Matière et Systèmes Complexes

MSC 7057

Tutelles >

Université Paris Diderot

UFR de rattachement >

UFR Physique

Label unité >

UMR 7057

Partenaires >

CNRS

Présentation

Le laboratoire « Matière et Systèmes Complexes » (MSC) est une unité mixte de recherche du CNRS et de l’université (UMR 7057). Le laboratoire est installé depuis 2007 sur le nouveau campus de l’Université Paris Diderot, Paris Rive Gauche, dans le bâtiment Condorcet. Il est réparti sur plusieurs étages. La direction et le secrétariat se trouvent au 6e étage. Le directeur actuel en est Laurent Limat, secondé par la directrice adjointe Florence Gazeau.

Le laboratoire MSC a pour sujet d’étude la matière et les systèmes complexes sous toutes leurs formes. Il peut s’agir de fluides montrant des phénomènes complexes non-linéaires (facettages de jets ou de tourbillons, structures et propriétés complexes de mousses, phénomènes de mouillage, propagation de vagues et de tsunamis) ou bien, par exemple, de systèmes proches de la géophysique et de l’environnement (systèmes granulaires tels que les dunes, phénomènes d’érosion, morphogenèse des plantes et même des villes, nage collective d’algues ou de bactéries…). Les études théoriques et expérimentales conduisent à des applications comme par exemple les éoliennes flexibles de haut rendement, l’optimisation de méthodes d’enduisage, le contôle de propriétés de surface ou la récupération de la biomasse (ingénierie verte)...

Le laboratoire étudie également le couplage entre la physique et la biologie des systèmes vivants, avec une approche multi-échelle. Les recherches effectuées vont d’échelles moléculaires ou supra-moléculaires (assemblages des protéines, chromatine, cytosquelette etc.) jusqu’à l’échelle de l’organisme entier (méduses, poulets, vers etc.) en passant par des études plus fondamentales sur des cellules uniques sur lesquelles sont exercées des forces quantifiées, permettant de comprendre les propriétés biophysiques de la matière vivante. Ces études aboutissent à de possibles applications en ingénierie tissulaire ou régénération des tissus avec des transferts dans le domaine médical.

Equipes de recherche

Le laboratoire est structuré en cinq équipes :

Dynamique des systèmes hors d’équilibre (DSHE), orientée plutôt vers les comportements non-linéaires de fluides, éventuellement actifs ou avec surface libre, et les phénomènes d’auto-organisation en général (morphogenèse des granulaires, systèmes particulaires inspirés de la matière condensée, colloïdes et transition d’encombrement, etc).
Dynamique et organisation de la matière molle (DOMM), orientée plutôt vers les matériaux mous visco-élastiques aux propriétés rhéologiques complexes (gels, polymères, mousses etc.), milieux caractérisés par une structure hétérogène, et dont l’organisation et les propriétés dépendent de l’échelle d’observation.
Physique du vivant, orientée plutôt vers l’étude des processus physiques qui sous-tendent les fonctions biologiques, principalement à l’échelle cellulaire, entre la molécule et le tissu.
Biofluidique, orientée plutôt vers l’étude des systèmes vivants du tissu à l’organisme, avec des applications à visées médicales.
Une équipe de théoriciens dont les thématiques couvrent un spectre large de questions fondamentales allant de la physique statistique hors équilibre à la neuroscience, en passant par la matière molle et la matière active.

Cependant les activités de ces équipes se recoupent souvent dans des projets communs aux frontières entre les comportements physiques et/ou biologiques (exemple : comportement de mousses marines, mesures de forces dans des tissus reconstitués, etc.)

[hal-04001901] A Novel Spatially Resolved 3D Force Sensor for Animal Biomechanics and Robotic Grasping Hands

Date: 23 Feb 2023 - 11:20

Desc: [...]

[hal-02375096] Biological modification of mechanical properties of the sea surface microlayer, influencing waves, ripples, foam and air-sea fluxes

Date: 21 Nov 2019 - 19:09

Desc: Gas exchange reduction (GER) at the air-sea interface is positively related to the concentration of organic matter (OM) in the top centimetre of the ocean, as well as to phytoplankton abundance and primary production. The mechanisms relating OM to GER remain unclear, but may involve mechanical (rheological) damping of turbulence in the water immediately below the surface microlayer, damping of ripples and blocking of molecular diffusion by layers of OM, as well as electrical effects. To help guide future research in GER, particularly of CO2, we review published rheological properties of ocean water and cultures of phytoplankton and bacteria in both 3D and 2D deformation geometries, in water from both the surface layer and underlying water. Production of foam modulates air-sea exchange of many properties and substances, perhaps including climate-changing gases such as CO2. We thus also review biological modulation of production and decay of whitecaps and other sea foam. In the ocean literature on biological production of OM, particularly that which associates with the sea surface, the terms “surfactant” and “surface-active” have been given a variety of meanings that are sometimes vague, and may confuse. We therefore propose a more restricted definition of these terms in line with usage in surface science and organic chemistry. Finally, possible changes in OM-modulated GER are presented in relation to predicted global environmental changes..

[hal-02446242] Unexpected trapping of swimming microalgae in foam

Date: 20 Jan 2020 - 16:55

Desc: Massive foam formation in aquatic environments is a seasonal threat that drastically impacts the stability of marine ecosystems. Because liquid foams are known to filter passive solid particles, with large particles remaining trapped by confinement in the network of liquid channels and small particles being freely advected by the gravity-driven flow, we hypothesized that a similar e↵ect could explain the major shifts in phytoplankton populations observed during foaming episodes. The model unicellular motile algae Chlamydomonas reinhardtii (CR) was incorporated in a bio-compatible foam, and the number of cells escaping the foam at the bottom was measured in time. Comparing the escape dynamics of living and dead CR cells, we found that dead cells are totally advected by the liquid flow towards the bottom of the foam, as expected since the CR diameter remains smaller than the typical foam channel diameter. In contrast, living motile CR cells escape the foam at a significantly lower rate: after two hours, up to 60 % of the injected cells may remain blocked in the foam, while 95 % of the initial liquid volume in the foam has been drained out of the foam. Microscopic observation of the swimming CR cells in a chamber mimicking the cross-section of foam internal channels revealed that swimming CR cells accumulate near channels corners. A theoretical analysis based on the probability density measurements in the micro chambers have shown that this trapping at the microscopic scale contributes to explain the macroscopic retention of the microswimmers in the foam.

[hal-03004737] Trapping of swimming microalgae in foam

Date: 13 Nov 2020 - 17:27

Desc: Massive foam formation in aquatic environments is a seasonal event that has a significant impact on the stability of marine ecosystems. Liquid foams are known to filter passive solid particles, with large particles remaining trapped by confinement in the network of liquid channels and small particles being freely advected by the gravity-driven flow. By contrast, the potential role of a similar retention effect on biologically active particles such as phytoplankton cells is still relatively unknown. To assess if phytoplankton cells are passively advected through a foam, the model unicellular motile alga Chlamydomonas reinhardtii (CR) was incorporated in a bio-compatible foam, and the number of cells escaping the foam at the bottom was measured in time. Comparing the escape dynamics of living and dead CR cells, we found that dead cells are totally advected by the liquid flow towards the bottom of the foam, as expected since the diameter of CR remains smaller than the typical foam channel diameter. By contrast, living motile CR cells escape the foam at a significantly lower rate: after 2 hours, up to 60% of the injected cells may remain blocked in the foam, while 95% of the initial liquid volume in the foam has been drained out of the foam. Microscopic observation of the swimming CR cells in a chamber mimicking the cross-section of foam internal channels revealed that swimming CR cells accumulate near channels corners. A theoretical analysis based on the probability density measurements in the micro chambers has shown that this trapping at the microscopic scale contributes to explain the macroscopic retention of the microswimmers in the foam. At the crossroads of distinct fields including marine ecology of planktonic organisms, fluid dynamics of active particles in a confined environment and the physics of foam, this work represents a significant step in the fundamental understanding of the ecological consequences of aquatic foams in water bodies.

[hal-00138987] Single-cell detection by gradient echo 9.4 T MRI : a parametric study

Date: 21 Apr 2023 - 14:50

Desc: Recent studies have shown that cell migration can be monitored in vivo by magnetic resonance imaging after intracellular contrast agent incorporation. This is due to the dephasing effect on proton magnetization of the local magnetic field created by a labelled cell. Anionic iron oxide nanoparticles (AMNP) are among the most efficient and non-toxic contrast agents to be spontaneously taken up by a wide variety of cells. Here we measured the iron load and magnetization of HeLa turnout cells labelled with AMNP, as a function of the external magnetic field. High-resolution gradient echo 9.4T MRI detected individual labelled cells, whereas spin echo sequences were poorly sensitive. We then conducted a systematic study in order to determine the gradient echo sequence parameters (echo time, cell magnetization and resolution) most suitable for in vivo identification of single cells.