Freshwater Aquaculture

Indian aquaculture has grown at a faster pace of almost 5.5 per cent per year consistently since last 50 years. In some of the years the growth rate in the aquaculture was recorded as high as 9 per cent. Indian aquaculture has demonstrated a six and half fold growth over the last two decades, with fresh water aquaculture contributing over 95 per cent of the total aquaculture production and more than half of the national fish production. The three Indian major carps, namely catla (Catla catla), rohu (Labeo rohita) and mrigal (Cirrhinus mrigala) contribute the bulk of production with over 1.8 million tonnes (FAO, 2003) Average national production from fresh water ponds has increased from 0.6 tonnes/ha/year in 1974 to 2.9 tonnes/ha/year by 2009–2010 (DAHDF, 2010), with several farmers even demonstrating production levels as high as 8–12 tonnes/ha/year. For the newly introduced fishes like Pangus the production recorded was as high as 25 tonnes/ha/yr. At the national level as well as in state level, the production and productivity has been on the rise over a period of time. Backed by new policies like Fish Farmers Development Agencies (FFDA), National Fisheries Development Board (NFDB) and state initiatives, there are enough incentives to increase the productivity of fish per unit water areas

Marketing and Processing

India is the third largest fish producing country in the world. The sector has high potentials for rural development, domestic nutritional security, employment generation as well as export earnings. Indian fisheries sector has been witnessing a steady growth, and the annual fish production has risen to 7.85 million tonnes during 2009-10. The rate of growth of the inland sector has been high and the inland fish production is 4.87 million tonnes and has almost doubled in the last decade. It is estimated that fishing, aquaculture and allied activities provide employment to over 14 million people

Environmental factors affecting the marine corrosion performance of nickel aluminium bronze

Nickel-aluminium bronze (NAB) alloys are extensively used in seawater environments because they have good castability, toughness and erosion-corrosion performance. However, NAB alloys may encounter corrosion related problems under in-service conditions, i.e. different local environments, leading to variability in corrosion performance worldwide. Importantly, NAB alloys have complex microstructures consisting of up to 6 different phases and as a consequence they are susceptible to selective phase corrosion. The current study has primarily concentrated on the corrosion performance of cast NAB, both uncoupled and galvanically coupled, in a marine environment, namely the natural seawater at the National Oceanography Centre Southampton. With particular emphasis given to the galvanic compatibility of NAB (naval specification NES 747 Part 2), the seasonality of environmental factors such as biofouling, plus an in-depth laboratory investigation was made into the erosion-corrosion performance of cast NAB using a test slurry containing 3.5% NaCl solution and sand. A study of the corrosion performance of uncoupled NAB revealed that initially corrosion was confined mainly to the eutectoid regions with slight attack of the copper-rich ?-phase within the ?+?III eutectoid. However, for prolonged exposures an adherent corrosion film formed as corrosion of the copper-rich ?-phase penetrated further into the NAB microstructure leaving the unattacked ?-phases to create an adherent skeletal lattice primarily due to the continuous nature of the ?III-phase. In addition, prolonged exposures resulted in selective phase corrosion which was predominately associated with an attack of the ?III–phase, which may also develop into pit initiation involving the formation of solid CuCl in an otherwise protective oxide film. The galvanically coupled NAB, with either itself, a wrought high strength copper-nickel alloy or a commercially pure titanium (Grade 2) showed accelerated galvanic corrosion within the first year of exposure to natural seawater which diminished in the following years. This behaviour coincided with the seasonal biofilm activity and increased likelihood of biofilm formation and kinetics. The role of bacterial metabolites/enzymes in the biofilm has been associated with an initial modification of the cathodic oxygen reduction kinetics, thus increasing the corrosion activity during the first biofilm season after exposure. Mass transfer kinetics for the anodic and cathodic reactions, as a function of flow rate, were studied in a wall-jet electrode for freshly polished pure copper and NAB. The diffusion coefficient of oxygen during cathodic reduction increases with increasing concentration oxygen. The cathodic reaction is the rate controlling step in the corrosion process. The high mass transfer coefficient for the oxygen has been attributed to the higher turbulence intensity within the wall-jet cell compared with either rotating disc or cylinder electrodes.Under flow corrosion, erosion and erosion-corrosion conditions (jet impingement) the cast NAB demonstrated superior performance than HVOF NAB coatings. The flow corrosion rates for cast NAB and HVOF NAB coating was found to be 0.5-0.8 and 0.8-1.5 mm y-1, respectively. Compared with the cast NAB, the porous nature of the HVOF coating and the presence of coating impurities undermined the corrosion performance. Likewise, the erosion behaviour of HVOF NAB coating was due to the high flaw density and splat boundaries, which act as crack initiators. The high kinetic energy exponent in HVOF NAB coating suggested a combination of both ductile and brittle erosion mechanisms possibly due to the porosity. In contrast, the cast NAB resulted in an energy exponent close to unity consistent with ductile materials. A SEM study revealed the cast NAB had undergone plastic deformation at the maximum erosion depth while microcutting was seen outside the centre of erosion scar. The synergistic effect based on the gravimetric, electrochemical and surface hardness measurements are also presented. The negative synergy in general infer to the good properties of the material

Fabrication of Cobalt-Based Nano-Composite Film for Corrosion Mitigation of Copper in Flow Chloride Medium

Corrosion of metals leads to high maintenance costs, as well as potential threats to structural health and safety. Here, we demonstrate the coating of cobalt tungstate (CoWO4) nanoparticles (NPS)/5-mercapto-1-phenyl-1 H-tetrazole derivative (MPT) used as a nano-composite film on Cu surface for the blocking of micropores to hinder the propagation of metastable pits in an aggressive NaCl medium. The mechanism of interaction between the nanoparticles and tetrazole derivative, in addition to the mode of anchoring to the metal surface and blocking the penetration of chloride ions (Cl−), are all investigated. In this investigation, CoWO4 is synthesized via a wet chemical route and thereafter, is combined with MPT at an optimized ratio thus formulating a nano-composite corrosion inhibitor which in solution gets coated on Cu surface. Atomic force and scanning electron microscopic images of the bare Cu reveal dip pits, which by the coating of the nano-composite are suppressed at the nucleation stage during exposure to the aggressive 3.5% NaCl electrolyte under flow conditions. Electrochemical analysis shows high protection of Cu up to 97% efficiency in the presence of the newly formulated nano-composite inhibitor film

Fabrication of Cobalt-Based Nano-Composite Film for Corrosion Mitigation of Copper in Flow Chloride Medium

Corrosion of metals leads to high maintenance costs, as well as potential threats to structural health and safety. Here, we demonstrate the coating of cobalt tungstate (CoWO4) nanoparticles (NPS)/5-mercapto-1-phenyl-1 H-tetrazole derivative (MPT) used as a nano-composite film on Cu surface for the blocking of micropores to hinder the propagation of metastable pits in an aggressive NaCl medium. The mechanism of interaction between the nanoparticles and tetrazole derivative, in addition to the mode of anchoring to the metal surface and blocking the penetration of chloride ions (Cl−), are all investigated. In this investigation, CoWO4 is synthesized via a wet chemical route and thereafter, is combined with MPT at an optimized ratio thus formulating a nano-composite corrosion inhibitor which in solution gets coated on Cu surface. Atomic force and scanning electron microscopic images of the bare Cu reveal dip pits, which by the coating of the nano-composite are suppressed at the nucleation stage during exposure to the aggressive 3.5% NaCl electrolyte under flow conditions. Electrochemical analysis shows high protection of Cu up to 97% efficiency in the presence of the newly formulated nano-composite inhibitor film

Studies on inhibitory effect of Eucalyptus oil on sebaceous glands for the management of acne

345-349Acne is the most common disorder virtually seen to affect teenagers and young adults between age of 14-30. It is characterized by inflamed specialized sebaceous follicles which are present at face, back and chest. Some serious factors responsible for generation of acne are abnormal follicular keratinization and desquamation, excessive secretion of sebum, and proliferation of Propionibacterium acnes in follicles. Other factors aggravating or worsening the acne conditions are secondary infections caused by some pathogenic strains of bacteria like Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, etc. There are various topical and systemic therapies available in market to treat or control the acne but maximum of them have the side effects like itching, redness, skin peeling, stinging and photosensitivity. Again, the development of resistance of available antibiotics for P. acne and other bacterial strains has necessitated the search for new antimicrobial agents. Thus, the current work was designed to gain attention towards the alternate pathway for controlling the acne condition by decreasing the production of sebum from sebaceous glands. The eucalyptus oil, obtained from Eucalyptus globulus Labill. (Myrtaceae) was chosen and its biocide action on various bacterial strains was established using agar-well diffusion technique to prove its efficacy in controlling the secondary infection condition i.e. worsening of acnes. The in vivo rat sebaceous gland model was chosen to show the effectiveness of eucalyptus oil in decreasing the sebum production by reducing the size of sebaceous glands to control the spread of acne. The results were found to be promising for eucalyptus oil in controlling the sebum protection and thus establishing the other pathway for the management of acne