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  • 1
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein Styrol/Maleinsäureanhydrid-Copolymeres (ST-co-MA), hergestellt aus Styrol und Maleinsäureanhydrid in Dimethylsulfoxid mit Azoisobutyronitril als Initiator, wurde durch eine Kondensationsreaktion auf Poly(vinylalkohol) (PVA) gepfropft. Die Strukturen der Produkte wurden mittels IR-Spektroskopie untersucht. Die Abhängigkeit der Pfropfterpolymerzusammensetzung, -viskosität und -ausbeute von der Konzentration der Reaktanden sowie die mechanischen Eigenschen von aus den Pfropfprodukten hergestellten Membranen wurden ermittelt. Bei der Untersuchung der Permeationseigenschaften zeigte sich, daß die Membranen bei allen Zusammensetzungen von Alkohol/Wasser-Gemischen bevorzugt für Wasser durchlässig sind. Mit steigendem PVA-Anteil in den Membranen und wachsendem Ethanolanteil der Alkohol/Wasser-Mischung nimmt die Durchlässigkeit ab und die Selektivität zu. Weiterhin wird der Einfluß der Größe der permeierenden Moleküle auf die Durchlässigkeit und Trenneigenschaften diskutiert.
    Notes: Graft copolymerization of styrene-maleic anhydride copolymer (ST-co-MA) onto poly(vinyl alcohol) (PVA) was carried out by a condensation-coupling reaction through esterification. The ST-co-MA copolymer was obtained by the copolymerization of MA and ST in dimethyl sulfoxide (DMSO), using azoisobutyronitrile as initiator. The structure of the reaction products was confirmed by infrared analysis. The dependence of composition, viscosity and yield of the graft terpolymers on the concentration of the reactants are presented in detail. Mechanical properties of membranes with different compositions were measured over a wide range of composition. It was found that water was permeated through the membranes preferentially in all ranges of feed compositions. The permeation decreased and the selectivity increased with increasing ethanol concentration in the feed and with increasing PVA content in the membrane. The effect of the molecular size of the permeating species on both permeation and separation is also discussed.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2018-06-11
    Description: An algorithm is proposed for the computation of streamfunction and velocity potential from given horizontal velocity vectors based on solving a minimization problem. To guarantee the uniqueness of the solution and computational reliability of the algorithm, a Tikhonov regularization is applied. The solution implies that the obtained streamfunction and velocity potential have minimal magnitude, while the given velocity vectors can be accurately reconstructed from the computed streamfunction and velocity potential. Because the formulation of the minimization problem allows for circumventing the explicit specification of separate boundary conditions on the streamfunction and velocity potential, the algorithm is easily applicable to irregular domains. By using an advanced minimization algorithm with the use of adjoint techniques, the method is computationally efficient and suitable for problems with large dimensions. An example is presented for coastal oceans to illustrate the practical application of the algorithm.
    Keywords: Meteorology and Climatology
    Type: Monthly Weather Review; Volume 134; Issue 11; 3384-3394
    Format: text
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  • 3
    Publication Date: 2019-07-13
    Keywords: Meteorology and Climatology
    Type: World Meteorological Organization, Assimilation of Observations in Oceanography; Mar 13, 1995 - Mar 17, 1995; Tokyo; Japan
    Format: text
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