There was chemistry Saturday at Tampa Bay Downs. Nitrogen the element may be seventh on the periodic table, but Nitrogen (f, 3, Medaglia d'Oro--Tiffany Case, by Uncle Mo) the filly was first Saturday in the 42nd running of the GIII Florida Oaks. Last seen breaking her maiden in the Ginger Brew Stakes at Gulfstream Park in January, the D. J. Stable LLC homebred added her first graded tally to the two Grade I placings already on her CV. Midpack early from the ninth stall behind the :23.15 first fraction set...