甘露糖修饰的微马达的制备及其免疫功能初探

为了开发集自驱动运动与免疫功能于一体的新型糖杂化材料,本工作设计并制备了一种甘露糖修饰的哑铃形微马达(Zincoxide/Polydopamine/Mannose微马达,简称ZnO/PDA/Man微马达),其不对称的哑铃结构会引起不均匀的离子分布,从而促使马达运动.该马达能量来源无生物毒性,能够在可见光的照射下,以纯水为燃料,实现离子型自扩散泳运动.通过调节可见光的强度和辐照方向,可实现马达运动速度和方向的精准调控.ZnO/PDA/Man微马达具有良好的生物相容性,且表面修饰生物活性的甘露糖苷可作为免疫激活剂使巨噬细胞极化.相比于传统免疫激活剂,ZnO/PDA/Man微马达有望在可见光照射下,实现肿瘤组织中的自由运动和深度渗透,在肿瘤免疫治疗领域具有潜在的应用价值.     

均聚物结晶与熔融化的稳态和亚稳态转变统计理论

基于多重微晶网络结构模型和分子分凝机制建立了高分子晶体的微晶核-和微晶粒-高分子链组模型,推导出了平衡态下高分子预结晶动力学方程,计算出了平衡态下不同尺寸微晶核-和微晶粒-高分子链组的几率分布函数.建立了非稳态下不同尺寸的微晶核-高分子链组的成核演化方程和微晶粒-高分子链组的增长演化方程,求解一般状态下的两个演化方程后,得到了不同时间和不同尺寸的微晶核-和微晶粒-高分子链组的一般密度分布函数.最后根据成核自由能和增长自由能对晶核和晶粒的尺寸大小的依赖性,提出了微晶核-高分子链组和微晶粒-高分子链组存在稳定性的热力学条件和动力学条件,成功地表征为三个特征区(稳态、亚稳态和非稳态).     

含BN旋转轴的光驱动分子马达的理论设计和机理研究

依据B=N键与C=C键的电子结构相似性,以Feringa型二苯乙烯型光驱动分子马达（CC-stilbene）为母体,设计了含极性旋转轴的模型马达BN-stilbene.CASPT2//CASSCF计算结果表明,优化所得的BN-stilbene分子的基态存在四个与CC-stilbene马达结构相似、相对能量一致的螺旋异构体;B=N极性共价双键对BN-stilbene的基态和激发态电子结构有显著影响.对BN-stilbene模型马达的工作机理研究表明,极性旋转轴的引入使得BN-stilbene中S₁/S₀-CI与激发态中间体构型更加相似且能量更低,同时可增加旋转的驱动力,起到改进分子马达光异构化过程的单向性的目的.     

荧光标记聚苯乙烯微球的激光捕获及其原位稳态和时间分辨荧光光谱研究

本工作设计研制了一套激光捕获与原位稳态及时间分辨荧光光谱检测系统,该系统将激光捕获技术与稳态及时间分辨荧光光谱检测技术相结合,实现了对亚微米级微粒的原位稳态及时间分辨发光性质研究.利用研制的仪器研究了荧光标记聚苯乙烯微球的激光捕获过程、以及捕获微粒的原位稳态及时间分辨荧光光谱.本工作为单个纳米粒子发光性质的研究开辟了一条新的途径.     

在激波波面中氧分子的非平衡离解

对强激波作用下双原子分子振动与离解耦合的非平衡离解过程进行了理论计算.本工作的特点是将计算起点建立在分子基本参数上,采用主方程理论处理振动与离解的耦合,振动跃迁几率用SSH理论计算,在离解限附近考虑多量子数跃迁并计及原子复合的影响.对O2－Ar体系,计算给出了在正激波后O2分子振动能级分布、振动弛豫时间、离解孕育时间、离解产物浓度、离解速率系数等物理量随时间的演化.计算结果分别与Camac 和Wray的实验相符.计算显示，在激波作用的后期,有准稳态的振动能级布居分布.计算结果显示，Park模型低估了非平衡离解速率系数,Hansen模型则高估了非平衡离解速率系数.     

肌球蛋白的结构及工作机制

在生物界中,化学能转化成定向的机械能的分子机理是一个基本问题.有一类能利用化学能/化学势进行机械做功的生物大分子,称为分子马达.分子马达依据其作用的方式可分为线性分子马达与旋转式分子马达两大类.线性分子马达是一类将化学能转化为机械能,并沿着一个线性轨道运动的生物     

胶体马达

胶体马达亦称微纳米马达、微纳米泳体或游动纳米机器人,是研究复杂系统的绝佳非平衡态物理模型,同时因其具有额外的自推进力、自主导航等独特优势,有望为靶向药物递送等生物医学应用带来颠覆性变革.作为一个新兴的多学科交叉领域,胶体马达拓展了胶体与界面化学的研究范畴,带来了新的现象、理论与应用,是以胶体科学为核心的国际前沿交叉学科研究的热点领域.本文系统地阐述了胶体马达以及基于胶体马达的超分子胶体马达和游动纳米机器人的新概念,同时以本课题组在胶体马达领域取得的研究成果为例,详细综述了胶体马达的结构设计与可控制备、驱动机理及运动行为的界面调控策略、集群行为规律与重构方法以及突破各种生物屏障实现药物主动靶向递送等方面的最新进展,在此基础上展望了胶体马达对于胶体科学发展所带来的新机遇与新挑战.     

凝并和成核机理下颗粒尺度分布的Monte Carlo求解

颗粒的凝并和成核现象影响其尺度分布,现有的MonteCarlo方法描述颗粒尺度分布的时间演变过程存在若干困难.提出了一种新的多重MonteCarlo(MMC)算法,基于时间驱动,利用加权的虚拟颗粒的思想,在模拟过程中保持虚拟颗粒总数不变和计算区域体积不变.利用该算法对“常凝并核,一阶成核”的情况下颗粒尺度分布的时间演变过程进行了数值求解,所得结果与数值解相符,表明MMC算法具有高且稳定的计算精度.另外,MMC算法由于跟踪比实际颗粒数目少得多的虚拟颗粒而具有较低的计算代价.     

可控分子组装的自驱动胶体马达及其生物医学应用

人造胶体马达是能够将不同形式的能量转化为流体中机械运动的微纳米机器.自2 0 1 2年以来,将自下而上的可控分子组装与自上而下的方法有效结合已成为可控构筑胶体马达的重要策略之一.基于可控分子组装(如层层组装)的胶体马达具有易于实现规模化制备、能够对外界刺激作出响应、便于实现多功能化等优点.本文综述了通过将各种功能性构筑基元集成到组装结构中进而实现胶体马达的可控构筑、运动控制以及生物医学应用等方面的研究进展.主要介绍了基于不同层层组装结构的气泡驱动马达的可控构筑,基于聚电解质多层膜微胶囊及纳米管的近红外光驱动马达的构筑,生物界面化马达的制备,实现对胶体马达运动速度、方向及状态有效控制的主要方法,以及马达在药物靶向递送、光热治疗和生物毒素清除等生物医学领域中的应用.     

利用高通量技术研究钴基费托催化剂的宏观动力学

利用高通量技术设计并运行了16路平行动力学固定床反应器,用于测量不同接触时间下的稳态反应物消耗速率和产物生成速率,研究了钴基费托催化剂的宏观动力学,包括C1～C4烷烃与烯烃的稳态反应速率及其随床层的分布,以及它们与反应器温度的关系.在等温固定床非扩散限制的反应条件下,除C1和C2烃类外,Cn的生成速率及CO/H2的消耗速率均随接触时间的增加先上升后下降,且烯烃生成速率的最高点较烷烃更靠近反应器入口;反应温度对速率的影响与转化率有关:生成烷烃的表观活化能大于烯烃.高通量动力学反应器可用于生成宏观动力学数据库,以预测催化剂在工业固定床反应器中的行为.     

Exact solutions for kinetic models of macromolecular dynamics

Dynamic biological processes such as enzyme catalysis, molecular motor translocation, and protein and nucleic acid conformational dynamics are inherently stochastic processes. However, when such processes are studied on a nonsynchronized ensemble, the inherent fluctuations are lost, and only the average rate of the process can be measured. With the recent development of methods of single-molecule manipulation and detection, it is now possible to follow the progress of an individual molecule, measuring not just the average rate but the fluctuations in this rate as well. These fluctuations can provide a great deal of detail about the underlying kinetic cycle that governs the dynamical behavior of the system. However, extracting this information from experiments requires the ability to calculate the general properties of arbitrarily complex theoretical kinetic schemes. We present here a general technique that determines the exact analytical solution for the mean velocity and for measures of the fluctuations. We adopt a formalism based on the master equation and show how the probability density for the position of a molecular motor at a given time can be solved exactly in Fourier-Laplace space. With this analytic solution, we can then calculate the mean velocity and fluctuation-related parameters, such as the randomness parameter (a dimensionless ratio of the diffusion constant and the velocity) and the dwell time distributions, which fully characterize the fluctuations of the system, both commonly used kinetic parameters in single-molecule measurements. Furthermore, we show that this formalism allows calculation of these parameters for a much wider class of general kinetic models than demonstrated with previous methods.     

Anomalous lineshapes and aging effects in two-dimensional correlation spectroscopy

Multitime correlation functions provide useful probes for the ensembles of trajectories underlying the stochastic dynamics of complex systems. These can be obtained by measuring their optical response to sequences of ultrashort optical pulse. Using the continuous time random walk model for spectral diffusion, we analyze the signatures of anomalous relaxation in two-dimensional four wave mixing signals. Different models which share the same two point joint probability distribution show markedly different lineshapes and may be distinguished. Aging random walks corresponding to waiting time distributions with diverging first moment show dependence of 2D lineshapes on initial observation time, which persist for long times.     

APA微胶囊扩散数学模型的改进

在膜阻力系数和膜内基质的分配系数两个新特性的基础上,重新建立了蛋白质在APA微胶囊体系上的扩散数学模型,该模型更为准确地反映出蛋白质在微胶囊上的扩散特性     

Dispersion of components in transport processes: velocity dispersion model

This paper presents a new model of dispersion of components in transport processes. It is suggested that the flow velocity may be specified by a Gauss function with relative dispersion of flow velocity beta=sigmav/v; the overall dispersion of inert component (in porous as well as in homogeneous medium) may be calculated from the equation sigma=(2Dt/tau2 + (betavt)2)0.5, where D is the diffusion coefficient, t is time, tau is tortuosity, and v is flow velocity. The most common range of variability of relative dispersion of flow velocity in natural soils is 8-32%. The model is well applicable to column and field experiments.     

Relationship between current response and time in ion transport problem including diffusion and convection. 1. An analytical approach

   The mathematical models of the ion transport problem in a potential field are anayzed. Ion transport is regarded as the superposition of diffusion and convection. In the case of pure diffusion model the classical Gottrell’s result is studied for a constant as well as for the time dependent Dirichlet data at the electrode. Comparative analysis of the current response and the classical Gottrellian is given on the obtained explicit formulas. The approach is extended to find out the current response corresponding to the diffusion-convection model. The relationship between the current response and Gottrellian is obtained in explicit form. This relationship permits one to compare pure diffusion and diffusion-convection models, including asymptotic behaviour of current response and an influence of the convection coefficient. The theoretical result are illustrated by numerical examples.      

Systematic search for surrogate chromatographic models of biopartitioning processes

A systematic approach for identifing surrogate chromatographic models for biopartitioning processes is described. The method is based on a comparison of the system constant ratios of the solvation parameter model for biopartitioning processes and a database of system constant ratios for reversed-phase liquid chromatographic and micellar electrokinetic chromatographic systems compiled from literature sources. An acceptance filter of < or = 0.2 is applied for each difference in system constant ratio for the compared systems to provide a reasonable probability of success without outputting too many systems with limited predictive properties. Surrogate chromatographic models identified for the non-specific toxicity of neutral organic compounds to the fathead minnow and the soil-water distribution constant are tested by construction of a correlation model for the characteristic property of the biological process and the chromatographic retention factors for a structurally varied group of compounds. Although these models are not the best that could be obtained based on ranking of the differences in system constant ratios the predictive ability of the correlation models is suitable for typical applications and similar to the accepted uncertainty in the measurements of the biological property. Retention factors on the immobilized artificial membrane column (IAM PC DD 2) with 10% (v/v) methanol-water as mobile phase are able to estimate non-specific toxicity to the fathead minnow with a standard error (SE) of 0.22 log units and coefficient of determination (r2) of 0.97 for 31 compounds. Retention factors on a Bakerbond DIOL column with 20% (v/v) acetonitrile-water as mobile phase are able to estimate the soil-water distribution constant with an SE of 0.38 log units and r2 = 0.88 for 59 compounds. Other potential surrogate chromatographic models are identified for non-specific toxicity to the guppy, tadpole, Vibrio fischeri and Terahymena pyriformis as well as the plant cuticle matrix-water distribution constant. On the other hand reversed-phase chromatographic systems seem poorly suited for estimating intestinal absorption and the blood-brain distribution constant.     

Polymer dynamics in repton model at large fields

Polymer dynamics at large fields in Rubinstein-Duke repton model is investigated theoretically. Simple diagrammatic approach and analogy with asymmetric simple exclusion models are used to analyze the reptation dynamics of polymers. It is found that for polyelectrolytes the drift velocity decreases exponentially as a function of the external field with an exponent depending on polymer size and parity, while for polyampholytes the drift velocity is independent of polymer chain size. However, for polymers, consisting of charged and neutral blocks, the drift velocity approaches the constant limit which is determined by the size of the neutral block. The theoretical arguments are supported by extensive numerical calculations by means of density-matrix renormalization group techniques.     

Slice imaging of quantum state-to-state photodissociation dynamics of OCS

Slice imaging experiments are reported for the quantum state-to-state photodissociation dynamics of OCS. Both one-laser and two-laser experiments are presented detecting CO(J) or S((1)D(2)) photofragments from the dissociation of hexapole state-selected OCS(v(2) = 0,1,2 / J = 1,2) molecules. We present data using our recently developed large frame CCD centroiding detector and have implemented a new high speed MCP high voltage pulser with an effective slice width of only 6 ns. Slice images are presented for quantum state-to-state photolysis, near 230 nm, of vibrationally excited OCS(v(2) = 0,1,2). Two-laser pump-probe experiments detecting CO(J = 63 or 64) show a dramatic change in the beta parameter for the same final state of CO(J) when the photolysis energy is reduced by about 1000 cm(-1). We attribute the observed change from large positive to large negative beta to a large increase of the molecular frame deflection angle at very slow recoil velocity, due to a breakdown of the axial recoil. Two-laser experiments on the S((1)D(2)) fragment reveal single well-separated rings in the slice images correlating with individual CO(J) states. Strong polarization effects of the probe laser are observed, both in the angular distribution of the intensity of single S((1)D(2)) rings and in the resolution of the radial velocity distribution. It is shown how the broadening of the velocity distribution can be reduced by a directed ejection of the electron in the ionization process perpendicular to the slice imaging plane. The dissociation energy of OCS(v(2) = 0, J = 0) --> CO(J = 0) + S((1)D(2)) is determined with high accuracy D(0) = (34 608 +/- 24) cm(-1).     

Propagators and related descriptors for non-Markovian asymmetric random walks with and without boundaries

There are many current applications of the continuous-time random walk (CTRW), particularly in describing kinetic and transport processes in different chemical and biophysical phenomena. We derive exact solutions for the Laplace transforms of the propagators for non-Markovian asymmetric one-dimensional CTRW's in an infinite space and in the presence of an absorbing boundary. The former is used to produce exact results for the Laplace transforms of the first two moments of the displacement of the random walker, the asymptotic behavior of the moments as t-->infinity, and the effective diffusion constant. We show that in the infinite space, the propagator satisfies a relation that can be interpreted as a generalized fluctuation theorem since it reduces to the conventional fluctuation theorem at large times. Based on the Laplace transform of the propagator in the presence of an absorbing boundary, we derive the Laplace transform of the survival probability of the random walker, which is then used to find the mean lifetime for terminated trajectories of the random walk.