Neutron isn't "responsible for the strong force"
The strong force acts between quarks, and is mediated by gluons (collectively, "glue"). Neutrons are composed of quarks (two down and an up). But so are protons. In fact, as far as the strong nuclear force is concerned there's very little difference between a neutron and a proton (this similarity is called isospin symmetry).
The interesting thing here is the implication that the the two negatively charged particles (the down quarks) are in orbitals above and below the up (positively-charged) quark. Maybe. I haven't read the paper.