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  • 1
    Electronic Resource
    Electronic Resource
    Thermoplastic matrix controlled-release zinc fertilizers (1988)
    Springer
    Nutrient cycling in agroecosystems 17 (1988), S. 235-250 
    Details
    ISSN: 1573-0867
    Keywords: Zinc fertilizer ; controlled-release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Thermoplastic matrix controlled-release (C.R.) zinc fertilizers are produced by extruding a mixture of zinc salt and inert polymer material. Three methods of laboratory evaluation were used to characterize a range of C.R. zinc formulations differing in concentration and nature of zinc salt, carrier matrix, and size. The methods were (i) electron microscopy, (ii) zinc emission into water, and (iii) zinc diffusion in indicator-agar. These methods complemented each other, with electron microscopy elucidating physical features governing zinc release from the fertilizer pellets. Finely divided particles of soluble zinc salt, for instance, were associated with formulations whose release characteristics approached theoretical (time)0.5 -order release kinetics. Apart from zinc particle size, other factors controlling zinc emission characteristics were the type of zinc salt, the zinc loading, and pellet size. Varying the polymer matrix materials had little or no effect on zinc release from the C.R. zinc formulations compared in this study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01049580
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Thermoplastic matrix controlled-release zinc fertilizers (1988)
    Springer
    Nutrient cycling in agroecosystems 17 (1988), S. 251-266 
    Details
    ISSN: 1573-0867
    Keywords: Zinc ; controlled-release ; diffusion ; pH ; temperature ; phosphate ; clay ; sand ; moisture content
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The emission and movement of zinc from planar arrangements of controlled-release (C.R.) thermoplastic matrix zinc fertilizer formulations was studied in cylindrical diffusion cells packed with a clay or a sand. The influences of a number of soil characteristics known to affect zinc diffusion were also investigated. Zinc emission was initially (over 2 days) very rapid. The rate declined markedly thereafter. Morphologically distinct C.R. zinc formulations released zinc at different rates. Zinc moved appreciably and consistently further in the sand than in the clay. Of the soil characteristics studied, increasing phosphate levels had no effect upon zinc emission or mobility in either soil. Increasing pH in the sand did not affect zinc emission, but decreased zinc mobility. Conversely, in the two soils, increasing temperature stimulated zinc emission, but had little influence on zinc mobility. At higher water contents, zinc release was increased in both soils. However, zinc movement was only increased in the sand.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01049581
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Thermoplastic matrix controlled-release zinc fertilizers (1988)
    Springer
    Nutrient cycling in agroecosystems 17 (1988), S. 267-283 
    Details
    ISSN: 1573-0867
    Keywords: Zinc ; controlled-release ; linseed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Thermoplastic matrix controlled-release (C.R.) zinc fertilizers were compared as zinc sources for linseed (Linum usitatissimum) grown on a zinc-deficient sand and a zinc-deficient clay. C.R. formulations differed in characteristics including origin (different extruders), type of zinc salt, and polymer matrix blends. Conventional fertilization with pure zinc salts was also included in the comparison. C.R. formulations based on zinc oxide (ZnO) were ineffective zinc sources, linseed growth and tissue zinc concentrations being similar to untreated controls. However, both zinc sulphate (ZnSO4·H2O)- and zinc chloride (ZnCl2)-based formulations were effective zinc fertilizers. A group of ZnSO4·H2O-based formulations produced in Melbourne (Australia) gave relatively higher plant zinc concentrations than similar formulations produced on a different extruder in Akron (U.S.A.). Varying the type of plastic or the blend of plastics constituting the matrices of the C.R. products had no consistent effects on tissue zinc concentrations or plant growth. Similarly, no specific benefit of C.R. over conventional zinc fertilization was established under the conditions of the present experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01049582
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The mutagenic potential of high flash aromatic naphtha (1989)
    Springer
    Cell biology and toxicology 5 (1989), S. 169-188 
    Details
    ISSN: 1573-6822
    Keywords: C9 Aromatic Hydrocarbons ; Ethyltoluene ; Genetic Toxicity ; High Flash Aromatic Naphtha ; Mutagenesis ; Trimethylbenzene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Catalytic reforming is a refining process that converts naphthenes to aromatics by dehydrogenation to make higher octane gasoline blending components. A portion of this wide boiling range hydrocarbon stream can be separated by distillation and used for other purposes. One such application is a mixture of predominantly 9-carbon aromatic molecules (C9 aromatics, primarily isomers of ethyltoluene and trimethylbenzene), which is removed and used as a solvent — high-flash aromatic naphtha. A program was initiated to assess the toxicological properties of high-flash aromatic naphtha since there may be human exposure through inhalation or external body contact. The current study was conducted partly to assess the potential for mutagenic activity and also to assist in an assessment of carcinogenic potential. The specific tests utilized included the Salmonella/mammalian microsome mutagenicity assay, the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) forward mutation assay in CHO cells, in vitro chromosome aberration and sister chromatid exchange (SCE) assays in CHO cells, and an in vivo chromosome aberration assay in rat bone marrow. There was no evidence that high-flash aromatic naphtha was either a gene or chromosomal mutagen. Thus it is unlikely to be a genotoxic carcinogen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00122651
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    Paper (German National Licenses)
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