title: Structure-function relationships in Macadamia integrifolia seed coats--fundamentals of the hierarchical microstructure.
abstract: The shells/coats of nuts and seeds are often very hard to crack. This is particularly the case with Macadamia seed coats, known to exhibit astoundingly high strength and toughness. We performed an extensive materials science characterization of the complex hierarchical structure of these coats, using light and scanning electron microscopy in 2D as well as microCT for 3D characterization. We differentiate nine hierarchical levels that characterize the structure ranging from the whole fruit on the macroscopic scale down to the molecular scale. From a biological viewpoint, understanding the hierarchical structure may elucidate why it is advantageous for these seed coats to be so difficult to break. From an engineering viewpoint, microstructure characterization is important for identifying features that contribute to the high strength and cracking resistance of these objects. This is essential for revealing the underlying structure-function-relationships. Such information will help us develop engineering materials and lightweight-structures with improved fracture and puncture resistance.
authors.affiliation: Materials Engineering, Technische Universität Berlin, Berlin, Germany.
authors.forename: Paul
authors.initials: P
authors.lastname: Schüler
authors.affiliation: Plant Biomechanics Group Freiburg, Botanic Garden, Faculty of Biology, University of Freiburg, Freiburg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Speck
authors.affiliation: Foundry-Institute, RWTH Aachen, Aachen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Bührig-Polaczek
authors.affiliation: Materials Engineering, Technische Universität Berlin, Berlin, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Fleck
mesh_terms: D039106:Macadamia / Q000648:ultrastructure*; D008422:Materials Testing; D055595:Mechanical Phenomena; D008855:Microscopy, Electron, Scanning; D012639:Seeds / Q000648:ultrastructure*; D013329:Structure-Activity Relationship
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