Histopathology of Clarias gariepinus juveniles exposed to aqueous and ethanolic extracts of Parkia biglobosa pod.

The toxicity of aqueous and ethanol extracts of Parkia biglobosa pods (95mg/l, 85mg/l, 75mg/l, 65mg/l and 55mg/l) on Clarias gariepinus was investigated under laboratory condition over a 96h exposure period. The effect of aqueous and ethanolic extracts of Parkia biglobosa pod on the histopathology of liver of the fresh water Cat fish (Clarias gariepinus) was investigated. The differential acute toxicity of aqueous and ethanolic extracts of Parkia biglobosa pod on Clarias gariepinus were carried out under laboratory conditions. The LC50 after 96 h of exposure for aqueous and ethanolic extracts of Parkia biglobosa were 2.95 and 2.23 g/L, respectively. These values showed that ethanolic extract of Parkia biglobosa pod was more toxic than its aqueous extract. Signs of agitated behaviours, respiratory distress and abnormal nervous behaviours including eventual deaths were observed in exposed fish. Control fish neither died nor exhibited any unusual behaviour. Histopathological changes of liver was noticed when Clarias gariepinus was exposed to aqueous extract of Parkia biglobosa for 96 h. Liver from exposed fish showed congestion, perivascular cuffing, vacuolation, dilated sinusoidal spaces, necrosis, pyknosis and mononuclear cell infiltration. Fish from the control group showed no histopathological changes. However clinical signs and death were more in fish exposed to the ethanol extracts. This investigation revealed that extract from pod of Parkia biglobosa has piscicidal property and can be put into use in the control and management of fish ponds by farmers. Therefore, this plant can actually be use as a biological control in eradicating predators and unwanted organisms in the ponds by farmer instead of using agrochemicals.Key words: Histopathology, Parkia biglobosa, Clarias gariepinus

Drying Kinetics in Solar Drying

From ancient times foods such as fruit, vegetables, meat or fish were dried by direct sunlight. The use of the sun as energy source is advantageous from the economic as well as environmental points of view. However, this procedure has many disadvantages concerning the efficiency and product safety and quality. The use of greenhouses can greatly minimize these problems Inside the greenhouses the air circulates by natural convection but they can also be equipped with chimneys for air outlet, thus increasing the airflow. In other cases, the efficiency of the drying system can be increased by incorporating a solar collector system, which uses panels for an efficient collection of the sun ray’s energy. Knowledge of the drying kinetics is of great importance for modeling the drying processes and to establish appropriate operating conditions. There are hundreds of mathematical models that were developed to represent the drying kinetics of foods, being mostly empirical, or semi-empirical or alternatively based on the Fick's second law of diffusion. This chapter presents the heat and mass transfer mechanisms that regulate the drying rate, the conditions in direct and indirect solar drying, the drying curves and the mathematical modeling of the solar drying processes, with application examples in various dominions.info:eu-repo/semantics/publishedVersio