Thermal Expansion of (Ba1-xLax))Ti1-x/4 O 3 Solid Solutions

Deformation and the thermal expansion coefficient of ceramic samples of (Ba1−xLax)Ti1−x /4 O 3 solid solutions (x= 0, 0.026, 0.036, 0.054) were studied in the temperature range 120–700 K. Based on an analysis of the data obtained, the temperature–composition phase diagram is refined, and the temperature dependence of the polarization is calculated. The results are discussed in combination with the dielectric measurement data

Thermochemistry of iron manganese oxide spinels

Oxide melt solution calorimetry has been performed on iron manganese oxide spinels prepared at high temperature. The enthalpy of formation of (MnxFe1−x)3O4 at 298 K from the oxides, tetragonal Mn3O4 (hausmannite) and cubic Fe3O4 (magnetite), is negative from x=0 to x=0.67 and becomes slightly positive for 0.670.6) spinels of intermediate compositions. The enthalpies of formation are discussed in terms of three factors: oxidation–reduction relative to the end-members, cation distribution, and tetragonality. A combination of measured enthalpies and Gibbs free energies of formation in the literature provides entropies of mixing. ΔSmix, consistent with a cation distribution in which all trivalent manganese is octahedral and all other ions are randomly distributed for x>0.5, but the entropy of mixing appears to be smaller than these predicted values for x<0.4

Long-term cycling behavior of asymmetric activated carbon/MnO2 aqueous electrochemical supercapacitor

Activated carbon–MnO2 hybrid electrochemical supercapacitor cells have been assembled and characterized in K2SO4 aqueous media. A laboratory cell achieved 195,000 cycles with stable performance. The maximal cell voltage was 2V associated with 21±2Fg−1 of total composite electrode materials (including activated carbon andMnO2, binder and conductive additive) and an equivalent serie resistance (ESR) below1.3cm2. Long-life cycling was achieved by removing dissolved oxygen from the electrolyte, which limits the corrosion of current collectors. Scaling up has been realized by assembling several electrodes in parallel to build a prismatic cell. A stable capacity of 380 F and a cell voltage of 2V were maintained over 600 cycles. These encouraging results show the interest of developing such devices, including non-toxic and safer components as compared to the current organic-based devices

Thermal expansion, polarization and phase diagrams of Ba1−yBi2y/3Ti1−xZrxO3 and Ba1−yLayTi1−y/4O3 compounds

The thermal expansion properties of the ceramic compositions Ba1−yLayTi1−y/4O3 (y = 0.0, 0.026, 0.036, 0.054) and Ba1−yBi2y/3Ti1−xZrxO3 (y = 0.10; x = 0.0, 0.04, 0.05, 0.10, 0.15) were determined in the temperature range 120–700 K. We report the temperature-dependent measurements of the strain, thermal expansion coefficient and the magnitude of root mean square polarization. The results obtained are discussed together with the data on the structure and dielectric properties

Plant Nutrient Resource Use Strategies Shape Active Rhizosphere Microbiota Through Root Exudation

Plant strategies for soil nutrient uptake have the potential to strongly influence plant–microbiota interactions, due to the competition between plants and microorganisms for soil nutrient acquisition and/or conservation. In the present study, we investigate whether these plant strategies could influence rhizosphere microbial activities via root exudation, and contribute to the microbiota diversification of active bacterial communities colonizing the root-adhering soil (RAS) and inhabiting the root tissues. We applied a DNA-based stable isotope probing (DNA-SIP) approach to six grass species distributed along a gradient of plant nutrient resource strategies, from conservative species, characterized by low nitrogen (N) uptake, a long lifespans and low root exudation level, to exploitative species, characterized by high rates of photosynthesis, rapid rates of N uptake and high root exudation level. We analyzed their (i) associated microbiota composition involved in root exudate assimilation and soil organic matter (SOM) degradation by 16S-rRNA-based metabarcoding. (ii) We determine the impact of root exudation level on microbial activities (denitrification and respiration) by gas chromatography. Measurement of microbial activities revealed an increase in denitrification and respiration activities for microbial communities colonizing the RAS of exploitative species. This increase of microbial activities results probably from a higher exudation rate and more diverse metabolites by exploitative plant species. Furthermore, our results demonstrate that plant nutrient resource strategies have a role in shaping active microbiota. We present evidence demonstrating that plant nutrient use strategies shape active microbiota involved in root exudate assimilation and SOM degradation via root exudation

Necrotrophism Is a Quorum-Sensing-Regulated Lifestyle in Bacillus thuringiensis

How pathogenic bacteria infect and kill their host is currently widely investigated. In comparison, the fate of pathogens after the death of their host receives less attention. We studied Bacillus thuringiensis (Bt) infection of an insect host, and show that NprR, a quorum sensor, is active after death of the insect and allows Bt to survive in the cadavers as vegetative cells. Transcriptomic analysis revealed that NprR regulates at least 41 genes, including many encoding degradative enzymes or proteins involved in the synthesis of a nonribosomal peptide named kurstakin. These degradative enzymes are essential in vitro to degrade several substrates and are specifically expressed after host death suggesting that Bt has an active necrotrophic lifestyle in the cadaver. We show that kurstakin is essential for Bt survival during necrotrophic development. It is required for swarming mobility and biofilm formation, presumably through a pore forming activity. A nprR deficient mutant does not develop necrotrophically and does not sporulate efficiently in the cadaver. We report that necrotrophism is a highly regulated mechanism essential for the Bt infectious cycle, contributing to spore spreading

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/)

Le droit à l'envers

Bitot Jacques, Guillemet Philippe. Le droit à l'envers. In: Communications, 19, 1972. Le texte : de la théorie à la recherche. pp. 60-68

Caractéristiques épidémiologiques des infections respiratoires virales au Cambodge au travers d'une approche diagnostique moléculaire par PCR multiplex et variabilité génétique des VRS A et B au Cambodge.

STRASBOURG-Medecine (674822101) / SudocSudocFranceF

CONTRIBUTION EXPERIMENTALE ET THEORIQUE A L'ETUDE DES PHENOMENES THERMIQUES INSTATIONNAIRES ULTRA-RAPIDES, DE LA NANOSECONDE A LA PICOSECONDE

LE MODELE CLASSIQUE DE CONDUCTION DE LA CHALEUR (L'EQUATION PARABOLIQUE), MUNI DES SES HABITUELLES CONDITIONS AUX LIMITES, NE PEUT PAS RENDRE COMPTE DES TRANSFERTS THERMIQUES CONDUCTIFS DANS LES SITUATIONS EXTREMES DONT LA PRISE EN CONSIDERATION S'IMPOSE AUJOURD'HUI, TANT SUR LE PLAN THEORIQUE QUE SUR LE PLAN TECHNOLOGIQUE. LE MODELE HISTORIQUE DE CONDUCTION HYPERBOLIQUE INTRODUIT UN HYPOTHETIQUE TERME D'INERTIE DE LA CHALEUR, LE TEMPS DE RELAXATION, DONT LES CONSEQUENCES PHYSIQUES SONT NOMBREUSES ET PARFOIS CONTROVERSEES. POUR TENTER LA MISE EN EVIDENCE EXPERIMENTALE DE CE TERME CORRECTIF, LA REALISATION D'UNE EXPERIMENTATION DE RESEAU TRANSITOIRE, DESTINEE A ETUDIER L'ECHELLE DES TEMPS DE RELAXATION DES GAZ (10 8 A 10 - 1 0S), PUIS DES DIELECTRIQUES (10 - 1 0 A 10 - 1 2 S), EST PRESENTEE. ELLE FAIT APPARAITRE, DANS UN ECHANTILLON DE DIAMANT, UN SIGNAL DONT LA MODELISATION THERMIQUE SEMBLE POSSIBLE, ET PERMET DE DEGAGER UN TEMPS DE RELAXATION DU MATERIAU DE L'ORDRE DE 5 A 810 - 1 2 S. MAIS LA GRANDE DIFFICULTE D'OBTENTION DE CE SIGNAL ET LE BRUIT QUI L'ENTACHE CONDUISENT A UNE TROP GRANDE PLAGE D'INCERTITUDE SUR CETTE VALEUR POUR POUVOIR JUGER DE LA PERTINENCE DU MODELE HYPERBOLIQUE. LA PARTIE THEORIQUE DE L'ETUDE MONTRE QUE LE MODELE CLASSIQUE DE CONDUCTION DE LA CHALEUR BRUTE NON SEULEMENT SUR LE PROBLEME DE L'INSTANTANEITE MAIS AUSSI SUR L'ASPECT SPATIAL, LIE A LA PETITESSE INEVITABLE DES DOMAINES CONCERNES (QUELQUES LIBRES PARCOURS MOYENS DES PORTEURS D'ENERGIE) PAR LES PREMIERS INSTANTS DES REGIMES TRANSITOIRES INCRIMINES (QUELQUES TEMPS DE RELAXATION). LA FAIBLE QUANTITE D'INTERACTIONS DIFFUSIVES ENTRE PORTEURS D'ENERGIE AU VOISINAGE D'UNE PAROI REND CADUQUE L'APPLICATION DE LA NOTION CLASSIQUE DE CONDUCTIVITE THERMIQUE DANS CETTE ZONE. UN MODELE EST PRESENTE. IL REPREND L'IDEE D'UNE PROLONGATION ARBITRAIRE DES EQUATIONS MACROSCOPIQUES JUSQU'A LA FRONTIERE, MAIS EN UTILISANT DES CONDITIONS AUX FRONTIERES ADAPTEES. CES CONDITIONS AUX LIMITES FONT INTERVENIR UN TERME RESISTIF TRADUISANT LE SAUT DE TEMPERATURE A LA PAROI LORSQUE CELLE-CI EST A TEMPERATURE IMPOSEE, AINSI QU'UNE CORRECTION DE LA CAPACITE THERMIQUE DE LA COUCHE PROCHE DE LA FRONTIERE QUI DEVIENT PREPONDERANTE LORSQUE LA PAROI EST THERMIQUEMENT ISOLEE, AVEC UNE EVENTUELLE GENERATION DE FLUX SURFACIQUE OU SUBSURFACIQUE.NANTES-Ecole Centrale (441092306) / SudocNANTES-BU Sciences (441092104) / SudocSudocFranceF