Figure 4.

Typical APA inner surface, in which the closed pore bottoms have been partly opened by immersion in 1 M oxalic acid at 30 °C for 30 min, in the following conditions:aAPA after cleaning only andbAPA after cleaning and keeping in 10% IL2 aqueous solution for 10 min. Both images have been smoothed with a 3x3 kernel Gaussian filter

Salerno et al. Nanoscale Research Letters 2009 4:865-872   doi:10.1007/s11671-009-9337-3