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The Editor-in-Chief and the publisher have retracted this article. 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 Editor-in-Chief therefore no longer has confidence in the results and conclusions of this article.

The author Mahmoud Mohamed Selim disagree with this retraction. The author Alibek Issakhov has not responded to correspondence regarding this retraction. The Publisher has not been able to obtain a current email address for the author Songhong Wei. The online version of this article contains the full text of the retracted article as Supplementary Information.