Mazhar Hussain

Radiation effects on the thermal boundary layer flow of a micropolar fluid towards a permeable stretching sheet

Abstract In this article, radiation effects on the unsteady boundary layer flow of a micropolar fluid over a stretching sheet are reported. The sheet is considered to be permeable and the problem is nondimensionalized by using similarity transformations. The resulting problem is solved analytically by the homotopy analysis method (HAM) and different interesting flow parameters are explained through graphical results. The convergence of the obtained solutions is checked by displaying ħ -curves in which the auxiliary parameter ħ plays an important role to ensure the convergence of the series solutions.

Optimization of extraction efficiency of tannins from Cichorium intybus L.: Application of response surface methodology

2-factorial central composite design was employed by using response surface methodology to optimize the extraction conditions. The analysis of variance showed the significant effect of both variables on the extraction yield of tannins. The lower P-values (P < 0.05) indicated the positive significant effect of both variables on the extraction of tannins from different parts of C. intybus. The values of correlation coefficient (R 2 ) indicated that more than 96% of the variability in tannins content of C. intybus could be explained by response surface model. The 3D surface plots showed a quadratic effect of methanol concentration and linear effect of time on the extraction efficiency of tannins from C. intybus. The optimum tannins yield of 0.607, 0.529, 0.26, and 0.431 g/100 g dry weight from root, stem, leaves, and seeds of C. intybus, respectively was observed at 60% methanol concentration and extraction time of 80 min. Moreover, the data suggests that C. intybus is a rich source of tannins and can be preferably used to fulfil the requirements of tannins in medicinal field.