Crystal Size,Morphology, and Growth Mechanism in Bio‐Inspired Apatite Nanocrystals

Bio‐inspired apatite nanoparticles precipitated in the presence of citrate ions at increasing maturation times are characterized in terms of structure, size, morphology, and composition through advanced X‐ray total scattering techniques. The origin of the platy crystal morphology, breaking the hexagonal symmetry, and the role of citrate ions is explored. By cross‐coupling the size and shape information of crystal domains with those obtained by atomic force microscopy on multidomain nanoparticles, a plausible mechanism underlying the amorphous‐to‐crystal transformation is reconstructed. In the present study, citrate plays the distinct roles of inducing the platy morphology of the amorphous precursor and controlling the thickness of the Ca‐deficient apatite nanocrystals. These findings can open new scenarios also in bone mineralization, where citrate might have a broader role to play than has been thought to date.     

一种直线感应电机的电磁场有限元分析

直线感应电机目前已经在地铁、轻轨等轨道交通中得到了很好的应用，在高速交通系统和其它一些游乐设施中也有光明的前景。本文针对正在建设中的直线电机综合测试试验台所用的直线电机，通过合理简化的方法建立了MAXWELL2一D仿真模型，同时也介绍了该类电机的结构和其传统等值电路。通过对有限元仿真结果与直线电机等效电路的计算值比较研究，发现用这两种不同方法得出的直线电机牵引力值和初级电流值非常接近，从而验证了仿真的正确性，仿真结果对今后控制系统的优化有着重要意义。     

Building Elastic Solid Electrolyte Interphases for Stabilizing Microsized Antimony Anodes in Potassium Ion Batteries

Alloy anodes composed of microsized particles receive increasing attention recently, which outperform the nanostructured counterparts in both the manufacturing cost and volumetric energy density. However, the pulverization of particles and fracture of solid electrolyte interphase (SEI) during cycling brings about fast capacity degradation. Herein, it is shown how normally considered fragile SEI can become highly elastic through electrolyte chemistry regulation. Compared to the SEI constructed in classic carbonate electrolyte, the atomic force microscopy tests reveal that the one built in ether-based electrolyte doubles the maximum elastic strain to accommodate the repeated swelling-contracting. Such an SEI effectively encapsulates the microsized Sb anodes to prevent the capacity loss from particle isolation. Coupled with an intercalation-assisted alloying reaction mechanism, a sustained capacity of ≈573 mAh g⁻¹ after 180 cycles at 0.1 A g⁻¹ with outstanding initial Coulombic efficiency is obtained, which is among the highest values achieved in K-ion batteries. This study emphasizes the significance of building robust SEI, which offers the opportunity to enable stable microsized alloy anodes.     

LDMOS功率器件在T/R组件中工程化应用研究

LDMOS微波功率器件与Si双极器件相比具有输出功率大、效率高、带宽宽等特点,在军用雷达电子系统中的广泛应用也是大势所趋,与其传统应用的区别是射频脉冲工作及饱和区工作。为了实现LDMOS的大规模工程化应用,必须通过调试解决LDMOS在C类或AB类工作条件下的一致性问题,电路设计时带外抑制信号增益,通过减小感应电动势提高器件使用可靠性等设计手段实现该器件的雷达工程应用。     

A tele-monitoring system for gait rehabilitation with an inertial measurement unit and a shoe-type ground reaction force sensor

In this paper, a tele-monitoring system is proposed, using an inertial measurement unit (IMU) and a shoe-type ground reaction force (GRF) sensor called a Smart Shoe to measure a patient’s walking data, and transmitting the measured data via the Internet. In our previous work, a mobile gait-monitoring system was developed, which provided visual feedback based on GRFs measured by a Smart Shoe (used as a mobile platform). However, the limited information provided by the Smart Shoe alone may not be adequate for a tele-monitoring system using the Internet. In the present tele-monitoring system for gait rehabilitation, a Smart Shoe is combined with an IMU for detailed monitoring of walking motions. By analyzing the signals from the IMU and the Smart Shoe, foot trajectories, walking distance, length of stride, etc., can be estimated. A user-friendly graphic interface displays the measured or estimated data on separate computers at the patient’s location and the physical therapist’s office. Thus, using the proposed system, it is possible to monitor a patient’s walking motion via the Internet, without restrictions on time or place.     

银纳米线与二氧化硅衬底表面摩擦力的测量

银纳米线是制作纳米光电子器件的理想材料,了解银纳米线与特定衬底间的摩擦特性对于器件的设计和制备工艺具有重要参考价值.本文利用原子力显微镜(AFM)研究银纳米线与二氧化硅衬底表面的摩擦特性,为提高摩擦力测量准确性,依次借助斜面法和横向力曲线分别标定了AFM探针的扭转弹性常数和光杠杆横向灵敏度,同时对扫描器引入的横向误差进行了补偿.利用AFM纳米操纵技术记录了单根银纳米线由静止到整体滑动的全过程,实验测得直径50 nm银纳米线与二氧化硅衬底表面的最大静摩擦线密度和滑动摩擦线密度分别为1.07 nN/nm和0.56 nN/nm.     

离心力对伺服系统的影响

方位在高速旋转状态下,对俯仰的位置控制难以按设定的步距角进行控制的问题,从力学上进行了理论分析和工程实验,通过理论分析和工程实验,发现该问题主要是由于方位在高速旋转时所产生的离心力分量对俯仰的运动产生的影响。工程实践表明：在实际系统中通过加大输出力矩能很好地实现对俯仰的运动控制。     

A simple method for high yield fabrication of sharp silicon tips

A simple, high yield, method for the fabrication of sharp silicon tips is described. A triangular etch mask design is used to ensure that the tip forms with a single point. An anisotropic wet etch gives rise to a tip that continues to “self-sharpen” after the etch mask is released. The tip geometry comprises three converging {1 1 3} planes towards the apex with {3 1 3} planes forming at the base. The apex of each tip typically has a radius of curvature of <5 nm, which can be reduced to <2 nm by a subsequent oxide sharpening process. Tips of this kind have been successfully integrated into the fabrication of atomic force microscopy probes.     

Dielectric–Semiconductor Interface Limits Charge Carrier Motion at Elevated Temperatures and Large Carrier Densities in a High‐Mobility Organic Semiconductor

The fundamental nature of charge transport in highly ordered organic semiconductors is under constant debate. At cryogenic temperatures, effects within the semiconductor such as traps or the interaction of charge carriers with the insulating substrate (dipolar disorder or Fröhlich polarons) are known to limit carrier motion. In comparison, at elevated temperatures, where charge carrier mobility often also decreases as function of temperature, phonon scattering or dynamic disorder are frequently discussed mechanisms, but the exact microscopic cause that limits carrier motion is debated. Here, the mobility in the temperature range between 200 and 420 K as function of carrier density is explored in highly ordered perylene‐diimide from 3 to 9 nm thin films. It is observed that above room temperature increasing the gate electric field or decreasing the semiconducting film thickness leads to a suppression of the charge carrier mobility. Via X‐ray diffraction measurements at various temperatures and electric fields, changes of the thin film structure are excluded as cause for the observed mobility decrease. The experimental findings point toward scattering sites or traps at the semiconductor–dielectric interface, or in the dielectric as limiting factor for carrier mobility, whose role is usually neglected at elevated temperatures.     

Improved direct inverse tracking control of a piezoelectric tube scanner for high-speed AFM imaging

For a piezoelectric tube scanner (PTS), this paper proposes an improved direct inverse tracking control algorithm and apply it to an atomic force microscope (AFM) to accomplish high-speed scanning tasks. That is, to enhance the high-speed tracking control performance of a PTS, an improved direct inverse rate-dependent Prandtl–Ishlinskii (P–I) model is firstly constructed, which includes a polynomial module to eliminate the structure nonlinearity. Based on the model, a practical feedforward control law is then designed to implement high-speed tracking control for a high-frequency trajectory with strong robustness, which presents the advantages of high-speed response, simple structure and convenient implementation. Subsequently, the designed feedforward law is combined with a feedback component, and the combined control strategy is employed in an AFM to accomplish fast imaging tasks. Numerous experimental results are then collected, which convincingly demonstrate the superior performance of the proposed practical model/control scheme.