Computational Investigation of the Effective Mechanical Behavior for 3D Pre-Buckled Auxetic Lattices

Negative Poisson’s ratio materials, or auxetics, have drawn attention for the past 30 years. The auxetic effect could lead to improved mechanical properties such as acoustic damping, indentation resistance, or crashworthiness. In this work, two 3D auxetic lattices are introduced. Auxeticity is achieved by design through pre-buckling of the lattice struts. The influence of geometrical parameters on the effective elastic properties is investigated using computational homogenization method with periodic boundary conditions. Effective Young’s modulus is 3D mapped to reveal anisotropy and identify spatial orientations of interest. The effective Poisson ratio is computed for various geometric configurations to characterize auxeticity. Finally, the influence of effective elastic properties on energy dissipation under compression is explored for elastoplastic lattices with different loading directions, using finite element simulations. Results suggest that loading 3D auxetic lattices along their stiffest direction maximizes their crashworthiness.ANR-16-CE08-000

Global sequence variation in the histidine-rich proteins 2 and 3 of Plasmodium falciparum: implications for the performance of malaria rapid diagnostic tests

Background. Accurate diagnosis is essential for prompt and appropriate treatment of malaria. While rapid diagnostic tests (RDTs) offer great potential to improve malaria diagnosis, the sensitivity of RDTs has been reported to be highly variable. One possible factor contributing to variable test performance is the diversity of parasite antigens. This is of particular concern for Plasmodium falciparum histidine-rich protein 2 (PfHRP2)-detecting RDTs since PfHRP2 has been reported to be highly variable in isolates of the Asia-Pacific region. Methods. The pfhrp2 exon 2 fragment from 458 isolates of P. falciparum collected from 38 countries was amplified and sequenced. For a subset of 80 isolates, the exon 2 fragment of histidine-rich protein 3 (pfhrp3) was also amplified and sequenced. DNA sequence and statistical analysis of the variation observed in these genes was conducted. The potential impact of the pfhrp2 variation on RDT detection rates was examined by analysing the relationship between sequence characteristics of this gene and the results of the WHO product testing of malaria RDTs: Round 1 (2008), for 34 PfHRP2-detecting RDTs. Results. Sequence analysis revealed extensive variations in the number and arrangement of various repeats encoded by the genes in parasite populations world-wide. However, no statistically robust correlation between gene structure and RDT detection rate for P. falciparum parasites at 200 parasites per microlitre was identified. Conclusions. The results suggest that despite extreme sequence variation, diversity of PfHRP2 does not appear to be a major cause of RDT sensitivity variation

Propriétés mécaniques de treillis auxétiques hybrides

Additive Manufacturing (AM) is an innovative process for producing complex geometry parts for small series or high value-added products. An example of innovative design linked to the possibilities offered by the geometric freedom due to AM are lattice structures which have proved themselves as extremely efficient structures in terms of mechanical properties brought back to their mass, preferable for biomedical implants for example . In this type of application, the structural integrity of the component is a non-negotiable parameter of the specifications. Additive manufacturing of architectured materials creates surfaces and geometrical imperfections that can cause a dramatic decrease of mechanical caracteristics. In order to counteract these undesirable effects, a strategy for the development of hybrid architectured materials is implemented. The addition of a second polymer phase acting as a matrix reinforced by a lattice structure makes it possible to eliminate the surface roughness while delaying the buckling of the constituent beams of the lattice. The project aims to develop a suitable numerical framework for the design and prediction of the behavior of hybrid architectured materials, based on full-field simulations and homogenization on periodic unit cell.Les treillis sont des structures composées d’un réseau de poutres pouvant être périodique et proposant des propriétés mécaniques supérieures ramenées à leur masse lorsque que comparé à un matériau "plein". En particulier, les structures treillis font preuve de capacités de dissipation d’énergie élevées relativement à leur masse, et sont donc candidates pour le remplacement de pièces mécaniques monolithique en usage. Parmi les treillis, les structures à coefficient de Poisson négatif permettraient une dissipation supérieure aux structures conventionnelles. Néanmoins, ces structures sont soumises à des modes de déformation et d’endommagement pouvant nuire à leurs performances.Ces travaux de thèses s’inscrivent dans l’exploration des possibilités visant à améliorer les propriétés mécaniques spécifiques des treillis périodiques, notamment pour la dissipation d’énergie, par une stratégie d’hybridation consistant à remplir le volume vacant des treillis par un matériau de nature différente, permettant de stabiliser la structure. Dans un premier temps, deux nouveaux treillis auxétiques sont proposés, et leurs propriétés élastiques et élasto-plastiques sont étudiées numériquement via une stratégie d’homogénéisation utilisant des conditions aux limites périodiques. L’influence de l’orientation de chargement et des propriétés élastiques sur la dissipation d’énergie est étudiée numériquement.Par la suite, une campagne expérimentale et numérique comparant mécaniquement deux treillis en polymère avec leurs équivalents composites remplis par un élastomère est détaillée. L’analyse des essais de compression permet d’observer une augmentation des propriétés élastiques des composites, ainsi qu’une augmentation des niveaux de contraintes et de la déformation à densification. La densification retardée observée sur les treillis composites permet un plus long plateau de contrainte, plus souhaitable pour des applications en dissipation d’énergie, entrainant une augmentation de l’énergie spécifique dissipée et de l’efficacité d’absorption.Enfin, des treillis métalliques sont réalisés par SLM avant d’être remplis de polyuréthane par moulage. Ces structures hybrides sont étudiées aussi bien expérimentalement que numériquement, via des essais de compression, mais également sous tomographe à rayons X pour observer les déformations internes du treillis. Les résultats suggèrent cependant qu’un fort contraste de propriétés entre les matériaux constitutifs peut atténuer l’accroissement des propriétés mécaniques.Ces travaux confirment que l’hybridation peut être une option efficace pour augmenter les propriétés mécaniques spécifiques des treillis, et notamment l’énergie spécifique dissipée

Patient-specific computer modeling for automated sizing of fenestrated stent-grafts Author names and affiliations

International audienc

Remdesivir for Patients Hospitalized with COVID-19 Severe Pneumonia: A National Cohort Study (Remdeco-19)

International audienceBackground. Given the rapidly evolving pandemic of COVID-19 in 2020, authorities focused on the repurposing of available drugs to develop timely and cost-effective therapeutic strategies. Evidence suggested the potential utility of remdesivir in the framework of an early access program. REMDECO-19 is a multicenter national cohort study assessing the ability of remdesivir to improve the outcome of patients hospitalized with COVID-19. Methods. We conducted a retrospective real-life study that included all patients from the early access program of remdesivir in France. The primary endpoint was the clinical course evolution of critically ill and hospitalized COVID-19 patients treated with remdesivir. Secondary endpoints were the SOFA score evolution within 29 days following the admission and mortality at 29 and 90 days. Results. Eighty-five patients were enrolled in 22 sites from January to April 2020. The median WHO and SOFA scores were respectively reduced by two and six points between days 1 and 29. Improvement in the WHO-CPS and the SOFA score were observed in 83.5% and 79.3% of patients, respectively, from day 10. However, there was no effect of remdesivir on the 90-day survival based on the control cohort for hospitalized COVID-19 patients with invasive ventilation. Conclusions. SOFA score appeared to be an attractive approach to assess remdesivir efficacy and stratify its utilization or not in critically ill patients with COVID-19. This study brings a new clinical benchmark for therapeutic decision making and supports the use of remdesivir for some hospitalized COVID-19 patients

Remdesivir for Patients Hospitalized with COVID-19 Severe Pneumonia: A National Cohort Study (Remdeco-19)

International audienceBackground. Given the rapidly evolving pandemic of COVID-19 in 2020, authorities focused on the repurposing of available drugs to develop timely and cost-effective therapeutic strategies. Evidence suggested the potential utility of remdesivir in the framework of an early access program. REMDECO-19 is a multicenter national cohort study assessing the ability of remdesivir to improve the outcome of patients hospitalized with COVID-19. Methods. We conducted a retrospective real-life study that included all patients from the early access program of remdesivir in France. The primary endpoint was the clinical course evolution of critically ill and hospitalized COVID-19 patients treated with remdesivir. Secondary endpoints were the SOFA score evolution within 29 days following the admission and mortality at 29 and 90 days. Results. Eighty-five patients were enrolled in 22 sites from January to April 2020. The median WHO and SOFA scores were respectively reduced by two and six points between days 1 and 29. Improvement in the WHO-CPS and the SOFA score were observed in 83.5% and 79.3% of patients, respectively, from day 10. However, there was no effect of remdesivir on the 90-day survival based on the control cohort for hospitalized COVID-19 patients with invasive ventilation. Conclusions. SOFA score appeared to be an attractive approach to assess remdesivir efficacy and stratify its utilization or not in critically ill patients with COVID-19. This study brings a new clinical benchmark for therapeutic decision making and supports the use of remdesivir for some hospitalized COVID-19 patients

Remdesivir for Patients Hospitalized with COVID-19 Severe Pneumonia: A National Cohort Study (Remdeco-19)

International audienceBackground. Given the rapidly evolving pandemic of COVID-19 in 2020, authorities focused on the repurposing of available drugs to develop timely and cost-effective therapeutic strategies. Evidence suggested the potential utility of remdesivir in the framework of an early access program. REMDECO-19 is a multicenter national cohort study assessing the ability of remdesivir to improve the outcome of patients hospitalized with COVID-19. Methods. We conducted a retrospective real-life study that included all patients from the early access program of remdesivir in France. The primary endpoint was the clinical course evolution of critically ill and hospitalized COVID-19 patients treated with remdesivir. Secondary endpoints were the SOFA score evolution within 29 days following the admission and mortality at 29 and 90 days. Results. Eighty-five patients were enrolled in 22 sites from January to April 2020. The median WHO and SOFA scores were respectively reduced by two and six points between days 1 and 29. Improvement in the WHO-CPS and the SOFA score were observed in 83.5% and 79.3% of patients, respectively, from day 10. However, there was no effect of remdesivir on the 90-day survival based on the control cohort for hospitalized COVID-19 patients with invasive ventilation. Conclusions. SOFA score appeared to be an attractive approach to assess remdesivir efficacy and stratify its utilization or not in critically ill patients with COVID-19. This study brings a new clinical benchmark for therapeutic decision making and supports the use of remdesivir for some hospitalized COVID-19 patients

Remdesivir for Patients Hospitalized with COVID-19 Severe Pneumonia: A National Cohort Study (Remdeco-19)

International audienceBackground. Given the rapidly evolving pandemic of COVID-19 in 2020, authorities focused on the repurposing of available drugs to develop timely and cost-effective therapeutic strategies. Evidence suggested the potential utility of remdesivir in the framework of an early access program. REMDECO-19 is a multicenter national cohort study assessing the ability of remdesivir to improve the outcome of patients hospitalized with COVID-19. Methods. We conducted a retrospective real-life study that included all patients from the early access program of remdesivir in France. The primary endpoint was the clinical course evolution of critically ill and hospitalized COVID-19 patients treated with remdesivir. Secondary endpoints were the SOFA score evolution within 29 days following the admission and mortality at 29 and 90 days. Results. Eighty-five patients were enrolled in 22 sites from January to April 2020. The median WHO and SOFA scores were respectively reduced by two and six points between days 1 and 29. Improvement in the WHO-CPS and the SOFA score were observed in 83.5% and 79.3% of patients, respectively, from day 10. However, there was no effect of remdesivir on the 90-day survival based on the control cohort for hospitalized COVID-19 patients with invasive ventilation. Conclusions. SOFA score appeared to be an attractive approach to assess remdesivir efficacy and stratify its utilization or not in critically ill patients with COVID-19. This study brings a new clinical benchmark for therapeutic decision making and supports the use of remdesivir for some hospitalized COVID-19 patients