A Cognitive Modeling Tutor Supporting Student Inquiry for Balancing Chemical Equations

Improved interactive tutoring capabilities in educational software for chemistry problem solving is an important need that has been clearly articulated by teachers and students. The purpose of this work is to examine the incorporation of new concepts from the field of artificial intelligence (AI) as a route to meaningful individualized tutoring. The basic shift is to replace specific foreknowledge of problems with a direct representation of chemical and pedagogical principles and then simulate reasoning using these principles to tutor students. To assess the potential of an AI-based approach, we have developed a prototype tutorial program for balancing chemical equations that contains two important advances. First, the system can create a worked-out solution with detailed explanations for any equation entered by the student or teacher. Unlike a conventional tutorial, this is done dynamically, without the equation being stored ahead of time. Second, the program can interactively answer a variety of detailed questions about its work at each step. Studying worked-out examples plays an important role in learning, and this approach to supporting interactive student inquiry is being investigated as a method of cognitive modeling and apprenticeship intended to foster the students own self-explanation and question-asking abilities.     

通识化学:有机物燃烧方程式的简易配平法

在通识化学的教学层面上,面向不同背景的学生,以简单有机物完全燃烧的化学方程式的配平为主题,梳理数学方法在化学方程式配平中的应用和特点,采用跨学科的方式,让学生能从不同的角度进行思考和学习,以掌握数学方法在化学中的应用。     

A Concise Description of an Old Problem: Application of Matrices to Obtain the Balancing Coefficients of Chemical Equations

It is not difficult to balance chemical equations and thus it is hardly given more thoughts. However, there is a mathematical principle for the balancing of chemical equations and this principle may be used for automation. The balancing of chemical equation is carried out, by formulating a reaction matrix and the latter is used in a matrix equation. The matrix equation is then solved to obtain the balancing coefficients. The conventional matrix inverse method cannot always be used and hence the solution is obtained by row reduced operations. These operations and any matrix manipulation are carried out with Matlab. Further this novel method can be used to classify chemical equations as nonfeasible, unique and nonunique.     

Modeling of Swelling Behaviors of Acrylamide-Based Polymeric Hydrogels by Intelligent System

Hydrogels based on acrylamide (AAm) were synthesized by free radical polymerization in an aqueous solution using N,N’-methylenebisacrylamide (MBAAm) as crosslinker. To obtain anionic hydrogels, 2-acrylamido-2-methylpropanesulfonic acid sodium salt (AMPS) and acrylic acid (AAc) were used as comonomers. The swelling behaviors of all hydrogel systems were modeled using an artificial neural network (ANN) and compared with a multivariable least squares regression (MLSR) model and phenomenal model. The predictions from the ANN model, which associated input parameters, including the amounts of crosslinker (MBA) and comonomer, and swelling values with time, produce results that show excellent correlation with experimental data. The parameters of swelling kinetics and water diffusion mechanisms of the hydrogels were calculated using the obtained experimental data. Model analysis indicated that the ANN models could accurately describe complex swelling behaviors of highly swellable hydrogels.     

基于认知结构测查的化学概念学习评价——以“化学键”为例

通过流程图法对高中生“化学键”认知结构测查的结果表明：在“化学键”概念的学习过程中,多数学生在建构知识的过程中注重对概念文字表述的记忆,而欠缺对相关概念内涵的深层次理解,尤其对“化学键”相关概念中所蕴含的化学学科观念较为忽视,认知困难主要表现在“离子键与共价键的本质”“离子键的形成过程”等内容中。     

开发面向分析化学的复杂方程绘图求解软件

化学平衡的精确解析会涉及复杂方程的求解,而分析化学专业人员通常不完全具备相关算法和编程知识。所以,尽管当前硬件发达、编程语言丰富,精确解析仍然难以在分析化学课程中大规模推广。为此,基于Matlab语言,开发了具有针对性的方程求解软件。该软件以简洁的界面、直观的图像和自然的人机交互,实现方程的高效求解;对用户的编程要求非常低。期望通过这种方式,显著降低化学平衡精确解析中的软件使用成本,从而为大规模推广提供进一步的支持。本文介绍了该软件的基本原理和主要特点;通过3个复杂化学平衡实例,详细说明软件的使用方法以及注意事项。另外提供Android系统版本,免费使用。     

Chemical Epigenetics: The Impact of Chemical and Chemical Biology Techniques on Bromodomain Target Validation

Epigenetics is currently the focus of intense research interest across a broad range of disciplines due to its importance in a multitude of biological processes and disease states. Epigenetic functions result partly from modification of the nucleobases in DNA and RNA, and/or post‐translational modifications of histone proteins. These modifications are dynamic, with cellular machinery identified to modulate and interpret the marks. Our focus is on bromodomains, which bind to acetylated lysine residues. Progress in the study of bromodomains, and the development of bromodomain ligands, has been rapid. These advances have been underpinned by many disciplines, but chemistry and chemical biology have undoubtedly played a significant role. Herein, we review the key chemistry and chemical biology approaches that have furthered our study of bromodomains, enabled the development of bromodomain ligands, and played a critical role in the validation of bromodomains as therapeutic targets.     

建模思想在化学原理教学中的运用

通过竞争反应与海水晒盐2个案例,阐述了在化学原理教学过程中运用建模思想,可以使复杂的过程变得简洁、抽象,从而明晰现象背后的原理、规律。     

“压强对化学平衡的影响”定量实验的探讨与商榷

通过对《化学教育》2015年第9期文章《一个定性到定量实验的创新案例——"压强对化学平衡的影响"实验改进》的探讨和12次定量实验验证,创新了NO_2气体制备、充装方法,并对该改进实验中不可忽视的4个细节问题提出解决方案,从实验数据不具备可重复性的角度,说明该实验"从定性到定量"的设想在实际中是不可能达成的。     

定量化学分析实验中的教与学

表述了如何摆正定量化学分析实验中验证性经典实验与设计性实验的关系。利用验证性经典实验为培养学生手、眼、脑并用能力打下基础;利用设计性实验培养学生分析、解决问题的能力。     

Diffuse Interface Modeling of Droplet Impact on a Pre‐Patterned Solid Surface

Summary: The impact of a droplet on a solid surface, pre‐patterned with a barrier, was studied using a diffuse interface model. The effect of the wettability of the barrier material and the width of the barrier on droplet spreading was investigated. The results show that depending on the barrier wettability and width, the flow of the spreading droplet can be controlled and that the droplet may or may not overflow the barrier.

Droplet shapes with the corresponding velocity field for different barrier contact angles at ± = 1.5.     

Crocodile Chemistry605在化学定量实验教学中的应用

Crocodile Chemistry 605软件特有的微观结构以及反应细节能够促进学生核心素养“宏观辨识与微观探析” “变化观念与平衡思想”的教学。以具体案例展示如何将Crocodile Chemistry 605这款仿真实验软件应用于定量实验教学中,旨在为教师的化学实验教学提供一款新颖、实用、科学、可定量的仿真教学软件。     

Fermentation Monitoring Based on HPTLC-OPLC. The Effect of a Complex Biological Matrix on Quantitative Performance

JPC – Journal of Planar Chromatography – Modern TLC - An OPLC method has been established for separation and quantification of eight carbohydrates (glucose, fructose, galactose,...     

Indirect Optical Analysis of a Dynamic Chemical System

Hide and seek : The composition of a dynamic covalent equilibrium reaction is determined by measuring the ‘left‐over’ concentration of a reference compound (blue object, see picture). Reaction of the reference compound with a scavenger generates a characteristic UV/Vis signal that is independent of the molecular structure of the target.

     

化学专业研究生职业伦理教育与化学实验室的管理

结合具体实例,分析了当前化学专业研究生进行职业伦理教育的必要性,探讨了研究生职业伦理教育对化学实验室管理的积极作用,阐述了化学实验室管理促进研究生职业伦理教育的主要途径,为化学专业的研究生教育和化学实验室的管理提供了有益参考。     

电极功函数对TiO2/PbS平面异质结激子太阳电池性能影响的理论模拟

采用一维微光电子结构分析模型(AMPS-1D)软件模拟分析了由TiO2纳米晶薄膜与PbS量子点薄膜组成的平面异质结激子太阳电池中电极功函数对电池性能的影响. 通过在界面上引入厚度为2 nm的激子发生分离的自由载流子产生层, 得到电池的电流-电压曲线、 电子电流及空穴电流的空间分布等信息. 模拟结果表明, 透明导电氧化物电极的功函数可以在一定区间内变化而不影响电池效率, 但是金属电极功函数的变化则会明显影响电池输出性能, 这是因为PbS与金属电极之间的肖特基(Schottky)接触会对电池性能产生负面作用.     

基于导数光谱融合建模的红外光谱定量分析方法

设计了基于奇摄动技术的导数光谱估计器并提出基于不同阶次导数光谱空间的融合建模定量分析方法。方法充分利用导数光谱信息空间、区间最小二乘法和融合建模的优点,挖掘光谱深层次信息进行融合建模。分别利用麦汁浓度范围4.23~18.76° P (柏拉图度)的啤酒红外光谱公共数据集和配制的浓度为0.04%~5%范围的葡萄糖溶液实测光谱数据集进行定量分析方法的对比实验。实验结果表明,融合建模定量分析方法能获得最小的预测均方根误差(RMSEP),其值分别为0.121和0.087,能够准确地进行定量分析。与其它建模方法相比较,基于导数光谱的融合建模方法所建立的预测模型具有明显优越的性能。     

对体系局部进行高精度量子化学计算的研究

用对大体系的局部区域进行高精度量子化学计算的新方法，对腈、酰胺、醚、醛、羧酸、硝基化合物、卤代物等不同类型的多种有机分子体系进行计算，得到电荷分布、键断裂能、电离势与电负性等方面的数据.为了比较，同时对上述体系进行整体的和模型体系的高精度计算.局部高精度计算与整体高精度计算的结果相当一致，优于模型体系的计算结果，进一步表明了局部高精度量子化学计算方法的可行性.