微纳米球形颗粒之间的毛细力研究

两球形颗粒之间的相互接触问题是研究微机械系统中纳米接触问题的一个重要课题.在微尺度下,毛细液桥现象尤为重要,在观测纳米级物体的相互接触作用力中不可避免地要研究微纳米尺度的液桥问题.本文采用液桥力学平衡、环形近似、体积守恒方法,建立了微纳米球形颗粒之间的液桥模型,通过精确的数学求解,分析球形颗粒的接触角对于毛细作用力和液桥的断裂高度的影响.模拟结果发现,当2个颗粒之间的毛细力作用都很小时,液桥的断裂高度随着接触角的增加而减小,当其中一个颗粒的毛细力作用比较大时,断裂高度随着接触角的增大而增大,接触角的大小对于液桥的断裂高度有直接的决定作用.研究结果为计算预测微观颗粒之间的相互作用力、探索纳米颗粒间的相关特性和机理提供参考.     

岩石剪切面纳米粒子层的近期研究进展

20世纪90年代,在各类岩石剪切面中相继发现纳米级和微米级超微粒子结构,近期结合力学、物理学成因研究又有新的进展.在超微观上,通过国内外的实例实测,从岩石剪切面纳米粒子层赋存展布的普遍性,结构特征的层次性,成因机制的非线性和功能效应的多样性四个方面,进行简要阐述,萃取更多信息.进而初步揭示了剪切摩擦黏性发育与纳米粒子形成间的共生关系,和剪切运动中岩石的分离、分凝和分层作用首先由纳米粒子层的滑移启动开始的.并分析了岩石塑性流变实质上是超微粒子(纳米-微米级磨粒)的运动,以及岩石剪切面纳米粒子层一些特殊的物理和化学地质作用等.诚然,纳米粒子层蕴涵的信息是丰富的,该项研究还处于起步开拓阶段,仅试图为构造地质学和相关学科领域提出新的理念和新的探讨平台.     

血清白蛋白与银纳米粒子的相互作用及包覆

用透射电镜、紫外-可见光谱研究银纳米粒子与血清白蛋白的相互作用及其相关效应，透射电镜观测到血清白蛋白对银纳米粒子的包覆，表面等离子共振吸收峰的研究表明，静电力和亲水力是血清白蛋白与银纳米粒子之间的主要作用力；血清白蛋白对锒纳米粒子最低包覆比在10^-5～10^-6之间。     

纳米粒子嫁接嵌段共聚物体系的自组装模拟研究

基于非格点模型,结合自洽场理论中的能量表达式,运用蒙特卡洛模拟方法对嫁接有嵌段共聚物的纳米粒子进行自组装模拟研究。每一个纳米粒子表面上嫁接有多条相同性质的AB嵌段共聚物,其中组分之间存在一定的相互作用。通过改变组分之间的相互作用来对纳米粒子-嵌段共聚物体系的自组装结构进行研究。通过模拟发现:当一个纳米粒子-嵌段共聚物体系只存在A-B组分相互排斥作用时,其纳米粒子-嵌段共聚物中的A组分与B组分相分离,若同时还存在A-A(B-B)组分相互吸引作用时,其A-A(B-B)组分会相融合。同时还发现随着纳米粒子表面上的嵌段共聚物数量的减少,其嵌段共聚物黏附在纳米粒子表面的现象越明显。还研究了两个纳米粒子-嵌段共聚物体系的自组装模拟,并对其体系受两个纳米粒子之间距离的影响进行了研究。通过上述研究模拟发现,纳米粒子-嵌段共聚物的相结构以及其"最适"稳定态受组分之间的相互作用势和纳米粒子之间的距离的影响。     

复合材料力学综述

复合材料力学是固体力学的一个新兴分支,它研究由两种或多种不同性能的材料,在宏观尺度上组成的多相固体材料,即复合材料的力学问题.近代复合材料最重要的有两类:一类是纤维增强复合材料,另一类是粒子增强复合材料.复合材料力学的研究可分为微观力学和宏观力学.在此基础上重点分析了陶瓷纳米复合材料、碳纳米管聚合物复合材料和纤维增强树脂基复合材料的力学性能.     

碳纳米管扭转引起的力学耦合效应

利用经典分子动力学方法,计算分析了单壁碳纳米管、双壁碳纳米管的扭转力学行为,结果表明,相同口径的双壁碳管,在长度一致的情况下,其扭转刚度与碳管结构关联很小.以锯齿型管为外壁的双壁管扭转时的轴向力使碳管伸长,而以其他类型管为外壁的双壁碳管扭转时轴向力使碳管收缩.这些结果对相关纳米器件的设计有重要意义.     

聚吡咯-Fe3O4纳米复合材料的制备与表征及性能

用共沉淀方法制备出平均粒径在10 nm左右的Fe3O4纳米粒子,然后在阳离子表面活性剂的引导下采用原位化学氧化聚合法,合成出聚吡咯-Fe3O4纳米复合材料.同时对此纳米复合材料的结构和性能进行了研究.结果表明Fe3O4纳米粒子和聚吡咯之间存在着一定的相互作用,从而有利于吡咯单体在Fe3O4纳米粒子的表面发生聚合反应,进而Fe3O4纳米粒子被聚吡咯所包覆.聚吡咯/Fe3O4纳米复合材料同时具有导电性和磁性,其导电性随着Fe3O4纳米粒子含量的增加先增大后减小,磁性则始终随着Fe3O4纳米粒子含量的增加而增大.     

受限在单壁碳纳米管中金纳米粒子相变的分子动力学模拟研究

近年来,负载型金属纳米催化剂的制备及其性能研究一直是催化领域重要的研究课题.通过分子动力学(MD)模拟研究了受限在单壁碳纳米管(SWNT)内金纳米粒子在升温和降温过程中的相变.结果表明,受限金纳米粒子在室温下表现出两种不同类型的圆筒状多层结构.基于MD模拟,我们观察到了一个有趣的现象,即受限金纳米粒子的熔点随粒子增大而降低.对于受限的金纳米粒子来说,每一层的有序-无序的结构转变是受限金纳米粒子熔化的本质结构特征.     

蛋白质折叠与力学传感的单分子磁镊操纵研究进展

蛋白质的折叠与相互作用是物理、生物等多学科交叉领域关注的基本问题.力生物学的前沿研究表明，一系列对力敏感的蛋白质在机械力作用下的去折叠与复折叠动力学及相互作用调控，是实现其力感知的物理机制.前沿单分子操纵技术的发展使得在单分子水平定量探究蛋白质的折叠与细胞力学传感的分子机制成为可能.本文重点介绍近年来蛋白质折叠与力学传感的单分子磁镊操纵研究进展，包括单结构域蛋白质的折叠-去折叠动力学、自由能曲面的构造，及细胞黏着斑与胞间连接的力敏感蛋白行使生物功能的分子机制.     

碳纳米管操纵中的微观摩擦问题

为了充分掌握纳米操纵中的微观摩擦规律,消除微观摩擦对纳米操纵的不利影响,该文利用原子力显微镜(AFM)的超微探针作为操纵工具,对具有优异力学和电学特性的碳纳米管在不同的表面状况下进行了剪切和操纵。实验中发现,当基底的表面成分和表面形貌不同的时候,操纵过程中的微观摩擦力会有明显的变化。从与光刻技术相结合的操纵实验中可以看出,光刻后残留的光刻胶会大大增加碳纳米管与基底间的微观摩擦力,并加剧操纵工具——AFM针尖的污染与磨损。     

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…     

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.     

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)

正~~     

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.