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S. Pabisch, S. Puchegger, H. Kirchner, H. Peterlik:
"Keratin homogeneity in the tail feathers of peacocks";
Talk: 75th Annual Meeting of the DPG and combined DPG Spring Meeting of the Condensed Matter Section and the Section AMOP, Technical University of Dresden, Germany; 2011-03-13 - 2011-03-18; in: "75th Annual Meeting of the DPG and combined DPG Spring Meeting of the Condensed Matter Section and the Section AMOP", (2011), BP 23.8.

X-ray diffraction studies successfully clarified the structure of avian feathers: Each filament has a helical structure with four repeating units per turn.[1] The structure of avian feathers is very stable though their relative density is low. The keratin structure in the cortex of peacocks´ feathers is studied by X-ray diffraction along the feather, from the calamus to the tip. It changes considerably over the first 5 cm close to the calamus and remains constant for about 1 m along the length of the feather. We attribute the X-ray patterns to a shrinkage of a cylindrical arrangement of beta-sheets, which is not fully formed initially. In the final structure, the crystalline beta-cores are fixed by the rest of the keratin molecule. The hydrophobic residues of the beta core are locked into a zip-like arrangement. Tensile and compression tests are additionally performed in-situ to follow the structural change as consequence of varying load.