Layered buserite Mg-Mn oxide cathode for aqueous rechargeable Mg-ion battery

Owing to the features(high safety,inexpensive and environmental friendliness)of aqueous rechargeable Mg-ion batteries(ARMIBs),they have drawn extensive attention in the future energy storage systems.However,the poor Mg^(2+)migration kinetics during the Mg^(2+)intercalation/extraction still hinders the progress of developing suitable cathode materials.Herein,a layered buserite Mg-Mn oxide(MMO)material with large interlayer space(~9.70A)and low-crystalline structure is studied as a high-performance cathode in ARMIBs.Compared with the counterpart,the Mg^(2+)migration kinetics of the MMO cathode can be enhanced by its unique structure(bigger interlayer spacing and low-crystalline structure).The layered buserite MMO as a high-performance ARMIBs cathode exhibits high Mg storage capacity(50 mAg^(-1):169.3 mAh g^(-1)),excellent rate capability(1000 mAg^(-1):98.3 mAh g^(-1)),and fast Mg^(2+)migration(an average diffusion coefficient:~4.21×10-^(10)cm^(2)s^(-1))in 0.5 M MgCl_(2)aqueous electrolyte.Moreover,the MMO-1//AC full battery achieved a high discharge capacity(100 mAg^(-1):111 mAh g^(-1)),and an ignored fading over 5000 cycles(1000 mAg^(-1)).Therefore,layered Mg-Mn oxide with large interlayer space may break a new path to develop the promising ARMIBs.

利用次序截尾数据线性回归方法推断正态总体的未知参数

统计学中,在采用抽样分析的方法进行参数估计与推断时,常要求样本数据数量、完整性好,且须满足随机抽取等特点。在实际应用中会遇到一系列按顺序排列的截尾样本数据,用普通的参数估计方法得到的参数估计值误差可能会较大,本文将回归分析方法推广到利用次序截尾数据推断正态总体参数中,且对所做结果进行模拟计算。通过误差比对,认为该方法是可行的,本文最后利用该方法通过部分排序的学生成绩推断了总体的平均成绩。

Dynamic Risk-Warning of Center Diaphragm and Bench Composite Method During Construction

During the construction of subway tunnels,safety issues should not be ignored,so it is necessary to prevent and resolve the risk in time and accurately.However,there are some shortcomings in the research of risk assessment,such as the subjectivity of initial data or the lack of scientific evaluation model,in order to solve the problem,this paper relies on the Changping section of the Guanhui Intercity Metro,in order to establish a dynamic risk-warn-ing model for the construction process of subway tunnel with the CD-Bench composite method.First,a monitor-ing plan was equationted according to the specification requirements and the actual situation of the project,and based on this,an evaluation index system was established from five aspects:geological and support conditions,crown settlement,clearance convergence,and ground settlement and building settlement.Secondly,according to the established risk evaluation standards,the risk level of the index is determined by introducing extension theory and determining the combined weight of the index based on the distance function.Finally,feedback the corresponding risk-warning signals and take control measures.Through the application analysis shows that the model can alarm the risks during the tunnel construction process directly and timely,so the model is feasible and practical,and it is worthy of popularization and application in similar projects.

基于三元自我角色视角的职业生涯建构理论述评

在VUCA时代背景下,强调生涯适应的职业生涯建构理论对于指导个体的职业生涯显得尤为重要,更具时代价值。该理论使用三元自我角色——角色扮演者、主动追求者、自传写作者来理解个体的职业生涯建构,但最初对于该理论的实证研究和理论探讨都只侧重于对主动追求者的职业生涯适应过程这一模块进行探讨。本文通过对该理论相关研究的梳理,发现近年来研究者们加强了对三元自我角色在工作场所、职业生涯管理、生活设计干预等领域的应用和探讨,关于该理论的研究在研究内容、研究视角和研究方法上都得到了丰富。最后,本文从拓展依恋图式在职业生涯建构情境中的研究、加强职业角色扮演的跨文化研究、探索适应链的因果顺序、注重对特殊群体的职业生涯建构干预研究,以及该理论在组织管理领域和职业生涯教育领域中的应用六个方面对未来研究方向进行了展望。

Dynamic nano-Ag colloids cytotoxicity to and accumulation by Escherichia coli:Effects of Fe^3+,ionic strength and humic acid

Released Ag ions or/and Ag particles are believed to contribute to the cytotoxicity of Ag nanomaterials,and thus,the cytotoxicity and mechanism of Ag nanomaterials should be dynamic in water due to unfixed Ag particle:Ag+ ratios.Our recent research found that the cytotoxicity of PVP-Ag nanoparticles is attributable to Ag particles alone in 3 hr bioassays,and shifts to both Ag particles and released Ag^+ in 48 hr bioassays.Herein,as a continued study,the cytotoxicity and accumulation of 50 and 100 nm Ag colloids in Escherichia coli were determined dynamically.The cytotoxicity and mechanisms of nanoAg colloids are dynamic throughout exposure and are derived from both Ag ions and particles.Ag accumulation by E.coli is derived mainly from extracellular Ag particles during the initial 12 hr of exposure,and thereafter mainly from intracellular Ag ions.Fe^3+ accelerates the oxidative dissolution of nano-Ag colloids,which results In decreasing amounts of Ag particles and particle-related toxicity.Na^+ stabilizes nano-Ag colloids,thereby decreasing the bioavailability of Ag particles and particle-related toxicity.Humic acid(HA) binds Ag^+ to form Ag^+-HA,decreasing ion-related toxicity and binding to the E.coli surface,decreasing particle-related toxicity.HA in complex conditions showed a stronger relative contribution to toxicity and accumulation than Na^+ or Fe^3+.The results highlighted the cytotoxicity and mechanism of nano-Ag colloids are dynamic and affected by environmental factors,and therefore exposure duration and water chemistry should be seriously considered in environmental and health risk assessments.

A Sixth-Order Parabolic System in Semiconductors

The authors investigate the global existence and semiclassical limit of weak solutions to a sixth-order parabolic system,which is a quantum-corrected macroscopic model derived recently to simulate the quantum effects in miniaturized semiconductor devices.