After 20 years of systematic studies,15 subfamilies,38 genus and 104 species of braconid wasp in Hunan province are recorded.According to the studies on both male and femal genitalia of Aridelus hunanensis You,Xio...After 20 years of systematic studies,15 subfamilies,38 genus and 104 species of braconid wasp in Hunan province are recorded.According to the studies on both male and femal genitalia of Aridelus hunanensis You,Xiong et Zhou and Aridelus rutilipes Papp,and on both male genitalia of Streblocera flava You et Xiong and Streblocera okadai Watanabe,it is pointed in this paper that Aridelus hunanensis You,Xiong et Zhou and Streblocera flava You et Xiong are still considered valid independent species.This disagrees with Chen X.’s and C.van Achterberg’s (1997) opinion that Aridelus hunanensis You,Xiong et Zhou is a junior synonym of Aridelus rutilipes Papp,and Streblocera flava You et Xiong is the same species of Streblocera okadai Watanabe. Key words:Braconid wasp;taxonomy;fauna;展开更多
在用聚丙烯酸制备超强吸水材料的过程中加入一定量的煅烧煤系高岭土和丙烯酰胺能有效降低材料成本和提高其耐盐性。通过正交实验,找出了制备成本低和耐盐性好的超强吸水复合材料的条件,当煅烧煤系高岭土量为丙烯酸单体质量50%,丙烯酰胺...在用聚丙烯酸制备超强吸水材料的过程中加入一定量的煅烧煤系高岭土和丙烯酰胺能有效降低材料成本和提高其耐盐性。通过正交实验,找出了制备成本低和耐盐性好的超强吸水复合材料的条件,当煅烧煤系高岭土量为丙烯酸单体质量50%,丙烯酰胺加入量为70%,中和度为90%,引发剂和交联剂量分别为0.3%和0.025%时,制得产品吸生理盐水(0.9%N aC l溶液)和吸自来水率分别达到60 g/g和325 g/g,吸水后凝胶强度明显提高。展开更多
Ultra-high strength Al alloy system was developed by cryorolling and the contribution of various strengthening mechanisms to the overall yield strength of the system was evaluated. Cryorolling of Al-4%Cu-3%TiB2 in sit...Ultra-high strength Al alloy system was developed by cryorolling and the contribution of various strengthening mechanisms to the overall yield strength of the system was evaluated. Cryorolling of Al-4%Cu-3%TiB2 in situ composite followed by short annealing at 175 ℃ and ageing at 125℃ resulted in an ultra-high yield strength of about 800 MPa with 9%total elongation. The strengthening contributions form solid solution strengthening, grain refinement, dislocation strengthening, precipitation hardening and dispersion strengthening were evaluated using standard equations. It was estimated that the maximum contribution was from grain refinement due to cryorolling followed by precipitation and dispersion strengthening.展开更多
This paper presents the development of ultra high strength concrete （UHSC） using local materials. UHSC mixture proportions were developed using local materials so that UHSC may be made more affordable to a wider var...This paper presents the development of ultra high strength concrete （UHSC） using local materials. UHSC mixture proportions were developed using local materials so that UHSC may be made more affordable to a wider variety of applications. Specifically, local sand with a top size of 600 um, and locally available Type I/II cement and silica fume were used in this research. Each of these material selections is seen as an improvement in sustainability for UHSC. Two mixtures （one with and one without fibers） were recommended as the UHSC mixtures. The greatest compressive strengths obtained in this study were 165.6 MPa for UHSC with steel fibers and 161.9 MPa for UHSC without fibers. The compressive and flexural strengths obtained from the UHSC mixtures developed in this work are comparable to UHSC strengths presented in the literature. Producing this innovative material with local materials reduces the cost of the material, improves sustainability, and produces mechanical performance similar to prepackaged, commercially available products.展开更多
Magnesium matrix nanocomposite reinforced with carbon nanotubes(CNTs/AZ91D) was fabricated by mechanical stirring and high intensity ultrasonic dispersion processing.The microstructures and mechanical properties of th...Magnesium matrix nanocomposite reinforced with carbon nanotubes(CNTs/AZ91D) was fabricated by mechanical stirring and high intensity ultrasonic dispersion processing.The microstructures and mechanical properties of the nanocomposite were investigated.The results show that CNTs are well dispersed in the matrix and combined with the matrix very well.As compared with AZ91D magnesium alloy matrix,the tensile strength,yield strength and elongation of the 1.5%CNTs/AZ91D nanocomposite are improved by 22%,21%and 42%respectively in permanent mold casting.The strength and ductility of the nanocomposite are improved simultaneously.The tensile fracture analysis shows that the damage mechanism of nanocomposite is still brittle fracture.But the CNTs can prevent the local crack propagation to some extent.展开更多
Efficient electrode material is crucial for energy conversion from renewable sources such as solar electricity. We present a method for preparation of carbon nanotubes （CNTs） with zeolitic imidazolate frameworks （Z...Efficient electrode material is crucial for energy conversion from renewable sources such as solar electricity. We present a method for preparation of carbon nanotubes （CNTs） with zeolitic imidazolate frameworks （ZIFs, e.g., ZIF-8） via an in situ pyrolysis process. The resultant materials are completely new carbon composites with desirable hierarchical porosity and nitrogen-doped features. Electron microscopy images show that CNTs with small external diameters enable more uniform dispersion of ZlF-8-derived carbons, subsequently yielding a unique hierarchically porous structure. Such carbon shows superior activity in oxygen reduction reaction （ORR） and high performance of supercapacitance, making it a valu- able metal-flee electrode material and a competent alternative to the state-of-the-art Pt/C catalyst. The electrocatalytic performance of CNTs can be dramatically improved by the incorporation of ZIF-8-derived carbons, which is attributed to the combination of good conductivity, abundant accessible dopant species, as well as proper porosity. Our method offers a new avenue for constructing electrocatalysts by effective integration of ZlF-8-derived carbon and the CNTs skeleton.展开更多
文摘After 20 years of systematic studies,15 subfamilies,38 genus and 104 species of braconid wasp in Hunan province are recorded.According to the studies on both male and femal genitalia of Aridelus hunanensis You,Xiong et Zhou and Aridelus rutilipes Papp,and on both male genitalia of Streblocera flava You et Xiong and Streblocera okadai Watanabe,it is pointed in this paper that Aridelus hunanensis You,Xiong et Zhou and Streblocera flava You et Xiong are still considered valid independent species.This disagrees with Chen X.’s and C.van Achterberg’s (1997) opinion that Aridelus hunanensis You,Xiong et Zhou is a junior synonym of Aridelus rutilipes Papp,and Streblocera flava You et Xiong is the same species of Streblocera okadai Watanabe. Key words:Braconid wasp;taxonomy;fauna;
文摘在用聚丙烯酸制备超强吸水材料的过程中加入一定量的煅烧煤系高岭土和丙烯酰胺能有效降低材料成本和提高其耐盐性。通过正交实验,找出了制备成本低和耐盐性好的超强吸水复合材料的条件,当煅烧煤系高岭土量为丙烯酸单体质量50%,丙烯酰胺加入量为70%,中和度为90%,引发剂和交联剂量分别为0.3%和0.025%时,制得产品吸生理盐水(0.9%N aC l溶液)和吸自来水率分别达到60 g/g和325 g/g,吸水后凝胶强度明显提高。
基金the Department of Science & Technology (DST) for their financial support for carrying out this research through Fast Track Scheme (DST Sanction No: SR/FT/ET-005/2008)Technical Education Quality Improvement Programme (TEQIP)
文摘Ultra-high strength Al alloy system was developed by cryorolling and the contribution of various strengthening mechanisms to the overall yield strength of the system was evaluated. Cryorolling of Al-4%Cu-3%TiB2 in situ composite followed by short annealing at 175 ℃ and ageing at 125℃ resulted in an ultra-high yield strength of about 800 MPa with 9%total elongation. The strengthening contributions form solid solution strengthening, grain refinement, dislocation strengthening, precipitation hardening and dispersion strengthening were evaluated using standard equations. It was estimated that the maximum contribution was from grain refinement due to cryorolling followed by precipitation and dispersion strengthening.
文摘This paper presents the development of ultra high strength concrete （UHSC） using local materials. UHSC mixture proportions were developed using local materials so that UHSC may be made more affordable to a wider variety of applications. Specifically, local sand with a top size of 600 um, and locally available Type I/II cement and silica fume were used in this research. Each of these material selections is seen as an improvement in sustainability for UHSC. Two mixtures （one with and one without fibers） were recommended as the UHSC mixtures. The greatest compressive strengths obtained in this study were 165.6 MPa for UHSC with steel fibers and 161.9 MPa for UHSC without fibers. The compressive and flexural strengths obtained from the UHSC mixtures developed in this work are comparable to UHSC strengths presented in the literature. Producing this innovative material with local materials reduces the cost of the material, improves sustainability, and produces mechanical performance similar to prepackaged, commercially available products.
文摘Magnesium matrix nanocomposite reinforced with carbon nanotubes(CNTs/AZ91D) was fabricated by mechanical stirring and high intensity ultrasonic dispersion processing.The microstructures and mechanical properties of the nanocomposite were investigated.The results show that CNTs are well dispersed in the matrix and combined with the matrix very well.As compared with AZ91D magnesium alloy matrix,the tensile strength,yield strength and elongation of the 1.5%CNTs/AZ91D nanocomposite are improved by 22%,21%and 42%respectively in permanent mold casting.The strength and ductility of the nanocomposite are improved simultaneously.The tensile fracture analysis shows that the damage mechanism of nanocomposite is still brittle fracture.But the CNTs can prevent the local crack propagation to some extent.
基金supported by the Award Program for Fujian Minjiang Scholar Professorshipthe National Natural Science Foundation of China (21571035)
文摘Efficient electrode material is crucial for energy conversion from renewable sources such as solar electricity. We present a method for preparation of carbon nanotubes （CNTs） with zeolitic imidazolate frameworks （ZIFs, e.g., ZIF-8） via an in situ pyrolysis process. The resultant materials are completely new carbon composites with desirable hierarchical porosity and nitrogen-doped features. Electron microscopy images show that CNTs with small external diameters enable more uniform dispersion of ZlF-8-derived carbons, subsequently yielding a unique hierarchically porous structure. Such carbon shows superior activity in oxygen reduction reaction （ORR） and high performance of supercapacitance, making it a valu- able metal-flee electrode material and a competent alternative to the state-of-the-art Pt/C catalyst. The electrocatalytic performance of CNTs can be dramatically improved by the incorporation of ZIF-8-derived carbons, which is attributed to the combination of good conductivity, abundant accessible dopant species, as well as proper porosity. Our method offers a new avenue for constructing electrocatalysts by effective integration of ZlF-8-derived carbon and the CNTs skeleton.
