植物乳杆菌LP21 (Lactobacillus plantarum LP21)合成的纳米硒易黏附于菌体表面,不易分离提取.本研究在保持细胞结构完整的前提下,对附着在菌体上的纳米硒进行分散处理.通过单因素实验探究超声波、有机溶剂及表面活性剂对纳米硒分散的影...植物乳杆菌LP21 (Lactobacillus plantarum LP21)合成的纳米硒易黏附于菌体表面,不易分离提取.本研究在保持细胞结构完整的前提下,对附着在菌体上的纳米硒进行分散处理.通过单因素实验探究超声波、有机溶剂及表面活性剂对纳米硒分散的影响,进而采用正交试验确定最佳分散条件,最后利用蔗糖密度梯度离心与微孔滤膜过滤的方法对纳米硒进行分离纯化.单因素结果表明:超声波、有机溶剂及表面活性剂均有分散作用,其中表面活性剂SDS效果最好;采用正交方法确定的最适分散条件为加入2.5%SDS、1.5%正己醇,超声处理时间25 min;分离纯化采用50%、60%、70%蔗糖密度梯度离心后用0.22μm的水性微孔滤膜过滤,可得到纯净的纳米硒.纳米硒颗粒分布均匀,平均粒径为165.88±35.35 nm.本研究为微生物来源纳米硒的分离制备提供参考依据.展开更多
The Northeastern China cold vortex(NCCV)is one type of strong cyclonic vortex that occurs near Northeastern China(NEC),and NCCV activities are typically accompanied by a series of hazardous weather.This paper employed...The Northeastern China cold vortex(NCCV)is one type of strong cyclonic vortex that occurs near Northeastern China(NEC),and NCCV activities are typically accompanied by a series of hazardous weather.This paper employed an automatic algorithm to identify the NCCVs from 1979 to 2018 and analyzed their circulation patterns and climatic impacts by using the defined NCCV intensity index(NCCVI).The analysis revealed that the NCCV activities in summer exhibited a strong inter-annual variability,with an obvious periodicity of 3-4 years and 6-7 years,but without significant trends.In years when the NCCVI was high,NEC experienced negative geopotential height anomalies,cyclonic circulation,and cooler temperature anomalies,which were conducive to the maintenance and development of NCCV activities.Furthermore,large amounts of water vapor converged in NEC through two transportation routes as the NCCVs intensified,leading to a significant positive(negative)correlation with the summer precipitation(surface temperature)in NEC.The Atlantic sea surface temperature(SST)anomalies were closely related to summer NCCV activities.As the Atlantic SST rose,large amounts of surface sensible and latent heat flux were transported into the lower troposphere,inducing a positive geopotential height anomaly that occurred on the east side of the heat source.As a result,an eastward diverging flow was formed in the upper troposphere and propagated downstream,i.e.,the eastward propagating Rossby wave train,which eventually led to a coupled circulation in the Ural Mountains and NEC,as well as more intensive NCCV activities in summer.展开更多
基金National Natural Science Foundation of China(41975073,42274215)Wuxi University Research Start-up Fund for Introduced Talents (2023r037)+1 种基金Qinglan Project of Jiangsu Province for DING Liu-guan"333"Project of Jiangsu Province for DING Liu-guan
文摘The Northeastern China cold vortex(NCCV)is one type of strong cyclonic vortex that occurs near Northeastern China(NEC),and NCCV activities are typically accompanied by a series of hazardous weather.This paper employed an automatic algorithm to identify the NCCVs from 1979 to 2018 and analyzed their circulation patterns and climatic impacts by using the defined NCCV intensity index(NCCVI).The analysis revealed that the NCCV activities in summer exhibited a strong inter-annual variability,with an obvious periodicity of 3-4 years and 6-7 years,but without significant trends.In years when the NCCVI was high,NEC experienced negative geopotential height anomalies,cyclonic circulation,and cooler temperature anomalies,which were conducive to the maintenance and development of NCCV activities.Furthermore,large amounts of water vapor converged in NEC through two transportation routes as the NCCVs intensified,leading to a significant positive(negative)correlation with the summer precipitation(surface temperature)in NEC.The Atlantic sea surface temperature(SST)anomalies were closely related to summer NCCV activities.As the Atlantic SST rose,large amounts of surface sensible and latent heat flux were transported into the lower troposphere,inducing a positive geopotential height anomaly that occurred on the east side of the heat source.As a result,an eastward diverging flow was formed in the upper troposphere and propagated downstream,i.e.,the eastward propagating Rossby wave train,which eventually led to a coupled circulation in the Ural Mountains and NEC,as well as more intensive NCCV activities in summer.
