Grain boundary-based plasticity mechanisms in nanostructured metals

The Hall-Petch relationship establishes the proportional dependency of a metal’s strength with the inverse of its grain size’s square root. This phenomena, is well understood using dislocation-based plasticity, until the grain size becomes too small. There plastic deformation mechanisms are usually related to grain boundaries (GBs). Previous studies have observed and simulated several plastic deformation mechanisms such as grain rotation, grain sliding and shear-migration coupling (Figure 1). Some models have been proposed to predict shear-migration coupling based on the initial GB misorientations[1], [4]. However, they have not yet been proven experimentally in the case of polycrystals. This study focuses on the shear-migration coupling, a mechanism which has fueled many recent studies in the field of plasticity [1], [2], [3]. To carry it out, we use polycrystals of Aluminum, Copper and Nickel, with ultrafine grains (\u3c1µm). We aim to find experimental evidences of such mechanism and characterize it in order to correlate it with initial grain misorientations, straining rate, chemical distribution, etc. Please click Additional Files below to see the full abstract

Endoscopic mucosal resection with anchoring of the snare tip: multicenter retrospective evaluation of effectiveness and safety

International audienc

Utilization of mechanical power and associations with clinical outcomes in brain injured patients: a secondary analysis of the extubation strategies in neuro-intensive care unit patients and associations with outcome (ENIO) trial

Background: There is insufficient evidence to guide ventilatory targets in acute brain injury (ABI). Recent studies have shown associations between mechanical power (MP) and mortality in critical care populations. We aimed to describe MP in ventilated patients with ABI, and evaluate associations between MP and clinical outcomes. Methods: In this preplanned, secondary analysis of a prospective, multi-center, observational cohort study (ENIO, NCT03400904), we included adult patients with ABI (Glasgow Coma Scale ≤ 12 before intubation) who required mechanical ventilation (MV) ≥ 24 h. Using multivariable log binomial regressions, we separately assessed associations between MP on hospital day (HD)1, HD3, HD7 and clinical outcomes: hospital mortality, need for reintubation, tracheostomy placement, and development of acute respiratory distress syndrome (ARDS). Results: We included 1217 patients (mean age 51.2 years [SD 18.1], 66% male, mean body mass index [BMI] 26.3 [SD 5.18]) hospitalized at 62 intensive care units in 18 countries. Hospital mortality was 11% (n = 139), 44% (n = 536) were extubated by HD7 of which 20% (107/536) required reintubation, 28% (n = 340) underwent tracheostomy placement, and 9% (n = 114) developed ARDS. The median MP on HD1, HD3, and HD7 was 11.9 J/min [IQR 9.2-15.1], 13 J/min [IQR 10-17], and 14 J/min [IQR 11-20], respectively. MP was overall higher in patients with ARDS, especially those with higher ARDS severity. After controlling for same-day pressure of arterial oxygen/fraction of inspired oxygen (P/F ratio), BMI, and neurological severity, MP at HD1, HD3, and HD7 was independently associated with hospital mortality, reintubation and tracheostomy placement. The adjusted relative risk (aRR) was greater at higher MP, and strongest for: mortality on HD1 (compared to the HD1 median MP 11.9 J/min, aRR at 17 J/min was 1.22, 95% CI 1.14-1.30) and HD3 (1.38, 95% CI 1.23-1.53), reintubation on HD1 (1.64; 95% CI 1.57-1.72), and tracheostomy on HD7 (1.53; 95%CI 1.18-1.99). MP was associated with the development of moderate-severe ARDS on HD1 (2.07; 95% CI 1.56-2.78) and HD3 (1.76; 95% CI 1.41-2.22). Conclusions: Exposure to high MP during the first week of MV is associated with poor clinical outcomes in ABI, independent of P/F ratio and neurological severity. Potential benefits of optimizing ventilator settings to limit MP warrant further investigation

Intérêt du séquençage de nouvelle génération dans le suivi et la prise en charge de la pandémie à SARS-CoV-2

SARS-CoV-2, a novel emerging coronavirus, is responsible for the COVID19 pandemic we have been facing for more than three years. Next-generation sequencing (NGS) holds a primordial place in the management of this pandemic. Through an introduction to sequencing by synthesis (Illumina, Inc.) and nanopore sequencing (ONT, Inc.), the most widely used technologies; this bibliographical work aims to summarise the applications of NGS for epidemiological surveillance and clinical management. The genetic characterisation of SARS-CoV-2 combined with evolutionary analysis allowed near real-time monitoring of virus spread. Molecular epidemiology now became an important tool for adapting public health policies in response to the spread of SARS-CoV-2. Large-scale genomic surveillance, with more than 16 million sequences shared, enabled the discovery and characterisation of several genetic variants with mutations that could be responsible for changes in viral pathogenicity and transmissibility. Many of these mutations occurred in the spike protein which led to immune escape with reduced sensitivity to vaccines and monoclonal antibodies used to fight infections. During the overlap period of variants, NGS allowed personalized management of therapeutics employed against SARS-CoV-2, depending on its sensitivity. NGS enables completion of the genome more easily and with greater precision, offering numerous perspectives for characterisation of the other coding regions, which might act as virulence factors.Le SARS-CoV-2, coronavirus humain émergent, est l’agent responsable de la pandémie de COVID-19 que nous traversons depuis plus de 3 ans. Le séquençage de nouvelle génération (NGS) a occupé une place primordiale dans la gestion de cette pandémie. Au travers de la présentation des technologies de séquençage par synthèse (Illumina) et nanopore (ONT), les plus couramment utilisées, ce travail bibliographique a pour objectif de présenter une synthèse des applications du NGS au service du suivi épidémiologique et de la prise en charge clinique. La caractérisation génétique des SARS-CoV-2 associée aux analyses évolutives ont permis un suivi en temps réel de la diffusion du virus. L’épidémiologie moléculaire a occupé une place prépondérante dans l’adaptation des politiques de santé publique, en réponse à la diffusion du SARS-CoV-2. La surveillance génomique à large échelle a permis, avec plus de 16 millions de séquence partagées, de caractériser l’émergence de nombreux variants, dont les mutations sont responsables de changements dans la pathogénicité et la transmissibilité du SARS-CoV-2. Bon nombre des mutations interviennent dans la protéine Spike et ont entrainé une perte de la sensibilité à la vaccination et aux traitements par anticorps monoclonaux largement employée pour lutter contre l’infection. Le NGS a ainsi permis, durant des périodes de chevauchement de ces variants, d’adapter une prise en charge thérapeutique personnalisée en fonction de l’évolution virale. Le NGS permettant l’obtention de génomes complets, avec une très grande fidélité et une importante précision, ouvre de nombreuses perspectives pour la caractérisation des autres régions géniques, pouvant constituer des facteurs de virulence.<br

Continuous Flow Synthesis of Propofol

Herein, we report a continuous flow process for the synthesis of 2,6-diisopropylphenol—also known as Propofol—a short-acting intravenous anesthesia, widely used in intensive care medicine to provide sedation and hypnosis. The synthesis is based on a two-step procedure: a double Friedel–Crafts alkylation followed by a decarboxylation step, both under continuous flow

Fièvre de la vallée du Rift : diagnostic d'une arbovirose peu classique en France métropolitaine, à ne pas méconnaître !

International audienc

Outcomes and Future Directions of Per-Oral Endoscopic Pyloromyotomy

International audienc

Will Endoscopic-Ultrasound-Guided Choledocoduodenostomy with Electrocautery-Enhanced Lumen-Apposing Metal Stent Placement Replace Endoscopic Retrograde Cholangiopancreatography When Treating Distal Malignant Biliary Obstructions?

Malignant distal biliary obstructions are becoming increasingly common, especially in patients with cancers of the pancreatic head, despite progress in medical oncology research. ERCP is the current gold standard for management of such strictures, but the emergence of EC-LAMS has rendered EUS-CDS both safe and efficient. It is a “game changer”; originally intended for ERCP failure, two randomised clinical trials recently proposed EUS-CDS as a first-intent procedure in palliative settings. For resectable diseases, the absence of iatrogenic pancreatitis associated with a lower rate of postsurgical adverse events (compared with ERCP) leads us to believe that EUS-CDS might be used in first-intent as a pre-operative endoscopic biliary drainage

Comptes Rendus Physique

International audienceShear-coupled migration of grain boundaries: the key missing link in the mechanical behavior of small-grained metals? Migration couplée au cisaillement des joints de grains : le chaînon manquant dans le comportement mécanique des métaux à petits grains