复合纳米材料TiO_2-SiO_2的制备及光催化降对硫磷的研究

以Ti(OC4H9)4和Si(OC2H5)4为原料,采用溶胶-凝胶法制备纳米TiO2及TiO2-SiO2复合材料.确定制备纳米TiO2-SiO2复合材料的最佳条件,即Ti∶Si=1∶0.5,煅烧温度为500℃,制备溶胶pH取5～6.通过SEM测试,发现纳米复合材料的基本粒子为分散均匀的球形颗粒状结构;XRD分析结果表明,复合材料中TiO2主要以锐钛矿晶型存在,颗粒粒径在10～30nm.光催化降解实验表明,复合纳米TiO2-SiO2材料的降解效果好于纳米TiO2,改性材料的降解效果好于未改性材料.     

尿素加压共沉淀法制备纳米ZnO-TiO2复合粉体

以Zn(NO3)2,Ti(SO4)2为原料,以尿素为沉淀剂宿主,采用高温加压共沉淀法将Zn2+及Ti4+同时沉淀出来,在热分析的基础上于一定温度下煅烧1h,制得纳米ZnO TiO2(锐钛矿型)复合粉体,其平均粒径约为45nm。结果表明,采用该方法制备复合粉体时,只有在一定的反应物配比范围内才能实现纳米ZnO与纳米TiO2的复合。     

金红石型二氧化钛纳米晶的制备

以TiCl4为原料，采用胶溶法制备出了具有金红石结构的纳米针状TiO2粉体，该针形晶体长约180nm，直径约30nm，讨论了反应时间、反应温度对TiO2粒子形貌的影响，并采用TEM和XRD等方法对晶体进行了表征。     

La2O3/Al2O3/TiO2纳米复合粉体的制备及其耐温性能的研究

以TiCl4、La2O3、Al片为原料,采用液相共沉淀法制备了La2O3/Al2O3/TiO2纳米复合粉体,采用DSC-TG、XRD、TEM技术对该纳米复合粉体进行了表征.结果表明纳米TiO2粉体经La2O3掺杂和Al2O3复合后,其耐温性能得到显著提高,该复合粉体经900℃煅烧后,粒径在32nm左右,锐钛矿含量约为77.2%(mol%)     

异丙醇水溶液加热法制备二氧化钛超细粉

以TiCl4和异丙醇为原料, 通过调节TiCl4的异丙醇水溶液的介电常数, 在存在分散剂聚乙二醇(PEG, 相对分子质量为10 000)的条件下, 采用加热水解法制备纳米TiO2粉末. 采用X射线衍射仪, 扫描电镜等对影响TiO2的产率、粒子大小和形貌的因素以及TiO2的光催化性能进行研究. 研究结果表明, 异丙醇水溶液的组成对TiO2产率、粒子大小和形貌的影响较大;PEG分散剂可明显改善TiO2的形貌. 当异丙醇与水的体积比为3, 并加有PEG分散剂时, 获得的纳米TiO2粉末呈球形, 产率为83%. 在700 ℃时煅烧4 h得到的TiO2的粒径约为80 nm, 具有较高的光催化活性.     

纳米固体超强酸SO2-4/TiO2的制备及其催化活性

以廉价的无机盐TiCl4为原料,采用溶胶-凝胶法结合超临界流体干燥技术制备出纳米TiO2粉末,经硫酸溶液浸泡、活化后制成纳米固体超强酸SO2-4/TiO2.着重探讨了纳米固体超强酸的制备条件,并将其用于乙酸正丁酯的合成反应以考察其催化活性.结果表明:该法制备的纳米固体超强酸SO2-4/TiO2具有很强的催化活性,且制备成本低,反应时间短,酯化率高.     

纳米固体超强酸SO4^2-/TiO2的制备及其催化活性

以廉价的无机盐TiCl4为原料,采用溶胶-凝胶法结合超临界流体干燥技术制备出纳米TiO2粉末,经硫酸溶液浸泡、活化后制成纳米固体超强酸SO4^2-/TiO2.着重探讨了纳米固体超强酸的制备条件,并将其用于乙酸正丁酯的合成反应以考察其催化活性.结果表明：该法制备的纳米固体超强酸SO4^2-/TiO2具有很强的催化活性,且制备成本低,反应时间短,酯化率高.     

纳米固体超强酸SO_4~(2-)/TiO_2的制备及其催化活性

以廉价的无机盐TiCl4为原料,采用溶胶-凝胶法结合超临界流体干燥技术制备出纳米TiO2粉末,经硫酸溶液浸泡、活化后制成纳米固体超强酸SO24-/TiO2.着重探讨了纳米固体超强酸的制备条件,并将其用于乙酸正丁酯的合成反应以考察其催化活性.结果表明:该法制备的纳米固体超强酸SO24-/TiO2具有很强的催化活性,且制备成本低,反应时间短,酯化率高.     

In2S3纳米结构微球的水热制备及其发光性质

报道一种以氧化铟、盐酸和硫脲为原料,采用水热法制备纳米片和纳米颗粒自组装In2S3微米球的简易方法.采用扫描电镜(SEM)、X射线衍射仪(XRD)和透射电子显微镜(TEM)对产物进行表征.SEM结果表明:于140 ℃、恒温24 h得到In2S3纳米片自组装微球,直径3～4 μm,纳米片厚度约20 nm,大小为0.5～0.8μm,于160℃恒温24 h得到In2S3纳米颗粒自组装微球.直径2.5～10 μm,纳米颗粒大小为20～200 nm.XRD结果表明制备的产物均为纯相立方晶相的In2S3;发光性能研究表明两种微球具有发冷光的性质.     

Fe_2O_3/TiO_2/蒙脱土光催化剂的制备及光催化性能研究

以TiCl4为原料采用溶胶凝胶法结合超临界流体干燥法(SCFD),制备了纳米级Fe2O3/TiO2/蒙脱土复合光催化剂.以亚甲基蓝为反应模型,对催化剂的催化活性进行了评价.结果表明,3 h亚甲基蓝降解率99.3%.采用XRD,TEM,UV和ICP等手段进行了表征,TiO2以锐钛矿型形式存在,催化剂粒径在15~21 nm.比较不同制备方法制得的复合催化剂,得出超临界干燥法制备的光催化剂具有粒径小,分散性好,光催化活性高等特点.     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to