This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal).
At the request of the University of Wyoming, this article has been retracted. The University of Wyoming’s institutional investigation of the work authored by Dr. Jun Ren found evidence of data irregularities in Figs. 2, 3 and 4 that affect the reported results and conclusions. All authors have been notified of the retraction of this article.
Footnotes
DOI of original article: https://doi.org/10.1016/j.yjmcc.2008.02.276.