Asymmetric Synthesis of Contact Sex Pheromone of Tetropium fuscum and Its Enantiomer

Tetropium fuscum is a harmful forest pest and attacks spruces. The contact sex pheromone of this pest, (S)-11-methyl-heptacosane, and its enantiomer were synthesized via Evans’ chiral auxiliaries. The key steps of this approach included acylation of carboxylic acid, diastereoselective methylation of oxazolidinone amide, and Wittig coupling of the aldehyde with chiral phosphonium salt. The synthetic pheromones would have potential utility in the control of this pest.     

Photophysical and Primary Self-Referencing Thermometric Properties of Europium Hydrogen-Bonded Triazine Frameworks

Lanthanide hydrogen-bonded organic frameworks (LnHOFs) are recently emerging as a novel versatile class of multicomponent luminescent materials with promising potential applications in optics and photonics. Trivalent europium (Eu³⁺) incorporated polymeric hydrogen-bonded triazine frameworks (PHTF:Eu) have been successfully obtained via a facile and low-cost thermal pyrolysis route. The PHTF:Eu material shows a porous frame structure principally composed of isocyanuric acid and ammelide as a minor constituent. Intense red luminescence with high colour-purity from Eu³⁺ is obtained by exciting over a broad absorption band peaked at 300 nm either at room or low temperature. The triazine-based host works as excellent optical antenna towards Eu³⁺, yielding ~42% sensitization efficiency (η_sens) and an intrinsic quantum yield of Eu³⁺ emission (Φ_Eu) as high as ~46%. Temperature-dependent emission studies show that PHTF:Eu displays relatively high optical stability at elevated temperatures in comparison to traditional inorganic phosphors. The retrieved activation energy of 89 meV indicates that thermal quenching mechanisms are attributed to the intrinsic energy level structure of the metal-triazine assembly, possibly via a thermally activated back transfer to ligand triplet or CT states. Finally, by using an innovative approach based on excitation spectra, we demonstrate that PHTF:Eu can work as a universal primary self-referencing thermometer based on a single-emitting center with excellent relative sensitivity in the cryogenic temperature range.     

激光沉积修复BT20合金的显微组织和力学性能

针对BT20钛合金锻件当量孔损伤进行激光沉积修复试验,考察了修复试样的组织和力学特点。修复区与基材之间形成了致密冶金结合,Al,Zr,Mo,V合金元素由锻件基体到激光修复区均匀分布,无宏观偏析,硬度分布从基材到修复区依次提高。热影响区组织是由基材的双态组织过渡到网篮组织;修复区组织为粗大的原始柱状晶,晶粒内为/网篮组织,晶内片层取向随机, 宽0.4~0.5 m。修复过程中发现,激光加工工艺参数选择不当、坡度过大等原因会造成修复区组织形成气孔和熔合不良等缺陷,但是通过优化工艺参数可以获得无缺陷修复试样。修复试样的室温静拉伸结果表明,试样的抗拉强度接近锻件基体强度,但修复件的韧性比锻件稍有提高。     

Synthesis,spectroscopic characterisation and structure of the first chiral heteroleptic bis(phthalocyaninato) rare earth complexes

Treatment of MIII(Pc)(acac) (M = Sm, Eu, Gd; Pc = phthalocyaninate; acac = acetylacetonate), generated in situ, with 3-(3-pentyloxy)phthalonitrile in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in n-pentanol affords racemic mixtures of the chiral double-deckers MIII(Pc)[Pc(OC5H11)4] [Pc(OC5H11)4 = 1,8,15,22-tetrakis(3-pentyloxy)phthalocyaninate], which have been spectroscopically and structurally characterised.     

基于最新势能面的C(1D)+H2反应的环聚合分子动力学研究

本文利用环聚合分子动力学方法对C(¹D)+H₂反应开展了详细的理论研究. 计算中使用了最近构建的Zhang-Ma-Bian(ZMB)从头算势能面,该势能面对锥形交叉附近区域以及范德华区域均有精确的描述. 环聚合分子动力学计算得到的热反应速率常数与最新实验值吻合很好. 与前人计算结果比较,发现在?¹A′电子基态的ZMB-a势能面上获得的反应速率常数远大于前人构建的RKHS势能面上的结果,这是由于ZMB势能面上的范德华鞍具有与之前势能面上的范德华阱完全不同的动态学作用,表明环聚合分子动力学方法能够处理范德华作用引起的势能面拓扑结构所导致的动态学效应. 本文还揭示了b¹A′′电子激发态ZMB-b势能面以及量子效应对反应的重要性.     

傅里叶变换轮廓术中新的相位及高度算法分析

在传统傅里叶变换轮廓术三维面型测量中,为了准确得到被测物体的高度分布,必需保证投影仪出射光瞳和摄像机入射光瞳的连线与参考面平行并且在同一水平面,否则存在较大的误差。着眼于更普通的情况,讨论双瞳连线与参考面成某一夹角时的高度计算,推导出了非平行时的参考面光场及物面变形条纹光场的表达式,并给出了高度映射公式。因而,传统的傅里叶变换轮廓术测量成为角度α=0时的特例。该方法使傅里叶变换轮廓术的测量条件得到了放宽;易于通过移动投影装置或成像装置获取全场条纹;并为在难以实现双瞳与参考面平行的特殊环境下的测量提供了可行的方法。计算机模拟及实验均证实了该方法的有效性。     

激光沉积修复TA15合金的组织和力学性能

采用激光沉积修复方法对TA15槽损伤试样进行了修复试验,考察了修复试样的组织和力学特点,发现激光修复试样组织是由基材的双态组织经由热影响区过渡到修复区的网篮组织。修复区组织为粗大的原始柱状晶,晶粒内为/网篮组织,晶内片层取向随机, 宽0.4~0.5 m。分析了修复区和坡面存在熔合不良缺陷的原因,并给出了纠正措施。修复试样的室温静拉伸结果表明,试样的抗拉强度接近工业锻件水平,表明修复区与基材之间形成了致密冶金结合,但由于修复区粗大柱状晶组织,试样的冲击韧性比基材稍差。     

脑电信号的标度分析及其在睡眠状态区分中的应用

脑电信号具有长程幂律相关性及多重分形的标度特性,并随生理病理状态改变.本文首次针对睡眠脑电信号应用单重分形去趋势波动分析(detrended fluctuation analysis,简记为DFA)方法与多重分形奇异谱对睡眠脑电信号的标度特征进行系统的对比研究.发现DFA标度指数α对于不同导联和样本组间的差异较为敏感,随睡眠状态的变化不规律;而多重分形奇异强度区间Δα随睡眠状态的变化更为规律,睡眠Ⅰ期至Ⅳ期不断增大,并且导联间差异和样本组间差异均较小.多重分形Δα参数更适合作为判定睡眠状态的定量参数.     

Definitive assignments of the visible-near-IR bands of porphyrin-naphthalocyanine rare-earth sandwich double- and triple-decker compounds by magnetic circular dichroism spectroscopy

A series of heteroleptic rare-earth sandwich complexes [M(Nc)(OEP)] (M = La, Nd, Eu, Dy, and Lu; Nc = 2,3-naphthalocyaninate; OEP = octaethylporphyrinate) have been investigated by electronic absorption and magnetic circular dichroism (MCD) spectroscopy. The electronic absorption spectra of the neutral forms showed two characteristic transitions (bands I and II) in the near-IR region, both of which were systematically shifted depending on the size of their central metal. In the MCD spectra, a relatively intense Faraday A term and a significantly weak Faraday B term have been observed corresponding to bands II and I, respectively. The spectral features were successfully interpreted using a simple MO model by considering the relevant interactions of Gouterman's four orbitals of the constituent chromophores. The model succeeded in assigning the MCD spectra of the related compounds, the oxidized and reduced forms of the dimer ([M(Nc)(OEP)]+ and [M(Nc)(OEP)]-), and neutral forms of the triple-decker compounds (M2(Nc)(OEP)2, M = Nd, Eu). DFT calculations of the dimers supported the validity of this model.     

位移约束集成化处理的连续体结构拓扑优化

为解决多工况下多位移约束的连续体结构拓扑优化问题,引入了K-S函数对位移约束进行集成化处理.在建立优化模型时,基于莫尔定理按ICM方法导出约束点位移与设计变量之间的近似显函数关系,然后采用Lagrange乘子法进行求解.给出三个算例对该方法进行验证,并与ESO法、BESO法、MD法以及均匀化方法的结果进行比较.结果表明:该方法计算效率较高,并且能够计算出更合理的结构拓扑.