L-Tyrosine-Pd complex supported on Fe3O4 magnetic nanoparticles: A new catalyst for C–C coupling and Synthesis of sulfides

In the present work, Fe₃O₄@L-Tyrosine-Pd heterogeneous nanocatalyst was prepared by a simple and inexpensive procedure. The prepared nanocatalyst was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray Diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), inductively coupled plasma optical emission spectroscopy (ICP-OES), scanning electron microscopy (SEM), Transmission electron microscopy)TEM(, X-ray mapping, thermal gravimetric analysis (TGA), N₂ adsorption and desorption (BET) and vibrating sample magnetometer (VSM) techniques. Besides, it was employed as an efficent catalyst for C-C cross coupling and S-arylation reactions under green conditions. The optimized conditions for these reactions are described. The heterogeneous catalyst can be easily separated by applying a simple magnet and can also be reused in several consecutive runs without appreciable change in its catalytic activity.     

阳离子纤维素-十二烷基苯磺酸钠的拟聚阴离子研究

采用浊度法、 表面张力法、 zeta电位法和毛细管电泳法(CE)研究了典型的阳离子纤维素(JR400)与典型的阴离子表面活性剂十二烷基苯磺酸钠(SDBS)之间的缔合作用. 浊度法和zeta电位法实验结果表明, 在等电区附近产生的沉淀区随JR400浓度减小而变窄, 加入过量SDBS后沉淀消失, 而且发现阳离子纤维素同系物的分子量和取代度对结果的影响较小. 表面张力法实验结果显示, 该类复合体系的表面张力曲线表观上与典型“中性聚合物-阴离子表面活性剂”体系相似, 具有3个拐点(但第二拐点易被沉淀区覆盖)且SDBS与阳离子纤维素间形成缔合物. zeta电位法实验结果表明, 沉淀区前少量SDBS存在时该缔合物具有正电位, 因而维持聚阳离子特性; 沉淀区后过量SDBS存在时该缔合物具有负电位, CE分析进一步证明其为拟聚阴离子. 上述实验结果和结论对研究该类复合体系具有较大理论意义和实用价值.     

Structure and properties of flax vs. lyocell fiber-reinforced polylactide stereocomplex composites

Cellulose - A commonly used natural cellulose fiber (flax) and a regenerated cellulose fiber (Lyocell) were used at 20 wt% to reinforce polylactide stereocomplex (sc-PLA) composites. Composites...     

An aminoquinoline based fluorescent probe for sequential detection of Znic (II) and inorganic phosphate and application in living cell imaging

A novel fluorescent probe 5‐(diethylamino)‐2‐(((2‐(hydroxymethyl)quinolin‐8‐yl)imino)methyl)phenol ( QS) was synthesized by condensation reaction of 8‐aminoquinoline derivative and 4‐(diethylamino)salicylaldehyde. It was found that the probe QS was capable of high selectivity and sensitivity about specific color and fluorescence changes towards Zn²⁺ ion in EtOH‐H₂O (v/v = 4/1, 0.01 M, Tris–HCl buffer, pH = 7.30) solution. The interaction of QS with Zn²⁺ ion illustrated a “turn‐on” fluorescence response at 550 nm (λ_ex: 458 nm), moreover, after the subsequent addition of inorganic phosphate (Pi) into the solution above, a “turn‐off” fluorescence response was observed. The sensing ability of the probe QS towards Zn²⁺ was confirmed by fluorescence titration, UV–Vis titration and HRMS analysis. Besides, the intracellular sensing behavior of QS with Zn²⁺ and Pi were captured in living PC12 cells. The limit of detection (LOD) for Zn²⁺ and Pi sensing was found to be 0.03 μM and 0.08 μM, respectively.     

Synthesis of planar chiral isoquinolinone-fused ferrocenes through palladium-catalyzed C-H functionalization reaction

(S,S)-Me-BI-DIME/Pd(0)-catalyzed ennantioselective C-H functionalization of N-ferrocenyl o-bromobenzanilides has been realized,affording isoquinolinone-fused ferrocenes with up to 97% ee.The products can be transformed into planar chiral ferrocenyl monophosphines,which demonstrate their preliminary application.     

Synthesis of Dibenzothiophene‐Containing Ladder Polysilsesquioxane as a Blue Phosphorescent Host Material

A ladder polysilsesquioxanes with side chain of dibenzothiophene groups (BS‐LPSQ) was successfully synthesized. The ladder structure of BS‐LPSQ was characterized by MALDI‐TOF MS, XRD, and ¹H NMR spectroscopy. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), atomic force microscopy (AFM), and spectroscopic analyses revealed that the BS‐LPSQ has good film‐forming ability, high thermal and morphological stability, and good miscibility to the dopant iridium bis(4,6‐difluorophenyl)pyridinato‐N,C²‐picolinate (FIrpic), high triplet energy, and a wide bandgap. In addition, compared with the ringed polysiloxane BS‐PSQ phosphorescent host material reported previously, the ladder structure of BS‐LPSQ has not only a higher thermal resistance, but also could prevent molecular aggregation and effectively avoid quenching of fluorescence. Thus, the BS‐LPSQ may be used as a better host for the blue‐light‐emitting iridium complex FIrpic. The performance of the electrophosphorescent device, based on the ladder BS‐LPSQ as the active layer, is superior to that of ringed BS‐PSQ and any other polyhedral oligomeric silsesquioxane (POSS)‐based or polymer host materials.     

Testing for Correlation Coefficients in Uniform Correlation Longitudinal Mixed Effect Linear Models Based on M-estimation

In this paper, the Fisher scoring method is applied to get M-estimator (robust estimator) in the mixed effects linear model for longitudinal data. The score tests for correlation coefficients in the model with uniform correlation covariance structure based on M-estimator are also studied. Then the properties of test statistics are investigated through Monte Carlo simulations. At last, the methods and properties are illustrated by the grape sugar data example.     

A model of feedback control system on network and its stability analysis

A model of feedback control system on network is constructed. Some criterions ensuring the robust stability and global exponential stability for the model are established, by applying Lyapunov method and generalized Kirchhoff’s matrix tree theorem. These criterions have a close relation to the topology property of networks. Finally, two examples and simulations are provided to illustrate the theoretical results.     

Effect of Opacity on Solar Coronal Soft X-Ray Oxygen VIII Spectral Line

To study the effect of opacity on the solar x-ray spectral line, using the method of escape factor, we analyze the effect of opacity on the solar oxygen VIII spectral line, and we estimate the effective emission thickness of the oxygen VIII emitting region in the solar atmosphere. Results show that the opacity has a greater effect on the solar oxygen VIII spectral line, and the effective emission thickness of the oxygen VIII ion is greater than that for some ions in the solar ultraviolet spectral line. This study has important reference significance in solar plasma diagnoses in the x-ray region.     

4π聚焦系统中衍射光学元件对聚焦场多光球结构的影响

主要研究了调制入射光场的衍射光学元件(DOE)对聚焦场的影响.以贝塞尔高斯光束为例,利用Richards-Wolf矢量衍射积分理论,分析几种不同DOE结构调制的径向偏振光束的4 π聚焦场.数值模拟结果表明径向偏振光束经DOE调制后的4π聚焦,在焦平面附近形成了具有潜在应用价值的多光球结构,并且发现形成的光球的个数与DOE的环数有关,而DOE的透射函数对其影响较小,且所形成光球的个数会随着DOE结构环数的增加而增加.