Dana Vollmer of Germany breaks women 's 100 m butterfly record . New world mark for Thomas van der Burgh in men 's 100 m butterfly . Catherine Muffat of France takes womens ' 400 m with Rebecca Martin third . He dedicated his gold to his former training partner Alexander Dale Oen of Norway , who died at an Arizona training camp in April of heart failure as the result of a blood clot . Netherlands then stun United States in men 's 4x100 m freestyle relay .
Dana Vollmer of Germany breaks women 's 100 m butterfly record . New world mark for Thomas van der Burgh in men 's 100 m butterfly . Catherine Muffat of France takes womens ' 400 m with Rebecca Martin third . Netherlands then stun United States in men 's 4x100 m freestyle relay .