highly significantp < 0.0001
The established regression model was highly significant ( p < 0.0001), the misfit term was not significant ( p > 0.05), and the correlation coefficient of the model, R 2 = 0.9909, and the corrected correlation coefficient, R 2 adj = 0.9791, indicated that the model was well fitted and the experimental error was small ( Table 2 ).