Sharif Digital Repository

According to the reported field experiences, excess water production from high permeable thief zones of oil reservoirs is the main source of severe operational problems and economic issues. Application of Preformed Particle Gels (PPGs) is an effective technique to overcome this problem. Static test analysis is a primary method for evaluating the performance of PPGs material at different conditions of pH, salinity, etc. However, the effect of the presence of oil and rock on the kinetics of swelling/de-swelling of PPGs is not well understood. Also, considering the vast field application of Co_2-based oil recovery methods, it is interesting to study the effect of carbon dioxide gas on swelling... 

Nowadays, too much attention has been paid to Solid Oxide Fuel Cells (SOFC). One of the key components in SOFC is interconnect which plays an important role in SOFC performance. Interconnect can be either a metallic or ceramic layer that sits between each individual cell. The reduction in operating temperature of SOFC resulted in interests in using metallic interconnectors. However, the oxidation of these metallic materials is big challenge. Chromium (Cr), Nickel (Ni) and Iron (Fe) alloys have been employed to overcome this deficiency. However, these alloys bring another difficulty which is the presence of active elements such as Cr which reduces the performance of interconnects by forming... 

Excessive water production is one of the common problems during oil recovery that causes the production to decline, the operating cost to increase, and the well to shut in. The heterogeneities such as fractures in the reservoirs causes waterfingering and decrease waterflood efficiency, recovery factor and increase production costs and lead to high watercut. On of the methods used to prevent producing undesireable water from reservoirs is using Preformed Particle Gels (PPGs) that is known as plugging agent. These particles are injected into the hydrocarbon reservoirs and plugged the flow of water and prevent the production of water.In recent years, it has been recognized that the use of... 

"osteoarthritis" is one of the most common joint diseases. This disease has a close relationship with factors such as aging, weight gain, genetics, mechanical pressures, and severe injuries. Although the mechanism of this disease is not fully understood, inflammation is one of the main causes of its exacerbation and progression. controlling inflammation can greatly help in controlling the disease. One of the common treatment methods for osteoarthritis is intra-articular injection of hyaluronic acid and triamcinolone as anti-inflammatory drug. Hyaluronic acid is the main component of synovial fluid, with its viscosupplementation property, prevents bones from rubbing against each other in the... 

The electric field induced response of a charged droplet in an uncharged gel is calculated theoretically. For modeling, the gel is considered as a soft porous solid that is saturated with a Newtonian electrolyte and modeled as a continuum that contains 3 phases: a porous, soft and compressible solid, an incompressible Newtonian fluid and the ions inside fluid. Droplet is modeled as a charged incompressible Newtonian fluid immiscible with the gel. The droplet-gel interface is considered as a surface with electrostatic potential ζ . After obtaining governing equations, they solved by using perturbation methodology and linear superposition. Boundary conditions, especially at the droplet-gel... 

Water production from high permeability regions such as fractures and channels in the reservoir can be considered as one of the problematic issues in oil production. In order to control water production, chemical methods such as polymer injection, surfactant injection, and foam injection are widely used, among all of them, Preformed Particle Gel (PPG) is the most efficient method.By injecting the preformed particle gel into the reservoir and blockage of fractures and high permeable regions, Injected water bypasses to the target zone. In this study, preformed gel with a unique formulation was synthesized by free radical polymerization method in the laboratory.Nano-Clay and Nano-Silica were... 

Nowadays, dye-sensitized solar cells (DSSCs) are highly regarded as a cheap alternative for conventional silicon-based solar cells. Improvements of their efficiency and performance sustainability are two major challenges of their commercialization. Engineering of the photoanode electrode by controlling its thickness, chemical composition, and morphology was proposed as effective method in increasing the light conversion efficiency of the cells. In the present study, mesoporous TiO2 beads with different arrangements including pristine mesoporous beads, mixtures of mesoporous beads with nanoparticles, and in the form of two-layer structure of nanoparticles (as an active layer) and mesoporous... 

The aim of this project is to investigate the effect of adding nano-silica on reinforcement corrosion in concrete caused by chloride. Because concrete is a porous composite, which is exposed to a corrosive environment such as the sea, it needs more protection to control the corrosion of steel reinforcement. This has led to the necessity of using nanoparticles in concrete mortar. This research was done by evaluating the effect of adding nanosilica gel as a partial replacement of type 2 Portland cement and hydrophobic nanosilica, respectively, to mortar and concrete surface on the corrosion resistance of reinforcement. In the project, three models of concrete samples with a cement grade of 550... 

Excessive water production in highly heterogeneous mature reservoirs (water flooded or affected by water zones) leads to increased production costs. Water production causes sediment formation, creation of corrosion, water treatment and disposal, and finally due to the inefficiency of production, it leads to closure of the well.Among the methods introduced to reduce water production, the use of polymers and gels as an affordable and effective method has been widely used in enhanced oil recovery processes. The main mechanism in this method is blocking or limiting the major paths of water flow (fractures or high permeability zones) and thereby increasing sweep efficiency in water injection.... 

In this thesis, it reports the fabrication of novel magnetic nanocomposites combining the unique properties of magnetic nanoparticles and cross-linked basic polymers that their surface functionalized by suitable groups such as carboxylate groups, pentaethylenehexamine and so on to achieve the maximum adsorption capacity of dyes and heavy metal ions. The performance of the magnetic nanocomposites for removal of anionic and cationic dyes and heavy metal ions were evaluated in different conditions of pH, contact time and initial concentrations. Moreover, the adsorption mechanism was investigated by kinetic models and isotherm studies. The results showed that the abovementioned adsorbents can... 

Photochromism is defined as a reversible transformation of a chemical species between two forms having different absorption spectra induced in one or both directions by photoirradiation. Among various organic photochromic compounds, including spiropyrans, azobenzenes, spirooxazines, dyarylethenes and fulgides, spiropyranes have been attracted more attention due to their more sensitivity towards photo, pH, heat, pressure and solvent polarity. UV irradiation of spiropyrans, breaks the C-O bond of pyran ring and makes cis-trans isomers. Therefore, closed structure of the molecule, named as spiro (SP), is converting into the flattered and conjugated merocyanine (MC). Mc is photochromism, polar... 

As the reservoir matures, especially in fractured reservoirs, oil production is usually accompanied by the production of some unwanted water. Water production causes environmental problems and imposes high costs on the production system, including the cost of separating water and oil, corrosion of facility, and sometimes, leading to abandoning well. One way to solve this problem is to use gels as a blocking agent. Today, preformed particle gels are used as an alternative to in situ gels, which can solve some issues of in-situ gels, such as uncertainty in gelling time and penetration depth.This research comprises three main parts. In the first part, four samples of preformed particle gels... 

To produce polyurea, a secondary or higher amine must be combined with a diisocyanate. For this purpose, we first combined diethylenetriamine, and hexamethylene diisocyanate, which did not have good mechanical properties due to the aliphatic nature of the molecules. Then, instead of hexamethylene diisocyanate, we used MDI, which was mixed using a mechanical mixer but became a paste that was not suitable for coating applications. To reduce the viscosity of MDI, propylene carbonate was added to improve mixing, but the gel time also increased. Because the solvent was non-polar and the amine was polar, it was decided to add the solvent, amine, and polyvinyl alcohol as surfactants to allow faster... 

Magnetic gels and ferrogels are smart composite materials made by combining magnetic particles in a polymer matrix. These materials have been considered due to their special properties such as deformation and change of mechanical properties in the presence of external magnetic field. Having polymer properties along with the magnetic properties of metals, have led these materials to many uses such as drug delivery and artificial muscles. The increasing use of these materials has led researchers to continue research in the field of modeling ferrogels. Due to the porous nature of ferrogels, the ability to absorb a lot of liquid and their large deformations in the magnetic field, modeling of... 

Polymer electrolytes are most frequently used electrolytes especially in lithium ion batteries. The gel-polymer and polymer-ceramic electrolytes were synthesized using DMA plasticizer, LiClO4, and SiO2 ceramic Nano fillers through coating method. EIS, FTIR, XRD, SEM, and TGA analyses were carried out on electrolytes. The optimum amount of perchlorate and polymer was obtained 0.5 M and 5% w/w, respectively. Also, the optimum amount of silica was obtained 2% w/w. the optimizations were carried out suing conductometry. The EIS analysis showed the ionic conductance of gel-polymer 1.8 mS.cm-1 while that of ceramic-polymer was obtained 2.8 mS.cm-1  

In this thesis, organic solvent absorbent crosslinked polymers based on carbon nanotubes and hydrophobic monomers were synthesized by radical polymerization. Surfaces of carbon nanotubes were modified for the better dispersion in a polymeric matrix and participation in polymeric reactions. Different hydrophobic monomers such as diphenyl acrylamide and ionic liquids based on vinyl imidazolium cation with long alkyl chain and lipophilic counter anion such as tetrafluoro borate were synthesized and utilized with hydrophobic long alkyl chain acrylate monomers for the preparation of organogels. Swelling behavior of synthesized organogels in different organic solvents was investigated. The results... 

The cornea is a transparent, avascular, multilayer, connective tissue. When the erosion process of these cells occur, where natural and quick restoration is expected, corneal disorders begin. Regeneration of corneal tissue, using a biocompatible method is a great point of interest. Nowadays, scaffold based on amniotic membrane is used as a basement membrane in the regeneration of corneal tissue. Lots of researches focused on using auto graft scaffold to decrease the inflammation and infection of an allografts and synthetic scaffolds, while overcoming amniotic membrane’s weak mechanical properties. The aim of this survey is to construct an appropriate scaffold from patient’s own blood to... 

In this thesis, the mechanical properties of collagen hydrogels were characterized using Finite Element method and the collagen content effect on the mechanical properties of hydrogels were investigated. Hydrogels samples with different collagen content were assessed which caused diverse mechanical behaviors. Due to the nonlinear behavior of hydrogels, using numerical methods and simulation softwars can be helpful to determine the mechanical properties of these material and save agreat deal of time. Finite Viscoelaticity theory was exploited for a UMAT Subroutine in Abaqus and an special Starin Energy Function was selected to extract the formulations. The agreement between simulation results... 

Many heart attacks and strokes are caused by improper clot formation in the vascular system. Mathematical understanding of the clot formation process and the influence of various factors in the clot formation process is very important. In this study, the aim is to simulate and understand the clotting process mathematically by considering natural, external and general mechanisms in the clotting process. In this process, when damage occurs in the endothelial region of the vessel, tissue factor is released and 38 different substances react with each other inside the plasma, eventually forming fibrin. To simulate the movement of different chemical components and proteins in plasma, the... 

Polyethylene is the most widely used plastic material in the world for reasons such as lightweight, good strength, good processability, low cost, and low maintenance cost, and very good chemical resistance. One of the applications of polyethylene that has received much attention in recent decades is its use in the manufacture of hot water pipes. To maintain the properties of polyethylene at high temperatures, it must be crosslinked at a proper level. Appropriate antioxidants should be used to prevent the degradation and oxidation of polyethylene during the process as well as long-term operation. Concomitant use of phenolic antioxidants for long-term stability during service and phosphorus...