We adress tno aspects of D-branes physics. The first regards the interaction between two electromagnetic dual D-branes in 10 dimensions. In particular, we give a meaning to both even and odd spin structure contributions, the latter being non vanishing and encoding the Lorentz-like contribution. The second aspect regards the D-brane/black holes correspondence. We show how the 4 dimensional configuration corresponding to a single D3-brane wrapped on T-6/Z(3) represents a regular solution of d=4N=2 supergravity.
