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  • Chemistry  (18)
  • Class II patatin gene  (1)
  • Antisense repression
  • Structured Biological Modelling
  • 1985-1989  (19)
Collection
Keywords
Publisher
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    A class II patatin promoter is under developmental control in both transgenic potato and tobacco plants (1989)
    Springer
    Molecular genetics and genomics 219 (1989), S. 390-396 
    Details
    ISSN: 1617-4623
    Keywords: Class II patatin gene ; β-glucuronidase ; Transgenic potato ; Transgenic tobacco ; Root tip
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A new member of the patatin gene family belonging to the class II subfamily was isolated and characterized by DNA sequencing. In order to study the expression profile of this gene, the promoter was fused to the β-glucuronidase gene and transferred to potato and tobacco. Histochemical analysis revealed high expression in a few defined cells in potato tubers and in a specific layer of both potato and tobacco root tips. In contrast to the developmentally and metabolically regulated class I patatin gene B33 this gene was not inducible by elevated levels of sucrose. Expression of this chimaeric gene was also found in callus and suspension cultures of potato.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00259611
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  • 2
    Electronic Resource
    Electronic Resource
    Continuous fractionation and solution properties of PVC, 3Part 1, 2: cf. 1,2. Pressure dependence of the solubility in single solventsIn memoriam of Professor G. Rehage (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 769-776 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: From the break-down in the viscosity and from the increase of the intensity of the scattered light, associated with the entrance into the two-phase region, the pressure dependence of the demixing temperature of solutions of PVC 37 000, PVC 75 000 and PVC 100 000 in phenetole and PVC 75 000 in o-xylene was measured up to 1 000 bar. (The numbers in the codes of the PVC specimens are their approximate molecular weights.) The application of pressure increases the demixing temperatures of PVC in both solvents by about 1 K/100 bar. For a qualitative forecast of the pressure effects, the solubility parameter theory in combination with the corresponding states principle, and an empirical correlation to the relative distance of the critical demixing temperature to the melting point of the pure solvent were used. The results of both concepts are in accord with the experimental findings.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.021860409
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  • 3
    Electronic Resource
    Electronic Resource
    Continuous fractionation and solution properties of PVC, 2Part 1: cf. 1. Scrutiny of solvents, intrinsic viscosityDedicated to Professor H. Inagaki in honour of his 60th birthday (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 753-767 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Investigations with ca. 100 organic liquids in a temperature range from -20°C to 90°C result in a survey of the solubility behaviour of PVC. The experimental results were compared with the predictions of the solubility parameter theory: Accepting δ = 9,75 (cal/cm3)1/2 as the solubility parameter for PVC, all solvents (except ketones in which PVC is soluble independent of their solubility parameters) are located within the range of δPVC ± 0,75. Only three of the 100 liquids examined turned out to be (endothermal) theta-solvents, namely the aromatic solvents o-xylene, phenetole and dimethyl phthalate. The theta-temperatures in o-xylene and phenetole were determined viscometrically by means of the temperature dependence of the Mark-Houwink exponent to be 84 and 88°C, respectively. Viscosity measurements were also performed in the temperature range of 25 to 60°C with solutions of PVC 75 000 in 10 thermodynamically good solvents used for rheological investigations. In all cases the intrinsic viscosities decrease slightly with increasing temperature, i.e., all solutions are weakly exothermal. The binary cluster integral, β, was determined (taking the monomeric unit as the statistical segment) and the polar contribution, βe, was calculated from Yamakawa's theory. The correlations between the non-polar part of (βn = β - βe) and the solubility parameter of the solvent, found by Utracki, were tested and found to be valid for the present systems, too.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.021860408
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  • 4
    Electronic Resource
    Electronic Resource
    Influence of shear on the demixing of polymer solutions, 1 apparatus and experimental results (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 1613-1625 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An apparatus for turbidimetric measurements of demixing temperatures under shear flow is presented, and the results of experiments with trans-decahydronaphthalene/polystyrene (TD/PS) solutions, investigating molecular weights ranging from 100 kg/mol to 1770 kg/mol, are compared with viscometric data. It is found that the sign and magnitude of shear effects depend on molecular weight (Mw), polymer concentration (c2), and shear rate (\documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document}). For the first time, it was possible to study a solution which exhibits shear dissolution at low shear rates but shear demixing at high shear rates.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890716
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  • 5
    Electronic Resource
    Electronic Resource
    Continuous fractionation and solution properties of PVC, 1. Continuous fractionation, characterisationDedicated to Professor R. Koningsveld in honour of his 60th birthday (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 735-751 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A new Continuous Polymer Fractionation method, called CPF, is described. The polymer to be fractionated is dissolved in a solvent/non-solvent mixture, and this solution (feed) is extracted continuously by a second liquid (extracting agent), which contains the same solvent components as the feed. In the case of PVC, the fractionation was carried out with a pulsed counter current extraction apparatus and THF/water was used as solvent/non-solvent mixture. Fractionation is achieved by the fact that the molecules are distributed over the counter current phases according to their chain length; the feed leaves the column as gel and the extracting agent as sol. First some explorative experiments were made in order to determine suitable working parameters, like frequency and amplitude of pulsation, compositions of feed and extracting agent and the ratio of flow. With the so obtained parameters, preparative experiments were carried out, yielding five PVC-fractions with molecular weights ranging from 20 000 to 100 000 (GPC, LS) and non-uniformities, U = (Mw/Mn) -1, of about 0,2 (GPC) using a starting material with Mw = 67 000 and U = 0,95.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.021860407
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  • 6
    Electronic Resource
    Electronic Resource
    Continuous fractionation and solution properties of PVC, 4Part 1-3: cf. Refs.1-3. Pressure dependence of the solubility in a mixed solventDedicated to Professor K. J. Ivin in honour of his 60th birthday (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 777-785 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Using a self-constructed light scattering apparatus, the pressure dependence of the demixing temperature of solutions of PVC 20 000, PVC 37 000 and PVC 70 000 in THE/water was determined up to 1 000 bar for different compositions of the mixed solvent. (The numbers in the codes of the PVC specimens are their approximate molecular weights.) In contrast to the thetasolvents o-xylene and phenetole, the solubility decreases with increasing pressure for all molecular weights and compositions under investigation typically by about 1 K/100 bar. The evaluation of the experimental findings demonstrates that the volume fraction of the nonsolvent in the mixed solvent, ϕ2*, is the variable that governs phase separation: For the present region of p and T, a given polymer solution demixes at a characteristic constant value of ϕ2*, no matter how it is reached. This fact allows the prediction of pressure influences from known pVT data of the pure components and measurements at atmospheric pressure. A qualitative theoretical understanding of the observed influences of p and T can be reached on the basis of the solubility parameter theory.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.021860410
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  • 7
    Electronic Resource
    Electronic Resource
    Continuous fractionation and solution properties of PVC, 5Part 1-4: cf. Refs.1-4. Pressure dependence of the viscosity  -  influence of solventDedicated to Professor J. Schurz in honour of his 60th birthday (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 787-799 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Viscosity measurements were carried out as a function of pressure and temperature with solutions of 8 wt.-% PVC (Mw ≈ 75 000) in ten thermodynamically good solvents by means of a Searle-type viscometer. A rollingxyhball viscometer was used for the investigation of the pure solvents. In all cases the viscosity increases in a more or less exponential manner when the pressure is raised. The viscosity ratio f1000 = η1000 bar/η1bar can be varied by the choice of the solvent from ca. 2 (tetrahydrofuran) to 3,0 (cyclohexanone) at 40°C. For a constant temperature of 40°C, the volumes of activation for the viscous flow of the solutions, V≠, or f1000 exceed that of the pure solvent, by typically 25%. The dependence of f1000 or V≠ upon temperature is not very pronounced. However, the greater the f1000-values, the more marked are the temperature effects. The theoretical analysis of the data, including earlier measurements with PS, indicates that three terms contribute to f1000: the basic value (f1000)s stemming from the pure solvent, the value (f1000)p which the polymer would contribute under athermal conditions, and finally a thermodynamic term, (f1000)pa, considering the pull-along effect (i.e. the specific forces a given segment exerts on other segments under variable thermodynamic conditions).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.021860411
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  • 8
    Electronic Resource
    Electronic Resource
    Continuous fractionation and solution properties of PVC, 6Parts 1-5: cf. refs. 1-5. Pressure dependence of the viscosity  -  influence of molecular weight and compositionDedicated to Professor O. Fuchs in honour of his 80th birthday (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 186 (1985), S. 801-815 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Viscosities were measured as a function of pressure and temperature with solutions of PVC 75 000 in cyclohexanone (CHO) and polymer contents ranging from 0,6 to 12 wt.-%, by means of a Searle-type (≥3 wt.-%) and a rolling-ball viscometer (〈3 wt.-%). Furthermore, the influence of molecular weight was determined with solutions of 8 wt.-% of PVC 20 000, PVC 37 000 and PVC 100 000. (The numbers in the codes of the PVC specimens are their approximate molecular weights.) For all concentrations and molecular weights, the viscosity increases in a more or less exponential manner with increasing pressure. The ratio f1000 of the viscosity of the solution at 1 000 and 1 bar can be varied by the change of the polymer content from 2,5 (the value of the pure solvent, index s) to 3,5 (12 wt.-% PVC 75 000) at t = 25°C and from 2,23 to 2,94 at t = 80°C. An increase of the molecular weight of the polymer raises f1000 in a similar manner as the polymer concentration. Using the reduced variables V≠/V≠ (ratio of the volumes of activation of the solution and the pure solvent) and c̃ (product of the polymer concentration and the intrinsic viscosity), all results obtained by variation of T, c and Mw can be represented by a master curve. This means that it is possible to calculate the pressure dependence of a given polymer solution of arbitrary polymer concentration from a mere measurement of the intrinsic viscosity at normal pressure. Criteria are presented which allow a forecast concerning the occurrence of minima in the concentration dependence of the energy of activation of the viscous flow E≠ and V≠.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.021860412
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  • 9
    Electronic Resource
    Electronic Resource
    Second virial coefficient revisited, 3Part 2: cf.2.. Viscosity of dilute polymer solutions: Molecular weight dependence of the Huggins coefficientDedicated to Prof. Dr. G. Manecke on the occasion of his 70th birthday (1986)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 187 (1986), S. 2969-2990 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The variation of the Huggins coefficient KH with the relative molecular mass M of the polymers was measured for solutions of polystyrene and of polyisobutylene and found to be most pronounced in the case of thermodynamically good solvents but vanishing at the theta-temperature, where the individual curves kH (T; M) intersect with each other. The experimental results are interpreted as a consequence of the rheological inequality of inter- and intra-molecular contacts between polymer segments. A model is presented according to which kH should be a linear function of M-(a-0,5), where a is the exponent of the intrinsic viscosity-relative molecular mass relationship (Kuhn-Mark-Houwink). The evaluation of the present data, together with information from the literature, yields the individual effects from inter- and intra-molecular intersegmental contacts, their interdependence, and their variation with the thermodynamic quality of the solvent. In thermodynamically poor solvents, were the polymer coils are nondraining, these effects are found to differ extremely; however, they approach each other as the goodness of the solvent improves and the coils become draining; their identity can be extrapolated for a = 1.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1986.021871221
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  • 10
    Electronic Resource
    Electronic Resource
    Influence of shear on the demixing of polymer solutions, 2Part 1: cf.4a.. Stored energy and theoretical calculations (1988)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 189 (1988), S. 1627-1634 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Phase diagrams were calculated for flowing solutions of polystyrene in trans-decahydronaphthalene assuming that the energy (Es) stored in the sheared state has to be added to the Gibbs energy of mixing; Es is computed from viscometric data (flow curves). The resulting phase diagrams exhibit two maxima in most of the cases instead of only one for the stagnant solutions. A comparison with experimental data (Part 1) shows that the calculated demixing behaviour agrees well for moderate shear rates and concentrations of the polymer. Deviations in the semidilute region, particularly for higher \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma $\end{document} values, are a consequence of the fact that so far no reliable theoretical relation has been given for these conditions to calculate Es from viscometric data. In all cases, however, the present attempt describes the characteristics of the phase diagrams very well, namely the eulytic points and the inversion of shear dissolution into shear demixing.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1988.021890717
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