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    Finite element modeling of single-walled carbon nanotubes with introducing a new wall thickness

    , Article Journal of Physics: Conference Series ; Volume 61, Issue 1 , 2007 , Pages 497-502 ; 17426588 (ISSN) Jalalahmadi, B ; Naghdabadi, R ; Sharif University of Technology
    Institute of Physics Publishing  2007
    A three-dimensional finite element (FE) model for armchair, zigzag and chiral single-walled carbon nanotubes (SWCNTs) is proposed. By considering the covalent bonds as connecting elements between carbon atoms, a nanotube is simulated as a space frame-like structure. Here, the carbon atoms act as joints of the connecting elements. To create the FE models, nodes are placed at the locations of carbon atoms and the bonds between them are modeled using three-dimensional elastic beam elements. Using Morse atomic potential, the elastic moduli of beam elements are obtained via considering a linkage between molecular and continuum mechanics. Also, a new wall thickness (bond diameter) equal to 0.1296... 

    The effect of carbon on the restoration phenomena during hot deformation of carbon steels

    , Article Zeitschrift fuer Metallkunde/Materials Research and Advanced Techniques ; Volume 94, Issue 8 , 2003 , Pages 916-921 ; 00443093 (ISSN) Serajzadeh, S ; Karimi Taheri, A ; Zebarjad, S. M ; Sharif University of Technology
    Carl Hanser Verlag  2003
    A study has been made to determine the influence of the carbon content on the kinetics of dynamic and static recrystallization during and after hot deformation of carbon steels. For this purpose, single- and double-hit hot compression experiments at various strain rates and temperatures together with the Avrami-type kinetics equation and Bergstrom approach have been utilized to investigate recrystallization behavior. The results show that the apparent activation energy of hot deformation decreases with increasing carbon content and this phenomenon results in a faster dynamic recrystallization at high temperatures and/or low strain rates. Also, increasing carbon content leads to a higher rate... 

    Studies on treatment of carbonaceous wastewater by Fixed Film Aeration Tank

    , Article Scientia Iranica ; Volume 9, Issue 1 , 2002 , Pages 47-52 ; 10263098 (ISSN) Yaghmaei, S ; Sharif University of Technology
    Sharif University of Technology  2002
    In this paper, a modified activated sludge process using a Fixed Film Aeration Tank (FFAT) was investigated as an improvement for the usual activated sludge or trickling filtration processes. The aeration tank of the system was arranged with fixed parallel saran nets, which were set vertically as supporting media for microbial growth. A carbonaceous solution was brought into contact with microorganisms in the media and was oxidized aerobically. Filamentous microorganisms predominantly grew on the films and the COD removal increased with the increase in accumulated biomass in the system. Simulation of treatment performance in the system was carried out using mathematical models. The... 

    Concentration of Low Grade Zinc Carbonate ore of Anguran Mine by Froth Flotation

    , M.Sc. Thesis Sharif University of Technology Dehghan, Yasser (Author) ; Halali, Mohammad (Supervisor)
    In this work feasibility of concentrating zinc carbonate ore from Anguran mine by froth flotation process has been studied. Potasium Amyl Xhantate and Oleic Acid have been studied as possible collectors. The initial tests indicate that oleic acid might be a better collector. Experimental were conducted to determined important factors and to optimize the process by careful control of the pulp chemical composition and flotation variables. A concentrate containing 24.9% zinc has been attained. The recovery of zinc in the concentrate is 76.1%.

    Convective stability of carbon sequestration in anisotropic porous media

    , Article Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences ; Vol. 470, Issue. 2170 , 2014 ; ISSN: 13645021 Hill, A. A ; Morad, M. R ; Sharif University of Technology
    The stability of convection in an anisotropic porous medium, where the solute concentration is assumed to decay via a first-order chemical reaction, is studied. This is a simplified model for the interactions between carbon dioxide and brine in underground aquifers; the instability of which is essential in reducing reservoir mixing times. The key purpose of this paper is to explore the role porous media anisotropy plays in convective instabilities. It is shown that varying the ratio of horizontal to vertical solutal diffusivites does not significantly affect the behaviour of the instability. This is also the case for changes of permeability when the diffusion rate dominates the solute... 

    Effect of microstructure on attenuation mechanism of ultrasonic waves in carbon steels

    , Article Materials Science and Technology ; Volume 26, Issue 4 , 2010 , Pages 482-486 ; 02670836 (ISSN) Behjati, P ; Vahid Dastjerdi, H ; Mahdavi, R ; Rasouli, D ; Sharif University of Technology
    In this paper, fundamental concepts of ultrasonics and characteristics of distinctive microstructures have been used to simply explain the effect of microstructure on the attenuation mechanism of ultrasonic waves in carbon steels. In addition, it has been shown that application of the second medium hardness instead of the bulk hardness is more appropriate to correlate the sound velocity and the microstructure  

    Surface modification of glassy carbon electrode with the functionalized carbon nanotube for ultrasensitive electrochemical detection of risperidone

    , Article Journal of the Iranian Chemical Society ; Volume 15, Issue 7 , July , 2018 , Pages 1485-1494 ; 1735207X (ISSN) Shahrokhian, S ; Hafezi Kahnamoui, M ; Salimian, R ; Sharif University of Technology
    Springer Verlag  2018
    Risperidone (RIS), one of the typical antipsychotics drugs, originally approved to be used for the mental illness treatment, especially schizophrenia, bipolar disorder, autism and major depression. In the present study, different carbon nanostructures including functionalized multi-walled carbon nanotubes (F-MWCNTs), carbon nanoparticles, nanodiamond-graphite and reduced graphene oxide were employed for modification of the surface of glassy carbon electrode (GCE) for ultrasensitive detection of RIS. The most significant increase in the anodic peak current of RIS was observed on F-MWCNTs-modified electrode (compared to the other modified electrodes and bare GCE). The influence of different... 

    Biocompatible magnetic N-rich activated carbon from egg white biomass and sucrose: Preparation, characterization and investigation of dye adsorption capacity from aqueous solution

    , Article Surfaces and Interfaces ; Volume 15 , 2019 , Pages 157-165 ; 24680230 (ISSN) Vahdati Khajeh, S ; Zirak, M ; Zooghi Tejrag, R ; Fathi, A ; Lamei, K ; Eftekhari Sis, B ; Sharif University of Technology
    Elsevier B.V  2019
    In the present work, N-rich activated carbon was synthesized using hydrothermal carbonization of egg white biomass in the presence of sucrose, followed by chemical activation and magnetization of hydrochar in the presence of iron (II) and (III) at NaOH solution. The results showed that the sucrose has a critical role in hydrochar yield by increasing of sucrose content. This claim also proved by SEM analysis, which hydrochar morphology was changed from the layered to fused carbon spheres morphology that confirmed the increasing of nucleation site. The materials were characterized with VSM, SEM, CHN, FTIR, Raman spectroscopy and XRD techniques. Capacity of prepared magnetic activated carbon... 

    Study of the effect of fluid flow on corrosion rate for simple carbon steel in aqueous solution using rotating disk electrode

    , Article 18th International Congress of Chemical and Process Engineering, CHISA 2008, Prague, 24 August 2008 through 28 August 2008 ; 2008 Bastani, D ; Mohagheghi, A ; Sharif University of Technology
    The influence of fluid flow on the corrosion of simple carbon steel ST37 (AISI 1020) in aqueous solution of Bandar-Abbas gas well was studied at 25°C under air-saturated condition. The mechanism and kinetic of corrosion in different hydrodynamic conditions were determined using a rotating disk electrode. Increasing the velocity of rotating disk ≤ 1000 rpm caused an augmentation in corrosion rate from 9.89 to 18.95 mill in./yr. Increasing the velocity beyond 1000 rpm changed the corrosion mechanism so that the activation polarization will control the corrosion process, and the variation in corrosion rates was due to various corrosion mechanisms rather than mass transfer of reactant component.... 

    As-cast mechanical properties of vanadium/niobium microalloyed steels

    , Article Materials Science and Engineering A ; Volume 486, Issue 1-2 , 2008 , Pages 1-7 ; 09215093 (ISSN) Najafi, H ; Rassizadehghani, J ; Asgari, S ; Sharif University of Technology
    Tensile and room temperature Charpy V-notch impact tests along with microstructural studies were used to evaluate the variations in the as-cast mechanical properties of low-carbon steels with and without vanadium and niobium. Tensile test results indicate that good combinations of strength and ductility can be achieved by microalloying additions. While the yield strength and UTS increase up to respectively 370-380 and 540-580 MPa in the microalloyed heats, their total elongation range from 20 to 25%. TEM studies revealed that random and interphase fine-scale microalloy precipitates play a major role in the strengthening of the microalloyed heats. On the other hand, microalloying additions... 

    A study on strain ageing during and after warm rolling of a carbon steel

    , Article Materials Letters ; Volume 62, Issue 6-7 , 2008 , Pages 946-948 ; 0167577X (ISSN) Serajzadeh, S ; Akhgar, J. M ; Sharif University of Technology
    In this study, strain ageing during and after warm rolling of a carbon steel has been investigated. At the first step, the occurrence of serrated flow was studied by means of tensile tests at different temperatures and strain rates. In the next stage, warm rolling experiments were performed under different rolling conditions and then the samples were aged at the room temperature for a period of 3 months. For both aged and non-aged samples, tensile tests were employed to evaluate their mechanical properties. The results show that static strain ageing is possible to happen in the utilized ageing period and increases the yield stress of the aged steel. However, the samples that experience both... 

    Multi-walled carbon nanotube paste electrode for selective voltammetric detection of isoniazid

    , Article Microchimica Acta ; Volume 157, Issue 3-4 , 2007 , Pages 149-158 ; 00263672 (ISSN) Shahrokhian, S ; Amiri, M ; Sharif University of Technology
    A multi-walled carbon nanotube paste electrode (MWCPE) is prepared as an electrochemical sensor with high sensitivity and selectivity in responding to isoniazid. The electrochemical oxidation of isoniazid is investigated in buffered solution by cyclic and differential pulse voltammetry. The electrode is shown to be very effective for the detection of isoniazid in the presence of other biological reductant compounds. The electrochemical oxidation of cysteine, due to the high overvoltage, is completely stopped at the surface of MWCPE. The electrode exhibits a very good resolution between the voltammetric peak of isoniazid and the peaks of ascorbic acid (AA) and dopamine (DA). A resolution of... 

    Process optimization for mineral carbonation in aqueous phase

    , Article International Journal of Mineral Processing ; Vol. 130 , July , 2014 , pp. 20-27 ; ISSN: 03017516 Hemmati, A ; Shayegan, J ; Bu, J ; Yeo, T. Y ; Sharratt, P ; Sharif University of Technology
    Carbon dioxide sequestration by a pH-swing carbonation process was considered in this work. A multi-step aqueous process is described for the fractional precipitation of magnesium carbonate and other minerals in an aqueous system at room temperature and atmospheric pressure. With the aim to achieve higher purity and deliver more valuable mineral products, the process was split into four steps. The first step consists of Mg leaching from the magnesium silicate in a stirred vessel using 1 M HCl at 80 °C, followed by a three step precipitation in reactors in sequence to remove Fe(OH)3, then Fe(OH)2 and other divalent ions, and finally MgCO3 nucleation and growth. Hydrated magnesium carbonate... 

    Experimental and theoretical study on BTEX removal from aqueous solution of diethanolamine using activated carbon adsorption

    , Article Journal of Natural Gas Science and Engineering ; Volume 22 , 2015 , Pages 618-624 ; 18755100 (ISSN) Aleghafouri, A ; Hasanzadeh, N ; Mahdyarfar, M ; SeifKordi, A ; Mahdavi, S. M ; Zoghi, A. T ; Sharif University of Technology
    Elsevier  2015
    Activated carbon beds are extensively used in sweetening units of natural gas refineries for the purification of contaminated amine solutions. Correlation of experimental adsorption data using an analytical isotherm equation is need to design an accurate activated carbon bed. In the present study, the adsorption of BTEX from Diethanolamine (DEA) solution by commercial and granular activated carbon (AC) were performed. The Langmuir, Freundlich and Sips isotherm models were used to describe the equilibrium data. The accuracy of the results obtained from the adsorption isotherm models was compared and the values for the regressed parameters were reported. The results show that the Freundlich... 

    On the pull-in instability of double-walled carbon nanotube-based nano electromechanical systems with cross-linked walls

    , Article Fullerenes Nanotubes and Carbon Nanostructures ; Volume 23, Issue 4 , Dec , 2015 , Pages 300-314 ; 1536383X (ISSN) Seyyed Fakhrabadi, M. M ; Rastgoo, A ; Ahmadian, M. T ; Sharif University of Technology
    Taylor and Francis Inc  2015
    This paper presents the deflection and pull-in instability of the double-walled carbon nanotubes with different dimensions and boundary conditions. Molecular dynamic technique is applied to model the desired behaviors of the nano systems. The effects of cross-linking between the carbon walls are investigated on the pull-in charge. In addition, the influences of axial stretching on the pull-in charge and vibrational frequencies of the carbon nanotubes are scrutinized. The effects of electrostatic charge distribution on the vibration amplitude are also reported  

    Investigation of oil recovery and CO2 storage during secondary and tertiary injection of carbonated water in an Iranian carbonate oil reservoir

    , Article Journal of Petroleum Science and Engineering ; Volume 137 , 2016 , Pages 134-143 ; 09204105 (ISSN) Shakiba, M ; Ayatollahi, S ; Riazi, M ; Sharif University of Technology
    Gas injection process for more oil recovery and in particular CO2 injection is well-established method to increment oil recovery from underground oil reservoirs. CO2 sequestration which takes place during this enhanced oil recovery (EOR) method has positive impact on reducing the greenhouse gas emission which causes global warming. Direct gas injection into depleted oil reservoirs, encounters several shortcomings such as low volumetric sweep efficiency, early breakthrough (BT) and high risk of gas leakage in naturally fractured carbonate oil reservoirs. Carbonated water injection (CWI) has been recently proposed as an alternative method to alleviate the problems associated with gas... 

    The impact of connate water saturation and salinity on oil recovery and CO2 storage capacity during carbonated water injection in carbonate rock

    , Article Chinese Journal of Chemical Engineering ; Volume 27, Issue 7 , 2019 , Pages 1699-1707 ; 10049541 (ISSN) Shakiba, M ; Riazi, M ; Ayatollahi, S ; Takband, M ; Sharif University of Technology
    Chemical Industry Press  2019
    Carbonated water injection (CWI) is known as an efficient technique for both CO2 storage and enhanced oil recovery (EOR). During CWI process, CO2 moves from the water phase into the oil phase and results in oil swelling. This mechanism is considered as a reason for EOR. Viscous fingering leading to early breakthrough and leaving a large proportion of reservoir un-swept is known as an unfavorable phenomenon during flooding trials. Generally, instability at the interface due to disturbances in porous medium promotes viscous fingering phenomenon. Connate water makes viscous fingers longer and more irregular consisting of large number of tributaries leading to the ultimate oil recovery... 

    Effective carbon composite electrode for low-cost perovskite solar cell with inorganic CuIn0.75Ga0.25S2 hole transport material

    , Article Solar RRL ; Volume 4, Issue 5 , 2020 Behrouznejad, F ; Forouzandeh, M ; Khosroshahi, R ; Meraji, K ; Badrabadi, M. N ; Dehghani, M ; Li, X ; Zhan, Y ; Liao, Y ; Ning, Z ; Taghavinia, N ; Sharif University of Technology
    Wiley-VCH Verlag  2020
    Perovskite solar cells are well known for being low cost, solution-based, and efficient solar cells; however, the high price of the conventional hole-collector electrode (Spiro-OMeTAD/Gold) and the high price and complexity of depositing gold on large scales are major barriers against commercializing them. Herein, an effective carbon composite electrode is introduced for a low-cost perovskite solar cell with CuIn0.75Ga0.25S2 hole transport material to solve this problem. The carbon electrode is deposited by the doctor blade method using a paste composed of flakes of graphite, carbon black, and a kind of hydrophobic polymer (polystyrene or poly-methyl methacrylate). It is investigated how the... 

    Nanoporous composites of activated carbon-metal organic frameworks for organic dye adsorption: Synthesis, adsorption mechanism and kinetics studies

    , Article Journal of Industrial and Engineering Chemistry ; Volume 81 , 2020 , Pages 405-414 Hasanzadeh, M ; Simchi, A ; Shahriyari Far, H ; Sharif University of Technology
    Korean Society of Industrial Engineering Chemistry  2020
    Activated carbon (AC) is an inert adsorbent material that has widely been used in water treatment or removing of environmental pollutants from water. In order to improve the adsorption of AC, which highly depends on its pore size and surface area, we prepared highly porous adsorbent composites of activated carbon (AC)/chromium-based MOF (MIL-101(Cr)). The composite has a high specific surface area of 2440 m2 g−1 and total pore volume of 1.27 cm3 g−1. To show the efficiency of the composite as an adsorbent, the removal kinetics of anionic dyes (Direct Red 31 and Acid Blue 92) from aqueous solutions dependent on the amount of composite, adsorption time, concentration of dye and pH is... 

    Electrochemical Sensors Based on Electrodes Modified with Composites of Carbon Nanostructures and Polypyrrole; Application to Electrochemical Investigations and Determination of Nifedipine and Tizanidine

    , M.Sc. Thesis Sharif University of Technology Shamloofard, Maryam (Author) ; Shahrokhian, Saeed (Supervisor)
    In the first part, the electropolymerization of pyrrole was performed in the presence of Titan Yellow (TY) as a dopant anion on the surface of the electrode precoated with CNTs. The modified electrode was used to study the voltammetric response of tizanidine (TIZ). A remarkable increase was observed in the anodic peak current of TIZ on the surface of the modified electrode relative to the bare GCE. The surface morphology PPY/CNT/GCE was thoroughly characterized by scanning electron microscopy (SEM) and cyclic voltammetry (CV) techniques. Under the optimized analysis conditions, the modified electrode showed two linear dynamic ranges of 0.01 - 1 μM and 1-10 μM with a detection limit of 3 nM...