“线上线下”结合的化学实验教学模式改革

在化学实验模块化教学改革中,存在实验课时少,实验室周转紧张,学生不能系统学习化学实验课程等问题。针对此现状,设计了“虚拟仿真实验”镶嵌在实验室实验教学中,组成了“线上线下”相结合的实验教学模式。基础知识采用线上自学,然后通过实验训练加以巩固;模块实验观看视频后进行操作训练;综合实验学生通过线上自学后申请进入实验室操作,完成整个实验教学过程。该实验教学模式不仅解决了现存问题,而且使学生有充分的独立思考空间,强烈的参与实验意识和完整实验操作技巧的训练。     

“翻转+分段式”有机化学实验教学设计及实践研究

以FeCl3·6H2O催化合成乙酸乙酯为教学内容,采用“翻转+分段式”混合教学方法对整个实验过程进行了改革探索。通过教师准备学习资源,学生自主学习,课堂分段讲解,互动交流以及跟踪评价等,探讨了大学有机化学实验实施“翻转+分段式”混合教学方法的有效途径。实践结果表明:混合教学模式能够显著促进学生对实验内容的理解和掌握,明显增加学生自主操作的时间,还能有效降低实验过程中的安全隐患。     

化学理论课堂教学结构模型构建初探——基于课堂教学视频案例分析的研究

模块化结构的我国中学化学课程标准和新教材,需要寻求教学规律与课堂教学的组成、结构模型来支持课程目标的实施,将课堂教学视频案例研究作为新的研究方法,成为关注的热点。研究采用了课堂教学视频案例采集和教学结构维度的分析方法,选取了6个优秀化学理论课堂教学视频案例,应用“Videograph”视频分析软件从学生学习行为、教师教学行为和师生互动3个主要维度对案例进行分析、解读与比较。对教师课堂导入、新内容讲授（区分为教师启发式讲授和教师直接知识讲授）、师生课堂探究（区分为教师演示实验探究和学生自主探究）、师生课堂探究讨论（区分为学生小组探究讨论、师生互动问答讨论）、课堂练习、课堂小结、其他活动等7个部分进行了编码分析和特征解读。初步提出了化学理论课堂教学结构的时间模型。     

“创客教育+SPOC”翻转实验教学模式研究——以磷酸氢二钠产品中微量杂质铁的测定为例

探索了一种“创客教育+SPOC”翻转实验教学模式,并具体应用于磷酸氢二钠产品中微量杂质铁的测定。充分融合线上、线下教学资源,依据翻转课堂教学流程研究了课前任务下达、视频预习、在线检测及课堂活动的前期预习问题翻转、中期实验内容协作以及后期实验过程反思等翻转方案,拓展了课后学生自主设计科研创新方案。既培养了学生的基本技能,又激发了学生实验的热情,同时提升了学生的科研素养。     

“有机化学”开放式精品示范课程建设与实践

以中南大学化学类专业本科生的重要基础课程“有机化学”为例,探讨开放式精品示范课程改革。为适应现今信息化的高速发展和大学生特点,从创新课程教学着眼点、创新课程教学方法、课程教学效果等方面,阐述了开放式精品示范课程建设与实践的思路。基于网络的自主学习、课堂的互动交流、实验实践的拓展提升、科学合理的多元化课程考核,有效地提高了学生的学习兴趣与积极性,得到了良好的教学效果。     

“工程化学”SPOC的建设与教学效果

河西学院“工程化学”教师组建设了面向河西学院土木工程专业,1.5学分的“工程化学”SPOC(小规模限制性在线课程),录制了44个视频知识点,讲解了物质的化学组成与聚集状态、化学反应与能源、水溶液中的化学、非化工类生产中的化学知识,设置了11次作业强化学生学习效果。该课程通过超星学习通平台上线并完成了教学任务。通过3个专业班级的教学实践,发现线上视频学习、课后作业、线上教师答疑相结合的教学模式,不仅发挥了学生为主体的学习作用,还实现了良好的教学效果。     

基于SPOC和慕课堂的物理化学实验混合式教学改革实践

为了提高物理化学实验的教学效果,拍摄制作了物理化学实验原理和操作视频,并基于爱课程(中国大学MOOC)平台的SPOC和慕课堂,开展了线上线下混合式教学。实践证明,混合式教学提高了学生的积极性,提升了学习效果,增加了师生之间的互动,可以进一步培养学生的综合能力,激发学生的创新思维。     

新型粉末涂料固化剂呔哔克的合成工艺

以环氧氯丙烷、氰尿酸、片碱为原料生产(三环氧丙基)异氰尿酸酯(即呔哔克),生产工艺采用两步法合成:环氧氯丙烷、氰尿酸在催化剂作用下发生开环反应,在反应中加入片碱,进行闭环反应,生成(三环氧丙基)异氰尿酸酯,再经抽滤、蒸馏、精制、造粒后得到呔哔克产品。     

校本课程开发:从“化学传奇”到“化学阅读”

校本课程“化学传奇”主要是引导学生阅读化学史文章。校本课程从“化学传奇”升级到“化学阅读”,化学阅读的内容拓展了,阅读形式升级了:由文章阅读升级为视频观看和整本书阅读,阅读的时间由校本课程的课内阅读延伸到课外阅读,阅读时段由校本课程季扩展为高中全学段。学生的阅读活动,也由教师规定阅读内容升级到学生在推荐书目内自主选择性阅读和个性化阅读。     

初中化学“铁元素专题复习”的项目式教学——探索蒸汽眼罩的奥秘

转变初中化学复习课的教学方式,以真实情境为载体,确定“探索蒸汽眼罩的奥秘”为项目主题,引导初中学生深入开展铁元素的专题复习。详细阐述了教师对该部分内容教学的课前分析,如何确立、规划和实施项目。学生通过完成“设计实验方案证明铁的存在”“探究活性炭和氯化钠对铁生锈的影响”等2个任务,提升了学科兴趣,对铁的性质进行了系统性再造。通过手持技术监测氧浓度和温度变化探究眼罩成分的作用,学生的科学探究能力从定性过渡到定量,实现了科学探究素养的深化与进阶;通过观看科普视频了解前沿科学,拓宽了学生的生涯认知,涵养了科学精神。     

Determination of the enthalpy of fusion of K<Subscript>3</Subscript>TaO<Subscript>2</Subscript>F<Subscript>4</Subscript> and KTaF<Subscript>6</Subscript>

Areas of fusion and crystallization peaks of K₃TaO₂F₄ and KTaF₆ were measured using the DSC mode of a high-temperature calorimeter (SETARAM 1800 K). On the basis of these quantities, considering the temperature dependence of the calorimeter sensitivity, values of the fusion enthalpy of K₃TaO₂F₄ at the fusion temperature of 1181 K of (43 ± 4) kJ mol⁻¹ and of KTaF₆ at the fusion temperature of 760 K of (8 ± 1) kJ mol⁻¹ were determined.     

2,4‐Di­nitro­phenyl­hydrazones of 2,4‐di­hydroxy­benz­aldehyde, 2,4‐di­hydroxy­aceto­phenone and 2,4‐di­hydroxy­benzo­phenone

In 2,4‐di­hydroxy­benz­aldehyde 2,4‐di­nitro­phenyl­hydrazone N,N‐di­methyl­form­amide solvate {or 4‐[(2,4‐di­nitro­phenyl)­hydrazono­methyl]­benzene‐1,3‐diol N,N‐di­methyl­form­amide solvate}, C₁₃H₁₀N₄O₆·C₃H₇NO, (X), 2,4‐di­hydroxy­aceto­phenone 2,4‐di­nitro­phenyl­hydrazone N,N‐di­methyl­form­am­ide solvate (or 4‐{1‐[(2,4‐di­nitro­phenyl)hydrazono]ethyl}benzene‐1,3‐diol N,N‐di­methyl­form­amide solvate), C₁₄H₁₂N₄O₆·C₃H₇NO, (XI), and 2,4‐di­hydroxy­benzo­phenone 2,4‐di­nitro­phenyl­hydrazone N,N‐di­methyl­acet­amide solvate (or 4‐­{[(2,4‐di­nitro­phenyl)hydrazono]phenyl­methyl}benzene‐1,3‐diol N,N‐di­methyl­acet­amide solvate), C₁₉H₁₄N₄O₆·C₄H₉NO, (XII), the molecules all lack a center of symmetry, crystallize in centrosymmetric space groups and have been observed to exhibit non‐linear optical activity. In each case, the hydrazone skeleton is fairly planar, facilitated by the presence of two intramolecular hydrogen bonds and some partial N—N double‐bond character. Each molecule is hydrogen bonded to one solvent mol­ecule.     

Influence of composition on corroding process of Na<Subscript>2</Subscript>O-K<Subscript>2</Subscript>O-CaO-ZrO<Subscript>2</Subscript>-SiO<Subscript>2</Subscript> glasses

The corroding process of six glasses of the Na₂O-K₂O-CaO-ZrO₂-SiO₂ system with ZrO₂content 0–2.13 mass % by water was observed during static tests at 121°C and pressure of 0.25 MPa in steam sterilizer. Significant increase of Na⁺ and K⁺ content in leachates was observed after the addition of ZrO₂ into glass. Further increase of the content of ZrO₂ in glasses slowed down the rate of Na⁺ and K⁺ leaching. The leaching process of SiO₂ as well as Na⁺, K⁺, and Ca²⁺ ions was evaluated on the basis of comparison with model leaching processes. Variation of the concentrations of Na⁺, K⁺, Ca²⁺, and SiO₂ in leachates with time was described by empirical equation. Observed changes in the initial leaching rates of Na⁺, K⁺, Ca²⁺, and SiO₂ can be ascribed to the content of ZrO₂ in glasses. The presence of ZrO₂ in glasses reduced the overall rate of glass dissolution.     

Ionic conduction of a high-temperature modification of Lu<Subscript>2</Subscript>Ti<Subscript>2</Subscript>O<Subscript>7</Subscript>

A nanoceramic product of the composition Lu₂Ti₂O₇ is synthesized by a coprecipitation method with a subsequent sublimation drying and an annealing at 650–1650°C. The conduction of Lu₂Ti₂O₇ synthesized at 1650°C is ionic (10^–3 S cm^–1 at 800°C). Thus, a new material with a high ionic conduction has been discovered. The ordering in Lu₂Ti₂O₇ is studied by methods of RFA, RSA, IK spectroscopy, electron microscopy, and impedance spectroscopy. The existence of a low-temperature phase transition fluorite-pyrochlore at 800°C and a high-temperature conversion order-disorder at 1650°C are established.Translated from Elektrokhimiya, Vol. 41, No. 3, 2005, pp. 298–303.Original Russian Text Copyright © 2005 by Shlyakhtina, Ukshe, Shcherbakova.     

Thermoanalytical study of the synthesis of Na<Subscript>0.5</Subscript>Bi<Subscript>0.5</Subscript>TiO<Subscript>3</Subscript> ferroelectric

The study presents results of examination on Na_0.5Bi_0.5TiO₃ (NBT) ferroelectric synthesis through intermediate binary compound Bi₄Ti₃O₁₂ (BIT). The first stage of the study related to obtaining BIT from oxide precursors, i.e. Bi₂O₃ and TiO₂. The second stage included obtaining NBT from Bi₄Ti₃O₁₂, Na₂CO₃ and TiO₂. Two polymorphic modifications of TiO₂ (anatase, rutile) and diversified initial homogenization of raw material batches were applied during examination.     

Physicochemical foundations of synthesis of new ferromagnets from chalcopyrites A<Superscript>II</Superscript>B<Superscript>IV</Superscript>C<Stack><Subscript>2</Subscript><Superscript>V</Superscript></Stack>

The results of studying phase equilibria of ternary A^IIB^IVC^V systems have been reported. Physicochemical foundations have been developed for the synthesis of new ferromagnets with Curie temperatures above room temperature structurally compatible with basic semiconducting materials. Methods of synthesis and physicochemical properties of manganese-doped A^IIB^IVC₂^V ferromagnets have been described. The results of theoretical simulation of magnetic properties have been considered and basic approaches to the explanation of the emergence of ferromagnetism in A^IIB^IVC₂^V doped with 3d metals have been surveyed. The most promising ways to produce and study dilute magnetic semiconductors as spintronics materials have been presented.     

Di­methyl­phenyl­sulfonium tri­fluoro­methane­sulfonate and methyl­di­phenyl­sulfonium tri­fluoro­methane­sulfonate

The bonding geometry of sulfur in the cations of the title compounds, C₈H₁₁S⁺·CF₃SO₃^? and C₁₃H₁₃S⁺·CF₃SO₃^?, respectively, is similar and is independent of the ratio of the Me/Ph substituents. As expected, in both cations, the S—Ph bonds are somewhat shorter than the S—Me bonds. In both crystal structures, the interaction between cations and anions is similar.     

Thermal synthesis of the CeO<Subscript>2</Subscript>-PrO<Subscript>2</Subscript>-Nd<Subscript>2</Subscript>O<Subscript>3</Subscript>pigments

Summary The synthesis of new compounds based on the CeO₂-PrO₂-Nd₂O₃system, which can be used as pigments for colouring of ceramic glazes, is investigated in our laboratory. The optimum conditions for the syntheses of these compounds have been estimated. The methods of thermal analysis provided first information about the temperature region of the formation of the pigments investigated. The synthesis of these compounds was followed by thermal analysis using STA 449/C Jupiter (Netzsch, Germany).     

“蒸馏酒”还是“发酵酒”——对《科学史导论》中“spirits” 和“distillation”的再思考

科学史奠基者乔治·萨顿在《科学史导论》第二卷的第一部分对我国宋代酿酒著作《北山酒经》予以了简要描述,出现了“spirits”“distillation”等字样;而《北山酒经》被众多学者认为其描述对象是发酵酒(黄酒)。本文从东西方蒸馏技术和相关著作的文本分析对《科学史导论》中提及的蒸馏技术和蒸馏酒存在的可能性提出了质疑。     

Projection of the liquidus surface of the Sb<Subscript>2</Subscript>Te<Subscript>3</Subscript>-Gd<Subscript>2</Subscript>Te<Subscript>3</Subscript>-Bi<Subscript>2</Subscript>Te<Subscript>3</Subscript> system

Phase equilibria in the Sb₂Te₃-Gd₂Te₃-Bi₂Te₃ ternary system have been studied using differential thermal analysis, namely, X-ray powder diffraction, microstructure examination, thermodynamic analysis, and microhardness and alloy density measurements. Phase diagrams of some polythermal joins and liquidus surface have been constructed. The regions of primary crystallization of phases and the coordinates of all invariant and univariant equilibria in the system under investigation have been established.