Influence of tetraborate anions on manganese electrodeposition in an anion-exchange membrane electrolysis reactor

The influences of tetraborate anions on manganese electrodeposition in an anion-exchange membrane electrolysis reactor were investigated. The experimental results of manganese electrodeposition indicate that a certain amount of tetraborate anions can increase cathode current efficiency and initial pH 7.0–8.0 is suitable for high cathode current efficiency. X-ray diffraction (XRD) and scanning electron microscope (SEM) analysis show the nanocrystalline structure and impact morphology of electrodeposited manganese. The purity of electrodeposited manganese is above 99.88 %. The tests of tetraborate anions on buffer capacity (β) and pH value of the electrolyte near the cathode surface confirm that tetraborate anions facilitate manganese electrodeposition. Tetraborate anions can improve concentration polarization of Mn²⁺ ions and then increase the overpotential of hydrogen evolution reaction. Therefore, ammonium tetraborate can reduce the hydrogen embrittlement, pore, and pitting negative effect on electrodeposit surface, to improve the corrosion resistance of electrodeposited manganese. After tetraborate anions being added in electrolyte, weight loss measurement indicates that the corrosion resistance of electrodeposited manganese is improved. Electrochemical measurements testify that corrosion resistance of electrodeposited manganese containing tetraborate anions in electrolyte is reflected by less negative corrosion potential and higher impedance.     

Determining the resistance of X-pinch plasma

The current and the voltage of an X-pinch were measured. The inductance of the X-pinch was assumed to be a constant and estimated by the calculation of the magnetic field based on the well-known Biot-Savart's Law. The voltage of the inductance was calculated with L · di/dt and subtracted from the measured voltage of the X-pinch. Then, the resistance of the X-pinch was determined and the following results were obtained. At the start of the current flow the resistance of the exploding wires is several tens of Ohms, one order of magnitude, higher than the metallic resistance of the wires at room temperature, and then it falls quickly to about 1 , which reflects the physical processes occurring in the electrically exploding wires, i.e., a current transition from the highly resistive wire core to the highly conductive plasma. It was shown that the inductive contribution to the voltage of the X-pinch is less than the resistive contribution. For the wires we used, the wires' material and diameter have no strong influence on the resistance of the X-pinch, which may be explained by the fact that the current flows through the plasma rather than through the metallic wire itself. As a result, the current is almost equally divided between two parallel X-pinches even though the diameter and material of the wires used for these two X-pinches are significantly different.     

激波冲击R22重气柱所导致的射流与混合研究

基于大涡模拟, 结合五阶加权基本无振荡格式与沉浸边界法对激波自左向右与R22重气柱作用过程进行了数值模拟. 数值结果清晰地显示了激波诱导Richtmyer-Meshkov不稳定性所导致的重气柱变形过程, 并与Haas 和 Sturtevant 的实验结果符合. 另外, 结果还揭示了入射激波在气柱内右侧边界发生聚焦并诱导射流的过程, 以及在Kelvin-Helmhotz 次不稳定性作用下两个主涡滑移层形成次级涡的过程, 并分析了气柱变形过程中与周围空气的混合机理. 最后, 通过改变反射距离对反射激波与不同变形阶段的气柱的再次作用过程进行了研究. 结果表明: 当激波反射距离较长时, 反射激波与充分变形后的气柱作用, 使其在流向方向上进一步被压缩; 而当激波反射距离较短时, 反射激波会在气柱内发生马赫反射, 两个三波点附近产生两个高压区, 当其传播至气柱左侧边界时对气柱边界造成冲击加速, 诱导两道向左传播的反向射流. 关键词： Richtmyer-Meshkov不稳定性 R22重气柱 反射激波 射流     

飞秒激光剥蚀-多接收电感耦合等离子质谱原位微区分析青铜中铅同位素组成-以古铜钱币为例

建立了飞秒激光剥蚀-多接收电感耦合等离子质谱(fLA-MC-ICPMS)铅同位素原位微区分析方法,分别利用溶液法(SN-MC-ICPMS)和激光剥蚀法(fLA-MC-ICPMS)对15个铜(黄铜,青铜)国家标准物质进行了实验分析,测试的结果表明CuPb12(GBW02137)中Pb同位素组成非常均一,可作为以铜为基体的青铜、黄铜及铜矿中Pb同位素原位微区分析的外部参考物质。对CuPb12进行了112次fLA-MC-ICPMS Pb同位素分析测试,其加权平均值与溶液法测定的Pb同位素比值在2σ误差范围内完全一致,208 Pb/204 Pb和207Pb/206Pb比值的内部精度RSE分别小于90和40ppm,外部精度RSD分别小于60和30ppm。利用本实验室建立的fLA-MC-ICPMS分析方法对13个古铜钱币中Pb同位素进行了原位微区无损伤分析,测试结果表明,不同朝代古钱币中Pb同位素组成差异较大,即使同一朝代的古钱币其Pb同位素组成也不尽相同。     

LED毫伏级待测电动势实验仪的设计及其稳定性的研究

为了满足电位差计实验对毫伏级待测电动势需求,设计了LED毫伏级待测电动势实验仪,并对其稳定性进行了研究.待测电动势实验仪是通过光电转换来实现的,输出的毫伏级电动势在电位差计实验仪的各个测量点都能稳定,能够满足箱式电位差计测量范围和精度要求,是比较理想的箱式电位差计实验配套仪器,能够大大提高学生的实验效率和教师对实验设计的选择性,实验效果良好.     

Cu/HMOR催化二甲醚羰基化合成乙酸甲酯: 催化剂制备方法的影响 (cited: 2)

采用氨蒸发法、尿素水解法、离子交换法及浸渍法制备HMOR负载的Cu催化剂, 考察其催化二甲醚(DME)羰基化合成乙酸甲酯(MA)性能. 结果表明离子交换法制得Cu/HMOR催化剂在Cu的金属中心和酸性分子筛载体的共同作用下具有较好催化反应活性. 在210 oC、1.5 MPa、空速4883 h^-1,DME转化率为95.3%,MA选择性为94.9%. 对催化剂进行N2物理吸附、X射线衍射、NH₃程序升温脱附和CO程序升温脱附等表征发现,离子交换法制得Cu/HMOR催化剂具有较高比表面、大量弱酸及一定中强酸、适中的CO吸附强度,提高了CO插入DME羰基化反应活性.     

全波段正常色散光子晶体光纤中超连续谱的产生

设计了一种铅硅酸盐SF57 材料的光子晶体光纤, 利用有限元法数值模拟了该光纤的 色散特性. 研究结果显示在整个透明波段光纤具有正常色散. 利用自适应分布傅里叶法求解非线性薛定谔方程, 对中心波长为1550 nm, 初始脉宽为150 fs 的脉冲在该光纤中传输进行了模拟, 获得了关于入射脉冲中心波长对称的展宽范围超过了600 nm 的超平坦连续光谱, 并且光谱具有极其稳定和 相干的特性. 关键词： 光子晶体光纤 超连续谱产生 正常色散     

Fabrication of rhenium Josephson junctions

Rhenium is a superconductor with a relatively weak tendency to oxidize, which is advantageous in superconducting quantum circuit and qubit applications. In this work, Re/A1-A1Ox/Re Josephson tunnel junctions were fabricated using a selective film-etching process similar to that developed in Nb trilayer technology. The Re films had a superconducting transition temperature of 4.8 K and a transition width of 0.2 K. The junctions were found to be highly reproducible using the fabrication process and their characteristics had good quality with a low leakage current and showed a superconducting gap of 0.55 meV.     

Characterizing neural activities evoked by manual acupuncture through spiking irregularity measures

The neural system characterizes information in external stimulations by different spiking patterns. In order to examine how neural spiking patterns are related to acupuncture manipulations, experiments are designed in such a way that different types of manual acupuncture （MA） manipulations are taken at the ＇Zusanli＇ point of experimental rats, and the induced electrical signals in the spinal dorsal root ganglion are detected and recorded. The interspike interval （ISI） statistical histogram is fitted by the gamma distribution, which has two parameters： one is the time-dependent firing rate and the other is a shape parameter characterizing the spiking irregularities. The shape parameter is the measure of spiking irregularities and can be used to identify the type of MA manipulations. The coefficient of variation is mostly used to measure the spike time irregularity, but it overestimates the irregularity in the case of pronounced firing rate changes. However, experiments show that each acupuncture manipulation will lead to changes in the firing rate. So we combine four relatively rate- independent measures to study the irregularity of spike trains evoked by different types of MA manipulations. Results suggest that the MA manipulations possess unique spiking statistics and characteristics and can be distinguished according to the spiking irregularity measures. These studies have offered new insights into the coding processes and information transfer of acupuncture.     

Research on lenses assemble precision in complicate laser amplification system

In a certain amplification system, signal laser can be amplified from 1 nJ to 5 J. To realize a high quality imaging transfer, meet beam diameter expansion requirement, and get good filtering effects, three spatial filters are designed and assembled. Lenses in these spatial filters can be assembled and adjusted by their reflection spots to meet wave-front requirements. In this letter, we analyze precision of the assembling, and make a ray-tracing simulation to discuss the relation between assembling precision and lenses parameters. On the optimized distance of 1000 mm, adjusting precision of lens tilt can reach 5 mrad.