Sharif Digital Repository

Memristor is a modern circuit element that demonstrates resistance memory function and can have important applications in emerging memories and artificial synapses. Binary oxides and perovskite oxides are two major classes of materials that are promising for memory resistances. Among the binary oxides, TiO2, and among the perovskite oxides, SrTiO3 (STO), are particularly promising in research on electrical resistance switching. In this thesis, by using two deposition techniques of sputtering and pulsed laser deposition (PLD), we have constructed single-layer and multi-layer memristor devices based on these two materials. Two general mechanisms control the behavior of memristors: bulk-control... 

Biodegradable implants are new generation of implants that require no secondary surgery for their removal. Mg exhibits a great potential to be used as the biodegradable implant. However, mechanical properties and biocorrosion behavior of Mg are not suitable for being used as biodegradable implants. In this study, effects of Sr additions, heat treatments (T4 and T6), and multi-directional forging on the microstructural evolution, mechanical properties and biocorrosion behavior of Mg-4Zn-xSr alloys, and also the effect of hydrothermal coating on the biocorrosion behavior of Mg-4Zn-0.3Sr alloy were investigated. Potentiodynamic polarization and hydrogen evolution methods were used to... 

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... 

Considering the operation of the current nuclear reactors and the country's policy to achieve 10,000 megawatts of nuclear power in the horizon of 1420, in the coming years we will face a huge amount of radioactive waste, the majority of which is waste with low and intermediate levels of radioactivity (LILW). A large percentage of the radioactive waste production in Bushehr power plant is concentrated waste with a low and intermediate level of radioactivity (about 70% by volume). Due to the commisining of phase 2 and 3 of Bushehr power plant in the coming years and the increase in the radioactive waste production, proper planning should be done for waste management in order to reduce the... 

In the upcoming research, with the aim of bone tissue engineering and achieving a new structure, a scaffold based on polyhema (PHEMA) and gelatin (Gel), which are biocompatible polymers for bone tissue, was made and evaluated. Also, in order to improve the bioactivity and mechanical properties, bioactive glass alone (BG45S5) or together with strontium (BG-Sr) was used in the scaffold structure. and chemical by conducting FTIR, XRD, SEM, mechanical strength, bioactivity measurement, contact angle, water absorption and degradation tests. Biological investigations were done using mesenchymal stem cells derived from human bone marrow and with the help of MTT evaluations and SEM photography. The...