Scientia Iranica
Volume:22 Issue: 6, 2015

Well-dispersed PtSn/C and PtSnO2/C catalysts with anatomic ratio of Pt:Sn (3:1) were deposited onto carbon using a modified alcohol-reduction process for electrochemical oxidation of ethanol. These materials were characterized using energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). An electrochemical study in theethanol and acid medium showed that the PtSnO2/C catalyst had a better performance compared with the PtSn/C and Pt/C catalysts. The CV analysis indicated that the presence of SnO2 increased the sensitivity of the catalyst to oxidation of acetaldehyde because of its low onset potential for the electrooxidation of adsorbed ethanol and acetaldehyde compared to PtSn/C and Pt/C. Since the activation of C-C bond breaking results in the generation of higher current density (mass activity) at higher potentials, the PtSnO2/C catalyst has been found favourable for the overall oxidation of ethanol.

The present study reports a simple, rapid, easy, eco-friendly and cost efficient method for green synthesis of silver nanoparticles (AgNPs)using pollen extract of rose flower as reducer and stabilizer. AgNPs synthesis was performed at room temperature in solutions by reduction rapidly takes place for 15 min and the synthesized AgNPs were stable for a long time. Moreover highlights for this method are avoiding the utilization of toxic organic solvents and using nontoxic water as the solvent for pollen extract from rose flower. Microscopy and UV–Vis spectroscopy confirmed the formation of nanoparticles as well as the colloid of silver samples. Surface plasmon resonance (SPR) peaks in UV–Vis spectra were observed at 427 nm indicated the formation of poly dispersive AgNPs using pollen of rose flower. The synthesized AgNPs were mostly spherical in shape with an average size of 12 nm. It shows the significant antibacterial efficacy against Staphylococcus aureus (S. aureus),Escherichia coli (E. coli), Bacillus cereus (B. cereus) and Enterococcus faecalis (E. faecalis)by disk diffusion method using Mueller-Hinton Agar. From the results, it is suggested that green synthesized AgNPs could be used effectively in cosmetics, foods and medical applications.

Titanium granules can be used as bone graft substitute in the field of orthopaedic and periodontal surgery but their bone bonding ability needs to be promoted. Nanostructured materials have shown to enhance bioactivity and overall bioperformance of biomaterials. In the present study, the effects of time and voltage of anodic oxidation process is investigated in order to forms TiO2 nanostructures with optimized morphology on the surface of porous titanium granules. The anodized granules are subsequently heat treated at 450 C for 1 h. MG63 osteoblast like cell is used to evaluate cell attachment and viability on the surfaces of anodized and annealed granules using scanning electron microscopy (SEM) and dimethylthiazol-diphenyl tetrazolium bromide (MTT) assay, respectively. The results of anodizing process show TiO2 nanostructures are constructed at the voltage of 60 V for 3 h. The X-ray diffraction results show improved crystallinity of TiO2 nanostructures on the surface of annealed anodized granule surfaces after the annealing process. Cell culture experiments show improved cell spreading and viability on the surface of annealed anodized granules compared to anodized sample. It is concluded that annealed anodized granules could have a potential for orthopaedic and periodontal applications as bone graft substitutes.

In this paper, the electronic transmission of an electrode-benzene-electrode system using equilibrium Green''s and rst order perturbation theory is investigated. The e ect of di erent values of perturbation on substitution of the electrode into the di erent atomic sites is presented. The range of the perturbation values are from zero to the energy gap between the highest occupied and the lowest unoccupied molecular orbitals. Our calculations indicate that increasing the perturbation value does not greatly a ect the case where the connection is with maximum transmission (para), whereas, doing likewise for the case of minimum transmission (ortho), we nd a much more sensitive transmission response.

Electrospinning of polyvinyl alcohol (PVA) solution followed by a 24 h iodination treatment for stabilization of PVA for carbonization yields carbon nano bers. When cadmium acetate dehydrate [(CH3COO)2Cd.2H2O] salt is added to the PVA spinning solution, the carbon nano bers derived from a iodinated PVA and cadmium/PVA nano bers precursor could increase the carbon yield to 30% and 34% after carbonization which is much higher than the yield (< 1%) for untreated spinning solution. Several techniques, such as TGA, FE-SEM, XRD, Raman spectroscopy, and HR-TEM, are utilized for characterization of carbon nano bers. The size of crystalline nano bers is in the range of 100-350 nm.

The present investigation is mainly focused on the problem of heat transfer of an incompressible heat generating/ absorbing magneto hydrodynamic non-Darcy flow of a water based nanofluid with different metallic and non- metallic nanoparticles over a stretching/shrinking sheet embedded in a thermally stratified porous medium in the presence of thermal radiation with second order slip flow model. To analyze the problem elaborately, numerical simulations are carried out. Moreover, an analytical treatment is performed for a special case. The results for nanofluid velocity, temperature, skin friction coefficient and reduced Nusselt number are discussed. It is found that a unique solution exists in stretching sheet and dual solutions for shrinking sheet which are classified as upper and lower branch solutions. The lower branch solution does not exist when the magnetic field and porous medium are high for a special case. Some of the notable results of nanoparticle volume fraction, non-Darcy, slip and stratification parameters are brought out which may applicable for future research works. To validate the present code the present results are compared with benchmark solutions and observed an excellent agreement.