The National Institute of Ocean Technology (NIOT) was established in November 1993 as an autonomous society under the Ministry of Earth Sciences, Government of India. NIOT is managed by a Governing Council and the Director is the head of the Institute. The institute is based in Chennai.The major aim of starting NIOT under the Ministry of Earth Sciences was to develop reliable indigenous technologies to solve various engineering problems associated with harvesting of non-living and living resources in India's Exclusive Economic Zone (EEZ), which is about two-thirds of the land area of India. It works under the Ministry of Earth Sciences.
Derivation of seawater quality criteria (SWQC) is based on ecotoxicological testing is commonly accepted practice because it is one of the important regulatory tools to set the seawater quality regulations for the protection of aquatic life. SWQC for metals in the coastal and coral reef ecosystems of Gulf of Mannar, India have not been derived and notified. To fill the gap, the present study was undertaken and derived the SWQC for copper (Cu), cadmium (Cd), zinc (Zn), and mercury (Hg) based on LC50/EC50, no observed effect concentration and lowest observed effect concentration, and chronic values calculated through ecotoxicological testing with marine food chain organisms. The calculated chronic values showed that mercury was highly toxic and zinc was least toxic to all the tested marine organisms. It is concluded that clam Donax faba, oyster Magallana bilineata, finfish Chanos chanos, and finfish Terapon jarbua showed similar order of toxicity (Hg > Cu > Cd > Zn) while it was Hg > Cd > Cu > Zn for post larvae of shrimp Penaeus monodon. The range of chronic values for Cu were varied from 5.0 (clam Donax faba) to 270.0 μg L−1 (Chanos chanos); Cd were ranged from 8.0 (shrimp P. monodon PL) to 590.0 μg L−1 (Terapon jarbua), Hg were found to be 0.11 (oyster Magallana bilineata) to 2.35 μg L−1 (clam Donax faba), and Zn were between 130.0 (shrimp Penaeus monodon) to 1200.0 μg L−1 (fish Terapon jarbua). Further, the criterion maximum concentration (CMC) and criterion continuous concentration (CCC) were derived based on LC50/EC50 values and final chronic values (FCV), respectively. The CMC values derived for Gulf of Mannar are 39.4 μg L−1 for Cu, 11.4 μg L−1 for Cd, 0.072 μg L−1 for Hg and 340 μg L−1 for Zn and the CCC values are 4.319, 0.909, 0.0044, and 37.226 μg L−1 for respective metal. It is suggested that the above values are recommended as SWQC for the protection of 95
The rise of multidrug-resistant (MDR) pathogens like Pseudomonas aeruginosa PAO1 underscores the urgent need for novel anti-infective strategies. Deep ocean ecosystems harbor diverse and unexplored microbial communities with potential to produce bioactive metabolites. In this study, 52 bacterial isolates from deep ocean sediment and water samples were screened for anti-infective potential using the Caenorhabditis elegans model. Several isolates conferred protection against PAO1-induced fast killing, with five showing no host toxicity. Metabolites extracted using five protocols were tested for immune-protective effects. Pre-supplementation of C. elegans with selected extracts 12 h prior to infection enhanced survival, feeding, and reproduction. Notably, an extract 500 W2 M3 significantly improved host outcomes, reduced pathogen colonization, and lowered ROS accumulation. Gene expression analysis indicated modulation of IIS-associated and immune-related genes, such as daf-16, clec-60, clec-87, scl-1 and sgk-1 suggesting host associated stress and defense responses. GC–MS profiling of 500 W2 M3 revealed the presence of several putative bioactive compounds, including octacosanol, γ-sitosterol, α-amyrin, ethyl 4-ethoxybenzoate, and α-amyrone which may contribute to the observed protective effects, however, further validation through functional assays and compound-based experimentations are required. Finally, upon sanger sequencing for 16S rRNA, the isolate 500 W2 was identified as Staphylococcus arlettae. These results highlight the therapeutic potential of marine-derived bacterial metabolites in combating MDR infections.
A novel multi-stage centrifugal pump with floating impellers, employed in renewable energy pumping systems, flexibly adjusts the number of stages to meet various underground water levels. The floating impeller, combined with sealing gaskets, effectively reduces the axial force, enhancing the pump's lifespan and stability. However, once seal wear occurs, the axial oscillation amplitude of the floating impeller increases, severely affecting the operation of the pumping system. Using computational fluid dynamics simulations with a coupled dynamic mesh and multiple reference frames, the impact of different levels of seal wear is analyzed. Repeated experiments confirm the accuracy of simulations. As the impeller oscillation amplitude increases, pump performance significantly deteriorates. The total leakage increases by up to 114 %, with reductions in head coefficient and efficiency reaching 8.8 % and 4.3 %, respectively. Entropy production within the pump intensifies, and the velocity and pressure distribution change noticeably. The increase in impeller oscillation amplitude leads to a maximum increase of 457 % in pressure fluctuations within the impeller, with increases exceeding 200 % in both the side chamber and return guide vane. The impeller oscillation frequency, as the fundamental frequency of pressure fluctuations, sees an amplitude increase of up to 594 % within flow channels. This study provides valuable insights for stabilizing the performance and reliability of multi-stage centrifugal pumps.
This study numerically investigates the convective heat transfer characteristics of a rotating heated elliptic cylinder immersed in non-Newtonian power law fluid in an unconfined laminar flow regime. The cylinder rotates at a constant angular velocity while the surrounding fluid flows longitudinally at a uniform velocity, while the cylinder surface is maintained at a higher temperature than the ambient fluid. Investigations are carried out on a wide range of variable parameters, including cylinder aspect ratio (0.1 <= e <= 1.0), rotational speed (0.5 <= alpha <= 2.0), Reynolds number (Re = 5, 10, 20 and 40), Prandtl number (1 <= Pr <= 100), and power law index (0.4 <= n <= 1.6). The results show that the heat transfer rate, represented by local and average Nusselt numbers (Nu), is highly responsive to these parameters. The surface averaged Nusselt numbers exhibit periodic variation with angular rotation of the cylinder, with the amplitude significantly influenced by Re, n, alpha, and e. Rotating elliptical cylinders consistently outperform circular cylinders in enhancing heat transfer, particularly in shear-thinning fluids and at higher values of Re and Pr. The isotherm patterns further illustrate the effects of shape, rotation, and fluid behavior on thermal boundary layer characteristics. The results indicate that shear-thinning fluids (n < 1) provide up to 25% higher heat transfer compared to Newtonian fluids. Cylinder rotation further augments convection, yielding about 30% improvement in heat transfer at higher rotation rates. At the end of the report, correlations were established for average Nusselt numbers were established to facilitate result interpolation for intermediate values of e, alpha, Re, Pr, and n and/or the estimation of changes in heat transfer in a new application.
Active cold seep sites associated with shallow methane hydrates, methane gas flares in the water column, and cold seep ecosystems have been reported from the Krishna-Godavari (K-G) basin along the eastern continental margin of India, and the present study represents the first attempt to map and demarcate these cold seep ecosystems in the region. An autonomous underwater vehicle survey was conducted at two cold seep locations (SN184/KG-1, water depth: 1750 and SN184/KG-2, water depth: 950 m) in the Krishna-Godavari basin, to understand the water column methane concentrations along with seabed survey using underwater photographic studies. A cold seep ecosystem is found only at SN184/KG-1. The dissolved methane concentrations at SN184/KG-1 vary from 0.18–1.48 µmol/L, while at SN184/KG-2 it varies from 0.14–0.5 µmol/L. The underwater photographs from the AUV show the presence of methane hydrates on the seabed, bubbling of methane gas, and a large cold seep ecosystem extending to several square meters. Very high dissolved methane concentrations in the water column may be attributed to gas bubbling from the cold seeps. The cold seep ecosystem is predominantly populated with Bathymodiolus species along with the presence of tube worms (Siboglinidae), goose barnacles, etc. At SN184/KG-1 there are fluctuations in the water column pH possibly induced by methane oxidation. Although enhanced water column methane concentrations, and surface hydrates coupled with carbonate crusts are observed at SN184/KG-2, the lack of benthic community at SN184/KG-2 may be attributed to the occurrence of very high sedimentation at this site because of mass transport deposits in recent times. The present study adds up a new methane seepage site and provides baseline database to quantify methane addition to global ocean.
