Genetic diversity of 32 individuals of P. chinensis in the Chinese coastal waters of the Huanghai and Bobal Seas was detected by RAPD technique. Twenty decamer primers of OPI were used for DNA amplification for each i...Genetic diversity of 32 individuals of P. chinensis in the Chinese coastal waters of the Huanghai and Bobal Seas was detected by RAPD technique. Twenty decamer primers of OPI were used for DNA amplification for each individual. The results showed that: Seventeen primers obtained reproducible fingerprints, and the bands were clear. Thirty--nine of 106 loci detected were polymorphic, amounting to 36. 8 %. Mean genetic distance was 0. 094 1 0. 020 6; 68 markers (63. 2 % of the total) showed stable homogeneity in all of the 32 individuals.展开更多
A rice male-sterile mutant OsMS-L of japonica cultivar 9522 background, was obtained in M4 population treated with Co γ-Ray. Genetic analysis indicated that the 60 male-sterile phenotype was controlled by a single re...A rice male-sterile mutant OsMS-L of japonica cultivar 9522 background, was obtained in M4 population treated with Co γ-Ray. Genetic analysis indicated that the 60 male-sterile phenotype was controlled by a single recessive gene. Results of tissue section showed that at microspore stage, OsMS-L tapetum was retarded. Then tapetal cells ex- panded and microspores degenerated. No matured pollens were observed in OsMS-L anther locus. To map OsMS-L lo- cus, an F2 population was constructed from the cross be- tween the OsMS-L (japonica) and LongTeFu B(indica). Firstly, the OsMS-L locus was roughly mapped between two SSR markers, RM109 and RM7562 on chromosome 2. And then eleven polymorphic markers were developed for further fine fine-mapping. At last the OsMS-L locus was mapped between the two InDel markers, Lhs10 and Lhs6 with genetic distance of 0.4 cM, respectively. The region was delimited to 133 kb. All these results were useful for further cloning and functional analysis of OsMS-L.展开更多
In flat jet electrochemical milling, the electrolyte forms a backward parallel flow after impacting the workpiece, resulting in a weak current density distribution on the workpiece. Poor surface quality usually occurs...In flat jet electrochemical milling, the electrolyte forms a backward parallel flow after impacting the workpiece, resulting in a weak current density distribution on the workpiece. Poor surface quality usually occurs on the machined titanium alloy surface because it inevitably suffers from the weak current density. In this study, a method of flat jet electrochemical milling with tailoring the backward parallel flow was proposed to eliminate the negative effects caused by the weak current density. Multiphysics simulations are carried out to comprehend the mechanism of flat jetEC milling with tailoring backward parallel flow and better construct the novel tool electrode.Experiments on flat jet electrochemical milling of TC4 alloy with and without tailoring backward parallel flow are conducted. The results reveal that, compared with flat jet electrochemical milling without tailoring backward parallel flow, the recommended tool reduces the surface roughness by86% to 93%, and improves the material removal rate by 93% to 163% with different feed rates.Additionally, the recommended tool is more conducive to maintaining the inherent hardness of the material. Finally, a surface with low Sa of 0.37 μm is obtained.展开更多
The genetic structure of three stocks (K, H and S) of Penaeus chinensis was detected by RAPD method which useed 41 random oligonucleotide primers with 10 bases. Stock K was from the spawning stock of the western coast...The genetic structure of three stocks (K, H and S) of Penaeus chinensis was detected by RAPD method which useed 41 random oligonucleotide primers with 10 bases. Stock K was from the spawning stock of the western coastal waters of the Korea Peninsula, H was from the Huanghai Sea-Bohai Sea stock and S was from the health cultured stock in Jimo, Shandong Province, China. Three genetic markers, F-02(540), OPN-13(800) and OPN-20(2200), which could differentiate the three different stocks, have been reported. The basic data for marker assisted selection (MAS) on genetic breeding of Penaeus chinensis are provided.展开更多
Macro electromechanical milling has recently attracted increasing attention because numerous large thin-walled structures composed of difficult-to-cut materials are employed in the aerospace field.This paper reviews r...Macro electromechanical milling has recently attracted increasing attention because numerous large thin-walled structures composed of difficult-to-cut materials are employed in the aerospace field.This paper reviews recent developments in state-of-the-art macro electromechanical milling.The fundamental aspects of material removal mechanisms,such as the generation and breakdown behaviors of passive oxide films of typical difficult-to-cut materials,were discussed.Rapid methods for breaking down passive films are summarized,and simulation methods for the machining process coupling multiple physical fields are introduced.Specific electrochemical milling methods,including fly mode electrochemical milling and sink electrochemical milling,are classified.Efforts made to improve process performance,such as the material removal rate,surface quality,and machining accuracy,are discussed.In addition,the main hybrid electrochemical milling methods,including electrochemical discharge milling,mechano-electrochemical milling,and electrochemical mill grinding,are also presented.展开更多
Wire electrochemical machining(WECM) is a flexible and effective method for machining complex-shaped metal components, but the ability to machine large-thickness workpieces is hampered by the difficulty of transportin...Wire electrochemical machining(WECM) is a flexible and effective method for machining complex-shaped metal components, but the ability to machine large-thickness workpieces is hampered by the difficulty of transporting electrolytic products in the narrow machining gap. This paper proposes a novel hybrid machining technique that combines the characteristics of WECM and wire electric discharge machining(WEDM), namely, helical wire electrochemical discharge machining. The formation mechanism of electrical discharge in salt-glycol solution was elucidated.Experiments and simulation were conducted to verify the machining mechanism and investigate the performance of the proposed technique. The results show that as the recast layer can be removed by electrochemical action during the proposed process, the surface quality is effectively improved.Minimum surface roughness of the slit sidewall after machining reaches Ra= 0.12 μm. Minimum standard deviation of the slit after machining reaches 5 μm. Moreover, the existence of the discharges significantly improves the transport of the electrolytic products, thus ensuring high machining efficiency. In the experiments, the maximum feed rate of the helical wire electrochemical discharge machining reaches 7 μm/s(12.6 mm^(2)/min). Finally, mortise structures of Inconel 718 with good machining accuracy and surface quality are fabricated with a feed rate of 5 μm/s(9 mm^(2)/min),demonstrating that electrical discharge assisted helical wire ECM is a promising technique for machining large-thickness hard metal materials.展开更多
A kind of baculovirus was isolated from the cephalothorax homogenate of sick or morbid Penaeus chinensis by differential centrifugation and density gradient centrifugation. Electron microscopic examination of ultrathi...A kind of baculovirus was isolated from the cephalothorax homogenate of sick or morbid Penaeus chinensis by differential centrifugation and density gradient centrifugation. Electron microscopic examination of ultrathin section of the gills, stomach and mid-gut tissues also revealed the presence of rod-shaped baculoviral particles with the same size in the affected cell nuclei, where most of the virions arranging in cluster assembled and caused a series of cytopathic changes. The virion covered with bilaminal envelope was 320 ~ 400 nm × 100 ~ 130 nm in size, whereas the nucleocapsid ranged in size of 250~ 300 nm in length and 70 ~ 100 nm in breadth respectively. No nuclear polyhedron or granulin occlusion theies have been found in cells. According to the principle of viral classification, this newly found virus could probably belong to the non-occluded subgroup of insect baculoviridae, i. e., C subgroup baculovirus.展开更多
In view of the fact that the follow-up search for an optimal topology is affected by deleting a large number of high-relative-density elements. When the typical density interpolation approach, namely, solid isotropic ...In view of the fact that the follow-up search for an optimal topology is affected by deleting a large number of high-relative-density elements. When the typical density interpolation approach, namely, solid isotropic microstructures with penalization （SIMP）, is employed in the continuum structural topology optimization, a new density interpolation approach based on the logistic function is proposed in this paper. This method can weaken low-relative-density elements while enhancing high-relative-density elements by polarization, and then rationally realize polarization of the intermediate density elements. It can reduce the number of gray-scale elements as much as possible to get the optimal topology with distinct boundaries in conjunction with the sensitivity filtering method based on particle swarm optimization （PSO）. Several typical numerical examples are given to demonstrate this method.展开更多
This paper was concerned with the tensile mechanics behavior of the composite π-joint under static tensile loading. The numerical strength analysis methodology was presented containing the basis assumption for the an...This paper was concerned with the tensile mechanics behavior of the composite π-joint under static tensile loading. The numerical strength analysis methodology was presented containing the basis assumption for the analysis, the material modeling, and the selected element type. It was assumed that the composite ply had transverse isotropic material properties and the adhesive had linear elastic properties. With the goal of the strength analysis to determine the onset of the damage initiation and the ultimate failure load, two stiffness degradation models were discussed and a modified maximum stress failure criteria was presented. To verify the numerical model, a pull-off test scheme was performed and the experimental data of five specimens were given. The experimental results indicate that the damage initiation location and the failure load were consistent with numerical predictions and verified the feasibility of the numerical model.展开更多
基金the National Natural Science Foundation of China finder the Project! No. 39620260.
文摘Genetic diversity of 32 individuals of P. chinensis in the Chinese coastal waters of the Huanghai and Bobal Seas was detected by RAPD technique. Twenty decamer primers of OPI were used for DNA amplification for each individual. The results showed that: Seventeen primers obtained reproducible fingerprints, and the bands were clear. Thirty--nine of 106 loci detected were polymorphic, amounting to 36. 8 %. Mean genetic distance was 0. 094 1 0. 020 6; 68 markers (63. 2 % of the total) showed stable homogeneity in all of the 32 individuals.
基金This work Was supported by The National Basic Research Program of China(Grant No.TG1999011605)the Shanghai Municipal Committee of Science and Technology(Grant No.03DJ14016).
文摘A rice male-sterile mutant OsMS-L of japonica cultivar 9522 background, was obtained in M4 population treated with Co γ-Ray. Genetic analysis indicated that the 60 male-sterile phenotype was controlled by a single recessive gene. Results of tissue section showed that at microspore stage, OsMS-L tapetum was retarded. Then tapetal cells ex- panded and microspores degenerated. No matured pollens were observed in OsMS-L anther locus. To map OsMS-L lo- cus, an F2 population was constructed from the cross be- tween the OsMS-L (japonica) and LongTeFu B(indica). Firstly, the OsMS-L locus was roughly mapped between two SSR markers, RM109 and RM7562 on chromosome 2. And then eleven polymorphic markers were developed for further fine fine-mapping. At last the OsMS-L locus was mapped between the two InDel markers, Lhs10 and Lhs6 with genetic distance of 0.4 cM, respectively. The region was delimited to 133 kb. All these results were useful for further cloning and functional analysis of OsMS-L.
基金supported by Defense Industrial Technology Development Program (Grant No. JCKY2021605B003)National Natural Science Foundation of China for Creative Research Groups (Grant No. 51921003)Postgraduate Research & Practice Innovation Program of Jiangsu Province (Grant No. KYCX20_0181)。
文摘In flat jet electrochemical milling, the electrolyte forms a backward parallel flow after impacting the workpiece, resulting in a weak current density distribution on the workpiece. Poor surface quality usually occurs on the machined titanium alloy surface because it inevitably suffers from the weak current density. In this study, a method of flat jet electrochemical milling with tailoring the backward parallel flow was proposed to eliminate the negative effects caused by the weak current density. Multiphysics simulations are carried out to comprehend the mechanism of flat jetEC milling with tailoring backward parallel flow and better construct the novel tool electrode.Experiments on flat jet electrochemical milling of TC4 alloy with and without tailoring backward parallel flow are conducted. The results reveal that, compared with flat jet electrochemical milling without tailoring backward parallel flow, the recommended tool reduces the surface roughness by86% to 93%, and improves the material removal rate by 93% to 163% with different feed rates.Additionally, the recommended tool is more conducive to maintaining the inherent hardness of the material. Finally, a surface with low Sa of 0.37 μm is obtained.
文摘The genetic structure of three stocks (K, H and S) of Penaeus chinensis was detected by RAPD method which useed 41 random oligonucleotide primers with 10 bases. Stock K was from the spawning stock of the western coastal waters of the Korea Peninsula, H was from the Huanghai Sea-Bohai Sea stock and S was from the health cultured stock in Jimo, Shandong Province, China. Three genetic markers, F-02(540), OPN-13(800) and OPN-20(2200), which could differentiate the three different stocks, have been reported. The basic data for marker assisted selection (MAS) on genetic breeding of Penaeus chinensis are provided.
基金co-supported by the Defense Industrial Technology Development Program,the Fundamental Research Funds for the Central Universities and the National Natural Science Foundation of China for Creative Research Groups(Nos.JCKY2021605B003,NP2022405 and 51921003).
文摘Macro electromechanical milling has recently attracted increasing attention because numerous large thin-walled structures composed of difficult-to-cut materials are employed in the aerospace field.This paper reviews recent developments in state-of-the-art macro electromechanical milling.The fundamental aspects of material removal mechanisms,such as the generation and breakdown behaviors of passive oxide films of typical difficult-to-cut materials,were discussed.Rapid methods for breaking down passive films are summarized,and simulation methods for the machining process coupling multiple physical fields are introduced.Specific electrochemical milling methods,including fly mode electrochemical milling and sink electrochemical milling,are classified.Efforts made to improve process performance,such as the material removal rate,surface quality,and machining accuracy,are discussed.In addition,the main hybrid electrochemical milling methods,including electrochemical discharge milling,mechano-electrochemical milling,and electrochemical mill grinding,are also presented.
基金the financial support provided by the National Natural Science Foundation of China(No.52175413)the Natural Science Foundation of Jiangsu Province(No.BK20192007)+3 种基金the National Natural Science Foundation of China for Creative Research Groups(No.51921003)the Fundamental Research Funds for the Central Universities(No.NS2021034)the Aeronautical Science Foundation of China(No.201907052002)the Interdisciplinary Innovation Fund for Doctoral Students of Nanjing University of Aeronautics and Astronautics(No.KXKCXJJ202207).
文摘Wire electrochemical machining(WECM) is a flexible and effective method for machining complex-shaped metal components, but the ability to machine large-thickness workpieces is hampered by the difficulty of transporting electrolytic products in the narrow machining gap. This paper proposes a novel hybrid machining technique that combines the characteristics of WECM and wire electric discharge machining(WEDM), namely, helical wire electrochemical discharge machining. The formation mechanism of electrical discharge in salt-glycol solution was elucidated.Experiments and simulation were conducted to verify the machining mechanism and investigate the performance of the proposed technique. The results show that as the recast layer can be removed by electrochemical action during the proposed process, the surface quality is effectively improved.Minimum surface roughness of the slit sidewall after machining reaches Ra= 0.12 μm. Minimum standard deviation of the slit after machining reaches 5 μm. Moreover, the existence of the discharges significantly improves the transport of the electrolytic products, thus ensuring high machining efficiency. In the experiments, the maximum feed rate of the helical wire electrochemical discharge machining reaches 7 μm/s(12.6 mm^(2)/min). Finally, mortise structures of Inconel 718 with good machining accuracy and surface quality are fabricated with a feed rate of 5 μm/s(9 mm^(2)/min),demonstrating that electrical discharge assisted helical wire ECM is a promising technique for machining large-thickness hard metal materials.
文摘A kind of baculovirus was isolated from the cephalothorax homogenate of sick or morbid Penaeus chinensis by differential centrifugation and density gradient centrifugation. Electron microscopic examination of ultrathin section of the gills, stomach and mid-gut tissues also revealed the presence of rod-shaped baculoviral particles with the same size in the affected cell nuclei, where most of the virions arranging in cluster assembled and caused a series of cytopathic changes. The virion covered with bilaminal envelope was 320 ~ 400 nm × 100 ~ 130 nm in size, whereas the nucleocapsid ranged in size of 250~ 300 nm in length and 70 ~ 100 nm in breadth respectively. No nuclear polyhedron or granulin occlusion theies have been found in cells. According to the principle of viral classification, this newly found virus could probably belong to the non-occluded subgroup of insect baculoviridae, i. e., C subgroup baculovirus.
基金supported by the National Natural Science Foundation of China(No.51105229)the National Science Foundation for Distinguished Young Scholars of Hubei Province of China(No.2013CFA022)+1 种基金the Science and Technology Support Program of Hubei Province of China(N0.2015BHE026)the Fund Project of Outstanding Dissertation of China Three Gorges University(No.2014PY026)
文摘In view of the fact that the follow-up search for an optimal topology is affected by deleting a large number of high-relative-density elements. When the typical density interpolation approach, namely, solid isotropic microstructures with penalization （SIMP）, is employed in the continuum structural topology optimization, a new density interpolation approach based on the logistic function is proposed in this paper. This method can weaken low-relative-density elements while enhancing high-relative-density elements by polarization, and then rationally realize polarization of the intermediate density elements. It can reduce the number of gray-scale elements as much as possible to get the optimal topology with distinct boundaries in conjunction with the sensitivity filtering method based on particle swarm optimization （PSO）. Several typical numerical examples are given to demonstrate this method.
文摘This paper was concerned with the tensile mechanics behavior of the composite π-joint under static tensile loading. The numerical strength analysis methodology was presented containing the basis assumption for the analysis, the material modeling, and the selected element type. It was assumed that the composite ply had transverse isotropic material properties and the adhesive had linear elastic properties. With the goal of the strength analysis to determine the onset of the damage initiation and the ultimate failure load, two stiffness degradation models were discussed and a modified maximum stress failure criteria was presented. To verify the numerical model, a pull-off test scheme was performed and the experimental data of five specimens were given. The experimental results indicate that the damage initiation location and the failure load were consistent with numerical predictions and verified the feasibility of the numerical model.
