Search for: synthesis
0.007 seconds
Total 1040 records

    Synthesis and thermoluminescence of ZnS:Mn2+ nanoparticles

    , Article AIP Conference Proceedings: First International Conference on Nanotechnology and Its Applications, Sharjah, 10 April 2007 through 12 April 2007 ; Volume 929 , 2007 , Pages 128-131 ; 0094243X (ISSN) ; 0735404399 (ISBN); 9780735404397 (ISBN) Zahedifar, M ; Taghavinia, N ; Aminpour, M ; Sharif University of Technology
    The controlled chemical method has been used for synthesis of Mn doped ZnS nanoparticles. Optical absorption studies showed that increasing of surfactant density, from 0.0001 to 0.5 mol/lit., causes the size of nanoparticles to decrease from 4.8 nm to about 3 nm and the band gap width to increase from 4.15 to 4.50 eV. Also increasing the temperature during the synthesis process caused the nanoparticle size to be increased. As a new result we observed a thermoluminescence (TL) glow peak at about 475 K, with its intensity depending on concentration of the Mn dopant. Activation energy of this glow peak was obtained to be about 0.6eV. A discussion of the obtained results is also presented. ©... 

    Microwave and BF3 promoted rearrangement of allyloxycoumarins to allylcoumarins and dihydrofurocoumarins

    , Article Heterocycles ; Volume 55, Issue 9 , 2001 , Pages 1805-1812 ; 03855414 (ISSN) Saidi, M. R ; Rajabi, F ; Sharif University of Technology
    Japan Institute of Heterocyclic Chemistry  2001
    Allyl, crotyl, methallyl and cinamyl ethers of 4-hydroxy-, 7-hydroxy-, and 4-methyl-7-hydroxycoumarins have been efficiently synthesized and rearranged to substituted allylcoumarins under microwave irradiation. Irradiation of allylcoumarins in the presence of BF3/ether directly produced substituted dihydrofurocoumarins in good yields  

    Welding of Al alloys through in situ fabrication of Al3Ni intermetallic compound using combustion synthesis

    , Article Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry ; Volume 43, Issue 10 , Dec , 2013 , Pages 1390-1396 ; 15533174 (ISSN) Motlagh, E. B ; Nasiri, H ; Khaki, J. V ; Mofrad, R. N ; Mohammadtaheri, M ; Sharif University of Technology
    The exothermic reactions in Al+Ni system were used as a power source for welding of Al1100 alloy so that the obtained joint was reinforced with in situ produced Al3Ni intermetallic compound, simultaneously. Due to the combustion heat, the surfaces of the plates were melted down which, in turn, eventuated in formation of a strong surficial bond. The cross sections of joints were analyzed using optical microscopy, EDS-equipped scanning electron microscopy (SEM), and X-ray diffraction experiments. XRD and EDS results represented the Al3Ni intermetallic compound as the reaction product. The compressive shear strength of the joint was 20 MPa  

    Rapid synthesis of hydroxyapatite nanopowders by a microwave-assisted combustion method

    , Article Journal of Ceramic Processing Research ; Volume 13, Issue 3 , Jan , 2012 , Pages 221-225 ; 12299162 (ISSN) Bovand, N ; Rasouli, S ; Mohammadi, M. R ; Bovand, D ; Sharif University of Technology
    Nano bioactive hydroxyapatite (Ca 10(PO 4) 6(OH) 2, HAp) ceramic powders have been synthesized by a microwave-assisted combustion method. The powders were synthesized using calcium nitrate tetrahydrate (as the source of calcium) and sodium phosphate dibasic anhydrous (as the source of phosphate ions). Glycine, citric acid and urea were used as fuesl. The influence of the fuel type on the structure and morphology of the samples was studied. Results by X-ray diffraction and Fourier-transform infrared spectroscopy showed the formation of hydroxyapatite as a major phase for all the samples. Using the Scherrer formula, the average crystallite size was found to be in the range of 10 to 28 nm.... 

    Straightforward and highly efficient catalyst-free one-pot synthesis of dithiocarbamates under solvent-free conditions

    , Article Organic Letters ; Volume 8, Issue 23, 9 November 2006, Pages 5275-5277 Azizi, N. (Najmodin) ; Aryanadab, F ; Saidi, M. R ; Sharif University of Technology
    A highly efficient and simple synthesis of dithiocarbamates is possible based on the one-pot reaction of amines, CS2, and alkyl halides without using a catalyst under solvent-free conditions. The mild reaction conditions, high yields, and broad scope of the reaction illustrate the good synthetic utility of this method. The reaction is a highly atom-economic process for production of S-alkyl thiocarbamates and successfully can be used in high quantities in the pharmaceutical or agrochemical industries  

    Synthesis, chemical and thermal characterization of poly(cis-2-butenylene oxalate) [electronic resource]

    , Article International Journal of Polymeric Materials and Polymeric Biomaterials ; Volume 46, Issue 3-4, 2000 Pourdjavadi, A. (Ali) ; Zohuriaan-Mehr, M. J ; Rezai, N ; Sharif University of Technology
    A non-terminated, low molecular weight, highly crystalline, linear aliphatic polyester was successfully synthesized via ester-interchange polycondensation of cis-2-butene-1,4-diol and diethyl oxalate by using of lead (II) oxide as the catalyst. No decarboxylation occurred during the optimized polymerization. Structural and Chemical identification was performed by elemental analysis, FTIR, 'H-NMR, and Mass spectroscopy. Some macrocyle species were detected in the product, according to GPC. Fragmentation patterns were suggested for the main m/e's of the mass spectrum. Thermal characterization was performed by DSC and TGA. It was found that the overall thermal stability of the polyester is... 

    Influence of polyaniline synthesis conditions on its capability for removal and recovery of chromium from aqueous solution

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 30, Issue 3 , 2011 , Pages 97-100 ; 10219986 (ISSN) Riahi Samani, M ; Borghei, S. M ; Olad, A ; Chaichi, M. J ; Sharif University of Technology
    Absorptive characteristics of polyaniline synthesized in different solvents were studied. Water and mixture of water with other solvents were implemented for polyaniline synthesis. Synthesized polyanilines in powder shape is used as an adsorbent to remove toxic hexavalent chromium from aqueous solutions. Experiments were conducted in batch mode. Removal mechanism involving polyaniline is the combination of surface adsorption and reduction. The kind of solvent used at synthesizing stage can affect the capacity of produced polyanilines for removal of heavy metals including chromium. Synthesized polyaniline in water had the maximum chromium removal efficiency. The morphology study of... 

    Controlled crystallization of LTA zeolitic nanoparticles from a clear solution using organic template

    , Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 30, Issue 2 , 2011 , Pages 9-14 ; 10219986 (ISSN) Esmaeili, N ; Kazemian, H ; Bastani, D ; Sharif University of Technology
    LTA Zeolite nanoparticles was successfully synthesized from clear solution under controlled conditions using hydrothermal method using tetramethyl ammonium hydroxide as a structural directing agent. The as-synthesized LTA zeolite particles were characterized by powder X-ray Diffraction (XRD) analysis, Scanning Electron Microscopy (SEM), Fourier Transform InfraRed (FT-IR) spectroscopy, Energy Dispersive X-ray (EDX) analysis and surface area measuring technique of Brunauer, Emmett and Teller (BET). XRD patterns and FT-IR spectra were ascertained the formation of pure crystalline phase of 4A (i.e. LTA) zeolite. SEM micrograph was shown particles size in the range of 60 -170 nm with uniform... 

    The possibilities of palladium-catalyzed aromatic cyanation in aqueous media

    , Article Inorganic Chemistry Communications ; Volume 72 , 2016 , Pages 86-90 ; 13877003 (ISSN) Vafaeezadeh, M ; Mahmoodi Hashemi, M ; Karbalaie Reza, M ; Sharif University of Technology
    Owing to the inherent incompatibility with water, cyanation of aryl halides may be the most challenging category of palladium-catalyzed coupling reactions. The major challenges are attributed to the catalyst deactivation by the soluble cyanide (CN−) ions and desirable conversions only could be obtained by employing toxic organic solvents. The current minireview highlights mechanistic insights and breakthrough achievements for this reaction in the aqueous media  

    Continuous synthesis of plate-like silica microparticles using microfluidics

    , Article Journal of Flow Chemistry ; Volume 9, Issue 3 , 2019 , Pages 161-174 ; 2062249X (ISSN) Tamtaji, M ; Mohammadi, A ; Sharif University of Technology
    Springer International Publishing  2019
    The synthesis of plate-like silica particles, which are of importance for a variety of applications, are mainly based on the widely adopted method of the sol-gel reaction of silicon alkoxides in traditional batch-wise instrumentation. In this study, continuous-flow synthesis of amorphous plate-like silica particles is reported through combining droplet-based microfluidics and the sol-gel reaction of tetraethyl orthosilicate. The reaction was conducted at the surface of oil droplets, comprising tetraethyl orthosilicate (TEOS), suspended in acidic (HCl) water, resulting in silica particles on the surface of the droplets, leaving the device with outlet flow. The synthesized particles had... 

    Nanodeposition and characterization of cobalt particles inside synthesized faujasitic support for preparing a catalyst for fischer-tropsch reaction

    , Article 18th International Congress of Chemical and Process Engineering, CHISA 2008, Prague, 24 August 2008 through 28 August 2008 ; 2008 Fotovat, F ; Kazemian, H ; Kazemeini, M ; Sharif University of Technology
    The importance of the gas-to-liquid process is increasing due to growing demand for a high quality, less expensive, and cleaner fuel. Faujasite zeolites, e.g,. zeolites type X and Y, are well-known catalysts in the petrochemical industry. Faujasitic supports (mainly X zeolites) were prepared via hydrothermal synthesis with different Si/Al ratios from pure chemical materials and fly ash as a source of silicon. A high quantity of cobalt oxides was deposited on supports by varying samples Si/Al ratios during the zeolite preparation procedure. Using fly ash in synthesizing the zeolitic support resulted in a A-X zeolite material with a very high cation exchange capability and final cobalt... 

    Chemistry, abundance, detection and treatment of per- and polyfluoroalkyl substances in water: a review

    , Article Environmental Chemistry Letters ; 2021 ; 16103653 (ISSN) Dadashi Firouzjaei, M ; Zolghadr, E ; Ahmadalipour, S ; Taghvaei, N ; Akbari Afkhami, F ; Nejati, S ; Elliott, M. A ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2021
    Per- and polyfluoroalkyl substances (PFAS) encompass a wide range of compounds containing carbon–fluorine bonds. Due the strength of this bond and the high electronegativity of fluorine atoms, PFAS display stability, wettability and other characteristics that are unique for industrial applications and products. However, PFAS induce adverse effects on the environment and human health. Here we review the chemistry, synthesis, properties, analysis, occurrence in water, filtration, removal and oxydation of PFAS. We highlight emerging hybrid treatments to remove PFAS from water. © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG  

    Electrochemical oxidation of catechol in the presence of 2-thiouracil: Application to electro-organic synthesis

    , Article Electrochemistry Communications ; Volume 5, Issue 8 , 2003 , Pages 706-710 ; 13882481 (ISSN) Shahrokhian, S ; Hamzehloei, A ; Sharif University of Technology
    Elsevier Inc  2003
    The electrochemical oxidation of catechol in the presence of 2-thiouracil (as a nucleophile) has been studied in aqueous solutions using cyclic voltammetry and controlled-potential coulometric techniques. The results indicate that catechol participating in a 1,4 (Michael) addition reaction converts to a new thiadiazafluorenone compound. The electrochemical synthesis of this compound has been successfully performed in an undivided cell in a good yield and purity and was characterized by IR, 1H and 13C NMR, mass spectrometry and elemental analysis. © 2003 Published by Elsevier B.V  

    A convenient synthesis of 3-formyl-2-thioacetamide-indole derivatives via the one-pot reaction of indolin-2-thiones, isocyanides and chloroacetylchloride

    , Article Tetrahedron Letters ; Volume 56, Issue 52 , 2015 , Pages 7190-7192 ; 00404039 (ISSN) Kiamehr, M ; Matloubi Moghaddamb, F ; Sadeghi Erami, M ; Sharif University of Technology
    An efficient method has been developed to construct 3-formyl-2-thioacetamide-indoles via a one-pot, two-step procedure involving condensation of isocyanides with indolin-2-thiones to give a 3-aminomethylene-indolin-2-thione intermediate, followed by regioselective reaction with chloroacetylchloride and subsequent hydrolysis  

    Optimization of a process synthesis superstructure using an ant colony algorithm

    , Article Chemical Engineering and Technology ; Volume 31, Issue 3 , 2008 , Pages 452-462 ; 09307516 (ISSN) Raeesi, B ; Pishvaie, M. R ; Rashtchian, D ; Sharif University of Technology
    The optimization of chemical syntheses based on superstructure modeling is a perfect way for achieving the optimal plant design. However, the combinatorial optimization problem arising from this method is very difficult to solve, particularly for the entire plant. Relevant literature has focused on the use of mathematical programming approaches. Some research has also been conducted based on meta-heuristic algorithms. In this paper, two approaches are presented to optimize process synthesis superstructure. Firstly, mathematical formulation of a superstructure model is presented. Then, an ant colony algorithm is proposed for solving this nonlinear combinatorial problem. In order to ensure... 

    Implementation and evaluation of statistical parametric speech synthesis methods for the Persian language

    , Article IEEE International Workshop on Machine Learning for Signal Processing, 18 September 2011 through 21 September 2011 ; September , 2011 , Page(s): 1 - 6 ; 9781457716232 (ISBN) Bahaadini, S ; Sameti, H ; Khorram, S ; Sharif University of Technology
    Scattered and little research in the field of Persian speech synthesis systems has been performed during the last ten years. Comprehensive framework that properly implements and adapts statistical speech synthesis methods for Persian has not been conducted yet. In this paper, recent statistical parametric speech synthesis methods including CLUSTERGEN, traditional HMM-based speech synthesis and its STRAIGHT version, are implemented and adapted for Persian language. CCR test is carried out to compare these methods with each other and with unit selection method. Listeners Score samples based on CMOS. The methods were ranked by averaging the CCR scores. The results show that STRAIGHT-based... 

    Synthesis of Graphene Nanosheets for Stem Cells Applications

    , M.Sc. Thesis Sharif University of Technology Shahsavar, Mahla (Author) ; Akhavan, Omid (Supervisor)
    Graphene nanogrids fabricated by graphene nanoribbons obtained through oxidative unzipping of multi-walled carbon nanotubes, used as two-dimensional selective templates for accelerated differentiation of human mesenchymal stem cells (hMSCs), isolated from umbilical cord blood, into osteogenic lineage. The biocompatible and hydrophilic graphene nanogrids showed high actin cytoskeleton proliferations that coinciding with patterns of the nanogrids. The amounts of proliferations found are slightly better than proliferation on hydrophilic graphene oxide (GO) sheets, and significantly higher than non-uniform proliferations on hydrophobic reduced graphene oxide (rGO) sheets and polydimethylsiloxane... 

    Synthesis of Graphene from Waste by Chemical Exfoliation and Study of It’s Physical Characteristics

    , M.Sc. Thesis Sharif University of Technology Mirsepah, Ali (Author) ; Akhavan, Omid (Supervisor)
    One atom thick layer of pure carbon in bonded and hexagonal lattice is named graphene. graphene has unique mechanical, optical, thermal and electrical properties and because of these properties has grabbed attention. graphene has been made from high pure graphite by different methods such as CVD(chemical vapor deposition) , chemical exfoliation , micromechanical cleavage and colloidal suspension. through these methods, green methods for synthesis of graphene, using eco-friendly reductants during synthesis of graphene instead of hydrazine and recently using waste(not graphite) are attractive for synthesis of graphene. Following this idea , a group has produced graphene from wastes such as... 

    Synthesis of Bromonitroalkenes and their Applications as Electrophile in the Reaction with Indoles

    , M.Sc. Thesis Sharif University of Technology Rostami Rad, Marzieh (Author) ; Mahmoodi Hashemi, Mohammad (Supervisor) ; Ziyaei Halimehjani, Azim (Co-Advisor)
    In this work Nitroolefins were made by aromatic aldehydes consisting of electron withdrawing and electron donor groups. Afterward β-Bromo-β-nitrostyrenes were produced from interaction between nitroolefins and brom, at suitable temperature. After providing ingredients, micheal reaction (Friedel-crafts Pseudo-alkylation) between nitroolefins and various nucleophiles such as indoles was investigated. Finally desired micheal products were achived with high efficiency  

    The Synthesis of Sialon Nano Particles by Sol- Gel Procedure and Investigation of Properties of its Erosion

    , M.Sc. Thesis Sharif University of Technology Fathi, Hamed (Author) ; Nemati, Ali (Supervisor) ; Halali, Mohammad (Supervisor)
    Sialons are materials which crystallize in four elements system (Si-Al-O-N). These materials have been widely observed by researchers because of their suitable properties like: high toughness and strength in high temperatures, high resistance to corrosion and stability in thermal shock. Because of these properties,Sialons are anti erosion materials. In this research, by controling the situations, mullite has been synthesized by sol-gel procedure. Then the powder has been ground by ballmill for 12 hours and by spex for 30 minutes. Then the produced powder was mixed with distinct amount of graphite and nano silica and was nitrided in the furnace at 1500 ̊C and was heated for 5 hours. Also...