从分子图像到热力学框架——物理化学教学的探讨与实践

化学的核心是基于原子分子的图像认识世界、创造物质,化学教育需要培养学生掌握相应的思维方式。在物理化学类课程建设中,浙江大学化学系尝试把宏观化学的基本理论框架,即热力学理论建立在原子分子水平上。具体地是先简述量子化学对单个原子、分子能级结构的处理,然后利用统计热力学的基本原理,从这些量子化的能级导出宏观系统的三个基石性概念(能量、熵、温度)和一条基本定律(熵增加原理),从而建立分子图像的热力学。在教学实践中,强调直接从原子分子层面切入、弱化热机理论、理论与实验结果直接关联。在本文中,我们通过几个教学实例来分享我们的教学经验。     

Discriminating between Parallel,Anti-Parallel and Hybrid G-Quadruplexes: Mechanistic Details on Their Binding to Small Molecules

G-quadruplexes (G4) are now extensively recognised as a peculiar non-canonical DNA geometry that plays a prime importance role in processes of biological relevance whose number is increasing continuously. The same is true for the less-studied RNA G4 counterpart. G4s are stable structures; however, their geometrical parameters may be finely tuned not only by the presence of particular sequences of nucleotides but also by the salt content of the medium or by a small molecule that may act as a peculiar topology inducer. As far as the interest in G4s increases and our knowledge of these species deepens, researchers do not only verify the G4s binding by small molecules and the subsequent G4 stabilisation. The most innovative studies now aim to elucidate the mechanistic details of the interaction and the ability of a target species (drug) to bind only to a peculiar G4 geometry. In this focused review, we survey the advances in the studies of the binding of small molecules of medical interest to G4s, with particular attention to the ability of these species to bind differently (intercalation, lateral binding or sitting atop) to different G4 topologies (parallel, anti-parallel or hybrid structures). Some species, given the very high affinity with some peculiar G4 topology, can first bind to a less favourable geometry and then induce its conversion. This aspect is also considered.     

Binding Delocalization in Polymer Inclusion Complexes of Ring Molecules: Pseudopolyrotaxanes of α-Cyclodextrin and Poly(ethylene glycol)

With polymer substrates, the continuous variation method based on monomer unit concentration underestimates the number of monomer units covered by a low-molecular-weight ligand. Accordingly, gel permeation chromatography confirms that an α-cyclodextrin (α-CD) molecule occupies more than previously claimed two ethylene glycol units in solid α-CD/poly(ethylene glycol) inclusion complexes. Consequently, the poly(ethylene glycol) chain cannot be modeled as an array of distinct binding sites corresponding to two monomer units and no preferred positions, i.e., no distinct binding sites probably exist on the chain for α-CD threading. The effect of such binding delocalization can be assessed using the theory of binding large ligands to a finite one-dimensional lattice [I.R. Epstein: Biophys. Chem. 8, 327 (1978)]. Binding delocalization slightly decreases the average occupancy with highly occupied chains but strongly promotes the occupancy in the case of weak binding. This may be an additional reason for observed high yields of precipitated CD/polymer complexes.     

基于思维模型建构的高三化学复习教学*—— 以“平衡原理的应用”为例

以高三复习课“平衡原理的应用”为例,通过真实情境的剖析让学生感知模型,引导学生分析归纳提炼模型,并进行针对练习运用模型,变式训练体会模型,让学生在实践中以模型思维为突破,深入领悟建构模型的实质,有序解决复杂化学问题,提升科学思维能力,发展化学学科核心素养。     

基于全极化连续介质模型计算溶液分子的第一原理电子结构理论方法的发展和应用

This is a brief review of some recent progress in the development and application of first-principles electronic structure approaches for molecules in solution.In particular,it accounts for the background,theoretical features,and representative applications of a recently developed,truly accurate continuum solvation model which is known as Surface and Volume Polarization for Electrostatics(SVPE) or Fully Polarizable Continuum Model(FPCM) in literature.The FPCM-based first-principles electronic structure approaches have been widely employed to study a variety of chemical and biochemical problems and serve as an integrated part of various computational protocols for rational drug design.Some perspective of the future of the FPCM-based first-principles electronic structure approaches is also given.     

基于核心素养发展的高中化学深度教学——探究配合物的性质

基于深度教学理论,从主体性、对话性和关联性,广度、深度和参与度等开展“配合物性质探究”的深度教学。以层层推进的探究实验和科学严谨的推理论证,建立配合物性质和结构的相互关系,搭建配合物电离平衡模型,逐步实现从宏观到微观,从定性到定量的高阶思维培养。在探讨问题的过程中,形成学科认识思路,发展化学学科核心素养。     

基于变构学习模型的高中化学“导致悖论”教学设计*

“导致悖论”教学是一种智在创境、妙在引领的教学,其核心理念源自于变构学习模型的悖论思想,给学习者创造一个“肯定→否定→肯定”的反思性学习过程。高中化学教学设计可以通过4种途径分别创设“概念与概念”相悖、“理论与实验”相悖、“理论与理论”相悖和“实验与实验”相悖的悖论情境,最终实现学生新旧概念的更替和高阶思维能力的发展。“导致悖论”教学在实施中要注意精选合适的知识内容,加强学生心理的调控,提供丰富的支撑材料。     

The Influence of Xanthate‐Based Transfer Agents on Styrene Emulsion Polymerization: Mathematical Modeling and Model Validation

A mathematical model was developed to account for the evolution of polymer product attributes in the emulsion polymerization of styrene. The effects of transfer agent, surfactant, initiator and temperature were investigated. Polymerization rate, and particle size decreased with increasing concentration of the transfer agent. The polymerization rate increased with increasing surfactant and initiator concentrations, while an increase in temperature led to a decrease of molecular weight but an increase of polymerization rate and particle size. Chain extension was successfully achieved in the presence of our RAFT agent. The model predictions compared well with our experimental results.

     

基于认识模型建构与应用的化学教学设计*——“水溶液中的离子反应与离子平衡”一轮复习课

分析了“水溶液中的离子反应与离子平衡”主题内容,通过学生前测发现学生对这一部分内容的认识存在着认识水平较低、认识不够深入等问题。针对这一问题,在实际教学中通过构建水溶液中的离子反应与离子平衡认识模型的方式,创设真实的问题情境,引导学生明确任务类型、丰富认识角度、形成认识思路,从而使学生对主题内容的认识走向深入和系统。通过后测,分析了教学效果,进行了教学反思,为在教学实践中开展认识模型建构教学提供参考。     

基于发展初中生化学学科核心素养的“分子”教学设计 ——分子构成物质的模型建构与应用

基于化学学科核心素养理念,以宏观的实验数据和现象作为切入点,引出分子的性质与构成,在此基础上,重点介绍由分子如何构成物质的微观模型,再运用该模型解释物质的性质、变化与种类的宏观问题,并在此过程中培养学生化学学科核心素养。     

从化学学科核心素养到学生学习活动*——基于证据推理与模型认知的“空气”教学

以学生活动为载体,借助表现性评价,有助于学生学科核心素养的形成。根据“表现性评价”和“证据推理与模型认知”的内涵,从“获取推理证据”“基于证据推理”“建立认知模型” “基于模型认知”等4个维度提出表现性评价量规,以 “空气”第1课时教学内容为例,设计表现性任务。介绍了在“空气”第1课时的教学中,教师在课堂上基于表现性评价观测学生课堂表现,并根据学生素养达成情况及时调整教学,展开“教、学、评”一体化的教学过程。     

基于元素化合物认识模型的单元教学设计实践探索——以“铁及其化合物”单元教学为例

从元素化合物认识模型出发, 以“铁及其化合物”为例设计单元教学, 阐述了基于元素化合物认识模型建构与应用的单元教学设计思路, 并从确定单元主题, 确定单元教学目标, 厘清单元教学起点, 设计单元教学进阶, 在真实情境中创设活动, 实施“教学评”一体化设计等方面进行单元教学设计实践研究。     

Insights into the Retention Mechanisms on Perfluorohexylpropylsiloxane-Bonded (Fluophase-RP) and Octadecylsiloxane-Bonded (Betasil C18) Stationary Phases Based on the Same Silica Substrate in RP-LC

The solvation parameter model is used to elucidate the retention mechanism on a perfluorohexylpropylsiloxane-bonded (Fluophase RP) and octadecylsiloxane-bonded (Betasil C18) stationary phases based on the same silica substrate with acetonitrile–water and methanol–water mobile phase compositions. Dewetting affects the retention properties of Fluophase RP at mobile phase compositions containing less than 20% (v/v) acetonitrile or 40% (v/v) methanol. It results in a loss of retention due to an unfavorable change in the phase ratio as well as changes in specific intermolecular interactions. Steric repulsion reduces retention of bulky solutes on fully solvated Betasil C18 with methanol–water (but not acetonitrile–water) mobile phase compositions but is not important for Fluophase RP. The retention of weak bases is affected by ion-exchange interactions on Fluophase RP with acetonitrile–water, and to a lesser extent, methanol-water mobile phases but these are weak at best for Betasil C18. The system constants of the solvation parameter model and retention factor scatter plots are used to compare selectivity differences for Fluophase RP, Betasil C18 and a perfluorophenylpropylsiloxane-bonded silica stationary phase Discovery HS F5 for conditions where incomplete solvation, steric repulsion and ion-exchange do not significantly contribute to the retention mechanism. Lower retention on Fluophase RP results from weaker dispersion and/or higher cohesion moderated to different extents by polar interactions since solvated Fluophase RP is a stronger hydrogen-bond acid and more dipolar/polarizable than Betasil C18. Retention factors for acetonitrile–water mobile phases are highly correlated for Fluophase RP and Betasil C18 except for compounds with a large excess molar refraction and weak hydrogen-bonding capability. Selectivity differences are more significant for methanol–water mobile phases. Retention factors on Fluophase RP are strongly correlated with those on Discovery HSF5 for acetonitrile–water mobile phases while methanol–water mobile phases retention on Fluophase RP is a poor predictor of the retention order on Discovery HS F5.     

指向深度学习的高三化学实验复习*——葡萄糖酸锌的制备及纯度测定

针对当前高三化学实验常态复习难以适应“素养为本”的实验试题考查要求的现状,提出了以深度学习指引高三化学实验有效复习的设计思路:精选学习主题、设计学习任务、进行实时评价,并以“七水合硫酸锌的制备、葡萄糖酸锌的制备、葡萄糖酸锌的纯度测定、构建认知模型”为主线,设计了“葡萄糖酸锌的制备及纯度测定”一课,为高三化学实验的深度复习提供了可资借鉴的设计思路和教学案例。     

Chemistry and Biology of Oligovalent β‐(1→2)‐Linked Oligomannosides: New Insights into Carbohydrate‐Based Adjuvants in Immunotherapy

A series of oligovalent carbohydrate assemblies (ranging from mono‐ to pentavalent), derived from three structurally different β‐linked or β‐(1→2)‐linked mannosides, has been chemically synthesized, and the respective compounds have been biologically evaluated in order to investigate their immunostimulatory properties. The Crich methodology for β‐mannosylation was successfully utilized to introduce the β‐linkages, and a click chemistry protocol was utilized to generate the oligovalent derivatives. A convenient protecting group strategy involving the simultaneous use of both p‐methoxybenzyl and benzylidene groups was employed, which allowed a simple and cost‐effective global deprotection step. The immunomodulatory properties of the synthesized multivalent mannosides were evaluated by assessing cytokine production in human white blood cell cultures. The Th2‐type cytokines interleukin‐4 and interleukin‐5 (IL‐4 and IL‐5), the Th1 cytokine interferon‐γ (IFN‐γ), the Treg cytokine IL‐10, and the pro‐inflammatory cytokine tumor necrosis factor (TNF) were included in the screening. A single trivalent acetylated mannobiose derivative was identified as a potent inducer of Treg and Th1 immune response, resulting in strong IL‐10 and moderate IFN‐γ productions dose‐dependently, while inducing no Th2 cytokine response. The immunomodulatory properties of this trivalent mannoside were further studied in vitro in allergen (Bet v)‐stimulated human peripheral blood mononuclear cell cultures of birch pollen allergic subjects. Stimulation with birch pollen induced strong IL‐4 and IL‐5 responses, which could be suppressed by the trivalent acetylated mannobiose derivative. The IL‐10 response was also suppressed, whereas the production of IFN‐γ was strongly enhanced. The results suggest that the identified lead compound has suppressive effects on the Th2‐type allergic inflammatory response and shows potential as a possible lead adjuvant for the specific immunotherapy of allergies.     

地方性本科院校应用化学专业创新创业人才培养模型建构——基于扎根理论的多个案研究

从“高校教师”和“创业成功者”的视角出发,对多个对象访谈获得原始材料。采用扎根理论研究方法进行分析,得出他们对于应用化学专业创新创业人才应具备的需要和人才培养方式的建议。研究提出船式人才培养模型,即以教学反思为推动力,创新、创业为发展方向,实行“知识＋方法＋通识类”课程体系。     

初中化学“分子和原子”的教学逻辑——基于2011-2018年的文献分析

以2011-2018年19篇有关初中化学“分子和原子”的教学研究文献为研究对象,基于教学观念与策略分析归纳出2种主要的教学逻辑:“证据推理型”和“模型认知型”。从“初步建立微粒观”“发展微粒观”“初步形成微粒观”等3个维度对2种教学逻辑进行归纳和评析,结合教学实践提出了一个新的“模型认知型”的教学逻辑。     

新课标“硅及其化合物”定位的嬗变与教学重构——基于HPS模式改进的教学设计

《普通高中化学课程标准(2017年版) 》中明确提出化学学科核心素养,完成了三维目标的迭代。硅及其化合物相关内容发生了较大变化,虽然知识层面要求降低,但是作为认识对象和感性认识素材的要求却有所提高。这种定位的嬗变,势必要求进行主题教学的重构。结合化学发展史以及改进的HPS教学模式,进行了初步的教学实践探索。     

基于模型建构的论证教学在化学概念学习中的应用*——以“原电池”概念学习为例

基于呈现批判反思提炼(PCRR)模式,提出了假设呈现批判反思提炼(HPCRR)模式,并以“原电池”概念学习为例,进行教学设计与教学实施。研究对象为广东省佛山市某校高二年级2个平行班的92名学生,其中实验组和对照组均为46人。从概念理解和学生对该教学模式的态度等2个方面调查了实施效果。结果显示,教学干预后,实验组学生的概念理解明显优于对照组,表明该教学模式能有效促进学生的概念理解,实现概念转变。实验组学生对该教学模式的接受度较高,持积极态度。