Helium and Iron in X-ray galaxy clusters
  I discuss the role of the sedimentation of helium in galaxy cluster cores on the observed X-ray properties and present a history of the metal accumulation in the ICM, with new calculations with respect to my previous work following the recent evidence of a bi-modal distribution of the delay time in Supernovae Type Ia. 
Stefano Ettori (INAF-OA Bologna)