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Increasing Critical Heat Flux and Boiling Heat Transfer on Superhydrophilic Nano Porous Surface Using Low Conductive Spots
, M.Sc. Thesis Sharif University of Technology ; Mousavi, Ali (Supervisor)
Abstract
This dissertation argues that bi-conductive textured surfaces increase both Critical Heat Flux (CHF) and Heat Transfer Coefficient (HTC) simultaneously. Surface modification is applied to stainless steel specimens by the anodizing method in an electrolyte containing Ammonium Fluoride and DI-Water and Ethylene Glycol as the based solvent. The process of oxidation was under constant DC voltage and constant temperature. The contact angle on self-aligned Nano-porous oxide layer fabricated on the substrate substantially decreases to about 5.7 degree which has a dramatic effect on CHF. Furthermore, the oxide layer augments the boiling efficiency by increasing the number of active sites and...
Simulation analysis of inverted organic solar cells with grating structure: undesirable effects of high absorption near grating anode
, Article Optik ; Volume 154 , February , 2018 , Pages 453-458 ; 00304026 (ISSN) ; Faez, R ; Sharif University of Technology
Elsevier GmbH
2018
Abstract
An inverted organic solar cell (IOSC) with nanograting array as anode of the cell has been simulated and analyzed using a combined electrical and optical approach. We have used finite difference time domain (FDTD) method for optimizing device structure. We have compared the characteristics of the IOSC with grating structure with a reference IOSC without grating structure. As a result, an improvement of 11% and 26% in power conversion efficiency (PCE) and short circuit current (JSC) compared to the reference structure was achieved. An analysis is provided on the origin of reduced fill factor (FF) in the IOSC with grating structure. We also have discussed about disadvantage of using optical...
Electrochemical degradation of clindamycin by anodic oxidation on SnO2-Sb coated titanium anodes
, Article Environmental Engineering and Management Journal ; Volume 17, Issue 2 , February , 2018 , Pages 343-355 ; 15829596 (ISSN) ; Davoudi, M ; Farzadkia, M ; Esrafili, A ; Dolati, A ; Sharif University of Technology
Gheorghe Asachi Technical University of Iasi, Romania
2018
Abstract
Degradation of Clindamycin phosphate (CMP) was studied in aqueous solutions by an anodic oxidation process under galvanostatic conditions. The electrolysis cell consisted of a Ti/SnO2-Sb anode, prepared by dip-coating technique, and a 316 stainless steel cathode, both of which had a surface area of 6 cm2. The effects of critical factors, including CMP concentration, current density, initial pH, and the supporting electrolyte were evaluated. The electrochemical oxidation of CMP was controlled by mass transport within the studied range. The kinetic analysis indicated that the degradation reactions followed pseudo-first-order equation. The rate of CMP decay, as well as that of COD removal,...
The Impedimetric Human Papiloma Virous DNA Biosensor Fabrication Based on Gold Nanotubes
, Ph.D. Dissertation Sharif University of Technology ; Ghorbani, Mohammad (Supervisor) ; Sasanpour, Pezhman (Supervisor)
Abstract
An impedimetric human papilloma virus (HPV) DNA biosensor based on gold nanotubes (AuNTs) in label free detection was materialized. The AuNTs decorated nanoporous polycarbonate (AuNTs-PC) template as biosensor electrode was fabricated by electrodeposition method. The single strand DNA (ss-DNA) probe was covalently immobilized onto the AuNTs-PC electrode. The hybridization of target sequences with the ss-DNA probe was observed by the electrochemical impedance spectroscopy (EIS). The biosensor showed high selectivity and could differentiate between the complementary, mismatch and non-complementary DNA sequences. The EIS measurements were matched to Randle's equivalent circuit. The...
Application of carbon-paste electrode modified with iron phthalocyanine for voltammetric determination of epinephrine in the presence of ascorbic acid and uric acid
, Article Sensors and Actuators, B: Chemical ; Volume 137, Issue 2 , 2009 , Pages 669-675 ; 09254005 (ISSN) ; Ghalkhani, M ; Amini, M. K ; Sharif University of Technology
2009
Abstract
A carbon-paste electrode (CPE) modified with iron(II) phthalocyanine was used for the sensitive voltammetric determination of epinephrine (EN). The electrochemical response characteristics of the modified electrode toward EN, ascorbic acid (AA) and uric acid (UA) were investigated by cyclic and differential pulse voltammetry (CV and DPV). The results show an efficient catalytic activity of the electrode for the electro-oxidation of EN, which leads to improvement of reversibility of the electrode response and lowering its overpotential by more than 100 mV. The effect of pH and potential sweep rate on the mechanism of the electrode process was investigated. The modified electrode exhibits an...
Lithium Extraction with TiO2 Nanotube Synthesized by Anodizing Method
, M.Sc. Thesis Sharif University of Technology ; Askari, Masoud (Supervisor)
Abstract
Due to the technology advancement and the large-scale application of lithium-ion batteries in recent years, the market demand for lithium is growing rapidly and the availability of land lithium resources is decreasing significantly. As such, the focus of lithium extraction technologies has shifted to water lithium resources involving salt-lake brines and sea water. The ion exchange process is a promising method for lithium extraction from brine and seawater having low concentrations of this element. Among various aqueous recovery technologies, the lithium ion-sieve (LIS) technology is considered the most promising one. This is because LISs are excellent adsorbents with high lithium uptake...
Kineticts of formation of Titania Nanotubes and Silk Fibroin on Titanium-based Metal for Investigating the Drug Release Behavior
, M.Sc. Thesis Sharif University of Technology ; Sadrnezhad, Khatiboleslam (Supervisor)
Abstract
In recent decades, due to the significant growth of implants’ application and considering the infection of the implants as the most momentous factor in implantation failure, study on the controlled drug release and other biologically active agents in modern drug delivery systems has attracted many kinds of research throughout the world and efforts are being made to use regulated drug delivery systems for implantation which is also the purpose of this current scientific work.To achieve this, the anodizing process was used to fabricate titanium oxide nanotubes (TNTs) to increase the absorption capacity of the drug in the implants and these TNTs were formed regularly and uniformly in an organic...
Preparation and Characterization of Ternary Mixed Oxide Containing IrO2,RuO2,TiO2 on Platinum Coated Titanium Anode
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor) ; Davami, Parviz (Supervisor)
Abstract
Ruthenium based-oxide coatings on Titanium anodes are widely used as DSA (Dimensionally Stable Anode) for chlorine and chlorate production. Coatings consisting of composition of highly conductive oxide of noble metals (Ru, Ir and Pt) make them as long lasting anodes in chlor-alkali technology.In this work, a newly anode by a ternary coating of IrO2, RuO2, and TiO2 on the Pt-coated Ti was developed through thermal decomposition of iridium and titanium and ruthenium inorganic salts dissolved in n-pentane. The effect of deposition parameters such as current density, time, different condition of baking, heating, mole ratio and pulling up the samples was investigated to find out reasonable...
Optimization of Nanostructures for Electron Emission
, Ph.D. Dissertation Sharif University of Technology ; Rashidian, Bizhan (Supervisor)
Abstract
The need for better characterization systems (electron microscopes) and high resolution lithography systems, have made electron beams systems an interesting choice for research and development. In fact, all of the above applications require ideal electron beams (beams with minimum energy spread, maximum current density, and minimum spotsize), and electron-optic lenses (simple lenses with minimum aberration). In this research, theoretical aspects of electron emission and lens systems are reviewed. Field emission array (FEA) electron guns are introduced as electron sources with minimum energy spread, and a new simulation method is presented in order to minimize the complexity, and reduce the...
Experimental Study of Hydrogen Production from Dairy Wastewater in the Annular Microbial Electrolysis Cell (AMEC)with Spiral Anode
, M.Sc. Thesis Sharif University of Technology ; Yaghmaei, Soheila (Supervisor)
Abstract
In this project, energy in form of electricity and hydrogen was produced in microbial fuel cell and microbial electrolysis cell respectively. For reducing costs, a stainless steel mesh with graphite coating was used as anode electode. Also for increasing efficiency, anode was positioned in cells in a spiral mode. Efficiency of cells was investigated in batch and continuous mode. In this research, dairy wastewater was used as substrate.This wastewater not only has severe emissions, but also is high energy content. In the field of dairy wastewater treatment and hydrogen production in an microbial electrolysis cell wasn’t observed any article.At the first, wastewater was treated in two...
Investigation of Si3n4 Nano Particle Addition on the Hardening Behavior of Anodized Coated 1050 Aluminum Alloy
, M.Sc. Thesis Sharif University of Technology ; Afshar, Abdollah (Supervisor)
Abstract
In the present study, it has been tried out to increase the hardness and wear resistance of anodized aluminum coating byadding Si3N4 nanoparticles to the anodizing bath and making a composite coating. In order to investigate the influence of other effective parameters on the properties of anodized coating before the compositing process, hardness and thickness were optimized in the Sulphoric/oxalic bath using design of experimental method (central composite design). The properties of these coatings are dependent on various parameters among which time, temperature and pulse current parameters (current density limit, frequency and duty cycle) were considered in the present study. Analysis of...
Electrochemical determination of l-dopa in the presence of ascorbic acid on the surface of the glassy carbon electrode modified by a bilayer of multi-walled carbon nanotube and poly-pyrrole doped with tiron
, Article Journal of Electroanalytical Chemistry ; Volume 636, Issue 1-2 , 2009 , Pages 40-46 ; 15726657 (ISSN) ; Asadian, E ; Sharif University of Technology
Elsevier
2009
Abstract
There are high attractions in the development of conducting polymer (CP) coatings to improve the electrochemical properties and biocompatibility of electrodes in the area of biosensors. A new type of the modified electrodes is prepared in a layer-by-layer process by using multi-walled carbon nanotube (MWCNT) and poly-pyrrole. In this procedure, the glassy carbon electrode is casted by a drop suspension of MWCNT, which leads to form a thin film of nanotube on its surface. In the second step, electrochemical polymerization of pyrrole in the presence of tiron (used as doping anion) is performed on the surface of the MWCNT pre-coated electrode. The modification procedure led to fabrication of a...
Influence of Cobalt and Vanadium Dopants on the Performance of TiO2(B) Nanowires used as anode Materials in Lithium-ion Batteries
, M.Sc. Thesis Sharif University of Technology ; Askari, Masoud (Supervisor)
Abstract
Li-ion batteries have been widely applied as power sources for portable electronic devices. Recently, Li-ion batteries are considered as the most promising energy storage technology for electric vehicle applications however, fundamental improvements are needed. TiO2 (B) is attractive candidate for anodes in rechargeable Li-ion batteries, due to their low cost, non-toxicity and favorable channel structure for fast lithium mobility. It is predicted that synthesis of doped nanostructure of this material, through reducing the diffusion pathway and formation of crystal defects, will increase the capacity of TiO2(B). In this investigation, Co and V doped TiO2(B) nanowires are synthesized by...
Fabrication of Vertically Oriented TiO2 Nanotube Arrays Using Organic Electrolytes
, M.Sc. Thesis Sharif University of Technology ; Askari, Masoud (Supervisor) ; Hakim, Manochehr (Supervisor)
Abstract
Titanium dioxide, due to its specific semiconductive properties, has been a highly investigated material for a variety of applications including gas sensors, hydrogen generation by water photoelectrolysis, photocatalysis, dye-sensitized solar cells and purification of water and air. Several recent studies have indicated that titania nanotubes have improved properties compared to any other form of titania for mentioned application. Titania nanotubes have been produced by a variety of methods including deposition into a template and hydrothermal processes. Anodic oxidation of titanium foil in a fluoride-based solution is one of the best methods to produce of titania nanotube arrays. Highly...
Electrocatalytic oxidation of glucose on Ni and NiCu alloy modified glassy carbon electrode
, Article Journal of Solid State Electrochemistry ; Volume 13, Issue 8 , 2009 , Pages 1171-1179 ; 14328488 (ISSN) ; Forouzandeh, F ; Danaee, I ; Gobal, F ; Mahjani, M. G ; Sharif University of Technology
2009
Abstract
Nickel and nickel-copper alloy modified glassy carbon electrodes (GC/Ni and GC/NiCu) prepared by galvanostatic deposition were examined for their redox processes and electro-catalytic activities towards the oxidation of glucose in alkaline solutions. The methods of cyclic voltammetry (CV) and chronoamperometry (CA) were employed. The cyclic voltammogram of NiCu alloy demonstrates the formation of β/β crystallographic forms of the nickel oxyhydroxide under prolonged repetitive potential cycling in alkaline solution. It is also observed that the overpotential for O 2 evolution increases for NiCu alloy modified electrode. In CV studies, NiCu alloy modified electrode yields significantly higher...
A study on electrochemical growth behavior of the Co-Ni alloy nanowires in anodic aluminum oxide template
, Article Journal of Alloys and Compounds ; Volume 480, Issue 2 , 2009 , Pages 275-278 ; 09258388 (ISSN) ; Dolati, A ; Sharif University of Technology
2009
Abstract
This study shows the growth behavior of Co-Ni alloy nanowires in AAO template. Growth of nanowires consists of four different stages namely electronucleation, steady state growth, filling of pores, and coverage of filled nanowires and forming of a film on the template surface. TEM study of nanowires showed that the nanowires possess hemispherical head due to the preferable and more rapid growth phenomenon in central section of nanowires instead of edge sides. Studies on the relations between nanowires composition and ion concentration in solution showed that growth of nanowires is a diffusion-controlled process. The compositional, structural and magnetic properties of nanowires were...
Comparison of various anodization and annealing conditions of titanium dioxide nanotubular film on MB degradation
, Article EPJ Applied Physics ; Volume 47, Issue 1 , 2009 ; 12860042 (ISSN) ; Iraji Zad, A ; Ahadian, M. M ; Taghavinia, N ; Dolati, A ; Sharif University of Technology
2009
Abstract
In this study the influence of morphology of vertically oriented titanium oxide nanotube arrays (TNTAs) on their photocatalytic activities was investigated. To obtain nanotubes with different morphologies, they were prepared at different anodization voltages. The size of TNTAs were measured using SEM images and also determined based on a non-destructive optical method; We demonstrate how the tubular geometry of the TNTAs can be used to adjust the optical and also the wetting properties of them and how these properties affect the performance of the nanostructure in further applications as a photocatalyst. To investigate their potentials for environmental applications, the photocatalytic...
Cathodic Protection of Concrete by Zinc Sacrificial Anode in Persian Gulf Sea Water
, M.Sc. Thesis Sharif University of Technology ; Dolati, Abolghasem (Supervisor)
Abstract
Many of the major structure over coastal waters in the Kish Island due to the aggressive condition are showing signs of reinforcement corrosion. Recent advances in the development of anodes make it practical to use zinc galvanic cathodic protection to protect this structure in this area. Five anode systems were tested on several samples as, (1) zinc metal spray applied by arc-spraying on the concrete, (2) a zinc foil with conductive adhesive backing, (3) a system of zinc mesh and grout jacket, (4) a system of zinc mesh and compression panels, and (5) a bulk zinc. These anodes are set up to comparison the effects of potential and current over the zinc galvanic cathodic protection during 4...
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...
Hydrogen bubble template fabricated nano-architecture quaternary dendritic sulfide as cathode and electro-etched carbon fiber paper as anode electrode for total novel binder-free asymmetric supercapacitors
, Article Journal of Alloys and Compounds ; Volume 811 , 2019 ; 09258388 (ISSN) ; Naderi, L ; Shahrokhian, S ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
A novel electrode consisting of 3D porous nickel‒cobalt‒copper sulfide dendritic structures is synthesized, in which, for the first time ternary Ni–Co–Cu foam is constructed through hydrogen bubble template and followed by sulfidization via a hydrothermal reaction in thiourea. The 3D, porous Ni–Co–Cu dendritic sulfide electrode exhibits a high specific capacitance of 1203.75 F g−1 (0.963 F cm−2) at current of 1.0 mA and excellent cycling stability, excellent ratability along with high cycle stability. An asymmetric supercapacitor (ASC) using dendritic sulfide structures and reduced electro-etched carbon fiber paper (RECF) as the positive and negative electrodes, respectively is developed....