Sol-Gel Chemistry Materials for Anti-Corrosion Coatings

This review paper summarizes the current state of the art of sol-gel technology for formulating anti corrosive protective coating. A brief description of the mechanism of sol-gel reactions, various parameters that influence the property of the final product and the course of the sol-gel reaction has been given. Different types of metal precursors that are extensively used in sol preparation and the advantages and disadvantages have also been mentioned in brief. Surface chemistry of sol-gel matrix and various stabilizing and destabilizing forces that are active on the surface of colloidal particles have also been discussed. Problems related to obtaining good quality product with uniformly distributed concentrations have been outlined. Possible pathways for further improvement of anti-corrosive properties of the coating have been described, such as incorporation of various types of additives into the sol matrix prior to coating. As a whole the present study summarizes the superiority and benefits of organic-inorganic hybrid coatings using sol-gel technique and having good protective and anti-corrosive properties

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Not AvailableAn integrated multi-trophic aquaculture (IMTA) model involving mullets (Mugil cephalus and Liza parsia) and tiger shrimp (Penaeus monodon) as fed-species, and estuarine oyster (Crassostrea cuttackensis) and seaweed, Enteromorpha spp. as extractive species was evaluated as a viable aquaculture option in brackishwater of the Indian Sundarban. A 150-day field experiment was conducted in six brackishwater ponds (600 m2 each). There were two randomly assigned groups, IMTA and polyculture (control) with three replicate ponds. Ponds under IMTA were stocked with mullets and tiger shrimp at 10000 and 30000 no./ha, respectively, C. cuttackensis at 1600 no./ha suspended with a basket in the water column and Enteromorpha spp. at 200 kg biomass/ha. Control ponds were stocked with mullets and shrimp at the same densities to that of IMTA, and devoid of oyster and seaweed. A common low-cost polyculture feed was provided to fishes and shrimp. Mullets attained a significantly higher growth (p <0.05) in the IMTA system compared to that of control ponds, whereas tiger shrimp had insignificantly higher growth in IMTA than in control. Significantly higher production of 1707 kg/ha (19% higher) with better water quality was obtained in IMTA system compared to that of control ponds (1434 kg/ha) (p <0.05). There was a significant reduction in apparent feed conversion ratio by 22%, and an increase in net income by 69% and benefit-cost ratio by 30% in the IMTA system than that of the control. Moreover, for the first time the estuarine oyster, C. cuttackensis was used as an extractive species in brackishwater IMTA system. From an indoor trial, it was observed that this oyster species has high water filtration capacity to remove suspended matters, including planktons. This preliminary experiment indicates the application of IMTA concept in brackishwater as a viable environment-friendly option and warrants further refinement for species combination with the economic viability and environmental suitability.Not Availabl

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Not AvailableVirulence gene and antibiotic resistance profile of Shiga-toxin producing Escherichia coli prevalent in captive yaks (Poephagus grunniens).Not Availabl

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Not AvailableFeed is the costliest input that accounts 50-60% of operational expenditure in aquaculture. To reduce the feed quantity and minimize related environmental impacts arising from feed wastage in aquaculture, natural fish food item, periphyton can be utilized as an alternate option. Milkfish (Chanos chanos), being a herbivore fish, can be cultured by developing periphyton biomass as natural diet and thereby to reduce use of commercial feed. Monoculture of milkfish (15000 no./ha) for 180 days was undertaken in 50 m2 pond enclosures with four different feeding systems: (P0) control with total feeding and no periphyton; P75, P100 and P125 were with periphyton grown on 75, 100 and 125% pond surface area, respectively along with partial feeding. White nylon net (40 mesh) as substrate for periphyton growth was fixed vertically in the epilimnion of pond water. Fish growth (242.29±5.22 g), productivity (3146±60 kg/ha) and benefit-cost ratio (1.81) were significantly highest (P<0.05) with lowest FCR of 1.17±0.02 in P125. FCR could be reduced maximum by 46% compared to P0 in P125 based on the dry matter of periphyton grown in negative control enclosures containing no fish. Therefore, this method is appropriate for monoculture of milkfish to reduce feed cost and ensure environmental sustainabilityNot Availabl

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Not AvailableAny sustainable aquaculture system should have low environmental impact, and high social and economic acceptability. To address these issues in brackishwater aquaculture, performance of integrated multi-trophic aquaculture (IMTA) models with three different species combinations (T1, T2 and T3) was compared with conventional polyculture (C) in low-saline ponds (500 m2) in triplicate. In a 150-day field trial, ponds under T1, T2, T3 and C were stocked with Mugil cephalus, Liza tade and Peneaus monodon at 2000, 10000 and 30000 no. ha−1, respectively as fed-species. In addition, T1 and T3 contained water spinach, Ipomoea aquatica at 200 kg ha−1, and T2 and T3 contained oyster, Crassostrea cuttackensis at 2000 no. ha−1 as extractive species. Experimental animals were fed with a low cost pellet feed (Crude protein 31%). The inorganic nutrient parameters (nitrogenous and phosphorus compounds) of water improved in all three IMTA treatment ponds in comparison to C. On the final day, dissolved organic carbon content was significantly the lowest (P  0.05) higher in T3 compared to that of T1, T2 and C. However, growth of tiger shrimp, P. monodon was significantly higher (P < 0.05) in T3 (22.17 ± 1.29 g). Pooled survival of fishes and shrimp was similar among treatments, whereas total production was significantly higher (P < 0.05) in T3 (1695.7 kg ha−1), followed by that in T1 (1211.9 kg ha−1), T2 (894.2 kg ha−1) and C (505.4 kg ha−1). Overall, whole body composition of fishes and shrimp at harvest revealed that crude protein and lipid contents were marginally at higher levels in IMTA treatments compared to that of C. There were 3.48 and 1.6-fold increases in net return and benefit-cost ratio, respectively in T3 than that in C. Therefore, this IMTA model (T3) proved to be productive, and economically viable with environmental bio-remediation effect.Not Availabl

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Not AvailableAny sustainable aquaculture system should have low environmental impact, and high social and economic acceptability. To address these issues in brackishwater aquaculture, performance of integrated multi-trophic aquaculture (IMTA) models with three different species combinations (T1, T2 and T3) was compared with conventional polyculture (C) in low-saline ponds (500 m2) in triplicate. In a 150-day field trial, ponds under T1, T2, T3 and C were stocked with Mugil cephalus, Liza tade and Peneaus monodon at 2000, 10000 and 30000 no./ ha, respectively as fed-species. In addition, T1 and T3 contained water spinach, Ipomoea aquatica at 200 kg/ ha, and T2 and T3 contained oyster, Crassostrea cuttackensis at 2000 no./ ha as extractive species. Experimental animals were fed with a low cost pellet feed (Crude protein 31%). The inorganic nutrient parameters (nitrogenous and phosphorus compounds) of water improved in all three IMTA treatment ponds in comparison to C. On the final day, dissolved organic carbon content was significantly the lowest (P < 0.05) in T3 (9.39 ± 0.61 mg/ L), compared to that in C (13.73 ± 1.27 mg/ L). Similarly, particulate organic matter content was also significantly the lowest (P < 0.05) in T3 (61.33 ± 5.75 mg/ L) among all the treatments. Chlorophyll-a content in pond water of IMTA treatments (T2 and T3) with oyster was significantly low (P < 0.05) compared to that in C (0.048 ± 0.009 mg/ L) and T1 (0.040 ± 0.002 mg/ L) on the final day. Final body weight of M. cephalus (118.10 ± 7.29 g) and L. tade (25.41 ± 1.54 g) was not significantly (P > 0.05) higher in T3 compared to that of T1, T2 and C. However, growth of tiger shrimp, P. monodon was significantly higher (P < 0.05) in T3 (22.17 ± 1.29 g). Pooled survival of fishes and shrimp was similar among treatments, whereas total production was significantly higher (P < 0.05) in T3 (1695.7 kg/ ha), followed by that in T1 (1211.9 kg/ ha), T2 (894.2 kg/ ha) and C (505.4 kg/ ha). Overall, whole body composition of fishes and shrimp at harvest revealed that crude protein and lipid contents were marginally at higher levels in IMTA treatments compared to that of C. There were 3.48 and 1.6-fold increases in net return and benefit-cost ratio, respectively in T3 than that in C. Therefore, this IMTA model (T3) proved to be productive, and economically viable with environmental bio-remediation effect.Not Availabl

Aquaculture

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Not AvailableTo evaluate the effects of different management systems on performances of grey mullet (Mugil cephalus L.) fingerlings, a 120-day experimental trial was conducted in twelve brackishwater ponds (600 m2 each). Rearing management systems assessed were: fertilization alone (FR), combined fertilization-feeding (FF), fertilizationperiphyton (FP) and fertilization-compost application (FC) in triplicate ponds. Soaked mustard cake was used as a fertilizer @ 100 kg ha−1 at 15-day intervals in all the treatment ponds. Formulated crumble diet containing 29.7% protein and 4.9% lipid was used as a supplementary feed in FF. Bamboo poles were used as substrates (equivalent to 10% of pond surface area) to facilitate periphyton growth in FP and composted aquatic weed was applied @ 500 kg ha−1 in FC at monthly intervals. Ponds were stocked with grey mullet fry (3.36 ± 0.32 g/ 63.70 ± 4.61 mm) at 30,000 number ha−1. The experiment revealed significant differences in most of the water quality parameters among the four treatments. In FP ponds, a significant reduction (P < 0.05) in inorganic nitrogen and phosphorous, chlorophyll-a contents, and plankton population was observed. The highest fish growth (28.39 ± 1.94 g) and survival (94.3 ± 4.2%) were recorded in FP followed by in FF, FC and FR (P < 0.05). A significantly higher total fish biomass (P < 0.05) was obtained in FP (803 ± 29 kg ha−1) followed by in FF (730 ± 37), FC (507 ± 33) and FR (362 ± 22). Condition factor (K) and isometric exponent (b) of length-weight relationship indicated that fingerlings were in better condition with isometric growth (K=1.37 ± 0.13; b =3.01 ± 0.12) in FP. Inferior condition with allometric growth was observed in FR, FF and FC systems. These results suggest that periphyton based system can be an appropriate rearing technique for grey mullet fingerling production in brackishwater fertilized ponds as an environment-friendly and sustainable practice.Not Availabl