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We present results from our studies on the fabrication of gold (Au) nanostructures (NSs) using picosecond (ps) laser ablation in ambient air, as well as the fabrication of silver (Ag) nanoparticles (NPs) in various liquids, such as distilled water, NaOH and KOH. The synthesized Au NSs and Ag NPs are utilized as surface-enhanced Raman scattering (SERS) substrates. Au NSs sensitivity was further improved with the deposition of chemically synthesized Au nanostars. The shape and size of obtained Ag NPs and Au nanostars were investigated using transmission electron microscopy (TEM). The morphology of the laser-patterned areas on the Au surface was studied by field emission scanning electron microscope (FESEM) measurements. The Au nanostars decorated on laser-patterned Au SERS substrate exhibited superior reproducibility of the Raman signals (< 10% RSD) and better SERS enhancement factors (~10 5 ) for thiram (a commonly used fungicide molecule in a variety of crops) in comparison with the laser-patterned Au (without Au nanostars) as well as Au nanostars decorated flat Au substrates. The stability of Ag NPs was studied by UV-visible absorption spectroscopic technique. Ag NPs synthesized in NaOH and KOH liquid environment are stable for 30 days compared with Ag NPs dispersed in distilled water.

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Present study was undertaken at the marine cage farm of Polem Village, Goa. Water and sediment samples were analysed for evaluation of the physicochemical characteristics and total cultivable heterotrophic bacteria. No significant variation was observed in the physicochemical parameters of water except for inorganic phosphate (p<0.05). Total cultivable bacterial count ranged from 2.06 to 19.27 x 10 4 cfu g -1 and from 1.14 to 8.41 x 10 4 cfu g -1 , while total presumptive vibrio count ranged from 0.15 to 1.57 x 10 4 g -1 and 0.09 to 0.78 x 10 -4 g -1 . Results of the present investigation revealed that all the parameters studied were within the optimum range and cage farming with limited number of cages does not have major impacts on the water and sediment quality.