer blends has been the lack of a convenient technique for measurement of molecular weight. Melt rheometry, while giving useful information related to processing and end-use performance, is incapable of providing detailed information on the individual components. This work describes the use of size exclusion chromatography (SEC) to study the molecular-weight distributions of polycarbonates and aromatic polyesters in blends of the two. SEC of the polycarbonate is achieved in a solvent which dissolves the polycarbonate, but not the polyester, while SEC is performed in a solvent which dissolves both components, but using selective detection. Thus, SEC is used to examine the individual components of the blend, while rheometry can be used to study the blend as a whole. This combination of techniques has been successfully used to analyze the effect of moisture, processing conditions, and recycling on blend properties.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760300109
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  • 5
    Electronic Resource
    Electronic Resource
    Polymer-diluent interactions of some nitrocellulose-nitrate ester systems (1965)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 9 (1965), S. 707-713 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The Flory-Huggins interaction χ and the closely related heat of mixing parameter B were determined for several nitrocellulose-nitrate ester systems. A micromethod which permitted the use of a simplified version of the Flory equation was successful in evaluating the effects of two series of nitrate ester diluents with nitrocellulose. A distinct difference exists between the effect of αω- and α,β-substituted diluents as shown by the χ and B parameters. Generally, the terminally substituted nitrate esters appear to be the better solvents.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1965.070090228
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