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  • Wiley-Blackwell  (74)
  • Geological Society of London
Collection
  • 11
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 20 (1981), S. 523-531 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The interaction of tylophorinidine (TPD) with lysozyme - a model protein - with biological activity, was investigated by determining its fluorescence and by assessing its activity under various conditions. The results indicated that TPD associated with lysozyme at pH 9.2 efficiently with an association constant Ka of 3.3 X 104 M-1 at 26°C. Ka increased with the increasing temperature in the range 26 to 55°C; the calculated enthalpy change ΔH was found to be 2.3 kcal/mol. Under the same conditions as above TPD also associated with the free amino acid tryptophan with a Ka of 1.7 X 104 M-1 indicating half the efficiency of its association with protein lysozyme. TPD associated lysozyme was less active than the uncomplexed enzyme in the above temperature range although beyond 45°C the inhibition was more significant. The results imply that TPD binds lysozyme outside the cleft region in the temperature range studied here. However, with increasing temperature the cleft region is gradually widened and/or the whole molecule is expanded such that the accommodation of whole or part of the TPD molecule is facilitated leading to the blockage of lytic activity.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 63 (1980), S. 1754-1758 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Pathway of the Catalytic Reduction of 6-MethylpterinThe catalytic hydrogenation of 6-methylpterin (I) in neutral or weekly acidic solution begins, as for the 7-methylpterin, by the thermodynamically controlled reduction of the 7,8-double bond. It is not possible to say, according to our experiments, which double bound, either the 5,6 or the 7,8, is first reduced in strongly acidic solution. However, a 5,8-reduction can be excluded.
    Additional Material: 2 Ill.
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  • 13
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 4 (1970), S. 139-147 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In an earlier paper (Bibliography [1]) it has been shown that approximate representations of excited states of atoms can be obtained from the study of the singularities in the dynamic polarizability. Starting with these wave functions a more accurate calculation of the excited states in the Hartree-Fock scheme can be made by a perturbation treatment. The resulting wave functions yield significantly improved energy values. The 21P, 31P and 41P states of the He sequence up to C4+ are studied. The expectation values of a number of operators are calculated. The results obtained by the present method compare favourably with other elaborate calculations.
    Additional Material: 4 Tab.
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  • 14
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 183 (1982), S. 1093-1099 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: N-Vinylcarbazole (NVC) is polymerised in the presence of pyridine at 60°C by using azodiisobutyronitrile (AIBN) and benzoyl peroxide (Bz2O2) as initiators and the results are compared with those obtained when benzene is used as the solvent. In the AIBN-initiated system using pyridine as the solvent the rates of polymerisation follow an usual linear relationship with respect to monomer concentration and a square root dependence with respect to the initiator concentration. In the Bz2O2-initiated system, however, deviations from these ideal behaviours are observed when benzene and pyridine, respectively, are used as the solvent. Initiation occurs through the complexation of the monomer with Bz2O2 and degradative transfer is thought to be mainly responsible for this unusual kinetic behaviour.
    Additional Material: 1 Ill.
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  • 15
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A unified study of the optical and mechanical properties of polyoxymethylene (POM) is attempted in the framework of the composite model for a wide range of temperature (-60 to 120°C) which covers a region well below and above the γ-relaxation temperature. It was found that the existing two phase models for semicrystalline polymers are not adequate for interpreting the mechanical properties of POM over a wide temperature and drawing ratio range. The composite model takes into consideration the effects due to the change in crystallinity and orientation on drawing. The elastic moduli of the composite units are also calculated in terms of those of its constituents. The orientational changes on drawing were directly computed from the birefringence data. It was observed that the general agreement of the calculated and experimental values of the elastic moduli over the entire temperature and drawing ratio range is quite satisfactory.
    Additional Material: 3 Ill.
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  • 16
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 187 (1986), S. 1023-1034 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The theoretical interpretation of the anisotropic elastic properties of polypropylene is given. It was found that none of the existing models provide a unified description of the mechanical and optical properties of ultradrawn polypropylene. The composite model proposed by the authors, which takes into account the change in orientation and crystallinity on drawing, was applied to investigate the elastic moduli data of polypropylene for a wide range of temperature (-40 to 110°C) and over the entire drawing ratio range. The relationship between θ and θ′, the angles made by the C-axis of the composite unit with drawing direction, was found to be adequately described by the relation tan θ = φ(n) tan θ′. It was further observed that φ(n) in the above relation obtained from birefringence data predicts the correct orientational changes on drawing for the temperature range -40 to 24°C. This makes the evaluation of mechanical properties possible without introducing any arbitrary parameter. However, it is noticed that a particular analytical form of φ(n) with two parameters is quite successful in interpreting the mechanical properties data over the entire temperature range. The abrupt changes of the parameters at certain temperatures seem to be correlated with the β-relaxation and glass transition temperature.
    Additional Material: 8 Ill.
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  • 17
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 217-226 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A phenomenological model is proposed which considers the polymer as an aggregate of units. The units are composed of two distinct phases  -  amorphous and crystalline. The thermal conductivity of a unit is calculated in terms of those of its constituents. In the undrawn state these units are distributed randomly, and the isotropic thermal conductivity of the bulk results. The development of strong anisotropy in thermal conductivity is explained in terms of the preferred orientation of these units. The structural features of this model are similar to those employed for the interpretation of the mechanical properties. The change in orientation of the units was deduced from the experimental data of birefringence. Finally, the results obtained from the composite model for several semicrystalline polymers are compared with the experimental data and other existing calculations. The model is found to give a fair overall description of the thermal conductivity in the cases of polypropylene, polyoxymethylene, low and high density polyethylene, and polychlorotrifluoroethylene.
    Additional Material: 4 Ill.
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  • 18
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 19 (1983), S. 1183-1192 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The results of the finite element analysis of 3-ply laminated conical shells with light core for linear panel flutter are presented and certain advantages of such shells discussed.
    Additional Material: 6 Ill.
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  • 19
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 187 (1986), S. 1009-1015 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The existing models of high density polyethylene (HDPE) fail to tackle effectively the development of mechanical anisotropy on drawing at different temperatures. This paper is concerned with the theoretical interpretation of the anisotropic elastic properties of HDPE by applying the composite model proposed by the authors. The model takes into account the change in orientation and crystallinity on drawing. As far as the orientational changes on drawing are concerned, it is seen that the pseudo affine deformation law tan θ = φ(n) · tan θ′ with φ(n) = n-3/2 is applicable at -60°C only. It is further found that the two parameter analytical form of φ(n) reproduces the correct orientational changes on drawing for the entire temperature range from -60 to 100°C. The agreement of the calculated values of E0 and E90 over the entire temperature range at all drawing ratios is quite satisfactory.
    Additional Material: 4 Ill.
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  • 20
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 993-1000 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The thermal expansivity of semicrystalline polymers is interpreted within the framework of the composite model which has already been found useful in describing mechanical and optical properties as well as the thermal conductivity of a large number of polymers. The model assumes the polymers to be an aggregate of units composed of crystalline and amorphous phases. The thermal expansivities of the unit are calculated in terms of those of the constituents. In the undrawn state the units are distributed randomly, and the isotropic thermal expansivity of the bulk results. The development of strong anisotropy in thermal expansivity on drawing is explained in terms of preferred orientation of the units. The orientational changes on drawing have been directly calculated from the birefringence versus draw ratio data. The results of these investigations indicate that the present model is quite successful in interpreting thermal expansivity data for poly(oxymethylene) and poly(propylene) over the entire draw ratio and temperature range.
    Additional Material: 2 Ill.
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