细菌生长的热动力学研究进展

本文简单介绍了绝热式和热导式量热计及理论模型,细菌生长的动力学模型,着重介绍了近五年中热动力学在研究细菌生长代谢过程中的应用;通过测定不同条件下细菌生长代谢过程的产热曲线,求得细菌生长代谢的热力学和动力学参数,研究细菌的生长条件和药物的抑制作用。     

细胞动力学研究VI. 厌氧菌生长过程热化学特征

用LKB2277生物活性检测系统测定了三种厌氧菌---吉氏类杆菌、艰难梭状芽胞杆菌、黑色消化球菌的生长发热功率曲线。根据广义logistic方程, 建立了细菌生长过程的热动力学方程:ln[P/(Pm-P)^v^+^1]=ln[P0/(Pm-P0)^v^+^1]+k.t。由此热动力学方程, 求得了细菌的生长常数k, 根据Arrhenius公式求得吉氏菌的生长活化能Ea=59.7kj/mol, 应用过渡态理论得到吉氏菌在不同温度下的活化力学参数, 这个热动力学方程描述的是一系列不规则的细菌生长过程发热曲线, 将它与经典的指数模型和logistic模型进行比较, 它具有更广泛的适用性。     

细胞动力学研究VI. 厌氧菌生长过程热化学特征

用LKB2277生物活性检测系统测定了三种厌氧菌---吉氏类杆菌、艰难梭状芽胞杆菌、黑色消化球菌的生长发热功率曲线。根据广义logistic方程, 建立了细菌生长过程的热动力学方程:ln[P/(Pm-P)^v^+^1]=ln[P0/(Pm-P0)^v^+^1]+k.t。由此热动力学方程, 求得了细菌的生长常数k, 根据Arrhenius公式求得吉氏菌的生长活化能Ea=59.7kj/mol, 应用过渡态理论得到吉氏菌在不同温度下的活化力学参数, 这个热动力学方程描述的是一系列不规则的细菌生长过程发热曲线, 将它与经典的指数模型和logistic模型进行比较, 它具有更广泛的适用性。     

蛋白质合成(翻译)过程的动力学模型

本文应用耗散结构理论并考虑了原初受精卵细胞中位置调控因素等的影响,给出了蛋白质合成(翻译)过程的动力学模型。研究结果表明,细胞中合成的蛋白质并非均匀分布,而是存在一定的动力学结构,因而可能与原初细胞分化有关。     

相场动力学模型研究细胞运动中的形态变化

细胞运动涉及细胞骨架和细胞之间的相互协同作用, 其中包括细胞膜上的表面张力作用和曲面弹性能的作用、细胞内肌动蛋白聚合时产生的“突起力”和肌球蛋白作用下的“收缩力”、细胞和基板的相互作用等. 为此, 我们基于相场动力学理论和反应扩散理论, 将细胞内肌动蛋白的动态组装行为、肌球蛋白的生理作用、以及细胞与基体的相互作用等因素与细胞的形态变化和运动相耦合关联起来建立新的细胞运动机制模型, 以研究细胞运动中的形态及速度变化. 通过该理论模型预测在一定生理条件下细胞稳态的形态和运动速度, 研究结果表明理论结果和仿生实验结果相对吻合. 此外, 我们还系统研究了细胞运动速度及形态对肌动蛋白与肌球蛋白浓度以及肌动蛋白组装成微丝的速率常数的依赖关系. 同时, 该理论方法还有望进一步拓展到细胞收缩、细胞分裂、细胞在流动场的运动等复杂体系.     

异硫氰酸荧光素标记万古霉素的制备及其与细菌相互作用的荧光检测

以异硫氰酸荧光素(FITC)标记万古霉素(Vanco)制备了FITC-Vanco(FV),FV经高效液相制备色谱纯化后,进行了质谱结构鉴定。分别通过荧光分光光度计和流式细胞仪(FCM)测定不同浓度FV培养基中培养细菌细胞的荧光强度。结果显示,所制备的荧光探针对5种细菌有特异性结合,用荧光强度可表征细胞结合抗生素的数量,对细菌耐药机制研究和细菌对万古霉素作用敏感性的测试有应用价值。     

异硫氰酸荧光素标记万古霉素的制备及其与细菌相互作用的荧光检测

以异硫氰酸荧光素（FITC）标记万古霉素（Vanco）制备了FITC Vanco（FV）,FV经高效液相制备色谱纯化后,进行了质谱结构鉴定。 分别通过荧光分光光度计和流式细胞仪（FCM）测定不同浓度FV培养基中培养细菌细胞的荧光强度。 结果显示,所制备的荧光探针对5种细菌有特异性结合,用荧光强度可表征细胞结合抗生素的数量,对细菌耐药机制研究和细菌对万古霉素作用敏感性的测试有应用价值。     

细菌生长的热动力学性质的研究

前文报导了大肠杆菌在不同培养基中生长的速率及热力学函数.本文在此基础上又测定了不同细菌在相同培养基中生长的规律.细菌生长是一系列非常复杂的过程,为便于研究,使复杂问题简单化,我们采取与过渡状态理论类似的模式进行处理,得出了一些热动力学函数,这些数据为进一步探讨这一复杂过程提供了有用的信息.     

细菌生长速率的测定及其热力学性质的研究

细菌生长是一系列非常复杂的生化反应的结果。为了使问题简化、便于采用物理化学的理论和方法对其进行处理,可假设细菌在培养基中的分裂、生长分为三个阶段进行。首先是底物进行扩散,并与细菌表面的活性物质进行作用(如输运过程);其次是细菌将底物吸收到细胞内形成细胞-底物复合物;然后是细胞-底物复合物在其内部一系列酶的作用下产生酶促反应,进行分裂生长和排出代谢产物。现用下式表示:     

以玉米浆干粉为氮源静态发酵生产细菌纤维素的动力学研究

以木葡糖酸醋杆菌为目标菌种,以玉米浆干粉为氮源,进行了静态发酵生产细菌纤维素(BC)的动力学研究。结果表明,菌体生长适合于Logistic方程,BC生成符合Luedeking-Piret方程,还原糖消耗可用基于物料衡算的基质消耗方程描述,且模型计算值与试验值能较好吻合。因此,利用建立的数学模型可以预测系统的生产率,有效控制和优化静态发酵过程,为日后实现工业化规模生产提供理论基础。     

Polar fluid model of viscoelastic membranes and interfaces

The polar surface fluid model is used to derive the generalized dynamic shape equation and the interfacial rheological material functions for viscoelastic membranes and curved interfaces, taking viscous bending and torsion modes into full account. The materials modeling approach based on the polar surface fluid leads to the integration of bending and torsion dissipative modes with their elastic counterparts that appear in the dynamic shape equation and in the interfacial rheological functions. The covariant bending and torsion rates derived in this paper are shown to be related to the interfacial co-rotational derivative of the curvature tensor. The dynamic shape equation is used to analyze shape fluctuation in planar geometries, and to establish the role of bending dissipation in shape dynamics. The dynamic shape equation generalizes the static Helfrich shape equation by incorporating bending and torsion dissipation, and it generalizes the dynamic shape equation based on the Boussinesq-Scriven model by incorporating bending and torsion elasticity and dissipation.     

Detailed balance condition and effective free energy in the primitive chain network model

We consider statistical mechanical properties of the primitive chain network (PCN) model for entangled polymers from its dynamic equations. We show that the dynamic equation for the segment number of the PCN model does not reduce to the standard Langevin equation which satisfies the detailed balance condition. We propose heuristic modifications for the PCN dynamic equation for the segment number, to make it reduce to the standard Langevin equation. We analyse some equilibrium statistical properties of the modified PCN model, by using the effective free energy obtained from the modified PCN dynamic equations. The PCN effective free energy can be interpreted as the sum of the ideal Gaussian chain free energy and the repulsive interaction energy between slip-links. By using the single chain approximation, we calculate several distribution functions of the PCN model. The obtained distribution functions are qualitatively different from ones for the simple slip-link model without any direct interactions between slip-links.     

Porous media characterization by the two-liquid method: effect of dynamic contact angle and inertia

The validity of using the Lucas-Washburn (LW) equation for porous media characterization by the two-liquid capillary penetration method was tested numerically and experimentally. A cylindrical capillary of known radius and contact angle was used as a model system for the tests. It was found that using the LW equation (i.e., ignoring inertia and dynamic contact angle effects) may lead to very erroneous assessment of the capillary radius and the equilibrium contact angle, for a relatively wide range of capillary radii and equilibrium contact angles. A correct assessment requires the application of a penetration kinetics equation that considers inertia and the dynamic contact angle.     

Dynamic diffuse double-layer model for the electrochemistry of nanometer-sized electrodes

A dynamic diffuse double-layer model is developed for describing the electrode/electrolyte interface bearing a redox reaction. It overcomes the dilemma of the traditional voltammetric theories based on the depletion layer and Frumkin's model for double-layer effects in predicating the voltammetric behavior of nanometer-sized electrodes. Starting from the Nernst-Planck equation, a dynamic interfacial concentration distribution is derived, which has a similar form to the Boltzmann distribution equation but contains the influence of current density. Incorporation of the dynamic concentration distribution into the Poisson and Butler-Volmer equations, respectively, produces a dynamic potential distribution equation containing the influence of current and a voltammetric equation containing the double-layer effects. Computation based on these two equations gives both the interfacial structure (potential and concentration profiles) and voltammetric behavior. The results show that the electrochemical interface at electrodes of nanometer scales is more like an electric-double-layer, whereas the interface at electrodes larger than 100 nm can be treated as a concentration depletion layer. The double-layer nature of the electrode/electrolyte interface of nanometer scale causes the voltammetric responses to vary with electrode size, reactant charge, the value of formal redox potential, and the dielectric properties of the compact double-layer. These voltammetric features are novel in comparison to the traditional voltammetric theory based on the transport of redox molecules in the depletion layer.     

Differential scanning calorimetric study on the curing behavior of epoxy resin/diethylenetriamine/organic montmorillonite nanocomposite

The curing mechanisms and kinetics of diglycidyl ether of bisphenol A with diethylenetriamine as the curing agent and different amounts of organic montmorillonite were examined with isothermal and dynamic scanning calorimetry. The modified Avrami equation was used to calculate the activation energy and reaction orders in the isothermal experiment. A single peak was observed in each dynamic scan. The curing mechanism and kinetics of the curing reaction were also analyzed by two kinds of methods—Kissinger and Flynn–Wall–Ozawa. The results obtained from those methods under dynamic measurement agreed with those obtained from the modified Avrami equation. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 378–386, 2003     

离子液体[Cnpy][NTf2] (n=2, 4, 5)的动力粘度和电导率

在298.15-338.15 K和283.15-338.15 K温度范围内,分别测量了N-烷基吡啶双三氟甲磺酸亚胺(烷基链分别为:乙基、丁基、戊基)三种疏水型离子液体的动力粘度和电导率.利用Arrhenius 方程和Fulcher 方程将测量的动力粘度和电导率对温度拟合,得到了动力粘度和电导率随温度变化方程式.从电导率和密度计算出了上述三种离子液体在283.15-338.15 K温度范围内的摩尔电导率.应用Walden 规则,描述了动力粘度与摩尔电导率之间的关系.     

Dynamic Theory of Die Swell for Entangled Polymeric Liquids in Tube Extrusion: Correlations of Total and Ultimate Extrudate Swell Effects to Growth Time,Shear Stress and Aspect Ratio Under the Free States

The dynamic theory of die swell deduced in a previous paper was extensively applied to study the xtrudate swelling behaviors of two entangled polymeric liquids (HDPE and PBD) in a simple shear flow at steady shear stress. The mechanism and dynamics for the recoils and the recoveries of viscoelastic strains in the extrudate were investigated under the free recovery and dynamic states. It was found that in the course of recovery the free recoil and the growth of die swell in the extrudate may be divided into two recovery regions (instantaneous and delayed regions) and three growth stages (instantaneous, delayed, and ultimate extrudate swelling stages). The free recoil and the extrudate swelling behaviors may be expressed as a function of shear stress. The correlations of instantaneous, delayed, total and ultimate extrudate swell effects to the molecular parameters and the operational variables in the simple shear flow at steady shear stress were derived from the dynamic theory of die swell. Also, two sets of new universal equations on the total extrudate swelling effect (TESE) and ultimate extrudate swelling effect (UESE) were deduced. The first is the universal equation of the logarithmic correlation between the TESE and the growth time under the free and dynamic states; the second is the universal equation of the logarithmic correlation between the UESE and the operational variables under the free and equilibrium states. The first equation was verified by experimental data of PBD with different molecular weights at different operational variables. The second equation was verified by experimental data of HDPE at two temperatures and different operational variables. An excellent agreement result was obtained. The excellent agreement shows that the two universal equations can be used directly to predict the correlations of the TESE and UESE to the growth time, the molecular parameters, and the operational variables under the dynamic and equilibrium states.     

动态模拟法在酸碱滴定中的应用

本文建立了ＮａＯＨ滴定混合酸过程中〔Ｈ〕随滴定剂Ｖ变化的微分滴定方程，选用龙格－库塔算法求解上述微分方程，从而进行ｐＨ随△Ｖ变化的动态模拟计算。本文将离子的活度系数引入计算过程，因而获得了与实验值吻合的模拟计算结果。     

Relationship between the dynamic viscosity of hydrocarbons and the Wiener topological index

Dependences of the dynamic viscosity on the product of the molecular weight into the Wiener topological index to the 2/3 power are obtained for some hydrocarbons. Relationships between the latter quantity and the parameters of the Frenkel-Andrade equation for the temperature dependence of the dynamic viscosity are established.     

The viscosity of aqueous electrolyte solutions and the TTG model

An equation covering the dynamic viscosity from zero to high concentrations has been derived on the basis of the TTG model. The equation is compatible with the Eyring andNMR theories and has a similar form to the Othmer-rule equation. A component of the limiting viscosity slope is shown to be proportional to the Falkenhagen slope. The TTG equation was tested for 20 electrolytes of diverse charge type and found to fit the data within the experimental errors. The equation is simply extended to cover pressure, temperature, and component changes. The viscosities of three multicomponent systems are predicted to within the experimental errors. The derived parameters of the equation were found to be simply related to the TTG volume of the solute.