Figure 6

(a) TEM thickness maps of C. sp. valves grown at different Al³⁺ concentrations (scale bar = 5 µm); (b) thickness maps of porous areas (scale bar = 500 nm); (c) bar graphs of thickness measurements of porous area, raphe and whole valve (n = 5 valves per culture). Error bars indicate standard deviations.* Indicates p ≤ 0.05.