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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1573-6881
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Charge carrier generation and transport in the mitochondrial lipoprotein system has been investigated by electrical conductivity, low frequency dielectric relaxation, and thermoelectric power. A parallel study was conducted on morphological/structural changes by DTA and NMR. The results obtained confirm the need to consider concurrently free charge carrier processes and polarization phenomena. All techniques show a “transition” at the same temperature. The steady state conductivity is correlated with main chain segmental reorientations of the phospholipid moiety below the transition and with an interfacial polarization process above it. The Seebeck coefficient provides a useful new aid to characterizing the charge carriers, confirming that they are electronic. The terminal cytochrome oxidase component was investigated separately but it largely reflected ionic impurities characteristic of the isolation process, so that the results were of no intrinsic value.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1573-6881
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The effect of known respiratory inhibitors on the charge carrier hall mobility of rat liver mitochondria has been investigated using a microwave technique. Potassium cyanide and rotenone were found to reduce the Hall mobility, but no effect was observed for antimycin-A. The marked effect of potassium cyanide and the low mobility value obtained for the lipid extract of the mitochondria, suggest that electronic conduction through the electron transport chain is being observed. Volume-corrected values of between 50 and 80 cm2/V sec are found for the electron Hall mobility. Measurements on spinach chloroplasts give P-type Hall mobility values of 0·5 and 0·8 cm2/V sec.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of solution chemistry 5 (1976), S. 787-797 
    ISSN: 1572-8927
    Keywords: Magnetic relaxation ; correlation times ; vinylpyrrolidone ; polyvinylpyrrolidone ; hydrophobic ; hydrophilic ; hydration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Deuteron magnetic spin-lattice relaxation times have been measured in D2O solutions of vinylpyrrolidone and polyvinylpyrrolidone as a function of concentration and temperature. For the monomer the results are interpreted in terms of a hydrophobic hydrations effect in which 42 D2O molecules per solute molecule have a correlation time of 3.2 psec at 298°K. Application of the transition state theory to the temperature dependence gave ΔH*=21 kJ mole−1 for the relaxation process. In the case of the polymer it is argued that a hydrophilic hydration effect dominates the observed relaxation. These activation enthalpy at 298°K is 24 kJ-mole−1. Assuming a hydration number of one D2O per polymer unit, the correlation time for the bound water is 77 psec at 298°K. Polymer proton spin-lattice relaxation times were measured as a function of frequency, and the results are analyzed in terms of a log normal distribution of correlation times. The median value at 296°K is 1.2 nsec.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1573-6881
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1573-6881
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1573-6881
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The observed initial microwave Hall mobility values at 1·21 tesla of heavy beef heart mitochondria is at least six times greater than that observed for bovine serum albumin at similar resistivity values. The respiratory inhibitor cyanide significantly reduces the initial Hall mobility values for HBHM and for a preparation of HBHM cytochrome oxidase. The four enzymic complexes of the respiratory chain were partially or completely separated. Of these complexes cytochrome oxidase exhibits the largest microwave Hall mobility. The maximum hydration content of loosely bound water for freezedried preparations of cytochrome oxidase is 5% by weight; 60% of this hydration content is driven off by microwave power. Since the effective ac resistivity of the samples of cytochrome oxidase did not appreciably vary with changes in hydration content, the true resistivity of cytochrome oxidase has a value of the order 5×103 ohm cm and possibly much lower. The electron transport pathway (as measured by Hall signal) of cytochrome oxidase is irreversibly damaged by prolonged exposure to microwave irradiation at 9·2 GHz. This is accompanied by the complete loss of capacity to oxidise ferrocytochromec. Such changes do not occur with HBHM or with the other respiratory complexes. There appears to be a direct relationship between observed Hall signals and the capacity of cytochrome oxidase to oxidize ferrocytochromec. There is a “background” signal which is not directly related to electron transport but which is dependent on the conformation of the cytochrome oxidase. The observed electronic parameters of cytochrome oxidase do not depend appreciably on its redox state. Acid denaturation of cytochrome oxidase drastically reduces the Hall signal, to include almost complete removal of the “background” signal. It also more than doubles ac resistivity. An electron tunnelling model is outlined.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 1 (1946), S. 529-534 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An elementary theory is given for the rolling of polymeric materials, for the case in which the deformation is largely an irreversible flow of the viscous type. The theory treats the rolling process as the homogeneous deformation of volume elements over the arc of contact and neglects frictional forces that may exist at the roll surface. A numerical example is given of the calculation of roll pressure, which agrees with available data to a factor of two or better. A more complete test will require parallel measurements of viscosity and roll pressure on the same material.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 1 (1946), S. 535-539 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In the rolling of Plastic sheet the viscous work gives rise to heating of the plastic sheet. The maximum temperature reached in the interior of the sheet during shearing is of the interest, both in the theoretical calculation of roll pressure, and from the point of view of possible thermal decomposition effects. A calculation is given for a simple, some-what artificial, model, which leads to an upper value for this maximum temperature if a measurement of the average temperature of the emergent sheet is given. The model taken is that of an infinite sheet, of thickness 2δ, in which heat is continuously liberated at the rate of 4ηφ2 cal. cc. -1 sec. -1, where φ is the relevant value of the rate of compression (assumed constant across the sheet). The curve giving the temperature distribution across the sheet is calculated numerically for two cases; it is relatively flat, as would be expected on physical grounds, since the viscosity, η, decreases as the temperature rises. It is concluded that these thermal effects may be neglected in the calculation of roll pressure in Part 1.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 58 (1962), S. 869-880 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The polymerization of acrylonitrile initiated by diethyl sodiomalonate in dimethylformamide has been investigated. The degree of polymerization was found to be independent of the monomer conversion but was dependent on the extent of polymerization. The polymers produced were examined for functional groups by infrared spectroscopy. An anionic mechanism involving hydride ion transfer to monomer has been suggested. The kinetics of the reaction can be followed because of the slow initiation step and are found to be governed by the rate expression -d[M]/dt = k[M]2[C]. The decrease in DP with increasing conversion is due to degradation of the polyacrylonitrile by basic ions. The ratios of the rate constants for both the monomer and polymer transfer reactions to the rate constant for propagation have been determined. The coloration of the polymers appears independent of the degradation reaction.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 3 (1948), S. 345-349 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The surface tension of polyoxyethylene glycol in water leads to a value for the area per molecule which shows that the polymer molecules lie approximately flat in the surface. Molecular weight determinations by end-group analysis and freezing-point depression are compared with values of the intrinsic viscosity and limiting area per molecule.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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