Shear thickening fluids (STFs) based on additives with different concentrations and molecular chain lengths were investigated. STF samples were prepared with silica and additive dispersed in polyethylene glycol (PE...Shear thickening fluids (STFs) based on additives with different concentrations and molecular chain lengths were investigated. STF samples were prepared with silica and additive dispersed in polyethylene glycol (PEG) 400, where three types of additives with different molecular chain lengths of PEG4000, PEG6000, and PEG10000 were used. For PEG10000, different concentrations, including 0, 1%, 3%, and 5%, were selected to study the influences of additive concentrations. Rheological properties of the samples were measured with a rheometer. The results show that the shear thickening effect was significantly enhanced with the increase of the concentration and the molecular chain length of additives. The mechanism of enhancement was quantitatively explained with the formation of large particles clusters.展开更多
Cu/SiO2 catalysts prepared by the ammonia evaporation method were applied to hydrogenation of diethyl malonate to 1,3‐propanediol. The calcination temperature played an important role in the structural evolution and ...Cu/SiO2 catalysts prepared by the ammonia evaporation method were applied to hydrogenation of diethyl malonate to 1,3‐propanediol. The calcination temperature played an important role in the structural evolution and catalytic performance of the Cu/SiO2 catalysts, which were systematically characterized by N2 adsorption‐desorption, inductively coupled plasma‐atomic emission spectros‐copy, N2O chemisorption, X‐ray diffraction, Fourier transform infrared spectroscopy, H2 tempera‐ture‐programmed reduction, transmission electron microscopy, and X‐ray photoelectron spectros‐copy. When the Cu/SiO2 catalyst was calcined at 723 K, 90.7%conversion of diethyl malonate and 32.3%selectivity of 1,3‐propanediol were achieved. Compared with Cu/SiO2 catalysts calcined at other temperatures, the enhanced catalytic performance of the Cu/SiO2 catalyst calcined at 723 K can be attributed to better dispersion of copper species, larger cupreous surface area and greater amount of copper phyllosilicate, which results in a higher ratio of Cu+/Cu0. The synergetic effect of Cu0 and Cu+is suggested to be responsible for the optimum activity.展开更多
The solubilities and the refractive indices of the saturated solution in the system C 6H 12 O 6 NH 4Cl C 2H 5OH-H 2O ( C 2H 5OH / H 2O=0.90, by wt ) at 35℃ have been determined. The isotherms and r...The solubilities and the refractive indices of the saturated solution in the system C 6H 12 O 6 NH 4Cl C 2H 5OH-H 2O ( C 2H 5OH / H 2O=0.90, by wt ) at 35℃ have been determined. The isotherms and refractive indices of the system at 35℃ consist of 2 branches, corresponding to C 6H 12 O 6( H 2O and NH 4Cl. The composition of eutectic solution is C 6H 12 O 6: 4.40 %, NH 4Cl: 13.86 %, C 2H 5OH: 38.88 %.展开更多
The solubility and supersolubility of 3,4-bis(3-nitrofurazan-4-yl)furoxan(DNTF) in ethanol + water at different operation were determined by laser monitoring system under atmospheric pressure to study the metastable z...The solubility and supersolubility of 3,4-bis(3-nitrofurazan-4-yl)furoxan(DNTF) in ethanol + water at different operation were determined by laser monitoring system under atmospheric pressure to study the metastable zone width(MSZW). The modified Apelblat equation was adopted to correlate the experimental solubility data, and the correlation result showed perfect consistent with the experimental data. The standard dissolution enthalpy, standard dissolution entropy and Gibbs energy were calculated according to the experimental solubility data. The effect of the cooling rate, stirring rate, temperature and the concentration of ethanol + water on the MSZW was studied. It was found that the MSZW of DNTF increased with the increasing cooling rate, decreasing temperature, decreasing stirring rate and decreasing ratio of water. And the apparent nucleation order of DNTF in ethanol + water was calculated by the relationship between the cooling rate and the MSZW.展开更多
The liver is a common location of both primary and secondary malignancies. For unresectable liver cancer, many local ablative therapies have been developed. These include e.g., percutaneous ethanol injection (PEI), pe...The liver is a common location of both primary and secondary malignancies. For unresectable liver cancer, many local ablative therapies have been developed. These include e.g., percutaneous ethanol injection (PEI), percutaneous acetic acid injection, radiofrequency ablation (RFA), cryoablation, microwave ablation, laserinduced thermotherapy, and high-intensity focused ultrasound. RFA has recently gained interest and is the most widely applied thermoablative technique. RFA allows more effective tumor control in fewer treatment sessions compared with PEI, but with a higher rate of complications. However, there are certain circumstances where PEI therapy represents a better strategy to control liver tumors than RFA, especially in situations where RFA is difficult, for example when large vessels surround the tumor. In the context of hepatocellular carcinoma (HCC), both RFA and PEI are feasible and of benefit in non-operable patients. RFA seems superior to PEI in HCC > 2 cm, and the combination of interventions may be of benefit in selected patients. Liver resection is superior to RFA for patients with HCC meeting the Milan criteria, but RFA can be employed in tumors ≤ 3 cm and where there is an increased expected operative mortality. In addition, some lines of evidence indicate that RFA and PEI can be employed as a bridge to liver transplantation. The use of RFA in colorectal liver metastases is currently limited to unresectable disease and for patients unfit for surgery. The aim of this article is to summarize the current status of RFA in the management of liver tumors and compare it to the cheap and readily available technique of PEI.展开更多
Densities and viscosities were measured as a function of composition for binary liquid mixture of diethylerie glycol monoethyl ether [CH3CH2O(CH2)2O(CH2)2OH] + water from 293.15 to 333.15 K at atmospheric pressur...Densities and viscosities were measured as a function of composition for binary liquid mixture of diethylerie glycol monoethyl ether [CH3CH2O(CH2)2O(CH2)2OH] + water from 293.15 to 333.15 K at atmospheric pressure, with a capillary pycnometer and Ubbelohde capillary viscometer respectively. From the experimental data, the excess molar volume V^E, viscosity deviation △η, and the excess energy of activation for viscous flow △G^*E were calculated. These data were correlated by the Redlich-Kister type equations to obtain the coefficients and standard deviations. The results showed a strong molecular interaction between diethylene glycol monoethyl ether and water.展开更多
Emodin is a kind of anthraquiones with pharmaceutical activities.The solubilities of emodin in ethanol,1-octanol,and ethanol+1-octanol at different temperatures were measured using an analytical method.The solubility ...Emodin is a kind of anthraquiones with pharmaceutical activities.The solubilities of emodin in ethanol,1-octanol,and ethanol+1-octanol at different temperatures were measured using an analytical method.The solubility of emodin in these solvents increased with an increase in temperature.With the temperature deviating from room temperature,the dependence of the solubility of emodin on temperature became a lot more remarkable.The solubility of emodin in ethanol was more sensitive to temperature than that in 1-octanol.The solubility data of emodin in the same species of solvent at different temperatures was correlated with an empirical equation.The calculated results agreed with the experimental data well.展开更多
[Objective] This study aimed to compare the contents of total alkaloids in different solvent extracts from climbing groundsel herb produced in Guizhou Province and their antibacterial activity. [Method] The content of...[Objective] This study aimed to compare the contents of total alkaloids in different solvent extracts from climbing groundsel herb produced in Guizhou Province and their antibacterial activity. [Method] The content of total alkaloids was measured by UV spectrophotometry, and Oxford cups were used to investigate the antibacterial activity of each solvent extract. [Result] There was a good linear correlation between the absorbance measured by the UV spectrophotometer and the content of total al- kaloids within the concentration of 0.011 0-0.054 8 mg/ml at 207 nm, and the re- gression equation was Y=23.654X+0.021, R=0. 999 7 and the average recovery rate was 99.2%. The contents of total alkaloids in 60% ethanol extract, 95% ethanol and water ethanol were 38.71, 52.25 and 60.50 mg/g, respectively. The 60% ethanol ex- tract had strong antibacterial activity against Streptococcus pneumoniae, Staphylo- coccus aureus and Escherichia coil; the water extractive had stronger antibacterial activity against Escherichia colr, 95% ethanol extract had weak antibacterial activity, with no inhibition of Pseudomonas aeruginosa. [Conclusion] This method is accurate, simple, with good repeatability, which can be used for the determination of alkaloids content of the climbing groundsel herb; there is no positive correlation between the content of total alkaloids in different solvent extracts of climbing groundsel herb and their antibacterial activity.展开更多
The extraction of ethanol with the solvents of aldehydes mixed with m-xylene was studied for the bioethanol concentration process.Furfural and benzaldehyde were selected as extraction solvents,with which the solubilit...The extraction of ethanol with the solvents of aldehydes mixed with m-xylene was studied for the bioethanol concentration process.Furfural and benzaldehyde were selected as extraction solvents,with which the solubility of water is small,expecting large distribution coefficient of ethanol.The liquid–liquid two-phase region was the largest with m-xylene solvent,followed by benzaldehyde and furfural.The region of two liquid–liquid phase became larger with the mixed solvent of m-xylene and furfural than that with furfural solvent.The NRTL model was applied to the ethanol–water–furfural–m-xylene system,and the model could well express the liquid–liquid equilibrium of the system.For any solvent used in this study,the separation selectivity of ethanol relative to water decreased as the distribution coefficient of ethanol increased.The separation selectivity with m-xylene was the largest among the employed solvents,but the distribution coefficient was the smallest.The solvent mixture of furfural and m-xylene showed relatively high distribution coefficient of ethanol and separation selectivity,even in the higher mass fraction of m-xylene in the solvent phase.The ethanol extraction with a countercurrent multistage extractor by a continuous operation was simulated to evaluate the extraction performance.The ethanol content could be concentrated in the extract phase with relatively small number of extraction stages but low yield of ethanol was obtained.展开更多
The shear thinning and shear thickening rheological properties of PCC/PEG suspension were investigated with the increase of oscillatory amplitude stress at different constant frequencies. The results show that the com...The shear thinning and shear thickening rheological properties of PCC/PEG suspension were investigated with the increase of oscillatory amplitude stress at different constant frequencies. The results show that the complex viscosity was initially independent of stress amplitude and obvious shear thinning occurred, then dramatic shear thickening took place after reaching the minimum viscosity. Typically, in a constant frequency of 5 rad/s, the elastic modulus, viscous modulus, and tanδ (δ is the out-of-phase angle) vs. the stress amplitude was investigated. It is found that the elastic modulus initially appeared to be independent of stress amplitude and then exhibited a rapid decrease, but the viscous modulus was independent of amplitude stress at lower amplitude stress. After reaching the minimum value the viscous modulus showed a rapid increase. On the other hand, tanδ increased from 0.6 to 92, which indicates that the transition from elastic to viscous had taken place and tanδ showed a steep increase when shear thickening occurred. Lissajous plots are shown for the dissipated energy vs. different maximum stress amplitude in the shear thinning and shear thickening regions. The relationship of dissipated energy vs. maximum stress amplitude was determined, which follows a power law. In the shear thinning region the exponent was 1.91, but it steeply increases to 3.97 in the shear thickening region.展开更多
The solubility of carbon monoxide in phenol+ethanol mixed solvents at elevated pressures is reported in this article. The experimental results revealed the influence of pressure on the solubility of CO in phenol+eth...The solubility of carbon monoxide in phenol+ethanol mixed solvents at elevated pressures is reported in this article. The experimental results revealed the influence of pressure on the solubility of CO in phenol+ethanol mixtures. These mixtures are a poorer solvent for carbon monoxide. The solubility of CO is a linear function of pressure, and the extended Henry's constants were presented at different concentrations of phenol. The cubic Soave-Redlich-Kwong equation of state was used to correlate the experimental gas liquid equilibrium data and to predict the solubility of CO. At the same time, the binary interaction parameters, kO, for CO-phenol, CO-ethanol and phenol-ethanol systems were estimated by fitting experimental GLE data at 303.15 K and at 2.0-9.0 MPa. Hence, a model was suggested for the solubility of CO in phenol+ethanol mixed solvents. The agreement between experimental and calculated solubilities with the proposed model was rather satisfactory.展开更多
[ Objective] The aim was to use response surface methodology to determine optimum conditions for extraction of polysaccharides from Tegillarca granosa. [ Method] Response surface methodology with three-factors and thr...[ Objective] The aim was to use response surface methodology to determine optimum conditions for extraction of polysaccharides from Tegillarca granosa. [ Method] Response surface methodology with three-factors and throe-levels was carried out for optimizing the extraction process of polysacchafides from Tegillarca granosa. A central composite des(gn including independent variables, such as extraction temperature (A), extraction time (B), and ethanol concentration (C) was obtained through Box-Benhnken central combination design. Selected response which evaluates the extraction process was polysacchadde yield. [ Result] The independent variable with the largest effect on response was ethanol concentration (C). The optimum extraction conditions were found to be extraction temperature 69.6℃, extraction time 6.2 h, and ethanol concen- tration of 78% (V/V), respectively. Under these conditions, the extraction efficiency of polysaccharide can increase to 1. 635%. [ Coaclusioa] Study on the extraction of polysaccharides from Tegillarca granosa could provide certain theoretical direction for extracting polysaccharides from Tegillarca granosa on a large scale.展开更多
Continuous homogenous azeotropic distillation(CHAD) and pressure-swing distillation(PSD) are explored to separate a minimum-boiling azeotropic system of ethyl acetate and n-hexane. The CHAD process with acetone as the...Continuous homogenous azeotropic distillation(CHAD) and pressure-swing distillation(PSD) are explored to separate a minimum-boiling azeotropic system of ethyl acetate and n-hexane. The CHAD process with acetone as the entrainer and the PSD process with the pressures of 0.1 MPa and 0.6 MPa in two columns are designed and simulated by Aspen Plus. The operating conditions of the two processes are optimized via a sequential modular approach to obtain the minimum total annual cost(TAC). The computational results show that the partially heat integrated pressure-swing distillation(HIPSD) has reduced in the energy cost and TAC by 40.79% and 35.94%, respectively, than the conventional PSD, and has more greatly reduced the energy cost and TAC by 62.61% and 49.26% respectively compared with the CHAD process. The comparison of CHAD process and partially HIPSD process illustrates that the partially HIPSD has more advantages in averting the product pollution, energy saving, and economy.展开更多
[ Objective] To optimize the ultrasonic-assisted extraction process of chlorogenic acid from sunflower meal. [ Method] Based on the sin-gle-factor test, the extraction factors of ethanol concentration, extraction temp...[ Objective] To optimize the ultrasonic-assisted extraction process of chlorogenic acid from sunflower meal. [ Method] Based on the sin-gle-factor test, the extraction factors of ethanol concentration, extraction temperature and extraction time were optimized using the response surface methodology with the extraction rate of chlorogenic acid as the response value. [ Result] The optimum extraction conditions of chlorogenic acid from sunflower meal were 57% of ethanol concentration, 39 min of extraction time, 53 ~C of extraction temperature, 100 W of ultrasonic power, 1 : 14 ( g/ ml) of solid-liquid ratio and one time of extraction. Under these conditions, the extraction rate of chlorogenic acid was 2.25%. [ Conclusion] Ultra-sonic assisted extraction method has high extraction rate but short time, the study provides a theoretical basis for the industrialized production of chlorogenic acid in sunflower meal.展开更多
The binding energy spectra and electron momentum distributions for the outer valence molecular orbitals of gaseous 2-fluoroethanol have been measured by the non-coplanar asym- metric (e, 2e) spectrometer at impact e...The binding energy spectra and electron momentum distributions for the outer valence molecular orbitals of gaseous 2-fluoroethanol have been measured by the non-coplanar asym- metric (e, 2e) spectrometer at impact energy of 2.5 keV plus binding energy. The quantitative calculations of the ionization energies and the relevant molecular orbitals have been carried out by using the outer-valence Green's function method and the density functional theory with B3LYP hybrid functional. The observed ionization bands in binding energy spectra, as well as the previous photoelectron spectrum which was not assigned, have been assigned for the first time through the comparison between experiment and theory. In general, the the- oretical electron momentum distributions calculated by B3LYP method with aug-cc-pVTZ basis set are in line with the experimental ones when taking into account the Boltzmann- weighted thermo-statistical abundances of five conformers of 2-fluoroethanol.展开更多
In this paper cotton hollow yarns were obtained from the core spun yams which were produced on a little modified conventional experiment ring frame with water soluble staple PVA yam as the core. For comparison, yams w...In this paper cotton hollow yarns were obtained from the core spun yams which were produced on a little modified conventional experiment ring frame with water soluble staple PVA yam as the core. For comparison, yams with same linear densities, same twists of the sheath, different linear densities, different twist directions of the core were prepared. The results show that the tensile strengths of the hollow yarns decrease first, then increase and decrease again, at last the tensile strength trends to reach a steady state with the soluble PVA core extraction proceeding. And when the sheath linear densities of the core spun yams are constant, their twist and twist direction are same as that of the core it will be easier to remove the core of the yam with a higher core size. When the linear densities of the sheath and the core are all constant, the twists of them are same, it will be easier to remove the core of the yam with a different twist direction of core to the sheath.展开更多
Solubility data were first presented for methane in the mixture of ethanol-hexane at temperatures from 291.15K to 318.15K and pressures up to 12.00MPa. The experimental data were correlated by PR and PRSV equations of...Solubility data were first presented for methane in the mixture of ethanol-hexane at temperatures from 291.15K to 318.15K and pressures up to 12.00MPa. The experimental data were correlated by PR and PRSV equations of state with rms errors of about 0.051. The A-K and Y-W-A-K models were both used to estimate liquid molar volume under high pressure. The results were satisfactory.展开更多
Density, ρ, ultrasonic speed, u, and viscosity, η, of binary mixtures of 2-methyl-2-propanol (2M2P) with acetonitrile (AN), propionitrile (PN) and butyronitrile (BN) including those of pure liquids are measured over...Density, ρ, ultrasonic speed, u, and viscosity, η, of binary mixtures of 2-methyl-2-propanol (2M2P) with acetonitrile (AN), propionitrile (PN) and butyronitrile (BN) including those of pure liquids are measured over the entire composition range at temperatures 298.15, 303.15 and 308.15 K. From these experimental data, the excess available volume, E a V , excess free volume, E f V , excess isothermal compressibility, E T β , excess thermal expansion coefficient, E α , and excess internal pressure, E i π , are calculated. The variation of these properties with composition and temperature are discussed in terms of molecular interactions between unlike molecules of the mixtures. It is found that the values of E a V , E f V , E T β and E α are positive and those of E i π are negative for all the mixtures at each temperature studied, indicating the presence of weak interactions between 2M2P and AN/PN/BN molecules. The variations of E a V , E f V , E T β , E α and E i π values with composition indicate that the interactions in these mixtures follow the order: AN<PN<BN, i.e., the 2M2P-nitrile interaction decreases with the increase of alkyl chain length in these nitrile molecules. In addition, the theoretical ultrasonic velocity is calculated using the scaled particle theory and compared with the experimental values.展开更多
文摘Shear thickening fluids (STFs) based on additives with different concentrations and molecular chain lengths were investigated. STF samples were prepared with silica and additive dispersed in polyethylene glycol (PEG) 400, where three types of additives with different molecular chain lengths of PEG4000, PEG6000, and PEG10000 were used. For PEG10000, different concentrations, including 0, 1%, 3%, and 5%, were selected to study the influences of additive concentrations. Rheological properties of the samples were measured with a rheometer. The results show that the shear thickening effect was significantly enhanced with the increase of the concentration and the molecular chain length of additives. The mechanism of enhancement was quantitatively explained with the formation of large particles clusters.
文摘Cu/SiO2 catalysts prepared by the ammonia evaporation method were applied to hydrogenation of diethyl malonate to 1,3‐propanediol. The calcination temperature played an important role in the structural evolution and catalytic performance of the Cu/SiO2 catalysts, which were systematically characterized by N2 adsorption‐desorption, inductively coupled plasma‐atomic emission spectros‐copy, N2O chemisorption, X‐ray diffraction, Fourier transform infrared spectroscopy, H2 tempera‐ture‐programmed reduction, transmission electron microscopy, and X‐ray photoelectron spectros‐copy. When the Cu/SiO2 catalyst was calcined at 723 K, 90.7%conversion of diethyl malonate and 32.3%selectivity of 1,3‐propanediol were achieved. Compared with Cu/SiO2 catalysts calcined at other temperatures, the enhanced catalytic performance of the Cu/SiO2 catalyst calcined at 723 K can be attributed to better dispersion of copper species, larger cupreous surface area and greater amount of copper phyllosilicate, which results in a higher ratio of Cu+/Cu0. The synergetic effect of Cu0 and Cu+is suggested to be responsible for the optimum activity.
文摘The solubilities and the refractive indices of the saturated solution in the system C 6H 12 O 6 NH 4Cl C 2H 5OH-H 2O ( C 2H 5OH / H 2O=0.90, by wt ) at 35℃ have been determined. The isotherms and refractive indices of the system at 35℃ consist of 2 branches, corresponding to C 6H 12 O 6( H 2O and NH 4Cl. The composition of eutectic solution is C 6H 12 O 6: 4.40 %, NH 4Cl: 13.86 %, C 2H 5OH: 38.88 %.
文摘The solubility and supersolubility of 3,4-bis(3-nitrofurazan-4-yl)furoxan(DNTF) in ethanol + water at different operation were determined by laser monitoring system under atmospheric pressure to study the metastable zone width(MSZW). The modified Apelblat equation was adopted to correlate the experimental solubility data, and the correlation result showed perfect consistent with the experimental data. The standard dissolution enthalpy, standard dissolution entropy and Gibbs energy were calculated according to the experimental solubility data. The effect of the cooling rate, stirring rate, temperature and the concentration of ethanol + water on the MSZW was studied. It was found that the MSZW of DNTF increased with the increasing cooling rate, decreasing temperature, decreasing stirring rate and decreasing ratio of water. And the apparent nucleation order of DNTF in ethanol + water was calculated by the relationship between the cooling rate and the MSZW.
文摘The liver is a common location of both primary and secondary malignancies. For unresectable liver cancer, many local ablative therapies have been developed. These include e.g., percutaneous ethanol injection (PEI), percutaneous acetic acid injection, radiofrequency ablation (RFA), cryoablation, microwave ablation, laserinduced thermotherapy, and high-intensity focused ultrasound. RFA has recently gained interest and is the most widely applied thermoablative technique. RFA allows more effective tumor control in fewer treatment sessions compared with PEI, but with a higher rate of complications. However, there are certain circumstances where PEI therapy represents a better strategy to control liver tumors than RFA, especially in situations where RFA is difficult, for example when large vessels surround the tumor. In the context of hepatocellular carcinoma (HCC), both RFA and PEI are feasible and of benefit in non-operable patients. RFA seems superior to PEI in HCC > 2 cm, and the combination of interventions may be of benefit in selected patients. Liver resection is superior to RFA for patients with HCC meeting the Milan criteria, but RFA can be employed in tumors ≤ 3 cm and where there is an increased expected operative mortality. In addition, some lines of evidence indicate that RFA and PEI can be employed as a bridge to liver transplantation. The use of RFA in colorectal liver metastases is currently limited to unresectable disease and for patients unfit for surgery. The aim of this article is to summarize the current status of RFA in the management of liver tumors and compare it to the cheap and readily available technique of PEI.
文摘Densities and viscosities were measured as a function of composition for binary liquid mixture of diethylerie glycol monoethyl ether [CH3CH2O(CH2)2O(CH2)2OH] + water from 293.15 to 333.15 K at atmospheric pressure, with a capillary pycnometer and Ubbelohde capillary viscometer respectively. From the experimental data, the excess molar volume V^E, viscosity deviation △η, and the excess energy of activation for viscous flow △G^*E were calculated. These data were correlated by the Redlich-Kister type equations to obtain the coefficients and standard deviations. The results showed a strong molecular interaction between diethylene glycol monoethyl ether and water.
基金Supported by the National Natural Science Foundation of China (20406008).
文摘Emodin is a kind of anthraquiones with pharmaceutical activities.The solubilities of emodin in ethanol,1-octanol,and ethanol+1-octanol at different temperatures were measured using an analytical method.The solubility of emodin in these solvents increased with an increase in temperature.With the temperature deviating from room temperature,the dependence of the solubility of emodin on temperature became a lot more remarkable.The solubility of emodin in ethanol was more sensitive to temperature than that in 1-octanol.The solubility data of emodin in the same species of solvent at different temperatures was correlated with an empirical equation.The calculated results agreed with the experimental data well.
基金Supported by the Clinical Scientific Research Capacity Construction Program for Country-level Hospitals of Department of Health,Guizhou Province(gzwxky2011-1-022)~~
文摘[Objective] This study aimed to compare the contents of total alkaloids in different solvent extracts from climbing groundsel herb produced in Guizhou Province and their antibacterial activity. [Method] The content of total alkaloids was measured by UV spectrophotometry, and Oxford cups were used to investigate the antibacterial activity of each solvent extract. [Result] There was a good linear correlation between the absorbance measured by the UV spectrophotometer and the content of total al- kaloids within the concentration of 0.011 0-0.054 8 mg/ml at 207 nm, and the re- gression equation was Y=23.654X+0.021, R=0. 999 7 and the average recovery rate was 99.2%. The contents of total alkaloids in 60% ethanol extract, 95% ethanol and water ethanol were 38.71, 52.25 and 60.50 mg/g, respectively. The 60% ethanol ex- tract had strong antibacterial activity against Streptococcus pneumoniae, Staphylo- coccus aureus and Escherichia coil; the water extractive had stronger antibacterial activity against Escherichia colr, 95% ethanol extract had weak antibacterial activity, with no inhibition of Pseudomonas aeruginosa. [Conclusion] This method is accurate, simple, with good repeatability, which can be used for the determination of alkaloids content of the climbing groundsel herb; there is no positive correlation between the content of total alkaloids in different solvent extracts of climbing groundsel herb and their antibacterial activity.
文摘The extraction of ethanol with the solvents of aldehydes mixed with m-xylene was studied for the bioethanol concentration process.Furfural and benzaldehyde were selected as extraction solvents,with which the solubility of water is small,expecting large distribution coefficient of ethanol.The liquid–liquid two-phase region was the largest with m-xylene solvent,followed by benzaldehyde and furfural.The region of two liquid–liquid phase became larger with the mixed solvent of m-xylene and furfural than that with furfural solvent.The NRTL model was applied to the ethanol–water–furfural–m-xylene system,and the model could well express the liquid–liquid equilibrium of the system.For any solvent used in this study,the separation selectivity of ethanol relative to water decreased as the distribution coefficient of ethanol increased.The separation selectivity with m-xylene was the largest among the employed solvents,but the distribution coefficient was the smallest.The solvent mixture of furfural and m-xylene showed relatively high distribution coefficient of ethanol and separation selectivity,even in the higher mass fraction of m-xylene in the solvent phase.The ethanol extraction with a countercurrent multistage extractor by a continuous operation was simulated to evaluate the extraction performance.The ethanol content could be concentrated in the extract phase with relatively small number of extraction stages but low yield of ethanol was obtained.
基金ACKNOWLEDGMENT This work was supported by the National Natural Science Foundation of China (No.50774096 and No.50604017).
文摘The shear thinning and shear thickening rheological properties of PCC/PEG suspension were investigated with the increase of oscillatory amplitude stress at different constant frequencies. The results show that the complex viscosity was initially independent of stress amplitude and obvious shear thinning occurred, then dramatic shear thickening took place after reaching the minimum viscosity. Typically, in a constant frequency of 5 rad/s, the elastic modulus, viscous modulus, and tanδ (δ is the out-of-phase angle) vs. the stress amplitude was investigated. It is found that the elastic modulus initially appeared to be independent of stress amplitude and then exhibited a rapid decrease, but the viscous modulus was independent of amplitude stress at lower amplitude stress. After reaching the minimum value the viscous modulus showed a rapid increase. On the other hand, tanδ increased from 0.6 to 92, which indicates that the transition from elastic to viscous had taken place and tanδ showed a steep increase when shear thickening occurred. Lissajous plots are shown for the dissipated energy vs. different maximum stress amplitude in the shear thinning and shear thickening regions. The relationship of dissipated energy vs. maximum stress amplitude was determined, which follows a power law. In the shear thinning region the exponent was 1.91, but it steeply increases to 3.97 in the shear thickening region.
基金Supported by the National Natural Science Foundation of China (20476083, 50576028).
文摘The solubility of carbon monoxide in phenol+ethanol mixed solvents at elevated pressures is reported in this article. The experimental results revealed the influence of pressure on the solubility of CO in phenol+ethanol mixtures. These mixtures are a poorer solvent for carbon monoxide. The solubility of CO is a linear function of pressure, and the extended Henry's constants were presented at different concentrations of phenol. The cubic Soave-Redlich-Kwong equation of state was used to correlate the experimental gas liquid equilibrium data and to predict the solubility of CO. At the same time, the binary interaction parameters, kO, for CO-phenol, CO-ethanol and phenol-ethanol systems were estimated by fitting experimental GLE data at 303.15 K and at 2.0-9.0 MPa. Hence, a model was suggested for the solubility of CO in phenol+ethanol mixed solvents. The agreement between experimental and calculated solubilities with the proposed model was rather satisfactory.
基金Supported by Key Scientific Research Program of Wannan MedicalCollege ( WK2012Z208)
文摘[ Objective] The aim was to use response surface methodology to determine optimum conditions for extraction of polysaccharides from Tegillarca granosa. [ Method] Response surface methodology with three-factors and throe-levels was carried out for optimizing the extraction process of polysacchafides from Tegillarca granosa. A central composite des(gn including independent variables, such as extraction temperature (A), extraction time (B), and ethanol concentration (C) was obtained through Box-Benhnken central combination design. Selected response which evaluates the extraction process was polysacchadde yield. [ Result] The independent variable with the largest effect on response was ethanol concentration (C). The optimum extraction conditions were found to be extraction temperature 69.6℃, extraction time 6.2 h, and ethanol concen- tration of 78% (V/V), respectively. Under these conditions, the extraction efficiency of polysaccharide can increase to 1. 635%. [ Coaclusioa] Study on the extraction of polysaccharides from Tegillarca granosa could provide certain theoretical direction for extracting polysaccharides from Tegillarca granosa on a large scale.
基金Supported by the Education Foundation of Chongqing(KJ1712307)the Application Technology Research and Developments Foundation of Fuling Technology Board(FLKJ,2016ABA1026)the Young Foundation of Yangtze Normal University(2015XJXM03)
文摘Continuous homogenous azeotropic distillation(CHAD) and pressure-swing distillation(PSD) are explored to separate a minimum-boiling azeotropic system of ethyl acetate and n-hexane. The CHAD process with acetone as the entrainer and the PSD process with the pressures of 0.1 MPa and 0.6 MPa in two columns are designed and simulated by Aspen Plus. The operating conditions of the two processes are optimized via a sequential modular approach to obtain the minimum total annual cost(TAC). The computational results show that the partially heat integrated pressure-swing distillation(HIPSD) has reduced in the energy cost and TAC by 40.79% and 35.94%, respectively, than the conventional PSD, and has more greatly reduced the energy cost and TAC by 62.61% and 49.26% respectively compared with the CHAD process. The comparison of CHAD process and partially HIPSD process illustrates that the partially HIPSD has more advantages in averting the product pollution, energy saving, and economy.
基金Supported by the Science and Technology Program of Jilin Education Department during the"Eleventh-Five Year Plan" (Jilin[2010]No.206)
文摘[ Objective] To optimize the ultrasonic-assisted extraction process of chlorogenic acid from sunflower meal. [ Method] Based on the sin-gle-factor test, the extraction factors of ethanol concentration, extraction temperature and extraction time were optimized using the response surface methodology with the extraction rate of chlorogenic acid as the response value. [ Result] The optimum extraction conditions of chlorogenic acid from sunflower meal were 57% of ethanol concentration, 39 min of extraction time, 53 ~C of extraction temperature, 100 W of ultrasonic power, 1 : 14 ( g/ ml) of solid-liquid ratio and one time of extraction. Under these conditions, the extraction rate of chlorogenic acid was 2.25%. [ Conclusion] Ultra-sonic assisted extraction method has high extraction rate but short time, the study provides a theoretical basis for the industrialized production of chlorogenic acid in sunflower meal.
基金This work was supported by the National Basic Research Program of China (No.2010CB923301) and the National Natural Science Foundation of China (No.11327404, No.20973160, No.10904136). The au- thors also gratefully acknowledge Professor C. E. Brion from the University of British Columbia (UBC) in Canada for giving us the HEMS programs.
文摘The binding energy spectra and electron momentum distributions for the outer valence molecular orbitals of gaseous 2-fluoroethanol have been measured by the non-coplanar asym- metric (e, 2e) spectrometer at impact energy of 2.5 keV plus binding energy. The quantitative calculations of the ionization energies and the relevant molecular orbitals have been carried out by using the outer-valence Green's function method and the density functional theory with B3LYP hybrid functional. The observed ionization bands in binding energy spectra, as well as the previous photoelectron spectrum which was not assigned, have been assigned for the first time through the comparison between experiment and theory. In general, the the- oretical electron momentum distributions calculated by B3LYP method with aug-cc-pVTZ basis set are in line with the experimental ones when taking into account the Boltzmann- weighted thermo-statistical abundances of five conformers of 2-fluoroethanol.
基金Supported by the Foundation of Tianjin Science and Technology Commission (No.043104711)
文摘In this paper cotton hollow yarns were obtained from the core spun yams which were produced on a little modified conventional experiment ring frame with water soluble staple PVA yam as the core. For comparison, yams with same linear densities, same twists of the sheath, different linear densities, different twist directions of the core were prepared. The results show that the tensile strengths of the hollow yarns decrease first, then increase and decrease again, at last the tensile strength trends to reach a steady state with the soluble PVA core extraction proceeding. And when the sheath linear densities of the core spun yams are constant, their twist and twist direction are same as that of the core it will be easier to remove the core of the yam with a higher core size. When the linear densities of the sheath and the core are all constant, the twists of them are same, it will be easier to remove the core of the yam with a different twist direction of core to the sheath.
文摘Solubility data were first presented for methane in the mixture of ethanol-hexane at temperatures from 291.15K to 318.15K and pressures up to 12.00MPa. The experimental data were correlated by PR and PRSV equations of state with rms errors of about 0.051. The A-K and Y-W-A-K models were both used to estimate liquid molar volume under high pressure. The results were satisfactory.
文摘Density, ρ, ultrasonic speed, u, and viscosity, η, of binary mixtures of 2-methyl-2-propanol (2M2P) with acetonitrile (AN), propionitrile (PN) and butyronitrile (BN) including those of pure liquids are measured over the entire composition range at temperatures 298.15, 303.15 and 308.15 K. From these experimental data, the excess available volume, E a V , excess free volume, E f V , excess isothermal compressibility, E T β , excess thermal expansion coefficient, E α , and excess internal pressure, E i π , are calculated. The variation of these properties with composition and temperature are discussed in terms of molecular interactions between unlike molecules of the mixtures. It is found that the values of E a V , E f V , E T β and E α are positive and those of E i π are negative for all the mixtures at each temperature studied, indicating the presence of weak interactions between 2M2P and AN/PN/BN molecules. The variations of E a V , E f V , E T β , E α and E i π values with composition indicate that the interactions in these mixtures follow the order: AN<PN<BN, i.e., the 2M2P-nitrile interaction decreases with the increase of alkyl chain length in these nitrile molecules. In addition, the theoretical ultrasonic velocity is calculated using the scaled particle theory and compared with the experimental values.