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  • 1
    Electronic Resource
    Electronic Resource
    State estimators (observers) for the on-line estimation of non-measurable process variables
    Amsterdam : Elsevier
    Trends in Biotechnology 7 (1989), S. 205-209 
    Details
    ISSN: 0167-7799
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0167-7799(89)90105-4
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  • 2
    Electronic Resource
    Electronic Resource
    Production of extracellular inulinase in high-cell-density fed-batch cultures of Kluyveromyces marxianus (1994)
    Springer
    Applied microbiology and biotechnology 42 (1994), S. 516-521 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The production of extracellular inulinase (\-1,2-d-fructan fructanohydrolase, EC 3.2.1.7) was studied in fed-batch cultures of the yeast Kluyveromyces marxianus CBS 6556 at 30 and at 40° C. At both temperatures, the final biomass concentration exceeded 100 g·l−1 and more than 2 g enzyme. L−1 of culture supernatant was produced. The biomass yield on O2 at 40° C was substantially lower than at 30°C. Nevertheless, at 40° C a growth rate of 0.20 h−1 could be maintained for a longer period than at 30° C. The unexpected higher O2-transfer rate at 40°C is probably due to a lower viscosity of the culture broth. The 40°C fermentation took only 33 h as compared to 42 h at 30° C. These results indicate that K. marxianus is a promising host for the extracellular production of heterologous proteins under the control of the inulinase promoter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173914
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  • 3
    Electronic Resource
    Electronic Resource
    Production of extracellular inulinase in high-cell-density fed-batch cultures of Kluyveromyces marxianus (1994)
    Springer
    Applied microbiology and biotechnology 42 (1994), S. 516-521 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The production of extracellular inulinase (β-1,2-d-fructan fructanohydrolase, EC 3.2.1.7) was studied in fed-batch cultures of the yeast Kluyveromyces marxianus CBS 6556 at 30 and at 40°  C. At both temperatures, the final biomass concentration exceeded 100 g·l – 1 and more than 2 g enzyme. L– 1 of culture supernatant was produced. The biomass yield on O2 at 40°  C was substantially lower than at 30°  C. Nevertheless, at 40°  C a growth rate of 0.20 h – 1 could be maintained for a longer period than at 30°  C. The unexpected higher O2-transfer rate at 40°  C is probably due to a lower viscosity of the culture broth. The 40°  C fermentation took only 33 h as compared to 42 h at 30°  C. These results indicate that K. marxianus is a promising host for the extracellular production of heterologous proteins under the control of the inulinase promoter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530050287
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  • 4
    Electronic Resource
    Electronic Resource
    Linear constraint relations in biochemical reaction systems: II. Diagnosis and estimation of gross errors (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 11-20 
    Details
    ISSN: 0006-3592
    Keywords: conservation equations ; linear constraints ; data reconciliation ; balancing technique ; gross error detection ; error diagnosis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Conservation equations derived from elemental balances, heat balances, and metabolic stoichiometry, can be used to constrain the values of conversion rates of relevant components. In the present work, their use will be discussed for detection and localization of significant errors of the following types: 1.At least one of the primary measurements has a significant error (gross measurement error).2.The system definition is incorrect: a component a.is not included in the system description.b.has a composition different from that specified.3.The specified variances are too small, resulting in a too-sensitive test.The error diagnosis technique presented here, is based on the following: given the conservation equations, for each set of measured rates, a vector of residuals of these equations can be constructed, of which the direction is related to the error source, as its length is a measure of the error size. The similarity of the directions of such a residual vector and certain compare vectors, each corresponding to a specific error source, is considered in a statistical test. If two compare vectors that result from different error sources have (almost) the same direction, errors of these types cannot be distinguished from each other. For each possible error in the primary measurements of flows and concentrations, the compare vector can be constructed a priori, thus allowing analysis beforehand, which errors can be observed. Therefore, the detectability of certain errors likely to occur can be insured by selecting a proper measurement set. The possibility of performing this analysis before experiments are carried out is an important advantage, providing a profound understanding of the detectability of errors. The characteristics of the method with respect to diagnosis of simultaneous errors and error size estimation are discussed and compared to those of the serial elimination method and the serial compensation strategy, published elsewhere. © 1994 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260430104
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  • 5
    Electronic Resource
    Electronic Resource
    Linear constrain relations in biochemical reaction systems III. Sequential application of data reconciliation for sensitive detection of systematic errors (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 44 (1994), S. 781-791 
    Details
    ISSN: 0006-3592
    Keywords: error diagnosis ; filtering technique ; data reconciliation ; measurement error detection ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This article presents a method to test the presence of relatively small systematic measurement errors; e.g., those caused by inaccurate calibration or sensor drift. To do this, primary measurements - flow rates and concentrations - are first translated into observed conversions, which should satisfy several constraints, like the laws of conservation of chemical elements. This study considers three objectives: 1.Modification of the commonly used balancing technique to improve error sensitivity to be able to detect small systematic errors. To this end, the balancing technique is applied sequentially in time.2.Extension of the method to enable direct diagnosis of errors in the primary measurements instead of diagnosing errors in the observed conversions. This was achieved by analyzing how individual errors in the primary measurements are expressed in the residual vector.3.Derivation of a new systematic method to quantitatively determine the sensitivity of the error, is that error size at which the expected value of the chisquare test function equals its critical value.The method is applied to industrial data demonstrating the effectiveness of the approach. It was shown that, for most possible error sources, a systematic errors of 2% to 5% could be detected. In given application, the variation of the N-content of biomass was appointed to be the cause of errors. © 1994 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260440703
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  • 6
    Electronic Resource
    Electronic Resource
    An efficient model development strategy for bioprocesses based on neural networks in macroscopic balances (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 54 (1997), S. 549-566 
    Details
    ISSN: 0006-3592
    Keywords: hybrid models ; neural networks ; penicillin G ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In the serial gray box modeling strategy, generally available knowledge, represented in the macroscopic balance, is combined naturally with neural networks, which are powerful and convenient tools to model the inaccurately known terms in the macroscopic balance. This article shows, for a typical biochemical conversion, that in the serial gray box modeling strategy the identification data only have to cover the input-output space of the inaccurately known term in the macroscopic balances and that the accurately known terms can be used to achieve reliable extrapolation. The strategy is demonstrated successfully on the modeling of the enzymatic (repeated) batch conversion of penicillin G, for which real-time results are presented. Compared with a more data-driven black box strategy, the serial gray box strategy leads to models with reliable extrapolation properties, so that with the same number of identification experiments the model can be applied to a much wider range of different conditions. Compared to a more knowledge-driven white box strategy, the serial gray box model structure is only based on readily available or easily obtainable knowledge, so that the development time of serial gray box models still may be short in a situation where there is no detailed knowledge of the system available. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 53: 549-566, 1997.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Linear constraint relations in biochemical reaction systems: I. Classification of the calculability and the balanceability of conversion rates (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 3-10 
    Details
    ISSN: 0006-3592
    Keywords: data reconciliation ; balancing ; classification ; observability ; redundancy ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Measurements provide the basis for process monitoring and control as well as for model development and validation. Systematic approaches to increase the accuracy and credibility of the empirical data set are therefore of great value. In (bio)chemical conversions, linear conservation relations such as the balance equations for charge, enthalpy, and/or chemical elements, can be employed to relate conversion rates. In a pactical situation, some of these rates will be measured (in effect, be calculated directly from primary measurements of, e.g., concentrations and flow rates), as others can or cannot be calculated from the measured ones. When certain measured rates can also be calculated from other measured rates, the set of equations, the accuracy and credibility of the measured rates can indeed be improved by, respectively, balancing and gross error diagnosis. The balanced conversion rates are more accurate, and form a consistent set of data, which is more suitable for further application (e.g., to calculate nonmeasured rates) than the raw measurements. Such an approach has drawn attention in previous studies. The current study deals mainly with the problem of mathematically classifying the conversion rates into balanceable and calculable rates, given the subset of measured rates. The significance of this problem is illustrated with some examples. It is shown that a simple matrix equation can be derived that contains the vector of measured conversion rates and the redundancy matrix R. Matrix R plays a predominant role in the classification problem. In supplementary articles, significance of the redundancy matrix R for an improved gross error diagnosis approach will be shown. In addition, efficient equations have been derived to calculate the balanceable and/or calculable rates. The method is completely based on matrix algebra (principally different from the graph-theoretical approach), and it is easily implemented into a computer program. © 1994 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260430103
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