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1

Digitale Medien

Adaptive on-line model for aerobic Saccharomyces cerevisiae fermentation (1995)

von Schalien, Randolf ; Fagervik, Kaj ; Saxén, Björn ; [weitere]

New York, NY [u.a.] : Wiley-Blackwell

Biotechnology and Bioengineering 48 (1995), S. 631-638

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ISSN: 0006-3592

Schlagwort(e): Saccharomyces cerevisiae ; fermentation ; on-line simulation ; state estimation ; Chemistry ; Biochemistry and Biotechnology

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: In order to study and control fermentation processes, indirect on-tine measurements and mathematical models can be used. In this article we present a mathematical on-line model for fermentation processes. The model is based on atom and partial mass balances as well as on equations describing the acid-base system. The model is brought into an adaptive form by including transport equations for mass transfer and unstructured expressions for the fermentation kinetics. The state of the process, i.e., the concentrations of biomass, substrate, and products, can be estimated on-line using the balance part of the model completed with measurement equations for the input and output flows of the process. Adaptivity is realized by means of on-line estimation of parameters in the transport and kinetic expressions using recursive regression analysis. These expressions can thus be used in the model as valid equations enabling prediction of the process. This makes model-based automation of the process and testing of the validity of the measurement variables possible. The model and the on-line principles are applied to a 3.5-L laboratory tormentor in which Saccharomyces cerevisiae is cultivated. The experimental results show that the model-based estimation of the state and the predictions of the process correlate closely with high-performance liquid chromatography (HPLC) analyses. © 1995 John Wiley & Sons, Inc.

Zusätzliches Material: 7 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/bit.260480611

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2

Digitale Medien

Kinetics of chlorinated ethylene dehalogenation under methanogenic conditions (1995)

Skeen, Rodney S. ; Gao, Jianwei ; Hooker, Brian S.

New York, NY [u.a.] : Wiley-Blackwell

Biotechnology and Bioengineering 48 (1995), S. 659-666

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ISSN: 0006-3592

Schlagwort(e): methanogenic activity ; ethylene ; dechlorination ; Chemistry ; Biochemistry and Biotechnology

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Kinetics were determined for methanogenic activity and chlorinated ethylene dehalogenation by a methanol-enriched, anaerobic sediment consortium. The culture reductively dechlorinated perchloroethylene (PCE) to trichloroethylene (TCE), 1,1-dichloroethylene (1,1-DCE), vinylchloride (VC), and ethylene and ethane. The absence : of methanol or the addition of 2-bromoethanesulfonic. acid in the presence of methanol suppressed both methanogenic activity and dechlorination. In contrast, acetate production continued in the presence of 2-bromoethanesulfonic acid. These results suggest that dechlorination was strongly linked to methane formation and not to acetate production. A kinetic model, developed to describe both methanogenesis and dechlorination, successfully predicted experimentally measured concentrations of biomass, methane, substrate, and chlorinated ethylenes. The average maximum specific dehalogenation rates for PCE, TCE, 1,1-DCE, and VC were 0.9 ± 0.6, 0.4 ± 0.1, 12 ± 0.1, and 2.5 ± 1.7 μmol contaminant/ g. DW/day, respectively. This pattern for dechlorination rates is distinctly different than that reported for transition metal cofactors, where rates drop by approximately one order of magnitude as each successive chlorine is removed. The experimental results and kinetic analysis suggest that it will be impractical to targeting methanol consuming methanogenic organisms for in situ ground-water restoration. © 1995 John Wiley & Sons, Inc.

Zusätzliches Material: 4 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/bit.260480614

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3

Digitale Medien

Enhancement of antibody production by growth factor addition in perfusion and hollow-fiber culture systems (1995)

Omasa, Takeshi ; Kobayashi, Masaki ; Nishikawa, Toshio ; [weitere]

New York, NY [u.a.] : Wiley-Blackwell

Biotechnology and Bioengineering 48 (1995), S. 673-680

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ISSN: 0006-3592

Schlagwort(e): bovine serum albumin ; growth factor ; hollow-fiber culture ; perfusion culture ; antibody production rate ; Chemistry ; Biochemistry and Biotechnology

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: The effects of the high-molecular-weight growth factors, transferrin and bovine serum albumin (BSA), on antibody production were analyzed quantitatively in continuous hollow-fiber cultivation over a period of 60 days. Transferrin enhanced cell growth but had no significant effect on the specific antibody production rate, whereas BSA significantly enhanced antibody production. The antibody production rate was increased 4- and 14-fold respectively by feeding BSA at 2 and 5 g L-1 into the EC side of the system (the side connected to the cell-containing outer part of the hollow-fiber unit) compared with the production achieved without BSA. Addition of 5 g L1 BSA into the IC side of the system (the side connected to the inner part of the hollow-fiber unit) resulted in a 2.5-fold increase in the antibody production rate. The effect of BSA was also analyzed using the perfusion culture system with a separation unit. When fresh medium containing either 2 or 5 g L-1 BSA was fed into the reactor, both the specific growth rate and specific death rate increased, while the specific antibody production rate was increased 2- and 25-fold, respectively, by feeding BSA at these two concentrations compared with no addition. Comparing the two systems, the increase in the antibody production rate achieved with the hollow-fiber system was threefold greater than that in the perfusion culture system with the same concentration of BSA feeding. © 1995 John Wiley & Sons, Inc.

Zusätzliches Material: 9 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/bit.260480616

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4

Digitale Medien

Microstructural descriptors characterizing granular deposits (1992)

Tassopoulos, Menelaos ; Rosner, Daniel E.

Hoboken, NJ : Wiley-Blackwell

AIChE Journal 38 (1992), S. 15-25

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ISSN: 0001-1541

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Quantitative results are presented on mean coordination number and coordination number distribution, contact normal distribution and fabric tensor of simulated anisotropic granular deposits with resulting solid fractions between ca. 15% for ballistic deposits and 58%, corresponding to a random loose packing. The deposits, generated by the capture of uniform size spherical particles arriving normal to a target, were simulated using a simple algorithmic model.We focus on microstructural quantities which explicitly take into account the discrete nature of the granules comprising the deposit. Such measures are important in determining the heat transport properties of the deposits for Fourier conduction through the solid phase, as well as their mechanical and sintering properties. The variation of mean coordination number with deposit solid fraction was successfully correlated using a unit-cell model (Eq. 13). This correlation, in conjunction with entropy maximization arguments (after Nayak and Tien, 1978) has been further used to predict the coordination number distribution. The usefulness of the results reported here is illustrated by computing an upper bound to the deposit effective thermal conductivity (Jagota and Hui, 1990) and comparing it to both ‘exact’ simulation results (Tassopoulos and Rosner, 1991b) and experimental data (Koh, 1971).

Zusätzliches Material: 9 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/aic.690380103

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5

Digitale Medien

Computation of transition and molecular diffusivities in fibrous media (1992)

Melkote, Rajesh R. ; Jensen, Klavs F.

Hoboken, NJ : Wiley-Blackwell

AIChE Journal 38 (1992), S. 56-66

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ISSN: 0001-1541

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: The tortuosities of fibrous media in the heretofore unexplored transition and ordinary regimes are computed using a Monte Carlo scheme based on the Einstein equation for random walkers. The model structure is that of fully penetrable cylinders (FPC) in a unit simulation volume. The mean square displacement technique is combined with the first passage time distribution to accelerate the progress of the walkers at low Knudsen number. The results include the computation of transition regime transport coefficients for the first time. The calculated ordinary tortuosities are approximately equal to the reciprocal of the porosity over a wide range, while the transition tortuosities are shown to deviate from the reciprocal porosity with a simple dependence on Knudsen number. The limits of the transition regime are shown to correspond roughly to Knudsen numbers of 0.50 and 100, respectively. The calculated Knudsen tortuosities are shown to improve on earlier results obtained by the authors using a flux-based technique.

Zusätzliches Material: 10 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/aic.690380106

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6

Digitale Medien

Multiplicity features of adiabatic autothermal reactors (1992)

Lovo, Marianne ; Balakotaiah, Vemuri

Hoboken, NJ : Wiley-Blackwell

AIChE Journal 38 (1992), S. 101-115

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ISSN: 0001-1541

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Singularity theory, large activation energy asymptotics, and numerical methods are used to present a comprehensive study of the steady-state multiplicity features of three classical adiabatic autothermal reactor models: tubular reactor with internal heat exchange, tubular reactor with external heat exchange, and the CSTR with external heat exchange. Specifically, we derive the exact uniqueness-multiplicity boundary, determine typical cross-sections of the bifurcation set, and classify the different types of bifurcation diagrams of conversion vs. residence time. Asymptotic (limiting) models are used to determine analytical expressions for the uniqueness boundary and the ignition and extinction points. The analytical results are used to present simple, explicit and accurate expressions defining the boundary of the region of autothermal operation in the physical parameter space.

Zusätzliches Material: 16 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/aic.690380111

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7

Digitale Medien

Metals sorption by chelating polymers: A unique role of ionic strength (1992)

Sengupta, Arup K. ; Zhu, Yuewei

Hoboken, NJ : Wiley-Blackwell

AIChE Journal 38 (1992), S. 153-157

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ISSN: 0001-1541

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Zusätzliches Material: 5 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/aic.690380116

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8

Digitale Medien

Errata (1992)

Hoboken, NJ : Wiley-Blackwell

AIChE Journal 38 (1992), S. 318-319

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ISSN: 0001-1541

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Zusätzliches Material: 10 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/aic.690380224

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9

Digitale Medien

Kinetics of phenol oxidation in supercritical water (1992)

Thornton, Thomas D. ; Savage, Phillip E.

Hoboken, NJ : Wiley-Blackwell

AIChE Journal 38 (1992), S. 321-327

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ISSN: 0001-1541

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Aqueous solutions of phenol were oxidized in a flow reactor at temperatures between 300 and 420°C (0.89 ≤ Tr ≤ 1.07) and pressures from 188 to 278 atm (0.86 ≤ Pr ≤ 1.27). These conditions included oxidations in both near-critical and supercritical water. Reactor residence times ranged from 1.2 to 111 s. The initial phenol concentrations were between 50 and 330 ppm by mass, and the initial oxygen concentrations ranged from 0 to 1,100% excess. The oxidation experiments covered essentially the entire range of phenol conversions. Analysis of the kinetics data for phenol disappearance using a combination of the integral method and the method of excess revealed that the reaction was first order in phenol and 1/2 order in oxygen, and influenced by pressure. The global reaction order for water was taken to be nonzero, and the global rate constant was assumed to be independent of pressure so that the only effect of pressure was to alter the water concentration and hence the reaction rate. This approach led to a global reaction rate law that was 0.7 order in water and had a rate constant with an activation energy of 12.4 kcal/mol. The implications of these rate laws to the design of a commercial supercritical water oxidation reactor are also explored.

Zusätzliches Material: 7 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/aic.690380302

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10

Digitale Medien

Coking and activity of porous catalysts in supercritical reaction media (1992)

Baptist-Nguyen, Sarah ; Subramaniam, Bala

Hoboken, NJ : Wiley-Blackwell

AIChE Journal 38 (1992), S. 1027-1037

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ISSN: 0001-1541

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: A mathematical model is presented to describe coking and activity characteristics of porous catalysts in supercritical reaction mixtures. These characteristics are determined by the way in which temperature and pressure affect the simultaneous physicochemical rate processes involving the effective diffusion of reactants in the pore, coke formation, and coke extraction. For a parallel coking reaction, the model predicts that when the reaction mixture density is isothermally increased from subcritical to low-to-moderate values, the ensuing higher reaction rates and restricted diffusion lead to pore-mouth plugging and decreased catalyst effectiveness factors. At dense supercritical conditions, however, the enhanced coke solubilities in the reaction mixture alleviate pore-mouth restrictions, resulting in a recovery of catalyst activity and increased effectiveness factors. The model predicts an optimum supercritical density at which catalyst activity is maintained at a maximum value. At smaller than optimum density values, the reaction rate is limited by coke extraction and at larger than optimum values, the rate is subject to pore diffusion limitations. These predictions are qualitatively consistent with reported experimental observations.

Zusätzliches Material: 11 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/aic.690380706

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