Application and recovery of ionic liquids in the preparative separation of four flavonoids from Rhodiola rosea by on‐line three‐dimensional liquid chromatography

A novel on‐line three‐dimensional liquid chromatography method was developed to separate four main flavonoids from Rhodiola rosea. Ethyl acetate/0.5 mol/L ionic liquid 1‐butyl‐3‐methylimidazolium chloride aqueous solution was selected as the solvent system. In the first‐dimension separation, the target flavonoids were entrapped and subsequently desorbed into the second‐dimension high‐speed countercurrent chromatographic column for separation. In the third‐dimension chromatography, the residual ionic liquid in the four separated flavonoids was removed and the used ionic liquid was recovered. As a result, 35.1 mg of compound 1 , 20.4 mg of compound 2 , 8.5 mg of compound 3, and 10.6 mg of compound 4 were obtained from 1.53 g R. rosea extract. They were identified as rhodiosin, rhodionin, herbacetin, and kaempferol, respectively. The recovery of ionic liquid reached 99.1% of the initial amount. The results showed that this method is a powerful technology for the separation of R. rosea flavonoids and that the ionic‐liquid‐based solvent system has advantages over traditional solvent systems in renewable and environmentally friendly properties.     

阶跃掺杂Er∶Al2O3光波导放大器增益特性数值模拟

构建了纵向阶跃非均匀掺杂的掺铒Al2O3光波导放大器理论模型,利用有限元法、速率方程和传输方程,数值模拟了放大器的净增益特性.计算结果表明:阶跃掺杂掺铒Al2O3光波导放大器提高了抽运效率,净增益和信号光输出功率比优化后的均匀掺杂光波导放大器分别提高了9.2%和90.5%,长度却缩短了16.9%.     

De Boor递推算法的误差分析

参数定义在矩形域与三角域上的De Boor递推算法在曲面造型中得到了广泛的应用，该文介绍了矩形域与三角域上的De Boor递推算法，并研究了在控制点存在扰动与计算过程存在舍入误差的情况下对曲面计算的影响．     

添加铈对锰基催化剂的织构-结构及其氧化还原性能的影响

考察了添加稀土Ce对Mn/γ-Al2O3催化剂的织构-结构、表面活性组分的分布及氧化还原性能的影响,以催化燃烧易挥发有机污染物(VOCs)苯为探针反应研究了Ce对Mn基催化剂催化性能的影响。采用传统的浸渍法制备了系列催化剂,利用粉末X射线衍射(XRD),N2吸脱附程序升温还原(TPR)等手段对催化剂进行了表征分析。结果表明,添加稀土使Mn基催化剂比表面积、孔体积减小,说明部分Ce进入孔道中,形成了更多的氧化还原活性位,并且进一步研究得知,适量Ce的添加可以促进催化剂活性位的自组装,达到理想的催化氧化性能。添加Ce后,催化剂的活性组分中高价Mn的含量明显增加,这些都有利于提高催化剂的氧化性能。活性实验结果表明,添加适量Ce优化了催化剂的织构-结构、表面活性组分及氧化还原性能,因此催化剂的活性和稳定性明显提高,其中以MnCe为1∶1时,活性最佳,280℃左右就能完全转化苯。     

Structural dependence of ultrafast third-order optical nonlinearity of Ge–Ga–Ag–S chalcogenide glasses

Ultrafast third-order optical nonlinearity of Ge–Ga–Ag–S chalcogenide glasses at the wavelength of 820 nm has been measured using femtosecond time-resolved optical Kerr (OKE) technique. The results show that Ge–Ga–Ag–S glasses have large third-order optical nonlinear susceptibility, χ⁽³⁾ and the response time is also subpicosecond, which are predominantly due to the ultrafast distortion of electron cloud surrounding the balanced positions of Ge, Ga, Ag and S atoms. What’s more, a strong dependence of χ⁽³⁾ on the composition and microstructure of these glasses was found which shows that [GeS₄] and [GaS₄] tetrahedra play an important role on the third-order optical nonlinearity. These Ge–Ga–Ag–S chalcogenide glasses would be expected as promising materials applied on all-optical switching devices.     

质子化非那吡啶在功能化复合介孔膜修饰的液/液界面上的转移反应

采用循环伏安法和差分脉冲伏安法考察了临床药物盐酸非那吡啶在功能化复合介孔膜修饰的水/1,6-二氯己烷(W/DCH)界面上的转移行为. 研究结果表明, 盐酸非那吡啶中的非那吡啶(PAP) 可在酸性条件下发生质子化形成非那吡啶阳离子(HPAP⁺)并在该界面上发生转移. 根据循环伏安曲线峰电流与扫描速率的关系以及Randles-Sev$\check{c}$ik 方程, 计算得到HPAP⁺在复合介孔膜内水相中的扩散系数为5.14×10^-8 cm²/s. 研究发现, 相对于空白膜修饰的W/DCH界面, 该复合介孔膜修饰的W/DCH界面可增强非那吡啶阳离子转移时的电流响应, 并提升非那吡啶阳离子的检测性能. 另外, 利用液/液界面电化学方法绘制了非那吡啶在功能化复合介孔膜修饰的W/DCH界面上的离子分布图, 从而得到非那吡啶在该界面上不同条件下的分布情况及其分配系数和吉布斯转移自由能.     

JRC快速测量技术

在回顾粗糙度测量方法的基础上 ,从岩石节理的具体特点出发 ,研制了轮廓曲线仪和粗糙度尺 ,为节理粗糙度系数的统计测量提拱了一种快速测量手段。     

Fluorescent probe for turn-on sensing of l-cysteine by ensemble of AuNCs and polymer protected AuNPs

A new fluorescent probe based on ensemble of gold nanoclusters (AuNCs) and polymer protected gold nanoparticles (AuNPs) for turn-on sensing of l-cysteine was designed and prepared. The AuNCs were protected by bovine serum albumin and had strong fluorescence. The polymer protected AuNPs were synthesized by a facile in situ strategy at room temperature and could quench the fluorescence of AuNCs due to the Förster resonance energy transfer. Interestingly, it has been observed that the quenched fluorescence of AuNCs was recovered by l-cysteine, which could induce the aggregation of polymer protected AuNPs by sulfur group. Then the prepared fluorescent probe was successfully used for determination of l-Cys in human urines, which would have an evolving aspect and promote the subsequent exploration.     

Immersive autostereoscopic display based on curved screen and parallax barrier

In this Letter,we present a display system based on a curved screen and parallax barrier,which provides stereo images with a horizontal field of view of 360°without wearing any eyewear,to achieve an immersive autostereoscopic effect.The display principle and characteristics of this display system are studied theoretically in detail.Three consecutive pixels on a curved screen and parallax barrier form a display unit,which can generate separate viewing zones for the left and right eyes,respectively.Simulation and experimental results show that the non-crosstalk effect can be obtained in the viewing zones,which proves the effectiveness of this display system.This study provides some new ideas for the improvement of the autostereoscopic display and to enable envisioned applications in virtual reality technology.     

CATALYSIS OF POLYSTYRENE N-HYDROXYL SULFONAMIDE FOR ESTERIFICATION OF BUTANOL WITH ACETIC ANHYDRIDE

Polystyrene N-hydroxyl sulfonamide resin l was prepared and used to catalyze the esterification of n-butanol and acetic anhydride. The mechanism of catalytic esterification proved by IR spectra of the resins was found that O-H and N-H of the N-lrydroxyl sulfonamide resin reacted with the acetic anhydride respectively to form the active intermediate polystyrene N.O-diaceyl sulfonamate which was cleaved by n-butanol to produce butyl acetate. The catalytic esterification by resin I was in good agreement with the kinetic model of “bi-bi-ping-pong“ mechanism.