A self-made lipase preparation from Candida sp. 99-125 was used for the production of biodiesel through enzymatic esterification of fatty acids. The crude lipase powder and fermentation broth were immobilized on a che...A self-made lipase preparation from Candida sp. 99-125 was used for the production of biodiesel through enzymatic esterification of fatty acids. The crude lipase powder and fermentation broth were immobilized on a cheap fiber cloth carrier. The conditions of lipase-catalyzed esterification between long-chain fatty acids and methanol in a solvent system were investigated in detail, including the temperature, pH value, substrate concentration, solvent, absorbent agent, enzyme dosage and purity, immobilization method, the mode of addition of substrate. The results show that reaction temperature, pH of lipase micro-environment, substrate concentration, enzyme dosage and purity affect the esterification strongly. Several new methods and enzymatic procedures for improving the enzymatic reaction involving the process cost are also discussed, such as fossil diesel fuel as reaction solvent, immobilization method, multi-step gradient addition of methanol. The esterification degree of 92.8% was obtained with oleic acid and methanol under the optimal reaction condition after 12.5 h reaction time. The half-life of the immobilized lipase preparation from crude free lipase powder for esterification was 15 days.展开更多
As a combination of bio-mechanism and engineering technology, robot fish has become a multidisci- plinary research that mainly involves both hydrodynamics-based control and actuation technology. This paper presents a ...As a combination of bio-mechanism and engineering technology, robot fish has become a multidisci- plinary research that mainly involves both hydrodynamics-based control and actuation technology. This paper presents a simplified propulsive model for carangiform propulsion, which is a swimming mode suitable for high speed and high efficiency. The carangiform motion is modeled as an N-joint nscillating mechanism that is composed of two basic components： the streamlined fish body represented by a planar spline curve and its hmate caudal tail by an oscillating foil. The speed of fish＇s straight swimming is adjusted by modulating the joint＇s oscillating frequency, and its orientation is tuned by different joint＇s deflection. The results from actual experiment showed that the proposed simplified propulsive model could be a viable eandidate for application in aquatic： swimming vehicles.展开更多
Previously, researchers raised the accuracy for a robot′s hand to track a specified path in Car-tesian space mainly through increasing the number of knots on the path and the number of the path′s segments, which res...Previously, researchers raised the accuracy for a robot′s hand to track a specified path in Car-tesian space mainly through increasing the number of knots on the path and the number of the path′s segments, which results in the heavier online computational burden for the robot controller. Aiming at overcoming this drawback, the authors propose a new kind of real-time accurate hand path tracking and joint trajectory planning method. Through selecting some extra knots on the specified hand path by a certain rule and introducing a sinusoidal function to the joint displacement equation of each segment, this method can greatly raise the path tracking accuracy of robot′s hand and does not change the number of the path′s segments. It also does not increase markedly the computational burden of robot controller. The result of simulation indicates that this method is very effective, and has important value in increasing the application of industrial robots.展开更多
The floating oil storage system has been proposed as a new facility for Strategic Petroleum Reserve (SPR) in China. Mooring is one of the key technologies to ensure the safety, reliability, and performance of the oil ...The floating oil storage system has been proposed as a new facility for Strategic Petroleum Reserve (SPR) in China. Mooring is one of the key technologies to ensure the safety, reliability, and performance of the oil storage system. This paper describes the concept, analysis, design and reliability of the mooring system. For mooring system design of these oil vessels, analysis is essential of the behavior of the vessel in connection with mooring facilities of nonlinear resilience. A nonlinear mathematical model for analyzing a moored vessel is established and solved. Some results of numerical simulations are presented. Assessment of the safety regarding the mooring system in terms of failure probability is carried out. Another simulation model for calculating the failure probability of the mooring system is proposed. The design parameters that have an influence on the characteristics of the failure probability have been identified. The simulation results,show that the mooring system has an annual reliability value of 0.999998. The proposed simulation method is proved to be effective in quantitative evaluation of the safety of the mooring system for floating oil storage vessels.展开更多
Cubic boron nitride(c-BN) films were deposited on W6Mo5Cr4V2 high speed steel(HSS) substrate implanted with boron ion by RF-magnetron sputtering. The films were analyzed by the bending beam method, scratch test, XPS a...Cubic boron nitride(c-BN) films were deposited on W6Mo5Cr4V2 high speed steel(HSS) substrate implanted with boron ion by RF-magnetron sputtering. The films were analyzed by the bending beam method, scratch test, XPS and AFM. The experimental results show that the implantation of boron atom can reduce the internal stress and improve the adhesion strength of the films. The critical load of scratch test rises to 27.45 N, compared to 1.75 N of c-BN film on the unimplanted HSS. The AFM shows that the surface of the c-BN film on the implanted HSS is low in roughness and small in grain size. Then the composition of the boron implanted layer was analyzed by the XPS. And the influence of the boron implanted layer on the internal stress and adhesion strength of c-BN films were investigated.展开更多
Objective To oberve the change in blood glutathione peroxidase (GSH-Px) protein levels of residents in the low-selenium (Se) area by contrasting the blood GSH-Px protein level of the children in the Keshan disease are...Objective To oberve the change in blood glutathione peroxidase (GSH-Px) protein levels of residents in the low-selenium (Se) area by contrasting the blood GSH-Px protein level of the children in the Keshan disease area with those in the Kashin-Beck disease and non-endemic areas. Methods GSH-Px protein levels were measured by enzyme-linked immunosorbent assays (ELISA). The Se content and GSH-Px activity were assayed by the 2,3-diaminonaphthalene spectrofluorimetric method and glutathione reductase-coupled method respectively. Results ①The blood Se content and GSH-Px protein level of children in Keshan disease area (Moding) were significantly lower than those in Xi’an non-endemic area, however, there was no significant difference when compared with the low-Se non-endemic area; ②The blood Se content, GSH-Px activity and GSH-Px protein level of children in the Kashin-Beck disease area (Yulin) were significantly lower than those of children in two non-endemic areas and in the Keshan disease area; ③The blood Se content and GSH-Px activity were positively correlated to the GSH-Px protein level respectively. Conclusion These results indicate that the blood GSH-Px protein level is decreased in the low-Se residents. The Se status not only affects the GSH-Px activity but also regulate the GSH-Px protein level.展开更多
基金Supported by the National Natural Science Foundation of China (No. 20176020) and 863 Hi-Technology Research and Deve-lopment Program of China (No. 2002AA514030)
文摘A self-made lipase preparation from Candida sp. 99-125 was used for the production of biodiesel through enzymatic esterification of fatty acids. The crude lipase powder and fermentation broth were immobilized on a cheap fiber cloth carrier. The conditions of lipase-catalyzed esterification between long-chain fatty acids and methanol in a solvent system were investigated in detail, including the temperature, pH value, substrate concentration, solvent, absorbent agent, enzyme dosage and purity, immobilization method, the mode of addition of substrate. The results show that reaction temperature, pH of lipase micro-environment, substrate concentration, enzyme dosage and purity affect the esterification strongly. Several new methods and enzymatic procedures for improving the enzymatic reaction involving the process cost are also discussed, such as fossil diesel fuel as reaction solvent, immobilization method, multi-step gradient addition of methanol. The esterification degree of 92.8% was obtained with oleic acid and methanol under the optimal reaction condition after 12.5 h reaction time. The half-life of the immobilized lipase preparation from crude free lipase powder for esterification was 15 days.
文摘As a combination of bio-mechanism and engineering technology, robot fish has become a multidisci- plinary research that mainly involves both hydrodynamics-based control and actuation technology. This paper presents a simplified propulsive model for carangiform propulsion, which is a swimming mode suitable for high speed and high efficiency. The carangiform motion is modeled as an N-joint nscillating mechanism that is composed of two basic components： the streamlined fish body represented by a planar spline curve and its hmate caudal tail by an oscillating foil. The speed of fish＇s straight swimming is adjusted by modulating the joint＇s oscillating frequency, and its orientation is tuned by different joint＇s deflection. The results from actual experiment showed that the proposed simplified propulsive model could be a viable eandidate for application in aquatic： swimming vehicles.
基金Foundation of the Robotics Laboratory, Chinese Academy of Sciences (No: RL200002)
文摘Previously, researchers raised the accuracy for a robot′s hand to track a specified path in Car-tesian space mainly through increasing the number of knots on the path and the number of the path′s segments, which results in the heavier online computational burden for the robot controller. Aiming at overcoming this drawback, the authors propose a new kind of real-time accurate hand path tracking and joint trajectory planning method. Through selecting some extra knots on the specified hand path by a certain rule and introducing a sinusoidal function to the joint displacement equation of each segment, this method can greatly raise the path tracking accuracy of robot′s hand and does not change the number of the path′s segments. It also does not increase markedly the computational burden of robot controller. The result of simulation indicates that this method is very effective, and has important value in increasing the application of industrial robots.
文摘The floating oil storage system has been proposed as a new facility for Strategic Petroleum Reserve (SPR) in China. Mooring is one of the key technologies to ensure the safety, reliability, and performance of the oil storage system. This paper describes the concept, analysis, design and reliability of the mooring system. For mooring system design of these oil vessels, analysis is essential of the behavior of the vessel in connection with mooring facilities of nonlinear resilience. A nonlinear mathematical model for analyzing a moored vessel is established and solved. Some results of numerical simulations are presented. Assessment of the safety regarding the mooring system in terms of failure probability is carried out. Another simulation model for calculating the failure probability of the mooring system is proposed. The design parameters that have an influence on the characteristics of the failure probability have been identified. The simulation results,show that the mooring system has an annual reliability value of 0.999998. The proposed simulation method is proved to be effective in quantitative evaluation of the safety of the mooring system for floating oil storage vessels.
基金National Natural Science Foundation ofChina(No.59971065)
文摘Cubic boron nitride(c-BN) films were deposited on W6Mo5Cr4V2 high speed steel(HSS) substrate implanted with boron ion by RF-magnetron sputtering. The films were analyzed by the bending beam method, scratch test, XPS and AFM. The experimental results show that the implantation of boron atom can reduce the internal stress and improve the adhesion strength of the films. The critical load of scratch test rises to 27.45 N, compared to 1.75 N of c-BN film on the unimplanted HSS. The AFM shows that the surface of the c-BN film on the implanted HSS is low in roughness and small in grain size. Then the composition of the boron implanted layer was analyzed by the XPS. And the influence of the boron implanted layer on the internal stress and adhesion strength of c-BN films were investigated.
文摘Objective To oberve the change in blood glutathione peroxidase (GSH-Px) protein levels of residents in the low-selenium (Se) area by contrasting the blood GSH-Px protein level of the children in the Keshan disease area with those in the Kashin-Beck disease and non-endemic areas. Methods GSH-Px protein levels were measured by enzyme-linked immunosorbent assays (ELISA). The Se content and GSH-Px activity were assayed by the 2,3-diaminonaphthalene spectrofluorimetric method and glutathione reductase-coupled method respectively. Results ①The blood Se content and GSH-Px protein level of children in Keshan disease area (Moding) were significantly lower than those in Xi’an non-endemic area, however, there was no significant difference when compared with the low-Se non-endemic area; ②The blood Se content, GSH-Px activity and GSH-Px protein level of children in the Kashin-Beck disease area (Yulin) were significantly lower than those of children in two non-endemic areas and in the Keshan disease area; ③The blood Se content and GSH-Px activity were positively correlated to the GSH-Px protein level respectively. Conclusion These results indicate that the blood GSH-Px protein level is decreased in the low-Se residents. The Se status not only affects the GSH-Px activity but also regulate the GSH-Px protein level.
