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  • Articles: DFG German National Licenses  (3)
  • 1990-1994  (3)
Source
  • Articles: DFG German National Licenses  (3)
Material
Years
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Evidence for two uptake systems in Rhizobium leguminosarum for hydroxy-aromatic compounds metabolized by the 3-oxoadipate pathway (1991)
    Springer
    Archives of microbiology 156 (1991), S. 385-391 
    Details
    ISSN: 1432-072X
    Keywords: Rhizobium leguminosarum ; Aromatic metabolism ; Aromatic uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rhizobium leguminosarum biovar viciae and Rhizobium leguminosarum biovar trifolii have separate uptake systems for 4-hydroxybenzoate and protocatechuate. The 4-hydroxybenzoate uptake system (pobP) is inhibited by a range of compounds with substitution at the 4-position on the aromatic ring whereas the uptake system for protocatechuate (pcaP) is markedly inhibited only by other dihydroxybenzoic acids. The rate of 4-hydroxybenzoate uptake is very low in Rhizobium leguminosarum and Rhizobium trifolii grown on protocatechuate but mutants defective in 4-hydroxybenzoate uptake transport protocatechuate at rates similar to the wild-type grown under similar conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248715
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Flow of thermoplastics in an annular die under parallel oscillations (1990)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 1574-1584 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A sound wave extrusion system has been developed. This system includes a single screw extruder and an annular die having an internal surface oscillating in the sound frequency range. Oscillating shear flow has been imposed in the direction parallel to the main pressure flow. The die characteristics and average melt temperature at the exit from the die for several thermoplastics have been measured with and without imposition of oscillations. Modeling of parallel superposition of sound oscillations upon pressure flow has been performed using the Leonov viscoelastic constitutive equation. Three cases are considered: (i) the process is isothermal and the change in die pressure is only due to a nonlinear interaction of oscillatory and pressure flow; (ii) the process is nonisothermal and adiabatic, and pressure reduction is due to the nonlinear interaction and the dissipation of oscillatory energy leading to the temperature rise in polymer melts; (iii) the process is nonisothermal with heat transfer due to transient heat conduction and the dissipation of oscillatory energy. Pressure reduction occurs due to both nonlinear interaction and temperature rise. It is found that case (i) cannot explain the observed die pressure reduction, while case (ii) describes those data only at high flow rates. The theoretical results from case (iii) are found to be in qualitative agreement with experimental observations. Generally, the theoretical results of case (iii) are better than those of cases (i) and (ii).
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760302404
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of oscillations during extrusion on rheology and mechanical properties of polymers (1990)
    Hoboken, NJ : Wiley-Blackwell
    Advances in Polymer Technology 10 (1990), S. 31-45 
    Details
    ISSN: 0730-6679
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: An experimental study associated with the applications of sound and ultrasonic waves to extrusion is conducted. Two laboratory setups are developed for these purposes incorporating orthogonal and parallel superposition of oscillations on pressure flow during extrusion. The orthogonal superposition of sound oscillations is imposed in an annular die. The parallel superposition of ultrasound oscillations is imposed in a circular die. Several materials including unfilled and filled thermoplastics, thermoplastic elastomer, and elastomer are tested. Die characteristics, power consumption, and die swell are determined during extrusion. The rheological properties, molecular weight, tensile properties, and impact strength of materials with and without sound and ultrasound treatment are investigated, indicating permanent changes in these properties. The observed effects are found to depend on melt temperature, flow rate, nature of polymer system, and oscillating parameters such as frequency and deformation amplitude.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/adv.1990.060100104
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    Paper (German National Licenses)
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