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  • Chemistry  (10)
  • Chemical Engineering  (2)
  • Oxisol  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 81 (1984), S. 165-176 
    ISSN: 1573-5036
    Keywords: Avocado ; Ca ; Mn ; Oxisol ; P ; pH ; Phytophthora root rot ; Soil water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This experiment employed a factorial design combining 4 soil pH levels, 3 soil moisture levels, with and without the addition ofPhytophthora cinnamomi to the soil to evaluate the conditions that lead to Phytophthora root rot of avocado. An inverse relation between soil pH and leaf production (and root-weight) was observed in nondiseased plants. In soil infested withP. cinnamomi, plant growth and root weights were much depressed by low soil pH, and especially by low soil pH coupled with high soil moisture contents. These interactions were statistically highly significant. Root weights in pots withP. cinnamomi were closely related to the incidence of disease. A disease index was used to visually assess the conditions of roots. Isolation of the pathogen from diseased plant roots confirmed the accuracy of the disease index. A process of elimination suggsts that favorable soil Ca level and not high pHper se was responsible for disease suppression and that the devastating effects of low soil pH was produced by high Mn (and possibly Al) and associated low levels of Ca and P in soil solutions, which led to breakdown of biological control mechanisms.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 16 (1988), S. 3-13 
    ISSN: 1573-0867
    Keywords: dicalcium orthosilicate ; calcium metasilicate ; mini-granulation ; extractable Si ; Si in saturation extract ; Oxisol ; Andept
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Silicate materials, dicalcium orthosilicate (Ca2SiO4), calcium metasilicate (CaSiO3), and mini-granulated CaSiO3, were incorporated into three highly weathered, low-Si soils. The mixtures were moistened to field moisture-holding capacity and incubated in plastic bags for 60 days at approximately 25°C, after which Si was extracted. Application rates of silicate materials were 0, 460, 920, and 1380 mg Si per kg soil. Two ranges of particles sizes, 0.25 to 0.84 mm and 0.074 to 0.15 mm CaSiO3 and Ca2SiO4 were compared. The soils were a Typic Gibbsiorthox, pH 4.6; a Humoxic Tropohumult, pH 4.2; and a Typic Hydrandept, pH 5.0. Materials were evaluated by four extraction procedures: shaking in water, water displacement from saturated soil, shaking in ammonium acetate solution, and biologically by roots of sugarcane (Saccharum Spp. hybrid). Silicate from the CaSiO3 materials were generally more readily extracted chemically and biologically than silicate from the Ca2SiO4. Solubility and availability of Si usually increased as primary particle size of the silicate materials decreased. The exceptions were associated with the most acid (pH 4.2) Ultisol. Mini-granulation did not reduce the effectiveness of CaSiO3 thus confirming agronomic feasibility of mini-granulation. Plant uptake of Si was most closely related to water-extractable soil Si, followed by Si in saturation extracts and then by NH4 OAc-extractable Si.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 41 (1990), S. 1281-1298 
    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: Morphology, stress-strain properties, and grafting have been investigated in highly phase-separated polyurethane (PU)-poly(n-butyl methacrylate) (PBMA) mixtures as a function of the sequence of formation of the components, both linear (l) and crosslinked (x), in the presence of each other. In the range of 0.3-0.7 weight fraction of PU, a morphology of PBMA particles in a PU matrix results. Particle size depends on matrix viscosity at the time of PBMA formation, decreasing as viscosity increases. The PBMA (l) particles are spherical; PBMA (x) particles are irregular in shape when formed in a fluid medium but tend to become spherical as the delay time before the onset of their formation is increased. Grafting, decreasing with increasing delay time, is observed between PBMA (l) particles and the PU (x) or PU (l) matrix. The grafting results from transesterification between BMA and the polyol precursors to the PU. Two families of mechanical properties are found, depending generally more on particle shape than size. Systematic trends of property values through a series of samples of constant composition, but increasing delay times, are observed with greater variation in the series with PBMA (x) particles; the trends are explainable in terms of matrix immobilization by the particles.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 25 (1985), S. 157-163 
    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: Dynamic mechanical properties have been investigated for interpenetrating-network systems based on polyol-cured polyurethanes (PU) and 2 to 1 n-butyl acrylate-n-butyl methacrylate (Ac) networks. The systems were formed simultaneously (SIN) from all of the precursors and reactants for both networks in the same vessel, and sequentially (SIPN) by swelling a precured PU with the reactants that will form the Ac network. If the Ac network is formed after gelation of the PU, the IPNs are transparent and appear to have single T (tan δmax) between those of the homonetworks; visible-phase separation occurs if the Ac is intentionally polymerized prior to PU gelation. Damping curves were lower and broader and the T (tan δmax) and rubber moduli were higher for the SIN than for the SIPN systems. Up to 65 percent Ac, the T (tan δmax) data for both SIN and SIPN fit the Gordon-Taylor equation if a T (tan δmax) for the Ac homonetwork 7°C higher than observed is used, suggesting a higher crosslink density for the Ac network under these conditions. The differences in properties of the SIN and SIPN are assumed to be dependent on sample homogeneity and upon the presence of a tin catalyst in the SIN preparation. This can result in limited Ac-network formation and consequent phase separation before PU gelation has occurred, and the catalyst may also increase the extent of interaction, such as grafting or hydrogen-bond formation between the networks.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 11 (1967), S. 2373-2379 
    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: Poly(methyl methacrylate) has been photolyzed with 2537 A. radiation in dioxane and in methylene chloride at about 25°C. in the presence and absence of air. In degassed solutions, quantum yields for random scission are only slightly affected by either intensity or polymer concentration. Oxygen is an apparent inhibitor for photodegradation. The inhibiting and sensitizing effects of a variety of added solutes, including aromatic hydrocarbons, aliphatic dienes, and ketones were investigated; the behavior is similar whether or not oxygen is present. The results are best explained on the basis of an electronic energy transfer mechanism involving the lowest excited triplet levels of the polymer and the added solutes.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 1011-1023 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Penicillium chrysogenum strain P1 was grown on complex media in 10 and 100 L agitated fermenters at various aeration rates and stirrer speeds. Samples were removed at intervals for measurements of the culture morphology. At high stirrer speeds (1000 and 1200 rpm) in 10-L fermentations the rate of decrease in the mean effective hyphal length was faster and the rate of penicillin production was lower than fermentations done at 800 rpm. At similar power inputs per unit volume in 100-L fermentations, the change in mean effective hyphal length was less and higher penicillin production rates were observed. This work comparing the results at two scales has shown that neither of the concepts of impeller tip speed or the dissipation rate of turbulence have general validity as a measure of hyphal damage. Our results are reasonaby well correlated by groups similar to circulation rate (NDi3/V) with lower circulation rates being beneficial. An adaptation of the van Suijdam and Metz relationship, expressed as P/Di3tc, was most successful. Our data are insufficient to demonstrate the generality of the relationship but do support the concept of a dispersion zone around the impellers in which mycelia may be damaged. The greater the frequency of circulation of mycelia through the zone the greater the damage and the lower the rate of penicillin synthesis by the culture.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 7
    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: Poly(methylene disulfide), poly(methylene tetrasulfide), poly(ethylene disulfide), and poly(ethylene tetrasulfide) have been subjected to ultraviolet radiation in vacuum at 50°C. Weight losses during photolysis include both low molecular weight compounds and readily condensable polymeric materials; the latter account for the greater proportion of the weight losses. Carbon monosulfide, isolated as its polymer, and hydrogen sulfide are major photolytic products. Carbon disulfide is a major product from the methylene but not from the ethylene polymers. The tetrasulfide polymers during irradiation from volatile products which on condensation give the original polymer. A mechanism of degradation compatible with these findings is suggested.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 31 (1985), S. 992-998 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In this work dispersive mixing and chemical reactions are treated simultaneously by resorting to the theory of stochastic processes. A fluidized-bed reactor is modeled by discretizing it into ideally stirred tanks of various sizes corresponding to bubble, cloud, and emulsion phases. All parameters in the model are correlated with known or experimentally obtainable quantities. Examples using a complex chemical reaction are given to demonstrate the applicability of the approach.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 56 (1962), S. 507-517 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The photodegradation of thin films of poly-α-methylstyrene by near ultraviolet radiation has been studied in vacuum at 27 and 115°C. Changes taking place during photolysis were followed by a determination of monomer formation by ultraviolet spectroscopy, residue molecular weight through a measurement of intrinsic viscosity, and volatile products by mass spectroscopy. Gross features of the photolysis include random chain scission in the polymer with subsequent depolymerization of the radicals formed to yield small amounts of monomer; the kinetic chain length is on the order of 15 in the temperature range studied. Quantum yields at 27°C. for chain scission and monomer formation are 1 × 10-3 and 7 × 10-3, respectively. At 115°C. the quantum yields are 2 × 10-2 and 0.5. Small quantities of hydrogen, CO2, CO, and a number of hydrocarbons were liberated during irradiation. An approximate one-to-one correlation between the number of main chain scissions and CO2 + CO molecules evolved was found, suggesting the occurrence of chain scission at weak linkages involving oxygen.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Letters 4 (1966), S. 771-774 
    ISSN: 0449-2986
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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