Relations of different ratios involving Ne IR emission-lines with O/H and log(U). (a) Relation between the Ne235 estimator, using H I 4 μm, and 12+ log(O/H) in our sample. The colorbar shows estimations of log(U). (b) Relation between estimator Ne23Ne5 and log(U) in our sample. The colorbar shows estimations of 12+log(O/H). For both plots, blank points indicate that no estimation can be provided of the colored quantity. AGN models for a fixed value of log(N/O) = −1.0 are presented as continuous lines, while dashed lines correspond to SFG models for the same fixed value. The following spectral types are represented: Seyferts 2 as circles; ULIRGs as squares; LIRGs as triangles; and LINERs as stars.