基于XGBoost的冷水机组不平衡数据故障诊断

The chiller operating data has unbalanced,non-Gaussian,non-linear,noise-containing characteristics,which poses a challenge for data-based chiller fault diagnosis.Aiming at these characteristics,a chiller fault diagnosis method based on Minority Oversampling under Local Area Density and e Xtreme Gradient Boosting is proposed to chiller fault diagnosis to overcome sample distribution imbalance.Introduce cost-sensitive learning theory to increase the recall rate of important faults.The simulations of seven fault monitoring data commonly used in centrifugal chillers show that XGBoost can better classify chiller status monitoring data compared to the control group.The MOLAD-XGBoost composite model can effectively deal with data imbalance problems; Cost sensitive weights can effectively increase the recall rate for critical failures

基于转录组数据揭示4种兜兰的全基因组复制历史

多倍化或全基因组复制(WGD)是物种多样性发生的重要驱动力。目前,在蕨类、菊科以及豆科等类群丰富的植物中已多次报道全基因组复制事件,而兰科(Orchidaceae)全基因组复制事件报道极少,与其丰富的物种多样性存在矛盾,推测与前期样本量小但类群跨度大的研究策略有关。选取染色体数目变异丰富且多样性较高的兜兰属(Paphiopedilum)为兰科植物代表类群,基于共享数据库中4种兜兰的转录组数据,采用同义替换率(Ks)、系统发生基因组学以及相对定年的方法分析兜兰属植物是否发生过全基因组复制事件。结果表明,在4种兜兰中均检测到3次全基因组复制事件,分别发生在110.17–119.77 Mya (WGD1)、60.95–74.19 Mya (WGD2)和38.19–45.85 Mya (WGD3)。其中, WGD3为新检测到的全基因组复制事件,推测其发生在杓兰亚科(Cypripedioideae)与姐妹类群分化后,兜兰属与姐妹类群分化之前。此外,3次全基因组复制事件发生后优先保留的基因拷贝在功能上多与当时的环境胁迫响应相关,推测全基因组复制提高了兜兰属植物祖先对当时极端环境变化的适应性

Recent Advances in Nanofluidic Electrochemistry for Biochemical Analysis

纳流控作为一个崭新的研究领域正受到越来越多的关注，并且已被成功应用到纳米尺度分离、生化传感、能量转化等诸多领域. 纳流控的发展与电化学紧密相连，一方面，电化学可以为纳米孔道中的物质传输特性的研究提供驱动力；另一方面，纳米孔道可以为限域电化学研究提供微环境. 纳流控和电化学技术相辅相成，催生了许多单分子、单粒子分析以及纳米流体操控的新理念与新技术. 本综述从纳米孔道与电极的结合方式出发，对纳流控-电化学相关研究进行了总结与展望.Nanofluidics, as a young research field, has been receiving more and more attentions. It has been successfully applied in various fields including nanoscale separation, biochemical sensing and energy conversion. The development of nanofluidics is closely related to electrochemistry that can provide a driving force for the study of the material transport characteristics in nanopores/nanochannels. On the other hand, nanopores/nanochannels can creat a microenvironment for study of spatially nanoconfined electrochemistry. The combination of nanofluidics and electrochemistry has given rise to many new theories and technologies for single molecule/particle analysis and nanofluid manipulation. Herein, we provide a review of the recent progresses in nanofluidic electrochemistry based on the combination of nanopore and electrode, and finally give a brief outlook on this field.  国家重点研发计划项目（No. 2017YFA0700500）、国家自然科学基金项目（No. 21635004, No. 21775066）资助作者联系地址：南京大学生命分析化学国家重点实验室，南京大学化学化工学院，江苏 南京 210023Author's Address: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China通讯作者E-mail：[email protected]