带电聚合电介质表面吸附理论研究

摘要：应用聚合电介质吸附的定标理论,根据介质和表面电介质常数的比率,考虑多化合价吸附电介质之间强相关性作用,我们提出一种表面排斥电荷的近似定标理论方法,根据这种方法把电介质表面吸附层的相图分为本质上不同的两大类。从相图可知：当表面电荷密度低（或体带相反电荷离子密度高）,这时表面和体带相反电荷离子密度几乎相同;一旦表面电荷密度足够高,就使带相反电荷的离子在表面上浓缩。据此,可确定在这个区域内,低化合价聚合电介质形成一个相关的多链状态,当化合价足够高时,由于近邻链之间的更强排斥增强,使状态转变成单链。     

带电聚合电介质表面吸附理论研究

应用聚合电介质吸附的定标理论,根据介质和表面电介质常数的比率,考虑多化合价吸附电介质之间强相关性作用,我们提出一种表面排斥电荷的近似定标理论方法,根据这种方法把电介质表面吸附层的相图分为本质上不同的两大类。从相图可知：当表面电荷密度低（或体带相反电荷离子密度高）,这时表面和体带相反电荷离子密度几乎相同;一旦表面电荷密度足够高,就使带相反电荷的离子在表面上浓缩。据此,可确定在这个区域内,低化合价聚合电介质形成一个相关的多链状态,当化合价足够高时,由于近邻链之间的更强排斥增强,使状态转变成单链。     

Scaling Theory of Polyelectrolyte Nanogels

The present paper develops the scaling theory of polyelectrolyte nanogels in dilute and semidilute solutions.The dependencies of the nanogel dimension on branching topology, charge fraction, subchain length, segment number,solution concentration are obtained. For a single polyelectrolyte nanogel in salt free solution, the nanogel may be swelled by the Coulombic repulsion(the so-called polyelectrolyte regime) or the osmotic counterion pressure(the so-called osmotic regime). Characteristics and boundaries between different regimes of a single polyelectrolyte nanogel are summarized.In dilute solution, the nanogels in polyelectrolyte regime will distribute orderly with the increase of concentration. While the nanogels in osmotic regime will always distribute randomly. Different concentration dependencies of the size of a nanogel in polyelectrolyte regime and in osmotic regime are also explored.     

Debye–Hückel Theory for Charged Aligned Needles and for Polyelectrolyte Solutions

We consider a simple extension of the familiar Debye–Hückel theory of electrolyte solutions (in which the ions are represented by spheres with embedded point charges) to study the thermodynamic properties and the phase diagram of ionic solutions in which the ions of at least one of the species are deformed into parallel and rigid needle-like ellipsoidal objects that have a continuous line of charge distribution along their axis of revolution. We examine two specific cases: (a) solutions comprising both cationic and anionic needles that are identical in every respect except for the charge sign, and (b) solutions in which only one ionic species is made up of parallel rigid needles while the other species is made up of point ions. The first system is the analog, for ionic needles, of the familiar restricted primitive model of electrolytes, while the second one is a very simple model for a polyelectrolyte solution. For both systems we investigate how the phase diagram is affected by the extent of deformation of the ions, as measured by the spatial spread of their charge distribution.     

四臂星型聚电解质刷在外加三价盐离子和电场下的塌缩

本文采用Langevin动力学模拟的方法,研究存在三价盐离子时,接枝在带相反电荷的极板上的部分带电的四个臂星型链呈现出的塌缩现象. 结果表明,在电场作用下,接枝星型链的平均带电分数和盐浓度在带电单体和三价盐离子的竞争性吸附中起关键作用. 对于接枝在带相反电荷的极板上的带电分数较高的星型链,刷子会塌缩到接枝极板上,并会产生极板表面电荷的过度补偿现象. 当带电分数较低时,如果星型链所带电荷数与三价盐离子电荷数相同,即使在很低的盐浓度下,极板对三价盐离子的吸引能力也高于对星型链中的带电单体的吸引. 结果表明,星型链在带电分数较低的情况下,三价盐离子的加入不会导致接枝电极表面电荷的过度补偿. 此外,本文还研究了三价盐离子对电场作用下星型刷的拉伸的影响.     

Linear Theory of Plasma-Filled Coaxial Cylindrical Cherenkov Maser

Injection of background plasma into the beam-wave interaction region can greatly enhance the beam-wave interaction efficiency and the microwave output power of the device. In this paper, a new type of plasma-filled slow-wave structure, i.e., plasma-filled, dielectric-loaded coaxial cylindrical waveguide with a dielectric ring enclosing tightly the inner conductor, is developed. The Cherenkov radiation excited by the beam-wave interaction in the slow-wave structure is examined by use of the self-consistent linear field theory. The dispersion equation and the synchronized condition of the beam-wave interaction are derived. It's clearly shown that the Cherenkov radiation excited by the beam-wave interaction results from the coupling between the slow electromagnetic wave, TM-modes, propagated along the slow-wave structure and the negative-energy space-charge wave propagated along the relativistic electron beam. And the wave growth rate is solved, and the beam-wave energy exchange in the presence of the background plasma is discussed. Finally, the effects of the background plasma density on the dispersion characteristics, the distribution of the longitudinal fluctuating electric field, the wave growth rate and the beam-wave energy exchange are calculated and discussed.     

Water-Soluble Polyelectrolyte Complexes of Oppositely Charged Polysaccharides

The article is an overview of our recent study on some particular aspects of polyelectrolyte complex (PEC) formation by oppositely charged polysaccharides when they are brought into contact in aqueous solutions. This type of complexation can lead to the thickening effect, jellification or PEC precipitation that find numerous applications in a variety of fields from the regulation of rheological characteristics of solutions to fabrication of functional materials by the layer-by-layer technique. Our focus was on the rheological aspects of water-soluble PEC formation and jellification, but to gain an insight into the mechanisms of the processes involved, atomic force microscopy, scanning electron microscopy and differential scanning calorimetry were also applied. As cationic polysaccharides, chitosan and cationic derivatives of hydroxypropylcellulose including hydrophobically modified samples were taken and, as their anionic counterparts, alginates, carrageenans, xanthans and fucoidans were used. Their combination allowed us to consider the influence of charge density, hydrophobicity and flexibility–stiffness of macromolecules on the association of oppositely charged polysaccharides, the formation of temperature sensitive hydrogels and some PEC morphological features.     

波数线性校正方法在多烯烃和类胡萝卜素Raman光谱频率校正中的应用

采用密度泛函理论计算了两种类胡萝卜素(β-胡萝卜素和叶黄素) 和几种短链(n=2~5)多烯烃的Raman光谱,用波数线性校正(WLS)方法对计算频率进行了校正,并与常用的几种校正方法作了比较。最常用的单一参数校正(UFS)方法只适用于个别频率的校正,对于所有振动频率的综合校正效果并不理想。WLS方法对于多烯烃和类胡萝卜素的校正结果明显优于UFS方法,校正公式分别为ν_obs／ν_calc=0.999 9-0.000 027 4ν_calc和ν_obs／ν_calc=0.993 8-0.000 024 8ν_calc,这些结果说明WLS方法可以用于类胡萝卜素这样的大分子的频率校正。WLS方法对多烯烃和类胡萝卜素的校正参数非常接近,证明WLS方法对多烯烃的校正结果可以用于类胡萝卜素的频率校正,这为类胡萝卜素频率校正提供了一种新的方法。     

Simplified Forms of Generalized MHD Equations in a Cylindrical Plasma

The simplified forms of generalized magnetohydrodynamic equations have been derived. The K. Appert theory and Hain-Lüst equation are two special cases of our results when p→0 and ω/ω_ci→0. It is shown that the process of taking any limits (p→0 or ω/ω_ci→0) will result in a singularity at the Alfvén resonant layer.     

基于分形理论的NDVI连续空间尺度转换模型研究

尺度效应是遥感领域的一个非常重要的科学问题。定量遥感尺度转换研究可用于解决如定量遥感反演产品真实性检验等诸多颇具挑战性的问题。传统升尺度转换研究方法无法得到连续空间尺度上反演量的变化特性;且面临不同传感器间几何、光谱等特性参数校正问题的干扰,尺度转换研究精度受到影响。为此,基于分形理论利用单一传感器影像解决这些问题。基于Enhanced Thematic Mapper Plus(ETM+)数据,以NDVI(利用其地表辐亮度计算模型)为研究对象,建立了一个可参考的反演量连续空间尺度转换模型研究流程。结果表明:(1)NDVI升尺度转换中存在尺度效应,且此效应可由尺度转换分形模型定量描述;(2)此分形模型适用于NDVI产品的真实性检验中。这表明分形作为一种有效的方法,可用于定量遥感尺度转换研究中。     

圆柱定程干涉法声速测量原理与实验系统研制

气相声速是日前可测量的最精确的热物性之一,圆柱定程干涉法是极有应用前景的测量方法.本文分析了圆柱定程干涉法测量气相声速的实验原理,在此基础上研制了一套新的实验系统,由共鸣腔、压力仓、共振频率测量系统、温度和压力测量系统以及数据采集与控制系统组成.实验系统综合考虑了多种非理想因素的影响,提高了共振频率测量的信噪比,降低了...     

The Effect of an Absorbed Polyelectrolyte Layer on the Dynamic Mobility of a Colloidal Particle

Electroacoustic measurements can be used for determining the characteristics of polymer layers on colloidal particles. In this paper a theoretical formula is derived for calculating the effect of a polyelectrolyte layer on the colloid electroacoustic signal. Representative calculations are presented, and the application of these results for polyelectrolyte characterisation are discussed.     

Quasilocal Energy for Static Charged Black Holes in String Theory

The Brown-York quasilocal energies of some static charged dilaton black holes are calculated, and then the validity of Martinez‘s conjecture is explored in string theory. It is shown that the energy is positive and monotonically decreases to the ADM mass at spatial infinity, and the conjecture that the Brown-York quasilocal energy at the outer horizon of black hole reduces to twice of its irreducible mass is still applicable for the static charged black holes in string theory. The result is different from Bose-Naing‘s one.``     

1,2,3-三氮唑基团连接的双丙烯酸酯单体环聚合形成PEG聚合物刷的合成及表征

通过带有PEG官能团的双丙烯酸酯大分子单体的RAFT环聚合反应合成含有十一元环重复结构的PEG大分子刷．不同PEG长度的连接1,2,3-三氮唑的双丙烯酸酯大分子单体通过点击化学反应合成．PEG侧链的较大位阻效应影响双丙烯酸酯大分子单体的聚合行为,以致于双丙烯酸酯大分子单体优先进行环化聚合反应而不发生交联反应．核磁数据和凝胶渗透色谱证明高效的环化聚合反应,而且没有副反应发生．PEG大分子刷在紫外光激发下有较强的荧光,而荧光则强烈依赖于聚合物刷的浓度,这归因于环聚合物在水中的聚集．PEG大分子刷的荧光能被DNA淬灭．     

Molecular Simulation of Salt Ion Effect on Anionic Polyelectrolyte Chain

The effect of salt ions on anionic polyelectrolyte chain structure has been studied by molecular mechanics and molecular dynamics, and the reason for sedimentation of the anionic polyelectrolyte in the salt solution is explored. Considering sodium polyacrylate as a model compound of anionic polyelectrolytes, the conformation of polyacrylate in salt-free and CaCl₂ solution is studied. The simulation results showed that anionic polyelectrolytes in aqueous solution had an extended chain structure due to the role of strong electrostatic repulsion. After introduction of Ca²⁺ to the solution, the collapse of the anionic polyelectrolyte chain happens. By analysis of the radius of gyration and the radial distribution function, the basic reason for the collapse of anionic polyelectrolyte chains in salt solution is clarified with atomistic resolution.     

聚电解质包覆的铕(Ⅲ)配合物@SiO2荧光纳米粒的合成与性质

以二苯甲酰甲烷(DBM)、邻菲罗琳(phen)和丙烯酸(AA)为配体,制备了铕的配合物Eu(Ⅲ)(DBM)2-(phen)(AA).利用St(o)ber法合成了SiO2纳米粒.通过超声辅助,将脂溶性的强荧光铕配合物吸附到SiO2纳米粒上,再包覆阳离子聚电解质聚二烯丙基二甲基氯化铵(PDAC)和阴离子聚电解质聚丙烯酸(P...     

时间分数阶Edwards-Wilkinson方程的标度行为研究

分别采用数值模拟和标度分析方法对1+1维时间分数阶Edwards-Wilkinson方程的标度行为进行研究.利用Caputo分数阶导数数值解求得的生长指数与采用直接标度分析方法得到的结果一致.     

Bifurcation of Dicke Model Driven by Laser Field and Scaling Theory of Critical Exponents Far from Equilibrium

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Stationary Scattering Theory for a Charged Particles Transport Problem

We consider a nonautonomous transport problem, the modelization of the charge exchange dynamics in a monoatomic ionized gas, and apply scattering theory to its dynamics. The free dynamics corresponds to the evolution of the total distribution of particles (neutral plus ionized particles) and the perturbed dynamics corresponds to the evolution of the neutral particles, which is the solution of a nonautonomous transport problem. The existence of the time-dependent wave operators was proved by the first author. In the present paper we follow Howland's formalism in constructing a stationary scattering theory for this nonautonomous transport problem by studying the evolution equation. We prove the existence of the wave operators and by using the smooth perturbation technique we obtain the similarity between perturbed and unperturbed operators.     

The Scaling Limit Geometry of Near-Critical 2D Percolation

We analyze the geometry of scaling limits of near-critical 2D percolation, i.e., for p = p _c+λδ^1/ν, with ν = 4/3, as the lattice spacing δ → 0. Our proposed framework extends previous analyses for p = p _c, based on SLE ₆. It combines the continuum nonsimple loop process describing the full scaling limit at criticality with a Poissonian process for marking double (touching) points of that (critical) loop process. The double points are exactly the continuum limits of “macroscopically pivotal” lattice sites and the marked ones are those that actually change state as λ varies. This structure is rich enough to yield a one-parameter family of near-critical loop processes and their associated connectivity probabilities as well as related processes describing, e.g., the scaling limit of 2D minimal spanning trees.