Abstract: The electrochemical dynamics of a film of FeCo nanoparticles were studied on a glassy carbon electrode (GCE). The film was found to be electroactive in 1 M LiClO4 containing 1:1 v/v ethylene carbonate dimethyl carbonate electrolyte system. Cyclic voltammetric experiments revealed a diffusion-controlled electron transfer process on the GCE/FeCo electrode surface. Further interrogation on the electrochemical properties of the FeCo nanoelectrode in an oxygen saturated 1 M LiClO4 containing 1:1 v/v ethylene-carbonate-dimethyl carbonate revealed that the nanoelectrode showed good response towards the electro-catalytic reduction of molecular oxygen with a Tafel slope of about 120 mV which is close to the theoretical 118 mV for a single electron transfer process in the rate limiting step; and a transfer coefficient (α) of 0.49. The heterogeneous rate constant of electron transfer (ket), exchange current density (io) and time constant (τ) were calculated from data obtained from electrochemical impedance spectroscopy and found to have values of 2.3 x 10-5 cm s-1, 1.6 x 10-4 A cm-2 and 2.4 x 10-4 s rad-1, respectively.
Abstract: Schedule waste used in this study is white aluminium dross produce from an aluminium smelting plant. It has a gibbsite crystal form, and was calcined at high temperature and transformed into α-alumina. nanosized powder with 76 nm primary particle size was produced by top-down method via high velocity wet milling. Comparative thermal insulation study was then performed in paints made from 15 wt% of these nanosize and micron-size alumina. The results from this study shows that the nanosize α-alumina is the best insulator, with a temperature reduction of 57 and 41% less, compared to micron-size α-alumina respectively for ceramic and steel plate.
Abstract: Silver nanoparticles are the most promising nanomaterial with antibacterial properties. Recent study of resistance to most potential antibiotics promotes research in the bactericidal activity of the silver nanoparticles. In this work, the effect of biosynthesized silver nanoparticles, in combination with gentamicin and ampicillin, on Pseudomonas Aeruginosa bacteria has been studied. Pseudomonas Aeruginosa is a common bacterium that can cause infections which are generalized as inflammation and sepsis. The results show that the bactericidal properties of the nanoparticles depends on the size of the as-synthesized silver nanoparticles as nanoparticles of diameter ~120 nm only have a direct interaction with the bacteria. It is observed that the antibacterial activities of antibiotics increase in the presence of AgNPs against test strains. Silver nanoparticles were synthesized elctrolytically using silver wire of 99% purity as anode and carbon rod wrapped with LDPE as cathode. 0.01 N Silver nitrate was used as an electrolyte. The process is termed as biosynthesis, because tea extract was used used as the capping agent which is also a very mild reducing agent. The polyphenols theaflavins and thearubigins, present in tea perform the role of stabilizing or capping agents due to their bulky and steric nature. A brown colored colloidal solution of silver nanoparticles is obtained. The as-synthesized silver nanoparticles were characterized using XRD, TEM and UV-Vis spectroscopy.
Abstract: t will be demonstrated that light extraction of GaNcan be more efficient with the use of flat and dome epoxy. Theoretically the angle, wavelength, and thickness depend on the photoluminescence emission of the luminescent film of transparent substrate. This was studiedusing theFresnel type transmittance calculations for s- (TE) and p- (TM) polarized emission. Experimentally we have demonstrated a GaN/sapphire microcavity exhibited in the 1.3-1.6 fold enhancement in light extraction efficiency by using flat and dome epoxy as external medium compared with air external medium. In addition, simulation results shows that using (HfO2(), Epoxy (),MgF2 (), Air ()) improve the light extraction by increasingthe critical angle and diffracting the internal light with a large solid angle into the light escape cone.
Abstract: The ferroelectric properties of layer-structured Strontium Bismuth Titanate (SBT) have been investigated in this study. SBT was prepared using solution combustion technique with glycine as a fuel. Single-phase formation of the layer-structured compound of SBT with orthorhombic structure was achieved after calcinations at 800 °C, and was confirmed by x-ray diffraction studies. Scanning electron micrograph shows that the grains exhibit a plate like morphology and possesses ne particle size. The as prepared sample exhibits ferroelectric properties with remnant polarization of 2Pr = 1.84 μC/cm2 at coercive field 2Ec= 2.61 kV/cm and displays low dielectric loss. Its ferroelectric transition temperature (Tc) is found to be 450 °C.
Abstract: Series of glasses based on (75-x)TeO2-15MgO-10Na2O-xNd2O3, where x=0, 1.0, 2.0 and 3.0, are synthesized by conventional melt-quenching technique. The nanoglass particles are derived from heat treatment of this glass near crystallisation temperature for 3 hours. The existence of nanocrystalline nature of this glass is confirmed by x-ray diffraction (XRD) technique followed by calculation using Scherrer equation. Meanwhile, the crystallization temperature, Tc determined using Differential thermal analysis (DTA). The fluorescence spectra of Nd3+ ions exhibit emission transition of 2P3/24I9/2, 4G7/24I9/2, 2H11/24I9/2, and 4F9/24I9/2 under 765 nm excitation wavelengths.
Abstract: In this work, we have investigated the fabrication of Double gate and Single gate Junctionless silicon nanowire transistor using silicon nanowire patterned on lightly doped (105 cm-3) p-type Silicon on insulator wafer fabricated by Atomic force microscopy nanolithography technique. Local anodic oxidation followed by two wet etching steps, Potassium hydroxide etching for Silicon removal and Hydrofluoric acid etching for oxide removal, were implemented to reach the structures. Writing speed and applied tip voltage were held in 0.6 µm/s and 8 volt respectively for Cr/Pt tip. Scan speed was held in 1.0 µm/s. The etching processes were elaborately performed and optimized by 30%wt. Potassium hydroxide + 10%vol. Isopropyl alcohol in appropriate time, temperature and humidity. The structure is a gated resistor turned off based on a pinch-off effect principle, when essential positive gate voltage is applied. Negative gate voltage was unable to make significant effect on drain current to drive the device into accumulation mode.
Abstract: Nanosized Zinc oxide (ZnO) possesses unique electrical, optoelectronics and photochemical characteristics and thus it is a potential candidate for different applications in next generation of optoelectronic device. In this work, a novel sol-gel route for the synthesis of ZnO nanoparticles and its transformation into wires and bundles has been reported. The process is adopted from a simple and hand-on route that also shows the power of green chemistry in nanomaterials synthesis. ZnO nanoparticles (~30 nm in diameter) were synthesized from bottom-up approach followed by a further process to obtain nanometric wires and bundles under controlled conditions. The nanowires and bundles are speculated to initiate from anisotropic agglomeration of nanometric particles and agglomeration of these nanometric wires into bundles respectively. Control of these agglomeration processes is a key challenge for application of nanowires and bundles into useful devices.