Biomedical subjects

F Kargi

Publications and source records attributed to F Kargi.

10 recordsLinked to original sources

PubMed2001

Salt inhibition kinetics in nitrification of synthetic saline wastewater.

Nitrification kinetics of synthetic saline wastewater was investigated by using an activated sludge unit. Initial experiments were performed with salt-free wastewater to obtain baseline information. Experiments with 3% salt concentration were performed at different sludge ages in order to investigate the system performance and salt inhibition effects on kinetic constants. Minimum sludge age required for complete nitrification increased from 12 days for salt-free wastewater to 25 days for 3% salt content. Salt inhibition was non-competitive type affecting both the maximum rate and the saturation constants. Inhibition constants were determined by using the experimental data as K(T1) = 200 g/liter and K(T2) = 7.4 g/liter. Further experiments were performed with salt concentrations between 0-5% to quantify variation of the rate and extent of COD removal with salt concentration. The rate and extent of nitrification decreased approximately 20% with 5% salt as compared to salt-free wastewater.

Journal Article↗

PubMed2000

Kinetics of sequential nitrification and denitrification processes.

Kinetics of nitrification and denitrification of synthetic wastewater was investigated by using two reactors in series. An activated sludge unit was used for nitrification followed by a downflow biofilter for denitrification. Glucose solution was fed to the denitrification column to supply carbon source. Reactors were operated at different operating conditions and data were collected for determination of kinetic constants. Experimental data indicated that nitrification and denitrification kinetics followed Monod kinetics. By using the experimental data, kinetic constants for nitrification were determined as k = 1.15 d(-1), K(N) = 5.14 mg/l, Y = 0.34 mgX/mgN and b = -0.021 d(-1). Similarly, kinetic constants for denitrification were determined as k = 0.23 d(-1) and K(DN) = 0.27 mg/l. Rates of nitrification and denitrification increased with increasing nitrogen loading rate.

Journal Article↗

PubMed1991

Biological responses of hybridoma cells to hydrodynamic shear in an agitated bioreactor.

Effects of long-term hydrodynamic shear on hybridoma cells were investigated in a 250-ml continuous stirred-tank reactor (CSTR). Cells grown at steady state were subjected to step changes in agitation rates. Cell viability, glucose consumption, and monoclonal antibody (MAb) production were determined at high agitation rates and compared with the control (100 rev min-1). Impeller tip speeds higher than 40 cm s-1 caused a significant drop in cell concentration and respiration activity, and increased lactate dehydrogenase (LDH) release to the culture medium. Also, high agitation speeds caused a decrease in MAb concentration and an increase in specific glucose consumption rate. The effects of dilution rate and serum concentration on the sensitivity of hybridoma cells to hydrodynamic shear were determined. Serum was found to protect the cells against shear damage and had a significant positive effect on hybridoma growth and MAb production. Shear damage on cells in CSTR was approximated to first-order kinetics. The death rate constant increased sharply at impeller tip speeds above 40 cm s-1.

Animals↗

PubMed1990

Growth and product inhibition kinetics of T-cell hybridomas producing lymphokines in batch and continuous culture.

The kinetics of growth and lymphokine formation by T-cell hybridomas were investigated in batch and continuous culture. Product inhibitions by ammonia and lactic acid were considered in the proposed model and experimental data were used to determine the kinetic and inhibition constants. The effect of dilution rate on specific substrate consumption and product formation rates was investigated.

Ammonia↗

PubMed1990

Transient behavior of T-cell hybridomas in response to changes in metabolite concentrations in continuous culture.

Effects of pulse and step changes in major metabolite concentrations such as glucose, glutamine, lactic acid, and ammonium on behavior of T-cell hybridomas in continuous culture were investigated in order to develop a strategy to maximize specific rate of lymphokine formation. Step increases in glucose, lactic acid, and ammonium concentrations decreased, and a step increase in glutamine concentration increased, the specific rate of lymphokine formation. Effects of step and pulse changes on specific rates of glucose and glutamine consumption and viability of cells were also investigated.

Ammonia↗

PubMed1990

Coiled tube membrane bioreactor for cultivation of hybridoma cells producing monoclonal antibodies.

A coiled tube membrane reactor was developed for the cultivation of mouse-mouse hybridoma cells producing monoclonal antibodies. The cell and antibody concentrations obtained in the membrane reactor were higher than that obtained in a batch spinner flask without a membrane. A mathematical model has been developed to describe the membrane transport coupled growth and product formation, and the physical and kinetic constants of the system were determined.

Animals↗

PubMed1982

Removal of Sulfur Compounds from Coal by the Thermophilic Organism Sulfolobus acidocaldarius.

The thermophilic, reduced-sulfur, iron-oxidizing bacterium Sulfolobus acidocaldarius was used for the removal of sulfur compounds from coal. The inclusion of complex nutrients such as yeast extract and peptone, and chemical oxidizing agents, 0.01 M FeCl(3) into leaching medium, reduced the rate and the extent of sulfur removal from coal. The rate of sulfur removal by S. acidocaldarius was strongly dependent on the sulfur content of the coal and on the total external surface area of coal particles. Approximately 96% of inorganic sulfur was removed from a 5% slurry of coal which had an initial total sulfur content of 4% and an inorganic (pyritic S and sulfate) sulfur content of 2.1%. This resulted in removal of 50% of initial total sulfur present in coal.

Journal Article↗

PubMedDate not supplied

Mass transfer effects in microencapsulated hybridoma cells producing monoclonal antibodies.

Rat-mouse and mouse-mouse hybridoma cell lines were used for formation of monoclonal antibodies (MAbs) in microcapsules of different sizes. Microcapsules were made of poly L-lysine-alginate hydrogel membranes. The effects of extracapsule liquid film, intracapsule and transmembrane transfer limitations of nutrients/products on system's performance were investigated. An agitation speed of 45 rpm (4 cm/s tip speed) was found to be optimal in spinner flasks to overcome liquid film resistances around capsules. Capsule sizes need to be reduced to smaller than 350 mu in order to eliminate intracapsule transfer limitations with a typical initial viable cell concentration of 0.5 x 10(5) viable cells/mL capsule. Double coating of capsules to improve strength of capsules resulted in higher transmembrane transfer resistances.

Animals↗

PubMedDate not supplied

Production of monoclonal antibodies by hybridoma cells in a flat sheet membrane bioreactor.

The purpose of this study was to investigate hybridoma growth and monoclonal antibody formation in a flat sheet membrane bioreactor. The effects of several different molecular weight cutoff membranes on growth and antibody formation were investigated. Nutrient and toxic product diffusion through the membranes were quantified, and the kinetic and physical constants of the system were determined.

Animals↗

PubMedDate not supplied

Indole alkaloid formation by Catharanthus roseus cells in a biofilm reactor.

Catharanthus roseus cells producing indole alkaloids were grown in the form of a biofilm. Production medium was circulated through the reactor parallel to the upper surface of the horizontal biofilm. Sugar consumption and indole alkaloid formation were followed to compare the performance of cultures with different biofilm thicknesses. Dissolved oxygen concentrations gradients within the biofilms were determined at the end of each run. RNA and protein content of the cells in the upper and lower layers of the the biofilms were compared. Results obtained in the biofilm experiments were compared to those obtained with suspension cultures. At optimized biofilm thicknesses, the biofilm reactor was more effective than suspension cultures in maximizing indole alkaloid titers. This is thought to be due to better cell-cell contact within the biofilm and nutrient concentration gradients, which resulted in low growth rates.

Agar↗