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Reference : UMR7645-LAULAC-002
Workplace : PALAISEAU
Date of publication : Friday, June 4, 2021
Scientific Responsible name : Marie-Claire SCHANNE-KLEIN
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 October 2021
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
Prepared from animal skins, parchments are essentially composed of collagen fibers and are sensitive to various alteration factors, the main ones being water and heat. A crucial challenge to define suitable treatments or conservation conditions is to determine the state of collagen in a non-invasive way and thus prevent an irremediable degradation of the parchment, called gelatinization. The aim of this project is to measure and characterize the physicochemical and morphological modifications of collagen as a function of temperature, humidity and pressure conditions and to understand their origins. Our approach is based on non-linear optical microscopy, a non-invasive technique at the micrometer scale, coupled with different chemical analysis techniques (infrared spectroscopy and thermal analysis) to allow the interpretation of the observed signals. Eventually, this microscopy technique will allow a non-invasive monitoring of parchment collections based on quantitative measurements of collagen degradation states.
The expected results are the following:
- Understanding the physico-chemical origin of non-linear optical microscopy signals in parchments and the evolution of these signals during alteration.
- Implementation of a new tool for dynamic monitoring under controlled humidity and temperature with different microscopy techniques.
- New knowledge on the impact of environmental parameters (heat, humidity) on collagen degradation mechanisms.
- Understanding of the mechanisms associated with transparency and gelatinization of parchments.
The project relies on the complementary expertise of CNRS laboratories from 3 different institutes:
- Laboratory for Optics and Biosciences (LOB, UMR7645) with Marie-Claire Schanne-Klein and Gaël Latour: expertise in multiphoton microscopy and various physical measurements of collagen-based materials, as well as in quantitative image processing.
- Conservation Research Center (CRC, USR3224) with Laurianne Robinet and Sylvie Heu-Thao of the Leather and Parchment Pole: expertise on parchments (manufacture, degradation), their physico-chemical analysis and conservation issues associated with heritage collections.
- Institute of Chemical Physics(ICP, UMR8000) with Ariane Deniset-Besseau and Jérémie Mathurin: expertise in multi-scale infrared spectroscopy (from millimeter to nanometer).
The PhD will be supervised by M.-C. Schanne-Klein (PhD director) and G. Latour (co-supervisor) at LOB and L. Robinet (co-supervisor) at CRC. It will take place mainly at the LOB, at the Ecole Polytechnique (Palaiseau), but regular work at the CRC (Paris) and the ICP (Orsay) are to be expected. At the LOB, the PhD student will be integrated in the advanced microscopy pole and will benefit from its expertise and its biophotonics facilities (microscopes, biology laboratory, image processing softwares). The candidate will join the doctoral school of the Institut Polytechnique de Paris, in the Physics field.
Ecole Polytechnique is located on the Saclay plateau and is easily accessible by transport from Paris. The campus offers a pleasant living environment, with many activities (sports, culture, associations). More information on https://www.ip-paris.fr.
Constraints and risks
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The candidate will have a master's degree in physics with a focus on optics, instrumental optics and data processing. He/she should be comfortable with experimental optics and microscopy techniques. Knowledge in programming and image processing will also be appreciated in order to extract quantitative information from the parchment images. An interest in heritage science and an ability to work in a highly interdisciplinary environment will also be essential.
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