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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial and engineering chemistry 11 (1972), S. 415-417 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 404 (1983), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 41 (1995), S. 415-425 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A 1-D model, which neglects radial variations, describes the hydrodynamics of cell-free ultrafiltration hollow-fiber bioreactors (HFBRs) and the transport of highmolecular-weight proteins trapped in the extracapillary space (ECS). The profiles of radially-averaged protein concentrations predicted by this model are identical to those obtained using a model with radial variations. The model predictions agree well with axial profiles of bovine serum albumin (BSA) and human transferrin concentrations measured in transient and steady-state experiments. The validated model explores the influence of cell culture operating conditions on HFBR protein transport. Increasing protein loading decreases BSA and transferrin polarization in HFBRs operated with unidirectional lumen flow. A relationship developed predicts the protein loading needed to ensure a nonzero steady-state protein concentration throughout the ECS. This critical protein loading depends only on the lumen pressure drop and the ECS protein osmotic pressure. Periodic reversal of the lumen flow direction also decreases protein polarization. The influence of the flow-direction switching time and membrane permeability on the ECS protein distribution is investigated.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 43 (1997), S. 1727-1736 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The magnitude and direction of the ultrasonic radiation forces that act on individual particles in a standing-wave field were determined using a microscope-based imaging system. The forces are calculated from measured particle velocities assuming that the drag force, given by Stokes' law, is exactly counterbalanced by the imposed ultrasonic forces. The axial primary radiation force was found to vary sinusoidally with axial position and to be proportional to the local acoustic energy density, as predicted by theory. The magnitude of the transverse primary force was determined by two independent methods to be about 100-fold weaker than the axial force. Separation concepts exploiting the transverse force for cell retention have been successful despite the great disparity in magnitude between the axial and transvers-force components. This may be explained by the reduced hydrodynamic forces on aggregated particles in transverse flow due to their alignment in the sound field.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 1099-1106 
    ISSN: 0006-3592
    Keywords: protein adsorption ; hollow fiber bioreactor ; transferrin ; serum-free medium ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The recovery of serum-free medium proteins from poly-sulfone hollow fiber bioreactors (HFBRs) was investigated. More than 99% of the initial transferrin was adsorbed to the hydrophobic hollow fibers within 2 h of HFBR operation. A methodology to minimize transferrin adsorption by pre-adsorption of bovine serum albumin (BSA) was developed. BSA adsorption on suspended cut fibers was virtually complete within 1 h. BSA-coated fibers adsorbed only 5% of the transferrin within 10 days, whereas uncoated cut fibers adsorbed more than 99% of the transferrin within 1 h. An improved HFBR startup procedure, using a BSA-coating step before inoculation, resulted in substantially higher transferrin recovery. Additional factors influenced extracapillary space (ECS) transferrin concentrations. Pronounced downstream polarization of transferrin was observed in the ECS. In addition, the 30-kDa nominal molecular weight cutoff ultrafiltration membranes rapidly leaked transferrin from the ECS to the lumen. © 1993 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Cytotechnology 28 (1998), S. 163-175 
    ISSN: 1573-0778
    Keywords: centrifuge ; cross-flow filter ; review ; sedimentation ; spin-filter ; ultrasonic cell retention
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Within the spectrum of current applications for cell culture technologies, efficient large-scale mammalian cell production processes are typically carried out in stirred fed-batch or perfusion bioreactors. The specific aspects of each individual process that can be considered when determining the method of choice are presented. A major challenge for perfusion reactor design and operation is the reliability of the cell retention device. Current retention systems include cross-flow membrane filters, spin-filters, inclined settlers, continuous centrifuges and ultrasonic separators. The relative merits and limitations of these technologies for cell retention and their suitability for large-scale perfusion are discussed.
    Type of Medium: Electronic Resource
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