Études des réactions primaires en solutions par la radiolyse pulsée picoseconde

Après la découverte des rayonnements ionisants et leurs effets chimiques, il était important d étudier et de comprendre les mécanismes de formations des radicaux libres et des produits moléculaires caractérisés par leurs courtes durées de vie. Ceci a encouragé les groupes de recherches à développer leurs outils pour qu ils puissent réaliser ces études. De nos jours la radiolyse impulsionnelle se manifeste comme un outil fondamental permettant de sonder les effets chimiques ainsi que les mécanismes réactionnels dans le milieu étudié.Le laboratoire de Chimie Physique d Orsay LCP est un laboratoire interdisciplinaire abritant la plateforme ELYSE qui est un centre de cinétiques rapides. Grâce au laser femtoseconde et à l accélérateur d électrons picoseconde, nous avons eu la possibilité, dans le domaine de la radiolyse, de remonter en temps, en étudiant les effets chimiques dans un milieu réactionnel, jusqu à ~ 5 ps.Nous nous sommes intéressés par les réactions primaires induites par les rayonnements ionisants en solution et ELYSE représentait l outil principal pour ces études. Les résultats obtenus concernent :- La détermination directe du rendement radiolytique du radical hydroxyle HO en fonction du temps à l échelle de la picoseconde ;- Etude de l effet direct du rayonnement ionisant sur les solutions aqueuses concentrées ainsi que la vérification de la réaction de transfert d électron ultrarapide entre le soluté et le trou positif H2O + issu lors de la radiolyse de l eau ;- Etude à température ambiante de la réaction de transfert d électron entre un électron solvaté (donneur d électron) et un soluté organique (accepteur d électron) en milieu visqueux ;- Etude à température ambiante de la solvatation de l électron dans l éthylène glycol et dans le propan-2-ol.Following the discovery of ionizing radiations and their chemical effects, it was important to study and comprehend the formation mechanisms of short lived free radicals and molecular products. In order to perform such studies, researchers and research groups worked on developing tools allowing both formation and detection of those species at short time scales. Nowadays, pulse radiolysis imposed itself as a fundamental and efficient tool allowing scientists to probe chemical effects as well as reaction mechanisms in studied media.The laboratoire de Chimie Physique d Orsay LCP is an interdisciplinary laboratory hosting the platform of fast kinetics known as ELYSE . Due to its femtosecond laser and its picosecond electron accelerator, we have the possibility to study chemical effects of ionizing radiations interaction with media at ultrashort times up to ~5 ps.Knowing that we are interested in primary reactions induced in aqueous media by ionizing radiations, ELYSE represents the essential tool in performing our studies. The obtained results concern:- First direct determination of hydroxyl radical HO radiolytic yield as function of time at picosecond time scale ;- Direct effect of ionizing radiation in highly concentrated aqueous solutions as well as investigation of the ultrafast electron transfer reaction between solute molecules and positive holes H2O + formed upon water radiolysis ;- Study at room temperature of electron transfer reaction between solvated electron (electron donor) and organic solutes (electron acceptors) en viscous medium ;- Study at room temperature of electron s solvation dynamics in ethylene glycol and 2-propanol.PARIS11-SCD-Bib. électronique (914719901) / SudocSudocFranceF

Cutaneous reactions to carbamazepine in children with epilepsy

BACKGROUND: The main components in controlling and treating seizures are antiepileptic drugs (AEDs). Mostly, the systemic side effects of these drugs are regarded very important; however, these drugs can also cause serious mucocutaneous side effects. Carbamazepine is a drug which is used to treat epilepsy. Side effects of this drug can range from skin rash to toxic epidermal necrolysis (TEN) and Stevens-Johnson syndrome (SJS). The purpose of this study was to evaluate skin complications of carbamazepine in children with epilepsy.METHODS: This study was performed on 99 children, aged 2 months to 11 years, with the diagnosis of skin complications after taking carbamazepine. Records were examined and their initial profiles including their medical skin conditions and rashes were recorded within the checklist. Data were entered into SPSS software. Measures of central tendency and dispersion were achieved. Finally, the relationship between the drug and the cutaneous reactions of these patients was analyzed using the chi-square test.RESULTS: The most common complications among the patients were maculopapular lesions and skin erythroderma, with the prevalence of 37.4% for each. Other types of skin lesions included papules with 14.1%, macules with 8.1%, and SJS with 3.0%. A significant association (P = 0.02) between the types of the skin lesion and the dose of carbamazepine was observed; the more the dosage was, the more severe skin lesions were.CONCLUSION: The most common cutaneous reactions to carbamazepine were erythroderma and maculopapular rash in the patients. The findings of this study also revealed that the lack of drug compliance was of high importance

La Recherche en Chimie aux Frontières de la Connaissance

National audienceMixed research units are building blocks, flexible but permanent, in rapidly evolving fields of research. Several measures shape the activities of research teams and thus give rise to “poles of research”. They also help consolidate national networks, identify strong points, boost the sharing of top-level equipment and stimulate collaboration between academics and industrialists. Chemists’ diverse activities lie on a thematic continuum that reaches beyond disciplinary bounds and crisscrosses the industrial and academic spheres. The dichotomy between, on the one hand, the structure in terms of disciplines used by the authorities in charge and, on the other hand, the socioeconomic priorities set by funding agencies should enable scientists to pursue topnotch research. It should also lead to the emergence of new concepts corresponding to breakthroughs that will reshape chemistry in the future.L’Unité Mixte de Recherche est la brique élémentaire, souple et pérenne d’un paysage de la recherche en évolution rapide. De nombreux dispositifs viennent structurer l’activité de ces équipes pour faire émerger des pôles de recherche, consolider le maillage des réseaux nationaux, identifier les points forts, mutualiser des équipements de haut niveau et promouvoir les collaborations académiques et industrielles. La diversité de l’activité des chimistes se place dans un continuum thématique dépassant les frontières disciplinaires et traversant les mondes académiques et industriels. La dichotomie entre les structures disciplinaires de nos tutelles et l’affichage de défis socio-économiques par les agences de financement doivent permettre aux acteurs de mettre en œuvre des recherches de très haut niveau tout en favorisant l’émergence et la description de nouveaux concepts en rupture qui permettront de construire la chimie de demain

Aerobic Exercise and Scaffolds with Hierarchical Porosity Synergistically Promote Functional Recovery Post Volumetric Muscle Loss

Volumetric muscle loss (VML) is a composite loss of skeletal muscle tissue (greater than 20%) that heals with minimal muscle regeneration, substantial fibrosis, and subsequent functional deficits. Standard treatment, involving free functional muscle transfer and physical therapy, cannot restore full muscle function following VML. Tissue engineered scaffolds, 3D structural templates that mimic native extracellular matrix, are promising to enhance functional muscle formation and recovery. Bioprinted 3D scaffolds are engineered using bioinks, created from scaffolding material, cells, and growth factors, to replicate skeletal muscle architecture with precise control over their spatial deposition. METHODS: The present study evaluates a 3D-printed foam-like scaffold for the treatment of VML in a murine model. This colloidal foam-like scaffold was developed to have high porosity to improve tissue ingrowth, in contrast to dense polymeric scaffolds that routinely resulted in very poor tissue ingrowth, and sufficient stiffness to maintain its shape

Global age-sex-specific mortality, life expectancy, and population estimates in 204 countries and territories and 811 subnational locations, 1950–2021, and the impact of the COVID-19 pandemic: a comprehensive demographic analysis for the Global Burden of Disease Study 2021

Background: Estimates of demographic metrics are crucial to assess levels and trends of population health outcomes. The profound impact of the COVID-19 pandemic on populations worldwide has underscored the need for timely estimates to understand this unprecedented event within the context of long-term population health trends. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 provides new demographic estimates for 204 countries and territories and 811 additional subnational locations from 1950 to 2021, with a particular emphasis on changes in mortality and life expectancy that occurred during the 2020–21 COVID-19 pandemic period. Methods: 22 223 data sources from vital registration, sample registration, surveys, censuses, and other sources were used to estimate mortality, with a subset of these sources used exclusively to estimate excess mortality due to the COVID-19 pandemic. 2026 data sources were used for population estimation. Additional sources were used to estimate migration; the effects of the HIV epidemic; and demographic discontinuities due to conflicts, famines, natural disasters, and pandemics, which are used as inputs for estimating mortality and population. Spatiotemporal Gaussian process regression (ST-GPR) was used to generate under-5 mortality rates, which synthesised 30 763 location-years of vital registration and sample registration data, 1365 surveys and censuses, and 80 other sources. ST-GPR was also used to estimate adult mortality (between ages 15 and 59 years) based on information from 31 642 location-years of vital registration and sample registration data, 355 surveys and censuses, and 24 other sources. Estimates of child and adult mortality rates were then used to generate life tables with a relational model life table system. For countries with large HIV epidemics, life tables were adjusted using independent estimates of HIV-specific mortality generated via an epidemiological analysis of HIV prevalence surveys, antenatal clinic serosurveillance, and other data sources. Excess mortality due to the COVID-19 pandemic in 2020 and 2021 was determined by subtracting observed all-cause mortality (adjusted for late registration and mortality anomalies) from the mortality expected in the absence of the pandemic. Expected mortality was calculated based on historical trends using an ensemble of models. In location-years where all-cause mortality data were unavailable, we estimated excess mortality rates using a regression model with covariates pertaining to the pandemic. Population size was computed using a Bayesian hierarchical cohort component model. Life expectancy was calculated using age-specific mortality rates and standard demographic methods. Uncertainty intervals (UIs) were calculated for every metric using the 25th and 975th ordered values from a 1000-draw posterior distribution. Findings: Global all-cause mortality followed two distinct patterns over the study period: age-standardised mortality rates declined between 1950 and 2019 (a 62·8% [95% UI 60·5–65·1] decline), and increased during the COVID-19 pandemic period (2020–21; 5·1% [0·9–9·6] increase). In contrast with the overall reverse in mortality trends during the pandemic period, child mortality continued to decline, with 4·66 million (3·98–5·50) global deaths in children younger than 5 years in 2021 compared with 5·21 million (4·50–6·01) in 2019. An estimated 131 million (126–137) people died globally from all causes in 2020 and 2021 combined, of which 15·9 million (14·7–17·2) were due to the COVID-19 pandemic (measured by excess mortality, which includes deaths directly due to SARS-CoV-2 infection and those indirectly due to other social, economic, or behavioural changes associated with the pandemic). Excess mortality rates exceeded 150 deaths per 100 000 population during at least one year of the pandemic in 80 countries and territories, whereas 20 nations had a negative excess mortality rate in 2020 or 2021, indicating that all-cause mortality in these countries was lower during the pandemic than expected based on historical trends. Between 1950 and 2021, global life expectancy at birth increased by 22·7 years (20·8–24·8), from 49·0 years (46·7–51·3) to 71·7 years (70·9–72·5). Global life expectancy at birth declined by 1·6 years (1·0–2·2) between 2019 and 2021, reversing historical trends. An increase in life expectancy was only observed in 32 (15·7%) of 204 countries and territories between 2019 and 2021. The global population reached 7·89 billion (7·67–8·13) people in 2021, by which time 56 of 204 countries and territories had peaked and subsequently populations have declined. The largest proportion of population growth between 2020 and 2021 was in sub-Saharan Africa (39·5% [28·4–52·7]) and south Asia (26·3% [9·0–44·7]). From 2000 to 2021, the ratio of the population aged 65 years and older to the population aged younger than 15 years increased in 188 (92·2%) of 204 nations. Interpretation: Global adult mortality rates markedly increased during the COVID-19 pandemic in 2020 and 2021, reversing past decreasing trends, while child mortality rates continued to decline, albeit more slowly than in earlier years. Although COVID-19 had a substantial impact on many demographic indicators during the first 2 years of the pandemic, overall global health progress over the 72 years evaluated has been profound, with considerable improvements in mortality and life expectancy. Additionally, we observed a deceleration of global population growth since 2017, despite steady or increasing growth in lower-income countries, combined with a continued global shift of population age structures towards older ages. These demographic changes will likely present future challenges to health systems, economies, and societies. The comprehensive demographic estimates reported here will enable researchers, policy makers, health practitioners, and other key stakeholders to better understand and address the profound changes that have occurred in the global health landscape following the first 2 years of the COVID-19 pandemic, and longer-term trends beyond the pandemic

Proprietes thermodynamiques d'agregats metalliques a faible nombre d'atomes en phase condensee : catalyse de transfert d'electron simulation du developpement photographique

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Formation et réactivité de la paire électron solvaté-métal alcalino-terreux bivalent dans le tétrahydrofuranne (étude par radiolyse impulsionnelle)

La réactivité des électrons solvates vis à vis des sels de magnésium et plus généralement dans le cas des alcalino-terreux n'avait jusqu'à présent jamais été étudiée. Or pour le magnésium, l'éventuelle formation de l'état de valence intermédiaire + I est important puisque sa nature et ses propriétés sont au coeur des modèles mécanistiques de la formation des réactifs de Grignard, ou organomagnésiens, au cours de laquelle le magnésium métallique (de valence 0) devient bivalent. Nous avons donc entrepris des séries d'expériences afin de caractériser cette espèce en faisant réagir le magnésium bivalent sous forme de sel (perchlorate et chlorure) avec un électron solvate issu de la radiolyse du solvant (le tétrahydrofuranne et d'autres solvants à titre de comparaison). Plus généralement l'étude a porté sur les alcalinoterreux dans le but de cerner les effets du cation au cours de cette réaction. Nous avons ainsi pu mettre en évidence, à la fois sur le plan expérimental et sur le plan théorique, la formation d'une paire d'ion cation - électron. La formation de cette paire ne fut mise en évidence que pour les perchlorates de métaux alcalino-terreux, puis nous avons observé sa disparition an bout de quelques centaines de nanosecondes selon une cinétique globalement de premier ordre. Ce transitoire, quel que soit le métal alcalino-terreux utilisé (Mg, Ca, Sr), possède un large spectre d'absorption composé de 2 bandes situées autour de 1000 nm qui indique plutôt la présence d'une paire d'ion que d'un cation monovalent. Les calculs de type SCF ont indiqué clairement qu'il s'agissait bien de la formation d'une paire. Cette paire cation - électron, bien que transitoire, possède une réactivité. Nous avons observé sa capacité à réduire des molécules aromatiques (biphényle, anthracène, chrysène, phénanthrène et tétracène) et nous avons ainsi pu déterminer son potentiel redox qui est situé entre -2,8 et -2,6 V. De même, nous avons mis en évidence la réduction de molécules d'halogénures d'alkyles (dérivés alkyliques, phényliques et benzyliques) par ces mêmes paires et la rupture de la liaison carbone - halogène qui correspond à une étape de la synthèse du réactif de Grignard. Dans tous les cas, nous avons déterminé les mécanismes et les cinétiques de ces différentes réactions.The reactivity of solvated electrons toward magnesium salts, and more generally, toward earth-alkaline metals has not yet been studied until those days. For magnesium, the formation of the unusual valence state is of interest because its nature and properties are at the center of mechanistics models on the formation of Grignard reagents, or organomagnesians, by which the metallic magnesium (valence 0) becomes divalent. We have conducted series of experiments in order to characterize this species by following the reaction of divalent magnesium salt (chloride or perchlorate) toward solvated electron generated by pulse radiolysis in tetrahydrofuran and some solvents for comparison. We showed experimentally and theoritically that there is formation of a pair solvated electron - metallic ion. This pair is obtained with perchlorates salts, then we followed its decay lasting few hundreds nanoseconds with a first order kinetic. This transient, whatever that would be the metal, has a broad spectrum which is composed by two bands around 1000 nm. It indicates the presence of a pair rather than a monovalent cation. SCF calculations confirmed it was the formation of a pair. This solvated electron - cation pair, even it has a short time life, has its own reactivity. We observed its capacity to reduce aromatic molecules (biphenyl, anthracen, chrysen, phenanthren and tetracen) and so we have estimated its redox potential which is include between - 2.8 and - 2.6 V_HNE. Furthermore, we brought out the reduction of alkyle halide (alkylic, phenylic and benzylic compounds) by the pair and the break of carbon-halogen bond which is corresponding to a step in the synthesis of Grignard reagents. In all cases, we determined mechanisms and kinetics of these different reactions.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF