采用Gleeble-3800热模拟试验机对Ti60钛合金进行了热压缩实验,研究该合金在变形温度800~1150℃和应变速率0.001~1 s^(-1)区间内的热变形行为。结果表明:变形温度和应变速率是决定Ti60钛合金流变应力大小的主要因素,随变形温度升高,应变...采用Gleeble-3800热模拟试验机对Ti60钛合金进行了热压缩实验,研究该合金在变形温度800~1150℃和应变速率0.001~1 s^(-1)区间内的热变形行为。结果表明:变形温度和应变速率是决定Ti60钛合金流变应力大小的主要因素,随变形温度升高,应变速率降低,流变应力减小,表现出较强的温度敏感性和应变速率敏感性;随应变增大,合金的流变应力达到最大值,之后趋于平稳,呈现出流变软化特征。采用双曲正弦模型确定合金在800~900℃、950~1020℃和1050~1150℃的变形激活能分别为545.82、732.78和116.19 k J·mol^(-1),进而建立了合金在不同温度区间变形的本构方程,为制定和优化最佳形变加工工艺提供了理论依据。展开更多
Male sterility induced by a chemical hybridization agent （CHA） is an important tool for utilizing crop heterosis. Leaves, especially the flag leaves, as CHA initial recipients play a decisive role in inducing male s...Male sterility induced by a chemical hybridization agent （CHA） is an important tool for utilizing crop heterosis. Leaves, especially the flag leaves, as CHA initial recipients play a decisive role in inducing male sterility. To investigate effects of different treatment times of CHA-SQ-1 used, morphological, biochemical and physiological responses of wheat flag leaves were detected in thistudy. CHA induced programmed cell death （PCD） as shown in terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling （TUNEL） and DNA laddering analysis. In the early phase, CHA-SQ-1 trig- gered organelle changes arid PCD in wheat leaves accompanied by excess production of reactive oxygen species （O2- and H202） and down-regulation of the activities of superoxide dismutase （SOD）, catalase （CAT） and guaiacol peroxidase （POD）. Meanwhile, leaf cell DNAs showed ladder-like patterns on agarose gel, indicating that CHA-SQ-1 led to the activation of the responsible endonuclease. The oxidative stress assays showed that lipid peroxidation was strongly activated and photosynthesis was obviously inhibited in SQ-l-induced leaves. However, CHA contents in wheat leaves gradually reduced along with the time CHA-SQ-1 applied. Young flags returned to an oxidative/antioxidative balance and ultimately developed into mature green leaves. These results provide explanation of the relations between PCD and anther abortion and practical application of CHA for hybrid breeding.展开更多
文摘采用Gleeble-3800热模拟试验机对Ti60钛合金进行了热压缩实验,研究该合金在变形温度800~1150℃和应变速率0.001~1 s^(-1)区间内的热变形行为。结果表明:变形温度和应变速率是决定Ti60钛合金流变应力大小的主要因素,随变形温度升高,应变速率降低,流变应力减小,表现出较强的温度敏感性和应变速率敏感性;随应变增大,合金的流变应力达到最大值,之后趋于平稳,呈现出流变软化特征。采用双曲正弦模型确定合金在800~900℃、950~1020℃和1050~1150℃的变形激活能分别为545.82、732.78和116.19 k J·mol^(-1),进而建立了合金在不同温度区间变形的本构方程,为制定和优化最佳形变加工工艺提供了理论依据。
基金supported by the National High Technology Research and Development Program of China (2011AA10A106)the National Natural Science Foundation of China (31171611, 31371697)+1 种基金the Technological Innovation and Over Planning Projects of Shaanxi Province, China (2014KTZB02-01-02, 2011KTZB02-01-01)the Projects Opening Up New Function of Precision Instrument of Northwest A&F University, China (dysb130210)
文摘Male sterility induced by a chemical hybridization agent （CHA） is an important tool for utilizing crop heterosis. Leaves, especially the flag leaves, as CHA initial recipients play a decisive role in inducing male sterility. To investigate effects of different treatment times of CHA-SQ-1 used, morphological, biochemical and physiological responses of wheat flag leaves were detected in thistudy. CHA induced programmed cell death （PCD） as shown in terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling （TUNEL） and DNA laddering analysis. In the early phase, CHA-SQ-1 trig- gered organelle changes arid PCD in wheat leaves accompanied by excess production of reactive oxygen species （O2- and H202） and down-regulation of the activities of superoxide dismutase （SOD）, catalase （CAT） and guaiacol peroxidase （POD）. Meanwhile, leaf cell DNAs showed ladder-like patterns on agarose gel, indicating that CHA-SQ-1 led to the activation of the responsible endonuclease. The oxidative stress assays showed that lipid peroxidation was strongly activated and photosynthesis was obviously inhibited in SQ-l-induced leaves. However, CHA contents in wheat leaves gradually reduced along with the time CHA-SQ-1 applied. Young flags returned to an oxidative/antioxidative balance and ultimately developed into mature green leaves. These results provide explanation of the relations between PCD and anther abortion and practical application of CHA for hybrid breeding.
