纳米二硫化钼的制备及AFM表征

利用硫化铵与钼酸铵为反应物,在适宜的分散剂与超声帮助下,通过快速液相沉淀法制备出三硫化钼,再通入高纯氢气,将三硫化钼加热分解,制备出二硫化钼。X射线衍射结果表明获得的三硫化钼是典型的非晶态MoS3,二硫化钼为2H-MoS2;通过原子力显微镜发现,制备的二硫化钼的平均粒径为70nm左右。     

Ni-B非晶纳米粉末微电极上丙醇的电氧化

在水溶液体系中,以化学还原法制得Ni-B非晶态合金纳米颗粒.应用循环伏安法,研究碱性介质中Ni-B非晶态合金纳米粉末微电极上丙醇的电催化氧化,并运用稳态极化曲线测定Ni-B非晶态合金纳米粉末微电极上丙醇的电催化氧化动力学参数.结果表明,Ni-B非晶态合金纳米粉末微电极对碱性溶液中丙醇的氧化具有很高的电催化作用.碱性介质中的Ni-B非晶态合金纳米粉末微电极上,丙醇的电催化氧化速率明显高于高择优取向(220)的镍电极.     

微波等离子体法制备纳米钼粉

阐述用微波等离子法制备纳米金属钼粉的原理,探讨了此法制备纳米钼粉颗粒的工艺与影响因素,并以羰基钼为原料制得纳米级钼粉,平均粒径小于５０ｎｍ,还研究了钼粉在空气中的热稳定性。     

W-Ni-Fe复合氧化物粉末的还原工艺

利用两阶段还原法对W-Ni-Fe复合氧化物粉末进行还原,控制还原工艺的参数制得纳米级W-Ni-Fe复合粉末.采用XRD对粉末进行物相分析,并计算晶粒尺寸;采用高倍SEM观察粉末形貌;对复合粉末的费氏粒度、比表面面积、氧含量等进行测定与分析,研究还原温度和还原时间对粉末性能的影响.研究结果表明:当还原温度高于600℃时制得的复合粉末由W和(Ni,Fe)两相组成;粉末颗粒呈球形或近球形;还原温度和还原时间都对W-Ni-Fe复合粉末的性能有显著影响,当还原温度为700℃,还原时间为90 min时,制备的颗粒为平均费氏粒度低于0.65μm,平均BET粒度小于100nm,晶粒粒径小于30 nm,粉末氧含量小于0.23%的纳米级W-Ni-Fe复合粉末.     

Fe-Cr-W复合氧化物粉末共还原工艺研究

通过H2-CO共还原法对Fe-18Cr-9W复合氧化物粉末进行还原,控制还原工艺的参数制得纳米级Fe-18Cr-9W复合粉末.采用XRD对粉末进行物相分析,并计算晶粒尺寸;采用高倍SEM观察粉末形貌;对复合粉末的费氏粒度、比表面面积、氧含量等进行测定与分析,研究还原温度和还原时间对粉末性能的影响.研究结果表明:当还原温度高于650℃时制得的复合粉末由Fe和Fe-(Cr,W)两相组成;粉末颗粒呈球形或近球形;还原温度和还原时间都对Fe-18Cr-9W复合粉末的性能有显著影响,当还原温度为700℃,还原时间为90 min时,制备的颗粒为平均费氏粒度低于0.58μm,平均BET粒度小于80 nm,晶粒粒径小于50 nm,粉末氧含量小于0.14%的纳米级Fe-18Cr-9W复合粉末.     

非晶态MoS_3制备方法的改进与其电化学特性的研究

本文报导了用改进的水溶液酸化沉淀法制备非晶态三硫化钼。并对该材料的导电特性、用作锂电池阴极材料的放电特性以及循环伏安特性进行了研究。     

成果推广

复合纳米稀土永磁复合纳米稀土永磁是一种新型永磁材料。其工艺过程是采用金属液态快速凝固技术制得非晶态或微晶态合金 ,再经过控制热处理获得的合金粉末。将这种磁性粉末配入热固性或热塑性树脂或橡胶 ,通过压制成型、挤出成型和注射成型等方法制成磁体 (也称为粘结磁体 )。这种稀土永磁合金中的显微组织特征是由晶粒度为纳米级的硬磁性相和软磁性相复合而成。其磁性特征是具有剩磁增强效应 ,即各向同性磁体其剩磁比Ｍｒ/Ｍｓ70 5 .经过材料基础研究、中试研究和开发 ,已能制备出高矫顽力和高剩磁两大类型纳米晶复合磁体 ,性能达到世界先…     

聚乙烯/纳米二硫化钼复合材料电性能

采用熔融共混的方法制得聚乙烯／纳米二硫化钼复合材料，研究该复合材料的电性能及其微观形貌,结果表明，当二硫化钼质量分数大于15％时，体系的电阻明显下降，复合材料的渗滤阀值为15％；二硫化钼均匀分散于聚乙烯基体中，二硫化钼导电颗粒相互接触，形成链状导电网络．     

用激光化学反应制备非晶态TiO2及其性质初探

用ＴＥＡ ＣＯ２中激光聚焦辐照ＴｉＣｌ４＋Ｏ２体系，制得了非晶态ＴｉＯ２粉末。对粉末作了ＸＲＤ，ＸＰＳ，ＴＧＡ，ＤＴＡ和ＴＥＭ分析。并研究了制得非晶态ＴｉＯ２的微观过程，讨论了它的一些特殊性质。     

高温高压下一些层状硫化物的合成

在４．０×１０９Ｐａ，１０２５℃条件下合成三硫化铌、二硫化钨和二硫化钼。高压合成是伴随扩散的动态过程，压力对反应动力学有较大影响，明显缩短了反应时间。高温高压合成的三硫化铌属单斜晶系，二硫化钨、二硫化钼属六方晶系。     

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).     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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