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  • 1
    Electronic Resource
    Electronic Resource
    Lysimeter studies on recovery of15N-labeled urea in wetland rice (1982)
    Springer
    Plant and soil 66 (1982), S. 57-67 
    Details
    ISSN: 1573-5036
    Keywords: Ammonia volatilization ; Denitrification ; 15N-labelled urea ; N utilization ; Residual effect ; Wetland rice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Results of a two year study on the fate on15N-labelled urea (9.95 atoms percent excess15N) applied @ 180 kg N/ha to flooded rice in monolith lysimeters at the Punjab Agricultural University Farm, Ludhiana are reported. The soil of the experimental field was sandy clay loam in texture (Typic Ustochrept), had pH 7.9, organic carbon 0.36 percent, available N 187 kg/ha and total N 0.08 percent. The results revealed that 18.1 to 53.0 per cent of the fertilizer N was utilized by the rice plant, 25.1 to 41.1 percent was immobilized in the soil and 4.8 to 7.2 percent was lost by denitrification. The losses due to ammonia volatilization and leaching were negligible. The data on vertical distribution of labelled N in the soil profile reflected a higher concentration (38.3 to 39.5 per cent) in the surface (0–30 cm) soil. The content sharply decreased (1.8 to 2.4, percent) in lower soil layers (30–150 cm). A balance sheet of the various pathways of applied N showed that 58.8 to 72.2 and 66.2 to 83.0 percent N was recovered in 1976 and 1977, respectively and 17 to 41.2 per cent of labelled N still remained unaccounted for. Utilization of fertilizer N by rice was increased and losses decreased when N was applied in three equal splits as compared to the single N application at transplanting. Availability of fertilizer N immobilized in the soil was investigated in the succeeding crops of wheat and rice. The results showed that 2.1 tot 3.4 per cent of the N applied to the preceding rice was utilized by the second rice crop grown in succession. This may look small but cannot be neglected on a long term basis. But there is need to initiate long term studies to investigate the, turnover of residual N and to determine the fate of applied N in varying soil and cropping systems by using improved techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02203403
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  • 2
    Electronic Resource
    Electronic Resource
    Aromatic ionomer membranes: II. Evaluation as separators for advanced alkaline water electrolyzers (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 30 (1985), S. 2837-2846 
    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 sorption and transport properties of newly developed aromatic carboxylate polymers have been investigated in the context of their application as membrane separators for water electrolyzers. Conductance measurements of aromatic carboxylates of various equivalent weights have been performed as a function of current density, temperature, and electrolyte environment. Results have been compared with those for Nafion 117. The sorption results in dilute and concentrated solution show large water and electrolyte uptake for the aromatic carboxylate films. Furthermore, relatively large sodium ion self-diffusion coefficients have been found in both dilute and concentrated solution environments. The results of these measurements are characteristic of microporous films. The de conductance behavior of the aromatic carboxylate ionomers is quite different from that found for nonporous 1150 equivalent weight Nafion membranes. This difference is caused primarily by the microporous structure of the aromatic carboxylates, which results in large membrane specific conductances.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1985.070300710
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  • 3
    Electronic Resource
    Electronic Resource
    AC breakdown of melt-crystallized isotactic polypropylene (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 35 (1988), S. 1459-1472 
    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 effect of polymer morphology on the dielectric breakdown of isotactic polypropylene was investigated under the influence of a ramped ac voltage. Samples were prepared by melt-pressing polypropylene beads into plaques and subsequently quenching or isothermally cyrstallizing these plaques. Some of the quenched samples were annealed at different temperatures to induce further crystallinity. The plaques were then characterized by wide-angle X-ray diffraction, density measurements, and differential scanning calorimetry. The 60 Hz, ac breakdown voltages of the samples were determined at 7°C, 23°C, and 45°C in a specially designed test cell. There was a lack of any significant effect on the ac breakdown strength of isotactic polypropylene of either the overall crystallinity or the crystallite thickness. This result can be understood in light of previous studies relating the electrical breakdown of polymers to morphology. It is postulated that the degree of crystallinity would influence the breakdown characteristics only when the amorphous regions constitute a small fraction of the total volume, that is, at very high crystallinity values - values beyond the range of the present study.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1988.070350605
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  • 4
    Electronic Resource
    Electronic Resource
    Competitive adsorption of water-soluble polymers on attapulgite clay (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 43 (1991), S. 1293-1299 
    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 individual, competitive, and displacement adsorption of polyvinyl alcohol (PVOH), hydroxyethyl cellulose (HEC), and hydroxypropylmethyl cellulose (HPMC) in aqueous solution onto an attapulgite clay has been systematically studied. For the individual adsorption experiments, the amount of polymer adsorbed at equilibrium decreased in the order PVOH, HEC, HPMC. In the competitive adsorption experiments, the adsorption level of each polymer is diminished by the presence of a competing polymeric species. Binary mixtures of a cellulosic polymer (HEC or HPMC) with PVOH result in a substantial reduction in the amount of cellulosic polymer adsorbed. In the displacement adsorption studies, the sequential addition of HEC or HPMC is not able to displace previously adsorbed PVOH molecules to any appreciable extent. However, the addition of PVOH to previously equilibrated HEC/clay or HPMC/clay suspensions results in a large amount of the adsorbed cellulosic polymer being displaced by PVOH, especially under conditions of high surface coverage. These results indicate that PVOH is preferentially adsorbed on the clay surface and the strength of attachment to the surface is greater for PVOH than for either cellulosic polymer.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070430710
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  • 5
    Electronic Resource
    Electronic Resource
    An aromatic amine as a co-curing agent in epoxy-bisimide blends (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 49 (1993), S. 1131-1144 
    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 structural properties of epoxy can be retained and thermal stability improved by blending epoxy with bismaleimide (BMI) and curing them simultaneously. Depending on the curing agent, the overall viscoelastic properties of the cured material can be varied. In the present work, diaminodiphenylmethane and diaminodiphenyl sulfone have been used as curing agents to prepare blends of epoxy and BMI. The blends were characterized by DSC, TG, DMA, and SEM. Results indicate that an excellent interpenetrating network forms in both the cases and that the DDM-cured system gives better thermal stability than that of the DDS-cured system. © 1993 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070490702
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