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  • Electronic Resource  (13)
  • Chemistry  (9)
  • Soil acidity  (2)
  • Zinc  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 17 (1988), S. 251-266 
    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
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 17 (1988), S. 267-283 
    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
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  • 3
    ISSN: 1573-5036
    Keywords: Acetylen reduction assay ; Aluminium toxicity ; Chemical composition ; Cowpea ; Cultivar tolerance to soil acidity ; Liming ; Nitrogen deficiency ; Nitrogenase activity ; Nodulation ; Relative dry matter yields ; Soil acidity ; Ultisol ; Lime-induced yield depression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The differential response of six cowpea (Vigna unguiculata (L.) Walp) cultivars to liming was assessed in a greenhouse trial using an Ultisol (Typic Paleudult) from southeastern Nigeria. Lime rates from 0 to 5.0 t/ha were applied to give a range of soil pH, determined in 1∶1 soil/water from 4.25 to about 7.0. Without liming, relative dry matter yields of tops ranged between 46.6 and 76.8 percent. Significant yield responses to the first lime increment (0.5 t/ha) were observed particularly in the less tolerant cultivars and maximum yields were generally obtained with application of 1.6 to 2.5 t/ha lime. Among the six cultivars, TVu 4557 and Ife Brown were most tolerant, Vita-1 and Vita-3 were moderately tolerant, and TVu 1977-OD and TVu 4552 were least tolerant to soil acidity. The latter two cultivars were the most poorly nodulated when grown in the unlimed soil. The first lime increment enabled excellent nodulation to be achieved in all cultivars. Nitrogen analyses on tops confirmed the visual symptoms of nitrogen deficiency in two cultivars (Vita-1, TVu 1977-OD) grown in the unlimed soil. Analysis of data on chemical composition of plant tops and chemical soil characteristics gave indications that aluminium toxicity is the major growth limiting factor for cowpeas in this soil. This study, albeit with a limited range of cowpea germplasm clearly indicates that cowpea possesses considerable potential as a grain legume on strongly acid soils (pH〈5.0), even in circumstances where lime is not available. Low rates of lime (0.5 t/ha or less) will greatly expand the available choice of cultivars.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 99 (1987), S. 31-37 
    ISSN: 1573-5036
    Keywords: Aluminium ; Hydrogen ; Soil acidity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Reduced productivity due to soil acidity has been demonstrated with subterranean clover and wheat in many parts of Australia. Nodulation in clover appears to be more sensitive to low pH than growth of the host plant in the presence of adequate mineral nitrogen. Low pH is associated with aluminium toxicity in a number of species and nodulation in clover is more sensitive than growth of the host plant to Al. Decrease in soil pH is associated with significant increases in exchangeable Al. The breeding of Al tolerant wheats in Australia involves a backcross programme utilizing the transfer of tolerance from the Brazilian cultivar Carazinho.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 27 (1997), S. 507-516 
    ISSN: 0887-3585
    Keywords: insulin ; despentapeptide ; structure ; fibrillation ; x-ray crystallography ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The crystal structure of despentapeptide insulin, a monomeric insulin, has been refined at 1.3 Å spacing and subsequently used to predict and model the organization in the insulin fibril. The model makes use of the contacts in the densely packed despentapeptide insulin crystal, and takes into account other experimental evidence, including binding studies with Congo red. The dimensions of this model fibril correspond well with those measured experimentally, and the monomer-monomer contacts within the fibril are in accordance with the known physical chemistry of insulin fibrils. Using this model, it may be possible to predict mutations in insulin that might alleviate problems associated with fibril formation during insulin therapy. © 1997 Wiley-Liss Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 2025-2035 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Thomas and Windle's model of Case II transport is analyzed for a semiinfinite medium by a singular perturbation technique. Two adjacent boundary layers separate equilibrated and dry regions. A thin boundary layer of width ∼ O(M-1/2/ln M), where M (≫1) dictates how rapidly the mixture's viscosity decays with liquid concentration, sits next to the equilibrated outer left region. Here, quasi-steady diffusion balances relaxation. A thicker intermediate layer of width ∼ O(M-1/2) separates the lefthand boundary layer and the dry outer region on the right, where both relaxation and unsteady diffusion participate in the transport. Matching the solutions at leading order specifies the moving front's speed, v: v ∼ M1/2. The analysis indicates that relaxation significantly affects the nearly dry region just ahead of the moving front. This disagrees with the widely accepted view that ordinary diffusion dominates in the nearly dry righthand region. Approximating that ordinary diffusion dominates in this region leads to a stepexponential concentration profile at the front and a simple analytical solution for the front speed, v with the correct M scaling. This approximate result accurately predicts the values of v determined by direct numerical solutions.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 3 (1980), S. 190-192 
    ISSN: 0935-6304
    Keywords: HPLC ; Routine quantitation of MDI at toxic levels ; Free MDI in prepolymers ; Minimum sample preparation ; Quick ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 161-163 
    ISSN: 0935-6304
    Keywords: Liquid chromatography ; Extraction of fatty acid amides ; Determination of slip agents in packaging films ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 11 (1965), S. 1073-1081 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An analytical and experimental study was made of the evaporation from pure and saline water films flowing down a heated vertical surface at Reynolds numbers between 160 and 600. Visual observation showed free surface evaporation. Film continuity was poor for pure water, but good for saline water, because of the influence of temperature and salinity on surface tension gradients. Evaporation rates were predicted by (1) a constant-property boundary-layer type of laminar analysis; (2) the constant-property Dukler “eddy” treatment; and (3) a variable property laminar analysis that took into account the boiling point elevation due to salinity. The experimental evaporation rates could be correlated by dimensionless moduli arising out of the laminar analyses, but best quantitative agreement was found with the Dukler eddy treatment.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 16 (1970), S. 594-601 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Linear perturbation analyses are extended to determine the lowest Rayleigh number at which convection initiates in a vertical cylinder heated on the bottom and cooled on the top. The critical Rayleigh number for the first mode of convection in a right circular cylinder with a perfectly conducting wall is shown to be three times larger than that in such a cell with a perfectly adiabatic side wall. An adjusted wave number is shown to make the results of Pellew and Southwell applicable to the adiabatic wall in a manner similar to that used by Pnueli and Ostrach for the perfectly conducting side wall. The results are compared with experiment and are in very good agreement.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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