  We show scattering below the ground state energy level for a class of
nonlinear 3D Schr\"odinger equations (NLS) with mass-energy intracritical
competing nonlinearities. Specifically, the NLS has a focusing leading order
nonlinearity with a defocusing perturbation. Our strategy combines interaction
Morawetz estimates and a new crucial bound for the Pohozaev functional of
localized functions. Furthermore, we give the rate of blow-up for symmetric
solutions.
