Abstract: Gas sensors are devices that can convert the concentration of an analyte gas into an electronic signal. Zinc oxide (ZnO) is an important n-type metal oxide semiconductor which has been utilized as sensor for several decades. In recent years, there have been extensive investigations of nanoscale semiconductor gas sensors. The size reduction of ZnO sensors to nanometer scale provides a good opportunity to dramatically increase their sensing properties in comparison with their macro scale counterparts. Among the semiconductor metal oxides, zinc oxide (ZnO) is one of the most widely used gas sensing material. Before making any gas sensor, it is very much necessary to know the sensitivity , selectivity of the sensor and their optimization. In this paper, we present the growth of ZnO nanostructures by thermal evaporation technique and investigation of their gas sensing properties. It is observed that the sensing characteristics of single nanowires and films made using nanowires to clearly differentiate the intra grain and grain boundary contributions as well as to develop sensors with better sensitivity/ selectivity. This paper is very much useful for those who would like work on gas sensors for better gas sensing performances.
Keywords: Gas sensor, Nanowires, ZnO.
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Abstract: There is an increasing demand to improve the energy density of dielectric capacitors for satisfying the next generation material systems. One effective approach is to embed high dielectric constant inclusions such as lead zirconia titanate in polymer matrix. However, with the increasing concerns on environmental safety and biocompatibility, the need to expel lead (Pb) from modern electronics has been receiving more attention. Using high aspect ratio dielectric inclusions such as nanowires could lead to further enhancement of energy density. Therefore, the present brief review work focuses on the feasibility of development of a lead-free nanowire reinforced polymer matrix capacitor for energy storage application. It is expected that Lead-free sodium Niobate nanowires (NaNbO3) will be a future candidate to be synthesized using simple hydrothermal method, followed by mixing them with polyvinylidene fluoride (PVDF) matrix using a solution-casting method for Nanocomposites fabrication. The energy density of NaNbO3/PVDF composites are also be compared with that of lead-containing (PbTiO3/PVDF) Nano composites to show the feasibility of replacing lead-containing materials from high-energy density dielectric capacitors. This paper is very much useful researchers who would like to work on polymer nanocomposites for high energy storage applications.
Keywords: Polymer nanocomposite, high energy, storage capacitors.
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Abstract: The increasing amount of research on watermarking over the past decade has been largely driven by its important applications in digital copyrights management and protection. One of the first applications for watermarking was broadcast monitoring. In this paper presented LSB substitution and threshold-based correlation techniques, performance analysis on the basis of their various types of noises. In this analysis, Different image simulated using two watermarks techniques. We used simulation through using Matlab Simulator.
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Abstract: In this study, the influence of single stage and double stage sintering routes on the microstructure and indentation hardness of nanoscale α-Al2O3 particles have been investigated. The nanoscale alumina particles were compacted by Uniaxial pressing technique. Sintered nanoscale α-Al2O3 particles have been shown to have excellent mechanical properties to be used in the manufacture of nanotubes and nanowires. Among the sintering routes, α-Al2O3 ceramic particles sintered by double stage sintering route showed comparatively higher resistance to indentation than single stage sintering route. The densification achieved by double stage sintering route is higher than single stage sintering route. Based on scanning electron microscope images, the microstructure of samples sintered by double stage sintering route contained less porosity than conventional/ single stage sintering route. The increase in hardness achieved by double stage sintering route can be attributed to higher densification and suppressed grain growth during final stage sintering.
Keywords: α-Al2O3, Uniaxial pressing, indentation hardness, double stage sintering route, single stage sintering route.
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