How deeply are core electrons perturbed when valence electrons are spin polarized? The case study of transition metal compounds

The ferromagnetic and antiferromagnetic wave functions of the KMnF₃ perovskite have been evaluated quantum-mechanically by using an all electron approach and, for comparison, pseudopotentials on the transition metal and the fluorine ions. It is shown that the different number of α and β electrons in the d shell of Mn perturbs the inner shells, with shifts between the α and β eigenvalues that can be as large as 6 eV for the 3s level, and is far from negligible also for the 2s and 2p states. The valence electrons of F are polarized by the majority spin electrons of Mn, and in turn, spin polarize their 1s electrons. When a pseudopotential is used, such a spin polarization of the core functions of Mn and F can obviously not take place. The importance of such a spin polarization can be appreciated by comparing (i) the spin density at the Mn and F nuclear position, and then the Fermi contact constant, a crucial quantity for the hyperfine coupling, and (ii) the ferromagnetic–antiferromagnetic energy difference, when obtained with an all electron or a pseudopotential scheme, and exploring how the latter varies with pressure. This difference is as large as 50% of the all electron datum, and is mainly due to the rigid treatment of the F ion core. The effect of five different functionals on the core spin polarization is documented.     

基于宏微辨析核心素养分析高中《化学1(必修)》教材*

教材分析是连接教材和课程的桥梁,基于宏观辨识和微观探析核心素养,比较分析了2004年版和2019年版高中《化学1(必修)》教材的特点。通过运用“三序结合”原则,从静态视角对比教材栏目设置、内容组织形式、核心素养呈现方式、学生认知水平以及作业布置形式等5个维度要素在宏微辨析核心素养领域的建构。分析结果显示,2019年版《化学1(必修)》教材在以上要素方面均围绕宏微辨析核心素养,呈现不同水平阶梯型设置。建议在“宏微符”概念形成的过程中增设更为细致的过渡内容,以及更为详尽的与教材配套的辅助内容,便于教材的二次开发。     

化学STSE教学:指向关键能力的实践活动*——以手工醋与勾兑醋的区分实践活动为例

近年来STSE教育即以科学、技术、社会和环境4者的协调性为基础的综合实践活动教学理念在历年的高考试题中的试题量和分值所占比例逐步上升,它是提升学生必备品格、培养学生关键能力、帮助学生针对公共生活中利与弊皆有的两难问题做出正确选择的有效抓手,是发展学生化学学科核心素养不可或缺的重要组成部分。基于STSE 的初中学生化学教学综合实践活动学习,为初中学生进入高中阶段,快速发展化学学科核心素养打下良好的基础。     

高中化学必修课程“变化观念与平衡思想”学科核心素养的系统构成研究

“变化观念与平衡思想”学科核心素养的系统构成对开展“素养导向”的教学与评价具有重要意义。通过课标分析,基于学科能力模型明确了高中必修学段“变化观念与平衡思想”核心素养的核心知识与活动经验、认识方式、研究对象及问题情境、学科能力活动及其表现等4个维度的具体内涵,系统建构了高中化学必修课程“变化观念与平衡思想”学科核心素养模型。     

化学学科核心素养在高中教材习题中的表现—以人教版教材为例

教材习题是落实新课标倡导的基于化学学科核心素养进行评价的重要载体。以化学学科核心素养的水平划分和学业质量水平为依据,分析人教版高中必修化学教材课后习题考查的核心素养及其水平。结果表明,2007年版和2019年版教材均注重全面考查核心素养和对基础性的考查,突出考查宏观辨识与微观探析素养,突出化学本质;但2019年版教材习题在数量上有所减少,加强了科学思维和科学实践的考查,合理拓展了核心素养考查的广度和深度。最后,依据习题特征获得相应的教学启示,以促进学生核心素养的发展。     

培养高阶思维和核心素养的高考有效复习——以“从海洋到餐桌上的碘”为例

选择学生比较熟悉的碘元素,结合海带提碘和精碘制碘酸钾工业生产情境展开复习教学,综合利用元素性质、反应原理探索含碘物质之间相互转化的最优路径,并对转化过程中的某些现象进行实验探究。通过设置有梯度的问题串引导学生在思考、分析、探究、归纳中完成综合型学习任务,实现知识规律化和体系化整合以及高阶思维培养。     

Synthesis and Biochemical Evaluation of Warhead-Decorated Psoralens as (Immuno)Proteasome Inhibitors

The immunoproteasome is a multicatalytic protease that is predominantly expressed in cells of hematopoietic origin. Its elevated expression has been associated with autoimmune diseases, various types of cancer, and inflammatory diseases. Selective inhibition of its catalytic activities is therefore a viable approach for the treatment of these diseases. However, the development of immunoproteasome-selective inhibitors with non-peptidic scaffolds remains a challenging task. We previously reported 7H-furo[3,2-g]chromen-7-one (psoralen)-based compounds with an oxathiazolone warhead as selective inhibitors of the chymotrypsin-like (β5i) subunit of immunoproteasome. Here, we describe the influence of the electrophilic warhead variations at position 3 of the psoralen core on the inhibitory potencies. Despite mapping the chemical space with different warheads, all compounds showed decreased inhibition of the β5i subunit of immunoproteasome in comparison to the parent oxathiazolone-based compound. Although suboptimal, these results provide crucial information about structure–activity relationships that will serve as guidance for the further design of (immuno)proteasome inhibitors.     

Computational Study of the Electron Spectra of Vapor-Phase Indole and Four Azaindoles

After geometry optimization, the electron spectra of indole and four azaindoles are calculated by density functional theory. Available experimental photoemission and excitation data for indole and 7-azaindole are used to compare with the theoretical values. The results for the other azaindoles are presented as predictions to help the interpretation of experimental spectra when they become available.     

多金核二氧化铈空心球用于硝基苯酚催化加氢

催化剂的微观结构在催化还原反应、有机物氧化反应及有机物转化反应中起着关键作用。本文利用无模板方法合成了多金核中空二氧化铈微球催化剂。将制备好的二氧化铈中空微球浸渍到一定浓度的氯金酸溶液中,然后多次洗涤除去表面吸附的氯金酸离子,最后通过硼氢化钠还原制成中空氧化铈微球包覆的多金核的核壳结构催化剂。将该核壳结构材料用于硝基苯酚加氢反应与金纳米粒子及氧化铈微球相比,多金核中空二氧化铈核壳结构表现出优越的活性和稳定性。通过这种浸渍洗涤再还原的简单方法合成的多金核二氧化铈催化剂有望应用于生物医药和能源环境等领域。     

Synthesis and self-assembly behavior of 2,5-diphenylethynyl thiophene based bolaamphiphiles

Synthesized 2,5-diphenylethynyl thiophene based bent bolaamphiphiles can self-organize into square honeycomb LC phases with p4mm symmetries in the presence of water. UV and PL measurements indicate fl uorescent properties making them potential candidates for application in fl uorescence sensor devices