热电物理的研究进展

热电效应在发电，致冷方面有巨大的应用潜力，这些年来，人们为提高热电能量转换效率进行了不懈的努力，文章概述了从机理上提高材料热性能的一般途径，在此基础上，介绍了最近几年在氧化物超导体，ＴＰｎ３化合物，富硼固体等新材料体系中，以及在非均匀材料，复合型材料，量子阱结构等新形式材料中的研究结果。     

800nm激光泵浦掺Nd^3＋的氟化物玻璃光纤正向双程超荧光分析

从实验上探讨了掺Ｎｄ＾３＋的氟化物玻璃光纤正向双程超荧光基本特性，包括输入－输出特性、输出－带宽特性以及输出－波长（激发）特性。并给出了理论上的拟合公式，实验表明利用氟化物玻璃光纤有望获得性能优异的有应用前景的低相干度集成化光源。     

三(2-苯并咪唑亚甲基)胺硝酸镍(Ⅱ)配合物的合成及结构

三（２－苯并咪唑亚甲基）胺简称ＮＴＢ与Ｎｉ（Ⅱ）的硝酸盐形成配合物Ｃ２８Ｈ３５Ｎ９Ｏ９Ｓ２Ｎｉ。本文报道其合成，红外光谱及晶体结构。该化合物为三斜晶系，空间Ｐ１↑－，ａ＝９．６５０（３），ｂ＝１２．７１６（２），ｃ＝１４．４３６Ａ，α＝１１．４６（２），β＝９１．６６（３），γ＝９７．５５（２）°，Ｖ＝１７１８（２）Ａ＾３，Ｚ＝２，Ｆ（０００）＝７９３，Ｄｃ＝１．４８ｇ／ｃｍ＾３，Ｍｒ＝７６４．１     

Synthesis and Insulin—sensitizing Activity of a Series of 2—Benzyl—1,3—dicarbonyl Derivatives

A series of 2-benzyl-1,3-dicabonyl derivatives was synthesized.Their insulin-sensitizing activity was evaluated in 3T3-L1 preadipocyte cells.Compounds3,26 and 27 were found to possess strong insulin-sensitizing activity in vitro and were selected for further hypoglycemic evaluation in vivo.     

ortho-Mercuration of ferrocenylimines

The mercuration of a series of aryliminomethylferrocenes occurred predominantly in an ortho-position of the substituted ferrocenyl ring to yield 2-mercurated ferrocenylimines. The regiospecificity of this reaction suggests that the mercury is directed into the ortho-position by coordination of the mercury to imino nitrogen with subsequent electrophilic substitution. The chromatographic and spectral properties of the 2-mercurated products show the presence of an intramolecular N → Hg coordination via the five-membered ring in these molecules, which was further confirmed by the single-crystal structure analysis of 2-chloromercuro-1-[(4-methoxyphenylimino)methyl]ferrocene.     

Steric effects of substituted quinolines on lithium coordination geometry

The X-ray crystal structures of a series of lithium quinolates – lithium 8-hydroxyquinolinate (Liq), lithium 2-methyl-8-hydroxyquinolinate (MeLiq), and 2-phenyl-8-hydroxquinolinate (PhLiq), are compared. The substitution at the 2-position of the 8-hydroxyquinoline ligand has significant impact on the aggregation of the lithium complex in the crystalline state. Liq and MeLiq molecules crystallize as hexamers, whereas PhLiq crystallizes as a tetramer. The possible influence of crystal-packing forces on the preferred cluster structure was probed using density functional theory calculations on a systematically varied set of Liq, MeLiq, and PhLiq clusters. For Liq and MeLiq, the observed structures match the most stable computed structures. In the PhLiq case, the observed tetrameric structure is computed to be less stable (+1.2 kcal/mol/monomer) than the lowest energy structure, a hexamer. In this case, solid-state effects probably outweigh small differences in cluster stability.     

波束开角对多普勒测频结果的影响*

具有不同波束开角的声学多普勒测速设备未标定的测速结果存在偏差。基于水底椭圆散射模型研究了波束开角对声学多普勒测速结果的影响,对提高声学测速性能具有实际意义。水底椭圆散射模型下,足印上不同方位传播损失和散射强度存在差异,导致频谱不对称,测频结果偏小。利用不对称系数量化频谱不对称程度,若波束开角增大,方位不对称系数随之增大,测频偏差增大,推导了波束开角导致的测频偏差解析式。分析仿真和外场试验数据测频结果可知,不同多普勒频移下测频偏差和理论计算值相符,不同波束开角下实际测频偏差与理论公式计算的测频偏差均随波束开角增大而增大。     

Phenothiazine-based covalent organic frameworks with low exciton binding energies for photocatalysis

Designing delocalized excitons with low binding energy (E_b) in organic semiconductors is urgently required for efficient photochemistry because the excitons in most organic materials are localized with a high E_b of >300 meV. In this work, we report the achievement of a low E_b of ∼50 meV by constructing phenothiazine-based covalent organic frameworks (COFs) with inherent crystallinity, porosity, chemical robustness, and feasibility of bandgap engineering. The low E_b facilitates effective exciton dissociation and thus promotes photocatalysis by using these COFs. As a demonstration, we subject these COFs to photocatalytic polymerization to synthesize polymers with remarkably high molecular weight without any requirement of the metal catalyst. Our results can facilitate the rational design of porous materials with low E_b for efficient photocatalysis.

We report the construction of phenothiazine-based covalent organic frameworks, which exhibited diverse structures, the feasibility of bandgap engineering, and unprecedented ultralow exciton binding energy of ∼50 meV for photocatalytic polymerization.