Characterization and catalytic behavior of silica-supported copper catalysts prepared by impregnation and ion-exchange methods

Two kinds of Cu/SiO₂ catalysts were prepared by impregnation (IM) and ion-exchange (IE) methods, and tested in dehydrogenation of 2-butanol to methyl-ethyl-ketone. Some kinds of Cu²⁺ on the IE catalyst could not be reduced during the reaction, and it produced the butene. The copper oxide over the IM catalyst could be reduced during the reaction, and showed stable dehydrogenation activity for 2-butanol.     

Fabrication of solid oxide fuel cell based on doped ceria electrolyte by one-step sintering at 800 °C

Ce_0.8Gd_0.05Y_0.15O_1.9 (GYDC) electrolyte was prepared by a carbonate co-precipitation method. Lithium nitrate at 1, 1.5, 2 and 3 mol% was added to GYDC as sintering additive. 96% relative density was achieved for GYDC at sintering temperature of 800 °C with addition of 1.5 mol% LiNO₃. The conductivities of GYDC with sintering aids LiNO₃ were measured by a.c. impedance spectroscopy and showed comparable values to that of pure GYDC sample sintered at 1400 °C. A single cell with 1.5 mol% LiNO₃ infiltrated GYDC electrolyte was fabricated by sintering at 800 °C for only 2 h. Lithiated NiO was synthesized by the glycine-nitrate combustion method and employed as cathode material. The cell was tested at temperatures from 500 to 575 °C and a maximum power density of 73 mW cm^− 2 was obtained at 575 °C. These preliminary results indicate that LiNO₃ is a very effective sintering additive for intermediate temperature solid oxide fuel cell fabrication.     

Modifications of interface chemistry of LSM-YSZ composite by ceria nanoparticles

A porous composite electrode LSM-YSZ (lanthanum strontium manganite and yttria stabilized zirconia) was impregnated with different amounts of SDC (samarium substituted ceria) nanoparticles. The materials were investigated with X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy to determine the microstructure, the interface chemistry and the surface chemistry of the various impregnated samples. The SDC nanoparticles cover the surface of the LSM-YSZ backbone to a large extent; they are approximately 5-20 nm in diameter and have a cubic crystal structure. Low concentrations of lanthanum and manganese originating from LSM were detected within SDC particles. It was also observed that the relative atomic concentration of strontium increased on the LSM-YSZ surface with increasing amount of SDC nanoparticles. These findings are related to the applied nanoparticle impregnation method. It is indicated that interactions between surfactant, nanoparticles, impregnation solution and the LSM-YSZ composite take place which can locally affect the surface and interface chemistry of the investigated materials.     

不同金属在催化脱硝过程中作用研究

采用共浸渍法和分步浸渍法在氧化铝载体上通过调节金属元素的负载量和负载顺序制备了多种催化剂,测试了其在NH3作为还原剂条件下的低温催化脱硝活性,研究各种活性组分在脱硝过程中的作用,考察浸渍顺序对脱硝性能的影响。在(?)(NO)=500×10~(-6),n(NH_3):n(NO)=1:1和(?)(O_2)=3.6%的条件下进行试验,结果表明,Mn在脱硝反应中是主要的活性组分,而Fe和Zr是助催化组分;浸渍顺序对催化剂脱硝活性有一定影响;当Fe负载量达到10%时,制备的催化剂5Zr-5Mn-10Fe/Al_2O_3脱硝活性最佳。     

Explicit optimal value for Dynkin's stopping game

Under the One-step Look Ahead rule of Dynamic Programming, an explicit game value of Dynkin's stopping problem for a Markov chain is obtained by using a potential operator. The condition on the One-step rule could be extended to the k-step and infinity-step rule. We shall also decompose the game value as the sum of two explicit functions under these rules.     

一类抛物型方程初值问题的随机数值算法

本文引入了求解二阶拟线性抛物型微分方程初值问题的一类新的数值算法一分层方法,这种数值方法是通过弱显式欧拉法离散其方程解的概率表示而得到的,相应地给出了该分层方法的收敛性结果.此外,还构造了基于插值的数值算法,最后提供了数值实验,得到的数值结果验证了获得的算法的精确性和有效性.     

Microfluidic immunoassay with plug-in liquid crystal for optical detection of antibody

Recent advance in liquid crystal (LqC) based immunoassays enables label-free detection of antibody, but manual preparation of LqC cells and injection of LqC are required. In this work, we developed a new format of LqC-based immunoassay which is hosted in a microfluidic device. In this format, the orientations of LqC are strongly influenced by four channel walls surrounding the LqC. When the aspect ratio (depth/width) of the channel is smaller than 0.38, LqC orients homeotropically inside the microchannel and appears dark. After antigens bind to immobilized antibodies on the channel walls, a shift of the LqC appearance from dark to bright (due to the disruption of LqC orientation) can be visualized directly. To streamline the immunoassay process, a tubing cartridge loaded with a sample solution, washing buffers and a plug of LqC is connected to the microfluidic device. By using pressure-driven flow, the cartridge allows antigen/antibody binding, washing and optical detection to be accomplished in a sequential order. We demonstrate that this microfluidic immunoassay is able to detect anti-rabbit IgG with a naked-eye detection limit down to 1 μg mL⁻¹. This new format of immunoassay provides a simple and robust approach to perform LqC-based label-free immunodetection in microfluidic devices.     

基于新型螺氧杂蒽主体的高效蓝色磷光有机发光二极管

We synthesized a series of novel spiro[fluorene-9, 9'-xanthene] (SFX)-based host materials via a one-step palladium-catalyzed cross-coupling reaction. These materials have high triple energy levels and high yield, and thus can be used as hosts for blue phosphors. Blue phosphorescent organic light-emitting devices (PHOLEDs) with a bis (3, 5-difluoro-2-(2-pyridyl) phenyl-(2-carboxypyri-dyl) iridium (Ⅲ) (FIrpic) emission were fabricated. Furthermore, we applied cohosts composed of one of the new synthesized materials and the hole transport material di-[4-(N, N-ditolyl-amino)-phenyl]cyclohexane (TAPC) to the blue PHOLEDs to successfully acquire efficient blue emissions. The SFX-based material provided efficient energy transfer while TAPC improved the mobility of the cohost as well as reduced the working voltage. Maximum current efficiencies of 22.56 and 25.93 cd·A^-1 and the maximum brightnesses of 6421 and 6196 cd·m^-2 were obtained for the PHOLEDs with TAPC: 2-(9-phenyl-fluoren-9-yl) spiro[fluorene-9, 9'-xanthene] (PF-SFX) and TAPC: 2-(9-(4-(octyloxy)-phenyl)-9H-fluoren-9-yl) spiro[fluorene-9, 9'-xanthene] (C8OPF-SFX) cohosts, respectively. The experimental results obtained for the four SFX-based host materials were enough to declare that SFX is an effective main unit that can be used to build efficient host materials for blue phosphors containing only C, H, and O basic elements.     

One step electrochemically deposited nanocomposite film of chitosan-carbon nanotubes-gold nanoparticles for carcinoembryonic antigen immunosensor application

A simple and controllable one-step electrodeposition method for the preparation of a chitosan-carbon nanotubes-gold nanoparticles (CS-CNTs-GNPs) nanocomposite film was used to fabricate an immunosensor for detection of carcinoembryonic antigen (CEA). The porous three-dimensional CS-CNTs-GNPs nanocomposite film, which offered a large specific surface area for immobilization of antibodies, exhibited improved conductivity, high stability and good biocompatibility. The morphology of the formed nanocomposite film was investigated by scanning electron microscopy (SEM), and the electrochemical behaviors of the immunosensor were characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Under the optimal conditions, the proposed immunosensor could detect CEA in two linear ranges from 0.1 to 2.0 ng mL⁻¹ and from 2.0 to 200.0 ng mL⁻¹, with a detection limit of 0.04 ng mL⁻¹. The immunosensor based on CS-CNTs-GNPs nanocomposite film as the antibody immobilization matrix could exhibit good sensitivity, stability, and reproducibility for the determination of CEA.     

超声浸渍对费托合成Co/Zr/SiO2催化剂性能的影响

采用超声浸渍法制备了费托合成Co/Zr/SiO2催化剂,考察了超声波功率对催化剂费托反应性能的影响,并运用N2物理吸附、X射线衍射、H2程序升温脱附、H2程序升温还原和透射电子显微镜对催化剂进行了表征,结果表明,超声波处理可以增大催化剂的比表面积,减小金属Co的粒径,并使其较为均匀地分散于载体表面,其中以高功率超声波作...