基于信息获取与加工的教学实施策略——以“分子结构与性质”单元教学为例

从信息获取与加工的视角看,学习的本质是行为主体对特定情境中的信息进行感知、辨识、选取、关联、转化、建模和应用的过程。为解决高中生在化学新知学习及问题解决中普遍存在的畏惧复杂信息、忽视关键信息、信息关联能力弱、信息转化及建模能力不足等问题,文章探讨了基于信息获取与加工的“四备”教研,并据此实施设计“驱动性任务—问题组”、引入“新异问题情境”等教学策略,以引导学生建构知识,并在实际问题的解决中加深对新知的理解。

从“氨的分子结构与性质”谈元素化合物的复习策略

新课改之后,元素化合物的教学内容和教学时间都有了大量的删减,然而元素化合物的考查内容和难度并没有降低,这给元素化合物的教学带来了很多困惑。本文以＂氨的分子结构与性质＂的教学设计为例,结合多年的教学实践,阐述在学完物质结构和反应原理后,如何进行元素化合物的复习。

思维导图在高中化学复习课中的应用研究——以分子结构与性质为例

以化学选修3"分子结构与性质"课本内容为知识载体,以结合思维导图的复习课为教学方式,通过整理"分子结构与性质"教学内容,根据思维导图在中学的实际应用情况,设计并且实施结合思维导图复习课模式的基本环节,确定复习课各环节要达到的目标,帮助培养学生的自主学习能力、提高学生的学习兴趣和思维能力。

大概念统领下的大单元教学设计与实践——以“分子结构与性质”为例

大概念是引领单元教学变革的核心理念,基于大概念的学习单元重构,有利于教师把握教学内容的本质和落实学生核心素养的培养目标。从大概念的确定与解构、教学目标的确定、学习活动的设计与评价等方面设计与实施“分子结构与性质”章节的教学,尝试抽提大概念统领下大单元教学的设计策略和一般方法。

呋咱及其自由基结构和性质的理论研究

采用DMol3程序对呋咱及其双自由基、单自由基的结构和性质(优化几何、振动分析、热力学、反应活性及稳定性)进行了理论研究。结果表明:呋咱环的共轭性较弱,其强弱及分子的热稳定性次序为呋咱>单自由基>双自由基,且N—O键可能是环稳定的"薄弱环节"。呋咱环能够从与之相连的氢原子上转移电子,环获得一定量的电子后,稳定度增加。双自由基对亲核、亲电及自由基反应均有一定的活性,单自由基次之,而呋咱最稳定;所有分子上的N原子可能对反应有一定活性。

2,2-二羟甲基丁醛的结构和性质的理论研究

采用DMol3程序对2,2-二羟甲基丁醛(DMB)的结构和性质(振动频率、热力学、反应活性及稳定性)进行了理论研究。得到了分子的几何构型和各原子上的电荷分布以及前沿分子轨道能级。计算结果表明:DMB分子容易得到电子,且醛基上的碳原子是亲核反应的作用点。

衣康酸酐的结构和性质的理论研究

采用DMol3程序对衣康酸酐的结构和相关性质(振动频率、热力学性质、反应活性及稳定性)进行了理论研究,得到了分子的几何优化构型和各原子上的电荷分布以及前线分子轨道能级。计算结果表明:衣康酸酐分子容易得到电子,且酸酐氧基上氧原子是亲电反应的作用点。

“分子结构与性质”复习课的结构化设计与实践

复习课选取甲醛在生产、生活中的应用作为素材,将福尔马林的用途体现出的甲醛性质作为结构复习的切入点和落脚点,通过问题驱动引发学生对“分子结构与性质”相关知识的回忆和检索,梳理和构建知识层面和认识思路的结构化,进而建立物质的结构与性质之间的关系,深化“结构决定性质,性质决定应用”的化学核心观念,发展学生“宏观辨识与微观探析”及“证据推理与模型认知”方面的化学学科素养。

多溴苊化合物的分子结构和热力学性质

多溴苊是一类潜在的有机污染物。本文采用密度泛函理论在B3LYP/6-311G**水平上优化35个多溴苊化合物的分子几何结构,并获得它们在理想气态的一些热力学性质的数值,研究这些性质与取代的溴原子数目和位置的关系,根据各异构体的标准生成Gibbs自由能的相对大小,求得它们的热力学稳定性顺序。计算结果表明:在大部分多溴苊分子中,除4个氢原子外的其他原子在同一平面上。多溴苊最稳定及最不稳定异构体的ΔfH及ΔfG,都随Br原子数目增加而逐渐增加。溴原子数目相同的多溴苊异构体的ΔfH和ΔfG与溴原子的取代位置有很大的关系,其相对稳定性主要由分子内的处在不同六元环上的邻近Br...Br核排斥作用决定。所有多溴苊化合物在热力学上都比其母体化合物苊相对较难形成。

饱和脂肪酯物理化学性质的定量探讨

采用改进的分子连接性指数1x,建立了饱和脂肪酸酯物理化学性质p的定量公式:P=a+b1x,式中a、b是系 数,对于某一物理化学性质为一定值.预测了含12个碳原子以内的饱和脂肪酸酯的水溶解度、分配系数、保留体积、 沸点和相对密度等五项物理化学性质.

硝酸钆与多孔硅爆炸反应的机理分析

采用基于第一原理计算的DMol3程序,对硝酸钆的结构和性质进行了理论研究,同时探讨了硝酸钆与多孔硅爆炸可能的机理.计算结果表明,基于硝酸钆的几何结构及Mulliken布居分析,推知硝酸钆易于热解产生NO2气体及含能较高的不稳定中间体;且由前线轨道分析得知硝酸钆分子LUMO主要由钆原子5d轨道组成,因此钆原子易接受配体,这2个因素可能是促成硝酸钆与多孔硅爆炸的主要原因.为进一步研究硝酸盐与多孔硅的爆炸提供了理论参考.

基于原子级别的模拟软件在有机化学教学中的应用

如何形象、生动地教学是大学老师在实践教学中努力的方向。为了提高学生学习兴趣和教学效果,本文介绍了采用软件模拟进行课堂教学的方式,探索了其在有机化学教学实践中的应用。

生物活性化合物液相直接化学发光特性的理论预测

基于分子结构与性质的相关性,对已知能在液相产生直接化学发光的典型化合物进行了结构分析,提取出与液相直接化学发光特性相关的分子拓扑指数,以向量夹角余弦系数为判别指标构建了判别方程.并用所建立的化学发光判别函数对101种生物活性化合物的化学发光特性进行了理论预测,正确率为95·05%.

Molecular Dynamics Simulations of Silica Nanotube： Structural and Vibrational Properties Under Different Temperatures

Four-, six-, and eight-membered ring silica nanotubes at temperatures from 300 K to 1600 K are relaxed by classical molecular dynamics simulations with three potential models. The simulation results indicate that the stability of the end rings of the three silica nanotubes gradually decreases with increase in temperature. The validity of the vibrational features of silica nanotubes is shown by the vibrational density of states. Infrared spectra on the silica nanotubes under different temperatures are investigated. A detailed assignment of each spectral peak to the corresponding vibrational mode of the three nanotubes has been addressed. The results are in good agreement with the other theoretical and experimental

Influences of Structure Disorder and Temperature on Properties of Proton Conductivity in Hydrogen-Bond Molecular Systems

The dynamic properties of proton conductivity along hydrogen-bonded molecular systems, for example, ice crystal, with structure disorder or damping and finite temperatures exposed in an externally applied electric-field have been numerically studied by Runge-Kutta way in our soliton model. The results obtained show that the proton-soliton is very robust against the structure disorder including the fluctuation of the force constant and disorder in the sequence of masses and thermal perturbation and damping of medium, the velocity of its conductivity increases with increasing of the externally applied electric-field and decreasing of the damping coefficient of medium, but the proton-soliton disperses for quite great fluctuation of the ＂force constant and damping coefficient. In the numerical simulation we find that the proton-soliton in our model is thermally stable in a large region of temperature of T ≤ 273 K under influences of damping and externally applied electric-field in ice crvstal. This shows that our model is available and appropriate to ice.

Stability and electronic spectra of C_(76) N_2 isomers

Study of geometries of 16 possible isomers for C76N2 based on C78(C2v) by intermediate neglect of differential overlap (INDO) series of methods indicated that the most stable geometry 25,78-C76N2 where two nitrogen atoms substitute two apexes C(25) and C(78) near the shortest X axis and Y axis formed by two hexagons and a pentagon. Electronic structures and spectra of C76N2 were investigated. The reason for the red-shift for absorptions of C76N2 compared with that of C78(C2v) is discussed.

Molecular Characterization of Nonstructural Protein NS38 of Grass Carp Reovirus

Viral nonstructural proteins in both enveloped and non-enveloped viruses play important roles in viral replication. Protein NS38 of Grass carp reovirus (GCRV), has been deduced to be a non-structural protein, and, consistent with other reoviruses, is considered to cooperate with the NS80 protein in viral particle assembly. To investigate the molecular basis of the role of NS38, a complete protein was expressed in E.coli for the first time. It was found that there is a better expression of NS38 induced with IPTG at 28 ℃ rather than 37 ℃. In addition, the antiserum of NS38 prepared with purified fusion protein and injected into rabbit could be used for detecting NS38 protein expression in GCRV infected cell lysate, while there is not any reaction crossed with purified virus particle, confirming NS38 is not a component of the viral structural protein. The result reported in this study will provide evidence for further viral protein-protein and protein-RNA interaction in dsRNA viruses replication.

Electronic and Optical Properties of Cubic SrHfO_3

In order to clarify the mechanism of optical transitions for cubic SrHfO_3, we have investigated the electronicstructure and optical properties of cubic SrHfO_3 using the plane-wave ultrasoft pseudopotential technique based on thefirst-principles density-functional theory (DFT).The ground-state properties, obtained by minimizing the total energy,are in favorable agreement with the previous work.From the band structure and charge densities as well as the theoryof crystal-field and molecular-orbital bonding, we have systematically studied how the optical transitions are affected bythe electronic structure and molecular orbitals.Our calculated complex dielectric function is in good agreement withthe experimental data and the optical transitions are in accord with the electronic structure.

Structure characteristics and adhesive property of humic substances extracted with different methods

The structure characteristics and adhesive property of humic substance(HS) extracted with different methods were mainly studied by terms of elementary analysis,visible spectrum,FT-IR spectroscopy,viscosity,adsorption and pelletizing experiments.The results show that HSs extracted with new method(HS-a) own higher degree of aromatization and polymerization,larger relative molecular mass and more polar functional groups than HS extracted with usual method(HS-b).The viscosity of HS-b is about 30-40 mPa·s lower than that of HS-a.The maximum adsorption amounts of HS-a and HS-b onto iron concentrates are 9.11 mg/g and 8.08 mg/g,respectively.Meanwhile,HS-a has a better performance than HS-b in the practical application for pelletizing of iron concentrates.The difference in agglomeration behaviors with iron concentrates lies in the differences of the structure characteristics of HSs.With higher content of polar functional groups,larger relative molecular mass and viscosity of HSs,the agglomeration behavior is improved.

Computational Calculations of Molecular Properties and Molecular Docking of New and Reference Cephalosporins on Penicillin Binding Proteins and Various β-Lactamases

An approach of using molinspiration calculations and molecular docking on PBPs （penicillin-binding proteins） and certain β-lactamases is employed to predict the molecular properties, bioactivity and resistance of newer and reference cephalosporins. The previously synthesized cephalosporins 1-8 and reference cephalosporins were subjected to extensive evaluations by calculating the molecular properties, drug-likeness scores on the bases of Lipinski＇s rule and bioactivity prediction using the method of molinspiration web-based software. The TPSA （topological polar surface area）, OH-NH interactions, n-violation and the molinspiration Log partition coefficient （miLogP） values were also calculated. The investigated cephalosporins were subjected to molecular docking study on PBPs （lpyy） and on β-lactamases produced by S. aureus, K. pneumonia, E. coil and P. auroginosa using 1-click-docking website. Molecular properties of 1-8 recorded higher ＂FPSA than cephalexin and were lower than the reference cephalosporins and do not fulfill the requirements for Lipinski＇s rule. Bioactivities of 1-8 were predicted to be less and their docking scores on PBPs were comparable to those of the reference cephalosporins, particularly ceftobiprole. The references recorded various docking scores on the above β-lactamases and as expected, cefiobiprole recorded the lowest scores on all β-lactarnases. Cephalosporins 1-8 recorded various docking scores on β-lactamases. Molecular docking studies on PBPs and β-lactamases are considered as very useful, reliable and practical approach for predicting the bioactivity scores and to afford some information about the stability and selectivity of the newly proposed cephalosporins against β-lactamases of certain pathogenic microbes, such as P. auroginosa and MRSA, by recording the relative docking scores in comparison with those of reference cephalosporins.