Electrochemical performance of Al-doped LiMn2O4 prepared by different methods in solid-state reaction

Al-doped LiMn₂O₄ cathode materials synthesized by a newly developed wet-milling method and a dry process method using a conventional solid-state reaction were evaluated physicochemically and electrochemically. In the wet-milling method, a precursor was made from the raw materials atomized by a wet milling. A good cyclic performance was obtained for the LiMn₂O₄ samples prepared by the wet-milling method, achieved up to 99% of retention of capacity at 50 °C at the 30th cycle. The precursor obtained by the wet-milling method was well homogenous and highly reactive due to their finely ground particles, giving good crystallinity to LiMn₂O₄ products.     

基于液晶引流效应的全新微流体驱动方式

对现有微流体驱动技术中普遍存在的微型化难、驱动力小等缺点,提出液晶引流驱动方式。作为开发该驱动方式的第一步,采用理论计算模拟与辅助试验验证相结合的研究方法,以小分子液晶Leslie-Ericksen理论为基础,对上板处于浮动状态下液晶盒的驱动效果及影响因素进行研究。结果表明,连续方波电场作用下引起的液晶引流效应可以驱动液晶盒上板运动,方波电场频率为1 Hz、有效率为5%时驱动速度最大。液晶分子指向矢倾斜角的旋转范围对驱动效果影响较大,所施加电压对于倾斜角的旋转范围没明显影响,两板间的距离却影响很大。通过选择合适的驱动条件已成功得到90μm/s的高驱动速度。采用显微镜下直接观察液晶盒上板运动情况的方法进行试验验证,结果与理论计算结果定性上十分吻合,定量上试验结果偏小,最大差距出现在电场施加后的第三周期,主要原因是液晶盒制作时初始配向误差,可通过改变配向膜的种类及摩擦条件来改善。     

Mass imaging and identification of biomolecules with MALDI-QIT-TOF-based system

Imaging mass spectrometry is becoming a popular visualization technique in the medical and biological sciences. For its continued development, the ability to both visualize and identify molecules directly on the tissue surface using tandem mass spectrometry (MSn) is essential. We established an imaging system based on a matrix-assisted laser/desorption ionization quadrupole ion trap time-of-flight type instrument (AXIMA-QIT, Shimadzu, Kyoto, Japan), which was compatible with both imaging and highly sensitive MSn. In this paper, we present the operating conditions of the AXIMA-QIT as an imaging instrument and introduce the data converter we developed that is available free of charge. The converted data can be applied to Biomap, the commonly used visualization software. For the feasibility experiments, we demonstrated the visualization of phospholipids, glycolipid, and tryptic-digested proteins in the mouse cerebellum. The visualized lipids were successfully identified by MSn directly on the tissue surface, with a strong ability to isolate precursor ions. In the analysis of tryptic-digested proteins, we compared the product ion spectra between AXIMA-QIT and a tandem TOF-type instrument. The results confirmed that AXIMA-QIT can provide a high quality of product ion spectra even on the tissue surface.     

A simplified method of calculating busbar inductance and its application for stray resonance analysis in an inverter dc link

Sinusoidal PWM control is widely applied to power electronic converters. The carrier frequency of recent converter products is gradually being raised in order to decrease current harmonics as much as possible. However, in the dc filter circuits of large capacity converters, the capacitance of a unit capacitor is relatively large, and the busbars are relatively long. Therefore, the resonant frequency is lower than those of small capacity converters. Consequently, there is a concern that the carrier frequency will become close to the resonant frequency, which will cause trouble. On the other hand, it is often necessary to decrease the inductance of the loop circuit consisting of a switching device and its by‐pass circuit, in order to suppress the switching surge voltage. In both cases described above, it is important to be sure of the exact busbar inductance for reliable design. In this paper, a simplified method of calculating busbar inductance is proposed. This method is based on the partial inductance theory. In particular, the characteristics of a pair of busbars, and the use of the method are described. Finally, an application to stray resonance analysis in the dc filter circuit of a three level inverter is described in comparison with experimental data. From these results, we confirmed that the proposed method is usable to estimate busbar inductance quickly and accurately. © 1999 Scripta Technica, Electr Eng Jpn, 126(3): 49–63, 1999