Background and Objectives: The quick response time and the coverage range are the crucial factors by which the quality service of a wireless sensor network can be acknowledged. In some cases, even networks possess sufficient available bandwidth but due to coverage tribulations, the customer satisfaction gets down suddenly. The increasing number of nodes directly is neither a canny solution to overcome the coverage problem nor a cost-effective. In fact, by changing the positions of the deployed node sagaciously can resolve the coverage issue and seems a cost-effective solution. Therefore, keeping all circumstances, a Depuration based Efficient Coverage Mechanism (DECM) has been developed. This algorithm suggests the new shifting positions for previously deployed sensor nodes to fill the coverage gap. Methods: It is a redeployment process and accomplished in two rounds. The first round avails the Dissimilitude Enhancement Scheme (DES), which searches the node to be shifted at new positions. The second round controls the unnecessary movement of the sensor nodes by the Depuration mechanism thereby the distance between previous and new positions is reduced. Results: The factors like loudness, pulse emission rate, maximum frequency, and sensing radius are meticulously explored during simulation rounds conducted by MATLAB. The performance of DECM has been compared with superlative algorithms i. e., Fruit Fly Optimization Algorithm (FOA), Particle Swarm Optimization (PSO), and Ant Colony Optimization (ACO) in terms of mean coverage range, computation time, standard deviation, and network energy diminution. Conclusion: According to the simulation results, the DECM has achieved more than 98% coverage range, with a trivial computation time of nearly 0. 016 seconds as compared to FOA, PSO, and ACO.

BACKGROUND AND OBJECTIVES: The nanoparticles has been discussed in terms of their adverse global impacts on health and health inequity. Metal oxide nanoparticles and their salts can have varied toxic effects on different tissues in the aquatic environments. The aim of present study was to assess the toxicity of nickel oxide nanoparticles in relation to different nickel salts. METHODS: Acute toxicity of nickel oxide nanoparticles, nickel sulfate, nickel nitrate and nickel chloride, in black fish was investigated. A total of 125 fish were randomly assigned to a control group (n=25) and four exposure groups (n=25 per group). After 28 days of exposure, the bioaccumulation of nickel oxide nanoparticles in gill, intestine, liver, and kidney of the fish was determined by killing half of them in each group and dissecting their tissues. The remaining fish were placed in clean water for another 28 days and the Depuration rate was estimated. FINDINGS: The LC50-96 values reported for nickel oxide nanoparticles, nickel sulfate, nickel nitrate and nickel chloride were 195, 120, 138 and 91 milligrams per liter, respectively. Therefore, nickel chloride had a higher toxicity compared to nickel oxide nanoparticles, nickel sulfate and nickel nitrate. The highest rate of nickel oxide nanoparticles bioaccumulation was observed in the gill (0. 40±, 0. 08 microgram per gram), intestine (41. 82±, 16. 95 microgram per gram), liver (2. 16±, 1. 82 microgram per gram), and kidney (2. 16±, 1. 26 microgram per gram) of the fish. The highest Depuration rate of nickel oxide nanoparticles, nickel sulfate, nickel nitrate, and nickel chloride was recorded in the intestinal tissue of the fish. The lowest Depuration rate of nickel oxide nanoparticles, nickel sulfate and nickel nitrate was observed in the kidney tissue of the fish. Also, the lowest Depuration rate of nickel chloride was witnessed in the gill tissue of the fish. Histopathological anomalies were detected in the fish exposed to nickel oxide nanoparticles. These anomalies were fusion of lamellae, lamellar synechiae, curvature and oedema in the gill,increased number of goblet cells and cell swelling,and degradation of villi structure and expansion of villi structure in the intestine. CONCLUSION: The study conclusively demonstrated that nickel oxide nanoparticles were ecotoxic and harmful to aquatic organisms. Strong global nickel oxide nanoparticles regulations must be enforced to prevent further environmental contamination with nanoparticles.

Background: Paraquat dichloride is a highly toxic herbicide which is still used in many developing countries. African cat fish (Clarias gariepinus) is a commercially important species in many countries and was selected assess accumulation and elimination of paraquat dichloride in its tissues.Methods: Groups of ten fish with equal lengths and weights were exposed to varying concentrations of Paraquat dichloride for 28 days. After the exposure, the fish were transferred to uncontaminated water. Two fish were sampled for pesticide residue at the end of exposure period (28days) and 1, 7 and 14 days post exposure.Results: In pesticide treated fish, the accumulation of paraquat increased with increases in the concentration of the toxicant and varied significantly between the treatments (p<0.05). The herbicide depurated gradually with cessation of exposure and no pesticide was observed after 14 days.Conclusion: Xenobiotics could be eliminated from aquatic organisms especially fishes and could be put into practice in areas at risk of pollutants. This novel approach can reduce the risks of biomagnification of poisons in sea food.

Background: This study aims to investigate the patterns of bioaccumulation and Depuration of copper in the selected kidney and liver of Capoeta fusca.Methods: The fish were collected between September and November 2010 from a qanat in Birjand. They were exposed to two types treatments with copper (0.25 and 0.75 mg/L) for a period of 41 days. The fish under study were exposed to the above-mentioned sub-lethal concentrations separately for 14 and 21 days (accumulation period). At the end of this period, the remaining fish were kept in tap water (elimination period) for 31 and 41 days.Results: The findings showed that the accumulation of copper in lower and higher sub-lethal concentrations was higher in kidney as the mean accumulation of copper on day 21 was 1.9±0.1 μg/g and 2.93±0.47 mg/g respectively, in 0.25 mg/g and 0.75 mg/g concentrations. On the other hand, the results also showed that the Depuration level of copper in the given concentrations was higher in liver than kidney. The bioaccumulation and Depuration of copper significantly increased in the kidney and liver of C. fusca (P<0.01).Conclusion: Based on the present work, it is concluded that C. fusca has a potential for the rapid accumulation and Depuration of copper in freshwater. Also, the results indicate that the fish C. fusca, as representative fish species in the East of Iran, can be a useful bioindicator organism of water contamination with copper.

Objective: The toxic effects of sublethal concentrations of endosulfan on Oreochromis niloticus was examined using bioaccumulation and histopathology studies of the liver as toxicological endpoint.Methods: The Organization for Economic Cooperation and Development #407 recommended static renewal bioassay was employed during the test. The test fish were exposed to sub-lethal concentrations separately for a period of 7, 14, 21, and 28 days. At the end of each exposure period the liver tissues were isolated and analyzed using high performance liquid chromatography for bioaccumulation study, while alterations observed in exposed fish were determined in the laboratory by light microscopy using standard technique of Haematoxylin and Eosin staining.Results: No mortalities occurred in any group during the test. The severity of the histological alterations observed in the liver of the treated fish reflects the concentrations of the toxicant, level of Depuration and exposure durations. An indication that the regulating mechanisms of the liver has been overwhelmed resulting in the structural damages. The findings showed that the body could be liberated of contaminants after longer exposure period however, the effects on the body’s tissues remain lethal.