Sharif Digital Repository

The purpose of this work is evaluating the effect of ultra small superparamagnetic iron oxide nanoparticles (USPIONs) coatings on encapsulation efficiency in liposomes and cellular cytotoxicity assay. Moreover, we assessed the effects of surface engineering on the relaxivity of magnetoliposome nanoparticles in order to create a targeted reagent for the intelligent diagnosis of cancers by MRI. For estimating the effect of nanoparticle coatings on encapsulation, several kinds of USPIONs coated by dextran, PEG5000 and citrate were used. All kinds of samples are monodispersed and below 100 ± 10 nm and the coatings of USPIONs have no significant effect on magnetoliposome diameter. The coating of... 

Surface coverage as one of the most effective parameters of shot peening process has substantial influence on the functionality of the peened component. The aim of this study is to investigate the effects of surface coverage increase on the properties of treated specimens experimentally before and after re-shot peening. Different shot peening treatments from conventional to severe; were performed on the AISI 1045 steel. Microstructural observations and XRD measurements were applied to characterize the circumstance of microstructure changes. In order to investigate the mechanical properties, microhardness profiles were achieved, surface roughness was evaluated and the residual stresses... 

Copper-graphite composites which have low friction coefficient can be used as bearing materials in lieu of materials containing lead which cause environmental problems. So far, some methods such as powder metallurgy and centrifugal casting have been employed to produce these composites. In this study, friction stir processing (FSP) was used to produce copper-graphite surface composites. Five tools with different pin profile were employed in order to achieve a comprehensive dispersion. Results show that the tool with triangular pin gives rise to a better dispersion of graphite particles. Furthermore, four copper-graphite composites containing different graphite content were prepared using... 

Solution-processed quantum dots (QDs) have attracted significant attention for the low-cost fabrication of optoelectronic devices. Here, we synthesized PbS QDs via hot injection method and passivated the trap states by using short thiols and dopant elements for photovoltaic application. In order to study the effect of dopants on photovoltaic application, PbS QDs were doped by using three different cations: Cadmium, Calcium, and Zinc. We utilized Time resolvel Photoluminescence measurement to study the carriers lifetime for different samples and found that the carriers life time increases ∼80% by using Cd as a dopant compared with undoped sample. In addition, the results of J-V measurement... 

Interfacial studies and band alignment engineering on the electron transport layer (ETL) play a key role for fabrication of high-performance perovskite solar cells (PSCs). Here, an amorphous layer of SnO2 (a-SnO2) between the TiO2 ETL and the perovskite absorber is inserted and the charge transport properties of the device are studied. The double-layer structure of TiO2 compact layer (c-TiO2) and a-SnO2 ETL leads to modification of interface energetics, resulting in improved charge collection and decreased carrier recombination in PSCs. The optimized device based on a-SnO2/c-TiO2 ETL shows a maximum power conversion efficiency (PCE) of 21.4% as compared to 19.33% for c-TiO2 based device....