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  • 1
    Electronic Resource
    Electronic Resource
    Oxygen Diffusion Coefficients in Commonly Used Topical Semisolid Creams (1988)
    Springer
    Pharmaceutical research 5 (1988), S. 92-98 
    Details
    ISSN: 1573-904X
    Keywords: steady-state analysis ; unsteady-state analysis ; USP XXI hydrophilic ointment ; phase–volume ratio ; 1% anthralin products
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The objective of this paper is to determine oxygen diffusion coefficients, permeabilities, and solubilities in a commonly used o/w topical ointment (similar to USP XXI hydrophilic ointment) and four commercial 1% anthralin creams. A new method developed by Ju and Ho in 1986 by applying a coupled steady-state and unsteady-state analysis for oxygen diffusion through a thin layer of test material on the surface of a membrane-covered polarographic oxygen electrode was used in the study. The results indicate that oxygen diffusion coefficients decrease with an increasing petrolatum concentration in o/w topical creams. The oxygen diffusion coefficients in four commercial creams containing 1% of extremely oxygen-sensitive anthralin were also determined using the same method. The information generated in this study can lead to a better understanding of the diffusion transport mechanism of oxygen in the topical creams and, thus, be useful to the formulation design of oxygen-sensitive drugs in semisolid dosage forms intended for topical, ophthalmic, and parenteral use.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015936100750
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  • 2
    Electronic Resource
    Electronic Resource
    Modeling and simulation of oxygen transfer in airlift fermentors (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 19 (1977), S. 1503-1522 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model for simulation of oxygen transfer in airlift fermentors is presented. The airlift fermentor is represented by a number of interconnected compartments, each of which is assumed to be well mixed. In the annular region, the model includes both upflow and downflow for the gas phase. The model contains several adjustable parameters through which important hydrodynamic effects affecting oxygen transfer are incorporated. The effect of hydrostatic pressure is also included in the model. The model is simple enough to be used in design studies and it can be easily adapted to other airlift system configurations. The simulation results show good qualitative agreement with available experimental results.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260191008
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  • 3
    Electronic Resource
    Electronic Resource
    Measuring oxygen diffusion coefficients with polarographic oxygen electrodes: I. Electrolyte solutions (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 1495-1499 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260271015
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  • 4
    Electronic Resource
    Electronic Resource
    The anomaly of oxygen diffusion in aqueous xanthan solutions (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 32 (1988), S. 8-17 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A membrane-covered polarographic oxygen electrode was used to measure oxygen diffusion coefficients in aqueous polyelectrolyte solutions of xanthan gum, sodium alginate, and sodium carboxymethylcellulose (CMC). In sodium alginate solutions, dilute xanthan solutions, and solutions containing more than 0.3 wt % CMC, oxygen diffusion coefficients decrease with increasing polymer concentrations. Interestingly, in dilute CMC solutions and concentrate xanthan solutions containing more than 0.5 wt % xanthan gum, oxygen diffusion coefficients increase with increasing polymer concentrations, and values exceeding that in pure water are generally observed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260320104
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  • 5
    Electronic Resource
    Electronic Resource
    Oxygen diffusion coefficient and solubility in n-hexadecane (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 34 (1989), S. 1221-1224 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260340914
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  • 6
    Electronic Resource
    Electronic Resource
    Enhancing penicillin fermentations by increased oxygen solubility through the addition of n-hexadecane (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 1110-1118 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: n-Hexadecane was added to fermentation media to increase the medium oxygen solubilities, thus enhancing oxygen transfer rates in penicillin fermentations. For shake flask fermentations, cells were found to grow faster in the flasks with n-hexadecane than those without. The addition of n-hexadecane to penicillin fermentations was shown to significantly increase cell growth and penicillin production and reduce formation of mycelial pellets. The result was attributed to the enhancement of oxygen transfer in mycelial fermentations due to the higher oxygen solubilities of fermentation media achieved by adding n-hexadecane.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260361106
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of Carbon dioxide on the Rheological behavior and oxygen transfer in submerged penicillin fermentations (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 1223-1232 
    Details
    ISSN: 0006-3592
    Keywords: penicillin fermentation ; carbon dioxide effect ; oxygen transfer ; oxygen diffusion ; rheological behavior ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fermentations of Penicillium chrysogenum have been made with different CO2 contents in the influent gas streams. The rheological behavior of the culture broth was found to be significantly changed by exposure to high levels of CO2. This is attributed to the wide variation in the morphology of P. chrysogenum, from normal mycelia with long hyphae to roughly spherical pellets when subjected to high levels of CO2. A correlation has been developed relating volumetric O2 transfer coefficients, kLa, with the effective O2 diffusion coefficients, De, and the apparent viscosities, μapp, based on the results obtained in this study. The use of CO2 as a potent means for altering the rheological properties of culture broths and consequently improving the O2 transfer capabilities in penicillin fermentations was clearly demonstrated.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260381015
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  • 8
    Electronic Resource
    Electronic Resource
    Distribution of dispersed oil phase in hydrocarbon fermentations (1978)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 20 (1978), S. 465-485 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Recent experimental results show that the spreading coefficient frequently becomes positive when Candida lipolytica is cultivated on n-hexadecane. The effects of oil spreading at the surface of air bubbles in an airlift fermentor are examined using a mathematical model. The distribution of the oil phase with position and among the phases is determined using computer simulation. The simulation results qualitatively explain some of the experimental observations which have been previously reported.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260200402
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  • 9
    Electronic Resource
    Electronic Resource
    Measuring oxygen diffusion coefficients with polarographic oxygen electrodes. II. Fermentation Media (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1086-1092 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fermentation media consist of a large number of chemicals which composition undergoes alteration during the course of fermentations. In consequence, the conventional methods and correlations for gas diffusion coefficient measurement and prediction cannot be easily applied to such systems. Oxygen diffusion coefficients have been measured in simulated chemical systems as well as in complex solutions of nutrient broth, using the polarographic technique introduced in a previous article. It is identified that sugars and salts are the major factors influencing oxygen diffusion coefficients in these aqueous fermentation media. The effect of salts on oxygen diffusion coefficients in electrolyte solutions has been found to be well correlated with the square root of total ionic strength of electrolyte solutions. The individual effect of glucose and its combined effect with salts are explored in order to reach rational correlations capable of predicting oxygen diffusion coefficients in synthetic fermentation media. For aqueous solutions of glucose plus salts, it is observed that the log-additive relationship can be used to account for the combined effect. Finally, a linear correlation has been established in measuring oxygen diffusion coefficients in aqueous solutions having different concentrations of nutrient broth.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260280720
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  • 10
    Electronic Resource
    Electronic Resource
    Effects of microorganisms on effective oxygen diffusion coefficients and solubilities in fermentation media (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 32 (1988), S. 313-325 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Effective oxygen diffusion coefficients and solubilities were measured for submerged cultures of Saccharomyces cerevisiae, Escherichia coli, and Penicillium chrysogenum. Both effective oxygen diffusion coefficients and solubilities were found to decrease with increasing cell concentrations in the fermentation media. Comparison of the experimental results of effective oxygen diffusion coefficients in fermentation media with values theoretically predicted on the assumption of unpenetrable microbial cells indicates that oxygen molecules diffuse through the cells during the diffusion process. Within the cell concentration range of typical submerged fermentations, the effective oxygen diffusion coefficient of the fermentation media can be described as De = A1f + A2f2. In this equation, fis the cell volume fraction and both A1 and A2 are functions of the shape of the cells and the ratio of effective oxygen diffusion coefficient in microbial cells to that in the medium.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260320308
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