High resolution X-ray tensor tomography to study the spiral nanostructure of narwhal tusk

Narwhals are mysterious animals whose tusk has a unique spiral structure with highly anisotropic mechanical properties. We hypothesize that the orientation of the biological nanostructure reflects the spiral macro-structure, which defines their mechanical properties. Previous experiments showed important aligned structures in the micrometric range however the achievable resolution was not enough to fully resolve them. Therefore, we propose to use SWAXS to study the orientation and degree of anisotropy of the biomineral nanoparticles in the tusk in 2D and 3D. Examining samples from dentine and cementum will reveal the unique structure and shed light on its formation process. The 3D hierarchical structure will be very valuable for micromechanical modelling of anisotropic composites, which will bring new knowledge on composite materials with complex architectures and inspire new material designs.

独角鲸（Narwhal）是一类神秘的生物，其象牙具备独特的螺旋状结构，并拥有高度各向异性的力学性能。我们提出如下假说：生物纳米结构的取向能够反映决定其力学性能的螺旋宏观结构。过往的实验已在微米尺度下观测到了显著的有序结构，但受限于当时可达到的成像分辨率，无法对这些结构进行完整解析。因此，我们提出采用小角X射线散射（SWAXS）技术，从二维和三维层面研究象牙中生物矿化纳米颗粒的取向特性与各向异性程度。对牙本质（dentine）与牙骨质（cementum）样本的检测分析，将揭示其独特结构，并阐明其形成过程。这种三维分级结构对于各向异性复合材料的微力学建模具有重要价值，将为复杂架构复合材料的研究提供新的认知，并为新型材料设计提供灵感。