Investigation of the electrochemical and electrocatalytic behavior of positively charged gold nanoparticle and L-cysteine film on an Au electrode

Positively charged gold nanoparticle (positively charged nano-Au), which was prepared, characterized by ξ-potential and transmission electron microscopy (TEM) was used in combination with l-cysteine to fabricate a modified electrode for electrocatalytic reaction of biomolecules. Compared with electrodes modified by negatively charged gold nanoparticle/l-cysteine, or l-cysteine alone, the electrode modified by the positively charged gold nanoparticle/l-cysteine exhibited excellent electrochemical behavior toward the oxidation of biomolecules such as ascorbic acid, dopamine and hydrogen peroxide. Moreover, the proposed mechanism for electrocatalytic response of positively charged gold nanoparticle was discussed. The immunosensor showed a specific to ascorbic acid in the range 5.1 × 10⁻⁷-6.7 × 10⁻⁴ M and a low detection limit of 1.5 × 10⁻⁷ M. The experimental results demonstrate that positively charged gold nanoparticle have more efficient electrocatalytic reaction than negatively charged gold nanoparticle, which opens up new approach for fabricating sensor.     

Grafting of nanoporous alumina membranes and films with organic acids

In this study, direct surface grafting of nanoporous alumina membranes and glass‐supported alumina films was carried out with three different fluorinated organic acids: trifluoroacetic acid, perfluoropentanoic acid and 2,3,4,5,6‐pentafluorobenzoic acid. Elemental surface composition and chemical environment of alumina were investigated using X‐ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Alumina surfaces grafted with fluoro‐organic acids exhibited increased hydrophobic properties compared to ungrafted surfaces when measured using goniometry and atomic force microscopy (AFM). This work describes the evidence for surface chemical modification of alumina using direct reaction with organic acids. An AFM study of the adsorption of the immunoglobulin G (IgG) molecules on the fluoro‐organic‐acid‐grafted surfaces is reported. The results show that an ordered arrangement of immunoglobulin G structures with in‐filling of pores could be achieved only on the more hydrophobic fluoro‐organic‐acid‐grafted alumina membranes. Copyright © 2007 John Wiley & Sons, Ltd.     

热分解制备CeO2-还原氧化石墨烯及其光催化性能

通过一步水热法制备了CeCO₃OH-rGO(还原氧化石墨烯),并在氩气(Ar)气氛下焙烧制备得到CeO₂-rGO复合材料。采用X射线衍射、扫描电子显微镜、X射线光电子能谱以及紫外可见漫反射光谱(UV-Vis DRS)等研究了复合材料的物相组成、微观形貌、空位缺陷和光电化学特性等。对比研究了不同GO(氧化石墨烯)负载量和NH₄HCO₃添加量下所制备材料的光催化性能,发现GO负载量为10 mg、NH₄HCO₃添加量为15 mmol的样品(CeO₂-10rGO-15)具有最窄的禁带宽度(3.17 eV),对亚甲蓝(MB)的光催化降解率达 80.66%。适宜的 rGO 负载量有利于促进 CeO₂空位缺陷的形成,也有利于光生载流子的分离,进而促进光催化性能。     

The physical properties of aqueous solution of room-temperature ionic liquids based on imidazolium: Database and evaluation

We report the systematic studies of the physical properties of systems involving imidazolium based ionic liquids and water. The measurements of density ρ, refractive index Δ_n, viscosity η, specific conductance κ and surface tension γ were made over the whole concentration range. The equivalent conductivity Λ_m was calculated. The physical properti`es of the solutions changed with the change of association between ionic liquid and water. The physical properties of the solutions also vary with the alkyl length on the cation and polarity of anion.     

4.48 nm正入射软X射线激光用Cr/C多层膜高反射镜的研制

针对4.48nm类镍钽软X射线激光及其应用实验,设计制备了工作于这一波长的近正入射多层膜高反射镜。选择Cr/C为制备4.48nm高反射多层膜的材料对,通过优化设计,确定了多层膜的周期、周期数以及两种材料的厚度比。模拟了多层膜非理想界面对高反射多层膜性能的影响。采用直流磁控溅射方法在超光滑硅基片上实现了200周期Cr/C多层膜高反射镜的制备。利用X射线衍射仪测量了多层膜结构,在德国BessyⅡ同步辐射上测量了在工作波长处多层膜反射率,测量的峰值反射率达7.5%。对衍射仪测量的掠入射反射曲线和同步辐射测量的反射率曲线分别进行拟合,得到的粗糙度和厚度比的结果相近。测试结果表明,所制备的Cr/C多层膜样品结构良好,在指定工作波长处有较高的反射峰,达到了设计要求。     

一种求解化学非平衡流动的新型解耦算法

在一种新型化学非平衡流解耦算法框架下,将WENO5M 格式用于化学非平衡流动的流场计算. 为了验证所发展算法的准确性,对多个典型算例进行了计算. 首先计算了Oran 的反射激波诱导爆轰实验,并考虑了不同化学反应机理和网格收敛性的影响,得到的计算结果与实验和其他文献给出的计算结果符合很好,并且由于采用了一种最近提出的氢氧燃烧机理,模拟得到的实验中各个事件发生的相对时间相比于与以前的计算结果与实验符合得更好. 然后计算了二维H₂/O₂/Ar 爆轰,计算得到的胞格结构与实验和其他模拟结果符合较好,并得到了详细的爆轰发展历程. 由于这种新型解耦算法的特点,仅需对现有的基于量热完全气体的可压缩流动计算程序做很小的修改,即能改造成化学反应流动计算程序,从而进一步体现了这种解耦算法的优势.      

Global well-posedness and blow-up for the hartree equation

For 2 γ min{4, n}, we consider the focusing Hartree equation iu_t+ △u +(|x|~(-γ)* |u|~2)u = 0, x ∈ R~n.(0.1)Let M [u] and E [u] denote the mass and energy, respectively, of a solution u, and Q be the ground state of-△ Q + Q =(|x|~(-γ)* |Q|~2)Q. Guo and Wang [Z. Angew. Math.Phy.,2014] established a dichotomy for scattering versus blow-up for the Cauchy problem of(0.1) if M [u]~(1-s_c)E [u]~(s_c) M [Q]~(1-s_c)E [Q]~(s_c)(s_c=(γ-2)/2). In this paper, we consider the complementary case M [u]~(1-s_c)E [u]~(s_c)≥ M [Q]~(1-s_c)E [Q]~(s_c) and obtain a criteria on blow-up and global existence for the Hartree equation(0.1).     

稀土掺杂上转换纳米粒子的表面功能化修饰及其生物应用

稀土掺杂上转换纳米粒子(RED-UCNPs)作为一种新型高效的上转换发光纳米材料,具有反斯托克斯位移大,发射光谱窄、发光寿命长、材料毒性低等优点,已成为荧光标记、光动力学治疗、生物成像和构建生物传感器等领域的研究热点。然而,目前广泛使用的溶剂热法合成的RED-UCNPs生物相容性和亲水性差,而且不具备与生物分子之间相偶联的活性基团,因此对RED-UCNPs进行表面功能化修饰就显得格外重要。本文重点综述了RED-UCNPs的表面功能化修饰的类型及其应用现状,为RED-UCNPs的进一步研究开发和应用提供思路和参考依据。     

Selective and quantitative cancer cell detection using target-directed functionalized graphene and its synergetic peroxidase-like activity

We report here a folic acid conjugated graphene-hemin composite for selective, quantitative and fast colorimetric detection of cancer cells based on the peroxidase-like activity.