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  • reactive oligomer  (2)
  • Biochemistry  (1)
  • Mineralisation  (1)
  • 1990-1994  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Variations in the rates of nitrification and denitrification during the growth of potatoes (Solanum tuberosum L.) in soil with different carbon inputs and the effect of these inputs on soil nitrogen and plant yield (1991)
    Springer
    Biology and fertility of soils 11 (1991), S. 157-162 
    Details
    ISSN: 1432-0789
    Keywords: Carbon ; Denitrification ; Immobilisation ; Mineralisation ; Nitrification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A potato crop (Solanum tuberosum L. cv. Maris piper) was grown in a soil to which N was added, as NH4NO3, with or without added C, as sucrose or straw. Shortly after amendment the soil, in all treatments, contained only relatively low levels of mineral N. However, these levels increased later. The increase, which was greatest in the absence of added C and least with added sucrose, occurred before the emergence of the plant canopy. The addition of C to the soil had no effect on plant yield, measured either as dry matter or total N content. The potential nitrification rate was high early in the season, and decreased significantly as the plants developed. The potential denitrification rate showed two significant peaks in activity, possibly related to plant development, the first to the development of new roots and the second to root senescence. It seems probable that the amount of C released by the potato plants was only about one-quarter of that required for the maximum microbial activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336382
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis and calorimetric curing study of amino-terminated PEEK oligomers (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 845-849 
    Details
    ISSN: 0887-624X
    Keywords: PEEK ; reactive oligomer ; crosslinking ; differential scanning calorimetry ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Amino-terminated polyetheretherketone (PEEK) oligomers were prepared by the condensation of 4,4′-difluorobenzophenone and hydroquinone in the presence of a calculated excess of m-aminophenol endblocker. The molecular weight of the oligomer was controlled by the manipulation of the ratio of difluoride to hydroquinone with the appropriate stoichiometric amount of m-aminophenol ensuring amino termination. The thermally induced self-crosslinking of these oligomers was studied by differential scanning calorimetry (DSC). Curing was found to be quite slow, taking up to 1 h to reach completion at 668 K. Cured materials were all completely amorphous in contrast to the semi-crystalline starting material. The limiting Tg reached on curing was found to be proportional to the percentage of reactive terminal groups, as would be expected.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080300515
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  • 3
    Electronic Resource
    Electronic Resource
    Thermosetting polyethersulphone oligomers (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 33 (1994), S. 321-327 
    Details
    ISSN: 0959-8103
    Keywords: polyethersulphone ; reactive oligomer ; thermosetting resin ; 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: Routes to thermosetting polyethersulphones (PES) by endcapping an hydroxy terminated oligomer with thermally reactive propargyl, vinylbenzyl and cyanate groups were investigated. Model compounds were prepared to establish suitable routes to the reactive oligomers. DSC was used to study curing behaviour of oligomers and model compounds.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pi.1994.210330312
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  • 4
    Electronic Resource
    Electronic Resource
    Gaussian multipoles in practice: Electrostatic energies for intermolecular potentials (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 15 (1994), S. 1187-1198 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A method is presented for calculating the total electrostatic interaction energies between molecules from ab initio monomer wave functions. This approach differs from existing methods, such as Stone's distributed multipole analysis (DMA), in including the short-range penetration energy as well as the long-range multipolar energy. The monomer charge densities are expressed as distributed series of atom-centered functions which we call Gaussian multipoles; these are analogous to the distributed point multipoles used in DMA. Our procedure has been encoded in the GMUL program. Calculations have been performed on the formamide/formaldehyde complex, a model system for N—H … O hydrogen bonding in biological molecules, and also on guanidinium/benzene, modeling amino/aromatic interactions in proteins. We find that the penetration energy can be significant, especially in its contribution to the variation of the electrostatic energy with interaction geometry. A hybrid method, which uses Gaussian multipoles for short-range atom pair interactions and point multipoles for long-range ones, allows the electrostatic energies, including penetration, to be calculated at a much reduced cost. We also note that the penetration energy may provide the best route to an atom-atom anisotropic model for the exchange-repulsion energy in intermolecular potentials. © 1994 by John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540151102
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