采用压敏凝胶和变压循环增强传质──改善固定化酶促反应的新途径

引言聚合物凝胶是最常用的酶固定化材料．然而凝胶固定而曲折的孔结构又具有较大的传质阻力．底物、产物、营养物等在固定化材料中受到的阻滞使催化反应减慢，从而成为固定化酶促反应中最严重的问题．环境敏感性凝胶为克服固定化酶中的高传质阻力提供了新思路．这种凝胶可随pH值、温度、溶剂组成或电场等的微小变化而产生体积的显著改变，并已在生化分离，化学驱动器、药物控制释放及人工肌肉等领域显示了良好的实用前景．Hoffman等的研究又显示了温敏性凝胶在固定化酶和细胞上的潜在应用价值。以此为基础，并基于Lee等关于凝胶压敏性的新…     

化学激发与热处理耦合作用对再生微粉的活性激发

为研究化学激发、热处理及两者耦合作用对再生微粉的活化效果,本文采用抗压强度测试、X射线衍射测试、红外光谱测试等对再生微粉的力学性能、矿物组成、反应产物类型进行了研究。结果表明,化学激发能够提供碱性环境及可反应的离子,高温煅烧能够改变原有物质的矿物结构,两种方式均可使再生微粉具备再水化胶凝的能力。高温热活化后,再生微粉的硅铝体结构发生重组或破坏,矿物中的基团在化学激发时更易溶出,参与反应形成胶凝产物,此时再生微粉的3、28 d抗压强度分别达到27.0、48.6 MPa,与原试件相比,强度值分别提高了10.3倍与5.8倍,耦合作用使再生微粉具有更高的活性及强度。     

固定化HRP/H2O2/ACAC酶促体系引发下降解淀粉接枝丙烯酰胺共聚物的合成与表征

以壳聚糖为载体、戊二醛为交联剂制备固定化辣根过氧化物酶（HRP）,采用固定化HRP/H₂O₂/乙酰丙酮（ACAC）酶促体系制备降解淀粉-丙烯酰胺接枝共聚物（St-g-PAM）,通过红外光谱、紫外光谱、核磁共振和电镜扫描等手段对接枝共聚产物进行了结构分析。结果表明,丙烯酰胺成功接枝在降解淀粉上。共聚物用做皮革复鞣剂进行了应用实验,应用结果表明复鞣后的革柔软、纤维分散好和选择填充性强。     

THE EFFECT OF PORE DIFFUSION ON THE SHAPE OF THE PH AND TEMPERATURE PROFILES OF IMMOBILIZED ENZYMES

The effect of diffusion on the pH and temperature profiles of immobilized enzymes has been quantitatively assessed using the theory of pore diffusion. The pH profiles of immobilized enzyme systems varied from those of soluble ones to the square root of the relative values of the soluble ones depending on the degree of pore diffusion limitation. Also the decrease in activation energy was predicted quantitatively with considerable accuracy in terms of effectiveness factor. The experimental pH profiles of a few immobilized enzymes were compared with those theoretically predicted.     

动态膜分离式固定化酶反应过程分析

测定了实验系统下固定化酶的本征动力常数,从动力学角度分析研究了所开发研制的动态膜分离式固定化酶反应器（DMIR）的反应过程,给出了无外扩散限制条件下的DMIR反应器的数学模型,并验证了实验方法的可靠性。     

照相明胶与化学增感剂相互作用的XPS研究

本文采用Ｘ射线光电子普技术研究了两种照相明胶与化学增感剂相互作用的机理,当两种照明明胶样品在ＨＡｕＣｌ５溶液中反应５ｍｉｎ后,明胶中的蛋氨酸,蛋氨酸亚砜均被氧化为蛋氨酸砜。与此同时,明胶吸附的大部分Ａｕ＾３＋被还原为Ａｕ＾＋,并且Ａｕ＾＋以络合形态存在于明胶之中。     

MIXING WITH DIFFUSION AND FAST CHEMICAL REACTION IN SIMPLE SHEAR FLOW: A COMPARISON OF STRETCH MODEL TO TWO-DIMENSIONAL DIFFUSION WITH PERIODIC BOUNDARY CONDITIONS

The lamellar stretch model for describing mixing with simultaneous diffusion and fast chemical reaction is evaluated for simple shear flow between two parallel plates by comparing the predicted concentration profiles to those computed from the governing partial differential equation. A direct algorithm is devised to solve the sparse matrix originating from the discretization of the PDE. Under conditions where initial striation thickness equals the characteristic dimension of the flow geometry, the lamellar stretch model turns out to be quite accurate for k ≥ 10⁶ or k ≤ 1, where k is the product of the Reynolds number and the Schmidt number. In the intermediate range of k values, where mechanical and diffusional mixing are of comparable importance, the model is less accurate     

A COMPARISON OF APPROXIMATE AND EXACT SOLUTIONS FOR HOMOGENEOUS IRREVERSIBLE CHEMICAL REACTION IN THE LAMINAR BOUNDARY LAYER

A comparison of approximate and exact solutions for homogeneous irreversible chemical reaction in the laminar boundary layer flow has been made. By using the Method of Weighted Residuals, approximate analytical expressions for the velocity and concentration profiles were developed for the case of a laminar boundary layer flow over a flat plate at zero incidence angle, where isothermal, homogeneous, nth order chemical reaction takes place. Both the Subdomain and Galerkin methods were employed to examine the influence of the choice of the weighting function on the predictions, and to provide a means for improving the solutions systematically. The problem was also solved numerically for the case of first order reaction by using a similarity solution for the hydrodynamic flow and a power series expansion method for the mass transfer. The analytical results were compared with the exact solutions in order to evaluate the accuracy of the approximate analytical solutions. The Method of Weighted Residuals provided approximate solutions that are qualitatively correct and, within limits, quantitatively accurate. The resulting approximate expressions can be used to give quick estimates for reactions investigated herein and to predict the results for higher order reactions when there are no exact solutions.     

MHD MIXED-CONVECTION INTERACTION WITH THERMAL RADIATION AND nTH ORDER CHEMICAL REACTION PAST A VERTICAL POROUS PLATE EMBEDDED IN A POROUS MEDIUM

This article investigates the hydromagnetic mixed convection heat and mass transfer flow of an incompressible Boussinesq fluid past a vertical porous plate with constant heat flux in the presence of radiative heat transfer in an optically thin environment, viscous dissipation, and an nth order homogeneous chemical reaction between the fluid and the diffusing species. The dimensionless governing equations for this investigation are solved numerically by the fourth-order Runge-Kutta integration scheme along with shooting technique. Numerical data for the local skin-friction coefficient, the plate surface temperature, and the local Sherwood number have been tabulated for various values of parametric conditions. Graphical results for velocity, temperature, and concentration profiles based on the numerical solutions are presented and discussed.     

模拟单颗粒催化剂上多组份反应扩散过程的通用软件的开发

本文在尘气传递模型的基础上,开发了在微机上实现的模拟单粒催化剂多组份多反应体系反应扩散过程的通用软件。它可用于横拟速率方程为任意形式的,扩散系数随温度、浓度变化的,不同形状颗粒、粒外有或无扩散效应时等温或非等温的反应扩散过程。本软件具有管理功能强、模型精度高、算法先进以及适用性广等特点,并配有彩色图形输出,是辅助催化剂设计和分析反应器性能的有效工具。     

THERMAL-DIFFUSION AND DIFFUSION-THERMO EFFECTS ON NATURAL CONVECTION ALONG AN INCLINED STRETCHING SURFACE IN A POROUS MEDIUM WITH CHEMICAL REACTION

The steady natural convection along an inclined stretching surface in the presence of chemical reaction under thermal-diffusion and diffusion-thermo effects is studied. The governing equations for continuity, momentum, energy, and concentration are transformed by similarity transformation and then solved numerically using the Runge-Kutta integration with shooting scheme. Comparisons between the present data with previously published work are performed and found to be in very good agreement with each other. The obtained results show that the flow, thermal, and diffusion fields are influenced appreciably by the effects of endothermic or exothermic chemical reaction, angle of inclination, thermal radiation, magnetic field, and Soret and Dufour numbers. The physical phenomenon can be realized from the graphical profiles and in tabular form to depict special features of the solutions.     

关于中国外销瓷器绘画的西化在18世纪中西经济美术文化交流与互动中的作用

中国出口艺术的西化,特别是外销瓷的西化,是18世纪中西经济美术文化交流与互动的一个引人入胜的重要课题。由于中国瓷绘装饰画家在西洋画技术上的造诣和宫廷御窑珐琅彩绘在景德镇烧制成功,甚而中国瓷器装饰艺术西化之赞助人的速增,形成西方绘画随经济交流持续东渐中国,中国西画(瓷器上的)返销西方的互动现象———即中西美术文化的交流又大大促进了中西经济文化的交流与互动。