Effect of the aggressive environment on the damage of a glass polyester composite developed by hand layup process

This work treats the behavior of a glass fibre/unsaturated polyester (UP) composite with structural deffects subjected to the attack of two corrosive solutions: H2SO4 and NaOH. The gravimetric analysis, the uptake mass of the resin, and the interfaces in the composite are established according to the proportion of the matrix/composite. The obtained results showed that, in the acidic solution, the glass fibre and the fibre/matrix interface absorption share is more significant than the alkaline solution. While the Fourier transform infrared analysis (FT-IR) of the UP resin revealed the presence of chemical degradation phenomenon (hydrolysis), the fibre corrosion was characterized by the atomic absorption analysis (AAS). The fibres/matrix interfaces degradation was confrmed by microscopic observations (SEM). The difusion kinetics of the both acid and alkaline solutions and chemical and mechanical degradation are afected by the presence of the pores in elaborated materia

Comparative evaluation of surface quality, tool wear, and specific cutting energy for wiper and conventional carbide inserts in hard turning of aisi 4340 alloy steel

This paper presents an experimental study into the comparative response of wiper and round-nose conventional carbide inserts coated with TiCN + AL$_{2}$O$_{3}$ + TiN when turning an AISI 4340 steel alloy. The optimal process parameters, as identified by pre-experiments, were used for both types of inserts to determine the machined surface quality, tool wear, and specific cutting energy for different cutting lengths. The wiper inserts provided a substantial improvement in the attainable surface quality compared with the results obtained using conventional inserts under optimal cutting conditions for the entire range of the machined lengths. In addition, the conventional inserts showed a dramatic increase in roughness with an increased length of the cut, while the wiper inserts showed only a minor increase for the same length of cut. A scanning electron microscope was used to examine the wear for both types of inserts. Conventional inserts showed higher trends for both the average and maximum flank wear with cutting length compared to the wiper inserts, except for lengths of 200–400 mm, where conventional inserts showed less average flank wear. A higher accumulation of deposited chips was observed on the flank face of the wiper inserts than the conventional inserts. The experimental results demonstrated that edge chipping was the chief tool wear mechanism on the rake face for both types of insert, with more edge chipping observed in the case of the conventional inserts than the wiper inserts, with negligible evidence of crater wear in either case. The wiper inserts were shown to have a higher specific cutting energy than those detected with conventional inserts. This was attributed to (i) the irregular nose feature of the wiper inserts differing from the simpler round nose geometry of the conventional inserts and (ii) a higher tendency of chip accumulation on the wiper inserts

Effects of a high-dose 24-h infusion of tranexamic acid on death and thromboembolic events in patients with acute gastrointestinal bleeding (HALT-IT): an international randomised, double-blind, placebo-controlled trial

Background: Tranexamic acid reduces surgical bleeding and reduces death due to bleeding in patients with trauma. Meta-analyses of small trials show that tranexamic acid might decrease deaths from gastrointestinal bleeding. We aimed to assess the effects of tranexamic acid in patients with gastrointestinal bleeding. Methods: We did an international, multicentre, randomised, placebo-controlled trial in 164 hospitals in 15 countries. Patients were enrolled if the responsible clinician was uncertain whether to use tranexamic acid, were aged above the minimum age considered an adult in their country (either aged 16 years and older or aged 18 years and older), and had significant (defined as at risk of bleeding to death) upper or lower gastrointestinal bleeding. Patients were randomly assigned by selection of a numbered treatment pack from a box containing eight packs that were identical apart from the pack number. Patients received either a loading dose of 1 g tranexamic acid, which was added to 100 mL infusion bag of 0·9% sodium chloride and infused by slow intravenous injection over 10 min, followed by a maintenance dose of 3 g tranexamic acid added to 1 L of any isotonic intravenous solution and infused at 125 mg/h for 24 h, or placebo (sodium chloride 0·9%). Patients, caregivers, and those assessing outcomes were masked to allocation. The primary outcome was death due to bleeding within 5 days of randomisation; analysis excluded patients who received neither dose of the allocated treatment and those for whom outcome data on death were unavailable. This trial was registered with Current Controlled Trials, ISRCTN11225767, and ClinicalTrials.gov, NCT01658124. Findings: Between July 4, 2013, and June 21, 2019, we randomly allocated 12 009 patients to receive tranexamic acid (5994, 49·9%) or matching placebo (6015, 50·1%), of whom 11 952 (99·5%) received the first dose of the allocated treatment. Death due to bleeding within 5 days of randomisation occurred in 222 (4%) of 5956 patients in the tranexamic acid group and in 226 (4%) of 5981 patients in the placebo group (risk ratio [RR] 0·99, 95% CI 0·82–1·18). Arterial thromboembolic events (myocardial infarction or stroke) were similar in the tranexamic acid group and placebo group (42 [0·7%] of 5952 vs 46 [0·8%] of 5977; 0·92; 0·60 to 1·39). Venous thromboembolic events (deep vein thrombosis or pulmonary embolism) were higher in tranexamic acid group than in the placebo group (48 [0·8%] of 5952 vs 26 [0·4%] of 5977; RR 1·85; 95% CI 1·15 to 2·98). Interpretation: We found that tranexamic acid did not reduce death from gastrointestinal bleeding. On the basis of our results, tranexamic acid should not be used for the treatment of gastrointestinal bleeding outside the context of a randomised trial

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Effect of temperature and initiator on glass fibre/unsaturated polyester composite : cross-linking, mechanical properties

The influence of temperature (20–60°C) and initiator ratio (1–3%) on the cross- linking and mechanical properties of the matrix resin and of gla ss fibre/unsaturated polyester composite; prepared by hand lay-up process and us ed in marine structures, is studied. Reactivity tests have shown that the effect of temperature in crease is similar to that of initiator ratio. They increase reaction rate and reduce the gelation tim e and exothermic peak. Conversely, the Fourier transform infrared spectroscopy analyses have sh own that the final conversions of styrene and polyester vinyl groups are almost co mplete, and that whatever the chosen operating conditions. Tensile and bending tests have shown that the m echanical properties (Elastic modulus, tensile strength...) are optimal for the samples operated at 40°C with 1% of initiator and those operated at 20°C with 2% of initiato

Effect of the Aggressive Environment on the Damage of a Glass Polyester Composite Developed by Hand Layup Process

This work treats the behavior of a glass fibre/unsaturated polyester (UP) composite with structural defects subjected to the attack of two corrosive solutions: H2SO4 and NaOH. The gravimetric analysis, the uptake mass of the resin, and the interfaces in the composite are established according to the proportion of the matrix/composite. The obtained results showed that, in the acidic solution, the glass fibre and the fibre/matrix interface absorption share is more significant than the alkaline solution. While the Fourier transform infrared analysis (FT-IR) of the UP resin revealed the presence of chemical degradation phenomenon (hydrolysis), the fibre corrosion was characterized by the atomic absorption analysis (AAS). The fibres/matrix interfaces degradation was confirmed by microscopic observations (SEM). The diffusion kinetics of the both acid and alkaline solutions and chemical and mechanical degradation are affected by the presence of the pores in elaborated material

Etude expérimentale des instabilités thermiques dans un béton à hautes performances

Résumé : L'étude proposée porte sur la mise en évidence des instabilités thermiques lors de la chauffe d'une paroi de Béton à Hautes Performances (BHP) en vue de leur modélisation par des lois de comportement d'endommagement. Le béton étudié est caractérisé par un rapport E/C de 0,25 et une teneur en fumée de silice de 10%. Les essais ont été effectués sur une installation constituée d'un brûleur à plusieurs ouvreaux, afin d'uniformiser la température sur la paroi, coiffé par un four. Les éprouvettes constituées de dalles carrées de 25 cm de côté et de 10 cm d'épaisseur sont chauffées sur l'une de leurs grandes faces en suivant la courbe standard de température ISO 834 de l'Eurocode 2. Elles sont munies de thermocouples placés pendant la confection de l'éprouvette et disposés à différentes distances de la face chauffée destinés à mesurer la variation de température dans l'épaisseur. Pour certaines d'entre elles, des tiges creuses noyées dans le béton et reliées à un capteur de pression permettent de mesurer la variation de pression en certains points au cours des essais. Les premiers essais, réalisés avec une première version du four remplissant partiellement le cahier des charges, ont permis toutefois de valider la capacité du brûleur à produire la puissance nécessaire pour suivre les courbes de température ISO 834 et HCM de l'Eurocode 2. Ils ont aussi permis d'optimiser les procédures d'implantation des thermocouples dans le béton lors de la confection des éprouvettes. Ils ont enfin permis au niveau de la physique de mettre en évidence la sensibilité du béton étudié aux instabilités thermiques car le phénomène d'écaillage et même d'explosion a été observé à chacun des essais. Les résultats de ces essais sont disponibles et prêts à être présentés. Nous travaillons actuellement à la finalisation de la version complète du four garantissant qu'au cours de l'essai les conditions aux limites appliquées à l'éprouvette soient conformes à celles imposées dans la modélisation numérique. En plus de la mesure de température réalisée avec la première version du four, il sera possible avec la version finalisée de faire des mesures de pression dans le béton et de réaliser un film vidéo de la face chauffée de l'éprouvette en cours d'essai. Ainsi, les résultats de mesure de température et de pression de vapeur en certains points seront analysés et corrélés avec les observations expérimentales directes et indirectes : occurrence des éclats, dimensions des éclats, fissuration et microfissuration, analyse des images vidéo. Cette étude permettra d'améliorer la compréhension des phénomènes générant les instabilités thermiques dans le béton par la réalisation d'un nombre d'essais représentatif d'un point de vue statistique. Elle permettra aussi de fournir des données expérimentales sur le champ thermique afin de caler les calculs de champ thermique issus de la modélisation numérique, préalable indispensable pour modéliser correctement le comportement d'endommagement du béton au cours de l'essai. Mots-clés : Béton à haute performance, courbe de température ISO 834, écaillage, température, pression de vapeur. Bibliographie : [1] W.Z. Zheng, X.M. Hou, D.S. Shi, M.X. Xu. 2010. Experimental study on concrete spalling in prestressed slabs subjected to fire. Fire Safety Journal 45 (2010) 283-297. [2] K.D. Hertz, L.S. Sorensen. 2005. Test method for spalling of fire exposed concrete. Fire Safety Journal 40 (2005) 466-476. [3] Pierre Kalifa, Gregoire Chene, Christophe Galle. 2001. High-temperature behavior of HPC with polypropylene fibres: From spalling to microstructure. Cement and Concrete Research 31 (2001) 1487-1499

Comparative Evaluation of Surface Quality, Tool Wear, and Specific Cutting Energy for Wiper and Conventional Carbide Inserts in Hard Turning of AISI 4340 Alloy Steel

This paper presents an experimental study into the comparative response of wiper and round-nose conventional carbide inserts coated with TiCN + AL2O3 + TiN when turning an AISI 4340 steel alloy. The optimal process parameters, as identified by pre-experiments, were used for both types of inserts to determine the machined surface quality, tool wear, and specific cutting energy for different cutting lengths. The wiper inserts provided a substantial improvement in the attainable surface quality compared with the results obtained using conventional inserts under optimal cutting conditions for the entire range of the machined lengths. In addition, the conventional inserts showed a dramatic increase in roughness with an increased length of the cut, while the wiper inserts showed only a minor increase for the same length of cut. A scanning electron microscope was used to examine the wear for both types of inserts. Conventional inserts showed higher trends for both the average and maximum flank wear with cutting length compared to the wiper inserts, except for lengths of 200–400 mm, where conventional inserts showed less average flank wear. A higher accumulation of deposited chips was observed on the flank face of the wiper inserts than the conventional inserts. The experimental results demonstrated that edge chipping was the chief tool wear mechanism on the rake face for both types of insert, with more edge chipping observed in the case of the conventional inserts than the wiper inserts, with negligible evidence of crater wear in either case. The wiper inserts were shown to have a higher specific cutting energy than those detected with conventional inserts. This was attributed to (i) the irregular nose feature of the wiper inserts differing from the simpler round nose geometry of the conventional inserts and (ii) a higher tendency of chip accumulation on the wiper inserts

e-Health: A promising solution for optimizing management of chronic diseases. Example of the national e-Health project E-care based on an e-platform in the context of chronic heart failure

International audienceMonitoring patients with heart failure by using telemedicine systems is a potentialmeans for optimizing the management of these patients and to facilitate the job of health care professionals. We report the experience of the deployment of such a monitoring platform,through the E-care project.Methods. — The national e-heath project E-care has developed an ‘‘intelligent’’ communicativeplatform enabling the monitoring of patients with NYHA stages III and IV heart failure using non-invasive sensors. This project has been deployed since October 2013 in the Strasbourg UniversityHospital (in Strasbourg, France).Results. — To date, more than 180 patients have been included. The patient profile includedwas: elderly patient, with several chronic diseases (>90%), chronic heart failure in more than60% of cases, total loss of autonomy in 25%. The E-care system operated perfectly and the exper-imental phase enabled us to validate the technological choices. A qualitative survey helped topositively assess the system’s ergonomics. A preliminary analysis of the relevance of alerts withour inference engine design resulted in no malfunction.Conclusion. — Preliminary results following the deployment of E-care system in hospitals appearto show that this platform will assist health care professionals, especially patient nurse ordoctor, by providing an automated processing of these sensors’ transmitted data in order toearly detect and report signs of cardiac impairment.Contexte. —Le suivi des patients atteints d’insuffisance cardiaque en utilisant des systèmes de télémédecine est un moyen potentiel pour optimiser la prise en charge de ces patients et faciliter le travail des professionnels des soins de santé. Nous rapportons ici l’expérience du déploiement d’un tel système de suivi des patients à travers le projet E-care.Méthodes. —Le projet national de télémédecine E-care a développé une plate-forme communicante et « intelligente » permettant le suivi des patients insuffisants cardiaques en stades III et IV de la NYHA en utilisant des capteurs non invasifs. Ce projet a été déployé à partir d’octobre 2013 aux hôpitaux universitaires de Strasbourg.Résultats. — À ce jour, plus de 180 patients ont été inclus. Ces patients sont âgés, poly-pathologiques dans plus de 90 % des cas, présentant une insuffisance cardiaque dans plus de60 % des cas, et une perte d’autonomie dans 25 %. Cette expérimentation a permis de valider les choix technologiques, les outils et les solutions développées et adoptées pour le suivi des insuffisants cardiaques. Une enquête qualitative réalisée auprès des professionnels de santé a évalué positivement l’ergonomie du système. Une analyse préliminaire de la pertinence des alertes avec le moteur d’inférence n’a pas montré de dysfonctionnement du système.Conclusion. — Les résultats préliminaires montrent que la plate-forme E-care devrait être susceptible d’aider les professionnels de soins de santé, en particulier infirmier, patient ou le médecin, en fournissant un traitement automatisé des données transmises par les capteurs afin de détecter et de signaler de fac¸on précoce des symptômes d’insuffisance cardiaque

Expérimentation d’une plateforme de détection automatisée des situations à risque de décompensation cardiaque (plateforme E-care) dans une unité de médecine interne

International audienceIntroduction. – La télémédecine est susceptible d’apporter une aide à la prise en charge des patients souf-frant d’insuffisance cardiaque et d’éviter des urgences vitales. Dans ce cadre, nous avons expérimenté dansune unité de médecine interne une e-plateforme E-care dédiée à la détection automatisée et intelligentedes situations à risque de décompensation cardiaque.Méthodes. – La plateforme E-care repose sur des capteurs médicaux (pression artérielle, fréquence car-diaque, O2, poids), communicants (Bluetooth), permettant de remonter, en temps réel, à un systèmeintelligent des informations physiologiques et sur une analyse de l’ontologie médicale, ce qui aboutit infine à la génération d’alertes. Après une phase de mise au point (proof of concept), la plateforme E-care aété déployée et testée par les professionnels de santé et les patients dans une unité de médecine internede 20 lits, ouverte sur les urgences aux hôpitaux universitaires de Strasbourg.Résultats. – Cent quatre-vingts patients ont été inclus et 1500 mesures ont été réalisées. Le profil depatients inclus dans cette expérimentation était un patient âgé, poly-pathologique dans plus de 90 %des cas, avec une perte d’autonomie dans 25 %. Les professionnels de santé utilisaient la plateformeE-care au quotidien à leur grande satisfaction. Cette expérimentation permettait de valider les choixtechnologiques, de consolider le système et de tester la robustesse de la plateforme E-care. La collecte encontinu nous a permis d’avoir le nombre critique de patients pour analyser plus finement la pertinence desalertes en rapport avec des décompensations cardiaques. Une analyse préliminaire montrait la pertinencedes alertes générées.Conclusion. – Les résultats préliminaires suite au déploiement de la plateforme E-care en milieu hospitaliersemblent montrer la pertinence des choix technologiques, des outils et des solutions développées etadoptées. Ce système de télémédecine permet de fac¸ on automatique, non intrusive, de générer des alertesen rapport avec la détection de situations à risque de décompensation cardiaque, étant in fine susceptiblede prévenir le recours à l’hospitalisation. Un déploiement à domicile est actuellement en cours