In order to determine the optimum technological parameters to extract gypenosides from Gynostemma pentaphyllum (Thunb.) Makino by using dynamic continuous countercurrent extraction,the single factor and orthogonal experiments were carried out in pilot scale test to observe the effect on extraction efficiency led by acting factors.The results showed that the optimum extraction condition were as follows:the temperature was 80 ℃,the ratio of material to solvent was 1∶35(g/mL) and the time was 50 min.In such conditions the yield of extract was 33.95% and the yield of gypenosides was 8.9%.The dynamic continuous countercurrent extraction has the advantages of better continuity,higher gypenosides yield and higher purity.
Tennis is a fashionable,elegant,and challenging movement,so it stimulates students'strong interests,and is loved by them.At the same time,tennis is highly technical,and requires students to master standardized technical movements.Among various methods of technical training in the physical education elective course of tennis,multi-ball training is the most common that is based on students'some previous technical skills.Training in the improvement stage is of special significance.This article is based on inadequacies of multi-ball training in universities'specialized course,and it introduces the role and importance of tennis ball training and analyzes students'forehand and backhand skills and scores of serving placement test of the elective course of tennis.Some advice is given too.
With I/O port of Singlechip C167CS simulating serial communication with PC,we can achieve many serial ports to meet our communication requirement.Including the subprogram of data collection,the subprogram of sending data,the subprogram of PC accepting data,and supply principle drawing of hardware.
The Pd-SiW12/SiO2 catalysts with different pore structure of SiO2 were prepared for direct oxidation of ethylene to acetic acid. The catalysts were characterized by X-ray diffraction, N, physical adsorption, infrared spectroscopy of adsorbed pyridine, and H-2-pulse chemical adsorption. The results showed that the pore structure of SiO2 had an important influence on the catalytic performance of the catalysts. The Pd-SiW12/SiO2 catalyst prepared by the SiO2 support with larger pore size and pore distribution exhibited the highest catalytic activity, on which 145.2 g/(L.h) of acetic acid yield was obtained. Pd dispersion was responsible for the catalytic activity of the Pd-SiW12/SiO2 catalyst.
The essential structure and the principle of continuous countercurrent extraction equipment on Chinese herbal medicine were introduced.The experiment on extraction effective components of Gynostemma pentaphyllum Makino was studied by water as solvent and G.pentaphyllum Makino as stuff.The key factors influencing extraction yield of wate-solubile matter and saponins,which including extracting temperature,ratio of liquid to solid and extracting time were investigated by using orthogonally experimental design.The results showed that the optimum condition were as follows: liquid to solid ratio 1∶35,temperature 80 ℃,time 50 min.Under these conditions,and the yield of extract was 33.95% and the yield of gypenosides was 8.9%.
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