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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Transition metal chemistry 25 (2000), S. 260-264 
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of H2O2 decomposition have been investigated using ZrO2 supported with transition metal ions including CuII, AgI, HgII, CoII, MnII, NiII and FeIII. At pH = 6.8, the reaction rate exhibits a first order dependence on the initial H2O2 concentration at low concentrations. The order of activity of the different catalysts is strongly dependent on the [H2O2]0 used. The reaction proceed via the formation of the peroxo-intermediate which has an inhibiting effect on the reaction rate. The rate increases with increasing pH, and attains a limiting rate at higher pH's. A reaction mechanism is proposed involving liberation of HO2 radicals from the peroxo-intermediate as the rate-determining step.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 131 (2000), S. 1139-1150 
    ISSN: 1434-4475
    Keywords: Keywords. Hydrogen peroxide; Zinc oxide; Transition metal ions; Decomposition; Kinetics; Catalysts.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary.  Transition metal sulfates of Cu(II), Co(II), Ni(II), Cr(III), Mn(II), and Fe(III) supported on ZnO were prepared and characterized by SEM, EDX, and XRD. The kinetics of the heterogeneous decomposition of H2O2 over these supported catalysts was investigated. The reaction rate is correlated with both the amount of supported metal ion and its redox potential. The rate of reaction increases with increasing initial concentration of H2O2, attains a maximum, and decreases thereafter. It also increases with pH and reaches a maximum at high pH values. A reaction mechanism is proposed that implies the formation of a peroxo intermediate at the early stages of the reaction. A second intermediate is assumed to be formed at high [H2O2]o which inhibits the progress of the reaction.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Aquaculture international 8 (2000), S. 9-18 
    ISSN: 1573-143X
    Keywords: Asian catfish (Clarias batrachus) ; Biotin requirement ; Biotin deficiency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Asian catfish, Clarias batrachus, were fed semi-purified basaldiets containing 0, 0.1, 0.5, 1, 3 and 5 mg biotin kg−1diet for 60 days. Fish fed the control diet (no biotin) showed(P 〈 0.05) higher mortality, lower weight gain, specificgrowth rate (SGR), feed efficiency ratio (FER) and protein efficiencyratio (PER) than in fish fed diets supplemented with biotin. The highestweight gain, SGR, FER and PER were noticed in fish fed 1 mg biotinkg−1, followed by 0.5, 5, 3 and 0.1 mg biotinkg−1, except for PER (followed by 0.5, 5, 0.1 and 3 mgbiotin kg−1). Quadratic analysis showed that the optimumdietary biotin requirements for maximal weight gain, PER and PER were2.49, 2.54 and 2.52 mg kg−1, respectively. Liver biotinconcentrations were influenced by levels of biotin in the diet.Concentration of liver biotin increased as level of dietarysupplementation increased and no biotin was detected in the liver of thecontrol fish. Liver pyruvate carboxylase and acetyl CoA carboxylaseactivities were higher in fish fed biotin-supplemented diets than incontrols. Biotin concentrations, pyruvate carboxylase and acetyl CoAcarboxylase activities in liver associated with normal growth rangedfrom 10.59 to 10.66 μg g−1, 147.97 to 148.18 units mgprotein−1 and 12.76 to 12.78 units mg protein−1, respectively. Biotin deficiency symptoms such as anorexia, darkskin colour and convulsions were observed in fish fed the control diet.The optimum dietary biotin requirement for maximal growth of C.batrachus is about 2.49 mg kg−1 diet.
    Type of Medium: Electronic Resource
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  • 14
    ISSN: 1573-143X
    Keywords: duck-fish culture ; economic analysis ; fish yield ; nutritional parameters ; plankton ; water quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Raising ducks on fish ponds (fish-duck culture) on a commercial scale is a new practice in Egypt, therefore, a study was undertaken to evaluate this practice from production, carcass composition and economic viewpoints. Five earthern ponds were used in the non-integrated system (no ducks) whereas four earthen ponds, in which each pond was supplied with 125 Pecking ducks per 0.42 ha, were used for the Integrated system. In both systems, each pond was stocked with four species of fish (common carp Cyprinus carpio, silver carp Hypophthalmichthys molitrix, Grey mullet Mugil cephalus and tilapias Oreochromis niloticusand O. aureus) at the same densities. There were no differences in temperature or pH in any of the ponds but dissolved oxygen levels were lower in integrated ponds concomitant with increasing levels of ammonia, phosphate and nitrate. Water in integrated ponds was richer in natural productivity (phytoplankton and zooplankton) either in species or density when compared with those variables in non-integrated ponds. Fish species reared in integrated ponds exhibited better body weight, food conversion and protein efficiency ratios compared with those of fish species in the non-integrated ponds. Fish yield per 0.42 ha produced from the integrated ponds was significantly higher than that obtained from non-integrated ones. Also, body composition of fish species was affected by the type of farming. Carcass crude protein of grey mullet, silver carp and tilapia was improved in the integrated system. The data on return on sales, return on costs, return on equity, pay-back period and break-even point showed that the integrated system was more profitable than the non-integrated system.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Economic change & restructuring 33 (2000), S. 171-184 
    ISSN: 1574-0277
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract In this paper I investigate the impact of overnight floating of the official rate and easing foreign exchange restrictions on post-unification domestic inflation rate. After analysing the behaviour of an economy under dual foreign exchange markets, an official market with a crawling foreign exchange rate and a free illegal parallel market. The paper also shows that maintaining a unified free exchange rate depends on the degree of foreign exchange restrictions under dual foreign exchange system and on the level of the official reserve that prompts foreign exchange liberalisation policy.
    Type of Medium: Electronic Resource
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