We consider the nonlinear Schrödinger equation in dimension and in the mass supercritical and energy subcritical range . For initial data with radial symmetry, we prove a universal upper bound on the blow-up speed. We then prove that this bound is sharp and attained on a family of collapsing ring blow-up solutions first formally predicted in Fibich et al.
"On collapsing ring blow-up solutions to the mass supercritical nonlinear Schrödinger equation." Duke Math. J. 163 (2) 369 - 431, 1 February 2014. https://doi.org/10.1215/00127094-2430477