ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 59 (1998), S. 451-460 
    ISSN: 0006-3592
    Keywords: protein fouling ; membrane transport ; ultrafiltration ; adsorption ; filtration ; composite membrane ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Protein fouling can significantly alter both the flux and retention characteristics of ultrafiltration membranes. There has, however, been considerable controversy over the nature of this fouling layer. In this study, hydraulic permeability and dextran sieving data were obtained both before and after albumin adsorption and/or filtration using polyethersulfone ultrafiltration membranes. The dextran molecular weight distributions were analyzed by gel permeation chromatography to evaluate the sieving characteristics over a broad range of solute size. Protein fouling caused a significant reduction in the dextran sieving coefficients, with very different effects seen for the diffusive and convective contributions to dextran transport. The changes in dextran sieving coefficients and diffusive permeabilities were analyzed using a two-layer membrane model in which a distinct protein layer is assumed to form on the upstream surface of the membrane. The data suggest that the protein layer formed during filtration was more tightly packed than that formed by simple static adsorption. Hydrodynamic calculations indicated that the pore size of the protein layer remained relatively constant throughout the adsorption or filtration, but the thickness of this layer increased with increasing exposure time. These results provide important insights into the nature of protein fouling during ultrafiltration and its effects on membrane transport. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:451-460, 1998.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 1151-1154 
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chlorinated and oxygenated cyclohexene derivatives detected in methylene chloride extracts of chlorinated drinking water were demonstrated to be artifacts produced during sample preparation. Commercial methylene chloride contains cyclohexene as a preservative, and this reacted during the extraction/concentration process to produce microgram amounts of chlorocyclohexene, 2-chlorocyclohexanol, trans-1,2-dichlorocyclohexane, cyclohexenone and cyclohexenol. Quantitative analysis indicated that over 90% of the initial cyclohexene was consumed during the process. Dechlorination of drinking water with sodium arsenite significantly reduced but did not eliminate cyclohexene artifact formation.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 36 (1990), S. 1141-1150 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Based on the well-known mechanism describing Michaelis-Menten kinetics, three rate expressions may be developed: the exact solution (Model 1), a rate equation resulting from the pseudo-steady-state assumption (Model 2), and Model 2 with the additional assumption that the amount of free substrate is approximately equal to the total amount of substrate (Model 3). Although Model 1 is the most precise, it must be integrated numerically and it requires three experimentally determined parameters. Models 2 and 3, however, are simpler and require only two parameters. Using dimensionless forms of the three models, we have evaluated the errors in the two simplified models relative to the exact solution using a wide range of parameter values. The choice of model for reactor design depends on the initial substrate to enzyme ratio (α0), and on the ratio of the Michaelis-Menten constant to the enzyme concentration (σ). Based on a 2% model error criteria, when α0 〉 15 or σ ≥ 100, Model 3 is adequate; if 5 〈 α0 〈 15, or if σ ≥ 10, then Model 2 may be used; and if α0 〈 5 and σ 〈 10, then the exact solution (Model 1) is required.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 31 (1993), S. 883-886 
    ISSN: 0749-1581
    Keywords: Aluminum-27 ; Gallium-71 ; Aluminosilicates ; Aluminophosphates ; Aluminas ; Gallosilicates ; Gallophosphates ; Gallias ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A linear relationship has been found to exist between the aluminum-27 and gallium-71 NMR chemical shifts of a series of structurally analogous aluminum and gallium compounds having only oxygen in the first metal coordination spheres; δ71Ga = 2.83(δ27Al) - 4.50. This relationship allows the prediction of 71Ga chemical shifts for such gallium compounds from the 27Al values already known for their aluminum analogues, and also a greater understanding of observed 71Ga chemical shifts.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...