The synthesis of Tempol–phenol derivatives and their protection against radical-induced damage

Stable nitroxides are potential antioxidant drugs. In this study, we have linked nitroxide (Tempol) to phenol with the aim of improving radioprotective activity. The radical scavenging activities of four Tempol–phenol conjugates were evaluated in L-02 and MCF-7 cells survival assays. A differential protection in normal cells as compared to tumor cells was confirmed. In addition, the protective effect of these compounds was demonstrated in a greater increase in peripheral WBC, ANC, AMC, and platelet counts in an in vivo rat model. It might be possible to develop them into a possible agent for radical injury.     

Ni 掺杂ZnO纳米线的电子结构与磁性

采用自旋极化密度泛函理论系统研究了Ni掺杂ZnO纳米线的电子结构、磁学和光学性质.磁学性质计算结果显示六种Ni掺杂ZnO纳米线的磁性耦合体系出现了铁磁(FM)、反铁磁(AFM)和顺磁(PM)二种不同的耦合状态.能量计算结果表明Ni原子在纳米线外表面沿[0001]方向替代Zn原子时能量最低,体系的AFM耦合相对稳定,AFM体系表现出金属性.态密度计算结果显示FM耦合在费米能级附近出现了明显的自旋极化现象,发生了强烈的Ni 3d和O 2p杂化效应,掺杂产生的磁矩主要来源于Ni 3d未成对轨道电子和部分O 2p轨道电子的贡献,FM耦合表现出半金属性.另外,光学性质计算结果显示Ni掺杂ZnO纳米线的远紫外吸收峰发生了红移现象,而380 nm附近的近紫外吸收峰发生了明显的蓝移现象,在整个紫外区都表现出了优异的发光性能.以上结果表明Ni掺杂ZnO纳米线是一种很有前途的磁光电子材料.     

Characteristics of CO2 corrosion scale formed on P110 steel in simulant solution with saturated CO2

The SEM, X‐ray diffraction (XRD), and XPS were employed to systematically characterize the component and microstructure of the corrosion scale formed on P110 steel exposed to carbon dioxide (CO₂) environment. A loose and porous microstructure in corrosion scale was observed under turbulent flow condition for 120 h at 100 °C with a carbon dioxide partial pressure of 4 MPa in which the principal component was iron carbonate (FeCO₃), whereas at 160 °C the corrosion scale was composed mainly of FeCO₃ and a little amount of FeO(OH). In addition, complex carbonate (Mg,Fe)CO₃ was produced because some Fe positions in FeCO₃ lattice were substituted by Mg. It showed that a double‐layer structure of corrosion scale was observed at 160 °C compared with the result at 100 °C. Copyright © 2008 John Wiley & Sons, Ltd.     

Synthesis of chiral dihydrofuran compounds by thiourea derivatives-catalyzed“interrupted”Feist-Bénary reaction

<正>In this study,six thiourea derivatives of cinchona alkaloids with 9-nat or 9-epi-configuration were synthesized.After characterized the structures,we adopted them to the asymmetric"interrupted"Feist-Benary(IFB) reaction ofα-haloketones with β-dicarbonyl compounds,to give optically active dihydrofurans.Various thiourea derivatives as organocatalysts were examined.The corresponding chiral hydroxyl dihydrofurans have been obtained in excellent yields and moderate ees.To the acyclic substrate,we obtained exciting and promising result.     

Pervaporation Separation and Catalysis Activity of Novel Zirconium Silicalite-1 Zeolite Membrane

Novel zirconium silicalite‐1 zeolite membrane was hydrothermally prepared on the mullite porous support at 150–185°C for 40–72 h by an "in situ" method using tetraethyl orthosilicate (TEOS), zirconium butoxide (ZBOT) and tetrapropylammonium hydroxide (TPAOH) as silica source, zirconium source and organic structure directing agent, respectively. X‐ray diffraction (XRD) patterns, fourier transformed infrared (FT‐IR) spectra, and inductively coupled plasma‐atomic emission spectrometry (ICP) of the accompanying zeolite powder confirmed that the zirconium was isomorphously incorporated into the zeolite framework. The surface chemical compositions of the obtained membrane were measured with an energy‐dispersive X‐ray spectral analyzer (EDS), and the membrane morphologies were observed by a scanning electron microscope (SEM). The results showed that the zeolite crystals growing on the support were zirconium silicalite‐1 zeolites, and the dense membrane layer was composed of the well inter‐growing zeolite crystals. The zirconium silicalite‐1 zeolite membrane, which was derived from the synthesis solution having a molar ratio of 1.00SiO₂:0.01ZrO₂:0.17TPAOH:120H₂O, showed high ethanol permselectivity with a flux of 1.01 kg/(m²·h) accompanied with a separation factor of 73 for ethanol/water (5/95, w/w) system under a pervaporation condition at 60°C. Moreover, this membrane displayed pervaporation‐aided catalysis activity for iso‐propanol oxidation with hydrogen peroxide as oxidant, and the corresponding iso‐propanol conversion was 35%.     

聚乙烯亚胺改性氧化石墨对水中Cr(Ⅵ)的吸附

通过对石墨氧化、酯化,将聚乙烯亚胺耦合接枝到氧化石墨表面,制备聚乙烯亚胺改性氧化石墨(PEI-GO)。通过FTIR、XRD、TEM、RS和XPS等对合成材料进行表征,并研究了其对水中的Cr(Ⅵ)吸附和脱附性能。表征结果表明,聚乙烯亚胺成功嫁接到氧化石墨上,其氨基含量为4.36mmol·g^-1。PEI-GO对水中Cr(Ⅵ)具有很好的吸附性能,吸附等温线符合Freundlich方程,吸附动力学可用拟二级动力学方程来描述。PEI-GO对水中Cr(Ⅵ)的吸附随pH的升高而降低。阴离子的存在降低吸附剂对Cr(Ⅵ)的吸附,不同阴离子的影响大小顺序为PO₄^3- >SO₄^2- >NO₃^- >Cl^-。XPS结果表明,PEI-GO对Cr(Ⅵ)的去除是吸附-化学还原耦合作用的结果。经4次脱附再生循环,PEI-GO对Cr(VI)仍具有较高吸附量,表明该吸附剂再生性好,可循环使用。     

固相萃取-超高效液相色谱-电喷雾串联质谱法同时测定食品中13种抗氧化剂

建立了固相萃取-超高效液相色谱-电喷雾串联三重四极杆质谱联用技术分析食品中13种抗氧化剂的方法。样品经固相萃取后,以Agilent Eclipse Plus C18色谱柱为分离柱,以乙腈和水为流动相进行梯度洗脱,电喷雾离子源电离、正负离子多反应监测模式质谱进行定性和定量分析。13种抗氧化剂质量浓度在0.1~5 mg/L范围内线性良好,相关系数为0.9936~0.9993,方法的定量限为0.5 mg/kg;在不同种类食品中3个添加水平的平均回收率为80.5%~118.8%,相对标准偏差为0.8%~9.1%。应用本方法检测食品中的抗氧化剂,分别检测出4种食品中含有抗氧化剂。     

包含平面五配位和平面四配位碳化合物的结构和稳定性

在B3LYP/6-311+G**水平上,研究了包含平面五配位碳(ppC)和平面四配位碳(ptC)的化合物CB5C2H2(C3B2)nC2H2CB5(n=1-5)的结构、能隙、IR光谱、电子光谱、Wiberg键指数以及芳香性.计算结果表明,这五种化合物的能量最低结构均位于势能面的极小值点,HOMO-LUMO能隙在0.5到1.2eV之间,第一电子的激发能在1780到2910nm之间,且与分子尺寸呈现非单调变化趋势.Wiberg键指数和键长表明这五种化合物的能量最低结构均包含平面五配位和平面四配位碳.C3B2单元和右侧CB5单元中三元环中心的核独立化学位移(NICS(0))值均为负值,而左侧CB5单元中的三元环中心的NICS(0)值中两个为正值,另两个为负值,NICS(1)值与NICS(0)值也一致,因此电子的局域离域对结构的稳定是很重要的.     

Stability of a two-dimensional airfoil with time-delayed feedback control

This paper presents a systematic study on aeroelastic stability of a two-dimensional airfoil with a single or multiple time delays in the feedback control loops. Firstly, the delay-independent stability region of the aeroelastic system with a single time delay is determined on the basis of the generalized Sturm criterion for polynomials. Then, the stability switches with variations in time delay are analyzed when the system parameters fall out of the delay-independent stability region. Flutter boundaries of the controlled aeroelastic system as time delay varies are predicted in a continuous way by the predictor-corrector technique. Finally, two methods, the polynomial eigenvalue method and the infinitesimal generator method, are introduced to investigate the stability of the controlled aeroelastic system with multiple time delays. Numerical simulations are made to demonstrate the effectiveness of all the above approaches.