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askaripour--hossein
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Investigating the Production of Phytase Enzyme via Bacillus Subtilis and Probiotic Bacteria in an Industrial Culture Medium
, M.Sc. Thesis Sharif University of Technology ; Askaripour, Hossein (Supervisor)
Abstract
This study focuses on the optimization of process conditions and culture medium for the production of phytase enzyme from two bacterial strains, Bacillus subtilis ATCC6633 and Lactobacillus acidophilus DSM17299, for potential use in the animal and poultry feed industry. Initially, optimal culture medium design for enzyme production was conducted using Minitab software and the Central Composite Design (CCD) method. Four variables—temperature, pH, carbon source concentration (wheat bran), and nitrogen source concentration (soybean meal)—were simultaneously investigated. Following data analysis with statistical methods, the optimal environmental conditions and suitable culture medium...
Simulation of the Production Process of Polyhydroxybutyrate (PHB) Biodegradable Polymer via a Bubble Column Bioreactor
, M.Sc. Thesis Sharif University of Technology ; Askaripour, Hossein (Supervisor)
Abstract
In this study, the biological process of producing polyhydroxybutyrate (PHB), a biodegradable polymer, using methane as the carbon source and nitrate as the nitrogen source was numerically modeled and simulated in an 8 m height and 0.5 m diameter bubble column bioreactor. The primary goal was to develop a time-dependent model capable of simultaneously describing biomass growth, substrate consumption, and polymer production, while accounting for gas–liquid mass transfer and momentum transfer. The modeling was performed under sufficient aeration, and any complications arising from strain swelling due to intracellular accumulation were neglected. Initially, a biomass growth model based on a...
Simulation of the Process of Aerobic Removal of Phenol from Wastewater using a Tubular Biofilm Bioreactor
, M.Sc. Thesis Sharif University of Technology ; Askaripour, Hossein (Supervisor)
Abstract
For several decades, tubular bioreactors have been used in many microbiological processes such as wastewater treatment and biopesticide production. The use of biofilm in bioreactors has positive effects on their technical characteristics, which include increasing the concentration of biomass, preventing depletion and increasing the resistance of cells against the inhibitory effect of toxic compounds. The existing mathematical models for biofilms can be divided into two general categories: analytical and numerical. In this project, the goal is to simulate the removal process of phenol by aerobic microorganisms in a tubular bioreactor with a biofilm layer on its inner wall, using numerical...
Simulation of Phenol Biodegradation by Pseudomonas Putida in a Continuous Stirred Biofilm Reactor
,
M.Sc. Thesis
Sharif University of Technology
;
Yaghmaei, Soheila
(Supervisor)
;
Askaripour, Hossein
(Supervisor)
Abstract
The use of microorganisms to remove or produce a substace is a fundamental part of biotechnology. An example is the bioreactors for phenol removal in wastewater. Biological processes are commonly done in batch reactors in which suspended cells grow in the liquid phase. The batch process needs alternate reactor washes and alternate cell cultivation, which leades to a longer time constant for for each batch. If these reactors operate in continuous conditions, the cells will leave the reactor in liquid flow, and high cell concentrations will be impossible. The biofilm layer makes a batch phase, so the liquid phase flows in and out continuously, but the cells in the biofilm layer stay in the...
Simulation and Optimization of Biogas Production Via Anaerobic Digestion of Biomass
, M.Sc. Thesis Sharif University of Technology ; Rashtchian, Davoud (Supervisor) ; Askaripour, Hossein (Supervisor)
Abstract
Biogas, a mixture of methane and carbon dioxide, is produced through the anaerobic digestion of organic materials where microorganisms, under oxygen-free conditions, convert organic materials through four stages: hydrolysis, acidogenesis, acetogenesis, and methanogenesis. This renewable and sustainable energy source significantly contributes to reducing dependence on fossil fuels, decreasing greenhouse gas emissions, managing organic waste effectively, and preventing soil and water pollution. In this study, the ADM1 model was used to simulate the conversion of organic materials into biogas, with simulations conducted using Aspen Plus and MATLAB software. The system simulated consists of two...
Effect of operating conditions on the performance of a PEM fuel cell
, Article International Journal of Heat and Mass Transfer ; Volume 144 , 2019 ; 00179310 (ISSN) ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
In this study, a two-phase flow model based on species transport, energy, and electrochemical equations was developed for polymer electrolyte membrane fuel cell (PEMFC). The influences of heat sources and sinks, and water transport inside the fuel cell were also taken into account. In this regard, the effect of the operating conditions including cell temperature and pressure, anode and cathode inlet humidity, and anode and cathode stoichiometric ratios on the fuel cell performance was investigated. The simulation results show that inlet humidity and stoichiometric ratio of the anode side, cell pressure and temperature, and distribution of the heat sources and sinks are crucial factors...
CFD modeling of gasification process in tapered fluidized bed gasifier
, Article Energy ; Volume 191 , 2020 ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
This article presents a two-dimensional simulation of the coal gasification in tapered fluidized bed gasifier. The effects of tapered angle, gasifier temperature, velocity of gasifying agent, and steam-to-air ratio on the gas compositions, lower heating value (LHV), and higher heating value (HHV) were examined. In order to find the appropriate operating conditions of coal gasification, carbon conversion efficiency (CCE) and cold gas efficiency (CGE) were also explored. It was found that with an increase of the gasifier temperature, CCE and CGE of the tapered gasifier diminishes. Increasing tapered angle results in a decrease of the LHV and HHV of the gas products, whereas the CCE of...
Optimization of Lipase Production Process in Suitable Strain Culture
, M.Sc. Thesis Sharif University of Technology ; Askaripour, Hossein (Supervisor) ; Roostaazad, Reza (Supervisor) ; Yeganeh Sarkandi, Shahin (Co-Supervisor)
Abstract
In this research, after examining the different strains available in the enzyme center's cell bank, the bacterial strain Pseudomonas aeruginosa (RPMC-B-3556) obtained from the Russian microbial collection was used for lipase production. This microbial strain has the ability to produce extracellular lipase enzyme and for this reason it has been selected as the target strain. The purpose of this research was to optimize the lipase production process in the culture of the appropriate strain. For this purpose, the compounds used in the culture medium are changed to investigate their effect on lipase enzyme activity. Considering that the studied strain has the ability to produce protease enzyme...
Simulation of 3D freely bubbling gas-solid fluidized beds using various drag models: TFM approach
, Article Chemical Engineering Research and Design ; Volume 100 , 2015 , Pages 377-390 ; 02638762 (ISSN) ; Molaei Dehkordi, A ; Sharif University of Technology
Institution of Chemical Engineers
2015
Abstract
In this article, 3D modeling and simulation of bubbling fluidized beds has been conducted using various drag models, and the model predictions were validated against reported experimental data and 2D simulation results. In this regard, different drag models reported in the literature including Gidaspow, Syamlal-O'Brien, Hill-Koch-Ladd, and Wen-Yu were applied. A standard Two-Fluid Model (TFM) closed by the Kinetic Theory of Granular Flows (KTGF) was used to simulate bubbling gas-solid fluidized beds. Excellent agreements between the simulation results and experimental data, concerning bed expansion ratio, gas volume fraction, and time-averaged particles velocity, were found over a wide range...
Effects of initial static bed height on fractional conversion and bed pressure drop in tapered-in and tapered-out fluidized bed reactors
, Article International Journal of Multiphase Flow ; Volume 79 , 2016 , Pages 50-61 ; 03019322 (ISSN) ; Molaei Dehkordi, A ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
In this article, a standard 2D Two-Fluid Model (TFM) closed by the kinetic theory of granular flow (KTGF) has been applied to simulate the behavior of tapered-in and tapered-out fluidized bed reactors. In this regard, two types of chemical reactions with gas volume reduction and increase were considered to investigate the effects of initial static bed height on the fractional conversion and bed pressure drop. To validate the CFD model predictions, the results of hydrodynamic simulations concerning bed pressure drop and bed expansion ratio were compared against experimental data reported in the literature and excellent agreement was observed. The obtained simulation results clearly indicate...
Two-dimensional CFD simulation of chemical reactions in tapered-in and tapered-out fluidized bed reactors
, Article Advanced Powder Technology ; 2018 ; 09218831 (ISSN) ; Dehkordi, A. M ; Sharif University of Technology
Elsevier B.V
2018
Abstract
This article presents a simulation study of tapered-in and tapered-out fluidized bed reactors to investigate the influences of apex angle on the fractional conversion and the pressure drop of the fluidized beds in the presence of two types of chemical reaction with gas volume increase and reduction. The 2D behavior of tapered-in and -out fluidized beds was also compared with a columnar one from fractional conversion and bed pressure drop point of views. To validate the simulation results, the numerical predictions for the expansion ratio and the pressure drop of a tapered fluidized bed were compared with experimental data and good agreement was observed. The obtained simulation results...
Two-dimensional CFD simulation of chemical reactions in tapered-in and tapered-out fluidized bed reactors
, Article Advanced Powder Technology ; Volume 30, Issue 1 , 2019 , Pages 136-147 ; 09218831 (ISSN) ; Molaei Dehkordi, A ; Sharif University of Technology
Elsevier B.V
2019
Abstract
This article presents a simulation study of tapered-in and tapered-out fluidized bed reactors to investigate the influences of apex angle on the fractional conversion and the pressure drop of the fluidized beds in the presence of two types of chemical reaction with gas volume increase and reduction. The 2D behavior of tapered-in and -out fluidized beds was also compared with a columnar one from fractional conversion and bed pressure drop point of views. To validate the simulation results, the numerical predictions for the expansion ratio and the pressure drop of a tapered fluidized bed were compared with experimental data and good agreement was observed. The obtained simulation results...
Two-dimensional CFD simulation of chemical reactions in tapered-in and tapered-out fluidized bed reactors
, Article Advanced Powder Technology ; Volume 30, Issue 1 , 2019 , Pages 136-147 ; 09218831 (ISSN) ; Molaei Dehkordi, A ; Sharif University of Technology
Elsevier B.V
2019
Abstract
This article presents a simulation study of tapered-in and tapered-out fluidized bed reactors to investigate the influences of apex angle on the fractional conversion and the pressure drop of the fluidized beds in the presence of two types of chemical reaction with gas volume increase and reduction. The 2D behavior of tapered-in and -out fluidized beds was also compared with a columnar one from fractional conversion and bed pressure drop point of views. To validate the simulation results, the numerical predictions for the expansion ratio and the pressure drop of a tapered fluidized bed were compared with experimental data and good agreement was observed. The obtained simulation results...
Modeling and Simulation Study of Tapered Fluidized-Bed Reactors with Gas Reduction
, M.Sc. Thesis Sharif University of Technology ; Molaei Dehkordi, Asghar (Supervisor)
Abstract
Existence of a velocity gradient in the axial direction in tapered fluidized beds causes unique dynamic characteristics of this kind of beds relative to cylindrical fluidized beds. Due to this characteristic, fluidized bed reactors with inclined walls have found a wide application in many industrial processes. In this study, tapered-¬in and tapered-¬out fluidized bed reactors have been simulated using Eulerian-¬Eulerian approach and applying the Kinetic Theory of Granular Flows (KTGF) for solid particles to investigate the bed behavior in the presence of two kinds of chemical reaction with gas volume reduction and gas volume increase. The results of hydrodynamic simulations show that the...
Magnetite nanoparticle as a support for stabilization of chondroitinase ABCI
, Article Artificial Cells, Nanomedicine and Biotechnology ; Volume 47, Issue 1 , 2019 , Pages 2721-2728 ; 21691401 (ISSN) ; Vossoughi, M ; Khajeh, K ; Alemzadeh, I ; Sharif University of Technology
Taylor and Francis Ltd
2019
Abstract
Chondroitinase ABCI (cABCI) is a drug enzyme that can be used to treat spinal cord injuries. Due to low thermal stability of cABCI, this enzyme was immobilized on Fe3O4 nanoparticle to increase its thermal stability. The size and morphology, structure and magnetic property of the Fe3O4 nanoparticles were characterized by the analyses of SEM, XRD and VSM, respectively, and FTIR spectroscopy was employed to confirm the immobilization of cABCI on the surface of Fe3O4 nanoparticles. The results indicated that the optimum conditions for pH, temperature, cABCI-to-Fe3O4 mass ratio and incubation time in immobilization process were 6.5, 15 °C, 0.75 and 4.5 h, respectively, and about 0.037 mg cABCI...
Examination of chondroitinase ABC I immobilization onto dextran-coated Fe3O4 nanoparticles and its in-vitro release
, Article Journal of Biotechnology ; Volume 309 , 2020 , Pages 131-141 ; Vossoughi, M ; Khajeh, K ; Alemzadeh, I ; Sharif University of Technology
Elsevier B.V
2020
Abstract
Chondroitinase ABC I (cABC I) has received notable attention in treatment of spinal cord injuries and its application as therapeutics has been limited due to low thermal stability at physiological temperature. In this study, cABC I enzyme was immobilized on the dextran-coated Fe3O4 nanoparticles through physical adsorption to improve the thermal stability. The nanoparticles were characterized using XRD, SEM, VSM, and FTIR analyses. Response surface methodology and central composite design were employed to assess factors affecting the activity of immobilized cABC I. Experimental results showed that pH 6.3, temperature 24 °C, enzyme/support mass ratio 1.27, and incubation time 5.7 h were the...
Experimental Study of Biological Synthesis, Stabilization and Delivery of the Recombinant Protein of Chondroitinase
, Ph.D. Dissertation Sharif University of Technology ; Vossoughi, Manouchehr (Supervisor) ; Alemzadeh, Iran (Supervisor) ; Khajeh, Khosro (Supervisor)
Abstract
In this research, immobilization method was employed to increase the thermal stability of Chondroitinase ABC I (cABC I) enzyme. In first step, magnetite nanoparticle (Fe3O4) was selected as a support and cABC I enzyme was attached via the adsorption method. The results showed that pH=6.5, temperature 15 ˚C, enzyme-to-support mass ratio 0.75, and incubation time 4.5 hr were the appropriate conditions for immobilizing cABC I enzyme on Fe3O4 nanoparticle. It was also found that the optimum pH for free and immobilized enzymes was 7.6 and 8.0, respectively. The maximum activity of free enzyme was obtained at 25 ˚C, whereas the activity of immobilized enzyme was almost constant in the temperature...
Calculation of the Energy Release Rate of Nano-Cracks in FCC Materials Via the Many Body Atomic Scale FEM
, M.Sc. Thesis Sharif University of Technology ; Mohammadi Shodja, Hossein (Supervisor)
Abstract
Since the classical continuum theory fails to deal with the problems associated with defects, stress concentrators, and relevant deformation phenomena in solids, alternative approaches that can detect the atomistic nature of materials' fracture are required. The deficiency of the capture the size effect which yields delusively high values for some components of the stress field right on the edge of the stress concentrators, and its weakness in describing the complex interaction between small inhomogeneities, cracks and the like when they are only a few nanometers apart, are among some of the disadvantages of the classical approach. In recent years, however, atomistic methods are emerging to...
Semisolid Stir Joining of As-Cast Silicon-Aluminum Bronze
, M.Sc. Thesis Sharif University of Technology ; Kokabi, Amir Hossein (Supervisor) ; Ashuri, Hossein (Supervisor)
Abstract
Aluminum Bronzes have many applications in marine environments. These alloys suffer from both hot cracking and cold cracking. In order to overcome the hot cracking and cold cracking, Semisolid Stir Joining method and a proper thermal cycle was used respectively. Effects of temperature, stirring rate, and tool type were investigated in Semisolid Stir joining method. In this method, butt joint design was used in order to place specimens, and the specimens were heated up to specific temperatures (920, 925, 930°C). A stirrer (Cylindrical and Grooved tool) with three rotational speeds (800, 1200, 1600 RPM) was introduced into the stir weld seam. Welded specimens were cooled to the 900°C...
The Study of Eliminating Gender Gap in Iran Labor Market on Participation Rate of Married Urban Women
, M.Sc. Thesis Sharif University of Technology ; Rahmati, Mohammad Hossein (Supervisor) ; Joshaghani, Hossein (Supervisor)
Abstract
The low female labor force participation rate in the Iranian labor market relative to the global average and even to countries that do not differ significantly from the socio-economic characteristics of our country is one of the important questions of the Iranian labor market. In this study, we seek to answer the question of whether the economic participation rate of married women will increase if the gender gaps in wages, job findings and job losses among women and men are eliminated in the Iranian labor market. To answer this question using household expenditure and income data and labor force data, we show that between the two categories of occupations, in terms of the share of women's...