Development of circumference oscillation mechanism with adjustable amplitude
According to the situation of the currently developed circumference oscillation mechanism without adjustable amplitude generally. The circular oscillation mechanism with adjustable amplitude is designed. It mainly comprises an eccentric motion mechanism and adaptive dynamic balance mechanism. The dynamic simulation and analysis is carried out on eccentric motion mechanism. The experimental results show it can achieve 0-Φ50mm adjustable amplitude and 20-350RPM adjustable oscillation frequency in the meantime, and the latter can be realized by changing eccentricity adjusting pin manually. The unbalance quality of the table can be compensated by adaptive dynamic balance mechanism in order to increase the die life. Its amplitude can be changed simply, conveniently and fast, and has the characteristics of simple and compact mechanism, rigid connection, strong bearing capacity and maintenance easily. It will be widely used in the field of biological engineering.
Recent advances in bioreactor and its engineering
The engineering methodologies and key technologies for the bioreactor design and the scale-up were discussed.The development trends in bioreactors for the production of biotechnology products were described,including a bioreactor system focusing on metabolic flux detection and analysis,the improved stirred-tank bioreactor based on computational fluid dynamics,microbioreactor,bioreactor for mammalian cell,and enzymatic bioreactor.
First-pass effect of norethindrone in rabbits and rats.
The influence of the route of administration on the pharmacokinetics of the synthetic progestogen norethindrone was studied in the rabbit and rat. In the rabbit, the area under the curve (AUC) after oral administration was 54% of that after i.v. administration. In the rat, the AUC after administration into the hepatic portal vein was 32% of AUCi.v.; after oral administration the AUCoral was 13.7% of AUCi.v. and 57.6% of AUCportal. Therefore, in both the rabbit and rat norethindrone is subject to a first-pass effect. Using the technique of constant withdrawal of blood from the hepatic portal vein after drug administration into the gastrointestinal tract, it was shown the norethindrone is metabolized in the gut wall. Hence, in the rat at least, there are both intestinal and hepatic components of the overall first-pass effect. In addition, increasing the time of intraportal injection from 15 sec to 2 min (thereby reducing the rate of drug delivery to the liver) resulted in the AUC being reduced by 40%. Dose-dependent kinetics were observed with doses of norethindrone greater than 500 microgram/kg.