Texturization Analysis by X-ray Diffraction of Shells of the Mussel Ischadium recurvum (Rafinesque, 1820) (Mollusca Biva
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Texturization Analysis by X-ray Diffraction of Shells of the Mussel Ischadium recurvum (Rafinesque, 1820) (Mollusca Bivalvia) Octavio Gómez-Martínez1, Daniel H. Aguilar1, Juan J. Alvarado-Gil1, Patricia Quintana1 and Dalila Aldana-Aranda. Marine Resources Department. 1 Applied Physics Department. Cinvestav-Unidad Mérida. Carretera Antigua a Progreso, Km 6. Mérida, Yucatán, 97310, Mexico. ABSTRACT Most of the inorganic biomineralized materials are deposited on an organic matrix that controls the orientation and structure of the crystals. It is thought that chemical groups at the surface of the matrix may act as a template for the nucleation and growth of the mineral. A x-ray diffraction study of the texturization development of the bivalve mollusk shells is presented; specifically, the mussel Ischadium recurvum (Rafinesque, 1820), in different growing stages. The x-ray reflections show a preferred orientation that changes as the mollusk grows, and at the final stages only two crystallographic planes prevail. INTRODUCTION In the last decades a great effort has been dedicated to study and to understand natural biomineralized materials, in order to design and develop new advanced materials with specific properties to use them on different technology applications [1,2]. For instance, the production of cements with a high hardness and free of macro-defects, can be improved by imitating the high resistance and hardness of the nacre produced by a species of marine bivalve (mother of pearl) [3]. There has been a great interest to study the growth mechanisms of the crystals developed by living organisms, as well as the variation of their properties with the aging of the organism, and to understand their differences with the geological world. In Geology, the stable crystal phases are formed under certain conditions of temperature, pressure, etc. Meanwhile in the biology world the organisms maintain a strong control during growth which also is influenced by the environmental conditions that could result in the development of preferred orientation of the crystals. Crystals in living systems grow up in a controlled shape under the direction of the organic molecules and tissues. In the minerals the crystals generally are precipitated from a solution or from solidification of a melted material; in contrast, the inorganic materials in living organisms grow from the organic matrix which has a strong influence to define the crystal shape and the crystalline phase to be developed. For example the shells of the mollusks start to grow from their edges where two polymorphs of calcium carbonate, calcite and aragonite, are formed within a protein matrix. In this work the study of the texturization of the crystalline phases during successive stages of growth in the mussel Ischadium recurvum (Rafinesque, 1820) showing preferred crystallographic orientation is presented.
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EXPERIMENTAL Shells from mussel Ischadium recurvum were collected from the Mecoacan Tabasco, Mexico lagoon, located in 93º04' west between 18º16' and 18º26'. The h
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