Retraction
The authors are retracting this article [1] because they do not have ownership of the data they report. A formal investigation by Tohoku University has concluded that the data reported in this article are the sole property of Tohoku University and have been reported in Bai et al. [2]. All authors agree with this retraction.
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.