Search for: polyols
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    Rapid microwave-assisted synthesis of PVP-coated ultrasmall gadolinium oxide nanoparticles for magnetic resonance imaging

    , Article Chemical Physics ; Volume 453-454 , May , 2015 , Pages 35-41 ; 03010104 (ISSN) Vahdatkhah, P ; Madaah Hosseini, H. R ; Khodaei, A ; Montazerabadi, A. R ; Irajirad, R ; Oghabian, M. A ; Delavari,H. H ; Sharif University of Technology
    Elsevier  2015
    Synthesis of polyvinyl pyrrolidone (PVP) coated ultrasmall Gd2O3 nanoparticles (NPs) with enhanced T1-weighted signal intensity and r2/r1 ratio close to unity is performed by a microwave-assisted polyol process. PVP coated Gd2O3NPs with spherical shape and uniform size of 2.5 ± 0.5 nm have been synthesized below 5 min and structure and morphology confirmed by HRTEM, XRD and FTIR. The longitudinal (r1) and transversal relaxation (r2) of Gd2O3NPs is measured by a 3 T MRI scanner. The results showed considerable increasing of relaxivity for Gd2O3NPs in... 

    Exploring of Hydrogen Bond Effect on Acidity Value for Multifunctional Alcohols in Gas Phase & Nonaqueous Solvent via DFT Method

    , M.Sc. Thesis Sharif University of Technology Abedin Maghanaki, Azar Dokht (Author) ; Fattahi, Alireza (Supervisor)
    Hydrogen bond is a type of molecular bonds which occurs between hydrogen and a highly electronegative atom( usually F, N and O) and results to special properties. Polyols and multihydroxyl compounds are among substances which have special properties such as acidity due to the existence of hydrogen bond in their molecular structure. Acidity in these compounds is a result of having stable anions due to intramolecular hydrogen bands. The existence of an electronegative group in addition to hydroxyl groups leads to increase the acidity in these substances. In this project acidities of some polyols and multihydroxyl compounds were calculated in both gas phase and solution phase( DMSO,... 

    Pervaporation of toluene and iso-octane through poly(vinyl alcohol)/graphene oxide nanoplate mixed matrix membranes: Comparison of crosslinked and noncrosslinked membranes

    , Article Journal of Applied Polymer Science ; Volume 135, Issue 7 , 2018 ; 00218995 (ISSN) Khazaei, A ; Mohebbi, V ; Behbahani, R. M ; Ramazani S. A., A ; Sharif University of Technology
    John Wiley and Sons Inc  2018
    Removal of aromatic compounds from fuel is an essential requirement in new environmental policies. In the present study, poly(vinyl alcohol)/graphene oxide (GO) mixed matrix membranes were prepared and applied to the separation of toluene from iso-octane by pervaporation, considering the similarity and interaction between graphene and aromatics. The effects of crosslinking and GO content on separation efficiency have been investigated in detail. Owing to the high affinity of GO with toluene through s and π bonds, the selectivity of the membranes was increased by incorporating a low amount of GO. The results also indicated that noncrosslinked membranes have higher selectivity and permeation... 

    Single-centered hydrogen-bonded enhanced acidity (SHEA) acids: a new class of Bronsted acids

    , Article Journal of the American Chemical Society ; Volume 131, Issue 46 , 2009 , Pages 16984-16988 ; 00027863 (ISSN) Tian, Z ; Fattahi, A ; Lis, L ; Kass, S. R ; Sharif University of Technology
    Hydrogen bonds are the dominant motif for organizing the three-dimensional structures of biomolecules such as carbohydrates, nucleic acids, and proteins, and serve as templates for proton transfer reactions. Computations, gas-phase acidity measurements, and pKa determinations in dimethyl sulfoxide on a series of polyols indicate that multiple hydrogen bonds to a single charged center lead to greatly enhanced acidities. A new class of Brønsted acids, consequently, is proposed. © 2009 American Chemical Society  

    The role of mixed reaction promoters in polyol synthesis of high aspect ratio ag nanowires for transparent conducting electrodes

    , Article Journal of Electronic Materials ; Volume 49, Issue 8 , 2020 , Pages 4822-4829 Amiri Zarandi, A ; Khosravi, A ; Dehghani, M ; Tajabadi, F ; Taghavinia, N ; Sharif University of Technology
    Springer  2020
    In recent years, thin silver nanowires (Ag NWs) with diameters smaller than 150 nm have been synthesized by implementation of NaCl or FeCl3 as reaction promoters and high molecular weight polyvinylpyrrolidone (PVP) as the capping agent. However, the yield of Ag NWs still remains low, mostly due to the insufficient aspect ratio (AR) of the synthesized nanostructures and the production of Ag nanoparticles, which is an undesirable by product. This study proposes a modified technique to alleviate the problem by using a mixture of FeCl3/CuCl2 as the reaction promoter and two different types of PVP with molecular weight of 360 k and 40 k as the capping agents. The appropriate mixtures of... 

    Morphology-Dependent Electrocatalytic Activity of Silver Nanostructures and Differentia Pulse Voltammetry Determination of Atorvastatin at Silver Nanowires Modified Electrode

    , M.Sc. Thesis Sharif University of Technology Naseri, Amene (Author) ; Shahrokhian, Saeed (Supervisor) ; Hormozi Nezhad, Mohammad Reza (Supervisor)
    In this work two shapes of silver nanostructures including silver nanowires and silver nanocubeswere synthesized by polyol method. Silver nanostructures were characterized by SEM, XRD and UV-Vis spectroscopy. Afterwards the morphology-dependent electrocatalyticperformance of these nanocrystals on the differential pulse behavior of naltrexone (NAL) was investigated. To this aim the differential pulse voltammetric behavior of NAL on a glassy carbon electrode modified with electrochemical deposited gold nanoparticles conjugated with different shapes of silver nanostructures and nafion was investigated. It was proved that silver nanowires show more effective electrocatalytic activity toward... 

    Design and Synthesis of Ni-Zn Magnetic Nanoparticles for Hyperthermia Treatment

    , Ph.D. Dissertation Sharif University of Technology Delavari, Hamid (Author) ; Madaah Hosseini, Hamid Reza (Supervisor) ; Simchi, Abdolreza (Supervisor)
    Hyperthermia (also called thermal therapy or thermotherapy) is defined as a type of cancer treatment in which body tissue is exposed to high temperatures, to damage and kill cancer cells, or to make cancer cells more sensitive to the effects of radiation and certain anticancer drugs. The temperature increase required by hyperthermia can be achieved via different heat sources, such as electromagnetic radiation waves (radiofrequency or microwave, ultrasound waves and electrical current. These techniques have shown good results, however, the major problem with present conventional methods is reaching homogenous heat distribution and therapeutic temperatures in the deep region of the tumor to be... 

    Ethylene glycol biodegradation in microbial fuel cell

    , Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Volume 38, Issue 8 , 2016 , Pages 1096-1102 ; 15567036 (ISSN) Hosseinpour, M ; Asadi, M ; Rahmani Eliato, T ; Vossoughi, M ; Alemzadeh, I ; Sharif University of Technology
    Taylor and Francis Inc 
    Ethylene glycol is an environmental pollutant, which exists in airport runoff and industrial waste. In this article, biodegradation of ethylene glycol in a two-chamber, batch-mode microbial fuel cell was investigated. Glucose and ethylene glycol at different concentrations were used as carbon and energy sources. Chemical oxygen demand removal in the range of 92-98% indicated that microbial fuel cell can be used for biodegradation of ethylene glycol. Ethylene glycol also improved power generation and the maximum power density was 5.72 mW/m2 (137.32 mW/m3), with respect to the same glucose and ethylene glycol concentrations (500 ppm)  

    Preparation of ZnO nanoparticles/Ag nanowires nanocomposites as plasmonic photocatalysts and investigation of the effect of concentration and diameter size of Ag nanowires on their photocatalytic performance

    , Article Journal of Alloys and Compounds ; Volume 664 , 2016 , Pages 707-714 ; 09258388 (ISSN) Khademalrasool, M ; Farbod, M ; Iraji Zad, A ; Sharif University of Technology
    Elsevier Ltd 
    In this work the plasmonic photocatalytic activity of ZnO/noble metals nanocomposites has been investigated. Ag nanowires and Au nanospheres were prepared and mixed with ZnO in order to prepare the nanocomposites. It was demonstrated that the composites containing the plasmonic Ag nanowires and ZnO nanoparticles showed a significant photocatalytic activity enhancement compared to the pure ZnO in decomposition of methylene blue (MB). By investigation of mechanisms governing the performance of plasmonic photocatalysts, it was found that the photocatalytic activity enhancement can be attributed to the energy transfer from Ag nanowires to the ZnO nanoparticles induced by the surface plasmonic... 

    Poly(vinyl alcohol)/graphene oxide mixed matrix membranes for pervaporation of toluene and isooctane

    , Article Polymer - Plastics Technology and Engineering ; Volume 56, Issue 12 , 2017 , Pages 1286-1294 ; 03602559 (ISSN) Khazaei, A ; Mohebbi, V ; Behbahani, R. M ; Ahmad Ramazani, S. A ; Sharif University of Technology
    Poly(vinyl alcohol)/graphene oxide mixed matrix membranes have been prepared and applied for the pervaporation of isooctane (aliphatic) and toluene (aromatic) mixtures. Characteristics of the membranes such as crystallinity, morphology, and swelling have been investigated, and the results have been used to describe pervaporation performance. Experimental tests evidenced that incorporation of low content of graphene oxide nanoplates (0.5 wt%) in poly(vinyl alcohol) increases affinity of the membrane to aromatics by S and π bonds and selectivity increase to about four times. Moreover, interaction of graphene oxide with toluene results in increasing of swelling and decreasing of permeation... 

    A comparative study on the performance of HFO-1234yf and HFC-134a as an alternative in automotive air conditioning systems

    , Article Applied Thermal Engineering ; Volume 110 , 2017 , Pages 1091-1100 ; 13594311 (ISSN) Daviran, S ; Kasaeian, A ; Golzari, S ; Mahian, O ; Nasirivatan, S ; Wongwises, S ; Sharif University of Technology
    In this study, an automotive air conditioning system is simulated by considering HFO-1234yf (2,3,3,3-tetrafluoropropene) as the drop-in replacement of HFC-134a. The simulated air conditioning system consists of a multi-louvered fin and flat-plate type evaporator, a wobble-plate type compressor, a mini-channel parallel-flow type condenser and a thermostatic expansion valve. The thermodynamic properties of the refrigerants are extracted from the REFPROP 8.0 software, and a computer program is simulated for the thermodynamic analysis. Two different conditions have been considered in this program for the cycle analysis: for the first state, the cooling capacity is taken as constant, and for the... 

    Experimental investigation of the effect of copper electrodeposition on the aluminum surface and addition of ethylene glycol on boiling heat transfer coefficient

    , Article Heat and Mass Transfer/Waerme- und Stoffuebertragung ; 2021 ; 09477411 (ISSN) Azadi Milani, P ; Mahdi, M ; Abarghooei, A ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2021
    In this research, the effect of surface characteristics on boiling heat transfer has been investigated experimentally. For this purpose, a device with the ability to automatically record the liquid temperature of the inlet and outlet of the test area, calculate the coefficient of boiling heat transfer, and heat flux has been developed. The automatic temperature stability of the working fluid and the ability to investigate the effect of surfaces with different characteristics (in terms of material and surface structure) on the boiling heat transfer parameters are the most important features of this device. The performance of the experimental setup was evaluated by the modified "Chen" equation... 

    Morphology and phase-controlled growth of CuInS2 nanoparticles through polyol based heating up synthesis approach

    , Article Materials Science in Semiconductor Processing ; Volume 121 , 2021 ; 13698001 (ISSN) Heidariramsheh, M ; Dabbagh, M. M ; Mahdavi, S. M ; Beitollahi, A ; Sharif University of Technology
    Elsevier Ltd  2021
    The properties of colloidal nanoparticles are the key parameters in the fabrication of inexpensive solar cells based on the solution methods. In this study, Different nanostructures of CuInS2 (CIS) were successfully synthesized by a heating-up facile polyol-based method in which, polyols including diethylene glycol (DEG), ethylene glycol (EG), and glycerol (Gly) were chosen as both the solvent and the reductant. It is found that not only the indium precursor type but also the polyol solvent are greatly effective on the size, morphology and crystal phase of this sulfide ternary composition. Briefly, the heating-up synthesis using In(acac)3 in DEG and Gly media, created nano-sized particles... 

    Colloidal stability of dextran and dextran/poly ethylene glycol coated TiO2 nanoparticles by hydrothermal assisted sol-gel method

    , Article Ceramics International ; Volume 39, Issue 7 , 2013 , Pages 8377-8384 ; 02728842 (ISSN) Naghibi, S ; Madaah Hosseini, H. R ; Faghihi Sani, M. A ; Sharif University of Technology
    Colloidal stability of dextran (Dex) and Dex/poly ethylene glycol (PEG) coated TiO2 nanoparticles (NPs) were investigated. The particles were successfully synthesized by a hydrothermal assisted sol-gel technique. The results of Ultraviolet-visible (UV-vis) spectrophotometry showed that Dex and PEG additions during hydrothermal process (HTP) led to the formation of long-term (more than 60 days) stable colloids, while the addition of dispersants after HTP did not have a significant impact on the colloidal stability of NPs. X-ray diffraction (XRD) and selected area electron diffraction (SAED) analyses proved that PEG and/or Dex coated NPs had less crystallinity than the plain TiO2. Fourier... 

    Effect of hydrogen bonds on pK a values: Importance of networking

    , Article Journal of the American Chemical Society ; Volume 134, Issue 25 , 2012 , Pages 10646-10650 ; 00027863 (ISSN) Shokri, A ; Abedin, A ; Fattahi, A ; Kass, S. R ; Sharif University of Technology
    The pK a of an acyclic aliphatic heptaol ((HOCH 2CH 2CH(OH)CH 2) 3COH) was measured in DMSO, and its gas-phase acidity is reported as well. This tertiary alcohol was found to be 10 21 times more acidic than tert-butyl alcohol in DMSO and an order of magnitude more acidic than acetic acid (i.e., pK a = 11.4 vs 12.3). This can be attributed to a 21.9 kcal mol -1 stabilization of the charged oxygen center in the conjugate base by three hydrogen bonds and another 6.3 kcal mol -1 stabilization resulting from an additional three hydrogen bonds between the uncharged primary and secondary hydroxyl groups. Charge delocalization by both the first and second solvation shells may be used to facilitate... 

    Super alcohol-absorbent gels of sulfonic acid-contained poly(acrylic acid)

    , Article Journal of Polymer Research ; Volume 18, Issue 3 , 2011 , Pages 449-458 ; 10229760 (ISSN) Kabiri, K ; Lashani, S ; Zohuriaan Mehr, M. J ; Kheirabadi, M ; Sharif University of Technology
    Alcohol-specific superabsorbing gels (superalcogels) based on non-neutralized acrylic acid (AA, 60-94 mol%) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) were prepared via solution polymerization in water. Polyethylene glycol dimethacrylate and potassium persulfate were used as crosslinker and initiator, respectively. Characterization of samples was performed using FTIR, 1H-NMR and thermomechanical analyses. Glass transition temperature and modulus of dried samples were found to be directly changed with their AA content. The gels exhibited enormous ability for absorbing and retaining a variety of mono- and poly-hydric alcohols. For example, in lieu of one gram of a typical sample... 

    Magnetic domain regime-controlled synthesis of nickel nano-particles by applying statistical experimental design in modified polyol process

    , Article Materials Chemistry and Physics ; Volume 168 , 2015 , Pages 117-121 ; 02540584 (ISSN) Delavari, H ; Madaah Hosseini, H. R ; Wolff, M ; Sharif University of Technology
    Elsevier Ltd  2015
    In this work, central composite design (CCD) as a statistical experimental design method is performed to prepare nickel nano-particle of different magnetic domain regimes by the modified polyol process. It is shown that not only the concentration of the different chemicals but also the injection rate is determining for the morphology and magnetic properties. The average diameter of the synthesized nickel NPs is smaller than the critical single domain size and thus the single domain or pseudo-single domain nickel nano-particles can be prepared based on Day's plot  

    Effect of reformer gas blending on homogeneous charge compression ignition combustion of primary reference fuels using multi zone model and semi detailed chemical-kinetic mechanism

    , Article Applied Energy ; Volume 179 , 2016 , Pages 463-478 ; 03062619 (ISSN) Neshat, E ; KhoshbakhtiSaraya Saray, R ; Hosseini, V ; Sharif University of Technology
    Elsevier Ltd  2016
    This study mainly aims to investigate the effect of reformer gas (RG) addition on the performance of homogeneous charge compression ignition (HCCI) engines using a multi zone model. The developed model is validated using a wide range of experimental data of a cooperative fuel research engine. Blended fuels of isooctane and n-heptane, known as primary reference fuels, with different octane numbers are used as the main engine fuel. A semi detailed chemical-kinetic mechanism containing 101 species and 594 reactions is used to simulate the combustion of blended fuels. The study is performed with different percentages of RG (0–30%). The results show that RG reduces the rate of some H abstraction... 

    Broadband and low-loss plasmonic Light trapping in dye-sensitized solar cells using micrometer-scale rodlike and spherical core-shell plasmonic particles

    , Article ACS Applied Materials and Interfaces ; Volume 8, Issue 25 , 2016 , Pages 16359-16367 ; 19448244 (ISSN) Malekshahi Byranvand, M ; Nemati Kharat, A ; Taghavinia, N ; Dabirian, A ; Sharif University of Technology
    American Chemical Society  2016
    Dielectric scattering particles have widely been used as embedded scattering elements in dye-sensitized solar cells (DSCs) to improve the optical absorption of the device. Here we systematically study rodlike and spherical core-shell silica@Ag particles as more effective alternatives to the dielectric scattering particles. The wavelength-scale silica@Ag particles with sufficiently thin Ag shell support hybrid plasmonic-photonic resonance modes that have low parasitic absorption losses and a broadband optical response. Both of these features lead to their successful deployment in light trapping in high-efficiency DSCs. Optimized rodlike silica@Ag@silica particles improve the power conversion... 

    Immobilization of copper ions onto α-amidotriazole-functionalized magnetic nanoparticles and their application in the synthesis of triazole derivatives in water

    , Article Applied Organometallic Chemistry ; Volume 30, Issue 6 , 2016 , Pages 488-493 ; 02682605 (ISSN) Matloubi Moghaddam, F ; Ayati, S. E ; Firouzi, H. R ; Ghorbani, F ; Sharif University of Technology
    John Wiley and Sons Ltd 
    A new heterogeneous copper catalyst was synthesized by immobilization of copper ions onto magnetic nanoparticles with a new ligand based on triazole. The catalyst was characterized using scanning and transmission electron microscopies, atomic absorption and Fourier transform infrared spectroscopies, and thermogravimetric, elemental and energy-dispersive X-ray analyses. The results confirmed that a good level of organic groups was immobilized on the magnetic nanoparticles. Huisgen cycloaddition reaction was chosen as a model reaction for the investigation of catalyst activity under green conditions. Phenylacetylene and benzyl bromide derivatives were used for the synthesis of triazoles. The...