Scientific Reports 5: Article number: 13639; published online: 09 September 2015; updated: 14 December 2015

In the Supplementary Information originally published with this Article, there was a typographical error in Table S1: ‘CO3’ now reads ‘CO32–’. This error has been corrected in the Supplementary Information that now accompanies the Article.

In addition, a proof of the Article was inadvertently published as Supplementary Information. This has now been removed.