[Q] The problem of energy loss had been a famous problem that Bohr had worked on and...

Yes, in fact the old theory of energy loss was initiated by Bohr about the same time as he found the old quantum theory and it's a beautiful paper, Bohr's paper, and his formula differs from mine in a just a very slight extent. But Bohr was very intrigued by that and he asked Felix Bloch to look into this: Why is it different? And Bloch then succeeded in making the connection between the classical formula of Bohr and my quantum formula and he found that for very slow electric particles, especially those of high charge, the old classical theory is right; and then for fast particles, my quantum theory is right, and Bloch succeeded in getting the... in bridging the two.