Sharif Digital Repository

The aim of this work is fabrication of magnetite@silica@gold particles. Study of the effect of pH showed that increasing pH from 9 to 12 resulted in a decrease in the size of magnetite nanoparticles from 7.9±1.38 nm to 5±0.64 nm. The TEM results indicated that modifying magnetic nanoparticles with sodium citrate prior to coating with silica leads to a narrow particle size distribution (275±16.1nm) and less number of silica nanoparticles without any magnetite core. Three methods were applied for attachment of gold nanoparticles seeds onto the silica surface: 1) use of an electrostatic interaction between positively-charged aminated silica and negatively-charged gold nanoparticles surfaces, 2)... 

Porous polymeric particles have the extensive application in various sciences and various methods have been introduced for production of these particles. Depending on method of production, porous polymeric beads can be produced in diverse shapes, pore size, pores interconectivity, surface morphology and chemical properties. In common methods for production of porous polymeric particles, tuning the size and porosity is difficult or even impossible. Porous polymeric beads with the vast surface area and good functionality have been applied for adsorption of various materials. The purpose of this study is therefore to investigate a new procedure for the production of porous polymeric... 

Zinc oxide thin films due to special specification and properties have variable application in different industries. Recently because of wide application of zinc oxide doped SiO2 in optoelectronics and sensors, lots of investigation have been focus on it. Meanwhile due to the SiO2 hydrophilic properties, doping of ZnO with SiO2 can improve self-cleaning properties zinc oxide membrane.It this project zinc oxide and ZnO doped SiO2 thin films with different composition were made by sol-gel and dip-coating process used for coating of mentioned sol over the quartz surface(15*25 mm). At first point different sol with different components was mixed with each other to make composite films but due to... 

Inthisresearch,silicananoparticleswere synthesized ymicroemulsionmethod. Thengadoliniumcarbonatewascoated onsilicananoparticles by depositiontechnique.After thatTiO2wascoatedbydeposition techniqueonsilica/gadolinium carbonatenanoparticles.The results of infrared spectroscopy (FT-IR) on silica/gadolinium carbonatesamples showed carbonate bonds. The results of X-ray diffraction (XRD) test on samples of silica/gadolinium carbonatethat had been calcined at 600 0C for 2 h, showed that silica and gadolinium carbonate phases are amorphous and with increasing calcination temperature, gadolinium oxide crystalline phase is formed. For TiO2 coatings process, the effect of TBOT concentration, the... 

Tumor markers are substances that are naturally found in blood and other fluids in body, but in abnormal conditions such as cancer and metastasis, their level increase. The aim of researching about tumor markers is to find a way for discovering cancer only with a blood test and replace with the current methods such as ELISA, and any type of cancer can be detected by these tests. In this study, molecular imprinted polymers were synthesized with biomolecules. To do that, silica microparticles were used as solid base and after functionalizing their surface, a thin film of polymer was synthesized on them. To optimize the components concentrations and the polymer thickness on the silica surface,... 

The investigations on hydrophobic surfaces have attracted lots of intrests in science and technology. Silica sols have been used extensively in the area of producing hydrophobic coatings. On the other hand, carbon-based materials have attracted of a great deal of scientific interest in recent years. The purpose of this research is synthesis and investigation on the properties of Silica- Graphene Oxide nanocomposite coating.Graphene Oxide synthesized by using Hummer’s method. Silica nanoparticles were prepared using sol-gel process and tetraethylorthosilicate (TEOS) as precursor. The surface hydroxyl groups of silica nanoparticles are replaced with Methyl groups by treatment with... 

In this study, polyelectrolyte-coated magnetic silica nanocomposites were prepared via the covalent attachment of polyelectrolytes onto the as-prepared magnetite-silica particles with core-shell structures and average diameter of 210±50 nm, and subsequently applied for the immobilization of lipase molecules. In this regard, polyethyleneimine (PEI) with two molecular weights of 10000 and 750000 and polyacrylic acid (PAA) with two molecular weights of 1800 and 100000 were utilized. The type and molecular weight of the polyelectrolyte molecules greatly impacted the concentration of binding sites on the particles surface and consequently on the lipase immobilization efficiency and loading... 

In this study Ni-P-Al2O3-SiO2 nano composite coating developed on aluminium alloy 6061 using electroless method. Due to oxidation of aluminium, a double zincate pretreatment performed to obtain proper adhesion of coating on substrate. Effect of solution temperature and heat treatment on thickness and property of nano composite coating was studied. Furthermore, effect of concentration of nano particles in electroless solution on thickness, morphology, micro hardness, wear behavior, corrosion resistance and particle content in coating were investigated. Field emission scanning electron microscopy (FESEM, Hitachi S-4160) with energy dispersive spectroscopy (EDS) was used to evaluate morphology... 

The purpose of this research is producing one phase silica superhydrophobic coating by sol-gel method and drying temperature less than 200 degrees. For preparing micrometer and nanometer scaled hierarchical structure based on silica, TEOS precursor and Fumed Silica nanoparticles were used by density of 43/30 cc/lit and 6/52 gr/lit in order to provide desired roughness in the range of 40 nm. Moreover, HMDS surface modifying agent was used for reducing the surface energy of coating, which is not a danger to the environment in comparison to the same substances. The best Contact Angle is 155 degree and the best Sliding Angle is less than 5 degree. For instance, it was created with the... 

The main purpose of this project is synthesis of the silica nano-sheets by means of microfluidic techniques. Continuous process, precise control of reaction condition, and higher production rate can be considered as main pros of silica nano-sheets synthesized by microfluidic platforms. General method can be explain as follow: first two oleic and aqueous phase are injected to the microfluidic system, then oleic phase breaks down in aqueous phase drop-wisely and by performing sol-gel reaction on the oil-water interface a silica crust is made on oil droplets. Eventually, oil droplets are left the system and broken down and silica nano-sheets are made. FESEM and microscopic images of... 

One of the most useful method in medical imaging is Magnetic Resonance Imaging. Gadolinium base contrast agents used to improve images contrast made by MRI. There are some problems with using these drugs, such as toxicity and lack of targeting. In this research, Silicon nanoparticles were produced by a new fashion of removing template method. Particle size was scanned by Dynamic light scattering (DLS), mesoporous structure was investigated by Brunauer-Emmett-Teller (BET), and amine functionalization was recognized by Fourier transform infrared (FTIR). Functionality was determined by evaluation of signal and relaxation of nanoparticles.T1 was defined by a 1.5 tesla power MRI device. The... 

Epoxy resins have good mechanical and thermal properties, high chemical resistance and low shrinkage during cure but in spite of these good properties,they are brittle and this limits the usage of them. Adding a second, soft or rigid, phase has been always an effective strategy to improve the toughness of epoxy. Rigid phase used in resins are divided into organic and inorganic. The aim of this study is to increase epoxy toughness, maintaining mechanical properties and study effect of silica and polycarbonate on fracture toughness simultaneously. Mechanical properties including yield strength and elastic modulus are evaluated by pressure test. Additionally fracture toughness and three... 

To reduce material consumption needed in production as well as avoiding thousands of tons of contaminations produced by spent materials in the battery industry, recycling was taken into consideration. In this study silica was recycled from spent lead-acid battery separators by the pyrolysis process. silica along with high-density polyethylene (HDPE), can be used as supporting material for fabricating form-stable phase change materials (FSPCM). FSPCMs are of great ability to be used as thermal energy storage (TES) in different parts of a building e. g. wallboards to reduce energy consumption. In this line, an eutectic mixture of lauric acid, palmitic acid and paraffin with the melting point... 

1- Mesoporous silica materials have been found to possess pore sizes ranging from 2 -10 nm alongside 2D-hexagonal and 3D-cubic structural features. The specific properties of nanoparticles of the mesoporous silica family, such as the collected size, porosity, morphology, and high chemical stability, make them among the best drug delivery systems and catalysts. Designing the catalysts with advanced structures that effectively locate the transition metals and create active centres onto the surfaces of mesoporous silica materials has attracted extraordinary attention. According to many studies, mesoporous silica materials without organic functional groups cannot be used as catalysts in chemical... 

Polyelectrolyte complexes based on polysaccharides have attracted the attention of researchers due to their potential for use in advanced industries. One of the most widely used cationic polysaccharides is chitosan. However, chitosan alone limits applications for smart and sustainable drug delivery due to uncontrolled degradation. For this reason, combining chitosan with another polyelectrolyte and forming a polyelectrolyte complex due to electrostatic interaction has been proposed as a solution. In the first phase of this dissertation, the effects of mixing ratio and concentration of Chitosan and Quince seed gum (QSG) on the physical and rheological properties of chitosan-QSG...