MoO_3-TiO_2纳米晶体复合材料光降解糖蜜(英文)

A MoO3-TiO2 nanocrystalline composite material was prepared by a simple solgel method.The synthesized material was charac-terized by X-ray diffraction,scanning electron microscopy with an electron dispersion spectroscopy,transmission electron microscopy,and Fourier transform infrared spectroscopy.Melanoidin is a dark brown pigment found in wastewater from the sugar industry and it pollutes water.This polluted water is generally referred to as molasses and it undergoes fermentation and is solely responsible for water,soil,and air pollution.The synthesized catalytic material was found to be effective in degrading molasses under UV-visible radiation.Analysis of treated and untreated molasses was carried out by measuring its color,chemical oxygen demand,biological oxygen demand,pH,and total dissolved solid.Results from these analyses indicate the effective photodegradation of the molasses.This methodology has several advantages such as high photocatalytic activity,non-toxicity,cleanliness,and reusability of the catalytic material.     

An efficient one-pot three-component synthesis of 7-amino-2, 4-dioxo-5-aryl-1,3,4,5-tetrahydro-2 H-pyrano[2,3-d]pyrimidine-6-carbonitriles catalyzed by SnO2/SiO2 nanocomposite

Research on Chemical Intermediates - We have developed a SnO2/SiO2 catalyzed efficient and rapid protocol for the synthesis of pyrano[2,3-d]pyrimidinone derivatives by the three-component...     

ZnO-beta zeolite mediated simple and efficient method for the one-pot synthesis of quinoxaline derivatives at room temperature

A rapid and an efficient one-pot method for the synthesis of quinoxalines catalysed by ZnO-beta zeolite at room temperature is described. This environmentally benign method provides several advantages over methods that are currently employed such as a simple work-up, mild reaction conditions, good to excellent yields, and a process to recover and reuse the catalyst for several cycles with consistent activity.      

Solar neutrino results and present status

The solar neutrino capture rate measured by the Russian-American Gallium Experiment on a metallic gallium target SAGE during the time from January 1990 through December 2000 is 77.0 _{?6.2 ?3.0} ^{+6.2 +3.5} SNU, where the uncertainties are statistical and systematic, respectively. The experimental procedures and data analysis are presented.     

Numerical simulation of three-dimensional duct flows of incompressible fluids by using the stream-tube method

Numerical simulation of three-dimensional flows generally involves solving large-scale problems. In this paper we consider the stream-tube method in three-dimensional duct flows. The analysis uses the concept of stream tubes in a mapped computational domain of the physical domain where the streamlines are parallel and straight. The incompressibility equation is automatically verified and the primary unknowns of the problem are, in addition to the pressure, the transformation functions between the two domains. It is also shown that the flow may be computed by considering successive subdomains (the stream tubes). This results in a reduction of computing time and storage area. Incompressible viscous and elastic liquids involving memory-integral equations may be considered in the flow simulations. This part of the paper examines three-dimensional flows of Newtonian fluids. The method is applied to the flow in a duct involving a threefold rotational symmetry, where the discretized relevant equations are solved by using the Levenberg-Marquardt algorithm.     

Long distance electron-transfer mechanism in peptidylglycine alpha-hydroxylating monooxygenase: a perfect fitting for a water bridge

The active sites of copper enzymes have been the subject of many theoretical and experimental investigations from a number of years. Such studies have embraced topics devoted to the modeling of the first coordination sphere at the metallic cations up to the development of biomimetic, or bioinspired, catalytic systems. At least from the theoretical viewpoint, fewer efforts have been dedicated to elucidate how the two copper cations act concertedly in noncoupled dicopper enzymes such as peptidylglycine alpha-hydroxylating monooxygenase (PHM) and dopamine beta-monooxygenase (DbetaM). In these metalloenzymes, an electronic transfer is assumed between the two distant copper cations (11 A). Recent experimental results suggest that this transfer occurs through water molecules, a phenomenon which has been theoretically evidenced to be of high efficiency in the case of cytochrome b5 (Science, 2005, 310, 1311). In the present contribution dedicated to PHM, we overpass the common theoretical approaches dedicated to the electronic and geometrical structures of sites CuM or CuH restricted to their first coordination spheres and aim at directly comparing theoretical results to the experimentally measured activity of the PHM enzyme. To achieve this goal, molecular dynamics simulations were performed on wild-type and various mutants of PHM. More precisely, we provide an estimate of the electron-transfer efficiency between the CuM and CuH sites by means of such molecular dynamics simulations coupled to Marcus theory joined to the Beratan model to approximate the required coupling matrix elements. The theoretical results are compared to the kinetics measurements performed on wild and mutated PHM. The present work, the dynamic aspects of which are essential, accounts for the experimental results issued from mutagenesis. It supports the conclusion that an electronic transfer can occur between two copper(I) sites along a bridge involving a set of hydrogen and chemical bonds. Residue Gln170 is evidenced to be the keystone of this water-mediated pathway.     

First-principles molecular dynamics evaluation of thermal effects on the NMR (1)J(Li,C) spin-spin coupling

Car-Parrinello (CP) molecular dynamics were applied to sample conformations of various models of organolithium aggregates which are chosen to estimate (1)J(Li,C) NMR coupling constants. The results show that the deviations from the values computed using static (optimized) geometries are small provided no large-amplitude motions occur within the timescale of the simulations. In the case of the vinyllithium dimer, for which rotation of the vinyl chain is observed, this approach allows analysis of the various contributions to the experimentally measured constants. For the trisolvated methyllithium monomer, partial decoordination of solvating dimethyl ether is observed and results in a significant shift of (1)J(Li,C). All these results highlight that a varied physicochemical machinery is hidden behind general empirical formulas, such as the Bauer-Winchester-Schleyer rule used experimentally.