Scientific Reports 3, Article number: 3048 (2013); Published: 25 October 2013; Updated: 17 December 2013

This Article contains errors in the Acknowledgments section. The Acknowledgements should read: “This work is partly supported by the National Basic Research Program of China (Grant No. 2012CB932302 and 2014CB848900), the National Natural Science Foundation of China (51172271, 51372269, 90921012 and U1232131), the strategic science and technology project of Chinese Academy of Sciences, Beijing Municipal Education Commission (Grant No. YB20108000101) and the Fundamental Research Funds for the Central Universities (WK2310000035).”