Tribological properties of room temperature fluorinated graphite heat-treated under fluorine atmosphere

This work is concerned with the study of the tribologic properties of room temperature fluorinated graphite heat-treated under fluorine atmosphere. The fluorinated compounds all present good intrinsic friction properties (friction coefficient in the range 0.05–0.09). The tribologic performances are optimized if the materials present remaining graphitic domains (influenced by the presence of intercalated fluorinated species) whereas the perfluorinated compounds, where the fluorocarbon layers are corrugated (armchair configuration of the saturated carbon rings) present higher friction coefficients. Raman analyses reveal that the friction process induces severe changes in the materials structure especially the partial re-building of graphitic domains in the case of perfluorinated compounds which explains the improvement of μ during the friction tests for these last materials

Pattern formation on carbon nanotube surfaces

Calculations of fluorine binding and migration on carbon nanotube surfaces show that fluorine forms varying surface superlattices at increasing temperatures. The ordering transition is controlled by the surface migration barrier for fluorine atoms to pass through next neighbor sites on the nanotube, explaining the transition from semi-ionic low coverage to covalent high coverage fluorination observed experimentally for gas phase fluorination between 200 and 250°C. The effect of solvents on fluorine binding and surface diffusion is explored

Burden of Stroke in Europe:An Analysis of the Global Burden of Disease Study Findings From 2010 to 2019

BACKGROUND:While most European Regions perform well in global comparisons, large discrepancies within stroke epidemiological parameters exist across Europe. The objective of this analysis was to evaluate the stroke burden across European regions and countries in 2019 and its difference to 2010.METHODS:The GBD 2019 analytical tools were used to evaluate regional and country-specific estimates of incidence, prevalence, deaths, and disability-adjusted life years of stroke for the European Region as defined by the World Health Organization, with its 53 member countries (EU-53) and for European Union as defined in 2019, with its 28 member countries (EU-28), between 2010 and 2019. Results were analyzed at a regional, subregional, and country level.RESULTS:In EU-53, the absolute number of incident and prevalent strokes increased by 2% (uncertainty interval [UI], 0%–4%), from 1 767 280 to 1 802 559 new cases, and by 4% (UI, 3%–5%) between 2010 and 2019, respectively. In EU-28, the absolute number of prevalent strokes and stroke-related deaths increased by 4% (UI, 2%–5%) and by 6% (UI, 1%–10%), respectively. All-stroke age-standardized mortality rates, however, decreased by 18% (UI, −22% to −14%), from 82 to 67 per 100 000 people in the EU-53, and by 15% (UI, −18% to −11%), from 49.3 to 42.0 per 100 000 people in EU-28. Despite most countries presenting reductions in age-adjusted incidence, prevalence, mortality, and disability-adjusted life year rates, these rates remained 1.4×, 1.2×, 1.6×, and 1.7× higher in EU-53 in comparison to the EU-28.CONCLUSIONS:EU-53 showed a 2% increase in incident strokes, while they remained stable in EU-28. Age-standardized rates were consistently lower for all-stroke burden parameters in EU-28 in comparison to EU-53, and huge discrepancies in incidence, prevalence, mortality, and disability-adjusted life-year rates were observed between individual countries.<br/

The polymorphism of samarium fullerides

International audienceThree different SmxC60 intercalation compounds have been identified. Sm 2.75C60 has Pa-3 symmetry and is characterized by tetrahedral cation vacancy-ordering. This phase coexists with a Pm-3 Sm3C60 phase, under non-equilibrium conditions, when the metal concentration is increased in the mixture. A bcc Sm6C60 compound represents the upper limit of the doping level. The same behaviour was observed previously in the case of europium fullerides. The possibility that several oxidation states for both anions and cations may exist in M2.75C60 systems is examined

C60-Inorganic fluorides intercalation compounds: some formation condition data and their electrochemical behavior in lithium cell systems

International audienceAn overview of our contribution to the worldwide work on fluorinated carbons and inorganic fluorides-based intercalation compounds is presented. Recent results concerning the intercalation of NbF5 , TaF5 and TiF4 into the C60 lattice and the behavior of a wide series of C60(MFn)x phases used as cathode materials in lithium batteries are described

Transition metals oxyfluorides intercalated into graphite: new synthesis route and electrochemical properties

International audienceA fluorine-oxygen exchange has been realized in several transition metals fluorides (NbF5 , MoF6 , WF6) graphite intercalation compounds (GICs) and oxyfluorides (VOF3 , VOF3-CrO2F2) GICs using hexamethyldisiloxane. The reaction products were characterized by X-ray diffraction, thermogravimetric analysis, FT-IR and 19F NMR spectroscopy. The electrochemical performances of these novel materials were tested in liquid electrolyte conditions