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Quantitative evaluation of aroma of black tea is a difficult task as no single sensor has been developed which can quantify the volatile aroma compounds. As an alternative, the array of sensors has been attempted to solve this problem involving the principle of neural-network for analysis of responses. To develop the array we have used nano-structured ZnO doped with various metals. In this presentation we describe the responses of Geraniol, Trans-2-Hexenal, Linalool Oxide & Linalool, the major aroma chemicals of black tea to doped and undoped ZnO with Pt metal. Nanostructured ZnO doped with and without Pt are synthesized through chemical process. The synthesized materials are characterized by XRD and SEM which confirm their nanostructure and phase purity. The synthesized sensors are heated in the temperature range of 200°C to 400°C and their responses towards volatile biochemical compounds like Geraniol, Trans-2-Hexenal, Linalool Oxide and Linalool are studied. [ABSTRACT FROM PUBLISHER]

The electrical, dielectric and structural properties of multilayer ZnO/MgO films prepared by simple chemical deposition technique were investigated using I-V measurement, impedance spectroscopy analyzer and field emission scanning electron microscope (FESEM). From the observation, it shows that the annealing temperature influence the electrical, dielectric and structural properties of ZnO/MgO multilayer films. Denser films and small particles are produced as the annealing temperature increase from 400°C to 500°C with 25°C interval. [ABSTRACT FROM PUBLISHER]

Nanostructured W03 thin films have been prepared by thermal evaporation to detect hydrogen at low temperatures. The influence of heat treatment on the physical, chemical and electronic properties of these films has been investigated. The films were annealed at 400°C for 2 hours in air. AFM and TEM analysis revealed that the as-deposited W03 film is high amorphous and made up of cluster of particles. Annealing at 400°C for 2 hours in air resulted in very fine grain size of the order of 5 nm and porous structure. GIXRD and Raman analysis revealed that annealing improved the crystallinity of W03 film. Gas sensors based on annealed W03 films have shown a high response towards various concentrations (10-10000 ppm) H2 at an operating temperature of 150°C. The improved sensing performance at low operating temperature is due to the optimum physical, chemical and electronic properties achieved in the W03 film through annealing. [ABSTRACT FROM AUTHOR]

An excellent UV and visible irradiation response of vanadium-doped silica-titania photocatalysts has been successfully prepared. The designed photocatalyst possesses high surface areas of 610 m2/g. Its outstanding photocatalytic activity is attributed to the presence of tetrahedrally coordinated vanadia species in forms of Ti[Single_Bond]O[Single_Bond]V bonding. Besides, the incorporation of V extends the light adsorption edge of V-doped silica titania aerogels and resulting in reduced band gap energy. [ABSTRACT FROM AUTHOR]