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Univ. Paris-Saclay

Sujet de stage / Master 2 Internship

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Physicochemical description of pearl oyster biocrystallization

Contact: CHEVALLARD Corinne, , corinne.chevallard@cea.fr, +33 1 69 08 52 23
The formation of pearl oyster shells will be studied through model syntheses. The objective of this study is to evaluate the relevance of a crystalline nucleation scenario involving a salt-enriched liquid intermediate, to describe the biocrystallization processes.
Possibility of continuation in PhD: Non
Deadline for application:21/04/2020

Full description:
Calcifying organisms (molluscs, corals, sponges) are able to produce crystalline mineral structures (shells, exoskeletons) with perfectly controlled morphologies in order to target a particular biological function (protection, flotation, etc.). The physicochemical processes underlying this biocrystallization are still poorly known. One hypothesis is that the formation of these hard tissues results from the transformation of an amorphous calcium carbonate precipitate, formed from a liquid precursor that is salt-enriched with respect to the starting solution. We propose to assess the validity of this hypothesis by carrying out model syntheses, for which the existence of a liquid precursor seems to be proven, and by comparing the structure, at the different spatial scales, of the minerals formed with that of the biocrystals produced by the biological organisms. This work is part of a collaboration with the Institut Fresnel (Marseille) and the IFREMER station in French Polynesia.
The duration of the internship is 3 months minimum.
Technics/methods used during the internship:
Titration, optical microscopy, Raman/ IR spectromicroscopy, cryo-TEM

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