Sharif Digital Repository

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... 

Sonodynamic therapy has been developed over the last century, now it has become more widely used as a medical tool for the treatment of various diseases such as cancer. This technique involves delivery of sonosensitizing drugs, irradiation of ultrasound waves and motivation of drugs. In this thesis surface modification process with polymer and biocompatible surfactant on TiO2 nanoparticles has been done due to stabilization of TiO2 nanoparticles in neutral pH which is similar to inside-body situation. In the last step, for cancer therapy, doxorubicin as a cancer drug was loaded on TiO2 which was surface modified by PVA. The results revealed the best ratio of (PVA: TiO2), (SDS: TiO2), (SDS:... 

In this thesis the graphene-based magnetic nanocatalyst was synthesized. The surface of this catalyst was cavered by silica and AgNPs. In addithion of simple sepration by magnetbar, yeild of reaction was promoted by surface modification. Catalyst structure was verified by transmission electron microscopy , scanning electron microscope, fourier transform infrared spectroscopy, X-ray diffraction and Energy dispersive spectroscopy.At the end catalytic activity was examined by oxidation reaction in persense of different alcohols. The oxidation of benzylic alcohol with electron withdrawing substituents was more difficult and the yield was lower, but electron donor substituents effect positively... 

In this work, synthesized Fe3O4 magnetic nanoparticles andcoated with SiO2 to prepare magnetic core-shell nanoparticles. Then immobilized Schiff baseof iron and vanadium complexes on magnetic core-shell nanoparticles was prepared as a recoverable magnetic nano catalysts. These catalysts were named Fe3O4@SiO2@L1@Fe, Fe3O4@SiO2@L2@Fe and Fe3O4@SiO2@L3@V. Furthermore,olefines epoxidation, sulfides and alcohols oxidation were studied with using iron and vanadium magnetic nano catalysts. The supported catalysts were characterized by atomic absorption, FT-IR and UV–Vis spectra.The catalytic performance of the synthesized iron catalyst was tested for the epoxidation of cyclohexene, styrene and... 

In nature, catalysis is of vital importance in a wide variety of biochemical processes catalyzed by metalloenzymes. The functions performed by the metalloenzymes and their significance have inspired a range of biomimetic studies, and intense efforts have been concentrated on the synthesis of low molecular weight complexes to model the spectroscopic features of such enzymes. Concomitantly, a challenging frontier in the field of biomimetic chemistry is the development of highly reactive model compounds that are able to effect rapid and selective substrate conversion. Some important catalytic transformations that have gained attention in recent years involve the carbon-carbon coupling, olefin... 

In recent years, application of transition metal biphasic catalytic systems for different reactions is an area of intense research activity. Among these reactions, oxidation of sulfides to sulfoxides and sulfones due to their importance as an intermediate in synthesis of organic compounds is a center of interest. Also, the catalytic conversion of alcohols to the corresponding aldehydes or ketones is a fundamental transformation in both laboratory and industrial synthetic chemistry. From environmental perspectives, the development of new catalytic oxidation systems with molecular oxygen as green oxidant is particularly attractive. In recent years, ionic liquids have been extensively studied... 

The purpose of this project is to correct the surface defects of the reverse osmosis membrane. The membrane tested in this project was a thin film made of three layers of polyester, polysulfone and polyamide. These three layers provide mechanical resistance to operating pressure, suitable substrate for polyamide layer synthesis and membrane selectivity, respectively.In order to improve the surface properties and modify the reverse osmosis membrane, it was first attempted to coat it with a protective layer of polyvinyl alcohol, then by modifying this layer and improving the properties of polyvinyl alcohol and synthesizing the sulfite agent on it by the esterification reaction, to the best... 

In this research, a novel nanofiltration membrane was used to separate nitrate from water as a nitrogen-containing compound. The membrane was fabricated by interfacial polymerization on the modified polysulfone substrate. To improve the efficiency of nitrate removal, several surface and bulk modifiers were used. As modified with LiCl and PVP polymer, the substrate matrix was modified to have the highest porosity to reduce the mass transfer resistance and the much surface area to form a polyamide layer on it. The polyamide layer was then synthesized by interfacial polymerization using a blend of MPD and PIP in different ratios (1: 1 optimum ratio) in reaction with TMC (optimum concentration... 

This study tries to introduce chemical coatings to reducing evaporation from Lake Urmia(LU). In LU, average annual evaporation is estimated at more than 1,000 mm, more than 80% of evaporation occurring in the warmer months of the year. Therefore, by reducing water evaporation, especially in the warmer months of the year, the most crucial factor in water outflow from LU can be reduced.At first, on the scale of class A evaporation pan in Tehran, three kinds of chemical coatings constituted stearic acid, jojoba oil, and fatty alcohols of style and stearyl to reduce evaporation from the LU is investigated. Then the best coating that includes combine of style and stearyl alcohols with stearic... 

In this thesis, a heterogeneous nanocatalyst based on graphene oxide was synthesized. To improve the graphene oxide, it was reacted with paraaminobenzoic acid and then metal salts (cobalt and manganese) were coated on it. The structure of the catalyst was confirmed by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), quantitative X-ray diffraction (EDS) and infrared (FT-IR) spectroscopy. Finally, the catalytic properties of the catalysts were evaluated in the oxidation reaction of different alcohols in the presence of oxygen. In the presence of benzyl alcohols with lethal electron groups, the oxidation conditions are stricter and the reaction efficiency is lower.... 

Reducing water evaporation is one of the ways to overcome the low precipitation and drought conditions in water reservoirs. For this purpose, extensive studies have been investigated on physical and chemical coatings on lakes and reservoirs. Physical methods often involve the use of floating covers on the water surface to block evaporation by shading, most of which are only suitable for reservoirs with surface areas smaller than 5 hectares. In chemical methods, the evaporation can be decreased by nanomaterial coating, usually, containing long-chain molecules, which by spraying them on the surface, molecular monolayers are formed. In this study, the effect of nanometer coatings on the surface... 

In this research, polyvinyl alcohol/ sodium alginate/ nano silver nanocomposite films were fabricated by solution casting method via gamma irradiation. The purpose of using gamma radiation was reduction of silver nitrate and synthesis of silver nanoparticles. Formation of silver nanoparticles was proved by ultra violet- visible spectroscopy (UV-Vis) and x-ray diffraction (XRD) tests. Dynamic light scattering (DLS) and scanning electron microscopy (SEM) were used to study morphology, size and distribution of silver nanoparticles. Chemical structure, thermal behavior and mechanical properties of nanocomposites were characterized by fourier transform infrared spectroscopy (FTIR), differential... 

Polyvinyl alcohol and polyvinyl pyrrolidone polymers are among the biocompatible and widely used polymers that are very important in medical science and their composites are used in tissue engineering, bone engineering, etc. Various nanoparticles have been used to improve the properties of these composites. With this knowledge, in this study, to prepare a biocompatible nanocomposite for medical engineering and improve the piezoelectric, mechanical, and electrical properties of these two polymers, different percentages of these polymers were prepared with barium titanate nanoparticles and scanning electron microscopy using infrared spectroscopy tests. Mechanical properties tests,... 

Successful treatment of bone infections is a major orthopedic challenge due to the physiological and anatomical features of bone. In this project, we prepared a drug delivery system with injectable and biodegradable polysaccharide agar containing alginate, polyvinyl alcohol and hydroxyapatite nanocarriers composite microspheres. Alginate and polyvinyl alcohol composite microspheres are crosslinked by calcium and freeze-thawing technique. Using the freeze thawing process for polyvinyl alcohol crosslinking, in addition to alginate crosslinking, improved hydrogel swelling behavior and enhanced drug loading and thus slowed drug release, drug loading increased with increasing PVA percentage from ... 

The occurrence of the COVID-19 pandemic and the subsequent rising demand for purchasing alcohol-based sanitizers led to a remarkable prosperity in supplying these hygiene products. Hence, the development of a straightforward and efficient analytical strategy for discrimination of antiseptic alcohols including methanol, ethanol and isopropanol is of great importance. By exploiting the alcohol-sensitive membranes of probiotic bacteria, this research aims to develop a colorimetric sensor array for discriminating methanol, ethanol and isopropanol. In this design, the aggregation of citrate-capped gold nanoparticles (Au NPs) on the thiol-modified surface of two probiotic bacteria, including... 

New methods of cancer treatment are always the attention of researchers all over the world, among which the photothermal treatment method is of particular importance. In addition to being easy, this treatment method has the least invasiveness. Studies have shown that combining this method with other methods such as chemotherapy not only can be very effective in destroying tumor tissue, but can significantly reduce the side effects of chemotherapy drugs.In order to apply the photothermal treatment method, an effective photothermal agent is needed. Molybdenum disulfide nanosheets have performed successfully in this field, which have been of great interest, due to their high efficiency in... 

Cartilage is a connective tissue, whose most important role in the body is to create a surface with a low friction coefficient in order to allow bones to slide on each other without direct contact to transfer loads. Articular cartilage is always under a harsh biomechanical environment and lacks blood, lymphatic and nerve vessels. As a result, it limits the capacity of this tissue to improve and restore itself. According to experimental efforts, cartilage cannot be regenerated spontaneously without the support of healthy subchondral bone. In recent years, the implantation of tissue engineering scaffolds has been considered as an effective strategy for the treatment of osteochondral damage.... 

Simultaneous detection of pH and glucose levels in sweat is a promising tool for early skin disease detection and diabetes diagnosis. Hydrogels have attracted a lot of attention in the field of wearable biosensors due to sweat absorption capability, biocompatibility, and the ability to store enzymes and reagents in their cavities. In this research, we have presented an innovative wearable colorimetric biosensor based on polyvinyl alcohol (PVA) hydrogel, which can simultaneously measure pH level (in the range of 3-9) and glucose concentration (in the range of 0.025-0.5 mM) of sweat with the help of machine learning (ML). This wearable sensor consists of two main parts: sensors and a patch, in...