Search for: room-temperature
Total 131 records
, M.Sc. Thesis Sharif University of Technology ; Vosoughi, Nasser
High purity Germanium (HPGe) detector is a sub branch of semiconductor detectors which has very good resolution, very little dead time, able tobuild in large dimensions and suitable for any condition that it is using in vast fields from space investigation to radiation therapy. this detector is usually used to detecting gamma radiations furthermore the best resolution can be attained with decreasing leakage current. for analyzing about operation of the HPGe detector, it needs to initiate a model of this detector. in this studing has been used modelGEM-15190,POP-TOP which is built by ortec company. for initiating, it was used liquid nitrogen and accessory equipments like high voltage supply,...
Palladium immobilized onto functionalized magnetic nanoparticles as robust catalysts for amination and room-temperature ullmann homocoupling of aryl halides: a walk around the C−F bond activation, Article Asian Journal of Organic Chemistry ; Volume 7, Issue 4 , 2018 , Pages 802-809 ; 21935807 (ISSN) ; Pourkaveh, R ; Karimi, A ; Ayati, E ; Sharif University of Technology
Wiley-VCH Verlag 2018
The first example of a heterogeneous catalytically active system for Buchwald–Hartwig and Ullmann homocoupling of unactivated aryl halides (fluorobenzene) is presented. The novel magnetic heterogeneous palladium catalyst was synthesized by immobilization of palladium ions onto an aminopyridine-functionalized Fe3O4. The catalyst was fully characterized by FTIR spectroscopy, temperature-programmed reduction, thermogravimetric analysis, CHN elemental analysis, transmission electron microscopy, field-emission scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, and atomic absorption spectroscopy. By using this catalyst system, various types of primary and...
Cobalt-copper ferrite nanoparticles catalyzed click reaction at room-temperature: green access to 1,2,3-triazole derivatives, Article ChemistrySelect ; Volume 3, Issue 9 , 2018 , Pages 2586-2593 ; 23656549 (ISSN) ; Pourkaveh, R ; Ahangarpour, M ; Sharif University of Technology
A typical Cobalt-Copper ferrite nanoparticles (CoCuFe2O4) was used as a catalyst for one-pot [3+2] cycloaddition of alkyl azides with alkynes at room temperature in green media. These nanoparticles were synthesized by using co-precipitation method and were fully characterized by physiochemical technique. By this catalyst system, various types of alkyl halides were coupled with alkynes efficiently to furnish 1,2,3 triazoles in excellent yields within short reaction time. The requirement on energy and time for the Click reaction extremely minimized in this method compared to previously reported reactions as an inevitable trend in development of green chemistry. Using green solvent, inexpensive...
Efficient synthesis of propargylamines in aqueous media catalyzed by au nanoparticles under ambient temperature, Article ChemistrySelect ; Volume 3, Issue 7 , 2018 , Pages 2053-2058 ; 23656549 (ISSN) ; Pourkaveh, R ; Sharif University of Technology
An eco-friendly gold-based catalyst supported on proline decorated montmorillonite was synthesized. The catalyst was characterized by combination of Fourier-transform infrared spectroscopy (FT-IR), Field Emission Scanning Electron Microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Brunauer–Emmett Teller (BET) surface area analysis, Ultraviolet–visible spectroscopy (UV-Vis), Energy-dispersive X-ray spectroscopy (EDX), thermo gravimetric analysis (TGA) and atomic absorption spectroscopy (AAS) techniques. The synthesized catalyst was found to be a highly efficient heterogeneous nanocatalyst for multi component A3 coupling reaction of aldehyde, amine and alkyne...
Microstructural study of a High Bainite Dual Phase (HBDP) steel austempered at different temperatures, Article Defect and Diffusion Forum ; Volume 297-301 , 2010 , Pages 62-67 ; 10120386 (ISSN); 3908451809 (ISBN); 9783908451808 (ISBN) ; Ekrami, A ; Sharif University of Technology
Trans Tech Publications Ltd 2010
4340 steel bars were austenitized at 850°C for 1 hour followed by heating at 700°C (ferrite and austenite region) for 90 min and quenching into a salt bath with different temperatures of 300, 350, 400 and 450°C. The steel bars were held for 1 hour at these temperatures before air cooling to room temperature. Various ferrite-bainite microstructures with 34% volume fraction of ferrite and different bainite morphologies were obtained. The results of SEM studies showed that by increasing the austempering temperature, the morphology of bainite varies from lower to upper bainite. According to the T-T-T diagram of the studied steel, the bainite transformation will not complete for the holding time...
Efficient and green oxidative degradation of methylene blue using Mn-doped ZnO nanoparticles (Zn
Journal of Experimental Nanoscience
Volume 10, Issue 16
; Amini, M
; Boghaei, D. M
Sharif University of Technology
Taylor and Francis Ltd 2015
Mn-doped ZnO nanoparticles, Zn
1−xMn xO, were synthesised by a polyethylene glycol (PEG) sol–gel method and the physicochemical properties of compounds were characterised by atomic absorption spectroscopy (AAS), energy-dispersive X-ray analysis, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The catalytic degradation of an organic dye, methylene blue (MB), in the presence of Zn 1−xMn xO as the catalyst and hydrogen peroxide (H 2O 2) as the oxidant at room temperature in water has been studied. Effects of oxidant, catalyst amount, catalyst composition, pH value of the solution and an OH-radical...
Structural, magnetic, and optical properties of zinc-and copper-substituted nickel ferrite nanocrystals, Article Journal of Superconductivity and Novel Magnetism ; Volume 25, Issue 7 , 2012 , Pages 2443-2455 ; 15571939 (ISSN) ; Daadmehr, V ; Rezakhani, A. T ; Akbarnejad, R. H ; Gholipour, S ; Sharif University of Technology
Ferrite nanocrystals are an interesting material due to their rich physical properties. Here we add nonmagnetic dopants Zn and Cu to nickel ferrite nanocrystals, Ni1-xMxFe2O4 (0 ≤ x ≤ 1, M = Cu, Zn), and study how relevant properties of the samples are modified accordingly. Basically, these dopings cause a rearrangement of Fe +3 ions into the two preexisting octahedral and tetrahedral sites. In fact, this, we show, induces pertinent magnetic properties of the doped samples. In the case of the Cu-doping, the Jahn-Teller effect also emerges, which we identify through the Fourier Transform Infra-Red Spectroscopy of the samples. Moreover, we show an increase in the lattice parameters of the...
Tribological characterization of electroless Ni-10% P coatings at elevated test temperature under dry conditions, Article International Journal of Advanced Manufacturing Technology ; Volume 62, Issue 9-12 , October , 2012 , Pages 1063-1070 ; 02683768 (ISSN) ; Ghasemi, H. R ; Ziaei, A. A ; Shahriari, D ; Sharif University of Technology
An experimental study of wear characteristics of electroless Ni-10% P coating sliding against hard AISI 52100 steel pin is investigated. Experiments are carried out at room and 550°C temperatures. Heat treatment effects on tribological behavior of this coating are studied. The wear surface and the microstructure of the coatings are analyzed using optical microscopy, scanning electron microscopy, energy dispersion analysis X-ray, and microhardness testing equipment. It is observed that the forming of continuous oxide film on contacting surfaces of pin and disk improves wear resistance and decreases friction coefficient of the Ni-10% P coating. The results indicate that the wear resistance of...
Microstructure and phase transformation behavior of a stress-assisted heat-treated Ti-Rich NiTi shape memory alloy, Article Journal of Materials Engineering and Performance ; Volume 21, Issue 8 , August , 2012 , Pages 1806-1812 ; 10599495 (ISSN) ; Rezaei, E ; Sharif University of Technology
In this study, the effects of stress-assisted heat treatment on the microstructure and phase transformation of a Ti-rich (Ti-49.52 at.% Ni) shape memory alloy were investigated. For this purpose, the alloy was heat treated at temperature of 500 °C for 10 h under applied stresses of 100 and 200 MPa. XRD, TEM, and repeated thermal cycling were employed to study the microstructure and transformation behavior of the heat-treated materials. Room temperature XRD diffractogram of the stress-free heat-treated material showed a weak reflection of austenite (B2), while that for the stress-assisted heat-treated materials had a high intensity implying the presence of residual austenite in the...
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 ; Mohammadi, M ; Shayegani Akmal, A. A ; Samadpour, M ; dehghani, M ; Parvazian, E ; Sharif University of Technology
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 ; Fathipour, M ; Faez, R ; Darvish, G ; Sharif University of Technology
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...
Solvent parameters effects on the second-order rate constants of the reaction of 2-chloro-3,5-dinitropyridine with aniline in aqueous solutions of alcohols, Article Progress in Reaction Kinetics and Mechanism ; Volume 31, Issue 2 , 2006 , Pages 117-127 ; 14686783 (ISSN) ; Masumpour, M. S ; Gholami, M. R ; Sharif University of Technology
Science Reviews Ltd 2006
Aromatic nucleophilic substitution reaction kinetics of 2-chloro-3,5-dinitropyridine with aniline was studied in aqueous solutions of methanol, ethanol, and 2-propanol at room temperature. The obtained results for aqueous solutions indicate that the second-order rate constants are in order of 2-propanol>ethanol>methanol with a maximum at water mole fraction of 0.9. The influence of solvent parameters including normalized polarity (E TN), dipolarity/polarisability (π*), and hydrogen bond donor acidity (α) on the second-order rate constants were investigated and multiple regressions gave much better results with regard to single parameter regressions. Dipolarity/polarisability and hydrogen...
Mechanical behavior during aging of plastically deformed AA6061-SiCp composite in different temperatures, Article Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications ; Volume 226, Issue 4 , 2012 , Pages 322-329 ; 14644207 (ISSN) ; Serajzadeh, S
In this study, the kinetics of aging in AA6061 and AA6061 with 5% volume fraction SiCp were studied and compared. The composite was first produced and homogenized using stir casting technique followed by hot extrusion with the ratio of 18:1. Then, both AA6061 and the composite were aged at three different temperatures including room temperature, 170 °C and 240 °C, while mechanical properties during aging were evaluated employing hardness measurements and tensile testing. Moreover, in order to assess the effect of plastic deformation on the kinetics of aging, a series of samples were first deformed by equal-channel angular pressing immediately after solution treatment and then aged in the...
Regiochemistry of nucleophilic substitution of pentachloropyridine with N and O bidentate nucleophiles, Article New Journal of Chemistry ; Volume 39, Issue 6 , 2015 , Pages 4398-4406 ; 11440546 (ISSN) ; Ranjbar Karimi, R ; Kia, R ; Sharif University of Technology
Royal Society of Chemistry 2015
Site reactivity of some enol-imines derived from N-aryl formamides with pentachloropyridine under basic conditions in dry CH
3CN was investigated. The aromatic nucleophilic substitution of pentachloropyridine with enol-imines occurs at the 4-position of pyridine ring by both oxygen and nitrogen site of enol-imines. Nucleophilic attack by the oxygen of enol-imine gave corresponding oximino compounds as a mixture of E- and Z-isomers. In contrast, nucleophilic attack by the nitrogen of enol-imine gave the unexpected N,N-di-substituted aryl compounds. The structures of all the compounds were confirmed by IR, 1H NMR, 13C NMR and 19F NMR spectroscopy as well as elemental analysis and...
Inverted perovskite solar cells based on lithium-functionalized graphene oxide as an electron-transporting layer, Article Chemical Communications ; Volume 53, Issue 10 , 2017 , Pages 1630-1633 ; 13597345 (ISSN) ; Mohammadi, M. R ; Lianos, P ; Sharif University of Technology
Royal Society of Chemistry 2017
Perovskite solar cells with an inverted p-i-n architecture were constructed under ambient conditions by employing materials of lower cost than standard cells. Thus, graphene oxide was used as a hole transporting material and Li-modified graphene oxide as an electron transporting material, while Al was used as a counter electrode. A maximum solar conversion efficiency of 10.2% was achieved by adding a Ti-based sol on the top of the Li-modified graphene oxide layer. © The Royal Society of Chemistry
Long-term stability of dye-sensitized solar cells using a facile gel polymer electrolyte, Article New Journal of Chemistry ; Volume 42, Issue 16 , 2018 , Pages 13256-13262 ; 11440546 (ISSN) ; Asgari Moghaddam, H ; Nouri, E ; Mohammadi, M. R ; Sharif University of Technology
Royal Society of Chemistry 2018
Herein, we demonstrate a facile low temperature approach to prepare a gel polymer electrolyte (GPE) based on the triiodide/iodide redox couple in a quasi-solid-state dye-sensitized solar cell (DSSC). Only one polymeric agent (i.e., hydroxypropyl cellulose (HPC)) is used for the preparation of a non-volatile GPE system for the standard liquid electrolyte containing 1-methyl-3-propylimidazolium iodide (MPII). The prepared GPE completely penetrates into a TiO2 photoanode at room temperature due to the uniform distribution of Ti, Ru and I elements in the cross-section of the electrode, forming an interpenetrating GPE/TiO2 network to access all dye molecules. The GPE with the optimum HPC : MPII...
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 ; 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...
Ballistic molecular transport through two-dimensional channels, Article Nature ; Volume 558 , 20 June , 2018 , Pages 420-423 ; 00280836 (ISSN) ; 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...
Catalyst-Free and Green Synthesis of Some Novel Benzamide Derivatives, Article Journal of Heterocyclic Chemistry ; Volume 52, Issue 6 , November , 2015 , Pages 1848-1857 ; 0022152X (ISSN) ; Rostami, M ; Mirkhani, V ; Moghadam, M ; Mohammadpoor Baltork, I ; Tangestaninejad, S ; Jamali Moghadam, A ; Kia, R ; Sharif University of Technology
In the present work, a simple, green, rapid, and catalyst-free procedure for the synthesis of benzamide derivatives by ring opening of azlactones with diamines such as ethylene diamine and 1,3-propylenediamine is described. The present method offers several advantages such as short reaction times, easy work-up, and mild reaction conditions in the absence of catalyst and any toxic solvent and material. In addition, the structure obtained by X-ray crystallography was compared with the theoretical results obtained by density functional theory using the B3LYP functional and cc-pVDZ basis sets
Novel one-pot synthesis of functionalized quinolines from isocyanides, aniline, and acetylene dicarboxylate via cu-catalyzed intramolecular C─H activation reactions, Article Journal of Heterocyclic Chemistry ; Volume 56, Issue 4 , 2019 , Pages 1254-1259 ; 0022152X (ISSN) ; Rezaee, E ; Jahani, M ; Tabatabai, S. A ; Sharif University of Technology
The one-pot synthesis of a novel class of substituted quinoline derivatives with good yields is achieved via the Cu-catalyzed intramolecular C─H activation reaction between isocyanides, aniline, and acetylene dicarboxylate in MeCN at room temperature. The existence of one-pot conditions, availability of a starting material-catalyst, the absence of column chromatography, and a high yield of products are among the advantages of this method. The structures are confirmed spectroscopically (1H NMR and 13C NMR, IR, and EI-MS) and through elemental analyses