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International audience; To enhance the performance of micro-patterned gaseous detectors (MPGDs) to meet thechallenging requirements of future high energy physics (HEP) experiments, two-dimensional (2D)materials are attractive candidates to address the back flow of positive ions, which affectsdetector performance by distorting electric field lines. In this context, graphene is promisingto work as selective filter for ion back flow suppression, being transparent to electrons while atthe same time blocking ions. Also, graphene membranes can physically separate drift andamplification regions of the detectors, offering additional flexibility in the choice of gasmixtures and allowing independent optimizations of detector sensitivity and electronmultiplication processes. Here we present an approach to integrate graphene grown via chemicalvapor deposition (CVD) on gaseous electron multiplier (GEM) prototypes via a wet transferprocedure in order to suspend graphene over thousands of holes with 60 μm diameter and overcomethe challenges encountered due to process steps involving liquids, mostly related with thecapillary effects during drying and evaporation of them. In order to overcome the risk of damagingthe membrane and decreasing the yield of suspended 2D material membranes, critical point dryer(CPD) and inverted floating method (IFM) procedures are investigated. In addition to thenecessity to cover the full holes in the active area, polymeric residuals have to be minimized inorder to evaluate the graphene transparency at the electron energies (i.e., < 15 eV) typicallyobtained in the operating conditions, measurements in these energy ranges are still not deeplyinvestigated.

International audience; Topological physics relies on the existence of Hamiltonian's eigenstate singularities carrying a topological charge, such as quantum vortices, Dirac points, Weyl points and -- in non-Hermitian systems -- exceptional points (EPs), lines or surfaces. They appear only in pairs connected by a Fermi arc and are related to a Hermitian singularity, such as a Dirac point. The annihilation of 2D Dirac points carrying opposite charges has been experimentally reported. It remained elusive for Weyl points and second order EPs terminating different Fermi arcs. Here, we observe the annihilation of second order EPs issued from different Dirac points forming distinct valleys. We study a liquid crystal microcavity with voltage-controlled birefringence and TE-TM photonic spin-orbit-coupling. Two neighboring modes can be described by a two-band Hermitian Hamiltonian showing two topological phases with either two same-sign or four opposite-sign Dirac points (valleys). Non-Hermiticity is provided by polarization-dependent losses, which split Dirac points into pairs of EPs, connected by Fermi arcs. We measure their topological charges and control their displacement in reciprocal space by increasing the non-Hermiticity degree. EPs of opposite charges from different valleys meet and annihilate, connecting in a closed line the different Fermi arcs. This non-Hermitian topological transition occurs only when the Hermitian part of the Hamiltonian is topologically trivial (with four valleys), but is distinct from the Hermitian transition. Our results offer new perspectives of versatile manipulation of EPs, opening the new field of non-Hermitian valley-physics.

International audience; The nature of the zero-temperature phase diagram of the spin-1/2J1-J2 Heisenberg model on a square lattice has been debated in the past three decades, and it remains one of the fundamental problems unsettled in the study of quantum many-body theory. By using the state-of-the-art tensor network method, specifically, the finite projected entangled pair state (PEPS) algorithm, to simulate the global phase diagram of the J1-J2 Heisenberg model up to 24×24 sites, we provide very solid evidences to show that the nature of the intermediate nonmagnetic phase is a gapless quantum spin liquid (QSL), whose spin-spin and dimer-dimer correlations both decay with a power law behavior. There also exists a valence-bond solid (VBS) phase in a very narrow region 0.56≲J2/J1≤0.61 before the system enters the well known collinear antiferromagnetic phase. We stress that we make the first detailed comparison between the results of PEPS and the well-established density matrix renormalization group (DMRG) method through one-to-one direct benchmark for small system sizes, and thus give rise to a very solid PEPS calculation beyond DMRG. Our numerical evidences explicitly demonstrate the huge power of PEPS for highly frustrated spin systems. Finally, an effective field theory is also proposed to understand the physical nature of the discovered gapless QSL and its relation to deconfined quantum critical point (DQCP).

Dye lasers have been the very first coherent tunable sources in the history of lasers. These lasers, based on dye solution circulation, are now considered too bulky and painful to operate, pushing research towards the exploration of various solid-state alternatives. But these solid-state alternatives suffer from low power, poor photo-stability and cannot be operated in Continuous wave (CW)/quasi-Continuous wave (q-CW). Therefore, to find a possible solution this work explores for the first time the photo-stability performance obtained with a design in which a spectroscopic cuvette filled with dye solution without any circulation is used as a gain medium under diode-pumping, making a low-cost, compact and user-friendly laser which can be compared to solid-state dye lasers but with the stability of older generation liquid dye lasers. The reported laser, in addition of being efficient (optical efficiency ~ 18%) is photo-stable up to roughly a billion of pulses at 1 kHz repetition rate, which is 5 orders of magnitude higher than the photo-stability of a solid-state dye laser in the same conditions. This unusually high photo-stability maybe attributed to molecular diffusion or slow convective flow of molecules due to localized heating in the medium, which might be sufficient to allow a replenishment of the gain medium between consecutive pulses. However, despite being highly photostable, the laser could not be operated beyond 2.4 kHz and could not produce pulse duration longer than few μs. We show here that their operational limit in repetition rates is not due to a fundamental limit imposed by triplet state accumulation in the organic compound which is often assumed to be the case in solid-state organic lasers. Instead, we demonstrate that this limit is due to thermal lensing. We measured the aberration-free component of the thermal lens by a pump-probe experiment and demonstrated a possible prolongation of lasing up to 14 kHz with a proper thermal lens intracavity correction. To check the universality of our claim, we also tested a second dye and found similar results. In contrast, solid-state dye lasers need a moving gain medium in order to be operated at high repetition rates and overcome abrupt photodegradation. Finally, we show that these lasers can also produce up to 80 μs lasing when they are highly multimode. Though we demonstrated such long pulse operation experimentally, more theoretical, and experimental investigation is required to understand their multimode lasing behavior which can be a future perspective of this work. Another perspective of this work would be to investigate mode-locking in organic laser which requires that the laser should be ideally CW or q-CW. We believe that our laser can be a good candidate for investigating such laser applications and hence, at the end of this thesis, we also give some useful direction and pathways to develop a low cost, compact, user friendly and tunable mode-locked organic in laser in future., Les lasers à colorant ont été les toutes premières sources cohérentes accordables dans l'histoire des lasers. Ces lasers, basés sur la circulation d'une solution de colorant, sont maintenant considérés comme trop encombrants et pénibles à utiliser, ce qui pousse la recherche vers l'exploration de diverses alternatives à l'état solide. Mais ces alternatives à l'état solide souffrent d'une faible puissance, d'une mauvaise photo stabilité et ne peuvent pas être utilisées en onde continue (CW)/quasi-continue (q-CW). Par conséquent, pour trouver une solution possible, ce travail explore pour la première fois la performance de la stabilité photo- stabilité obtenue avec une conception dans laquelle une cuvette spectroscopique remplie d'une solution de colorant sans aucune circulation est utilisée comme milieu de gain sous pompage par diode, ce qui permet d'obtenir un laser peu coûteux, compact et convivial qui peut être comparé aux lasers à colorant à l'état solide mais avec la stabilité des lasers à colorant liquide d'ancienne génération. Le laser présenté, en plus d'être efficace (efficacité optique ~ 18%) est photos table jusqu'à environ un milliard d'impulsions à une fréquence de répétition de 1 kHz, ce qui est 5 ordres de grandeur plus élevé que la photo stabilité d'un laser à colorant à l'état solide dans les mêmes conditions. Cette photo stabilité exceptionnellement élevée peut être attribuée à la diffusion moléculaire ou à un lent flux convectif de molécules dû à un chauffage localisé dans le milieu, ce qui pourrait être suffisant pour permettre un renouvellement du milieu de gain entre des impulsions consécutives. Cependant, malgré sa grande photo stabilité, le laser n'a pas pu fonctionner au-delà de 2,4 kHz et n'a pas pu produire des durées d'impulsion supérieures à quelques μs. Nous montrons ici que leur limite opérationnelle en termes de taux de répétition n'est pas due à une limite fondamentale imposée par l'accumulation d'états triplets dans le composé organique, ce qui est souvent supposé être le cas dans les lasers organiques à l'état solide. Au contraire, nous démontrons que cette limite est due à la lentille thermique. Nous avons mesuré la composante sans aberration de la lentille thermique par une expérience pompe-sonde et démontré une prolongation possible de l'effet laser jusqu'à 14 kHz avec une correction intracavité appropriée de la lentille thermique. Pour vérifier l'universalité de notre affirmation, nous avons également testé un second colorant et avons obtenu des résultats similaires. En revanche, les lasers à colorant à l'état solide ont besoin d'un milieu de gain mobile afin de fonctionner à des taux de répétition élevés et de surmonter une photo dégradation abrupte. Enfin, nous montrons que ces lasers peuvent également produire un effet laser allant jusqu'à 80 μs lorsqu'ils sont fortement multimodes. Bien que nous ayons démontré expérimentalement le fonctionnement de ces longues impulsions, des recherches théoriques et expérimentales supplémentaires sont nécessaires pour comprendre leur comportement multimode, ce qui peut être une perspective future de ce travail. Une autre perspective de ce travail serait d'étudier le verrouillage de mode dans un laser organique, ce qui nécessite que le laser soit idéalement CW ou q-CW. Nous pensons que notre laser peut être un bon candidat pour l'étude de telles applications laser et donc, à la fin de cette thèse, nous donnons également quelques directions et voies utiles pour développer un laser organique à verrouillage de mode à faible coût, compact, convivial et accordable dans le futur.

In this note we report on the development plans and first results of the Grenoble Axion Haloscope (GrAHal) project. It is aimed at developing a haloscope platform dedicated to the search for axion dark matter particles. We discuss its general framework and the plans to reach the sensitivity required to probe well known invisible axion models, over particularly relevant axion masses and coupling regions. We also present our first haloscope prototype and the result of its test run at liquid He temperature, setting a new exclusion limit $g_{a \gamma \gamma} \leq 2.2 \times 10^{-13}~ \text{GeV}^{-1}$ ($g_{a \gamma \gamma} \leq 22 \times g_{\text{KSVZ}}$) around 6.375 GHz ($m_a \simeq 26.37$ $\mu \text{eV}$)., Comment: 5 pages

The negatively charged nitrogen-vacancy (NV) center in nano- or micro- diamonds has emerged as a promising magnetic field sensor, as a candidate for hyper-polarizing paramagnetic species, as well as a tool for spin-mechanics at the nanoscale. However, NV-doped diamonds are presently not straightforwardly employable for these applications in a liquid or when levitating under atmospheric pressures due to the random angular Brownian motion which tends to rotate the NV quantization axis over the course of the measurments. Here, we report on angle locking of the crystalline axis of a trapped micro-diamond along an external magnetic field. Specifically, we use spin population inversion after a ground state level crossing of the NV center to turn the diamond into a diamagnet. The diamond crystalline axis naturally aligns to the magnetic field with high precision and in the absence of micro-wave, offering bright prospects for applications in biology and spin-mechanical platforms., Comment: 13 pages

International audience; This paper presents the design of a new Positron Emission Tomography (PET) with improved time resolution, Time-Of-Flight PET (TOF-PET). Using the time information improves image quality and reduces the radiation dose inoculated to patients. Extended Field-Of-View (FOV) total-body scanner built from low-radioactivity liquid argon (LAr) scintillator (LAr-TOF-PET) and silicon photomultipliers (SiPMs) are readout by fast cryogenic electronics. This new concept is based on the emerging technology coming from the field of direct dark matter searches for weakly interacting massive particles (WIMPs). The DarkSide Collaboration has been particularly successful in demonstrating the true power of the advancing LAr detector technology. SiPM technology has many broader applications in science and industry, most notably in medical physics, where exquisite timing resolution of SiPMs could revolutionize PET, one of the key tools in a diagnosis of cancer, allowing one to substantially improve precision and at the same time minimize adverse side-effects to the patient. We simulated this design using Geant4 toolkit while following the National Electrical Manufacturers Association’s evaluation tests for performance assessment. We will present results that highlight a 200-fold increase in sensitivity, spatial resolutions comparable to commercial PET scanners and produce PET images from 15-30 second scans, faster than traditional 30-35-minute scans. Further studies will involve optimizing the layer thickness of LAr+Xe. Moreover, scintillation induced ionization electrons can produce Cherenkov radiation along with the LAr+Xe scintillation light. With the LAr+Xe scintillator and SiPMs of 3Dπ, we can use the precise TOF info of gamma rays to improve the localization of individual positron annihilations, and as one example benefit, provide low-dose PET scans for patients who may be at high risk for exposure to radiation.

International audience; Plasma jets are being intensively researched for cancer therapy with encouraging initial clinical outcomes already realised. However, the fine control of plasma jets remains challenging due to the mutual interaction between plasma and target [1]. Even considering perhaps one of the simplest scenarios in a research laboratory, using a plasma jet to treat a 2D culture of cells in a plastic multi-well plate, it is not known in detail how the physical environment of the micro-well may influence the nature of the plasma jet treatment. This study aims to shed light into this topic by investigating how electro fluid dynamic (EFD) flows influence the delivery of the bioactive plasma-generated RONS when a plasma jet is used to treat a conductive biologically-relevant liquid (i.e. PBS) in a standard tissue culture grade 24-well plate [2]. The results show how the formation of complex EFD flows in the liquid induce a non-uniform distribution of the RONS, especially within the first few seconds of treatment (Fig. 1a). Shortly after the ignition of the plasma jet an initial rapid liquid stream can reach the bottom of the well, whereas a stable vortex mixing is observed few seconds later (Fig. 1b). Experimental results indicate that electric charge accumulation on the liquid surface and plasma induced gas swirling could be the causes of the liquid motions. Furthermore, the liquid depth and the voltage polarity were found to be critical parameters in controlling the delivery of the RONS to the bottom of the well. A multijet plasma source was, then, used for the treatment of PBS (pPBS), which was combined with a pulsed electric field (PEF) to permeabilise B16-F10 murine melanoma cells. Compared to PEF alone, the combined treatment with pPBS (applied before and after PEF exposure) can greatly increase the number of permeabilised cells and the uptake of a model non-permeant molecule (Yo-Pro®-1) to confirm the permeability of the cell membrane (Fig. 1c). This synergistic effect of plasma treated PBS and PEF could open new opportunities for the application of plasma jets in electrochemotherapy

We report results of large scale quantum Monte Carlo (QMC) simulations of graphene. Using cutting-edge algorithmic improvements, we are able to consider spatial volumes, corresponding to 20808 electrons, that allow us to access energy scales of direct relevance to experiments. Using constrained random phase approximation (cRPA) estimates of short ranged interactions combined with a Coulomb tail akin to the vacuum, we are able to confront successfully numerical and experimental estimates of the Fermi velocity renormalization. These results and their comparison with perturbation theory not only show the non-Fermi liquid character of graphene, but also prove the importance of lattice-scale physics for the quantitative description of the experimental data for the Fermi velocity renormalization in suspended graphene., Comment: 17 pages, 6 figures plus Supplementary material

National audience; Plasma jets are intensively studied for biomedicine applications but their fine control remains challenging due to the mutual interactions between plasma and target. Even considering the simplest scenario in a research laboratory, a plasma jet treating a 2D culture of cells, it is not known in detail how the physical environment of the micro-well may influence the treatment. This study aims to shed light on this topic by investigating how electro fluid dynamic (EFD) flows influence the delivery of the bioactive plasmagenerated reactive species when a plasma jet is used to treat a biologicallyrelevant liquid (i.e. PBS) in a standard tissue culture grade 24-well plate. The results show how the formation of complex EFD flows in the liquid induce a non-uniform distribution species. Shortly after the ignition of the plasma jet a fast stream can reach the bottom of the well, whereas a stable toroidal vortex mixing is observed few seconds later. Electric charge accumulation on the liquid surface and plasma induced gas swirling could be the causes of the liquid motions. Furthermore, the liquid depth/volume and the voltage polarity are found to be critical parameters in controlling the delivery of the RONS to the bottom of the well.

International audience; A coupled thermodynamic/kinetic CALPHAD type modeling of the glass transition for a glass forming unary substance is proposed. In this quantitative modeling, the vibrational contributions to the thermodynamic functions of the crystal and liquid/glass phases are classically modeled using weighed sums of Einstein functions while the configurational contributions to the liquid/glass phase functions are described using a single internal variable within the frame of the ideal two-state model. The freezing kinetics of this internal variable on cooling is calculated with an Adam-Gibbs logarithmic relaxation law. The model is applied to the boron oxide B2O3 and, after a numerical optimization of the parameters, is shown to well represent the hysteresis loop of the heat capacity detected by DSC in the glass transition range during cooling/reheating cycles at various rates. The model also allows to calculate the fictive temperature and residual or zero-point entropy of the glass.

The contact between a cylindrical flat indenter and an incompressible, nonviscous liquid is considered. The behaviour is totally controlled by the assumed constant surface tension and gravity. An analytical approach and a numerical solution are developed to describe the shape of the surface as a function of the applied force. In the absence of an exact solution, an approximate solution is proposed.

International audience; Oxylipins are potent lipid mediators involved in a variety of physiological processes. Their profiling has the potential to provide a wealth of information regarding human health and disease and is a promising technology for translation into clinical applications. However, results generated by independent groups are rarely comparable, which increases the need for the implementation of internationally agreed upon protocols. We performed an interlaboratory comparison for the MS-based quantitative analysis of total oxylipins. Five independent laboratories assessed the technical variability and comparability of 133 oxylipins using a harmonized and standardized protocol, common biological materials (i.e., seven quality control plasmas), standard calibration series, and analytical methods. The quantitative analysis was based on a standard calibration series with isotopically labeled internal standards. Using the standardized protocol, the technical variance was within +/- 15% for 73% of oxylipins; however, most epoxy fatty acids were identified as critical analytes due to high variabilities in concentrations. The comparability of concentrations determined by the laboratories was examined using consensus value estimates and unsupervised/supervised multivariate analysis (i.e., principal component analysis and partial least squares discriminant analysis). Interlaboratory variability was limited and did not interfere with our ability to distinguish the different plasmas. Moreover, all laboratories were able to identify similar differences between plasmas. In summary, we show that by using a standardized protocol for sample preparation, low technical variability can be achieved. Harmonization of all oxylipin extraction and analysis steps led to reliable, reproducible, and comparable oxylipin concentrations in independent laboratories, allowing the generation of biologically meaningful oxylipin patterns.

The electrical charges naturally present at liquid/solid interfaces or which develop in liquids in a controlled or undesired way are at the origin both of numerous applications (micro-pumps, lab-on-a-chip, super-capacitors) and of industrial risks (inflammations, explosions). This requires the most precise possible quantification of the values and distributions of these charges in liquid dielectric media. The present measurement techniques are either non-resolutive, as the responses measured on the entire specimen allow to deduce information about the charges and the associated processes indirectly (through models), or limited in terms of sensitivity and resolution. For example, the electrical double layer model, proposed by Stern in 1924 and fully accepted by the scientific community since then, has not been confirmed experimentally yet, in particular due to the lack of resolution and sensitivity of the existing methods.Several techniques have been developed since 1980 to measure directly and non-destructively the electrical charges in solid insulators. Among these methods, those based on the application of low-amplitude thermal stimuli have shown high sensitivity and performance for the measurement of loads near interfaces. The application of these techniques to liquids is a research path to be explored in order to answer the above scientific and applicative questions. This work studies, both from theoretical and experimental points of view, the application of the thermal step principle to the measurement of electrical charges in insulating liquids. The electrical double layer, which sets up at the level of the liquid/solid walls, is used as object of the study. Several dielectric liquids are concerned: cyclohexane in liquid and solid state, pure and additive mineral oil and silicone oil.Through numerical simulations, electrical responses expected from the application of thermal stimuli of several degrees to insulating liquids are calculated, considering the diffuse layer present at the interface with the walls. The influence of different parameters of the electrical double layer on the simulated signals is studied. In particular, the effects of thermo-convection are quantified and criteria to identify them in the electrical responses are established.Experimental results, obtained with a measuring installation designed and built specifically for liquids, prove that the responses resulting from the application of low-amplitude thermal steps to insulating liquids are well measurable. Their detailed analysis leads to the conclusion that these responses are indeed due to charges from the electrical double layer. The probable contribution to the measured signals not only of the diffuse layer, but also of the compact layer, is highlighted. The results allow to conclude that thermal stimuli methods are applicable to dielectric liquids. Their further development should lead to experimental implementations with resolutions and sensitivities adapted to the study of electric charges and fields at the interfaces and in the volume of these materials.; Les charges électriques présentes naturellement aux interfaces liquide/solide ou qui se développent dans les liquides de façon contrôlée ou non-désirée sont sources, d’une part, de nombreuses applications (micro-pompages, laboratoires sur puce, super-condensateurs…), et d’autre part de risques industriels (inflammations, explosions…). Ceci nécessite une quantification aussi précise que possible des valeurs et des répartitions de ces charges dans les milieux diélectriques liquides. Les techniques de mesure actuelles sont soit non-résolutives, les réponses mesurées sur l’ensemble de l’éprouvette permettant de déduire des informations sur les charges et les processus associés de manière indirecte (au travers de modèles), soit limitées en termes de sensibilité et/ou de résolution. Par exemple, le modèle de la double couche électrique, proposé par Stern en 1924 et complètement accepté par la communauté scientifique depuis, n’a encore jamais été confirmé expérimentalement, notamment en raison du manque de résolution et de sensibilité des méthodes existantes.Plusieurs techniques ont été développées depuis 1980 pour mesurer de façon directe et non-destructive les charges électriques dans les isolants solides. Parmi ces méthodes, celles basées sur l’application de stimuli thermiques de faible amplitude ont montré les meilleures sensibilités et les meilleures performances pour la mesure des charges près des interfaces. L’application de ces techniques aux liquides est une voie de recherche à explorer afin de répondre aux questionnements scientifiques et applicatifs évoqués. Ce travail étudie, aussi bien du point de vue théorique qu’expérimental, l’application du principe de l’onde thermique à la mesure de charges électriques dans les liquides isolants. La double couche électrique, qui s’établit au niveau des parois liquide/solide, est utilisée comme objet d’étude. Plusieurs liquides diélectriques sont concernés : cyclohexane à l’état liquide et solide, huile minérale pure et additivée et huile silicone.À travers des simulations numériques, les réponses électriques susceptibles d’être issus de l’application de stimuli thermiques de quelques degrés à des liquides isolants sont calculées, en considérant la couche diffuse présente à l’interface avec les parois. L’influence de différents paramètres de la double couche électrique sur les signaux simulés est étudiée. Les effets de la thermo-convection sont quantifiés en particulier et des critères permettant de les identifier dans les réponses électriques sont établis.Des résultats expérimentaux, obtenus avec une installation de mesure conçue et réalisée spécialement pour les liquides, montrent que les réponses issues de l’application d’onde thermique de faibles amplitudes à des liquides isolants sont bien mesurables. Leur analyse détaillée permet de conclure que ces réponses proviennent bien des charges de la double couche électrique. La contribution probable aux signaux mesurés non seulement de la couche diffuse, mais également de la couche compacte, est mise en évidence. Les résultats permettent de conclure que les méthodes à stimuli thermique sont applicables aux liquides diélectriques. La poursuite de leur développement devrait aboutir à des mises en œuvres expérimentales avec des résolutions et des sensibilités adaptées à l’étude des charges et des champs électriques aux interfaces et dans le volume de ces matériaux.

International audience; Obtaining diagnostic specimens, notably to monitor disease course in cancer patients undergoing therapy, is an emerging area of research, however, with few clinical implications so far in the field of Neuro-oncology. Specifically for patients with primary brain tumors where repeat biosampling from the tumor and clinical decision making based on neuroimaging alone remain challenging, this area may assume a central role. In principle, sampling could focus on blood, cerebrospinal fluid or urine with differential sensitivities and specificities of findings that differ between specific parameters and target molecules. These include protein, mRNA, miRNA, cell-free DNA, either freely circulating or as cargo of extracellular vesicles, as well circulating tumor cells. The most solid biomarkers are those directly reflecting neoplastic disease, e.g., in the case of primary brain tumors isocitrate dehydrogenase mutation or epidermal growth factor receptor variant III. Importantly, the main goals of liquid biopsy marker development are to better understand response to therapy, natural evolution and emergence of resistant clones, rather than obviating the need for surgical interventions which remain to be a mainstay of therapy for the vast majority of primary brain tumors.

International audience; A process in three steps involving a gas-liquid contactor with an organic phase, a TPPB and a liquid/liquid separator to recover the organic phase for its recycling was proposed to treat hydrophobic Volatile Organic Compounds. Among the processes tested for liquid/liquid separation (settling, hydrocyclone and centrifugation), the latter appeared to be the most efficient. The centrifugal acceleration needed for the separation of oil and water was found to be dependent on the viscosity of the oil used and the presence of microorganisms. The force required for phases' separation was found to be reduced in the presence of selected commercial demulsifiers.

International audience; This paper studies the breakdown voltage for different insulating materials encapsulating power electronic devices. A comparison between some liquids and silicone gel is carried out. The 50 Hz AC voltage tests were performed according to the IEC 60156 specifications. The same process was applied to the DC voltage tests due to a lack of standard procedure concerning DC voltage tests on liquids. In each case, a ceramic substrate was placed in a container filled with the insulating material. A voltage was applied between two electrodes glued on the substrate. Mineral, both synthetic and natural ester oils and silicone gel were tested. The voltages of breakdown between oils were quite similar in AC and DC. The gel is more resistant to DC stress even though its self-healing is less than the liquids investigated.

International audience; Marine mollusk aquaculture has more than doubled over the past twenty years, accounting for over 15% of total aquaculture production in 2016. Infectious disease is one of the main limiting factors to the development of mollusk aquaculture, and the difficulties inherent to combating pathogens through antibiotic therapies or disinfection have led to extensive research on host defense mechanisms and host-pathogen relationships. It has become increasingly clear that characterizing the functional profiles of response to a disease is an essential step in understanding resistance mechanisms and moving towards more effective disease control. The Manila clam, Ruditapes philippinarum, is a main cultured bivalve species of economic importance which is affected by Brown Ring disease (BRD), an infection induced by the bacterium Vibrio tapetis. In this study, juvenile Manila clams were subjected to a 28-day controlled challenge with Vibrio tapetis, and visual and molecular diagnoses were carried out to distinguish two extreme phenotypes within the experimental clams: uninfected ("RES", resistant) and infected ("DIS", diseased) post-challenge. Total protein extractions were carried out for resistant and diseased clams, and proteins were identified using LC-MS/MS. Protein sequences were matched against a reference transcriptome of the Manila clam, and protein intensities based on label-free quantification were compared to reveal 49 significantly accumulated proteins in resistant and diseased clams. Proteins with known roles in pathogen recognition, lysosome trafficking, and various aspects of the energy metabolism were more abundant in diseased clams, whereas those with roles in redox homeostasis and protein recycling were more abundant in resistant clams. Overall, the comparison of the proteomic profiles of resistant and diseased clams after a month-long controlled challenge to induce the onset of Brown Ring disease suggests that redox homeostasis and maintenance of protein structure by chaperone proteins may play important and interrelated roles in resistance to infection by Vibrio tapetis in the Manila clam.

The contact between a cylindrical flat indenter and a liquid is considered. The behavior is totally controlled by the supposed constant surface tension. An analytical approach and a numerical solution are developed to describe the shape of the surface as a function of the applied force and to calculate the pressure induced in the liquid. This article follows an article, in English (Fond, 2018b) and French (Fond, 2018a), concerning a medium for which only surface tension would act, the effects of the elastic response of the massif being negligible, i.e. a very flexible and highly compressible medium. In order to validate finite element calculations in finite media concerning the indentation of flexible material in the presence of surface tension in the case where the mechanical behaviour of the solid approaches a compressible liquid 1 , it is necessary to know the solution for a liquid in the context of a finite medium. 1 extremely flexible medium in shear and relatively stiff in compressibility; Le contact entre un indenteur plat cylindrique et un liquide est considéré. Le comportement est totalement contrôlé par la tension de surface supposée constante. Une approche analytique et une solution numérique sont développées pour décrire la forme de la surface en fonction de la force appliquée et calculer la pression induite dans le liquide.

International audience; Tilted image series are acquired on liquid suspensions of latex particles supported by a carbon membrane. To do so, a home-made stage fitting in an Environmental Scanning Electron Microscope (ESEM) is optimized in order to minimize cold losses and therefore improve both sample stability and spatial resolution in the images. As latex particles are electron-sensitive materials, sample degradation and stability are taken into account in the choice of the parameters for tilted image series acquisition. Despite the limited number of images, conventional algorithms are used to reconstruct the volume and study the three-dimensional arrangement of latex particles. The lattice types are in good agreement with what can be observed on frozen suspensions, although the domain sizes are smaller. Several quantitative parameters such as the latex particle size and the distance to the first neighbors are extracted from the 3D model. Finally, the spatial resolution in the tomograms is estimated using the Crowther's criterion and Fourier Shell Correlation analysis. It is also measured directly by analyzing a suspension containing latex particles and a surfactant of interest for composite formulation.

International audience; We review field theory studies devoted to understanding electron–electron interaction effects in condensed matter systems such as planar Dirac liquids, for example, graphene and graphene-like systems, surface states of some topological insulators, and possibly half-filled fractional quantum Hall systems. These liquids are characterized by gapless bands, strong electron–electron interactions, and emergent Lorentz invariance deep in the infrared. We address several important issues raised by experiments on these systems covering subjects of wide current interest in low-energy (condensed matter) and also high-energy (particle) physics. In particular, we consider the subtle influence of interactions on transport properties and their supposedly crucial influence on a potential dynamical mass generation. The resolution of these problems guide us from a thorough examination of the perturbative structure of gauge field theories to the development and application of nonperturbative approaches known from quantum electro/chromo-dynamics to address strong coupling issues.

The large-scale use of quaternary ammonium compounds (QACs) in medicines or disinfectants can lead to their release into the environment, posing a potential risk to organisms. This study examined the effects of three typical QACs, dodecyltrimethylammonium chloride (DTAC), dodecyldimethylbenzylammonium chloride (DBAC), and didodecyldimethylammonium chloride (DDAC), on hydroponically cultured wheat seedlings. After 14 days of exposure, both hormesis and phytotoxicity were observed in the wheat seedlings. The shoot and root fresh weight gradually increased as QAC concentrations rose from 0.05 to 0.8 mg L-1. However, higher QAC concentrations severely inhibited plant growth by decreasing shoot and root fresh weight, total root length, and photosynthetic pigment content. Moreover, the increase in malondialdehyde and O-2(.-) contents, as well as root membrane permeability, reflected an oxidative burst and membrane lipid peroxidation caused by QACs. However, the effects of QACs on the levels of these oxidative stress markers were compound-specific, and the changes in superoxide dismutase, peroxidases, and catalase activity were partly related to reactive oxygen species levels. Considering the order of median effective concentration values (EC50) and the levels of oxidative stress induced by the three tested QACs, their phytotoxicities in wheat seedlings increased in the following order: DDAC < DTAC < DBAC, which mainly depended on their characteristics and applied concentrations. These results, which illustrated the complexity of QAC toxicity to plants, could potentially be used to assess the risk posed by these compounds in the environment.

The failed "vortex-atoms" theory of matter by Kelvin and Tait had a profound impact on mathematics and physics. Building on the understanding of vorticity by Helmholtz, and observing stability of smoke rings, they hypothesised that elementary particles (at that time atoms) are indestructible knotted vortices in luminiferous aether: the hypothetical ideal fluid filling the universe. The vortex-atoms theory identified chemical elements as topologically different vortex knots, and matter was interpreted as bound states of these knotted vortices. This work initiated the field of knot theory in mathematics. It also influenced modern physics, where a close although incomplete analogy exists with the theory of superfluidity, which started with Onsager's and Feynman's introduction of quantum vortices. Indeed many macroscopic properties of superconductors and superfluids are indeed determined by vortex lines forming different "aggregate states", such as vortex crystals and liquids. While crucial importance of knots was understood for many physical systems in the recent years, there is no known physical realization of the central element of Kelvin theory: the stable particle-like vortex knot. Indeed, vortex loops and knots in superfluids and ordinary superconductors form as dynamical excitations and are unstable by Derrick theorem. This instability in fact dictates many of the universal macroscopic properties of superfluids. Here we show that there are superconducting states with principally different properties of the vorticity: where vortex knots are intrinsically stable. We demonstrate that such features should be realised near certain critical points, where the hydro-magneto-statics of superconducting states yields stables vortex knots which behave similar to those envisaged in Kelvin and Tait's theory of vortex-atoms in luminiferous aether.

The field theoretic renormalization study of reduced quantum electrodynamics (QED) is performed up to two loops. In the condensed matter context, reduced QED constitutes a very natural effective relativistic field theory describing (planar) Dirac liquids, e.g., graphene and graphene-like materials, the surface states of some topological insulators and possibly half-filled fractional quantum Hall systems. From the field theory point of view, the model involves an effective (reduced) gauge field propagating with a fractional power of the d'Alembertian in marked contrast with usual QEDs. The use of the BPHZ prescription allows for a simple and clear understanding of the structure of the model. In particular, in relation with the ultra-relativistic limit of graphene, we straightforwardly recover the results for both the interaction correction to the optical conductivity: $\mathcal{C}^*=(92-9\pi^2)/(18\pi)$ and the anomalous dimension of the fermion field: $\gamma_{\psi}(\bar{\alpha},\xi) = 2 \bar{\alpha}\,(1-3\xi)/3 -16\,\left( \zeta_2 N_F + 4/27 \right)\, \bar{\alpha}^2 + O(\bar{\alpha}^3)$, where $\bar{\alpha} = e^2/(4\pi)^2$ and $\xi$ is the gauge-fixing parameter., Comment: (v2) Published in PRD. Some references added. No change in results. (v1) LaTeX file with feynMF package. 15 pages, 4 figures

Modelling of processes involving deep Earth liquids requires information on their structures and compression mechanisms. However, knowledge of the local structures of silicates and silica (SiO2) melts at deep mantle conditions and of their densification mechanisms is still limited. Here we report the synthesis and characterization of metastable high-pressure silica phases, coesite-IV and coesite-V, using in situ single-crystal X-ray diffraction and ab initio simulations. Their crystal structures are drastically different from any previously considered models, but explain well features of pair-distribution functions of highly densified silica glass and molten basalt at high pressure. Built of four, five-, and six-coordinated silicon, coesite-IV and coesite-V contain SiO6 octahedra, which, at odds with 3rd Pauling’s rule, are connected through common faces. Our results suggest that possible silicate liquids in Earth’s lower mantle may have complex structures making them more compressible than previously supposed., As silica melts are believed to be important components of the Earth’s mantle, their structure should determine many of its properties. Here, the authors identify two crystalline modifications of SiO2, whose local structures closely resemble those of known melts, providing a structural model for their atomic ordering at the nanoscale.

The study of electrical arcs in liquids begins in XXth century with the first oil circuit breaker and the use of welding/cutting processes on ship hulls in full water. These studies have been neglected for about 60 years, until the emergence of new applications such as the manufacture of nanostructures (for electrical engineering, medicine, etc.), electrical arc fracturing or different environmental applications (depollution, sterilization, gasification). In these applications different times and energies scales are involved for the discharge characteristics. Despite these differences, in all configurations a spherical gaseous medium dues to the current carrying path in the liquid exists. However, this gaseous phase is not much studied in the literature, particularly for an energy discharges of the order of kilojoule applied during 10ms. The goal of the thesis was to improve the understanding and to interpret the formation and the dynamic of the gas bubble created by this arc by varying the conditions. The work follows two ways: an experimental study to analyze the behavior of the bubble depending on the arc characteristics as the energy injected, the distance between the electrodes or the nature of the fluid; And a numerical study, where a 2D diphasic model has been implemented under Ansys Fluent to simulate the creation and the expansion of this gaseous phase in a liquid. The complementarity of these two approaches allows complementarities and interpretations. The experiment set up is composed by a closed aluminum reactor, where the electric arc is established in a liquid (water or oil) by a fusible wire between two electrodes. Windows allows to visualize by a speed camera the inter-electrode space, and so the arc and the gas bubble created. The current and voltage characteristics of the electric arc are recorded over time. A pressure sensor located in the volume of air above the liquid controls the pressure variations. The experimental results are treated through Matlab software and allow corroborating the numerical model developments. The code uses the Navier-Stokes equations to describe the two phases of the fluid via the Volume-Of-Fluids (VOF) method. Specifics developments have also been integrated to take into account the phase transfer at the gas/liquid interface adapting the mass transfer intensity coefficient. This coefficient is described as a function of the temperature and of the proportion of phase in a cell. The simulation results from the model support the experimental observations and build the foundations for a study on the behavior of the gaseous phase produced by the passage of an electric arc in a liquid.; L'étude des arcs électriques dans les liquides débute au XXème siècle suite à la création des premiers disjoncteurs à bain d'huile et à l'utilisation de différents procédés de soudure/découpe en pleine eau de coques de navire. Ces études ont été délaissées pendant environ 60 ans jusqu'à ce que de nouvelles applications voient le jour comme la fabrication de nanostructures (pour le génie électrique, la médecine, etc), la fracturation électrique ou encore diverses applications environnementales (dépollution, stérilisation, gazéification, ondes de chocs). Ces diverses applications se font avec des temps et des énergies mises en jeu pour la décharge très variables. Malgré ces différences, il y a toujours l'apparition d'une phase gazeuse globalement sphérique due au passage du courant. Cependant, cette phase est très peu étudiée dans la littérature notamment pour des décharges de l'ordre du kilojoule pour des durées de 10ms environ. L'objectif de la thèse est donc d'améliorer la compréhension de la formation et de la dynamique de la bulle de gaz alimentée par cet arc en jouant sur certains paramètres du système. Les travaux effectués s'articulent suivant deux axes : une étude expérimentale pour analyser le comportement de cette bulle par rapport à l'arc en modifiant notamment l'énergie injectée, la distance inter-électrode utilisée ou encore la nature du fluide employé ; et une étude numérique où un modèle diphasique 2D a été mis en œuvre sous Ansys Fluent pour simuler la création et le développement de cette phase gazeuse au sein d'une phase liquide. La complémentarité de ces deux études permet de témoigner de la présence de certains mécanismes comme ceux de la formation de bulles ou de cycles d'expansion et d'effondrement, gouvernés par des phénomènes de chauffage, d'évaporation ou électrothermiques. L'expérience mise en place se compose d'un réacteur hermétique en aluminium où l'arc électrique est amorcé par un fil fusible entre deux électrodes dans un liquide : eau ou huile. Des hublots permettent la visualisation par caméra rapide de l'espace inter électrode, et donc de l'arc et de la bulle de gaz qu'il engendre. Les caractéristiques courant et tension de l'arc électrique sont suivies dans le temps. Un capteur de pression dans le volume d'air situé au-dessus du liquide contrôle l'onde de pression générée par la décharge. Les résultats expérimentaux sont traités sous Matlab et permettent de conforter le modèle numérique mis en place. Le code utilise les équations de Navier-Stokes pour décrire les deux phases du fluide via la méthode Volume-Of-Fluids (VOF). A ces développements a aussi été intégré un modèle pour prendre en compte le transfert d'une phase de fluide vers une autre. Pour nos conditions de températures élevées, ce modèle a dû être adapté via le coefficient d'intensité de transfert de masse, qui est décrit en fonction de la température et de la proportion de phase dans une cellule. Les résultats de simulation issus de ce modèle permettent d'appuyer les observations expérimentales, et de poser les bases d'une étude sur la formation et le comportement de la phase gazeuse produite par le passage d'un arc électrique dans un liquide.

The study of electrical arcs in liquids begins in XXth century with the first oil circuit breaker and the use of welding/cutting processes on ship hulls in full water. These studies have been neglected for about 60 years, until the emergence of new applications such as the manufacture of nanostructures (for electrical engineering, medicine, etc.), electrical arc fracturing or different environmental applications (depollution, sterilization, gasification). In these applications different times and energies scales are involved for the discharge characteristics. Despite these differences, in all configurations a spherical gaseous medium dues to the current carrying path in the liquid exists. However, this gaseous phase is not much studied in the literature, particularly for an energy discharges of the order of kilojoule applied during 10ms. The goal of the thesis was to improve the understanding and to interpret the formation and the dynamic of the gas bubble created by this arc by varying the conditions. The work follows two ways: an experimental study to analyze the behavior of the bubble depending on the arc characteristics as the energy injected, the distance between the electrodes or the nature of the fluid; And a numerical study, where a 2D diphasic model has been implemented under Ansys Fluent to simulate the creation and the expansion of this gaseous phase in a liquid. The complementarity of these two approaches allows complementarities and interpretations. The experiment set up is composed by a closed aluminum reactor, where the electric arc is established in a liquid (water or oil) by a fusible wire between two electrodes. Windows allows to visualize by a speed camera the inter-electrode space, and so the arc and the gas bubble created. The current and voltage characteristics of the electric arc are recorded over time. A pressure sensor located in the volume of air above the liquid controls the pressure variations. The experimental results are treated through Matlab software and allow corroborating the numerical model developments. The code uses the Navier-Stokes equations to describe the two phases of the fluid via the Volume-Of-Fluids (VOF) method. Specifics developments have also been integrated to take into account the phase transfer at the gas/liquid interface adapting the mass transfer intensity coefficient. This coefficient is described as a function of the temperature and of the proportion of phase in a cell. The simulation results from the model support the experimental observations and build the foundations for a study on the behavior of the gaseous phase produced by the passage of an electric arc in a liquid.; L'étude des arcs électriques dans les liquides débute au XXème siècle suite à la création des premiers disjoncteurs à bain d'huile et à l'utilisation de différents procédés de soudure/découpe en pleine eau de coques de navire. Ces études ont été délaissées pendant environ 60 ans jusqu'à ce que de nouvelles applications voient le jour comme la fabrication de nanostructures (pour le génie électrique, la médecine, etc), la fracturation électrique ou encore diverses applications environnementales (dépollution, stérilisation, gazéification, ondes de chocs). Ces diverses applications se font avec des temps et des énergies mises en jeu pour la décharge très variables. Malgré ces différences, il y a toujours l'apparition d'une phase gazeuse globalement sphérique due au passage du courant. Cependant, cette phase est très peu étudiée dans la littérature notamment pour des décharges de l'ordre du kilojoule pour des durées de 10ms environ. L'objectif de la thèse est donc d'améliorer la compréhension de la formation et de la dynamique de la bulle de gaz alimentée par cet arc en jouant sur certains paramètres du système. Les travaux effectués s'articulent suivant deux axes : une étude expérimentale pour analyser le comportement de cette bulle par rapport à l'arc en modifiant notamment l'énergie injectée, la distance inter-électrode utilisée ou encore la nature du fluide employé ; et une étude numérique où un modèle diphasique 2D a été mis en œuvre sous Ansys Fluent pour simuler la création et le développement de cette phase gazeuse au sein d'une phase liquide. La complémentarité de ces deux études permet de témoigner de la présence de certains mécanismes comme ceux de la formation de bulles ou de cycles d'expansion et d'effondrement, gouvernés par des phénomènes de chauffage, d'évaporation ou électrothermiques. L'expérience mise en place se compose d'un réacteur hermétique en aluminium où l'arc électrique est amorcé par un fil fusible entre deux électrodes dans un liquide : eau ou huile. Des hublots permettent la visualisation par caméra rapide de l'espace inter électrode, et donc de l'arc et de la bulle de gaz qu'il engendre. Les caractéristiques courant et tension de l'arc électrique sont suivies dans le temps. Un capteur de pression dans le volume d'air situé au-dessus du liquide contrôle l'onde de pression générée par la décharge. Les résultats expérimentaux sont traités sous Matlab et permettent de conforter le modèle numérique mis en place. Le code utilise les équations de Navier-Stokes pour décrire les deux phases du fluide via la méthode Volume-Of-Fluids (VOF). A ces développements a aussi été intégré un modèle pour prendre en compte le transfert d'une phase de fluide vers une autre. Pour nos conditions de températures élevées, ce modèle a dû être adapté via le coefficient d'intensité de transfert de masse, qui est décrit en fonction de la température et de la proportion de phase dans une cellule. Les résultats de simulation issus de ce modèle permettent d'appuyer les observations expérimentales, et de poser les bases d'une étude sur la formation et le comportement de la phase gazeuse produite par le passage d'un arc électrique dans un liquide.

International audience; Here is reported a dedicated and reliable experimental setup which has been designed to study the corrosive effects of liquid uranium hexafluoride (UF6) on pure metallic iron at 80°C and 3 bars of pressure. Three corrosion tests have been carried out, ranging from several hundred to almost one thousand hours. No uniform corrosion was observed on early-stage samples. However, a nodule facies consisting in FeF2 and UFx (with 4

ALTO is a concept/project in the exploratory phase since 2013 aiming to build a wide-field VHE gamma-ray observatory at very high altitude in the Southern hemisphere. The operation of such an observatory will complement the Northern hemisphere observations performed by HAWC and will make possible the exploration of the central region of our Galaxy and the hunt for PeVatrons, and to search for extended Galactic objects such as the Vela Supernova Remnant and the Fermi bubbles. The ALTO project is aiming for a substantial improvement of the Water Cherenkov Detection Technique by increasing the altitude of the observatory in order to lower the energy threshold, by using a layer of scintillator below the water tank to optimize the S/B discrimination, by minimizing the size of the tanks and having a more compact array to sample the air-shower footprints with better precision, and by using precise electronics which will provide time-stamped waveforms to improve the angular and energy resolution. ALTO is designed to have as low an energy threshold as possible so as to act as a fast trigger alert to other observatories, primarily to the Southern part of CTA, for transient Galactic and extra-galactic phenomena. The wide FoV resulting from the detection technique allows the survey of a large portion of the sky continuously, thus giving the possibility to access emission from Gamma-Ray Bursts, Active Galactic Nuclei and X-ray binary flares, and extended emissions of both Galactic (Vela SNR, Fermi bubbles) and extra-galactic (AGN radio lobes) origin. The ALTO observatory will be composed of about a thousand detection units, each of which consists of a Water Cherenkov Detector positioned above a liquid Scintillation Detector, distributed within an area of about 200 m in diameter. The project is in the design study phase which is soon to be followed by a prototyping phase., 7 pages, 2 figures, Proceedings of the 35th International Cosmic Ray Conference (ICRC2017), Busan (South Korea)

International audience; We present a method to characterize optical properties of liquids by spectroscopic ellipsometry. The experiments use a specific liquid cell that avoids disturbance of waves at air-liquid interface and allows the determination of the real and the imaginary part of the refractive index, with a sensitivity of the latter below 10−4. The method is illustrated by results obtained with a spectroscopic phase modulation ellipsometer on several liquids such as deionised water, microscope oil and protein solution. Comparisons of the method with standard techniques are given.

Semi-holographic models of non-Fermi liquids have been shown to have generically stable generalised quasi-particles on the Fermi surface. Although these excitations are broad and exhibit particle-hole asymmetry, they were argued to be stable from interactions at the Fermi surface. In this work, we use this observation to compute the density response and collective behaviour in these systems. Compared to the Fermi liquid case, we find that the boundaries of the particle-hole continuum are blurred by incoherent contributions. However, there is a region inside this continuum, that we call inner core, within which salient features of the Fermi liquid case are preserved. A particularly striking prediction of our work is that these systems support a plasmonic collective excitation which is well-defined at large momenta, has an approximately linear dispersion relation and is located in the low-energy tail of the particle-hole continuum. Furthermore, the dynamic screening potential shows deep attractive regions as a function of the distance at higher frequencies which might lead to long-lived pair formation depending on the behaviour of the pair susceptibility. We also find that Friedel oscillations are present in these systems but are highly suppressed., 45 pages; 24 figures; published version

International audience; Pyrochemical technology using high-temperature molten salts and molten metal media presents a potential interest for an overall separation and transmutation strategy for long-lived radionuclides. A pyroprocess was developed at the CEA Marcoule, based on a two- step liquid-liquid extraction. This process aims to demonstrate the feasibility of a group separation of actinides with sufficient decontamination from fission products.Taking advantage of chemical properties of cryolite fluoride salts, the first step consists in a selective reductive extraction of actinides coming from direct dissolution of oxide fuel in the molten fluoride salt, into liquid aluminium metal. The second step is the actinides back-extraction, which consists in a liquid/liquid oxidative stripping of the An from aluminium matrix into molten chloride media. The DOS process has been successfully demonstrated for treatment of oxide type fuels within the last years the core of the process has been already assessed and the studies have shown high selectivity and a quantitative recovery of actinides.Within the framework of the SACSESS European research program, the pyrochemical activities focused on applications of this process for treatment of CERCER and CERMET transmutation targets. These particular type of fuels consist of a mixture of minor actinides (MA) oxides diluted in an inert matrices (MgO) for CERCER and metallic Mo for CERMET. In the present work the behaviour of matrices material was first investigated regarding the solubility in the fluoride salt, starting from both oxide powders (considering a prior oxidation step Mo into oxide form for reprocessing of CERMET) or sintered pellets. Further investigations focused on the reductive extraction behaviour of Mg or Mo in metallic Al. The impact of Mg and Mo on the efficiency of An reductive extraction was also studied using uranium simulating the behaviour of MA oxides.

International audience; Dedicated and reliable experimental setup had been designed and experiments had been carried out in order to perform corrosion experiments on pure iron in liquid uranium hexafluoride (UF$_6$) at 80°C and 3 bars. Three corrosion tests have been carried out from several hundred to almost a thousand hours. No uniform corrosion has been observed for early stages samples with nodule-facies consisting in FeF$_2$ and UF$_x$ (with 4

In this experimental–theoretical investigation, we consider a turbulent plume generated by an isothermal wall in a closed cavity and the formation of heat stratification in the interior. The buoyancy of the plume near the wall and the temperature stratification are measured across a vertical plane with the temperature laser induced fluorescence method, which is shown to be accurate and efficient (precision of $0.2\,^{\circ }$C) for experimental studies on convection. The simultaneous measurement of the velocity field with particle image velocimetry allows for the calculation of the flow characteristics such as the Richardson number and Reynolds stress. This enables us to give a refined description of the wall plume, as well as the circulation and evolution of the stratification in the interior. The wall plume is found to have an inner layer close to the heated boundary with a laminar transport of hardly mixed fluid which causes a relatively warm top layer and an outer layer with a transition from laminar to turbulent at a considerable height. The measured entrainment coefficient is found to be dramatically influenced by the increase in stratification of the ambient fluid. To model the flow, the entrainment model of Morton, Taylor & Turner (Proc. R. Soc. Lond. A, vol. 234 (1196), 1956, pp. 1–23) has first been adapted to the case of an isothermal wall. Differences due to their boundary condition of a constant buoyancy flux, modelled with salt by Cooper & Hunt (J. Fluid Mech., vol. 646, 2010, pp. 39–58), turn out to be small. Next, to include the laminar–turbulent transition of the boundary layer, a hybrid model is constructed which is based on the similarity solutions reported by Worster & Leitch (J. Fluid Mech., vol. 156, 1985, pp. 301–319) for the laminar part and the entrainment model for the turbulent part. Finally, the observed variation of the global entrainment coefficient, which is due to the increased presence of an upper stratified layer with a relatively low entrainment coefficient, is incorporated into both models. All models show reasonable agreement with experimental measurements for the volume, momentum and buoyancy fluxes as well as for the evolution of the stratification in the interior. In particular, the introduction of the variable entrainment coefficient improves all models significantly.

International audience; A hydrodynamic theory of transport in quantum mechanically phase-disordered superconductors is possible when supercurrent relaxation can be treated as a slow process. We obtain general results for the frequency-dependent conductivity of such a regime. With time-reversal invariance, the conductivity is characterized by a Drude-type peak, with width given by the supercurrent relaxation rate. Using the memory matrix formalism, we obtain a formula for this width (and hence also the dc resistivity) when the supercurrent is relaxed by short-range density-density interactions. This leads to an effective field theoretic and fully quantum derivation of a classic result on flux flow resistance. With strong breaking of time-reversal invariance, the optical conductivity exhibits what we call a “hydrodynamic supercyclotron” resonance. We obtain the frequency and decay rate of this resonance for the case of supercurrent relaxation due to an emergent Chern-Simons gauge field. The supercurrent decay rate in this “topologically ordered superfluid vortex liquid” is determined by the conductivities of the normal fluid component, rather than the vortex core.

A detailed study of vortices is presented in Ginzburg-Landau (or Abelian Higgs) models with two complex scalars (order parameters) assuming a general U(1)$\times$U(1) symmetric potential. Particular emphasis is given to the case, when only one of the scalars obtains a vacuum expectation value (VEV). It is found that for a significantly large domain in parameter space vortices with a scalar field condensate in their core (condensate core, CC) coexist with Abrikosov-Nielsen-Olesen (ANO) vortices. Importantly CC vortices are stable and have lower energy than the ANO ones. Magnetic bags or giant vortices of the order of 1000 flux quanta are favoured to form for the range of parameters ("strong couplings") appearing for the superconducting state of liquid metallic hydrogen (LMH). Furthermore, it is argued that finite energy/unit length 1VEV vortices are smoothly connected to fractional flux 2VEV ones. Stable, finite energy CC-type vortices are also exhibited in the case when one of the scalar fields is neutral., Comment: 34 pages, 11 figures

A hydrodynamic theory of transport in quantum mechanically phase-disordered superconductors is possible when supercurrent relaxation can be treated as a slow process. We obtain general results for the frequency-dependent conductivity of such a regime. With time-reversal invariance, the conductivity is characterized by a Drude-like peak, with width given by the supercurrent relaxation rate. Using the memory matrix formalism, we obtain a formula for this width (and hence also the dc resistivity) when the supercurrent is relaxed by short range Coulomb interactions. This leads to a new -- effective field theoretic and fully quantum -- derivation of a classic result on flux flow resistance. With strong breaking of time-reversal invariance, the optical conductivity exhibits what we call a `hydrodynamic supercyclotron' resonance. We obtain the frequency and decay rate of this resonance for the case of supercurrent relaxation due to an emergent Chern-Simons gauge field. The supercurrent decay rate in this `topologically ordered superfluid vortex liquid' is determined by the conductivities of the normal component of the liquid. Our work gives a controlled framework for low temperature metallic phases arising from phase-disordered superconductivity., 1 + 44 pages. 2 figures. v2 discussion improved in places. v3 sign errors fixed in section 4

International audience; Pyrochemical technology using high-temperature molten salts and molten metal media presents a potential interest for an overall separation and transmutation strategy for long-lived radionuclides. Within the frame of the two French acts on radioactive waste management, a pyrochemical RandD program was launched at the CEA Marcoule in the late 90's. The developed so called DOS (Direct Oxide Solubilisation) process, based on a two- step liquid-liquid (molten salt/liquid metal) extraction, aims to demonstrate the feasibility of a group separation of actinides with sufficient decontamination from fission products.The first step consists of a selective reductive extraction of actinides coming from direct dissolution of oxide fuel in the molten fluoride salt, into liquid aluminium metal. The second step is the actinides back-extraction, which consists of a liquid/liquid oxidative stripping of the An from aluminium matrix into molten chloride media. The DOS process has been successfully demonstrated for treatment of oxide type fuels within the last years the core of the process has been already assessed and the studies have shown high selectivity and a quantitative recovery of actinides. Within the framework of the SACSESS European research program, the present work focuses on a potential application of the DOS process for the reprocessing of MgO based CERCER transmutation targets. The behaviour of Mg was investigated regarding the solubility of MgO in the fluoride salt and then regarding Mg reductive extraction in metallic Al. The impact of Mg on the efficiency of An reductive extraction was also studied using U3O8 simulating the behaviour of MA oxides. Eventually, the validity of the DOS process was demonstrated on a Pu0.5Am0.5O2-et61540;-MgO FUTURIX CERCER pellet synthesized at the ATALANTE facility within the framework of Eurotrans program. Substantial amount of Nd2O3 was added during the demonstration experiment in order to simulate fission products behaviour. Quantitative recovery of purified Pu and Am was achieved in a single batch experiment.

International audience; Santorini volcano in the Aegean region (Greece) is characterized by andesitic- to silicic-dominated explosive activity and caldera-forming eruptions, sourced from magmatic reservoirs located at various structural levels beneath the volcano. There is a good understanding of the silica-rich magmatism of the island whereas the andesite-dominated volcanism and the petrogenesis of the parental mafic magmas are still poorly understood. To fill this gap we have performed crystallization experiments on a representative basalt from Santorini with the aim of determining the conditions of differentiation (pressure, temperature, volatile fugacities) and the parental magma relationship with the andesitic eruptive rocks. Experiments were carried out between 975 and 1040°C, in the pressure range 100–400 MPa, fO2 from QFM to NNO + 3·5 (where QFM is quartz–fayalite–magnetite and NNO is nickel–nickel oxide), with H2Omelt contents varying from saturation to nominally dry conditions. The results show that basalt phenocrysts within the basalt crystallized at around 1040°C in a magma storage reservoir located at a depth equivalent to 200–400 MPa pressure, with 3–5 wt % dissolved H2O, and fO2 around QFM. Comparison with the xenocryst and phenocryst assemblages of the Upper Scoria 1 andesite shows that andesitic liquids are produced by fractionation of a similar basalt at 1000°C and 400 MPa, following 60–80 wt % crystallization of an ol + cpx + plag + Ti-mag + opx ± pig–ilm assemblage, with melt water contents around 4–6 wt %. At Santorini, the andesitic low-viscosity and water-rich residual liquids produced at these depths segregate from the parent basaltic mush and feed the shallow magma reservoirs, eventually erupting upon mixing with resident magma. Changes in prevailing oxygen fugacity may control the tholeiitic–calc-alkaline character of Santorini magmas, explaining the compositional and mineralogical differences observed between the recent Thyra and old eruptive products from Akrotiri.

International audience; Nuclear fuel cycle operation, production and application of radioisotope in biological investigation, industry,research.are as much sources of liquid radioactive waste. Some of them are currently treated to immobilize theirradionuclides before final repository when others are waiting for suitable processes.For several years, the CEA has worked to adapt plasma technology to liquid treatment. Among the followed technologicaltracks, two have been considered as promising because rapid and very effective. The first, involving aerial inducted plasmatorch, ensures the treatment by feeding the liquid in the hearth of the inductive coil, directly into the plasma plume. Thesecond, involving submerged non transferred plasma torch into which the liquid is also fed, has the particularity to useunderwater plasma in order to avoid corrosion and to extend the range of waste that can be treated.The aim of this paper is to provide a description and the performances of these two processes displaying large potentialitiesthrough their originality. Several radwastes could find their outlet thanks to these two new routes.

International audience; The authors aimed at developing a liquid chromatography tandem mass spectrometry (LC-MS/MS) method with online extraction to determine (R)- and (S)- methadone enantiomers and its main metabolite 2-ethylidine-1,5-dimethyl-3,3 diphenylpyrrolidine (EDDP) in plasma. The analysis combined straightforward sample preparation, consisting of protein precipitation with acetonitrile, and an online enrichment by a flush/back-flush cycle before the second dimension chromatography. Using D3-deuterated internal standards allows overcoming significant relative matrix effect. Our method was linear up to 2000 ng/mL. This simple sample preparation provides sensitive (the limit of quantitation is 25 ng/mL for (R,S)-methadone and EDDP and 12.5 ng/mL for (R)- and (S)- methadone), accurate and precise (the intra-day and inter-day imprecision and inaccuracy are lower than 15%) quantification of the plasma concentration of these drugs. We have developed a reliable LC-MS/MS method for both routine therapeutic drug monitoring and pharmacokinetics studies and for toxicology analysis in the setting of methadone treatment or intoxication.

International audience; Impingement of a water jet on a rigid wall and entry of a rigid body into water are subject to common effects of compressibility, occurring during a very short period. Thanks to order of magnitude estimates and application of the fundamental laws of conservation, the extent and the duration of the domain of highly compressed water are obtained in terms of the Mach number and of the curvature at the tip of the jet, or of the projectile. The model works for jet fronts and body profiles of any shape.

The present work focuses on the collective effect on both bubble dynamics and mass transfer in a dense homogeneous bubble swarm for gas volume fractions${\it\alpha}$up to 30 %. The experimental investigation is carried out with air bubbles rising in a square column filled with water. Bubble size and shape are determined by means of a high-speed camera equipped with a telecentric lens. Gas volume fraction and bubble velocity are measured by using a dual-tip optical probe. The combination of these two techniques allows us to determine the interfacial area between the gas and the liquid. The transfer of oxygen from the bubbles to the water is measured from the time evolution of the concentration of oxygen dissolved in water, which is obtained by means of the gassing-out method. Concerning the bubble dynamics, the average vertical velocity is observed to decrease with${\it\alpha}$in agreement with previous experimental and numerical investigations, while the bubble agitation turns out to be weakly dependent on ${\it\alpha}$. Concerning mass transfer, the Sherwood number is found to be very close to that of a single bubble rising at the same Reynolds number, provided the latter is based on the average vertical bubble velocity, which accounts for the effect of the gas volume fraction on the bubble rise velocity. This conclusion is valid for situations where the diffusion coefficient of the gas in the liquid is very low (high Péclet number) and the dissolved gas is well mixed at the scale of the bubble. It is understood by considering that the transfer occurs at the front part of the bubbles through a diffusion layer which is very thin compared with all flow length scales and where the flow remains similar to that of a single rising bubble.

International audience; Design and optimization of cryogenic technologies for biogas upgrading require accurate determination of freeze-out boundaries. In cryogenic upgrading processes involving dry ice formation, accurate predictions of solid–liquid, solid–vapor, and solid–liquid–vapor equilibria are fundamental for a correct design of the heat exchanger surface in order to achieve the desired biomethane purity. Moreover, the liquefied biogas production process, particularly interesting for cryogenic upgrading processes due to the low temperature of the obtained biomethane, requires an accurate knowledge of carbon dioxide solubility in liquid methane to avoid solid deposition. The present work compares two different approaches for representing solid–liquid, solid–vapor, and solid–liquid–vapor equilibria for the CH4−CO2 mixture. Model parameters have been regressed in order to optimize the representation of phase equilibrium at low temperatures, with particular emphasis to the equilibria involving a solid phase. Furthermore, the extended bibliographic research allows determining the regions where more accurate data are needed.

International audience; The paper is concerned with dynamics of light solid in cavity with liquid subjected to rotational vibration in the external force field. New vibrational phenomenon – diving of a light cylinder to the cavity bottom is found. The experimental investigation of a horizontal annulus with a partition has shown that under vibration a light body situated in the upper part of the layer is displaced in a threshold manner some distance away from the boundary. In this case the body executes symmetric tangential oscillations. An increase of the vibration intensity leads to a tangential displacement of the body near the external boundary. This displacement is caused by the tangential component of the vibrational lift force, which appears as soon as the oscillations lose symmetry. In this case the trajectory of the body oscillatory motion has the form of a loop. The tangential lift force makes stable the position of the body on the inclined section of the layer and even in its lower part. A theoretical interpretation has been proposed, which explains stabilization of a quasi-equilibrium state of a light body near the cavity bottom in the framework of vibrational hydromechanics.

International audience; This paper studies the chemical attachment of pyridine on two semiconductor surfaces, Si(100) and Ge(100), at low coverages. We use thermodynamic arguments to show that the aromaticity of pyridine is preserved in both cases at low temperatures. At high temperatures, a transition toward nonaromatic structures-tetrapod structure for Si(100) and dipod structure for Ge(100)-occurs without cleavage of C-H bonds. We show that this transition can be explained by the tiny entropy increase associated with the disappearance of aromaticity.

International audience; Signaling cascades rely strongly on protein kinase-mediated substrate phosphorylation. Currently a major challenge in signal transduction research is to obtain high confidence substrate phosphorylation sites and assign them to specific kinases. In response to bacterial flagellin, a pathogen-associated molecular pattern (PAMP), we searched for rapidly phosphorylated proteins in Arabidopsis thaliana by combining multistage activation (MSA) and electron transfer dissociation (ETD) fragmentation modes, which generate complementary spectra and identify phosphopeptide sites with increased reliability. Of a total of 825 phosphopeptides, we identified 58 to be differentially phosphorylated. These peptides harbor kinase motifs of mitogen-activated protein kinases (MAPKs) and calcium-dependent protein kinases (CDPKs), as well as yet unknown protein kinases. Importantly, 12 of the phosphopeptides show reduced phosphorylation upon flagellin treatment. Since protein abundance levels did not change, these results indicate that flagellin induces not only various protein kinases but also protein phosphatases, even though a scenario of inhibited kinase activity may also be possible.

International audience; The microphthalmia-associated transcription factor (MITF) is indispensable for the viability of melanocytic cells, is an oncogene in melanoma and has a cell type-specific expression pattern. As the modulation of MITF activity by direct chemical targeting remains a challenge, we assessed a panel of drugs for their ability to downregulate MITF expression or activity by targeting its upstream modulators. We found that the multi-kinase inhibitors midostaurin and sunitinib downregulate MITF protein levels. To identify the target molecules shared by both the drugs in melanocytic cells, a chemical proteomic approach was applied and AMP-activated kinase (AMPK) was identified as the relevant target for the observed phenotype. RNA interference and chemical inhibition of AMPK led to a decrease in MITF protein levels. Reduction of MITF protein levels was the result of proteasomal degradation, which was preceded by enhanced phosphorylation of MITF mediated by ERK. As expected, downregulation of MITF protein levels by AMPK inhibition was associated with decreased viability. Together, these results identify AMPK as an important regulator for the maintenance of MITF protein levels in melanocytic cells.

The presence of biological matter (biofilms) in deep geological sites for storage of, for instance, toxic elements or groundwater in aquifers was clearly proved. That biomass triggers physical and chemical processes which greatly modify the durability and the sustainability of the sites. These processes, mainly from oxidative/reductive reactions, are poorly understood. This is mainly due to the fact that former studies were done at the macroscopic level far away from the micrometric scale where relevant processes induced by bacteria take place. Investigations at microscopic level are needed. Thus, we developed an experimental set-up based on the combined use of optical microscopy (transmission), atomic force microscopy (AFM) and electrical and electro-chemical AFM microscopy (EC_AFM) in order to get simultaneous information on topographic and electro-chemical processes. The first highly sensitive step was to use AFM with biological samples in liquid environment: wepresent here a study about AFM imaging of living, moving or self-immobilized bacteria, in their genuine physiological liquid medium and in true in vivo conditions. No external immobilization protocol, neither chemical nor mechanical was needed. For the first time, the native gliding movements of Gram negative Nostoc cyanobacteria upon the surface were studied by AFM. AFM height and mechanical stiffness data were simultaneously acquired. From these, mechanical parameters, inner turgor pressure and Young modulus, were derived for different bacterial species (Anabaenopsis circularis, Rhodococcus wratislaviensis). Our study revealed that AFM imaging is thus possible on moving living species. These results open a large window on new studies of both dynamical phenomena of practical and fundamental interests such as the formation of biofilms and dynamic properties of bacteria in real physiological conditions. The second delicate step was to combine AFM and optical measurements with electrical ones. We mounted a new experimental set-up coupling real-time (i) monitoring of optical properties as the optical density (OD) evolution related to bulk bacterial growth in liquid or as the counting of number of bacteria adhering on the surface of the sample as well and (ii) electrical and electrochemical measurements. Furthermore, these results will shortly be applied to the optimized monitoring of the in-situ activity of bacteria consuming oil pollutants, following this way, in real-time, the bioremediation of an oilcontaminated soil (ANR ECOTECH_BIOPHY program).; La présence de matière biologique (biofilms) dans les sites de stockage géologique profond, d'éléments toxiques ou encore de l'eau potable des aquifères est maintenant clairement démontrée. Cette biomasse est à l'origine de processus physiques et chimiques qui modifient considérablement la durabilité et la pérennité des sites concernés. Ces processus, principalement de type oxydo-réductif, sont encore mal compris. Ceci est principalement dû aux méthodes d'investigation, principalement macroscopiques, loin de l'échelle micrométrique caractéristique des bactéries. Seules des études, basées sur des méthodes d'investigation locale, peuvent apporter les informations requises. Ainsi, nous avons développé un dispositif expérimental basé sur l'utilisation combinée de la microscopie optique (en transmission), la microscopie à force atomique (AFM) et la microscopie AFM en mode électrique et électrochimique (EC_AFM) afin d'obtenir des informations simultanées sur la topographie de l'échantillon et sur les processus électrochimiques à l'échelle des bactéries. La première étape sensible consistait à utiliser l'AFM sur des échantillons biologiques en milieu liquide: nous présentons ici les résultats de l'imagerie AFM en milieu liquide de plusieurs types de bactéries dans leurs conditions physiologiques naturelles (conditions in vivo). Aucun protocole d'immobilisation, ni chimique ni mécanique, n'a été nécessaire; et pour la première fois, les mouvements de reptation de cyanobactéries Nostoc ont été étudiés par l'AFM. Les études AFM ont permis d'acquérir des données topographiques mais aussi mécaniques : nous avons pu ainsi mesurer le module d'Young, la pression de turgescence de différentes souches bactériennes (Anabaenopsis circularis, Rhodococcus wratislaviensis). Cette étude complète, a révélé que l'imagerie AFM est donc possible sur des espèces vivantes en mouvement. Ces résultats ouvrent une grande fenêtre sur de nouvelles études d'intérêts tels que la formation de biofilms et les propriétés dynamiques de bactéries dans des conditions physiologiques réelles. La deuxième étape délicate était de combiner l'AFM aux mesures optiques et électriques. Nous avons développé un nouveau dispositif expérimental permettant (i) le suivi de l'évolution de la croissance bactérienne par la mesure des propriétés optiques comme la densité optique DO (pour le développement bactérien en volume - milieu planctonique) , ou l'analyse de l'image du substrat par comptage du nombre de bactéries sur la surface de l'échantillon (biofilm), et (ii) les mesures électriques et électrochimiques. L'ensemble de ces résultats sera prochainement appliqué au développement de nouveaux outils de surveillance d'une biodépollution de terrain contaminé par les hydrocarbures, par le suivi in situ et en temps réel de l'activité de bactéries dépolluantes (ECOTECH_BIOPHY ANR).

International audience; In the background of the strong magnetic field the vacuum is suggested to possess an electromag- netically superconducting phase characterised by the charged ρ-meson condensate. The ρ-meson condensate is inhomogeneous due to the presence of the string-like defects which are parallel to the magnetic field. In agreement with these expectations, we have observed the presence of the ρ-vortices in numerical simulations of the vacuum of the quenched two-color lattice QCD in strong magnetic field background. We have found that in the quenched QCD the ρ-vortices form a liquid.