猛犸牙与象牙的微生长结构及红外吸收光谱的差异性

Differences on Growth Microstructure and FTIR Absorption Spectra between Mammoth Teeth and Ivory

猛犸象属古脊椎动物,其现存的猛犸牙多呈半化石状态。采用SEM,FTIR等分析测试仪器对猛犸牙和象牙的微生长结构、胶原蛋白等差异特征进行了研究。结果表明,象牙和猛犸牙主要由胶原蛋白和羟基磷酸钙组成,由胶原蛋白酰胺键致特征的红外吸收谱带分别位于1 663 cm-1(νC-O),1 558 cm-1(νC-H)和1 240 cm-1(δN-H)处。石化作用导致胶原蛋白酰胺键受到不同程度的破坏,致使猛犸牙中胶原蛋白的红外吸收谱带强度递减。象牙与猛犸牙指向牙心的两组粗勒兹纹理的夹角存在着明显的差异,前者的最大夹角>120°,后者的最大夹角<95°。象牙的粗勒兹纹层具纤束状交织结构,结构致密、坚韧、细腻;猛犸牙的粗勒兹纹层多具叶片状结构,胶原蛋白纤束体数量明显减少,结构疏松,质地干涩,孔隙度增大,微裂隙发育,韧性变差。

Mammoth is the ancient vertebrate and most of the existing mammoth teeth often exists as semi-fossil.The difference characteristics between mammoth teeth and ivory in the growth microstructure and collagen are studied by using the analysis and testing instruments like SEM and FTIR.The results show that the ivory and mammoth teeth are primarily composed of collagen and hydroxyl calcium phosphate.The infrared absorption spectra with the characteristics of the amido bond of the collagen are located at 1 663 cm-1（νC-O）,1 558 cm-1（νC-H） and 1 240 cm-1（δN-H）.The fossilization leads to the damage of the amido bond of the collagen to some extent and the intensities of the infrared absorption spectra of the collagen in the mammoth teeth are reduced gradually.There is the obvious difference between the ivory and mammoth teeth in the maximum included angle of the Retzius pointing to the center.The maximum angle of the former is larger than 120° while the maximum angle of the latter is smaller than 95°.The Retzius layer of the ivory has the fibrous interlocking texture with dense,solid and delicate structure.The Retzius layer of the mammoth teeth has the leaf-shaped structure with less collagen fibers and loose structure.The texture is dry and the size of the hole is larger.With the growth of the microfracture,the toughness will become weak.