磁流变液双链密排微结构模型

为了揭示磁流变液宏观响应特性下的深层次物理背景,从而为研制高性能磁流变液提供指导,基于磁偶极子理论,结合铁磁颗粒的链化机理,提出了磁流变液双链密排微结构模型.在外加磁场下,当铁磁颗粒沿磁场方向形成链状结构后,通过考虑相邻链之间的影响,假定磁偶极子链发生剪切变形后的倾斜角度服从指数分布,从磁偶极子能量的角度推导了磁流变液双链密排微结构模型的剪切屈服应力公式.分析了磁感应强度、铁磁颗粒体积分数、铁磁颗粒尺寸以及颗粒包覆层厚度等主要影响因素与磁流变液剪切屈服应力的关系,并进行了试验验证.结果表明,该模型与试验结果吻合很好,可以反映各主要因素对磁流变液剪切屈服应力的影响.     

具有复合结构颗粒的介电相互作用

讨论了电流变液分散相固体颗粒采取分层复合结构时可能对电流变效应产生的影响．分析过程基于介电极化理论．给出了电场作用下具有复合结构颗粒间的结合能、失配参数的解析表达式，分析了固体颗粒各层的材料性质、厚度、介电常数等因素变化对颗粒间结合能的影响．讨论显示：尽管复合结构颗粒的电流变液具有较为复杂的失配参数表达式，但与单一结构颗粒的电流变液相比，两者在颗粒间结合能的表现上十分类似，提示了以改善电流变效应为目的而采用复合结构固体颗粒作为分散相的建议缺乏理论依据．同时还发现，颗粒外覆层厚度的变化随介电常数的不同、对颗粒间结合能的影响具有正、逆两种效应．     

电流变抛光液中固相粒子间结合模型研究

电流变抛光液中的固相极化后形成复杂的微观结构并改变其流变性能。通过超景深三维显微系统观察了电流变抛光液在外加电场作用下形成的微观结构。根据粒子介电极化模型和抛光液中固相粒子间的作用力,建立了混有不同粒度磨料颗粒的电流变抛光液中固相粒子的结合模型,分析了颗粒粒度和粒子间作用力等因素对粒子结合模型的影响。     

电流变液的流变性试验和建模

利用旋转粘度计装置,研究电流变液的流变特性.通过试验,分析电场强度、剪切速率和分散相粒子的百分比等对电流变液剪切应力的影响.利用实验数据,建立描述电流变液流变特性的Bingham模型、广义Bingham和非线性模型,并讨论它们的误差.     

含位形权重的磁流变液孤立链流变剪应力模型

为降低采用标准孤立链理论模型计算高体积分数磁流变液流变剪应力时的计算误差,提出一种通过距离权重系数评价磁链间相互作用的流变模型.编写Monte Carlo仿真程序计算颗粒位置与磁矩方向矢量、同时输出与系统颗粒间距有关的距离权重系数.按标准和距离权重这两种链结构模型计算磁流变液剪切应力数值,并和4种磁流变液(30.58%~44.79%)的流变仪剪应力测试数据进行比较,结果显示,权重模型在磁场全范围内具有更高的计算精度,并且和流变试验实际结果基本符合,证实了磁链微观结构间的相互作用力是影响磁流变液流变特性的主要因素之一.     

电流变液的研究进展与存在问题

电流变液是具有高介电常数的固体微粒分散于低介电常数的绝缘液体中所形成的一类稳定悬浮液。作为近年来发展较快的一类智能材料,由于其具有在液体和固体之间进行快速可逆转变的特性,因此在机电一体化控制、汽车、通用机械等领域有着广泛的应用前景,并有可能在这些部门引起革命性的变化。本文详细评述了电流变液在作用机制,材料,应用等方面的研究现状,并提出了电流变液研究中尚待解决的问题。     

插层高岭土的制备及其电流变性能

以肼为客体采用水热法对高岭土进行插层处理,获得插层率较高的插层高岭土.以插层高岭土为分散质、甲基硅油为连续相制备复合电流变液.利用X射线衍射(XRD)、红外光谱(FTIR)、电流变液测试装置等对插层高岭土进行结构表征及电流变液性能分析.讨论水热处理温度、肼质量分数、酸碱度对插层率的影响,以及高岭土插层对电流变液效应的作用.结果表明,在160℃的条件下,用质量分数为50%的肼溶液插层处理高岭土可以得到插层率59%的插层高岭土;水热法在肼插层高岭土制备方面效果明显;肼分子进入到高岭土层间,导致其层间距由0.714 nm增加至1.037 nm;插层高岭土电流变液的电流变性能明显优于未插层高岭土电流变液.     

电流变阻尼器用于抑制系统的振动

电流变液是一种极有发展前景的新频材料,对于外加电场的变化,它可以迅速作出响应,在工业上极具应用前景。简要介绍了电流变液及其力学特性,并利用一种简单的阻尼模型,对具有电流变阻尼器的振动地响应分析,给出了数值算例,结果表明,电流变阻尼器可以明显地降低系统的振幅。     

大阻尼力电流变阻尼器的结构设计及力学性能

根据电流变液的力学性能并结合原有的电流变阻尼器的特点，提出了一种可以大大提高其阻尼力的新型电流变阻尼器结构，并建立了力学模型，给出了其阻尼力和等效粘性阻尼系数，通过与原电流变阻尼器的阻尼力特性相比较，新型阻尼器在电场为0kV/mm、增益为2时，其粘性阻尼系数是原电流变阻尼器的4倍，表明新型结构的阻尼器设计在理论上是可行的。     

β-环糊精包合物材料的电流变性能——功能基的影响

用β-环糊精（简称p—CD）作为主体,水杨酸（简写为SCA）、邻苯二甲酸（简写为PHA）、邻氨基苯甲酸（简写为OAA）和磺基水杨酸（简写为HS03）等作为客体,采用固相反应,合成了新型的电流变材料-β-环糊精包合物材料．研究了材料的电流变性能,以及客体分子的组成和结构与材料电流变性能的关系．结果表明,客体分子的结构,特别是客体分子的功能基是影响材料电流变性能的重要因素．β-环糊精包合磺基水杨酸的包合物有最高的电流变活性．     

Stacking of conical molecules with a fullerene apex into polar columns in crystals and liquid crystals

Polar liquid crystalline materials can be used in optical and electronic applications, and recent interest has turned to formation strategies that exploit the shape of polar molecules and their interactions to direct molecular alignment. For example, banana-shaped molecules align their molecular bent within smectic layers, whereas conical molecules should form polar columnar assemblies. However, the flatness of the conical molecules used until now and their ability to flip have limited the success of this approach to making polar liquid crystalline materials. Here we show that the attachment of five aromatic groups to one pentagon of a C(60) fullerene molecule yields deeply conical molecules that stack into polar columnar assemblies. The stacking is driven by attractive interactions between the spherical fullerene moiety and the hollow cone formed by the five aromatic side groups of a neighbouring molecule in the same column. This packing pattern is maintained when we extend the aromatic groups by attaching flexible aliphatic chains, which yields compounds with thermotropic and lyotropic liquid crystalline properties. In contrast, the previously reported fullerene-containing liquid crystals all exhibit thermotropic properties only, and none of them contains the fullerene moiety as a functional part of its mesogen units. Our design strategy should be applicable to other molecules and yield a range of new polar liquid crystalline materials.     

极性流体的微扰理论研究

建立了一个用以计算极性流体热力学性质的微扰理论模型。模型中考虑了粒子间硬球排斥、色散、静电和诱导等相互作用能，由同时拟合饱和蒸汽压和液相密度获得分子微观参数。对几种常见的极性流体的计算结果表明，这一模型具有比较简单、准确、参数的物理意义明确等优点。     

致密储层各向异性地震岩石物理建模及应用

针对致密砂岩储层低孔低渗及微裂缝发育的特点,提出一种适合致密孔隙裂缝型储层的岩石物理模型构建方法:首先,在岩石基质中利用有效介质理论添加含流体孔隙,然后利用结合Hudson理论和各向异性Gassmann理论推导得到的各向异性流体替代方程添加含流体裂缝。基于构建的岩石物理模型,定量分析裂缝密度、裂缝形状、充填流体等储层岩石的物理性质对饱含流体岩石的纵横波速度的影响。采用某研究区实际井资料对该方法进行试算,完成纵横波速度的估算和裂缝储层各向异性参数的提取,纵横波速度的估算值与其实测值的吻合程度较高,且各向异性参数能够较好地反映裂缝发育位置,证明了本文方法的有效性。     

链状方阱流体的状态方程研究

为研究链状分子物质（如烷烃等）及其混合物的热力学性质,应用Ｗｅｒｔｈｅｉｍ的热力学微扰理论,在链状硬球流体状态方程的基础上,发展得到了链状方阱流体的状态方程。它可以表示成三部分：硬球贡献、方阱吸引势能贡献和成键贡献。在计算成键对压缩因子的贡献时,考虑到了成键对组成链的原子之间径向分布函数的影响。用得到的状态方程计算不同链长的链状方阱流体的压缩因子,其结果与分子模拟数据符合较好。     

Estimation of the polarity of the protein interior by optical spectroscopy

Crystallographic studies of myoglobin have shown that the haem pocket is lined with nonpolar amino-acid residues. In order to estimate the true polarity of the interior of proteins, certain studies have used bound fluorophores, the spectroscopic properties of which reflect the polarity of their environment. These studies have most often used 1-amino-8-naphthalene sulphonate (ANS) as a probe, but a more suitable probe, in principle, is 6-propionyl 2-(N,N-dimethyl)aminonaphthalene (PRODAN). We have synthesized a molecule with the advantageous spectroscopic properties of PRODAN but with a higher affinity for apomyogloblin: 2'-(N,N-dimethyl)amino-6-naphthopyl-4-trans-cyclohexanoic acid (DANCA), and report here its use to determine the polarity of the myoglobin haem pocket. Our results show that the pocket is actually a polar environment, and the polarity can be accounted for by peptide amide dipoles.     

Substrate specificity and affinity of a protein modulated by bound water molecules

Water molecules influence molecular interactions in all biological systems, yet it is extremely difficult to understand their effects in precise atomic detail. Here we present evidence, based on highly refined atomic structures of the complexes of the L-arabinose-binding protein with L-arabinose, D-fucose and D-galactose, that bound water molecules, coupled with localized conformational changes, can govern substrate specificity and affinity. The atoms common to the three sugars are identically positioned in the binding site and the same nine strong hydrogen bonds are formed in all three complexes. Two hydrogen-bonded water molecules in the site contribute further to tight binding of L-arabinose but create an unfavourable interaction with the methyl group of D-fucose. Equally tight binding of D-galactose is attained by the replacement of one of the hydrogen-bonded water molecules by its--CH2OH group, coordinated with localized structural changes which include a shift and redirection of the hydrogen-bonding interactions of the other water molecule. These observations illustrate how ordered water molecules can contribute directly to the properties of proteins by influencing their interaction with ligands.     

Orientation of molecular interface dipole on metal surface investigated by noncontact atomic force microscopy

We investigated the orientations of interface dipole moments of individual non-planar titanyl phthalocyanine(TiOPc)molecules on Cu(111)and Cu(100)substrates using scanning tunneling microscope(STM)and noncontact atomic force microscope(NC-AFM).The dipole moment orientations corresponding to two different configurations of individual TiOPc molecules were determined unambiguously.The correlation between the actual molecular structures and the corresponding STM topographies is proposed based on the sub-molecular resolution imaging and local contact potential difference(LCPD)measurements.Comparing with the pristine substrate,the LCPD shift due to the adsorption of non-planar molecule is dependent on the permanent molecular dipole,the charge transfer between the surface and the molecule,and the molecular configurations.This work would shed light on tailoring interfacial electronic properties and controlling local physical properties via polar molecule adsorption.     

参照零模型的符号社交网络理论研究

 结构平衡理论和地位理论是社交网络领域的重要理论,可以用来分析同时具有正向和负向连边的社交符号网络。提出了3种新的随机断边重连零模型,基于随机断边重连和符号随机置乱两大类零模型,对符号社交网络的地位理论和结构平衡理论进行了系统研究。发现基于零模型不但可以验证两种理论在实证网络中的准确性,还能揭示正边、负边拓扑结构和连边符号相关性对于整个网络性质的影响。提出了一个新框架,研究能否将有向符号网络转化为无向符号网络,发现目前常用的将有向符号网络转化成无向符号网络的方法在有些情况下对于研究社交网络理论是不合适的,存在着信息损失;讨论了非符号有向网络中的势能理论。     

稠油胶质特性及其对沥青质吸附行为研究

考察了4种稠油胶质的分子结构特性及其对塔河、辽河沥青质的吸附行为,探讨了胶质吸附行为与沥青质分散稳定性间的内在联系。 结果表明: 4种胶质对沥青质的吸附符合Freundlich吸附,曲线形状是胶质多层吸附及渗透进入沥青质微孔结构的综合反映。4种胶质吸附等温曲线形状与其分子结构特性对照表明,塔河、渤海和辽河胶质对沥青质的吸附在低平衡浓度部分产生紧密单分子层吸附, 吸附曲线平滑;在高平衡浓度部分, 因其较强极性导致正庚烷对其亲和作用力不及沥青质从而发生相态分离, 在沥青质表面产生积极吸附造成曲线斜率急剧增大; 较弱极性的华北胶质未产生明显相态分离现象, 而是随浓度增加成比例渗透进沥青质聚集体中产生吸附。4种胶质的吸附行为与其分散稳定沥青质的有效性之间关系显示了胶质对沥青质的分散稳定能力既与其吸附量有关,也与其分子结构特性有关。     

Experimental non-classicality of an indivisible quantum system

In contrast to classical physics, quantum theory demands that not all properties can be simultaneously well defined; the Heisenberg uncertainty principle is a manifestation of this fact. Alternatives have been explored--notably theories relying on joint probability distributions or non-contextual hidden-variable models, in which the properties of a system are defined independently of their own measurement and any other measurements that are made. Various deep theoretical results imply that such theories are in conflict with quantum mechanics. Simpler cases demonstrating this conflict have been found and tested experimentally with pairs of quantum bits (qubits). Recently, an inequality satisfied by non-contextual hidden-variable models and violated by quantum mechanics for all states of two qubits was introduced and tested experimentally. A single three-state system (a qutrit) is the simplest system in which such a contradiction is possible; moreover, the contradiction cannot result from entanglement between subsystems, because such a three-state system is indivisible. Here we report an experiment with single photonic qutrits which provides evidence that no joint probability distribution describing the outcomes of all possible measurements--and, therefore, no non-contextual theory--can exist. Specifically, we observe a violation of the Bell-type inequality found by Klyachko, Can, Binicio?lu and Shumovsky. Our results illustrate a deep incompatibility between quantum mechanics and classical physics that cannot in any way result from entanglement.