纳米CuAl_2-Al复合微粉热稳定性的研究

作者根据惯性约束聚变(ICF)靶材料研究的需要,采用自悬浮定向流法制备了金属间化合物CuAl2-Al纳米复合微粉.经TEM和XRD检测表明所制备的纳米颗粒基本呈球形,粒径分布在30~50nm之间,颗粒的主要组成相为CuAl2,并有少量的Cu9Al4和Al.CuAl2复合纳米微粒热稳定研究所采用的退火方案基于DTA实验数据,实验表明在DTA曲线中的548℃和769℃处的吸热峰对应着Cu9Al4向CuAl2的相转变,并伴随着一定程度的晶粒尺寸长大,并且热处理前后样品的相结构和晶粒尺寸变化的结果表明,所制备的CuAl2纳米复合微粒具有良好的热稳定性,可以用于780℃甚至更高温度下进行加工.     

铝合金纳米粉末中相生成规律的初步研究

采用蒸发凝聚法制备了Al-M(M=Cu,Fe,Cr,Mn)合金纳米粉末,研究了粉末中的相生成规律.实验结果表明,纳米粉末的相组成及其相对含量主要是由母合金的成分决定的.在Al-Cu合金纳米粉末中生成的合金相有-θCuAl2,γ2-Al4Cu9,-βAlCu3,Cu在Al中的最大固溶度明显高于Al-Cu平衡相图上的值.在Al-Fe合金纳米粉末中生成了Al13Fe4和FeAl2相.在Al-Mn和Al-Cr合金纳米粉末中则分别生成了-βMnAl6,η2-Al8Mn5相和Al13Cr2,Cr9Al17相.纳米颗粒的组织和形貌与纯金属纳米粒子的差异很大.讨论了合金纳米粒子的形成机理.     

纳米TiO2复合氧化物的制备及其光催化降解对硝基苯胺的性能研究

采用超声化学共沉淀法制备了含Ti、Cu和Cr的复合氧化物，并对纯TiO2进行超声处理．用ICP，XRD，BET，TEM，SEM等手段对所制备的氧化物进行了表征并考察了它们光催化降解对硝基苯胺的性能．只含Cu和Cr的复合氧化物光催化活性较低；掺杂Cu和Cr的TiO2复合氧化物的光催化活性高于纯锐钛型TiO2；超声处理能够提高TiO2的光催化性能．XRD表征结果表明，不含Ti的复合氧化物的CurD物相和CuCr2O4物相主要衍射锋相互重叠，而含TiO2的复合氧化物中CuD和CuCrO4物相衍射峰弱，且强度随着TiO2的含量增加而减弱．BET，SEM和TEM结果表明，光催化活性高的复合氧化物的比表面积大，且其颗粒尺寸为纳米级，纳米颗粒堆积形成二次孔．     

Cu-Zn-Al_2O_4复合粉末的机械合金化反应

采用X射线衍射仪、电子扫描、TEM透射电镜和DTA差热分析等手段,研究了在Ar气氛保护下Cu-Zn-Al2O4粉在高能球磨过程中发生的机械合金化反应,分析了不同球磨时间对α-Cu的晶格常数和粉体成分、形貌、热稳定性的影响.结果表明:随着球磨时间延长,Cu的晶格常数不断变化,晶粒尺寸可细化至22nm;高能球磨120h后,可获得纳米氧化铝颗粒弥散分布的Cu-Zn复合粉末;Cu-Zn-Al2O4混合粉在700-850℃之间加热时,会出现Al2O4的晶化转变,球磨时间越长,Al2O4晶化转变温度越高,固溶体的熔点温度降低,球磨60h后熔化温度可降为1045℃.     

沉积于硅纳米孔柱阵列上的铜纳米颗粒退火行为研究

以具有规则表面形貌的硅纳米孔柱阵列（Silicon Nanoporous Pillar Array,Si-NPA）作为还原性衬底和组装模板,采用浸渍技术制备了铜／Si-NPA（Cu／Si-NPA）纳米复合体系。将新鲜制备的Cu／Si-NPA样品分别在400℃、600℃和800℃氮气气氛中退火,对比研究了沉积于Si-NPA衬底之上的铜纳米颗粒的表面形貌、晶粒尺寸随温度的演化规律。在较低、较高温度下退火时,铜纳米颗粒所发生的定向迁移、颗粒长大及中心凝聚现象分别在Ostwald成熟理论和团簇扩散理论的框架下得到了解释。     

AlN和Al2O3纳米颗粒增强铜基复合材料

用粉末冶金法制备了Cu/AlN和Cu/Al2O3两种复合材料,研究了两种纳米颗粒含量对复合材料性能的影响和复合材料的软化温度,并探讨了相关机理,比较了AlN和Al2O3纳米颗粒的增强效果.结果表明,在烧结过程中,弥散分布在铜基体中的AlN和Al2O3纳米颗粒细化了晶粒;随着复合材料中AlN和Al2O3质量分数的增加,材料的密度和导电性都呈下降趋势,而硬度出现极大值;两种复合材料的软化温度均达到700℃,远远高于纯铜的软化温度(150℃),从而提高了材料的热稳定性;综合各种因素考虑,AlN纳米颗粒对铜基体的增强效果要优于Al2O3纳米颗粒.     

机械化学还原法制备Al_2O_3-Mo_3Si/Mo_5Si_3纳米复合粉体

以MoO3、Si粉和Al粉为原料,采用机械化学还原法制备了Al2O3-Mo3Si/Mo5Si3纳米复合粉体.利用X射线衍射(XRD)、激光粒度分析仪(LPS)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)和差热-热重分析(DTA-TG)等对复合粉体和球磨过程中粉体的固态反应过程进行表征.结果显示,MoO3-Si-Al混合粉体球磨5h后转变为Al2O3-Mo3Si/Mo5Si3复合粉体,反应为机械诱导的自蔓延反应.球磨20h后,Mo3Si、Mo5Si3和Al2O3的晶粒尺寸分别为27.5、23.3和31.8nm,产物具有纳米晶结构,粉体平均粒度为3.988μm,颗粒呈球形,分布均匀.DTA分析表明,复合粉体在机械化学反应过程中首先发生MoO3和Al之间的铝热反应,之后将发生一系列Mo和Si之间的反应,生成Mo5Si3和Mo3Si.     

纳米晶CuAl2O4的合成、表征及光催化性能研究

本文通过有机物前驱体法制备尖晶石型CuAl2O4纳米晶,利用TG-DTA、XRD、TEM、UV-VIS等分析手段表征了前驱体和CuAl204粉体。结果表明,CuAl2O4在热处理中出现了CuO中间相,经900℃焙烧得到单相CuAl2O4。800℃的CuAl2O4的禁带宽度为1.92 eV,颗粒直径在20～40 nm,具有最佳的光催化活性：在紫外光辐照2h对甲基橙的降解率为99%,在可见光和太阳光下也具有较高的活性。     

高压方法合成α″-Fe16N2

用同步还原氮化技术制备的Fe、Fe4N混合纳米颗粒和Fe／Fe4N核壳复合纳米颗粒分别作为前驱体，再经高压加温后合成了含有高饱和磁化强度的α″-Fe16N2相，采用X-射线衍射仪(XRD)表征样品的结构，研究了高压下温度及前驱体对合成α″-Fe16N2相的影响，其磁性用振动样品磁强计(LakeShore VSM)在室温下进行测量，实验结果表明：混合的Fe-Fe4N纳米颗粒和复合的核壳结构Fe／Fe4N颗粒在高压下均有可能发生相变，压力为6GPa时，当温度在400℃、500℃Fe和Fe4N仅仅发生晶粒细化，没有相变；当温度高于600℃时，可使Fe和Fe4N两相之间发生固相反应，产生了α″-Fe16N2等新的相．但用混合的Fe-Fe4N作为前驱体时会发生氧化，而高压复合的Fe／Fe4N前驱体则不会发生氧化．采取不同的氮化时间，可获得不同比例的α-Fe/γ′-Fe4N前驱体，在高温高压作用下可得到不同含量的α″-Fe16N2。本对实验结果也进行了初步解释。     

纳米氧化锌的微乳液法制备及表征

纳米ZnO可用于毛织物的后整理，使织物具有抗菌除臭、消毒、抗紫外线的功能．采用TritonX-100／正庚醇／正辛烷／盐水微乳液体系，以一定盐浓度的硝酸锌（Zn（NO3）2）水溶液（A）与碳酸钠（Na2CO3）水溶液（B），通过两个乳液混合的方法，制备出氧化锌超细微粒．并用差热分析（DTA）、透射电镜（TEM）和X射线衍射仪对其进行表征分析．实验表明，30℃时，以A型微乳液与B型微乳液通过乳液混合搅拌的反应方式制备出纳米ZnO微粒的前驱体，经80℃真空干、燥约5h后，在350℃下煅烧2h，得到了平均粒径约为10nm的超细ZnO粉末，且微粒粒径分布均匀、团聚少，多数为球状颗粒．     

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.     

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.     

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.