Embedded layer of Ag nanoparticles prepared by a combined PECVD/PVD process producing SiOxCy-Ag nanocomposite thin films.

Structural properties of SiOxCy–Ag nanocomposite thin films prepared by a dual process PVD–PECVD in the same reactor have been investigated. The experimental results have demonstrated the influence of a PECVD process carried out at room temperature for the growth of a dielectric matrix on the size and the distribution density of Ag nanoparticles (NPs) deposited beforehand by magnetron sputtering. The plasma during the growth of the encapsulation SiOxCy layer caused a diffusion of silver from NPs through the SiOxCy matrix associated with a decrease in the average size of nanoparticles and an increase of their distribution density. Silver diffusion is blocked at a barrier interface to form a buried layer of individual Ag NPs which, for instance, can find plasmonic applications. Silver also diffuses toward the outer surface inducing antibacterial properties. In both cases initial Ag NPs act as reservoirs for multifunctional properties of advanced nanostructured films

DLI-CVD of TiO2–Cu antibacterial thin films: Growth and characterization

TiO2–Cu nanocomposite films were grown by pulsed direct liquid injection chemical vapor deposition (DLICVD) on stainless steel, silicon and glass substrates with the goal to produce bactericidal surfaces. Copper bis (2,2,6,6-tetramethyl-3,5-heptadionate), Cu(TMHD)2, and titanium tetra-iso-propoxide, TTIP, were used as metalorganic precursors. Liquid solutions of these compounds in xylene were injected in a flash vaporization chamber connected to a cold wall MOCVD reactor. The deposition temperature was typically 683 K and the total pressure was 800 Pa. The copper content of the layers was controlled by the mole fraction of Cu (TMHD)2 which was adjusted by the injection parameters (injection frequency and concentration of the starting solution). The chemical, structural and physical characteristics of the films were investigated by XRD, XPS, FEG-SEM and TEM. Copper is incorporated as metal particles with a relatively large size distribution ranging from 20 to 400 nm (with a large majority in 20–100 nm) depending on the copper content of the films. The influence of the growth conditions on the structural features and the antibacterial properties of the thin films are reported and discussed

Comparative study of antibacterial efficiency of M-TiO2 (M = Ag, Cu) thin films grown by CVD

M-TiO2 (M = Ag, Cu) nanocomposite layers were grown by pulsed direct liquid injection chemical vapor deposition (DLICVD) on various substrates to produce bactericidal surfaces with long term activity. Monodisperse Ag nanoparticles (NPs) with an average size of 5-10 nm are embedded in an anatase matrix. A bactericidal behavior determined by the JIS Z 2801 standard test was found for Ag-TiO2 films for Ag ≤ 1 at. % and above. Higher Ag content is not necessary since efficiency is already at its maximum (relative activity 100%). By contrast, using Cu as antibacterial agent, a larger size distribution of metal particles was found (20 to 400 nm). Cu-TiO2 films exhibit a bactericidal behavior if their thickness is higher than 100 nm and Cu content ≥ 3.5 at. %. These coatings are still antibacterial after 5 months of aging and their efficiency has decreased by only 35%

Antibacterial properties of TiO2–Cu composite thin films grown by a one step DLICVD process

The correlations between microstructural features, chemical compositions and antibacterial properties of coatings containing metallic Cu particles embedded in a titanium dioxide matrix have been determined. A Direct Liquid Injection Chemical Vapor Deposition (DLICVD) processwas used for the one step growth of TiO2–Cu composite coatings on various substrates. Titanium tetra-iso-propoxide (TTIP) and copper bis(2,2,6,6-tetramethyl-3,5-heptationate) (Cu(tmhd)2) were used as titanium and copper molecular sources, respectively. This growth process allows a good control of the quantity of metalorganic precursors injected into the CVD reactor and thus of the coating composition. The deposition occurs at 683 K under low pressure (800 Pa). The influence of the main features of the coatings on their antibacterial properties was investigated in order to produce bactericidal surfaces that are durable, non-toxic and containing aminimumamount of active agent. The antibacterial activity on Staphylococcus aureus without any photon activation was measured according to the JIS Z 2801:2000 standard method. An antibacterial activity was detected for a low metal content of ca. 1 at.% Cu, and was found to increasewith the Cu content. It wasmaximal for 3.5 at.% Cu, i.e. TiO2–Cu composite coatings exhibit bactericidal behavior against S. aureus for this optimal composition (relative activity = 100%). In order to better characterize the microbiological behavior of the coatings more discriminating methods derived from the literature were tested to assess the performances of these CVD coatings in terms of efficiency, release of antibacterial agent and accelerated aging

Differing roles of CD1d2 and CD1d1 proteins in type I natural killer T cell development and function

MHC class I-like CD1 molecules have evolved to present lipid-based antigens to T cells. Differences in the antigen-binding clefts of the CD1 family members determine the conformation and size of the lipids that are presented, although the factors that shape CD1 diversity remain unclear. In mice, two homologous genes, CD1D1 and CD1D2, encode the CD1d protein, which is essential to the development and function of natural killer T (NKT) cells. However, it remains unclear whether both CD1d isoforms are equivalent in their antigen presentation capacity and functions. Here, we report that CD1d2 molecules are expressed in the thymus of some mouse strains, where they select functional type I NKT cells. Intriguingly, the T cell antigen receptor repertoire and phenotype of CD1d2-selected type I NKT cells in CD1D1−/− mice differed from CD1d1-selected type I NKT cells. The structures of CD1d2 in complex with endogenous lipids and a truncated acyl-chain analog of α-galactosylceramide revealed that its A′-pocket was restricted in size compared with CD1d1. Accordingly, CD1d2 molecules could not present glycolipid antigens with long acyl chains efficiently, favoring the presentation of short acyl chain antigens. These results indicate that the two CD1d molecules present different sets of self-antigen(s) in the mouse thymus, thereby impacting the development of invariant NKT cells

CD63-GPC1-Positive Exosomes Coupled with CA19-9 Offer Good Diagnostic Potential for Resectable Pancreatic Ductal Adenocarcinoma

Tumor-released extracellular vesicles (EVs) contain tumor-specific cargo distinguishing them from healthy EVs, and making them eligible as circulating biomarkers. Glypican 1 (GPC1)-positive exosome relevance as liquid biopsy elements is still debated. We carried out a prospective study to quantify GPC1-positive exosomes in sera from pancreatic ductal adenocarcinoma (PDAC) patients undergoing up-front surgery, as compared to controls including patients without cancer history and patients displaying pancreatic preneoplasic lesions. Sera were enriched in EVs, and exosomes were pulled down with anti-CD63 coupled magnetic beads. GPC1-positive bead percentages determined by flow cytometry were significantly higher in PDAC than in the control group. Diagnosis accuracy reached 78% (sensitivity 64% and specificity 90%), when results from peripheral and portal blood were combined. In association with echo-guided-ultrasound-fine-needle-aspiration (EUS-FNA) negative predictive value was 80% as compared to 33% for EUS-FNA only. This approach is clinically relevant as a companion test to the already available diagnostic tools, since patients with GPC1-positive exosomes in peripheral blood showed decreased tumor free survival

Impact of species and antibiotic therapy of enterococcal peritonitis on 30-day mortality in critical care - An analysis of the OUTCOMEREA database

Introduction: Enterococcus species are associated with an increased morbidity in intraabdominal infections (IAI). However, their impact on mortality remains uncertain. Moreover, the influence on outcome of the appropriate or inappropriate status of initial antimicrobial therapy (IAT) is subjected to debate, except in septic shock. The aim of our study was to evaluate whether an IAT that did not cover Enterococcus spp. was associated with 30-day mortality in ICU patients presenting with IAI growing with Enterococcus spp. Material and methods: Retrospective analysis of French database OutcomeRea from 1997 to 2016. We included all patients with IAI with a peritoneal sample growing with Enterococcus. Primary endpoint was 30-day mortality. Results: Of the 1017 patients with IAI, 76 (8%) patients were included. Thirty-day mortality in patients with inadequate IAT against Enterococcus was higher (7/18 (39%) vs 10/58 (17%), p = 0.05); however, the incidence of postoperative complications was similar. Presence of Enterococcus spp. other than E. faecalis alone was associated with a significantly higher mortality, even greater when IAT was inadequate. Main risk factors for having an Enterococcus other than E. faecalis alone were as follows: SAPS score on day 0, ICU-acquired IAI, and antimicrobial therapy within 3 months prior to IAI especially with third-generation cephalosporins. Univariate analysis found a higher hazard ratio of death with an Enterococcus other than E. faecalis alone that had an inadequate IAT (HR = 4.4 [1.3-15.3], p = 0.019) versus an adequate IAT (HR = 3.1 [1.0-10.0], p = 0.053). However, after adjusting for confounders (i.e., SAPS II and septic shock at IAI diagnosis, ICU-acquired peritonitis, and adequacy of IAT for other germs), the impact of the adequacy of IAT was no longer significant in multivariate analysis. Septic shock at diagnosis and ICU-acquired IAI were prognostic factors. Conclusion: An IAT which does not cover Enterococcus is associated with an increased 30-day mortality in ICU patients presenting with an IAI growing with Enterococcus, especially when it is not an E. faecalis alone. It seems reasonable to use an IAT active against Enterococcus in severe postoperative ICU-acquired IAI, especially when a third-generation cephalosporin has been used within 3 months. © 2019 The Author(s)

Structure et réductibilité de pérovskites La-Co-Fe (Application à la synthèse Fischer-Tropsch)

La synthèse Fischer-Tropsch est une voie de valorisation du gaz naturel particulièrement intéressante. Après reformage du gaz naturel en gaz de synthèse (CO +H2) ce procédé permet d'obtenir, sur des catalyseurs à base de cobalt et/ou de fer métallique, des hydrocarbures exempts de soufre. Dans ce travail, Fe et Co ont été intégrés dans une structure cristalline de type pérovskite (ABO3) connue pour sa malléabilité. La série LaCoxFe(1-x)O3 a été préparée par une méthode pseudo sol-gel. En fonction de la teneur en cobalt x, les pérovskites cristallisent dans le système orthorhombique si x<0,5 ou dans le système rhomboédrique si xđ0,5. L'étude du processus de réduction de ces matériaux a montré que leur réduction partielle est possible et que seules les pérovskites orthorhombiques permettent d'obtenir des particules de Co0. L'oxyde partiellement réduit conserve après le traitement réducteur sa structure cristalline originelle. La quantité de métal extractible peut être augmentée soit en diminuant la température de calcination de l'oxyde brut, soit en introduisant, lors de la synthèse, une déficience en lanthane afin de générer des défauts dans le réseau cristallin. L'étude par DRX et spectroscopie Mössbauer de la série déficiente en lanthane La(1-y)Co0,4Fe0,6O3-d a révélé l'existence d'un phénomène " noyau-coquille ". L'excès de cations B de la pérovskite est rejeté sous forme de petits noyaux de g-Fe2O3 (cubique) sur lesquels cristallise par épitaxie une phase pérovskite cubique non déficiente en La et riche en Co. La réduction partielle à 450ʿC de ces nano-composites génère une phase alliage (Co-Fe)0 dont le fer provient de la réduction des noyaux de g-Fe2O3. Au cours du traitement réducteur, la phase pérovskite s'enrichit en fer.La réactivité catalytique de ces oxydes partiellement réduits a été étudiée sous flux et sous pression. Les catalyseurs sont très sélectifs pour la formation d'oléfines légères, ont une durée de vie remarquable et produisent très peu de CO2.The FTS is one of the most interesting way to valorize the natural gas. After reforming the natural gas toward syngas (CO+H2), this process leads to the obtainment of sulfur-free hydrocarbons catalyzed by Coʿ and/or Feʿ. In this work, both Co and Fe have been integrated in a perovskite-type structure well known for its flexibility.LaCoxFe1-xO3 series was prepared by a sol-gel like method. Depending on the Co content x, perovskites crystallize either in the orthorhombic system if x<0.5 or in the Rrhombohedral one if xđ0.5. The reduction process study of these materials revealed that their partial reduction is possible and that only the orthorhombic perovskites allow the formation of Coʿ particles. During the reducing treatment the initial oxide crystalline structure is preserved. The extractable metal amount can be enhanced either by decreasing the calcination temperature of the raw oxide or by introducing, when preparing, a lanthanum deficiency in order to generate some defects in the crystalline lattice.The study by XRD and Mössbauer spectroscopy of the La(1-y)Co0.4Fe0.6O3-d series pointed out a core-shell phenomenon. The perovskite B cation excess is rejected through Fe as small size cores of g-Fe2O3 (cubic). On these cores crystallizes by epitaxy a cubic Co-rich perovskite-type phase without any La-deficiency. The partial reduction at 450ʿC of these nano-composites remains possible and generates a (Co-Fe)0 alloy in which the iron comes from the g-Fe2O3 cores reduction. An iron enrichment of the perovskite phase is observed during the reducing treatment.The partially reduced oxides catalytic reactivity has been studied under pressure with an on-stream set up. Catalysts are very selective toward light olefins formation, have a remarkable life time and produce a very few CO2 amount.STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF

Modeling of the Coupling of Microstructure and Macrosegregation in a Direct Chill Cast Al-Cu Billet

This is a post-peer-review, pre-copyedit version of an article published in Metallurgical and Materials Transactions A. The final authenticated version is available online at: http://dx.doi.org/10.1007/s11661-017-4238-zInternational audienceThe macroscopic multiphase flow and the growth of the solidification microstructures in the mushy zone of a direct chill (DC) casting are closely coupled. These couplings are the key to the understanding of the formation of the macrosegregation and of the nonuniform microstructure of the casting. In the present paper we use a multiphase and multiscale model to provide a fully coupled picture of the links between macrosegregation and microstructure in a DC cast billet. The model describes nucleation from inoculant particles and growth of dendritic and globular equiaxed crystal grains, fully coupled with macroscopic transport phenomena: fluid flow induced by natural convection and solidification shrinkage, heat, mass, and solute mass transport, motion of free-floating equiaxed grains and of grain-refiner particles. We compare our simulations to experiments on grain-refined and non grain-refined industrial size billets from literature. We show that a transition between dendritic and globular grain morphology triggered by the grain refinement is the key to the explanation of the differences between the macrosegregation patterns in the two billets. We further show that the grain size and morphology are strongly affected by the macroscopic transport of free-floating equiaxed grains and of grain-refiner particles

Embedded layer of Ag nanoparticles prepared by a combined PECVD/PVD process producing SiOxCy-Ag nanocomposite thin films.

International audienceStructural properties of SiOxCy–Ag nanocomposite thin films prepared by a dual process PVD–PECVD in the same reactor have been investigated. The experimental results have demonstrated the influence of a PECVD process carried out at room temperature for the growth of a dielectric matrix on the size and the distribution density of Ag nanoparticles (NPs) deposited beforehand by magnetron sputtering. The plasma during the growth of the encapsulation SiOxCy layer caused a diffusion of silver from NPs through the SiOxCy matrix associated with a decrease in the average size of nanoparticles and an increase of their distribution density. Silver diffusion is blocked at a barrier interface to form a buried layer of individual Ag NPs which, for instance, can find plasmonic applications. Silver also diffuses toward the outer surface inducing antibacterial properties. In both cases initial Ag NPs act as reservoirs for multifunctional properties of advanced nanostructured films