['We', 'investigate', 'the', 'density', 'behavior', 'of', 'the', 'symmetry', 'energy', 'with', 'respect', 'to', 'isospin', 'equilibration', 'in', 'the', 'combined', 'systems', 'Ru(Zr)+Zr(Ru', ')', 'at', 'relativistic', 'energies', 'of', '\xa0', '0.4', 'and', '1.528A', '\xa0', 'GeV.', 'The', 'study', 'is', 'performed', 'within', 'a', 'relativistic', 'framework', 'and', 'the', 'contribution', 'of', 'the', 'iso', '-', 'vector', ',', 'scalar', 'δ', 'field', 'to', 'the', 'symmetry', 'energy', 'and', 'the', 'isospin', 'dynamics', 'is', 'particularly', 'explored', '.']