An efficient method for the isolation and purification of 12,13-dihydroxyeuparin from Radix Eupatorii Chinensis by high speed counter-current chromatography (HSCCC) was established in this paper. The ether extracts of...An efficient method for the isolation and purification of 12,13-dihydroxyeuparin from Radix Eupatorii Chinensis by high speed counter-current chromatography (HSCCC) was established in this paper. The ether extracts of Radix Eupatorii Chinensis were purified by HSCCC with a solvent system of hexyl hydride-ethyl acetate-methanol-water (1:2:1:2, v/v/v/v). The upper phase was used as the stationary phase and the lower phase as the mobile phase. About 8.4 mg of 12, 13-dihydroxyeuparin was obtained from 200 mg of ether extracts from Radix Eupatorii Chinensis in one-step HSCCC separation, with the purity of 96.71%, as determined by HPLC. After methanol- water recrystallization, the purity of 12,13-dihydroxyeuparin reached 99.83%. Such a simple and effective method was fairly useful to prepare pure compound as reference substances for related study on Radix Eupatorii Chinensis.展开更多
Coptis chinensis Franch, a widely used Traditional Chinese Medicine, shows various kinds of bioactivity. The major active components of the herb are considered to be alkaloids. Thus, preparative separation of these al...Coptis chinensis Franch, a widely used Traditional Chinese Medicine, shows various kinds of bioactivity. The major active components of the herb are considered to be alkaloids. Thus, preparative separation of these alkaloids is critical important for further pharmacology and mechanism studies. In the paper, five alkaloids from C. chinensis were purified by HSCCC using the solvent system composed of chloro-form-metha- nol-water (2:1:1, v/v/v) single prepared. The content of each solvent in solvent system were determined by gas chromatography (GC), then according the ratios of solvents in each phase to prepare the mobile and stationary phase respectively. And a comparative study was carried out between together preparation and single preparation of the solvent system. The purities and recoveries of all the products were over 98.5% and 92%. However, 134 mL chloroform, 336 mL methanol and 452 mL water were saved when the two phase were singled by GC. Our research showed an economical method for separating alkaloids from C. chinensis by HSCCC using the solvent system single prepared by GC.展开更多
A multi-try counter-meshing gears stronglink based on micro electromechanical system （MEMS） technology is introduced, including research, design, couple and fabrication of unique signal （UQS） for some specified fi...A multi-try counter-meshing gears stronglink based on micro electromechanical system （MEMS） technology is introduced, including research, design, couple and fabrication of unique signal （UQS） for some specified fields of information security. The stronglink consists of two groups of metal counter-meshing gears, two pawl/ratchet mechanisms, two driving micromotors and two resetting micromotors. The resetting micromotors make counter-meshing gears withdraw by raising pawls so that the interfered counter-meshing gears will be relieved. The energy-coupling element is a photoelectric sensor with a circular notched plate. The counter-meshing mechanism is fabricated using the ultraviolet-lithographie~ galvanoformung and abformung （UV-LiGA） process and a precision mechanical technique. The stronglink can be tried several times if the correct resetting code is known.展开更多
光伏发电并网规模持续增长,改变了电力系统大扰动后的动态特性。文章建立了计及低电压穿越(Low Voltage Ride Through,LVRT)功能的光伏发电系统机电暂态仿真模型。针对故障后联系阻抗显著增大的光伏弱交流并网系统,分析了光伏低电压穿...光伏发电并网规模持续增长,改变了电力系统大扰动后的动态特性。文章建立了计及低电压穿越(Low Voltage Ride Through,LVRT)功能的光伏发电系统机电暂态仿真模型。针对故障后联系阻抗显著增大的光伏弱交流并网系统,分析了光伏低电压穿越的恢复过程对系统行为特性的影响,揭示了因光伏频繁进入LVRT引起系统电压周期性振荡的机制,分析了相关影响因素,并提出了缓解应对措施。最后,面向西藏中部光伏高渗透实际电网,仿真复现了大扰动后系统振荡现象,验证了应对措施的有效性。展开更多
基金supported by the International Scientific and Technological Cooperation Program of China (no.2009DFA31230)the Industry-University-Research Cooperation Program from Science and Technology Department of Guangdong Province (no. 2010B090400533)
文摘An efficient method for the isolation and purification of 12,13-dihydroxyeuparin from Radix Eupatorii Chinensis by high speed counter-current chromatography (HSCCC) was established in this paper. The ether extracts of Radix Eupatorii Chinensis were purified by HSCCC with a solvent system of hexyl hydride-ethyl acetate-methanol-water (1:2:1:2, v/v/v/v). The upper phase was used as the stationary phase and the lower phase as the mobile phase. About 8.4 mg of 12, 13-dihydroxyeuparin was obtained from 200 mg of ether extracts from Radix Eupatorii Chinensis in one-step HSCCC separation, with the purity of 96.71%, as determined by HPLC. After methanol- water recrystallization, the purity of 12,13-dihydroxyeuparin reached 99.83%. Such a simple and effective method was fairly useful to prepare pure compound as reference substances for related study on Radix Eupatorii Chinensis.
文摘Coptis chinensis Franch, a widely used Traditional Chinese Medicine, shows various kinds of bioactivity. The major active components of the herb are considered to be alkaloids. Thus, preparative separation of these alkaloids is critical important for further pharmacology and mechanism studies. In the paper, five alkaloids from C. chinensis were purified by HSCCC using the solvent system composed of chloro-form-metha- nol-water (2:1:1, v/v/v) single prepared. The content of each solvent in solvent system were determined by gas chromatography (GC), then according the ratios of solvents in each phase to prepare the mobile and stationary phase respectively. And a comparative study was carried out between together preparation and single preparation of the solvent system. The purities and recoveries of all the products were over 98.5% and 92%. However, 134 mL chloroform, 336 mL methanol and 452 mL water were saved when the two phase were singled by GC. Our research showed an economical method for separating alkaloids from C. chinensis by HSCCC using the solvent system single prepared by GC.
基金the High-Technology Research and Development Program of China (Grant No.863-2003AA404210,the second phase 863-2005AA404250,863-2003AA404210 and the third phase 863-2006AA01Z443)
文摘A multi-try counter-meshing gears stronglink based on micro electromechanical system （MEMS） technology is introduced, including research, design, couple and fabrication of unique signal （UQS） for some specified fields of information security. The stronglink consists of two groups of metal counter-meshing gears, two pawl/ratchet mechanisms, two driving micromotors and two resetting micromotors. The resetting micromotors make counter-meshing gears withdraw by raising pawls so that the interfered counter-meshing gears will be relieved. The energy-coupling element is a photoelectric sensor with a circular notched plate. The counter-meshing mechanism is fabricated using the ultraviolet-lithographie~ galvanoformung and abformung （UV-LiGA） process and a precision mechanical technique. The stronglink can be tried several times if the correct resetting code is known.
文摘光伏发电并网规模持续增长,改变了电力系统大扰动后的动态特性。文章建立了计及低电压穿越(Low Voltage Ride Through,LVRT)功能的光伏发电系统机电暂态仿真模型。针对故障后联系阻抗显著增大的光伏弱交流并网系统,分析了光伏低电压穿越的恢复过程对系统行为特性的影响,揭示了因光伏频繁进入LVRT引起系统电压周期性振荡的机制,分析了相关影响因素,并提出了缓解应对措施。最后,面向西藏中部光伏高渗透实际电网,仿真复现了大扰动后系统振荡现象,验证了应对措施的有效性。
