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silica
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Synthesis of Mesoporous Silica-Magnetite Nanocopmposite for Biological Applications
, M.Sc. Thesis Sharif University of Technology ; Madaah Hosseini, Hamid Reza (Supervisor)
Abstract
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...
Development of Polymerization Method to Produce Spherical Polymer Particles with Nanoscale Porosity in Packed Beds
, M.Sc. Thesis Sharif University of Technology ; Shojaei, Akbar (Supervisor) ; Abd Khodaei, Mohammad Jafar (Supervisor) ; Nematollah Zadeh, Ali (Co-Advisor)
Abstract
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...
Preparation of Polyelectrolyte-Coated Magnetic Silica Nanocomposite Particles and Investigation of their Application for Enzyme Immobilization and Biodiesel Production
, Ph.D. Dissertation Sharif University of Technology ; Kazemeini, Mohammad (Supervisor) ; Arpanaei, Ayyoob (Supervisor) ; Singh, Gurvinder (Co-Advisor)
Abstract
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...
Preparation of Heterogeneous Catalysts by Immobilization of Molybdenum and Manganese-shiff Base Complexes into the Nanopores of Zeolite and SBA-15
, Ph.D. Dissertation Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
This thesisconsiders new fundamental approaches to yield heterogeneous catalysts in to three sections. The first section described the immobilization of the molybdenum-Schiff base complexes in pores of SBA-15 in two different methodologies depending on the actual structure of the complexes., (i) stepwise formation of the complex by initial covalent anchoring of one of the components and consecutive solid phase synthesis consisting of the condensation of the other components of the salen complex (iii) one-step complex immobilization by covalent binding through the ligand.Based on the first methodology, we report the preparation of ordered mesoporous silica SBA-15 containing a molybdenum...
Synthesis and Characterization of Smart Silica Nanocomposites via Reversible Addition−Fragmentation Chain-Transfer (RAFT)Polymerization
, M.Sc. Thesis Sharif University of Technology ; Pourjavadi, Ali (Supervisor)
Abstract
Photochromism is defined as a reversible transformation of a chemical species between two forms having different absorption spectra induced in one or both directions by photoirradiation. Numerous photochromic molecules were investigated such as spiropyrans (SP), spirooxazines (SO), fulgides, diarylethenes, and azobenzenes. Recently, spirooxazines have been attracted more attention due to their more sensitivity towards photo, pH, heat, pressure, solvent polarity, and high fatigue resistance. Spirooxazine moieties are one of the most popular photochromic groups that can be transformed from colorless closed ring form (SO from) to blue color open ring form by UV irradiation that so-called;...
Preparation of Magnetically Recyclable Silica Supported Oxovanadium Nanocatalyst and its Application in the Oxidation of Sulfides
, M.Sc. Thesis Sharif University of Technology ; Bagherzadeh, Mojtaba (Supervisor)
Abstract
Current study reports a state-of-the-art approach for synthesis of nanocatalyst based on Oxo-vanadium Schiff base complex which itself is, covalently, immobilized on core-shell magnetic nanoparticles of silica-modified magnetite (Fe3O4@SiO2) and the substantial potential it offers as heterogeneous catalyst in selective oxidation of sulfides.Synthesized materials and complexes in this project were characterized by means of modern spectral devices such as FT-IR, XRD and SEM.Unlike routine process of the preparation of heterogeneous catalysts that requires further modification of the core-shell nanoparticles with capping agents, here we have been capable of cutting some time-consuming steps...
Characterization of Mechanical Properties of Polymer Nanocomposites with Spherical Inhomogeneities
, M.Sc. Thesis Sharif University of Technology ; Naghdabadi, Reza (Supervisor) ; Bagheri, Reza (Supervisor)
Abstract
The improved properties of nanocomposites are not achievable with conventional composites. Scale effect is one the most important parameters in the physical and mechanical properties of polymeric nanocomposites. One of the physical phenomena, which can be related to the scale effect, is the very large interface between the nanoparticles and the polymeric matrices. Motional behavior and conformation of polymeric chains change near the nanoparticles surfaces. Due to high interface of the nanoparticles with the polymeric matrices the amount of these types of changes in the polymeric chains are so large that can change the physical and mechanical properties of polymeric nanocomposites. In this...
Immobilization of Pd Nanoparticles on Functionalized SBA-15 and a Robust Mesoporous Catalyst for Reduction and Oxidation Reactions and Synthesis of Tetrasubstituted Pyrroles Via Multicomponent Reactions
, M.Sc. Thesis Sharif University of Technology ; Matloubi Moghaddam, Firouz (Supervisor)
Abstract
In first part Mesoporous silica (SBA-15) was synthesized by template synthesis method and the surface of SBA-15 was functionalized with 3-glycidoxypropyltrimethoxysilane and 5-Phenyl-1H-tetrazole. Palladium nanoparticles were immobilized on the aforementioned mesoporous support. Characterization of catalyst regarding to its structure, morphology and other parameters was investigated by physiochemical analysis such as XRD, SEM, TEM, and TGA. This heterogeneous catalyst has high capability in reduction of nitrobenzenes and selective oxidation of primary alcohols which respectively gain aminoarenes and benzaldehydes in high yields. Reduction and oxidation reactions are done in water as a green...
α-Amylase Immobilization on Nanocomposite Magnetic Silica Particles and Characterization of the Prepared Nanobiocatalysts
, M.Sc. Thesis Sharif University of Technology ; Mashayekhan, Shohreh (Supervisor) ; Arpanaei, Ayyoob (Supervisor)
Abstract
Enzymes are widely used in industry, however, the expensive cost, low stability, and the limited activity in a certain range of temperature and pH, have limited the usage of such bio-catalists. In addition to increasing and preserving their activity under different conditions, the enzyme immobilization can improve its stability in different pH, temperature values and increase its thermostability, storage stability and the possibility of their recycling. Meanwhile, utilizing the super-magnetic systems could be very helpful as well. For instance, separation of the the magnetic nano-particles like Fe3O4 from reaction system using an external magnetic field is easily possible. In this study,...
The Effect of Surfactant Agents on the Superhydrophobic Properties of Silica Coatings Synthesis by Sol-gel
, M.Sc. Thesis Sharif University of Technology ; Dolati, Abolghasem (Supervisor)
Abstract
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...
Fabrication of Superhydrophobic Surfaces to Decrease Pressure Drop through the Galvanized Pipe and Study about Feasibility of the Fabricated Surface to Use for Non-newtonian Fluid
, M.Sc. Thesis Sharif University of Technology ; Mousavi, Ali (Supervisor) ; Nouri boroojerdi, Ali (Supervisor)
Abstract
Nowdays, one of the most important concerns for scientists is increasing CO2 emmisions and global warming. To overcome this problem, a large number of studies have been carried out to improve energy system performance and reducing the overall energy consumption. One solution to this problem is using the superhydrophobic surfaces with contact angle larger than 150°.In this study, we try to reduce the pressure drop through the galvanized pipes. So, by reducing the pressure drop, power required for pumps can be reduced. To this end, two different coatings by silica nano-particles which were modified with first hydrophobic agent are used. In first coating which is named as PS coating, stearic...
Modification of Gd-DTPA Contrast Agent for Targeted Drug Delivery be Nano Delivery
, M.Sc. Thesis Sharif University of Technology ; Hamid Reza, Maddah Hosseini (Supervisor) ; Amo Abedini, Ghasem (Supervisor)
Abstract
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...
Investigation and Determination of Optimal Composition of Hydrogels and Nanoparticles for Proliferation of Mesenchymal Stem Cells in Alginate Beads
, M.Sc. Thesis Sharif University of Technology ; Yaghmaei, Soheila (Supervisor) ; Arpanaei, Ayyoob (Supervisor)
Abstract
The aim of this dissertation is to investigate and determine the optimal composition of hydrogels that can meet the needs of stem cells for the growth and proliferation of mesenchymal stem cells. In this research, firstly, unfunctionalized and functionalized mesoporous silica nanoparticles (with an average diameter of approximately 90 nm), were synthesized. Scanning electron microscopy and zeta potential measurement were utilized to study their morphology and surface charge. Then, graphene oxide nanosheets were synthesized. Field emission electron microscopy, zeta potential measurement and Fourier transform infrared spectrum analysis were used to examine their morphology, surface charge and...
Pore-Scale Investigation of the Effect of Fracture and Mineralogy on Formation Damage Caused by Drilling Fluid
, M.Sc. Thesis Sharif University of Technology ; Mahani, Hassan (Supervisor) ; Masihi, Mohsen (Supervisor)
Abstract
Formation damage in petroleum engineering is an important and fundamental phenomenon. During drilling operation, penetration of either the solid phase of drilling fluid or the base-fluid into the porous medium, reduces the permeability of the formation. While most experiments in the literature have focused on core-scale and beyond, there is lack of pore-scale studies. Moreover, presence of fractures has an undeniable effect on the extent of formation damage. Thus, the main objective of this dissertation is to investigate the effects of fractures on the severity of formation damage caused by the water-based drilling fluid and the mechanisms of formation damage at the pore scale, using glass...
The Study of Function of Lipase Biocatalyst Immobilized on Silica Nanoparticles Used for Biodiesel Production
,
M.Sc. Thesis
Sharif University of Technology
;
Kazemini, Mohammad
(Supervisor)
;
Arpanaei, Ayyoob
(Supervisor)
;
Tabandeh, Fatemeh
(Co-Advisor)
Abstract
Superparamagnetic core/shell nonporous (S1) and core/shell/shell mesoporous (S2 and S3) nanocomposite magnetite/silica particles with a magnetite cluster core of 130±30 nm, a nonporous silica shell of 90±10 nm thickness, and a mesoporous silica shell of 70±15 nm thickness were prepared thorough a simple method. Mesoporous particles were prepared with two BJH pore sizes (2.44 for S2 and 3.76 nm for S3 particles, respectively). The fabricated S1, S2 and S3 particles present high saturation magnetization values of 20, 13 and 17 emu/g, respectively. As a biological application, the lipase from Pseudomonas cepacia was successfully immobilized onto the amino-functionalized nanocomposite particles...
Non-Equilibrium Interfacial Behavior of Dynamic Interfaces in Presence of Surfactants and Nanoparticles; Experimental and Computational Fluid Dynamic Investigations
, Ph.D. Dissertation Sharif University of Technology ; Bastani, Dariush (Supervisor) ; Lotfi, Marzieh (Supervisor)
Abstract
The present study has been performed for better understanding about the dynamic behavior of fluid interfaces in presence of surfactants, nanoparticles and their interactions in gas-liquid dispersion systems. One of the main purposes of this work is to investigate the influence of surface modified nanoparticles on the dynamic behavior of gas-liquid interfaces. For this purpose, the rising bubble experiment was used as one of the most conventional procedures. Local velocities of bubbles rising in nanoparticle solutions were determined experimentally. Influences of silica nanoparticles which were modified via three approaches were investigated in these experiments. Heat treatment was applied to...
3D Stem Cell Culture and Differentiation Using Alginate Hydrogel Scaffolds Incorporated with Silicon-Based Nanoparticles
, Ph.D. Dissertation Sharif University of Technology ; Yaghmaei, Soheila (Supervisor) ; Arpanaei, Ayyoob (Co-Supervisor) ; Dolatshahi Pirouz, Alireza (Co-Supervisor)
Abstract
Bone is one of the most vital parts of the body for almost any functional movement. Due to its many involved diseases, traumas and injuries, bone maintenance and regeneration are of high importance. Engineering and design of complex tissues, with impeccable mimicry of the native ones, are always accounted as the solution to dysfunction of body organs due to aging, various diseases, etc. However, the inability to complete mimicry of the native tissue architecture and cell microenvironment are the main barriers to functional tissue regeneration. In this project, in order to design a suitable scaffold for bone regeneration, hydrogel nanocomposites with polysaccharide basis were developed by...
Characterization of Elecroless Ni-P-Al2O3-SiO2 Nano-composite Coating on Aluminium
, M.Sc. Thesis Sharif University of Technology ; Afshar, Abdollah (Supervisor) ; Dolati, Abolghasem (Supervisor)
Abstract
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...
Study of Micropollutants Adsorption from Water by Nanoporous Silica Aerogels
, M.Sc. Thesis Sharif University of Technology ; Bastani, Daruoosh (Supervisor) ; Bargozin, Hassan (Co-Advisor)
Abstract
Phenolic compounds are important environmental pollutants that the removal and separation of them from the water and industrial wastewater especially in the oil industry is essential before entering the environment. In the present study, the removal efficiency of the adsorbent silica aerogel 4-Chlorophenol and 4-Bromophenol as phenolic compounds from aqueous solution was surveyed. In this research, the effects of various factors such as contact time, pH, and initial concentration of the pollutant and the adsorbent on the adsorption were studied. It was observed that there is a large amount of adsorption in acidic pH and this amount increases by incrementing the concentration of the...
Experimental and Analytical Study of Warpage Reduction in Polypropylene 3d Printing by using Recycled Silica Nanoparticles
, M.Sc. Thesis Sharif University of Technology ; Pircheraghi, Gholamreza (Supervisor) ; Tavakoli, Rohollah (Supervisor)
Abstract
Creating sustainable development in today's society is essential, and one of the most important elements to achieve this is the phenomenon of recycling. Lead-acid batteries are one of the sources of environmental pollution, and their separators contain 50% recyclable silica nanoparticles. In this research, impurities in these separators were removed using two methods: washing with water and sandblasting. The purity of recycled nanoparticles was 85.5% in the first method and 98% in the second method. In addition to the importance of recycling, finding a suitable use for recycled materials is also critical. FDM 3D printing is a new method of producing parts, but polypropylene is not commonly...