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    The effects of oxidation conditions on structural and electrical properties of silicon nanoparticles obtained by ultra-low-energy ion implantation

    , Article Nanotechnology ; Volume 16, Issue 12 , 2005 , Pages 2987-2992 ; 09574484 (ISSN) Grisolia, J ; Shalchian, M ; Ben Assayag, G ; Coffin, H ; Bonafos, C ; Schamm, S ; Atarodi, S. M ; Claverie, A ; Sharif University of Technology
    In this paper, we have studied the effect of annealing under slightly oxidizing ambient (N2+O2) on the structural and electrical characteristics of a limited number of silicon nanoparticles embedded in an ultra-thin SiO2 layer. These nanoparticles were synthesized by ultra-low-energy (1 keV) ion implantation and annealing. Specific experimental methods have been used to characterize the ncs populations. They include transmission electron microscopy (TEM) Fresnel imaging for evaluating the distances and widths of interest and spatially resolved electron energy loss spectroscopy (EELS) using the spectrum-imaging mode of a scanning transmission electron microscope (STEM) to measure the size... 

    Room temperature synthesis of highly crystalline TiO2 nanoparticles

    , Article Materials Letters ; Volume 92 , February , 2013 , Pages 287-290 ; 0167577X (ISSN) Sasani Ghamsari, M ; Radiman, S ; Azmi Abdul Hamid, M ; Mahshid, S ; Rahmani, S ; Sharif University of Technology
    Hydrolysis of titanium isopropoxide alcoholic solution has been used to prepare the crystallized TiO2 nanoparticles at low temperature. Concentration ratio was used to control the pathway of sol-gel process and change the physical characteristics of TiO2 nanopowders. The crystallinity, morphology and size of aged TiO2 nanopowders were studied by X-ray diffraction and Scanning Electron Microscopy (SEM). FTIR and, Thermo-Gravimetric (TG) analysis were used to identify the functional groups and thermal behavior of prepared samples. Experimental results have shown that high crystalline TiO2 nanomaterial with anatase polymorph can be obtained at room temperature. It has been found that the... 

    Ag3PO4/BiPO4 p-n heterojunction nanocomposite prepared in room-temperature ionic liquid medium with improved photocatalytic activity

    , Article Materials Science in Semiconductor Processing ; Volume 39 , 2015 , Pages 506-514 ; 13698001 (ISSN) Mohaghegh, N ; Rahimi, E ; Gholami, M. R ; Sharif University of Technology
    Elsevier Ltd  2015
    Abstract A visible-light-active Ag3PO4/BiPO4 nanocomposite with a p-n heterojunction structure was fabricated via a co-precipitation hydrothermal process using 2-hydroxylethylammonium formate (RTIL) as a room-temperature ionic liquid. The resulting catalysts were characterized by various techniques. The photocatalytic activity of the photocatalysts was evaluated by the photodegradation of phthalocyanine Reactive Blue 21 (RB21) under both visible and UV light irradiations. The results reveal that the heterojunction composite prepared in RTIL noticeably exhibited an improvement in both efficiency and rate of RB21 photodegradation in comparison with pure Ag3PO4 and BiPO4. The enhanced... 

    , M.Sc. Thesis Sharif University of Technology Zamzamian, Mehrdad (Author) ; Vosoughi, Nasser (Supervisor)
    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,... 

    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 Bayat, A ; Shakourian-Fard, M ; Hashemi, M. M ; Sharif University of Technology
    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 Ghadim, E. E ; Rashidi, N ; Kimiagar, S ; Akhavan, O ; Manouchehri, F ; Ghaderi, E ; Sharif University of Technology
    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... 

    Threshold characteristics analysis of InP-based PhC VCSEL with buried tunnel junction

    , Article 2013 21st Iranian Conference on Electrical Engineering ; May , 2013 , Page(s): 1 - 4 ; 9781467356343 (ISBN) Marjani, S ; Hosseini, S. E ; Faez, R ; Sharif University of Technology
    The comprehensive optical-electrical-gain-thermal self-consistent model of the 1.55 μm AlGaInAs Photonic Crystal vertical cavity surface emitting diode lasers (PhC VCSELs) with buried tunnel junction (BTJ) has been applied to optimize its threshold characteristics. It shows that, for 5 μm devices, the room temperature (RT) threshold current equal to only 0.59 mA and maximum operating temperature equal to as much as 380 K. Results suggest that, the 5 μm AlGaInAs PhC VCSELs seem to be the most optimal ones for light sources in high performance optical communication systems  

    Influence of martensite volume fraction on impact properties of triple phase (TP) steels

    , Article Journal of Materials Engineering and Performance ; Volume 22, Issue 3 , 2013 , Pages 823-829 ; 10599495 (ISSN) Zare, A ; Ekrami, A ; Sharif University of Technology
    Ferrite-bainite-martensite triple phase (TP) microstructures with different volume fractions of martensite were obtained by changing heat treatment time during austempering at 300 C. Room temperature impact properties of TP steels with different martensite volume fractions (VM) were determined by means of Charpy impact testing. The effects of test temperature on impact properties were also investigated for two selected microstructures containing 0 (the DP steel) and 8.5 vol.% martensite. Test results showed reduction in toughness with increasing VM in TP steels. Fracture toughness values for the DP and TP steels with 8.5 vol.% martensite were obtained from correlation between fracture... 

    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) Baghalha, M ; Sharif University of Technology
    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) Koohbor, B ; Serajzadeh, S
    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 leaching kinetics of an oxide gold ore with iodide/iodine solutions

    , Article Hydrometallurgy ; Volume 113-114 , 2012 , Pages 42-50 ; 0304386X (ISSN) Baghalha, M ; Sharif University of Technology
    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, since gold-iodide complexes 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 h. When the iodate was partially converted to iodine by adding HCl to the solution, gold... 

    Synthesis, structure and photophysical properties of binuclear methylplatinum complexes containing cyclometalating 2-phenylpyridine or benzo{h}quinoline ligands: A comparison of intramolecular Pt-Pt and π-π Interactions

    , Article Dalton Transactions ; Volume 40, Issue 36 , 2011 , Pages 9123-9130 ; 14779226 (ISSN) Jamali, S ; Czerwieniec, R ; Kia, R ; Jamshidi, Z ; Zabel, M ; Sharif University of Technology
    The binuclear cyclometalated complexes [Pt2Me 2(ppy)2(μ-dppm)], 1a, and [Pt2Me 2(bhq)2(μ-dppm)], 1b, in which ppy = 2-phenylpyridyl, bhq = benzo{h}quinoline and dppm = bis(diphenylphosphino)methane, were synthesized by the reaction of [PtMe(SMe2)(ppy)] or [PtMe(SMe 2)(bhq)] with 1/2 equiv of dppm at room temperature, respectively. Complexes 1a and 1b were fully characterized by multinuclear (1H, 31P, 13C, and 195Pt) NMR spectroscopy and were further identified by single crystal X-ray structure determination. A comparison of the intramolecular Pt-Pt and π-π interactions in complexes 1a and 1b has been made on the basis of data on crystal structures and wave functions analysis. The binuclear... 

    An investigation on diffusion bonding of aluminum to copper using equal channel angular extrusion process

    , Article Materials Letters ; Volume 65, Issue 12 , June , 2011 , Pages 1862-1864 ; 0167577X (ISSN) Eslami, P ; Taheri, A. K ; Sharif University of Technology
    A new method for production of bimetallic rods, utilizing the equal channel angular extrusion (ECAE) process has been introduced before by previous researchers, but no attempt has been made to assess the effect of different temperatures and holding times in order to achieve a diffusional bond between the mating surfaces. In present research copper sheathed aluminum rods have been ECAEed at room temperature and subsequently held at a constant ECAE pressure, at different temperatures and holding times to produce a diffusional bond between the copper sheath and the aluminum core. The bonding quality of the joints was examined by shear strength test and a sound bonding interface was achieved.... 

    Hybrid nanomaterials containing PAMAM, polyrotaxane and quantum dot blocks

    , Article Nano ; Volume 6, Issue 3 , June , 2011 , Pages 239-249 ; 17932920 (ISSN) Adeli, M ; Sarabi, R. S ; Sadeghi, E ; Sharif University of Technology
    Pseudopolyrotaxanes, Ps-PR, consisting of α-cyclodextrin rings, polyethylene glycol axes and end triazine groups were prepared and then were capped by amino-functionalized quantum dots, NH 2-QDs, to achieve polyrotaxanes. The amino-functionalized QDs stoppers of polyrotaxanes were used as core to synthesize polyamidoamine, PAMAM, dendrons divergently and hybrid nanomaterials were obtained. Synthesized hybrid nanomaterials were characterized by different spectroscopy, microscopy and thermal analysis methods. They were freely soluble in water and their aqueous solutions were stable at room temperature over several months. Due to their biocompatible backbone, high functionality and water... 

    Effect of rolling speed on the occurrence of strain aging during and after warm rolling of a low-carbon steel

    , Article Journal of Materials Science ; Volume 45, Issue 13 , July , 2010 , Pages 3405-3412 ; 00222461 (ISSN) Koohbor, B ; Ohadi, D ; Serajzadeh, S ; Akhgar, J. M ; Sharif University of Technology
    In this study, effect of rolling speed on strain aging phenomena in warm rolling of a carbon steel has been investigated. For this purpose, by using a mathematical model and predicting temperature and strain rate fields, the possibility of occurrence of dynamic strain aging during the warm rolling was first evaluated. In the next stage, warm-rolled samples were aged up to 11 months at room temperature for studying the kinetics of static strain aging, while mechanical tests as well as microstructural evolutions have been performed to determine the effect of strain aging on material behavior. The results indicate that dynamic strain aging may not occur for the employed rolling program;... 

    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) Nouri, E ; 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) Ma'alinia, A ; 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... 

    Regioselective bromination of aromatic amines and phenols using N-benzyl-DABCO tribromide

    , Article Synthetic Communications ; Volume 39, Issue 23 , 29 October , 2009 , Pages 4212-4220 ; 00397911 (ISSN) Matloubi Moghaddam, F ; Zargarani, D ; Sharif University of Technology
    N-Benzyl-DABCO tribromide, a stable, solid organic ammonium tribromide, has been used as a bromine source for the regioselective and high-yielding bromination of aromatic amines and phenols. Mono-bromination proceeds well in the presence of a stoichiometric amount of bromine source at room temperature  

    Monitoring temperature variation of reactance capacitance of water using a cylindrical cell probe

    , Article Journal of Applied Sciences ; Volume 9, Issue 4 , 2009 , Pages 752-758 ; 18125654 (ISSN) Behzadi, G ; Golnabi, H ; Sharif University of Technology
    In this study by using a capacitive cell probe the temperature variation of the electrical properties of the water liquids is investigated. Variation of the reactance capacitance parameter of liquids with temperature in the range of 17-60°C is measured for the plain water and water mixtures. The temperature variations of the capacitance for the cool distilled and tap water samples are studied for the range of 17-29°C obtained. Present results indicate an averaged variation of 4.69 μF/°C for the distilled water and 3.24 μF/°C for tap water in warm up process to a near room temperature. The cooling behaviors for the warm mineral, tap and salt water liquids are also investigated in this study.... 

    Stereoselective synthesis ofβ-Amino ketones via direct mannich-type reaction catalyzed with SO 2- 4/TiO 2 and SO 2- 4/nano TiO 2

    , Article Synthetic Communications ; Volume 39, Issue 24 , 2009 , Pages 4441-4453 ; 00397911 (ISSN) Samet, M ; Eftekhari Sis, B ; Mahmodi Hashemi, M ; Farmad, F ; Sharif University of Technology
    At room temperature, SO 2- 4/nano-TiO 2 efficiently catalyze the direct Mannich-type reaction of varieties of in situ-generated aldimines using aldehydes and anilines with ketones in a three-component reaction under solvent-free conditions. The reaction proceeds rapidly and affords the correspondingβ-amino ketones in good to high yields with good to excellent stereoselectivity. The catalyst can be recycled for subsequent reactions without any appreciable loss of efficiency