基于双(4-(1H-咪唑-1-基)苯基)甲酮的三个锌配位聚合物的结构多样性和发光性质

通过溶剂热法合成了3个锌的配位聚合物{[Zn₂(bipmo)₂(ipa)₂]·3H₂O}_n(1)、{[Zn (bipmo)(5-OH-ipa)]·DMA·H₂O}_n(2)和{[Zn (bipmo)(5-Me-ipa)]·H₂O}_n(3),其中bipmo=双(4-(1H-咪唑-1-基)苯基)甲酮,H₂ipa=间苯二甲酸,5-OH-ipaH₂=5-羟基间苯二甲酸,5-Me-ipaH₂=5-甲基间苯二甲酸。用元素分析、红外光谱和单晶X射线衍射等技术对结构进行了表征。单晶X射线衍射分析表明,配合物1具有二重互穿的{4⁴·6²}二维网络结构,配合物2则是{6⁵·8}拓扑的二维结构,配合物3却表现为二维的{6³}拓扑网络。间苯二甲酸上5-位取代基的不同对最终的结构形成有重要的影响。此外,对化合物1~3的发光性质也进行了详细研究。     

不同V型辅助配体构筑的两个镉配位聚合物的合成、结构和荧光性质

在溶剂热条件下,合成了2个基于V型辅助配体（bipmo、bppmo）的镉配位聚合物{[Cd （bipmo）（NDC）]·1.75H₂O}_n（1）和{[Cd （bppmo）（NDC）（H₂O）]·H₂O}_n（2）,其中H₂NDC=2,6-萘二羧酸,bipmo=双（4-（1H-咪唑-1-基）苯基）甲酮,bppmo=双（4-（吡啶-4-基）苯基）甲酮。利用单晶X射线衍射、键价和分析、红外光谱和元素分析对其结构进行了表征。研究发现,配合物1具有二重互穿的{6³}拓扑结构。配合物2同样是3-连接的{6³}拓扑,却存在三重穿插结构。分析表明,V型配体对最终结构的形成有很大影响。此外,对配合物1和2的发光性质也进行了详细研究。     

Fdtd simulation for the EMI properties of impedance surface enclosures

An enclosure with impedance interior surfaces is studied using the FDTD method. The FDTD simulation shows a wonderful depression of the resonance-related EMI signals in the impedance surface enclosure.This work was supported by the National Natural Science Fund of China, and by the He Yingdong Education Fund.     

A Novel Reconfiguration CPW Leaky-Wave Antenna for Millimeter-Wave Application

A novel reconfigurable millimeter-wave leaky-wave antenna is proposed according to the radiation characteristics of periodically loaded coplanar waveguide and simulated by the finite-difference time-domain method. The simulated results demonstrate that the single main beam of this antenna operating at 35.0GHz can scan with small steps in the E-plane from –90° to 90° except the angle around 0°. The main beam scanning is obtained by the antenna structure reconfiguration with nine discrete states controlled by embedded switches and two feed ports. The antenna is useful for millimeter-wave applications.     

Catalytic Linkage Engineering of Covalent Organic Frameworks for the Oxygen Reduction Reaction

Metal-free covalent organic frameworks (COFs) have been employed to catalyze the oxygen reduction reaction (ORR). To achieve high activity and selectivity, various building blocks containing heteroatoms and groups linked by imine bonds were used to create catalytic COFs. However, the roles of linkages of COFs in ORR have not been investigated. In this work, the catalytic linkage engineering has been employed to modulate the catalytic behaviors. To create single catalytic sites while avoiding other possible catalytic sites, we synthesized COFs from benzene units linked by various bonds, such as imine, amide, azine, and oxazole bonds. Among these COFs, the oxazole-linkage in COFs enables to catalyze the ORR with the highest activity, which achieved a half-wave potential of 0.75 V and a limited current density of 5.5 mA cm⁻². Moreover, the oxazole-linked COF achieved a conversion frequency (TOF) value of 0.0133 S⁻¹, which were 1.9, 1.3, and 7.4-times that of azine-, amide- and imine-COFs, respectively. The theoretical calculation showed that the carbon atoms in oxazole linkages facilitated the formation of OOH* and promoted protonation of O* to form the OH*, thus advancing the catalytic activity. This work guides us on which linkages in COFs are suitable for ORR.     

Chemical modification on UHMWPE microparticles to improve the interfacial and tribological properties of UHMWPE/carbon fabric/phenolic laminate in water environment

Carbon fabric (CF)/phenolic laminates filled with pristine and chromic acid treated ultra high molecular weight polyethylene (UHMWPE) microparticles were fabricated. Their interfacial and tribological properties in water environment were comparatively investigated. The interlaminar shear strength (ILSS) of the laminates was tested on a universal testing machine (DY35), and the tribological properties were evaluated by a block‐on‐ring tribo‐tester. The worn surfaces and the interfaces of the laminates were respectively analyzed by scanning electron microscope (SEM) and field emission SEM (FESEM). The change of the chemical composition of UHMWPE microparticles after chromic acid etching was analyzed by Fourier transform infrared spectroscopy (FTIR). The chemical state of carbon fiber surface was examined using X‐ray photoelectron spectroscopy (XPS). The results revealed that the chromic acid treated UHMWPE microparticles had more remarkable effect than the pristine ones on improving not only ILSS and wear resistance of CF/phenolic laminate, but also its immunity to water environment. This should be attributed to the strengthened interfaces in treated UHMWPE/CF/phenolic laminate, which were characterized by the drawn dendritic UHMWPE fibrils firmly clinging on the surfaces of carbon fibers and resin in a Boston ivy‐like manner. Copyright © 2015 John Wiley & Sons, Ltd.     

利用小波变换检测电化学噪声信号波形

简述了应用小波变换检测点蚀电化学噪声信号的基本原理,对在3.5％ NaCl溶液中工业纯铝发生点蚀的电化学噪声信号检测分析表明：小波变换能够提取发生点蚀的电化学噪声信号和测量系统噪声在多惊讶分辨空间中的波形特征,根据表征该特征的小波系数模极大值在不同尺度下的传播特性,可实现对点蚀电化学噪声信号波形的检测。     

Fabrication of nanochannels via near-field electrospinning

A simple and low-cost method is suggested to fabricate nanochannels via Near-Field Electrospinning (NFES). In this process, orderly and patterned nanofibers direct-written by NFES are used as sacrificial templates. Well-defined nanochannels are available after the removal process of both sacrificial fibers and material coating over the fibers. The sacrificial fiber, controlled by NFES, dominates the channel geometry. The channel width ranges from 133 nm to 13.54?μm while the applied voltage increases from 1.2 kV to 2.5 kV. Complicated wave-shape and grid pattern channels are presented under a corresponding movement of substrate. This method integrates electrospinning with conventional MEMS fabrication technology and has a potential in micro/nano manufacturing.     

An Efficient Synthesis of Polysubstituted Dihydropyrans via Iodocyclization Reaction of Allylic Alcohols

Iodomethyl‐ and sulfonyl‐containing polysubstituted dihydropyrans were synthesized conveniently in high yield by FeCl₃·6H₂O catalyzed iodocyclization of allylic alcohols.     

Syntheses and supramolecular structures of two 5‐nitrosalicylate titanocene complexes

Two 4‐coordinated titanocene complexes, [(η⁵‐C₅H₅)₂Ti(O,O′)(5‐NO₂‐OCC₆H₃)] (I) and [(η⁵‐C₅H₅)₂Ti(2‐OH‐5‐NO₂‐O₂CC₆H₃)₂] (II), have been synthesized by reaction of Cp₂TiCl₂ and 5‐nitrosalicylic acid in aqueous media. Single‐crystal X‐ray analyses of I and II display the mononuclear forms of Ti^IV, and geometries at titanium atoms are distorted tetrahedrons, while the coordination environment at Ti^IV in complex I is different from that in complex II. Crystallographic characterization revealed that each of the complexes exhibits a three‐dimensional framework constructed through weak interactions, which are H‐bonding, π–π stacking and C–H·π interactions, but they differ greatly when forming the three‐dimensional network structure in both complexes. The results show that the dramatic change of conditions has great effect on the molecular structure of 5‐nitrosalicylate titanocene, thereby significantly influencing the weak interactions and the specific framework structure. Copyright © 2005 John Wiley & Sons, Ltd.