. 2010 Aug 20;6(1):4. doi: 10.1007/s11671-010-9741-8
Copyright ©2010 Chen et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.