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    Quantum chemical parameters of some organic corrosion inhibitors, pyridine, 2-picoline 4-picoline and 2,4-lutidine, adsorption at aluminum surface in hydrocholoric and nitric acids and comparison between two acidic media

    , Article Main Group Metal Chemistry ; Volume 26, Issue 6 , 2003 , Pages 349-361 ; 07921241 (ISSN) Monajjemi, M ; Mollaamin, F ; Gholami, M. R ; Yoosbashizadeh, H ; Sadrnezhad, S.K ; Passdar, H ; Sharif University of Technology
    Walter de Gruyter GmbH  2003
    The effect of new corrosion inhibitors, namely pyridine, 2-methylpyridine (2-picoline), 4-methylpyridine (4-picoline), 2,4-dimethylpyridine (2,4-lutidine), on the corrosion of Al-surface in hydrocholoric acid (HCl) and nitric acid (HNO3) was investigated at the HF and B3LYP level using the ab initio 6-3IG and LANL2DZ basis sets from the program package Gaussian 98 (A.7 Public Domain version). The physico-chemical properties of corrosion inhibitors are one of the principal criteria for the determination and selection of inhibitors. The inhibition of the Al-surface in solutions of hydrocholoric acid and nitric acid by some N-heterocyclic compounds has been studied. The calculated results... 

    An experimental and modeling study of asphaltene deposition due to CO 2 miscible injection

    , Article Petroleum Science and Technology ; Volume 31, Issue 2 , 2013 , Pages 129-141 ; 10916466 (ISSN) Bolouri, H ; Schaffie, M ; Kharrat, R ; Ghazanfari, M. H ; Ghoodjani, E ; Sharif University of Technology
    The authors studied deposition and entrainment of asphaltene particles as major mechanisms that occur in porous media. Deposition mechanisms that contribute to permeability reduction and entrainment of deposited particle improve the damaged permeability value. While in most previous works the effects of entrainment mechanism are considered negligible, in this study miscible CO2 injection tests were conducted by core flood apparatus to investigate the effect of asphaltene deposition on permeability and porosity alterations. Results indicated that proposed model for entrainment mechanism is affected by deposition mechanism. The asphaltene deposition core's characteristics have undeniable roles... 

    Model study on the kinetics of scale removal due to ultrasonic radiation

    , Article 73rd European Association of Geoscientists and Engineers Conference and Exhibition 2011: Unconventional Resources and the Role of Technology. Incorporating SPE EUROPEC 2011 ; Volume 7 , 2011 , Pages 5657-5659 ; 9781617829666 (ISBN) Sherafati, M ; Hemmati, N ; Mashayekhi, L ; Sharif University of Technology
    Scale formation is one of the major problems in oilfields. Removal of scales is a difficult process due to their relative hardness and low solubility. Therefore it is valuable to find a method which can remove damages caused by scales. Ultrasonic radiation is known have the sufficient energy to remove the scales. Our purpose is to investigate the role of ultrasound on permeability increments due to scale removal. Some experiments were carried out to find these effects and observed that ultrasound has increased volumetric mass transfer, concentration and solubility limits. We also worked on a model presented by Tahmasebi et. al[2010] and applied changes on it to make it able to predict... 

    Conceptualization of a fresh groundwater lens influenced by climate change: A modeling study of an arid-region island in the Persian Gulf, Iran

    , Article Journal of Hydrology ; Vol. 519, issue. PA , 2014 , pp. 399-413 ; ISSN: 00221694 Mahmoodzadeh, D ; Ketabchi, H ; Ataie-Ashtiani, B ; Simmons, C. T ; Sharif University of Technology
    Understanding the fresh groundwater lens (FGL) behavior and potential threat of climatic-induced seawater intrusion (SWI) are significant for the future water resources management of many small islands. In this paper, the FGL of Kish Island, an arid-region case in the Persian Gulf, Iran, is modeled using two-dimensional (2D) and three-dimensional (3D) simulations. These simulations are based on the application of SUTRA, a density-dependent groundwater numerical model. Also, the numerical model parameters are calibrated using PEST, an automated parameter estimation code. Firstly a detailed conceptualization of the FGL model is completed to understand the sensitivity of the FGL to some... 

    Recovery of uranium from UCF liquid waste by anion exchange resin CG-400: Breakthrough curves, elution behavior and modeling studies

    , Article Annals of Nuclear Energy ; Volume 54 , April , 2013 , Pages 149-153 ; 03064549 (ISSN) Tavakoli, H ; Sepehrian, H ; Semnani, F ; Samadfam, M ; Sharif University of Technology
    Continuous fixed-bed column studies were carried out by using Amberlite CG-400 anion exchange resin for the recovery of uranium from aqueous solutions (synthetic solutions and uranium conversion facility (UCF) liquid waste). Effects of operating parameters such as flow rate and bed height were studied. The breakthrough capacity decreases with increasing flow rate, but this dependence was not significant with a long column. The maximum breakthrough capacity of uranium ions were achieved by CG-400 resin at a flow rate of 0.2 mL min-1 and bed height 9.1 cm (4 g resin). The elution behavior of uranium from CG-400 resin by various eluents have been investigated and the results show that 0.5 mol... 

    The effects of intra-abdominal pressure on the stability and unloading of the spine

    , Article Journal of Mechanics in Medicine and Biology ; Volume 12, Issue 1 , 2012 ; 02195194 (ISSN) Mokhtarzadeh, H ; Farahmand, F ; Shirazi Adl, A ; Arjmand, N ; Malekipour, F ; Parnianpour, M ; Sharif University of Technology
    In spite of earlier experimental and modeling studies, the relative role of the intra-abdominal pressure (IAP) in spine mechanics has remained controversial. This study employs simple analytical and finite element (FE) models of the spine and its surrounding structures to investigate the contribution of IAP to spinal loading and stability. The analytical model includes the abdominal cavity surrounded by muscles, lumbar spine, rib cage and pelvic ring. The intra-abdominal cavity and its surrounding muscles are represented by a thin deformable cylindrical membrane. Muscle activation levels are simulated by changing the Young's modulus of the membrane in the direction of muscle fibers, yielding... 

    Effects of particle size, shape and crystal structure on the formation energy of Schottky vacancies in free-standing metal nanoparticles: A model study

    , Article Physica B: Condensed Matter ; Volume 406, Issue 20 , October , 2011 , Pages 3777-3780 ; 09214526 (ISSN) Delavari H., H ; Madaah Hosseini, H. R ; Simchi, A ; Sharif University of Technology
    A simplified model based on cohesive energy is proposed to estimate the formation energy of Schottky vacancies (VFE) in free-standing metal nanoparticles with BCC and FCC crystal structures. To study the effect of particle size and shape, the surface energy, elastic contraction and average coordination number of particles at the surface and core was considered. It is shown that the energy of vacancy formation in FCC nanoparticles increases with decreasing the size while the effect of particle shape (sphere, cubic and icosahedral) is marginal. In spite of this behavior, BCC nanoparticles exhibit a critical particle size at around 25 Å, at which a minimum VFE is attained. Additionally, the... 

    Synthesis, crystal structure and DNA interaction of a new water-soluble derivative of pyrazino[2,3-f][1,10] phenanthroline; theoretical calculations, experimental and molecular docking studies

    , Article Journal of Molecular Structure ; Volume 1165 , 2018 , Pages 267-275 ; 00222860 (ISSN) Aminzadeh, M ; Eslami, A ; Kia, R ; Aleeshah, R ; Sharif University of Technology
    Elsevier B.V  2018
    The new water-soluble derivative of pyrazino[2,3-f][1,10] phenanthroline has been synthesized and characterized by conductivity measurement, elemental analysis, FT-IR, 1H NMR, 13C NMR spectroscopic studies, as well as single crystal x-ray crystallography. Theoretical calculations have been performed using the density functional theory (DFT) in order to confirm the structure and understand the electronic structure of the synthesized compound. The DNA binding properties of the compound were investigated by absorption spectroscopy, melting temperature and viscosity measurements. The intrinsic binding constant, Kb, was determined as 7.84 × 103 M−1 at 298 K. Thermodynamic parameters showed that... 

    Sustainable ammonia production from steam reforming of biomass-derived glycerol in a heat-integrated intensified process: Modeling and feasibility study

    , Article Journal of Cleaner Production ; Volume 324 , 2021 ; 09596526 (ISSN) Khademi, M. H ; Lotfi Varnoosfaderani, M ; Sharif University of Technology
    Elsevier Ltd  2021
    Currently, ammonia, as a clean and sustainable energy carrier, is intensively synthesized from its elements during the Haber-Bosch technology. This process requires a large amount of energy and emits numerous amounts of carbon dioxide, because hydrogen is dominantly produced from fossil fuels through reforming processes. Biomass-derived glycerol steam reforming is an attractive alternative to traditional reforming for reducing the dependence on hydrocarbon resources and mitigating climate change. This research aims to intensify a heat-integrated process for the co-production of ammonia and syngas from glycerol valorization. In this process, glycerol reforming continuously provides hydrogen... 

    Computational modeling of the transverse-isotropic elastic properties of single-walled carbon nanotubes

    , Article Computational Materials Science ; Volume 49, Issue 3 , 2010 , Pages 544-551 ; 09270256 (ISSN) Montazeri, A ; Sadeghi, M ; Naghdabadi, R ; Rafii-Tabar, H ; Sharif University of Technology
    Various experimental and theoretical investigations have been carried out to determine the elastic properties of nanotubes in the axial direction. Their behavior in transverse directions, however, has not been well studied. In this paper, a combination of molecular dynamics (MD) and continuum-based elasticity model is used to predict the transverse-isotropic elastic properties of single-walled carbon nanotubes (SWCNTs). From this modeling study, five independent elastic constants of an SWCNT in transverse directions are obtained by analyzing its deformations under four different loading conditions, namely, axial tension, torsion, uniform and non-uniform radial pressure. To find the elastic... 

    A comprehensive approach for the validation of lumbar spine finite element models investigating post-fusion adjacent segment effects

    , Article Journal of Biomechanics ; Volume 121 , 2021 ; 00219290 (ISSN) Azadi, A ; Arjmand, N ; Sharif University of Technology
    Elsevier Ltd  2021
    Spinal fusion surgery is usually followed by accelerated degenerative changes in the unfused segments above and below the treated segment(s), i.e., adjacent segment disease (ASD). While a number of risk factors for ASD have been suggested, its exact pathogenesis remains to be identified. Finite element (FE) models are indispensable tools to investigate mechanical effects of fusion surgeries on post-fusion changes in the adjacent segment kinematics and kinetics. Existing modeling studies validate only their intact FE model against in vitro data and subsequently simulate post-fusion in vivo conditions. The present study provides a novel approach for the comprehensive validation of a lumbar... 

    A modeling study on utilizing SnS2 as the buffer layer of CZT(S, Se) solar cells

    , Article Solar Energy ; Volume 167 , 2018 , Pages 165-171 ; 0038092X (ISSN) Haghighi, M ; Minbashi, M ; Taghavinia, N ; Kim, D. H ; Mahdavi, S. M ; Kordbacheh, A. A ; Sharif University of Technology
    Elsevier Ltd  2018
    CdS is conventionally used as the n-type buffer layer in chalcopyrite (CIG(S, Se)) and Kesterite (CZT(S, Se)) solar cells. CdS is toxic and there are wide attempts to find substitutes for it. Here, we suggest SnS2 as a possible alternative. SnS2 films were deposited by pulsed laser deposition (PLD), characterized to estimate carrier concentration and electron affinity values, and the obtained values were used to model a CZT(S, Se) solar cell. The experimental values of a benchmark CZT(S, Se) cell with efficiency of 12.3% were employed to obtain the density and energy position of defects in CZT(S, Se) and validating the model. We observed that SnS2 results in almost identical performance as...