配位聚合物[HgI2(bpea)]n[bpea=1,2-双(4-吡啶基)乙烷]的合成结构表征和光学折射效应

制备4,4-连吡啶基二卤加和物[MX2(4,4′-bipy)]n仍然有较大困难.这类化合物数量不多且已报道的多为难处理的微晶材料.本文在室温下通过简单的操作合成了新的碘化汞连吡啶乙烷加和物[HgI2(bpea)]nox-射线单晶衍射分析表明其中的汞原子通过与两个碘原子以及吡啶乙烷的两个氮原子配位形成扭曲的四面体构型.每个HgI2单元由bpea桥连形成锯齿状链.其非线性光学性质用8-纳秒激光在532nm波长进行了研究.该化合物相对于入射光表现为一定的光学吸收和强的自聚焦效应,其三阶非线性吸收系数α2=1.1×10-11m@W-1,折射系数n2=5.29×10-188m2@w-1.     

四溴-2,3-萘酞菁铅的合成及性质研究

以1,8-二氮杂双环[5.4.0]+-碳烯-7(DBU)为催化剂合成了中心原子为重原子铅、环取代基为重原子溴的萘酞菁配合物四溴-2,3-萘酞菁铅[PbNcBr₄],并研究了该配合物的电子吸收光谱、热稳定性、光限幅特性及重原子对其光限幅特性的影响及其机理.该配合物在近红外区(795～825nm)有强吸收(Q带),溴取代可使配合物Q带略微蓝移,溶剂的极性对配合物的电子吸收光谱有较大影响.该配合物具有较高的热稳定性,气氛对其热稳定性有明显影响,其在N₂气氛中的热稳定性明显比在O₂气氛中的高;在O₂气氛中为一步分解,在N₂气氛中为多步分解.标题配合物具有优异的非线性光限幅特性,在高线性透射率88%时的限幅阈值为148mJ/cm²,限幅幅值为332mJ/cm²,损伤阈值约为3J/cm²,其光限幅特性明显优于光限幅新材料C₆₀(透射率70%时,限幅阈值大于240mJ/cm²).重原子铅和溴可显著优化材料的非线性光限幅特性.     

Simple measurement of nonlinear refraction by using a single pulse and beam

A very simple technique, by which both the magnitude and the sign of nonlinear refraction can be determined through using only one single pulse and beam with a phase object, is presented. Using this technique, only the transmittance of an aperture in the far field is investigated. We study the nonlinear refraction of the carbon disulfide by using the presented technique with 21~ps pulses at a wavelength of 532~nm as a test.     

相位物体$lt;i$gt;Z$lt;/i$gt;-扫描研究金属簇合物［$lt;i$gt;Tp$lt;/i$gt;*W($lt;i$gt;μ$lt;/i$gt;$lt;sub$gt;3$lt;/sub$gt;-S)$lt;sub$gt;3$lt;/sub$gt;Cu$lt;sub$gt;3$lt;/sub$gt;$lt;i$gt;Py$lt;/i$gt;$lt;sub$gt;3$lt;/sub$gt;($lt;i$gt;μ$lt;/i$gt;$lt;sub$gt;3$lt;/sub$gt;-Br)］($lt;i$gt;PF$lt;/i$gt;$lt;sub$gt;6$lt;/sub$gt;)/DMF溶液的瞬态热致非线性折射

在纳秒时域,采用相位物体（PO）Z-扫描技术研究了一种新型金属簇合物溶液的瞬态热致非线性效应.该方法的最大优点是很容易区分瞬态热致非线性折射和三阶非线性折射.本文利用PO Z-扫描和传统Z-扫描研究了在8 ns脉宽、不同能量激光脉冲作用下［Tp*W（μ₃-S）₃Cu₃Py₃（μ₃-Br）］（PF₆）/DMF溶液的光学非线性.从声波方程和热传导方程出发,对实验结果进行了理论分析和数值模拟,理论值和实验结果很好的吻合.研究结果表明,样品溶液的非线性折射主要来源于瞬态热致非线性效应. 关键词： Z-扫描')" href="#">相位物体 Z-扫描 瞬态热致非线性折射 光克尔效应 DMF     

辐射对称金字塔型剪纸的力学行为

通过在弹性薄板上引入切口,构建了多边形辐射对称金字塔型剪纸结构.利用伽辽金法求解的悬臂梁形变公式和悬臂梁组合的方法,创建了用于解释形变过程的梁模型,得到n个模块的正N边形金字塔结构的弹性系数与结构参数的关系公式,并求出弹性系数线性阈值的表达式,解释了该结构产生平面外扭曲的原因.利用推导的梁模型公式,并通过有限元仿真和实验的方法,系统研究了辐射对称金字塔型剪纸结构的力学响应特征,验证模型的准确性,并用于已有报道的石墨烯剪纸结构的力学特征分析.这项工作系统解释了竖直拉伸的金字塔型剪纸结构的力学响应.     

逐步聚类分析在医学研究中的应用

本文提出了一个多变量逐步聚类算法,它可应用于逐步回归所适用的范围,但在处理离散变量和连续变量,以及变量间的非线性关系上,更具有优越的性能.文中用此法研究了河南林县姚村公社49个大队食管癌和食管上皮重度增生患病率与四季饮水井中NO₃^-和NO₂^-含量的相关关系,探索食管癌的发生、发展与亚硝胺化合物前体的关系,结果表明:食管癌患病率主要与井水中夏季NO₃^-的含量,春季NO₂^-的含量有显著的“正相关”关系,而食管上皮重度增生患病率主要与井水中春季NO₂^-、NO₃^-,秋李NO₂、NO₃^-,以及冬季NO₂^-,NO₃^-的含量有显著的“正相关”关系.实践证明:本文所提出的逐步聚类分析法是医学研究中一个有效的统计方法。     

C-Alkylation of α-acylamino ketones. A versatile synthesis of α-alkyl α-amino ketones

C-Alkylation of some α-acylamino ketones were achieved with alkyl halides by means of sodium ethoxide in ethanol. The present paper deals with the C-alkylation of N,N-diformylamino ketones and the difference in stability of the amide group.     

Electrochemical Investigation of Heterogeneous Affinity Behaviour of Methylene Blue and G-quadruplex

The heterogeneous binding behaviour between methylene blue (MB) and G-quadruplex, one kind of single-stranded (ss) DNA with specific guanine tetrads, has been thoroughly studied via electrochemical techniques. Positively charged MB interacted electrostatically with both G-quadruplex and normal ssDNA but the binding and dissociation kinetics between them were significantly different. Compared with ssDNA, G-quadruplex had a slower binding rate constant and dissociation rate constant with MB since there existed other different binding mechanisms between G-quadruplex and MB besides electrostatic interaction. This work might provide valuable information in the design and development of DNA sensors.     

Solvent-free thermocyclization of the unactivated linear gramicidin S precursor and analogues

A convenient thermocyclization of the linear gramicidin S precursor and its analogues is demonstrated. With the preorganized β-sheet conformation, the unactivated linear precursors can cyclize into the corresponding head-to-tail cyclic products in high yield after being heated under solvent-free conditions.     

Synthesis,Self-assembly and Electrode Application of Mussel-inspired Alternating Copolymers

We reported the first mussel-inspired alternating copolymer with a high amount of catechol groups(50% molar ratio) through a facile epoxy-amino click reaction between 9,9-bis(4-(2-glycidyloxyethyl)phenyl fluorene(BGEPF) and dopamine(DA).The obtained copolymers were used to prepare carbon/nitrogen-doped α-Fe_2O_3 nanoparticles through self-assembly,coordination and calcination,which displayed excellent electrochemical performance as anode materials for Li-ion batteries.