油菜对Sr胁迫的生理生态响应

在砂培条件下,采用不同浓度的Sr2+ (0、05、1、5、10 mmol/L)对转pprI基因油菜幼苗(Brassica napus L.)和非转基因油菜幼苗处理30 d,分析油菜幼苗对Sr的吸收积累情况,并研究油菜对Sr胁迫的生理生态响应。结果表明:转基因油菜幼苗和非转基因油菜幼苗对Sr2+的吸收量均随Sr2+胁迫浓度的升高而升高,转基因油菜根部的Sr2+含量大于非转基因油菜根部,而地上部分的Sr2+含量却小于非转基因油菜。与对照相比,在Sr2+胁迫下的转基因油菜和非转基因油菜脯氨酸(Pro)含量则随Sr2+浓度的提高而升高,而SOD、POD活性和叶绿素含量都随Sr2+浓度的增加呈先上升后下降趋势。与非转基因油菜相比,转基因油菜在各种胁迫浓度下的SOD、POD活性、叶绿素含量以及脯氨酸含量都高于非转基因油菜。因此得出结论:转pprI基因油菜较非转基因油菜更具有对Sr胁迫的抗性和耐受能力。

Performance evaluation from stochastic statecharts representation of flexible reactive systems:a simulation approach

This paper focuses on the performance analysis of flexible reactive systems. The performance analysis consists of two phases： first system modeling, second performance evalua-tion. The paper models the flexible reactive system by the stochas-tic statecharts method, and uses the simulation method to evalu-ate the performance. To make use of the feature of event-triggered state transitions in the statecharts, a new method of simulation is proposed based on the techniques of the discrete-event system simulation. The new method solves the problem of computer imple-mentation of stochastic events, probabilistic transition, concurrent states, paral el actions, and broadcast communication mechanism in the stochastic statecharts. An example of a flexible manufactur-ing system is presented. The simulation result of the example is consistent with the analytical result, which shows the feasibility of the proposed new simulation method.

Numerical Modeling of a New Flight Simulator Enabling Continuous 360⁃Degree Spinning and Translational Motion

This paper presents a new nine⁃degree⁃of⁃freedom parallel mechanism,which can be applied as a flight simulator.The mechanism is composed by Stewart turntable and another three⁃axis turntable.The Stewart platform can realize six⁃degree⁃of⁃freedom movement in space,but the working space is limited.After the three⁃axis turntable is installed,the rotation space can be increased to simulate more realistic flight conditions.This paper analyzes the new flight simulator from kinematics and dynamics aspects.In addition,the flight simulator is simulated and analyzed based on the MATLAB/Simulink simulation system.The results obtained from the numerical simulations is planned to be used for the practical manufacturing and applications of the new platform.

共价有机框架材料作为金属离子电池正极材料

共价有机框架材料(Covalent organic frameworks,COFs)是一种具有周期性二维或三维网状结构的多孔有机材料,其结构由两种或更多有机分子通过共价键连接而成。COFs具有骨架密度低、比表面积大、孔隙率高、结构可设计性和功能可修饰性等特点,在储能领域展现出巨大的潜力。由于其丰富的氧化还原活性位点和开放的框架结构,COFs作为金属离子电池正极材料有着独特的优势。然而COFs导电性差、能量密度低、可用的活性位点较少和离子传输通道的阻塞等缺陷限制了其在储能领域的应用。本文系统综述了COFs作为金属离子电池正极材料的最新研究现状,包括对COFs的种类、合成方法以及设计策略进行总结,从不同活性基团的角度对其电化学储能机理进行概述,并介绍了COFs在不同金属离子电池方面的应用。最后总结和展望了COFs在储能领域应用的前景和挑战。

Interfacial engineering of atomic platinum-doped molybdenum carbide quantum dots for high-rate and stable hydrogen evolution reaction in proton exchange membrane water electrolysis

Platinum(Pt)-based electrocatalysts remain the only practical cathode catalysts for proton exchange membrane water electrolysis(PEMWE),due to their excellent catalytic activity for acidic hydrogen evolution reaction(HER),but are greatly limited by their low reserves and high cost.Here,we report an interfacial engineering strategy to obtain a promising low-Pt loading catalyst with atomically Pt-doped molybdenum carbide quantum dots decorated on conductive porous carbon(Pt-MoCx@C)for high-rate and stable HER in PEMWE.Benefiting from the strong interfacial interaction between Pt atoms and the ultra-small MoCx quantum dots substrate,the Pt-MoCx catalyst exhibits a high mass activity of 8.00 A·mgPt−1,5.6 times higher than that of commercial 20 wt.%Pt/C catalyst.Moreover,the strong interfacial coupling of Pt and MoCx substrate greatly improves the HER stability of the Pt-MoCx catalyst.Density functional theory studies further confirm the strong metal-support interaction on Pt-MoCx,the critical role of MoCx substrate in the stabilization of surface Pt atoms,as well as activation of MoCx substrate by Pt atoms for improving HER durability and activity.The optimized Pt-MoCx@C catalyst demonstrates>2000 h stability under a water-splitting current of 1000 mA·cm^(−2)when applied to the cathode of a PEM water electrolyzer,suggesting the potential for practical applications.

In vivo target protein degradation induced by PROTACs based on E3 ligase DCAF15

Dear Editor,As an emerging drug discovery paradigm,Proteolysis targeting chimeras(PROTACs)facilitate ubiquitination and degradation of the targets by cellular endogenous proteasome system.Compared with traditional small molecular inhibitors,PROTACs work like enzymes and can operate with or without functional inhibition of the targets,which endows this strategy to degrade drug targets,especially useful for“undruggable”ones.