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Projets 2018

14-11-2018
   

TUNIFOLDS : Building blocks of foldamers in the gas phase

Contacts M. Mons, V. Brenner

This topic capitalizes on the team's achievements and in particular its pioneering role in the laser spectroscopy of isolated peptides. The elementary building blocks of foldamers, based on β-peptides, i.e. peptides more complex than the natural (α-) peptides, have specific intramolecular interactions, which can be characterized by IR / UV laser spectroscopy. 
These studies are at the origin of the project ANR TUNIFOLDS, in collaboration with the groups of D. Aitken and A. Zehnacker in Orsay, which seeks to finely tune the folding properties of the building blocks, by using specific intramolecular interactions, such as NH - S hydrogen bonds, when a heteroatom sulfur is included in the building blocks. Using these specific interactions as pivots, one should be able to control the folding properties of oligomers of these β-peptides, to form various types of secondary structures (helices, ribbons, etc ...).

This project is funded by the French National Research Agency (2017-2020, ANR-17-CE29-0008)

Collaborations :
•    Pr. David J. Aitken (Institut de Chimie Moléculaire et des Matériaux d'Orsay, Université Paris-Saclay)
•    Anne Zehnacker, Katia LeBarbu-Debus, Valéria Lepère, (Institut des Sciences Moléculaires d'Orsay, Université Paris-Saclay)
 

13-09-2018
Responsable : Eric GLOAGUEN

Ion Pairs

Ion pairs are ubiquitous in Nature, from sea water and aerosols, to living organisms. Being the very first step of crystallization of ionic species and influencing the properties of ion-concentrated solutions or ionic liquids, they also play a key role in countless applications. Although they are met in many areas of Physics, Chemistry and Biology, their characterization is complicated by the co-existence of several types of pairs and their elusive nature in solution.

In this context, this project aims at documenting net neutral ion pairs by investigating them in the gas phase using IR and UV laser spectroscopic techniques which enable us to characterize each type of ion pair individually. This experimental approach is combined with theoretical approaches aiming at identifiying the ion pairs formed in the gas phase, and extrapolating their vibrational signature in solution. Several questions are investigated by this project:

  • the spectroscopic characterization of ion pair types, and its application to the study of the ability of solvent molecules to dissociate an ion pair.
  • the influence of nearby counterions on the structure of charged biomolecules.
  • the early stages of ionic crystallization.

This project is funded by:

  • the French National Research Agency (2016-2020, JCJC grant number ANR-16-CE29-0017)
  • the French National Computing Centers (2016-present, High Performance Computing resources, project A0050807524)
  • Université Paris-Saclay  (2014-2017, PhD grant of the Chemical Sciences Doctoral School of Université Paris-Saclay )
  • the LabEx PALM (2014-2018, Master student grants, ANR-10-LABX-0039-PALM)
  • the Japan Society for the Promotion of Science (2018, JSPS Summer Grant, J. Donon)

Collaborations:

  • Pr. David J. Aitken (Institut de Chimie Moléculaire et des Matériaux d'Orsay, Université Paris-Saclay)
  • Dr. Denis Céolin (Soleil Synchrotron Facility, France)
  • Pr. Masaaki Fujii , Dr. Shun-ichi Ishiuchi (Tokyo Institute of Technology, Japan)

Références:

S. Habka, T. Véry, J. Donon, V. Vaquero-Vara, B. Tardivel, F. Charnay-Pouget, M. Mons, D.J. Aitken, V. Brenner, E. Gloaguen in preparation

S. Habka, "Spectroscopie optique des paires d’ions : De la caractérisation des modèles en phase gazeuse à l’identification des paires d’ions en solution", PhD thesis Université Paris-Saclay (2017)

S. Habka, V. Brenner, M. Mons, E. Gloaguen J. Phys. Chem. Lett. 7 (7) 1192 (2016)

21-08-2018

Project acronym: FLAVE
Project title: "Project Energetics of natural turbulent flows: the impact of waves and radiation".
Researcher (PI): Basile GALLET
Host Institution (HI):  CEA
Call Details: Starting Grant (StG), PE3, ERC-2017-STG


Summary:

Turbulence in natural flows is an outstanding challenge with key implications for the energetics of planets, stars, oceans, and the Earth’s climate system. Such natural flows interact with waves, radiation or a combination thereof: surface waves and solar radiation on oceans and lakes, bulk waves and radiation inside the rapidly rotating and electrically conducting solar interior, etc. Standard simplified models often discard waves, radiation, or both, with dramatic consequences for the energy budget of natural flows: geostrophic models neglect waves, and Rayleigh-Bénard thermal convection considers heat diffusively injected through a solid boundary, in strong contrast with radiative heating. The purpose of the present multidisciplinary project is to develop a consistent and coupled description of natural flows interacting with waves and radiation, to properly assess their energy budget:

  • Because resolving surface waves in global ocean models will remain out-of-reach for decades, I will derive and investigate reduced equations describing their two-way coupling to the ocean currents, with timely implications for the upwelling of nutrients, the strength of the global ocean circulation and ultimately CO2 sequestration and the climate system. 
  • Building on my recent advances in the field of rotating and magnetohydrodynamic turbulence, I will derive a set of reduced equations to simulate such turbulent flows in the vicinity of the transition where bulk 3D waves appear on a 2D turbulent flow. This approach will allow me to reach unprecedented parameter regimes, orders of magnitude beyond state-of-the-art 3D direct numerical simulations (DNS).
  • Finally, I will combine state-of-the-art DNS with a versatile experimental platform to determine the structure, kinetic energy and heat transport of turbulent radiative convection in various geometries. I will extrapolate the resulting scaling-laws to the ocean circulation, the mixing in lakes and the solar tachocline.

Start date: 2018-03-01, End date: 2023-02-28.

 

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