Mechanical properties and the laminate structure of Arapaima gigas scales
Mechanical properties and the laminate structure of Arapaima gigas scales
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DOI：
10.1016/j.jmbbm.2011.03.024
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发表时间：
2011-10-01
影响因子：
3.9
通讯作者：
Meyers, Marc A.
中科院分区：
文献类型：
--
作者：
Lin, Y. S.;Wei, C. T.;Meyers, Marc A.
在保护这种大型亚马逊河流域鱼类免受食人鱼等掠食者的攻击方面，Arapaima gigas鳞片发挥着重要作用。它们具有层状复合结构，由外部矿化层和内部层组成，每个层的厚度为50-60 μ m，并由直径约为1 μ m的胶原纤维组成。胶原纤维的排列在每个单独的层中是一致的，但在层与层之间是不同的，形成非正交的胶合板结构，称为Bouligand堆叠。X射线衍射分析表明，鳞片的外表面含有缺钙的羟基磷灰石。EDS结果证实，钙的百分比在外层中较高。外层的显微压痕硬度（550 MPa）显著高于内层的显微压痕硬度（200 MPa），这与其较高的矿化度相一致。在干燥和潮湿条件下进行的鳞片的拉伸测试表明，强度和刚度是水化依赖的。与大多数生物材料的情况一样，鳞片的弹性模量是应变率相关的。由Ramberg-Osgood方程表示的弹性模量的应变率依赖性等于0.26，约为骨的10倍。这归因于鳞片中胶原蛋白的较高分数和高度水合（30%H2O）。鳞片的脱蛋白揭示了由厚度类似于50 nm且直径类似于500 nm的血小板的互连网络组成的矿物质组分的结构。(C)2011爱思唯尔有限公司保留所有权利。
The Arapaima gigas scales play an important role in protecting this large Amazon basin fish against predators such as the piranha. They have a laminate composite structure composed of an external mineralized layer and internal lamellae with thickness of 50-60 mu m each and composed of collagen fibers with similar to 1 mu m diameter. The alignment of collagen fibers is consistent in each individual layer but varies from layer to layer, forming a non-orthogonal plywood structure, known as Bouligand stacking. X-ray diffraction revealed that the external surface of the scale contains calcium-deficient hydroxyapatite. EDS results confirm that the percentage of calcium is higher in the external layer. The micro-indentation hardness of the external layer (550 MPa) is considerably higher than that of the internal layer (200 MPa), consistent with its higher degree of mineralization. Tensile testing of the scales carried out in the dry and wet conditions shows that the strength and stiffness are hydration dependent. As is the case of most biological materials, the elastic modulus of the scale is strain-rate dependent. The strain-rate dependence of the elastic modulus, as expressed by the Ramberg-Osgood equation, is equal to 0.26, approximately ten times higher than that of bone. This is attributed to the higher fraction of collagen in the scales and to the high degree of hydration (30% H2O). Deproteinization of the scale reveals the structure of the mineral component consisting of an interconnected network of platelets with a thickness of similar to 50 nm and diameter of similar to 500 nm. (C) 2011 Elsevier Ltd. All rights reserved.