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  • 1975-1979  (27)
  • Polymer and Materials Science  (26)
  • 5-Hydroxyindoleacetic acid  (1)
  • 1
    Digitale Medien
    Digitale Medien
    Cerebrospinal fluid cyclic AMP and acid monoamine metabolites following probenecid: Studies in psychiatric patients (1979)
    Springer
    Psychopharmacology 62 (1979), S. 17-22 
    Details
    ISSN: 1432-2072
    Schlagwort(e): CSF cyclic AMP ; Probenecid ; Homovanillic acid ; 5-Hydroxyindoleacetic acid ; Chlorpromazine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract At probenecid levels greater than 10 μg/ml, CSF cAMP was independent of CSF probenecid concentration. At these levels of probenecid, cAMP transport out of CSF is probably maximally blocked and cAMP levels reflect cAMP release into CSF. CSF cAMP was significantly higher in RDC-diagnosed schizophrenics than in other psychotics or depressives. A significant decrease in CSF cAMP was found in psychotic patients treated with chlorpromazine. No changes in CSF cAMP were observed in patients treated with tricyclic antidepressants or lithium.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00426029
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  • 2
    Digitale Medien
    Digitale Medien
    Thermal perturbation techniques in characterizing ligand-macromolecule interactions: Theory and application to the proflavin-α-chymotryspin system (1978)
    New York : Wiley-Blackwell
    Biopolymers 17 (1978), S. 1773-1792 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A thermal perturbation curve (TPC) is defined to be the derivative of the fractional degree of saturation, f, with respect to temperature, considered as a function of the natural logarithm of free ligand concentration, y. The theoretical framework for the use of such curves in the thermodynamic analysis of ligand binding to macromolecules is presented. The thermal perturbation curve either provides or complements the information obtained from the derivative binding isotherm ∂f/∂y. For a single set of identical and independent sites the TPC is identical to the derivative binding isotherm. Analysis of such a curve directly yield ΔH0 and ΔG0 for the binding reaction. In actual experimental work, however, the TPC can only be approximated because of “self-buffering” effects relations between the parameter of the approximate curve and the thermodynamic quantities have been developed. This technique is applied to the proflavin-α-chymotryspin system to demonstrate its usefulness. The general features of thermal perturbation curves for cases of multiple sets of independent sites and cooperatively interacting sites have also been developed. The analysis of thermal perturbation curves in combination with other methods should provide a more powerful approach to the characterization of ligand-macromolecule interactions.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1978.360170712
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  • 3
    Digitale Medien
    Digitale Medien
    Thermodynamics of mucopolysaccharide-dye binding. I. Identification of free and bound dye via membrane filtration: Acridine orange-dermatan sulfate system (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 685-693 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Stoichiometric mixtures of acridine orange with dermatan sulfate at total dye concentrations ≤ 1 × 10-5 M show fluorescence maxima at 540 nm and 660 nm on excitation at 436 nm. By means of membrane filtration, it is directly demonstrated that the species emitting at 540 nm is due only to unbound dye whereas the 660-nm emitting species is due to bound dye. It is, therefore, possible to differentiate unbound acridine orange from its dermatan sulfate complex solely by spectroscopic methods. Thermodynamic binding parameters can be calculated from rapid spectroscopic measurements without disturbing the system.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1977.360160316
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  • 4
    Digitale Medien
    Digitale Medien
    La fusion et la cristallisation de la poly(α,α-diéthyl-β-propiolactone): Comparaison avec d'autres polylactones (1979)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 769-783 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Measurements of crystallization kinetics were made for a sample of poly(α,α-diethyl-β-propiolactone) (DEPL) (syst. name: poly(oxy-2,2-diethyl-1-oxotrimethylene)). An Avrami exponent of 2 was found indicating a two-dimensional growth rate of the crystal, following a pre-determined and heterogeneous nucleation mode. Two melting peaks were found for most samples. The second melting peak (at high temperatures) is probably due to the re-crystallization of part of the sample initially present under the first melting peak. A value of 21kJ.mol-1 was also determined for the heat of fusion of DEPL by the diluent method. This value leads to a degree of crystallinity of 17% which is about four times smaller than that found for poly(pivalolactone) (syst. name: poly(oxy-2,2-dimethyl-1-oxotrimethylene)). We have also determined an equilibrium melting temperature of 531 K for this polymer and an entropy of fusion of 40J.mol-1. K-1. Finally, the surface free energies σ and σe for the lamellar crystals were found to be 12.10-7J.cm-2 and 72.10-7J.cm-2, respectively.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1979.021800320
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  • 5
    Digitale Medien
    Digitale Medien
    Poly(perfluoroether) oxadiazole elastomer system cured with terephthalonitrile oxide (1976)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 20 (1976), S. 1035-1047 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The terpolymerization of N,N′-terephthalonitrile oxide (TPNO), 1,3,5-tricyanobenzene, and oligomeric perfluoroalkylene dinitriles derived from the oligomerization of tetrafluoroethylene oxide yields poly(perfluoroether)-1,2,4-oxadiazole polymers which are soluble in Freon TF and bear pendent nitrile groups as curing sites. The polymerization is a two-step, ambient-temperature reaction. Several different perfluoroether dinitriles are shown to polymerize using this procedure. The syntheses and certain structure/property relationships of the polymers are discussed. Increasing the chain length of the perfluoroalkylene oxide dinitriles results in polymers which range from paraffin-like solids through tough elastomers and, finally, to tacky gums. Tough, crepe elastomer gum with a Tg of -64°C may be obtained in yields of 60-70%. The poly(perfluoroether) oxadiazoles may be milled with additional TPNO and press cured at 95°C (200°F). The following physical properties of the cured polymers are given: compression set, tensile strength, per cent elongation at break, set at break, and Shore A hardness. Thermal stability, moisture stability, and low-temperature flexibility data are also presented for the cured elastomeric polymer.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1976.070200415
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  • 6
    Digitale Medien
    Digitale Medien
    Thermodynamics of mucopolysaccharide-dye binding. II. Binding constant and cooperativity parameters of acridine orange-dermatan sulfate system (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 695-702 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In the acridine orange-dermatan sulfate system, free and bound dye can be distinguished from each other spectroscopically. This permits the use of fluorometric methods to study the binding of acridine orange to the acid mucopolysaccharide dermatan sulfate. Experiments were conducted at 24°C in 10-3 M citrate/phosphate buffer at pH = 7.0. The binding of the dye is highly cooperative, as evidenced by considerable interaction between adjacent bound dye molecules. Analysis of the data indicates that dermatan sulfate binds 2.3 ± 0.3 mol of acridine orange per dermatan sulfate uronic acid residue with a cooperative binding constant, Kq ranging from 4.9 to 6.0 × 105 M-1 which corresponds to a free energy of 7.74 ≤ ΔG° ≤ 7.86. The cooperativity parameter q apparently increases with increasing polymer-to-dye ratio.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1977.360160317
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  • 7
    Digitale Medien
    Digitale Medien
    Thermodynamics of mucopolysaccharide-dye binding. III. Thermodynamic and cooperativity parameters of acridine orange-heparin system (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 493-505 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Binding isotherms for acridine orange (AO)-heparin systems can be evaluated solely on the basis of quantitative fluorescence spectroscopic measurements. The evaluation of thermodynamic parameters indicates that the interactions of AO with heparins from several animal sources are similar to each other in magnitude. Binding is highly exothermic (ΔH = -6 kcal mol-1) and is stabilized by dye-polymer and dye-dye (coopertive) interactions, as well as by entropic factors (ΔS = +7 e.u.). The predominant stabilizing factor appears to be the electrostatic attraction between the AO cation and the heparin polyanion, although the other factors are important as well. At 24°C the value of the cooperative binding constants for the various heparins range from 8.8 to 11.3 × 105M-1, corresponding to a free energy of -8 kcal mol-1. The degree of cooperativity, which is a direct measure of dye-dye interaction, varies with polymer:dye ratio; the theoretical basis for this variation remains to be elucidated. Electrophoretic data indicate that each heparin sample consists of a mixture of species, each with its own charge density. This precludes definitive interpretation of observed small differences in the values of the thermodynamic parameters among the various samples until each sample can be resolved into its components.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1979.360180302
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  • 8
    Digitale Medien
    Digitale Medien
    Thermodynamics of the partition of chondroitin sulfate-hexadecylpyridinium complexes in butanol/aqueous salt biphasic solutions (1978)
    New York : Wiley-Blackwell
    Biopolymers 17 (1978), S. 2601-2608 
    Details
    ISSN: 0006-3525
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The thermodynamics of the partition of chondroitin sulfate-hexadecylpyridinium complexes wee studied in order to gain further insight into the mechanisms responsible for the sensitivity of the relative solubility of these complexes in aqueous slat and butanol phases to small changes in slat concentration. The dependence of the partition coefficient was measured as a function of temperature at three different salt concentrations. Increasing the temperature was found to favor the form of the complex which was soluble n the aqueous phase. Although the transition could be induced by temperature changes, he transition occurred over a 20°C range in temperature. The transition from the aqueous phase to the butanol phase was strongly exothermic, with ΔH = -22.3 kcal/mol polymer. The value of ΔS was found to be dependent on the salt concentration, ranging from -72.7 e.u./mol polymer in 0.05125M NaCl to -77.1 e.u./mol polymer in 0.05375M MaCl. When placed on a disaccharide basis, the corresponding values are ΔH = -402 cal/mol and ΔS = -1.31 to -1.3 e.u./mol. The sharpness of he transition was found to be due t the similarity in magnitude of ΔH and TΔS, and on the dependence of the later upon the salt concentration.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bip.1978.360171108
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  • 9
    Digitale Medien
    Digitale Medien
    Mechanical properties of polymer-paper laminates (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 947-957 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Tensile mechanical properties of synthetic polymer-paper laminates were measured. The laminates were constructed by hot pressing a sandwich made of a sheet of paper between polymer films. There is complete penetration of the polymer inside the paper; no voids are left. Two different polymer matrices were used: poly(methyl methacrylate) and polyethylene. Several paper samples were utilized: an unoriented holocellulose paper (a strong paper), a highly oriented holocellulose paper, and an unoriented Whatman filter paper (a weak paper). The laminates contain from 0% to 50% of paper. Young's moduli and breaking strengths of the unoriented holocellulose paper laminates can be theoretically predicted from the properties of their constituents using laws of mixtures. The mechanical properties of the Whatman paper laminates are significantly higher than those predicted from the laws of mixtures. This indicates that the polymer increases the strength of the fiber-to-fiber bonds of the weaker sheets, although it does not change the bond strength of a stronger paper such as the holocellulose paper. For the oriented paper laminates, changes in Young's modulus with angle of measurement are explained by the composite materials theories if the angular variations in shear modulus are taken in to account. Changes in breaking strength with angle for the oriented laminates can be analyzed by Tsai and Azzi's theory for composite materials.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1977.070210408
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  • 10
    Digitale Medien
    Digitale Medien
    Partial miscibility of cellulose-polyacrylonitrile blends (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 1943-1949 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Cellulose-polyacrylonitrile (PAN) blends have been prepared by the regeneration of 2% concentration solutions in dimethylformamide-NO2 solvent. The blends are transparent when containing between 0 and 50% by weight of PAN. Dynamic mechanical measurements indicate a shift in glass transition temperature Tg of PAN for the blends, suggesting partial miscibility between cellulose and PAN. Experimental density values larger than those predicted theoretically are also in agreement with this conclusion.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1979.070230705
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