مجله مواد و فناوری های پیشرفته
سال پنجم شماره 2 (تابستان 1395)

Synthesis of HAp is of considerable interest because of its similariity to mineral component of bone. It has good biocompatibility and bioactivity for bone tissue therapy. In this project, we looked at the effect of calcium substitution with cobalt divalent cation on the structure and magnetic property of HAp. Cobalt- doped HAp nanoparticles was synthesized via hydrothermal condition. First, Calcium nitrate and Cobalt nitrate was mixed. Then di- ammonium hydrogen phosphate was added drop by drop and finally Co-HAp was precipitated from the solution. The precipitate was heated at 200C under hydrothermal condition. XRD pattern analysis verified the substitution of cobalt in HAp structure by showing a shift in the peak positions in the pattern. Furthermore, broadening and reduction in the peak intensities of the peaks with cobalt substitution was also observed in this study. The presence of functional groups related to HAp structure (PO43-, OH-) were confirmed by FTIR analysis. The size and morphology of nanoparticle HAp particles were evaluated by FESEM analysis. Calcium substitution with cobalt induced size reduction and morphology change in HAp particles. VSM analysis was carried out to investigate the magnetization of HAp and Co-HAp nanoparticles. The results showed that cobalt substituted nanoparticles displayed paramagnetic properties, as opposed to the diamagnetism of pure HAp. Cobalt doped HAp, a biomaterial with magnetic properties, could be used in a variety of biomedical applications, including magnetic imaging, drug delivery and hyperthermia based cancer treatment.

In this research, electrochemical deposition of alumina-titania nanoparticles in thin-film forms and in different alcoholic environments such as ethanol, butanol and isopropanol on Api5-GrB steel substrates was evaluated. Different voltages were applied to the coating, also chronoamperometry method was used in order to investigation of nucleation mechanism and quality of the coatings surface. Alumina-Titania nanoparticles, different alcoholic electrolytes (ethanol, butanol and isopropanol), dispersant particles (iodine) and Api5-GrB steel substrates were used as consuming materials. In the coating weight measurement test showed that the coatings weight increases with increasing voltage. With applying 30, 40 voltages, the maximum coverage was created in presence of butanol suspension but by increasing the voltage, the maximum cover was made in the presence of ethanol suspension.

In the present work the Al2O3 content (0, 5, 10, 15 wt%) and annealing effect on the microstructural properties of Al-10Mg alloy was investigated.The milling process of the composites was carried out under argon atmosphere. Milled powders were pressed and annealed at 400 C for 45 min. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) devices were applied to microstructural and phase transformations studies of the prepared composites. The results show that the mechanical alloying process accelerates due to alumina content increment and it results in the formation of a steady-state condition. The alumina increasing cause to decrement of the matrix grain size from 32 to about 15 ?m before annealing and it prevent the abnormal grain growth after annealing. Increasing in the grain size occurs after annealing process due to the particles agglomeration. Also, grain growth, lattice strain decrement and lattice parameter decrement were observed as a result of recrystallization. The microstructural did not show significant changes for the samples with high quantity of alumina. Formation of Al3Mg2 phase after annealing, observed at the X-ray patterns, can prevent from further grain growth.

In this paper, SnO2/ZnO core - shell nanocomposites were synthesized via sonochemical processing. To achieve this, ZnO nanoparticles were prepared by ultrasonic method. In the next stage, the core-shell nanocomposites in the presence of ZnO particles (prepared in the previous step) and adding precursor SnCl4.5H2O was prepared by ultrasonic. After synthesizing the nanocomposites, their properties were studied by XRD, TG-DTA and TEM analyses. The synthesized SnO2/ZnO core - shell nanocomposites have amorphous structure that can be changed to crystalline structure after calcination at 650 C for 1 hour. Also, the gas sensing characteristics of SnO2/ZnO core- shell nanocomposite was studied. For evaluating the gas sensing properties, the synthesized particles were prepared by pressing the powder into pills and gas sensing test was performed with respect to the various gases such as methanol, CO, and H2. Due to the unique properties of the core - shell semiconductor particles in the mechanism of charge separation, the gas sensing properties of core - shell particles are higher than those of pure oxides.

In the present research, polyaniline (PANI) was used as a conducting polymer and carboxymethyl cellulose (CMC) also used as a biopolymer because of its antibacterial property and also suitable biocompatibility. TiO2 nanoparticles also was considered as a reinforcing agent to prepare PANI-CMC-TiO2 nanocomposite with different weight rates. The obtained results from review of antibacterial property showed that nanocomposites with optimal weight percentages have the most antibacterial effects on both two different types of Gram-positive and Gram-negative bacteria. The obtained results from TGA tests also indicate promotion of thermal stability of nanocomposite in respect to pure CMC. Also, the FTIR and SEM techniques were used to characterize the composition and structure of nanocomposite.

In this paper, the TCO/a-Si:H(n)/c-Si:H(i)/c-Si(p)/c-Si:H(i)/BSF/TCO/Ag Bifacial HIT (Heterojunction with intrinsic thin-layer) solar cells was analyzed and designed by AFORS-HET Software. We consider the emitter and BSF layers thickness is constant, then the influences of wafer and intrinsic layer thickness, Densities of interface defects (Dit), and using three different types BSF layer and compare the output from these three types of structure with structure without the BSF layer, Solar cell efficiency is studied And the best available mode for optimum cell is selected. It is noteworthy that according to the simulation results, use a layer of intrinsic microcrystalline layer of a-Si: H (n) / c-Si (p) and c-Si (p) / a-Si: H (p ) Density of states and combined carriers reduce, Increase the efficiency of silicon solar cells is the numerical value of 28%.

The objective of this study is to assess the uptake of Cd2, from aqueous solution by nano hydroxyapatite granular in fixed bed reactor system was investigated. The study also investigates the effects of parameters such as initial concentration ion, bed depth, and flow rate. The breakthrough time and exhaustion time decreased with increasing initial Cd2 concentration, decreasing bed depth and increasing flow rate. The Thomas model and Yoon-Nelson model were applied to the experimental results for measurement adsorption capacity. Thomas and Yoon-Nelson model predictions were in good agreement with the experimental data. Adsorption capacity and time required for 50% adsorbate breakthrough obtained for initial concentrations of 300, 400 and 500 mg/L of divalent cadmium ions are 2425.95, 2679.14, 4265.51 mg/g of adsorbent, and 18.33, 15.18 and 19.33 min, respectively.

In this paper, the effect of Pd decorated Carbon nanotube system for Carbon monoxide gas sensor applications was studied. Various positions of Pd atom and CO molecule have been considered and investigated using ab initio atomic simulator software (Siesta and Quantumwise (to obtain the most appropriate structure for enhancing the sensitivity of Carbon nanotubes. According to the simulation results, the most stable configuration of Pd atom and CO molecule are obtained while Pd atoms stand parallel to the CNT with no carbon vacancy on and CO molecule approaches the Carbon nanotube with its Carbon atom. Results indicate that the obtained structure can be considered as an interesting candidate for gas sensing devices.