Scientia Iranica
Volume:21 Issue: 6, 2014

In the present paper, we use a gold electrode modified by 2-(3, 4-dihydroxy phenyl) benzothiazole self-assembled monolayer (DHT-SAM) for the determination of epinephrine (EP) and uric acid (UA). Initially, DHT-SAM was characterized by different techniques. CV was used to investigate the redox properties of the modified electrode at various scan rates. The apparent charge transfer rate constant, ks and transfer coefficient (α) were calculated. Next, electro oxidation of epinephrine (EP) and uric acid (UA) on a gold electrode modified by a self-assembled monolayer of DHT mediated was investigated. At the optimum pH of 7.0, the oxidation of EP occurs at a potential about 200 mV less positive than that of an unmodified gold electrode. The values of transfer coefficients (α = 0.35), catalytic rate constant (k = 4.4 × 104 M-1s-1) and diffusion coefficient (D = 1.03 × 10-6cm2s-1) were calculated for EP, using electrochemical approaches. Differential pulse voltammetry (DPV) exhibited a linear dynamic range over the concentration range of 0.5–400.0 µM and a detection limit (3s) of 0.11 µM for EP in pH= 7. Finally, simultaneous determination of EP and UA at the modified electrode was described and used for the determination of EP in EP ampoule.

Nickel (Ni) doped tin oxide (Sn1-xNixO2 x=0.00, 0.02, 0.04, 0.06, 0.10, 0.20) thin films were deposited on glass substrates by a sol-gel method using an ethanol solution containing tin and nickel chloride. The structural and optical properties of Ni-doped SnO2 transparent semiconducting thin films were investigated. X-ray diffraction patterns showed that all samples have tetragonal phases. The morphology of the films showed that the films have good surface and are very dense. The grain size was calculated between 4.4 and 5.3nm by a transmission electron microscope. The electrical measurement showed that the resistivity increases as the Ni concentration increases. The optical properties of the films measured by UV-Vis showed that the films have transparency between 90% and 98%. The extinction coefficient is very small, and the refractive index is saturated at a wavelength >400 nm. The VSM results showed that all the samples are ferromagnetic, except for the lowest Ni dopant. Moreover, the original ferromagnetism can be explained by the bound magneton polaron (BMP) mechanism.

CuMS2 (M=Al, In, Fe) ternary compounds were synthesized via the facile polyol method in autoclave. Depending on the functional groups of solvent and surfactant, the structure of the nanocrystals can be controlled in the form of wurtzite or chalcopyrite. The chalcopyrite structure was obtained when the precursors solved in the mixture of diethylene glycol, polyethylene glycol 600 and ammonium hydroxide. When the solvent was replaced by ethylene diamine the wurtzite was obtained along with chalcopyrite (polytypism). The products were characterized by X-Ray diffraction (XRD) for analysis of structural properties, transmission electron microscopy (TEM) for studying of morphological properties, absorbance spectrophotometer (UV-Vis-NIR) and photoluminescence (PL) for analysis of optical properties. The different optical band gap for CuAlS2 (3.48eV), CuInS2 (1.51eV) and CuFeS2 (0.65eV) could be utilized for absorbance material in a whole range of sunlight wavelength. The possible formation mechanism was also discussed.

Low temperature processing of dye-sensitized solar cells (DSCs) is essential to enable commercialization with low cost plastic substrates and diminish the overall manufacturing cost. We report a low temperature processing route for photoanodes where thin ZnO nanoshell is deposited by atomic layer deposition at 150°C, on a mesoporous insulating template. We found that a 6 nm ZnO overlayer on a 3 µm mesoporous nanoparticle Al2O3 template shows a power conversion efficiency of 4.3 % with the standard organic sensitizer (coded Y123) and cobalt bipyridine redox mediator.

in this work the non local conductance (NLC) in the topological insulator ferromagnetic / superconductor / insulator / superconductor / ferromagnetic (F/S/I/S/F) structure is numerically investigated. The insulator region is a thin barrier and the magnetization of the ferromagnetic regions is considered as perpendicular to the surface of the topological insulator. Our results indicate when the magnetization vectors in the ferromagnetic regions are parallel (anti-parallel) the crossed Andreev reflection (electron elastic Cotunneling) process does not occur and also the NLC in terms of barrier strength shows a periodic behaviour. In addition, the NLC as a function of the barrier strength shows an on-off quantum switching properties. We find also that this junction can be used as a quantum entangler devise which is of high important in quantum computing.

An innovative TiO2/iron oxide/Ag nanoparticles with crystal size of about 25 nm was synthesized on polyester fabric to achieve different multi-features including super-paramagnetism, antibacterial and enhanced self-cleaning properties. Treatment temperature was varied at boil and 130°C, creating TiO2/magnetite/silver and TiO2/hematite/silver nanoparticles, respectively. The alkaline hydrolysis of polyester surface was accompanied by the nanoparticles synthesis, which forms more active surface for nanoparticles adsorption. The co-operation of iron oxide and silver nanoparticles on TiO2 surface synergistically improved the self-cleaning efficiency of titanium dioxide nanoparticles by separation of electron-hole pairs, three and four times for fabrics treated with TiO2/Fe3O4/silver and TiO2/α-Fe2O3/silver nanoparticles, respectively comparing with their corresponding control samples. Moreover, both TiO2/iron oxide/Ag nanoparticles treated samples indicated antibacterial efficiency of ≥99.99% against Staphylococcus aureus bacteria. Findings suggested that the developed magneto, bio and photo activities could be idealized depending on the end use of the treated fabrics through incorporation of different iron oxides in the prepared nanoparticles; magnetite providing the highest saturation magnetization and hematite the best self-cleaning towards degradation of Methylene Blue under sunlight irradiation.

In the present study, green synthesis of silver nanoparticles (AgNPs) was attempted using ower extract of Cassia roxburghii belonging to the family Fabaceae. Synergistic antibacterial activity of AgNPs with 15 commercial antibiotics was evaluated gainst 2 Gram-positive bacteria (S. aureus and B. cereus), 2 Gram-negative bacteria (E. coli and P. aeruginosa) and 4 fungi, which included one clinical isolate (C. glabrata, C. albicans, C. neoformans and 1 Candida sp., clinical isolate). Characterization of synthesized AgNPs was done by various spectral analysis, including UV-Vis spectroscopy, Fourier transform infrared spectroscopy, X-ray di raction, Transmission electron microscopy and zeta potential. The UV-Vis spectrum of AgNPs showed absorption maxima at 348 nm. TEM analysis revealed that AgNPs were ower-like and/or triangular in shape, ranging from 5 to 360 nm in size. The antibacterial activity of AgNPs with antibiotics was better than antibiotics alone against the tested bacterial strains. The highest enhancing e ects were observed for 7 antibiotics against S. aureus. This is a simple, economic, ecofriendly, nontoxic, quick and green synthesis of AgNPs using an aqueous ower extract of Cassia roxburghii. It can be de nitely used in cosmetics, foods and medical applications.

We propose an innovative design for metallic slit-groove nanostructure to increase the propagation intensity of a unidirectional surface plasmon polariton (SPP) light beam. Our idea is based on the combination of the concept of unidirectional plasmonic wave propagation in a metallic slit-groove nanostructure and the well- known hybrid modes of a hybrid metal-dielectric waveguide. Our results demonstrate that the hybrid structure results in up to 5 times enhancement in the SPP beam intensity relative to the conventional design of slit-groove nanostructure. This new design of SPP based nano source can be applied in many applications including nano photonic devices.