Adhesive Contact to a Coated Elastic Substrate

We show how the quasi-analytic method developed to solve linear elastic contacts to coated substrates (Perriot A. and Barthel E. {\em J. Mat. Res.}, {\bf 2004}, {\em 19}, 600) may be extended to adhesive contacts. Substrate inhomogeneity lifts accidental degeneracies and highlights the general structure of the adhesive contact theory. We explicit the variation of the contact variables due to substrate inhomogeneity. The relation to other approaches based on Finite Element analysis is discussed

Encephalopathies Associated With Severe COVID-19 Present Neurovascular Unit Alterations Without Evidence for Strong Neuroinflammation.

Coronavirus disease (COVID-19) has been associated with a large variety of neurologic disorders. However, the mechanisms underlying these neurologic complications remain elusive. In this study, we aimed at determining whether neurologic symptoms were caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) direct infection or by either systemic or local proinflammatory mediators. In this cross-sectional study, we checked for SARS-CoV-2 RNA by quantitative reverse transcription PCR, SARS-CoV-2-specific antibodies, and 49 cytokines/chemokines/growth factors (by Luminex) in the CSF +/- sera of a cohort of 22 COVID-19 patients with neurologic presentation and 55 neurologic control patients (inflammatory neurologic disorder [IND], noninflammatory neurologic disorder, and MS). We detected anti-SARS-CoV-2 immunoglobulin G in patients with severe COVID-19 with signs of intrathecal synthesis for some of them. Of the 4 categories of tested patients, the CSF of IND exhibited the highest level of cytokines, chemokines, and growth factors. By contrast, patients with COVID-19 did not present overall upregulation of inflammatory mediators in the CSF. However, patients with severe COVID-19 (intensive care unit patients) exhibited higher concentrations of CCL2, CXCL8, and vascular endothelium growth factor A (VEGF-A) in the CSF than patients with a milder form of COVID-19. In addition, we could show that intrathecal CXCL8 synthesis was linked to an elevated albumin ratio and correlated with the increase of peripheral inflammation (serum hepatocyte growth factor [HGF] and CXCL10). Our results do not indicate active replication of SARS-CoV-2 in the CSF or signs of massive inflammation in the CSF compartment but highlight a specific impairment of the neurovascular unit linked to intrathecal production of CXCL8

Hydroxyapatite-TiO2-SiO2-Coated 316L Stainless Steel for Biomedical Application

This study investigated the effectiveness of titania (TiO2) as a reinforcing phase in the hydroxyapatite (HAP) coating and silica (SiO2) single-layer as a bond coat between the TiO2-reinforced hydroxyapatite (TiO2/HAP) top layer and 316L stainless steel (316L SS) substrate on the corrosion resistance and mechanical properties of the underlying 316L SS metallic implant. Single-layer of SiO2 film was first deposited on 316L SS substrate and studied separately. Water contact angle measurements, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectrophotometer analysis were used to evaluate the hydroxyl group reactivity at the SiO2 outer surface. The microstructural and morphological results showed that the reinforcement of HAP coating with TiO2 and SiO2 reduced the crystallite size and the roughness surface. Indeed, the deposition of 50 vol. % TiO2-reinforced hydroxyapatite layer enhanced the hardness and the elastic modulus of the HAP coating, the introduction of SiO2 inner-layer on the surface of the 316L SS allowed the improvement of the bonding strength and the corrosion resistance as confirmed by scratch studies, nanoindentation and cyclic voltammetry tests

MODIFICATION DE LA PERSPECTIVE TEMPORELLE PAR LA PRÉCARITÉ: quels effets sur le sevrage tabagique ?

International audienceLe tabagisme représente un problème de santé publique majeur car il est source d’une lourde morbi-mortalité. Près de la moitié des décès dans la classe sociale la moins favorisée seraient causés par le tabac. Les personnes en situation de précarité sont vulnérables psychologiquement et physiquement. L’instabilité de leur situation augmente leurs difficultés à investir un sevrage tabagique, et certaines orientations temporelles représentent des facteurs péjoratifs de son pronostic. Dans les populations précaires, les conséquences du tabagisme sont mal perçues à moins qu’il n’y ait déni des risques. Les motivations sont essentiellement financières, la perspective du sevrage est vécue comme une privation de plaisir. Indépendamment de l’identification des facteurs de précarité, la prise en compte de la perspective temporelle apporte des informations nécessaires à une prise en charge adaptée

Atomic-Scale Structure and Stability of the Low-Index Surfaces of Pyrochlore Oxides

The multifunctional properties of complex ternary oxides such as pyrochlores are often influenced by surface structure. Optimizing the surface-driven attributes of these materials necessitates a detailed understanding of the structure and chemical composition of those surfaces. Here we report atomistic simulations elucidating the diverse atomic-scale structures of a set of low-index surfaces [(100), (110), (111), and (112)] in pyrochlore compounds as a function of both A and B cation chemistry. In pyrochlores, the low-index facets are all dipolar, requiring the introduction of surface defects to eliminate the surface dipole. We find that, due to the corresponding higher coordination of the surface cations, the (110) facet is the most energetically stable in all of the compounds considered, an interesting contrast to fluorite, in which the (111) surface is most stable. We also reveal a correlation between the surface energy and the energy to disorder the pyrochlore as a function of B cation chemistry, implying a similar physical origin for the two phenomena. Further, we find that surface rumpling is common across all pyrochlore compounds. An even more interesting feature emerging at these surfaces is the formation of extended structural defects such as steps and trenches, which are found to be stable after high-temperature annealing. As the formation of these features is a consequence of surface defects introduced to eliminate the surface dipole, we propose that the superior surface properties of materials of pyrochlores are due to these extended structural features, which are a direct consequence of the inherent dipole at the surfaces

Smoking cessation attempts: is it useful to treat hard core smokers?

Introduction Hard core smokers have been studied in many countries but only a few trials have compared the effectiveness of smoking cessation with other smokers. The objective of this study was to compare the frequencies of success in smoking cessation between hard-core smokers and other smokers. Material and Methods Data were collected in Clermont-Ferrand from the Emile Roux dispensary ‘Pneumology and Tobaccology Centre’ between 1999 and 2009. Assistance with smoking cessation was proposed to 1367 patients but only 1296 patients were included: 219 HCS and 1077 other smokers. Smoking cessation was considered a success when patients were abstinent 6 months after the beginning of cessation. The profiles of the two types of smokers were compared using Chi square test and Student’s t test. Multivariate logistic regression was used to investigate the association between the smoking cessation result and the type of smokers. Results HCS more frequently consumed other psychoactive substances (41.1 % vs 25.7 % for other smokers; p < 0.001). Current depression was more frequent in HCS (46.6 % vs 34.8 % for other smokers; p = 0.001). Smoking cessation was less frequent in HCS (45.2 % vs 56.5 % for other smokers ; p = 0.002). In multivariate analysis, after controlling for other factors, the frequency of smoking cessation was not significantly associated with the type of smokers (p = 0.47). After limiting to initial factors (present before the beginning of smoking cessation), the frequency of smoking cessation was still not significantly associated with the type of smokers (p = 0.78). Conclusions Smoking cessation is possible for hard core smokers, who should be treated as other types of smokers taking into account other factors:the problem is how to encourage them to try to stop smoking