Weakly Closed Unipotent Subgroups in Chevalley Groups
  The goal of this note is to classify the weakly closed unipotent subgroups in the split Chevalley groups. In an application we show under some mild assumptions on the characteristic that the Lie algebra of a connected simple algebraic group fails to be a so called 2F-module. 
R. Guralnick, G Roehrle