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  • Biochemistry and Biotechnology  (2)
  • Industrial Chemistry  (2)
  • cell damage  (1)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 446-454 
    ISSN: 0006-3592
    Keywords: bubbles ; Pluronic F68 ; hybridoma cells ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We describe a method by which the degree of bubble saturation can be determined by measuring the velocity of single bubbles at different heights from the bubble source in pure water containing increasing concentrations of surfactants. The highest rising velocities were measured in pure water. Addition of surfactants caused a concentration-dependent and height-dependent decrease in bubble velocity; thus, bubbles are covered with surfactants as they rise, and the distance traveled until saturation is reached decreases with increased concentration of surfactant. Pluronic F68 is a potent effector of bubble saturation, 500 times more active than serum. At Pluronic F68 concentrations of 0.1% (w/v), bubbles are saturated essentially at their source. The effect of bubble saturation on the interactions between animal cells and gas bubbles was investigated by using light microscopy and a micromanipulator. In the absence of surfactants, bubbles had a killing effect on cells; hybridoma cells and Chinese hamster ovary (CHO) cells were ruptured when coming into contact with a bubble. Bubbles only partially covered by surfactants adsorbed the cells. The adsorbed cells were not damaged and they also could survive subsequent detachment. Saturated bubbles, on the other hand, did not show any interactions with cells. It is concluded that the protective effect of serum and Pluronic F68 in sparged cultivation systems is based on covering the medium-bubble interface with surfaceactive components and that cell death occurs either after contact of cells with an uncovered bubble or by adsorption of cells through partially saturated bubbles and subsequent transport of cells into the foam region. © 1994 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 1246-1254 
    ISSN: 0006-3592
    Keywords: bubble aeration ; oxygen transfer ; hybridoma ; cell damage ; foam reduction ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new bubble aeration system was designed to minimize cell killing and cellular damage due to sparging. The residence time of the bubbles in the developed bubble bed reactor was prolonged dramatically by floating them in a countercurrent produced by an impeller. The performance of the new reactor bubble aeration system, implemented in a laboratory reactor, was tested in dynamic aeration experiments with an without cells. An efficiency up to 95% in oxygen transfer could be achieved, which enables a much lower gas flow rate compared with conventional bubble aeration reactors. The low gas flow rate is important to keep cell damage by bubbles as low as possible. A laser light sheet technique used to find the optimal flow pattern in the reactor. The specific power dissipation of the impeller is a good measure to predict cell damage in a turbulent flow. Typical values for the power dissipation measured in the bubble bed reactor were in the range of 0.002 to 0.013 W/kg, which is far below the critical limit for animal cells. The growth of a hybridoma cell line was studied in cell cultivation experiments. A protein-free medium without supplements such as serum or Pluronic F68 was used to exclude any effect of cell-protecting factors, No difference in the specific growth rate and the yield of the antibodies was observed in cell grown in the bubble free surface aeration in the spinner flask. In contrast to the spinner flask, however, the bubble bed reactor design could be scaled up. © 1994 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 37 (1965), S. 39-43 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bei der Tropfenbildung an einer Düse in einer pulsierenden Flüssigkeit zeigen sich bestimmte Frequenzbereiche, in denen sich regelmäßig Tropfen von einheitlicher Größe bei jedem dritten, zweiten oder jedem einzelnen Pulsationshub ablösen. Dazwischen befinden sich Übergangsgebiete mit unregelmäßiger Ablösung, in denen Tropfen unterschiedlicher Größe gebildet werden. Für einen einzelnen Übergangsbereich wird eine durch zwei empirische Größen ergänzte Gleichung abgeleitet, die den Zusammenhang zwischen dem Volumendurchsatz und der dazugehörigen Grundfrequenz beschreibt. Die Meßwerte lassen sich damit für verschiedene Pulsationsamplituden, Düsendurchmesser und Flüssigkeitssysteme zusammenfassend darstellen.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 39 (1967), S. 900-906 
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Die Größe der in pulsierten Füllkörper-Extraktionskolonnen gebildeten Tropfen wurde photographisch und photoelektrisch bestimmt. Die Resultate für verschiedene Stoffsysteme ließen sich durch einen dimensionslosen Ausdruck zusammenfassen. Messungen des Holdup führten zu dem überraschenden Ergebnis, daß der Holdup der dispersen Phase nur über die Tropfengröße von den Pulsationsbedingungen abhängig ist. Aus Stoffaustauschmessungen ließen sich bei bekanntem Holdup und gemessener Tropfengröße Stoffdurchgangskoeffizienten berechnen, die mit entsprechenden Werten aus Versuchen an nicht-pulsierten Kolonnen ohne Einbauten gut übereinstimmen, was auf eine neue, einfache Berechnungsmethode von pulsierten Füllkörper-Extraktionskolonnen hinweist.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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