JOURNAL OF NANOSTRUCTURES
Year:2016 | Volume:6 | Issue:4|Papers Count:10

In this study, effects of multi walled carbon nanotubes and temperature on rheological behavior of engine oil (10W40) have been examined. For this purpose, the experiments were carried out in the temperature range of 5-55oC for several suspensions with solid volume fractions of 0.025%, 0.05%, 0.1%, 0.25%, 0.5% and 0.75%. The viscosity of all samples was measured in the shear rate range of 666s-1 to 13333 s-1 at all temperatures considered. The viscosity measurements at different shear rates revealed that all nanofluid samples showed non-Newtonian behavior. The results also revealed that for an increase in the solid volume fraction from 0 to 0.75%, the viscosity increases to 2.5 times. The consistency and the power law index were attained by curve-fitting method for all samples and temperatures. Furthermore, the curve-fitting results revealed that the consistency index and apparent viscosity of nanofluid increases with augmenting the solid volume fraction and diminishes with growing temperature.

Nanomagnetic MgFe2O4 is an active, stable, and reusable catalyst for the oxidation of alcohols. The oxidation of various primary and secondary alcohols has been examined and related corresponding products were obtained in good yields. The reactions were carried out in the presence of water as solvent and oxone (at room temperature) or H2O2 (at 60 oC) as an oxidant. The catalyst was investigated by X-ray powder diffraction, scanning electron microscope, inductively coupled plasma and infrared techniques. Furthermore, the catalyst could be easily recovered and reused up to 7 runs without loss of activity.

In present work, we have calculated the electronic properties including density of states and electron density for GaN, InN and Inx Ga1-x N in wurtzite phase for x=0.5. The study is based on density functional theory with full potential linearized augmented plane wave method by generalized gradient approximation for calculating electronic properties. In this report we concluded that Inx Ga1-x N band gap, which would be decreased with increasing in concentration and GaN is very sensitive on in content.

At the first step CuFe2O4 nanoparticles were synthesized by a fast and facile microwave method. The obtained nanoparticles and modified carbon nano tubes were added to poly styrene matrix. The products were characterized through Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. Vibrating sample magnetometer shows nanoparticles exhibit ferromagnetic behavior. The influence of CuFe2O4 nanostructures on the flame retardancy of the polystyrene (PS) matrix was studied using UL-94 analysis. The enhancement of thermal stability and flame retardancy of nano composites is due to magnetic CuFe2O4 barrier against flame, oxygen and evaporation.

The present work focuses on preparation and characterization of erythromycin loaded gelatin nanoparticles through nanoprecipitation method. The procedure consists of the addition of the aqueous gelatin solution to the non-solvent phase containing Lutherol F127. Three different measures of cross-linker and polymer concentration were also examined, and the optimum concentration was found. The morphology of gelatin nanoparticles was characterized by field emission scanning electron microscope. It was shown that the optimal morphology can be achieved at the concentration of 1.25 wt % of gelatin in aqueous phase by addition of 20 mL of glutaraldehyde 5%, as the crosslinking agent. Nanoparticle wet size determination was carried out using a dynamic light scattering system and found to be approximately 100 nm. Furthermore, Erythromycin release studies proved the suitability of these particles as a drug delivery system, at least in the studied 72 hours interval. As suggested by related measurements, these nanoparticles are good candidates for antibacterial agent release in any possible related application.

The combination of graphene and nickel oxide nanoparticles yields nanostructured electrochemical sensor formed a novel kind of structurally uniform and electrocatalytic activity material. In cyclic voltammetry studies, in the presence of epinephrine, nickel oxide / graphene composite modified electrode shows a significantly higher current response for epinephrine oxidation. Based on differential pulse voltammetry technique, the oxidation of epinephrine exhibited the dynamic range between 1.0–1800.0 mM and the detection limit was 0.42 mM. Finally, the resulting sensor was used to detect epinephrine and AC simultaneously in human serum samples.

The perovskite-structured La2CuO4 nanoparticles have been synthesized via an ultrasonic-assisted co-precipitation route using octanoic acid as organic surfactant, and the phase composition, morphology, lattice parameters and size of nanoparticles are characterized through Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and Transmission electron microscopy. Magnetic measurements are carried out by a vibrating sample magnetometer on the resultant powders at room temperature. Vibrating sample magnetometer shows nanoparticles exhibit ferromagnetic behavior. The synthesized perovskite yields comparatively pure crystalline phase of La2CuO4 nanoparticles. These nanoparticles are used as an efficient and effective catalyst for the oxidation of aldehydes to corresponding carboxylic acids, and this oxidation protocol works well for various aldehydes. Also the La2CuO4 nanoparticles can be recycled for several times without obvious loss of activity. The results show the utilization of these nano catalysts have several advantages, viz. high yields, clean reaction, short reaction times and recyclability of the catalyst.

Nickel doped TiO2 nano particles (1% w/w) were prepared and immobilized on NaX zeolite and after characterization by X-ray diffraction and scanning electron microscopy used as photo catalyts for degradation of orange G. The X-ray diffraction patterns show that the supported TiO2 are crystallized in anatase form and the intensity of the zeolite peaks decreases with the increase of TiO2 loading. Scanning electron micrographs of synthesized samples show that nano size titanium dioxide particles are accumulated on the surface of the zeolite. These materials are applied as photo catalysts for the degradation of orange G in aqueous solution by means of ultraviolet light irradiation at room temperature. The effect of solution pH, ultraviolet irradiation time and catalyst in degradation of orange G was investigated. The results show that nickel doped TiO2/NaX zeolite as a photo catalyst in degradation of orange G in acidic solution is superior to the Ni/TiO2 nano composite and also undoped nano size titanium dioxide particles.

A new recoverable molybdenum nanocatalyst was prepared by immobilization of a Schiff base ligand on the surface of silica coated magnetite nanoparticles (Fe3O4@SiO2) through condensation reaction between 3-aminopropyl triethoxysilane and 2-hydroxy1-naphthaldehyde and succeeding reaction with dioxomolybdenum (VI) acetylacetonate (MoO2 (acac) 2). The synthesized catalyst was characterized by inductively coupled plasma, thermogravimetric analysis, scanning electron microscopy, vibrating sample magnetometry, Energy-dispersive X-ray, Fourier transform infrared and X-raydiffraction spectroscopy. Catalytic performance of the synthesized nanocatalyst was investigated for the preparation of 2-amino-4H-benzo [h] chromenes. The compounds were prepared high yield through one-pot, three-component reaction of 1-naphthol, various of aldehydes and malonitrile in the presence of nanocatalyst, Fe3O4@SiO2@Mo-Schiff base, under solvent-free conditions. The benefits of this protocol are short reaction time, simple work-up procedure, high yields and use of the concept of green chemistry. The magnetic nanocatalyst could be separated easily from the reaction media using an external magnetic field and reused in subsequent catalytic runs without significant deterioration of its activity.

A new natural and environmental friendly wound dressing was introduced for the first time that was prepared by electrospinning method. This new wound dressing has chitosan base, and poly (ethylene oxide) was added as co-spinning agent to improve spinnability of chitosan. Moreover, thyme extract as a natural antibacterial additive was introduced in the as electrospun nanofibers scaffold in order to increase those wound healing properties. Some parameters of electrospinning such as feed rate, nozzle-collector distance, voltage and content of thyme extract in nanofiber structure were studied and optimized. The average diameters of prepared nanofibers was determined by "Clemex vision professional edition" software. Morphology and structure of electrospun nanofibers was studied with use of scaning electorn microscopy and Fourier transform infrared spectroscopy spectroscopy. The results showed that the antibacterial activity of nanofibers increased as the amount of thyme extract was increased, thus a chitosan/PEO containing 3% of thyme extract was selected as the best prepared nanofiber for wound dressing preparation. Chitosan/PEO/thyme nanofiber showed high stability in the buffer and good antibacterial activity against three understudy bacteria including Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus.