A new elasmobranch fauna from the early Miocene of Sharbithat (Sultanate of Oman) reveals the teeth of an ancient fantail stingray

Here we describe a new elasmobranch assemblage consisting of isolated dental material from the Aquitanian near-shore marine deposits of the Shuwayr and Warak formations at Sharbithat, in eastern Sultanate of Oman. The faunal composition clearly indicates affinities to other early Miocene elasmobranch-bearing localities worldwide. This assemblage is predominantly composed of large and common pelagic sharks as well as teeth attributable to a new species of fantail stingray, Taeniurops tosii, as old as the oldest undisputable fossil records of Taeniurops. The study of this fossil assemblage presented here improves the knowledge of the ancient elasmobranchs that frequented the eastern Arabian coasts during the closure of the Neotethys and the birth of the Arabian Sea. DOI: 10.1344/GeologicaActa2022.20.

Extended Czjzek model applied to NMR parameter distributions in sodium metaphosphate glass

The Extended Czjzek Model (ECM) is applied to the distribution of NMR parameters of a simple glass model (sodium metaphosphate, $\mathrm{NaPO_3}$) obtained by Molecular Dynamics (MD) simulations. Accurate NMR tensors, Electric Field Gradient (EFG) and Chemical Shift Anisotropy (CSA), are calculated from Density Functional Theory (DFT) within the well-established PAW/GIPAW framework. Theoretical results are compared to experimental high-resolution solid-state NMR data and are used to validate the considered structural model. The distributions of the calculated coupling constant $C_Q\propto |V_{zz}|$ and of the asymmetry parameter $\eta_Q$ that characterize the quadrupolar interaction are discussed in terms of structural considerations with the help of a simple point charge model. Finally, the ECM analysis is shown to be relevant for studying the distribution of CSA tensor parameters and gives new insight into the structural characterization of disordered systems by solid-state NMR.Comment: 17 pages, 12 figures to be published in J. Phys.: Condens. Matte

Pré Dimensionnement d’une machine à flux axial à double stator pour un cahier des charges d’une hydrolienne à entraînement circonférentiel

Dans la présente étude une structure de machine à flux axial à double stator est présentée, un modèle électromagnétique de pré dimensionnement au premier ordre est décrit pour cette structure. Les dimensions principales de cette machine ainsi qu’un modèle thermique sont présentés pour un cahier des charges d’hydrolienne Rim-Driven. Ces structures originales d’hydroliennes, qui ont fait l’objet de précédentes études au laboratoire (IRENav), sont caractérisées par le fait que les parties actives de la machine se situent sur la périphérie de l’hélice. Les volumes des matériaux actifs et le comportement thermique de la machine axiale sont comparés avec une machine radiale à aimants permanents dimensionnée lors de travaux précédents. Cette première étude, montre un intérêt pour ce type de structures poly-entrefer, notamment en termes de compacité. En effet, l’étude démontre que ces machines sont caractérisées par un comportement thermique moins contraignant

Pré Dimensionnement d’une machine à flux axial à double stator pour un cahier des charges d’une hydrolienne à entraînement circonférentiel

National audienceDans la présente étude une structure de machine à flux axial à double stator est présentée, un modèle électromagnétique de pré dimensionnement au premier ordre est décrit pour cette structure. Les dimensions principales de cette machine ainsi qu’un modèle thermique sont présentés pour un cahier des charges d’hydrolienne Rim-Driven. Ces structures originales d’hydroliennes, qui ont fait l’objet de précédentes études au laboratoire (IRENav), sont caractérisées par le fait que les parties actives de la machine se situent sur la périphérie de l’hélice. Les volumes des matériaux actifs et le comportement thermique de la machine axiale sont comparés avec une machine radiale à aimants permanents dimensionnée lors de travaux précédents. Cette première étude, montre un intérêt pour ce type de structures poly-entrefer, notamment en termes de compacité. En effet, l’étude démontre que ces machines sont caractérisées par un comportement thermique moins contraignant

A new elasmobranch fauna from the early Miocene of Sharbithat (Sultanate of Oman) reveals the teeth of an ancient fantail stingray

Acknowledgement. We gratefully thank Jorge Carrillo-Briceño and Gloria Arratia for their constructive criticism and comments on the manuscript. We also wish to thank the Ministry of Heritage and Tourism of the Sultanate of Oman for granting us permission to carry out fieldwork along the Omani Arabian sea shores, with specific reference to H.E. Salim Mohammed Al Mahruqi, Minister; Mr. Sultan Said Al-Bakri, Director General for Archaeology; Mr. Khamis Al Asmi, Director of the Department of Excavations and Archaeological Studies; M. Ali Al Mashani of the Salalah department. We would like to thank the Consultative Commission for Excavations Abroad of the French Ministry of European and Foreign Affairs, the Agence Nationale de la Recherche with the NeoArabia Program (ANR-16-CE03-0007, CNRS, Inrap, MNHN) for funding the archaeological Mission «Archaeology of the Arabian Sheashores»Here we describe a new elasmobranch assemblage consisting of isolated dental material from the Aquitanian near-shore marine deposits of the Shuwayr and Warak formations at Sharbithat, in eastern Sultanate of Oman. The faunal composition clearly indicates affinities to other early Miocene elasmobranch-bearing localities worldwide. This assemblage is predominantly composed of large and common pelagic sharks as well as teeth attributable to a new species of fantail stingray, Taeniurops tosii, as old as the oldest undisputable fossil records of Taeniurops. The study of this fossil assemblage presented here improves the knowledge of the ancient elasmobranchs that frequented the eastern Arabian coasts during the closure of the Neotethys and the birth of the Arabian Sea

Etude structurale des verres de borates par une approche combinant résonance magnétique nucléaire du solide et dynamique moléculaire

International audienceL'oxyde de bore B$_2$ O$_3$ est ajouté à de nombreuses compositions verrières dans le but d'améliorer certaines propriétés, comme dans le verre Pyrex ou Duran. Pour étudier la structure et les propriétés des verres, la Résonance Magnétique Nucléaire est de plus en plus utilisée. Il est également fréquent de réaliser des simulations numériques des structures étudiées afin d'aider à l'analyse des données RMN obtenues expérimentalement. La possibilité de réaliser des calculs de paramètres RMN sur des structures de quelques centaines d'atomes par des méthodes DFT permet de faire le lien entre RMN et DM. Dans cette étude, des verres de compositions xNa$_2$O-(1-x)B$_2$O$_3$ ont été étudiés. En parallèle des mesures RMN à champs multiples réalisées (7.0, 9.4, 11.75 et 18.8T), des simulations par dynamique moléculaires (DM) ont été menées sur des systèmes de 100-200 atomes, soit en utilisant des potentiels classiques soit par des calculs ab-initio (AIMD), suivies de calculs DFT des paramètres RMN par la méthode GIPAW

Synthesis and properties of macroporous SiC ceramics synthesized by 3D printing and chemical vapor infiltration/deposition

Open porosity cellular SiC-based ceramics have a great potential for energy conversion, e.g. as solar receivers. In spite of their tolerance to damage, structural applications at high temperature remain limited due to high production costs or inappropriate properties. The objective of this work was to investigate an original route for the manufacturing of porous SiC ceramics based on 3D printing and chemical vapor infiltration/deposition (CVI/CVD). After binder jetting 3D-printing, the green α-SiC porous structures were reinforced by CVI/CVD of SiC using CH3SiCl3/H2. The multiscale structure of the SiC porous specimens was carefully examined as well as the elemental and phase content at the microscale. The oxidation and thermal shock resistance of the porous SiC structures and model specimens were also studied, as well as the thermal and mechanical properties. The pure and dense CVI/CVD-SiC coating considerably improves the mechanical strength, oxidation resistance and thermal diffusivity of the material

The experimental power of FR900359 to study Gq-regulated biological processes.

Despite the discovery of heterotrimeric αβγ G proteins ∼25 years ago, their selective perturbation by cell-permeable inhibitors remains a fundamental challenge. Here we report that the plant-derived depsipeptide FR900359 (FR) is ideally suited to this task. Using a multifaceted approach we systematically characterize FR as a selective inhibitor of Gq/11/14 over all other mammalian Gα isoforms and elaborate its molecular mechanism of action. We also use FR to investigate whether inhibition of Gq proteins is an effective post-receptor strategy to target oncogenic signalling, using melanoma as a model system. FR suppresses many of the hallmark features that are central to the malignancy of melanoma cells, thereby providing new opportunities for therapeutic intervention. Just as pertussis toxin is used extensively to probe and inhibit the signalling of Gi/o proteins, we anticipate that FR will at least be its equivalent for investigating the biological relevance of Gq

How can the MHC mediate social odor via the microbiota community? A deep dive into mechanisms

Genes of the major histocompatibility complex (MHC) have long been linked to odor signaling and recently researchers’ attention has focused on MHC structuring of microbial communities and how this may in turn impact odor. However, understanding of the mechanisms through which the MHC could affect the microbiota to produce a chemical signal that is both reliable and strong enough to ensure unambiguous transmission of behaviorally important information remains poor. This is largely because empirical studies are rare, predictions are unclear, and the underlying immunological mechanisms governing MHC-microbiota interactions are often neglected. Here we review the immunological processes involving MHC class II (MHC-II) that could affect the commensal community. Focusing on immunological and medical research, we provide background knowledge for non-immunologists by describing key players within the vertebrate immune system relating to MHC-II molecules (which present extracellular-derived peptides, and thus interact with extracellular commensal microbes). We then systematically review the literature investigating MHC-odor-microbiota interactions in animals and identify areas for future research. These insights will help to design studies that are able to explore the role of MHC-II and the microbiota in the behavior of wild populations in their natural environment and consequently propel this research area forward

The search campaign to identify and Image the Philae Lander on the surface of comet 67P/Churyumov-Gerasimenko

On the 12th of November 2014, the Rosetta Philae Lander descended to make the first soft touchdown on the surface of a comet – comet 67P/Churyumov- Gerasimenko. That soft touchdown did occur but due to the failure in the firing of its two harpoons, Philae bounced and travelled across the comet making contact with the surface twice more before finally landing in a shaded rocky location somewhere on the southern hemisphere of the comet. The search campaign, led by ESA, involved multiple teams across Europe with a wide range of techniques used in support of it. This search campaign would continue through 2015 where a prime candidate on the surface was identified and on into 2016 to end on the 2nd of September 2016 when a definitive and conclusive image was taken of the lander on the surface of the comet, confirming the prime candidate to indeed be Philae