It's not easy to drive long molecule chains – such as DNA – through a "nanopore" (a pore which is just few millionths of a millimeter wide) because they tend to tangle up.
A simulation carried out by an international group of scientists – among whom are SISSA researchers – has suggested a solution: it's better to "pull" gently without applying too much force, otherwise the molecule could be stopped due to excessive friction. That is an important observation to create innovative DNA sequencing methods.