Growth characteristics of a Bombyx mori insect cell line in stationary and suspension cultures

The growth characteristics of the BM-5 insect cell line of Bombyx mori (silkworm) have been experimentally investigated in order to develop optimal growth protocols when these cells are used to produce large quantities of biopesticides or human proteins by recombinant baculoviruses. Experiments were performed in 2 mL wells and 200 mL spinner flasks. Spinner flasks were operated at 80 rpm with 0.3% methyl cellulose (MCL) added to the medium in order to protect the cells from liquid shear stress. In addition to the effect of agitation rate and amount of MCL added to the medium, the cell response during the adaptation to growth in suspension from stationary cultures is reported. Exposure of the cells to varying nutrient and metabolite concentrations is accomplished through batch and repeated-batch modes in 2 mL wells. The results imply that glutamine is a limiting nutrient and lactate has an inhibitory effect on cell growth. Ammonia depletion from the medium was accompanied by uric acid accumulation, suggesting that ammonia is converted to this metabolic product by the “uricotelic” and “nucleicolytic” metabolic pathways.     

Equilibrium conditions for methane hydrate formation in aqueous mixed electrolyte solutions

Equilibrium data on the formation of methane hydrate in six mixtures of NaCl and KCl, six mixtures of NaCl and CaCl₂ and a mixture of eight electrolytes found in sea water were experimentally obtained. The ionic strength (in molality units) of the NaCl and KCl mixtures ranged from 0.97 to 4.72 and that of the NaCl and CaCl₂ mixtures from 1.27 to 3.90. The experimental temperatures ranged from 264 to 284 K and the pressures from 2.5 to 9.7 MPa. Equilibrium pressures predicted using a recently proposed method (Englezos and Bishnoi, 1988) have been compared with the data obtained and it was found that the predictions match the data very well. The standard errors for the mixtures of NaCl and KCl, NaCl and CaCl₂ and the synthetic sea water were 5.54, 3.5 and 1.4%, respectively. The largest prediction error for an experimental data point was 10.1%.     

Modelling the internal flow structure of circulating fluidized beds

A simple hydrodynamic model for Circulating Fluidized Beds has been developed. The mathematical model, based on the core-annulus flow structure, is shown to be able to predict the two-phase flow characteristics and it requires only two measurable steady-state parameters, namely the experimental average voidage profile along the riser, or equivalently the pressure distribution, and the net solids circulation rate. The model has been successfully tested using recently obtained literature data covering a variety of reactor configurations and operating conditions.