public function eliminarCarga()
 {
     try {
         $idSalon = isset($_POST['idSalon']) ? $_POST['idSalon'] : NULL;
         $idMateria = isset($_POST['idMateria']) ? $_POST['idMateria'] : NULL;
         echo json_encode($idSalon);
         $c = new Carga();
         $c->eliminarCarga($idSalon, $idMateria);
         echo json_encode(1);
     } catch (Exception $exc) {
         echo json_encode('Error de aplicacion: ' . $exc->getMessage());
     }
 }