Search for: association-reactions
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    Synthesis and photoisomerization study of new aza-crown macrocyclic tweezer tethered through an azobenzene linker: the first report on supramolecular interaction of azobenzene moiety with C60

    , Article Journal of Molecular Structure ; Volume 1144 , 2017 , Pages 360-369 ; 00222860 (ISSN) Ghanbari, B ; Mahdavian, M ; García Deibe, A. M ; Sharif University of Technology
    In the present communication, three bimacrocyclic tweezers linked through azobenzene moiety, Ln (n = 1–3) were synthesized in a multistep route and characterized by x-ray crystallography, IR, 1H and 13C NMR, UV–vis spectroscopy as well as CHN microanalysis. UV–visible spectroscopy established that the irradiation of L1 and L3 with UV light promoted the trans to cis isomerization. Irradiating the reaction mixtures with Hg lamp, significant supramolecular interactions between L1 and L3 with C60 were also found in terms of the association constants calculated by UV–visible spectroscopy, denoting on more pronounced interaction with C60 that in the absence of UV light. The molecular structures of... 

    Intracellular viral infection kinetics using a stochastic approach

    , Article Progress in Reaction Kinetics and Mechanism ; Volume 38, Issue 4 , 2013 , Pages 359-376 ; 14686783 (ISSN) Taherkhani, F ; Taherkhani, F ; Rezania, H ; Akbarzadeh, H ; Sharif University of Technology
    Stochastic simulation is carried out to investigate intracellular viral reaction kinetics and the time evolution of the average particle number ( N̄) and coefficient variation (CV) for genome, template, and structural protein. The coefficient variation of these components is found to be ordered as: CV template > CV structural protein > CVgenome. The average particle number is also calculated via a deterministic approach. The magnitude value of the difference between the stochastic and deterministic approaches is found to be N̄ template ̃ N̄ structural protein > N̄ genome. The Poisson algorithm has been used to investigate the number of particles in the dynamics of intracellular viral... 

    Geometry effect on electrokinetic flow and ionic conductance in pH-regulated nanochannels

    , Article Physics of Fluids ; Volume 29, Issue 12 , 2017 ; 10706631 (ISSN) Sadeghi, M ; Saidi, M. H ; Moosavi, A ; Sadeghi, A ; Sharif University of Technology
    Semi-analytical solutions are obtained for the electrical potential, electroosmotic velocity, ionic conductance, and surface physicochemical properties associated with long pH-regulated nanochannels of arbitrary but constant cross-sectional area. The effects of electric double layer overlap, multiple ionic species, and surface association/dissociation reactions are all taken into account, assuming low surface potentials. The method of analysis includes series solutions which the pertinent coefficients are obtained by applying the wall boundary conditions using either of the least-squares or point matching techniques. Although the procedure is general enough to be applied to almost any... 

    Extending application of Dehaghani Association Equation of State for Modeling Phase Behavior of Water-Alcohol Systems

    , Article Fluid Phase Equilibria ; Volume 482 , 2019 , Pages 126-133 ; 03783812 (ISSN) Saeedi Dehaghani, A. H ; Badizad, M. H ; Sharif University of Technology
    Elsevier B.V  2019
    This paper concerns extending applicability of Dehaghani association equation of state (in short DA-EOS) to model non-ideality in phase behavior caused by hydrogen bonding. Advantageously, this equation only needs two and one parameters to treat self- and cross association, respectively, which were determined for methanol/water and ethanol/water mixture in this study. In this respect, DA was coupled with PR and SRK EOS to account for physical interaction between molecules. Notably, DA-PR persistently provides more accurate prediction than DA-SRK for both aqueous methanol and ethanol solutions  

    A review on the kinetics of iron ore reduction by hydrogen

    , Article Materials ; Volume 14, Issue 24 , 2021 ; 19961944 (ISSN) Heidari, A ; Niknahad, N ; Iljana, M ; Fabritius, T ; Sharif University of Technology
    MDPI  2021
    A clean energy revolution is occurring across the world. As iron and steelmaking have a tremendous impact on the amount of CO2 emissions, there is an increasing attraction towards improving the green footprint of iron and steel production. Among reducing agents, hydrogen has shown a great potential to be replaced with fossil fuels and to decarbonize the steelmaking processes. Although hydrogen is in great supply on earth, extracting pure H2 from its compound is costly. Therefore, it is crucial to calculate the partial pressure of H2 with the aid of reduction reaction kinetics to limit the costs. This review summarizes the studies of critical parameters to determine the kinetics of reduction.... 

    Influence of butyl side chain elimination, tail amine functional addition, and c2 methylation on the dynamics and transport properties of imidazolium-based [Tf2N-] ionic liquids from molecular dynamics simulations

    , Article Journal of Chemical and Engineering Data ; Volume 60, Issue 3 , January , 2015 , Pages 551-560 ; 00219568 (ISSN) Kowsari, M. H ; Fakhraee, M ; Sharif University of Technology
    American Chemical Society  2015
    Molecular dynamics simulations of four ionic liquids (ILs) based on the [Tf2N] bis(trifluoromethanesulfonyl)imide anion, and imidazolium cations with different alkyl side chains have been performed. These simulations investigate the influence of butyl side chain elimination, tail amine functional addition, and C2 methylation on the dynamics and transport properties of this family of ionic liquids at 400 K. In our earlier work (J. Chem. Eng. Data, 2014, 59, 2834-2849), a suite of thermodynamic quantities and microscopic structures of these ILs were studied by classical molecular dynamics simulations and ab initio calculations. In this work, the dynamics of the ILs are studied by calculating... 

    Preparation, physiochemical and kinetic investigations of V2O5/SiO2 catalyst for sulfuric acid production

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 29, Issue 11 , 2016 , Pages 1478-1488 ; 1728144X (ISSN) Tavassoli, A ; Kazemeini, M ; Fattahi, M ; Vafajoo, L ; Sharif University of Technology
    Materials and Energy Research Center  2016
    V2O5/SiO2 catalyst utilized to oxidize the SO2 to SO3 species in the presence of oxygen mainly for producing sulfuric acid. For this catalyst, the active phase was a mixture of vanadium pentoxide and basic sulfate/pyrosulfate material. This active phase at the reaction temperature behaved as a liquid filling up the pores of the silica support. On the other hand, amounts of the SO3 and V5+ species in the catalyst necessarily varied with the concentration of the feed material and temperature rendering complexity to the kinetics of the SO2 oxidation reaction. In the current research, the catalyst preparation with different amounts of such materials was undertaken. Purified Diatomaceous earth of... 

    High molecular weight polyacrylamide nanoparticles prepared by inverse emulsion polymerization: reaction conditions-properties relationships

    , Article Colloid and Polymer Science ; Volume 294, Issue 3 , 2016 , Pages 513-525 ; 0303402X (ISSN) Tamsilian, Y ; Ramazani S. A ; Shaban, M ; Ayatollahi, S ; Tomovska, R ; Sharif University of Technology
    Springer Verlag  2016
    High molecular weight polyacrylamide (PAM) nanoparticle dispersions are products with wide application possibilities, the most important of which is in petroleum industry such as drilling fluid and flooding agent in enhanced oil recovery. For that aim, it is necessary to achieve complete control of the final dispersion and polymer properties during the synthesis step. In this work, PAMs were synthesized by inverse emulsion polymerization of aqueous acrylamide solution in cyclohexane in the presence of emulsifier mixture of Span 20 and Span 80. We present a comprehensive study of the effects of variation of all important reaction conditions (agitation rate, reaction time and temperature,... 

    Inhibiting asphaltene precipitation from Iranian crude oil using various dispersants: Experimental investigation through viscometry and thermodynamic modelling

    , Article Fluid Phase Equilibria ; Volume 442 , 2017 , Pages 104-118 ; 03783812 (ISSN) Saeedi Dehaghani, A. H ; Badizad, M. H ; Sharif University of Technology
    Elsevier B.V  2017
    Asphaltene precipitation is a major assurance problem posing significant technical and economic loss on petroleum industry. To tackle this issue, various treatments have been proposed and applied by industry. Amongst, inhibiting or retarding the asphaltene precipitation has been understood as the most efficient approach. In this regard, blending crude oil with chemical additives could appreciably heighten its stability. Surfactants, owing to amphiphilic nature, could keep asphaltene dissolved in crude oil by precluding self-tendency of those particles to making agglomerates. Despite importance of this subject, there is still lack of sufficient experimental data to evaluate effectiveness of... 

    Numerical modeling of surface reaction kinetics in electrokinetically actuated microfluidic devices

    , Article Analytica Chimica Acta ; Vol. 838, issue , August , 2014 , pp. 64-75 ; ISSN: 00032670 Sadeghi, A ; Amini, Y ; Saidi, M. H ; Chakraborty, S ; Sharif University of Technology
    We outline a comprehensive numerical procedure for modeling of species transport and surface reaction kinetics in electrokinetically actuated microfluidic devices of rectangular cross section. Our results confirm the findings of previous simplified approaches that a concentration wave is created for sufficiently long microreactors. An analytical solution, developed for the wave propagation speed, shows that, when normalizing with the fluid mean velocity, it becomes a function of three parameters comprising the channel aspect ratio, the relative adsorption capacity, and the kinetic equilibrium constant. Our studies also reveal that the reactor geometry idealized as a slit, instead of a... 

    Supramolecular polycaprolactone nanocomposite based on functionalized hydroxyapatite

    , Article Journal of Bioactive and Compatible Polymers ; Volume 27, Issue 5 , January , 2012 , Pages 467-480 ; 08839115 (ISSN) Mehmanchi, M ; Shokrollahi, P ; Atai, M ; Omidian, H ; Bagheri, R ; Sharif University of Technology
    SAGE  2012
    Arms bearing ureido-pyrimidinone functional groups with self-association capability (through quadruple hydrogen bonds) were successfully grafted onto hydroxyapatite nanoparticles. The supramolecularly modified nanoparticles (nHApUPy) exhibited enhanced colloidal stability compared to the original hydroxyapatite nanoparticles and were uniformly dispersed in supramolecular polycaprolactone in PCL(UPy)2/HApUPy nanocomposites at different filler loadings. The combined atomic force microscopy, mechanical, and rheological analyses confirmed a high degree of compatibility of HApUPy nanoparticles with the polymer matrix. The temperature dependence of the supramolecular structure in PCL(UPy)2/HApUPy... 

    Molecular dynamics simulation and MM-PBSA calculations of sickle cell hemoglobin in dimer form with Val, Trp, or Phe at the lateral contact

    , Article Journal of Physical Organic Chemistry ; Volume 23, Issue 9 , March , 2010 , Pages 866-877 ; 08943230 (ISSN) Abroshan, H ; Akbarzadeh, H ; Parsafar, G. A ; Sharif University of Technology
    As the delay time and hence nuclei formation play a crucial role in the pathophysiology of sickle cell disease, MD simulation and molecular mechanics-Poisson-Boltzmann surface area (MM-PBSA) calculations have been performed on three systems of hemoglobin; namely dimer of hemoglobin with valine (Hb S), tryptophan (Hbβ6W), and phenylalanine (Hbβ6F) at β6 position. The structural changes due to these aromatic substitutions are investigated. It is shown that β subunits have significant impact on the differences between a dimer and other crystal structures. Transition from a dimer to polymer for Hb S system affects the donor molecule more than that of the acceptor. In the case of donor and... 

    Rheology and colloidal structure of silver nanoparticles dispersed in diethylene glycol

    , Article Powder Technology ; Volume 197, Issue 1-2 , 2010 , Pages 49-53 ; 00325910 (ISSN) Tamjid, E ; Guenther, B. H ; Sharif University of Technology
    Rheological behavior of agglomerated silver nanoparticles (~ 40 nm) suspended in diethylene glycol over a wide range of volumetric solids concentrations (φ{symbol} = 0.11-4.38%) was studied. The nanoparticle suspensions generally exhibited a yield pseudoplastic behavior. Bingham plastic, Herschel-Bulkley and Casson models were used to evaluate the shear stress-shear rate dependency. Analyzing the effect of silver concentrations on the yield stress and viscosity of the suspensions followed an exponential form, revealing an increase in the degree of interparticle interactions with increasing solid concentrations. Fractal dimension (Df) was estimated from the suspension yield stress and... 

    Amino acid ionic liquids based on imidazolium-hydroxyl functionalized cation: New insight from molecular dynamics simulations

    , Article Journal of Molecular Liquids ; Volume 279 , 2019 , Pages 51-62 ; 01677322 (ISSN) Fakhraee, M ; Sharif University of Technology
    Elsevier B.V  2019
    Various thermodynamic and structural properties of amino acid ionic liquids (AAILs), comprising 1-(2-Hydroxyethyl)-3-methyl imidazolium ([C 2 OHmim] + ) cation mixed with Glycinate [Gly], Serinate [Ser], Alaninate [Ala], and Prolinate [Pro] AA anions are explored using molecular dynamic (MD) simulations and quantum theory of atoms in molecules (QTAIM) analysis. In general, the simulated thermodynamic results are in good agreement with the reported experimental data. Structural dependence of vdW- and electrostatic energies of AAILs is [Pro] > [Ala] > [Ser] > [Gly] and [Gly] > [Ala] > [Pro] > [Ser], respectively. The similar trend of electrostatic energies is found for their interaction... 

    Thermodynamic modeling of hydrogen sulfide solubility in ionic liquids using modified SAFT-VR and PC-SAFT equations of state

    , Article Fluid Phase Equilibria ; Volume 309, Issue 2 , 2011 , Pages 179-189 ; 03783812 (ISSN) Rahmati Rostami, M ; Behzadi, B ; Ghotbi, C ; Sharif University of Technology
    Equations of state based on the statistical associating fluid theory for potentials of variable range (SAFT-VR) and the perturbed chain statistical associating fluid theory (PC-SAFT) have been used to model the PVT behavior of ionic liquids and the solubility of H2S in six imidazolium-based ionic liquids. The studied systems included [bmim][PF6], [hmim][PF6], [bmim][BF4], [hmim][BF4], [bmim][NTF2] and [hmim][NTF2] at various temperatures and pressures.For pure components, parameters of the models have been obtained by fitting the models to experimental data on liquid densities; the average relative deviation between the calculated and experimental densities for ionic liquids is less than...