4,706 research outputs found

    Influence of silver content on the tribomechanical behavior on Ag-TiCN bioactive coatings

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    Surface modification of bulk materials used in biomedical applications has become an important prerequisite for better biocompatibility. In particular, to overcome the particle generation, low-wear coatings based on carbon (nitrogen) and containing antimicrobial elements such as silver are promising candidates. Thus, the present work explores the potentialities of silver-containing carbonitride-based (Ag-TiCN) thin films prepared by direct current unbalanced reactive magnetron sputtering. The silver content in the coatings was varied from 0 to 26.7 at.% by changing the targets and the fraction of C2H2 and N2 in the gas mixture with Ar. The obtained Ag-TiCN based coatings were characterized in terms of composition and microstructure. Mechanical and tribological properties of the films were studied by nanoindentation and reciprocating pin-on disk testing in a fetal bovine serum solution, respectively. Raman, scanning electron microscope and energy dispersive X-ray analysis was carried out in the contact region after tribological tests to obtain information about the friction mechanism. The cytotoxicity of the coatings was assessed by in vitro tests using fibroblast cells. The coatings comprised a mixture of TiCxN1‚ąíx, Ag and a-C(N)x phases whose relative proportion varied depending on the Ag/Ti ratio. The mechanical, tribological and cytotoxicity properties were correlated with the chemical and phase composition. When the Ag/Ti ratios were below 0.20 (Ag contents b6.3 at.%) the films resulted harder (~18 GPa) with higher wear resistance (~10‚ąí6 mm3/Nm), showing similar friction coefficient (~0.3) and good biocompatibility.The authors are grateful to the financial support of the CRUP Institution by the project "Accao No E-1007/08", the Spanish Ministry of Science and Innovation (projects FUNCOAT CSD2008-00023 and HP2007-0116), Junta de Andalucia (project TEP 06782) and CSIC-FCT institutions (2007PT0043). The work was financially supported by Portuguese national funds through the FCT-Fundacao para a Ciencia e a Tecnologia, (project PTDC/CTM/102853/2008) and partially sponsored by FEDER funds through the program COMPETE - Programa Operacional Factores de Competitividade

    Lying in Wait: The Resurgence of Dengue Virus After the Zika Epidemic in Brazil

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    After the Zika virus (ZIKV) epidemic in the Americas in 2016, both Zika and dengue incidence declined to record lows in many countries in 2017-2018, but in 2019 dengue resurged in Brazil, causing ~2.1 million cases. In this study we use epidemiological, climatological and genomic data to investigate dengue dynamics in recent years in Brazil. First, we estimate dengue virus force of infection (FOI) and model mosquito-borne transmission suitability since the early 2000s. Our estimates reveal that DENV transmission was low in 2017-2018, despite conditions being suitable for viral spread. Our study also shows a marked decline in dengue susceptibility between 2002 and 2019, which could explain the synchronous decline of dengue in the country, partially as a result of protective immunity from prior ZIKV and/or DENV infections. Furthermore, we performed phylogeographic analyses using 69 newly sequenced genomes of dengue virus serotype 1 and 2 from Brazil, and found that the outbreaks in 2018-2019 were caused by local DENV lineages that persisted for 5-10 years, circulating cryptically before and after the Zika epidemic. We hypothesize that DENV lineages may circulate at low transmission levels for many years, until local conditions are suitable for higher transmission, when they cause major outbreaks

    Phagosomal removal of fungal melanin reprograms macrophage metabolism to promote antifungal immunity

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    Acknowledgements This work was supported by the Northern Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER) (NORTE-01- 0145-FEDER-000013), the Fundação para a Ciência e Tecnologia (FCT) (SFRH/BD/136814/2018 to S.M.G., SFRH/BD/141127/2018 to C.D.O., PD/BD/137680/2018 to D.A., IF/00474/2014 to N.S.O., IF/01390/2014 to E.T., IF/00959/2014 to S.C., IF/00021/2014 to R.S., PTDC/SAU-SER/29635/2017 and CEECIND/04601/2017 to C.C., and CEECIND/03628/2017 to A.C.), the Institut Mérieux (Mérieux Research Grant 2017 to C.C.), and the European Society of Clinical Microbiology and Infectious Diseases (ESCMID Research Grant 2017 to A.C.). M.G.N. was supported by a Spinoza grant of the Netherlands Organization for Scientific Research. A.A.B. was supported by the Deutsche Forschungsgemeinschaft Collaborative Research Center/Transregio TR124 FungiNet (project A1). G.D.B. was funded by the Wellcome Trust (102705), the MRC Centre for Medical Mycology and the University of Aberdeen (MR/N006364/1).Peer reviewedPublisher PD
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