Reduction micro-biological

Enantiomeric norethisterone and ethynodiol diacetate, obtained from ent-(305), have been shown to be devoid of gestagenic activity, although a small but significant block of oestradiol-induced uterine growth occurs with enr-oestradiol. In comparison with 19-nortestosterone, which is reduced micro-biologically with Mycobacterium smegmatis to AB-trans-fused-5a-products, cnr-19-nortestosterone suffers reduction, in high yield, to AB-cis-fused SP-derivatives. 

The flow rate and concentration of wastewater do not remain constant but vary during the course of the day and are also dependent on the time of year. If the flow rate is too high, loss of micro-organisms by washout may occur in secondary treatment processes. If the flow rate is too low, then the lack of nutrients will lead to a reduction of the micro-organism population. Wastewaters entering a treatment plant usually flow first into an equalisation basin, so that the flow rate out of the basin is maintained constant, or between prescribed limits, to protect the subsequent processes. The equalisation tank also reduces the effect of toxic shocks on the biological processes within the main treatment plant. 

The activated sludge process, depicted in Fig. 1, involves basically the aeration and agitation of an effluent in the presence of a flocculated suspension of micro-organisms which are supported on particulate organic matter. After a predetermined residence time (usually several hours) the effluent is passed to a sedimentation tank where the flocculated solids are separated from the treated liquid. A reduction of BOD from 250-350 mg IT1 to a final value of 20 mg L-1 is achieved under typical operating conditions. Part of the settled sludge is usually recycled to the aeration tank in order to maintain biological activity. 

Biological contamination of the sample can occur where sampling devices have not been sterilised. External bacterial contamination and microbial activity present in the sample could combine to degrade existing macromolecules. Chemical transformations such as methylation, cleavage of the carbon-metal bond, and reduction of the metal have occurred in the presence of micro-organisms (Thayer and Brinkman, 1984 Thayer, 1984 Krishnamurthy, 1992) as shown by the following equations ... 

The bioavailability of a poorly water-soluble drug is often limited by its dissolution rate, which in turn is controlled by the surface area available for dissolution. The effect of the particle size of a drug on its dissolution rate and its biological activity is well known. For example, Atkinson et al. reported that micro-nization of griseofulvin resulted in reduction of the therapeutic dose by half. 

Oxygen concentration is determined electrochemically using a membrane oxygen electrode (Clark sensor). Oxygen is consumed by micro-organisms, and the reduction in oxygen consumption with time is a measure of biological activity. 

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