Neuroglobin, clues to function and mechanism

Neuroglobin is expressed in vertebrate brain and belongs to a branch of the globin family that diverged early in evolution. Sequence conservation and presence in nervous cells of several taxa suggests a relevant role in the nervous system, with tight structural restraints. Twenty years after its discovery, a rich scientific literature provides convincing evidence of the involvement of neuroglobin in sustaining neuron viability in physiological and pathological conditions however, a full and conclusive picture of its specific function, or set of functions is still lacking. The difficulty of unambiguously assigning a precise mechanism and biochemical role to neuroglobin might arise from the participation to one or more cell mechanism that redundantly guarantee the functioning of the highly specialized and metabolically demanding central nervous system of vertebrates. Here we collect findings and hypotheses arising from recent biochemical, biophysical, structural, in cell and in vivo experimental work on neuroglobin, aiming at providing an overview of the most recent literature. Proteins are said to have jobs and hobbies, it is possible that, in the case of neuroglobin, evolution has selected for it more than one job, and support to cover for its occasional failings. Disentangling the mechanisms and roles of neuroglobin is thus a challenging task that might be achieved by considering data from different disciplines and experimental approaches

Towards passive ultrasonic sounding of a steelconcrete-steel containment structure using embedded optical fibers

International audienceWe present a Steel-Concrete wall model equipped with several embedded fiber Bragg Gratings (FBGs) and several embedded and surface piezoelectric accelerometers (PZAs). We compare the performances of these embedded sensors for several ultrasonic sources disposed on the surface of the wall and emitting at frequencies between a few tens and a few hundreds of kilohertz. We observed that a significant part of the wave energy can be transmitted to the concrete through the surface liner, despite the high mechanical contrasts between steel and concrete. Using a collection of random hammer impacts applied on the steel surface, we further attempted to reconstruct empirical Green's functions between pairs of sensors buried into the structure using passive seismic methods

Point mutations at a key site alter the cytochrome P450 oleP structural dynamics

Substrate binding to the cytochrome P450 OleP is coupled to a large open-to-closed transition that remodels the active site, minimizing its exposure to the external solvent. When the aglycone substrate binds, a small empty cavity is formed between the I and G helices, the BC loop, and the substrate itself, where solvent molecules accumulate mediating substrate-enzyme interactions. Herein, we analyzed the role of this cavity in substrate binding to OleP by producing three mutants (E89Y, G92W, and S240Y) to decrease its volume. The crystal structures of the OleP mutants in the closed state bound to the aglycone 6DEB showed that G92W and S240Y occupied the cavity, providing additional contact points with the substrate. Conversely, mutation E89Y induces a flipped-out conformation of this amino acid side chain, that points towards the bulk, increasing the empty volume. Equilibrium titrations and molecular dynamic simulations indicate that the presence of a bulky residue within the cavity impacts the binding properties of the enzyme, perturbing the conformational space explored by the complexes. Our data highlight the relevance of this region in OleP substrate binding and suggest that it represents a key substrate-protein contact site to consider in the perspective of redirecting its activity towards alternative compounds

Spatial Covariance Modeling for Stochastic Subgrid‐Scale Parameterizations Using Dynamic Mode Decomposition

Stochastic parameterizations are increasingly being used in climate modeling to represent subgrid‐scale processes. While different parameterizations are being developed considering different aspects of the physical phenomena, less attention is given to technical and numerical aspects. In particular,empirical orthogonal functions (EOFs) are employed when a spatial structure is required. Here, we provide evidence they might not be the most suitable choice. By applying an energy‐consistent parameterization to the two‐layer quasi‐geostrophic (QG) model, we investigate the model sensitivity to apriori assumptions made on the parameterization. In particular, we consider here two methods to prescribe the spatial covariance of the noise:first, by using climatological variability patterns provided by EOFs,and second, by using time‐varying dynamics‐adapted Koopman modes, approximated by dynamic mode decomposition (DMD). The performance of the two methods are analyzed through numerical simulations of the stochastic system on a coarse spatial resolution and the outcomes compared to a high‐resolution simulation of the original deterministic system. The comparison reveals that the DMD‐based noise covariance scheme outperforms the EOF‐based one. The use of EOFs leads to a significant increase of the ensemble spread and to a meridional misplacement of the bimodal eddy kinetic energy (EKE) distribution.Conversely, using DMDs, the ensemble spread is confined, the meridional propagation of the zonal jet stream is accurately captured, and the total variance of the system is improved. Our results highlight the importance of the systematic design of stochastic parameterizations with dynamically adapted spatial correlations, rather than relying on statistical spatial patterns

Surveillance non destructive de l'état du béton des enceintes de confinement des centrales nucléaires avec et sans précontrainte

International audienceLes enceintes de confinement en béton précontraint des centrales nucléaires jouent un rôle majeur de sécurité en cas d'accident pour préserver l’environnement de fuites radioactives. Pour assurer la sûreté des installations, il est important de contrôler régulièrement les structures dont le prolongement de la durée de vie est acté et d’estimer leur endommagement en cas d’accident. Un accident provoque des augmentations de pression et de température dans l’enceinte interne et donc une diminution de la contrainte et une augmentation de la température du béton. Dans le projet PIA ANR ENDE, huit universitaires et laboratoires industriels avec des compétences en Évaluation Non Destructive (END), ont étudié le potentiel et la pertinence d’utiliser des ENDs pour suivre l’état du béton en termes de contrainte, d’endommagement et de fissuration dans de telles conditions. Dans cette présentation, nous nous concentrons sur la synthèse des résultats obtenus avec différentes techniques ENDs. Des tests expérimentaux ont été réalisés en laboratoire sur des dalles de 0,5 m x 0,25 m x 0,12 m, saines ou endommagées thermiquement, sous différents chargements statiques en compression, pour une formulation de béton spécifique. De manière complémentaire, des mesures ENDs ont été effectuées in-situ pendant une épreuve enceinte jusqu’à une pression de 4 bars sur le moyen d’essai VeRCoRs, maquette à l'échelle 1/3 d’une enceinte de confinement double paroi (cylindre de diamètre égal à 16 m, de 30 m de hauteur avec des parois de 0,40 m d'épaisseur). Des mesures radar (GPR), capacitive, de résistivité, de perméabilité et des mesures ultrasonores (impact echo,ondes de surface, pulse echo, interférométrie des ondes de coda, acoustique non linéaire, etc.) ont été entreprises. De bons accords sont observés entre les mesures de laboratoire et celles in situ. Cette étude ouvre des perspectives industrielles et de recherche notamment en lien avec la fusion de données pour l’estimation quantitative de propriétés telles que la teneur en eau, la porosité, la perméabilité

Non Destructive Evaluation of concrete material properties for nuclear power plant survey: results in the laboratory and on the VeRCoRS mock-up

NDE/NDT, Structural Materials Technology for Highways and Bridges (SMT) and the International Symposium on Non-Destructive Testing in Civil Engineering (NDT-CE) 2018, New Brunswick, ETATS-UNIS, 27-/08/2018 - 29/06/2018Pre-stressed concrete nuclear power plant containment vessel is the third barrier in case of an accident so that quantifying concrete properties with Non Destructive Evaluation (NDE) is a continuing goal. This includes the mapping of the following concrete properties: elastic modulus, water saturation, permeability. In addition, those measurements have to be challenged with the level of stress (which will be modified during an accident) possibly coupled with thermal induced damage. In the ANR French project 'Non Destructive Evaluation of containment nuclear plant structures' (ENDE) eight partners have carried out laboratory and in situ NDE measurements with the aim to compare and combine them to reach quantitative useful information about concrete conditions. In this paper we present a synthesis of the mains results obtained with classical and non-classical NDE methods. This includes electromagnetic techniques such as radar, capacitive measurements, resistivity measurements and ultrasonic measurements (impact echo, ultrasonic pulse velocity - in reflexion and transmission mode for longitudinal and transverse waves, surface waves, diffuse waves, coda wave interferometry, nonlinear acoustics, etc.). The laboratory experiments have been conducted on slabs 0.5 m x 0.25 m x 0.12 m, for one concrete mix formulated to be representative of nuclear containment walls, in different conditions: - sound concrete without any stress for different water saturations,- heat damage of partially saturated slab (at 80°C, 150°C, 200°C),- sound concrete under stress (up to 30% of the compressive strength),- heat damage concrete under stress.A series of NDE method combinations (using data fusion approach) is performed to solve the problem of multiple sensitivity issues. This laboratory work is then transposed on the VeRCoRS mock-up which is a 1/3 scaled concrete power plant (a Õ 16 m x h 30 m cylinder, with 0.40 m thick walls) heavily instrumented (700 sensors, 2 km of fiber optic). In this paper we present results obtained before, during and after a decennial test simulation which consists in increasing the internal pressure with air, maintaining its level to 4 bars during 2 hours and then decreasing back to the atmospheric pressure level.To conclude industrial and research perspectives are presented.Pre-stressed concrete nuclear power plant containment vessel is the third barrier in case of an accident so that quantifying concrete properties with Non Destructive Evaluation (NDE) is a continuing goal. This includes the mapping of the following concrete properties: elastic modulus, water saturation, permeability. In addition, those measurements have to be challenged with the level of stress (which will be modified during an accident) possibly coupled with thermal induced damage. In the ANR French project 'Non Destructive Evaluation of containment nuclear plant structures' (ENDE) eight partners have carried out laboratory and in situ NDE measurements with the aim to compare and combine them to reach quantitative useful information about concrete conditions. In this paper we present a synthesis of the mains results obtained with classical and non-classical NDE methods. This includes electromagnetic techniques such as radar, capacitive measurements, resistivity measurements and ultrasonic measurements (impact echo, ultrasonic pulse velocity - in reflexion and transmission mode for longitudinal and transverse waves, surface waves, diffuse waves, coda wave interferometry, nonlinear acoustics, etc.). The laboratory experiments have been conducted on slabs 0.5 m x 0.25 m x 0.12 m, for one concrete mix formulated to be representative of nuclear containment walls, in different conditions: - sound concrete without any stress for different water saturations,- heat damage of partially saturated slab (at 80°C, 150°C, 200°C),- sound concrete under stress (up to 30% of the compressive strength),- heat damage concrete under stress.A series of NDE method combinations (using data fusion approach) is performed to solve the problem of multiple sensitivity issues. This laboratory work is then transposed on the VeRCoRS mock-up which is a 1/3 scaled concrete power plant (a Õ 16 m x h 30 m cylinder, with 0.40 m thick walls) heavily instrumented (700 sensors, 2 km of fiber optic). In this paper we present results obtained before, during and after a decennial test simulation which consists in increasing the internal pressure with air, maintaining its level to 4 bars during 2 hours and then decreasing back to the atmospheric pressure level.To conclude industrial and research perspectives are presented

Non destructive monitoring of mechanical stress in concrete for the survey of nuclear power plants

Session 2-1 - NDE and NDT for Civil Engineering, paper QNDE2019-6837, 3 pagesInternational audienceTo prevent consequences of damage in case of accident, some barriers of pre-stressed concrete are included in the nuclear power plant structures. Hence, to insure the nuclear security, it is important to control these structures. The nuclear accident induces pressure and temperature increases. This case is studied in a French Project involving eight academic and industrial laboratories with skills in NDE (Non-Destructive Evaluation) methods. In this paper, we focus on the synthesis for the results with different techniques in relation with the evolution of stress in the structure. Experiments tests have been conducted on slabs 0.5 m x 0.25 m x 0.12 m submitted to compressive load, for one concrete mix formulated to be representative of nuclear containment. In situ NDE measurements have been done during a test simulating nuclear accident. These experiments were realized on the Vercors mock-up which is a 1/3 scaled concrete power plant (? 16 m x h 30 m cylinder, with 0.40 m thick walls) submitted to internal pressure up to 4 bars. This study includes electromagnetic techniques such as radar, capacitive, resistivity, permeability and ultrasonic measurements (impact echo, ultrasonic pulse velocity for volume and surface waves, diffuse waves, coda wave interferometry, nonlinear acoustics, etc.). Good agreements are observed between laboratory and in situ measurements. Industrial and research perspectives are presented

Surveillance non destructive de l'état du béton des enceintes de confinement des centrales nucléaires avec et sans précontrainte

International audienceLes enceintes de confinement en béton précontraint des centrales nucléaires jouent un rôle majeur de sécurité en cas d'accident pour préserver l’environnement de fuites radioactives. Pour assurer la sûreté des installations, il est important de contrôler régulièrement les structures dont le prolongement de la durée de vie est acté et d’estimer leur endommagement en cas d’accident. Un accident provoque des augmentations de pression et de température dans l’enceinte interne et donc une diminution de la contrainte et une augmentation de la température du béton. Dans le projet PIA ANR ENDE, huit universitaires et laboratoires industriels avec des compétences en Évaluation Non Destructive (END), ont étudié le potentiel et la pertinence d’utiliser des ENDs pour suivre l’état du béton en termes de contrainte, d’endommagement et de fissuration dans de telles conditions. Dans cette présentation, nous nous concentrons sur la synthèse des résultats obtenus avec différentes techniques ENDs. Des tests expérimentaux ont été réalisés en laboratoire sur des dalles de 0,5 m x 0,25 m x 0,12 m, saines ou endommagées thermiquement, sous différents chargements statiques en compression, pour une formulation de béton spécifique. De manière complémentaire, des mesures ENDs ont été effectuées in-situ pendant une épreuve enceinte jusqu’à une pression de 4 bars sur le moyen d’essai VeRCoRs, maquette à l'échelle 1/3 d’une enceinte de confinement double paroi (cylindre de diamètre égal à 16 m, de 30 m de hauteur avec des parois de 0,40 m d'épaisseur). Des mesures radar (GPR), capacitive, de résistivité, de perméabilité et des mesures ultrasonores (impact echo,ondes de surface, pulse echo, interférométrie des ondes de coda, acoustique non linéaire, etc.) ont été entreprises. De bons accords sont observés entre les mesures de laboratoire et celles in situ. Cette étude ouvre des perspectives industrielles et de recherche notamment en lien avec la fusion de données pour l’estimation quantitative de propriétés telles que la teneur en eau, la porosité, la perméabilité