Fabrication and characterization of a highly sensitive surface plasmon resonance-based fiber optic sensor for the detection of low concentrations of ammonia gas have been reported. The sensor probe is fabricated by coating an unclad core of the optical fiber with successive layers of indium tin oxide (ITO) and bromocresol purple (BCP). Increase in the concentration of ammonia gas around the sensing probe increases the resonance wavelength linearly implying that the absorption of ammonia gas by BCP layer increases its refractive index. In addition, ITO layer also contributes to the increase in the resonance wavelength because it is porous and has grains, which allow the reaction products to enter the pores of the ITO layer causing swelling of the layer resulting in mechanical stress and hence increase in the refractive index. To achieve maximum sensitivity of the sensor, the thickness of the BCP layer is optimized and is found to be 70 nm. The sensitivity of the sensor with optimized thickness of BCP layer is 1.891 nm/ppm and is larger than the sensitivity values obtained in the cases of Ag/BCP and Cu/BCP-coated probes for the concentration range 1-10 ppm of the ammonia gas. The selectivity of the probe is checked by carrying out experiments on the probe with different gases and it is observed that the probe is highly selective for ammonia gas. The sensor has many advantages, such as low cost, online monitoring, and remote sensing, due to the fabrication of the surface plasmon resonance probe on an optical fiber.Index Terms-Ammonia gas, bromocresol purple, indium tin oxide, optical fiber, sensor, surface plasmon resonance.

Novel series of aryldiazoquinoline multifunctional molecules controls amyloid formation and neuro-protective role by inhibiting esterase enzymes.

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This paper presents an investigation of the thermal behaviour of a non‐airconditioned building with walls/roof being exposed to periodic solar radiation and atmospheric air while the inside air temperature is controlled by an isothermal mass, window and door in the walls of the room. The effects of air ventilation and infiltration, the heat capacities of the isothermal storage mass inside air and walls/roof, heat loss into the ground, and the presence/absence of the window/door have been incorporated in the realistic time dependent periodic heat transfer analysis to evaluate the overall heat flux coming into the room and the inside air temperature. A numerical computer model using typical weather data for Delhi has been made to appreciate the analytical results quantitatively. It is found that the heat fluxes through different walls have different magnitudes and phase lags w.r.t. the corresponding solair temperatures. The overall heat flux coming into the room as well as the room air temperature are sensitive functions of the number of air changes per hour, closing/opening of the window and the door ventilation. The effects of the heat capacity of the isothermal mass and the basement ground are found to reduce the inside air temperature swing and the presence of a window is found to increase the inside air temperature even when the window area is much smaller than the wall/roof area. The model presented would be an aid to a building architect for good thermal design of non‐airconditioned buildings.