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.     

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.     

The research on temperature measurement based on polarization dependent loss

This paper analyzes the properties of reflected polarization dependent loss of apodized fiber Bragg gratings with temperature effective. We simulates reflected spectrum and polarization dependent loss of the apodized fiber Bragg gratings. The reflected spectrum and polarization dependent loss are measured under different temperatures. The analysis results show that reflected polarization dependent loss presents two peaks which shift an equal proportion to long wavelength with temperature increasing and have very good stability so we propose an idea that use polarization dependent loss as temperature sensor measurement parameters. The results show that the accuracy of measurement can be increased almost by one order of magnitude.     

量子信令中继器模型及性能仿真

为了解决量子信令远程传输损伤问题,提出了一种量子信令中继器模型. 在该模型中,首先对接收到的信令量子态进行纠缠纯化和纠缠分发,这样就可在收发双方之间建立纠缠信道. 其次,通过纠缠交换,传送所要发送的量子信令,从而完成量子信令的中继. 仿真结果表明,在保真度为0.98、纠缠对成功建立概率为0.98的条件下, 信令中继成功率可以达到97%以上;在纠缠交换概率、纯化概率和纠缠对成功建立概率都为0.98时, 量子信令中继器的吞吐量可达到183kbps,以上各项指标能够有效满足量子通信对信令中继的要求. 关键词： 量子通信 量子信令 纠缠纯化 纠缠分发     

Lead zirconate titanate behaviors in an LDMOS

The behaviors of lead zirconate titanate (PZT) deposited as the dielectric for high-voltage devices are investigated experimentally and theoretically. The devices demonstrate not only high breakdown voltages above 350 V, but also excellent memory behaviors. A drain current-gate voltage (ID-VG) memory window of about 2.2 V is obtained at the sweep voltages of ±10 V for the 350-V laterally diffused metal oxide semiconductor (LDMOS). The retention time of about 270 s is recorded for the LDMOS through a controlled ID-VG measurement. The LDMOS with memory behaviors has potential to be applied in future power conversion circuits to boost the performance of the energy conversion system.     

多环芳烃时间分辨荧光光谱特性研究

利用时间分辨荧光光谱技术,研究了菲、荧蒽、芴、蒽、芘等五种多环芳烃的荧光时间分辨发射光谱特性。以289 nm受激拉曼光作为激发光源,研究了289 nm激发光作用下五种多环芳烃的延时特性和门宽特性。并以多环芳烃随延时时间的荧光峰强度衰减关系曲线,得到菲、荧蒽、芴、芘的荧光寿命分别为37.0, 32.7, 10.9, 147.0 ns。不同荧光物质具有特定的荧光光谱特性,多环芳烃时间分辨荧光光谱特性的研究可以为复杂水体中不同种类多环芳烃的诊断提供依据。     

利用三维荧光结合平行因子算法研究金属离子对溶解性有机物的猝灭和校正

溶解性有机物的荧光组份由于受到金属离子的影响其荧光强度受到变化,从而为溶解性有机物的定量分析带来挑战。利用三维荧光结合平行因子分析方法研究了Cu(Ⅱ), Fe(Ⅲ), Ni(Ⅱ), Sr(Ⅱ), Hg(Ⅱ), K(Ⅰ), Mg(Ⅱ) 和Mn(Ⅱ)八个金属离子对典型溶解性有机物荧光组分的荧光猝灭作用,五个水样来源各不相同。实验表明水样被平行因子成功分解为三个荧光组分(色氨酸、腐殖酸、富里酸),这三个荧光组份的荧光得分随着Fe(Ⅲ), Cu(Ⅱ), Hg (Ⅱ)和 Ni(Ⅱ)浓度的增加呈线性或指数下降。在这四种离子中,Fe(Ⅲ)和Cu(Ⅱ)对腐殖酸和富里酸的荧光猝灭作用明显大于Hg (Ⅱ)和 Ni(Ⅱ)。Sr(Ⅱ), K(Ⅰ), Mg(Ⅱ)和Mn(Ⅱ)基本没有影响。其中Fe(Ⅲ)对于三个荧光组分的荧光猝灭都有较好的分析。由于只考虑Fe(Ⅲ) 和Cu(Ⅱ)的影响,对于含有金属离子的饮用水的荧光强度的校正曲线也被建立。不同来源的饮用水中荧光组份的荧光得分的衰减规律也是不一样的,因此水样的来源也是测量时需要考虑的因素。实验证实了金属离子对溶解性有机物的荧光猝灭作用以及其他因素比如Fe(Ⅲ) 和Cu(Ⅱ)和溶解性有机物本身的多样性都是我们荧光测量典型荧光组份时需要考虑的。表明三维荧光结合平行因子分析方法是一个有效的准确测量溶解性有机物荧光组份的工具。     

Diode-pumped 593.5 nm cw yellow laser by type-I CPM LBO intracavity sum-frequency-mixing

A design of LD-pumped Nd:YVO₄ laser that generates simultaneous laser action at wavelengths 1064 and 1342 nm by optimizing film design is presented. An optimized continuous-wave (cw) yellow laser at 593.5 nm in room temperature is obtained for the first time. Using type-I critical phase-matching (CPM)LBO crystal, a yellow laser at 593.5 nm is obtained by 1064 and 1342 nm intracavity sum-frequency mixing. The maximum laser output power of 85 mW is obtained when an incident pump laser of 1.8 W is used. The optical-to-optical conversion is up to 4.7%, and the power stability in 24 h is better than ±2.8%.