2   Motivations
      Radical attack contribution to cellular death
      Survival / Dose with different     Degree of protection against 
      DMSO concentrations                DMSO concentration
                           DMSO ~ « anti-OH radical »
         Contributions of Direct and Indirect Actions in Cell Killing by High-
         LET Radiations, Hirayama et al, 2009
    Modeling the Physico-Chemistry & 
    Chemistry Stages
      Modeling water radiolysis ?
  5
       Physico-chemistry 
      Physico-chemistry                  Chemistry stage
       stage                             Chemistry stage
      stage
          -15                       -12                       -6
      t=10 s                    t=10 s                   t=10 s
         Physico-chemical stage
   6
          Physico-chemistry                              Ionised molecules convert into :
          Physico-chemistry 
          stage                                                      +                        +          ●
          stage                                                H2O + H2O  ►  H3O + OH
            •  Dissociation : 
           •   Dissociation : 
                      + 
                      + 
               HO*/  
               HO*/  
                 2
                2                                        Excited molecules relax or 
                           + °
                          + °
                     (H O , OH, e , H, H )
                    (H O , OH, e , H, H )
                        3            aq       2
                       3            aq       2              dissociate
            •  Thermalization of the 
           •   Thermalization of the 
               products:          all        the 
               products:          all        the 
               generated molecules slow 
               generated molecules slow 
               down  until  they  reach 
               down  until  they  reach 
               their energy of diffusion. 
               their energy of diffusion. 
               This slowing down is described 
               This slowing down is described 
               by  a  displacement  of  the 
               by  a  displacement  of  the 
               products    from    the    mother 
               products    from    the   mother 
               molecule’s position according to 
               molecule’s position according to 
               their respective mass. (cf. Kreipl   (From Kreipl et al, Radiat Environ Biophys, 2009)
               their respective mass. (cf. Kreipl 
               et al, REB, 2009)
               et al, REB, 2009)
                 -15                                       -12
         t=10 s                                    t=10 s