物理化学教学研究会第三次会议纪要

物理化学教学研究会第三次会议以物理化学实验教学改革与建设为主题,介绍了教指委制订的实验教学建议内容,并就今后的物理化学实验教学改革进行了交流和研讨。本文介绍了物理化学实验的特点、当前的改革进展及其局限性,总结了部分高校在实验的目标导向设计、教学模式改革、教学理念和方法改革、教学达成度考核设计、实验新原理新方法引入等方面的做法和经验。论述了近期需要开展的重点工作。对今后的物理化学实验教学改革和建设具有一定的指导意义。     

光学实验的计算机仿真

基于计算机仿真技术,以光学干涉实验和滤波实验为研究对象,应用Matlab软件数值模拟了杨氏双缝干涉实验和多光束干涉实验干涉图形和光强分布图,数值模拟了光学滤波实验字母滤波后的频谱图和字母成像图,结果表明,计算机仿真结果能够清晰的表达出实验和理论的效果。研究结果为光学实验的课堂教学提供了参考。     

《聚合物改性》课程线上教学的探索

本文分析了新冠疫情形势下《聚合物改性》课程线上教学实施的问题.依托"QQ课堂"和"超星学习通"平台,通过"在线讲授理论环节"和"居家实验"相结合的形式,开展了融"理论+实践"为一体的《聚合物改性》课程在线教学.把需要在实验室完成的实验生活化,既锻炼了学生的动手能力又能尝试自己制作的美食,既激发了学生的学习兴趣,又进行了...     

Experimental investigation of a developing two-phase bubbly flow in horizontal pipe

Experimental results for various water and air superficial velocities in developing adiabatic horizontal two-phase pipe flow are presented. Flow pattern maps derived from videos exhibit a new boundary line in intermittent regime. This transition from water dominant to water–gas coordinated regimes corresponds to a new transition criterion C_T = 2, derived from a generalized representation with the dimensionless coordinates of Taitel and Dukler.Velocity, turbulent kinetic energy and dissipation rate, void fraction and bubble size radial profiles measured at 40 pipe diameters for J_L = 4.42 m/s by hot film velocimetry and optical probes confirm this transition: the gas influence is not continuous but strongly increases beyond J_G = 0.06 m/s. The maximum dissipation rate, derived from spectra, is increased in two-phase flow by a factor 5 with respect to the single phase case.The axial evolution of the bubble intercept length histograms also reveal the flow organization in horizontal layers, driven by buoyancy effects. Bubble coalescence is attested by a maximum bubble intercept evolving from 2.5 to 4.5 mm along the pipe. Turbulence generated by the bubbles is also manifest by the 4-fold increase of the maximum turbulent dissipation rate along the pipe.     

Experiment on the object-image distance parameter in the X-ray phase contrast imaging system

For the X-ray phase contrast imaging system, in addition to the hardware-related parameters, the object-image distance is an important parameter that affects the imaging results. Based on the Fresnel diffraction theory, the X-ray phase contrast formation mechanism is analyzed to find the theoretical relationship between the object-image distance parameter and the image contrast. Through the experimental simulation on a ball model, images with edge enhancement effect and image contrast data were obtained with regard to different object-image distance conditions. The analysis and experimental results show that, clear image information about the edges of the sample structures can be got if the object-image distance parameter is set suitably.     

物理实验教学新模式的探索与实践

提出了一种新的物理实验教学模式，论述了建立实验教学模式所遵循的基本原则和基本做法，简要介绍实施新的教学模式所取得的教学成果。     

Ultrafiltration of a polymer-electrolyte mixture

We present a mathematical model to describe the ultrafiltration behaviour of polymer-electrolyte mixtures. The model combines the proper thermodynamic forces (pressure, chemical potential and electrical potential differences) with multicomponent diffusion theory. The model is verified with experimental data on the ultrafiltration of aqueous solutions of PEG-4000 and potassium phosphate. The single solute rejection of PEG-4000 goes through a maximum as also found by others. The single solute rejection of potassium phosphate depends on the ionic strength of the solution. At low ionic strength rejections are found of 50%. Solutions containing a high concentration of PEG-4000 and potassium phosphate show a negative rejection for potassium phosphate. This is caused by the strongly non-ideal behaviour of these aqueous solutions. The model predicts the behaviour of single solute experiments quite well, but some deviations are found with the mixed solute experiments. However, negative rejections found in the mixed solute experiments are predicted by the model.     

Evaluation of the use of consensus values in proficiency testing programmes

Proficiency testing (PT) is an essential tool used by laboratory accreditation bodies to assess the competency of laboratories. Because of limited resources of PT providers or for other reasons, the assigned reference value used in the calculation of z-score values has usually been derived from some sort of consensus value obtained by central tendency estimators such as the arithmetic mean or robust mean. However, if the assigned reference value deviates significantly from the ‘true value’ of the analyte in the test material, laboratories’ performance will be evaluated incorrectly. This paper evaluates the use of consensus values in proficiency testing programmes using the Monte Carlo simulation technique. The results indicated that the deviation of the assigned value from the true value could be as large as 40%, depending on the parameters of the proficiency testing programmes under investigation such as sample homogeneity, number of participant laboratories, concentration level, method precision and laboratory bias. To study how these parameters affect the degree of discrepancy between the consensus value and the true value, a fractional factorial design was also applied. The findings indicate that the number of participating laboratories and the distribution of laboratory bias were the prime two factors affecting the deviation of the consensus value from the true value.     

以应用和创新能力培养为核心,构建有特色的地方师范院校高分子实验教学体系

高分子实验是材料学专业特别是高分子材料专业的核心课程。本文结合我们学校十余年开设高分子实验并不断完善的实际情况,对高分子实验的教学体系从如何开设地方工业相关实验、开设应用性实验项目、教育性实验项目、开放性实验项目、系统性实验项目以及编写实验教材等六个方面进行归纳总结。我们以应用和创新能力培养为核心,构建有特色的地方师范院校高分子实验教学体系的措施与教学实践或可为同类型或类似兄弟院校的高分子实验教学提供有益的参考。