BOSTON - With six quadruple jumps and an audacious backflip, U.S. figure skater Ilia Malinin captured his second straight world championships title in Boston on Saturday.Malinin was in the lead after Thursday's short program and he put the world on notice less than a year to go before the Milano Cortina Olympics with a stunning display of athleticism in Saturday's free skate for a total score of 318.56.Mikhail Shaidorov of Kazakhstan was second with 287.47, while Yuma Kagiyama of Japan (278.19) took bronze.