Structural stability and electrical properties of AIB2-type MnB2 under high pressureStructural stability and electrical properties of AIB2-type MnB2 under high pressureStructural stability and electrical properties of AIB2-type MnB2 under high pressureStructural stability and electrical properties of AIB2-type MnB2 under high pressure

The structural stability and electrical properties of A1B2-type MnB2 were studied based on high pressure angle- dispersive x-ray diffraction, in situ electrical resistivity measured in a diamond anvil cell （DAC） and first-principles calcu- lations under high pressure. The x-ray diffraction results show that the structure of A1B2-type MnB2 remains stable up to 42.6 GPa. From the equation of state of MnB2, we obtained a bulk modulus value of 169.9~3.7 GPa with a fixed pressure derivative of 4, which indicates that A1B2-type MnB2 is a hard and incompressible material. The electrical resistance un- dergoes a transition at about 19.3 GPa, which can be explained by a transition of manganese 3d electrons from localization to delocalization under high pressure.     

绿色磷光四配位氮杂环卡宾铜(Ⅰ)配合物的合成及发光性质

为了制备发光性能优良的新型四配位氮杂环卡宾铜髣配合物,以咪唑、苯并咪唑、2-溴-5-氟-6-甲基吡啶和溴化苄为初始原料,反应生成氮杂环卡宾配体(Ph-Im-flumePy)PF_6和(Ph-BenIm-mePy)PF_6,随后卡宾配体与Cu粉及配体双(2-二苯基膦)苯醚(POP)反应,制备出2个四配位类型的氮杂环卡宾铜髣配合物[Cu(Ph-Im-flumePy)(POP)]PF_6(P1)和[Cu(Ph-BenIm-flumePy)(POP)]PF_6(P2)。通过核磁、质谱技术对产物结构进行了表征。系统研究了配合物的紫外-可见吸收光谱、发射光谱以及发光寿命等光学特性。结果表明,配合物P1和P2的最低吸收峰分别位于325和335 nm处。粉末状态下,配合物P1在514 nm处有较强的绿光发射,量子发光效率为82.6%,激发态寿命为56μs;而配合物P2的波长在516 nm处,量子发光效率为49.2%,激发态寿命为50.6μs。在PMMA(10%,w/w)膜片中,配合物P1的发射波长蓝移至505 nm处,激发态寿命为40.7μs,量子发光效率为38.0%;而配合物P2的发射波长位于508 nm处,激发态寿命为61μs,量子发光效率为44.2%。     

水流动强化天然气水合物降压分解研究

降压法被认为是最经济可行的天然气水合物开采方法,但开采后期驱动力不足、甚至产生水合物的二次生成,因此其应用受到限制。本文将降压法与水流动结合提升水合物分解驱动力,研究不同降压模式和水流动对天然气水合物分解特性的影响。发现当降压结合水流动时,压降为水合物分解提供初始驱动力,且压降越大水合物分解驱动力越大。同时水流动能够加快传热传质过程,为水合物分解提供额外的驱动力。在快速降压结合水流动模式中,较高背压下水流动为水合物分解提供主要的驱动力;在梯度降压结合水流动模式中,降压和水流动共同为水合物提供分解驱动力,对水合物分解的促进作用更加显著。     

A green synthesis of a simple chemosensor that could instantly detect cyanide with high selectivity in aqueous solution

A novel and simple cyanide chemosensor 2-(naphthalen-1-ylmethylene)malononitrile(L) was designed and synthesized via a green chemistry method in water without using any catalyst.The chemosensor showed an excellent sensitivity and selectivity for CN in aqueous solution.The detection limit could be as low as 1.6×10~7 moI/L(0.16μmol/L),which is far lower than the WHO guideline of 1.9μmol/L cyanide for drink water.     

Photoreversible dendritic organogel

A photoreversible organogel made from dendrons was reported.     

云教学在化学师范生数字化实验课中的应用研究*

结合本校化学教学论实验的教学现状,融合云教学及翻转课堂理念对教学进行重构,设计并实施以“蓝墨云班课”云平台为师生互动桥梁的翻转课堂云教学。以中学化学数字化实验教学为例,让化学师范生以“学习者”和“未来教师”的双重角色体验翻转课堂云教学的学习过程,并利用SERVQUAL模型评价法对云教学进行数据分析、反馈完善。通过进一步问卷分析,了解到学生不仅熟练地掌握了所学知识内容,而且对翻转课堂模式与实施细节有了更为深刻的理解,最后对翻转课堂云教学及师范生教学提出了几点建议。     

Quantum Discord Behaviors in Two Qubits Spin Squeezing Model with Intrinsic Decoherence

By taking into account the intrinsic decoherence and the external magnetic field, quantum discord(QD) behaviors in two-qubit spin squeezing model are investigated in detail. It is found that the magnitude of quantum discord is strongly dependent on the initial states, the squeezing interaction μ, the magnetic field Ω and the purity r of initial states. With t → ∞, one can obtain the steady quantum discord (SQD) value, the environmental decoherence cannot entirely destroy the quantum correlation. Based on the analysis of the SQD, the conditions about the existence of SQD are obtained with different initial states. Varying the parameters μ, Ω and r not only can weaken the effects of decoherence but also can improve the magnitude of QD and SQD. The effects of the parameters μ and Ω on the QD and SQD display so different and complicated features that one cannot get an uniform law about them, while the values of QD and SQD are improved with increasing r. Properly tuning the parameters μ, Ω and r, one can obtain a larger value of QD or SQD.     

紫外激光和压力共同作用下C60-peapod的聚合相变研究

采用气相扩散方法将C60分子填充到单壁碳纳米管(SWNTs)中,制备出高填充比率的豆荚形纳米材料C60@SWNT,又称为peapod.用金刚石对顶砧(DAC)装置获得高压,在高压下同时利用紫外激光处理样品,通过激光和压力的共同作用研究了C60分子在碳管内的聚合相变.在21.5 Gpa高压下,同时紫外激光(325 nm)照射30 min后,拉曼光谱表明C60分子在碳管内发生了聚合,形成一维链状O相聚合结构,且该相变是不可逆的.紫外激光的引入使样品发生O相聚合所需的压力值低于仅由压力诱导的聚合压力.     

Silver Single Atom in Carbon Nitride Catalyst for Highly Efficient Photocatalytic Hydrogen Evolution

Single atom catalysts (SACs) with the maximized metal atom efficiency have sparked great attention. However, it is challenging to obtain SACs with high metal loading, high catalytic activity, and good stability. Herein, we demonstrate a new strategy to develop a highly active and stable Ag single atom in carbon nitride (Ag-N₂C₂/CN) catalyst with a unique coordination. The Ag atomic dispersion and Ag-N₂C₂ configuration have been identified by aberration-correction high-angle-annular-dark-field scanning transmission electron microscopy (AC-HAADF-STEM) and extended X-ray absorption. Experiments and DFT calculations further verify that Ag-N₂C₂ can reduce the H₂ evolution barrier, expand the light absorption range, and improve the charge transfer of CN. As a result, the Ag-N₂C₂/CN catalyst exhibits much better H₂ evolution activity than the N-coordinated Ag single atom in CN (Ag-N₄/CN), and is even superior to the Pt nanoparticle-loaded CN (Pt_NP/CN). This work provides a new idea for the design and synthesis of SACs with novel configurations and excellent catalytic activity and durability.     

静电场对强激光场非序列双电子电离的影响

利用半经典重碰模型计算并研究了He原子在强激光场与静电场的混合场下的非序列双电子电离过程. 由于静电场破坏了激光场电场的反演对称性,在平行于激光场偏振方向的He²⁺离子动量分布不再具有对称双峰结构. 由于超短脉冲具有相似的非对称性,研究静电场对原子在强场中非序列电离的影响,有助于分析超短脉冲非序列电离的过程,进一步了解非序列双电子电离的机理. 关键词： 非序列双电离 静电场 重碰 非对称性场