highly significantp = 0.004
For D 3,2 , the linear ZnO term was highly significant (β 2 = −19.7 nm, p = 0.004), indicating progressively smaller droplets at higher ZnO levels, while the quadratic linseed oil term (β 11 = +15.3 nm, p = 0.012) revealed a curvature that penalised very high oil fractions.