A Highly Stable Electrochemical Scanning Tunneling Microscope

We demonstrate a home-built electrochemical scanning tunneling microscope （ECSTM）. The ECSTM exhibits highly stable performance. The drifting rates in XY and Z directions of the ECSTM are about 67 and 55.6 pm/min, respectively. Moreover, a specially designed scanner unit successfully solves the well-known problem of large leakage current in high humidity atmosphere. The mechanical structure of the ECSTM is described in detail. The excellent performances of the system are demonstrated by the measured STM images （in copper sulfate solution）, including clean and well-ordered large area morphology of Au（111） and the atomically resolved image of highly oriented pyrolytic graphite.

基质微环境力学与细胞生物学行为

细胞作为有机体的最小组成单元,广泛参与着一系列的生命活动。细胞甚至单分子层面上的生物化学反应一直是探究机体生理活性的重点。近些年来,越来越多的研究指出,力学微环境广泛地影响着细胞的生物学活性,如细胞内蛋白质的分布和动态变化、信号转导等,同时细胞对外界产生的力学效应在组织的重构中起着重要的作用。理解力学微环境与细胞生物学效应的关系为研究生理病理条件下细胞的变化提供了新的视角,同时为开发支架等仿生材料提供了新的思路。本文总结了基质的硬度、配体浓度如何影响细胞黏附、迁移和分化,可为未来生物力学的研究提供基础和依据。

A Simple,Compact and Rigid Scanning Tunneling Microscope

We present a homebuilt scanning tunneling microscope(STM)which employs an inner-wall polished sapphire guiding tube as a rail for the scanner to form a short tip-sample mechanical loop.The scanner is mounted on a square rod which is housed in the guiding tube and held by a spring strip.The stiff sapphire guiding tube allows the STM body to be made in a simple,compact and rigid form.Also the material of sapphire improves the thermal stability of the STM for its good thermal conductivity.To demonstrate the performance of the STM,high quality atomic-resolution STM images of high oriented pyrolytic graphite were given.

Direct Observation of Transition Metal Dichalcogenides in Liquid with Scanning Tunneling Microscopy

We present atomic-resolution images of TiSe2,MoTe2 and TaS2 single crystals in liquid condition using our home-built scanning tunneling microscopy(STM).By facilely cleaving of single crystals in liquid,we were able to keep the fresh surface not oxidized within a few hours.Using the high-stable home-built STM,we have obtained atomic resolution images of TiSe2 accompanied with the single atom defects as well as the triangle defects in solution for the first time.Besides,the superstructure of MoTe2 and hexagonal chargedensity wave domain structure in nearly commensurate phase of TaS2 were also obtained at room temperature(295 K).Our results provide a more efficient method in investigating the lively surface of transition metal dichalcogenides.Besides,the high stable liquid-phase STM will support the further investigations in liquid-phase catalysis or electrochemistry.

基于二分法的感应电机电流预测控制研究

提出一种新型的恒开关频率感应电机的模型预测电流控制方法。使用模型预测电流控制,设计了考虑参考电流和预测电流之间误差的代价函数。提出一种基于二分法的准连续参考电压计算的数值方法,用于在逆变器切换前生成优化的参考电压矢量作为PWM输入值。这可以显著提高电流质量,减少转矩脉动,并确保逆变器的开关频率固定。所提出的方法通过仿真验证,提高了感应电动机性能。

永磁电机优化占空比模型预测控制研究

提出了用于表面式永磁同步电机驱动系统的占空比控制的一种新型有限控制集模型预测控制(FCS-MPC)。该算法分别计算三个方向的占空比,建立一个新的控制集,并从中选择最佳电压矢量,同时进行原型实验。结果表明,该方法具有良好的性能,定子电流失真小,转矩脉动小,动态响应快的特点。