Iridium-catalyzed asymmetric ring opening of azabicyclic alkenes by amines

The enantioselective ring-opening reactions of azabicyclic alkenes with primary and secondary aromatic amine nucleophiles are reported using an iridium catalyst generated in situ from 1.5 mol % of [Ir(COD)Cl](2) and 3 mol % of (S)-BINAP. The reaction affords the corresponding trans-1,2-diamine derivatives in moderate to good yields with moderate to high enantioselectivities (up to 97% ee). The trans-configuration of the 1,2-diamino product 2g was confirmed by X-ray crystallography.     

Encapsulation of polyaniline in 3-D interconnected mesopores of silica KIT-6

Composite material PANI/KIT-6, with polyaniline (PANI) chains encapsulated in the 3-D interconnected pore channels of mesoporous silica, KIT-6, has been synthesized via a gas-phase method. The composite formation and the presence of PANI inside the pore channels of KIT-6 were evidenced by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), small-angle X-ray scatter (SAXS), transmission electron microscopy (TEM), and N₂ adsorption–desorption isotherms. The PANI/KIT-6 composite showed good electrical conductivity (2.4 × 10^?3 S/cm) due to the formation of 3-D networks of PANI inside the 3-D interconnected channels of KIT-6. The resistance of PANI/KIT-6 composite at different relative humidities (RH) was investigated. An essentially linear relationship between the relative resistance of the composite and the relative humidity of the environment was found from 11.3% to 97.3% RH.     

槲皮素酯类衍生物研究进展

健康生活方式特别强调食物质量,多酚在这方面发挥了关键作用。槲皮素是一种天然多酚,是多种植物性食品中发现最丰富的类黄酮类化合物之一。槲皮素是天然的抗氧化剂,可以保护细胞免受自由基造成的损害。槲皮素是一种亲脂性化合物,能够穿过细胞膜,可调节众多与疾病进展、化学预防有关的细胞内和细胞外信号通路。槲皮素具有广泛的药理活性,抗炎、抗菌、抗癌和预防心脑血管疾病,但是它低溶解度和生物利用度限制了在临床上的应用。对槲皮素的结构进行优化修饰获得了溶解性能好、生物利用度高、活性明显改善、抗癌活性增强的槲皮素衍生物。综述了近年来槲皮素酯衍生物的研究进展,为槲皮素衍生物的进一步开发提供参考。     

Red top-emitting organic light-emitting device with improved efficiency and saturated color

In this work, characteristics of microcavity top-emitting red organic light-emitting device (TEROLED) having metallic electrodes had been examined. The TEOLED shows the higher efficiency in comparison with that of the bottom OLED. However, color variation with the increasing view angles is also observed. For the purpose of diminishing the blue-shift of resonant wavelength (RW) in the device with increasing view angle, the effect of out-coupling layer on the emission properties of the TEOLED is discussed in detail. Finally, the out-coupling layer was introduced in theory without sacrificing the efficiency through precise optical simulation.     

Study on inverse taper based mode transformer for low loss coupling between silicon wire waveguide and lensed fiber

We have simulated the coupling loss of three types of Inverse Taper and taper-lensed fiber using three dimensional (3D) semi-vectorial beam propagation methods (BPM) respectively. Our results showed that the performances of exponential inverse taper and quadratic inverse taper were better than the commonly used linear inverse taper. Especially, for TM mode the improvement in the reduction of devices size is 53% and 136% for exponential and quadratic inverse taper compared with the linear inverse taper.     

Transport properties and magnetoresistance in La0.8Te0.2MnO3/ZrO2 composites

The transport properties and magnetoresistance of electron-doped manganate / insulator composites (La_0.8Te_0.2MnO₃)_{1 - x}/(ZrO₂)_x (x=0, 0.3, and 0.5) are investigated. It is found that the metal-insulator transition temperature of this system shifts to a lower value as the ZrO₂ content increases. The introduction of ZrO₂ enhances both the domain scattering and electron relative scattering in the metal transport region. In the adiabatic small polaron hopping transport region, the thermal activation energy seems invariable regardless of the ZrO₂ content. The application of a magnetic field promotes the charge transportation capabilities of the composites, and the magnetoresistance is enhanced with an increase of the ZrO₂ content. This could be attributed to the more remarkable modification effect of magnetic field on ordering degree in the composites than in pure La_0.8Te_0.2MnO₃.     

Growth of SnO2 nanoparticles via thermal evaporation method

Tin oxide (SnO₂) nanoparticles were fabricated by evaporation of Sn powers at 1000 °C in air pressure. The as-deposited SnO₂ particles were single crystal structure, which were mostly spherical shape, the diameter of particles was ranging from 200 to 600 nm. The photoluminescence (PL) spectrum showed that a sharp emission peak at around 393 nm with the excitation wavelength at 325 nm, which suggested possible applications in nanoscaled optoelectronic devices. It was also found that the holding time affects the morphology of the products. The formation mechanism of SnO₂ particles was discussed.     

Beam controller using nonlinear embedded optical transformation

Flexible and adjustable beam splitters, expanders/compressors and the cloak are presented based on a universal two-dimensional transformation formula for the embedded transformation optics. Nonlinear transformation results by the suggested formula under different conditions reveal several interesting phenomena and potential applications. All beam controllers are achieved by the nonlinear coordinate transformation.     

Phase-change behavior in Si/Sb80Te20 nanocomposite multilayer films

Phase-change behavior in Si/Sb₈₀Te₂₀ nanocomposite multilayer films were investigated by utilizing in situ resistance measurements. It was found that the crystallization temperature increased firstly with increasing Si layer thickness within the multilayer films, and then remained almost unchanged at 170°C. The multilayer films have the merits of both good thermal stability and fast phase-change speed. An increase in crystallization temperature by around 95°C was observed for the multilayer films when the Sb₈₀Te₂₀ layer thickness was reduced to 3 nm. Cross-sectional transmission electron microscopy (TEM) observations revealed that Si/Sb₈₀Te₂₀ nanocomposite multilayer films had layered structures with clear interfaces. The reversible phase change between set and reset states was verified in phase-change random access memory (PCRAM) cell based on [Si (1 nm)/Sb₈₀Te₂₀ (5 nm)]₁₇ multilayer film.