Nanoscale relationships between uranium and carbonaceous material in alteration halos around unconformity-related uranium deposits of the Kiggavik camp, Paleoproterozoic Thelon Basin, Nunavut, Canada

International audienceConcentrations of 7% U and 1% Cu were identified in massive, brecciated, and amorphous carbonaceous materials (CM) characterized by strongly negative values of carbon stable isotopes (δ13C = − 39.1‰ relative to PDB). The anomalies are restricted to clay alteration halos developed in Neoarchean Woodburn Lake group metagreywacke that is the predominant host of unconformity-related uranium (U) deposits in the Kiggavik exploration camp. Petrographic and microstructural analyses by SEM, X-Ray Diffraction, HR-TEM and RAMAN spectroscopy identified carbon veils, best described as graphene-like carbon, upon which nano-scale uraninite crystals are distributed. CM are common in U systems such as the classic Cretaceous roll-front deposits and the world-class Paleoproterozoic unconformity-related deposits. However, the unusual spatial and textural association of U minerals and CM described herein raises questions on mechanisms that may have been responsible for the precipitation of the CM followed by crystallization of U oxides on its surfaces. Based on the characteristics presented herein, the CMs at Kiggavik are interpreted as hydrothermal in origin. Furthermore, the nanoscale organization and properties of these graphene-like layers that host U oxide crystallites clearly localized U oxide nucleation and growth

Solar axions in large extra dimensions

We wish to thank Barbara and Janusz Sylwester who kindly shared with us the SphinX measurements of solar X-rays and who answered with details our questions about the working principles of the SphinX detector. MBG would like to thank the LPSC (UGA, CNRS, Grenoble INP) for kind hospitality. The work of MBG has been partially supported by MICINN (PID2019-105943GB-I00/AEI/10.13039/501100011033) and "Junta de Andalucia" grants P18-FR-4314 and A-FQM-211-UGR18.The axion could be used as a probe for extra dimensions. In large extra dimensions, besides the QCD axion one obtains an infinite tower of massive Kaluza-Klein (KK) states. We describe the processes of KK axions production in the Sun via the axion-photon coupling, g(a gamma gamma), and we derive the number density of KK axions that get trapped into the solar gravitational field and then accumulate over cosmic times. The large multiplicity of states, as well as their masses in the keV-range, deeply alter the phenomenology of the axion. This scenario leads us to propose the presence of KK axions as an interpretation of the non-thermal distribution of the solar X-rays. In this work, we dedicate special attention on the astrophysical and cosmological bounds that apply to the model. In particular, we show how the KK axions may escape the EBL limit that constrains standard ALPs in the same mass range. Present searches for KK axions make use of the decay channel, a -> gamma gamma, for which we revise the event rate; our value lies orders of magnitude below the rate usually quoted in the literature. This major conclusion stems from recent measurements of the luminosity of the quiet Sun which acts as an irreducible limit. The revised model remains a viable and an attractive explanation for multiple astrophysical observations, and we propose several approaches to search for solar KK axions in the near future.Spanish GovernmentEuropean Commission PID2019-105943GB-I00/AEI/10.13039/501100011033Junta de Andalucia P18-FR-4314 A-FQM-211-UGR1

New solar X-ray constraints on keV Axion-Like Particles

The decay of Axion-Like Particles (ALPs) trapped in the solar gravitational field would contribute to the observed solar X-ray flux, hence constraining ALP models. We improve by one order of magnitude the existing limits in the parameter space $(g_{a\gamma\gamma}, m)$ by considering ALPs production via photon coalescence. For $g_{ae} \neq 0$, we demonstrate that trapped ALPs can be Compton-absorbed while crossing the Sun, resulting in two regimes in the exclusion limits, with a transition triggered by $g_{ae}$. Out of the transitional region, the solar X-ray constraints on ALPs are exclusively governed by $g_{a\gamma\gamma}$.Comment: 6 pages, 4 figure

Les veines synmétamorphiques de quartz à disthène : témoins d'un métamorphisme associé à l'amincissement post-orogénique (Meseta occidentale, Maroc)

International audienceDes études récentes portant sur la chaîne hercynienne marocaine ont essayé de démontrer par de nombreux arguments d'ordre métamorphique, magmatique et structural qu' à une période de collision succède une évolution induite par le retour vers un équilibre thermique et gravitaire d'une croûte sur-épaissie. Par cette étude nous nous attacherons à mettre en évidence ce caractère généralisé de la tectonique extensive post-collision. Dans le massif hercynien des Rehamna, les veines de quartz à disthène sont encaissées dans des métapélites affectées par un métamorphisme à caractère barrovien, qui atteint les conditions du faciès des amphibolites et, de façon synchrone, la fusion partielle qui a engendré les granitoïdes de la région. De nouvelles observations de terrain appuyées par des travaux de laboratoire ont permis de mettre en évidence les caractères suivants : (i) les veines ou les filons de quartz à disthène sont clairement sécants et donc tardifs par rap-port à la stratification et la foliation régionale S0-1 associée à la première phase tectonothermale qui est synchrone de la collision hercynienne ; donc ces veines quartzitiques à disthène sont liées à une structuration plus récente. (ii) la structure pegmatitique et l'orientation des paragenèses minérales (disthène + quartz + micas blancs +/- tourmaline) dans les veines suggèrent une cristallisation qui correspond à une précipitation de minéraux à partir d'une solution hydrothermale riche en silice dans des ouvertures macroscopiques. (iii) presque toujours les veines discordantes de quartz contenant ce silicate d'alumine sont associées à des zones métamorphiques marquées par une forte activité hydrothermale d'origine magmatique, et de ce fait elles sont considérées comme pénécontemporaines des pegmatites tardi-magmatiques, des veines de tourmalinite et des dykes de greisen minéralisés en béryl, rutile et cassitérite. Dans le cadre régional, le premier apport de cette étude est de susciter une hypothèse : le disthène n'est pas attribué à la pression lithostatique, c'est-à-dire à la profondeur, mais plutôt à la pression de fluide engendrée par une solution hydrothermale en surpression. La présente note s'attache précisément à proposer un processus géodynamique où sont intégrés d'une part les veines ou filons synmétamorphiques de quartz à disthène, et d'autre part, l'amincissement crustal post-orogénique, considéré comme élément structural majeur dont le développement s'est accompagné de plu-sieurs manifestations hydrothermales de grande ampleur, vraisemblablement associées à un magmatisme granitique qui contrôle la distribution de la quasi-totalité des minéralisations dans le massif hercynien des Rehamna. Recent studies on the Moroccan Hercynian Belt have used metamorphic, magmatic and structural evidence to demonstrate that the post-collisional period was driven by return of the thickened crust towards thermal and gravi-tational equilibrium. In this study, we aim to characterize this general post-collisional extensional tectonic event. In the Rehamma Hercynian Massif, quartz-kyanite veins are found in association with amphibolite facies Barrovian metapelites. This metamorphism is synchronous with the partial melting episode which generated granitoids in the same region. Both experimental studies and field observations have led to the following conclusions: (i) quartz-kyanite veins or sills occurred later than the stratification and the regional foliation S0-1, which are associated with the first tectonothermal stage of the Hercynian collision. These veins are therefore contemporaneous with a more recent tectonic event. (ii) In the veins, both the pegmatitic structure and orientation of the paragenetic assemblage (kyanite + quartz + muscovite +/- tourmaline) suggest that the minerals precipitated from silica-rich hydrothermal solutions within macroscopic cracks. (iii) Discordant quartz-kyanite veins are usually found in association with metamorphic zones which have been altered by intense hydrothermal activity of magmatic origin. These kyanite-quartz veins can be viewed as penecontemporaneous with other late-magmatic pegmatites, tourmaline veins and greisen dykes rich in beryl, rutile and cassiterite. In this study, we suggest that kyanite growth was induced by high-pressure hydrothermal fluids rather than by litho-static pressure alone (i.e. depth). We show that both quartz-kyanite veins/sills and post-orogenic crustal thinning can be integrated into a single geodynamic process. Significant hydrothermal events are contemporaneous with post-orogenic crustal thinning and are probably associated with the granitic magmatism which controls the distri-bution of almost all the mineralisation in the Rehamna Hercynian Massif

Illite-smectite mixed-layer minerals in hydrothermal alteration of volcanic rocks: I. One-dimensional XRD structure analysis and characterisation of component layers.

International audienceFor a series of mixed-layer illite-smectite (I-S) minerals from a drill hole near the Kakkonda geothermal field, one-dimensional structure analysis by X-ray diffraction (XRD) was performed using Ca-saturated specimens at both air-dried and ethylene glycol solvated states. The expandability characteristics of component layers were also examined by means of alkylammonium exchange and Li-saturation. The K content in illite layer was almost constant at 1.5-1.7/O20(OH)4 in the I-S series from 3% to 85% of I-layer content (% I). The layer charge of smectite layer varied slightly within the ranges of R1 I-S samples showed complicated expandability with alkylammonium exchange. The XRD patterns of dodecylammonium exchanged I-S samples can be interpreted by random interstratification of several types of sub-units such as layer-doublets, layer-triplets and layer-quarutets present in the crystallites. This interpretation is consistent with the variation in the occurrence probabilities of layer-multiplets calculated from the junction probabilities and the proportions of layers. Because the interpretation indicates that I-S is a stack of various types of the sub-units, the smectite illitization can be described by a systematic change in the type and proportion of the sub-units constituting crystallites

Middle Permian Telodiagenetic Processes in Neoproterozoic Sequences, Tandilia System, Argentina

In the Tandilia Basin, Buenos Aires Province, Argentina, we study the genesis of mud beds and pipes in the Loma Negra Formation (limestones), Sierras Bayas area, together with the emplacement of alunite and aluminum phosphate sulfate (APS) minerals in the Las Aguilas Formation, Barker area. All these features are related to basin inversion, uplift, erosion, and injection or expulsion, or infiltration of fluids and oxidation reactions in the exhumed rocks during a telodiagenetic stage. On the basis of K--Ar dating of alunite in the Las Aguilas Formation (claystones) giving an age of 254 ± 7 Ma (middle Permian), these processes are considered to be linked to a major geological event which affected these Neoproterozoic lithostratigraphic units: the folding of the Ventania System, located 150 km to the SW of the study area.Centro de Tecnología de Recursos Minerales y Cerámic

Common coding variant in SERPINA1 increases the risk for large artery stroke

Large artery atherosclerotic stroke (LAS) shows substantial heritability not explained by previous genome-wide association studies. Here, we explore the role of coding variation in LAS by analyzing variants on the HumanExome BeadChip in a total of 3,127 cases and 9,778 controls from Europe, Australia, and South Asia. We report on a nonsynonymous single-nucleotide variant in serpin family A member 1 (SERPINA1) encoding alpha-1 antitrypsin [AAT; p.V213A; P = 5.99E-9, odds ratio (OR) = 1.22] and confirm histone deacetylase 9 (HDAC9) as a major risk gene for LAS with an association in the 3?-UTR (rs2023938; P = 7.76E-7, OR = 1.28). Using quantitative microscale thermophoresis, we show that M1 (A213) exhibits an almost twofold lower dissociation constant with its primary target human neutrophil elastase (NE) in lipoprotein-containing plasma, but not in lipid-free plasma. Hydrogen/deuterium exchange combined with mass spectrometry further revealed a significant difference in the global flexibility of the two variants. The observed stronger interaction with lipoproteins in plasma and reduced global flexibility of the Val-213 variant most likely improve its local availability and reduce the extent of proteolytic inactivation by other proteases in atherosclerotic plaques. Our results indicate that the interplay between AAT, NE, and lipoprotein particles is modulated by the gate region around position 213 in AAT, far away from the unaltered reactive center loop (357-360). Collectively, our findings point to a functionally relevant balance between lipoproteins, proteases, and AAT in atherosclerosis

Consensus Recommendations for the Use of Automated Insulin Delivery (AID) Technologies in Clinical Practice

International audienceThe significant and growing global prevalence of diabetes continues to challenge people with diabetes (PwD), healthcare providers and payers. While maintaining near-normal glucose levels has been shown to prevent or delay the progression of the long-term complications of diabetes, a significant proportion of PwD are not attaining their glycemic goals. During the past six years, we have seen tremendous advances in automated insulin delivery (AID) technologies. Numerous randomized controlled trials and real-world studies have shown that the use of AID systems is safe and effective in helping PwD achieve their long-term glycemic goals while reducing hypoglycemia risk. Thus, AID systems have recently become an integral part of diabetes management. However, recommendations for using AID systems in clinical settings have been lacking. Such guided recommendations are critical for AID success and acceptance. All clinicians working with PwD need to become familiar with the available systems in order to eliminate disparities in diabetes quality of care. This report provides much-needed guidance for clinicians who are interested in utilizing AIDs and presents a comprehensive listing of the evidence payers should consider when determining eligibility criteria for AID insurance coverage

Illite-smectite mixed-layer minerals in hydrothermal alteration of volcanic rocks: II. One- dimensional HRTEM structure images and formation mechanisms.

International audienceSmectite illitization was investigated in felsic volcaniclastic rocks from a drill core near the Kakkonda active geothermal system, Japan, using high resolution transmission electron microscopy (HRTEM) that provided one-dimensional structure images of mixed-layer illite-smectite (I-S) minerals normal to [hk0]. Simulated images of a rectorite-like structure revealed that smectite can be distinguished from illite in mixed-layer I-S by HRTEM if the basal spacing of smectite is larger than that of illite. The larger basal spacing of smectite, 1.3 nm under HRTEM, was obtained by intercalation of dodecylammonium ions into smectitic interlayers. In simulated and observed images normal to [hk0], tetrahedral (T) and octahedral (O) cation-layers are imaged as dark lines, an illitic interlayer a bright line, and a smectitic interlayer a dark line sandwiched by two bright lines. Samples are from 435 m (5% I; R0), 635 m (35% I; R0), 656 m (62% I; R1), and 756 m (85% I; R3) depths where % I is the percent of illite layers in a sample and R is the Reichweite parameter. Sample 435 consisted mostly of smectite, and illite layers occurred, though small in amount, as M1 units (module of type 1, defined as one consisting of two polar T-O-T silicate layers with one central illitic interlayer and two, half smectitic interlayers at the outermost surface; the number corresponds to that of central illitic interlayers). M1 units were dominant and isolated or consecutive smectite layers of > two were present in sample 635. Sample 656 consisted mostly of packets of M1 units of 1 to 5 containing M2 to M5 units occasionally. Isolated or consecutive smectite layers of > two were not present in 656. Illite layers occurred almost as M1 units in samples 435, 635 and 656, and the number of M1 units increased with increase in % I. Sample 756 was characterized by the presence of M2 to M10 units accompanied by smectitic interlayers at the external surface and the absence of M1 units and isolated smectite layers. HRTEM data strongly suggest that illitization in a hydrothermal system occurs by precipitation of M1 units for mixed-layer I-S minerals up to 60% I. This does not require the presence of precursor smectite. Illitization of I-S minerals with more than 60% I proceeds by precipitation of various types of Mn(n≥2) units. Illite occurs only as Mn(n≥1) units throughout illitization