Ordered Mesoporous Carbon Functionalized with Polythionine for Electrocatalytic Application

A polythionine (PTH) functionalized ordered mesoporous carbon (OMC) material (PTH/OMC) was presented. The electrochemistry kinetic characteristics of this material are investigated and compared with pure OMC. The results showed that compared with OMC, PTH/OMC possesses a much higher electron transfer rate. For the application of this material, an electrocatalytic based NADH biosensor was constructed on glassy carbon electrode (GCE). Instead of 0.592 V on bare GCE and 0.206 V on OMC/GCE, the amperometric detection of NADH could be effectively performed on the present biosensor with operation potential be set at 0.0 V. In addition, the sensor showed good reproducibility and stability.     

Disjointness preserving C0-semigroups and local operators on ordered Banach spaces

We generalize results concerning ${\mathrm{C}}_0$-semigroups on Banach lattices to a setting of ordered Banach spaces. We prove that the generator of a disjointness preserving ${\mathrm{C}}_0$-semigroup is local. Some basic properties of local operators are also given. We investigate cases where local operators generate local ${\mathrm{C}}_0$-semigroups, by using Taylor series or Yosida approximations. As norms we consider regular norms and show that bands are closed with respect to such norms. Our proofs rely on the theory of embedding pre-Riesz spaces in vector lattices and on corresponding extensions of regular norms.     

高温水热合成具有高稳定性的有序介孔材料

高温水热合成路线作为合成具有超高稳定性的介孔材料越来越受到人们的重视.本文对高温水热合成有序介孔材料的发展过程作一个简单的综述,合成路线包括使用碳氟表面活性剂和碳氢表面活性剂作为复合模板,有机季铵盐与碳氢表面活性剂作为复合模板以及最近报道的采用碳氢表面活性剂作为单一模板来合成系列的有序介孔材料,其组成为二氧化硅、氧化钛硅以及聚合物等.     

A fast heuristic attribute reduction approach to ordered decision systems

Rough set theory has shown success in being a filter-based feature selection approach for analyzing information systems. One of its main aims is to search for a feature subset called a reduct, which preserves the classification ability of the original system. In this paper, we consider ordered decision systems, where the preference order, a fundamental concept in dominance-based rough set approach, plays a critical role. In recent literature, based on the greedy hill climbing method, many heuristic attribute reduction algorithms are proposed by utilizing significance measures of attributes, and they are extended to deal with ordered decision systems. Unfortunately, they are often time-consuming, especially when applied to deal with large scale data sets with high dimensions. To reduce the complexity, a novel accelerator is introduced in heuristic algorithms from the perspectives of objects and criteria. Based on the new accelerator, the number of objects and the dimension of criteria are lessened thus making the accelerated algorithms faster than their original counterparts while maintaining the same reducts. Experimental analysis shows the validity and efficiency of the proposed methods.     

Polymer-templated organosilicas with hexagonally ordered mesopores: the effect of organosilane addition at different synthesis stages

Two series of ordered mesoporous organosilica (OMO) SBA-15 materials with surface and bridging groups were fabricated by varying the organic precursor addition at different synthesis stages. The consequence of the delayed introduction of organic precursor on the structural and adsorption properties of the resulting OMOs was investigated. The OMOs studied were synthesized via co-condensation of tetraethyl orthosilicate (TEOS) and ureidopropyltrimethoxysilane (UPS) as well as TEOS and bis(triethoxysilylpropyl) disulfide (BTDS) in the presence of poly(ethylene oxide)-poly(propylene oxide)- poly(ethylene oxide) triblock copolymer Pluronic P123 (EO₂₀PO₇₀EO₂₀). The aforementioned OMOs were characterized by nitrogen adsorption-desorption isotherms at −196 °C and powder X-ray diffraction (XRD). Nitrogen adsorption isotherms were used to estimate the pore volume, mesopore diameter and the BET specific surface area, whereas the XRD data provided information about structural ordering and unit cell of the samples studied. Ryan Felix, undergraduate student from Oberlin College (Oberlin, OH, USA) participating in the NSF-REU program during Summer 2006.     

双槽法电沉积Cu/Ni多层纳米线有序阵列

以多孔阳极氧化铝（AAO）为模板，采用双槽法电沉积工艺制得高度有序的Cu/Ni多层纳米线阵列。利用扫描电镜（SEM）和透射电镜（TEM）对Cu/Ni多层纳米线进行了表征，观察到纳米线表面平滑，多层结构清晰，各子层厚度均匀，直径约为 100 nm，与AAO模板孔径基本一致。由选区电子衍射（SAED）照片可知，多层纳米线中Cu层和Ni层均为单晶结构。振动样品磁强计（VSM）测试结果表明，Cu/Ni多层纳米线阵列具有明显的垂直磁各向异性，外加磁场垂直和平行于AAO模板表面时，磁滞回线的矩形比分别为 0.701 和 0.101 ，矫顽力分别为 589 Oe和 202 Oe。通过控制铝阳极氧化工艺及电沉积时间，可获得不同直径、不同子层厚度的Cu/Ni多层纳米线阵列。     

Metal deposits on well-ordered oxide films

Metal oxide interfaces, metal coatings or dispersed metals on oxide supports play an important part in many technological areas. Nevertheless, there is still a lack of fundamental knowledge about the essential properties of thin metal films and small metal particles on oxide supports, although a deeper understanding could help to improve the electronic, mechanical or catalytic performance of such systems. In the past, a number of different approaches have been proposed and explored aiming at the preparation of suitable model systems. In this review, we discuss the possibility to use thin, well-ordered oxide films as supports for the study of deposited metal particles. This approach offers the advantage to permit the unrestricted application of all experimental methods, which rely on a good electrical or thermal conductivity of the sample, like PES, LEED, STM or TDS. With the help of several examples taken from our own work on a thin alumina film, we show that it is feasible to characterise such systems on a microscopic level with respect to all relevant structural, electronic and adsorption properties. In this way, correlations between these features can be established helping to understand the particular chemistry and physics of small metal aggregates.     

Experiments on individual alumina-supported adatoms and clusters

To contribute to an understanding of growth conditions and electronic properties of metal clusters on technologically relevant oxides we have examined the mobility of individual, alumina-supported Pt-adatoms and the optical properties of single supported Ag-clusters. Using field-ion microscopy (FIM) we have prepared and imaged an individual Pt-adatom at approximately 40 K, both on the apex plane of a [1 1 0]-oriented NiAl tip and on a thin alumina film, grown on the same NiAl specimen by oxidation. On the alumina film, the onset temperature for Pt surface diffusion approaches 100 K being distinctively lower than the value 165 K measured on NiAl(1 1 0). Employing the tip of a scanning tunneling microscope (STM) as a local electron source, photon emission from individual, alumina-supported Ag-clusters was spectroscopically analyzed. The occurrence of a distinct emission line is explained by the decay of a collective electron oscillation (Mie-plasmon resonance). For decreasing Ag-cluster diameter, the emission lines (i) shift to higher energies and (ii) their widths increase. To explain these observations, we discuss (i) the reduced screening of the plasmon oscillation due to the Ag 4d electrons and (ii) an enhanced electron surface scattering rate in small clusters.     

适合无限维实零点定理的序域之结构II

在本文的第二部分中,我们研究了适合无限维实零点定理的序域的结构。通过嵌入,我们证明了,一个序域适合无限维实零点定理,当且仅当它的实闭包同构于域Ｒ｛Γ｝的某个具有无限维逼近性质的子域。这里Γ是一个无裂缝的可除序群,Ｒ｛Γ｝是指数在Γ中,系数为实数的形式幂级数域。