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
针对煤与瓦斯突出事故的复杂性以及数据获取困难导致预测准确率低的问题,提出基于密度的噪声应用空间聚类-改进哈里斯鹰优化-支持向量机(density based spatial clustering of applications with noise-improved Harris hawks optimizat...针对煤与瓦斯突出事故的复杂性以及数据获取困难导致预测准确率低的问题,提出基于密度的噪声应用空间聚类-改进哈里斯鹰优化-支持向量机(density based spatial clustering of applications with noise-improved Harris hawks optimization-support vector machine, DBSCAN-IHHO-SVM)预测模型。首先,选取瓦斯含量、瓦斯压力、煤层孔隙率、煤层坚固性系数作为预测指标,对数据中的缺失值采用均值填补处理,利用生成式对抗网络(generative adversarial network, GAN)扩充突出数据量。接着,采用DBSCAN从非突出数据中识别潜在危险数据,并将其作为新的突出数据。最后,引入IHHO调整SVM模型参数,将处理后的数据输入IHHO-SVM模型进行预测分析。结果表明,相比于原始SVM模型,DBSCAN-IHHO-SVM模型的整体预测准确率、危险数据识别率分别提升了5.87%、38.46%。在突出数据样本有限的情况下,DBSCAN-IHHO-SVM模型能有效挖掘非突出数据潜在信息,实现精准预警,为该领域研究提供了新思路。展开更多
The deformation energy(Wd)of soil-like tectonic coal is crucial for investigating the mechanism of coal and gas outbursts.Tectonic coal has a significant nonlinear constitutive relationship,which makes traditional ela...The deformation energy(Wd)of soil-like tectonic coal is crucial for investigating the mechanism of coal and gas outbursts.Tectonic coal has a significant nonlinear constitutive relationship,which makes traditional elastic-based models for computing Wdunsuitable.Inspired by critical state soil mechanics,this study theoretically established a new calculation model of Wdsuitable for the coal with nonlinear deformation characteristics.In the new model,the relationship between energy and stress no longer follows the square law(observed in traditional linear elastic models)but exhibits a power function,with the theoretical value of the power exponent ranging between 1 and 2.Hydrostatic cyclic loading and unloading experiments were conducted on four groups of tectonic coal samples and one group of intact coal samples.The results indicated that the relationship between Wdand stress for both intact and tectonic coal follows a power law.The exponents for intact and tectonic coal are close to 2 and 1,respectively.The stress-strain curve of intact coal exhibits small deformation and linear characteristics,whereas the stress-strain curves of tectonic coal show large deformation and nonlinear characteristics.The study specifically investigates the role of coal viscosity in the cyclic loading/unloading process.The downward bending in the unloading curves can be attributed to the time-dependent characteristics of coal,particularly its viscoelastic behavior.Based on experimental statistics,the calculation model of Wdwas further simplified.The simplified model involves only one unknown parameter,which is the power exponent between Wdand stress.The measured Wdof the coal samples increases with the number of load cycles.This phenomenon is attributed to coal's viscoelastic deformation.Within the same stress,the Wdof tectonic coal is an order of magnitude greater than that of intact coal.The calculation model of Wdproposed in this paper provides a new tool for studying the energy principle of coal and gas outbursts.展开更多
Outburst of coal and gas represents a significant risk to the health and safety of mine personnel working in development and longwall production face areas.There have been over 878 outburst events recorded in twenty-t...Outburst of coal and gas represents a significant risk to the health and safety of mine personnel working in development and longwall production face areas.There have been over 878 outburst events recorded in twenty-two Australian underground coal mines.Most outburst incidents have been associated with abnormal geological conditions.Details of Australian outburst incidents and mining experience in conditions where gas content was above current threshold levels are presented and discussed.Mining experience suggests that for gas con-tent below 9.0 m^3/t,mining in carbon dioxide(CO2)rich seam gas conditions does not pose a greater risk of outburst than mining in CH4 rich seam gas conditions.Mining experience also suggests that where no abnormal geological structures are present that mining in areas with gas content greater than the current accepted threshold levels can be undertaken with no discernible increase in outburst risk.The current approach to determining gas content threshold limits in Australian mines has been effective in prevent-ing injury from outburst,however operational experience suggests the current method is overly conser-vative and in some cases the threshold limits are low to the point that they provide no significant reduction in outburst risk.Other factors that affect outburst risk,such as gas pressure,coal toughness and stress and geological structures are presently not incorporated into outburst threshold limits adopted in Australian mines.These factors and the development of an outburst risk index applicable to Australian underground coal mining conditions are the subject of ongoing research.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 Fundamental Research Funds for the Central Universities(No.2024QN11072)National Natural Science Foundation of China(Nos.52404264 and 52174217)State Key Program of the National Natural Science Foundation of China(No.52034008)。
文摘The deformation energy(Wd)of soil-like tectonic coal is crucial for investigating the mechanism of coal and gas outbursts.Tectonic coal has a significant nonlinear constitutive relationship,which makes traditional elastic-based models for computing Wdunsuitable.Inspired by critical state soil mechanics,this study theoretically established a new calculation model of Wdsuitable for the coal with nonlinear deformation characteristics.In the new model,the relationship between energy and stress no longer follows the square law(observed in traditional linear elastic models)but exhibits a power function,with the theoretical value of the power exponent ranging between 1 and 2.Hydrostatic cyclic loading and unloading experiments were conducted on four groups of tectonic coal samples and one group of intact coal samples.The results indicated that the relationship between Wdand stress for both intact and tectonic coal follows a power law.The exponents for intact and tectonic coal are close to 2 and 1,respectively.The stress-strain curve of intact coal exhibits small deformation and linear characteristics,whereas the stress-strain curves of tectonic coal show large deformation and nonlinear characteristics.The study specifically investigates the role of coal viscosity in the cyclic loading/unloading process.The downward bending in the unloading curves can be attributed to the time-dependent characteristics of coal,particularly its viscoelastic behavior.Based on experimental statistics,the calculation model of Wdwas further simplified.The simplified model involves only one unknown parameter,which is the power exponent between Wdand stress.The measured Wdof the coal samples increases with the number of load cycles.This phenomenon is attributed to coal's viscoelastic deformation.Within the same stress,the Wdof tectonic coal is an order of magnitude greater than that of intact coal.The calculation model of Wdproposed in this paper provides a new tool for studying the energy principle of coal and gas outbursts.
基金ACARP for financial support of project C26055the Australian underground coal mine operators that have supported this research project
文摘Outburst of coal and gas represents a significant risk to the health and safety of mine personnel working in development and longwall production face areas.There have been over 878 outburst events recorded in twenty-two Australian underground coal mines.Most outburst incidents have been associated with abnormal geological conditions.Details of Australian outburst incidents and mining experience in conditions where gas content was above current threshold levels are presented and discussed.Mining experience suggests that for gas con-tent below 9.0 m^3/t,mining in carbon dioxide(CO2)rich seam gas conditions does not pose a greater risk of outburst than mining in CH4 rich seam gas conditions.Mining experience also suggests that where no abnormal geological structures are present that mining in areas with gas content greater than the current accepted threshold levels can be undertaken with no discernible increase in outburst risk.The current approach to determining gas content threshold limits in Australian mines has been effective in prevent-ing injury from outburst,however operational experience suggests the current method is overly conser-vative and in some cases the threshold limits are low to the point that they provide no significant reduction in outburst risk.Other factors that affect outburst risk,such as gas pressure,coal toughness and stress and geological structures are presently not incorporated into outburst threshold limits adopted in Australian mines.These factors and the development of an outburst risk index applicable to Australian underground coal mining conditions are the subject of ongoing research.
