Comparative study of Nickel-based perovskite-like mixed oxide catalysts for direct decomposition of NO

The mixed oxides LaNiO3, La0.1Sr0.9NiO3, La2NiO4 and LaSrNiO4 were prepared and used as catalysts for the direct decomposition of NO. The catalysts were characterized by means of XRD, XPS, O-2-TPD, NO-TPD and chemical analysis. By comparing the physico-chemical properties and catalytic activity for NO decomposition, a conclusion could be drawn as follows. The direct decomposition of NO over perovskite and related mixed oxide catalysts follows a redox mechanism. The lower valent metal ions Ni2+ and disordered oxygen vacancies seem to be the active sites in the redox process. The oxygen vacancy plays an important role favorable for the adsorption and activation of NO molecules on one hand and on the other hand for increasing the mobility of lattice oxygen which is beneficial to the reproduction of active sites. The presence of oxygen vacancies is one of the indispensable factors to give the mixed oxides a steady activity for NO decomposition.

高温高压下H2O-CH4体系PVTx性质的分子动力学模拟研究

Geological fluids are important components in the earth system. To study thephysical chemistry properties and the evolution of fluid system turns out to be one of the most challenging issues in geosciences. Besides the conventional experimental approaches and theoretical or semi-theoretical modeling, molecular level computer simulation(MLCS) emerges as an alternative tool to quantificationally study the physico-chemical properties of fluid under extreme conditions in order to find out the characteristics and interaction of geological fluids in and around earth. Based on our previous study of the intermolecular potential for pure H2O and thestrict evaluation of the competitive potential models for pure CH4 and the ab initio fitting potential surface across H2O-CH4 molecules in this study, we carried out more than two thousand molecular dynamics simulations for the PVTx properties of pure CH4 and the H2O-CH4 mixtures. Comparison of 1941 simulations with experimental PVT data for pure CH4 shows an average deviation of 0.96% and a maximum deviation of 2.82%. The comparison of the results of 519 simulations of the mixtures with the experimental measurements reveals that the PVTx properties of the H2O-CH4 mixtures generally agree with the extensive experimental data with an average deviation of 0.83% and 4% in maximum, which is equivalent to the experimental uncertainty. Moreover, the maximum deviation between the experimental data and the simulation results decreases to about 2% as temperature and pressure increase,indicating that the high accuracy of the simulation is well retained in the high temperature and pressure region. After the validation of the simulation method and the intermolecular potential models, we systematically simulated the PVTx properties of this binary system from 673 K and 0.05 GPa to 2573 K and 10 GPa. In order to integrate all the simulation results and the experimental data for the calculation of thermodynamic properties, an equation of state (EOS) is developed for the H2O-CH4 system covering 673 to 2573 K and 0.01 to 10 GPa. Isochores for compositions < 4 mol% CH4 up to 773 K and 600 MPa are also determined in this thesis.

Study on the microstructure and properties of nanosized stannic oxide powders

Stannic oxide xerogel was prepared by a forced hydrolysis method using SnCl4 as the precursor. The average grain sizes of the nanosized stannic oxide powders varied with the sintering temperatures. The powders were characterized by several different physico-chemical techniques. TEM was employed for the direct observation on grain sizes, shape and state of aggregation of the particles. XRD technique was used for the determination of the crystalline structure. Microstructural parameters of average crystallite size () and mean-square root microstrain (epsilon(2)>(1/2)) for the samples were calculated from the broadened values of the half-peak intensity of XRD. The atomic ratio between oxygen and tin in the surface region of the particles was estimated through the analysis of XPS. Attributing to lots of oxygen vacancies in the surface region of the nanoparticulates and the 'trapped electrons' in the vacancies, an ESR signal was observed in the sample sintered at 300 degrees C for 2 h. FTIR of the powders showed that intensity of the transverse optical mode of Sn-O stretching vibration increased with the sintering temperature while the bending vibration of O-Sn-O showed a blue shift. For Raman spectra, very important spectral characteristics such as variations of intensity and width of the bands were observed. A new Raman vibrational band located at 572 cm(-1) was identified in the samples of nanosized stannic oxide powders. Variation of these spectroscopic properties were strongly affected by grain size, shape and state of aggregation of the nanosized particulates.

Fabrication and emission properties of Er3+/Yb3+ codoped tellurite glass fiber for broadband optical amplification

Tellurite glass is proposed as a host for broadband erbium-doped fiber amplifiers because of their excellent optical and chemical properties. A new single mode Er3+/Yb3+ codoped tellurite fiber with D-shape cladding geometry is fabricated in this work. When pumped at 980 nm, a broad erbium amplified spontaneous emission (ASE) nearly 100 nm in the wavelength range of 1450-1650 ran around 1.53 mu m is observed. It was found that the emission spectrum from erbium in tellurite glass fibers is almost twice as broad as the corresponding spectrum in tellurite bulk glass. The changes in ASE with regard to fiber lengths and pumping power were measured and discussed. The output of about 2.3 mW from Er3+/Yb3+ codoped tellurite fiber ASE source is obtained under the pump power of 700 mW. The broad 1.53 mu m emission of Er3+ in Er3+/Yb3+ codoped tellurite glass fiber can be used as host material for potential broadband optical amplifier and tunable fiber lasers. (c) 2005 Elsevier B.V. All rights reserved.

Recent advances in synthesis and properties of cubic boron nitride films

Cubic boron nitride (c-BN) attracts widespread interest as a promising material for many potential applications because of its unique physical and chemical properties. Since the 1980's the research in c-BN thin films has been carried out, which reached its summit in the mid of 1990's, then turned into a downward period. In the past few years, however, important progress was achieved in synthesis and properties of cubic boron nitride films, such as obtaining > 1 mu m thick c-BN films, epitaxial growth of single crystalline c-BN films, and advances in mechanics properties and microstructures of the interlayer of c-BN films. The present article reviews the current status of the synthesis and properties of c-BN thin films.

Effect of oxidation on the optical and surface properties of AlGaN

The chemical properties of AlxGa1-xN surfaces exposed to air for different time periods are investigated by atomic force microscopy (AFM), photoluminescence (PL) measurement and X-ray photoelectron spectroscopy (XPS). PL and AFM results show that AlxGa1-xN samples exhibit different surface characteristics for different air-exposure times and Al contents. The XPS spectra of the Al 2p and Ga 2p core levels indicate that the peaks shifted slightly, from an Al-N to an Al-O bond and from a Ga-N to a Ga-O bond. All of these results show that the epilayer surface contains a large amount of Ga and Al oxides. (c) 2006 Elsevier B.V. All rights reserved.

青藏高原青稞淀粉资源的评价

青稞（Hordeum vulgare L.var．nudum Hook．f.），即裸大麦，是兼食用、饲用和酿造于一体的作物，有着重要的利用价值。淀粉是青稞籽粒中含量最多、最重要的碳水化合物，淀粉含量、直支淀粉比将会直接影响淀粉的功能特性，进而影响淀粉的应用领域。我国青藏高原青稞的栽培和食用历史悠久，特色青稞资源极其丰富。目前关于青藏高原青稞淀粉特性的报道还不多见，筛选和培育特色淀粉青稞利于拓展青稞的应用领域, 从而提高其经济价值。 本研究以114份青藏高原青稞品种(系)为实验材料，通过SDS-PAGE对材料的胚乳淀粉颗粒结合蛋白（SGAPs）进行分离，确定各蛋白的分子量大小、组合类型和多态性等。然后按照国标法测试材料的籽粒总淀粉含量和直链淀粉含量，通过微型糊化粘度仪分析相应的淀粉糊化特性，最后使用显微镜观察比较了青稞的淀粉颗粒形态特征。主要结果如下： 1、114种青稞中共分离出20种不同的SGAP条带，条带分子量为35.00～112.39 KDa，分布频率为12.28～97.37%。材料含有的SGAPs条带数从10到14不等，超过一半的材料含11种SGAP条带。20种条带形成16种组合类型，其中西藏地区青稞包含所有16个组合类型，四川地区青稞包含其中12个组合类型。青藏高原青稞籽粒淀粉颗粒结合蛋白的差异很大，遗传多样性丰富。 2、114份青稞的总淀粉含量、直链淀粉含量、直支淀粉比、峰值粘度、糊化温度和峰值温度的变幅分别为51.26～66.70%、14.64～29.74%、0.17～0.42、194～1135BU、58.8～65.2℃和81.4～92.4℃，相应的平均值分别为59.82%、23.60%、0.31、722.30BU、62.1℃和88.8℃。群体在总淀粉含量、直链淀粉含量、直支淀粉比、峰值粘度、糊化温度和峰值温度上的分布具有明显的正态性；所有胚乳淀粉体的淀粉粒都呈复粒结构。对西藏和四川的材料进行了分组比较， 两地区的青稞在直链淀粉含量和直支淀粉比上的差异达到显著水平。 3、筛选出18份具有特殊淀粉特性的青稞品种，其中5份材料的总淀粉含量超过65%，包括NB63-1、NB67、甘孜白六棱、98221-1和NB63；3份材料的直链淀粉含量大于29%，包括藏青85、藏青3号和喜马拉6号；8份材料的直支淀粉比小于0.25，包括99033-6、春青稞、阿坝330、Jan-03、米麦114、396、NB63-1和92013；7份材料的糊化温度低于60℃，同时材料的峰值粘度大于1000BU,并且峰值温度低于90℃，包括足捉春、Jan-03、阿坝330、米麦114、春青稞、20003和阿青5号。 4、各淀粉特性间存在高度相关性。直链淀粉含量和直支淀粉比与糊化温度成极显著正相关，与峰值粘度成极显著负相关，与A型淀粉粒数量和大小呈负相关。不同SGAPs组合的品种之间，淀粉含量和淀粉糊化特性间差异均达显著水平。SGAP2、SGAP5、SGAP6和SGAP7可能对籽粒直链淀粉含量、直支淀粉比和糊化温度有正向效应；SGAP3、SGAP9∼SGAP20可能对峰值粘度有正向效应。 本研究对青藏高原青稞淀粉资源进行了较为全面的评价，对该区青稞淀粉特性有了系统的认识。研究筛选出的特殊青稞品种可作为青稞育种和青稞淀粉工业应用的潜在资源，淀粉特性差异巨大的众多青稞品种也为拓宽青稞应用领域提供了丰富的资源保障。本研究对部分SGAPs在性质上的鉴定和功能上的初步推断为青稞材料的筛选提供了指导，也为品质育种提供了理论参考。 Hulless barley (naked barley, Hordeum vulgare L.) is a short- season, early maturing crop with a wide range of adaptation. It has been attracting more and more attention due to its superior nutrition and extensive industrial applications. Starch is the main ingredient in hulless barley seeds which makes up 65 percent of hulless barley’s dry weight. The ratio of the amylose/amylopectin and the size, shape, distribution of starch granules can affect the physico-chemical and functional properties of starch, which may turn affect its utilizations. The Qinghai-Tibet Plateau, which is located in southwestern China, is a typical area of vertical agricultural ecosystem and one of the barley origin centers with abundant hulless barley resources. There are little reports about hulless barley in Qinghai-Tibet Plateau at present. To screen and cultivate some characteristic hulless barley can improve its value. An improved SDS-PAGE was used to identify SGAPs combination of 114 hulless barley varieties. Starch content (total starch and amylose starch) was determined according to the standard methods GB5006-85 and GB/T 15683 using PerkinElmer M341 Precision Automatic Polarimeter and UV spectrophotometer 755B respectively. The pasting properties were measured by BRABENDER Micrio Visco-Amylo- Graph 803201. The morphology of starch granules were observed and compared with Axioplan 2 Imaging light microscopy. The following were the results obtained: 1. There were 20 major SGAPs presented in 114 varieties, with the molecular weight ranged from 35.00 to 112.39 KDa, and the frequencies ranged from 12.28% to 97.37%. The number of SGAP bands in each accession varied from 10 to 14, more than half of the population had 11 bands. There were 16 distinct SGAP patterns in the 114 varieties, the Tibet hulless barley had all of the 16 types and the Sichuan hulless barley had 12 types. The results indicated the Qinghai-Tibet Plateau hulless barley had a polymorphism of the SGAPs. 2. The ranges of the total starch content, amylose content, Am/Ap, peak viscosity, pasting temperature and peak temperature of the 114 hulless barley were 51.26～66.70%,14.64～29.74%,0.17～0.42,194～1135BU,58.8～65.2 and 81.4℃～92.4, with an average of ℃59.82%, 23.60%, 0.31, 722.30BU, 62.1 and 88.8,℃℃ respectively. The distributions of the total starch content, amylose content, Am/Ap, peak viscosity, pasting temperature and peak temperature were visibly normal school. All of the amyloplasts in endosperm of varieties showed bimodal size distributions.The main starch properties of hulless barley from Tibet and Sichuan were separated and compared, the differences on amylose content and Am/Ap were obvious. 3. Eighteen accessions which had special starch properties were screened out. Five accessions with total starch content beyond 65%, including NB63-1, NB67, Ganzibailiuleng, 98221-1 and NB63; three accessions, Zangqing85, Zangqing3 and Ximala6, with the highest amylose content (>29%); five accessions with Am/Ap less than 0.25, including 99033-6, Chun Qingke, A Ba 330, Jan-03, Mi Mai114, 396, NB63-1 and 92013; seven accessions had a pasting temperature under 60, ℃meanwhile their peak viscosity beyond 1000BU and their peak temperature under 90℃，including Zu Cuochun, Jan-03, A Ba 330, Mi Mai 114, Chun Qingke, 20003 and A Qing 5. 4. There were high correlations between starch properties. Amylose content and Am/Ap were positively correlated to pasting temperature, negatively correlated to peak viscosity, negatively correlated to the number and granule size of A-type granule. Different SGAP combinations caused significant diversities in starch content and pasting properties. SGAP2, SGAP5, SGAP6 and SGAP7 may have positive effect on amylose content, Am/Ap and pasting temperature; SGAP3, SGAP9∼SGAP20 may have positive effect on peak viscosity. Our research made a comprehensive evaluation on the hulless barley starch from the Qinghai-Tibet Plateau, we can get a systemic understanding. Some special accessions were screened out can be used on the hulless barley breeding lines and industries utilization.The combination of the SGAPs may become a criterion to evaluate the hulless barley endosperm starch quality. Consequently, the results will be good information for further studies on the hulless barley.

Effect of properties of active carbon supports on performance of Pt/C catalysts in polymer electrolyte membrane fuel cell

The Pt/C catalysts were prepared with pine active carbon and Vulcan XC-72 active carbon as the supports. The performances of the Pt/C catalysts in polymer electrolyte membrane fuel cell were compared. The result indicates that the performance of Pt/Vulcan XC-72 is better than that of Pt/pine. The physical and chemical properties of the two active carbons were measured using several analysis techniques. It was found that the pore size, specific conductivity and the surface function group significantly influence the performance of the electrocatalyst.

Interaction characterization of PA1010/PP blends using PP-g-AA as compatibilizer

The morphology of polyamidelOlO/polypropylene blends was found to significantly depend upon the concentration of the compatibilizer[polypropylene-grafted-acrylic acid (PP-g-AA)]. A significant reduction in phase size was observed because of the interaction that existed between the PP-g-AA and polyamide. These interactions have been confirmed by several methods. The tensile mechanical properties and impact behavior of the prepared blends were investigated and correlated with scanning electron microscope (SEM) analysis of the fracture surfaces. It was found that PP-g-AA as the compatibilizer has a profound effect upon the properties of the blends. This behavior is attributed to a series of chemical and physico-chemical interactions taking place between the two components.

Anisotropic Deformation Of Polystyrene Particles By Mev Au Ion Irradiation

MeV An irradiation leads to a shape change of polystyrene (PS) and SiO2 particles from spherical to ellipsoidal, with an aspect ratio that can be precisely controlled by the ion fluence. Sub-micrometer PS and SiO2 particles were deposited on copper substrates and irradiated with Au ions at 230 K, using an ion energy and fluence ranging from 2 to 10 MeV and 1 x 10(14) ions/cm(2) to 1 x 10(15) ions/cm(2). The mechanisms of anisotropic deformation of PS and SiO2 particles are different because of their distinct physical and chemical properties. At the start of irradiation, the volume of PS particles decrease, then the aspect ratio increases with fluence, whereas for SiO2 particles the volume remains constant. (C) 2008 Elsevier B.V. All rights reserved.

Comparisons of static, quasi-static and dynamic 3D porous media scale network models for two-phase immiscible flow in porous media

A dynamic 3D pore-scale network model is formulated for investigating the effect of interfacial tension and oil-water viscosity during chemical flooding. The model takes into account both viscous and capillary forces in analyzing the impact of chemical properties on flow behavior or displacement configuration, while the static model with conventional invasion percolation algorithm incorporates the capillary pressure only. From comparisons of simulation results from these models. it indicates that the static pore scale network model can be used successfully when the capillary number is low. With the capillary increases due to the enhancement of water viscosity or decrease of interfacial tension, only the quasi-static and dynamic model can give insight into the displacement mechanisms.

Yb：Y2O3透明陶瓷的光学性能研究

介绍了一种基于纳米粉末真空烧结技术的新型固体激光材料——Yb：Y2O3多晶陶瓷的制备工艺、物理化学特性、能级结构和光谱特性，并与Yb：YAG单晶进行了对比．采用紧凑型有源镜激光器（CAMIL）的抽运方式，验证了Yb：Y2O3透明陶瓷的激光输出性能．在35W的最大抽运功率下，得到波长1078nm，功率10．5w的连续激光输出，斜率效率达到37．5％．实验中还观察到激光输出波长随抽运功率增加而红移以及随输出耦合镜变化而漂移的现象．Yb：Y2O3多晶陶瓷是一种理想的激光材料，不仅具有与Yb：YAG单晶同样优秀的

透红外大尺寸氧氟化物玻璃研究

锗酸盐和氟铝酸盐透红外玻璃材料作为窗口或头罩材料具有广泛的应用前景。结合锗酸盐玻璃含有少量水的问题，在成分中引入氟化物，实验表明：随氟化物含量增加．玻璃中羟基含量逐渐降低。同时通过对熔制温度的调整，获得了不合羟基的红外玻璃。针对氟铝酸盐玻璃在冷却过程中易析晶的问题，在氟化物组分中加入少量重金属氧化物TeO2，得到析晶性能好的氧氟铝酸盐玻璃。同时给出了两类红外材料的一些物理、化学性质。

P2O5-B2O3-R2O-MO-Al2O3系统玻璃物化性质的研究

以Yb^3+-Er^3+共掺的P2O5-B2O3-R2O-MO-Al2O3(R=Li，Na，K；M=Zn，Ca，Sr，Ba)系统玻璃为研究对象，分别分析了改变B2O3，的含量，以及加入不同种类的碱金属和碱土金属氧化物对玻璃的物理化学性质的影响。研究结果表明，当B2O3的含量增加，玻璃的Tg，Tf上升，热膨胀系数下降；随着修饰体阳离子半径减小，玻璃的溶解速率下降，化学稳定性变好。

稀土离子掺杂的多组分玻璃光纤

abstract {Rare earth ions doped multi-component glass fibers have important application in broad band fiber amplifier and up-conversion fiber lasers. In this paper, the mechanism and the progress of study on rare earth ions doped multi-component glass fibers in broad band fiber amplifier and up-conversion fiber lasers are introduced and reviewed. The questions and the applications of rare earth ions doped multi-component glass fibers in the future are also prospected. Based on the present research progress, it is suggested to further study the tellurite and bismuth glasses, which are used as fiber materials in broad band fiber amplifier. To up-conversion fiber laser, it is still need to further investigate novel glasses, which has low phonon energy and good physical and chemical properties.}