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  • 1
    Electronic Resource
    Electronic Resource
    Selective sorption and facilitated transport of oxygen in porphinatocobalt-coordinated polymer membranes (1991)
    s.l. : American Chemical Society
    Macromolecules 24 (1991), S. 5851-5855 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00021a020
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  • 2
    Electronic Resource
    Electronic Resource
    Sorption and partial molar volumes of organic gases in rubbery polymers (1992)
    s.l. : American Chemical Society
    Macromolecules 25 (1992), S. 4321-4324 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00043a012
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  • 3
    Electronic Resource
    Electronic Resource
    Dynorphins directly inhibit neuronal nicotinic acetylcholine receptors in PC12 cells (2000)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 12 (2000), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The authors have previously reported that dynorphin A (1–17), an endogenous kappa opioid agonist, inhibits the current mediated through neuronal nicotinic acetylcholine receptors (nAChRs) without the involvement of opioid receptors or G-proteins. We have further characterized this action to elucidate the mechanisms. The nicotine-induced current was studied in PC12 cells using patch-clamp techniques. In the whole-cell configuration, four kinds of dynorphins with different lengths, dynorphin A (1–17) (1–13) (2–13) and (1–8), similarly inhibited the nicotine-induced inward current at 1 μm and accelerated the current decay. The inhibition by dynorphin A (1–17) was not antagonized by the increasing concentrations of nicotine. The current–voltage relationship revealed that dynorphin's inhibition was voltage independent at the membrane potentials from −30 to −70 mV. The inhibition was not affected by pretreatment with pertussis toxin (PTX) or inclusion of staurosporine into the pipette solution. The inhibitory effect of dynorphin A (1–17) was well preserved in the outside-out patch configuration. Analysis of the nicotine-induced noise and single-channel kinetics revealed that dynorphin A(1–17) reduced open time without changing the amplitude of the unitary current. We found that the inhibitory effect on neuronal nAChRs is shared by all four dynorphins studied. The inhibition appears to be non-competitive and voltage independent. The outside-out recording together with other experiments indicated that a major part of this inhibition is not mediated through cytoplasmic messengers, but based on the direct action of dynorphins on neuronal nAChRs leading to the reduction of open time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9568.2000.00012.x
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  • 4
    Electronic Resource
    Electronic Resource
    A dielectric relaxation study of plasticization of poly(ethyl methacrylate) by carbon dioxide (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 28 (1990), S. 1955-1964 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Plasticization of poly(ethyl methacrylate) (PEMA) by CO2 is investigated by dielectric relaxation spectroscopy. The dissipation factor of a dielectric cell containing the film and air gaps is measured as a function of frequency (1-10,000 kHz) and CO2 pressure (0-60 atm) over the temperature range 35-115°C. A maximum in the frequency dependence of the dissipation factor, which is attributed to the α relaxation of PEMA, shifts to higher frequency with increasing temperature, pressure, or concentration. The apparent activation energy of the isosteric relaxation decreases from 28 to 23 kcal/mol as the concentration is increased from 0 to 90 cm3 (STP)/cm3 (polym). The relaxation peak temperature at fixed frequency decreases with increasing concentration. The effect of hydrostatic pressure on the dielectric relaxation is estimated and compared with values for the PEMA-He and PEMA-Ar systems. The plasticizing effect of sorbed CO2 is discussed on the basis of the relaxation data.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1990.090281106
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  • 5
    Electronic Resource
    Electronic Resource
    Argon sorption and partial molar volume in poly(ethyl methacrylate) above and below the glass transition temperature (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 29 (1991), S. 225-234 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Sorption and dilation isotherms for argon in poly(ethyl methacrylate) (PEMA) are reported for pressures up to 50 atm over the temperature range 5-85°C. At temperatures below the glass transition (Tg=61°C), sorption isotherms are well described by the dual-mode sorption model; and isotherms above Tg follow Henry's law. However, isotherms for dilation due to sorption are linear in pressure at all temperatures over the range investigated. Partial molar volumes of Ar in PEMA are obtained from these isotherms. The volumes are approximately constant above Tg (about 40 cm3/mol), whereas the volumes below Tg are smaller and dependent on both temperature and concentration (19-26 cm3/mol). By analyzing the experimental data according to the dual-mode sorption and dilation model, the volume occupied by a dissolved Ar molecule and the mean size of microvoid in the glass are estimated to be 67 129 Å3, respectively. The cohesive energy density of the polymer is also estimated as 61 cal/cm3 from the temperature dependence of the dual-mode parameters.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1991.090290208
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  • 6
    Electronic Resource
    Electronic Resource
    Permeation of high-pressure gases in poly(ethylene-co-vinyl acetate) (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 693-697 
    Details
    ISSN: 0887-6266
    Keywords: permeation of high-pressure gases in poly(ethylene-co-vinyl acetate) ; copolymer, ethylene-vinylacetate, permeation of gases in ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A previously proposed theoretical treatment to elucidate the pressure dependence of gas permeability is improved in order to apply it to polymer-gas systems in which gas dissolution follows the Flory-Huggins equation. Permeation rates of N2, CH4, and CO2 in poly(ethylene-co-vinyl acetate) are measured in the pressure range below 90 atm at 10-40°C, and the effect of pressure on permeability is found for each gas. The data are analyzed using the improved method to estimate the contributions of concentration and hydrostatic pressure to the pressure dependence of permeability. The concentration effect decreases with increasing temperature, whereas the hydrostatic-pressure effect is almost independent of temperature. Crystallinity dependence of the concentration effect is discussed in connection with high-pressure permeation data of other semicrystalline polymers reported elsewhere. © 1993 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1993.090310609
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  • 7
    Electronic Resource
    Electronic Resource
    Sorption and partial molar volume of gases in poly (dimethyl siloxane) (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 28 (1990), S. 1297-1308 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Sorption of N2, O2, Ar, CH4, CO2, C2H4, and C2H6 in poly (dimethyl siloxane) liquid and rubber and the dilation of the polymers due to sorption of the gases are studied at 25°C under pressures up to 50 atm. In the liquid, the sorption isotherms for low-solubility and high-solubility gases are described by Henry's law and the Flory-Huggins equation, respectively. Gas sorption in the rubber, which contains a 29 wt % silica filler, follows the dual-mode sorption model, though marked hysteresis is observed in the sorption of O2 and CH4. The dilation isotherms increase linearly or exponentially in both polymers with increasing pressure. Considering that gas molecules adsorbed into micropores of the filler particles do not participate in the dilation, partial molar volumes of the dissolved gases in the rubber are determined from data of sorption and dilation. The values are nearly equal to the partial molar volumes in the liquid (48-60 cm3/mol).
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1990.090280808
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  • 8
    Electronic Resource
    Electronic Resource
    Sorption and dilation properties of poly(p-phenylene sulfide) under high-pressure carbon dioxide (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 28 (1990), S. 2057-2069 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Sorption and dilation properties of the system poly(p-phenylene sulfide) (PPS) and carbon dioxide have been investigated at pressures up to 50 atm over the temperature range 25-85°C. The shapes of the sorption isotherms are in agreement with those predicted by the dual-mode theory. Analysis of the sorption and dilation isotherms confirms the occurrence of an isothermal glass transition. This occurrence and its corresponding disappearance in the range investigated is discussed. Values of the partial molar volume of CO2 sorbed in PPS are calculated below and above the isothermal transition. Compared with sorption by other polymers, these values were about the same in the glassy state, but were smaller in the rubbery state. Under 50 atm CO2 at 85°C crystallization of amorphous PPS was observed. The crystallinity estimated from the solubility before and after crystallization is about 20%.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1990.090281112
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  • 9
    Electronic Resource
    Electronic Resource
    Plasticization of poly(ethyl methacrylate) by dissolved argon (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 30 (1992), S. 1177-1181 
    Details
    ISSN: 0887-6266
    Keywords: plasticization of poly(ethyl methacrylate) by dissolved argon ; poly(ethyl methacrylate) plasticization by dissolved argon ; sorption of argon in poly(ethyl methacrylate) ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1992.090301014
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  • 10
    Electronic Resource
    Electronic Resource
    The effect of pressure on gas permeation through semicrystalline polymers above the glass transition temperature (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 29 (1991), S. 457-462 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A method is proposed to analyze the effect of pressure on permeation of gases through semicrystalline polymers above the glass transition temperature. The method utilizes similarities in molecular diameters of the gases and differences in their solubilities. Two polymers, polyethylene and polypropylene, and a series of gases are chosen for an application of the method, and the effect of pressure on the permeabilities for 10 gases is measured in the pressure range 1-130 atm at 25°C. For polymers, the logarithm of the permeability coefficient is linear in the pressure for each gas, with negative slope for slightly soluble gases (He, Ne, H2, N2, O2, and Ar) and positive slope for highly soluble gases (CH4, Kr, CO2, and N2O). Analyzing these slopes by the method proposed permits contributions of hydrostatic pressure and concentration to the pressure dependence of permeation to be evaluated. On the basis of the results, the mechanism of gas permeation in rubbery films under high pressures is discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1991.090290408
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