ABSTRACT
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. (c) 1995 John Wiley & Sons, Inc.
ABSTRACT
Clearance calculations based on single sample determinations from 51Cr-EDTA samples 180 min after giving radioisotope showed a correlation coefficient of 0.992 to clearance calculations after multiple sampling of 51Cr-EDTA. The range of clearance determinations in 108 patients varied from 4 to 141 ml/min, 1.73 m2 BA. Twenty patients had clearance values below 20 ml/min, 1.73 m2 BA. Clearance calculations from single samples of iohexol from 180 min values showed a correlation coefficient of 0.986 to clearance calculations after multiple sampling of 51Cr-EDTA. These calculations were based on samples from 122 patients with clearance values varying from 4 to 139 ml/min, 1.73 m2 BA. No adverse reactions were registered during the study. This study confirms the reliability of single sample methods for clearance calculations at all levels of renal function.
