New bonded assembly configuration for dynamic mechanical analysis of adhesives

A new sample configuration has been developed in order to study molecular mobility of an adhesive in a bonded assembly configuration by dynamic mechanical analysis. The torsional rectangular mode is used to provide a shear solicitation all along the adherend/adhesive interface. The initial mechanical properties of each assembly's constituent are first investigated as reference. The modulus of aluminum foils used as substrates exhibits a classic elastic component and a slight viscous part due to microstructural changes or stress relaxation. Four relaxation modes are highlighted and identified for epoxy adhesive tested as a bulk material. Its viscoelastic behavior is compared to the one of adhesive tested in assembly configuration. The relaxation modes of the adhesive remain visible in spite of the sample stiffening by aluminum foils. Relaxation modes comparison shows that the temperature of loss modulus associated with the mechanical manifestation of glass transition slightly increases for the assembly configuration. Energy losses during this relaxation are much higher in the assembly configuration. Influence of rigid aluminum substrates is discussed in terms of the adhesively bonded joint solicitation mode

Enthalpy relaxation phenomena of epoxy adhesive in operational configuration: Thermal, mechanical and dielectric analyses

Thermal cycling in space environment can cause physical aging of polymers used in structural adhesive bonded joint. Later, they can initiate failure. A methodology to follow physical aging effects on their thermal, mechanical and dielectric properties is applied to a commercial epoxy adhesive. The analytic description, using Tool, Narayanaswamy and Moynihan model gives a good description of the enthalpy relaxation. It is completed by a phenomenological analysis of the evolution of the adhesive thermal transitions, mechanical properties and molecular mobility. Testedsamples with bondedassembly are representative ofin service configurations. The influence of physical aging on the adhesive and the associated bonded assemblies is analyzed

Gender and class in Britain and France

This article examines the treatment of women's oppression in feminist theory, focusing on the engagement of second wave feminists with the concept of class and its relation to gender. This examination is carried out with reference to British and French feminisms, identifying the main trends and shifts that have developed over the last 35 years and noting that while these are undoubtedly influenced by a particular national context they are also shaped by increasing European integration and social, political and cultural exchanges at a global level. The authors find evidence of a number of similarities in the questions that feminist theorists have asked in Britain and France but also demonstrate that there are significant differences. They conclude that areas of convergent theoretical interests will extend along with cross-border flows of peoples and information

Hyperoxemia and excess oxygen use in early acute respiratory distress syndrome : Insights from the LUNG SAFE study

Publisher Copyright: © 2020 The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Background: Concerns exist regarding the prevalence and impact of unnecessary oxygen use in patients with acute respiratory distress syndrome (ARDS). We examined this issue in patients with ARDS enrolled in the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE (LUNG SAFE) study. Methods: In this secondary analysis of the LUNG SAFE study, we wished to determine the prevalence and the outcomes associated with hyperoxemia on day 1, sustained hyperoxemia, and excessive oxygen use in patients with early ARDS. Patients who fulfilled criteria of ARDS on day 1 and day 2 of acute hypoxemic respiratory failure were categorized based on the presence of hyperoxemia (PaO2 > 100 mmHg) on day 1, sustained (i.e., present on day 1 and day 2) hyperoxemia, or excessive oxygen use (FIO2 ≥ 0.60 during hyperoxemia). Results: Of 2005 patients that met the inclusion criteria, 131 (6.5%) were hypoxemic (PaO2 < 55 mmHg), 607 (30%) had hyperoxemia on day 1, and 250 (12%) had sustained hyperoxemia. Excess FIO2 use occurred in 400 (66%) out of 607 patients with hyperoxemia. Excess FIO2 use decreased from day 1 to day 2 of ARDS, with most hyperoxemic patients on day 2 receiving relatively low FIO2. Multivariate analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FIO2 use and adverse clinical outcomes. Mortality was 42% in patients with excess FIO2 use, compared to 39% in a propensity-matched sample of normoxemic (PaO2 55-100 mmHg) patients (P = 0.47). Conclusions: Hyperoxemia and excess oxygen use are both prevalent in early ARDS but are most often non-sustained. No relationship was found between hyperoxemia or excessive oxygen use and patient outcome in this cohort. Trial registration: LUNG-SAFE is registered with ClinicalTrials.gov, NCT02010073publishersversionPeer reviewe

Expression of the mutant Arabidopsis thaliana acetolactate synthase gene confers chlorsulfuron resistance to transgenic poplar plants

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Environmental ageing of aerospace epoxy adhesive in bonded assembly configuration

International audienceAerospace epoxy adhesive has been subjected to various environmental ageing processes. A comparative study is performed between ageing under vacuum and atmospheric pressure for various ageing temperatures. The macroscopic behaviour of the assemblies is investigated by single lap shear test. Glass transition temperature of the bulk adhesive is followed by differential scanning calorimetry.Molecular mobility of the adhesive in service configuration is studied by dynamic dielectric spectroscopy. No significant difference is noticed due to an ageing under vacuum. A comparison between test results after each isotherm ageing highlights the temperature influence. For ageing of adhesive in a vitreous state, the crosslink density increases. For ageing of adhesive in a rubbery state, a severe decrease of glass transition is observed. The influence of additives and physical ageing is null. Thisplasticisation effect might be associated with the homogenisation of the structure of epoxy due to the molecular mobility of loose chains

Immunocompromised patients with acute respiratory distress syndrome: Secondary analysis of the LUNG SAFE database

Background: The aim of this study was to describe data on epidemiology, ventilatory management, and outcome of acute respiratory distress syndrome (ARDS) in immunocompromised patients. Methods: We performed a post hoc analysis on the cohort of immunocompromised patients enrolled in the Large Observational Study to Understand the Global Impact of Severe Acute Respiratory Failure (LUNG SAFE) study. The LUNG SAFE study was an international, prospective study including hypoxemic patients in 459 ICUs from 50 countries across 5 continents. Results: Of 2813 patients with ARDS, 584 (20.8%) were immunocompromised, 38.9% of whom had an unspecified cause. Pneumonia, nonpulmonary sepsis, and noncardiogenic shock were their most common risk factors for ARDS. Hospital mortality was higher in immunocompromised than in immunocompetent patients (52.4% vs 36.2%; p &lt; 0.0001), despite similar severity of ARDS. Decisions regarding limiting life-sustaining measures were significantly more frequent in immunocompromised patients (27.1% vs 18.6%; p &lt; 0.0001). Use of noninvasive ventilation (NIV) as first-line treatment was higher in immunocompromised patients (20.9% vs 15.9%; p = 0.0048), and immunodeficiency remained independently associated with the use of NIV after adjustment for confounders. Forty-eight percent of the patients treated with NIV were intubated, and their mortality was not different from that of the patients invasively ventilated ab initio. Conclusions: Immunosuppression is frequent in patients with ARDS, and infections are the main risk factors for ARDS in these immunocompromised patients. Their management differs from that of immunocompetent patients, particularly the greater use of NIV as first-line ventilation strategy. Compared with immunocompetent subjects, they have higher mortality regardless of ARDS severity as well as a higher frequency of limitation of life-sustaining measures. Nonetheless, nearly half of these patients survive to hospital discharge. Trial registration: ClinicalTrials.gov, NCT02010073. Registered on 12 December 2013

Psychiatric symptoms and mortality in older adults with major psychiatric disorders: results from a multicenter study

International audienc

Mechanical ventilation in patients with cardiogenic pulmonary edema: a sub-analysis of the LUNG SAFE study

International audienceBackground: Patients with acute respiratory failure caused by cardiogenic pulmonary edema (CPE) may require mechanical ventilation that can cause further lung damage. Our aim was to determine the impact of ventilatory settings on CPE mortality. Methods: Patients from the LUNG SAFE cohort, a multicenter prospective cohort study of patients undergoing mechanical ventilation, were studied. Relationships between ventilatory parameters and outcomes (ICU discharge/ hospital mortality) were assessed using latent mixture analysis and a marginal structural model. Results: From 4499 patients, 391 meeting CPE criteria (median age 70 [interquartile range 59-78], 40% female) were included. ICU and hospital mortality were 34% and 40%, respectively. ICU survivors were younger (67 [57-77] vs 74 [64-80] years, p < 0.001) and had lower driving (12 [8-16] vs 15 [11-17] cmH 2 O, p < 0.001), plateau (20 [15-23] vs 22 [19-26] cmH 2 O, p < 0.001) and peak (21 [17-27] vs 26 [20-32] cmH 2 O, p < 0.001) pressures. Latent mixture analysis of patients receiving invasive mechanical ventilation on ICU day 1 revealed a subgroup ventilated with high pressures with lower probability of being discharged alive from the ICU (hazard ratio [HR] 0.79 [95% confidence interval 0.60-1.05], p = 0.103) and increased hospital mortality (HR 1.65 [1.16-2.36], p = 0.005). In a marginal structural model, driving pressures in the first week (HR 1.12 [1.06-1.18], p < 0.001) and tidal volume after day 7 (HR 0.69 [0.52-0.93], p = 0.015) were related to survival. Conclusions: Higher airway pressures in invasively ventilated patients with CPE are related to mortality. These patients may be exposed to an increased risk of ventilator-induced lung injury