Self‐Assembled Sugar‐Substituted Perylene Diimide Nanostructures with Homochirality and High Gas Sensitivity

A new symmetrical sugar‐based perylenediimide derivative PTCDI‐BAG is synthesized and its aggregate morphologies and formation mechanisms are studied in detail in the mixed solvent system water/N,N‐dimethylformamide (H₂O/DMF) with changing volume ratios. PTCDI‐BAG molecules self‐assemble into planar ribbons in 20/80 and 40/60 H₂O/DMF (v/v), but their chiralities are opposite according to recorded circular dichroism (CD) spectra. With a further increase of the water content, only left‐handed helical nanowires are obtained in 60/40 and 80/20 H₂O/DMF (v/v) mixtures. By combining density functional theory (DFT) calculations with the experimental investigations, it is proposed that kinetic and thermodynamic factors play key roles in tuning PTCDI‐BAG structures and helicity. The formation of the ribbon is thermodynamically controlled in the 20/80 H₂O/DMF system, but kinetically controlled nucleation followed by thermodynamically controlled self‐assembly plays the governing roles for the formation of nanoribbons in 40/60 H₂O/DMF. Devices based on single nanoribbons for hydrazine sensing exhibit better performance than nanofiber bundles obtained in this study and achiral nanostructures reported in previous study. This study not only provides an elaborated route to tuning the structures and helicity of PTCDI molecules, but also provides new possibilities for the construction of high‐performance nanodevices.     

Microstructure evolution and corrosion resistance in simulated CGHAZ of X80 high-deformability pipeline steel

In this study, the microstructure evolution and corrosion resistance in 0.5M Na₂CO₃-1 M NaHCO₃ solution of X80 high-deformability (X80HD) pipeline steel coarse-grained heat-affected zone (CGHAZ) with several heat input levels were investigated. It is shown that the microstructure of CGHAZ changes from bainite ferrite to granular bainite as the heat input increasing. In addition, the corrosion resistance and the stability of passive film of base material are better than those of CGHAZ with several heat input levels. Too small or too big heat input is inadvisable and better corrosion resistance of CGHAZ is attained when heat input is 30kJ/cm.     

混合动力电动汽车驱动系统设计与实现

本文阐述了混合动力电动汽车的结构和工作原理，设计并实现了一种基于SVPWM矢量控制的混合动力车驱动控制系统，给出了控制系统的软件流程，并对关键模块做了较详细的说明。驱动单元现场运行情况良好，其工作波形证明了其控制系统设计的正确性。     

In Situ Topochemical Transformation of ZnIn2S4 for Efficient Photocatalytic Oxidation of 5-Hydroxymethylfurfural to 2,5-Diformylfuran

Photocatalytic selective oxidation of 5-hydroxymethylfurfural (HMF) coupled H₂ production offers a promising approach to producing valuable chemicals. Herein, an efficient in situ topological transformation tactic is developed for producing porous O-doped ZnIn₂S₄ nanosheets for HMF oxidation cooperative with H₂ evolution. Aberration-corrected high-angle annular dark-field scanning TEM images show that the hierarchical porous O-ZIS-120 possesses abundant atomic scale edge steps and lattice defects, which is beneficial for electron accumulation and molecule adsorption. The optimal catalyst (O-ZIS-120) exhibits remarkable performance with 2,5-diformylfuran (DFF) yields of 1624 µmol h⁻¹ g⁻¹ and the selectivity of >97%, simultaneously with the H₂ evolution rate of 1522 µmol h⁻¹ g⁻¹. Mechanistic investigations through theoretical calculations show that O in the O-ZIS-120 lattice can reduce the oxidation energy barrier of hydroxyl groups of HMF. In situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) results reveal that DFF^* (C₄H₂(CHO)₂O^*) intermediate has a weak interaction with O-ZIS-120 and desorb as the final product. This study elucidates the topotactic structural transitions of 2D materials simultaneously with electronic structure modulation for efficient photocatalytic DFF production.     

Digital driver for 2-inch LTPS AM-OLED displays

Organiclightemittingdiode(OLED)displayshave beenattractingmoreattentionbecauseoftheirvariousadvantagesincludingsimplestructure,self emitting,fast responsetimeandwideviewingangle.Inthelastdec ade,thefocusofresearchisonimprovementofefficiency andreliability…     

多弹串联预装填式发射器内弹道过程的数值模拟

多弹串联预装填式发射器无传统发射器的运动部件，能实现超高射速，在未来战争中必将会有很重要的作用。本文建立了反映膛内规律的理论计算内弹道模型，并对该模型进行了数值模拟，分析了射击频率、装药量、行程长对最大膛压和初速的影响。     

身管弯曲度测量误差处理技术研究

给出了基于PSD(position sensing detector)传感器的弯曲度测量系统的基本硬件结构。分析了电路系统引起的系统误差和随机误差。提出了采用内插、曲线拟合、动态调零等技术消除电路部分系统误差及采用滤波抑制随机误差的处理方法。分析了机械系统由于机械加工、机械装配引起的系统误差．建立了误差模型。提出了通过最小二乘法求解误差参数和修正测量结果的误差处理方法。     

Calculation of the Fisher information matrix for multidimensional data sets

Data sets that are acquired in many practical systems can be described as the output of a multidimensional linear separable-denominator system with Gaussian measurement noise. An important example is nuclear magnetic resonance (NMR) spectroscopy. In NMR spectroscopy, high-accuracy parameter estimation is of central importance. A classical result on the Crame/spl acute/r-Rao lower bound states that the inverse of the Fisher information matrix (FIM) provides a lower bound for the covariance of any unbiased estimator of the parameter vector. The calculation of the FIM is therefore of central importance for an assessment of the accuracy with which parameters can be estimated. It is shown how the FIM can be expressed using the matrices that determine the system that generates the data set. For uniformly sampled data, it is shown how the FIM can be expressed through the solutions of Lyapunov equations. The novel techniques are demonstrated with an example arising from NMR spectroscopy.     

制备过程中对VO_2薄膜热致相变光电性能的控制

本文利用真空还原V2 O5的方法制备出优质对VO2 薄膜 ;研究了不同真空还原时间VO2 薄膜热致相变过程中光电性能的影响 ;利用XPS、XRD对薄膜的化学状态和结晶状态进行了研究。制备的薄膜高 /低温电阻变化最大达到三个数量级 ,90 0nm处的光学透过率在相变前后改变了 40 %左右 ,热致相变性能优良。讨论了不同的真空还原时间下VO2 薄膜热滞回线的宽度、相变温度点以及高低温光透射性能。最后给出了最佳真空还原时间。