Pb(Ⅱ)与8-羟基喹啉沉淀反应及其分析应用

研究了在乙酸盐络合保护作用下,8-羟基喹啉与Pb(Ⅱ)沉淀反应条件,测得了8-羟基喹啉铅螯合物的红外光谱图及差热分析数据,结果表明,8-羟基喹啉铅螫合物适合于重量分析,应用于巴氏合金中高含量铅的分析测定,获得了满意的结果。     

Copper Nanoparticles on Graphene Support: An Efficient Photocatalyst for Coupling of Nitroaromatics in Visible Light

Copper is a low‐cost plasmonic metal. Efficient photocatalysts of copper nanoparticles on graphene support are successfully developed for controllably catalyzing the coupling reactions of aromatic nitro compounds to the corresponding azoxy or azo compounds under visible‐light irradiation. The coupling of nitrobenzene produces azoxybenzene with a yield of 90 % at 60 °C, but azobenzene with a yield of 96 % at 90 °C. When irradiated with natural sunlight (mean light intensity of 0.044 W cm⁻²) at about 35 °C, 70 % of the nitrobenzene is converted and 57 % of the product is azobenzene. The electrons of the copper nanoparticles gain the energy of the incident light through a localized surface plasmon resonance effect and photoexcitation of the bound electrons. The excited energetic electrons at the surface of the copper nanoparticles facilitate the cleavage of the N O bonds in the aromatic nitro compounds. Hence, the catalyzed coupling reaction can proceed under light irradiation and moderate conditions. This study provides a green photocatalytic route for the production of azo compounds and highlights a potential application for graphene.     

EXPERIMENTAL INVESTIGATION AND COMPUTER SIMULATION ON DYNAMIC BUCKLING BEHAVIOR OF LIQUID-FILLED CYLINDRICAL SHELLS UNDER AXIAL IMPACT

This article reports an experimental investigation on the axial impact buckling of thin metallic cylindrical shells fully filled with water. Low velocity impact tests are carried out by DHR-9401 drop hammer rig. The whole process of dynamic buckling is simulated using LS-DYNA computer code. The consistency between experimental observation and numerical simulation is quite satisfactory. The investigation indicates that quite high internal hydrodynamic pressure occurs inside the shell during the impact process. Under the combined action of the high internal pressure and axial compression plastic buckling occurs easily in the thin-walled shells and buckling modes take on regular and axisymmetric wrinkles. This project is supported by the National Natural Science Foundation of China(19672039) and the Shanxi Foundation for Returned Scholars from Abroad.     

改性钆/硼/聚乙烯纳米复合材料的制备及对中子和伽马射线的屏蔽性能

采用偶联剂γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH570)对纳米氧化钆(nanoGd₂O₃)表面进行包覆改性, 通过热压成型法制备了一种新型的改性纳米氧化钆/碳化硼/高密度聚乙烯(M-nanoGd₂O₃/B₄C/HDPE)复合材料. 傅里叶变换红外光谱(FTIR)、 扫描电子显微镜(SEM)和X射线能谱(EDS)分析结果表明, nanoGd₂O₃成功被偶联剂改性, 且改性nanoGd₂O₃在聚乙烯基体内的界面相容性和分散性显著提高. 热重分析(TGA)、 差示扫描量热分析(DSC)和力学拉伸实验表明, 改性nanoGd₂O₃的引入增强了复合材料的热稳定性, 提高了复合材料的拉伸强度、 杨氏模量和断裂伸长率. 对复合材料的中子和伽马射线屏蔽性能进行了实验测试和蒙特卡罗模拟计算, 研究了nanoGd₂O₃改性、 材料形状和材料厚度对屏蔽性能的影响. 结果表明, 界面相容性和分散性优良的nanoGd₂O₃能够有效提高中子及伽马射线屏蔽率. 方形M-nanoGd₂O₃/B₄C/HDPE材料在厚度为11.7 cm时中子屏蔽率达到90%, 在厚度为13.5 cm时伽马射线屏蔽率达到70%.     

In situ synchrotron X‐ray diffraction analysis of deformation behaviour in Ti–Ni‐based thin films

Deformation mechanisms of as‐deposited and post‐annealed Ti_50.2Ni_49.6, Ti_50.3Ni_46.2Cu_3.5 and Ti_48.5Ni_40.8Cu_7.5 thin films were investigated using the in situ synchrotron X‐ray diffraction technique. Results showed that initial crystalline phases determined the deformation mechanisms of all the films during tensile loading. For the films dominated by monoclinic martensites (B19′), tensile stress induced the detwinning of 〈011〉 type‐II twins and resulted in the preferred orientations of (002)_B19′ parallel to the loading direction (∥ LD) and (020)_B19′ perpendicular to the LD (⊥ LD). For the films dominated by austenite (B2), the austenite directly transformed into martensitic variants (B19′) with preferred orientations of (002)_B19′ ∥ LD and (020)_B19′ ⊥ LD. For the Ti_50.3Ni_46.2Cu_3.5 and Ti_48.1Ni_40.8Cu_7.5 films, martensitic transformation temperatures decreased apparently after post‐annealing because of the large thermal stress generated in the films due to the large differences in thermal expansion coefficients between the film and substrate.     

UV‐Triggered Surface‐Initiated Polymerization from Colorless Green Tea Polyphenol‐Coated Surfaces

A facile and versatile approach to constructing colorless surface coatings based on green tea polyphenols is reported, which can further act as a photoinitiating layer to initiate radical polymerization. These colorless green tea polyphenol coatings are capable of successfully photografting polymer brushes, and the resulting polymer brush patterns show spatial shape adjustability by masked UV irradiation. Both surface modifications and photografted polymer brushes do not alter the original color of the substrates. This method could be promising for the development of surface modifications.

     

An Ultra-stable Eu3+ Doped Yttrium Coordination Polymer with Dual-function Sensing for Cr(Ⅵ)and Fe(Ⅲ)Ions in Aqueous Solution

The exploration of a dual-functional sensor is the key to effectively detect the Cr(Ⅵ)and Fe(Ⅲ)cations in water,which is important to human health and environme...     

A facile route for regioselective conjugation of organo-soluble polymers onto chitosan

A facile route is described for the regioselective conjugation of organo-soluble polymers onto chitosan under very mild conditions, using SCC as intermediates. SCC could be prepared simply by mixing chitosan acidic aqueous solution with SDS. PEG or PCL were then grafted to SCC using the NHS/DCC coupling method. In addition, the polymers were found to be linked to chitosan through the hydroxyl groups of chitosan when stoichiometric SCC was used as a precursor. SDS could be removed simply by either precipitating the solution of SCC-graft-polymer in DMSO into Tris aqueous solution or dialyzing against Tris solution.     

LC Method for Analysis of Three Flavonols in Rat Plasma and Urine after Oral Administration of Polygonum aviculare Extract

A high-performance liquid chromatographic method has been developed for the simultaneous analysis of the flavonols myricitrin (1), avicularin (2), and juglanin (3) in rat plasma and urine after oral administration of the total flavonoids from Polygonum aviculare. Samples were prepared by solid-phase extraction then separated on a C₁₈ reversed-phase column by use of a mobile-phase gradient prepared from methanol and aqueous formic acid solution. The flow rate was 1 mL min^?1. Detection was performed at 254 nm. The calibration range was 11–1,100 μg mL^?1 for both 2 and 3 in plasma; in urine the calibration ranges for 1, 2, and 3 were 32–1,600, 11–1,100, and 22–1,100 μg mL^?1, respectively. Intra-day and inter-day RSD were less than 4.33 and 3.62% for 2 and 3, respectively, in plasma, and no more than 4.03 and 2.22% for all the analytes in urine. The analytical sensitivity and selectivity of the assay enabled successful application to pharmacokinetic studies of flavonols 1–3 in rats.