2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/152131We use Furuta's result, usually referred to as ``10/8-conjecture'', to show that for any compact 3-manifold $M$ the open manifold $M\times\r$ has infinitely many different smooth structures. Another consequence of Furuta's result is existence of infinitely many smooth structures on open topological 4-manifolds with a topologically collarable end, provided there are only finitely many ends homeomorphic to it. We also show that for each closed spin 4-manifold there are exotic \rf's that can not be smoothly embedded into it.8 pages, AMSTeX, no figuresDifferential Geometrytext