ERC FUNDED PROJECTS

At the end of their life, stars spread their inner material into the diffuse interstellar medium. This diffuse medium gets locally denser and form dark clouds (also called dense or molecular clouds) whose innermost part is shielded from the external UV field by the dust, allowing for molecules to grow and get more complex. Gravitational collapse occurs inside these dense clouds, forming protostars and their surrounding disks, and eventually planetary systems like (or unlike) our solar system. The formation and evolution of molecules, minerals, ices and organics from the diffuse medium to planetary bodies, their alteration or preservation throughout this cosmic chemical history set the initial conditions for building planets, atmospheres and possibly the first bricks of life. The current view of interstellar chemistry is based on fragmental works on key steps of the sequence that are observed. The objective of this proposal is to follow the fractionation of the elements between the gas-phase and the interstellar grains, from the most diffuse medium to protoplanetary disks, in order to constrain the chemical composition of the material in which planets are formed. The potential outcome of this project is to get a consistent and more accurate description of the chemical evolution of interstellar matter. To achieve this objective, I will improve our chemical model by adding new processes on grain surfaces relevant under the diffuse medium conditions. This upgraded gas-grain model will be coupled to 3D dynamical models of the formation of dense clouds from diffuse medium and of protoplanetary disks from dense clouds. The computed chemical composition will also be used with 3D radiative transfer codes to study the chemical tracers of the physics of protoplanetary disk formation. The robustness of the model predictions will be studied with sensitivity analyses. Finally, model results will be confronted to observations to address some of the current challenges.

1 166 231 €

Start date: 2013-09-01, End date: 2018-08-31

What is responsible for the emergence of homochirality, the almost exclusive use of one enantiomer over its mirror image? And what led to the evolution of life’s homochiral biopolymers, DNA/RNA, proteins and lipids, where all the constituent monomers exhibit the same handedness? Based on in-situ observations and laboratory studies, we propose that this handedness occurs when chiral biomolecules are synthesized asymmetrically through interaction with circularly polarized photons in interstellar space. The ultimate goal of this project will be to demonstrate how the diverse set of heterogeneous enantioenriched molecules, available from meteoritic impact, assembles into homochiral pre-biopolymers, by simulating the evolutionary stages on early Earth. My recent research has shown that the central chiral unit of RNA, ribose, forms readily under simulated comet conditions and this has provided valuable new insights into the accessibility of precursors of genetic material in interstellar environments. The significance of this project arises due to the current lack of experimental demonstration that amino acids, sugars and lipids can simultaneously and asymmetrically be synthesized by a universal physical selection process. A synergistic methodology will be developed to build a unified theory for the origin of all chiral biological building blocks and their assembly into homochiral supramolecular entities. For the first time, advanced analyses of astrophysical-relevant samples, asymmetric photochemistry triggered by circularly polarized synchrotron and laser sources, and chiral amplification due to polymerization processes will be combined. Intermediates and autocatalytic reaction kinetics will be monitored and supported by quantum calculations to understand the underlying processes. A unified theory on the asymmetric formation and self-assembly of life’s biopolymers is groundbreaking and will impact the whole conceptual foundation of the origin of life.

1 500 000 €

Start date: 2019-04-01, End date: 2024-03-31

The emergence of life is one of the most fascinating and yet largely unsolved questions in the natural sciences, and thus a significant challenge for scientists from many disciplines. There is growing evidence that ribonucleic acid (RNA) polymers, which are capable of genetic information storage and self-catalysis, were involved in the early forms of life. But despite recent progress, RNA synthesis without biological machineries is very challenging. The current project aims at understanding how to synthesize RNA in abiotic conditions. I will solve problems associated with three critical aspects of RNA formation that I will rationalize at a molecular level: (i) accumulation of precursors, (ii) formation of a chemical bond between RNA monomers, and (iii) tolerance for alternative backbone sugars or linkages. Because I will study problems ranging from the formation of chemical bonds up to the stability of large biopolymers, I propose an original computational multi-scale approach combining techniques that range from quantum calculations to large-scale all-atom simulations, employed together with efficient enhanced-sampling algorithms, forcefield improvement, cutting-edge analysis methods and model development. My objectives are the following: 1 • To explain why the poorly-understood thermally-driven process of thermophoresis can contribute to the accumulation of dilute precursors. 2 • To understand why linking RNA monomers with phosphoester bonds is so difficult, to understand the molecular mechanism of possible catalysts and to suggest key improvements. 3 • To rationalize the molecular basis for RNA tolerance for alternative backbone sugars or linkages that have probably been incorporated in abiotic conditions. This unique in-silico laboratory setup should significantly impact our comprehension of life’s origin by overcoming major obstacles to RNA abiotic formation, and in addition will reveal significant orthogonal outcomes for (bio)technological applications.

1 497 031 €

Start date: 2018-02-01, End date: 2023-01-31

Aeroelastic instabilities are at the origin of large deformations of structures and are limiting the capacities of products in various industrial branches such as aeronautics, marine industry, or wind electricity production. If suppressing aeroelastic instabilities is an ultimate goal, a paradigm shift in the technological development is to take advantage of these instabilities to achieve others objectives, as reducing the drag of these flexible structures. The ground-breaking challenges addressed in this project are to design fundamentally new theoretical methodologies for (i) describing mathematically aeroelastic instabilities, (ii) suppressing them and (iii) using them to reduce mean drag of structures at a low energetic cost. To that aim, two types of aeroelastic phenomena will be specifically studied: the flutter, which arises as a result of an unstable coupling instability between two stable dynamics, that of the structures and that the flow, and vortex-induced vibrations which appear when the fluid dynamics is unstable. An aeroelastic global stability analysis will be first developed and applied to problems of increasing complexity, starting from two-dimensional free-vibrating rigid structures and progressing towards three-dimensional free-deforming elastic structures. The control of these aeroelastic instabilities will be then addressed with two different objectives: their suppression or their use for flow control. A theoretical passive control methodology will be established for suppressing linear aeroelastic instabilities, and extended to high Reynolds number flows and experimental configurations. New perturbation methods for solving strongly nonlinear problems and adjoint-based control algorithm will allow to use these aeroelastic instabilities for drag reduction. This project will allow innovative control solutions to emerge, not only in flutter or vortex-induced vibrations problems, but also in a much broader class of fluid-structure problems.

1 377 290 €

Start date: 2015-07-01, End date: 2020-06-30