Soutenance de Thèse de Khadeeja MUBASHIRA (CEA-Irig/IBS)
2026-06-22 13:30 - 15:30 (Europe/Paris) | Amphi A de Biologie, Rue de la Piscine, Saint-Martin-d'Hères, 38400, France
Étude de la séparation de phase de la phosphoprotéine du virus de la rage et de sa régulation par LC8
Résumé :
Rabies virus (RABV) replication occurs in cytoplasmic, membrane-less compartments known as Negri bodies (NBs), formed through liquid-liquid phase separation (LLPS) of viral components. The phosphoprotein (RABV P) is a central, intrinsically disordered scaf fold of the viral replication machinery. This thesis investigates the structural, biophysical, and dynamic properties of RABV P, with emphasis on its phase separation behavior and interactions with molecular partners. To enable this, recombinant expression and purification protocols were optimized to produce stable, high-quality protein samples for reproducible analyses.
We first characterized the intrinsic phase behavior of RABV P in vitro. The protein undergoes thermoresponsive LLPS with a lower critical solution temperature (LCST), forming reversible condensates within a narrow range of protein and salt concentrations. This process is driven by multivalent interactions within a heterogeneous ensemble of conformations, where dimers assemble into higher-order oligomers prior to phase separation. The resulting phase diagram reveals a complex, reentrant system governed by a balance between electrostatic repulsion and attractive dipole-dipole interactions.
The role of ionic conditions was further examined. While NaCl induced reentrant phase separation, LLPS strongly depended on ion identity rather than ionic strength alone. Chloride salts promoted condensate formation, whereas bromide salts did not, indicating ion-specific (Hofmeister-type) effects. Systematic trends showed that fluoride enhances phase separation, while cation effects are weaker. Divalent ions also promoted LLPS, highlighting valency contributions. Chemical perturbations confirmed that condensates are stabilized by weak interactions: 1,6-hexanediol partially disrupted droplets, whereas ATP fully dissolved them. Notably, RABV P intrinsically phase separates even in water, modulated by pH, protein concentration, and ionic conditions.
Time-resolved small-angle X-ray scattering (SAXS) revealed the structural evolution underlying LLPS. Following a temperature jump, RABV P undergoes a hierarchical assembly process, transitioning from dispersed species to larger structures. Early conformational rearrangements precede the formation of intermediate clusters, followed by growth into larger assemblies. These structures remain disordered and liquid-like, supporting a multistep nucleation-and-growth mechanism.
The host protein LC8 was investigated as a regulator of RABV P condensation. LC8 binds a conserved motif in RABV P with high affinity, forming a defined complex and partitioning into condensates. Functionally, LC8 enhances phase separation by increasing condensate size, enriching RABV P in the dense phase, and broadening the phase-separation window. It shifts phase boundaries toward lower concentrations and temperatures while preserving liquid-like properties. These results indicate that LC8 actively promotes condensation by stabilizing interaction-competent conformations and enhancing intermolecular connectivity.
To assess whether LC8 can compensate for intrinsic multivalency, a truncated RABV P lacking the dimerization domain was analyzed. Although LC8 bound this construct, the interaction was weaker and failed to restore robust phase separation. Only weak condensation was observed under crowding conditions, demonstrating that LC8 cannot substitute for the native dimerization-driven multivalency.
Overall, this work establishes RABV P as a finely tuned multivalent scaffold whose phase behavior arises from the interplay of intrinsic disorder, ion-specific effects, and hierarchical assembly. LLPS emerges as a multistep, non-ideal process rather than a simple binary transition. LC8 acts as a key host regulator that enhances phase separation without altering condensate dynamics, while intrinsic multivalency remains essential. These findings provide a mechanistic framework for understanding viral condensate formation and highlight potential avenues for antiviral intervention.
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Contact : alain.farchi@cea.fr

Maurizio SACCHI (CNRS - Institut des NanoSciences de Paris and Synchrotron SOLEIL)
2026-06-22 14:00 - 15:00 | CNRS – Salle Louis Weil (E424), CNRS - Institut Néel 25 avenue des Martyrs, Grenoble, 38042, France
X-rays with Orbital Angular Momentum for spectroscopy and imaging
Résumé :
In addition to the spin angular momentum (SAM) associated to the light polarization, Laguerre-Gaussian light beams carry also an orbital angular momentum (OAM) of ℓ /photon [1]ℏ associated to an azimuthal dependence exp(iℓϕ) of the electric field phase. Over the last thirty years, OAM beams at vis-IR wavelengths found applications in fields as different as biology, telecommunication and imaging [2]. The azimuthal phase dependence, with a singularity on the propagation axis, is accompanied by a radial modulation of the intensity (ring-shaped beams), properties that have been used to modify local magnetic ordering, to improve the spatial resolution in microscopy, and to enhance the edge sharpness in phase-contrast imaging.
Over the last decade, several approaches to the generation of OAM beams at shorter wavelengths, from XUV to hard x-rays, were proposed. Potential applications are often based on the extrapolation of previous work carried out in the vis-IR range. For instance, as for the SAM, the handedness imposed by the OAM has been exploited to study magnetic materials [3] and chiral molecules [4]. The interest of extending the use of OAM beams from the vis-IR to the x-ray range has been growing steadily over the last few years. Nonetheless, the offer of user accessible beamlines and endstations remains limited, especially when one aims at independently varying both SAM and OAM in a controlled way. At the SEXTANTS beamline of the SOLEIL synchrotron, we have implemented and commissioned a new setup for soft x-ray spectroscopy (absorption and resonant scattering experiments) with OAM beams [5].
1. L. Allen at al., Orbital angular momentum of light and the transformation of Laguerre-Gaussian laser modes, Phys. Rev. A 45, 8185 (1992).
2. Y. Shen et al., Optical vortices 30 years on: OAM manipulation from topological charge to multiple singularities, Light: Science & Applications 8, 90 (2019).
3. M. Fanciulli et al., Electromagnetic theory of Helicoidal Dichroism in reflection from magnetic structures, Phys. Rev. A 103, 013501 (2021); Observation of magnetic helicoidal dichroism with extreme ultraviolet light vortices, Phys. Rev. Lett. 128, 077401 (2022); Magnetic vortex dynamics probed by time-resolved magnetic helicoidal
dichroism, Phys. Rev.Lett. (2025).
4. J. R. Rouxel et al., Hard X-ray helical dichroism of disordered molecular media, Nature Phot. 16, 570 (2022).
5. P. Carrara et al., Soft x-rays with Orbital Angular Momentum for resonant scattering experiments at the SOLEIL synchrotron, J. Synchr. Rad. 33, 858 (2026).
Contact : matteo.dastuto@neel.cnrs.fr

Cyril BRESSY (Aix-Marseille Université - Institut des Sciences Moléculaires de Marseille (iSm2))
2026-06-23 10:00 - 11:00 | DCM – Salle C209, DCM - Bât Chimie Recherche 301 rue de la Chimie, St Martin d'Hères, 38400, France
Compartmentalized MultiCatalysis : Chirality as Probe, Separation of Enantiomers & Catalytic Active Transport
Résumé :
Life solves the problem of different reaction conditions by the compartmentalization of the catalytic systems. This solution opens new opportunities for the chemists using synthetic membranes to isolate the catalytic systems.
We were interested to study the diffusion of molecules through a semi-permeable membrane when no gradient of concentration does exist. Chirality was found to be helpful to be used as probe to study such systems (1). A scale of diffusion energy depending on the structure of the solute was established providing fruitful lessons.
Based on these results, compartmentalized multicatalytic systems were set up for different goals :
– A system where two catalysts of opposite configurations are working in each compartment leading to the physical separation of enantiomeric products starting from a racemic substrate. This is describing a case of compartmentalized parallel kinetic resolution (CPKR)(2).
– A system to promote the active transport of a molecule able to cross a membrane. The active transport means a transfer against the gradient of concentration (3).
References
1 . J. Hou, S. Chevallier-Michaud, L. Favre, D. Hérault & C. Bressy, J. Membrane Sci. 2026, in revision.
2 . a) J. Hou, S. Chevallier-Michaud, M. Jean, L. Favre, D. Hérault & C. Bressy, J. Am. Chem. Soc. 2023, 145, 27236-27241; b) J. Hou, D. Hérault, C. Bressy, “Method for simultaneous preparation of separated enantiomeric products from racemic substrates”, Extension internationale PCTEP2022085983 (2022) WO2023126186A1.
3 . Manuscript in preparation
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Contact : adrien.quintard@univ-grenoble-alpes.fr

Lucas GOEHRING (Nottingham Trent University (UK))
2026-06-23 11:00 - 12:00 | ILL – Salle de Séminaire (110-111), ILL 50 71 avenue des Martyrs, Grenoble, 38042, France
Structure formation in paints and coatings
Résumé :
Paints and coatings are typically a mix of small particles, like pigments, along with a polymer glue or binder. Similar products include inks, varnishes, cosmetics, ceramics and even the lithium-ion battery electrodes that power modern electric vehicles. These materials are prepared as a liquid, spread over a surface, and dried. As anyone who has painted a wall will know, however, this process can easily go wrong. Even a well-prepared paint can develop an undesirable skin and wrinkle, crack, or peel, and these coatings can also visibly degrade over time.
In this talk I will go through the key stages of film formation, or how a colloidal dispersion dries. I will show how small angle scattering experiments (SANS/SAXS) helped to elucidate how the structure of the film changes during drying, evolving from a dilute gas of particles, into a transient gel where capillary pressures balance electrostatic repulsion, to a final aggregated solid. I will then turn to look at how the insight gained has led to a better understanding of mechanical instabilities like fracture, shear banding, birefringence, and peeling, as well as revealing an unexpected route to colloidal crystallisation.
Finally, I will summarise our recent work using neutron scattering techniques to investigate blanching, a degradation process that can cause a visible whitening in the traditional varnishes that are used as a protective outer coating on many historically and artistically important paintings.
Speaker’s website: https://www.ntu.ac.uk/staff-profiles/science-technology/lucas-goehring
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Orsolya Czakkel (College 9 Secretary)
External visitors may ask for a site access to tellier@ill.fr
Zoom link: https://ill.zoom.us/j/95581858117?pwd=[REDACTED] – Passcode: [REDACTED]

Soutenance HDR de Damien CALISTE (CEA-Irig/MEM)
2026-06-23 14:00 - 16:00 | CEA, entrée principale – Salle de soutenance (bâtiment A2), 17, avenue des Martyrs, Grenoble, 38000, France
Étude de mécanismes à l’échelle atomique pour les matériaux fonctionnels, apports de la DFT comme un outils en évolution
Résumé :
The purpose to use numerical tools is to treat problems where the analytical solutions are too complex or unknown. In the field of solid-state physics, the advent of the Density Functional Theory (DFT) had a major impact on the studies of materials at the atomic scale. Its numerous implementations and ability to efficiently run on large computing infrastructures, made it popular and it quickly became indispensable in both academic and industrial research, enabling unprecedented insights into the electronic, structural, and chemical properties of complex systems. However, the power of DFT is not solely derived from its theoretical foundations; it is equally dependent on the robustness, efficiency, and adaptability of the computational tools that implement it. ​
This defense will deal with these two aspects: material science through DFT simulations, and maintainance and development of large numerical infrastructures like a DFT code. ​
I will first address how atomistic-level simulations can be used to complement experimental characterisations, through the example of the indirect role played by Se atoms in the efficiency improvement of CdTe solar panels. Revealing such mechanisms is important for material design, driving material engineering by knowledge. ​
A second part will be dedicated to a broad overview on the physics description of a graphite electrode in a Li-ion battery. Starting from a fully charged anode, and following the deintercalation process, I will question what insights we can get from DFT calculations with the existing knowledge obtained from long-passed experiments as from more recent in-operando characterisation results. ​
​Studying the dilute regime in graphite intercalation will lead to open questions about the capability of numerical simulations to address cases where the strong interactions between the cations and the host material, compete with the binding of the layers. To properly address such questions, it is important to have available within DFT, a level of theory capable of treating inhomogeneous systems made of places where covalent bonds are dominant while in other areas van der Waals interactions take the lead. These situations can be commonly found in several classes of materials, from van der Waals heterostructures to hybrid perovskites when out-of-equilibrium processes take place, with defect / impurity diffusion or phase / structural transitions. The recent developments of versatile meta-GGAs associated to dispersion corrections, look promising and have demonstrated their ability to reproduce perfect van der Waals systems. Concurrently, their usage are restricted to some codes, hindered by the complexity in DFT implementations, isolating the diffusion of new ideas. I believe that the advent of code generation through AI is a timely opportunity to help spreading state-of-the-art DFT developments. Such thoughts will be discussed in the last part of the defense.​
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Contact : alain.farchi@cea.fr

Editathon « Femmes & Ingéniosité » 2026
2026-06-23 18:00 - 22:00 | La Casemate, 2 Place Saint-Laurent, Grenoble, 38000, France
Depuis 2017, La Casemate, centre de sciences de Grenoble et ses partenaires organisent un éditathon « Femmes & Sciences » sur des thèmes aussi variés que l’astronomie, l’environnement ou les sciences de la Terre.
Le 23 juin 2026, venez participer au 9ème éditathon « Femmes & Sciences » de La Casemate, une édition qui mettra en avant les femmes ingénieures et ingénieuses ! Cet événement est organisé à l’occasion des 25 ans de Wikipédia et de la Journée internationale des femmes ingénieures et en marge de l’exposition Batteries à La Casemate.
En savoir plus…
Inscription gratuite mais obligatoire

Mucio A. CONTINENTINO (Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro, Brazil)
2026-06-24 10:00 - 11:00 | CNRS – Salle Rémy Lemaire (K223), CNRS - Institut Néel 25 avenue des Martyrs, Grenoble, 38042, France
Dehybridization transition in multi-band systems: a renormalization group approach
Résumé :
In strongly correlated multi-band systems, such as transition metal intermetallics, heavy fermions, and Kondo insulators, electron-electron interactions lead to the damping of electronic quasiparticles at finite temperatures. This phenomenon results in an effective dehybridization between the electrons in the large conduction band and those in the narrow, correlated band. The dehybridization effect has been employed to explain the transport properties of intermetallics and the results of angle-resolved photoemission spectroscopy (ARPES) experiments on heavy fermions at sufficiently high temperatures (1). Recent insights from the theory of non-Hermitian systems provide a novel perspective on this problem. In this work, we adopt this viewpoint through a renormalization group (RG) approach. We derive RG equations for a one-dimensional two-band model to identify the exceptional points of this system and to characterize its topological properties in the presence of dissipation. Our findings reveal that for a non- trivial topological sp-chain, dehybridization can be interpreted as a topological phase transition, characterized by critical exponents that we calculate. By employing a parametrization of the self-energy in a strongly correlated system, computed numerically, we investigate the temperature dependence of the lifetime of heavy quasiparticles. From these results, a characteristic temperature related to dehybridization emerges. We discuss whether this temperature represents a new energy scale or if it is associated with the Kondo or coherence temperatures in the phase diagram of heavy fermions [2].

References
1. C. Adriano, F. Rodolakis, P. F. S. Rosa, F. Restrepo, M. A. Continentino, Z. Fisk, J. C. Campuzano, and P. G. Pagliuso, Unveiling the hybridization gap in Ce2RhIn8 heavy fermion compound, arXiv:1502.02544 [cond-mat.str-el], https://doi.org/10.48550/arXiv.1502.02544
2. Dehybridization transition in Kondo insulators and heavy fermions, arXiv:2505.04730. https://doi.org/10.48550/arXiv.2505.04730

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Contact : claudine.lacroix@neel.cnrs.fr

Louisa CASTEL (LPMMC)
2026-06-24 11:00 - 12:00 | LPMMC – salle Roger Maynard (G421), CNRS - LPMMC 25 avenue des Martyrs, Grenoble, 38042, France
Theoretical Study of Two Coupled 1D Exciton-Polariton Condensates
Résumé :
Exciton-polaritons are elementary bosonic excitations formed in a semiconductor microcavity under incoherent optical pumping. Under certain conditions, a gas of exciton polaritons can undergo a Bose-Einstein transition to form a non-equilibrium condensate, whose statistical properties are very different from those of equilibrium condensates. In this work, we explore analytically and numerically the physics of two tunnel-coupled one-dimensional exciton-polariton condensates.
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Conctact : pierre.nataf@lpmmc.cnrs.fr

Mathias GODEFROI (LPMMC)
2026-06-24 11:30 - 12:30 | LPMMC – salle Roger Maynard (G421), CNRS - LPMMC 25 avenue des Martyrs, Grenoble, 38042, France
TITRE A VENIR
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Contact : pierre.nataf@lpmmc.cnrs.fr

Elodie LAINE (Sorbone Université)
2026-06-25 13:00 - 14:00 | IMAG – Salle de Réunion, 150 place du Torrent, St Martin d’Hères, 38400, France
What evolution tells us about the impact of mutations — and how to scale it up
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Contact : lucie.lamothe@univ-grenoble-alpes.fr

Ismaele Vincent MASIELLO (TU WIEN, Austria)
2026-06-25 14:00 - 15:00 | ILL – Salle de Séminaire (110-111), ILL 50 71 avenue des Martyrs, Grenoble, 38042, France
Nonclassicality, quasiprobabilities and weak values explored in neutron interferometry
Résumé :
The violation of Bell inequalities has demonstrated that quantum mechanics exhibits features with no classical counterpart; however, identifying the boundary between quantumness and classicality remains a nontrivial task. Quasiprobability representations and weak values are valuable tools for investigating these boundaries, and their physical relevance has been confirmed across a range of impactful experiments. Several of these experiments have been implemented in neutron interferometry, a platform that has historically played a central role in the study of foundational quantum mechanics and nonclassicality. Compared to typical photonic implementations, it is less susceptible to classical reinterpretations, as it involves a single massive particle in a superposition of two or three spatially separated paths. Moreover, it offers several experimental advantages, such as macroscopic beam separation, individual control of the sub-beams, and long interaction and coherence times at room temperature and ambient pressure. In this talk, I will introduce weak values and quasiprobabilities as tools to investigate the quantum–classical boundary and present results obtained in neutron interferometry.
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Hanno Filter (College 3 Secretary)
External visitors may ask for a site access to tellier(at)ill.fr
Zoom link : https://ill.zoom.us/j/98964195699?pwd=[REDACTED] – Password : [REDACTED]

Benjamin BACQ-LABREUIL (IPCMS, Université Strasbourg)
2026-06-25 14:00 - 15:00 | CNRS – Salle Rémy Lemaire (K223), CNRS - Institut Néel 25 avenue des Martyrs, Grenoble, 38042, France
The Role of the Apical Oxygen in Cuprate High-Temperature Superconductors
Résumé :
Scanning tunneling microscopy measurements exploiting the natural superstructure modulation of the cuprate superconductor Bi$_2$Sr$_2$CaCu$_2$O$_{8+x}$ (Bi-2212) have revealed a possible correlation between the Cu-apical-O distance and the superconducting order parameter, as reported recently by O’Mahony et al. [1]. These observations were interpreted as evidence for a direct link between superconductivity and the charge-transfer gap, and more broadly revived the long-standing question of the role of apical oxygens in cuprate superconductivity. In this talk, I will discuss the impact of apical oxygen displacement on the superconducting properties of Bi$_2$Sr$_2$CuO$_{6+x}$, Bi-2212, and HgBa$_2$CuO$_{4+x}$ [2], leveraging a recently developed first-principles framework for high-temperature superconductors [3]. The quantitative agreement between our calculations and experiments allows us to unambiguously attribute the observed variations of superconducting order parameter to changes in the apical distance. We demonstrate, however, that the latter controls the former predominantly via the effective hole-doping of the CuO$_2$ planes, with negligible effect on the charge-transfer gap. The modest magnitude of the order parameter modulation induced by apical-oxygen displacement alone therefore warrants caution in interpreting correlations between $T_c$ and the apical distance inferred from comparisons across different cuprate compounds.
[1] O’Mahony, et al., Proc. Natl. Acad. Sci. 119, e2207449119 (2022)
[2] S. Vadnais, et al., arXiv:2601.16017 (2026)
[3] B. Bacq-Labreuil, et al., Phys. Rev. X 15, 021071 (2025)
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Contact : florence.levy-bertrand@neel.cnrs.fr

Christophe MASSELON (CEA-Irig/BGE) et Vincent AGACHE (CEA-Leti/DTIS)
2026-06-26 11:00 - 12:00 | IBS – Salle des séminaires, IBS 71 avenue des Martyrs, Grenoble, 38042, France
Sensing Mass at the Nanoscale : Suspended Nanochannel Resonators and NEMS-MS for Biology
Résumé :

Determining the mass of biological nanoparticles opens new avenues for characterizing biological systems at their own scale. In this joint seminar, researchers from LETI and IRIG will present two complementary nanoresonator platforms : Suspended Nanochannel Resonators (SNR), which operate in solution, and Nanoelectromechanical Mass Spectrometry (NEMS-MS), which operates in the gas phase. Together, these technologies cover a range of biological particles, from lipid nanoparticles and extracellular vesicles to viral particles. Beyond the technical principles underlying each platform, selected applications will illustrate the potential of these approaches for the characterization of biological samples.​​​​​
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Les séminaires et soutenances sont ouverts à tous, notez toutefois que l’accès au campus EPN nécessite un avis de rendez-vous. Merci de remplir ce formulaire et de l’adresser, plus de 48h à l’avance, à ce contact.
Pensez à vous munir d’une pièce d’identité le jour de votre visite.

Rémi AVRILLER
2026-06-26 11:00 - 12:00 | LPMMC – salle Roger Maynard (G421), CNRS - LPMMC 25 avenue des Martyrs, Grenoble, 38042, France
Resonance energy transfer in molecular aggregates : a stochastic approach
Le séminaire théorie est financé par la fédération de recherche Quantalps.
Résumé :
We investigate theoretically how energy dissipates and migrates from one place to another in complex and bi-dimensional molecular aggregates. In this context, a key role is played by resonance electronic energy transfer (RET) processes [1] through which an excitation initially stored onto a donor molecule (D) can be transferred to an acceptor molecule (A). Despite its long history, the mechanism of RET is still not completely understood and is the object of intense research activities and debates [2].
In this presentation, we address the question of how to describe collective and non-equilibrium effects in RET processes after all the donor molecules have been excited by a pump laser (see Fig). We predict that, due to the dimensionality of the network, the effective rate of RET scales as ^{alpha}, with the average distance between individual excited donors and their nearest-neighbor acceptor molecules, and alpha in [-6, -2] an exponent depending on the spatial distribution of molecular pairs in the 2D sample [3]. We show departures from this mean-field description arising from fluctuations and spatial correlations between several molecules involved in the RET process.
The relevance of such stochastic approaches is further investigated in order to capture the essential features of more recent experiments related to energy transfer in optical cavities [4]. In the latter case, we show as preliminary results that the interaction between pairs of molecules inside cavity can be highly modified with consequences on the kinetics of RET processes inside cavity [5].
References :
[1] T. Förster. “Transfer mechanisms of electronic excitation energy” (1960).
[2] S. Jang, M. D. Newton, and R. J. Silbey. Phys. Rev. Lett. 92, 218301 (2004).
[3] R. Avriller, A. Marché, and G. Jonusauskas, Phys. Rev. B 108, 205419 (2023).
[4] X. Zhong et al., Angewandte Chemie International Edition, 56(31), 9034-9038 (2017).
[5] K. Wu, D. Hagenmüller et R. Avriller, in preparation (2026).
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Contact : jeanne.colbois@neel.cnrs.fr

Soutenance de Thèse de Henri GRÖGER (Irig/IBS)
2026-06-26 14:00 - 16:00 | Salle des séminaires du CIBB, EPN Campus - 71 avenue des Martyrs, Grenoble, 38000, France
Structural and functional characterisation of the vaccinia virus PLD- fold endonuclease K4, telomere-binding protein i1 and the DNA polymerase complex E9A20D4
Résumé :

Poxviruses, such as the vaccinia virus (VACV) and the monkeypox virus, are large, enveloped dsDNA viruses from the orthopoxvirus genus that replicate entirely within the host cytoplasm. The 2022 and 2024 outbreaks of mpox, caused by clade IIb and Ib, respectively, have revealed the lack of efficient antivirals and underlined the urgency of understanding poxvirus biology. The poxvirus genome is flanked by short, inverted complementary hairpin telomeres that feature mismatched bases and insertions essential for viral replication. ​
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This thesis presents the structural and functional characterisation of three proteins central to poxvirus DNA metabolism : the E9A20D4 DNA polymerase holoenzyme, and two telomere-interacting proteins, the PLD-fold nuclease K4 and I1. The project initially focused on the VACV polymerase holoenzyme, but was reoriented towards the telomere-interacting proteins following the publication of numerous competing mpox polymerase structures. ​
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Having established that VACV polymerase activity requires K+ and is inhibited by Na+, I undertook a structure determination of the E9A20D4 polymerase holoenzyme bound to template DNA, primer and incoming nucleotide in the presence of K+, using single-particle cryogenic electron microscopy (cryo-EM). I obtained both the structure of the complex E9exo−A20D4 as well as the structure of E9exo− alone bound to the primer-template DNA. The structures in the presence of K+ appear identical to published structures in the presence of Na+. However, I identified an ion binding site in the exonuclease domain of E9. The thumb domain is disordered in the DNA-free structure, partially disordered in DNA-bound E9 and ordered in the holoenzyme-DNA complex. SAXS data indicate conformational flexibility, with more open conformations of E9A20D4 lacking an E9-D4 interface, while mass photometry reveals partial dissociation of E9A20D4 at low concentrations, even in the presence of substrate. ​
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Using cryo-EM, I report the first structures of K4 in both apo and DNA-bound states, revealing that the active site is occluded by an orthopoxvirus-specific C-terminal extension of the PLD fold that is displaced upon DNA binding. Biochemical characterisation demonstrates that K4 functions as a DNA-specific endonuclease with a preference for single-stranded DNA and hairpin loops. ​
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I also report the first cryo-EM structure of I1 bound to DNA. I1 is known to bind to viral telomeres and is essential for virion maturation. Cryo-EM data showed the presence of dimers where the head domains 2 and 3 of I1 interact with the DNA duplex through electrostatic interactions, while the N-terminal domain predicted to be α-helical remains disordered. In solution, isolated I1 or I1 bound to DNA forms higher-order assemblies, predominantly tetramers, but also octamers. ​
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​ Altogether, these findings substantially advance the molecular understanding of poxvirus biology, providing a foundation for future mechanistic studies and the rational development of antiviral strategies against emerging orthopoxvirus infections.
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Les séminaires et soutenances sont ouverts à tous, notez toutefois que l’accès au campus EPN nécessite un avis de rendez-vous. Merci de remplir ce formulaire et de l’adresser, plus de 48h à l’avance, à ibs.seminaires@ibs.fr. Pensez à vous munir d’une pièce d’identité le jour de votre visite.

Dario DAGHERO (Department of Applied Science and Technology, Politecnico di Torino)
2026-06-29 14:00 - 15:00 | CNRS – Salle Louis Weil (E424), CNRS - Institut Néel 25 avenue des Martyrs, Grenoble, 38042, France
Point Contact Andreev-Reflection Spectroscopy : mechanisms, models and examples
Résumé :
Point-contact spectroscopy [1] in superconductors, also known as point-contact Andreev-Reflection spectroscopy (PCARS) is a simple but powerful and versatile technique that allows a direct determination of the number, the amplitude and the symmetry of the energy gap(s) in superconducting materials [2,3]. The technique is rather simple in principle, i.e. it just consists in creating a small (point-like) contact between a normal metal and a superconductor, and to measure its differential conductance as a function of the bias voltage across the junction. However, there are several complications that make this simple recipe fairly difficult to realize in practice. First of all, the contact must be in the spectroscopic regime [1,2,3], i.e. electrons from the normal metal must be injected in the superconductor with an excess energy that coincides with eV, V being the bias voltage. Hence, they must not lose energy in the banks and in the contact itself. The ideal condition is that of ballistic conduction through the N/S interface, which ensures no Joule effect and requires in turns that the contact size is smaller than both the coherence length and the electronic mean free path in the superconductor.
When these conditions are met, the conduction through the contact is dominated by Andreev reflection, a quantum phenomenon that is responsible for the conversion of the normal current into supercurrent, and occurs in a specific range of voltages (electron energies) set by the amplitude of the superconducting gap. Several models have been proposed to describe the phenomenon and are currently used to extract information on the amplitude and symmetry of the order parameter from the spectra. The simplest one [4] was only suited for superconductors with an isotropic (s-wave) gap, but has been successfully generalized to the case of layered materials with anisotropic gaps, like cuprates [5,6] or strontium ruthenate [7]) and finally to the 3D case, while taking into account the shape of the actual Fermi surface [3]. The latter generalization allows calculating the point-contact spectrum for any symmetry of the order parameter, including exotic ones with horizontal node lines.
After discussing these general aspects, I will briefly describe the application of the technique to some example materials, from the conventional multiband superconductors MgB2 [8] to unconventional ones like Pu-based heavy fermion compounds [9] or Fe-based compounds [3], to transition-metal dichalcogenides [10].
References
1. Y. G. Naidyuk and I. K. Yanson, Point-Contact Spectroscopy, Springer Series in Solid-State Sciences, Vol. 145 (Springer, 2004).
2. D. Daghero and R.S. Gonnelli, Supercond. Sci. Technol. 23, 043001 (2010).
3. D. Daghero et al., Rep. Prog. Phys. 74, 124509 (2011).
4. G. E. Blonder, M. Tinkham and T. M. Klapwijk, Phys. Rev. B 25, 4515 (1982)
5. Y. Tanaka and S. Kashiwaya, Phys. Rev. Lett. 74, 3451 (1995)
6. S. Kashiwaya and Y. Tanaka, Rep. Prog. Phys. 63, 1641 (2000).
7. M. Yamashiro, Y. Tanaka, and S. Kashiwaya, Phys. Rev. B 56, 7847 (1997)
8. R. S. Gonnelli et al., Phys Rev. Lett. 89, 247004 (2002)
9. D. Daghero et al., Nature Communications 3, 786 (2012)
10. E. Piatti et al., Materials Today Physics 59 (2025) 101883
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Contact : matteo.dastuto@neel.cnrs.fr

Carlotta PORZIO (CERN, Switzerland)
2026-06-30 10:30 - 11:30 | ILL – Salle de Séminaire (110-111), ILL 50 71 avenue des Martyrs, Grenoble, 38042, France
Experimental activities at the ISOLDE-CERN facility
Résumé :
The ISOLDE factily at CERN is one of the world-leading laboratories for the production of radioactive ion beams (RIBs) with the ISOL (Isotope Separation On-Line) method. More than 1000 isotopes of over 70 chemical elements have been produced via the interaction of a 1.4 GeV proton beam with a variety of target materials. After ionization and mass separation, the beams can be delivered at low energy or post-accelerated up to about 10 MeV/u using the HIE-ISOLDE linear accelerator. The facility supports a broad scientific program, spanning nuclear structure studies, nuclear astrophysics, materials science, life sciences, and investigations of fundamental interactions.
Among the experimental setups available at HIE-ISOLDE, the Miniball gamma-ray spectrometer is employed to investigate both collective and single-particle properties of exotic nuclei. Combined with the post-accelerated radioactive ion beams, Miniball enables nuclear structure studies via Coulomb excitation and nucleon-transfer reactions.
This seminar will provide an introduction to the ISOLDE facility and the ISOL RIB production method, and an overview of experimental setups and techniques, with a focus on the Miniball spectrometer.
—
Hanno Filter (College 3 Secretary
External visitors may ask for a site access to tellier@ill.fr

Soutenance de Thèse par Hanna KARAOUI (CEA-Irig/Spintec)
2026-07-07 14:00 - 16:00 | CEA – Salle de Séminaire IRIG (1005 – 445), Laboratoire Irig/Spintec, salle de séminaire 445, bâtiment 1005, CEA-Grenoble, Grenoble
Perpendicular anisotropy interfaces for high-efficiency low power spintronics
Résumé :
L’augmentation de la consommation mondiale d’énergie accentue le besoin de stockage de données à haute efficacité, orientant la recherche vers des mémoires non volatiles à faible puissance comme la MRAM (Magnetoresistive Random Access Memory) à couple de transfert de spin. Les jonctions tunnel magnétiques (MTJ) perpendiculaires conventionnelles font face à un compromis critique lors de la réduction d’échelle, l’anisotropie magnétique d’interface diminue, imposant un dilemme entre stabilité thermique et efficacité de commutation. Les structures doubles-MTJ (DMTJ) répondent théoriquement à ce problème en insérant la couche de stockage (SL) entre deux barrières de MgO, bien qu’elles souffrent souvent d’une fabrication complexe et de l’instabilité des couches de référence supérieures. Cette thèse étudie une architecture innovante nommée ASL-DMTJ, où le polariseur fixe supérieur est remplacé par une couche d’assistance magnétique (ASL) à aimantation libre. Cette ASL interagit dynamiquement avec la couche de stockage par couple de transfert de spin et couplage ferromagnétique, renforçant la stabilité par alignement magnétostatique et permettant une rétention élevée ainsi qu’une commutation à très faible puissance. Afin d’évaluer les performances via l’intégration de cette ASL, un cadre de modélisation macrospin complet a été établi pour étudier les propriétés magnétostatiques et dynamiques. L’analyse du profil énergétique démontre que la stabilité thermique du système dépend de l’anisotropie interfaciale liée à l’épaisseur et du couplage dipolaire mutuel. Tandis que la réduction de l’épaisseur de la SL diminue intrinsèquement la barrière d’énergie, l’inclusion du couplage dipolaire renforce la stabilité globale en favorisant les configurations parallèles, agissant comme un mécanisme vital pour la rétention des données. Des investigations numériques mettent en évidence un mécanisme de commutation par étapes où la SL bénéficie des couples cumulatifs fournis par les couches de référence et d’assistance, garantissant que la SL reste la couche la plus stable tandis que l’ASL facilite le renversement. Sur le plan expérimental, une étude comparative démontre que les structures à double MgO offrent des propriétés de transport nettement améliorées par rapport aux implémentations à triple MgO en éliminant la résistance parasite. En optimisant l’épaisseur et l’oxydation de la barrière tunnel, des valeurs de magnétorésistance tunnel optimisées ont été obtenues. L’utilisation systématique d’échantillons en double-MgO avec l’interface inférieure FeCoB/MgO sert de barrière principale, tandis que l’interface supérieure est cruciale pour maximiser le champ d’anisotropie effectif. L’optimisation des matériaux a confirmé que les échantillons conservant une couche magnétique à l’interface MgO supérieure offrent une stablité dépassant le seuil de stabilité thermique requis de 40kBT avec une symétrie de commutation élevée. Enfin, l’efficacité de commutation a été quantifiée via les distributions du taux d’erreur d’écriture sur des impulsions allant de 4 ns à 10 µs. Nous avons introduit un modèle unifié capturant la dépendance de la tension critique par rapport à la largeur d’impulsion à travers les régimes balistiques et thermiquement assistés. Ce modèle identifie un seuil de commutation caractéristique centré sur le point d’énergie minimale, introduisant une nouvelle figure de mérite, le rapport entre la barrière de stabilité thermique et l’énergie de commutation minimale, fournissant une estimation plus précise de l’énergie opérationnelle. Les résultats expérimentaux ont montré une dépendance linéaire de la barrière d’énergie vis-à-vis du diamètre, prouvant un mécanisme de commutation régi par la nucléation de domaines et la propagation de parois plutôt que par un modèle macrospin pur. Les calculs analytiques et expérimentaux confirment que les champs de fuite de la couche de référence modulent significativement ces barrières.
La hausse de la consommation énergétique mondiale pousse au développement de mémoires plus sobres comme la MRAM (Magnetoresistive Random Access Memory). Mais en dessous de 20 nm, les jonctions magnétiques classiques perdent en stabilité ou en efficacité. Cette thèse étudie une architecture innovante, appelée ASL-DMTJ, où une couche magnétique d’assistance aide la couche de stockage à conserver l’information tout en facilitant l’écriture avec peu d’énergie. Des modèles montrent que les interactions magnétiques internes renforcent la stabilité malgré la miniaturisation. Les expériences confirment que des structures à double barrière MgO améliorent les performances et réduisent les pertes. Un nouveau modèle de commutation est aussi proposé pour mieux estimer l’énergie nécessaire. Ces travaux ouvrent la voie à des mémoires plus petites, rapides et économes en énergie.Face à l’explosion de la consommation numérique, nos appareils ont besoin de mémoires plus économes. La technologie MRAM est une candidate idéale car elle conserve les données sans électricité. Cependant, miniaturiser ces mémoires réduit leur stabilité , les données risquent de s’effacer. Cette thèse explore une architecture innovante, la “ASL-DMTJ”. L’idée est d’entourer la couche de stockage d’informations par deux barrières protectrices et d’ajouter une couche d’assistance magnétique. Cette dernière agit comme un guide dynamique qui aide à l’écriture des données tout en renforçant leur maintien dans le temps. En combinant simulations numériques et tests réels, ces travaux prouvent que ce design permet de créer des mémoires ultra-stables et rapides. L’étude montre aussi que le basculement de l’information se passe à point d’énergie minimale, offrant une grande efficacité énergétique. Ce nouveau modèle architectural permet d’envisager des technologies dont la consommation électrique serait drastiquement réduite.
Plus d’information
Pour suivre la soutenance ​​​en visioconférence zoom​ ​​ – Meeting ID : 987 6986 7024 – Passcode : [REDACTED]​
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ATTENTION ! L’entrée du site CEA-Grenoble nécessite une autorisation préalable et sur présentation de votre pièce d’identité le jour de votre venue (CI ou passeport, car le permis de conduire n’est pas recevable).
Veuillez impétaivement nous contacter par mail avant le 26 juin : admin.spintec@cea.fr​Note: Entry to the CEA-Grenoble site requires prior authorization and the presentation of your ID on the day of your visit (ID card or passport; driver’s licenses are not accepted).
Please request this authorization before June 26th to admin.spintec@cea.fr​

X-Ray and neutron Science
2026-09-02 00:00 - 2026-09-29 23:59 | ILL – Salle de Séminaire (SB-036), ILL 71 avenue des Martyrs, Grenoble, 38042, France
International Summer Programme on Neutron and X-Ray Science for undergraduate students
More information is available on the website :
https://workshops.ill.fr/e/SummerSchool2026 and on the poster
It is a very interesting opportunity for undergraduate students to discover these techniques and the science at our institutes. We would be grateful if you forward this information to students who may be interested. Applications close on February 28th.
Contact : summerschool-2026@ill.eu

Recent Advances in Quantum Integrable Systems 2026 (RAQIS)
2026-09-07 00:00 - 2026-09-11 23:59 | LAPTh – Auditorium, 9, chemin de Bellevue, Annecy, 74940, France
The conference aims at bringing in contact people working on various aspects of Quantum Integrable Systems, including applications to Statistical Physics, Condensed Matter and Field Theories.
The registration to the conference can be done through the website https://indico.in2p3.fr/event/38960/

It will be closed on July 31th, 2026.
Note also that the early fees period will end by the end of June 2026.
Fees include lunches, conference banquet and coffea breaks.
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Contact : raqis@lapth.cnrs.fr

Cecile ENGRAND
2026-10-08 16:00 - 17:00 | Laboratoire IJCLab – Auditorium Pierre Lehmann, Rue Ampère, Orsay cedex, 91898, France
Les micrométéorites : les messagères de notre origine
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Toutes les informations sont disponibles sur : https://indico.ijclab.in2p3.fr/event/13491/
Contact : louis.fayard@IJCLAB.INP3.FR

Christophe SALOMON
2026-10-15 16:00 - 17:00 | Laboratoire IJCLab – Auditorium Pierre Lehmann, Rue Ampère, Orsay cedex, 91898, France
Atomes froids et mesure précise du temps
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Toutes les informations sont disponibles sur : https://indico.ijclab.in2p3.fr/event/13426/
Contact : louis.fayard@IJCLAB.INP3.FR

Journées de la Matière Condensée (JMC 2026)
2026-10-26 08:00 - 2026-10-30 14:00 | Université de Toulouse – Auditorium Marthe Condat, 118, route de Narbonne, Toulouse, 31400, France
Ces journées rassemblent la communauté scientifiques autour des thématiques relevant de la matière condensée, des concepts aux applications. Le succès de ces journées en fait l’un des plus grand congrès de Physique en France et l’une des plus grandes rencontres de la physique de la Matière Condensée en Europe.
La soumission des résumés est ouverte et le restera jusqu’à fin mai.
Nous vous encourageons à vous inscrire dès l’ouverture afin de :

bénéficier du tarif préférentiel,
garantir votre participation,
faciliter l’organisation scientifique et logistique.

Toutes les informations pratiques (programme préliminaire, conférencier·es invités, modalités d’inscription, hébergement) sont régulièrement mis à jour sur le site de la conférence (Journées de la Matière Condensée 2026 – Sciencesconf.org)
Nous espérons vous retrouver nombreuses et nombreux pour cette nouvelle édition des JMC !

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We are pleased to announce the Journées de la matière condensée JMC 2026 (Condensed Matter Days 2026), which will be held from 26 to 30 October in Toulouse.
This conference brings together the scientific community to discuss topics related to condensed matter, from concepts to applications. The success of this conference makes it one of the largest physics conferences in France and one of the largest gatherings of condensed matter physicists in Europe.
Abstract submission is open and will remain so until the end of May.
We encourage you to register as soon as possible in order to benefit from the preferential rate, guarantee your participation, facilitate scientific and logistical organisation.
All practical information (preliminary programme, guest speakers, registration details, accommodation) is available on the conference website: Journées de la Matière Condensée 2026 – Sciencesconf.org

We hope to see many of you at this new edition of the JMC !

European Conference on Neutron Scattering
2027-06-27 00:00 - 2027-07-01 23:59 | Université Grenoble Alpes (UGA), 621 avenue Centrale, Saint-Martin-d'Hères, 38400, France
Hosted in the heart of the French Alps and home to the Institut Laue Langevin (ILL), Grenoble provides an inspiring setting for this premier neutron science event.
ECNS 2027 will highlight the vital role of neutron research in addressing major societal challenges.

The celebration of the 60th anniversary of the ILL will take place on 2 July at the ECNS2027 venue.

We warmly invite the international neutron community to join us for a week of scientific exchange and collaboration.
Contact : ecns2027_contact@ill.eu
