Based on the generalized Hamilton's principle,the nonlinear governing equation of an axially functionally graded(AFG)pipe is established.The non-trivial equilibrium configuration is superposed by the modal functio...Based on the generalized Hamilton's principle,the nonlinear governing equation of an axially functionally graded(AFG)pipe is established.The non-trivial equilibrium configuration is superposed by the modal functions of a simply supported beam.Via the direct multi-scale method,the response and stability boundary to the pulsating fluid velocity are solved analytically and verified by the differential quadrature element method(DQEM).The influence of Young's modulus gradient on the parametric resonance is investigated in the subcritical and supercritical regions.In general,the pipe in the supercritical region is more sensitive to the pulsating excitation.The nonlinearity changes from hard to soft,and the non-trivial equilibrium configuration introduces more frequency components to the vibration.Besides,the increasing Young's modulus gradient improves the critical pulsating flow velocity of the parametric resonance,and further enhances the stability of the system.In addition,when the temperature increases along the axial direction,reducing the gradient parameter can enhance the response asymmetry.This work further complements the theoretical analysis of pipes conveying pulsating fluid.展开更多
Supercritical fluid extraction (SFE) of essential oil from dry rhizome ofLigusticum chuanxiong Hort was developed. GC/MS was used for the determination of the composition ofessential oil. Forty-four compounds were ide...Supercritical fluid extraction (SFE) of essential oil from dry rhizome ofLigusticum chuanxiong Hort was developed. GC/MS was used for the determination of the composition ofessential oil. Forty-four compounds were identified. The conventional extraction method wasconducted in parallel for comparison. The extracts were qualitatively compared by GC/MS. The yieldsof SFE and steam distillation-extraction were 4.16 % ( v/w) and 0.8 % ( v/w), respectively.Application of SFE of zessential oil from dry rhizome of Ligustiaan chuanxiong Hort was preferable.展开更多
The supercritical fluid crystallization technique is a novel technology for preparing ultrafine particles. This paper introduced the concept and features of the technique with an emphasis on three kinds of supercritic...The supercritical fluid crystallization technique is a novel technology for preparing ultrafine particles. This paper introduced the concept and features of the technique with an emphasis on three kinds of supercritical fluid crystallization techniques, i.e. rapid expansion of supercritical solutions, supercritical fluid anti-solvent and particles from gas saturated solutions Some questions and the prospect of this technique were also discussed.展开更多
Tea is a widely consumed beverage and has many important physiological properties and potential health benefits. In this study, a novel method based on supercritical fluid chromatography coupled with mass spectrometry...Tea is a widely consumed beverage and has many important physiological properties and potential health benefits. In this study, a novel method based on supercritical fluid chromatography coupled with mass spectrometry (SFC-MS) was developed to simultaneously determine 11 amino acids in different types of tea (green teas, Oolong tea, black tea and Pu-erh tea). The separation conditions for the analysis of the selected amino acids including the column type, temperature and backpressure as well as the type of additive, were carefully optimized. The best separation of the 11 amino acids was obtained by adding water (5%, v/v) and trifluoroacetic acid (0.4%, v/v) to the organic modifier (methanol). Finally, the developed SFC-MS method was fully validated and successfully applied to the determination of these amino acids in six different tea samples. Good linearity (r ≥ 0.993), precision (RSDs≤ 2.99%), accuracy (91.95%-107.09%) as well as good sample stability were observed. The limits of detection ranged from 1.42 to 14.69 ng/mL, while the limits of quantification were between 4.53 and 47.0 ng/mL. The results indicate that the contents of the 11 amino acids in the six different tea samples are greatly influenced by the degree of fermentation. The proposed SFC-MS method shows a great potential for further investigation of tea varieties.展开更多
In the present paper is reported the method for the isolation and extraction of total flavonoids of Epimedium Koreanum Nakai by means of supercritical fluid extraction(SFE). By examining pressure, temperature, amounts...In the present paper is reported the method for the isolation and extraction of total flavonoids of Epimedium Koreanum Nakai by means of supercritical fluid extraction(SFE). By examining pressure, temperature, amounts of modifier and extraction time, the optimized condition of SFE is confirmed as 30 MPa and 60 ℃, with 70% ethanol as the modifier. The samples were statically extracted for 30 min, followed by dynamic extraction for 120 min at a flow rate of 6 mL/min. The quantitative analysis of total flavonoids was performed by UV-Vis spectrophotometry. Compared with the conventional method, the SFE method is more efficient, more rapid and more friendly environmentally.展开更多
The herbal plant Acanthopanax Senticosus Harms is natural herb of Changbaishan in Jilin Province of China, which belongs to the Araliaceae family. As the ingredients of folk medicine, it has long been used to treat a ...The herbal plant Acanthopanax Senticosus Harms is natural herb of Changbaishan in Jilin Province of China, which belongs to the Araliaceae family. As the ingredients of folk medicine, it has long been used to treat a variety of human diseases, such as cerebrovascular disease, diabetes, tumor, isochemic heart diseases, hypertension, rheumatic arthritis, etc. E2,33. Flavonoids, a class of constituent compounds, which have a broad distribution in the nature and are found in Acanthopanax Senticosus Harms, have gained particular attention. A number of studies have shown that flavonoid compounds have wide biological activities, such as anti-aging, anticancer, anti-HIV,展开更多
A series of TiO 2-MoO 3 nano-composite photocatalysts were prepared by supercritical fluid dry method(SCFD) and an impregnation technique with TiCl 4 and (NH 4) 6Mo 7O 24 ·4H 2O as the starting materia...A series of TiO 2-MoO 3 nano-composite photocatalysts were prepared by supercritical fluid dry method(SCFD) and an impregnation technique with TiCl 4 and (NH 4) 6Mo 7O 24 ·4H 2O as the starting materials. The catalysts were characterized by the means of XRD, TEM and UV-Vis. Methyl orange was used as model compound for the evaluation of their catalytic activities. The results indicated that the photo-catalyst prepared by SCFD had the advantages of small size(12.84 nm), narrow distribution and good dispersivity. The presence of small amount of Mo in composite catalyst gives rise to the red shift of its absorbance wavelength, decrease of its energy gap and increase of the utility of visible light. Furthermore, higher surface acidity of the photo-catalyst was obtained as the result of the addition of MoO 3. Compared with pure TiO 2, the catalytic activity of the TiO 2-MoO 3 nano-composite photo-catalyst was improved significantly. As the doping concentration of the composite catalysts was controlled at 0.6%(molar percentage), 100% degradation of methyl orange was achieved with in 1.2 h irradiation time.展开更多
Supercritical fluid chromatography(SFC) meets with great favor due to its high efficiency, low organic solvent consumption, and the specialty for the identification of the isomeric species. This review describes the a...Supercritical fluid chromatography(SFC) meets with great favor due to its high efficiency, low organic solvent consumption, and the specialty for the identification of the isomeric species. This review describes the advances of SFC in targeted and untargeted lipid profiling. The advancement of the SFC instruments and the stationary phases are summarized. Typical applications of SFC to the targeted and untargeted lipid profiling are discussed in detail. Moreover, the perspectives of SFC in the lipid profiling are also proposed. As a useful and promising tool for investigating lipids in vitro and in vivo, SFC will predictably obtain further development.展开更多
Owing to an environment-friendly utilization of resources, increased attention has been focused on fuels and chemicals from biomass as an alternative to fossil resources. In addition, supercritical fluid technology ha...Owing to an environment-friendly utilization of resources, increased attention has been focused on fuels and chemicals from biomass as an alternative to fossil resources. In addition, supercritical fluid technology has been considered to be an environmentally-benign treatment. Therefore, its technology was applied for a conversion of biomass to useful fuels and chemicals in order to mitigate environmental loading. For example, supercritical water treatment has demonstrated that lignocellulosics can be hydrolyzed to become lignin-derived products for useful aromatic chemicals and carbohydrate-derived products, such as polysaccharides, oligosaccharides and monosaccharides of glucose, mannose and xylose used for subsequent ethanol fermentation. If this treatment is prolonged, lignocellulosics were found to be converted to organic acids such as formic, acetic, glycolic and lactic acids which can be converted to methane for biofuel. When alcohols, such as methanol and ethanol, were used instead of water, some other useful products were achieved, and its liquefied products were found to have a potential for liquid biofuel. In this study, therefore, our research achievements in supercritical fluid science of woody biomass will be introduced for clean and green chemistry for a sustainable environment.展开更多
Based on the solubility in supercritical CO2,two strategies in which CO2 plays different roles are used to make quercetine and astaxanthin particles by supercritical fluid technologies.The experimental results showed ...Based on the solubility in supercritical CO2,two strategies in which CO2 plays different roles are used to make quercetine and astaxanthin particles by supercritical fluid technologies.The experimental results showed that micronized quercetine particles with mean particle size of 1.0-1.5 μm can be made via solution enhanced dispersion by supercritical fluids(SEDS) process,in which CO2 worked as turbulent anti-solvent;while for astaxanthin,micronized particles with mean particle size of 0.3-0.8 μm were also made successfully by rapid expansion supercritical solution(RESS) process.展开更多
Introduction Ginseng( Panax ginseng C. A. Meyer, Araliaceae) is one of the most valuable Chinese crude drugs and has been used widely for over 2000 years. Studies have demonstrated that ginseng can act on the centr...Introduction Ginseng( Panax ginseng C. A. Meyer, Araliaceae) is one of the most valuable Chinese crude drugs and has been used widely for over 2000 years. Studies have demonstrated that ginseng can act on the central nervous system, the cardiovascular system and the endocrine system; it can enhance immune function and metabolism; it possesses a biomodulation action, anticancer effect, anti-stress and anti-ageing activities, and so on.展开更多
The objective of this study was to improve the dissolution and bioavailability of silymarin(SM).Solid dispersions(SDs)were prepared using solution-enhanced dispersion by supercritical fluids(SEDS)and evaluated in vitr...The objective of this study was to improve the dissolution and bioavailability of silymarin(SM).Solid dispersions(SDs)were prepared using solution-enhanced dispersion by supercritical fluids(SEDS)and evaluated in vitro and in vivo,compared with pure SM powder.The particle sizes,stability,and contents of residual solvent of the prepared SM-SDs with SEDS and solvent evaporation(SE)were investigated.Four polymer matrix materials were evaluated for the preparation of SM-SD-SEDS,and the hydrophilic polymer,polyvinyl pyrrolidone K17,was selected with a ratio of 1:5 between SM and the polymer.Physicochemical analyses using X-ray diffraction and differential scanning calorimetry indicated that SM was dispersed in SD in an amorphous state.The optimized SM-SD-SEDS showed no loss of SM after storage for 6 months and negligible residual solvent(ethanol)was detected using gas chromatography.In vitro drug release was increased from the SM-SDSEDS,as compared with pure SM powder or SM-SD-SE.In vivo,the area under the rat plasma SM concentration-time curve and the maximum plasma SM concentration were 2.4-fold and 1.9-fold higher,respectively,after oral administration of SM-SD-SEDS as compared with an aqueous SM suspension.These results illustrated the potential of using SEDS to prepare SM-SD,further improving the biopharmaceutical properties of this compound.展开更多
Mesoporous zirconia was synthesized by a new and simple method. Zirconium n-propoxide was used as the zirconium source. A small, inexpensive nonsurfactant, triethanolamine, was used as the template. The template was r...Mesoporous zirconia was synthesized by a new and simple method. Zirconium n-propoxide was used as the zirconium source. A small, inexpensive nonsurfactant, triethanolamine, was used as the template. The template was removed by thermal treatment in air and supercritical fluid extraction using CO2. The structure of the resulting materials was characterized by X-ray diffraction, transmission electron microscopy, and N2 adsorption-desorption analyses. The materials are found to have narrowly distributed average pore diameters and wormhole-like pore channels. However, higher surface area and larger pore volume are exhibited after supercritical fluid extraction with CO2. The removal of the template by thermal treatment also leads to condensation and mild shrinkage of the zirconia framework.展开更多
Ti-Ce, Ti-Si binary and Ti-Ce-Si ternary novel nanocomposite oxide photocatalysts were prepared with cheap inorganic salts TiCI4, Na2SiO3·9H2O and Ce(NO3)3·6H2O as precursors by supercritical fluid drying ...Ti-Ce, Ti-Si binary and Ti-Ce-Si ternary novel nanocomposite oxide photocatalysts were prepared with cheap inorganic salts TiCI4, Na2SiO3·9H2O and Ce(NO3)3·6H2O as precursors by supercritical fluid drying (SCFD) technology. The catalysts were characterized by means of XRD and TEM. The particle size of nanocomposite oxide photocatalysts synthesized by SCFD method is about 6 - 11 nm, which is smaller than those obtained by common drying method (CD). The phase transformation from anatase to rutile was inhibited by SCFD technology. The peaks of SiO2 and CeO2 in XRD patterns indicate that a SiO2 amorphorous phase exists in all the samples and CeO2 is well dispersed on the surface of TiO2. The orthogonal test was designed to optimize the preparing conditions. It is found that ceria dop;.ng enhances the photocatalyric activity markedly, and the optimum doping of CeO2 is 0.1%. The thermal stability of photocatalyst can be improved ; the growth of particle-size and the decrease of surface area can be prohibited by doping of SlOe. Heat-treatment is a necessary factor to induce chemistry change of Ti-Si surface. The optimum heat-treating temperature is 600℃. A novel and efficient Ti-Ce-Si ternary nanocomposite was prepared by SCFI) method with strong thermal stability and high photoactivity in the photodegratation of phenol.展开更多
TiO_2-CeO_2 nanocomposite particles were prepared with Ce(NO_3)_3·6H_2O and TiCl_4 as precursors by the codeposition method and supercritical fluid drying (SCFD) technology. The particles prepared were characteri...TiO_2-CeO_2 nanocomposite particles were prepared with Ce(NO_3)_3·6H_2O and TiCl_4 as precursors by the codeposition method and supercritical fluid drying (SCFD) technology. The particles prepared were characterized by means of XRD, TEM and FTIR. The results show that SCFD can give rise to the direct synthesis of the anatase TiO_2-CeO_2,and the particle size is 6~11 nm under 500 ℃ thermal-treated,smaller than that by common drying (CD). The phase transformation from anatase to rutile is inhibited by supercritical fluid drying technology. The peak of CeO_2 is not observed in XRD patterns,Ce-O band vibration was present in FTIR spectrum,which indicates that CeO_2 is well dispersed on the surface of TiO_2.展开更多
A number of studies have been reported on the applications of supercritical fluids to polymeric processes. The presence of volatiles can affect the end-use properties of polymer materials. Therefore, these volatiles m...A number of studies have been reported on the applications of supercritical fluids to polymeric processes. The presence of volatiles can affect the end-use properties of polymer materials. Therefore, these volatiles must be reduced to a level below the maximum permissible limit. Conventional heat-relevant techniques for polymer devolatilization sometimes have limited effectiveness. Devolatilization with supercritical fluids, however, can enhance removal of volatiles from polymers. A model for diffusion-limited extraction is used to characterize dynamic supercritical fluid devolatilization of spherical polymer particles. The rate of supercritical fluid devolailization for styrene/polystyrene system is measured at 343 K and 18 MPa and at CO2 flow rate of 1.93, 3.27 and 5.62 L·min^-1, respectively. The model analysis, which is consistent with experimental results, indicates that the supercritical fluid devolatilization is not solubility-limited but diffusion-limited when CO2 flow rate is above 4.00 L·min^-1.展开更多
The simultaneous removal of up to 92% of the surfactant template and chemical implantation of transition metal complexes into mesopores has been successfully achieved by treating as-synthesized pure siliceous MCM-41 w...The simultaneous removal of up to 92% of the surfactant template and chemical implantation of transition metal complexes into mesopores has been successfully achieved by treating as-synthesized pure siliceous MCM-41 with supercritical CO2 modified with CH2Cl2/MeOH mixture, resulting in the formation of functionalized material with uniform pore structure.展开更多
In 1822, almost 200 years ago, Baron Charles Cagniard de Latour (1777-1859) discovered the critical phenomena or critical state [1] [2]. At that time, it was described as a curiosity. However, it is now used as an adv...In 1822, almost 200 years ago, Baron Charles Cagniard de Latour (1777-1859) discovered the critical phenomena or critical state [1] [2]. At that time, it was described as a curiosity. However, it is now used as an advanced extraction and analytical technology in industry and research. Extraction with supercritical fluids (SFs) was welcome from the very beginning. In the present paper, the application to chromatography of the critical phenomena of compressed gases or overheated liquids as supercritical fluids will be discussed. Supercritical Fluid Chromatography (SFC) received an uneasy welcome, mainly because of the lack of commercially available analytical instruments. Even today, only a small number of industrial companies are manufacturing SFC instrumentation. A very small spectrum of columns is manufactured specially for SFC. SFC is not accepted by Pharmacopeia committees for the analysis of drugs and medical forms to the same extent as Gas Chromatography, High-Performance Liquid Chromatography or even Thin Layer Chromatography. The present status and future perspectives for SFC will be discussed.展开更多
The purpose of this study was to investigate the influence of the supercritical CO2 processing on the particle size and morphology of puerarin crystals. The process parameters included solvents, temperature, pressures...The purpose of this study was to investigate the influence of the supercritical CO2 processing on the particle size and morphology of puerarin crystals. The process parameters included solvents, temperature, pressures, antisolvent times, addition volumes, antisolvent addition rates and solute concentrations. After being processed, the dramatic reduction of the dimensions and the change of the crystal shape were noticed. Decreasing the antisolvent addition rate, increasing the temperature and the addition volume below 50 ml led to a decrease in size. The new crystal of puerarin generated at the optimal conditions was 30.34 μm.The solvent of methanol and the concentration of 60 mg/ml were found to determine the type and degree of crystallinity of particles. These results showed that this process has the potential to produce a drug recrystallization product with newly generated crystal forms and the size of drug particles could be controlled through the tuning of various experimental conditions.展开更多
基金Project supported by the National Natural Science Foundation of China (Nos.12002195 and 12372015)the National Science Fund for Distinguished Young Scholars of China (No.12025204)the Program of Shanghai Municipal Education Commission of China (No.2019-01-07-00-09-E00018)。
文摘Based on the generalized Hamilton's principle,the nonlinear governing equation of an axially functionally graded(AFG)pipe is established.The non-trivial equilibrium configuration is superposed by the modal functions of a simply supported beam.Via the direct multi-scale method,the response and stability boundary to the pulsating fluid velocity are solved analytically and verified by the differential quadrature element method(DQEM).The influence of Young's modulus gradient on the parametric resonance is investigated in the subcritical and supercritical regions.In general,the pipe in the supercritical region is more sensitive to the pulsating excitation.The nonlinearity changes from hard to soft,and the non-trivial equilibrium configuration introduces more frequency components to the vibration.Besides,the increasing Young's modulus gradient improves the critical pulsating flow velocity of the parametric resonance,and further enhances the stability of the system.In addition,when the temperature increases along the axial direction,reducing the gradient parameter can enhance the response asymmetry.This work further complements the theoretical analysis of pipes conveying pulsating fluid.
文摘Supercritical fluid extraction (SFE) of essential oil from dry rhizome ofLigusticum chuanxiong Hort was developed. GC/MS was used for the determination of the composition ofessential oil. Forty-four compounds were identified. The conventional extraction method wasconducted in parallel for comparison. The extracts were qualitatively compared by GC/MS. The yieldsof SFE and steam distillation-extraction were 4.16 % ( v/w) and 0.8 % ( v/w), respectively.Application of SFE of zessential oil from dry rhizome of Ligustiaan chuanxiong Hort was preferable.
文摘The supercritical fluid crystallization technique is a novel technology for preparing ultrafine particles. This paper introduced the concept and features of the technique with an emphasis on three kinds of supercritical fluid crystallization techniques, i.e. rapid expansion of supercritical solutions, supercritical fluid anti-solvent and particles from gas saturated solutions Some questions and the prospect of this technique were also discussed.
基金the financial support from China Postdoctoral Science Foundation(2018M643205)
文摘Tea is a widely consumed beverage and has many important physiological properties and potential health benefits. In this study, a novel method based on supercritical fluid chromatography coupled with mass spectrometry (SFC-MS) was developed to simultaneously determine 11 amino acids in different types of tea (green teas, Oolong tea, black tea and Pu-erh tea). The separation conditions for the analysis of the selected amino acids including the column type, temperature and backpressure as well as the type of additive, were carefully optimized. The best separation of the 11 amino acids was obtained by adding water (5%, v/v) and trifluoroacetic acid (0.4%, v/v) to the organic modifier (methanol). Finally, the developed SFC-MS method was fully validated and successfully applied to the determination of these amino acids in six different tea samples. Good linearity (r ≥ 0.993), precision (RSDs≤ 2.99%), accuracy (91.95%-107.09%) as well as good sample stability were observed. The limits of detection ranged from 1.42 to 14.69 ng/mL, while the limits of quantification were between 4.53 and 47.0 ng/mL. The results indicate that the contents of the 11 amino acids in the six different tea samples are greatly influenced by the degree of fermentation. The proposed SFC-MS method shows a great potential for further investigation of tea varieties.
基金the Natural Science and Technology Foundation of Jilin Province(No.2 0 0 2 0 6 37- 1)
文摘In the present paper is reported the method for the isolation and extraction of total flavonoids of Epimedium Koreanum Nakai by means of supercritical fluid extraction(SFE). By examining pressure, temperature, amounts of modifier and extraction time, the optimized condition of SFE is confirmed as 30 MPa and 60 ℃, with 70% ethanol as the modifier. The samples were statically extracted for 30 min, followed by dynamic extraction for 120 min at a flow rate of 6 mL/min. The quantitative analysis of total flavonoids was performed by UV-Vis spectrophotometry. Compared with the conventional method, the SFE method is more efficient, more rapid and more friendly environmentally.
基金the Natural Science and Technology Foundation of Jilin Province(No 20020637-1)
文摘The herbal plant Acanthopanax Senticosus Harms is natural herb of Changbaishan in Jilin Province of China, which belongs to the Araliaceae family. As the ingredients of folk medicine, it has long been used to treat a variety of human diseases, such as cerebrovascular disease, diabetes, tumor, isochemic heart diseases, hypertension, rheumatic arthritis, etc. E2,33. Flavonoids, a class of constituent compounds, which have a broad distribution in the nature and are found in Acanthopanax Senticosus Harms, have gained particular attention. A number of studies have shown that flavonoid compounds have wide biological activities, such as anti-aging, anticancer, anti-HIV,
文摘A series of TiO 2-MoO 3 nano-composite photocatalysts were prepared by supercritical fluid dry method(SCFD) and an impregnation technique with TiCl 4 and (NH 4) 6Mo 7O 24 ·4H 2O as the starting materials. The catalysts were characterized by the means of XRD, TEM and UV-Vis. Methyl orange was used as model compound for the evaluation of their catalytic activities. The results indicated that the photo-catalyst prepared by SCFD had the advantages of small size(12.84 nm), narrow distribution and good dispersivity. The presence of small amount of Mo in composite catalyst gives rise to the red shift of its absorbance wavelength, decrease of its energy gap and increase of the utility of visible light. Furthermore, higher surface acidity of the photo-catalyst was obtained as the result of the addition of MoO 3. Compared with pure TiO 2, the catalytic activity of the TiO 2-MoO 3 nano-composite photo-catalyst was improved significantly. As the doping concentration of the composite catalysts was controlled at 0.6%(molar percentage), 100% degradation of methyl orange was achieved with in 1.2 h irradiation time.
基金supported by the National Natural Science Foundation of China (Grant No. 21775047)Pearl River S and T Nova Program of Guangzhou, China (Grant No. 201806010055)the Fundamental Research Funds for the Central Universities (Grant No. 2018MS55)
文摘Supercritical fluid chromatography(SFC) meets with great favor due to its high efficiency, low organic solvent consumption, and the specialty for the identification of the isomeric species. This review describes the advances of SFC in targeted and untargeted lipid profiling. The advancement of the SFC instruments and the stationary phases are summarized. Typical applications of SFC to the targeted and untargeted lipid profiling are discussed in detail. Moreover, the perspectives of SFC in the lipid profiling are also proposed. As a useful and promising tool for investigating lipids in vitro and in vivo, SFC will predictably obtain further development.
文摘Owing to an environment-friendly utilization of resources, increased attention has been focused on fuels and chemicals from biomass as an alternative to fossil resources. In addition, supercritical fluid technology has been considered to be an environmentally-benign treatment. Therefore, its technology was applied for a conversion of biomass to useful fuels and chemicals in order to mitigate environmental loading. For example, supercritical water treatment has demonstrated that lignocellulosics can be hydrolyzed to become lignin-derived products for useful aromatic chemicals and carbohydrate-derived products, such as polysaccharides, oligosaccharides and monosaccharides of glucose, mannose and xylose used for subsequent ethanol fermentation. If this treatment is prolonged, lignocellulosics were found to be converted to organic acids such as formic, acetic, glycolic and lactic acids which can be converted to methane for biofuel. When alcohols, such as methanol and ethanol, were used instead of water, some other useful products were achieved, and its liquefied products were found to have a potential for liquid biofuel. In this study, therefore, our research achievements in supercritical fluid science of woody biomass will be introduced for clean and green chemistry for a sustainable environment.
基金Supported partially by the China Ministry of Science and Technology for the China’s Agenda 21 Strategic Research (MOST,2008IM021900)the General Administration of Quality Supervision Inspection and Quarantine of the People’s Republic of China for the 4th Food Safety Research (AQSIQ 2008:ASPAQ0809)
文摘Based on the solubility in supercritical CO2,two strategies in which CO2 plays different roles are used to make quercetine and astaxanthin particles by supercritical fluid technologies.The experimental results showed that micronized quercetine particles with mean particle size of 1.0-1.5 μm can be made via solution enhanced dispersion by supercritical fluids(SEDS) process,in which CO2 worked as turbulent anti-solvent;while for astaxanthin,micronized particles with mean particle size of 0.3-0.8 μm were also made successfully by rapid expansion supercritical solution(RESS) process.
文摘Introduction Ginseng( Panax ginseng C. A. Meyer, Araliaceae) is one of the most valuable Chinese crude drugs and has been used widely for over 2000 years. Studies have demonstrated that ginseng can act on the central nervous system, the cardiovascular system and the endocrine system; it can enhance immune function and metabolism; it possesses a biomodulation action, anticancer effect, anti-stress and anti-ageing activities, and so on.
基金supported financially by the Subject Chief Scientist Program(10XD14303900)from Science and Technology Commission of Shanghai Municipalitythe Specialized Research Fund for the Doctoral Program of Higher Education of China(20123107110005).
文摘The objective of this study was to improve the dissolution and bioavailability of silymarin(SM).Solid dispersions(SDs)were prepared using solution-enhanced dispersion by supercritical fluids(SEDS)and evaluated in vitro and in vivo,compared with pure SM powder.The particle sizes,stability,and contents of residual solvent of the prepared SM-SDs with SEDS and solvent evaporation(SE)were investigated.Four polymer matrix materials were evaluated for the preparation of SM-SD-SEDS,and the hydrophilic polymer,polyvinyl pyrrolidone K17,was selected with a ratio of 1:5 between SM and the polymer.Physicochemical analyses using X-ray diffraction and differential scanning calorimetry indicated that SM was dispersed in SD in an amorphous state.The optimized SM-SD-SEDS showed no loss of SM after storage for 6 months and negligible residual solvent(ethanol)was detected using gas chromatography.In vitro drug release was increased from the SM-SDSEDS,as compared with pure SM powder or SM-SD-SE.In vivo,the area under the rat plasma SM concentration-time curve and the maximum plasma SM concentration were 2.4-fold and 1.9-fold higher,respectively,after oral administration of SM-SD-SEDS as compared with an aqueous SM suspension.These results illustrated the potential of using SEDS to prepare SM-SD,further improving the biopharmaceutical properties of this compound.
基金Supported by the Natural Science Foundation of Ningxia ProvinceInnovation Team Projects in Ningxia Teachers University
文摘Mesoporous zirconia was synthesized by a new and simple method. Zirconium n-propoxide was used as the zirconium source. A small, inexpensive nonsurfactant, triethanolamine, was used as the template. The template was removed by thermal treatment in air and supercritical fluid extraction using CO2. The structure of the resulting materials was characterized by X-ray diffraction, transmission electron microscopy, and N2 adsorption-desorption analyses. The materials are found to have narrowly distributed average pore diameters and wormhole-like pore channels. However, higher surface area and larger pore volume are exhibited after supercritical fluid extraction with CO2. The removal of the template by thermal treatment also leads to condensation and mild shrinkage of the zirconia framework.
文摘Ti-Ce, Ti-Si binary and Ti-Ce-Si ternary novel nanocomposite oxide photocatalysts were prepared with cheap inorganic salts TiCI4, Na2SiO3·9H2O and Ce(NO3)3·6H2O as precursors by supercritical fluid drying (SCFD) technology. The catalysts were characterized by means of XRD and TEM. The particle size of nanocomposite oxide photocatalysts synthesized by SCFD method is about 6 - 11 nm, which is smaller than those obtained by common drying method (CD). The phase transformation from anatase to rutile was inhibited by SCFD technology. The peaks of SiO2 and CeO2 in XRD patterns indicate that a SiO2 amorphorous phase exists in all the samples and CeO2 is well dispersed on the surface of TiO2. The orthogonal test was designed to optimize the preparing conditions. It is found that ceria dop;.ng enhances the photocatalyric activity markedly, and the optimum doping of CeO2 is 0.1%. The thermal stability of photocatalyst can be improved ; the growth of particle-size and the decrease of surface area can be prohibited by doping of SlOe. Heat-treatment is a necessary factor to induce chemistry change of Ti-Si surface. The optimum heat-treating temperature is 600℃. A novel and efficient Ti-Ce-Si ternary nanocomposite was prepared by SCFI) method with strong thermal stability and high photoactivity in the photodegratation of phenol.
文摘TiO_2-CeO_2 nanocomposite particles were prepared with Ce(NO_3)_3·6H_2O and TiCl_4 as precursors by the codeposition method and supercritical fluid drying (SCFD) technology. The particles prepared were characterized by means of XRD, TEM and FTIR. The results show that SCFD can give rise to the direct synthesis of the anatase TiO_2-CeO_2,and the particle size is 6~11 nm under 500 ℃ thermal-treated,smaller than that by common drying (CD). The phase transformation from anatase to rutile is inhibited by supercritical fluid drying technology. The peak of CeO_2 is not observed in XRD patterns,Ce-O band vibration was present in FTIR spectrum,which indicates that CeO_2 is well dispersed on the surface of TiO_2.
基金Supported by the National Natural Science Foundation of China (No. 20576123).
文摘A number of studies have been reported on the applications of supercritical fluids to polymeric processes. The presence of volatiles can affect the end-use properties of polymer materials. Therefore, these volatiles must be reduced to a level below the maximum permissible limit. Conventional heat-relevant techniques for polymer devolatilization sometimes have limited effectiveness. Devolatilization with supercritical fluids, however, can enhance removal of volatiles from polymers. A model for diffusion-limited extraction is used to characterize dynamic supercritical fluid devolatilization of spherical polymer particles. The rate of supercritical fluid devolailization for styrene/polystyrene system is measured at 343 K and 18 MPa and at CO2 flow rate of 1.93, 3.27 and 5.62 L·min^-1, respectively. The model analysis, which is consistent with experimental results, indicates that the supercritical fluid devolatilization is not solubility-limited but diffusion-limited when CO2 flow rate is above 4.00 L·min^-1.
文摘The simultaneous removal of up to 92% of the surfactant template and chemical implantation of transition metal complexes into mesopores has been successfully achieved by treating as-synthesized pure siliceous MCM-41 with supercritical CO2 modified with CH2Cl2/MeOH mixture, resulting in the formation of functionalized material with uniform pore structure.
文摘In 1822, almost 200 years ago, Baron Charles Cagniard de Latour (1777-1859) discovered the critical phenomena or critical state [1] [2]. At that time, it was described as a curiosity. However, it is now used as an advanced extraction and analytical technology in industry and research. Extraction with supercritical fluids (SFs) was welcome from the very beginning. In the present paper, the application to chromatography of the critical phenomena of compressed gases or overheated liquids as supercritical fluids will be discussed. Supercritical Fluid Chromatography (SFC) received an uneasy welcome, mainly because of the lack of commercially available analytical instruments. Even today, only a small number of industrial companies are manufacturing SFC instrumentation. A very small spectrum of columns is manufactured specially for SFC. SFC is not accepted by Pharmacopeia committees for the analysis of drugs and medical forms to the same extent as Gas Chromatography, High-Performance Liquid Chromatography or even Thin Layer Chromatography. The present status and future perspectives for SFC will be discussed.
基金the Basic Research Program from Science,Industry,Trade and Information Technology Commission of Shenzhen Municipality(Grant no.JCYJ20130402145002398)National Natural Science Foundation of China(Grant no.81102824).
文摘The purpose of this study was to investigate the influence of the supercritical CO2 processing on the particle size and morphology of puerarin crystals. The process parameters included solvents, temperature, pressures, antisolvent times, addition volumes, antisolvent addition rates and solute concentrations. After being processed, the dramatic reduction of the dimensions and the change of the crystal shape were noticed. Decreasing the antisolvent addition rate, increasing the temperature and the addition volume below 50 ml led to a decrease in size. The new crystal of puerarin generated at the optimal conditions was 30.34 μm.The solvent of methanol and the concentration of 60 mg/ml were found to determine the type and degree of crystallinity of particles. These results showed that this process has the potential to produce a drug recrystallization product with newly generated crystal forms and the size of drug particles could be controlled through the tuning of various experimental conditions.