纳米钡铁氧体的柠檬酸盐法制备与吸波性能

采用柠檬酸盐溶胶-凝胶法制备钡铁氧体.试验表明:缓慢加热至650℃,即得到结晶良好的六角磁铅型晶体BaFe12O19针状纳米颗粒,粒径50 nm,同时伴生有尖晶石型γ-Fe2O3,BaFe2O4及α-Fe2O3相;加热温度升高,BaFe12O19相增多,伴生相减少;至800℃,基本为钡铁氧体BaFe12O19晶体;快速加热至800℃,固相反应产物仍为BaFe12O19,但晶体颗粒粗大.在所试验的1-6 GHz范围内,钡铁氧体吸波性能随着微波频率的增高而加强,最佳吸波频率在6 GHz以上.     

柠檬酸溶胶凝胶法合成BaAl_(12-x)O_(19)∶Mn_x荧光粉

以AlCl3·6H2O,BaCO3和MnCO3为原料,分别溶于去离子水和柠檬酸中,采用溶胶凝胶法合成了BaAl12xO19∶Mnx荧光粉。IR分析表明,干凝胶具有柠檬酸盐结构。XRD分析表明,1200℃煅烧,粉末中的主要成分为BaAl2O4,1400℃煅烧,粉末为BaAl12xO19∶Mnx和BaAl2O4的混合物,此时仍残余部分BaAl2O4,1500℃煅烧能合成单相BaAl12xO19∶Mnx,相对于传统的高温固相合成法降低100～300℃。SEM分析表明,晶粒较小且具有片状结构。碱土金属离子Mg2+,Ca2+和Sr2+的掺杂对BaAlO∶Mn荧光粉的发光性能有一定的影响。     

M型钡铁氧体的制备及其吸波性能表征

采用溶胶凝胶自蔓延合成工艺制备了六角晶系M型钡铁氧体微粉BaFe12O19.用X射线衍射仪,振动样品磁强计和矢量网络分析仪对粉末的结构、磁性能以及电磁波吸收性能进行了表征.结果表明,BaFe12O19既能产生磁损耗,又能产生介电损耗,是一种宽频微波吸收材料.     

尖晶石型MAl2O4(M=Ni、Mg)纳米粉体的溶胶凝胶法制备及表征

采用溶胶-凝胶法合成了MAl2O4（M=Ni、Mg）尖晶石纳米粉体，无水乙醇溶解摩尔比nM（NO3）2∶nM（NO3）3=1 ∶ 2，草酸作络合剂，加热搅拌得到湿凝胶，继续干燥得到干凝胶，随后对于凝胶在不同温度下进行焙烧，得到了粉体状产物．用TG、DSC技术对前躯体干凝胶进行热分析，对煅烧粉末进行了XRD、TEM表征，并考察了煅烧温度对MAl2O4晶化程度的影响．实验结果表明：该方法制备单相且晶化程度较高的尖晶石型MAl2O4纳米粉体所需温度为800℃，比微波反应法合成温度降低200℃，比铝单醇盐Sol-Gel法降低100℃．     

船舶尾气中NO臭氧氧化研究——反应温度和尾气中碳氢化合物含量的影响

用管式反应器试验研究了反应温度和[O3]/[NO]对臭氧氧化NO的影响。结果表明,O3/N2/O2体系在常温、200℃和275℃下均不发生反应,N2不能被O3氧化;在O3/NO/N2/O2体系中,NO主要氧化为NO2,当[O3]/[NO]=1,反应温度分别为常温和200℃时,NO氧化率都达到100%,而在275℃时,NO氧化率只有72%,表明反应温度影响显著,原因主要与较高温度下O3分解加快有关。O3在不同温度下的分解试验发现,O3在常温下分解很慢;200℃时分解加快,在反应器中停留9s时,O3的分解率为59%,而275℃时分解更快,在反应器中停留9s时,O3的分解率为80%。NO的氧化率与[O3]/[NO]成线形相关,C2H4对NO氧化成NO2有促进作用。在[O3]/[NO]=0.6,反应温度分别为常温、200℃和275℃时,加入400×10-6C2H4,NO氧化率率由61%、62.6%和38.5%分别提高到63.8%、63%和41%。C2H4的促进机理,可能是O3与C2H4发生一系列反应生成强氧化性的过氧自由基CH3O2和HO2,这些自由基参与了NO的氧化反应。     

铁酸钡复合超细微粒的制备和性能研究

以FeCl3·6H2 O、FeSO4·7H2 O和BaCl2 ·2H2 O为原料 ,采用固相反应法和微乳液 -沉淀法制备铁酸钡超细微粒。并进行了XRD、TEM、IR分析和磁化率的测定 ,结果表明 ,微粒的主要成分为α 型BaFe2 O4,平均粒径分别约为 2 38nm和 2 5 5nm ,单个微粒的粒径分别约为 3 1 4nm和2 65nm ,每个复合微粒中分别含有 72和 1 34个铁酸钡粒子 ;磁化率的大小随磁场强度、灼烧温度的增加而增大。     

镧掺杂铁酸铋纳米线的溶胶凝胶氧化铝模板法制备

以Bi(NO3)3·5H2O、Fe(NO3)3·9H2O和La(NO3)3·6H2O为原料,乙二醇甲醚[2-methoxyethanol,C3H8O2]为溶剂,冰乙酸[C2H4O2]为络合剂,采用溶胶凝胶氧化铝模板法在600℃退火制备了Bi0·85La0·15FeO3(BLFO)纳米线.利用X射线(XRD)和扫描电子显微镜(SEM)研究了产物的物相和形貌.结果表明合成的产物为BLFO纳米线,直径约100-200 nm,长度约5-50μm.不同退火温度XRD研究表明600℃制备了纯相BLFO,低于文献报道的铁酸铋纳米结构合成温度.     

水热法制备碳纳米管/钡铁氧体复合材料

采用水热合成法对碳纳米管(CNTs)进行酸化处理,并且合成钡铁氧体包覆CNTs的新型纳米复合材料,使用红外光谱仪(FT-IR)对酸化CNTs的表面官能团进行表征,使用X线衍射仪(XRD)与扫描电子显微镜(SEM)对复合材料的物相和形貌进行表征。结果表明:60℃水热法酸化能有效地除去CNTs中的无定形杂质,并在表面引入大量极性基团;在200℃下,Ba2+与Fe3+摩尔比在3∶12和4∶12时,水热合成了结晶程度较高的BaFe12O19/CNTs复合材料,CNTs表面均匀地覆盖了一层BaFe12O19;随着反应体系中Ba2+比例的升高,BaFe12O19的结晶程度有相应提高。     

pH值和煅烧温度对莫来石生成的影响

以溶胶凝胶法为基础,采用正硅酸乙酯(C8H20O4Si)、硝酸铝(Al(NO3)3·9H2O)为主要原料,借助X射线衍射仪进行检测,系统研究了pH值、煅烧温度对生成3∶2型莫来石以及生成过程的影响。结果表明：莫来石凝胶介于单相凝胶和双相凝胶的混合尺度,pH值在4~10范围内均可生成莫来石,煅烧温度为1175 ℃时出现明显的莫来石化;pH=4时,不利于无定形硅的转化;在pH值为5~9范围、煅烧温度1200 ℃时完全莫来石化,且生成的莫来石结晶度总体变小,晶胞参数上下波动。莫来石的生成经历了无定形硅和铝的氧化物到铝硅尖晶石再到莫来石的过程。     

均匀沉淀法制备纳米α-Al2O3粉

以Al（NO3）4.9H2O、NH4HCO3和C6H8O7.H2O为主要原料,采用均匀沉淀法制备纳米α-Al2O3粉。研究了表面活性剂和过滤方法对前躯体转晶温度的影响,采用XRD和TEM对粉体进行表征。结果表明：在前躯体制备过程中加入表面活性剂PEG6000可使前躯体的转化温度降低75℃,常压过滤比用真空抽滤的前躯体转化温度低25℃,前躯体转化为α-Al2O3相的最佳煅烧温度是1050℃;制备的α-Al2O3是粉体分散性良好的片状晶体,呈两极分布状态,小颗粒平均粒径约20nm,大颗粒的宽约50～80nm、长约100～200nm。     

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…     

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。     

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     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.     

Tracking data management using topology of moving object database system for moving object constrained trajectory in LBS application

Advances in wireless technologies and positioning technologies and spread of wireless devices, an interest in LBS (Location Based Service) is arising. To provide location based service, tracking data should have been stored in moving object database management system (called MODBMS) with proper policies and managed efficiently. So the methods which acquire the location information at regular time intervals then, store and manage have been studied. In this paper, we suggest tracking data management techniques using topology that is corresponding to the moving path of moving object. In our techniques, we update the MODBMS when moving object arrived at a street intersection or a curved road which is represented as the node in topology and predict the location at past and future with attribute of topology and linear function. In this technique, location data that are corresponding to the node in topology are stored, thus reduce the number of update and amount of data. Also in case predicting the location,because topology are used as well as existing location information, accuracy for prediction is increased than applying linear function or spline function.