title: Uncovering three-dimensional gradients in fibrillar orientation in an impact-resistant biological armour.
abstract: The complex hierarchical structure in biological and synthetic fibrous nanocomposites entails considerable difficulties in the interpretation of the crystallographic texture from diffraction data. Here, we present a novel reconstruction method to obtain the 3D distribution of fibres in such systems. An analytical expression is derived for the diffraction intensity from fibres, explaining the azimuthal intensity distribution in terms of the angles of the three dimensional fibre orientation distributions. The telson of stomatopod (mantis shrimp) serves as an example of natural biological armour whose high impact resistance property is believed to arise from the hierarchical organization of alpha chitin nanofibrils into fibres and twisted plywood (Bouligand) structures at the sub-micron and micron scale. Synchrotron microfocus scanning X-ray diffraction data on stomatopod telson were used as a test case to map the 3D fibre orientation across the entire tissue section. The method is applicable to a range of biological and biomimetic structures with graded 3D fibre texture at the sub-micron and micron length scales.
authors.affiliation: Queen Mary University of London, School of Engineering and Material Science, London, E1 4NS, UK.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Institute of Physics, Montanuniversitaet Leoben, Leoben, Austria.
authors.forename: O
authors.initials: O
authors.lastname: Paris
authors.affiliation: Diamond Light Source, Harwell Science and Innovation Campus, Harwell, UK.
authors.forename: N J
authors.initials: NJ
authors.lastname: Terrill
authors.affiliation: Queen Mary University of London, School of Engineering and Material Science, London, E1 4NS, UK.
authors.forename: H S
authors.initials: HS
authors.lastname: Gupta
mesh_terms: D060105:Animal Shells / Q000737:chemistry / Q000648:ultrastructure; D000818:Animals; D002686:Chitin / Q000737:chemistry* / Q000648:ultrastructure; D003198:Computer Simulation; D003445:Crustacea / Q000737:chemistry; D021621:Imaging, Three-Dimensional; D008855:Microscopy, Electron, Scanning; D008958:Models, Molecular; D053761:Nanocomposites / Q000737:chemistry / Q000648:ultrastructure; D057139:Nanofibers / Q000737:chemistry / Q000648:ultrastructure; D017356:Synchrotrons; D014961:X-Ray Diffraction
chemical_list: D002686:Chitin