Sharif Digital Repository

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... 

It is well known that poly(ethylene terephthalate) (PET) is a high melting compound which has exceptional value as a fiber and film-making material, and which currently dominates the whole field of linear polyester substances. However, the high viscosity and limited solubility in liquid solvents restrict its processing to powders and hence the range of applications of such a polymer. Traditionally, crushing, mechanical grinding, ball milling and precipitation from solution are methods for producing powders. The first three ones inevitably change the property of materials. The last one is carried out on the basis of the application of an anti-solvent to decrease the solubility of a... 

In recent decade energy crisis causes research on luminescent devises gains special importance. Particularly, hybrid LEDs (organic- nanocrystal) have been studied by a number of researches due to their advantages. Easy fabrication and narrow spectrum of radiation are mentioned as the most important benefits. The emissive layer is the most important part in these diodes which made of semiconductor nanoparticles. There are a variety of chemical methods for synthesis of semiconductor nanoparticles. We focus on aqueous method for nanoparticles synthesis because of its advantages. Alloyed semiconductor nanoparticles of ZnxCd1-xS were selected for this research work. The manifest features of the... 

Successful formulation development for poor water soluble drugs is a critical, long-standing and challengeable problem in cancer treatment. One of the methods for transporting low-soluble drugs is using nanoparticles which are able to pass through capillary walls of tumor tissues due to their small size. An example of the nanoparticles is micelle systems. Functionalized β-cyclodextrin (β-CD) by hyper branched polyglycerol (HPG) can dissolve low-soluble compounds. This polymer can be used in preparing micelles. In this project, β-cyclodextrin (β-CD) by anionic reactions is initiator for polymerization of glycidol monomer. Hydrophobic cavity of the β-cyclodextrin (β-CD) in placing the phenyl... 

Previous studies indicate that increasing cement compressive strength can’t prevent loss of zonal isolation and casing collapse in worse case during well operations or formation loading. Since standard cements with high compressive strength can’t solve these problems, so application of elastic cements with low Young’s modulus and high Poisson’s ratio becomes important. These cements sustain generated stresses during well operations and prevent creation of point loads when formation creep occurs. For this purpose, a new additive was designed in order to improve the cement elasticity and tensile strength. It is a nanoparticle and named EX-RIPI (by Research Institute of Petroleum Industry,... 

Due to the diameter and size of nanoparticles, they have been applied in various fields to make materials with better properties. In this thesis, the purpose has been to investigate the influence of nano alumina and nano alumina incorporating nano silica particles on mechanical properties of cement mortars. Different portions of nano alumina that include 1, 3, and 5% have been used. Nano silica with 1 and 2% has been used. At first, nano particles were dispersed by sonication with water, and then the cement mortars with various percent of nano additives with the same workability have been made. After different curing periods (7, 28 days), the specimens have been tested for bending and... 

In this research, TiO2 nano-particles were electrophoretically deposited on the FTO glass to produce self-cleaning property. Two type of suspensions with different TiO2 nano-powders were used. Merck and fabricated by sol-gel route, TiO2 nano-powders were utilized in suspensions and Conductivity, pH and zeta potential of suspensions were determined. Electrophoretic deposition of two kind of suspensions was performed in different voltages of 10, 30 and 60V (for 10s) and room temperature. TiO2 coatings were sintered in 450oC for 1 hour. The phase transformation of TiO2 films were measured using XRD. Morphology, average particle size and thickness of TiO2 films were analyzed using FESEM... 

Dye sensitized solar cells (DSCs) are among the 3rd generation solar cells which their mechanism of light absorption is similar to chlorophyll in green leafs and is based on photo-excitation of dyes. The electron-hole pairs of photo-excited dye separate at the interface of mesoporous semiconductor-dye-electrolyte. One of the approaches to increase the light path length and therefore the light harvesting efficiency in DSC is the addition of light scatterers inside the mesoporous semiconductor (photoanode).In this research, nanoparticulated hollow TiO2 fibers are introduced as novel light scatterers in DSCs with simultaneous light scattering, light trapping and high surface area. Light... 

After primary and secondary recovery processes more than 50 percent of oil remains in reservoirs. Therefore for more recovery from these reservoirs, methods of enhanced oil recovery should be applied.In this paper the effect of nanoparticles of SiO2 in size of 14 nm, on wettability is investigated. Using this nanoparticle, the wettability of carbonate rock in reservoirs could be changed and alter from oil-wet or mix-wet to water-wet. To assess this, hydrophilic changes of sandstone core and carbonate core are studied using the contact angle test. The same test is done on the carbonate core saturated with brine and oil that had received injection with brine and nanoparticles of SiO2 with two... 

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... 

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... 

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... 

In current project, high purity nanoparticles were synthesized by use of Electromagnetic Levitation Melting Gas Condensation (ELM-GC) method. In this case high purity aluminum samples were melted by this method to a temperature of 1683 0C in a silica tube. High purity argon and helium gases were employed as carrier gases and cooling agents. To study particle size, morphology, and purity of obtained nanoparticles, Field Emission Scanning Electron Microscopy (FE-SEM), X-ray Diffraction (XRD), Dynamics Light Scattering (DLS), and ADS analysis were employed. The FE-SEM and DLS tests confirmed narrow size distribute of spherical shape pure aluminum nanoparticles under both inert gases. The... 

One of the most convenient methods for the synthesis of metal oxide nanoparticles, inorganic ceramic materials and catalysts is supercritical hydrothermal method. In its pure form or mixed metal oxide nanoparticles have potential applications are wide. An important aspect of functional metal oxides of uranium dioxide as the selective catalyst for the conversion of methane to methanol and chlorinated organic matter decomposition is used. The main issue that led to the definition of this project was that nanoparticles synthesized with supercritical hydrothermal conditions influenced by change in the temperature. Temperature also affects the particle size and the conversion efficiency. This... 

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... 

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... 

There are many techniques that have been used to create hydroxyapatite nanoparticles coating on nanotubes. Electrophoretic deposition (EPD) is one of the methods that has advantages of short formation time, needs simple apparatus, little restriction of the shape of substrate, no requirement for binder burnout as the green coating contains few or no organics. In the research, first, titanium dioxide nanotubes were fabricated by anodic oxidation. Anodizing voltage effect on the morphology of nanotubes was evaluated. SEM images was shown that in the anodizing voltage 20V, nanotubes were the most regular. Then, Hydroxyapatite nanoparticles has been deposited onto nanotublar TiO2 by... 

In this research, a powder containing magnesium-aluminate spinel particles is prepared based on co-precipitation method and 5% , 10%, 15% and 20% zirconia-contained composites are produced as second phase from the synthesized powder. The raw materials used in the synthesis comprise hexa-hydrated magnesium nitrate, nona-hydrated aluminum nitrate, ammonium bicarbonate, 28% ammonium solution and distilled water. The properties of the powder is then investigated using STA, XRD and SEM tests. Also, XRD and SEM analyses as well as triple point flexural strength and Vickers hardness tests are carried out in order to investigate the effect of adding zirconia to the powders. The variations of the...