Sharif Digital Repository

The Fuel cell is an energy converter which converts the chemical energy of a chemical reaction to electricity and heat directly and without any pollution. One of the most important types of fuel cells is the proton exchange membrane (PEM) fuel cell. The importance of PEM fuel cells is a result of their high energy density, quick start up ability, lower operating temperature, high efficiency and low or zero emissions. Catalysts play an important role in both costs and durability of PEM fuel cells. Alloying the Pt with other metals can increase the activity of the catalysts of the fuel cells and also reduces the amount of costly Pt. In this study, the nanoparticles of Ni were added to the... 

Using plasma cluster in fusion has attracted many attentions in recent year. In this work, generating of hard X-ray with energy more than 10 keVby Ti-sapphire laser, 100 fs pulses’ duration and focal intensity of more than 1014W/cm2 has been discussed. Due to significant enhancement of X-ray production from metal nanoplasma cluster, a reasonable theoretical model is needed to describe the more than 10-fold increment of X-ray generation. Hence, the present models have been studied and a proper model based on available experimental data, has been presented. The X-ray, which is produced through this way, can be used in Inertial Fusion Confinement (ICF). One of the major obstacles in ICF is... 

In the present study, smart anticorrosion coatings were successfully prepared based on epoxy ester (EPE) resin and conductive nano polyaniline particles (nES). Anticorrosion behaviors of these coatings were analyzed by electrochemical techniques. Generally, this thesis consists of two main parts: the theoretical studies (1st and 2nd Chaps.) and empirical investigations (3th to 8th Chaps.).The first Chap. expresses a basic introduction about the corrosion concepts and different types of anticorrosion coating. In the second Chap. main goals and stage works of the thesis about the smart anticorrosion coatings are introduced considering literature researches. The subject of the 3th Chap. is... 

In the present thesis the fabrication of various tungsten oxide nanostructures (films and colloidal nanoparticles) with coverage of catalyst on their surfaces has been investigated which show gasochromic properties. Tungsten oxide films and nanoparticles were synthesized by pulsed laser abalation technique in vacuum and liquid environment, respectively. To activate the synthesized films and nanoparticles against hydrogen gas, the catalyst nanoparticles (Pd or Pt) were deposited onto their surface through hydrogen reduction of metal salt and electroless methods, respectively. The products were characterized by XPS, UV-Vis., AFM and DLS techniques. The prepared samples show significant color... 

High purity titanium nanoparticles were synthesized by utilizing Electromagnetic Levitation Melting Gas Condensation (ELM-GC) method. High purity titanium samples were melted by electromagnetic levitation to a temperature of 1700 ± 20 °C in a silica tube. High purity argon and helium were employed as carrier gases and cooling agent. Particlesize, morphology, and Purity of the produced nanoparticles were studied by Field-Emission Scanning Electron Microscopy (FE-SEM), X-ray Diffraction (XRD), Dynamic Light Scattering (DLS), X-ray fluorescence (XRF), and ICP-AES analysis. The FE-SEM, DLS and XRF studies confirmed narrow size distribution of almost spherical shape pure titanium nanoparticles... 

In this thesis, proteinnanoparticle interactions have been studied using Molecular Dynamics simulation. sT fN, is the studied protein in this work. It is one of the most important proteins in the blood fluid. In this work, nanoparticle has been modeled as a surface; because the radius of gyration of sT fN is less than 3nm, so when it is near an enough big nanoparticle (100200 nm), nanoparticle seems as a surface from the view of protein. The surface of nanoparticle consists of sodium ions. Surface of nanoparticle, has been modeled using two types of surface:flat surface and nonflat surface. Protein interaction with surface, has been studied in two different initial orientations with respect... 

In this project, a novel system of bioactive electrospun scaffold for bladder tissue engineering , has been investigated to control in vitro cell differentiation, and utilize in in vivo vascularization and tissue formation. This method doesn’t have custom bioactive scaffolds problems such as, protein instability, technical complexity and, difficulties in accurate kinetics prediction. First of all, protein loaded chitosan nanoparticles based on ionic gelation interaction between chitosan and Sodium tripolyphosphate were prepared. Maximum protein loading efficiency (80% for BSA & 99% for TGF-beta1) in chitosan nanoparticles was obtained at mean diameter of 51nm. Moreover polycaprolactone... 

Non-uniform laminated beams are being used in many engineering applications as primary elements. Helicopter blades, wind turbine blades and robot arms are examples of applications of these structures, in which the high stiffness-to-weight ratio and the non-uniform geometry are of high importance. Changing the thickness in laminated structures is a big challenge in fabrication view as different tapering configurations may significantly alter the stiffness of the structure. Thus, increasing the stiffness and dynamics characteristics of tapered beams with simple configuration is of high importance. The present work aims to investigate the effect of adding nano particles in resin during the... 

Today, due to limited number of light oil reservoirs, enhanced recovery from heavy oil reservoirs is taken into consideration. During the early production from heavy oil reservoirs, due to high viscosity, only a small amount (about 5%) of the oil can be produced; also after water injection operation due to unfavorable mobility ratio of water and oil, sorely more than about 10% of the original oil can be produced. On the other hand, fractured reservoirs represent about 20% of the world's oil reserves, while over 60% of the world's remaining oil reserves are in fractured reservoirs. Water flooding process leaves very high amounts of oil as remaining oil in these reservoirs too. One of the... 

Due to ignoring the effect of length scale and neglecting the details at nanosize, classical methods are not sufficiently accurate to determine the properties of nanostructured materials. More reliable results can be obtained, using surface elasticity theory. Lots of analytical, experimental and numerical investigations have been done on the effect of interphase on the mechanical properties of polymer nanocomposites whereas metal matrix nanocomposites are in the first stages of analytical and numerical researches and have attracted so much attention.
The main objective of this research is to investigate the effects of interphase as well as coating, on the mechanical behavior of metal... 

Interest in lithium sources has been increasing because of wide applications of the metal in high-energystorage lithium batteries and its compounds in otherfields.Lithium appears in lake, brines and several minerals such as spodumene, petallite, and lepidolite. Several methods such as ion exchange (adsorption), solvent extraction, and coprecipitation have been investigated for the extraction of lithium from seawater, brine, and geothermal water. The adsorption method is suitable for recovery of lithium from seawater because certain inorganicion-exchange materials show extremely high selectivity for lithium ions only.The objective of this study is to evaluate the applicability of nano... 

In this study, nano-powders of copper-cobalt spinel (CuCo2O4) were fabricated by solution combustion synthesis (SCS) of Cu and Co nitrates with urea, glycine,acid citric and alanine. The method involved exothermic decomposition of viscous liquid nitrates and the fuel. Products which were synthesized by using this fuels contained less impurity constituents. Duo to low purity, other factors which have influence on synthesis process investigated and observed that pH have key role on process. X-ray diffraction (XRD) patterns gave crystal structure and the existing phases. Particle size distribution and morphology changes were studied by dynamic light scattering (DLS) and field emission scanning... 

The present study was aimed at investigating the use of platinum and platinum nanoparticles stabilized on zeolite as catalyst for the reduction reaction of p-nitrotoluene as one of the dangerous pollutants. The adsorption properties of platinum based on zeolite have been studied for some heavy metals. Monodispersed platinum nanoparticles were synthesized through reduction of H2PtCl6 by ethanol in the presence of polyvinyl pyrrolidone (PVP) as a stabilizer, and then were immobilized on four types of zeolites. The study then focused on elaboration of the catalytic activity of the nano catalysts under different operational conditions. In order to investigate the catalytic properties, operating... 

In this research, we focused on demonstration of features and advantages of supercritical fluids technology to formation of fine particles (nano and micro scales) from bulk materials (solid) and synthesized metal oxides nanoparticles. Therefore, using two different fluids, carbon dioxide and water, and two completely different methods, the Rapid expansion of supercritical solution and supercritical hydrothermal, were used to produce fine particles of drug (acetaminophen) and nano metal oxide (zirconium dioxide and bismuth ferrite). The summary of this research are as follows:1. The solubility of acetaminophen in SuperCritical-Carbon Dioxide (SC-CO2) with and without menthol as a cosolvent... 

Particle reinforced aluminum matrix composites have considerable attraction in automotive and aerospace industries due to their special properties as light weight, high ratio of strength/density, improved elastic modulus, low coefficient of thermal expansion and high wear and corrosion resistance. Among the production processes of metal matrix composites, accumulative roll bonding process has particular importance due to producing ultrafine grained composite sheets. However, uncontrolled and undesired agglomeration of particles is the main problem in producing these composites. In this research, the Al2O3 and SiC nanoparticles were electrostatically stabilized against agglomeration by... 

Recent studies in nanotechnology field have shown this technology could solve many challenges and needs in oil and gas industry. As yet, many applications of nanoparticles in enhanced oil recovery have been reported. One of the most important applications is wettability alteration due to presence of nanoparticles in injecting fluid, which has recently been studied by several research groups. These studies indicate that, presence of nanoparticles in injecting water would improve oil recovery. However, there is no adequate information about the mechanisms affecting fluid flow in reservoir rock and its mathematical modeling.The aim of this project is to evaluate the effect of injection of... 

Heavy metals, present in many industrial wastewaters, are considered as major pollutants of environment. Various methods to removal heavy metals effectively from effluents have been used in industry, yet more efficient and economical methods are required. Magnetic iron nanoparticles are known for their superior adsorption, ion exchange and electro-static forces characteristics.The aim of this study was to evaluate the efficiency of magnetic nanoparticles for removal of hexavalent chromium (VI) and Divalent nickel from wastewater and the parameters that influence the removal.The magnetite nanoparticles were prepared by co-precipitation method where produced Fe3O4 nanoparticle’s average size... 

In this study, the substituted barium hexaferrite nanoparticles with general formula Ba1-xCexFe12-xCoxO19 (x = 0, 0.1, 0.2 and 0.3) were prepared by the sol-gel auto combustion method. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), Mossbauer spectroscopy (MS), vibrating sample magnetometer (VSM) and performing network analyzer (PNA) were employed to investigation of structural, magnetic, dielectric and microwave properties of barium hexaferrite nanoparticles. Moreover, differential scanning calorimetry (DSC) were performed to observe the formation mechanism of barium hexaferrite. DSC studies showed that barium... 

Drilling of low pressure layers is one of the major problems in petroleum industry, in which requires a lightweight drilling fluid for drilling of these layers. Use of lightweight Colloidal Gas Aphron (CGA) leads to loss reduction of drilling fluid, decreases formation damage and finally, well stimulation costs will be reduced. Use of nanoparticles can improve the aphron drilling fluid performance. But there is little information in the literature about the role of natural surfactant in the presence of nanoparticles on the CGA based fluid properties. Especially, micro bubbles behavior in the presence of nanoparticles in pore scale is less considered. This study consists of two parts, in the... 

In this work, nanoparticle production via microemulsion method has been investigated from theoretical and experimental points of view. Population balance approach has been used to model nanoparticle formation in an inverse microemulsion system. The study of nanoparticle formation in the inverse microemulsion system of Marlipal O13/40-cyclohexane-water reveals that in low reactants concentrations, the coagulation phenomenon has an important effect on the formation of particles. In this regard, the population balance equations has been developed to consider the coagulation phenomenon in the inverse microemulsion system. The kernel of coagulation has been calculated based on attractive and...