ZnO/Sm-TiO_2纳米粉体制备及光催化性能

以钛酸四正丁酯为钛源,采用水热法制备Sm掺杂的纳米Sm-TiO2粉体.将ZnO引入到SmTiO2粉体中得到ZnO/Sm-TiO2粉体,研究不同焙烧温度、ZnO添加量对催化剂光催化性能的影响,确定最佳掺杂量及最佳焙烧温度;利用X射线衍射仪(XRD)、傅里叶变换红外光谱(FTIR)、扫描电镜(SEM)等测试手段对产物进行表征.结果表明:Sm-ZnO共掺杂能抑制TiO2由锐钛矿相向金红石相的转变,拓宽光催化剂的光谱响应范围,抑制了纳米晶体的生长;经掺杂后的TiO2纳米粉体的光催化性能有了明显的提高,在温度为400℃,Sm的掺杂质量百分比为0.2%,ZnO与TiO2的掺杂比为1∶8时所得样品的光催化效果最佳,甲基橙降解率可达96.34%.     

稀土离子(Sm~(3+),La~(3+))掺杂纳米TiO_2光催化性能研究

以钛酸四丁酯和稀土氧化物Sm2O3、La2O3为原料,分别制备了掺杂稀土离子Sm2+和La3+的纳米TiO2光催化剂,分别进行了两种离子掺杂纳米材料在甲基橙溶液中的光催化降解实验,通过对制备条件优化,研究了光降解条件对降解效果的影响.结果表明:La2+掺杂纳米TiO2材料的光催化活性要优于Sm3+掺杂纳米TiO2材料.     

Ag纳米颗粒修饰对La掺杂ZnO纳米棒光催化性能的影响

采用水热法和光沉积制备Ag纳米颗粒修饰的La掺杂ZnO纳米棒,并通过光催化降解甲基橙(MO)溶液,考查了La掺杂浓度和Ag修饰对ZnO纳米棒光催化性能的影响.结果表明:La掺杂和Ag修饰能够提高ZnO纳米棒的光催化性能.La掺杂改变了ZnO纳米棒的结晶质量,La—O键的形成使ZnO晶体的本征吸收边红移且吸收强度增加,同时,La掺杂可提高ZnO电子浓度和形成杂质能级,Ag纳米颗粒的修饰提高了La掺杂ZnO光生电子与空穴对的分离效率,增加了载流子的寿命.与纯ZnO纳米棒相比,La掺杂和Ag修饰的ZnO纳米棒表现出良好的光催化性能.     

Al掺杂ZnO纳米颗粒的光催化性能

溶胶-凝胶法合成ZnO和Al掺杂ZnO(AZO),通过降解甲基橙(MO)评价纳米颗粒的光催化性能.与纯ZnO相比,Al掺杂使ZnO晶粒尺寸减小,比表面积增加.此外,Al掺杂诱发高浓度缺陷,从而调整ZnO晶体的能带结构.电子从导带跃迁到低能态的缺陷能级,能量差与可见光的能量吻合,从而大幅提高光催化过程中对可见光的利用率.AZO样品在可见光范围内都表现出优异的光催化性能,并且a(Al)=3%掺杂的ZnO表现出最佳的光催化性能,60 min降解效率为94%.     

ZnO纳米材料抑菌活性研究

为了探讨纳米材料的尺寸和浓度对其抑菌活性的影响,选用两种尺寸不同的ZnO纳米材料,通过TEM、SEM、XRD和Raman表征纳米材料的形貌、尺寸、晶体结构和化学成分,通过抑菌活性测试比较两种材料的抑菌性能.结果表明,ZnO纳米材料A的尺寸比B小,均属于六方晶系,具有纤锌矿结构,晶体质量良好.抑菌实验表明,两种纳米ZnO材料均对金黄色葡萄球菌和大肠杆菌具有明显的抑制效果,浓度增大,抑菌圈直径也增大,即纳米材料浓度与抑菌效果正相关.浓度相同时,材料A比B显示出更强的抑制作用.相比之下,尺寸小的纳米ZnO材料是更有效的文物保护抑菌剂.     

ZnO纳米管的制备及光催化性能研究

采用"化学刻蚀法"成功将制得的ZnO纳米棒(ZnO nanorods,ZnO NRs)转换成ZnO纳米管(ZnO nanotubes,ZnO NTs).利用X射线衍射仪(X-ray diffraction,XRD)、扫描电子显微镜(scanning electron microscope,SEM)、透射电子显微镜(transmission electron microscope,TEM)、光致发光谱(photoluminescence,PL)等表征手段对样品的结构、形貌和性能进行了测试表征.实验结果表明,制得的ZnO NRs和ZnO NTs均为具有六方纤锌矿结构的纳米材料.PL结果显示,大比表面ZnO NTs的形成有效地抑制了光生载流子的复合,并产生了更多的表面缺陷,这将会对材料的光催化性能产生影响.紫外光下,ZnO NTs对有机染料罗丹明B的光催化降解效率优于ZnO NRs.     

模拟太阳光照射下Fe掺杂与Ag复合ZnO纳米材料的光催化性能研究

利用高分子网络凝胶法制备了Fe掺杂与Ag复合的ZnO纳米复合材料.采用X射线衍射(XRD)、扫描电子显微镜(SEM)和光电子能谱(XPS)研究分析了样品的微结构和形貌与成分变化,采用光致发光(PL)和紫外-可见吸收谱(UV-vis)对样品的光学性质进行表征.在模拟太阳光照射下,以亚甲基蓝为光催化反应模型化合物,考察了掺杂对光催化活性的影响.无论是单复合Ag还是Fe掺杂后再Ag复合,光催化性能都优于ZnO.特别是同时进行Fe掺杂与Ag复合的ZnO,其光催化性能显著提高.结合微结构表征和光学测试,对ZnO及掺杂ZnO的光催化机理进行了讨论.     

ZnSe纳米颗粒的制备及光学性能研究

以硝酸锌和硒粉为源物质,以乙二醇和氢氧化钠的水溶液为反应介质,采用水热法制备了ZnSe纳米颗粒,利用差热分析仪(TG-DTA)、X射线衍射仪(XRD),扫描电子显微镜(SEM)和光致发光谱(PL)对产物进行热稳定性、结构、形貌和光学性能表征.差热结果表明ZnSe在常温下具有一定稳定性,直到450℃以上时在空气中可转化为ZnO纳米材料.XRD和SEM研究结果表明,纳米颗粒具有闪锌矿结构并且随着反应时间的增加颗粒尺寸有所增大.PL测试显示近带边发射峰较强,这说明产物的结晶状况良好,并且具有较好的光致发光性能.     

Ce~(4+)掺杂ZnO纳米材料的制备及其光催化性能研究

采用水热法通过构建具有MOFs结构的Ce~(4+)掺杂沸石咪唑酯骨架材料ZIF-8前驱体,再高温热解制备了Ce/ZnO光催化纳米材料,利用X射线衍射(XRD)、扫描电镜(SEM)和能谱(EDS)、比表面积测定(BET)对样品结构进行表征.以罗丹明B(RhB)染料为目标降解物,考察了不同的Ce掺杂量及煅烧温度对Ce/ZnO的结构形貌和光催化性能的影响.实验结果表明,适量Ce掺杂后,Ce/ZnO粒径均一性与分散性更好,且颗粒更小,比表面积增大,可显著提高其光催化活性和光催化稳定性,煅烧温度过高会出现烧结现象促使光催化性能降低. Ce掺杂量为2%(质量分数),煅烧温度为600℃条件下制得的Ce/ZnO光催化性能最佳,对RhB光照降解1 h后降解率超过99%,4次循环催化后降解率仍达97.89%.     

铈掺杂氧化锌六角杯型结构纳米光催化剂的制备及其性能研究

通过微波辅助水热技术制备了新颖的六角杯型铈掺杂氧化锌(Ce/ZnO)纳米光催化材料.利用XRD,SEM,XPS,UV-Vis DRS等手段表征了上述材料的结构、形貌及光学特性.讨论了Ce/ZnO六角杯型结构可能的生长机理.实验结果表明:光催化降解罗丹明B(RhB)的反应中,稀土Ce掺杂可以拓宽ZnO的光吸收范围,并进一步提高其光催化活性;不同的Ce掺杂浓度对Ce/ZnO光催化性能的影响存在一定的差异;Ce/ZnO在模拟太阳光激发下,经循环使用6次之后RhB的催化降解效率仍非常可观.该样品性能的提高得益于二元异质复合材料高效的光生电子和空穴的分离能力.     

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