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  • Polymer and Materials Science  (46)
  • Crystal Structure  (20)
  • 1990-1994  (66)
  • 1
    Digitale Medien
    Digitale Medien
    Thermodynamic cycle-perturbation study of the binding of trifluoroacetyl dipeptide anilide inhibitors with porcine pancreatic elastase (1990)
    New York : Wiley-Blackwell
    Biopolymers 30 (1990), S. 773-780 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The variety of results of crystallographic studies of the serine proteases complexed with isocoumnrin inhibitors presents a challenging problem to modeling methods and molecular energetics. Therefore, the thermodynamic cycle-perturbation technique has been used to study a model system of elastase and two peptidic inhibitors. Using the program AMBER, the technique correctly predicts changes of the binding constants for the trifluoroacetyl dipeptide inhibitors in comparison with available experimental (kinetic and crystallographic) data. However, the absolute values obtained are shown to be sensitive to the specific electrostatic interaction potential parameters used in the simulations. The reader and user are cautioned that thermodynamic cyle-perturbation results may be too optimistic by underestimating the accuracy of free energy values. This is especially a matter of concern for those cases where a direct comparison with experimental values is not possible, viz., (1) the simulation of binding of novel compounds, (2) structurally uncertain binding sites, or (3) structurally different binding modes. With our best 4-31G* ESP (electrostatic potential) charges we were able to reproduce experimentally determined free energy differences (ΔΔA) with an accuracy of about 1.5 kcal/mol. Dynamically induced structural changes in the binding site of elastase, and particularly changes in hydrogen-bond patterns of the binding site, are also reported.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.360300712
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  • 2
    Digitale Medien
    Digitale Medien
    Correlation between microscopic structural parameters and macroscopic flow behaviour of some polymer-surfactant systems suitable for tertiary oil recovery (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 195 (1992), S. 57-77 
    Details
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Einige für den kombinierten Polymer-Tensid-Einsatz in der tertiären Erdölförderung (EOR) diskutierte Substanzen wurden mittels statischer und dynamischer Lichtstreuung charakterisiert und bezüglich ihrer Anwendbarkeit in unterschiedlich salinaren Modellwässern durch rheologische und rheologisch-dynamische Messungen unter-sucht.Als Polymere wurden Xanthan sowie unterschiedlich hydrolysierte Polyacrylamide verwendet, als Tensid ein Ethylenglykolsulfonat. Es ließen sich Korrelationen zwischen mikroskopischen Strukturparametern (z. B. hydrodynamischer Radius, Trägheitsradius, Molekulargewicht, Gestaltparameter der gelösten Polymeren) und makroskopischem Verhalten wie Viskosität aufstellen, welche für den EOR-Einsatz wichtige rheologische Parameter darstellen.Mit ergänzenden Messungen (Oberflächenspannung, zeitabhängiges Viskositätsverhalten) können Aussagen über die Effizienz und Langzeitstabilität eingesetzter Polymer-Tensid-Slugs in unterschiedlich salinaren Lagerstätten gemacht werden.
    Notizen: Some materials, suitable for application in polymer-surfactant flooding used in tertiary oil recovery (EOR), have been characterized by static and dynamic light scattering and studied in respect to their suitability in various model brines by measuring their rheological and dynamic-rheological behaviour. Xanthan and polyacrylamides of different degree of hydrolysis have been used as polymers, an ethylene glycol sulfonate as surfactant.Correlations have been established between microscopic structural parameters (Hydrodynamic radius, radius of gyration, molar mass, shape of the polymers) and the macroscopic behaviour, such as viscosity and elasticity, being important rheological parameters for EOR application. Additional investigations on surface tension and long term viscosity study lead then to a judgement for the efficiency and long term stability of polymer-surfactant slugs in various reservoirs of different salinity.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/apmc.1992.051950104
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  • 3
    Digitale Medien
    Digitale Medien
    Copolymers of ethyl p-vinylbenzenesulfonate for the preparation of polyelectrolytes of reproducible ion content (1993)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 194 (1993), S. 1237-1248 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Ethyl p-vinylbenzenesulfonate (ESS) for which a new synthesis is described has been copolymerized with vinylcarbazole, styrene, p-methylstyrene and p-bromostyrene in N,N-dimethylformamide at 60°C using azoisobutyronitrile as initiator. Copolymer compositions and copolymerization parameters have been evaluated. Q, e-values for ESS are 4,19 and -0,11. Thermal properties of the copolymers have been investigated by differential scanning calorimetry and thermogravimetric analysis. Polyelectrolytes have been prepared either by polymer analogous hydrolysis of the sulfonic acid esters followed by conversion of the free acids into alkali metal salts or by using the alkylating properties of the esters towards tertiary amines or pyridines to form the appropriate sulfonic acid ammonium or pyridinium salts. The latter method offers the opportunity to synthesize polyelectrolytes with a well defined content of chromophores.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1993.021940417
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  • 4
    Digitale Medien
    Digitale Medien
    Polymers with pendant carbazolyl groups, 5Part 4: cf.3.. Photoconductive properties of some carbazole derivatives with electron donor and acceptor groups (1991)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 192 (1991), S. 617-629 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: In this paper photocurrents of N-isopropylcarbazole (NIPC) derivatives in polycarbonate hosts are reported and compared to data for a benzotriazole derivative (BTA). The carbazole moiety was substituted with both electron donor and acceptor substituents and the photoconductivity was measured as a function of concentration, electrical field, and temperature using the time-of-flight (TOF) technique. The observed increase of the effective mobility of charge carriers at low dopant concentrations upon substitution with a moderate electron acceptor is in contrast to literature data for some other materials. We interpret this increase as being due to an increase in the delocalisation radius of the transport state of the substituted carbazole molecule. The field dependence of the effective mobility shows Poole-Frenkel behaviour, which is attributed to polaron formation. Comparison of the effective mobility of the NIPC derivatives with BTA shows that the size of the molecule plays a decisive role for the absolute value of the effective mobility.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1991.021920313
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  • 5
    Digitale Medien
    Digitale Medien
    Synthesis and characterization of dextran radiocontrast carriers, 1. Ether methylamide derivatives (1991)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 192 (1991), S. 2603-2613 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The synthesis of dextran radiocontrast carriers was undertaken to obtain derivatives expected to have slow and controlled biodegradation as well as slow extravascular diffusion features. The results presented here particularly concern derivatives including a methylamide spacer, prepared by condensation of the amine function of the contrast product with carboxymethylated dextran (CMD). The effect of various coupling reagents on the final yields is disucssed. Concerning the macromolecular features, all the synthesized products were characterized by acid-base titration, elemental analysis, flame photometry, spectroscopic determinations and gel-permeation chromatography. GPC showed that the carboxymethylation of dextran leads to some reticulation (doubling the molecular weights), whereas the coupling of CMD with the contrast compound does not alter the molecular weight and the polydispersity index of the products appreciably.
    Zusätzliches Material: 5 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1991.021921107
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  • 6
    Digitale Medien
    Digitale Medien
    A multitechnique surface analytical study of a segmented block copolymer poly(ether-urethane) modified through an H2O radio frequency glow discharge (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 535-545 
    Details
    ISSN: 0887-624X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Recent work in our laboratories has fully characterized the surface region of a segmented poly(ether-urethane) (PEU) extending from the air/polymer interfacial region through bulk depths in the micron range. This characterization utilized energy and angle dependent Electron Spectroscopy for Chemical Analysis (ESCA), Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), and Comprehensive Wettability Profiling (contact angle using a homologous series of liquids) as defined by Zisman. In this study this same multi-analytical-technique approach is used to elucidate changes in these PEU surfaces induced through an H2O Radio Frequency Glow Discharge (RFGD) plasma. This investigation reports both qualitative and quantitative changes due to the modification treatments as well as the permanency of the changes effected on these surfaces through the plasma treatment. From our analyses, the amount of surface residing polyurethane (hard segment) is observed to increase due to a proposed plasma etching mechanism. Further, the addition of oxygen containing functionality is detected at the modified surfaces unique with respect to the unmodified PEU. These surface modifications which show large increases in wettability, are finally observed to be semi-permanent over a time period of 6 months.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pola.1991.080290410
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  • 7
    Digitale Medien
    Digitale Medien
    Hydrogen/liquid vapor radio frequency glow discharge plasma oxidation/hydrolysis of expanded poly(tetrafluoroethylene) (ePTFE) and poly(vinylidene fluoride) (PVDF) surfaces (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 555-570 
    Details
    ISSN: 0887-624X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Modification of fluorine-containing polymers has recently received much attention due to new chemistries allowing for refunctionalization of these materials, especially their surfaces. In this article results are discussed which demonstrate various interesting modifications (including incorporations of —OH and oxygen comprised functionality) to expanded poly(tetrafluoroethylene) (ePTFE) surfaces. This is effected through the use of low damage, radio frequency glow discharge (RFGD) processes. The low damage conditions, which preserve the original pore structure/morphology of these RFGD treated materials, are supported by Scanning Electron Microscopy (SEM) while the resulting atomic and molecular effects are investigated through other surface analytical methodology. All materials reported in this investigation have been subjected to intensive structural analyses utilizing Electron Spectroscopy for Chemical Analysis (ESCA), Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR), and wettability profiles obtained through contact angle measurements using a large series of liquids having varying surface tensions and surface reactive functionality. Through this multitechnique analysis of both expanded PTFE and poly(vinylidene fluoride) (PVDF) treated surfaces, a model is supported which illustrates surfaces possessing both high and low energy regions comprising both oxygen and fluorine functionality in close molecular proximity.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/pola.1991.080290412
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  • 8
    Digitale Medien
    Digitale Medien
    Polyelectrolyte glasses with linear and nonlinear optical properties (1991)
    Weinheim : Wiley-Blackwell
    Advanced Materials 3 (1991), S. 153-156 
    Details
    ISSN: 0935-9648
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/adma.19910030308
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  • 9
    Digitale Medien
    Digitale Medien
    Tetraphenylporphyrins as coupling reagents and corrosion inhibitorsDedicated to Professor Dr. H.-F. Grützmacher on the occasion of his 60th birthday (1992)
    Weinheim : Wiley-Blackwell
    Advanced Materials 4 (1992), S. 496-498 
    Details
    ISSN: 0935-9648
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/adma.19920040709
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  • 10
    Digitale Medien
    Digitale Medien
    Polymeric materials: A review of progress in 1992In a review of this kind it is impossible to do justice to all interesting work published in 1992. The paper is necessarily subjective and colleagues whose work has been omitted due to the incomplete coverage are asked for their understanding. (1993)
    Weinheim : Wiley-Blackwell
    Advanced Materials 5 (1993), S. 254-259 
    Details
    ISSN: 0935-9648
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/adma.19930050404
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