“…In particular, the first studies have been devoted to the matrix formulation of the gradient-flux relationships (see [23] and the references therein). Subsequently, the wellposedness and the long-time behavior of the solutions of the Maxwell-Stefan system (or some variants) have been studied in [11,14,16,25,28,29], the numerical simulation of the Maxwell-Stefan system has been the subject of [9,14,22,32], and the relationships between Fickian diffusion and the Maxwell-Stefan model have been analyzed in [12,37]. By following the research line initiated by Bardos, Golse and Levermore in the Nineties -whose goal was the derivation of the equations of fluid mechanics starting from the Boltzmann equation [2,3] -several articles have carried out the formal derivation of isothermal multicomponent Maxwell-Stefan type diffusion equations starting from the Boltzmann system for monatomic non-reactive gaseous mixtures [12,13,15,26,27].…”