Micromechanical properties and structural characterization of modern inarticulated brachiopod shells
Micromechanical properties and structural characterization of modern inarticulated brachiopod shells
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现代铰接腕足动物壳的微机械特性和结构表征
DOI：
10.1029/2006jg000253
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发表时间：
2007
影响因子：
--
通讯作者：
Schmahl W.W.
中科院分区：
文献类型：
--
作者：
Merkel C;Griesshaber E;Kelm K;Neuser R.D;Jordan G;Logan A;Mader W;Schmahl W.W.
利用扫描电子显微镜（SEM）、能谱仪（EDX）、透射电子显微镜（TEM）和维氏显微硬度压痕分析，研究了现代腕足动物鸭舌（Lingula anatina）、光滑盘鱼（Discinisca laevis）和星盘鱼（Discradisca stella）贝壳的显微力学性质和超微结构。壳由两个不同的层组成，外部初级层和内部次级层。除鸭舌壳的初生层完全由有机质组成外，其余壳层均为有机/无机层状复合物。有机物由甲壳素纤维构成，甲壳素纤维为磷酸钙的结合提供基质。无定形磷酸钙在外层，初级层和结晶磷灰石沉积到内部，次级层的外壳。在壳的隆起区域的磷灰石微晶尺寸约为50 × 50 nm，而在阀内的微晶尺寸明显较小，平均为10 × 25 nm。壳层之间和所调查的腕足类物种之间的硬度值有很大的变化。所研究的壳的显微硬度显着低于无机羟基磷灰石。这是由主要的有机材料成分引起的，在这些壳中，有机材料成分或者发展为纯有机层，或者发展为由微晶增强的有机纤维基质。我们的研究结果表明，这种特殊的纤维复合材料是非常有效的保护和支持的软动物组织。它降低了裂纹形成的可能性，并通过裂纹偏移机制有效阻止裂纹垂直于壳体扩展。高机械稳定性和韧性通过两个设计特征实现。第一，纤维复合材料克服了单一成分的一些不利性质，并增强了单一成分的一些有利性质，即甲壳素的柔软性和柔韧性以及磷灰石的硬度和脆性。第二，从纳米到微米级存在层次结构。我们可以在外壳中识别出至少七个层次。
We investigated micromechanical properties and ultrastructure of the shells of the modern brachiopod speciesLingula anatina,Discinisca laevis, andDiscradisca stellawith scanning electron microscopy (SEM, EDX), transmission electron microscopy (TEM) and Vickers microhardness indentation analyses. The shells are composed of two distinct layers, an outer primary layer and an inner secondary layer. Except for the primary layer inLingula anatina, which is composed entirely of organic matter, all other shell layers are laminated organic/inorganic composites. The organic matter is built of chitin fibers, which provide the matrix for the incorporation of calcium phosphate. Amorphous calcium phosphate in the outer, primary layer and crystalline apatite is deposited into the inner, secondary layer of the shell. Apatite crystallite sizes in the umbonal region of the shell are about 50 × 50 nm, while within the valves crystallite sizes are significantly smaller, averanging 10 × 25 nm. There is great variation in hardness values between shell layers and between the investigated brachiopod species. The microhardness of the investigated shells is significantly lower than that of inorganic hydroxyapatite. This is caused by the predominantly organic material component that in these shells is either developed as purely organic layers or as an organic fibrous matrix reinforced by crystallites. Our results show that this particular fiber composite material is very efficient for the protection and the support of the soft animal tissue. It lowers the probability of crack formation and effectively impedes crack propagation perpendicular to the shell by crack‐deviation mechanisms. The high degree of mechanical stability and toughness is achieved by two design features. First, there is the fiber composite material which overcomes some detrimental and enhances some advantageous properties of the single constituents, that is the softness and flexibility of chitin and the hardness and brittleness of apatite. Second, there is a hierarchical structuring from the nanometer to a micrometer level. We could identify at least seven levels of hierarchy within the shells.
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腕足动物 (Inarticualte Brachiopod) 外壳的超微结构和矿化
DOI：
--
发表时间：
1981
期刊：
影响因子：
--
作者：
K. Iwata
通讯作者：
K. Iwata
影响因子：
3
作者：
Prockop, DJ;Fertala, A
通讯作者：
Fertala, A
影响因子：
2.9
作者：
Vivi Ziv;S. Weiner
通讯作者：
Vivi Ziv;S. Weiner
腕足动物壳的微观结构——具有纳米晶保护层的无机/有机纤维复合材料
DOI：
10.1557/proc-844-y9.3
发表时间：
2004
期刊：
MRS Proceedings
影响因子：
--
作者：
E. Griesshaber;W. Schmahl;R. Neuser;R. Job;M. Bluem;U. Brand
通讯作者：
U. Brand
盘类腕足动物壳的化学结构系统发育
DOI：
--
发表时间：
1998
期刊：
影响因子：
--
作者：
Alwyn Williams;M. Cusack;J. Buckman
通讯作者：
J. Buckman