Sharif Digital Repository

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... 

Rehabilitation usually involves physical therapy, occupational therapy and counseling for the patient's morale to help to restore his power and performance. Considering the economic outlook and the costs of rehabilitation methods and due to the increasing prevalence of stroke and the need to recover the patients in a short period, only the use of robotic systems opens the door to the medical community. Since a large rehabilitation robots designed and built and each been used according to their advantages and shortcomings. In this project, the major shortcomings examined and exoskeleton designed on two major features including portability and covering shoulder workspace. Shoulder movement was... 

Silica nanoparticles is one of the most important mineral particles. In this study, Sodium silicate, Sulfuric acid and Sodium aluminate is used in order to synthesis of the modified Silica nanoparticles. The effects of temperature, reaction time and the molar ratio of regents were tested and optimized. Synthesized nanoparticles were characterized by use of XRD, FT-IR and SEM techniques. The results show that by controlling the reaction conditions, nanoparticles with an average size of 26.2 nm is obtained. The increase of temperature and reaction time alters the structure of the particles of amorphous state to a crystalline needles. The particle surface modification process was performed by... 

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,... 

In this research, an adsorptive affinity membrane has been prepared based on the combination of the nanofiber structure’s intrinsic characteristic in the dye adsorption and its membrane filtration properties. Electrospinning method has been used to prepare chitosan/poly(vinyl alcohol) (PVA) nanofibers. The morphology and properties of the prepared nanofibrous membranes were characterized using Fourier-transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FE-SEM), image processing, atomic force microscopy (AFM), and thermogravimetric analysis (TGA). Also, the major drawback of electrospun nanofibrous membranes (ENMs) is their low mechanical resistance. So,... 

In past two decades, the direction of oil and gas exploration has moved towards deep water drilling. The pressure and temperature in these zones are ideal for gas hydrate formation that can cause serious and sometimes uncontrollable issues during drilling operations. Gas hydrate formation while drilling can cause problems such as occurrence of kick and blowout, plug chock and kill line, and change in rheology of drilling mud. On the other hand, nowadays, nanotechnology has created an evolution in engineering sciences and because of the wide range of this science, drilling industry is affected like other industries. In the meantime, because of high yield, high stability and various methods of... 

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... 

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... 

Several studies based on anti- cancer, anti- metastatic and anti- tumor effects of curcumin have been reported . Besides these benefits, the therapeutic efficacy of curcumin is limited due to its poor aqueous solubility, extensive first-pass metabolism, inadequate tissue absorption and degradation at alkaline pH, which severely diminishes its bioavailability. In this project we seek to solve some of the problems with nanoscience to work more effectively. In the past decade, mesoporous silica nanoparticles (MSNs) have found widespread application as controlled drug delivery systems. Recent reports on the design of capped and gated MSN-based systems have shown promise in preventing premature... 

Three sizes of silica nanoparticles (160±7, 450±10 and 600±25) were sythetized via template-removing method. The synthetized nanoparticles were functionalized with N-(2-aminoethyl)-3-aminopropyl trimethoxy-silane (EDS) to provide a positive charge on the surface of nanoparticles. BET analysis showed that the average pore diameter, surface area and pore volume of nanoparticles were 2.3 nm, 769 m2.g-1 and 0.44 cm3.g-1, respectively. showed that the Amine-functionalized silica nanoparticles were used to enhance the application of alginate polymer for 3D encapsulation of mammalian cells. Incorporating of silica nanoparticles can be suitable for the bead integrity and attachement of mammalian... 

Ni/SiO2 nanoparticle composite coatings were prepared by electrophoretic deposition (EPD) and their hardness, wear and corrosion resistance were examined. Additionally, the morphology of the coatings was observed. In the first phase, the feasibility of coating with Scanning Electron Microscopy (SEM) as well as X-ray diffraction (XRD) and Energy Dispersive Spectra (EDS) techniques was evaluated. After finding the effect of concentration of nanoparticles on coating characteristics and the results of using SEM, optimum conditions for uniform coating, acceptable adhesion at 20V and concentrations of 10 g/L for Ni, 1.2 g/L for SiO2, and choosing NiCl2 as additive with a concentration of 0.2 g/L... 

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... 

This thesis is a research corresponding to Super-Hydrophobic condensation substrates with Nanometer texture. In this study, the foresaid surfaces are fabricated by two methods that are Nano-composite paint and Electrophoretic coating. As a summary for the first method (the Super-Hydrophobic Nano-composite paint), the hybrid coating contains two mineral and organic phases; The organic phase is a two-part clear-coat polyurethane and plays the role as a polymer matrix in Nano-composite structure. Silica Nano-particles are the mineral phase and the two phases of Nano-composite have made connection with silane compounds. Also, surface-modification in Nano-particles for giving hydrophobicity... 

Important features of the nanoparticles properties are their high superficial area and being able to reform their surface. In this study, the repairable property used to reform surface of silica nanoparticles (Those are used more frequently than other nanoparticles). Repairing of surface are doing to use nanoparticles as a surface-active material in enhanced oil recovery. Silane compounds with different chain length are used to create hydrophobic nanoparticles and PEG compounds are used to create hydrophilic nanoparticles. Also amphiphilic nanoparticles are created with a combination of both hydrophilic and hydrophobic compounds. To investigate the usefulness of nanofluids are made up of the... 

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;...