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    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) Molaei, M. J ; Ekrami, A ; Sharif University of Technology
    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... 

    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) Nematpour, M ; Rezaee, E ; Tabatabai, S. A ; Jahani, M ; Sharif University of Technology
    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  

    Ballistic molecular transport through two-dimensional channels

    , Article Nature ; Volume 558 , 20 June , 2018 , Pages 420-423 ; 00280836 (ISSN) Keerthi, A ; Geim, A. K ; Janardanan, A ; Rooney, A. P ; Esfandiar, A ; Hu, S ; Dar, S. A ; Grigorieva, I. V ; Haigh, S. J ; Wang, F. C ; Radha, B ; Sharif University of Technology
    Nature Publishing Group  2018
    Gas permeation through nanoscale pores is ubiquitous in nature and has an important role in many technologies 1,2 . Because the pore size is typically smaller than the mean free path of gas molecules, the flow of the gas molecules is conventionally described by Knudsen theory, which assumes diffuse reflection (random-angle scattering) at confining walls 3-7 . This assumption holds surprisingly well in experiments, with only a few cases of partially specular (mirror-like) reflection known 5,8-11 . Here we report gas transport through ångström-scale channels with atomically flat walls 12,13 and show that surface scattering can be either diffuse or specular, depending on the fine details of the... 

    Comparison of mechanical properties of martensite/ferrite and bainite/ferrite dual phase 4340 steels

    , Article Materials Science and Engineering A ; Volume 523, Issue 1-2 , 2009 , Pages 125-129 ; 09215093 (ISSN) Saeidi, N ; Ekrami, A ; Sharif University of Technology
    Different microstructures were produced by heat treatment of 4340 steel. These microstructures are bainite, martensite, ferrite-martensite and ferrite-bainite. Mechanical tests were carried out at room temperature. The results showed that steel with bainite-ferrite microstructure has better ductility and charpy impact energy than steels with martensite-ferrite and full bainite microstructures. But yield and tensile strengths of this steel are less than the yield and tensile strengths of the other two steels. Hardness measurements showed that their hardness is the same. Fracture surface observations of tensile specimens showed increase in toughness of bainite-ferrite in comparison to... 

    Microstructure-performance relationships in gas tungsten arc welded Hastelloy X nickel-based superalloy

    , Article Materials Science and Engineering A ; Volume 793 , 2020 Ghasemi, A ; Kolagar, A. M ; Pouranvari, M ; Sharif University of Technology
    Elsevier Ltd  2020
    This study aims at understanding the metallurgical and mechanical response of Hastelloy X nickel-based superalloy to the thermal cycle of gas tungsten arc welding (GTAW), post welding solution treatment (ST), and aging. In the as-weld condition, the weldment was characterized by the formation of the M6C carbide, sigma phase, and micro-solidification cracks in the interdendritic zones of the weld metal, and constitutional liquation of M6C carbide in the heat-affected zone. It is demonstrated that neither the weld metal nor the heat-affected zone could adversely affect mechanical properties of the welded joint in as-weld condition. However, to alleviate the microstructural heterogeneity,... 

    A new Mumm-type rearrangement with dithiocarbamates via isocyanide-based multicomponent reaction under ultrasound irradiation: synthesis of polysubstituted pyrrolidine compounds

    , Article New Journal of Chemistry ; Volume 44, Issue 23 , May , 2020 , Pages 9699-9702 Matloubi Moghaddam, F ; Goudarzi, M ; Chamani, F ; Mohammadzadeh Dezag, H ; Sharif University of Technology
    Royal Society of Chemistry  2020
    A novel and efficient multicomponent reaction for the synthesis of polysubstituted pyrrolidine derivatives is described under catalyst-free conditions using ultrasonic irradiation. The reactions were performed via a one-pot four-component condensation of secondary amines, carbon disulfide, isocyanides, and gem-dicyano olefins at room temperature to afford polysubstituted pyrrolidines diastereoselectively in 56-96% yields. This is the first report of a Mumm-type rearrangement with dithiocarbamates followed by intramolecular cyclization, which leads to the preparation of the key structure of pyrrolidine. This journal is © The Royal Society of Chemistry and the Centre National de la Recherche... 

    Sequential RTV/(TiO2/SiO2) nanocomposite deposition for suppressing the leakage current in silicone rubber insulators

    , Article Applied Physics A: Materials Science and Processing ; Volume 126, Issue 5 , 2020 Parand, P ; Mohammadi, M ; Shayegani Akmal, A. A ; Samadpour, M ; dehghani, M ; Parvazian, E ; Sharif University of Technology
    Springer  2020
    The sequential deposition method is introduced for suppressing the leakage current in silicone rubber insulators. Room temperature vulcanizing silicone and TiO2/silica nanocomposites are sequentially deposited on silicone insulators surface. TEM results showed that TiO2 nanoparticles size is about 20–30 nm, and the structural study revealed their anatase crystalline structure. Silica nanoparticles are deposited on the surface of insulators by spray deposition. The contact angle was enhanced from 104° to 149° after nanoparticles deposition, which confirms the hydrophobicity improvement. Results show that leakage current for nanocomposite samples in a contaminated environment reduced to about... 

    Near-room-temperature spin caloritronics in a magnetized and defective zigzag MoS2 nanoribbon

    , Article Journal of Computational Electronics ; Volume 19, Issue 1 , 2020 , Pages 137-146 Zakerian, F ; Fathipour, M ; Faez, R ; Darvish, G ; Sharif University of Technology
    Springer  2020
    Using a tight-binding approach and first-principles calculations combined with the nonequilibrium Green’s function method, the thermal spin transport in a zigzag molybdenum disulfide (MoS 2) nanoribbon in the proximity of a ferromagnetic insulator that induces a local exchange magnetic field in the center of the nanoribbon is investigated. It is found that a pure spin current and perfect spin Seebeck effect with zero charge current can be generated by applying a thermal gradient and local exchange magnetic field without a bias voltage near room temperature. Furthermore, it is shown that this nanoscale device can act as a spin Seebeck diode for the control of thermal and spin information in... 

    Effect of microstructure on rolling behavior of NiTi memory alloy

    , Article Materials and Manufacturing Processes ; Volume 23, Issue 7 , 26 August , 2008 , Pages 646-650 ; 10426914 (ISSN) Sadrnezhaad, S. K ; Badakhshan Raz, S ; Sharif University of Technology
    NiTi shape memory alloy (SMA) ingots were produced by vacuum induction melting/casting unit. The effect of microstructure on the hot (1000C) and cold (room temperature) rolling workability of cast samples was investigated. Microstructure of the cast samples was related to the type of crucible which used for melting and the average vacuum pressure of VIM furnace. Optical microscope, scanning electron microscope (SEM), and energy dispersive technology (EDS) methods were used to inspect the origins of observed cracks after rolling processes. The results showed that the formation of both Ti4Ni2O and TiC impurities formed due to inappropriate melting conditions had detrimental effects on... 

    Water repellent room temperature vulcanized silicone for enhancing the long-term stability of perovskite solar cells

    , Article Solar Energy ; Volume 218 , 2021 , Pages 28-34 ; 0038092X (ISSN) Samadpour, M ; Heydari, M ; Mohammadi, M ; Parand, P ; Taghavinia, N ; Sharif University of Technology
    Elsevier Ltd  2021
    A key direction toward enhancing the long term and outdoor stability of the perovskite solar cells is encapsulation. As a result, a suitable encapsulation package is required to prevent moisture and oxygen penetration toward the perovskite solar cells. In this work, a low-cost commercially available bilayer structure of poly (methyl methacrylate)/ room-temperature vulcanizing silicone rubber (RTV) encapsulation package for enhancing the long term stability of the perovskite solar cells has been investigated. Encapsulated cells retained more than 80% of the initial efficiency at the environmental condition of 50% moisture, and room temperature after 1000 h, however reference cell efficiency... 

    Solid lithium perchlorate as a powerful catalyst for the synthesis of β-aminoalcohols under solvent-free conditions

    , Article Canadian Journal of Chemistry ; Volume 83, Issue 5 , 2005 , Pages 505-507 ; 00084042 (ISSN) Azizi, N ; Saidi, M. R ; Sharif University of Technology
    Lithium perchlorate catalyzed the ring opening of epoxides with amines to provide the corresponding β-aminoalcohols in excellent yields with high regioselectivity. The reaction proceeds rapidly under mild and neutral conditions and worked well with primary, secondary, aliphatic, aromatic, and hindered amines in short times at room temperature, in the absence of solvent. © 2005 NRC Canada  

    An intriguing effect of lithium perchlorate dispersed on silica gel in the bromination of aromatic compounds by N-bromosuccinimide

    , Article Canadian Journal of Chemistry ; Volume 83, Issue 2 , 2005 , Pages 146-149 ; 00084042 (ISSN) Bagheri, M ; Azizi, N ; Saidi, M. R ; Sharif University of Technology
    A convenient and efficient procedure for electrophilic aromatic bromination has been developed by mixing of N-bromosuccinimide and an aromatic compound at room temperature on the surface of silica gel mixed with solid anhydrous LiClO4. All of the substrates examined underwent clean electrophilic aromatic bromination in reaction times of a few minutes to afford the corresponding bromoarenes under neutral conditions in excellent yield. In the case of thiophenol, no substitution reaction occurred, and the corresponding disulfide was obtained in excellent yield. © 2005 NRC Canada  

    Ionic liquid/graphene oxide as a nanocomposite for improving the direct electrochemistry and electrocatalytic activity of glucose oxidase

    , Article Journal of Solid State Electrochemistry ; Volume 17, Issue 1 , January , 2013 , Pages 183-189 ; 14328488 (ISSN) Tasviri, M ; Ghasemi, S ; Ghourchian, H ; Gholami, M. R ; Sharif University of Technology
    By combination of 1-ethyl-3-methyl immidazolium ethyl sulfate as a typical room temperature ionic liquid (IL) and graphene oxide (GO) nanosheets, a nanocomposite was introduced for improving the direct electrochemistry and electrocatalytic activity of glucose oxidase (GOx). The enzyme on the IL-GO-modified glassy carbon electrode exhibited a quasireversible cyclic voltammogram corresponding to the flavine adenine dinucleotide/FADH2 redox prosthetic group of GOx. At the scan rate of 100 mV s-1, the enzyme showed a peak-to-peak potential separation of 82 mV and the formal potential of -463 mV (vs Ag/AgCl in 0.1 M phosphate buffer solution, pH 7.0). The kinetic parameters of the charge transfer... 

    A superabsorbent hydrogel network based on poly ((2-dimethylaminoethyl) methacrylate) and sodium alginate obtained by γ-radiation: Synthesis and characterization

    , Article Iranian Polymer Journal (English Edition) ; Volume 21, Issue 12 , 2012 , Pages 829-836 ; 10261265 (ISSN) Bardajee, G. R ; Hooshyar, Z ; Zehtabi, F ; Pourjavadi, A ; Sharif University of Technology
    In this study, the synthesis and characterization of a novel nano-porous superabsorbent hydrogel with high water swelling capacity is described. A nano-porous hydrogel was prepared by employing (2-dimethylaminoethyl) methacrylate (PDMAEMA) as a pH sensitive monomer and sodium alginate (SA) as a water soluble polysaccharide under γ-ray irradiation. The polymerization reaction was performed at room temperature in the absence of chemically toxic crosslinking agent and initiators. The interactive parameters including biopolymer backbone concentration, monomer concentration and γ-irradiation dose were selected as major factors in the synthesis of superabsorbent and three levels for each factor... 

    Electrophoretic deposition of bioactive glass coating on 316L stainless steel and electrochemical behavior study

    , Article Applied Surface Science ; Volume 258, Issue 24 , 2012 , Pages 9832-9839 ; 01694332 (ISSN) Mehdipour, M ; Afshar, A ; Mohebali, M ; Sharif University of Technology
    Elsevier  2012
    In this research, submicron bioactive glass (BG) particles were synthesized by a sol-gel process and were then coated on a 316L stainless steel substrate using an electrophoretic deposition (EPD) technique. Stable suspension of bioactive glass powders in ethanol solvent was prepared by addition of triethanol amine (TEA), which increased zeta potential from 16.5 ± 1.6 to 20.3 ± 1.4 (mv). Thickness, structure and electrochemical behavior of the coating were characterized. SEM studies showed that increasing EPD voltage leads to a coating with more agglomerated particles, augmented porosity and micro cracks. The results of Fourier transformed infrared (FTIR) spectroscopy revealed the adsorption... 

    Comparison of dry reforming of methane in low temperature hybrid plasma-catalytic corona with thermal catalytic reactor over Ni/γ-Al 2O 3

    , Article Journal of Natural Gas Chemistry ; Volume 21, Issue 4 , 2012 , Pages 466-475 ; 10039953 (ISSN) Aziznia, A ; Bozorgzadeh, H. R ; Seyed Matin, N ; Baghalha, M ; Mohamadalizadeh, A ; Sharif University of Technology
    In the current study, the hybrid effect of a corona discharge and γ-alumina supported Ni catalysts in CO 2 reforming of methane is investigated. The study includes both purely catalytic operation in the temperature range of 923-1023 K, and hybrid catalytic-plasma operation of DC corona discharge reactor at room temperature and ambient pressure. The effect of feed flow rate, discharge power and Ni/γ-Al 2O 3 catalysts are studied. When CH 4/CO 2 ratio in the feed is 1/2, the syngas of low H 2/CO ratio at about 0.56 is obtained, which is a potential feedstock for synthesis of liquid hydrocarbons. Although Ni catalyst is only active above 573 K, presence of Ni catalysts in the cold corona plasma... 

    Enhanced electricity generation from whey wastewater using combinational cathodic electron acceptor in a two-chamber microbial fuel cell

    , Article International Journal of Environmental Science and Technology ; Volume 9, Issue 3 , 2012 , Pages 473-478 ; 17351472 (ISSN) Nasirahmadi, S ; Safekordi, A. A ; Sharif University of Technology
    While energy consumption is increasing worldwide due to population growth, the fossil fuels are unstable and exhaustible resources for establishing sustainable life. Using biodegradable compounds present in the wastewater produced in industrial process as a renewable source is an enchanting approach followed by scientists for maintaining a sustainable energy production to vanquish this problem for ulterior generations. In this research, bioelectricity generation with whey degradation was investigated in a two-chamber microbial fuel cell with humic acid as anodic electron mediator and a cathode compartment including combinational electron acceptor. Escherichia coli was able to use the... 

    New gasochromic system: Nanoparticles in liquid

    , Article Journal of Nanoparticle Research ; Volume 14, Issue 4 , March , 2012 ; 13880764 (ISSN) Ranjbar, M ; Kalhori, H ; Mahdavi, S. M ; Zad, A. I ; Sharif University of Technology
    In this study, WO 3 nanocrystallites were first produced by laser ablation of W target in deionised water. To synthesize palladium, a PdCl 2 solution (0.2 g/L) was added to the liquid. Transmission electron microscope revealed successful synthesis of tungsten oxide nanocrystallites along with the production of Pd and core-shell Pd/WO3 nanoparticles. Gasochromic behavior was examined by hydrogen bubbling into Pd/WO 3 liquid in which a transition to blue absorbing state was observed. Optical absorption spectra of the colored liquid represented different sharp small polaron absorbing peaks below 3 eV and the peaks intensity was observed to be varied with Pd:WO 3 ratio. Time variations of... 

    Investigation on the solubility of SO2 and CO2 in imidazolium-based ionic liquids using NPT Monte Carlo simulation

    , Article Journal of Physical Chemistry B ; Volume 115, Issue 46 , 2011 , Pages 13599-13607 ; 15206106 (ISSN) Ghobadi, A. F ; Taghikhani, V ; Elliott, J. R ; Sharif University of Technology
    The solubility of sulfur dioxide (SO2) and carbon dioxide (CO2) at P = 1 bar in a series of imidazolium-based room-temperature ionic liquids (RTILs) is calculated by Monte Carlo simulation in NPT ensemble using the OPLS-UA force field and Widom particle insertion method. The studied ILs were 1-butyl-3-methylimidazolium ([bmim]+) tetrafluoroborate ([BF4]-), [bmim]+ hexafluorophosphate ([PF 6]-), [bmim]+ bromide ([Br]-), [bmim]+ nitrate ([NO3]-), [bmim]+ bis-(trifluoromethyl) sulfonylimide ([Tf2N]-), and 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF4]). To validate the simulations, the liquid density of studied ILs and the solubility of CO2 in [bmim][PF6] was compared with... 

    Preparation and characterization of nanocrystalline and mesoporous strontium titanate thin films at room temperature

    , Article Journal of Coatings Technology Research ; Volume 8, Issue 5 , July , 2011 , Pages 585-593 ; 15470091 (ISSN) Mohammadi, M. R ; Fray, D. J ; Sharif University of Technology
    The low temperature perovskite-type strontium titanate (SrTiO 3) thin films and powders with nanocrystalline and mesoporous structure were prepared by a straightforward particulate sol-gel route. The prepared sol had a narrow particle size distribution with hydrodynamic diameter of about 17 nm. X-ray diffraction (XRD) revealed that the synthesized powders had a perovskite-SrTiO 3 structure with preferable orientation growth along the (1 0 0) direction. TEM images showed that the average crystallite size of the powders annealed in the range 300-800°C was around 8 nm. FE-SEM analysis and AFM images revealed that the deposited thin films had mesoporous and nanocrystalline structure with the...