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Original publish date:Feb 09, 2011
編輯 JYWu 報導
一般的螺貝類外殼結構，外層為角質層由殼蛋白構成，往內為棱柱層及珍珠層由碳酸鈣結晶組成，2001年印度洋2420公尺深的熱泉噴口（Kairei Indian hydrothermal vent field）中所發現的C. squamiferum ，卻擁有不同於眾所皆知的構造，殼最外層為硫化鐵成份，內層為碳酸鈣組成。因此，美國麻省理工學院材料科學與工程學系Christine Ortiz的研究團隊利用奈米尺度的壓痕實驗（nanoindentation experiments），還有電腦模擬捕食者如螃蟹攻擊時對C. squamiferum各殼層的破壞程度、力的消散等，對殼進行了一系列的材料力學的分析研究。
研究團隊發現C. squamiferum外殼具有獨特性的三層（剛─軟─剛）結構：最外層由奈米至微米粒狀的硫化鐵組成提供第一線防禦，含有硫複鐵礦（greigite, Fe3S4），約有30μm 的厚度，在受到攻擊時，就會使這層防禦的粒狀結構分裂，此犧牲性的裂痕導致攻擊力量被分散，可防止整個外殼產生破壞性的裂痕；中間是具彈性的有機層，由殼蛋白組成，厚度約為150μm，能在外殼受到攻擊時吸收能量，以緩解來自外部的衝擊和壓力，並可減緩環境溫度變化所造成的影響；內層由碳酸鈣片狀的霰石晶體組成（aragonite），厚度約為250μm，其堅硬度可提供外殼結構上的支撐，並且抵抗彎曲變形，以達保護脆弱的軟組織之功能。藉由這種生物防護材料原理的發現，可望開發出高負載的保護材料、防爆裝備等實用於生物材料、航空及航太等科學。
- H. Yao et al., PNAS 107, 987-992, 2010
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