Microwave-assisted silica-supported aluminum chloride-catalyzed Friedel-Crafts alkylation

Microwave irradiation is a popular method in organic synthesis to achieve high yields in shorter reaction times. This decreases total ‘man-hours’ in a synthetic setting. Another technique used in organic chemistry to decrease manual manipulations, is solid support reagents. The benefits of this approach is that upon completion of a reaction, a simple filtration can be performed which expedites the work-up and also produces less organic waste. Friedel-Crafts alkylation has been explored using microwave chemistry as well as with solid-supported reagents. In comparison with traditional heating, as well as with AlCl₃, superior yields were observed with silica-gel bound aluminum chloride (Si-AlCl_x) when microwave irradiated for only 5 min.     

污泥内层和外层胞外聚合物的三维荧光光谱特性研究

运用三维荧光光谱技术对污泥LB-EPS和TB-EPS的荧光特性进行了研究.实验结果表明,在污泥LB-EPS和TB-EPS中都有三个明显的荧光峰,分别为Peak B(λex/λem=270～280 nm/345～360 nm),Peak C(λex/λem=330～340 nm/410～430 am)和Peak D(λex/λem=390 nm/450～470 nm).其中Peak B为类蛋白荧光(Protein-like)、Peak C为可见区类富里酸荧光(Visible fulvic-like)、Peak D为类腐殖酸荧光(Humic-like).从各荧光峰的荧光强度来分析,LB-EPS和TB-EPS中的主要成分都为类蛋白,然后依次为富里酸和腐殖酸.浓度和pH值对污泥LB-EPS和TB-EPS的三维荧光特性都有很大的影响,但影响程度略有区别,表明作为外层的胞外聚合物,LB-EPS表现出与TB-EPS不全相同的化学结构.     

On the Upper Bound of Second Eigenvalues for Uniformly Elliptic Operators of any Orders

Abstract Let Ω R~m(m≥1)be a bounded domain with piecewise smooth boundary Ω.Let t and r bepositive integers with t>r+1. We consider the eigenvalue problems(1.1)and(12),and obtain Theorem 1and Theorem 2, which generalize the results in[1,2.5].     

Global Error Bound for the Generalized Linear Complementarity Problem over a Polyhedral Cone

In this paper, the global error bound estimation for the generalized linear complementarity problem over a polyhedral cone (GLCP) is considered. To obtain a global error bound for the GLCP, we first develop some equivalent reformulations of the problem under milder conditions and then characterize the solution set of the GLCP. Based on this, an easily computable global error bound for the GLCP is established. The results obtained in this paper can be taken as an extension of the existing global error bound for the classical linear complementarity problems. This work was supported by the Research Grant Council of Hong Kong, a Chair Professor Fund of The Hong Kong Polytechnic University, the Natural Science Foundation of China (Grant No. 10771120) and the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry.     

Monoclonal Antibody-Based Immunolocalization of Bound Triazine Residues in Two Aquatic Macrophytes (Elodea Canadensis and Myriophyllum Spicatum)

Abstract

Immunohistochemical localization offers a fast and reliable method of obtaining information about the distribution of bound pesticide residues in plants. In the present study aquatic macrophytes (Elodea canadensis, Myriophyllum spicatum) were grown in laboratory model ecosystems spiked with 50 μg/l atrazine. To label cryosections, monoclonal antibodies from cell culture supernatants and ascites fluid with differing specificities for s-triazines were used in combination with the fluorescent dye Phycoerythrin and biotin-streptavidin amplification. The best results were observed with antibodies gained from mice immunized with an ametryn sulfoxide-BSA conjugate, regardless of the method employed for antibody production. The consequences with respect to herbicide metabolism and binding are discussed.     

Thermal behavior of short-range-order in quenched Cu-12 at% Mn assessed by DSC

Summary The ordering behavior of quenched Cu-12 at% Mn was investigated by differential scanning calorimetry (DSC) under increasing temperature conditions. The ordering process can be better explained in terms of a homogeneous short-range-order (SRO) rather than a disperse-short-range-order (DSRO) model as for concentrated Cu-γMn solid solutions. At the employed high quench rates ordering is established in one stage here termed stage 1, assisted by excess vacancies. This stage obeys a first order kinetics law, being the effective activation energy consistent with a weighed average sum of the activation energy for migration of free and bound vacancies. An estimated solute-vacancy binding energy of 15 kJ mol^-1 seems quite reasonable for this alloy together with the assessed activation energy for complex migration of 92.6 kJ mol^-1. By adopting a first SRO order parameter based in quasi-chemical theory in pair approximation and using boundary values calculated from displayed features of DSC traces, the retained degree of quenched-in order at room temperature was calculated. This procedure also enabled to estimate an ordering energy of -2.7 kJ mol^-1. The effect of quenching temperature demonstrate that for smaller vacancy sink densities, the retained degree of order at room temperature goes through a minimum.     

Effects of DNA secondary structure on oligonucleotide probe binding efficiency

Secondary structure motifs in nucleic acid probes generally impair intended hybridization reactions and so efforts to predict and avoid such structures are commonly employed in probe design schemes. Another key facet of probe design that has received much less attention, however, is that secondary structure at targeted probe binding site regions may also impair hybridization. Thus, evaluation of both probe and target site secondary structures together should improve hybridization prediction and design effectiveness. Several challenges confound this goal, including imperfect empirical rules and parameters underlying predictions and the fact that folding algorithms scale poorly with respect to sequence length. Here, we attempt to quantify the consequences of target site structure on predicted hybridization using sequences sampled from the human genome. We also provide a methodology for choosing a reasonable “window size” around target sites that is as small as possible without compromising folding algorithm prediction accuracy.     

Eigenvalues Estimate for the Neumann Problem of a Bounded Domain

In this note, we investigate upper bounds of the Neumann eigenvalue problem for the Laplacian of a domain Ω in a given complete (not compact a priori) Riemannian manifold (M,g). For this, we use test functions for the Rayleigh quotient subordinated to a family of open sets constructed in a general metric way, interesting for itself. As applications, we prove that if the Ricci curvature of (M,g) is bounded below Ric  ^g ≥−(n−1)a ², a≥0, then there exist constants A _n >0,B _n >0 only depending on the dimension, such that