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
[Objectives] To develop a method for separation and purification of acetophenones from Cynanchum bengei Decne root bark by combination of silica gel and high-speed counter-current chromatography( HSCCC). [Methods]The ...[Objectives] To develop a method for separation and purification of acetophenones from Cynanchum bengei Decne root bark by combination of silica gel and high-speed counter-current chromatography( HSCCC). [Methods]The crude extract of Cynanchum bengei Decne root bark was separated by silica gel column chromatography,and parts A and B containing acetophenones were obtained. Then,parts A and B were separated by HSCCC with a two-phase solvent system composed of petroleum ether-ethyl acetate-methanol-water( 4∶ 6∶ 4. 5∶ 5. 5 and4∶ 6 ∶ 3 ∶ 7, V/V), respectively. [Results] From 260 mg of part A, four compounds with p-dihydroxybenzene 3. 9 mg(Ⅰ),4-hydroxyacetophenone 17. 1 mg( Ⅱ),2,5-di-hydroxyacetophenone 13. 3 mg(Ⅲ) and 2,4-dihydroxyaceto-phenone 21. 0 mg(Ⅳ) were obtained. And from 300 mg of part B,136 mg of Radix Cynanchi Bungei benzophenone(Ⅴ) was obtained. The purity of compounds determined by HPLC was 97. 0%,96. 6%,99. 2%,99. 7%,99. 5%,respectively. [Conclusions] The established method is simple and efficient. It can be used for separation of acetophenones from Cynanchum bengei Decne root bark and has better practical value,which could provide a reference basis for development and utilization of Cynanchum bengei Decne root bark.展开更多
Several applications such as liquid-liquid extraction in micro-fluidic devices are concerned with the flow of two immiscible liquid phases. The commonly observed flow regimes in these systems are slug-flow and stratif...Several applications such as liquid-liquid extraction in micro-fluidic devices are concerned with the flow of two immiscible liquid phases. The commonly observed flow regimes in these systems are slug-flow and stratified flow. The latter regime in micro-channels has the inherent advantage that separation of the two liquids at the exit is efficient. Recently extraction in a stratified counter-current flow has been studied experimentally and it has been shown to be more efficient than co-current flow. An analytical as well as a numerical method to determine the steady-state solution of the corresponding convection-diffusion equation for the two flow-fields is presented. It is shown that the counter-current process is superior to the co-current process for the same set of parameters and operating conditions. A simplified model is proposed to analyse the process when diffusion in the transverse direction is not rate limiting. Different approaches to determining mass transfer coefficient are compared. The concept of log mean temperature difference used in design of heat exchangers is extended to describe mass transfer in the system.展开更多
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
Objective To develop an efficient method to isolate and purify the main components isoaloeresin D and aloin from Aloe vera for its industrial production.Methods High-speed counter-current chromatography was used to is...Objective To develop an efficient method to isolate and purify the main components isoaloeresin D and aloin from Aloe vera for its industrial production.Methods High-speed counter-current chromatography was used to isolate isoaloeresin D and aloin in a one-step separation from dried crude extract of A.vera.The biphasic solvent system composed of hexane-ethyl acetate-acetone-water(0.2:5:1.5:5) was used at a flow rate of 1.0 mL/min,while the lipophilic phase was selected as the mobile phase and the apparatus was rotated at 840 r/min.The effluent was detected at 254 nm.Results Isoaloeresin D(53.1 mg) and aloin(106.9 mg) were separated from the crude extract(384.7 mg) with the purities of 98.6% and 99.5%,respectively.Conclusion HSCCC is a powerful technique for isolation and separation of chemical composition from aloe.展开更多
Gas-solid counter-current downer reactors,in which particles move downward in an upward gas flow,can achieve high solid concentration for high heat and/or mass transfer rates.However,the particles may reverse their di...Gas-solid counter-current downer reactors,in which particles move downward in an upward gas flow,can achieve high solid concentration for high heat and/or mass transfer rates.However,the particles may reverse their direction or even be carried out of the reactor as the gas flow rate increases.This is closely related to "flooding" in counter-current flows.The energy minimization multiscale (EMMS) model well describes multiscale heterogeneity in gas-solid cocurrent upward flows.It is further developed to simulate gas-solid counter-current downward flows because similar heterogeneity can also be found in downers.The model characterizes well the axial hydrodynamics and predicts an inflexional voidage variation with superficial gas velocity in the fully developed region.This is supported by a simulation based on computational fluid dynamics and the discrete element method.The flooding predicted by the model agrees better with experiment than previous models.展开更多
Bubble columns can be operated in semi-batch, co-current or counter-current mode. This study attempts to extend the dual-bubble-size (DBS) model, viz., the energy-minimization multi-scale (EMMS) model for gas-liquid s...Bubble columns can be operated in semi-batch, co-current or counter-current mode. This study attempts to extend the dual-bubble-size (DBS) model, viz., the energy-minimization multi-scale (EMMS) model for gas-liquid systems, to co-current and counter-current bubble columns. With the increase of superficial liquid velocity, the predicted total gas holdup and regime transition are in accordance with experiments. A DBS drag model was then developed and incorporated into the CFD simulation. The total gas holdup and local gas holdup radial distribution in both the co-current and counter-current bubble columns are well estimated. The findings in the present work demonstrate that developing closure laws through the stability condition is of great significance in modeling complicated multi-scale flow in bubble columns.展开更多
Objective To develop an efficient preparative method for the separation of Gelsemium alkaloids from Gelsemium elegans. Methods High-speed counter-current chromatography （HSCCC） with several two-phase solvent systems...Objective To develop an efficient preparative method for the separation of Gelsemium alkaloids from Gelsemium elegans. Methods High-speed counter-current chromatography （HSCCC） with several two-phase solvent systems was investigated for the separation of Gelsemium alkaloids. The purity and structure identification of the purified compounds were performed with HPLC and NMR spectra, respectively. Results In a single operation, 206.6 mg of crude alkaloid sample was separated to yield 28.7 mg of koumine, 24.9 mg of gelsemine, 26.9 mg of humantenine, and 7.2 mg of gelsevirine, with the purities of 97.8%, 95.4%, 97.4%, and 93.5%, respectively. Conclusion A preparative HSCCC method is successfully established for the separation of four Gelsemium alkaloids from G. elegans with a modified two-phase solvent system com posed of n-hexane-ethyl acetate-ethanol-O. 5% triethylamine-H2O （3：5：3：4）.展开更多
A computational fluid dynamics study of three-phase counter-current fluidization occurring in a turbu- lent contact absorber was performed. A two-dimensional, transient Eulerian multi-fluid model was used, in which th...A computational fluid dynamics study of three-phase counter-current fluidization occurring in a turbu- lent contact absorber was performed. A two-dimensional, transient Eulerian multi-fluid model was used, in which the dispersed solid phase was modeled employing a kinetic theory of granular flow. The grid independence of the model, the effect of wall boundary conditions, the choice of granular temperature model, the effects of order of discretization scheme and drag models were studied for a base case setting, The results of simulations were validated against experimental results obtained from the literature. Once the model settings were finalized, simulations were performed for different gas and liquid velocities to predict the hydrodynamics of the absorber. Computed bed expansion and pressure drop were compared with experimental data. Good agreement between the two was found for low velocities of gas and liquid.展开更多
Quercetin-3-O-sambubioside[Quercetin-3-O-β-D-xylopyranosyl(1→2)-β-D-glucopyranoside]was separated and purified by semi-preparative high-speed counter-current chromatography(HSCCC)with a twophase-solvent system comp...Quercetin-3-O-sambubioside[Quercetin-3-O-β-D-xylopyranosyl(1→2)-β-D-glucopyranoside]was separated and purified by semi-preparative high-speed counter-current chromatography(HSCCC)with a twophase-solvent system composed of ethyl acetate-nbutanol-water(4∶1∶5,v/v)from the leaves of Nelumbo nucifera(Lotus).A total of 5.0 mg of the targeted compound with a purity of 98.6%as determined by high performance liquid chromatography(HPLC)was obtained from 100 mg of the crude extract cleaned up by AB-8 macroporous resin in a one-step separation.Quercetin-3-O-sambubioside was a novel flavonoid glycoside from the leaves of Nelumbo nucifera,and its chemical structure was identified by means of ESI-MS,1D NMR and 2D NMR.展开更多
A sample enrichment method focusing on the minor targeted components was established to help them to be successfully separated by pH-zone refining CCC.Seven minor indole alkaloids in Uncaria rhynchophylla(Miq.)Miq.ex ...A sample enrichment method focusing on the minor targeted components was established to help them to be successfully separated by pH-zone refining CCC.Seven minor indole alkaloids in Uncaria rhynchophylla(Miq.)Miq.ex Havil(UR)were chosen to show the advantage of this method.The sample enrichment and separation were展开更多
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Supported by National Natural Science Foundation Item of 2014(81373941)Shandong Natural Science Foundation Item of 2012(ZR2012HM047)+1 种基金Science and Technology Development Plan Item of Shandong(2014G2X219003)Major Project of the State Administration of Traditional Chinese Medicine(201407002)
文摘[Objectives] To develop a method for separation and purification of acetophenones from Cynanchum bengei Decne root bark by combination of silica gel and high-speed counter-current chromatography( HSCCC). [Methods]The crude extract of Cynanchum bengei Decne root bark was separated by silica gel column chromatography,and parts A and B containing acetophenones were obtained. Then,parts A and B were separated by HSCCC with a two-phase solvent system composed of petroleum ether-ethyl acetate-methanol-water( 4∶ 6∶ 4. 5∶ 5. 5 and4∶ 6 ∶ 3 ∶ 7, V/V), respectively. [Results] From 260 mg of part A, four compounds with p-dihydroxybenzene 3. 9 mg(Ⅰ),4-hydroxyacetophenone 17. 1 mg( Ⅱ),2,5-di-hydroxyacetophenone 13. 3 mg(Ⅲ) and 2,4-dihydroxyaceto-phenone 21. 0 mg(Ⅳ) were obtained. And from 300 mg of part B,136 mg of Radix Cynanchi Bungei benzophenone(Ⅴ) was obtained. The purity of compounds determined by HPLC was 97. 0%,96. 6%,99. 2%,99. 7%,99. 5%,respectively. [Conclusions] The established method is simple and efficient. It can be used for separation of acetophenones from Cynanchum bengei Decne root bark and has better practical value,which could provide a reference basis for development and utilization of Cynanchum bengei Decne root bark.
文摘Several applications such as liquid-liquid extraction in micro-fluidic devices are concerned with the flow of two immiscible liquid phases. The commonly observed flow regimes in these systems are slug-flow and stratified flow. The latter regime in micro-channels has the inherent advantage that separation of the two liquids at the exit is efficient. Recently extraction in a stratified counter-current flow has been studied experimentally and it has been shown to be more efficient than co-current flow. An analytical as well as a numerical method to determine the steady-state solution of the corresponding convection-diffusion equation for the two flow-fields is presented. It is shown that the counter-current process is superior to the co-current process for the same set of parameters and operating conditions. A simplified model is proposed to analyse the process when diffusion in the transverse direction is not rate limiting. Different approaches to determining mass transfer coefficient are compared. The concept of log mean temperature difference used in design of heat exchangers is extended to describe mass transfer in the system.
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.
基金Science and Technology Project of Zhuhai (PC20051072),2005
文摘Objective To develop an efficient method to isolate and purify the main components isoaloeresin D and aloin from Aloe vera for its industrial production.Methods High-speed counter-current chromatography was used to isolate isoaloeresin D and aloin in a one-step separation from dried crude extract of A.vera.The biphasic solvent system composed of hexane-ethyl acetate-acetone-water(0.2:5:1.5:5) was used at a flow rate of 1.0 mL/min,while the lipophilic phase was selected as the mobile phase and the apparatus was rotated at 840 r/min.The effluent was detected at 254 nm.Results Isoaloeresin D(53.1 mg) and aloin(106.9 mg) were separated from the crude extract(384.7 mg) with the purities of 98.6% and 99.5%,respectively.Conclusion HSCCC is a powerful technique for isolation and separation of chemical composition from aloe.
基金the Strategic Priority Research Pro-gram of the Chinese Academy of Sciences(No.XDA07080400)the Informationization Program of the Chinese Academy ofSciences(No.XXH13506-301)。
文摘Gas-solid counter-current downer reactors,in which particles move downward in an upward gas flow,can achieve high solid concentration for high heat and/or mass transfer rates.However,the particles may reverse their direction or even be carried out of the reactor as the gas flow rate increases.This is closely related to "flooding" in counter-current flows.The energy minimization multiscale (EMMS) model well describes multiscale heterogeneity in gas-solid cocurrent upward flows.It is further developed to simulate gas-solid counter-current downward flows because similar heterogeneity can also be found in downers.The model characterizes well the axial hydrodynamics and predicts an inflexional voidage variation with superficial gas velocity in the fully developed region.This is supported by a simulation based on computational fluid dynamics and the discrete element method.The flooding predicted by the model agrees better with experiment than previous models.
基金The authors acknowledge the long-term support from the National Key R&D Program of China (2017YFB0602500)the National Natural Science Foundation of China (91634203, 21808222)+2 种基金Beijing Natural Science Foundation (2184125)the Research Center for Mesoscience at Institute of Process Engineering (COM2016A004)the Strategic Priority Research Program (XDA21030700), Chinese Academy of Sciences.
文摘Bubble columns can be operated in semi-batch, co-current or counter-current mode. This study attempts to extend the dual-bubble-size (DBS) model, viz., the energy-minimization multi-scale (EMMS) model for gas-liquid systems, to co-current and counter-current bubble columns. With the increase of superficial liquid velocity, the predicted total gas holdup and regime transition are in accordance with experiments. A DBS drag model was then developed and incorporated into the CFD simulation. The total gas holdup and local gas holdup radial distribution in both the co-current and counter-current bubble columns are well estimated. The findings in the present work demonstrate that developing closure laws through the stability condition is of great significance in modeling complicated multi-scale flow in bubble columns.
文摘Objective To develop an efficient preparative method for the separation of Gelsemium alkaloids from Gelsemium elegans. Methods High-speed counter-current chromatography （HSCCC） with several two-phase solvent systems was investigated for the separation of Gelsemium alkaloids. The purity and structure identification of the purified compounds were performed with HPLC and NMR spectra, respectively. Results In a single operation, 206.6 mg of crude alkaloid sample was separated to yield 28.7 mg of koumine, 24.9 mg of gelsemine, 26.9 mg of humantenine, and 7.2 mg of gelsevirine, with the purities of 97.8%, 95.4%, 97.4%, and 93.5%, respectively. Conclusion A preparative HSCCC method is successfully established for the separation of four Gelsemium alkaloids from G. elegans with a modified two-phase solvent system com posed of n-hexane-ethyl acetate-ethanol-O. 5% triethylamine-H2O （3：5：3：4）.
文摘A computational fluid dynamics study of three-phase counter-current fluidization occurring in a turbu- lent contact absorber was performed. A two-dimensional, transient Eulerian multi-fluid model was used, in which the dispersed solid phase was modeled employing a kinetic theory of granular flow. The grid independence of the model, the effect of wall boundary conditions, the choice of granular temperature model, the effects of order of discretization scheme and drag models were studied for a base case setting, The results of simulations were validated against experimental results obtained from the literature. Once the model settings were finalized, simulations were performed for different gas and liquid velocities to predict the hydrodynamics of the absorber. Computed bed expansion and pressure drop were compared with experimental data. Good agreement between the two was found for low velocities of gas and liquid.
基金funded by the Natural Science Foundation of Jiangxi Province(2006GY0066)the Research Project of Education Office of Jiangxi Province(20030058)the Program for Yangtse Scholars and Innovative Research Team in University(IRT0540).
文摘Quercetin-3-O-sambubioside[Quercetin-3-O-β-D-xylopyranosyl(1→2)-β-D-glucopyranoside]was separated and purified by semi-preparative high-speed counter-current chromatography(HSCCC)with a twophase-solvent system composed of ethyl acetate-nbutanol-water(4∶1∶5,v/v)from the leaves of Nelumbo nucifera(Lotus).A total of 5.0 mg of the targeted compound with a purity of 98.6%as determined by high performance liquid chromatography(HPLC)was obtained from 100 mg of the crude extract cleaned up by AB-8 macroporous resin in a one-step separation.Quercetin-3-O-sambubioside was a novel flavonoid glycoside from the leaves of Nelumbo nucifera,and its chemical structure was identified by means of ESI-MS,1D NMR and 2D NMR.
基金supported by the National Science and Technology Major Project for Major Drug Development(No.2013ZX09508104)the Traditional Chinese Medicine Industry Research Special Project(No.201307002)the National Science&Technology Major Project Key New Drug Creation and Manufacturing program(No.2011ZX09307002-03)of the People's Republic of China
文摘A sample enrichment method focusing on the minor targeted components was established to help them to be successfully separated by pH-zone refining CCC.Seven minor indole alkaloids in Uncaria rhynchophylla(Miq.)Miq.ex Havil(UR)were chosen to show the advantage of this method.The sample enrichment and separation were
