Purification of phloridzin from Lithocarpus polystachyus Rehd leaves using polymeric adsorbents functionalized with glucosamine and β-cyclodextrin

A high-efficient purification method of flavonoids from Lithocarpus polystachyus Rehd leaves is reported. Two adsorbents functionalized with glucosamine (GA) and β-cyclodextrin (β-CD) were synthesized and characterized by the Fourier transform infrared (FTIR) spectra. Also, adsorption properties and purification effect of flavonoids on different adsorbents were investigated. Two typical commercial adsorbents, AB-8 and D101, were employed as the reference materials. The adsorption capacity was enhanced remarkably by the introduction of GA and β-CD groups to the adsorbents. Moreover, the isotherms were well fitted by the Freundlich model. After a one-step column chromatographic separation, the purity of phloridzin increased significantly from 14.65 % to 79.48 % for PS-CD, to 66.56 % for PS-GA, 44.68 % for D101, and to 52.84 % for AB-8. This study provides a novel alternative matrix for the purification of phloridzin from Lithocarpus polystachyus Rehd leaves extracts.     

TiO2-decorated graphene nanohybrids for fabricating an amperometric acetylcholinesterase biosensor

This work describes a highly sensitive and rapid amperometric biosensor for organophosphate compounds (OPs) based on immobilization of acetylcholinesterase (AChE) on a novel TiO(2)-decorated graphene (TiO(2)-G) nanohybrid, which was constructed by in situ growth of TiO(2) nanoparticles (NPs) on the graphene sheet. The well-dispersed TiO(2) NPs eliminated the restacking of TiO(2)-G nanohybrids. Due to the integrating of TiO(2)-G nanohybrids, the as-prepared biosensor showed high affinity to acetylthiocholine (ATCl) with a Michaelis-Menten constant (K(m)) value of 0.22 mM, and rapid inhibition time (3 min). Further, based on the inhibition of OPs on the enzymatic activity of the immobilized AChE, and using carbaryl as a model compound, the inhibition of carbaryl was proportional to its concentration ranging from 0.001 to 0.015 and 0.015 to 2 μg mL(-1) with a detection limit of 0.3 ng mL(-1) (S/N = 3). The developed biosensor exhibited a good performance for organophosphate pesticide detection, including good reproducibility and acceptable stability, which provided a new and promising tool for the analysis of enzyme inhibitors.     

High Performance Long Wavelength Superlattice Photodetectors Based on Be Doped Absorber Region

The effect of Be doping on the quantum efficiency and the dark current of InAs/GaSb long-wavelength infrared superlattice photodetectors grown by molecular-beam epitaxy on GaSb substrates are reported. A significant improvement of quantum efficiency （QE） with p-type doping is demonstrated. Our results show that Be doping level at 2.5 × 10^15 cm^3 gives the highest quantum efficiency of product 28%. We also demonstrate that the increased QE is not only resulted from the longer minority carrier diffusion length, but also the p-n junction location change. Finally, the result also shows that the sample with a doping density of 2,5 × 10^15 cm^3 has the largest D＊ as 8.68 × 10^10 cm.Hz^l/2.W^-1, which is almost five times D＊ of the non-intentionally doped one.     

Novel Route to 2-Trifluoromethylated Benzofurans

A novel route for the synthesis of a variety of 2-trifluoromethylbenzofurans is reported. By selection of solvents, the key intermediates, 2-chloro-3,3,3-trifluoropropenyl phenyl acetates, were cyclized either to give 2-trifluoromethyl-substituted benzofurans or to yield trifluoromethyl modified o-alkynylphenols. The latter intermediates could also be cyclized to give 3-iodo-2-trifluoromethyl-substituted benzofurans.     

高通量便携式荧光检测装置的研制与应用

基于一字线激光模组,设计并构建了高通量便携式荧光检测装置,因其无需传统微孔板荧光仪所要求的专业精密调节的复杂光路系统,具有结构简单、小巧轻便、成本低廉与多通道的特点。结合自行研制的图像处理软件,对96孔微孔板样品的检测与数据处理可在10 min内完成,实现了溶液的高通量定量检测。检测罗丹明B的灵敏度为(2.80±0.15)nmol/L。应用本装置检测水溶液中Hg2+,检出限为7.7μg/L;检测自来水样品中Hg2+的加标回收率为99.9%~102.4%,RSD为1.5%~2.6%;检测湖水样品中Hg2+的加标回收率为96.2%~98.9%,RSD为1.6%~2.5%。     

Biphasic recognition chiral extraction — novel way of separating pantoprazole enantiomers

This paper presents a biphasic recognition chiral extraction system developed as a new chiral separation technology for the separation of pantoprazole enantiomers, combining a hydrophilic β-CD derivative in the aqueous phase and a hydrophobic tartaric acid in the organic phase which preferentially recognise the (R)-enantiomer and (S)-enantiomer, respectively. In this study, a number of factors which influence the efficiency of the extraction were investigated including types of organic solvents, β-CD and tartaric acid esters and their concentrations, pH and temperature. As a result, enantioselectivity for pantoprazole enantiomers can be improved up to 1.42 under optimised conditions; in addition, it is clear that the combined action of β-CD and tartaric acid esters leads to formation of the biphasic chiral extraction system with a stronger separation capacity than a monophasic chiral extraction system.     

Molecular weight and monosaccharide composition of Astragalus polysaccharides

Two polysaccharides (APS-I and APS-II) were isolated from the water extract of Radix Astragali and purified through ethanol precipitation, deproteination and by ion-exchange and gel-filtration chromatography. Their molecular weight was determined using high performance liquid chromatography and gel permeation chromatography (HPLC-GPC) and their monosaccharide composition was analyzed by TLC and HPLC methods, using a refractive index detector (RID) and an NH(2) column. It was shown that APS-I consisted of arabinose and glucose and APS-II consisted of rhamnose, arabinose and glucose, in a molar ratio of 1:3.45 and 1:6.25:17.86, respectively. The molecular weights (Mw) of APS-I and APS-II were 1,699,100 Da and 1,197,600 Da, respectively.     

一种基于激光辐照热效应的薄膜参数反演方法

本文研究并建立了一种基于激光辐照热效应的薄膜参数反演方法.首先给出激光辐照薄膜产生温升问题的热传导理论模型,并利用拉普拉斯变换得到了膜层和基底温度场的解析解;然后以膜层和基底的导热系数为反演参数,基于非线性共轭梯度算法给出反演基本原理及流程,并推导得到了反演过程中灵敏度系数的解析表达式;以aluminum,silver,copper和gold四种金属薄膜为例,通过与有限元法的计算结果对比验证了温度场解析解的正确性;最后结合四种金属薄膜进行了参数反演,通过考察分析不同随机噪声等条件下的参数反演结果,验证了本文方法在薄膜参数反演精度与反演效率等方面的有效性.反演结果显示:本文方法具有较高的反演精度和效率,在迭代截止误差为10~(-7)时只需用少于20次迭代就能收敛;在测量数据中加入的随机噪声越小,反演的迭代收敛次数就越少,即使是在迭代初值与反演结果相差较大时,用包含5%随机噪声的测量数据反演也能快速收敛.本文提出的薄膜参数反演方法不仅适用于反演导热系数,也可扩展用于反演膜层反射系数或吸收率等参数,具有一定的适用性.本文方法对于激光加工或激光损伤过程中的参数反演及优化具有一定的指导意义.     

Interactions between pyridinium and Nd3+

In this paper,2D asynchronous spectra generated by using the DAOSD approach was utilized to probe interactions between Nd~(3+) and pyridinium dissolved in aqueous solution.A series of cross peaks in the resultant 2D asynchronous spectrum confirms the occurrence of intermolecular interaction between Nd~(3+)and pyridinium.However,no coordination occurs between Nd~(3+) and pyridinium.Interaction between πelectron from aromatic system and/electron from lanthanide ions account for the appearance of cross peaks in 2D asynchronous spectra.Because of the interaction,the emission spectrum of pyridinium exhibits a significant change when neodymium perchlorate was introduced into the system.     

Hydration characteristics of Ca2+ and Mg2+: a density functional theory,polarized continuum model and molecular dynamics investigation

In this work, density functional theory, Møller–Plesset second-order perturbation theory, and ab initio molecular dynamics (AIMD) were used to investigate hydrated characteristics of Mg²⁺ and Ca²⁺ as a function of coordination number in the first hydration shell (CN) and cluster size. It is generally accepted that the CNs of Mg²⁺ and Ca²⁺ are both six. Calculations show that the hydration of Mg²⁺ generally prefers six-coordinated structures, whereas the CN value of Ca²⁺ varies from 6 to 8 as the hydration proceeds. Moreover, the first hydration of Ca²⁺ is found to be more flexible than that of Mg²⁺, as indicated by the results of transition state calculations and AIMD simulations. In addition, the constraint of Mg²⁺ on the first hydration shell is obviously stronger than that of Ca²⁺, while the constraint on the inner hydration shells fades slightly faster for Mg²⁺ than Ca²⁺. It is also found that the charge transfer from central cation to water molecules is affected only by the first hydration shell for Mg²⁺, whereas by the first and second hydration shells for Ca²⁺. Based on hydration characteristics, approximatively saturated ion hydration shells for the hydration of Mg²⁺ and Ca²⁺ were proposed.