  Let $G$ be a simple graph and $Q(G)$ be the signless Laplacian matrix of $G$.
Let $S_\alpha(G)$ be the sum of the $\alpha$-th powers of the nonzero
eigenvalues of $Q(G)$. We disprove two conjectures by You and Yang on the
extremal values of $S_\alpha(G)$ among bipartite graphs and among graphs with
bounded connectivity.
