Ultra-fast pathogenic bacteria detection in human blood
This project aims to develop a versatile and easy-to-use surface plasmon resonance imaging (SPRi) instrument for the rapid and broad-spectrum detection of low concentrations of pathogenic bacteria in complex samples, particularly blood. SPRi is a label-free technique that allows real-time probing of a sample (regardless of its optical transparency). Due to the high sensitivity of the plasmon phenomenon, the dynamic range of measurable index variation is limited by SPRi detection when reading is performed at a fixed angle, as is the case in commercially available devices. This reduces the use of such optical instruments to the study of environments whose index remains relatively stable during the experiment and whose molecular probes have molecular weights comparable to the targets (monitoring of bimolecular interactions).
This considerably limits the detection of growing bacteria in complex environments. Our laboratory has developed original solutions for the detection of very low levels of contamination in food matrices (creation of a start-up in 2012), but SPRi is unsuitable for the detection of bacteria in blood, partly due to the very high intrinsic variability of this matrix.
These limitations will be overcome by integrating five complementary components:
1. The design of an instrument optimized for real-time recording of SPR images over a defined range of illumination angles;
2. The development of dedicated SPR data analysis and processing to extract the most relevant information for each probe from the images in real time;
3. The functionalization of biochips through a combination of appropriate probes (series of peptides such as antimicrobial peptides (AMPs), antibodies, and even bacteriophages) to optimize the number of possible identifications with a reduced set of probes;
4. The learning of specific “4D-SPRi signatures” of model strains in blood matrices;
5. Validation of the performance of the new “4D-SPRi” instrument as a tool for detecting and characterizing bacteria from hospital strains compared to reference techniques.
Multi-modal in situ nuclear magnetic resonance analysis of electrochemical phenomena in commercial battery prototypes
Advancing electrochemical energy storage technologies is impossible without a molecular-level understand-ing of processes as they occur in practical, commercial-type devices. Aspects of the battery design, such as the chemistry and thickness of electrodes, as well as configurations of current collectors and tabs, influence the electronic and ionic current density distributions and determine kinetic limitations of solid-state ion transport. These effects, in turn, modulate the overall battery performance and longevity. For these reasons, optimistic outcomes of conventional ‘coin’ cell tests often do not converge into high-performance commercial cells. Safety concerns associated with high energy density and flammable components of batteries are another subject paramount for conversion from fossil to green energy sources.
Nuclear magnetic resonance (NMR) spectroscopy and imaging (MRI) are exceptionally sensitive to the structural environment and dynamics of most elements in active battery materials.
Recently, plug-and-play NMR and surface-scan MRI methods have been introduced. In the context of fun-damental electrochemical research, merging two innovative complementary concepts within one multi-modal (NMR-MRI) device would enable diverse analytical solutions and reliable battery performance metrics for academia and the energy sector.
In this project, an advanced analytical framework for in situ analysis of fundamental phenomena such as sol-id-state ion transport, intercalation and associated phase transitions, metal plating dynamics, electrolyte deg-radation and mechanical defects in commercial Li- and Na-ion batteries under various operational conditions will be developed. A range of multi-modal (NMR-MRI) sensors will be developed and employed for deep analysis of fundamental electrochemical processes in commercial battery cells and small battery packs.
What mechano-thermal coupling is necessary for fast transients? Evaluation of the contributions of thermodynamics to irreversible processes.
The Laboratory for the Analysis of Radioelement Migration (LAMIR) at the Institute for Research on Nuclear Systems (IRESNE) of the CEA Cadarache has developed a set of measurement methods to characterize the release of fission products from nuclear fuel during transient thermal transients. For these transients, it is important to simulate the mechanical stresses associated with temperature changes that could lead to fracturing of the tested fuel samples . This thesis focuses on modeling hypothetical and very rapid accidental power transients. Its objective is to implement a new model based on the thermodynamics of irreversible processes (TIP).
The first part of this thesis will aim to validate the thermomechanical coupling model in TIP, which was proposed in our laboratory (https://www.mdpi.com/2813-4648/3/4/33). This will be an essentially analytical approach to establish the orders of magnitude of the various mechanisms involved. The second part will apply this formalism to experimental results obtained during rapid heating experiments using laser beams.
One of the main challenges of numerical simulation with TIP is calculating the temperature and stress fields simultaneously, rather than sequentially as in current models. We will start with a 1D program (in Python or another language) that will be progressively refined. Comparing the results obtained with TIP and with current models will help us identify situations in which TIP-specific couplings must be taken into account to achieve accurate predictions.
The PhD candidate will benefit from the support of experts in thermodynamics, mechanics, and programming. The research will lead to scientific publications and conference presentations. Owing to the diversity of the fields involved, this thesis topic offers excellent career prospects in both industry and academic research.
INFLUENCE OF THE DRY GRANULATION ON THE MANUFACTURING OF SFR MOX FUELS
The subject is related to the manufacture of MOX U,Pu)O2 fuel for Fast Neutron Reactors. The current process integrates a co-grinding step of uranium and plutonium dioxides to generate a powder medium which is then shaped by uniaxial pressing to generate cylindrical fuel pellets which are then sintered at high temperature. The collected powder medium has poor flowability which limits the rates of shaping by pressing. The objective of the thesis is therefore to evaluate the impact of mechanical granulation of the powder medium on the flowability, the pressing step and the microstructure obtained after sintering. Dissolution tests in nitric acid will also be carried out on certain very specific microstructures. The thesis will be based on a formal experimental plan developed using specific software (JMP). The PhD will take place at the INB Atalante facility on the CEA Marcoule site. The candidate will work in a unique facility in Europe and will be able to develop expertise in working in a nuclear environment with a highly innovative approach that will lead to the publication of original scientific results.