In this work,a novel ultrahigh-strength Al-10Zn-3.5Mg-1.5Cu alloy was fabricated by powder metallurgy followed by hot extrusion.Investigations on microstructural evolution and mechanical properties of the fabricated s...In this work,a novel ultrahigh-strength Al-10Zn-3.5Mg-1.5Cu alloy was fabricated by powder metallurgy followed by hot extrusion.Investigations on microstructural evolution and mechanical properties of the fabricated samples were carried out.The results show that the grain size of sintered samples matches with the powder particles after ball milling.The relative densities of sintered and hot extruded samples reach 99.1%and 100%,respectively.Owing to the comprehensive mechanism of grain refinement,aging and dispersion strengthening,the ultimate tensile strength,yield strength and elongation of the Al-10Zn-3.5Mg-1.5Cu alloy after hot extrusion and subsequent heat treatment achieve 810 MPa,770 MPa and 8%,respectively.展开更多
[目的]筛选柴胡明蚜Hyadaphis bupleuri有效防治药剂,并对天敌异色瓢虫和龟纹瓢虫进行安全性评价。[方法]通过浸虫法在室内进行了10种药剂筛选试验,并通过田间药效试验进行验证。通过浸虫法对主要天敌异色瓢虫和龟纹瓢虫进行了安全性评...[目的]筛选柴胡明蚜Hyadaphis bupleuri有效防治药剂,并对天敌异色瓢虫和龟纹瓢虫进行安全性评价。[方法]通过浸虫法在室内进行了10种药剂筛选试验,并通过田间药效试验进行验证。通过浸虫法对主要天敌异色瓢虫和龟纹瓢虫进行了安全性评价。[结果]室内药效结果表明:柴胡明蚜对供试10种药剂全部敏感,药后72 h校正死亡率均达到96%以上。在田间70%噻虫嗪水分散粒剂22.5 g a.i./hm^(2)、10%吡虫啉可湿性粉剂262.5 g a.i./hm^(2)、50%噻虫啉水分散粒剂180 g a.i./hm^(2)和25 g/L高效氯氟氰菊酯乳油900 g a.i./hm^(2)对柴胡明蚜防效高,见效快,药后1 d防效为78.01%~90.54%;药后7 d防效为93.83%~98.89%。田间防效较好的药剂中,10%吡虫啉可湿性粉剂、25 g/L高效氯氟氰菊酯乳油对2种瓢虫相对安全,药剂高低浓度处理后2种瓢虫72 h校正死亡率为0.83%~41.28%。[结论]田间防治推荐优先施用10%吡虫啉和25 g/L高效氯氟氰菊酯防治柴胡明蚜,可结合其他药剂交替施用。展开更多
The extruded plate of powder metallurgy AA2024 aluminum alloy was successfully solid-state joined by friction stir welding(FSW) to demonstrate potential applications in the aerospace and automotive industries. For det...The extruded plate of powder metallurgy AA2024 aluminum alloy was successfully solid-state joined by friction stir welding(FSW) to demonstrate potential applications in the aerospace and automotive industries. For determining the optimal processing parameters of FSW, the microstructure, mechanical properties, and fracture behavior of FSW joints were evaluated. When the processing parameters were optimized with 2000 r/min rotation speed and100 mm/min traverse speed, high quality welds were achieved. The ultimate tensile strength yield strength and elongation of the joint can reach 415 MPa(85% of the base metal strength), 282 MPa, and 9.5%, respectively. The hardness of the joint gradually decreased from the alloy matrix to the heat-affected zone. The lowest strength and hardness appeared near the heat-affected zone because of the over-aging caused by heat flow from repeated stirring during FSW. The average grain size of the stir zone(2.15 μm) was smaller than that of the base metal(4.43 μm) and the heat-affected zone(5.03 μm), whose grains had <110> preferred orientation.展开更多
In this study, the Harmonia axyridis vitellogenin gene 2 (HmVg2) sequence was identified from transcriptomic databases of female adult H. axyridis and cloned into pMD18-T vector. The HmVg2 gene was 5 460 bp in length,...In this study, the Harmonia axyridis vitellogenin gene 2 (HmVg2) sequence was identified from transcriptomic databases of female adult H. axyridis and cloned into pMD18-T vector. The HmVg2 gene was 5 460 bp in length, and formed with an open reading frame (ORF) of 5 361 nucleotides (GenBank accession no. KY794939). The putative molecular weight of the primary HmVg2 protein was 203.459 kDa and the predicted isoelectric point (pI) was 8.59. HmVg2 contained a signal peptide, vitellogenin N-terminal (vitellogenin-N) domain, domain of unknown function 1943 (DUF1934) domain and von Willebrand factor type D (VWD) domain. The developmental expression profiling showed that HmVg2 was extremely highly expressed in female insects, but was expressed at lower levels in male insects. In female insects, HmVg2 was mainly expressed in the wing and fat body. The double-stranded RNA-HmVg2/-GFP was injected into H. axyridis, and qRT-PCR results showed that the HmVg2 gene was specifically silenced. The eggs laid during the first five days and the hatching rate of eggs was lower than controls after dsHmVg2 injection. This investigation demonstrated that the HmVg2 gene plays an important role in H. axyridis reproduction and enriches the function of the insect vitellogenin gene.展开更多
基金Project(FRF-GF-19-012AZ)supported by the Fundamental Research Funds for the Central Universities,China。
文摘In this work,a novel ultrahigh-strength Al-10Zn-3.5Mg-1.5Cu alloy was fabricated by powder metallurgy followed by hot extrusion.Investigations on microstructural evolution and mechanical properties of the fabricated samples were carried out.The results show that the grain size of sintered samples matches with the powder particles after ball milling.The relative densities of sintered and hot extruded samples reach 99.1%and 100%,respectively.Owing to the comprehensive mechanism of grain refinement,aging and dispersion strengthening,the ultimate tensile strength,yield strength and elongation of the Al-10Zn-3.5Mg-1.5Cu alloy after hot extrusion and subsequent heat treatment achieve 810 MPa,770 MPa and 8%,respectively.
文摘[目的]筛选柴胡明蚜Hyadaphis bupleuri有效防治药剂,并对天敌异色瓢虫和龟纹瓢虫进行安全性评价。[方法]通过浸虫法在室内进行了10种药剂筛选试验,并通过田间药效试验进行验证。通过浸虫法对主要天敌异色瓢虫和龟纹瓢虫进行了安全性评价。[结果]室内药效结果表明:柴胡明蚜对供试10种药剂全部敏感,药后72 h校正死亡率均达到96%以上。在田间70%噻虫嗪水分散粒剂22.5 g a.i./hm^(2)、10%吡虫啉可湿性粉剂262.5 g a.i./hm^(2)、50%噻虫啉水分散粒剂180 g a.i./hm^(2)和25 g/L高效氯氟氰菊酯乳油900 g a.i./hm^(2)对柴胡明蚜防效高,见效快,药后1 d防效为78.01%~90.54%;药后7 d防效为93.83%~98.89%。田间防效较好的药剂中,10%吡虫啉可湿性粉剂、25 g/L高效氯氟氰菊酯乳油对2种瓢虫相对安全,药剂高低浓度处理后2种瓢虫72 h校正死亡率为0.83%~41.28%。[结论]田间防治推荐优先施用10%吡虫啉和25 g/L高效氯氟氰菊酯防治柴胡明蚜,可结合其他药剂交替施用。
基金Project(92066205) supported by the National Natural Science Foundation of ChinaProject(JCKY61420052008)supported by the National Defense Science and Technology Key Laboratory Foundation,China+2 种基金Project(311021013)supported by Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai),ChinaProject(FRF-MP-20-52) supported by the Fundamental Research Funds for the Central Universities,ChinaProject(075-15-2021-612) support from the Government of the Russian Federation。
文摘The extruded plate of powder metallurgy AA2024 aluminum alloy was successfully solid-state joined by friction stir welding(FSW) to demonstrate potential applications in the aerospace and automotive industries. For determining the optimal processing parameters of FSW, the microstructure, mechanical properties, and fracture behavior of FSW joints were evaluated. When the processing parameters were optimized with 2000 r/min rotation speed and100 mm/min traverse speed, high quality welds were achieved. The ultimate tensile strength yield strength and elongation of the joint can reach 415 MPa(85% of the base metal strength), 282 MPa, and 9.5%, respectively. The hardness of the joint gradually decreased from the alloy matrix to the heat-affected zone. The lowest strength and hardness appeared near the heat-affected zone because of the over-aging caused by heat flow from repeated stirring during FSW. The average grain size of the stir zone(2.15 μm) was smaller than that of the base metal(4.43 μm) and the heat-affected zone(5.03 μm), whose grains had <110> preferred orientation.
基金supported by the National Natural Science Foundation of China (31272095)the National Key Research and Development Program of China (2017YFD0201004)the Hebei Modern Agriculture Industry Technology System, China (HBCT2018060204)
文摘In this study, the Harmonia axyridis vitellogenin gene 2 (HmVg2) sequence was identified from transcriptomic databases of female adult H. axyridis and cloned into pMD18-T vector. The HmVg2 gene was 5 460 bp in length, and formed with an open reading frame (ORF) of 5 361 nucleotides (GenBank accession no. KY794939). The putative molecular weight of the primary HmVg2 protein was 203.459 kDa and the predicted isoelectric point (pI) was 8.59. HmVg2 contained a signal peptide, vitellogenin N-terminal (vitellogenin-N) domain, domain of unknown function 1943 (DUF1934) domain and von Willebrand factor type D (VWD) domain. The developmental expression profiling showed that HmVg2 was extremely highly expressed in female insects, but was expressed at lower levels in male insects. In female insects, HmVg2 was mainly expressed in the wing and fat body. The double-stranded RNA-HmVg2/-GFP was injected into H. axyridis, and qRT-PCR results showed that the HmVg2 gene was specifically silenced. The eggs laid during the first five days and the hatching rate of eggs was lower than controls after dsHmVg2 injection. This investigation demonstrated that the HmVg2 gene plays an important role in H. axyridis reproduction and enriches the function of the insect vitellogenin gene.
