This article has been retracted: please see Elsevier policy on article withdrawal (https://www.elsevier.com/about/policies-and-standards/article-withdrawal). This article has been retracted at the request of the Editor. An investigation conducted on behalf of the journal by Elsevier's Research Integrity & Publishing Ethics team found a significant increase of citations to papers published by the authors, Alex V. Trukhanov and Sergei V. Trukhanov, between the original submission and the revised version of this article. In summary, no papers by the authors were cited in the original version of the article. This increased to eleven papers in the revised version of the article. Further to the above concern, the Editor has determined that the authors were requested by one of the reviewers to insert redundant references to their paper during the peer-review process. The Editor has lost confidence in the findings of the article and has determined that it should be retracted. The authors have not responded to the retraction notice.