Search for: absorption-spectroscopy
0.007 seconds
Total 47 records

    A novel highly dispersive magnetic nanocatalyst in water : Glucose as an efficient and green ligand for the immobilization of copper(II) for the cycloaddition of alkynes to azides

    , Article RSC Advances ; Volume 6, Issue 83 , 2016 , Pages 80234-80243 ; 20462069 (ISSN) Matloubi Moghaddam, F ; Saberi, V ; Kalhor, S ; Ayati, S. E ; Sharif University of Technology
    Royal Society of Chemistry 
    A new heterogeneous and highly dispersive nanocatalyst in water was prepared by the immobilization of Cu2+ onto glucose on Fe3O4. The catalyst was fully characterized by FT-IR, TGA, CHN, SEM, EDX, and atomic absorption spectroscopy. The synthesized catalyst was used in the synthesis of different derivatives of 1,2,3-triazole via a one-pot three-component reaction of alkynes, alkyl halides, and sodium azide. To the best of our knowledge, this novel catalyst adheres to the principles of green chemistry. The nanocatalyst could be recycled and reused in several runs without significant loss of activity  

    Experimental analysis and characterization of high-purity aluminum nanoparticles (Al-Nps) by electromagnetic levitation gas condensation (ELGC)

    , Article Nanomaterials ; Volume 10, Issue 10 , 2020 , Pages 1-15 Sabouni Tabari, R ; Halali, M ; Javadi, A. A ; Khanjanpour, M. H ; Sharif University of Technology
    MDPI AG  2020
    The production of high-purity aluminum nanoparticles (Al-NPs) is challenging due to the highly reactive nature of Al metals. Electromagnetic levitation gas condensation (ELGC) is a promising method to produce high-purity metallic particles as it avoids the interaction between molten metal and refractory-lined, which guarantees the removal of impurities such as oxygen (O). In this research, high-purity Al-NPs were successfully fabricated via ELGC process and fully characterized. The effects of power input and gas flow rate on particle size and distribution were analyzed using field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), and dynamic light... 

    A highly reactive and magnetic recyclable catalyst based on silver nanoparticles supported on ferrite for n-monoalkylation of amines with alcohols

    , Article Applied Organometallic Chemistry ; Volume 31, Issue 10 , 2017 ; 02682605 (ISSN) Bayat, A ; Shakourian Fard, M ; Nouri, P ; Mahmoodi Hashemi, M ; Sharif University of Technology
    Fe3O4@SiO2-Ag catalyst was found to be highly active and selective in the N-alkylation of amines with a variety of aromatic and linear alcohols. The heterogeneous nature of the Fe3O4@SiO2-Ag catalyst allows easy recovery and regeneration by applying an external magnet for six subsequent reaction cycles. The prepared catalyst was characterized using electron microscopy techniques, X-ray diffraction, vibrating sample magnetometry and atomic absorption spectroscopy. Copyright © 2017 John Wiley & Sons, Ltd  

    Palladium(II) immobilized onto the glucose functionalized magnetic nanoparticle as a new and efficient catalyst for the one-pot synthesis of benzoxazoles

    , Article Applied Organometallic Chemistry ; Volume 32, Issue 4 , April , 2018 ; 02682605 (ISSN) Matloubi Moghaddam, F ; Saberi, V ; Kalhor, S ; Veisi, N ; Sharif University of Technology
    John Wiley and Sons Ltd  2018
    Palladium(II) have been immobilized into the nano magnetic Fe3O4 which was functionalized with glucose in order to achieve a one-pot synthesis of 2-substituted benzoxazole derivatives with high yields in the diverse range of organic solvents. The nano catalyst is highly dispersive in polar solvents and can be easily recovered and reused for 6 runs without significant loss of its activity. Finally, the catalyst was fully characterized by FT-IR, TGA, CHN, SEM, EDX and atomic absorption spectroscopy. Copyright © 2018 John Wiley & Sons, Ltd  

    Synthetic study of symmetrical and unsymmetrical schiff base complexes of VO(IV) and Mn(III) derived from 2,2′-diaminobiphenyl

    , Article Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry ; Volume 35, Issue 4 , 2005 , Pages 261-267 ; 15533174 (ISSN) Boghaei, D. M ; Behzad, M ; Sharif University of Technology
    The symmetrical and unsymmetrical Schiff base complexes of VO(IV) and Mn(III) derived from 2,2′-diaminobiphenyl and derivatives of salicylaldehyde and 1-hydroxy-2-napnthaldehyde have been synthesized and characterized by elemental analysis, NMR, infrared and electronic absorption spectroscopies, and conductivity measurements. The reaction of the ligands with oxovanadium(IV) was found to be kinetically unfavored, probably due to the small ionic radius of the metal ion, which is not in accordance with the cavity size of the ligands. Copyright © 2005 Taylor & Francis, Inc  

    Design and Construct of Nd:YAG Laser and Using it in the Laser Ablation Process of Silver, Titanium and Zinc Element

    , M.Sc. Thesis Sharif University of Technology Gohari kamel, Nasser (Author) ; Sadighi Bonabi, Rasoul (Supervisor)
    The purpose of this project is to investigate the production of nano-micro metallic particles—of different elements—with different characteristics in size and optical property by employing a pulsed laser ablation processes in liquid medium. In this study, the means by which we build the laser, the experimental arrangement of the pulsed laser ablation process, the measurement of the absorption spectrum of generated nano-micro particles as well as the size of the particles are discussed.
    To satiate this aim, we have expressed the manner of constructing the Nd:YAG laser, the power supply circuits, along with its optics. This laser has some advantages such as high energy ~700mj, good... 

    The intra-cavity mode competition and laser absorption spectroscopy with CO2 laser

    , Article Optik ; Vol. 125, issue. 10 , 2014 , p. 2248-2255 Fuladvand, H ; Salehi, A ; Daneshfar, N ; Bahrampour, A ; Moghaddam, R. F ; Sharif University of Technology
    A mathematical model is developed for analysis the dynamics of an intra-cavity laser spectroscopy and mode competition using the CO2 laser as the coherent source. The governing equations of system are derived and effect of the absorbing material on the laser modes, as a time-dependent term is considered. Thus, the application of the CO2 laser for intra-cavity laser spectroscopy with considering an inhomogeneous medium and effect of the absorbing material is investigated  

    Application of an optimized SLW model to calculation of non-gray radiation heat transfer in a furnace

    , Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE), 13 November 2015 through 19 November 2015 ; Volume 8B-2015 , 2015 ; 9780791857502 (ISBN) Darbandi, M ; Abrar, B ; Schneider, G. E
    The spectral line based weighted sum of gray gases (SLW) model is considered as an advanced model, which can solve the radiative transfer equation (RTE) in non-gray participating media by dividing the absorption cross section spectrum into a limited number of intervals. Each interval is then treated as a gray gas medium, in which the attributed RTE should be solved separately. Therefore, the SLW model would be computationally more efficient than the other non-gray participating media solvers because it is faced with a small number of RTE solutions. In this work, we present a novel optimized SLW model and applied it to radiation heat transfer calculation in a model furnace. The current... 

    Fine tuning of the size of CdS nanoparticles synthesized by a photochemical method

    , Article Nanotechnology ; Volume 17, Issue 5 , 2006 , Pages 1230-1235 ; 09574484 (ISSN) Marandi, M ; Taghavinia, N ; Iraji zad, A ; Mahdavi, S. M ; Sharif University of Technology
    In this work, we propose a combined photochemical-chemical method that enables us to grow CdS nanoparticles with ångström precision. CdS nanoparticles were formed through a photo-induced reaction between CdSO 4 and Na2S2O3. Thioglycerol (C 3H8O2S) was used as the capping agent. Fine tuning of the size was subsequently carried out by controlling the pH of the solution. Optical absorption spectroscopy was mainly used to monitor the process of particle formation, and to measure the bandgap and size. X-ray diffraction spectra confirmed the optical sizes and demonstrated crystalline nanoparticles. In the presence of the capping agent there was a dark growth that was completely dependent on the pH... 

    Synthesis, characterization, electrochemical studies and catecholase-like activity of a series of mononuclear Cu(II), homodinuclear Cu(II)Cu(II) and heterodinuclear Cu(II)Ni(II) complexes of a phenol-based compartmental ligand

    , Article Journal of Molecular Catalysis A: Chemical ; Volume 241, Issue 1-2 , 2005 , Pages 1-7 ; 13811169 (ISSN) Boghaei, D. M ; Behzad, M ; Bezaatpour, A ; Sharif University of Technology
    A series of previously reported mononuclear Cu(II) and homodinuclear Cu(II)Cu(II) complexes, as well as, novel mononuclear Cu(II), homodinuclear Cu(II)Cu(II), and heterodinuclear Cu(II)Ni(II) complexes of a phenol-based dinucleating ligand with two different N(amine)2O2 and N(imine)2O2 coordination sites, were synthesized and characterized by elemental analyses, infrared and electronic absorption spectroscopies and conductivity measurements. The electrochemical behavior and catecholase-like activity of the complexes were also studied using cyclic voltammetry and UV-vis spectrophotometry, respectively. Our results show that the dinuclear complexes are more effective catalysts in the oxidation... 

    Nanoparticle supported, magnetically separable manganese porphyrin as an efficient retrievable nanocatalyst in hydrocarbon oxidation reactions

    , Article RSC Advances ; Volume 6, Issue 47 , 2016 , Pages 41551-41560 ; 20462069 (ISSN) Bagherzadeh, M ; Mortazavi Manesh, A ; Sharif University of Technology
    Royal Society of Chemistry 
    A manganese porphyrin, meso-tetrakis(pentafluorophenyl)porphyrinato manganese(iii) acetate, Mn(TPFPP)OAc, was immobilized on silica-coated magnetic Fe3O4 nanoparticles functionalized with 3-aminopropyltriethoxysilane (APTS) through the amino propyl linkage using a grafting process in toluene solvent. This enabled the covalent immobilization of Mn(iii) porphyrin via an aromatic nucleophilic substitution reaction, to afford the Fe3O4@SiO2-NH2@MnPor catalyst. The resulting nanoparticles were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), FT-IR spectroscopy, UV-Vis spectroscopy, elemental analysis (CHN), atomic absorption spectroscopy (AAS), and vibrating... 

    Gold-Decorated 3D 2,6-diaminopyridine network: a robust catalyst for the bromination of aromatic compounds

    , Article Industrial and Engineering Chemistry Research ; Volume 57, Issue 37 , 2018 , Pages 12314-12322 ; 08885885 (ISSN) Pourjavadi, A ; Keshavarzi, N ; Hosseini, S. H ; Matloubi Moghaddam, F ; Sharif University of Technology
    American Chemical Society  2018
    This article reports the synthesis of a magnetic heterogeneous catalyst through the decoration of gold ions onto the cross-linked polymeric nanocomposite from 2,6-diaminopyridine. The activity of the resulting catalyst was then evaluated in the bromination of aromatic compounds. The nitrogen rich support showed a high affinity to gold ions, and the measured content of Au was 0.76 mmol g-1. The structure of the catalyst was fully characterized by using Fourier-transform infrared spectroscopy, thermogravimetric analysis, atomic absorption spectroscopy, transmission electron microscopy, scanning electron microscope, energy-dispersive X-ray spectroscopy, Brunauer-Emmett-Teller surface area... 

    Elemental Characterization of the Total Suspended Particulate Matter of the Industrial City of Arak with NAA and AAS and Modeling with the AERMOD Software

    , M.Sc. Thesis Sharif University of Technology Sarlak, Mansoureh (Author) ; Sohrabpour, Mostafa (Supervisor)
    Environmental conditions of various cities of Iran are deteriorating due to various contributing effects of increased traffic, deforestation, industrial pollution etc. Arak is an example in point. It is a city of about 440,000 inhabitants. It is located at the edge of the main central desert (Kavir) of Iran. It lacks any appreciable vegetation or wooded areas and it is the home of a number of major industries. These include aluminum smelting, petrochemical industry, refinery, power plant and various other heavy manufacturing facilities. It was suggested to perform an air sampling of the city for a whole year (2010-2011) to determine the concentration of various elements by instrumental... 

    Survey of Corrosion and Biocompatibility of Metallic Biomaterials in Simulated Body Fluids

    , M.Sc. Thesis Sharif University of Technology Nourimehr, Omid (Author) ; Afshar, Abdollah (Supervisor)
    In this project, the aim is finding the corrosion behavior and biocompatibility of metallic biomaterials in simulated body fluids.by this study we can have a wide knowledge about the behavior and use of metallic biomaterials.in this project we use three base metals. Ti (grade 5 and grade 2), stainless steel (316L and 316) and Mg alloy(AZ91 and AZ31). the media was six physiological environment( Cigada solution, Hank solution, SBF solution, Fusayama solution, Ringer solution and Tyrod’s solution). all of these environments are related to the body fluids except Fusayama solution that is an artificial saliva and is a mouth fluid. we used polarization tests to determine the corrosion behavior... 

    Activated layered manganese oxides with deposited nano-sized gold or silver as an efficient catalyst for epoxidation of olefins

    , Article RSC Advances ; Volume 3, Issue 46 , 2013 , Pages 24069-24074 ; ISSN: 20462069 Najafpour, M. M ; Amini, M ; Sedigh, D. J ; Rahimi, F ; Bagherzadeh, M ; Sharif University of Technology
    Activated layered manganese oxides with deposited nano-sized gold or silver were synthesized and characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction spectrometry, atomic absorption spectroscopy and energy-dispersive X-ray mapping. Here, we report that Au or Ag nanoparticles deposited on layered Mn oxides improve the catalytic activity of the Mn oxides toward the epoxidation of olefins in the presence of H2O2 and NaHCO3  

    Investigating the role of MoS2/reduced graphene oxide as cocatalyst on Cu2O activity in catalytic and photocatalytic reactions

    , Article New Journal of Chemistry ; Volume 41, Issue 16 , 2017 , Pages 7998-8005 ; 11440546 (ISSN) Akbarzadeh, E ; Rahman Setayesh, S ; Gholami, M. R ; Sharif University of Technology
    Royal Society of Chemistry  2017
    In this study, MoS2/reduced graphene oxide (rGO) was used as a cocatalyst to synthesize very highly efficient Cu2O/MoS2/rGO for cooperative catalytic applications. The resulting nanocomposite was characterized by various analytical techniques and applied for catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol and photocatalytic degradation of Acid blue 92. Cu2O/MoS2/rGO composite presents superior performance to pure Cu2O particles in both catalytic and photocatalytic reactions. This excellent activity demonstrates synergistic effect of MoS2/rGO as a cocatalyst in the nanocomposite. The role of the active sites in the reduction of 4-NP and degradation of dye was discussed and... 

    An optimal architecture of magneto-plasmonic core-shell nanoparticles for potential photothermal applications

    , Article Physical Chemistry Chemical Physics ; Volume 22, Issue 25 , 2020 , Pages 14318-14328 Hadilou, N ; Souri, S ; Navid, H. A ; Sadighi Bonabi, R ; Anvari, A ; Palpant, B ; Sharif University of Technology
    Royal Society of Chemistry  2020
    In this work, the optical responses of Fe3O4@Au and Fe3O4@Ag are comprehensively investigated using the discrete dipole approximation. It is found that the resonance wavelength and absorption efficiency strongly depend on the composition of the core and shell, geometry of the nanoparticles, core to particle volume ratio, core radius and shell thickness. The strongest impact is due to the shell material, the shape of the nanoparticles and their combination. When the composition of the shell is changed from gold to silver, instead of one fundamental resonance peak the absorption spectrum shows two, corresponding to the bonding plasmon mode at the nanoparticle-environment interface and... 

    Effects of ligands on (de-)enhancement of plasmonic excitations of silver, gold and bimetallic nanoclusters: TD-DFT+TB calculations

    , Article Physical Chemistry Chemical Physics ; Volume 23, Issue 33 , 2021 , Pages 17929-17938 ; 14639076 (ISSN) Asadi Aghbolaghi, N ; Pototschnig, J ; Jamshidi, Z ; Visscher, L ; Sharif University of Technology
    Royal Society of Chemistry  2021
    Metal nanoclusters can be synthesized in various sizes and shapes and are typically protected with ligands to stabilize them. These ligands can also be used to tune the plasmonic properties of the clusters as the absorption spectrum of a protected cluster can be significantly altered compared to the bare cluster. In this paper, we computationally investigate the influence of thiolate ligands on the plasmonic intensity for silver, gold and alloy clusters. Using time-dependent density functional theory with tight-binding approximations, TD-DFT+TB, we show that this level of theory can reproduce the broad experimental spectra of Au144(SR)60 and Ag53Au91(SR)60 (R = CH3) compounds with... 

    Rapid and efficient synthesis of colloidal gold nanoparticles by arc discharge method

    , Article Applied Physics A: Materials Science and Processing ; Volume 96, Issue 2 , 2009 , Pages 423-428 ; 09478396 (ISSN) Ashkarran, A. A ; Iraji zad, A ; Mahdavi, M ; Ahadian, M. M ; Hormozi nezhad, M. R ; Sharif University of Technology
    We report a simple, inexpensive and one-step synthesis route of colloidal gold nanoparticles using arc discharge between titanium electrodes in HAuCl 4 solution achieving long-time stability. Gold nanoparticles of 8 nm diameter were formed during reduction of HAuCl4 in the plasma discharge zone. The resulting nanoparticles were characterized using UV-Vis spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Optical absorption spectroscopy of as prepared samples at 15 A arc current in HAuCl4 solution shows a surface plasmon resonance around 550 nm. It was found that sodium citrate acts as a stabilizer and surface capping agent of the colloidal... 

    Immobilization of Au nanoparticles on poly(glycidyl methacrylate)-functionalized magnetic nanoparticles for enhanced catalytic application in the reduction of nitroarenes and Suzuki reaction

    , Article Applied Organometallic Chemistry ; Volume 34, Issue 10 , 2020 Pourjavadi, A ; Kohestanian, M ; Keshavarzi, N ; Sharif University of Technology
    John Wiley and Sons Ltd  2020
    We report a novel strategy for the synthesis of magnetic nanocomposite for highly efficient catalysis. Poly(glycidyl methacrylate) (PGMA) chains were grafted to the surface of magnetic nanoparticles (MNPs) through surface-initiated reversible addition-fragmentation chain transfer polymerization. Then, the oxirane rings in the PGMA chains were opened with 2,6-diamino pyridine (DAP) molecules as ligands to prepare the solid support. Finally, this magnetic nanocomposite was used for the immobilization of gold nanoparticles. Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, transmission electron microscopy, scanning electron microscopy, gel permeation...