Laws of thermodynamics do not prevent the possibility of extracting work from systems that are isothermic and in a stationary state as long as these are not at equilibrium. These states require something similar to a spontaneous breaking of symmetry and these pertain to the realm of Brownian motors.

Macroscopic realizations have been developed in the field of granular mechanics, a field of great relevance both industrially [due to the ubiquity of granular materials (GMs)] and theoretically (for the challenging properties and behavior generally exhibited by GMs).

A new realization of a granular ratchet has been completed in collaboration with A. Puglisi and A. Gnoli at the Physics Dept. of the University La Sapienza ( Gnoli et al.  Phys. Rev. Lett. 110, 120601 (2013),  Phys Rev. E 87, 052209, (2013) )

Previously  we had realized in our laboratory, in collaboration with R. Balzan and V. Loreto from La Sapienza, an experimental apparatus ( Balzan et al., Phys Rev. E 83, 031310 (2011)) in which a ratchet probe is immersed in a vibrated dense granular, in order to study how chaotic granular motion can indeed propel an asymmetric probe in a persistent direction. More recently, in collaboration with A. Gnoli (ISC Tor Vergata) and A. Puglisi (ISC La Sapienza) a gas granular version of the experiment has been realised and is currently under investigation. See the movie.

The failure of materials is a complex and complicated process exhibiting broad phenomenology. The fracture of heterogeneous media under slow external loading displays intermittency  and scale invariance in both dynamical and morphological quantities. In Pontuale et al., EPL 101, 16005 (2013) we have shown that the intermittent and self-similar fluctuations displayed by a slow crack during the propagation in a heterogeneous medium can be quantitatively described by an extension of a classical statistical model for fracture. The model yields the correct dynamical and morphological scaling, and allows to demonstrate that the scale invariance originates from the presence of a non-equilibrium, reversible, critical transition which, in the presence of dissipation, gives rise to self-organized critical behaviour.