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Selective oxidation of sulfides to sulfoxides by a molybdate-based catalyst using 30% hydrogen peroxide
, Article Catalysis Communications ; Vol. 52, issue , July , 2014 , pp. 16-21 ; ISSN: 15667367 ; Shakourian-Fard, M ; Hashemi, M. M ; Sharif University of Technology
Abstract
An efficient method is reported for selective oxidation of various types of sulfides to sulfoxides and sulfones in good to high yields using 30% H 2O2 in the presence of catalytic amounts of molybdate-based catalyst in acetonitrile as solvent at room temperature. The catalyst can be easily recovered and reused for seven reaction cycles without considerable loss of activity
Pulsed laser irradiation for environment friendly reduction of graphene oxide suspensions
, Article Applied Surface Science ; Vol. 301 , May , 2014 , pp. 183-188 ; ISSN: 01694332 ; Rashidi, N ; Kimiagar, S ; Akhavan, O ; Manouchehri, F ; Ghaderi, E ; Sharif University of Technology
Abstract
Graphene oxide (GO) sheets were synthesized through a modified Hummers' method. Using high resolution transmission electron microscopy the thickness of the GO sheets in a multilayer structure of stacked GO sheets was found ∼0.8 nm. A nanosecond pulsed laser (with wavelength of 532 nm and average power of 0.3 W) was applied for effective and environment friendly reduction of the GO sheets in an ammonia solution (pH ∼9) at room temperature conditions. The deoxygenation of the GO sheets by the pulsed laser reduction method was confirmed by using UV-visible, Fourier transform infrared, X-ray photoelectron spectroscopy (XPS) and thermo gravimetric analysis. Based on XPS analysis, the O/C ratio of...
Facile synthesis of monodisperse thermally immiscible Ag-Ni alloy nanoparticles at room temperature
, Article Bulletin of Materials Science ; Vol. 37, issue. 6 , 2014 , pp. 1447-1452 ; Sadrnezhaad, S. K ; Sharif University of Technology
Abstract
Ag and Ni are immiscible, mainly due to their large lattice mismatch. This paper reports on their nanoscale formation of solid solution at room temperature by simple reduction reactions which lead to the amorphous Ag-Ni alloy nanoparticles (ANPs) with mono-disperse distribution. Microscopic and spectroscopic studies confirmed dependence of the alloy composition on size of nanoparticles. In the presence of different ligands such as sodium citrate, polyvinyl alcohol and potassium carbonate a mixture of silver oxide and Ag-Ni ANPs was achieved. Stoichiometry of the Ag-Ni ANPs was also found to be strongly dependent on ligands of the reduction reaction and further study shows without any ligand...
Efficient synthesis of novel 3-substituted coumarin-3-carboxamide
, Article Journal of the Korean Chemical Society ; Vol. 58, Issue. 2 , 20 April , 2014 , pp. 186-192 ; ISSN: 2234-8530 (Online) ; Balalaie, S ; Bigdeli, M. A ; Habibi, A ; Moghaddam, H. P ; Sharif University of Technology
Abstract
A series of novel pseudopeptides contained coumarin skeleton were synthesized through the Ugi-four-component reaction. The 3-substituted coumarin-3-carboxamides were formed through reaction of benzaldehyde derivatives, anilines, coumarin-3- carboxylic acid and isocyanides with high yields and high bond-forming efficiency at room temperature. These novel amidated coumarins exhibit brilliant fluorescence in range of 535-547 nm in chloroform
Gold extraction from an oxide ore in iodine-iodide solutions
, Article Industrial Electrochemistry and Electrochemical Engineering General Session - 220th ECS Meeting, Boston, MA, 9 October 2011 through 14 October 2011 ; Volume 41, Issue 17 , 2012 , Pages 53-60 ; 19385862 (ISSN) ; 9781607683070 (ISBN) ; Sharif University of Technology
Abstract
Two types of gold ores were subjected to iodide/iodine leaching at room temperature. The effects of three factors, including ore type (a carbonaceous and an oxide gold ores), iodide/iodine concentration, and the presence of oxygen in solution on gold leaching performance were investigated. The carbonaceous ore showed only 20% gold extraction into the solution; since gold-iodide complexes would readily adsorb on organic matter. In contrast, gold extraction from the oxide ore in a solution containing 20 g/L iodide and 4 g/L iodine reached 77% in 6 h and 89% in 24 h. With iodate as the oxidant, no gold could be leached in 48 hours. When the iodate was partially converted to iodine by adding HCl...
Influence of deformation path change on static strain aging of cold rolled steel strip
, Article International Journal of Advanced Manufacturing Technology ; Volume 61, Issue 9-12 , 2012 , Pages 901-909 ; 02683768 (ISSN) ; Serajzadeh, S
Abstract
Effect of deformation path change on the static strain aging of low carbon steel was studied in this work. In the first stage, strip samples were subjected to cold rolling processes under different paths with the same total reduction in thickness while the deformation behaviors of the rolled samples were also evaluated using a mathematical analysis. Then, cold-rolled strips were aged in room temperature up to 45 days while hardness and tensile evaluations were performed to assess the mechanical properties of the as-rolled and the aged samples. Finally, the influence of rolling pass schedule on the subsequent strain aging phenomenon was investigated by means of the experimental results and...
The effect of pre-straining at intermediate temperatures on the mechanical behavior of high-bainite dual phase (HBDP) steels
, Article Materials Science and Engineering A ; Volume 543 , May , 2012 , Pages 224-230 ; 09215093 (ISSN) ; Haghshenas Fatmehsari, D ; Ekrami, A ; Sharif University of Technology
Abstract
High-bainite dual phase (HBDP) steels with 34. vol.% ferrite were subjected to tensile strains of 1%, 3%, and 5% at intermediate temperatures (150-450. °C). Mechanical behavior of pre-deformed steels was then investigated at room temperature. A maximum value for both yield stress and ultimate tensile strength was observed for pre-deformed steels. A minimum elongation was also found in the same pre-deformed specimens at the range of 250-350. °C. It was found that dynamic strain aging (DSA) plays the major role in mechanical properties of pre-strained HBDP steels. The DSA indicator parameter (DSAP) was introduced to evaluate DSA mechanism. Maxima of DSAP were likewise observed at the range of...
Efficient synthesis of novel coumarin-3-carboxamides (=2-oxo-2h-1- benzopyran-3-carboxamides) containing lipophilic spacers
, Article Helvetica Chimica Acta ; Volume 95, Issue 3 , 2012 , Pages 528-535 ; 0018019X (ISSN) ; Bigdeli, M. A ; Sheikhhosseini, E ; Habibi, A ; Moghadam, H. P ; Naderi, M ; Sharif University of Technology
Abstract
The novel coumarin-3-carboxamides (=2-oxo-2H-1-benzopyran-3-carboxamides) 5a-5g containing lipophilic spacers were synthesized through the Ugi-four-component reaction (Scheme 1). The reactions of aromatic aldehydes 1, 4,4'-oxybis[benzenamine] or 4,4'-methylenebis[benzenamine] as diamine 2, coumarin-3-carboxylic acid (=2-oxo-2H-benzopyran-3-carboxylic acid; 3), and alkyl isocyanides 4 lead to the desired substituted coumarin-3-carboxamides 5a-5g at room temperature with high bond-forming efficiency. These novel coumarin derivatives exhibit brilliant fluorescence at 544 nm in CHCl 3
AC impedance and cyclic voltammetry studies on PbS semiconducting film prepared by electrodeposition
, Article Journal of Electroanalytical Chemistry ; Volume 661, Issue 1 , 2011 , Pages 265-269 ; 15726657 (ISSN) ; Jafarian, M ; Danaee, I ; Gobal, F ; Mahjani, M. G ; Sharif University of Technology
Abstract
Semiconducting lead sulfide film was deposited on Stainless Steel (SS) electrode by cyclic voltammetry (CV) at room temperature. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry were used to investigate the electrochemical properties of PbS film in Na2SO4 solution. The voltammetric results showed that oxidative dissolution of PbS film occurred at about 0.21 V vs. Ag/AgCl and total film detachment from the surface occurs with increasing potential. It is concluded that the electrode surface was not passivated by sulfur produced from oxidative dissolution of PbS film. Also, cathodic reduction of the film continued to beyond the hydrogen evolution at -1.35 V vs. Ag/AgCl....
Microstructure-toughness relationship in AISI4340 steel
, Article Defect and Diffusion Forum ; Volume 312-315 , 2011 , Pages 110-115 ; 10120386 (ISSN) ; 9783037851173 (ISBN) ; Ekrami, A ; Sharif University of Technology
Abstract
To improve the strength and toughness of AISI 4340 steel, different microstructures, containing full bainite, bainite-ferrite, martensite-ferrite and full martensite were produced by different heat treatment cycles. Tensile, impact and hardness tests were carried out at room temperature. The ductile-brittle transition temperature was determined from impact data at different temperatures. The results showed that steel with bainite - 0.34 ferrite microstructure has the highest elongation and charpy impact energy, while its tensile strength and yield stress decreased in comparison to other microstructures. This increment was noticeable when bainite - 0.34 ferrite steel was tempered. The...
Microstructural features, texture and strengthening mechanisms of nanostructured AA6063 alloy processed by powder metallurgy
, Article Materials Science and Engineering A ; Volume 528, Issue 12 , 2011 , Pages 3981-3989 ; 09215093 (ISSN) ; Simchi, A ; Kim, H. S ; Sharif University of Technology
Abstract
Nanostructured AA6063 (NS-Al) powder with an average grain size of ~100. nm was synthesized by high-energy attrition milling of gas-atomized AA6063 powder followed by hot extrusion. The microstructural features of the consolidated specimen were studied by transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) techniques and compared with those of coarse-grained AA6063 (CG-Al) produced by hot powder extrusion of gas-atomized powder (without using mechanical milling). The consolidated NS-Al alloy consisted of elongated ultrafine grains (aspect ratio of ~2.9) and equiaxed nanostructured grains. A high fraction (~78%) of high-angle grain boundaries with average...
Crystallisation kinetics of hydroxyapatite thin films prepared by sol-gel process
, Article Advances in Applied Ceramics ; Volume 109, Issue 6 , Jul , 2010 , Pages 313-317 ; 17436753 (ISSN) ; Nemati, A ; Sadeghian, Z ; Sharif University of Technology
Abstract
In this study, the crystallisation of nano hydroxyapatite (HA) films on stainless steel 316L was studied. The film was prepared by sol-gel technique. The process was started with preparation of an HA sol. After aging of the sol at room temperature, a stainless steel 316L substrate was dip coated and then was heat treated from 350 to 450°C at different periods of time in air. The crystallisation behaviour and the transformation-temperature-time diagram of HA films were achieved and analysed using the avrami equation. The results showed that the crystallisation of HA began at 250°C and was increased up to 450°C. The obtained HA film showed a nanostructure character with a suitable crystalinity...
Pd doped WO3 films prepared by sol-gel process for hydrogen sensing
, Article International Journal of Hydrogen Energy ; Volume 35, Issue 2 , 2010 , Pages 854-860 ; 03603199 (ISSN) ; Iraji zad, A ; Rahimi, F ; Ghasempour, R ; Sharif University of Technology
Abstract
The sol gel method was employed to prepare peroxopolytungstic acid (P-PTA). Palladium chloride salt was dissolved in the sol with different Pd:W molar ratios and coated on Al2O3 substrates by spin coating method. XRD and XPS techniques were used to analyze the crystal structure and chemical composition of the films before and after heat treatment at 500 °C. We observed that Pd can modify the growth kinetic of tungsten trioxide nanoparticles by reducing the crystallite size and as a result can improve hydrogen sensitivity. Resistance-sensing measurements indicated sensitivity of about 2.5 × 104 at room temperature in hydrogen concentration of 0.1% in air. Considering all sensing parameters,...
The effect of dynamic strain aging on fatigue properties of dual phase steels with different martensite morphology
, Article Materials Science and Engineering A ; Volume 527, Issue 1-2 , 2009 , Pages 235-238 ; 09215093 (ISSN) ; Ekrami, A ; Sharif University of Technology
Abstract
Dual phase (DP) steels with network and fibrous martensite were produced by intercritical annealing heat treatment cycles. Some of these steels were deformed at dynamic strain aging temperatures. Room temperature tensile tests of specimens deformed at 300 °C showed that both yield and ultimate tensile strengths for both morphologies increased, while total elongation decreased. Fatigue test results before and after high temperature deformation showed that dynamic strain aging has a stronger effect on fatigue properties of dual phase steels with fibrous martensite. Cracks in DP steels with fibrous martensite propagate in a tortuous path in soft ferrite phase, while they pass of both hard and...
Cu surface segregation in Ni/Cu system
, Article Vacuum ; Volume 84, Issue 4 , 2009 , Pages 469-473 ; 0042207X (ISSN) ; Iraji zad, A ; Ahadian, M. M ; Sharif University of Technology
Abstract
We report experimental evidence of Cu surface segregation in Ni/Cu system, during deposition of Ni film onto Cu substrate at room temperature and during heat treatment in vacuum. Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) by Tougaard's analysis results show that surface segregation defeats in competition with increase in Ni thickness and terminates when thickness of Ni increase to more than 4 nm. Surface energy and concentration were calculated using contact angle measurements and the results confirm that segregation reduces the surface energy. Surface segregation during heat treatment at 150-220 °C range as a function of time initially shows linear mass...
A copper-catalyzed synthesis of functionalized quinazolines from isocyanides and aniline tri- and dichloroacetonitrile adducts through intramolecular C-H activation
, Article Synlett ; Volume 28, Issue 12 , 2017 , Pages 1441-1444 ; 09365214 (ISSN) ; Rezaee, E ; Tabatabai, S. A ; Jahani, M ; Sharif University of Technology
Abstract
A novel class of substituted quinazolines were prepared in good yields by a one-pot three-component reaction of isocyanides with adducts of anilines and tri- or dichloroacetonitrile, followed by intramolecular C-H activation, catalyzed by copper(I) iodide with l -proline as a ligand in acetonitrile at room temperature. © 2017 Georg Thieme Verlag Stuttgart .New York-Synlett