Biomedical subjects

M N Karim

Publications and source records attributed to M N Karim.

3 recordsLinked to original sources

PubMed1998

Adaptive pole placement control algorithm for DO-control in beta-lactamase production.

The dissolved oxygen (DO) is an important variable in aerobic fermentations and affects the cell growth and product formation. Dissolved oxygen control is difficult in batch fermentations because of the time-varying conditions, time delays, and the probe dynamics. Modeling of the various patterns of biological activity in fermentations and their impact on the DO process dynamics is essential to both achieve a satisfactory control and to track the aforementioned patterns. An adaptive pole placement algorithm with time-delay compensation was used for controlling the DO, coupled with system identification using recursively estimated autoregressive models with exogeneous inputs (ARX). The flow rate of O2 in a constant flow rate gas inlet mixture is used as the manipulated variable. Supervision and coordination techniques are applied to improve the control performance. The control performance is affected by the accuracy of the model prediction and the selected time delay. The effect of DO level on the productivity of beta-lactamase using Bacillus subtilis under oxygen-limited conditions is investigated. Beta-lactamase stability is improved under prolonged growth conditions with low DO levels.

Aerobiosis↗

PubMed1992

Artificial neural networks in bioprocess state estimation.

The application of artificial neural networks to the estimation and prediction of bioprocess variables is presented in this paper. A neural network methodology is discussed, which uses environmental and physiological information available from on-line sensors, to estimate concentration of species in the bioreactor. Two case studies are presented, both based on the ethanol production by Zymomonas mobilis. An efficient optimization algorithm which reduces the number of iterations required for convergence is proposed. Results are presented for different training sets and different training methodologies. It is shown that the neural network estimator provides good on-line bioprocess state estimations.

Biomedical Engineering↗

PubMed1988

An analysis of sugar content of commonly used pediatric liquid medicines--its relevance to dentistry.

The sugar content of twenty-four liquid medicines commonly prescribed for infants and young children were measured and the type of sugars present were also identified in four randomly selected samples. All the liquid medicines tested contained sugar, in the range of 29.4% to 61.2%. Sucrose appeared to be the most commonly used sugar. Whilst it is agreed that sucrose makes the medicine more acceptable to children, its continual use by the pharmaceutical industry should be discontinued due to its harmful effect on the dental health of children, particularly those taking these syrup-based medicines on prolonged basis. Sugar-free alternatives such as sorbitol or saccharin should be used instead.

Carbohydrates↗