in order to determine the best growing media for gerbera jamesonii under alkaline conditions, a factorial experiment was conducted with two factors, namely: (i) growing medium, and (ii) concentrations of bicarbonate (nahco3) in nutrient solution. results showed that increasing the concentration of nahco3 from 0 to 40 mm in nutrient solution significantly decreased plant growth, maximal quantum ...

The time it takes an enzyme to complete its reaction is a stochastic quantity governed by thermal fluctuations. With the advent of high-resolution methods of single-molecule manipulation and detection, it is now possible to observe directly this natural variation in the enzymatic cycle completion time and extract kinetic information from the statistics of its fluctuations. To this end, the inve...

We have constructed a plasmid expressing E. coli M1 RNA, the catalytic RNA subunit of ribonuclease P, under the control of a phage T7 promoter. The active M1 RNA species synthesized in vitro by T7 RNA polymerase from this vector was reacted with the tRNA(Gln) - tRNA(Leu) precursor RNA (Band K) encoded by phage T4. Only the tRNA(Leu) moiety of this dimeric precursor RNA contains the 3' terminal ...

Mn doped GaAs thin films were grown using molecular beam epitaxy at high and low substrate temperatures. The elemental concentration depth profiles in the thin films were determined by using Auger electron spectroscopy combined with ion etching. The Mn concentration is higher near the surface and then decreases with depth for films grown at high substrate temperatures. The Mn concentration prof...

Batch culture of Ralstonia eutropha using the recycled gas closed circuit culture system was conducted in order to develop a practical fermentation system for industrial autotrophic culture for poly (hydroxybutrate) production. The gas phase of the culture system consisted of substrate gas so that gases in this culture could be recycled as long as the amount of the gas consumed would be repleni...

a solid state fermentation method was used to utilize wheat straw as substrates for citric acid production by using aspergillus niger atcc 9142. the plackett burman design (pbd) of experiments was used to test the relative importance of the variables affecting production such as moisture content, age of spore, inoculum size, initial ph of substrate, methanol concentration, incubation temperatur...

Five control configurations for continuous bioreactors are analyzed using a simple model. A controller-independent measure, the partial disturbance gain, is used for evaluating their controllability with respect to disturbance rejection. The computation of the partial disturbance gain is generalized to the case with several uncontrolled outputs. At substrate-limited growth conditions, the conce...

Coupling between chemical reactions and transport phenomena can cause the substrate concentration at the surface of a membrane to be lower on the substrate-rich side than the substrate-lean side. Thus, the diffusing flux inside the membrane may be counter to the overall external concentration driving force. Graphical solutions of various steady states of such membranes are presented.