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mazaheri-tehrani--zahra
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Mesoporous silica nanoparticles (MCM-41) coated PEGylated chitosan as a pH-Responsive nanocarrier for triggered release of erythromycin [electronic resource]
, Article International Journal of Polymeric Materials and Polymeric Biomaterials ; 2014, Volume 63, Issue 13, Pages 692-697 ; Mazaheri Tehrani, Zahra ; Sharif University of Technology
Abstract
A pH-responsive drug delivery system based on core shell structure of mesoporous silica nanoparticle (MSN) and chitosan-PEG copolymer was prepared and characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscope (SEM), and high-resolution transmission microscope (HR-TEM) techniques. In order to improve compatibility MSN and drug, mesoporous nanosilica was modified by 3-aminopropyl triethoxysilane. The release of erythromycin (a macrolide antibiotic) as a model drug was investigated in two pHs, 7.4 and 5.5
Design of Drug Nanocarriers Based on Mesoporous Silica Nanoparticles Coated with Smart Polymers
, Ph.D. Dissertation Sharif University of Technology ; Pourjavadi, Ali (Supervisor)
Abstract
Mesoporous silica nanoparticles have broad application in drud delivery systems due to their porous structure, functionalization, biocompatibility, high surface area and pore volume. Neverthless, pure mesoporous silica nanoparticles without functionality were not smart material and could not release drug in triggered and controlled manner. For this reason, using smart polymeric coating would be considered. Polymer shells also provide colloidal stability, improved blood circulation lifetime and reduced toxicity which are crucial for efficient in vivo drug delivery. Inflammatory and tumor tissue have low pH and high temperature as compared to health tissue. Therefore, using pH and...
Magnetic micellar nanocarrier based on pH-sensitive PEG-PCL-PEG triblock copolymer: a potential carrier for hydrophobic anticancer drugs
, Article Journal of Nanoparticle Research ; Volume 20, Issue 10 , 2018 ; 13880764 (ISSN) ; Dastanpour, L ; Mazaheri Tehrani, Z ; Sharif University of Technology
2018
Abstract
In this research, we report a magnetic pH-sensitive polymeric micelle designed for hydrophobic drug carrier in cancer treatment. This carrier was prepared by self-assembly of biodegradable triblock copolymer PEG-PCL-PEG coated on oleate-modified magnetic nanoparticles. The amphiphilic triblock copolymer was synthesized via reaction between the aldehyde group from the hydrophilic component with the amine group of the hydrophobic component. The resulting Schiff base linkage was sensitive to pH. The structure of nanocarrier was characterized by Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectroscopy (1H-NMR). Morphology and size of the magnetic...
Development of Optimization Algorithm for Low Speed UAVs Propellers
, M.Sc. Thesis Sharif University of Technology ; Mazaheri, Karim (Supervisor)
Abstract
Aerodynamic shape optimization has been always of great importance in aerospace design. Recent advancements in computational algorithms and hardware, has made it feasible to have advanced optimization as a standard part of desing procedure. Here we have promoted aerodynamic optimization of air propeller.
Propeller optimization process requires a propeller performance analysis program and an efficient optimization algorithm. A vortex lattice model is used for the propeller performance analysis and a computer program is developed based on it. Experiment and litritures are used for validation of VLM code. In order to optimize the propeller peformance, propeller efficiency is applied as cost...
Propeller optimization process requires a propeller performance analysis program and an efficient optimization algorithm. A vortex lattice model is used for the propeller performance analysis and a computer program is developed based on it. Experiment and litritures are used for validation of VLM code. In order to optimize the propeller peformance, propeller efficiency is applied as cost...
Implementation of Millimeter-wave Imaging Algorithm Based on Frequency Scanning Antenna
, M.Sc. Thesis Sharif University of Technology ; Shabani, Mahdi (Supervisor) ; Kavehvash, Zahra (Supervisor)
Abstract
Nowadays millimeter wave imaging technology has found various applications in industry, medical and security systems. From one side the capability of penetration of this frequency spectrum into non-metal objects, and being harmless to humankind on the other side, has made this spectrum an appropriate alternative instead of dangerous spectrums such as X-ray. Recently, development of millimeter wave electronic circuits and antenna arrays has made the optimal design and implementation of millimeter wave imaging systems feasible. Among actions which have been taken in industry, medical and security systems until now, we can refer to efforts for detection of defects in production line,...
Incorporating the Impacts of Energy Storage Systems on Transmission Expansion Planning Studies
, M.Sc. Thesis Sharif University of Technology ; Abbaspour Tehrani Fard, Ali (Supervisor) ; Fotuhi-Firuzabad, Mahmud (Co-Advisor)
Abstract
Transmission expansion planning is an important part of power system planning that it task is to determine the optimal structure of transmission network based on load growth and to consider the future plan of system generation for a specified time period. The development of generation plans based on renewable resources, cost and time-consuming transmission expansion plans have caused that transmission planning to become a fundamental challenge. Therefore, in recent year’s decision makers of power systems are following the alternative ways of transmission expansion planning with lower cost and economic appropriate justification. Using of energy storage systems have cause to a delay on...
Theoretical Investigation of Hydrogen Bonding Effects on Interaction of Metal Nanoclusters with Biomolecules & Acidity Enhancement of Alcohols
, Ph.D. Dissertation Sharif University of Technology ; Fattahi, Alireza (Supervisor) ; Mahmoodi Hashemi, Mohammad (Supervisor) ; Jamshidi, Zahra (Co-Advisor)
Abstract
This thesis is divided into three parts: In part I, conformational properties of neutral, anionic, cationic and zwitterionic forms of glutathione tripeptide were investigated by means of DFT-B3LYP method with 6-31+G (d,p) basis set. Results show that glutathione is a very flexible molecule and its conformational energy landscape is strongly influenced by forming intramolecular hydrogen bond and its charge. Conformation of each amino acid in glutathione tripeptide depends on its orientation within the peptide sequence in addition to the conformation of other amino acids within the chain. Investigation of intramolecular hydrogen bonds in these conformers by means of AIM analysis demonstrates...
Flexible bactericidal graphene oxide–chitosan layers for stem cell proliferation [electronic resource]
, Article Journal of Applied Surface Science ; 15 May 2014, Volume 301, Pages 456–462 ; Akhavan, O ; Simchi, A. (Abdolreza) ; Sharif University of Technology
Abstract
Graphene oxide (GO)–chitosan composite layers with stacked layer structures were synthesized using chemically exfoliated GO sheets (with lateral dimensions of ∼1 μm and thickness of ∼1 nm), and applied as antibacterial and flexible nanostructured templates for stem cell proliferation. By increasing the GO content from zero to 6 wt%, the strength and elastic modulus of the layers increased ∼80% and 45%, respectively. Similar to the chitosan layer, the GO–chitosan composite layers showed significant antibacterial activity (>77% inactivation after only 3 h) against Staphylococcus aureus bacteria. Surface density of the actin cytoskeleton fibers of human mesenchymal stem cells (hMSCs) cultured...
An MPC method based on a hybrid model of a three-phase inverter with output LC- filter
, Article 2012 3rd Power Electronics and Drive Systems Technology, PEDSTC 2012, 15 February 2012 through 16 February 2012 ; February , 2012 , Pages 170-174 ; 9781467301114 (ISBN) ; Mokhtari, H ; Sharif University of Technology
2012
Abstract
Controlling inverters with LC output filters in order to achieve a high quality desired output voltage or current is a challenging problem in power electronics. The LC filter and the binary nature of switch state variables increase the difficulty of achieving a single comprehensive model for the system. In this paper, a hybrid model is presented for a three-phase inverter with an LC output filter and a three-phase RL load. Then, the Model Predictive Control (MPC) algorithm is applied to the model and a geometrical approximate method is used to fit the answers to the binary values. Simulation results for a sample system verify the usability of the method and the quality of the answers
Experimental investigation on aerodynamic performance of a flapping wing vehicle in forward flight
, Article Journal of Fluids and Structures ; Volume 27, Issue 4 , 2011 , Pages 586-595 ; 08899746 (ISSN) ; Ebrahimi, A ; Sharif University of Technology
2011
Abstract
The aerodynamic performance of a flexible membrane flapping wing has been investigated here. For this purpose, a flapping-wing system and an experimental set-up were designed to measure the unsteady aerodynamic forces of the flapping wing motion. A one-component force balance was set up to record the temporal variations of aerodynamic forces. The flapping wing was studied in a large low-speed wind tunnel. The lift and thrust of this mechanism were measured for different flapping frequencies, angles of attack and for various wind tunnel velocities. Results indicate that the thrust increases with the flapping frequency. An increase in the wind tunnel speed and flow angle of attack leads to...
Electrical behavior of nano-polycrystalline (La1-yK y)0.7Ba0.3MnO3 manganites
, Article Journal of Magnetism and Magnetic Materials ; Volume 322, Issue 21 , November , 2010 , Pages 3255-3261 ; 03048853 (ISSN) ; Akhavan, M ; Sharif University of Technology
2010
Abstract
We present a study of the structural and electrical behavior of nano-polycrystalline mixed barium and alkali substituted lanthanum-based manganite, (La1-yKy)0.7Ba0.3MnO 3 with y=0.00.3. The samples were synthesized by the polymerization complex solgel method. The powder X-ray diffraction (XRD) data of the samples show a single-phase character with R3c space group. The magnetic and electrical transport properties of the nano-polycrystalline samples have been investigated in the temperature range 50300 K and a magnetic field up to 10 kOe. The metalinsulator transition temperature Tp of all the samples decreased with potassium doping, and also, it increased slightly with the application of...
Experimental study on interaction of aerodynamics with flexible wings of flapping vehicles in hovering and cruise flight
, Article Archive of Applied Mechanics ; Volume 80, Issue 11 , 2010 , Pages 1255-1269 ; 09391533 (ISSN) ; Ebrahimi, A ; Sharif University of Technology
2010
Abstract
Flapping wings are promising lift and thrust generators, especially for very low Reynolds numbers. To investigate aeroelastic effects of flexible wings (specifically, wing's twisting stiffness) on hovering and cruising aerodynamic performance, a flapping-wing system and an experimental setup were designed and built. This system measures the unsteady aerodynamic and inertial forces, power usage, and angular speed of the flapping wing motion for different flapping frequencies and for various wings with different chordwise flexibility. Aerodynamic performance of the vehicle for both no wind (hovering) and cruise condition was investigated. Results show how elastic deformations caused by...
Preparation and characterization of nano-polycrystalline lanthanum-based manganite (La1 - y Ky)0.7 Ca0.3 MnO3
, Article Physica B: Condensed Matter ; Volume 405, Issue 1 , 2010 , Pages 72-76 ; 09214526 (ISSN) ; Akhavan, M ; Sharif University of Technology
2010
Abstract
A series of nano-polycrystalline alkali metal doped in La-based manganites (La1 - y Ky)0.7 Ca0.3 MnO3 samples (y = 0.0, 0.1, 0.2, and 0.3) were synthesized using the polymerical complex sol-gel method. The structural properties are studied via the X-ray diffraction experiments, and results are refined by the Rietveld method. The electrical transport properties of the polycrystalline samples have been investigated in the temperature range 50-300 K and a magnetic field up to 10 kOe. The metal-insulator transition temperature (Tp) changes with doping due to the difference between the electron configuration and ionic radius of the dopants and manganese trivalent ions. Characteristic grain...
Experimental investigation of the effect of chordwise flexibility on the aerodynamics of flapping wings in hovering flight
, Article Journal of Fluids and Structures ; Volume 26, Issue 4 , May , 2010 , Pages 544-558 ; 08899746 (ISSN) ; Ebrahimi, A ; Sharif University of Technology
2010
Abstract
Ornithopters or mechanical birds produce aerodynamic lift and thrust through the flapping motion of their wings. Here, we use an experimental apparatus to investigate the effects of a wing's twisting stiffness on the generated thrust force and the power required at different flapping frequencies. A flapping wing system and an experimental set-up were designed to measure the unsteady aerodynamic and inertial forces, power usage and angular speed of the flapping wing motion. A data acquisition system was set-up to record important data with the appropriate sampling frequency. The aerodynamic performance of the vehicle under hovering (i.e., no wind) conditions was investigated. The lift and...
Numerical optimization of laboratory combustor geometry for NO suppression
, Article Applied Thermal Engineering ; Volume 102 , 2016 , Pages 1328-1336 ; 13594311 (ISSN) ; Shakeri, A ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
In this article, geometry optimization of a jet stirred reactor (JSR) combustor has been carried out for minimum NO emissions in methane oxidation using a combined numerical algorithm based on computational fluid dynamics (CFD) and differential evolution (DE) optimization. The optimization algorithm is also used to find a fairly accurate reduced mechanism. The combustion kinetics is based on a five-step mechanism with 17 unknowns which is obtained using an optimization DE algorithm for a PSR-PFR reactor based on GRI-3.0 full mechanism. The optimization design variables are the unknowns of the five-step mechanism and the cost function is the concentration difference of pollutants obtained...
The multi-point optimization of shock control bump with constant-lift constraint enhanced with suction and blowing for a supercritical airfoil
, Article Flow, Turbulence and Combustion ; Volume 96, Issue 3 , 2016 , Pages 639-666 ; 13866184 (ISSN) ; Nejati, A ; Sharif University of Technology
2016
Abstract
Both shock control bump (SCB) and suction and blowing are flow control methods used to control the shock wave/boundary layer interaction (SWBLI) in order to reduce the resulting wave drag in transonic flows. A SCB uses a small local surface deformation to reduce the shock-wave strength, while suction decreases the boundary-layer thickness and blowing delays the flow separation. Here a multi-point optimization method under a constant-lift-coefficient constraint is used to find the optimum design of SCB and suction and blowing. These flow control methods are used separately or together on a RAE-2822 supercritical airfoil for a wide range of off-design transonic Mach numbers. The RANS flow...
Numerical study of pollutant emissions in a Jet stirred reactor under elevated pressure Lean premixed conditions
, Article Mathematical Problems in Engineering ; Volume 2016 , 2016 ; 1024123X (ISSN) ; Shakeri, A ; Sharif University of Technology
Hindawi Publishing Corporation
2016
Abstract
Numerical study of pollutant emissions (NO and CO) in a Jet Stirred Reactor (JSR) combustor for methane oxidation under Elevated Pressure Lean Premixed (EPLP) conditions is presented. A Detailed Flow-field Simplified Chemistry (DFSC) method, a low computational cost method, is employed for predicting NO and CO concentrations. Reynolds Averaged Navier Stokes (RANS) equations with species transport equations are solved. Improved-coefficient five-step global mechanisms derived from a new evolutionary-based approach were taken as combustion kinetics. For modeling turbulent flow field, Reynolds Stress Model (RSM), and for turbulence chemistry interactions, finite rate-Eddy dissipation model are...
Optimization of bump and blowing to control the flow through a transonic compressor blade cascade
, Article Shock Waves ; 2017 , Pages 1-13 ; 09381287 (ISSN) ; Khatibirad, S ; Sharif University of Technology
Springer New York LLC
2017
Abstract
Shock control bump (SCB) and blowing are two flow control methods, used here to improve the aerodynamic performance of transonic compressors. Both methods are applied to a NASA rotor 67 blade section and are optimized to minimize the total pressure loss. A continuous adjoint algorithm is used for multi-point optimization of a SCB to improve the aerodynamic performance of the rotor blade section, for a range of operational conditions around its design point. A multi-point and two single-point optimizations are performed in the design and off-design conditions. It is shown that the single-point optimized shapes have the best performance for their respective operating conditions, but the...
Using a shock control bump to improve the performance of an axial compressor blade section
, Article Shock Waves ; Volume 27, Issue 2 , 2017 , Pages 299-312 ; 09381287 (ISSN) ; Khatibirad, S ; Sharif University of Technology
Springer New York LLC
2017
Abstract
Here, we use numerical analysis to study the effects of a shock control bump (SCB) on the performance of a transonic axial compressor blade section and to optimize its shape and location to improve the compressor performance. A section of the NASA rotor 67 blade is used for this study. Two Bézier curves, each consisting of seven control points, are used to model the suction and pressure surfaces of the blade section. The SCB is modeled with the Hicks–Henne function and, using five design parameters, is added to the suction side. The total pressure loss through a cascade of blade sections is selected as the cost function. A continuous adjoint optimization method is used along with a RANS...
Optimization of bump and blowing to control the flow through a transonic compressor blade cascade
, Article Shock Waves ; Volume 28, Issue 2 , 2018 , Pages 285-297 ; 09381287 (ISSN) ; Khatibirad, S ; Sharif University of Technology
Springer New York LLC
2018
Abstract
Shock control bump (SCB) and blowing are two flow control methods, used here to improve the aerodynamic performance of transonic compressors. Both methods are applied to a NASA rotor 67 blade section and are optimized to minimize the total pressure loss. A continuous adjoint algorithm is used for multi-point optimization of a SCB to improve the aerodynamic performance of the rotor blade section, for a range of operational conditions around its design point. A multi-point and two single-point optimizations are performed in the design and off-design conditions. It is shown that the single-point optimized shapes have the best performance for their respective operating conditions, but the...