Sharif Digital Repository

Inert gold become catalytically active when dispersed in the form of nanoparticles. Isolated gold nanoparticles have demonstrated high catalytic activity for both oxidation and reduction reactions. In order to obtain high catalytic activity, gold nanoparticles are generally dispersed on support materials, among which oxides are commonly used. However, a substantial decrease in activity and selectivity of the immobilized catalysts is frequently observed due to the heterogeneous nature of these support materials in reaction media. In the course of our study on the metal-based catalysis for synthesis of organic compounds, we herein report that rod-shaped Au nanoparticles in aqua solution... 

Pure zinc coating and Zn-TiO2 composite coating were deposited from two methods: Direct and Pulse Current from a sulphate bath. D.C. section, current density and particle concentration in electrolyte were investigated. Moreover in Pulse section, frequency, duty cycle and maximum current density were investigated as parameters. Morphological properties of these coatings were investigated by FE-SEM and corrosion behavior by potentiodynamic polarization in 1M NaCl. In D.C. section, in investigation of the effect of current density, an optimum was observed in case of obtaining the highest amount of deposited particles at 0.1 A/cm2 and amount of 2.93%. This amount is the highest one in D.C.... 

The optical properties of semiconductor nanoparticles are dependent on their size. Then, the important problem in synthesized semiconductor nanoparticles is controllable of their size. In this research ZnS nanoparticles were synthesized by hydrothermal method and taguchi design of experiments and study on effect of solvent, reaction temperature and molar precursor ratio on band gap and particle size of ZnS . The UV-Vis spectrum was carried out for measurement of band gap and the size of nanoparticles by using the effective mass approximation. The X-ray diffraction patterns exhibited a cubic zinc blende structure for the nanoparticles. The ZnS:Mn +2 nanoparticles werw synthesized. With... 

The aim of this research is to study the effect of surfactant type and the concentration reactants on the size, shape and magnetic properties of iron-gold core-shell magnetic nanoparticles (NPs) useable for biomedical application. The reverse micelle procedure was employed to synthesize iron NPs using two surfactants of CTAB and SDS. A gold shell with a thickness in the range of 10 to 40 nm was induced by reverse micelle method in order to prevent oxidation of the iron core. The size and morphology of NPs were studied by transition electron microscopy (TEM). It was found that the size of NPs increases by the increasing the reactants concentration while the morphology of the NPs was not... 

In this study new magnetic solid phase extraction (MSPE) methods based on Fe3O4 magnetic nanoparticles (NPs) for extraction and preconcentration of oxadiargyl and fuoxetine from aqueous and biological samples were developed. In the first work, Fe3O4 NPs was successfully used as a magnetic nano-sorbent in magnetic micro-solid phase extraction (M-µ-SPE) of oxadiargyl, a newly used pesticide, from environmental water samples prior to gas chromatography-mass spectrometry determination. Oxadiargyl in mild acidic condition has tendency to be adsorbed on Fe3O4 NPs surfaces. Most important parameters that affect the extraction efficiency were also studied. Under optimized condition, the proposed... 

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... 

This thesis encompasses two parallel, but independent subjects as follow: The first part of the thesis deals with synthesis of bimetallic Ni-Au nanoparticles (Bi Ni-Au), and application of them as electrodes in the methanol fuel cells. The Bi Ni-Au nanoparticles for this purpose were synthesized by controlled reduction of HAuCl3 and NiCl3 in the aqueous medium using NaBH4 as reductant and PVP as stabilizer, and immobilized on the surface of a glassy carbon (GC) electrode by means of Nafion polymer. The obtained electrode then was conditioned in an alkaline solution by cyclic voltammetric method in potential range 100 -700 mV (vs. Ag/AgCl). Physicochemical characterizations of the... 

Mesoporous silica nanoparticles (MSNP) have attracted lots of attentions because of their particular characteristics. Physical characteristics such as structure, morphology, porosity, and size of these nanoparticles have strong impact on their function and it can be conceived a wide range of applications for them by manipulating these characteristics. In this research, monodispersed MSNPs with a controllable size in the range of 50-130 nm and pore size in the range of 4-24 nm were synthesized and positively functionalized in order to develop a carrier for the delivery of nucleic acids (siRNA and pDNA). The MSNPs were synthesized by the template removing method.In this method, sodium... 

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... 

A simple and effective procedure is proposed for colorimetric detection of hydrazine and phenylhydrazine. It was found that the reduction of AuCl4- to gold nanoparticles (Au-NPs) by these compunds in the presence of Tween-20 as a stabilizing agent produced very intense surface plasmon resonance peak of Au-NPs. The plasmon absorbance of the Au-NPs allows the quantitative spectrophotometric detection of the hydrazine and phenylhydrazine. The calibration curves derived from the changes in absorbance at λ = 530 and λ = 550 nm for hydrazine and phenylhydrazine, respectively were linear with concentration of hydrazine and phenylhydrazine in the range of 1.0×10-6- 2.0×10-4 M, 5×10-6 - 4×10-4 M,... 

Metal matrix nanocomposites contains ceramic ultrafine particles in a metal matrix, are used to improve the mechanical properties such as hardness and wear of coatings. For developing metal matrix nanocomposites, there are many methods. Electrochemical deposition process is one of these methods that have some advantages like uniform depositions on substrates with complex shapes, low cost, good repeatability and reducing waste. In this project, for increasing the hardness and wear resistance of nickel, composite coatings of nickel - titanium nitride was created by using electrochemical deposition of Watts bath contained titanium nitride particles. In order to increase the amount of... 

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... 

Production of nano-particles using arc-discharge method in a liquid nitrogen environment is a proficient way of forming nitride Particles whose formation by other methods is difficult and expensive. Amongstall, Titanium nitride (TiN) is of significant importance because of its high formidability and its optical and electrical metal properties due to plasmonic electrons. This research studies the production of titanium nitride Nano-particles using arc-discharge method and investigates optical properties and features, specially dielectric constant and optical extinction coefficient. Modeling interband Transitions is also discussed to revise Drude's electron theory. First, in experimental... 

This present work is an introduction of a new electrochemical sensor toward the determination of biomolecule. A simple electrodeposition method was employed to construct a thin film modifier of palladium–gold nanoparticles (Pd–AuNPs) decorated multi-walled carbon nanotube (MWCNT) on the surface of glassy carbon electrode (GCE). Morphological characterization of the modified electrode was performed by the scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and cyclic voltammetry (CV) techniques. This nanostructured film modified electrode effectively exhibited enhanced properties for the detection of ceftazidime (CFZ). The effects of various experimental variables such... 

Considering the widespread applications of amides, synthesis of these compounds is of great importance. The one pot oxidative addition of amines to aldehydes is one of the most simple and appealing approaches to synthesis amides. With the aim of developing a mild and convenient approach towards preparation of amides, numerous methods have been reported for this important process over the past few decades. These improvements have been mostly related to the optimization of reaction conditions and the use of more challenging substrates including diverse derivatives of aldehydes, and also design a novel and effective catalytic systems. Due to the various advantages of supported heterogeneous... 

The present work is based on the, synthesis and investigation of photocatalytic activity of TiO2, TiO2/MWCNT, ZnO and ZnO/MWCNT nanostructures. The nanostructures were prepared using multi-walled carbonnanotubes (MWCNT) as templates.The SEM images of TiO2 and ZnO nanoparticles and TiO2/MWCNT andZnO/MWCNT showed that nanosize TiO2 and ZnO particles homogeneously and densely supported on the surfaces of multiwall carbon nanotubes the photocatalytic activity of the TiO2, TiO2 /MWCNT, ZnO and ZnO/MWCNT was examined by the degradation of Basic Blue 41(BB41) under UV and Vis lights. The optimum conditions for degradation of BB41 on TiO2 where found to be: calcination temperature (450 °C), dye... 

In addition to chemical stability and biocompatibility, because of the characteristics of quantum dimensions, gold nanoparticles are used in detecting cancers, imaging and therapeutics .Atomic interactions between gold particles and bioparticles are influenced by the dimensions of gold particles .Therefore, in this project, after introduction of various water models and used potentials for modeling by the method of TIP3P, we studied gold clusters in different dimensions and densities, by using EAM potential in the aquatic environment .Then we can pave the way for studying proteins besides gold nanoparticles, in the future studies. Besides, gold particles were studied as colloid, so as to... 

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... 

This research aims to develop a drug delivery system based on mesoporous silica nanoparticles (MSNPs) for hydrophobic drugs and evaluating their cytotoxicity. The internal environment of the body is aqueous, while most of effective drugs display poor aqueous solubility, resulting in insufficient bioavailability. Due to their several unique properties, such as a large surface area, tunable pore size, facile surface multi functionalization and excellent biocompatibility, MSNPs are recognized as promising and powerful tools to overcome this hurdle. In the present study, MSNPs were synthesized using template removing method and then were functionalized through grafting procedure. They were... 

Separation and identification of metal nanoparticles in surface water samples such as river water is very important. Nanoparticles specially metal nanoparticles have small dimensions can easily pass through from the body's outer immune system and disrupt biological function. Most of the nanoparticles have active surface so environmental contaminants can be absorbed on their surface and then can penerated in the body, and they may cause disease. Therefore determination of nanoparticles type and concentrations and their separation from the surrounding environment, especially surface waters is important. Separation and preconcentration of metal nanoparticles was done by using cloud point...