以淀粉溶液为催化剂锅三组分法合成四氢苯并[b]吡喃和3,4-二氢吡喃并[c]苯并吡喃衍生物简

Tetrahydrobenzo[b]pyran and 3,4-dihydropyrano[c]chromene derivatives were synthesized via a one-pot three-component condensation of aromatic aldehydes with malononitrile and dimedone or 4-hydroxycoumarin in excellent yields in the presence of starch solution as a highly efficient homogenous catalyst. The use of a nontoxic and biodegradable catalyst, simple work-up procedure, and short reaction time are advantages of this method.     

Influence of copper cations on the magnetic properties of NiCuZn ferrite nanoparticles

Ni_0.6−xCu_xZn_0.4Fe₂O₄ (x=0-0.5) ferrite nanoparticles were prepared, employing a reverse micelle process. X-ray diffraction and transmission electron microscopy evaluations demonstrated that single phase spinel ferrites with narrow size distribution were obtained. Vibrating sample magnetometer was employed to probe the magnetic properties of the samples. It was found that with an increase in copper content, the saturation magnetization decreases. Magnetic dynamics of the samples was studied by measuring a.c. magnetic susceptibility versus temperature at different frequencies. The phenomenological Néel-Brown and Vogel-Fulcher models were employed to distinguish between the interacting or non-interacting systems. The system exhibits that there is strong interaction among fine particles.     

Ab-Initio Molecular Dynamics Simulation of Condensed-Phase Reactivity: The Electrolysis of Amino Acids and Peptides

Electrolysis is a potential candidate for a quick method of wastewater cleansing. However, it is necessary to know what compounds might be formed from bioorganic matter. We want to know if there are toxic intermediates and if it is possible to influence the product formation by the variation in initial conditions. In the present study, we use Car–Parrinello molecular dynamics to simulate the fastest reaction steps under such circumstances. We investigate the behavior of amino acids and peptides under anodic conditions. Such highly reactive situations lead to chemical reactions within picoseconds, and we can model the reaction mechanisms in full detail. The role of the electric current is to discharge charged species and, hence, to produce radicals from ions. This leads to ultra-fast radical reactions in a bulk environment, which can also be seen as redox reactions as the oxidation states change. In the case of amino acids, the educts can be zwitterionic, so we also observe complex acid–base chemistry. Hence, we obtain the full spectrum of condensed-phase chemistry.     

Computational analysis of heat transfer in a PEM fuel cell with metal foam as a flow field

Journal of Thermal Analysis and Calorimetry - Thermal management of proton-exchange membrane (PEM) fuel cell has an important effect on the overall cell performance. In this paper, metal foams as...     

Rheological and transport properties of sulfonated polyacrylamide hydrogels for water shutoff in porous media

In this research, an optimal hydrogel, based on sulfonated polyacrylamide, was synthesized by statistical design of experiments using central composite method. This new hydrogel composed of sulfonated polyacrylamide (AN125VLM) and chromium triacetate as copolymer and crosslinker, respectively. The bottle and rheological tests were conducted to investigate the gelation time, thermal stability, gel strength and also ultimate elastic modulus, complex modulus, and yield stress. It was found that copolymer concentration had the main effect in both rheological and transport properties of hydrogels. The sample prepared at optimum condition, i.e. copolymer concentration of 26,340 ppm and crosslinker/copolymer ratio of 0.12, had an ultimate elastic modulus of 29.9 kPa, yield stress of 800 Pa, and complex modulus of 32 kPa. A coreflooding test through fracture was carried out to examine the optimum gel performance in a porous media. A value of 483 for the residual resistance factor ratio of water to oil confirmed the high ability of the hydrogel in reducing the relative permeability of water to oil in fractured media. Copyright © 2014 John Wiley & Sons, Ltd.     

Norm-Controlled Inversion in Weighted Convolution Algebras

Journal of Fourier Analysis and Applications - Let G be a discrete group, let $$p\ge 1$$, and let $$\omega $$ be a weight on G. Using the approach from Gröchenig and Klotz (J Lond Math Soc (2)...     

Enhancing water splitting via weakening H2 and O2 adsorption on NiCo-LDH@CdS due to interstitial nitrogen doping: A close look at the mechanism of electron transfer

This paper is a report on the development of a convenient approach to fabricating a very efficient hybrid photoelectrocatalyst for water splitting.This photoele...     

Substituted 5-Antipyrinylazo-4-phenyl-2-aminothiazoles as Disperse Dyes for Dyeing Polyester Fabrics

A series of some new substituted 5-antipyrinylazo-4-phenyl-2-aminothiazole disperse dyes was synthesized by diazocoupling of 4-antipyrinyldiazonium chloride with aminothiazole derivatives. The synthesized dyes were characterized by UV-Vis absorption, IR, ¹H NMR, and MS spectroscopy. The dyes gave orange to reddish-violet shades with very good depth and levelness when applied to polyester fabrics as disperse dyes and their fastness properties were evaluated on polyester fibers. Also the position of color in CIELAB coordinates (L^*, a^*, b^*, H^*, and C^*) was assessed.     

Flow injection determination of formaldehyde by its catalytic effect on the oxidation of sulfonazo III by bromate with spectrophotometric detection.

A simple and sensitive flow injection method with spectrophotometric detection was developed for the determination of formaldehyde. The method is based on the catalytic effect of formaldehyde on the oxidation of sulfonazo III with bromate in acidic media. The decrease in absorbance of the reaction mixture was measured at 566 nm. The calibration graph was linear in the range of 0.005 to 2.80 microg ml(-1) formaldehyde at a rate of 38 +/- 4 samples h(-1). The limit of detection was 4 ng ml(-1). The relative standard deviations for ten replicate measurements of 0.20, 0.50 and 1.00 microg ml(-1) formaldehyde were 1.3, 0.8 and 0.7%, respectively. The method was applied to the determination of formaldehyde in river water, shampoo and melamine-formaldehyde resin.     

Electron acceleration below quarter-critical density in CO2 laser-produced plasmas

We present detailed characteristics of heated electron distributions in long-scale-length underdense plasmas irradiated by intense nanosecond CO₂ laser radiation. Below n_c/4, the heated electron distributions are consistent with heating by Raman instability.