Time-resolved torsional relaxation of spider draglines by an optical technique.

International audienceThe sensitivity of the torsional pendulum demonstrates the self-shape-memory effect in different types of spider draglines. Here we report the time-resolved noncovalent bonds recovery in the protein structure. The torsional dynamics of such multilevel structure governed by reversible interactions are described in the frame of a nested model. Measurement of three different relaxation times confirms the existence of three energy storage levels in such two protein spidroin systems. Torsion opens the way to further investigations towards unraveling the tiny torque effects in biological molecules

Relationship between ventilator-associated pneumonia and mortality in COVID-19 patients: a planned ancillary analysis of the coVAPid cohort

Background Patients with SARS-CoV-2 infection are at higher risk for ventilator-associated pneumonia (VAP). No study has evaluated the relationship between VAP and mortality in this population, or compared this relationship between SARS-CoV-2 patients and other populations. The main objective of our study was to determine the relationship between VAP and mortality in SARS-CoV-2 patients. Methods Planned ancillary analysis of a multicenter retrospective European cohort. VAP was diagnosed using clinical, radiological and quantitative microbiological criteria. Univariable and multivariable marginal Cox's regression models, with cause-specific hazard for duration of mechanical ventilation and ICU stay, were used to compare outcomes between study groups. Extubation, and ICU discharge alive were considered as events of interest, and mortality as competing event. Findings Of 1576 included patients, 568 were SARS-CoV-2 pneumonia, 482 influenza pneumonia, and 526 no evidence of viral infection at ICU admission. VAP was associated with significantly higher risk for 28-day mortality in SARS-CoV-2 group (adjusted HR 1.65 (95% CI 1.11-2.46), p = 0.013), but not in influenza (1.74 (0.99-3.06), p = 0.052), or no viral infection groups (1.13 (0.68-1.86), p = 0.63). VAP was associated with significantly longer duration of mechanical ventilation in the SARS-CoV-2 group, but not in the influenza or no viral infection groups. VAP was associated with significantly longer duration of ICU stay in the 3 study groups. No significant difference was found in heterogeneity of outcomes related to VAP between the 3 groups, suggesting that the impact of VAP on mortality was not different between study groups. Interpretation VAP was associated with significantly increased 28-day mortality rate in SARS-CoV-2 patients. However, SARS-CoV-2 pneumonia, as compared to influenza pneumonia or no viral infection, did not significantly modify the relationship between VAP and 28-day mortality

a planned ancillary analysis of the coVAPid cohort

Funding: This study was supported in part by a grant from the French government through the «Programme Investissement d’Avenir» (I-SITE ULNE) managed by the Agence Nationale de la Recherche (coVAPid project). The funders of the study had no role in the study design, data collection, analysis, or interpreta tion, writing of the report, or decision to submit for publication.BACKGROUND: Patients with SARS-CoV-2 infection are at higher risk for ventilator-associated pneumonia (VAP). No study has evaluated the relationship between VAP and mortality in this population, or compared this relationship between SARS-CoV-2 patients and other populations. The main objective of our study was to determine the relationship between VAP and mortality in SARS-CoV-2 patients. METHODS: Planned ancillary analysis of a multicenter retrospective European cohort. VAP was diagnosed using clinical, radiological and quantitative microbiological criteria. Univariable and multivariable marginal Cox's regression models, with cause-specific hazard for duration of mechanical ventilation and ICU stay, were used to compare outcomes between study groups. Extubation, and ICU discharge alive were considered as events of interest, and mortality as competing event. FINDINGS: Of 1576 included patients, 568 were SARS-CoV-2 pneumonia, 482 influenza pneumonia, and 526 no evidence of viral infection at ICU admission. VAP was associated with significantly higher risk for 28-day mortality in SARS-CoV-2 (adjusted HR 1.70 (95% CI 1.16-2.47), p = 0.006), and influenza groups (1.75 (1.03-3.02), p = 0.045), but not in the no viral infection group (1.07 (0.64-1.78), p = 0.79). VAP was associated with significantly longer duration of mechanical ventilation in the SARS-CoV-2 group, but not in the influenza or no viral infection groups. VAP was associated with significantly longer duration of ICU stay in the 3 study groups. No significant difference was found in heterogeneity of outcomes related to VAP between the 3 groups, suggesting that the impact of VAP on mortality was not different between study groups. INTERPRETATION: VAP was associated with significantly increased 28-day mortality rate in SARS-CoV-2 patients. However, SARS-CoV-2 pneumonia, as compared to influenza pneumonia or no viral infection, did not significantly modify the relationship between VAP and 28-day mortality. CLINICAL TRIAL REGISTRATION: The study was registered at ClinicalTrials.gov, number NCT04359693.publishersversionpublishe

Adherence measurements and corrosion resistance in primer/hot-dip galvanized steel systems

This paper focuses on the adherence during ageing of a primer (made of polyester resins crosslinked with melamine) applied onto hot-dip galvanized (HDG) steel for coil coating application and its influence on corrosion protection. A chromium-free surface treatment, composed of fluorotitanic acid, phosphoric acid, manganese phosphate, and vinylphenol was applied on the HDG steel to obtain high corrosion resistance and high adherence of a polyester and melamine primer. The influence of the manganese phosphate on the corrosion and adherence was investigated. To measure the adherence between the metal and the primer, a three-point flexure test was set up. The adherence was then linked with corrosion resistance during ageing, using electrochemical impedance spectroscopy

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Etudes théoriques et expérimentales de mécanismes catalytiques impliquant des complexes de métaux de transition du groupe 10 et de mécanismes réactionnels impliquant des composés du phosphore hybridé sp

PALAISEAU-Polytechnique (914772301) / SudocSudocFranceF

Synthesis of 1-phosphabarrelenes phosphino sulfide substituted palladium(II) complexes: application in the catalyzed Suzuki cross-coupling process and in the allylation of secondary amines.

10 pages Full paperReactivity of 2-phosphine sulfide substituted phosphinines toward alkynes was examined. 2,6-bis(diphenylphosphine sulfide)-3,5-diphenylphosphinine 2 reacts with diphenylacetylene to yield the corresponding 1-phosphabarrelene derivative 3, resulting from the [4 + 2] cycloaddition. Compound 2 and 2-(diphenylphosphine sulfide)-3-methyl-5,6-diphenylphosphinine 1 react with dimethyl acetylenedicarboxylate in a similar fashion to yield the expected 1-phosphabarrelenes 4 and 5, respectively. Ligand 3 acts as a tridentate ligand in its reaction with [Pd(COD)Cl-2] to afford the expected cationic Pd-Cl complex 6. The reaction of [Pd(COD)Cl-2] and [Pd(eta(3)-C3H5)Cl](2) with ligand 5 yielded the corresponding complexes 7 and 8, in which the ligand behaves as a bidentate ligand. Complex 8 was isolated as a cationic derivative after chloride abstraction with AgOTf. DFT calculations, carried out at the B3LYP/6-311+G(d,p) level of theory, have shown that formation of 1phospha-barrelenes is thermodynamically favored when dimethyl acetylenedicarboxylate is used as the alkyne. Complexes 6 and 8 proved to be very active catalysts in the Suzuki-Miyaura reaction, which allows the synthesis of functionalized biphenyl derivatives from the coupling of bromoarenes with phenylboronic acid (TON up to 7 x 106 using complex 8 as catalyst). The cationic complex 8 also catalyzes the coupling between allyl alcohol and secondary amines to afford the corresponding N-allylamines in toluene at 70 degrees C using 2% of the catalyst

Palladium-Catalyzed Deallylation of Allyl Ethers with a Xanthene Phosphole Ligand. Experimental and DFT Mechanistic Studies

International audienceA cationic xanthene phosphole palladium allyl complex efficiently catalyzes the deallylation of allyl ethers into alcohols and the concomitant formation of allyl amines. Parallel experiments and DFT calculations show that acidic catalysis plays a significant role in promoting the cleavage of the C−O bond in a 16 VE complex featuring an allyl ether as η2-ligand

Journées de la Division de Chimie de Coordination de la SFC

3-4 Avril 2006 Laboratoire de Chimie de Coordination du CNR

A joint experimental and theoretical study of the palladium-catalyzed electrophilic allylation of aldehydes

International audiencealladium-catalyzed electrophilic allylation of aldehydes with allylstannanes has been proposed in the literature as a model reaction illustrating the potential of nucleophilic eta(1)-allyl palladium pincer complexes to promote new catalytic processes. This reaction was studied by a joint experimental and theoretical approach. It was shown that pincer palladium complexes featuring a S similar to P similar to S and a S similar to C similar to S tridentate ligand are efficient catalysts for this reaction. The full mechanism of this transformation was studied in detail by means of DFT calculations. Two pathways were explored: the commonly proposed mechanism involving eta(1)-allyl palladium intermediates and a Lewis acid promoted mechanism. Both of these mechanisms were compared to the direct transformation that was shown experimentally to occur under mild conditions. The mechanism involving an eta(1)-allyl palladium intermediate has been discarded on energetic grounds, the nucleophilic attack and the transmetalation step being more energetically demanding than the direct reaction between allyltin and the aldehyde. On the other hand, a mechanism where the palladium acts as a Lewis acid proved to be fully consistent with all experimental and theoretical results. This mechanism involves (L similar to X similar to L)Pd+ species which activate the aldehyde moiety toward nucleophilic attack