Actualités

Les prochaines Journées de la Diffusion Neutronique se dérouleront du 2 au 5 juin 2025 au Lac d’Annecy. Notez le dès maintenant dans vos agendas ! Plus d’information ici.

HERCULES est une école européenne dédiée aux étudiants en thèse et aux jeunes chercheurs utilisant les Neutrons et le Rayonnement Synchrotron pour des applications en Biologie, Chimie, Physique, Matière Condensée (dure et molle).

The study of confined particles is at the heart of any quantum physics textbook, including examples of particles moving in a harmonic oscillator potential well and of particles trapped in a box. Studying these examples constitutes a starting block to deepen our understanding of the quantum dynamics of more realistic systems.

Publication: A combined inelastic neutron scattering and simulation study of the ³He@C₆₀ endofullerene, M. Aouane et al., Physical Chemistry Chemical Physics 25 (2023). https://doi.org/10.1039/D3CP02253F

Les composés multiferroiques sont largement étudiés en raison du couplage magnétoélectrique, permettant de manipuler par exemple la polarisation à l’aide d’un champ magnétique. Une nouvelle manifestation du couplage magnéto-électrique vient d’être découverte dans le composé multiferroique GdMn₂O₅. Cette étude montre qu’il est possible d’induire un nouvel état électronique après avoir appliqué un champ magnétique puis l’avoir coupé. Quant à l’ordre magnétique, il revient bien dans son état initial comme le montre la diffusion de neutrons.

Publication: Electronic ground-state hysteresis under magnetic field in GdMn2O5, V. Balédent et al., Physical Review B 108 (2023). https://doi.org/10.1103/PhysRevB.108.104419

Here we report on a recent study of Phosphoglycerate Kinase with high-resolution quasielastic neutron scattering (QENS) in which the data analysis with a “minimalistic” multi-scale model for protein dynamics in space and time shows directly that the transformation of adenosine diphosphate (ADP) into adenosine triphosphate (ATP), and thus the production of energy carriers within the living cell, is enabled by inter-domain motions of this enzyme.

Publication: Signature of functional enzyme dynamics in quasielastic neutron scattering spectra: The case of phosphoglycerate kinase, A. Hassani et al., J. Chem. Phys. 159 (2023). https://doi.org/10.1063/5.016612486

When polymers self assemble in water, unlike surfactants, they do not reach a thermodynamically stable state but undergo slow relaxations for a long time. Small angle neutron scattering performed during dialysis of the polymer solution, enables to study of this effect and eventually understand how to overcome it. 

Publication: In situ monitoring of block copolymer self-assembly through controlled dialysis with light and neutron scattering detection, M. Fauquignon et al., ACS Macro Lett. 12 (2023). https://doi.org/10.1021/acsmacrolett.3c00286

Among all the quantum manifestations of matter, quantum phase transitions – corresponding to an abrupt change in the ground state of a system at zero temperature due to quantum fluctuations when an external parameter such as a magnetic field or pressure is applied – are particularly exacerbated in 1D magnetic systems, where magnetic ions interact preferentially along one direction in space. Inelastic neutron scattering and numerical simulations allowed us to study such quantum transitions in the anisotropic antiferromagnetic chain compound BaCo₂V₂O₈. 

Publication: Phase transitions and spin dynamics of the quasi-one dimensional Ising-like antiferromagnet BaCo2V2O8 in a longitudinal magnetic field, S. Takayoshi et al., Phys. Rev. Research 5 (2023). https://doi.org/10.1103/PhysRevResearch.5.023205

Have you ever thought of using inorganic ions to solubilize organic dyes, pharmaceutical active ingredients, perfumes or solvents in water? No? Well, read on… 

Publication: Aqueous solubilization of hydrophobic compounds by inorganic nano-ions: An unconventional mechanism, I. Chazapi et al., Journal of Colloid and Interface Science 638 (2023). https://doi.org/10.1016/j.jcis.2023.01.115

Since the outbreak of the COVID-19 pandemics, much has been discussed about the relationship between the severity of the disease and the plasma lipid profiles of the population. We therefore studied the role played by the Spike protein (S protein) from SARS-CoV-2 in the lipid metabolisms, especially its interaction with High-Density Lipoproteins (HDLs). Our first work on the topic showed that the S protein removes lipids from model membranes and interferes with the capacity of HDL for removing and exchanging lipids composed of saturated phospholipids (DMPC) and cholesterol. Among the remaining open questions : does the S protein have preference over certain lipids? Could the lipid serum profile in individuals have an effect over how the S protein affect HDL function?

Publication: High-density lipoprotein function is modulated by the SARS-CoV-2 spike protein in a lipid-type dependent manner, Y. Correa et al., Journal of Colloid and Interface Science 645 (2023). https://doi.org/10.1016/j.jcis.2023.04.137

Les matériaux présentant un fort couplage spin-orbite ont récemment attiré beaucoup d’attention de par leur potentielle réalisation de nouvelles phases électroniques et magnétiques. La combinaison de diffraction des neutrons, de mesures magnétométriques et de mesures de magnétorésistance sous champ magnétique apporte finalement une compréhension fine des propriétés de tels matériaux. 

Publication: Magnetic structure and field dependence of the cycloid phase mediating the spin reorientation transition in Ca₃Ru₂O₇, Q. Faure et al., Phys. Rev. Research 5 (2023). https://doi.org/10.1103/PhysRevResearch.5.013040

What is happening to the proteome of a bacterium like Escherichia coli when it is heated above the temperature of cell death ? For a long time, it was hypothesized that a so-called proteome catastrophe happens when going beyond denaturation, where most of the proteins unfold in a narrow range of temperatures. With the help of incoherent neutron scattering, we were able to find out that on the contrary…

Publication: Diffusive dynamics of bacterial proteome as a proxy of cell death, D. Di Bari et al., ACS Central Science 9 (2023). https://doi.org/10.1021/acscentsci.2c01078

Understanding thermal transport in materials is one of the major challenges today, fundamental for engineering new materials efficient for thermal management and energy harvesting. A good understanding of heat transport mechanisms is now achieved for crystals on one side and disordered materials (glasses) on the other, which exhibit very different properties. A new class of crystalline materials, High Entropy Alloys, characterized by a strong local chemical disorder, exhibits thermal transport properties similar to the ones of glasses: understanding the origin of this behavior requires investigating their phonon dynamics.

Publication: Phonon behavior in a random solid solution: a lattice dynamics study on the high-entropy alloy FeCoCrMnNi, S. Turner et al., Nature Communications 13 (2022). https://doi.org/10.1038/s41467-022-35125-4

Mixtures of hyaluronic acid (HA) and liposomes are efficient drug delivery systems for applications in otology and ophthalmology, yet little is known about their microstructure. In this study, we used SANS to demonstrate that liposomes keep their integrity in a matrix of HA chains, whether they are anionic, cationic, or decorated by poly(ethylene glycol) chains, and whether they contain or not a corticoid. We also demonstrate that their aggregation state is driven by how their surface interacts with the HA chains.

Publication: Hybrid systems combining liposomes and entangled hyaluronic acid chains: influence of liposome surface and drug encapsulation on the microstructure, C. Jaudoin et al., J. Colloid. Int. Science 628 (2022). https://doi.org/10.1016/j.jcis.2022.07.146

Wire Arc Additive Manufacturing (WAAM) is one of the lesser-known metal 3D printing technologies. The metal wire is melted with an electric arc as the heat source, thus the technique has a huge potential for large 3D metal parts with complex design in many industrial applications using less material. One of the limitations of this technique is residual stresses. This study shows how the process can be studied coupling several techniques, measuring residual stresses thanks to neutron techniques, which are able to analyse thick pieces without any destruction. 

Publication: A WAAM benchmark: from process parameters to thermal effects on weld pool shape, microstructure and residual stresses, C. Cambon et al., Materials Today Communications 33 (2022). https://doi.org/10.1016/j.mtcomm.2022.104235

Nanocelluloses can be used to stabilize oil–water surfaces, forming so-called Pickering emulsions. In this work, we probed the organization of native and mercerized cellulose nanocrystals (CNC-I and CNC-II) adsorbed on the surface of hexadecane droplets dispersed in water by coupling small-angle neutron scattering with contrast variation experiments and molecular dynamics simulations. We showed that there exists a preferred interacting crystalline plane for both allomorphs that exposes the CH groups (100 and 010) and is therefore considered hydrophobic. This study suggests that whatever the allomorph, the migration of CNCs to the interface is spontaneous and irreversible, leading to highly stable emulsions. 

Publications: Edge-on (cellulose II) and face-on (cellulose I) adsorption of cellulose nanocrystals at the oil-water interface: a combined entropic and enthalpic process, S. Haouache et al., Biomacromolecules 23 (2022). https://doi.org/10.1021/acs.biomac.2c00201

Cellulose nanocrystals from native and mercerized cotton, S. Haouache et al., Cellulose 29 (2022). https://doi.org/10.1007/s10570-021-04313-8

The realization of exotic state of matter is interesting not only from a fundamental physics point of view but also holds immense promise for potential applications in robust quantum computing technology. In the frustrated antiferromagnet Li₄CuTeO₆, a dynamic and correlated disorder-induced spin-liquid ground state is evidenced experimentally for the first time. Here, neutron diffraction has proven to be essential to probe the disorder at the origin of this original magnetic state.

Publication: Signature of a randomness-driven spin-liquid state in a frustrated magnet, J. Khatua et al., Communications Physics 5 99 (2022). https://doi.org/10.1038/s42005-022-00879-2

Water is essential to life as we know it. In planetary sciences, it is also considered key to whether life ever existed elsewhere in the Solar System, for example on Mars. One way to approach this question is to investigate martian meteorites that reacted with liquid water when they were still part of the martian crust.

Publication: The scale of a martian hydrothermal system explored using combined neutron and x-ray tomography, J. Martell et al., Science Advances 8 19 (2022). https://doi.org/10.1126/sciadv.abn3044

Due to the COVID-19 pandemic, a thorough understanding of the molecular mechanisms of cellular infection by coronaviruses has become imperative. A critical stage in cell entry by the SARS-CoV-2 virus occurs when its Spike protein mediates fusion between viral and host membranes. Recently published in the Journal of the American Chemical Society, we presented a detailed investigation of the role of selected regions of the Spike protein, and the influence of calcium and cholesterol, in this fusion process.

Publication: Strikingly Different Roles of SARS-CoV-2 Fusion Peptides Uncovered by Neutron Scattering, A. Santamaria et al., J. Am. Chem. Soc. 144 2968 (2022). https://doi.org/10.1021/jacs.1c09856