Corrosion sous contrainte intergranulaire du noyau de soudure par FSW de l'alliage Al-Li 2050

Pour réduire le poids des structures aéronautiques, plusieurs voies ont été explorées. Parmi elles, l'utilisation des alliages d'aluminium légers et le remplacement des structures rivetées par des structures soudées par Friction Stir Welding (FSW) sont envisagées. La question de la durée de vie de ces structures préoccupe les industriels. Dans ce cadre, cette étude porte sur la sensibilité à la corrosion sous contrainte intergranulaire (CSC-IG) du noyau de soudure par FSW de l'alliage Al-Cu-Li 2050. Ce matériau est composé de grains équiaxes dont la taille diminue de 17 à 4 m à mesure que l'on s'éloigne de la surface de soudage. Une variation de texture est révélée grâce à des cartographies EBSD formant la microstructure des onion rings . La périodicité de ces onions rings est égale à l'avancée du pion FSW sur un tour (500 m pour notre matériau). Ces hétérogénéités microstructurales entraînent des gradients de champs mécaniques locaux quantifiés par corrélation d'images lors des essais mécaniques. Ces hétérogénéités microstructurales et mécaniques favorisent les phénomènes de corrosion localisée lorsque le matériau est soumis à un environnement agressif. Les effets des contraintes et de la microstructure sur la CSC-IG sont mis en évidence par des essais de corrosion et des essais de corrosion sous contrainte (CSC). Les essais de corrosion montrent une sensibilité du matériau à la piqûration alors que les essais de CSC révèlent l'amorçage de fissures intergranulaires. Les plus grosses fissures s'amorcent préférentiellement à la frontière des onion rings . Un modèle par éléments finis a été développé dans le but de simuler la propagation des fissures intergranulaires sur des agrégats réels générés par des cartographies EBSD.To reduce the aircraft components weight, several solutions were explored. Among them, the using of light aluminum alloys and the substitution of riveting by friction stir welding (FSW) are investigated. Industry is concerned by the question of the life of such structures. For this, this study is focused on intergranular stress corrosion cracking (IGSCC) sensitivity of the 2050 Al-Li-Cu alloy friction stir weld nugget. This material consists of equiaxed grains whose size is decreasing with the distance from the weld surface between 17 m at the top and 4 m at the bottom. The onion rings microstructure is revealed by EBSD cartographies as a texture variation. They appear with a periodicity of 500 m corresponding to the advance per revolution of the tool. Those microstructural heterogeneities cause local mechanical field gradients quantified by digital image correlation measurements during mechanical tests. Those microstructural and mechanical heterogeneities promote localized corrosion when the material is submitted to an aggressive environnement. Microstructure and stress effects on IGSCC are shown by corrosion tests and stress corrosion tests. The first ones show a sensitivity to pitting corrosion and a stress application reveal initiation of intergranular cracks. The biggest ones preferentially initiate at onion rings boundaries. A finite element model was developed in order to simulate intergranular cracks propagation on real aggregates obtained by EBSD cartographies.BORDEAUX1-Bib.electronique (335229901) / SudocSudocFranceF

An exploration of multilinguals’ voice-hearing experiences

Research on multilinguals’ voice-hearing, sometimes termed auditory-verbal hallucinations, is dominated by reports from treating psychiatrists, skewing toward etic over emic approaches. Most also pre-dates developments in both voice-hearing and multilingualism research which highlight the complexity and dynamic nature of both phenomena and shows little cross-fertilisation between the two fields. This paper sits within this gap, presenting results from an in-depth interview study with ten UK-resident multilingual voice-hearers analysed via constructionist reflexive thematic analysis. A high proportion of participants described hearing voices they did not (fully) understand, challenging the dominance of the hypothesis that voice-hearing originates from misattributed inner speech. This set of experiences is presented along a spectrum with a complex array of associated emotions and subtle experiential distinctions. The relationship between language experiences, voices’ languages, and associated emotions was similarly complex and individual: participants described voices both reflecting and distorting or shifting the contexts, domains, interlocutors and feelings associated with their various languages. This has implications for therapeutic and peer support for those who are distressed by their voices, as well as opening up new avenues in voice-hearing phenomenology and aetiology

Mechanical behavior of periodical microstructure induced by friction stir welding on Al–Cu–Li 2050 alloy

Mechanical behavior analysis of the friction stir weld nugget of an aluminum alloy 2050 reveals a major role of the microstructure which varies with the distance to the weld surface. Three types of microstructure heterogeneities are considered namely grain size, precipitation state and textured bands. The grain size and the T1 precipitates density decrease with the distance from the weld surface. The density of T1 precipitates has a first order effect on micro-hardness variations and makes the Hall–Petch rule not valid in this case. Tensile tests combined with strain field identification done by digital image correlation measurements demonstrate the good correlation between textured bands and strain field heterogeneities. Crystal plasticity simulations by finite element method well account for the macroscopic mechanical behavior as well as strain field in textured bands

Formation continue et parcours professionnels : entre aspirations des salariés et contexte de l’entreprise

« Levier déterminant de la compétitivité des entreprises », « élément structurant de la sécurisation des parcours des personnes », instrument de « liberté de choisir son avenir professionnel », la formation continue est érigée en solution privilégiée pour le marché du travail. Les enjeux de la crise ouverte par la pandémie du Covid 19 pourraient bien aussi se décliner en termes de formation continue, notamment autour des besoins de reconversion. Pourtant, concilier les besoins des entreprises avec les aspirations professionnelles des personnes ne va pas de soi. Les travaux présentés dans cet ouvrage collectif, réalisés dans le cadre du premier groupe d’exploitation du Dispositif d’enquêtes couplées sur les formations et les itinéraires des salariés (Defis), éclairent, chacun à sa façon et sous des angles variés, les multiples enjeux de la formation continue. Ils questionnent la formation des salariés en lien avec leurs aspirations et les parcours professionnels. Ils tentent également de mieux comprendre la manière dont les différentes configurations productives et le contexte des entreprises peuvent influencer leurs pratiques de formation, de recrutement et autres modes d’acquisition des compétences. Conçu comme un lieu d’échanges et de dialogue pluridisciplinaire autour des données Defis, le groupe d’exploitation a réuni des chercheurs issus du Céreq, des universités ou laboratoires CNRS et autres organismes publics. Leurs appartenances disciplinaires sont variées (économie, sociologie, gestion, sciences de l’éducation) et les méthodologies mobilisées associent parfois une approche qualitative à l’analyse des données quantitatives

The reg4 Gene, Amplified in the Early Stages of Pancreatic Cancer Development, Is a Promising Therapeutic Target

BACKGROUND: The aim of our work was to identify the genes specifically altered in pancreatic adenocarcinoma and especially those that are altered early in cancer development. METHODOLOGY/PRINCIPAL FINDINGS: Gene copy number was systematically assessed with an ultra-high resolution CGH oligonucleotide microarray in DNA from samples of pancreatic cancer. Several new cancer-associated variations were observed. In this work we focused on one of them, involving the reg4 gene. Gene copy number gain of the reg4 gene was confirmed by qPCR in 14 cancer samples. It was also found with increased copy number in most PanIN3 samples. The relationship betweena gain in reg4 gene copy number and cancer development was investigated on the human pancreatic cancer cell line Mia-PaCa2 xenografted under the skin of nude mice. When cells were transfected with a vector allowing reg4 expression, they generated tumors almost twice larger in size. In addition, these tumors were more resistant to gemcitabine treatment than control tumors. Interestingly, weekly intraperitoneal administration of a monoclonal antibody to reg4 halved the size of tumors generated by Mia-PaCa2 cells, suggesting that the antibody interfered with a paracrine/autocrine mechanism involving reg4 and stimulating cancer progression. The addition of gemcitabine resulted in further reduction, tumors becoming 5 times smaller than control. Exposure to reg4 antibody resulted in a significant decrease in intra-tumor levels of pAkt, Bcl-xL, Bcl-2, survivin and cyclin D1. CONCLUSIONS/SIGNIFICANCE: It was concluded that adjuvant therapies targeting reg4 could improve the standard treatment of pancreatic cancer with gemcitabine

Puerarin Suppresses Invasion and Vascularization of Endometriosis Tissue Stimulated by 17β-Estradiol

BACKGROUND: Puerarin, a phytoestrogen with a weak estrogenic effect, binds to estrogen receptors, thereby competing with 17β-estradiol (E2) and producing an anti-estrogenic effect. This study was to investigate whether puerarin could suppress the invasion and vascularization of E2-stimulated endometriotic tissue. METHODOLOGY/PRINCIPAL FINDINGS: The endometriotic stromal cells (ESCs) were successfully established and their invasive ability under different treatments was assessed through a Transwell Assay. Simultaneously, matrix metallopeptidase 9 (MMP-9) and tissue inhibitor of metalloproteinase 1 (TIMP-1) were detected by western blotting. Vascularization of endometriotic tissues was observed by chicken chorioallantoic membrane (CAM) assay. The staining of MMP-9, intercellular adhesion molecule 1 (ICAM-1), TIMP-1, and vascular endothelial growth factor (VEGF) in grafted endometriotic tissues was examined using immunohistochemistry analysis. The purity of ESCs in isolated cells was >95%, as determined by the fluoroimmunoassay of vimentin. E2 (10(-8) mol/L) promoted the invasiveness of ESCs by increasing MMP-9 accumulation and decreasing TIMP-1 accumulation. Interestingly, puerarin (10(-9) mol/L) significantly reversed these effects (P<0.01). The CAM assay indicated that puerarin (10(-9) mol/L) also inhibited the angiopoiesis of endometriotic tissue stimulated by the E2 (10(-8) mol/L) treatment (P<0.05). Accordingly, immunohistochemistry showed that the accumulation of MMP-9, ICAM-1, and VEGF was reduced whereas that of TIMP-1 increased in the combination treatment group compared with the E2 treatment group. CONCLUSIONS/SIGNIFICANCE: This study demonstrated that puerarin could suppress the tissue invasion by ESCs and the vascularization of ectopic endometrial tissues stimulated by E2, suggesting that puerarin may be a potential drug for the treatment of endometriosis

Endovascular Therapy in the Extended Time Window for Large Vessel Occlusion in Patients With Pre-Stroke Disability.

BACKGROUND AND PURPOSE We compared the outcomes of endovascular therapy (EVT) in an extended time window in patients with large-vessel occlusion (LVO) between patients with and without pre-stroke disability. METHODS In this prespecified analysis of the multinational CT for Late Endovascular Reperfusion study (66 participating sites, 10 countries between 2014 and 2022), we analyzed data from patients with acute ischemic stroke with a pre-stroke modified Rankin Scale (mRS) score of 0-4 and LVO who underwent EVT 6-24 hours from the time last seen well. The primary outcome was the composite of functional independence (FI; mRS score 0-2) or return to the pre-stroke mRS score (return of Rankin, RoR) at 90 days. Outcomes were compared between patients with pre-stroke disability (pre-stroke mRS score 2-4) and those without (mRS score 0-1). RESULTS A total of 2,231 patients (median age, 72 years; median National Institutes of Health Stroke Scale score, 16) were included in the present analysis. Of these, 564 (25%) had pre-stroke disability. The primary outcome (FI or RoR) was observed in 30.7% of patients with pre-stroke disability (FI, 16.5%; RoR, 30.7%) compared to 44.1% of patients without (FI, 44.1%; RoR, 13.0%) (P<0.001). In multivariable logistic regression analysis with inverse probability of treatment weighting, pre-stroke disability was not associated with significantly lower odds of achieving FI or RoR (adjusted odds ratio 0.73, 95% confidence interval 0.43-1.25). Symptomatic intracranial hemorrhage occurred in 6.3% of both groups (P=0.995). CONCLUSION A considerable proportion of patients with late-presenting LVO and pre-stroke disability regained pre-stroke mRS scores after EVT. EVT may be appropriate for patients with pre-stroke disability presenting in the extended time window

The origins and spread of domestic horses from the Western Eurasian steppes

This is the final version. Available on open access from Nature Research via the DOI in this recordData availability: All collapsed and paired-end sequence data for samples sequenced in this study are available in compressed fastq format through the European Nucleotide Archive under accession number PRJEB44430, together with rescaled and trimmed bam sequence alignments against both the nuclear and mitochondrial horse reference genomes. Previously published ancient data used in this study are available under accession numbers PRJEB7537, PRJEB10098, PRJEB10854, PRJEB22390 and PRJEB31613, and detailed in Supplementary Table 1. The genomes of ten modern horses, publicly available, were also accessed as indicated in their corresponding original publications57,61,85-87.NOTE: see the published version available via the DOI in this record for the full list of authorsDomestication of horses fundamentally transformed long-range mobility and warfare. However, modern domesticated breeds do not descend from the earliest domestic horse lineage associated with archaeological evidence of bridling, milking and corralling at Botai, Central Asia around 3500 BC. Other longstanding candidate regions for horse domestication, such as Iberia and Anatolia, have also recently been challenged. Thus, the genetic, geographic and temporal origins of modern domestic horses have remained unknown. Here we pinpoint the Western Eurasian steppes, especially the lower Volga-Don region, as the homeland of modern domestic horses. Furthermore, we map the population changes accompanying domestication from 273 ancient horse genomes. This reveals that modern domestic horses ultimately replaced almost all other local populations as they expanded rapidly across Eurasia from about 2000 BC, synchronously with equestrian material culture, including Sintashta spoke-wheeled chariots. We find that equestrianism involved strong selection for critical locomotor and behavioural adaptations at the GSDMC and ZFPM1 genes. Our results reject the commonly held association between horseback riding and the massive expansion of Yamnaya steppe pastoralists into Europe around 3000 BC driving the spread of Indo-European languages. This contrasts with the scenario in Asia where Indo-Iranian languages, chariots and horses spread together, following the early second millennium BC Sintashta culture