Scientific Reports 1, Article number: 18 (2011); Published: 20 June 2011; Updated: 18 April 2013

The authors have noticed that in the original version of this Article there was a typographical error in the Results section. The value quoted in the text for the fitting parameter C (1.5 × 10−14) is actually the value of the function C/(1 + d/d0)n for particles with d = 20 nm, as plotted in Figure 5b. The correct value for the diameter-independent parameter C alone is C = (8.8 ± 0.4) × 10−14. A similar normalisation error occurred in the quoted value of the parameter B, whose correct value is B = (1.5±0.08) × 10−14. This error only affected these values as quoted in the text and all figures and other comparisons made use of the correct parameters.