单分子层保护纳米 Au 粒子表面配位催化剂的制备及其应用

 贵金属纳米粒子由于其小尺寸效应而表现出特殊的催化性能. 综述了纳米 Au 粒子表面配位催化剂的制备方法及其在催化中的应用. 由于 Au 可与硫化物形成配位键, 所以硫化物可在 Au 表面形成有序单分子膜. 单分子膜保护的 Au 纳米粒子具有非常好的溶解性、分散性、稳定性, 以及由不同的表面功能团而导致的不同的催化性能. 该催化体系兼具均相催化剂和多相催化剂的特点, 这对开发新型催化剂具有重要的理论和实际意义.     

基于卷绕型带状线的感应电压叠加器的初步实验

 提出了一种基于卷绕型带状线和感应电压叠加器的重复频率脉冲电子束加速器的技术方案。介绍了一台感应电压叠加器感应单元的结构设计,并建立相应的电路模型,对其响应特性进行了模拟研究。介绍了卷绕型带状线的设计原理,制作了一台输出阻抗约3 Ω、脉冲宽度约230 ns的固态化卷绕型带状脉冲形成线。利用该脉冲发生器作为馈源,对感应电压叠加器感应单元的响应特性进行了实验研究,表明感应单元响应良好。对4级感应电压叠加器分别进行了单次脉冲和5 Hz重复频率的实验研究,结果表明叠加器的输出电压约为输入电压幅值的4倍,电流效率约80%,重复频率条件下,脉冲序列重复性较好。     

Interfacial reaction of intermetallic compounds of ultrasonic-assisted brazed joints between dissimilar alloys of Ti6Al4V and Al4Cu1Mg

Ultrasonic-assisted brazing of Al4Cu1Mg and Ti6Al4V using Zn-based filler metal (without and with Si) has been investigated. Before brazing, the Ti6Al4V samples were pre-treated by hot-dip aluminizing and ultrasonic dipping in a molten filler metal bath in order to control the formation of intermetallic compounds between the Ti6Al4V samples and the filler metal. The results show that the TiAl(3) phase was formed in the interface between the Ti6Al4V substrate and the aluminized coating. For the Zn-based filler metal without Si, the Ti6Al4V interfacial area of the brazed joint did not change under the effect of the ultrasonic wave, and only consisted of the TiAl(3) phase. For the Zn-based filler metal with Si, the TiAl(3) phase disappeared and a Ti(7)Al(5)Si(12) phase was formed at the interfacial area of the brazed joints under the effect of the ultrasonic wave. Due to the TiAl(3) phase completely changing to a Ti(7)Al(5)Si(12) phase, the morphology of the intermetallic compounds changed from a block-like shape into a lamellar-like structure. The highest shear strength of 138MPa was obtained from the brazed joint free of the block-like TiAl(3) phase.     

Tuning the frontier molecular orbital energy levels of n‐type conjugated copolymers by using angular‐shaped naphthalene tetracarboxylic diimides,and their use in all‐polymer solar cells with high open‐circuit voltages

An angular‐shaped naphthalene tetracarboxylic diimide (NDI) was designed and synthesized as a new building block for n‐type conjugated polymers to tune their energy levels. Three n‐type copolymers incorporating this angular‐shaped NDI as the acceptor moiety were obtained by Stille coupling reactions and had number average molecular weights of 18.7–73.0 kDa. All‐polymer bulk‐heterojunction solar cells made from blends of these polymers with poly(3‐hexylthiophene) gave a power conversion efficiency up to 0.32% and exhibited an open‐circuit voltage (V_oc) up to 0.94 V due to their relative high‐lying lowest unoccupied molecular orbital energy levels. The high V_oc of 0.94 V is higher than that of solar cells based on linear‐shaped NDI‐containing polymers (<0.6 V). The results indicate that the angular‐shaped NDI is a promising building block for constructing nonfullerene polymer acceptors for solar cells with high open‐circuit voltages. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Electronic control of product distribution in the [5+5]-coupling of ortho-alkynylbenzaldehyde derivatives and γ,δ-unsaturated carbene complexes

The coupling of highly oxygenated ortho-alkynylbenzaldehyde derivatives with γ,δ-carbene complexes was evaluated systematically. In all of the electron-rich systems investigated the exclusive product of the reaction is the dihydrophenanthrene derivative. Only the extremely electron-withdrawing methanesulfonate group can prevent this process from occurring. The use of the base additive collidine resulted in a surprising yield enhancement but no other discernable effect on the course of the reaction. Dihydrophenanthrene formation was attributed to rapid dehydration after the opening of a benzo-oxanorbornene intermediate.     

Fluorimetric determination of tetracycline and anhydrotetracycline

Summary A rapid fluorimetric method employing the complexes of Al³⁺ with tetracycline (TC) and anhydrotetracycline (ATC) has been used for the measurement of the concentrations of TC and ATC in about 10^–7–10^–6 mol/l. The assay offers simplicity and rapidly compared with other methods. The recoveries in the determination of synthetic samples are in the range of 95–103% for TC and 101–120% for ATC. Several determinations of TC and ATC in serum and urine have been carried out with satisfactory results.     

铕-3-(2-萘甲酰基)-2-苯基苯并二氢吡喃-4-酮-邻菲罗啉配合物的合成及荧光性能研究

为了探讨2,3-二氢黄酮类化合物在发光材料方面的应用,首先合成了2,3-二氢黄酮类衍生物[3-(2-萘甲酰基)-2-苯基苯并二氢吡喃-4-酮(L)]配体,然后利用Eu(III)与此配体和水/邻菲罗啉(Phen)反应得到两种新型的红色荧光配合物。运用元素分析、红外光谱与荧光光谱等手段对相关物质进行了系统的表征。表征结果表明:两个新配合物的组成分别为Eu(L)3·2H2O和Eu(L)3·Phen;荧光光谱研究显示,两种配合物的配体能将吸收的能量有效地传递给铕离子,从而使配合物发射出强的铕离子的特征荧光,且两个配合物Eu(L)3·2H2O和Eu(L)3·Phen均以5D0→7F2跃迁的荧光发射最强。得到了两种新的高效的红色荧光材料。     

Inhibition effect of pomelo peel extract for N80 steel in 3.5% NaCl saturated with CO2 solution

Research on Chemical Intermediates - Pomelo peel extract (PPE) has been evaluated as a corrosion inhibitor for N80 steel in 3.5% NaCl saturated with CO2 solution using weight loss measurements,...