纳米晶PbTiO3负载CuO催化NO分解

A large specific surface area perovskite-type mixed oxide PbTiO₃ supported cupric oxide was synthesized as a catalyst for NO decomposition and characterized by techniques such as XPS, XRD, H₂-TPR before and after NO decomposition reactions. The catalytic properties were tested with a fix-bed micro-reactor. The results showed that the PbTiO₃ was inactive for the reactions, but 1wt % Cu/PbTiO₃ catalyst gave fairly good activities for NO decomposition at temperature as low as 473 K. Copper species were found well-dispersed but weakly interacted with the support before NO decomposition, and the NO decomposition caused significant change in the environment of the copper species, which became Cu(Ⅰ) and most probably incorporated into surface crystal lattice of the nano-sized PbTiO₃. In NO reaction, a large amount of oxygen atoms from the decomposition of NO penetrated into the nano-sized PbTiO₃ support and caused small expansion of crystal lattice. The transport of oxygen between the copper species and the catalyst support may be helpful to speed up the kinetic regeneration of active metal sites from oxygen occupancy and resulted in good catalytic performance.     

温和条件下混合碱辅助水热合成硅酸镁纳米管

在混和碱的辅助下, 以普通氢氧化镁和二氧化硅粉末为原料在温和条件下高效合成硅酸镁纳米管。采用XRD, TEM, FTIR, 氮气吸附等多种手段对产物进行了表征, 并对其合成过程进行了研究。结果表明氢氧化钠和氢氧化钾的共融液能提高反应物间的溶解性, 促进反应可以在温和条件下加快进行。250℃下合成硅酸镁纳米管, 传统水热法至少需要7 d, 混合辅助水热合成只需36 h。与传统的水热法相比, 混和碱辅助的水热法是一种温和且高效的过程。     

Construction of new generalizations of Wynn’s epsilon and rho algorithm by solving finite difference equations in the transformation order

We construct new sequence transformations based on Wynn’s epsilon and rho algorithms. The recursions of the new algorithms include the recursions of Wynn’s epsilon and rho algorithm and of Osada’s generalized rho algorithm as special cases. We demonstrate the performance of our algorithms numerically by applying them to some linearly and logarithmically convergent sequences as well as some divergent series.

     

An integrable semi-discrete equation and combinatorial numbers with their combinatorial interpretations

A Hankel type determinant solution for an integrable semi-discrete equation is presented. As an application, the relations between the solution and combinatorial numbers are discussed, which lead to new combinatorial numbers. The so-called Motzkin-like numbers are obtained, and the corresponding combinatorial interpretation is given. Additionally, it is also shown that some lattice paths have connections with the special solution.     

双酚A敏化Bi5O7I纳米片增强可见光自降解活性

以BiOIO₃为前驱体,通过高温煅烧法制备了一系列铋(Bi)基材料,并系统地研究了不同样品的物相组成、微观形貌、光学性能及光催化活性。实验结果表明,Bi₅O₇I纳米片在可见光(λ>420 nm)照射60 min后,对双酚A(BPA)的降解率可达99.3%,5次循环使用后仍能去除97%的BPA,表现出良好的光催化活性与稳定性。研究表明,BPA可以作为表面配体,与Bi₅O₇I发生表面配位,通过配体-金属电荷转移(LMCT)的光敏化机制作用实现太阳光的高效利用并促进其自降解。     

双酚A敏化Bi5O7I纳米片增强可见光自降解活性

以BiOIO₃为前驱体,通过高温煅烧法制备了一系列铋(Bi)基材料,并系统地研究了不同样品的物相组成、微观形貌、光学性能及光催化活性。实验结果表明,Bi₅O₇I纳米片在可见光(λ>420 nm)照射60 min后,对双酚A(BPA)的降解率可达99.3%,5次循环使用后仍能去除97%的BPA,表现出良好的光催化活性与稳定性。研究表明,BPA可以作为表面配体,与Bi₅O₇I发生表面配位,通过配体-金属电荷转移(LMCT)的光敏化机制作用实现太阳光的高效利用并促进其自降解。     

Selective Carbon Dioxide Capture in Antifouling Indole-based Microporous Organic Polymers

Intermolecular synergistic adsorption of indole and carbonyl groups induced by intermolecular hydrogen bonding makes microporous organic polymer(PTICBL)exhibit high CO2 uptake capacity(5.3 mmol·g^-1at 273 K)and selectivities(CO2/CH4=53,CO2/N2=107 at 273 K).In addition,we find that indole units in the PTICBL networks inhibit the attachment of bacteria(E.coil and S.aureus)on the surface of PTICBL and extend its service life in CO2 capture.     

IGAOR and multisplitting IGAOR methods for linear complementarity problems

In this paper, we propose an interval version of the generalized accelerated overrelaxation methods, which we refer to as IGAOR, for solving the linear complementarity problems, LCP (M, q), and develop a class of multisplitting IGAOR methods which can be easily implemented in parallel. In addition, in regards to the H-matrix with positive diagonal elements, we prove the convergence of these algorithms and illustrate their efficiency through our numerical results.     

A conjecture based on Somos-4 sequence and its extension

In two recent papers by Barry (2010) [29] and (2011) [30], it is conjectured that Somos-4 admits a solution expressed in terms of Hankel determinant with its elements satisfying a convolution recursion relation. In this paper, Barry’s conjecture on Somos-4 is firstly confirmed. Actually, we present a more generalized result. The proof is mainly based on new findings on properties for so-called Block–Hankel determinants. The method can also be used to prove another conjecture proposed by Michael Somos, which has been solved by Guoce Xin.     

修饰剂链长变化对核壳结构CdS纳米晶尺寸和光学性质的影响

采用液液两相法,在甲苯和水的两相体系中制备了由不同烷基链长单硫醇修饰的具有无机-有机核壳结构的CdS半导体纳米晶.使用透射电子显微镜(TEM)、X射线粉末衍射(XRD)和紫外-可见吸收光谱(UV-Vis)对样品的结构和组成进行了表征.结果表明,样品CdS半导体纳米晶是由无机纳米核及其表面化学吸附的硫醇组成的,而且壳层有机修饰剂对无机纳米核的尺寸和光学性质影响很大.进一步分析发现,层修饰剂的烷基链长和CdS纳米核的尺寸之间存在着类似抛物线的关系.这主要是由于在两相体系中,Cd纳米核的形成和成长两个阶段受到修饰剂在有机相中的迁移率以及其在纳米核表面的组装有序度两种关键因素竞争结果的控制.