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Subramoniam T.,National Institute of Ocean Technology
Fisheries Science | Year: 2011

Crustaceans produce complex yolk proteins to meet the substrate and energy requirements of embryonic development. Early electron microscopic investigations point to a biphasic yolk synthesis, first within the ovary, followed by heterosynthesis at extra-ovarian sites. Recent advances in molecular techniques have enhanced our understanding of the genetic control of yolk synthesis in crustaceans. Amino acid sequencing of crustacean vitellogenin (Vg) has enabled the elucidation of the cDNA sequence associated with it, the identification of genes, and the examination of their expression patterns in different tissues. Yolk processing in crustaeans involves cleavage of the pro-Vg at consensus sites by subtilisin-like endoproteases within the hepatopancreas, hemolymph and oocytes. The structural elucidation of crustacean yolk proteins, as well as the comparison of amino acid sequences of vitellogenins from various crustacean species, has revealed molecular phylogenetic relationships not only among them but also with other large lipid transfer lipoproteins of disparate function. The combinatorial effects of eyestalk neuropeptides and a variety of trophic hormones achieve the hormonal coordination of molting and reproduction. Biogenic amines secreted by the central nervous system may also play an integrative role by stimulating neuropeptide secretion. © 2010 The Japanese Society of Fisheries Science. Source

Mohammed Fayaz A.,University of Madras | Girilal M.,University of Madras | Venkatesan R.,National Institute of Ocean Technology | Kalaichelvan P.T.,University of Madras
Colloids and Surfaces B: Biointerfaces | Year: 2011

Metal nanoparticles, in general, and gold nanoparticles, in particular, are very attractive because of their size- and shape-dependent properties. Biosynthesis of anisotropic gold nanoparticles using aqueous extract of Madhuca longifolia and their potential as IR blockers has been demonstrated. The tyrosine residue was identified as the active functional group for gold ion reduction. These gold nanoparticles were characterized by of UV-Vis spectrophotometer, FTIR, TEM and HrTEM. The presence of proteins was identified by FTIR, SDS-PAGE, UV-Vis and fluorescence spectroscopy. The micrograph revealed the formation of anisotropic gold nanoaprticles. The biologically synthesized gold nanotriangles can be easily coated in the glass windows which are highly efficient in absorbing IR radiations. © 2011 Elsevier B.V. Source

Low temperature thermal desalination (LTTD) process involves flash evaporation of a seawater at 28–29°C in a single-stage evaporator maintained at a vacuum of around 25–27 m bar (abs). The seawater was splashed inside an evaporator through a 0.1 m diameter upward facing nozzles of around 24 nos arranged evenly throughout the evaporator and generated vapour was condensed in the shell and tube condenser using cooling water available at 12–13°C sucked from the deep sea through a long HDPE pipe. The main objective of this study was to find out the effect of geometry of the upward facing nozzles on the flash evaporation rate as well as on the non-equilibrium temperature difference (NETD) of the flashing process. Two different spout nozzle geometries with 0.37–0.87 m height were used in the experiment. The study indicated that the flashing rate increased by 0.9% (average) and and the NETD (Two – Tsat) decreased by 0.7°C (average), respectively, when nozzle height was increased by 0.87 m. Mechanism that controlled these two factors were identified and discussed in this paper. Drawbacks of 0.37 m nozzle geometry was also discussed. It was reported in literature that 4% yield ratio was obtained for a nozzle injection pressure of 1 bar for a similar desalination process. But in the present study, a maximum of 1.12% yield ratio was obtained with a nozzle injection pressure of around 0.17 bar. In this work,the effect of the process parameters on the liquid flashing in a LTTD desalination process was investigated and discussed. In order to fine tune the evaporator design for the future LTTD plants, the experimental results of flash evaporation were compared with two mathematical models obtained from the literature. While comparing the results, it was observed that the model which used actual heat (Twi – Two) made a good agreement with the experimental data compared to the other model that used superheat (Twi – Tsat). From the experimental study, it was observed that the NETD (i.e. thermal loss) measured was found to be higher than the predicted value. The reason that caused the difference in the NETD value was investigated and discussed. Suitable suggestions to reduce these NETD in the flashing process were also presented. © 2016 Balaban Desalination Publications. All rights reserved. Source

Inbakandan D.,Sathyabama University | Inbakandan D.,Annamalai University | Venkatesan R.,National Institute of Ocean Technology | Ajmal Khan S.,Annamalai University
Colloids and Surfaces B: Biointerfaces | Year: 2010

The growing trend of exploring bacteria, fungi, actinomycetes and plant materials for the biosynthesis of nanoparticles is considered as eco friendly and a green technological approach. In this backdrop the present study reports the synthesis of gold (Au) nanoparticles from gold precursor using the extract derived from the marine sponge, Acanthella elongata (Dendy, 1905) belonging to the primitive phylum Porifera. Water-soluble organics present in the marine sponge extract were mainly responsible for the reduction of gold ions to nano-sized Au particles. The sponge extract added to 10-3M HAuCl4 aqueous solution at 45°C changed to pinkish ruby red color solution and confirm the bioreduction within 4h with continuous stirring. UV-visible spectrum of the aqueous medium containing gold nanoparticles showed a peak around 526nm. High-resolution transmission electron micrographs (HR-TEM) confirmed the monodispersed and spherical shaped with the size ranges from 7 to 20nm, however a maximum number of particles were in 15nm diameter. Through Fourier transform infrared spectroscopy (FT-IR) analysis, the reducing agent in the marine sponge extract was identified which is attributed for the biosynthesis of gold colloids. The XRD analysis respects the Bragg's law and confirmed the crystalline nature of the gold nanoparticles. © 2010 Elsevier B.V. Source

Narayanaswamy V.,National Institute of Ocean Technology
Underwater Technology | Year: 2014

Reliable power supply is required for operating subsea installations, such as enhanced oil recovery systems, tidal power generator systems and benthic environment monitoring stations. Electrical and electronic systems need to be operated inside pressure-rated or pressure-compensated enclosures so as to protect them from external seawater and hydrostatic pressure. Such enclosures are nitrogen filled, partially oil filled, fully oil filled or pressure compensated. System breakdowns lead to huge production losses and loss of critical environmental data. Reliability and, hence, the useful life of the internal systems depend mainly on the internal ambient temperature and relative humidity levels. The present paper discusses the need for efficient thermal and humidity management, methods currently adopted in the industry and their limitations in long-term operation. Solutions to carry out effective thermal and humidity management in future subsea electric systems, with the objective of reduced maintenance over the design lifetime of the system, are discussed. The proposed thermal management techniques include use of static fans, thermoelectric coolers, acoustic-based heat transfer and bio-fouling control methods. Proposed humidity management techniques include thermo-siphon-based water removal, and in situ subseabased molecular sieve oil filtration. Further, the advantages of pressure compensation in overcoming the thermal and enclosure structural challenges are explained. The ongoing global efforts in the development of pressure-tolerant systems, significant findings on the component behaviour to pressure and the need for accelerating pressure-tolerant electronic developments are discussed. Source

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