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Synthesis-structure-performance correlation for poly-aniline-Me-C non-precious metal cathode based on mesoporous carbon catalysts for oxygen reduction reaction in low temperature fuel cells
, Article Renewable Energy ; Volume 77 , 2015 , Pages 558-570 ; 09601481 (ISSN) ; Samiee, L ; Fattahi, M ; Seifkordi, A. A ; Shoghi, F ; Maghsodi, A ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
In this work, attempt is made to development of active non-precious metal catalysts (NPMCs) for the oxygen reduction reaction in polymer electrolyte fuel cells (PEFCs) based on the heat treatment of poly-aniline/transition metal/carbon precursors. All the materials have been characterized by X-ray diffraction (XRD) small and wide angle, N2 adsorption-desorption isotherms, high-resolution transmission electron microscopy (TEM), Scanning electron microscope (SEM) and X-ray photo-electron spectroscopy (XPS). Moreover for electrochemical evaluation of samples, Rotating Disk electrode (RDE) technique and Fuel Cell test were employed. The results showed that onset potential for the optimized...
Developing a feed forward multilayer neural network model for prediction of CO2 solubility in blended aqueous amine solutions
, Article Journal of Natural Gas Science and Engineering ; Volume 21 , November , 2014 , Pages 19-25 ; ISSN: 18755100 ; Mazinani, S ; Davardoost, F ; Mokhtare, A ; Najibi, H ; Van der Bruggen, B ; Darvishmanesh, S ; Sharif University of Technology
2014
Abstract
Absorption of carbon dioxide (CO2) in aqueous solutions can be improved by the addition of other compounds. However, this requires a large amount of equilibrium data for solubility estimation in a wide ranges of temperature, pressure and concentration. In this paper, a model based on an artificial neural network (ANN) was proposed and developed with mixtures containing monoethanolamine (MEA), diethanolamine (DEA), methyldiethanolamine (MDEA), 2-amino-2-methyl-1-propanol (AMP), methanol, triethanolamine (TEA), piperazine (PZ), diisopropanolamine (DIPA) and tetramethylensulfone (TMS) to predict solubility of CO2 in mixed aqueous solution (especially in binary and ternary mixtures) over wide...
The Use of Non-platinum Electro-catalyst for Low Temperature Fuel Cells
, M.Sc. Thesis Sharif University of Technology ; Samiee, Leila (Supervisor) ; Seifkordi, Ali Akbar (Co-Advisor)
Abstract
In the recent decades, Polymer Electrolyte Membrane Fuel Cells (PEFC) have been known as an appropriate type of fuel cells, due to being electrochemical converter and clean energy generator with high power density and having low operation temperature and launch time. Palatine is one of the major materials that are used in electro-catalysts of fuel cell. Due to shortage of palatine resources and its high price, fuel cell production is not economical. To achieve economic conditions for production of fuel cell, two major methods are proposed:
1) Reduction of the employed amount of palatine in electro-catalyst
2) Full replacement of palatine with cheap materials
In the current...
1) Reduction of the employed amount of palatine in electro-catalyst
2) Full replacement of palatine with cheap materials
In the current...
Numerical investigation on the effect of the size and number of stages on the tesla microvalve efficiency
, Article Journal of Mechanics ; Volume 29, Issue 3 , 2012 , Pages 527-534 ; 17277191 (ISSN) ; Kolahdouz, E. M ; Shirani, E ; Shafii, M. B ; Sharif University of Technology
2012
Abstract
In the present study, the effect of the number of stages of Tesla Micro-Valve (TMV), as well as the dependency of Reynolds number, Re, on the valve performance has been analyzed. For this purpose, different layouts include one to four-stage with different sizes are investigated numerically. The main criterion for evaluation of valves performance is diodicity, Di. Unsteady and steady flow in valve have been simulated and compared. It is shown that although there are some difference but the trend is similar for both responses. Finally, 2-D and steady state computations of the fluid flow have been utilized that reveal a strong dependence of Di on Re and pressure drop, ΔP. The results showed...
Numerical study on the performance of Tesla type microvalve in a valveless micropump in the range of low frequencies
, Article Journal of Micro-Bio Robotics ; Volume 8, Issue 3 , 2013 , pp 145-159 ; 21946418 (ISSN) ; Kolahdouz, E. M ; Shirani, E ; Shafii, M. B ; Sharif University of Technology
2013
Abstract
In this study, the performance of Tesla-type microvalves, used in micropumps for low frequency driving force, is examined. Three-dimensional and unsteady numerical analysis of fluid flow inside a valveless reciprocating micropump in the range of low working frequencies is carried out. Reciprocating movement of flow actuator provides the actuation and pumping of the working fluid. Ferrofluidic valveless micropump is one practical sample of this kind of micropumps that operate in the range of low working frequencies. To model the reciprocating movement of flow actuator, two time varying functions that includes sinusoidal and step excitation are employed. Also, the performance of...
Simultaneous variation-aware architecture exploration and task scheduling for MPSoC energy minimization
, Article Proceedings of the ACM Great Lakes Symposium on VLSI, GLSVLSI ; 2011 , Pages 271-276 ; 9781450306676 (ISBN) ; Ghorbani, M ; Goudarzi, M ; Sanaei, E
2011
Abstract
In nanometer-scale process technologies, the effects of process variations are observed in Multiprocessor System-on-Chips (MPSoC) in terms of variations in frequencies and leakage powers among the processors on the same chip as well as across different chips of the same design. Traditionally, worst-case values are assumed for these parameters and then a deterministic optimization technique is applied to the MPSoC application under design. We show that such worst-case-based approaches are not optimal with the increasing variation observed at system-level, and instead, statistical approaches should be employed. We consider the problem of simultaneously choosing MPSoC architecture and task...
Monitoring the role of polymer and surfactant concentrations on bubble size distribution in colloidal gas aphron based fluids
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 556 , 2018 , Pages 93-98 ; 09277757 (ISSN) ; Kazemzadeh, E ; Kamari, E ; Ghazanfari, M. H ; Soleymani, M ; Sharif University of Technology
Elsevier B.V
2018
Abstract
Colloidal gas aphron (CGA) based fluids have recently been introduced to develop depleted hydrocarbon reservoirs due to their ability in controlling fluid losses. Bubbles size of CGAs plays an important role in pore blockage ability as the controlling mechanism in fluid invasion reduction. However, fundamental understanding of how bubble size distribution is controlled by polymer and surfactant concentrations is not well discussed in the available literature. Almost all reported experiences on CGAs sizing were conducted on single bubble behavior, and little attention has been given to the variation of bubble size distribution (BSD) of CGAs at different levels of polymer/surfactant...
Investigating fluid invasion control by Colloidal Gas Aphron (CGA) based fluids in micromodel systems
, Article Journal of Natural Gas Science and Engineering ; Volume 66 , 2019 , Pages 1-10 ; 18755100 (ISSN) ; Kamari, E ; Kazemzadeh, E ; Ghazanfari, M. H ; Soleymani, M ; Sharif University of Technology
Elsevier B.V
2019
Abstract
Recently, Colloidal Gas Aphron (CGA) based fluids have been introduced to further develop depleted hydrocarbon reservoirs. This fluid system has been employed in an attempt to control drilling fluid invasion and, thus, reducing formation damage occurred during drilling operations. Understanding the mechanisms of fluid invasion control is of great importance for successful design and application of CGA-based fluids in drilling operations. Although fluid flow of conventional foams has been studied extensively in the available literature, little attention has been paid to CGA fluids flow, especially in heterogeneous fractured porous media. Here, an experimental study was conducted to achieve...
Insight into the behavior of colloidal gas aphron (CGA) fluids at elevated pressures: an experimental study
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 537 , January , 2018 , Pages 250-258 ; 09277757 (ISSN) ; Kazemzadeh, E ; Kamari, E ; Ghazanfari, M. H ; Soleymani, M ; Sharif University of Technology
Elsevier B.V
2018
Abstract
Recently, colloidal gas aphron (CGA) fluids technology has been employed to drill depleted oil and gas reservoirs. Almost all reported experience on CGA fluids were conducted at ambient conditions, and little attention has been paid on the behavior of CGAs at high pressures which is more close to real conditions. In this study, high pressure experiments were conducted by using High Pressure Microscope cell to visualize/monitor the behavior of CGAs at elevated pressures. Single bubble behavior and bubble size distribution (BSD) of CGAs were investigated under different scenarios of pressure change. Results of experiments revealed that BSD of CGAs is controlled by the path of pressure changes,...
Authors’ reply to a comment on M. pasdar et al article
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 561 , 2019 , Pages 407-408 ; 09277757 (ISSN) ; Kazemzadeh, E ; Kamari, E ; Ghazanfari, M. H ; Soleymani, M ; Sharif University of Technology
Elsevier B.V
2019
Insight into selection of appropriate formulation for colloidal gas aphron (CGA)-based drilling fluids
, Article Petroleum Science ; Volume 17, Issue 3 , 2020 , Pages 759-767 ; Kazemzadeh, E ; Kamari, E ; Ghazanfari, M. H ; Soleymani, M ; Sharif University of Technology
China University of Petroleum Beijing
2020
Abstract
Application of light-weight drilling fluids is essential to develop depleted hydrocarbon reservoirs. Recently, colloidal gas aphron (CGA)-based fluids have been introduced for such applications due to their ability in controlling fluid losses. In this work, a comprehensive experimental study was performed to choose the best formulation for CGA fluids by implementing static stability tests, rheological behavior measurements, and bubble size analyses of CGAs. Xanthan gum polymer and sodium dodecyl benzene sulfonate (SDBS), an anionic surfactant, and cetyl trimethyl ammonium bromide (CTAB), a cationic surfactant, were utilized to prepare CGAs. For the range of experiments conducted, the...
Effect of localized corrosion on the galvanic corrosion of nitinol and dental alloys
, Article Anti-Corrosion Methods and Materials ; Volume 56, Issue 6 , 2009 , Pages 323-329 ; 00035599 (ISSN) ; Shirazi, M ; Rahman, M ; Fakheri, E ; Aref, M. R
2009
Abstract
Purpose: The purpose of this paper is to evaluate the galvanic corrosion of nitinol orthodontic wires with six dental alloys in artificial saliva and consider the effect of initiated localized corrosion and real surfaces of anode and cathode on galvanic current. Design/methodology/approach: Linear polarization and cyclic polarization curves for each alloy in de-aerated Duffo and Castillo's artificial saliva are obtained. Galvanic corrosion investigation is conducted by polarization curve intersection and mixed potential theory methods. In order to verify the initiation of localized corrosion, scanning electron microscopy is used. Findings: Initiation of localized corrosion on the anode...
Synthesis of dithiocarbamates by Markovnikov addition reaction in PEG and their application in amidoalkylation of naphthols and indoles
, Article Journal of the Brazilian Chemical Society ; Volume 26, Issue 7 , 2015 , Pages 1500-1508 ; 01035053 (ISSN) ; Dadras, A ; Ramezani, M ; Shamiri, E. V ; Hooshmand, S. E ; Hashemi, M. M ; Sharif University of Technology
Sociedade Brasileira de Quimica
2015
Abstract
Synthesis of dithiocarbamates by the one-pot three-component Markovnikov addition reaction of an amine, carbon disulfide and an alkyl vinyl ether or N-vinylpyrrolidone is reported in polyethylene glycol (PEG) under a mild and green procedure with high yields and completely regiospecific. Also, the products were used as efficient starting materials for amidoalkylation of electron-rich arenes such as naphthols and indoles
Parallel in-vitro and in-vivo techniques for optimizing cellular microenvironments by implementing biochemical, biomechanical and electromagnetic stimulations
, Article Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS ; 2012 , Pages 1397-1400 ; 1557170X (ISSN) ; 9781424441198 (ISBN) ; Heibatollahi, M ; Ghafar Zadeh, E
2012
Abstract
Development of novel engineering techniques that can promote new clinical treatments requires implementing multidisciplinary in-vitro and in-vivo approaches. In this study, we have implemented microfluidic devices and in-vivorat model to study the mechanism of neural stem cell migration and differentiation.These studies can result in the treatment of damages to the neuronal system. In this research, we have shown that by applying appropriate ranges of biochemical and biomechanical factors as well as by exposing the cells to electromagnetic fields, it is possible to improve viability, proliferation, directional migration and differentiation of neural stem cells. The results of this study can...
The effect of soot nano-particles injection on two-phase smoke aerosol formation in a kerosene-fired burner
, Article 54th AIAA Aerospace Sciences Meeting, 2016, 4 January 2016 through 8 January 2016 ; 2016 ; 9781624103933 (ISBN) ; Ghafourizadeh, M ; Schneider, G. E
American Institute of Aeronautics and Astronautics Inc, AIAA
2016
Abstract
Feeding a laboratory furnace with the gaseous kerosene, the resulting two-phase turbulent flame is simulated to study the effects of injecting soot nano-particles into the inflow air on the emissions of smoke aerosol, CO, and CO2species pollutants, and the resulting radiation heat transfer. We use our past experiences in aerosol modeling of soot nano/micro particles in turbulent nonpremixed flames burning simple hydrocarbon fuels and extend them to study the effects of injecting gaseous kerosene on the aforementioned parameters. To model the evolutionary process of soot nanoparticle formation, i.e., the nucleation, coagulation, surface growth, and oxidation, we employ a two-equation soot...
CFD-aided simulation of frost growth inside a narrow duct with uniform wall temperature variation
, Article ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM 2014, Collocated with the ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting ; 2014 ; ISBN: 9780791846278 ; Asgari, E ; Hajikaram, M ; Schneider, G. E ; Sharif University of Technology
2014
Abstract
In this paper, we study the frost formation and growth at the walls of a duct with uniform wall temperature variation. The simulation is performed for laminar flow regime considering suitable semi-empirical models incorporated with computational fluid dynamics (CFD) method. The frost growth is considered to be normal to the duct surface. Since the duct aspect ratio is high, we perform our simulations in two-dimensional zones. To simulate the frost layer properly, we solve both the energy and mass balance equations implementing some semi-empirical correlations on the frost side. At this stage, we suitably predict the required heat flux value at the solid boundary and the heat transfer...
Using the direct simulation Monte Carlo method to study the effect of wall temperature variation on gas mixing evolution through micro T-mixers
, Article 11th International Energy Conversion Engineering Conference ; 2013 ; Sabouri, M ; Lekzian, E ; Schneider, G. E ; Sharif University of Technology
2013
Abstract
In this work, we study the gas mixing behavior in a micro T-mixer using the direct simulation Monte Carlo (DSMC) method. The gas mixing process is monitored through a T-mixer, which is fed by two different CO and N2 gases; flowing into the T-mixer through the upper and lower inlets. We investigate the effects of axial and lateral wall temperature gradients on the mixing evolution at different rarefaction levels. The achieved results show that any temperature difference between the channel walls would result in an increase in mixing length for the chosen wall temperature gradient ranges and the studies pressure cases. Our observations show that a positive temperature gradient toward the...
Plasma density ramp for relativistic self-focusing of an intense laser: Comment
, Article Journal of the Optical Society of America B: Optical Physics ; Volume 27, Issue 9 , 2010 , Pages 1731-1734 ; 07403224 (ISSN) ; Yazdani, E ; Habibi, M ; Lotfi, E ; Sharif University of Technology
Optical Society of American (OSA)
2010
Abstract
Gupta et al. [J. Opt. Soc. Am. B. 24, No. 5 (2007)] have introduced a localized upward plasma density ramp to overcome the defocusing of a laser beam. We report that there are fundamental mistakes in their work. First, the density profile formula that they have introduced is dimensionally incorrect. Second, the calculated dielectric constant is wrong as well, which renders their main spot size equation and the quantitative results unacceptable, and it seriously falters the results of the self-focusing. We correctly derived a new equation of the spot size, and the computational curves are also presented
CaZnO-based nanoghosts for the detection of ssDNA, pCRISPR and recombinant SARS-CoV-2 spike antigen and targeted delivery of doxorubicin
, Article Chemosphere ; Volume 306 , 2022 ; 00456535 (ISSN) ; Akhavan, O ; Fatahi, Y ; Ghadiri, A. M ; Kiani, M ; Makvandi, P ; Rabiee, M ; Nicknam, M. H ; Saeb, M. R ; Varma, R. S ; Ashrafizadeh, M ; Nazarzadeh Zare, E ; Sharifi, E ; Lima, E. C ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Overexpression of proteins/antigens and other gene-related sequences in the bodies could lead to significant mutations and refractory diseases. Detection and identification of assorted trace concentrations of such proteins/antigens and/or gene-related sequences remain challenging, affecting different pathogens and making viruses stronger. Correspondingly, coronavirus (SARS-CoV-2) mutations/alterations and spread could lead to overexpression of ssDNA and the related antigens in the population and brisk activity in gene-editing technologies in the treatment/detection may lead to the presence of pCRISPR in the blood. Therefore, the detection and evaluation of their trace concentrations are of...
Nanodiamonds for surface engineering of orthopedic implants: Enhanced biocompatibility in human osteosarcoma cell culture [electronic resource]
, Article Diamond and Related Materials ; Volume 40, 2013, Pages 107-114 ; Shokrgozar, M. A ; Mehrjoo, M ; Tamjid, E ; Simchi, A ; Sharif University of Technology
Abstract
Recently, nanodiamonds have attracted interest in biomedical applications such as drug delivery, targeted cancer therapies, fabrication of tissue scaffolds, and biosensors. We incorporated diamond nanoparticles in alginate–bioactive glass films by electrophoretic process to prepare functional coatings for biomedical implants. Turbidity examination by time-resolved laser transmittance measurement revealed that a stable multi-component aqueous suspension of alginate, bioactive glass and diamond particles could be obtained at concentrations of 0.6, 1.3, and 0.65 g/l, respectively. Uniform films with ~ 5 μm thickness were deposited on 316 stainless steel foils by employing constant field...