R-(—)-1-氯甲基-4-乙基-2,8,9-三氧杂-5-氮杂-1-硅杂三环[3,3,3,0~(1.5)]十一碳烷的晶体结构

杂氮硅三环是一类具有特殊生理活性的新型有机硅化合物,有关其合成及性质在近20年中已有大量报道。特别是当R为氯甲基时,该化合物的生理活性很高,用它制成的药膏已用来治疗脱发及伤口愈合。因此,1-氯甲基杂氮硅三环(Ⅰ)的分子结构引起了人们的关注,先后有人报道了(Ⅰ)及1-氯甲基-3,7-二甲基,1-氯甲基-3,7,10-三甲基     

Organometallic titanocene complex as highly efficient bifunctional catalyst for intramolecular Mannich reaction

Bifunctional catalysts bearing two catalytic sites, Lewis acidic organometallic titanocene and Brønsted acidic COOH, have been assembled in situ from Cp₂TiCl₂ with carboxylic acid ligands, showing high catalytic activity over an intramolecular Mannich reaction towards synthesis of 2‐aryl‐2,3‐dihydroquinolin‐4(1H)‐ones. The determination of the bifunctional catalyst Cp₂Ti(C₈H₄NO₆)₂ was elucidated by single X‐ray HR‐MS and investigation of catalytic behavior. In particular, masking the Brønsted acidic COOH catalytic site with dormant COOMe lowered the reaction yield greatly, indicating that two catalytic sites work together to maintain high catalytic efficiency.     

Highly improved crystallization behavior of poly(L‐lactide) induced by a novel nucleating agent: substituted‐aryl phosphate salts

In this work, a novel nucleating agent (NA) based on substituted‐aryl phosphate salts was introduced into poly(L‐Lactide) (PLLA). The nonisothermal and isothermal crystallization behaviors of nucleated PLLA samples were investigated through differential scanning calorimetry (DSC), wide angle X‐ray diffraction, and polarized optical microscope (POM). Furthermore, the effect of annealing treatment on the cold crystallization behaviors of nucleated samples was also investigated. The results show that the crystallization of PLLA, whether for the melt crystallization (including nonisothermal and isothermal crystallization process) or for the cold crystallization (including the cold crystallization occurring during the DSC heating process and during the annealing process), is greatly dependent upon the content of NA. At relatively lower NA content (≤0.1 wt%), the nucleation effect of NA is inconspicuous, however, at higher NA content (≥0.2 wt%), it exhibits great nucleation effect for the crystallization of PLLA. Further results show that the double endothermic peak of PLLA depends on the temperature applied for the crystallization. Copyright © 2012 John Wiley & Sons, Ltd.     

Conductive 2D Metal-organic Framework (Co,NiCo, Ni) Nanosheets for Enhanced Non-enzymatic Detection of Urea

2D metal-organic framework (MOF) has potential applications in electrocatalysis owing to fast mass transfer, charge transfer and large specific surface area. Here, we had prepared three conductive 2D MOF based on Ni, NiCo and Co in a simple and rapid way. The 2D nanostructure of MOF was confirmed by SEM and TEM. The chemical composition was studied by XRD, Raman and XPS spectrum. The electrochemical oxidation and detection was investigated through cyclic voltammetry and current-time method. Their sensing performance for urea was determined by varying oxidation potentials and metal sites. The non-enzymatic Ni-, NiCo- and Co-MOF sensors had good catalytic activity for urea. Compared with NiCo- and Co-MOF, Ni-MOF had a wider linear range (0.5–832.5 μM), high sensitivity (1960 μA mM⁻¹ cm⁻²), low detection limit (0.471 μM), and fast response time. The sensors had well repeatability, reproducibility, and selectivity to specific interfering species. Furthermore, Ni- and NiCo-MOF modified electrode was also applied to detection of milk samples. The results showed that the recovery was satisfactory, which further confirmed the effectiveness of non-enzyme sensor. In general, the highly-sensitive 2D Ni- and NiCo-MOF modified electrode has great potential as nonenzymatic urea sensors for real samples detection in hydrogen energy, clinical diagnostics, and environmental protection, et al.     

Binder-free activated carbon papers for high-performance electric double-layer capacitors

A binder-free activated carbon paper (ACP) was simply prepared for electric double-layer capacitors by the carbonization of filter paper, followed by heat-air activation at a lower temperature. The electrochemical cells assembled using the as-prepared ACP-470 provides a high specific capacitance of 296.4 F g^?1 at current density of 0.5 A g^?1 and a high rate performance at a current density of 150 A g^?1 with a capacitance of 191.2 F g^?1 and a high cycle ability at 10,000 recycles with 100 % capacitance retention. In addition, the ACP has a lower electrical resistivity and provides an effective energy storage performance with a maximum energy density of 41.2 Wh kg^?1 and a maximum power density of 138.0 kW kg^?1 in a voltage range of 1 V.     

Multicomponent Reactions for Diverse Synthesis of N‐Substituted and NH 1,4‐Dihydropyridines

The multicomponent reactions of aldehydes, electron deficient alkynes and amines have been successfully performed to yield a number of symmetrical 2,6‐unsubstituted 1,4‐dihydropyridines (1,4‐DHPs). This method has been found generally applicable for the synthesis of both N‐substituted and N‐unsubstituted 1,4‐DHPs by employing secondary amine to activate the alkyne component via enaminoester intermediates. The present method runs through an enamine type activation, which is different from the known approach employing AcOH as solvent.     

石墨烯纳米孔的制备及λ-DNA穿孔初步研究

纳米孔测序是有可能实现"$1,000 Genome"目标的技术之一.近年来,研究较多的纳米孔有蛋白质纳米孔和硅基材料的固态纳米孔.蛋白孔寿命比较短,而基于硅基底的固态纳米孔深度显著超过单链DNA相邻碱基的间距,所以,无法实现DNA的单个碱基的分辨.作者用聚焦离子束先制造氮化硅基底,并在该基底上铺设石墨烯,再用聚焦电子束刻蚀石墨烯,获得直径10 nm以下的纳米孔,初步分析了DNA穿越纳米孔时产生的电信号及穿孔噪音,向单层石墨烯纳米孔测序DNA迈出了一步.     

三、四唑高能离子盐的研究概况

为满足火炸药等领域对多功能含能材料的需求,高生成焓、高密度、钝感、稳定和环境友好的三、四唑高能离子盐的研究受到广泛关注。 本文综述了10年来三唑和四唑高能离子盐的合成及性能研究概况,为含能离子盐的研究提供参考。     

近场强度分布对线性相位反演算法复原效果的影响

利用数值仿真的方法详细的分析了近场强度分布对线性相位反演算法复原效果的影响.对近场强度分布分别为倾斜、环形和高斯随机型的情况下的复原结果与光强均匀时的复原结果进行对比,结果表明像倾斜型这种大部分为奇函数的近场强度分布对复原效果的影响比较恶劣;而像环形、随机型这样的偶函数或大部分为偶函数的近场强度分布对复原效果的影响则不...     

Optical characteristics of subwavelength metallic grating coupled porous film surface plasmon resonance sensor with high sensitivity

A high performance sub-wavelength metallic grating coupled surface plasmon resonance (SWMGCSPR) sensor with metal and porous composite layer is proposed. Rigorous coupled-wave analysis (RCWA) is conducted to prove the design feasibility, characterize the sensor's performance and determine geometric parameters of the structure, which is also employed to compute the electromagnetic (EM) field distributions at the resonant wavelengths. Parameters of sensing platform are optimized to achieve the best performance of the SPR sensor. Obtained results reveal that the proposed structure can excite SPR with negative diffraction order of SWMG. Both wavelength and angular sensitivities are greatly enhanced because surface plasmon wave (SPW) exhibits a large penetration depth which will enlarge the distance of interactions between SP and analytes. The detection sensitivities and quality parameters are estimated to be 700 nm/RIU and 509°/RIU with full width at half maximum (FWHM) less than 2.5 nm using the same optimized structure.