Sharif Digital Repository

In this study magnetite nanoparticles were synthesized by microemulsion and were coated with TiO2 by a precipitation technique. The synthesize process were done under fixed molar ratio of various constituents of microemulsion and molar ratio of water to oil. Results of X-ray diffraction spectroscopy (XRD) showed that the uncoated nanoparticles were consisted of magnetite as the major phase and no other detectable phases such as pure iron or hematite were found. Field emission scanning electron microscopy (FE-SEM) results showed that the synthesized nanoparticles small size and narrow particle size distribution. For TiO2 coating process the effect of TBOT concentration, water concentration,... 

Our goal in this research is to fabricate janus micromotors capable of moving in aquious media and being manipulated by an external magnetic field. Such devices were made via attaching magnetic nanoparticles to the surface of magnesium janus motor. The FTIR study proved their existance and physical attraction to the surface of the motors. They were easily navigated through a static magnetic field and janus motors aligned their motion to the direction of magnetic field. The anisotropic geometry of janus micromotors were verified through scaning electron microscope and elemental analysis. Biocompatibility of magnetised janus motors were examined through mtt assay and it was shown that the... 

Recently, Aluminum alloys have been the materials of choice for both military aircraft and automotive industries due to their high strength-to-weight ratio, high electrical and thermal conductivities and excellent corrosive resistance. However, their applications have been limited due to the low yield stress and wear resistance. In order to improve the surface wear resistance, structural and chemical surface modifications such as producing composite coatings could be applied. Gas Tungsten Arc welding (GTAW) process can be used to produce alloy and composite surface layers on different substrates. In this research, GTAW process and aluminum cored wires were used for coating of Al/Al3Ti... 

In the past few years, many research works on the controllable integration of metal nanoparticles and metal-organic frameworks were done, since the obtained composite material shows a synergism effect in catalysis and photocatalysis, drug delivery applications, gas, and energy storage, as well as sensing. For the first time, in this study, we employed template-assisted growth to synthesize Au-HKUST-1 Nanocomposite. XRD analysis entirely confirms that employing this strategy in synthesizing Au-HKUST-1 was wholly successful, and the plasmonic properties of this nanostructure were studied via UV-visible spectroscopy. In the course of synthesis, gold nanoparticles with 70nm diameter were... 

During the most recent years, investigating novel nanomaterials based on porous strucures has become an interesting field of research. Among these kinds of materials, mesoporous silica has extensive applications in catalysis, absorbants and biomedical engineering. By combining specific surface characteristics of mesoporous silica with magnetic properties of iron oxide nanoparticles, new nanocomposites owing unique properties, can be obtained. In the present research, magnetic mesoporous nanocomposite has been synthesized. Iron oxide nanoparticles were produced through reduction of water solution containing Fe2+/Fe3+ ions, followed by hydrothermal treatment of precipitan. Then, iron oxide... 

In this study in-situ Al/Al3Ti was fabricated by mechanical alloying, hot extrusion and subsequent heat treatment. First, initial pure powders of Al and Ti were mechanically alloyed with 5 weight percentages of Ti for 40 hours. The as-hot extruded samples containing 5 wt% of initial Ti particles, were exposed to heating at 600 oC for various time intervals up to 10 hours. Microstructure analysis by OM and SEM proved that in-situ Al3Ti phase was formed as a layer around Ti particles by solid reactive diffusion between Al and Ti particles. After 10 hours of heating, all the Ti particles were consumed and transformed to Al3Ti. Mechanical properties of samples were investigated by Brinell... 

The aim of this project is the surface modification of super para magnetic iron oxide (SPIONs), leading to oriented covalent bonding of antibody(AB) to these nanoparticles (NPs) and improve the efficiency of cell separation at MACS columns. For this purpose, SPIONs synthesized by co-precipitation method, and the stability of colloidal NPs then was provided by coating with Dextran . We used TGA to measure weight percentage of dextran. Some properties like particle size, hydrodynamic diameter, presence of coating and superparamagnetic properties were characterized by XRD (16 nm), FTIR, DLS (73 nm), TEM (20nm) and VSM (≈76/78 emu/g) method, respectively. Then we tried to immobilize AB on NPs... 

Ferrofluids are special stable suspensions of magnetic nanoparticles dispersed in liquid phase. These materials have numerous biological applications such as drug delivery, magnetic hyperthermia and magnetic resonance imaging due to their special magnetic properties and fluidity. Particle size and magnetic properties of ferrofluids have an important role in these applications. In this work, magnetite-based ferrofluids have been synthesized via coprecipitation and hydrothermal methods. In the coprecipitation process, cysteine and dextran surfactants have been used as ferrofluid stabilizer and effect of synthesize temperature, time, pH and surfactant concentration have been investigated on... 

Recently, preparation of biofunctionalized nanoparticles with specific magnetic properties has received great attention for medical imaging. Targeting magnetic nanoparticles with high signal in magnetic resonance imaging (MRI) could be a powerful tissue imaging and cellular tracking agent. Main purpose of this research is the synthesis of Mn3O4@polymer composite nanoparticles as a positive MRI contrast agent. Nanoparticles were prepared by modified microwavepolyol and precipitation method with average particle size of 18 and 3nm.Respectivelythe effect of diffrent parameters such as time, surfactant and the presence of water in polyol method and the amount ofpolyethylene glycol as surfactant... 

In the present study, a simple synthesis route was used to obtain Titanium dioxide nanoparticles with aggregates different in size. The purpose was to study the effect of TiO2 nanoparticles size on photocatalytic activity and develop it to sonocatalytic properties. Surface modification with polymeric and/or anionic agents were carried out to stabilize titania nanoparticles in aqueous media with neutral pH, specifically in SBF. Sonocatalytic properties of modified and bare particles were compared to show if the particles may be used in future studies on sonodynamic therapy. Results showed that increment in size of the aggregates, similar to primary particles, lead to lower properties due to... 

In this research, soft magnetic-soft composite of iron-borosilicate was prepared by cold compression and then heat treatment at 850 ° C. In order to prepare the initial mixture, the pure iron powder was mixed with different particles of 2% by weight of borosilicate and pressed at 400, 800 and 1200 MPa, and then subjected to thermal treatment at 850 ° C for one hour. After examining the density, electrical resistance, magnetic properties of DC, the magnetic properties of these materials were studied in the frequency range of 10-1000 kHz at room temperature and at 300 ° C. The results show that increasing the particle size increases the saturation magnetization and magnetism and reduces the... 

In this study, in situ Al-Al3Ti-Al2O3 nanocomposite has been fabricated on thermal decomposition of tialite (Al2TiO5 or AT) precursor in the aluminum matrix through powder metallurgy method. The high-temperature mechanical property of Al-Al3Ti-Al2O3 on this procedure has been investigated. In the first step nano-structured tialite were synthesized through citrate sol-gel methods. Then 3.5 wt.% tialite powder was mixed with aluminum by high energy vibratory milling for 3 hours. In the next step, green compacts of mechanically milled powder mixtures were sintered at 530°С for 6 hours under argon atmosphere. In the final step, hot extrusion as a consolidation method reduces the sample voids,... 

Developing an efficient visible-light-driven photocatalyst is believed to be a practical solution for clean energy and environmental remediation. The present study aimed to broaden current knowledge of the graphitic carbon nitride (g-C3N4)-based plasmonic photocatalysts by decorating polydopamine-grafted g-C3N4 (PDA/g-C3N4) with silver nanoparticles (AgNPs). The ternary nanocomposite was prepared using a facile synthesis method, while XPS and electron microscopy measurements confirmed the homogenous dispersion of AgNPs on PDA/g-C3N4. It was revealed that AgNPs successfully reduced the recombination rate of photoinduced electron-hole charge carriers. The calculated bandgap energy was... 

The search for sustainable and clean energy sources to replace fossil fuels has become one of the most important scientific and technological challenges today due to the threat of fossil fuel shortages and environmental pollution. Therefore, the need for clean energy production and storage resources, including supercapacitors, has increased day by day. Today, supercapacitors have been considered suitable for energy storage due to their high-power density, appropriate energy density, long cycle life, and high safety. The aim of the present study was to obtain activated carbon fabric as electrode material in electrochemical energy storage applications and specifically supercapacitors. The... 

The bladder is one of the most important internal organs of human that improper functioning of this organ causes various diseases such as bladder exstrophy, bladder syndrome, bladder cancer and bladder infection. The main challenge in treating these diseases is the presence of a mucous layer consisting of glycosaminoglysis (GAG) in the bladder wall that prevents drugs from reaching the surface of the bladder. Hence, drug delivery through the mucosal layer is not easy, Hence, urease micro/nano carriers have recently been considered for the treatment of bladder diseases. In this study, new janus micromotors based on black titanium oxide with asymmetric urease catalytic coating were synthesized... 

This research aims to enhance the wetting behavior of nanostructured aluminum titanate to improve adsorption and photocatalytic performance. In this study, heterogeneous nanostructures based on aluminum titanate were synthesized using the sol-gel method and modified with monohydrate citric acid. The stability of colloidal solutions was investigated by varying reaction conditions such as temperature, time, and modifier quantity. Analysis through FTIR and EDS confirmed the presence of carboxyl groups on the material's surface. XRD analysis indicated the existence of aluminum titanate, titanium oxide, and aluminum oxide phases. FESEM results revealed a significant population of agglomerates due... 

Today, due to changes in lifestyle and environmental changes, the incidence of cancer is increasing worldwide. With the advancement of science and technology, humans have always sought ways to improve their quality of life and lifespan. The most common cancer related to bone tissue is osteosarcoma. One of the most effective treatment methods is photodynamic therapy. This method requires a photosensitizer with appropriate optical and biological properties. The ideal photosensitizer should be excited with light in the NIR range and produce ROS or active oxygen species. In this research, oxygen-doped graphitic carbon nitride modified by heterojunction with Mn3O4 was used as a photosensitizer.... 

Controlled release is a crucial factor in tissue engineering and cancer-therapy applications. The main purpose of current research is to synthesis smart magnetic nanocarriers for hydrophobic drug and embedding them in a fibrous platform for anti-cancer/ tissue engineering applications. In this regard, three different drug delivery systems of magnetic nanocolloid, magnetic fibers and hydrogels were studied. In the first phase, superparamagnetic iron oxide nanoparticles (SPIONs) were synthesized and then were modified using oleic acid and thermo-sensitive polymer of pluronic F127/F68. After characterization of this composite, Response Surface Methodology (RSM) was applied to model the lower... 

In the current research, colloidal stability of two different types of coating on the surface of Superparamagnetic Iron Oxide nanoparticles (SPIONs) was studied. In the first triumph, a dual-layer coating was achieved by utilizing optimum amount of Dextran and different PEG (Poly(ethylene glycol)) concentrations which the weight ratios of iron oxide/PEG were 1/1, 2/1, 4/1, 8/1, and 16/1. Then, the presence of the coating was characterized by XRD, FT-IR, DLS and FE-SEM methods. These results together with the TGA ones revealed that as the concentration of PEG surfactant increases, the thickness of coating increases. Moreover, VSM test was performed to specify the effect of coating on the... 

In recent years, much attention has been paid to the development of biofunctionalized nanoparticles with special magnetic properties for using in clinical imaging. Targeted magnetic materials with high MRI signal intensity can be used in tissue imaging and molecular and cellular detection as valuable tools. The aim of this study has been to synthesize the nanocomposite including the functional gadolinium oxide (Gd2O3) nanoaprticles for MRI contrast agent. Synthesis and in-situ surface modification of ultrasmall Gd2O3 nanoparticles (2.5nm) with PVP was performed by a microwave modified polyol in 5 min. The structure and size of synthesized nanoparticles were studied using X-ray diffraction...