微波消解——FAAS测定康定鼠尾草中8种元素的含量

用微波消解-火焰原子吸收光谱法测定了康定鼠尾草药材中8种元素(钙、铜、铁、锰、锌、镁、铅、镉)的含量。结果表明,康定鼠尾草药材中含有较丰富的镁、钙、铁,该法灵敏度高、快速、准确,所测数据可为康定鼠尾草药材的合理利用提供可靠依据。     

Efficient Lewis acid ionic liquid-catalyzed synthesis of the key intermediate of coenzyme Q10 under microwave irradiation

An efficient synthesis of a valuable intermediate of coenzyme Q(10) by microwave-assisted Lewis acidic ionic liquid (IL)-catalyzed Friedel-Crafts alkylation is reported. The acidity of six [Etpy]BF(4)-based ionic liquids was characterized by means of the FT-IR technique using acetonitrile as a molecular probe. The catalytic activities of these ionic liquids were correlated with their Lewis acidity. With increasing Lewis acid strength of the ionic liquids, their catalytic activity in the Friedel-Crafts reaction increased, except for [Etpy]BF(4)-AlCl(3). The effects of the reaction system, the molar fraction of Lewis acid in the Lewis acid ILs and heating techniques were also investigated. Among the six Lewis acid ionic liquids tested [Etpy]BF(4)-ZnCl(2) showed the best catalytic activity, with a yield of 89% after a very short reaction time (150 seconds). This procedure has the advantages of higher efficiency, better reusability of ILs, energy conservation and eco-friendliness. The method has practical value for preparation of CoQ(10) on an industrial scale.     

Rh(III)-catalyzed oxidative coupling of N-aryl-2-aminopyridine with alkynes and alkenes

[RhCp*Cl(2)](2) (1-2 mol %) can catalyze the oxidative coupling of N-aryl-2-aminopyridines with alkynes and arylates to give N-(2-pyridyl)indoles and N-(2-pyridyl)quinolones, respectively, using Cu(OAc)(2) as an oxidant. Coupling with styrenes gave mono- and/or disubstituted olefination products.     

原子吸收光谱法测定野胡萝卜中的微量元素

采用湿法消化溶解样品，用原子吸收光谱法测定了野胡萝卜叶及根中的Zn、Mn、Fe、Cu等元素的含量。结果表明，该法的平均相关系数≥0．9995；测定样品的相对标准偏差为0．31％．1．60％；样品的回收率在96．30％～105．88％之间，表明该法准确、可靠，测定结果为更好地开发野胡萝卜资源提供了参考依据。     

Pb/Al codoped germano-silicate optical fiber with high non-resonant third-order nonlinearity

A germano-silicate optical fiber codoped with Pb²⁺ and Al³⁺ was developed by modified chemical vapor deposition and solution doping techniques. The non-resonant third-order optical nonlinearity was measured to be 6.9105 × 10⁻²⁰ m²/W by using the continuous-wave self-phase modulation method. The enhanced non-resonant nonlinearity was ascribed to the increasing number of non-bridging oxygens due to the incorporation of the glass modifiers Pb²⁺ and Al³⁺, the large molar refraction from heavy metal ions Pb²⁺, and the enhanced hyper-polarization from PbO doped into the core of the made fiber.     

超临界CO2萃取薰衣草的挥发性组分

1.1样品来源及制备薰衣草：购于新疆远馨香料开发公司。超临界CO2萃取：薰衣草经农用粉碎机粉碎后,用自制的0．5L超临界装置进行萃取(萃取压力：10MPa,萃取温度：321K,萃取时间：120min),得到橙色透明油状物,得率约为2．0％～2．5％,水汽蒸馏：薰衣草粉碎后,经共水蒸馏同时用油水分离器分离精油,3h后收集精油并用无水硫酸钠干燥,得淡黄色油状物,得率约为0．8％～1．0％。     

Surface activity and spreading ability of new trisiloxane-tailed dicephalic surfactants

A family of trisiloxane-tailed dicephalic surfactants was synthesized. The structures of intermediates and products were confirmed by infrared spectroscopy and ¹H nuclear magnetic resonance spectroscopy. Surface activity and spreading ability of the surfactants were also investigated. The results showed that the prepared surfactants exhibited excellent spreading ability and high surface activity by reducing the equilibrium surface tension of water to a minimum value about 20 mN m^?1.     

Inexact Alternating-Direction-Based Contraction Methods for Separable Linearly Constrained Convex Optimization

Alternating direction method of multipliers has been well studied in the context of linearly constrained convex optimization. In the last few years, we have witnessed a number of novel applications arising from image processing, compressive sensing and statistics, etc., where the approach is surprisingly efficient. In the early applications, the objective function of the linearly constrained convex optimization problem is separable into two parts. Recently, the alternating direction method of multipliers has been extended to the case where the number of the separable parts in the objective function is finite. However, in each iteration, the subproblems are required to be solved exactly. In this paper, by introducing some reasonable inexactness criteria, we propose two inexact alternating-direction-based contraction methods, which substantially broaden the applicable scope of the approach. The convergence and complexity results for both methods are derived in the framework of variational inequalities.     

Aggregation Behavior of Trisiloxane-Tailed Surface Active Ionic Liquids in Aqueous Solution: Coarse-Grained Molecular Dynamics Study

The aggregation behaviors of two trisiloxane-tailed surface active ionic liquids in water have been investigated by coarse-grained (CG) molecular dynamics simulation on the basis of MARTINI force field. The new CG model is developed from the optimized molecule computed by using density functional theory. Direct comparison of angles and bonds obtained from all-atom (AA) simulations with those calculated from the CG model has been conducted to validate the latter model. Excellent agreement between AA and CG demonstrates that the potential of the new CG model can represent the complex system well. The long time CG simulation has been performed to understand the formation process of micelles when dissolving ionic liquids in water. Vesicles were observed at the final stage of the simulation and their partially truncated views and density profiles were obtained to describe the structure in detail.     

Switchable erbium-doped fiber ring laser based on Sagnac loop mirror incorporating few-mode high birefringence fiber

Without the need of any other additional filtering device, a triple-wavelength switchable erbium-doped fiber ring laser based on Sagnac loop mirror incorporating a piece of few-mode high birefringence fiber is newly proposed and experimentally demonstrated. Three potential lasing wavelengths at about 2.0 nm interval with the side mode suppression ratio higher than 40 dB can be switched mainly by adjusting a polarization controller next to the few-mode high birefringence fiber in the Sagnac loop. In addition to the stable single-line lasing operation, simultaneous dual- and triple-line oscillations are also highly stable at room temperature with suppressing the intrinsic homogeneous gain broadening of the erbium-doped fiber.