化学教育硕士研究生的科学本质观研究*——基于对科普微视频的分析

以构建的科学本质要素框架作为分析工具,研究学生经科普微视频分析所呈现的科学本质观。结果表明,学生无法全面、深入分析视频呈现的科学本质,反映了局限的科学本质观,而经过讨论与汇报能在一定程度上提升其科学本质观。据此,为化学教育硕士研究生的培养工作提出3点建议,即将科普微视频作为科学本质教育的素材,促进学生形成完整且深刻的科学本质观,发展学生准确抽提课程资源中的科学本质的能力。     

Linearization of Poisson groupoids

Motivated by a search for Lie group structures on groups of Poisson diffeomorphisms, we investigate linearizability of Poisson structures of Poisson groupoids around the unit section. After extending the Lagrangian neighbourhood theorem to the setting of cosymplectic Lie algebroids, we establish that dual integrations of triangular bialgebroids are always linearizable. Additionally, we show that the (non-dual) integration of a triangular Lie bialgebroid is linearizable whenever the $r$-matrix is of so-called cosymplectic type. The proof relies on the integration of a triangular Lie bialgebroid to a symplectic LA-groupoid, and in the process we define interesting new examples of double Lie algebroids and LA-groupoids. We also show that the product Poisson groupoid can only be linearizable when the Poisson structure on the unit space is regular.     

体积应变对立方钛酸铅电子结构和光学性质的影响

本文利用第一性原理方法计算并分析了体积应变(-11%~11%)对立方顺电相PbTiO₃的结构、稳定性、电子结构和光学性质的影响。研究发现体积应变后PbTiO₃形成焓增大,稳定性下降,其中压应变对其稳定性的影响比拉应变大。当受到拉伸应变时,立方PbTiO₃由直接带隙半导体变为间接带隙半导体,且带隙随应变增大呈先增大后降低的趋势。在发生压应变时,从复介电函数、复折射率及吸收系数的分析结果可知,在自然光照下PbTiO₃的光吸收能力仅在个别波段有所增大,但总体呈减弱趋势,当产生拉伸应变时,介电峰、吸收峰红移,表明PbTiO₃在可见光范围内光吸收能力增强,并且当应变增大到11%时,PbTiO₃的吸收能力远高于本征立方相。     

从化学视角剖析烫发、染发原理及顺序*

从头发的结构和组成出发分析头发形状和颜色改变的可能性,剖析烫发、染发的化学原理,阐释先烫发后染发的本质原因,从化学视角辨证地看待烫发、染发的利弊。     

Characterization and gas adsorption of a novel three‐dimensional metal–organic framework (MOF) generated from a new polydentate fluorene‐bridged ligand

A polydentate ligand bridged by a fluorene group, namely 9,9‐bis(2‐hydroxyethyl)‐2,7‐bis(pyridin‐4‐yl)fluorene (L), has been prepared under solvothermal conditions in acetonitrile. Crystals of the three‐dimensional metal–organic framework (MOF) poly[[[μ₃‐9,9‐bis(2‐hydroxyethyl)‐2,7‐bis(pyridin‐4‐yl)fluorene‐κ³N:N′:O]bis(methanol‐κO)(μ‐sulfato‐κ²O:O′)nickel(II)] methanol disolvate], {[Ni(SO₄)(C₂₇H₂₄N₂O₂)(CH₃OH)]·2CH₃OH}_n, (I), were obtained by the solvothermal reaction of L and NiSO₄ in methanol. The ligand L forms a two‐dimensional network in the crystallographic bc plane via two groups of O—H…N hydrogen bonds and neighbouring two‐dimensional planes are completely parallel and stack to form a three‐dimensional structure. In (I), the Ni^II ions are linked by sulfate ions through Ni—O bonds to form inorganic chains and these Ni‐containing chains are linked into a three‐dimensional framework via Ni—O and Ni—N bonds involving the polydentate ligand L. With one of the hydroxy groups of L coordinating to the Ni^II atom, the torsion angle of the hydroxyethyl group changes from that of the uncoordinated molecule. In addition, the adsorption properties of (I) with carbon dioxide were investigated.     

Fixed Points,Continuous Selections,and Existence of Solution of Optimization-Related Problems

We propose a definition of a generalized type of Knaster–Kuratowski–Mazurkiewicz (KKM) mappings, called a weak T-KKM mapping, and a corresponding weak KKM property. A new extension of the Fan–Glicksberg fixed-point theorem is established. Sufficient conditions for the existence of a continuous selection, a fixed point of a composition, and a coincidence point are also provided. Then, we use the obtained results to study the existence of solutions to various optimization-related problems. Discussions and detailed examples are included as well to compare our results with existing ones and to explain their advantages in many situations.     

X-ray diffraction study of mesogenic 4-methoxyphenyl-4′-n-nonyloxybenzoate

4-methoxyphenyl-4′-n-nonyloxybenzoate have been investigated by single crystal X-ray structural analysis. Crystal packing of the compounds does not represent a precursor of the mesophse although the typical for liquid crystal compounds separation of crystal packing on aromatic and aliphatic areas is observed here. Possible reason for monotropic properties are discussed.     

Electron Transport in Configurational Model of Ferromagnetic Fulleride with Triple Orbital Degeneracy

Abstract

Phenomenon of ferromagnetic ordering was for a long time associated exclusively with transition metal and rare-earth compounds. Nowadays this view is challenged by growing evidence that in molecular carbon-based systems the ferromagnetic alignment of spins can be observed as well. We have developed a microscopical model of a fulleride electronic subsystem taking into account triple orbital degeneracy of energy states within the configurational-operator approach. Using the Green function method the energy spectrum of the model has been calculated. Conditions for the ferromagnetic state stabilization have been determined. Static electrical conductivity and effective masses of current carriers in the system with orbitally degenerated energy band have been obtained. In the ground state and for low temperatures at different forms of unperturbed density of electronic states the concentration dependences of transport characteristics for less-then-half-filled lower quasiparticle subband have been calculated.