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Response surface analysis of photocatalytic degradation of methyl tert-butyl ether by core/shell Fe3O4/ZnO nanoparticles
, Article Journal of Environmental Health Science and Engineering ; Vol. 12, issue. 1 , 2014 ; Rostami, M. H ; Alizadeh, M ; Alizadehbirjandi, A ; Nakhli, S. A. A ; Aminzadeh, R ; Sharif University of Technology
Abstract
The degradation of methyl tert-butyl ether (MTBE) was investigated in the aqueous solution of coated ZnO onto magnetite nanoparticale based on an advanced photocatalytic oxidation process. The photocatalysts were synthesized by coating of ZnO onto magnetite using precipitation method. The sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibration sample magnetometer (VSM). Besides, specific surface area was also determined by BET method. The four effective factors including pH of the reaction mixture, Fe3O4/ZnO magnetic nanoparticles concentration, initial MTBE concentration and molar ratio of [H2O2]/ [MTBE] were optimized using response surface...
Influence of nanoclay on morphology, mechanical properties and deformation mechanism of Polystyrene
, Article Polymer - Plastics Technology and Engineering ; Vol. 53, issue. 2 , 2014 , p. 156-161 ; ISSN: 03602559 ; Bagheri, R ; Sharif University of Technology
Abstract
Polystyrene/organoclay nanocomposites were prepared by melt intercalation method in this research. Morphology, tensile and impact properties and deformation mechanism of the samples were studied. To study the structure of nanocomposites, X-ray diffraction and transmission electron microscopy techniques are utilized. The deformation mechanisms of different samples were examined via reflected and transmitted optical microscopy. The results reveal that incorporation of organoclay affects structure, mechanical properties and deformation mechanism of nanocomposite. Introduction of organoclay can facilitate initiation and growth of crazing mechanism in polystyrene at both conditions of loadings,...
Synthesis of highly porous nanocrystalline alumina as a robust catalyst for dehydration of methanol to dimethyl ether
, Article Journal of Porous Materials ; Volume 20, Issue 1 , 2013 , Pages 151-157 ; 13802224 (ISSN) ; Kazemeini, M ; Aghaziarati, M ; Alamolhoda, S ; Sharif University of Technology
2013
Abstract
Highly porous nanocrystalline alumina was synthesized using two different precipitation processes and precipitating agents, which were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and porosimetry analyses. Different precipitating agents yielded nanocrystalline alumina catalysts with different morphologies and textural properties. Batch precipitation using sodium bicarbonate at constant pH resulted in a highly porous nanocrystalline γ-alumina catalyst, having surface area of 351.47 m2 g-1, total pore volume of 1.68 cm3 g -1 and mean pore diameter of 19.17 nm. The mean crystallite size was also determined to be 3.8 nm, based on the XRD results. Catalytic...
Influence of compatibilizer and processing conditions on morphology, mechanical properties, and deformation mechanism of PP/clay nanocomposite
, Article Journal of Nanomaterials ; Volume 2012 , 2012 ; 16874110 (ISSN) ; Bagheri, R ; Sharif University of Technology
2012
Abstract
Polypropylene/montmorillonite nanocomposite was prepared by melt intercalation method using a twin-screw extruder with starve feeding system in this paper. The effects of compatibilizer, extruder rotor speed and feeding rate on properties of nanocomposite were investigated. Structure, tensile, and impact properties and deformation mechanism of the compounds were studied. For investigation of structure and deformation mechanisms, X-ray diffraction (XRD) and transmission optical microscopy (TOM) techniques were utilized, respectively. The results illustrate that introduction of the compatibilizer and also variation of the processing conditions affect structure and mechanical properties of...
Characterization and photocatalytic activities of nanosized titanium dioxide thin films
, Article International Journal of Environmental Science and Technology ; Volume 8, Issue 3 , 2011 , Pages 545-552 ; 17351472 (ISSN) ; Rashidzadeh, M ; Nemati, A ; Irandoukht, A ; Faridnia, B ; Sharif University of Technology
2011
Abstract
Thin films of titanium dioxide with high surface area are prepared by sol-gel dip-coating technique. In this regards, Titania nano sols with high photocatalytic activity were prepared by dissolving titanium alkoxide in alcohol and water under acidic conditions. Photocatalytic activities of titanium dioxide thin films were measured in the presence of methylene blue. Microstructure and photocatalytic activity of the films, nanopowders and titanium dioxide sols were investigated using X-ray diffraction, scanning electron microscopy, specific surface area, zeta sizer and ultraviolet-visible spectrometry techniques. Particle size analysis of sols showed that the mean particle sizes were 15 to 128...
An enhancement in the photocatalytic activity of TiO 2 by the use of Pd: The question of layer sequence in the resulting hierarchical structure
, Article Journal of Coatings Technology Research ; Volume 8, Issue 1 , January , 2011 , Pages 75-81 ; 15470091 (ISSN) ; Ghorbani, M ; Mohsenzadeh, M ; Sharif University of Technology
2011
Abstract
TiO 2 and Pd-modified TiO 2 photocatalysts were prepared by sol-gel method. X-ray diffraction (XRD) data showed that the presence of Pd in TiO 2 catalyst decreases the crystalline size of TiO 2 and stabilizes anatase phase. The study of the photocatalytic activity of the films via Linear Sweep Voltametry (LSV) plots and antibacterial test against Escherichia coli ATCC 25922-a gram negative bacterium-showed that Pd increases the photocatalytic activity of the coatings. Besides, the sequence of layer deposition (TiO 2 and Pd-modified TiO 2) influences the photocatalytic properties. In other words, more photocatalytic activity is obtained when Pd-modified layer is deposited first
On water: A practical and efficient synthesis of benzoheterocycle derivatives catalyzed by nanocrystalline copper(II) oxide
, Article Synthetic Communications ; Volume 40, Issue 4 , 2010 , Pages 607-614 ; 00397911 (ISSN) ; Hekmatshoar, R ; Ahmadi, S. J ; Hosseinpour, M ; Outokesh, M ; Sharif University of Technology
Abstract
Recyclable CuO nanoparticles provide an efficient, economic, and novel method for the synthesis of quinoxaline, benzoxazine, and benzothiazine. This method provides a wide range of substrate applicability, avoids the use of organic solvents, and gives benzoheterocycles in satisfactory yields
Comparison of isothermal with cyclic oxidation behavior of “Cr-Aluminide” coating on inconel 738LC at 900 °C
, Article Oxidation of Metals ; Volume 87, Issue 1-2 , 2017 , Pages 57-74 ; 0030770X (ISSN) ; Ghasemi, B ; Sadrnezhaad, S. K ; Feizabadi, A ; HabibollahZadeh, A ; Salehi Doolabi, D ; AsadiZarch, M ; Sharif University of Technology
Springer New York LLC
2017
Abstract
A two-step pack cementation technique was used to cover nickel-based IN-738LC superalloy with a Cr-aluminide coating layer. The IN-738LC/Cr-aluminide samples were oxidized at 900 °C for 350 and 700 h, isothermally, and 175 and 350 h, cyclically. Each cycle lasted for 25 h. Effects of the isothermal and the cyclic oxidation on (a) morphology, (b) new-phase formation, (c) weight gain, and (d) oxidation reactions were investigated by scanning electron microscopy, electron dispersive spectroscopy, X-ray diffraction, and weight gain measurements. From results, it was concluded that the oxygen attack was more severe during the cyclic oxidation than the isothermal procedure. Kinetics of the...
Investigation of thermal behavior of α-PbO and β-PbO IN O2 atmosphere
, Article Metalurgija ; Volume 57, Issue 4 , 2018 , Pages 287-290 ; 05435846 (ISSN) ; Nazari Alavi, A ; Mirzai, M ; Sharif University of Technology
Faculty of Metallurgy
2018
Abstract
The compounds α-lead oxide (α-PbO) and β-lead oxide (β-PbO) were purchased from Merck co. and used for thermal investigations in laboratory. The compound was heated in a thermogravimeter at different temperature, from 25 to 400 °C. The used gas atmosphere was O2. The received products were investigated by X-ray diffraction (XRD) technique. The received product Pb3O4 was confirmed by XRD. The textures of two different morphologies of α-PbO, β-PbO and the product Pb3O4 is investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM) techniques. © 2018, Faculty of Metallurgy. All rights reserved
Flow stress evolution in further straining of severely deformed Al
, Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 50, Issue 5 , 2019 , Pages 2371-2380 ; 10735623 (ISSN) ; Kazeminezhad, M ; Sharif University of Technology
Springer Boston
2019
Abstract
To investigate the flow stress evolution in further straining of severely deformed Al sheets, a comprehensive model which considers both mechanical and metallurgical alterations is needed. In this study, constrained groove pressing (CGP) as a severe plastic deformation method, and a flat rolling process for further straining are utilized. Using basic mechanical models, strain and strain rate were calculated for this process. Dislocation density and flow stress evolutions were predicted by utilizing initial mechanical data, considering the ETMB (Y. Estrin, L. S. Toth, A. Molinari, and Y. Brechet) dislocation density model. Based on these model predictions, the combination of the CGP process...
Structural, non-covalent interaction, and natural bond orbital studies on bromido-tricarbonyl rhenium(I) complexes bearing alkyl-substituted 1,4-diazabutadiene (DAB) ligands
, Article Crystals ; Volume 10, Issue 4 , April , 2020 ; Kalaghchi, A ; Sharif University of Technology
MDPI AG
2020
Abstract
The synthesis, characterization, structural and computational studies of Re(I) tricarbonyl bromo complexes bearing alkyl-substituted 1,4-diazabutadiene ligands, [Re(CO)3(1,4-DAB)Br], where 1,4-DAB = N,N-bis(2,4-dimethylbenzene)-1,4-diazabutadiene,2,4-Me 2DAB (1); N,N-bis(2,4-dimethylbenzene)-2,3-dimethyl-1,4-diazabutadiene,2,4-Me 2DABMe (2); N,N-bis(2,4,6-trimethylbenzene)-1,4-diazabutadiene,2,4,6-Me 3DAB (3); and N,N-bis(2,6-diisopropylbenzene)-1,4-diazabutadiene,2,6-ipr 2DAB (4) are reported. The complexes were characterized by different spectroscopic methods such as FT-IR,1 H-NMR,13C-NMR, and elemental analyses and their solid-state structures were confirmed by X-ray diffraction. In each...
Crystallization and electrical properties of [(Pb1-xSrx)·TiO3][(2SiO2·B2O3)][K2O] glass-ceramics
, Article Journal of Materials Processing Technology ; Volume 206, Issue 1-3 , 12 September , 2008 , Pages 126-131 ; 09240136 (ISSN) ; Nemati, Z. A ; Alizadeh, P ; Bolandi, M ; Sharif University of Technology
2008
Abstract
The effect of compositional change on glass-ceramic formation and its electrical properties were studied. The composition was formulated with 40 wt.% of borosilicate glass, 60 wt.% of titanate and 10 wt.% of alkaline oxide. The glass samples with composition of [(Pb1-xSrx)·TiO3][(2SiO2·B2O3)][K2O] with different values of x (x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5) were prepared. After heat treatment of glasses at different temperatures, which were chosen based on differential thermal analysis-DTA curves, the crystallized phase and its microstructure were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD and SEM results revealed the formation of ferroelectric solid...
Five- and six-coordinated silver(I) complexes formed by a metallomacrocyclic ligand with a “Au2N2” donor group: observation of pendulum and linear motions and dual phosphorescence
, Article Inorganic Chemistry ; Volume 59, Issue 8 , 31 March , 2020 , Pages 5702-5712 ; Jamali, S ; Jamjah, A ; Shakirova, J. R ; Tunik, S. P ; Gurzhiy, V ; Samouei, H ; Shahsavari, H. R ; Sharif University of Technology
American Chemical Society
2020
Abstract
The six-coordinated silver(I) complex [Au2Ag(μ-(PPh2)2py)2(OTf)2](OTf), 4 (py = pyridine, OTf = CF3SO3), and the five-coordinated silver(I) complex [Au2Ag(acetone)(μ-(PPh2)2py)2](PF6)3, 6, were prepared by the reaction of the precursor complexes 1(OTf)2 and 1(PF6)2, in which 1 = [Au2(μ-(PPh2)2py)2]2+, with 1 equiv of Ag(OTf) in dichloromethane and excess of Ag(PF6) in a mixture of dichloromethane/acetone, respectively. Also, the five-coordinated silver(I) complex [Au2Ag(μ-(PPh2)2py)2(py)(OTf)](OTf)2, 5, was obtained by the reaction of 4 with pyridine. The clusters 4-6 were characterized using multinuclear NMR spectroscopy and elemental microanalysis. The single-crystal X-ray diffraction...
Characterization of mechanically alloyed Fe100-xSix and Fe83.5Si13.5Nb3 nanocrystalline powders
, Article Journal of Materials Processing Technology ; Volume 203, Issue 1-3 , 2008 , Pages 554-560 ; 09240136 (ISSN) ; Abachi, P ; Madaah Hosseini, H. R ; Bahrami, A ; Sharif University of Technology
2008
Abstract
In present research, nanocrystalline Fe100-xSix (x = 6.5, 10, 13.5, 20 and 25 at.%) and Fe83.5Si13.5Nb3 alloy powders were prepared by mechanical alloying using high-energy ball milling. The resulting powders mainly consist of micron-sized particles with an average grain size of less than 20 nm. According to the XRD test results, by increasing the milling time and/or the Si content the lattice parameter decreases and the internal microstrain increases. In addition, the specific saturation magnetization diminishes as Si content increases. The coercive forces of the as-milled nanocrystalline powders are much higher than those of corresponding Fe-Si bulk alloys with a minimum at 13.5 at.% Si....
Hall effect and sign reversal in Gd(Ba2-xNdx)Cu3O7+δ
, Article Journal of Magnetism and Magnetic Materials ; Volume 320, Issue 13 , 2008 , Pages 1884-1888 ; 03048853 (ISSN) ; Taheri, M ; Akhavan, M ; Sharif University of Technology
2008
Abstract
We have investigated the Hall measurement of Gd(Ba2-xNdx)Cu3O7+δ with x=0, 0.05, 0.1, 0.15, and 0.2 in a magnetic field of 0-1 T. The nominal samples has been prepared by the conventional solid-state reaction technique. The iodometric titration experiment was carried out for samples. The Rietveld analysis of the X-ray diffraction patterns indicates that samples are mainly single phase. The normal state Hall coefficient behaves as 1/T in all samples. All samples with nominal compositions show single sign reversal with variation of magnetic field and temperature. The Hall resistivity of the samples with x=0 and 0.1 close to the superconducting transition temperature changes its sign with...
The effect of heating time on growth of NaxWO3 nanowhiskers
, Article Vacuum ; Volume 82, Issue 8 , 2008 , Pages 821-826 ; 0042207X (ISSN) ; Goudarzi, M ; Akhavan, O ; Moshfegh, A. Z ; Sharif University of Technology
2008
Abstract
A simple method for synthesis of NaxWO3 nanowhiskers on tungsten thin films with 40 nm thickness sputtered on soda lime substrate as a source of sodium atoms has been reported for the first time. After heat treatment of the W thin films at 650 °C in N2 ambient for different times (15, 80 and 180 min), crystalline NaxWO3 nanowhiskers with [0 0 1] direction were obtained. scanning electron microscopy (SEM), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS) and optical transmission/reflection measurements were employed to determine various properties of the grown nanowhiskers. Experimental results revealed that size and density of nanowhiskers were dependent on the annealing...
Thermal behavior of alkaline lead acetate, a study of thermogravimetry and differential scanning calorimetry
, Article Scientia Iranica ; Volume 15, Issue 4 , 2008 , Pages 435-439 ; 10263098 (ISSN) ; Alamolhoda, A. A ; Hashemian, S. J ; Sharif University of Technology
Sharif University of Technology
2008
Abstract
The compound, alkaline lead acetate, Pb(CH3COO)2·PbO·H2O (ALA), was purchased from the Fluka Company. The X-ray diffraction film and SEM electron microgaph of this compound were obtained and reported in this paper for the first time. The thermal behavior of alkaline lead acetate (ALA) was studied using thermogravimetery (TGA) and Differential Scanning Calorimetery (DSC) techniques under an O2 gas atmosphere from 25 to 600°C. Four distinct energy changes associated with weight changes were observed, all of them being exothermic in the DSC results. The amount of ΔH for each peak is reported. © Sharif University of Technology
Thickness dependence on thermal stability of sputtered Ag nanolayer on Ti/Si(1 0 0)
, Article Applied Surface Science ; Volume 254, Issue 2 , 2007 , Pages 548-551 ; 01694332 (ISSN) ; Moshfegh, A.Z ; Sharif University of Technology
Elsevier
2007
Abstract
Thermal stability of Ag layer on Ti coated Si substrate for different thicknesses of the Ag layer have been studied. To do this, after sputter-deposition of a 10 nm Ti buffer layer on the Si(1 0 0) substrate, an Ag layer with different thicknesses (150-5 nm) was sputtered on the buffer layer. Post annealing process of the samples was performed in an N 2 ambient at a flow rate of 200 ml/min in a temperature range from 500 to 700 °C for 30 min. The electrical property of the heat-treated multilayer with the different thicknesses of Ag layer was examined by four-point-probe sheet resistance measurement at the room temperature. Phase formation and crystallographic orientation of the silver...
Localization length-doping dependence in GdBa2Cu3-xCrxO7-δ
, Article Physica C: Superconductivity and its Applications ; Volume 466, Issue 1-2 , 2007 , Pages 157-162 ; 09214534 (ISSN) ; Javanmard, H ; Akhavan, M ; Sharif University of Technology
2007
Abstract
The bulk samples of GdBa2Cu3-xCrxO7-δ with x = 0-0.3 have been prepared by the conventional solid-state reaction method. Structural phases were determined by powder X-ray diffraction. The XRD and the unit cell parameters were obtained through Rietveld refinement of the XRD data. By increasing the doping, the c parameter decreases and the a parameter increases, and by the nearly fixed b parameter, the orthorhombic phase approaches to the tetragonal phase. The resistivity measurements show a strong effect of doping on suppression of Tc. At the first doping step of x = 0.05, Tc decreases abruptly to 57 K, but by increasing the doping, this rate slows down and becomes nearly linear for higher...
Synthesis parameters and their effects on the resistivity anomaly in GdPr1113 ceramic
, Article Journal of Superconductivity and Novel Magnetism ; Volume 20, Issue 4 , 2007 , Pages 279-283 ; 15571939 (ISSN) ; Akhavan, M ; Sharif University of Technology
2007
Abstract
Tetragonal Gd 1-x Pr x BaSrCu 3O 7-δ (GdPr1113) polycrystalline high-temperature superconducting ceramic samples have been synthesized by the standard solid-state reaction process with different calcination and sintering temperatures and characterized by XRD and SEM. The optimum synthesis temperatures for obtaining single phase varied with Pr doping. Higher temperatures were necessary to obtain single phase for x ≥ 0.3. It was found that higher synthesis temperatures improved the electrical characteristics of these materials. The effects of different calcination and sintering temperatures on the anomalous hump in the ρ(T) curves observed at about 80 K is investigated. The percentage of the...