The billets of AM60 alloy, prepared with self-inoculation method, were partially remelted into semisolid state. Effects of process parameters on remelting microstructure of semisolid billet were investigated. Experime...The billets of AM60 alloy, prepared with self-inoculation method, were partially remelted into semisolid state. Effects of process parameters on remelting microstructure of semisolid billet were investigated. Experimental results show that the solid particles obtained with self-inoculation method are in smaller grain size and globular shape after partial remelting, compared with those prepared with other casting methods. In the optimized process conditions, the average size of solid particles of partially remelted billet is 65 μm, and the shape factor is 1.12. The process parameters, i.e. pouting temperature, addition amount of self-inoculants, and the slope angle of multi-stream mixing cooling chalmel have influence on the microstructure of partially remelted billet. The optimized temperature is from 680 ℃ to 700 ℃, addition amount of self-inoculants is between 5% and 7% (mass fraction), slope angle of multi-stream mixing cooling channel is between 30° and 45°, with which the dendritic microstructure of as-cast billet can be avoided, and the size of solid particles ofremelted billet is reduced.展开更多
The ascidian Ciona intestinalis is a model organism of developmental and evolutionary biology and may provide orucial clues concerning two fundamental matters, namely, how chordates originated from the putative deuter...The ascidian Ciona intestinalis is a model organism of developmental and evolutionary biology and may provide orucial clues concerning two fundamental matters, namely, how chordates originated from the putative deuterostome ancestor and how advanced chordates originated from the simplest chordates. In this paper, a whole-life-span culture of C. intestinalis was conducted. Fed with the diet combination of dry Spirulina, egg yolk, Dicrateria sp., edible yeast and weaning diet for shrimp, C. intestinalis grew up to average 59 mm and matured after 60 d cultivation. This culture process could be repeated using the artificially cultured mature ascidians as material. When the fertilized eggs were maintained under 10, 15, 20, 25 ℃, they hatched within 30 h, 22 h, 16 h and 12 h 50 min respectively experiencing cleavage, blastulation, gastrulation, neurulation, tailbud stage and tadpole stage, The tadpole larvae were characterized as typical but simplified chordates because of their dorsal nerve cord, notochord and primordial brain. After 8-24 h freely swimming, the tadpole larvae settled on the substrates and metamorphosized within 1-2 d into filter feeding sessile juvenile ascidians. In addition, unfertilized eggs were successfully dechorionated in filtered seawater containing 1% Tripsin, 0.25% EDTA at pH of 10.5 within 40 min. After fertilization, the dechorionated eggs developed well and hatched at normal hatching rate. In conclusion, this paper presented feasible methodology for rearing the tadpole larvae of C. intestinalis into sexual maturity under controlled conditions and detailed observations on the embryogenesis of the laboratory cultured ascidians, which will facilitate developmental and genetic research using this model system.展开更多
Phase equilibrium conditions of gas hydrate in several systems were measured by the step-heating method using the cylindrical transparent sapphire cell device.The experimental data for pure CH4 or CO2+deionized water ...Phase equilibrium conditions of gas hydrate in several systems were measured by the step-heating method using the cylindrical transparent sapphire cell device.The experimental data for pure CH4 or CO2+deionized water systems showed good agreement with those in the literatures.This kind of method was then applied to CH4/CO2+sodium dodecyl sulfate(SDS)aqueous solution,CH4/CO2+SDS aqueous solution+silica sand,and(CH4+C2H6+C3H8)gas mixture+SDS aqueous solution systems,where SDS was added to increase the hydrate formation rate without evident influence on the equilibrium conditions.The feasibility and reliability of the step-heating method,especially for porous media systems and gas mixtures systems were determined.The experimental data for CO2+silica sand data shows that the equilibrium pressure will change significantly when the particle size of silica sand is less than 96μm.The formation equilibrium pressure was also measured by the reformation of hydrate.展开更多
This article examines the legal impediments to proper cultural heritage management in Ethiopia in light of three successive Ethiopian governments’ proclamations on cultural heritage conservation. It provides a brief...This article examines the legal impediments to proper cultural heritage management in Ethiopia in light of three successive Ethiopian governments’ proclamations on cultural heritage conservation. It provides a brief overview of the meaning and types of cultural heritages as well as the evolution of the concept and practice of the protection and preservation of cultural heritages. Having critically analyzed the basic essences of the legal provisions of the cultural heritage conservation proclamations of the Imperial, the Military (Derg), and the reigning governments, the article argues that the decrees issued mainly reflect the political philosophy of the three respective regimes. As a result, the second legal provision is not better than the first one, and within the same logic, the third is more expected to mitigate the problems related to cultural heritage management than the second one. Nevertheless, it is an open secret that the destruction and loss of cultural heritages in Ethiopia are increasing from time to time. Finally, the article provides conclusions consisting of recommendations to address the legal impediments to proper cultural heritage management in Ethiopia.展开更多
Three industrial spent S Zorb sorbents extracted from production line were studied with XRD, TPR-MS and XPS. The characterization results of XPS and TPR-MS identified the existence of amorphous Ni_xS_y on industrial s...Three industrial spent S Zorb sorbents extracted from production line were studied with XRD, TPR-MS and XPS. The characterization results of XPS and TPR-MS identified the existence of amorphous Ni_xS_y on industrial spent S Zorb sorbents, while the existing XRD quantitative analysis methods can only provide the long-range order in phase information and the grain size of Ni metal. XPS is a powerful tool to investigate the chemical states of nickel atom and the depthwise distribution of nickel species on S Zorb sorbent. Ni_xS_y and Ni metal species coexist on the industrial spent sorbents, and their percentages to total nickel slightly change with the operating conditions in the surface layer. It proves that Ni_xS_y is a stable intermediate product rather than a transition state. The information can contribute to the better elucidation of S Zorb desulfurization mechanism and offer a new direction for selectivity optimization of industrial S Zorb sorbents.展开更多
Kjellander has reported an algorithm for fairing uniform parametric cubic splines. Poliakoff extended Kjellander’s algorithm to non-uniform case. However, they merely changed the bad point’s position, and neglected ...Kjellander has reported an algorithm for fairing uniform parametric cubic splines. Poliakoff extended Kjellander’s algorithm to non-uniform case. However, they merely changed the bad point’s position, and neglected the smoothing of tangent at bad point. In this paper, we present a fairing algorithm that both changed point’s position and its corresponding tangent vector. The new algorithm possesses the minimum property of energy. We also proved Poliakoff’s fairing algorithm is a deduction of our fairing algorithm. Several fairing examples are given in this paper.展开更多
The objective of this work is using the online measurement method to study the process of precipitation of nickel hydroxide in a single-feed semi-batch stirred reactor with an internal diameter ofD = 240mm. The effect...The objective of this work is using the online measurement method to study the process of precipitation of nickel hydroxide in a single-feed semi-batch stirred reactor with an internal diameter ofD = 240mm. The effects of impeller speed, impeller type, impeller diameter and feed location on the mean particle size d43 and particle size distribution (PSD) were investigated, d43 and PSD were measured online using a Malvern Insitec Liquid Pro- cess Sizer every 20 s. It was found that d43 varied between 13 kwh and 26 lain under different operating conditions, and it decreased with increasing impeller diameter. When feeding at the off-bottom distance of D/2 under lower impeller speeds, d43 was significantly smaller than that at D/3. PSDs were slightly influenced by operating conditions.展开更多
High enzymatic activity is required for laccase applications.Central composite design (CCD)-based response surface methodology (RSM) can effectively increase the enzymatic activity of Pleurotus ostreatus P40 in li...High enzymatic activity is required for laccase applications.Central composite design (CCD)-based response surface methodology (RSM) can effectively increase the enzymatic activity of Pleurotus ostreatus P40 in liquid substrate fermentation.Initial screening of the nutritional components was performed using a Plackett-Burman design.The variables,namely,bran,bagasse,Tween 80,and yeast extract,were found to have statistically significant effects on laccase activity.These variables were further optimized using CCD-based RSM.Optimal concentrations for the maximum laccase activity were 8.144 2 g/L bran,50 g/L bagasse,0.424 1 mL/L Tween 80,and 2.832 5 g/L yeast extract.Under optimized conditions,the maximum measured laccase activity reached 96 480 U/L,which was close to the predicted value (104 830 U/L) by RSM.Therefore,RSM can be used to optimize culture components for laccase activity from Pieurotus ostreatus P40.展开更多
The culture of Magnetospirillum magneticum WM-1 depends on several control factors that have great effect on the magnetic cells concentration. Investigation into the optimal culture conditions needs a large number of ...The culture of Magnetospirillum magneticum WM-1 depends on several control factors that have great effect on the magnetic cells concentration. Investigation into the optimal culture conditions needs a large number of experiments So it is desirable to minimize the number of experiments and maximize the information gained from them. The orthogonal design of experiments and mathematical statistical method are considered as effective methods to optimize the culture condition of magnetotactic bacteria WMol for high magnetic cells concentration. The effects of the four factors, such as pH value of medium, oxygen concentration of gas phase in the serum bottle, C:C (mtartaric acid: m=succinic acid) ratio and NaNO3 concentration, are simultaneously investigated by only sixteen experiments through the orthogonal design L16(44) method. The optimal culture condition is obtained. At the optimal culture condition ( pH 7.0, an oxygen concentration 4.0%, C:C (mtartaric acid: m=succinic acid) ratio 1:2 and NaNO3 100 mg 1^-1), the magnetic cells concentration is promoted tO 6.5×10^7 cells ml^-1, approximately 8.3% higher than that under the initial conditions. The pH value of medium is a very important factor for magnetic cells concentration. It can be Proved that the orthogonal design of experiment is of 90% confidence. Ferric iron uptake follows MichaelisoMenten kinetics with a Km of 2.5 pM and a Vmax of 0.83 min^-1.展开更多
Harmful algal blooms(HABs) have led to extensive ecological and environmental issues and huge economic losses.Various HAB control techniques have been developed,and biological methods have been paid more attention.Alg...Harmful algal blooms(HABs) have led to extensive ecological and environmental issues and huge economic losses.Various HAB control techniques have been developed,and biological methods have been paid more attention.Algicidal bacteria is a general designation for bacteria which inhibit algal growth in a direct or indirect manner,and kill or damage the algal cells.A metabolite which is strongly toxic to the dinoflagellate Alexandrium tamarense was produced by strain DH46 of the alga-lysing bacterium Alteromonas sp.The culture conditions were optimized using a single-factor test method.Factors including carbon source,nitrogen source,temperature,initial pH value,rotational speed and salinity were studied.The results showed that the cultivation of the bacteria at 28℃ and 180 r min-1with initial pH 7 and 30 salt contcentration favored both the cell growth and the lysing effect of strain DH46.The optimal medium composition for strain DH46 was determined by means of uniform design experimentation,and the most important components influencing the cell density were tryptone,yeast extract,soluble starch,NaNO3 and MgSO4.When the following culture medium was used(tryptone 14.0g,yeast extract 1.63g,soluble starch 5.0 g,NaNO3 1.6 g,MgSO4 2.3 g in 1L),the largest bacterial dry weight(7.36 g L-1) was obtained,which was an enhancement of 107% compared to the initial medium;and the algal lysis rate was as high as 98.4% which increased nearly 10% after optimization.展开更多
The use of electro-osmotic chemical is an effective method to improve the clayey soil foundation.Various boundary conditions can be adopted in this method.In this work,two electrode–clay contacts,three solution condi...The use of electro-osmotic chemical is an effective method to improve the clayey soil foundation.Various boundary conditions can be adopted in this method.In this work,two electrode–clay contacts,three solution conditioners,and four anode solution supply times were used for clayey soil improvement.Based on the experimental data,electro-osmotic consolidation theory,and transport of ion theory,it is found that the electro-osmotic chemical effect of the separation of electrode–clay(E_S)is more beneficial for the transport of Ca^(2+),production of cementing material,and reduction of water content than that of electrode–clay(E_C)joining;through electrode–clay contact separation,the anode solution conditioner(NaPO3)6(E_SHMP)delayed the cementing reaction and then increased the transport of Ca^(2+)near the cathode,which increased the amount of cementing material and the electro-osmotic chemical effect;and when the anode conditioner(NaPO3)6 was used,two days of anode solution supply followed by three days cut off from the anode solution led to the highest undrained shear strength increase after the application of electro-osmotic chemical,which resolved the uneven electro-osmotic chemical effect in the E_SHMP.展开更多
In order to improve the production of human-like collagen III(HLC III)by fed-batch culture of recombinant Escherichia coli BL21,the Plackett-Burman and Box-Behnken design were applied to optimize the fermentation proc...In order to improve the production of human-like collagen III(HLC III)by fed-batch culture of recombinant Escherichia coli BL21,the Plackett-Burman and Box-Behnken design were applied to optimize the fermentation process parameters.Three variables(induction time,inoculum age and pH),which have significant effects on HLC III production,were selected from eight variables by Plackett-Burman design.With the regression coefficient analysis in the Box-Behnken design,a relationship between HLC III production and three significant factors was obtained,and the optimum levels of the three variables were as follows:induction time 3.2h,inoculum age 12.6 h and pH 6.7.The 3D response surface plots and 2D contour plots created by the Box-Behnken design showed that the interaction between induction time and pH and that between innoculum age and pH were significant.An average 9.68 g·L1HLC III production was attained in the validation experiment under optimized condition,which was 80%higher than the yield of 5.36 g·L1before optimization.展开更多
Microcapsules of volatile oil containing Herba Schizonepetae(VOHS) were prepared by emulsion solvent diffusion method to improve the drug loading and reduce the amount of pharmaceutical excipients.Orthogonal assay was...Microcapsules of volatile oil containing Herba Schizonepetae(VOHS) were prepared by emulsion solvent diffusion method to improve the drug loading and reduce the amount of pharmaceutical excipients.Orthogonal assay was applied to optimize the preparation condition of microcapsulation,and the results illustrated that the ratio of ethyl cellulose(EC) to VOHS influenced the property of VOHS microcapsule significantly.GC-MS analysis indicated that some volatile components with low concentration in VOHS were lost after microencapsulation.The microcapsules prepared with optimum condition had good fluidity,and the holes on the surface of the microcapsules contributed to the release of VOHS.The particles of the microcapsule conformed to a normal distribution with the diameter of 45—220 μm.In the simulated intestinal fluid containing 0.2% sodium dodecyl sulfate,pulegone in VOHS microcapsule showed a certain degree of slow release.Compared with β-cyclodextrin method,the microencapsulation used in the present work could reduce the amount of excipients and increase the drug loading.It was beneficial to reduce the dose of Chinese medicines containing volatile oils.展开更多
The reverse time migration(RTM)of ground penetrating radar(GPR)is usually implemented in its two-dimensional(2D)form,due to huge computational cost.However,2D RTM algorithm is difficult to focus the scattering signal ...The reverse time migration(RTM)of ground penetrating radar(GPR)is usually implemented in its two-dimensional(2D)form,due to huge computational cost.However,2D RTM algorithm is difficult to focus the scattering signal and produce a high precision subsurface image when the object is buried in a complicated subsurface environment.To better handle the multi-off set GPR data,we propose a three-dimensional(3D)prestack RTM algorithm.The high-order fi nite diff erence time domian(FDTD)method,with the accuracy of eighth-order in space and second-order in time,is applied to simulate the forward and backward extrapolation electromagnetic fi elds.In addition,we use the normalized correlation imaging condition to obtain pre-stack RTM result and the Laplace fi lter to suppress the low frequency noise generated during the correlation process.The numerical test of 3D simulated GPR data demonstrated that 3D RTM image shows excellent coincidence with the true model.Compared with 2D RTM image,the 3D RTM image can more clearly and accurately refl ect the 3D spatial distribution of the target,and the resolution of the imaging results is far better.Furthermore,the application of observed GPR data further validates the eff ectiveness of the proposed 3D GPR RTM algorithm,and its fi nal image can more reliably guide the subsequent interpretation.展开更多
The present paper deals with a multiobjective optimization of truss topology by either Sequential Linear Programming (SLP) method or Linear Programming (LP) method. The ground structure approach is often used to s...The present paper deals with a multiobjective optimization of truss topology by either Sequential Linear Programming (SLP) method or Linear Programming (LP) method. The ground structure approach is often used to solve this kind of design problems. In this paper, the topology optimization is formulated as a Multiobjective Optimization Problem (MOP), which is to find the cross-sectional area of truss members, such that both the total volume of members and the weighted mean compliance are minimized. Based upon the Karush-Kuhn-Tucker conditions (the optimality condition), the Pareto optimal front of this problem can be obtained theoretically. The truss topology optimization under multiple load cases can be solved by the SLP. On the other hand, the LP such as the Simplex method or the interior point method can be applied to find one of the Pareto optimal solutions of the MOP under single load case. The applications of either the SLP or the LP are illustrated in numerical examples with discussion on characteristics of design results.展开更多
Tube furnaces are essential and primary energy intensive facilities in petrochemical plants. Operational optimization of furnaces could not only help to improve product quality but also benefit to reduce energy consum...Tube furnaces are essential and primary energy intensive facilities in petrochemical plants. Operational optimization of furnaces could not only help to improve product quality but also benefit to reduce energy consumption and exhaust emission. Inspired by this idea, this paper presents a composite model predictive control(CMPC)strategy, which, taking advantage of distributed model predictive control architectures, combines tracking nonlinear model predictive control and economic nonlinear model predictive control metrics to keep process running smoothly and optimize operational conditions. The controllers connected with two kinds of communication networks are easy to organize and maintain, and stable to process interferences. A fast solution algorithm combining interior point solvers and Newton's method is accommodated to the CMPC realization, with reasonable CPU computing time and suitable online applications. Simulation for industrial case demonstrates that the proposed approach can ensure stable operations of furnaces, improve heat efficiency, and reduce the emission effectively.展开更多
基金Project(2007CB613700) supported by the National Basic Research Program of ChinaProject(50964010) supported by the National Natural Science Foundation of ChinaProject(090WCGA894) supported by the International S&T Cooperation Program of Gansu Province,China
文摘The billets of AM60 alloy, prepared with self-inoculation method, were partially remelted into semisolid state. Effects of process parameters on remelting microstructure of semisolid billet were investigated. Experimental results show that the solid particles obtained with self-inoculation method are in smaller grain size and globular shape after partial remelting, compared with those prepared with other casting methods. In the optimized process conditions, the average size of solid particles of partially remelted billet is 65 μm, and the shape factor is 1.12. The process parameters, i.e. pouting temperature, addition amount of self-inoculants, and the slope angle of multi-stream mixing cooling chalmel have influence on the microstructure of partially remelted billet. The optimized temperature is from 680 ℃ to 700 ℃, addition amount of self-inoculants is between 5% and 7% (mass fraction), slope angle of multi-stream mixing cooling channel is between 30° and 45°, with which the dendritic microstructure of as-cast billet can be avoided, and the size of solid particles ofremelted billet is reduced.
基金Project supported by the Hi-Tech Research and Development Pro-gram (863) of China (No. 2003AA603440) and the Knowledge In-novation Program from the Chinese Academy of Sciences (No.KZCX2-211)
文摘The ascidian Ciona intestinalis is a model organism of developmental and evolutionary biology and may provide orucial clues concerning two fundamental matters, namely, how chordates originated from the putative deuterostome ancestor and how advanced chordates originated from the simplest chordates. In this paper, a whole-life-span culture of C. intestinalis was conducted. Fed with the diet combination of dry Spirulina, egg yolk, Dicrateria sp., edible yeast and weaning diet for shrimp, C. intestinalis grew up to average 59 mm and matured after 60 d cultivation. This culture process could be repeated using the artificially cultured mature ascidians as material. When the fertilized eggs were maintained under 10, 15, 20, 25 ℃, they hatched within 30 h, 22 h, 16 h and 12 h 50 min respectively experiencing cleavage, blastulation, gastrulation, neurulation, tailbud stage and tadpole stage, The tadpole larvae were characterized as typical but simplified chordates because of their dorsal nerve cord, notochord and primordial brain. After 8-24 h freely swimming, the tadpole larvae settled on the substrates and metamorphosized within 1-2 d into filter feeding sessile juvenile ascidians. In addition, unfertilized eggs were successfully dechorionated in filtered seawater containing 1% Tripsin, 0.25% EDTA at pH of 10.5 within 40 min. After fertilization, the dechorionated eggs developed well and hatched at normal hatching rate. In conclusion, this paper presented feasible methodology for rearing the tadpole larvae of C. intestinalis into sexual maturity under controlled conditions and detailed observations on the embryogenesis of the laboratory cultured ascidians, which will facilitate developmental and genetic research using this model system.
基金Supported by the National Natural Science Foundation of China (20676145, U0633003), the National Basic Research Program of China (2009CB219504) and the Program for New Century Excellent Talents in University of the State Ministry of Education.
文摘Phase equilibrium conditions of gas hydrate in several systems were measured by the step-heating method using the cylindrical transparent sapphire cell device.The experimental data for pure CH4 or CO2+deionized water systems showed good agreement with those in the literatures.This kind of method was then applied to CH4/CO2+sodium dodecyl sulfate(SDS)aqueous solution,CH4/CO2+SDS aqueous solution+silica sand,and(CH4+C2H6+C3H8)gas mixture+SDS aqueous solution systems,where SDS was added to increase the hydrate formation rate without evident influence on the equilibrium conditions.The feasibility and reliability of the step-heating method,especially for porous media systems and gas mixtures systems were determined.The experimental data for CO2+silica sand data shows that the equilibrium pressure will change significantly when the particle size of silica sand is less than 96μm.The formation equilibrium pressure was also measured by the reformation of hydrate.
文摘This article examines the legal impediments to proper cultural heritage management in Ethiopia in light of three successive Ethiopian governments’ proclamations on cultural heritage conservation. It provides a brief overview of the meaning and types of cultural heritages as well as the evolution of the concept and practice of the protection and preservation of cultural heritages. Having critically analyzed the basic essences of the legal provisions of the cultural heritage conservation proclamations of the Imperial, the Military (Derg), and the reigning governments, the article argues that the decrees issued mainly reflect the political philosophy of the three respective regimes. As a result, the second legal provision is not better than the first one, and within the same logic, the third is more expected to mitigate the problems related to cultural heritage management than the second one. Nevertheless, it is an open secret that the destruction and loss of cultural heritages in Ethiopia are increasing from time to time. Finally, the article provides conclusions consisting of recommendations to address the legal impediments to proper cultural heritage management in Ethiopia.
基金the funding of the project by SINOPEC(No.114138)
文摘Three industrial spent S Zorb sorbents extracted from production line were studied with XRD, TPR-MS and XPS. The characterization results of XPS and TPR-MS identified the existence of amorphous Ni_xS_y on industrial spent S Zorb sorbents, while the existing XRD quantitative analysis methods can only provide the long-range order in phase information and the grain size of Ni metal. XPS is a powerful tool to investigate the chemical states of nickel atom and the depthwise distribution of nickel species on S Zorb sorbent. Ni_xS_y and Ni metal species coexist on the industrial spent sorbents, and their percentages to total nickel slightly change with the operating conditions in the surface layer. It proves that Ni_xS_y is a stable intermediate product rather than a transition state. The information can contribute to the better elucidation of S Zorb desulfurization mechanism and offer a new direction for selectivity optimization of industrial S Zorb sorbents.
基金Project (No. 10371026) supported by the National Natural Science Foundation of China
文摘Kjellander has reported an algorithm for fairing uniform parametric cubic splines. Poliakoff extended Kjellander’s algorithm to non-uniform case. However, they merely changed the bad point’s position, and neglected the smoothing of tangent at bad point. In this paper, we present a fairing algorithm that both changed point’s position and its corresponding tangent vector. The new algorithm possesses the minimum property of energy. We also proved Poliakoff’s fairing algorithm is a deduction of our fairing algorithm. Several fairing examples are given in this paper.
基金the State Key Development Program for Basic Research of China(2013CB632601)the National High Technology Research and Development Program of China(2011AA060704)+1 种基金the National Natural Science Foundation of China(21476236,91434126)the National Science Fund for Distinguished Young Scholars(21025627)
文摘The objective of this work is using the online measurement method to study the process of precipitation of nickel hydroxide in a single-feed semi-batch stirred reactor with an internal diameter ofD = 240mm. The effects of impeller speed, impeller type, impeller diameter and feed location on the mean particle size d43 and particle size distribution (PSD) were investigated, d43 and PSD were measured online using a Malvern Insitec Liquid Pro- cess Sizer every 20 s. It was found that d43 varied between 13 kwh and 26 lain under different operating conditions, and it decreased with increasing impeller diameter. When feeding at the off-bottom distance of D/2 under lower impeller speeds, d43 was significantly smaller than that at D/3. PSDs were slightly influenced by operating conditions.
基金National Science&Technology Pillar Program of China(No.2012BAC02B04)National Natural Science Foundation of China(No.41201306)
文摘High enzymatic activity is required for laccase applications.Central composite design (CCD)-based response surface methodology (RSM) can effectively increase the enzymatic activity of Pleurotus ostreatus P40 in liquid substrate fermentation.Initial screening of the nutritional components was performed using a Plackett-Burman design.The variables,namely,bran,bagasse,Tween 80,and yeast extract,were found to have statistically significant effects on laccase activity.These variables were further optimized using CCD-based RSM.Optimal concentrations for the maximum laccase activity were 8.144 2 g/L bran,50 g/L bagasse,0.424 1 mL/L Tween 80,and 2.832 5 g/L yeast extract.Under optimized conditions,the maximum measured laccase activity reached 96 480 U/L,which was close to the predicted value (104 830 U/L) by RSM.Therefore,RSM can be used to optimize culture components for laccase activity from Pieurotus ostreatus P40.
文摘The culture of Magnetospirillum magneticum WM-1 depends on several control factors that have great effect on the magnetic cells concentration. Investigation into the optimal culture conditions needs a large number of experiments So it is desirable to minimize the number of experiments and maximize the information gained from them. The orthogonal design of experiments and mathematical statistical method are considered as effective methods to optimize the culture condition of magnetotactic bacteria WMol for high magnetic cells concentration. The effects of the four factors, such as pH value of medium, oxygen concentration of gas phase in the serum bottle, C:C (mtartaric acid: m=succinic acid) ratio and NaNO3 concentration, are simultaneously investigated by only sixteen experiments through the orthogonal design L16(44) method. The optimal culture condition is obtained. At the optimal culture condition ( pH 7.0, an oxygen concentration 4.0%, C:C (mtartaric acid: m=succinic acid) ratio 1:2 and NaNO3 100 mg 1^-1), the magnetic cells concentration is promoted tO 6.5×10^7 cells ml^-1, approximately 8.3% higher than that under the initial conditions. The pH value of medium is a very important factor for magnetic cells concentration. It can be Proved that the orthogonal design of experiment is of 90% confidence. Ferric iron uptake follows MichaelisoMenten kinetics with a Km of 2.5 pM and a Vmax of 0.83 min^-1.
基金financially supported by the National Natural Science Foundation(40930847,31070442)the Natural Science Foundation of Fujian Province(2012J01150)Public science and technology research funds projects of ocean(201305016,201305041,201305022) and MELRI1003
文摘Harmful algal blooms(HABs) have led to extensive ecological and environmental issues and huge economic losses.Various HAB control techniques have been developed,and biological methods have been paid more attention.Algicidal bacteria is a general designation for bacteria which inhibit algal growth in a direct or indirect manner,and kill or damage the algal cells.A metabolite which is strongly toxic to the dinoflagellate Alexandrium tamarense was produced by strain DH46 of the alga-lysing bacterium Alteromonas sp.The culture conditions were optimized using a single-factor test method.Factors including carbon source,nitrogen source,temperature,initial pH value,rotational speed and salinity were studied.The results showed that the cultivation of the bacteria at 28℃ and 180 r min-1with initial pH 7 and 30 salt contcentration favored both the cell growth and the lysing effect of strain DH46.The optimal medium composition for strain DH46 was determined by means of uniform design experimentation,and the most important components influencing the cell density were tryptone,yeast extract,soluble starch,NaNO3 and MgSO4.When the following culture medium was used(tryptone 14.0g,yeast extract 1.63g,soluble starch 5.0 g,NaNO3 1.6 g,MgSO4 2.3 g in 1L),the largest bacterial dry weight(7.36 g L-1) was obtained,which was an enhancement of 107% compared to the initial medium;and the algal lysis rate was as high as 98.4% which increased nearly 10% after optimization.
基金Project(41902280)supported by the National Natural Science Foundation of ChinaProject(300102219105)supported by the Fundamental Research Funds for the Central Universities,China+1 种基金Project(LP1922)supported by the Open Foundation of State Key Laboratory of Coastal and Offshore Engineering,ChinaProject(XJKFJJ201805)supported by the Open Foundation of Shaanxi Key Laboratory of Safety and Durability of Concrete Structures,China。
文摘The use of electro-osmotic chemical is an effective method to improve the clayey soil foundation.Various boundary conditions can be adopted in this method.In this work,two electrode–clay contacts,three solution conditioners,and four anode solution supply times were used for clayey soil improvement.Based on the experimental data,electro-osmotic consolidation theory,and transport of ion theory,it is found that the electro-osmotic chemical effect of the separation of electrode–clay(E_S)is more beneficial for the transport of Ca^(2+),production of cementing material,and reduction of water content than that of electrode–clay(E_C)joining;through electrode–clay contact separation,the anode solution conditioner(NaPO3)6(E_SHMP)delayed the cementing reaction and then increased the transport of Ca^(2+)near the cathode,which increased the amount of cementing material and the electro-osmotic chemical effect;and when the anode conditioner(NaPO3)6 was used,two days of anode solution supply followed by three days cut off from the anode solution led to the highest undrained shear strength increase after the application of electro-osmotic chemical,which resolved the uneven electro-osmotic chemical effect in the E_SHMP.
基金Supported by the National Natural Science Foundation of China(20776119) the National High Technology Research and Development Program of China(2007AA03Z456A) the Special Research Program of the Education Department of Shaanxi Province(07JK417)
文摘In order to improve the production of human-like collagen III(HLC III)by fed-batch culture of recombinant Escherichia coli BL21,the Plackett-Burman and Box-Behnken design were applied to optimize the fermentation process parameters.Three variables(induction time,inoculum age and pH),which have significant effects on HLC III production,were selected from eight variables by Plackett-Burman design.With the regression coefficient analysis in the Box-Behnken design,a relationship between HLC III production and three significant factors was obtained,and the optimum levels of the three variables were as follows:induction time 3.2h,inoculum age 12.6 h and pH 6.7.The 3D response surface plots and 2D contour plots created by the Box-Behnken design showed that the interaction between induction time and pH and that between innoculum age and pH were significant.An average 9.68 g·L1HLC III production was attained in the validation experiment under optimized condition,which was 80%higher than the yield of 5.36 g·L1before optimization.
基金Supported by the Plan Issue of Shanghai Science&Technology Committee(No.13401901100)
文摘Microcapsules of volatile oil containing Herba Schizonepetae(VOHS) were prepared by emulsion solvent diffusion method to improve the drug loading and reduce the amount of pharmaceutical excipients.Orthogonal assay was applied to optimize the preparation condition of microcapsulation,and the results illustrated that the ratio of ethyl cellulose(EC) to VOHS influenced the property of VOHS microcapsule significantly.GC-MS analysis indicated that some volatile components with low concentration in VOHS were lost after microencapsulation.The microcapsules prepared with optimum condition had good fluidity,and the holes on the surface of the microcapsules contributed to the release of VOHS.The particles of the microcapsule conformed to a normal distribution with the diameter of 45—220 μm.In the simulated intestinal fluid containing 0.2% sodium dodecyl sulfate,pulegone in VOHS microcapsule showed a certain degree of slow release.Compared with β-cyclodextrin method,the microencapsulation used in the present work could reduce the amount of excipients and increase the drug loading.It was beneficial to reduce the dose of Chinese medicines containing volatile oils.
基金This work is supported by the National Natural Science Foundation of China(No.41604039,41604102,41764005,41574078)Guangxi Natural Science Foundation project(No.2020GXNSFAA159121,2016GXNSFBA380215).
文摘The reverse time migration(RTM)of ground penetrating radar(GPR)is usually implemented in its two-dimensional(2D)form,due to huge computational cost.However,2D RTM algorithm is difficult to focus the scattering signal and produce a high precision subsurface image when the object is buried in a complicated subsurface environment.To better handle the multi-off set GPR data,we propose a three-dimensional(3D)prestack RTM algorithm.The high-order fi nite diff erence time domian(FDTD)method,with the accuracy of eighth-order in space and second-order in time,is applied to simulate the forward and backward extrapolation electromagnetic fi elds.In addition,we use the normalized correlation imaging condition to obtain pre-stack RTM result and the Laplace fi lter to suppress the low frequency noise generated during the correlation process.The numerical test of 3D simulated GPR data demonstrated that 3D RTM image shows excellent coincidence with the true model.Compared with 2D RTM image,the 3D RTM image can more clearly and accurately refl ect the 3D spatial distribution of the target,and the resolution of the imaging results is far better.Furthermore,the application of observed GPR data further validates the eff ectiveness of the proposed 3D GPR RTM algorithm,and its fi nal image can more reliably guide the subsequent interpretation.
文摘The present paper deals with a multiobjective optimization of truss topology by either Sequential Linear Programming (SLP) method or Linear Programming (LP) method. The ground structure approach is often used to solve this kind of design problems. In this paper, the topology optimization is formulated as a Multiobjective Optimization Problem (MOP), which is to find the cross-sectional area of truss members, such that both the total volume of members and the weighted mean compliance are minimized. Based upon the Karush-Kuhn-Tucker conditions (the optimality condition), the Pareto optimal front of this problem can be obtained theoretically. The truss topology optimization under multiple load cases can be solved by the SLP. On the other hand, the LP such as the Simplex method or the interior point method can be applied to find one of the Pareto optimal solutions of the MOP under single load case. The applications of either the SLP or the LP are illustrated in numerical examples with discussion on characteristics of design results.
文摘Tube furnaces are essential and primary energy intensive facilities in petrochemical plants. Operational optimization of furnaces could not only help to improve product quality but also benefit to reduce energy consumption and exhaust emission. Inspired by this idea, this paper presents a composite model predictive control(CMPC)strategy, which, taking advantage of distributed model predictive control architectures, combines tracking nonlinear model predictive control and economic nonlinear model predictive control metrics to keep process running smoothly and optimize operational conditions. The controllers connected with two kinds of communication networks are easy to organize and maintain, and stable to process interferences. A fast solution algorithm combining interior point solvers and Newton's method is accommodated to the CMPC realization, with reasonable CPU computing time and suitable online applications. Simulation for industrial case demonstrates that the proposed approach can ensure stable operations of furnaces, improve heat efficiency, and reduce the emission effectively.