The Publisher has retracted this article in agreement with the Editor-in-Chief. The article was submitted to be part of a guest-edited issue. An investigation by the publisher found a number of articles, including this one, with a number of concerns, including but not limited to compromised editorial handling and peer review process, inappropriate or irrelevant references or not being in scope of the journal or guest-edited issue. Based on the investigation's findings the publisher, in consultation with the Editor-in-Chief therefore no longer has confidence in the results and conclusions of this article.

Y. A. Nanehkaran, Defu Zhang, Yuan Tian and Najla Al-Nabhan have not responded to correspondence regarding this retraction. The Publisher has not been able to obtain a current email address for Junde Chen.

The online version of this article contains the full text of the retracted article as Supplementary Information.