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  • MATERIALS PROCESSING  (18)
  • Biochemistry and Biotechnology  (8)
  • Chemical Engineering  (5)
  • 1985-1989  (31)
  • 1
    Electronic Resource
    Electronic Resource
    Physical mechanisms of cell damage in microcarrier cell culture bioreactors (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 32 (1988), S. 1001-1014 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The negative effects of excessive agitation on tissue cells in microcarrier culture have often been ascribed to “shear.” Analysis of the fluid mechanics occurring suggests that there are actually three potential damage mechanisms: collisions of a cell-covered microcarrier with other beads, collisions with parts of the reactor (primarily the impeller), and interaction with turbulent eddies the size of the microcarrier beads. Review of the available quantitative information on agitation effects in cell cultures does not establish which mechanism is predominant; the range of experimental variables reported emphasizes power input over the other reactor and impeller parameters. The bead-bead collision model is tentatively supported by the available data, but the other mechanisms may still be significant in some systems. The formation of bead aggregates by cellular bridging provides a parallel means of damaging cells. Breaking of these bridges by any of the three means identified earlier can cause cell destruction and/or the net transfer of cells to formerly bare beads. High concentrations of bridges are favored by lower agitation rates, presumably because the bridges are not as quickly destroyed after formation.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260320808
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  • 2
    Electronic Resource
    Electronic Resource
    Diffusion and solid dissolution/precipitation in permeable media (1989)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 35 (1989), S. 1057-1072 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We have developed an analytical solution which describes mineral zonation caused by diffusion in permeable media. For a semiinfinite domain, the species conservation equations transform into ordinary differential equations that yield a closed-form solution. The solution exhibits shock dissolution/precipitation fronts and gradual (nonshock) precipitation fronts. The solution can exhibit regions (gaps) containing no reactive solids which separate moving dissolution and precipitation fronts. The analysis is, in principle, extendable to include intraaqueous reactions, although the mathematics quickly becomes intractable.Numerical simulation exhibits all of the features of the more restricted analytical solution and is in good agreement with the data on hydroxyapatite dissolution taken by Kim and Cussler (1987).
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690350702
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  • 3
    Electronic Resource
    Electronic Resource
    Modeling of contact-inhibited animal cell growth on flat surfaces and spheres (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 33 (1989), S. 300-305 
    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 model of contact-inhibited growth of cells on flat and spherical surfaces is presented. It shows that contact inhibition does not significantly affect the calculated growth rate of cells unless they are allowed to multiply a large amount from the original seeding density. Microcarriers seeded at low densities require long times to reach confluence because contact inhibition becomes important. In systems with both growth and separate cell death, the equilibrium fraction of holes in the confluent monolayer is below 8% if the death rate is less than half the growth rate, but increases rapidly as the death rate increases from that value.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260330308
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  • 4
    Electronic Resource
    Electronic Resource
    Molecular thermodynamics of aqueous two-phase systems for bioseparations (1988)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 34 (1988), S. 1585-1594 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Aqueous polymer-polymer two-phase systems provide a powerful method for separating biomolecules by extraction. When a complex mixture of biomolecules (e.g., a fermentation broth or a solution of lysed cells) is added to such a system, biomolecules partition uniquely between the two phases, achieving separation.A thermodynamic framework is presented for optimizing extraction performance in biological separations. First, a molecular-thermodynamic model, based on the osmotic virial equation, is proposed to describe phase equilibria for dilute aqueous mixtures containing polymers and protein. Second, experimental phase-equilibrium data (protein partition coefficients) are reported for a number of model proteins including albumin, lysozyme, and α-chymotrypsin. To interpret and correlate the experimental data, Low-Angle Laser-Light Scattering (LALLS) measurements were made to determine osmotic second virial coefficients for aqueous mixtures containing polymers, proteins, salts (KCl, KH2PO4 and K2SO4 at concentrations of 50 and 100 mM) and several combinations of polymer-polymer and polymer-protein pairs. Combined with electrochemical measurements (differences in potential between the two phases and protein net charge), these data provide parameters for the model to calculate the desired phase equilibria. A comparison of calculated and experimental results indicates that the virial-equation model provides good prediction of binodals and a reliable basis for estimating infinite-dilution protein partition coefficients for biotechnical process design.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690341002
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  • 5
    Electronic Resource
    Electronic Resource
    Rule-based mineral sequences in geochemical flow processes (1988)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 34 (1988), S. 1607-1614 
    Details
    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 infiltration of an aqueous solution into a permeable medium generally results in the dissolution of some of the minerals initially present and the possible precipitation of others. When the infiltration velocities are small, as is the case for many natural processes, conditions of local equilibrium apply and the dissolution and precipitation processes exhibit a wave-type behavior reminiscent of chromatogrphic fronts. Zones of constant composition (state) will be separated by narrow regions within which the aqueous and solid phase concentrations exhibit sharp changes. Because of this wave-like structure, an algebraic solution of the coupled material balance equations exists, but in a form that involves a trial and error solution procedure which has heretofore discouraged its application. This paper describes the essence of a scheme which uses a combination of graph theory and heuristics to minimize trials and thereby render the algebraic solution practical. The scheme offers an alternative to time-sequencing solutions (e.g., finite difference) of the set of partial differential equations.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690341004
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  • 6
    Electronic Resource
    Electronic Resource
    A system for automated DNA electrophoresis, molecular hybridization and electronic detection: I Electrophoresis and hybridization (1987)
    Weinheim : Wiley-Blackwell
    Electrophoresis 8 (1987), S. 255-261 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: We have designed and constructed a computer-controlled, fully automated system for Southern-type nucleic acid hybridization analysis. Restriction enzyme digests of DNA are placed into sample wells of the gel contained on a nine-fingered plastic frame. The 32-labeled probe is loaded into the hybridization chamber. Instructions for all the subsequent steps in the fully automated process are specified by the operator's answers to questions which appear on the computer screen at the start of the experiment. The system performs horizontal submarine electrophoresis. An adjustable endpoint detector concludes electrophoresis. Automatic voltage/temperature feedback control maintains maximum allowable voltage while keeping the temperature constant. Following electrophoresis a robot arm moves the gel frame from station to station. The system then affixes the separated fragments to a solid phase matrix, denatures, neutralizes, hybridizes, washes, dries and detects the 32 P according to the specifications preprogrammed by the operator. The results, printed out by the computer, give a plot of radioactivity versus distance from the origin for each of the nine simultaneous hybridizations.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150080602
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  • 7
    Electronic Resource
    Electronic Resource
    Analysis of free zone electrophoresis of fixed erythrocytes performed in microgravity (1985)
    Weinheim : Wiley-Blackwell
    Electrophoresis 6 (1985), S. 3-9 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A free fluid zone electrophoresis experiment was performed in the microgravity environment of Space Shuttle flight STS-3 (March 1983). The experiment was designed to confirm observations made on the Apollo-Soyuz mission of 1975 and to test the effect of high red blood cell (RBC) concentration on free fluid electrophoresis. Photographic documentation of cell zone progression in one-hour separations of mixtures of formaldehyde-fixed human and rabbit erythrocytes (RBC), which were subjected to a field of approximately 13 V cm-1 in low ionic strength buffer, was analyzed. One of two columns contained 2 × 108 RBC ml-1 (low concentration), and the other contained 1 × 109 RBC ml-1 (high concentration). The observed and calculated leading edge displacements of the RBC in the two columns were in agreement, indicating the absence of unexpected effects of the reduced gravity environment. Post-flight analyses of the contents of the columns was not possible, and additional microgravity experiments are needed to evaluate the role of particle-particle interactions in concentrated suspensions undergoing electrophoresis.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150060103
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  • 8
    Electronic Resource
    Electronic Resource
    Rapid mechanical versus conventional acid fixation in electrophoresis (1985)
    Weinheim : Wiley-Blackwell
    Electrophoresis 6 (1985), S. 191-192 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: We have devised methodology which allows for the rapid mechanical fixation of proteins in polyacrylamide slab gels. Proteins so fixed remain in the gel even after four days of soaking. The potential utility of this approach is discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150060411
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of conductivity and concentration on the sample stream in the transverse axis of a continuous flow electrophoresis chamber (1985)
    Weinheim : Wiley-Blackwell
    Electrophoresis 6 (1985), S. 377-381 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The resolution of continuous flow electrophoresis systems is generally measured by the spread of the sample bands in the direction of the electrophoretic migration. This spreading assumes an electric field that extends uniformly between the two electrodes. This paper evaluates the cross-section of the sample bands in the plane perpendicular to the flow and shows that the spread in the direction perpendicular to the migration increased significantly with the applied electic field. Concentrated samples of monodisperse latex particles and vinyltoluene T-butylstyrene particles in sample buffers of different electrical conductivities were used to map the shape of the sample bands relative to the zero electric field case. As the electric field was applied, the sample band spread from an initial diameter of only one-third the chamber thickness until it approached the chamber walls where electroosmosis significantly reduced the resolution of separation. It can be shown, however, that it is possible to minimize these distortions by careful sample preparation and experiment design.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150060805
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  • 10
    Electronic Resource
    Electronic Resource
    On the relationship of amino acid composition to silver staining of proteins in electrphoresis gels (1986)
    Weinheim : Wiley-Blackwell
    Electrophoresis 7 (1986), S. 327-332 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Development of techniques for silver staining of proteins separated by polyacrylamide gel electrophoresis has increased experimental detection limits. However, the precise basis for the reaction between silver and polypeptides is still unclear and, depending upon the choice of silver reagent, may even differ. We compared protein stain intensity with silver diamine (ammoniacal silver) and silver nitrate reagents based on amino acid composition by determining the protein amount required to generate an arbitrary staining intensity and then calculating moles of each amino acid present in some representative proteins. We compared these values for each amino acid, taken singly, as well as for combinations of two and more. In no case could staining be attributed entirely to specific or classes of amino acids, thus supporting the argument that an inherent difference exists between primary reactive centers for the two staining reagents.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150070708
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