In light of the percentage of Earth’s cloud coverage, heterogeneous ice nucleation in clouds is the most important global-scale pathway. More recent parameterizations of ice nucleation processes in the atmosphere are...In light of the percentage of Earth’s cloud coverage, heterogeneous ice nucleation in clouds is the most important global-scale pathway. More recent parameterizations of ice nucleation processes in the atmosphere are based on the concept of ice nucleation active surface site density (<i><span style="font-family:Verdana;">n</span><sub><span style="font-family:Verdana;">s</span></sub></i><span style="font-family:Verdana;">). It is usually assumed that </span><i><span style="font-family:Verdana;">n</span><sub><span style="font-family:Verdana;">s</span></sub></i><span style="font-family:Verdana;"> is independent of time and aerosol size distribution, </span><i><span style="font-family:Verdana;">i.e.</span></i><span style="font-family:Verdana;"> that the surface properties of aerosols of the same species do not vary with size. However, the independence of </span><i><span style="font-family:Verdana;">n</span><sub><span style="font-family:Verdana;">s</span></sub></i><span style="font-family:Verdana;"> on aerosol size for every species has been questioned. This study presents the results of ice nucleation processes of ATD laboratory-generated aerosol (particle diameters of 0 - 3 μm). Ice nucleation in the condensation mode was performed in a Dynamic Filter Processing Cham- ber at temperatures of </span><span style="font-family:;" "=""><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">-</span></span><span style="font-family:Verdana;">18<span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">°</span>C and </span><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">-</span></span><span><span style="font-family:Verdana;">22<span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">°</span>C, with a saturation ratio with respect to water of 1.02. Results show that </span><i><span style="font-family:Verdana;">n</span><sub><span style="font-family:Verdana;">s</span></sub></i><span style="font-family:Verdana;"> increased by lowering the nucleation temperature, and was also dependent on the particle size. The </span><i><span style="font-family:Verdana;">n</span><sub><span style="font-family:Verdana;">s</span></sub></i><span style="font-family:Verdana;"> of particles collected on the filters, after a 0.5 μm D</span><sub><span style="font-family:Verdana;">50</span></sub><span style="font-family:Verdana;"> cut-off cyclone, resulted statistically higher with respect to the values obtained from the particles collected on total filters. The results obtained suggest the need for further investigation of </span><i><span style="font-family:Verdana;">n</span></i><sub><span style="font-family:Verdana;">s</span></sub><span style="font-family:Verdana;"> dependence of same composition aerosol particles with a view to support weather and climate predictions.</span></span></span>展开更多
Ice core provides a valuable vertical timeline of past climates and anthropogenic activities.Environmental proxies have been widely used in these studies,but there are few biological indicators available.To address th...Ice core provides a valuable vertical timeline of past climates and anthropogenic activities.Environmental proxies have been widely used in these studies,but there are few biological indicators available.To address this gap,we investigated the bacterial community from a 74 m ice core of Muztag ata glacier on the Tibetan Plateau to link biological indicators with past climate and anthropogenic activities.By analyzing the portion of the ice core with environmental proxies available(corresponding to 1907 to 1991),we observed an increase in bacterial richness throughout the ice core,which was associated with higher NH_(4)^(+),an indicator of agricultural development.The bacterial community was jointly determined by human activity,natural input,and air temperature,with a strong human influence after the 1950s.Furthermore,the relative abundance of animal gut-associated bacteria,including Aerococcaceae,Nocardiaceae,Muribaculaceae,and Lachnospiraceae,was associated with livestock number changes in the Central Asian region.Together with other bacterial lineages,they jointly explained 59.8%of the livestock number changes.This study provides quantitative evidence of the associations between bacterial indicators and past climate and human activities,highlighting the potential of using bacterial proxies for ice core studies.展开更多
Effects of low temperature and INA bacteria on the change of chlorophyll a fluorescence in young fruit from two apricot cultivars were investigated. Low temperature decreased the potential activity (Fv/ Fo), conversio...Effects of low temperature and INA bacteria on the change of chlorophyll a fluorescence in young fruit from two apricot cultivars were investigated. Low temperature decreased the potential activity (Fv/ Fo), conversion efficiency of primary light energy (Fv/Fm)of PS II and photochemical quenching (qP) in young fruit of two apricot cultivars. Low temperature enhanced non-photochemical quenching qN, decreasing the quantum yield of photosynthetic electron transfer. The presence of ice nucleating active (INA) bacteria intensified the effects of low temperature, raised the injury temperature threshold from - 4℃ to - 2 - - 3℃. INA bacteria can be a factor to induce frost susceptibility of apricot fruit. The amount of damaged PS I activity center was related to apricot fruit size and cultivar.展开更多
从茶树内生菌中进行了冰核细菌拮抗菌的筛选,得到菌株Y1,通过对菌株Y1进行形态学观察、生理生化指标测定及16 S r DNA序列测定和序列同源性分析,将菌株Y1鉴定为解淀粉芽孢杆菌(Bacillus amyloliquefaciens)。本研究获得了茶树内生拮抗菌...从茶树内生菌中进行了冰核细菌拮抗菌的筛选,得到菌株Y1,通过对菌株Y1进行形态学观察、生理生化指标测定及16 S r DNA序列测定和序列同源性分析,将菌株Y1鉴定为解淀粉芽孢杆菌(Bacillus amyloliquefaciens)。本研究获得了茶树内生拮抗菌株,明确了菌株Y1的种属,有利于冰核细菌生物防治的开展。展开更多
文摘In light of the percentage of Earth’s cloud coverage, heterogeneous ice nucleation in clouds is the most important global-scale pathway. More recent parameterizations of ice nucleation processes in the atmosphere are based on the concept of ice nucleation active surface site density (<i><span style="font-family:Verdana;">n</span><sub><span style="font-family:Verdana;">s</span></sub></i><span style="font-family:Verdana;">). It is usually assumed that </span><i><span style="font-family:Verdana;">n</span><sub><span style="font-family:Verdana;">s</span></sub></i><span style="font-family:Verdana;"> is independent of time and aerosol size distribution, </span><i><span style="font-family:Verdana;">i.e.</span></i><span style="font-family:Verdana;"> that the surface properties of aerosols of the same species do not vary with size. However, the independence of </span><i><span style="font-family:Verdana;">n</span><sub><span style="font-family:Verdana;">s</span></sub></i><span style="font-family:Verdana;"> on aerosol size for every species has been questioned. This study presents the results of ice nucleation processes of ATD laboratory-generated aerosol (particle diameters of 0 - 3 μm). Ice nucleation in the condensation mode was performed in a Dynamic Filter Processing Cham- ber at temperatures of </span><span style="font-family:;" "=""><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">-</span></span><span style="font-family:Verdana;">18<span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">°</span>C and </span><span style="font-family:Verdana;"><span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">-</span></span><span><span style="font-family:Verdana;">22<span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">°</span>C, with a saturation ratio with respect to water of 1.02. Results show that </span><i><span style="font-family:Verdana;">n</span><sub><span style="font-family:Verdana;">s</span></sub></i><span style="font-family:Verdana;"> increased by lowering the nucleation temperature, and was also dependent on the particle size. The </span><i><span style="font-family:Verdana;">n</span><sub><span style="font-family:Verdana;">s</span></sub></i><span style="font-family:Verdana;"> of particles collected on the filters, after a 0.5 μm D</span><sub><span style="font-family:Verdana;">50</span></sub><span style="font-family:Verdana;"> cut-off cyclone, resulted statistically higher with respect to the values obtained from the particles collected on total filters. The results obtained suggest the need for further investigation of </span><i><span style="font-family:Verdana;">n</span></i><sub><span style="font-family:Verdana;">s</span></sub><span style="font-family:Verdana;"> dependence of same composition aerosol particles with a view to support weather and climate predictions.</span></span></span>
基金supported by the National Key Research and Development Plans(Grant No.2021YFC2300904)the National Natural Science Foundation of China(Grant Nos.U21A20176 and 42330410)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant No.2019QZKK0503)。
文摘Ice core provides a valuable vertical timeline of past climates and anthropogenic activities.Environmental proxies have been widely used in these studies,but there are few biological indicators available.To address this gap,we investigated the bacterial community from a 74 m ice core of Muztag ata glacier on the Tibetan Plateau to link biological indicators with past climate and anthropogenic activities.By analyzing the portion of the ice core with environmental proxies available(corresponding to 1907 to 1991),we observed an increase in bacterial richness throughout the ice core,which was associated with higher NH_(4)^(+),an indicator of agricultural development.The bacterial community was jointly determined by human activity,natural input,and air temperature,with a strong human influence after the 1950s.Furthermore,the relative abundance of animal gut-associated bacteria,including Aerococcaceae,Nocardiaceae,Muribaculaceae,and Lachnospiraceae,was associated with livestock number changes in the Central Asian region.Together with other bacterial lineages,they jointly explained 59.8%of the livestock number changes.This study provides quantitative evidence of the associations between bacterial indicators and past climate and human activities,highlighting the potential of using bacterial proxies for ice core studies.
文摘Effects of low temperature and INA bacteria on the change of chlorophyll a fluorescence in young fruit from two apricot cultivars were investigated. Low temperature decreased the potential activity (Fv/ Fo), conversion efficiency of primary light energy (Fv/Fm)of PS II and photochemical quenching (qP) in young fruit of two apricot cultivars. Low temperature enhanced non-photochemical quenching qN, decreasing the quantum yield of photosynthetic electron transfer. The presence of ice nucleating active (INA) bacteria intensified the effects of low temperature, raised the injury temperature threshold from - 4℃ to - 2 - - 3℃. INA bacteria can be a factor to induce frost susceptibility of apricot fruit. The amount of damaged PS I activity center was related to apricot fruit size and cultivar.
文摘从茶树内生菌中进行了冰核细菌拮抗菌的筛选,得到菌株Y1,通过对菌株Y1进行形态学观察、生理生化指标测定及16 S r DNA序列测定和序列同源性分析,将菌株Y1鉴定为解淀粉芽孢杆菌(Bacillus amyloliquefaciens)。本研究获得了茶树内生拮抗菌株,明确了菌株Y1的种属,有利于冰核细菌生物防治的开展。