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  • 1
    ISSN: 1432-2234
    Keywords: Optical activity ; Chirality functions ; Phosphanes and phos-phinoxides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die molaren Drehungen von 7 Horner-Phosphanen und 16 Phosphinoxiden werden als experimentelle Basis für einen Test approximativer Chiralitätsfunktionen verwendet. Unter Zugrundelegung der Gerüstsymmetrie C3v für diese Verbindungsklasse stellen Zweiligandenfunktionen eine gute Näherung dar; eine Approximation unter Verwendung ligandenspezifischer Zahlen führt nur bei einigen Beispielen zum Erfolg.
    Notes: Abstract Seven optically active phosphanes and sixteen phosphin-oxides are used to test approximative chirality functions experimentally. Based onC 3v -symmetry of the molecular skeleton two-ligand-functions yield a good approximation for the experimental data. Ligand-specific parameters can only be gained from a few compounds.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Numerical algorithms 19 (1998), S. 1-12 
    ISSN: 1572-9265
    Keywords: Lagrange's equations of motion ; viscoelasticity ; semi-explicit methods ; 92C10
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract In this paper a mathematical model is developed for the dynamical behaviour of a hydrostatic skeleton. The basic configuration is taken from the worm-like shape of the medicinal leech. It consists of a sequence of hexahedra with damped elastic springs as edges to model the various parts of the musculature. The system is stabilized by the constraint of constant volume either in the whole body or in prescribed compartments. We set up Lagrange's equations of motion with the Lagrange multipliers being the pressure values in the compartments. The equations of motion lead to a large differential-algebraic system which is solved by an application of semi-explicit numerical methods. Though the model has not yet been adapted to experimental data, first simulations with a simplified set of parameters show that it is capable of generating basic movements of the leech such as crawling and swimming.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0570-0833
    Keywords: Chirality functions ; Optical activity ; Methane derivatives ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The optical activity can provide detailed information about the configuration and conformation of methane derivatives if the chirality function is resolved, according to the theory of chirality functions[3] and the quantum mechanical theory of the optical activity of methane derivatives[4], into its components which are compared with experimental data. A first step in this direction is undertaken in the present article and it will be shown that the second approximation method for determining the conformationally independent contribution to the optical activity yields quantitatively good results. Description of the overall optical rotation by this component is expectedly poor where interactions between ligands, e. g. hydrogen bonding, tend to favor specific conformations. A quantitative understanding of such additional effects appears promising in conjunction with analyses of the kind described.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
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