Organic acid content is one of the most important factors influencing fruit flavors.The predominant organic acid in most pear cultivars is malic acid,but the mechanism controlling its accumulation remains unclear.In t...Organic acid content is one of the most important factors influencing fruit flavors.The predominant organic acid in most pear cultivars is malic acid,but the mechanism controlling its accumulation remains unclear.In this study,by comparing gene expression levels and organic acid contents,we found that the expression of PbPH5,which encodes a P_(3A)-ATPase,is highly correlated with malic acid accumulation in four different pear species,with correlation coefficients of 0.932**,0.656*,0.900**,and 0.518*(*,P<0.05;**,P<0.01)for Pyrus bretschneideri Rehd.,P.communis Linn.,P.pyrifolia Nakai.,and P.ussuriensis Maxim.,respectively.Moreover,the overexpression of PbPH5 in pear significantly increased the malic acid content.In contrast,silencing PbPH5 via RNA interference significantly decreased both its transcript level and the pear fruit malic acid content.A subcellular localization analysis indicated that PbPH5 is located in the tonoplast.Additionally,a phylogenetic analysis indicated that PbPH5 is a PH5 homolog gene that is clustered with the Petunia hybrida,Malus domestica,and Citrus reticulata genes.Considered together,these findings suggest that PbPH5 is a functionally conserved gene.Furthermore,the accumulation of malic acid in pear fruit is at least partly related to changes in the PbPH5 transcription levels.展开更多
目的针对15-5PH钢零件再制造后性能调控缺乏试验和数据支撑的问题,研究热处理温度对15-5PH熔覆层微观组织及力学性能的影响。方法利用冷金属过渡(Cold Metal Transfer,CMT)工艺制备了连续、平整、无宏观缺陷的熔覆层,并采用不同温度对...目的针对15-5PH钢零件再制造后性能调控缺乏试验和数据支撑的问题,研究热处理温度对15-5PH熔覆层微观组织及力学性能的影响。方法利用冷金属过渡(Cold Metal Transfer,CMT)工艺制备了连续、平整、无宏观缺陷的熔覆层,并采用不同温度对熔覆层进行了热处理。利用光学显微镜、XRD、SEM和EDS等手段分析了熔覆层的微观组织、物相组成,通过拉伸试验、剪切试验测试了熔覆层力学性能。结果焊态熔覆层主要由马氏体、铁素体、球状碳化物构成,不同区域的马氏体、铁素体形态有显著差异。随热处理温度的升高,焊道中间区域微观组织差异逐渐减小,尺寸有增加的趋势,经580℃、620℃热处理后,马氏体晶界上生成白色块状逆转变奥氏体,而且逆转变奥氏体含量和尺寸随温度的升高逐渐增加。此外,经450℃热处理后,熔覆层的屈服强度、抗拉强度、剪切强度达到最高,分别为1251、1318、674.9 MPa,伸长率仅为3.6%;当温度高于450℃时,随温度的升高,屈服强度、抗拉强度、剪切强度逐渐降低,伸长率增加。结论探明了热处理温度对再制造15-5PH熔覆层组织和性能的影响规律,为再制造15-5PH零件的热处理提供了依据。展开更多
The global climate change and ocean acidification brought about by the anthropogenic release of carbon dioxide gas into the air is considered one of the greatest problems facing marine life.In this research,the intera...The global climate change and ocean acidification brought about by the anthropogenic release of carbon dioxide gas into the air is considered one of the greatest problems facing marine life.In this research,the interactions between two species of fish(the gold mollies and tiger barb)were investigated under two different environmental conditions,an elevated temperature of 28℃ and a low pH of 5 and a normal pH of 7 and a normal temperature of 24℃.The mollies at pH 7 and a temperature of 24℃ exhibited scary interactions with the tiger barb.They were scared and ran fast away from the tiger barb.At the same time,the mollies at pH 5 and a temperature of 28℃ interacted normally as though both species were one species showing behavioral changes due to these two stressors(pH 5 and elevated temperature 28℃).This could be the only research that has addressed how the kinematics and swimming interactions of two species of fish changed in response to elevated temperature and low pH.展开更多
基金funded by the National Key Research and Development Program of China (2019YFD1001400)the National Natural Science Foundation of China (31601715)
文摘Organic acid content is one of the most important factors influencing fruit flavors.The predominant organic acid in most pear cultivars is malic acid,but the mechanism controlling its accumulation remains unclear.In this study,by comparing gene expression levels and organic acid contents,we found that the expression of PbPH5,which encodes a P_(3A)-ATPase,is highly correlated with malic acid accumulation in four different pear species,with correlation coefficients of 0.932**,0.656*,0.900**,and 0.518*(*,P<0.05;**,P<0.01)for Pyrus bretschneideri Rehd.,P.communis Linn.,P.pyrifolia Nakai.,and P.ussuriensis Maxim.,respectively.Moreover,the overexpression of PbPH5 in pear significantly increased the malic acid content.In contrast,silencing PbPH5 via RNA interference significantly decreased both its transcript level and the pear fruit malic acid content.A subcellular localization analysis indicated that PbPH5 is located in the tonoplast.Additionally,a phylogenetic analysis indicated that PbPH5 is a PH5 homolog gene that is clustered with the Petunia hybrida,Malus domestica,and Citrus reticulata genes.Considered together,these findings suggest that PbPH5 is a functionally conserved gene.Furthermore,the accumulation of malic acid in pear fruit is at least partly related to changes in the PbPH5 transcription levels.
文摘目的针对15-5PH钢零件再制造后性能调控缺乏试验和数据支撑的问题,研究热处理温度对15-5PH熔覆层微观组织及力学性能的影响。方法利用冷金属过渡(Cold Metal Transfer,CMT)工艺制备了连续、平整、无宏观缺陷的熔覆层,并采用不同温度对熔覆层进行了热处理。利用光学显微镜、XRD、SEM和EDS等手段分析了熔覆层的微观组织、物相组成,通过拉伸试验、剪切试验测试了熔覆层力学性能。结果焊态熔覆层主要由马氏体、铁素体、球状碳化物构成,不同区域的马氏体、铁素体形态有显著差异。随热处理温度的升高,焊道中间区域微观组织差异逐渐减小,尺寸有增加的趋势,经580℃、620℃热处理后,马氏体晶界上生成白色块状逆转变奥氏体,而且逆转变奥氏体含量和尺寸随温度的升高逐渐增加。此外,经450℃热处理后,熔覆层的屈服强度、抗拉强度、剪切强度达到最高,分别为1251、1318、674.9 MPa,伸长率仅为3.6%;当温度高于450℃时,随温度的升高,屈服强度、抗拉强度、剪切强度逐渐降低,伸长率增加。结论探明了热处理温度对再制造15-5PH熔覆层组织和性能的影响规律,为再制造15-5PH零件的热处理提供了依据。
文摘The global climate change and ocean acidification brought about by the anthropogenic release of carbon dioxide gas into the air is considered one of the greatest problems facing marine life.In this research,the interactions between two species of fish(the gold mollies and tiger barb)were investigated under two different environmental conditions,an elevated temperature of 28℃ and a low pH of 5 and a normal pH of 7 and a normal temperature of 24℃.The mollies at pH 7 and a temperature of 24℃ exhibited scary interactions with the tiger barb.They were scared and ran fast away from the tiger barb.At the same time,the mollies at pH 5 and a temperature of 28℃ interacted normally as though both species were one species showing behavioral changes due to these two stressors(pH 5 and elevated temperature 28℃).This could be the only research that has addressed how the kinematics and swimming interactions of two species of fish changed in response to elevated temperature and low pH.
