The accelerating factor (AF) method is a simple and appropriate way to investigate the atomic long-time deep diffusion at solid-solid interface. In the framework of AF hyperdynamics (HD) simulation, the relationsh...The accelerating factor (AF) method is a simple and appropriate way to investigate the atomic long-time deep diffusion at solid-solid interface. In the framework of AF hyperdynamics (HD) simulation, the relationship between the diffusion coefficient along the direction of z-axis which is normal to the Mg/Zn interface and temperature was investigated, and the AF's impact on the diffusion constant (D0) and activation energy (Q^*) was studied. Then, two steps were taken to simulate the atomic diffusion process and the formation of new phases: one for acceleration and the other for equilibration. The results show that: the Arrhenius equation works well for the description of Dz with different accelerating factors; the AF has no effect on the diffusion constant Do in the case of no phase transition; and the relationship between Q* and Q conforms to Q^*=Q/A. Then, the new Arrhenius equation for AFHD is successfully constructed as Dz=Doexp[-Q/(ART)]. Meanwhile, the authentic equilibrium conformations at any dynamic moment can only be reproduced by the equilibration simulation of the HD-simulated configurations. Key words: accelerating factor method; Arrhenius equation; two-steps scheme; Mg/Zn interface; hyperdynamic simulation展开更多
[Objective] Ginger essential oil (GEO) is widely used in food production and medical field in recent years due to its prominent biological functions, and this study was conducted to obtain high-quality and high-puri...[Objective] Ginger essential oil (GEO) is widely used in food production and medical field in recent years due to its prominent biological functions, and this study was conducted to obtain high-quality and high-purity ginger essential oil from the fresh ginger. [Method] GEO was extracted from ginger roots by supercritical fluid extraction (SFE) method. The effects of flow rate of CO2, mesh size of ginger powder and volume of entrainer were investigated by single-factor experiments and response surface method. The content and extraction rate of 6-gingerol represented the extraction index of GEO. [Result] The conditions were optimized as follows: flow rate of CO2 at 25 L/h, mesh size of ginger power of 80 mesh, and volume of anhydrous ethanol as entrainer of 92.46 ml. The optimal extraction rate of 6-gingerol was 3.21%, which was predicted by RSM. [Conclusion] The optimal process of supercritical carbon dioxide extraction of ginger essential oil was identified by singlefactor experiments and response surface method. The present study provides a satisfactory method for purifying GEO from ginger for industrial purpose.展开更多
A learning algorithm based on a hard limiter for feedforward neural networks (NN) is presented,and is applied in solving classification problems on separable convex sets and disjoint sets.It has been proved that the a...A learning algorithm based on a hard limiter for feedforward neural networks (NN) is presented,and is applied in solving classification problems on separable convex sets and disjoint sets.It has been proved that the algorithm has stronger classification ability than that of the back propagation (BP) algorithm for the feedforward NN using sigmoid function by simulation.What is more,the models can be implemented with lower cost hardware than that of the BP NN.LEARNIN展开更多
Most of the developed immune based classifiers generate antibodies randomly, which has negative effect on the classification performance. In order to guide the antibody generation effectively, a decision hyper plane h...Most of the developed immune based classifiers generate antibodies randomly, which has negative effect on the classification performance. In order to guide the antibody generation effectively, a decision hyper plane heuristic based artificial immune network classification algorithm (DHPA1NC) is proposed. DHPAINC taboos the inner regions of the class domain, thus, the antibody generation is limited near the class domain boundary. Then, the antibodies are evaluated by their recognition abilities, and the antibodies of low recognition abilities are removed to avoid over-fitting. Finally, the high quality antibodies tend to be stable in the immune network. The algorithm was applied to two simulated datasets classification, and the results show that the decision hyper planes determined by the antibodies fit the class domain boundaries well. Moreover, the algorithm was applied to UCI datasets classification and emotional speech recognition, and the results show that the algorithm has good performance, which means that DHPAINC is a promising classifier.展开更多
In order to estimate and detect the surface defect depth of metals, the transmission method of laser ultrasonic surface waves is used in this work. The laser ultrasonic detection platform taking use of thermoelastic m...In order to estimate and detect the surface defect depth of metals, the transmission method of laser ultrasonic surface waves is used in this work. The laser ultrasonic detection platform taking use of thermoelastic mechanism as acoustic signal excitation method and interference receiver as acoustic signal receiver method was built, by which B-scan images of detected specimens with surface defects were collected to establish the relationship between the transmission coefficient and depth of the surface defect. Experimental results show that the amplitude of transmitted acoustic signal is related to the depth of surface defect. At last, a fitted curve of transmission coefficient using measured experimental data is obtained to estimate depth of surface defect on the 6061 aluminum alloy. Furthermore, a surface defect depth of 0.3 mm is estimated by the fitting curve with an estimated error of 16%. Therefore, a experimental method using the transmission method by laser ultrasonic is presented in this paper.展开更多
A numerical model was established to predict and optimise the chemical cleaning process of Polyvinylidene Fluo- ride (PVDF) Ultrafiltration (UF) membranes with the results from the experiment that applied the Resp...A numerical model was established to predict and optimise the chemical cleaning process of Polyvinylidene Fluo- ride (PVDF) Ultrafiltration (UF) membranes with the results from the experiment that applied the Response Sur- face Method (RSM) and Central Composite Design (CCD). The factors considered in the experimental design were sodium hydroxide (NaOH) concentration, sodium bypochlorite concentration (NaCIO), citric acid concentration and cleaning duration, The interactions between the factors were investigated with the numerical model. Humic acid (20 mg· L-1) was used as the model foulant, and chemical enhanced backflush (CEB) was employed to sim- ulate the chemical cleaning process. The concentrations of sodium hydroxide, sodium hypochlorite, citric acid and cleaning duration tested during the experiments were in the range of 0.1%-0.3% 100-300 mg· L-1 1%-3% and 0.5-1.5 h, respectively. Among the variables, the sodium hypochlorite concentration and the cleaning dura- tion showed a positive relationship involving the increased efficiency of the chemical cleaning. The chemical cleaning efficiency was hardly improved with increasing concentrations of sodium hydroxide. However, the data was sharply decreased when at a low level of sodium hydroxide concentration. In total, 54 sets of cleaning schemes with 80% to 100K cleaning efficiency were observed with the R&M model after calibration.展开更多
Due to the influence of joint fissure, mining intensity, designed slope angle, underground water and rainfall, the failure process of mine slope project is extremely complicated. The current safety factor calculation ...Due to the influence of joint fissure, mining intensity, designed slope angle, underground water and rainfall, the failure process of mine slope project is extremely complicated. The current safety factor calculation method has certain limitations, and it would be difficult to obtain the reliability index when the performance function of reliability analysis is implicit or has high order terms. Therefore, with the help of the logistic equation of chaos theory, a new algorithm of mine slope reliability based on limiting state hyper-plane is proposed. It is shown that by using this new reliability algorithm the calculation of partial derivative of performance function is avoided, and it has the advantages of being simple and easy to program. The new algorithm is suitable for calculating the reliability index of complex performance function containing high order terms. Furthermore, the limiting state hyper-plane models of both simplified Bishop's and Janbu's method adaptive to slope project are obtained, and have achieved satisfactory effect in the study of mine slope stability in Dexing copper open pit.展开更多
Jatropha curcas L. (JCL) seeds were extracted and transesterified in-situ using supercritical methanol extraction in the absence of catalyst at different temperatures (200-280℃) and pressures (8-12 MPa), and at...Jatropha curcas L. (JCL) seeds were extracted and transesterified in-situ using supercritical methanol extraction in the absence of catalyst at different temperatures (200-280℃) and pressures (8-12 MPa), and at a fixed reaction time of 30 min with seeds-to-methanol ratio of 1:40 w/v. Design of experiment approach using five-level-two-factors design of Response Surface Methodology (RSM) was used to observe the effect of two independent variables i.e. temperature and pressure and the percent of biodiesel yield which required 13 runs. For optimization of the variables, Central Composite Rotatable Design (CCRD) was used for regression analysis and analysis of variance (ANOVA). The optimize conditions suggested by RSM were at T = 280℃ and P = 12.04 MPa. The predicted and experimental biodicsel yields were found to be 56.8% and 59.9%, respectively, with relatively small deviation errors of 1.59%.展开更多
Multi-level inverters(MLIs)have become popular in different applications such as industrial power control systems and distributed generations.There are different forms of MLIs.The cascaded MLIs(CMLIs)have some special...Multi-level inverters(MLIs)have become popular in different applications such as industrial power control systems and distributed generations.There are different forms of MLIs.The cascaded MLIs(CMLIs)have some special advantages among them such as more different output voltage levels using the same number of components and higher power quality.In this paper,a 27-level inverter switching algorithm considering total harmonic distortion(THD)minimization is investigated.Switching angles of the inverter switches are achieved by minimizing a THD-based objective function.In order to minimize the THD-based objective function,the hyper-spherical search(HSS)algorithm,as a novel optimization algorithm,is improved and the results of improved HSS(IHSS)are compared with HSS algorithm and other five evolutionary algorithms to show the advantages of IHSS algorithm.展开更多
A new heuristic algorithm is proposed for solving general integer linear programming problems. In the algorithm, the objective function hyperplane is used as a cutting plane, and then by introducing a special set of a...A new heuristic algorithm is proposed for solving general integer linear programming problems. In the algorithm, the objective function hyperplane is used as a cutting plane, and then by introducing a special set of assistant sets, an efficient heuristic search for the solution to the integer linear program is carried out in the sets on the objective function hyperplane. A simple numerical example shows that the algorithm is efficient for some problems, and therefore, of practical interest.展开更多
A new method for optimizing a butterfly-shaped linear ultrasonic motor was proposed to maximize its mechanical output. The finite element analysis technology and response surface methodology were combined together to ...A new method for optimizing a butterfly-shaped linear ultrasonic motor was proposed to maximize its mechanical output. The finite element analysis technology and response surface methodology were combined together to realize the optimal design of the butterfly-shaped linear ultrasonic motor. First, the operation principle of the motor was introduced. Second, the finite element parameterized model of the stator of the motor was built using ANSYS parametric design language and some structure parameters of the stator were selected as design variables. Third, the sample points were selected in design variable space using latin hypercube Design. Through modal analysis and harmonic response analysis of the stator based on these sample points, the target responses were obtained. These sample points and response values were combined together to build a response surface model. Finally, the simplex method was used to find the optimal solution. The experimental results showed that many aspects of the design requirements of the butterfly-shaped linear ultrasonic motor have been fulfilled. The prototype motor fabricated based on the optimal design result exhibited considerably high dynamic performance, such as no-load speed of 873 ram/s, maximal thrust of 27.5 N, maximal efficiency of 43%, and thrust-weight ratio of 45.8.展开更多
The aim of the present study was to optimize the supercritical CO_2 extraction conditions of icariin from Herba Epimedii by response surface method(RSM) and central composite design(CCD).A 3-factor,5-level CCD was use...The aim of the present study was to optimize the supercritical CO_2 extraction conditions of icariin from Herba Epimedii by response surface method(RSM) and central composite design(CCD).A 3-factor,5-level CCD was used for the optimization.Independent variables were extraction temperature,extraction pressure and entrainer flow rate.Dependent variable was yield ratio of icariin from Herba Epimedii.A two-order polynomial equation was fitted to the data.The results showed that the optimum extraction conditions were as follows:extraction temperature 46.5℃,extraction pressure 30.6 MPa,entrainer flow rate 3.3 mL/min.CCD/ RSM is convenient and highly predictive for optimizing the extraction process of icariin from Herba Epimedii.展开更多
Cimicifugae Rhizome (RC) is one of many commonly used traditional Chinese medicines. This study used Box-Behnken Design (BBD), a widely used form of response surface methodology (RSM), to optimize the conditions...Cimicifugae Rhizome (RC) is one of many commonly used traditional Chinese medicines. This study used Box-Behnken Design (BBD), a widely used form of response surface methodology (RSM), to optimize the conditions of the ultrasound-assisted extraction (UAE) for the extraction of phenolic compounds from CimicifugaeRhizome. The influence of three independent variables, including ethanol concentration (%), extraction time (min) and solvent-to-material ratio (mL/g), on the extraction yields of phenolic compounds were examined. The results demonstrated that the optimal ultrasound-assisted extraction (UAE) conditions were as follows: ethanol concentration of 68%, an extraction time of 19 min, and solvent-to-material ratio of 30 mL/g for the extraction of caffeic acid, cimicifugoside, ferulic acid, isoferulicacid, cimifugin, 4′-O-β-glucopyranosyl-5-O-methylvisamminol. These results demonstrated the suitability of UAE for the extraction of phenolic compounds from CimicifugaeRhizome.展开更多
Over the past decade, ultrathin lanthanide oxides (Ln2O3, Ln = La to Lu) nanomaterials have been intensively studied in the fields of rare earth materials science. This unique class of nanomaterials has shown many u...Over the past decade, ultrathin lanthanide oxides (Ln2O3, Ln = La to Lu) nanomaterials have been intensively studied in the fields of rare earth materials science. This unique class of nanomaterials has shown many unprecedented properties (big surface area, high surface effect, physical and chemical activities) and is thus being explored for numerous promising applications. In this review, a brief introduction of ultrathin Ln2O3 nanomaterials was given and their unique advantages were highlighted. Then, the typical synthetic methodologies were summarized and compared (thermal decomposition, solvothermal, soft template, co-precipition and microwave etc.). Due to the high surface effect, some promising applications of ultmthin Ln203 nanomaterials, such as drug delivery and catalysis of CO oxidation, were reviewed. Finally, on the basis of current achievements on ultrathin Ln203 nanomaterials, personal perspectives and challenges on future research directions were proposed.展开更多
kinematic Euclidean By using the moving frame method, the authors obtain a kind of asymmetric formulas for the total mean curvatures of hypersurfaces in the n-dimensional space
基金Project (2012CB722805) supported by the National Basic Research Program of ChinaProjects (50974083, 51174131) supported by the National Natural Science Foundation of China+1 种基金Project (50774112) supported by the Joint Fund of NSFC and Baosteel, ChinaProject(07QA4021) supported by the Shanghai "Phosphor" Science Foundation, China
文摘The accelerating factor (AF) method is a simple and appropriate way to investigate the atomic long-time deep diffusion at solid-solid interface. In the framework of AF hyperdynamics (HD) simulation, the relationship between the diffusion coefficient along the direction of z-axis which is normal to the Mg/Zn interface and temperature was investigated, and the AF's impact on the diffusion constant (D0) and activation energy (Q^*) was studied. Then, two steps were taken to simulate the atomic diffusion process and the formation of new phases: one for acceleration and the other for equilibration. The results show that: the Arrhenius equation works well for the description of Dz with different accelerating factors; the AF has no effect on the diffusion constant Do in the case of no phase transition; and the relationship between Q* and Q conforms to Q^*=Q/A. Then, the new Arrhenius equation for AFHD is successfully constructed as Dz=Doexp[-Q/(ART)]. Meanwhile, the authentic equilibrium conformations at any dynamic moment can only be reproduced by the equilibration simulation of the HD-simulated configurations. Key words: accelerating factor method; Arrhenius equation; two-steps scheme; Mg/Zn interface; hyperdynamic simulation
基金Supported by the Natural Science Foundation of Higher Education Institutions of Jiangsu Province(16KJA550001)~~
文摘[Objective] Ginger essential oil (GEO) is widely used in food production and medical field in recent years due to its prominent biological functions, and this study was conducted to obtain high-quality and high-purity ginger essential oil from the fresh ginger. [Method] GEO was extracted from ginger roots by supercritical fluid extraction (SFE) method. The effects of flow rate of CO2, mesh size of ginger powder and volume of entrainer were investigated by single-factor experiments and response surface method. The content and extraction rate of 6-gingerol represented the extraction index of GEO. [Result] The conditions were optimized as follows: flow rate of CO2 at 25 L/h, mesh size of ginger power of 80 mesh, and volume of anhydrous ethanol as entrainer of 92.46 ml. The optimal extraction rate of 6-gingerol was 3.21%, which was predicted by RSM. [Conclusion] The optimal process of supercritical carbon dioxide extraction of ginger essential oil was identified by singlefactor experiments and response surface method. The present study provides a satisfactory method for purifying GEO from ginger for industrial purpose.
文摘A learning algorithm based on a hard limiter for feedforward neural networks (NN) is presented,and is applied in solving classification problems on separable convex sets and disjoint sets.It has been proved that the algorithm has stronger classification ability than that of the back propagation (BP) algorithm for the feedforward NN using sigmoid function by simulation.What is more,the models can be implemented with lower cost hardware than that of the BP NN.LEARNIN
基金Foundation item: Projects(61170199, 60874070) supported by the National Natural Science Foundation of China Project(11A004) supported by the Major Project of Education Department in Hunan Province, China Project(2010GK3067) supported by Science and Technology Planning of Hunan Province, China
文摘Most of the developed immune based classifiers generate antibodies randomly, which has negative effect on the classification performance. In order to guide the antibody generation effectively, a decision hyper plane heuristic based artificial immune network classification algorithm (DHPA1NC) is proposed. DHPAINC taboos the inner regions of the class domain, thus, the antibody generation is limited near the class domain boundary. Then, the antibodies are evaluated by their recognition abilities, and the antibodies of low recognition abilities are removed to avoid over-fitting. Finally, the high quality antibodies tend to be stable in the immune network. The algorithm was applied to two simulated datasets classification, and the results show that the decision hyper planes determined by the antibodies fit the class domain boundaries well. Moreover, the algorithm was applied to UCI datasets classification and emotional speech recognition, and the results show that the algorithm has good performance, which means that DHPAINC is a promising classifier.
基金National Natural Science Foundation of China(No.11604304)High School Science and Technology Innovation Project of Shanxi ProvinceApplied Basic Research Project of Shanxi Province(Nos.201701D221127,201801D121160)
文摘In order to estimate and detect the surface defect depth of metals, the transmission method of laser ultrasonic surface waves is used in this work. The laser ultrasonic detection platform taking use of thermoelastic mechanism as acoustic signal excitation method and interference receiver as acoustic signal receiver method was built, by which B-scan images of detected specimens with surface defects were collected to establish the relationship between the transmission coefficient and depth of the surface defect. Experimental results show that the amplitude of transmitted acoustic signal is related to the depth of surface defect. At last, a fitted curve of transmission coefficient using measured experimental data is obtained to estimate depth of surface defect on the 6061 aluminum alloy. Furthermore, a surface defect depth of 0.3 mm is estimated by the fitting curve with an estimated error of 16%. Therefore, a experimental method using the transmission method by laser ultrasonic is presented in this paper.
基金Supported by State Key Laboratory of Urban Water Resource and Environment(2016DX01)the Fundamental Research Funds for the Central University(NSRIF.2014096)Science and Technology Planning Project of Chancheng District(2013A1044)
文摘A numerical model was established to predict and optimise the chemical cleaning process of Polyvinylidene Fluo- ride (PVDF) Ultrafiltration (UF) membranes with the results from the experiment that applied the Response Sur- face Method (RSM) and Central Composite Design (CCD). The factors considered in the experimental design were sodium hydroxide (NaOH) concentration, sodium bypochlorite concentration (NaCIO), citric acid concentration and cleaning duration, The interactions between the factors were investigated with the numerical model. Humic acid (20 mg· L-1) was used as the model foulant, and chemical enhanced backflush (CEB) was employed to sim- ulate the chemical cleaning process. The concentrations of sodium hydroxide, sodium hypochlorite, citric acid and cleaning duration tested during the experiments were in the range of 0.1%-0.3% 100-300 mg· L-1 1%-3% and 0.5-1.5 h, respectively. Among the variables, the sodium hypochlorite concentration and the cleaning dura- tion showed a positive relationship involving the increased efficiency of the chemical cleaning. The chemical cleaning efficiency was hardly improved with increasing concentrations of sodium hydroxide. However, the data was sharply decreased when at a low level of sodium hydroxide concentration. In total, 54 sets of cleaning schemes with 80% to 100K cleaning efficiency were observed with the R&M model after calibration.
基金Project(2013BAB02B05)supported by National Science and Technology Support Program of ChinaProject(2013JSJJ029)supported by the Teacher Fund of Central South University,ChinaProjects(51074177,41372278)supported by the National Natural Science Foundation of China
文摘Due to the influence of joint fissure, mining intensity, designed slope angle, underground water and rainfall, the failure process of mine slope project is extremely complicated. The current safety factor calculation method has certain limitations, and it would be difficult to obtain the reliability index when the performance function of reliability analysis is implicit or has high order terms. Therefore, with the help of the logistic equation of chaos theory, a new algorithm of mine slope reliability based on limiting state hyper-plane is proposed. It is shown that by using this new reliability algorithm the calculation of partial derivative of performance function is avoided, and it has the advantages of being simple and easy to program. The new algorithm is suitable for calculating the reliability index of complex performance function containing high order terms. Furthermore, the limiting state hyper-plane models of both simplified Bishop's and Janbu's method adaptive to slope project are obtained, and have achieved satisfactory effect in the study of mine slope stability in Dexing copper open pit.
文摘Jatropha curcas L. (JCL) seeds were extracted and transesterified in-situ using supercritical methanol extraction in the absence of catalyst at different temperatures (200-280℃) and pressures (8-12 MPa), and at a fixed reaction time of 30 min with seeds-to-methanol ratio of 1:40 w/v. Design of experiment approach using five-level-two-factors design of Response Surface Methodology (RSM) was used to observe the effect of two independent variables i.e. temperature and pressure and the percent of biodiesel yield which required 13 runs. For optimization of the variables, Central Composite Rotatable Design (CCRD) was used for regression analysis and analysis of variance (ANOVA). The optimize conditions suggested by RSM were at T = 280℃ and P = 12.04 MPa. The predicted and experimental biodicsel yields were found to be 56.8% and 59.9%, respectively, with relatively small deviation errors of 1.59%.
文摘Multi-level inverters(MLIs)have become popular in different applications such as industrial power control systems and distributed generations.There are different forms of MLIs.The cascaded MLIs(CMLIs)have some special advantages among them such as more different output voltage levels using the same number of components and higher power quality.In this paper,a 27-level inverter switching algorithm considering total harmonic distortion(THD)minimization is investigated.Switching angles of the inverter switches are achieved by minimizing a THD-based objective function.In order to minimize the THD-based objective function,the hyper-spherical search(HSS)algorithm,as a novel optimization algorithm,is improved and the results of improved HSS(IHSS)are compared with HSS algorithm and other five evolutionary algorithms to show the advantages of IHSS algorithm.
文摘A new heuristic algorithm is proposed for solving general integer linear programming problems. In the algorithm, the objective function hyperplane is used as a cutting plane, and then by introducing a special set of assistant sets, an efficient heuristic search for the solution to the integer linear program is carried out in the sets on the objective function hyperplane. A simple numerical example shows that the algorithm is efficient for some problems, and therefore, of practical interest.
基金Projects(51275235, 50975135) supported by the National Natural Science Foundation of ChinaProject(U0934004) supported by the Natural Science Foundation of Guangdong Province, ChinaProject(2011CB707602) supported by the National Basic Research Program of China
文摘A new method for optimizing a butterfly-shaped linear ultrasonic motor was proposed to maximize its mechanical output. The finite element analysis technology and response surface methodology were combined together to realize the optimal design of the butterfly-shaped linear ultrasonic motor. First, the operation principle of the motor was introduced. Second, the finite element parameterized model of the stator of the motor was built using ANSYS parametric design language and some structure parameters of the stator were selected as design variables. Third, the sample points were selected in design variable space using latin hypercube Design. Through modal analysis and harmonic response analysis of the stator based on these sample points, the target responses were obtained. These sample points and response values were combined together to build a response surface model. Finally, the simplex method was used to find the optimal solution. The experimental results showed that many aspects of the design requirements of the butterfly-shaped linear ultrasonic motor have been fulfilled. The prototype motor fabricated based on the optimal design result exhibited considerably high dynamic performance, such as no-load speed of 873 ram/s, maximal thrust of 27.5 N, maximal efficiency of 43%, and thrust-weight ratio of 45.8.
文摘The aim of the present study was to optimize the supercritical CO_2 extraction conditions of icariin from Herba Epimedii by response surface method(RSM) and central composite design(CCD).A 3-factor,5-level CCD was used for the optimization.Independent variables were extraction temperature,extraction pressure and entrainer flow rate.Dependent variable was yield ratio of icariin from Herba Epimedii.A two-order polynomial equation was fitted to the data.The results showed that the optimum extraction conditions were as follows:extraction temperature 46.5℃,extraction pressure 30.6 MPa,entrainer flow rate 3.3 mL/min.CCD/ RSM is convenient and highly predictive for optimizing the extraction process of icariin from Herba Epimedii.
基金Suzhou Youth science and technology plan(Grant No.KJXW2015028)
文摘Cimicifugae Rhizome (RC) is one of many commonly used traditional Chinese medicines. This study used Box-Behnken Design (BBD), a widely used form of response surface methodology (RSM), to optimize the conditions of the ultrasound-assisted extraction (UAE) for the extraction of phenolic compounds from CimicifugaeRhizome. The influence of three independent variables, including ethanol concentration (%), extraction time (min) and solvent-to-material ratio (mL/g), on the extraction yields of phenolic compounds were examined. The results demonstrated that the optimal ultrasound-assisted extraction (UAE) conditions were as follows: ethanol concentration of 68%, an extraction time of 19 min, and solvent-to-material ratio of 30 mL/g for the extraction of caffeic acid, cimicifugoside, ferulic acid, isoferulicacid, cimifugin, 4′-O-β-glucopyranosyl-5-O-methylvisamminol. These results demonstrated the suitability of UAE for the extraction of phenolic compounds from CimicifugaeRhizome.
基金supported by the Start-up Funding from Xi’an Jiaotong Universitythe Fundamental Research Funds for the Central Universities (2015qngz12)+1 种基金the National Natural Science Foundation of China (21371140)the China National Funds for Excellent Young Scientists (21522106)
文摘Over the past decade, ultrathin lanthanide oxides (Ln2O3, Ln = La to Lu) nanomaterials have been intensively studied in the fields of rare earth materials science. This unique class of nanomaterials has shown many unprecedented properties (big surface area, high surface effect, physical and chemical activities) and is thus being explored for numerous promising applications. In this review, a brief introduction of ultrathin Ln2O3 nanomaterials was given and their unique advantages were highlighted. Then, the typical synthetic methodologies were summarized and compared (thermal decomposition, solvothermal, soft template, co-precipition and microwave etc.). Due to the high surface effect, some promising applications of ultmthin Ln203 nanomaterials, such as drug delivery and catalysis of CO oxidation, were reviewed. Finally, on the basis of current achievements on ultrathin Ln203 nanomaterials, personal perspectives and challenges on future research directions were proposed.
基金supported by the National Natural Science Foundation of China(No.11271302)Chongqing Natural Science Foundation(No.cstc2011jj A00026)
文摘kinematic Euclidean By using the moving frame method, the authors obtain a kind of asymmetric formulas for the total mean curvatures of hypersurfaces in the n-dimensional space