Calculation of exact sample size is an important part of research design. It is very important to understand that different study design need different method of sample size calculation and one formula cannot be used in all designs. In this short review we tried to educate researcher regarding various method of sample size calculation available for different study designs. In this review sample size calculation for most frequently used study designs are mentioned. For genetic and microbiological studies readers are requested to read other sources.

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Results have implications for improved leishmanicidal action of Qr in combination with SA targeting RR and suggest future drug design based on interference with the parasite's iron metabolism under in vivo conditions.

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The present paper puts forth the complete characterization of effluents produced at various leather processing stages of three selected tannery industries, and of composite effluents at three selected monitoring points (P 1 , P 2 and P 3 ) located at Hazaribagh leather industrial zone in Bangladesh. The analysis results show that the effluents possess extremely high values of TSS, EC, TDS, TS, BOD 5 and COD, and high concentrations of SO 4 2− , Na, Cl , BOD 5 , COD, Na, Cr, As, Cd and Pb in the collected composite tannery effluents, at all monitoring points, were also above the standard disposal limits. The pollutant levels observed at the three monitoring points were in the order P 1 >P 2 >P 3 indicating pollution level decreasing with distance. The study also revealed that the concentrations of various metal ions in the sludge were very high, and the concentrations of Cr and Na ions in particular were about 10,000 and 6000 mg/kg, respectively. The concentrations of chemicals in the sludge were in the order: Cr>Na>Ca>S>Mg>P>Cu>TN>Zn>Organic compound>Pb>As>Cd. So, it is concluded that the leather industrial effluent was highly polluted and not suitable for irrigation or any other uses.