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Eşfahān, Iran

The effects of acidity of electrolyte (pH) on the hysteresis behavior, the specific surface area, and nanostructure morphology of electrolytic manganese dioxides (EMDs) have been studied by using the Barrett-Joyner-Halenda (BJH) analysis, X-ray diffraction (XRD) and scanning electron microscopy (SEM) images analysis. EMD samples are electrodeposited at a variable pH (6 to 1) and many fixed pH (2, 3, 4, 5, and 6). Results indicate that pH play key roles in the characteristics of EMD. The samples obtained at low pH (2 and 3) show multi-branched morphology and represent a H4 hysteresis loop. At pH 4 and 5, a uniform and dense structure of MnO 2 is obtained without hysteresis behavior. The sample electrodeposited at pH 6 shows a regular reticulate, that its adsorption-desorption isotherm show hysteresis behavior. By electrodeposition at a variable pH, the sample shows a cauliflower-like and multi-branched form. From the viewpoint of classification of isotherm, pH strongly affects on Type of isotherm. The results show that γ-MnO 2 is as main-product of electrodeposition and α-MnO 2 and β-MnO 2 were obtained as side-product at low and high pH, respectively. © 2012 Elsevier B.V. Source

Bagherzadeh M.,Material Research School | Heydari M.,Islamic Azad University at Shahreza
Analyst | Year: 2013

Herein, graphene nanosheets (GNS) were synthesized, by a green and facile method based on reduction by glucose, and characterized. Afterwards, a carbon paste electrode (CPE) was modified with GNS by casting and drying GNS on top of the CPE (CPE/GNS). The behavior of the CPE/GNS towards dopamine (DA) and ascorbic acid (AA) was investigated by electrochemical methods and the obtained results showed that the CPE/GNS had adsorbed only DA. Based on this behavior, the DA molecules were pre-concentrated on top of the CPE/GNS, followed by stripping in DA free solution. Subsequent to experimental and instrumental optimization, a calibration curve from 2.0 × 10-6 to 1.0 × 10-3 M DA, r2 = 0.99 (±0.01), with detection limit (DL) = 8.5 × 10-7 M DA, sensitivity = 15.4 (±0.94) μA, and RSD = 6.1 was observed in the presence of 1.0 × 10-3 M AA. Finally, the performance of the CPE/GNS was successfully tested in a pharmaceutical sample. This work provides a promising strategy for DA detection in the presence of biological interferences, e.g. AA, with high sensitivity and simple characteristics. © 2013 The Royal Society of Chemistry. Source

Nasrollahzadeh M.,University of Qom | Sajadi S.M.,Kurdistan Regional Government | Rostami-Vartooni A.,University of Qom | Bagherzadeh M.,Material Research School
Journal of Colloid and Interface Science | Year: 2015

We report the green synthesis of palladium/CuO nanoparticles (Pd/CuO NPs) using Theobroma cacao L. seeds extract and their catalytic activity for the reduction of 4-nitrophenol and Heck coupling reaction under aerobic conditions. The catalyst was characterized using the powder XRD, TEM, EDS, UV-vis and FT-IR. This method has the advantages of high yields, elimination of surfactant, ligand and homogeneous catalysts, simple methodology and easy work up. The catalyst can be recovered from the reaction mixture and reused several times without any significant loss of catalytic activity. © 2015 Elsevier Inc. Source

Nasrollahzadeh M.,University of Qom | Sajadi S.M.,Soran University | Rostami-Vartooni A.,University of Qom | Bagherzadeh M.,Material Research School | Safari R.,University of Qom
Journal of Molecular Catalysis A: Chemical | Year: 2015

We report the facile synthesis of environmentally benign Cu NPs/perlite composites without employing any toxic reductants or capping agents. Renewable natural Euphorbia esula L. not only functioned as a reductant, but also served as a stabilizer for the formation of Cu NPs. Cu NPs synthesized using aqueous extract of the leaves of E. esula L. was immobilized on perlite by a very simple and inexpensive method. The structural investigation was performed using XRF, XRD, SEM, EDS, TEM, TG-DTA, BET and FT-IR. The Cu NPs/perlite shows favorable activity and separability on the catalytic reduction of 4-nitrophenol, and can be reused several times without a decrease in the catalytic activity. Their reaction rate constant was calculated according to the pseudo-first-order reaction equation. © 2015 Elsevier B.V. Source

Nassiri-Mofakham N.,Material Research School
Physica A: Statistical Mechanics and its Applications | Year: 2015

This paper concerns the magneto-fluid dynamics modeled by the stochastic flow where the turbulent term is driven by the random forcing. Magnetohydrodynamic (MHD) turbulence can be interpreted in terms of a standard map (SM), modeling perturbed Hamiltonian systems, to explain some of the features of the problem. The dynamics generated by SM, although being chaotic, are influenced by periodic islands embedded in the chaotic sea due to stickiness effect and also to the behavior of the diffusion coefficient. Anomalous diffusion exists only up to some crossover time, beyond which the diffusion is Gaussian consistent with quasi-linear predictions. The results can be applicable to systems where there exist intensive interaction between a stochastic turbulent system and waves. © 2014 Elsevier B.V. All rights reserved. Source

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