Energy bounds for entire nodal solutions of autonomous superlinear equations

We prove new lower bounds for the energy of sign changing solutions of two different types of autonomous superlinear equations on R-N. These bounds increase the energy range for which Palais-Smale sequences of related variational problems have a nontrivial weak limit. The results are obtained by transforming sign changing solutions of low energy into a convenient form and then applying different variants of the moving plane method.