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nikonam-mofrad--raheleh
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Effect of Cu2+ ion on biological performance of nanostructured uorapatite doped with copper
, Article Scientia Iranica ; Volume 24, Issue 6 , 2017 , Pages 2845-2855 ; 10263098 (ISSN) ; Sadrnezhaad, S. K ; Vahdati Khaki, J ; Sharif University of Technology
2017
Abstract
Nanostructured copper-doped uorapatite (Cux.Ca(10X).(PO4)6.F2) having crystallite sizes of 19, 29, and 34 nm at x = 0:9, 0.4, and 0.0, respectively, was synthesized by planetary ball milling of CaO, P2O5, CaF2, and CuO powders. Specifications of the products were determined by Fourier-transform infrared spectroscopy, eld emission scanning electron microscopy, transmission electron microscopy, and X-ray di raction analyses. In-vitro studies and Mossman's Tetrazole Test (MTT) assays were also conducted by incubating Cux.Ca(10X).(PO6).F2 powder into Kokubo's Simulated Body Fluid (SBF) and against BT-20 cell, respectively, to determine bioactivity and biocompatibility of the materials....
Mechanism of nanostructured fluorapatite formation from CaO, CaF2 and P2O5 precursors by mechanochemical synthesis
, Article Progress in Reaction Kinetics and Mechanism ; Volume 43, Issue 3-4 , 2018 , Pages 201-210 ; 14686783 (ISSN) ; Sadrnezhaad, S. K ; Vahdati Khaki, J ; Sharif University of Technology
Science Reviews 2000 Ltd
2018
Abstract
We determined the mechanism of mechanochemical synthesis of fluorapatite from CaO, CaF2 and P2O5 by characterisation of the intermediate compounds. We used atomic absorption spectroscopy, X-ray diffraction, field emission scanning electron microscopy, FTIR spectroscopy and transmission electron microscopy to find the transitional compounds. Investigation of the binary and ternary powder mixtures revealed the appearance of H3PO4, Ca(OH)2, Ca2P2O7 and CaCO3 as the intermediate compounds. At early stages of the milling, conversions of P2O5 to H3PO4 and CaO to Ca(OH)2 occurred in the wet atmosphere. Later, a combination of Ca(OH)2 and H3PO4 formed Ca2P2O7 while the unreacted CaO was converted to...
Mechanochemical Synthesis of Copper Doped Nanostructured Fluorapatite
, M.Sc. Thesis Sharif University of Technology ; Sadrnezhad, Khatiboleslam (Supervisor) ; Vahdati Khaki, Jalil (Co-Advisor)
Abstract
Fluorapatite (FA) has been widely used on orthopedic and dentistry prosthesis due to its excellent bioactivity properties. Therefore, the aim of this work is to prepare and characterize copper doped nanostructured fluorapatite powder via mechanical alloying (MA) method using a high energy planetary ball mill.FA powder samples with the general chemical formula Cux.Ca(10-x).(PO4)6.F2 (where x is the ratio of substitution of Cu-2 by F−1) are successfully synthesized using the starting materials of calcium oxide (CaO), phosphorous pentoxide (P2O5), calcium fluoride (CaF2), and copper (II) oxide (CuO) powders under various milling times. In order to evaluate the antibacterial effect of copper,...
Aerodynamic Design Methodology for Changing Axial Compressor Capacity
, M.Sc. Thesis Sharif University of Technology ; Ghorbanian, Kaveh (Supervisor)
Abstract
Axial compressor design is a very complex and expensive process. In general, for design and development of a new axial compressor, manufacturing companies usually intend to employ an existing and successful axial compressor as an starting point and modify and upgrade it. In this regard, dimensional scaling is a common method for derivative axial compressors. The goal of dimensional scaling is to get a different capacitywhile minimizing the development time and cost. In this thesis, theNASA eight stage transonic axial flow compressor is chosen as the base model for dimensional scaling to lower and upper size of its original dimension. The scaled compressor is analyzed with a quasi 2-D code....
Fabrication of a Tactile Sensor Based on Triboelectric Nanogenerators
, Ph.D. Dissertation Sharif University of Technology ; Mohammadpour, Raheleh (Supervisor) ; Sasanpour, Pezhman (Supervisor)
Abstract
Humans need the five senses to understand and interact constructively with their surrounding environment; in the world of robots and intelligent systems, this is achieved using sensors. In the modern world, tactile sensors based on triboelectric effect play a prominent role in important application areas such as health monitoring, human-computer interaction, robotics, pressure mapping, and electronic signature. Triboelectric nanogenerators (TENGs) are one type of energy harvesting systems that convert mechanical energy into electrical energy. In these sensors, due to the contact and touch with the triboelectric material, an electric charge is generated and induced into the electrode, then...
Simulation of the effects of oxygen carriers and scaffold geometry on oxygen distribution and cell growth in a channeled scaffold for engineering myocardium
, Article Mathematical Biosciences ; Volume 294 , 2017 , Pages 160-171 ; 00255564 (ISSN) ; Mashayekhan, S ; Bastani, D ; Sharif University of Technology
2017
Abstract
This study proposes a mathematical model to evaluate the impact of oxygen carriers and scaffold geometry on oxygen distribution and cell growth in a 3D cardiac construct using computational fluid dynamics (CFD). Flow equations, oxygen balance equation and cell balance equation were solved using special initial and boundary conditions. The modeling results revealed that 55% increase in cardiac cell density occurred by using 6.4% perfluorocarbon oxygen carrier (PFC) compared to pure culture medium without PFC supplementation. Moreover, the effects of the scaffold geometry on cell density were examined by changing the channel numbers and the construct length. A 30% increase in the average cells...
Design of Injectable Hydrogel Scaffold based on Smart Polymer in Tissue Engineering
, M.Sc. Thesis Sharif University of Technology ; Shamloo, Amir (Supervisor)
Abstract
Nerve damage is one of the factors affecting the quality of life of patients. The nervous system does not have the ability to repair large injuries, and autologous transplantation, which is the standard treatment method for nerve injuries, is faced with a shortage of donors and a decrease in the function of the donor site. Tissue engineering hydrogels, due to their similarity to the natural tissue of the stomatal body, are a hope for the repair of nerve tissue. In this research, an injectable, minimally invasive and temperature-sensitive hydrogel based on chitosan-etaglycerophosphate-sodium hydrogen carbonate salt or trisodium phosphate salt containing aligned nanofibers made of gelatin and...
Fabrication of Nanostructure Cuprous Oxide Films for Photovoltaic Systems
, Ph.D. Dissertation Sharif University of Technology ; Iraji Zad, Azam (Supervisor) ; Mohammadpour, Raheleh (Supervisor)
Abstract
Metal oxide semiconductors are promising materials for photovoltaic systems, because they are chemically stable, almost non-toxic and abundant. These materials are cheap and have low cost fabrication process. Cu2O is the most popular metal oxide semiconductor to absorb light in Photovoltaic (PV) applications, and photocathode in the photoelectrochemical systems.In this project, thermal oxide and electrodeposition methods, both interesting and cheap, were applied for preparing Cu2O films. As inexpensive materials results in low-minority carrier diffusion length, we report on surface engineering of bulk Cu2O photocathode thorough employing nanorods of copper oxide with the average lengths of...
Synthesis and Characterization of 2D-WS2 Nanostructures for Gas Sensing Applications
, Ph.D. Dissertation Sharif University of Technology ; Iraji Zad, Azam (Supervisor) ; Mohammadpour, Raheleh (Supervisor)
Abstract
Nowadays, beside of two-dimensional tungsten disulfide nanosheets, its hybrid nanostructures also provide active sites for physisorption of gas molecules due to their high surface-to-volume ratio, surface active site (such as sulfur vacancies, surface defects, and p-n junctions) and active edges, and are very attractive for gas sensing applications. In this research, tungsten disulfide layered crystallines were grown by chemical vapor phase transport and its two-dimensional nanoflakes were prepared by liquid exfoliation method. So, a thin film of the nanoflakes was deposited on a silicon oxide substrate by drop casting method, and its gas sensing properties were investigated for water and...
Directional migration and differentiation of neural stem cells within three-dimensional microenvironments
, Article Integrative Biology (United Kingdom) ; Volume 7, Issue 3 , Jan , 2015 , Pages 335-344 ; 17579694 (ISSN) ; Heibatollahi, M ; Mofrad, M. R. K ; Sharif University of Technology
Royal Society of Chemistry
2015
Abstract
Harnessing neural stem cells to repair neuronal damage is a promising potential treatment for neuronal diseases. To enable future therapeutic efficacy, the survival, proliferation, migration and differentiation of neural stem/progenitor cells (NPCs) should be accurately studied and optimized in in vitro platforms before transplanting these cells into the body for treatment purposes. Such studies can determine the appropriate quantities of the biochemical and biomechanical factors needed to control and optimize NPC behavior in vivo. In this study, NPCs were cultured within a microfluidic device while being encapsulated within the collagen matrix. The migration and differentiation of NPCs were...
A Ring Selection Platform for Treatment of Keratoconus
, M.Sc. Thesis Sharif University of Technology ; Asghari, Mohsen (Supervisor)
Abstract
Corneal keratoconus is one of the common eye diseases that usually occurs in the teenage years or the beginning of the third decade of life. In this disease, the cornea thins and loses its original shape and becomes conical. To treat this disease, ophthalmologists use different methods such as using glasses, contact lenses (hard and soft), corneal transplantation, and also corneal cross-linking, each of these methods has limitations, on the other hand, considering that The disease progresses and its severity increases, Ophthalmologists use corneal rings to treat this disease in more advanced stages, implanting a suitable ring in the patient's cornea both increases the strength of the...
Fabrication of gas ionization sensor based on titanium oxide nanotube arrays
, Article Applied Physics A ; Volume 115, Issue 4 , June , 2014 , pp 1387-1393 ; 1432-0630 ; Mohammadpour, R. (Raheleh) ; Iraji Zad, A. (Azam) ; Sharif University of Technology
2014
Abstract
Gas sensors have been fabricated based on field ionization from titanium oxide nanotubes grown on titanium foil. Ordered nanaotube arrays of titanium oxides were grown by the anodization method. We measured breakdown voltages and discharge currents of the device for various gases. Our gas ionization sensors (GIS) presented good sensitivity, selectivity, and short response time. The GISs based on TiO2 nanotube arrays showed lower breakdown voltage, higher discharge current, and good selectivity. An excellent response observed for Ar compared to other gases. Besides, by introducing 2 % CO and 4 % H2 to N2 flow gas, the amount of breakdown voltage shifts about 20 and 70 volts to the lower...
Fabrication and Characterization of Electron Transport and Buffer Layer Thin Films, Employing Sputtering Method, for All-Oxide Solar Cells
, M.Sc. Thesis Sharif University of Technology ; Iraji zad, Azam (Supervisor) ; Mohammadpour, Raheleh (Co-Advisor)
Abstract
In this study, transparent conductive thin film of Aluminum doped ZnO (ZnO:Al) have been fabricated thorough RF sputtering. The main goal of fabrication of these layers is achieving thin films with minimum resistivity and maximum optical transparency in visible range of spectrum employing as transparent electrodes and buffer layer at the entirely oxidized solar cells. To achieve the suitable structure, various parameters including pressure, power and the thickness of the deposition and annealing on morphologies of thin film has been investigated. According to these results, thin film of ZnO:Al has the transparency of 80% in the visible light range . Doping of ZnO with Aluminum caused...
Investigation of the Ion Migration Mechanism and its Effect on the Slow Response of Perovskite Solar Cells
, Ph.D. Dissertation Sharif University of Technology ; Taghavinia, Nima (Supervisor) ; Mohammadpour, Raheleh (Supervisor)
Abstract
In recent years, organo-metal perovskite solar cells have attracted remarkable attention due to their low cost manufacturing method as well as the rapid growth of efficiency. Despite the fast growing efficiency of organo-metal perovskite solar cells, there are big challenges around their low stability under real operational condition. In addition to extrinsic parameters like oxygen and humidity, intrinsic instability of perovskite rises mainly from ion migration in perovskite film. In order to understand the ion migration and its effect on photovoltaic parameters of the devices, appropriate characterizations and analysis are needed. Since ions are much slower compare to electrons, their...
Robust Optimization of Portfolio with Stock Options
, M.Sc. Thesis Sharif University of Technology ; Modarres Yazdi, Mohammad (Supervisor)
Abstract
In this thesis, we apply robust optimization to analyze the uncertainty of model parameters of a portfolio optimization which contains stock options. We also develop two robust counterpart models for single period and multiperiod problems. By assuming that the probability distribution of parameters is not known, their uncertainty is considered to lie within known linear intervals. Due to the existence of nonlinear relations (piecewise linear) between uncertain data (stock and option price), we present an over-conservative robust model to make the solution feasible for all parameters. However in the second model by adopting a different approach we develop a robust counterpart model with...
Comparison of logarithmic, elliptic, and conical helical spiral for isolation of circulating tumor cells based on inertial method
, Article Physics of Fluids ; Volume 34, Issue 9 , 2022 ; 10706631 (ISSN) ; Mozhdehbakhsh Mofrad, Y ; Safari, M ; Naseri, T ; Sharif University of Technology
American Institute of Physics Inc
2022
Abstract
Cancer is one of the most significant causes of death in the world. It has been shown that the role of circulating tumor cells (CTCs) in the early detection of cancer is crucial. Since the number of these cancerous cells in blood is very rare, the inertial microfluidic devices are one of the best candidates for the isolation of CTCs because they result in a high throughput process. Consequently, they can process a large volume of blood in a short time. Despite extensive computational and experimental studies on inertial microfluidic platforms, the impact of the curvature has not been thoroughly investigated during separation. In this paper, the feasibility of isolation of CTCs for...
Modeling for Sensing Behavior of SnO2-CuO Nanostructures toward H2S Gas
, Ph.D. Dissertation Sharif University of Technology ; Ghorbani, Mohammad (Supervisor) ; Moosavi, Ali (Supervisor) ; Mohammadpour, Raheleh (Supervisor)
Abstract
H2S is a toxic and corrosive gas which is detrimental for both human’s health and some of important industries such as oil and gas. Based on different experimental research among various systems, resistive sensors fabricated from SnO2-CuO nanostructures have promising performance toward detection of this gas. High sensitivity and selectivity, response time of order of seconds, recovery times of order of tens of seconds and determining concentration of H2S gas below ppm level are advantages of this system. Unfortunately due to lack of a theoretical model, current experimental researches are excessively based on “trial and error” methodology. In this research some of the basic questions which...
Development of Modified Nanostructures for Fabrication of Polymer Nanocomposite Films for Controlled Atmosphere Food Packaging
, Ph.D. Dissertation Sharif University of Technology ; Bagheri, Reza (Supervisor) ; Pircherghi, Gholamreza (Supervisor) ; Mohammadpour, Raheleh (Co-Supervisor)
Abstract
Active packaging is a novel approach that can ensure food safety by removing undesirable compounds such as Oxygen, ethylene, moisture, and microbial contamination from fresh produce's environment and reducing product loss by extending shelf life. Current research on active food packaging materials focuses on using biopolymers such as carbohydrates, proteins, and lipids as alternatives to non-degradable petroleum-based packaging materials. Active nanomaterials are commonly used to impart functionality to packaging materials. However, the lack of functionality limits their industrial application.Therefore, the main objective of this work was to fabricate bioactive nanocomposite films by...
Cooperation within von Willebrand factors enhances adsorption mechanism
, Article Journal of the Royal Society Interface ; Volume 12, Issue 109 , 2015 ; 17425689 (ISSN) ; Mehrbod, M ; Ejtehadi, M. R ; Mofrad, M. R ; Sharif University of Technology
Royal Society of London
2015
Abstract
von Willebrand factor (VWF) is a naturally collapsed protein that participates in primary haemostasis and coagulation events. The clotting process is triggered by the adsorption and conformational changes of the plasma VWFs localized to the collagen fibres found near the site of injury. We develop coarse-grained models to simulate the adsorption dynamics of VWF flowing near the adhesive collagen fibres at different shear rates and investigate the effect of factors such as interaction and cooperativity of VWFs on the success of adsorption events. The adsorption probability of a flowing VWF confined to the receptor field is enhanced when it encounters an adhered VWF in proximity to the...
Determination of Optimum Temperature Profile in Fermentation of B.Subtilis to Maximize Alpha-Amylase Activity
, M.Sc. Thesis Sharif University of Technology ; Vosoughi, Manouchehr (Supervisor) ; Roostaazad, Reza (Supervisor)
Abstract
Alpha amylase enzyme is one of the most important enzymes used in a wide range of industries. The enzyme is used in industries such as detergents, food, pharmaceuticals, paper making and textile. Various national and international articles have been published on this enzyme that focused on specific targets. Despite the extensive studies carried out in this area inside the country, there is still no industrial production of alpha amylase and other enzymes in our country. In the view of the fundamental problem of the lack of industrialization of these studies, in addition to the lack of a riskier investor, it seems that there is a lack of industrial vision in these studies.In this study, the...