Mutations within the hepatitis C virus genotype 1b E2-PePHD domain do not correlate with treatment outcome.

The hepatitis C virus (HCV) envelope protein 2 (E2) interacts in vitro with the interferon alpha (IFN-alpha)-inducible double-stranded RNA-activated protein kinase, suggesting a possible mechanism by which HCV may evade the antiviral effects of IFN-alpha. Variability in the part of the HCV E2 gene encoding the carboxy-terminal part of the protein, which includes the interaction domain (E2-PePHD), was explored in 25 patients infected with HCV genotype 1b and receiving IFN-alpha therapy. PCR products were generated and sequenced for 15 patients with a sustained response and for 10 patients with no virological response after treatment with IFN-alpha and ribavirin. PePHD amino acid sequences were obtained for isolates from serum collected before and during treatment, after 2 months in responders, and after 6 months in nonresponders. Quasispecies analysis of the pretreatment PePHD region was performed for isolates from patients displaying amino acid substitutions in this domain on direct sequencing. The E2-PePHD sequence was highly conserved in both resistant and susceptible genotype 1b strains and was identical to the prototype HCV type J sequence. No significant emergence of PePHD mutants during therapy was observed in our clonal analysis, and sporadic mutations and treatment outcomes were not found to be correlated. The PePHD sequence before or during treatment cannot be used to predict reliably the outcome of treatment in HCV type 1b-infected patients

Analyse des mutations des domaines ISDR et V3 de la protéine NS5A du virus de l'hépatite C avant le traitement par l'interféron avec ou sans ribavirine

Aim of the study. – The hepatitis C virus (HCV) non-structural NS5A protein has been controversially implicated in the resistance of HCV to interferon therapy in clinical studies. In Japan, mutations in the interferon sensitivity-determining region (ISDR) in the NS5A gene were associated with response to interferon therapy in patients infected with genotype 1b. In contrast, studies from Europe did not confirm such association. More recently, it has been suggested that the V3 domain outside the putative ISDR might also have amino acids changes that may be involved in the resistance to IFN. In this study, the relationship between NS5A mutations in ISDR and V3 domains and virological response to therapy were investigated. Materials and methods. – The NS5A gene was sequenced from 35 HCV genotype 1b infected patients at D0 of a prospective clinical trial of interferon therapy and interferon plus Ribavirin combination therapy. Results. – In the ISDR domain, we did not observe any significant differences in amino acids changes between responders (1.7 ± 1.8, n = 19, range 0–6) and non-responders (1.1 ± 0.8, n = 14, range: 0–3), (P = 0.483), to therapy before the beginning of treatment. In the V3 domain, we found more mutations in responders (6.5 ± 1.9, range: 2–11) than in non-responders (4.7 ± 1.2, range: 3–8) (P = 0.0013), before the beginning of treatment. Conclusion. – Our results confirm that, in Europe, the ISDR domain is not predictive for treatment success but suggest that the V3 domain have greater variability in responders than non-responders

Visualizing in situ translational activity for identifying and sorting slow-growing archaeal−bacterial consortia

To understand the biogeochemical roles of microorganisms in the environment, it is important to determine when and under which conditions they are metabolically active. Bioorthogonal noncanonical amino acid tagging (BONCAT) can reveal active cells by tracking the incorporation of synthetic amino acids into newly synthesized proteins. The phylogenetic identity of translationally active cells can be determined by combining BONCAT with rRNA-targeted fluorescence in situ hybridization (BONCAT-FISH). In theory, BONCAT-labeled cells could be isolated with fluorescence-activated cell sorting (BONCAT-FACS) for subsequent genetic analyses. Here, in the first application, to our knowledge, of BONCAT-FISH and BONCAT-FACS within an environmental context, we probe the translational activity of microbial consortia catalyzing the anaerobic oxidation of methane (AOM), a dominant sink of methane in the ocean. These consortia, which typically are composed of anaerobic methane-oxidizing archaea (ANME) and sulfate-reducing bacteria, have been difficult to study due to their slow in situ growth rates, and fundamental questions remain about their ecology and diversity of interactions occurring between ANME and associated partners. Our activity-correlated analyses of >16,400 microbial aggregates provide the first evidence, to our knowledge, that AOM consortia affiliated with all five major ANME clades are concurrently active under controlled conditions. Surprisingly, sorting of individual BONCAT-labeled consortia followed by whole-genome amplification and 16S rRNA gene sequencing revealed previously unrecognized interactions of ANME with members of the poorly understood phylum Verrucomicrobia. This finding, together with our observation that ANME-associated Verrucomicrobia are found in a variety of geographically distinct methane seep environments, suggests a broader range of symbiotic relationships within AOM consortia than previously thought

Corrosion behaviour of substoichiometric TiNx films produced by DC magnetron sputtering

The present work describes the corrosion behaviour of substoichiometric TiNx films obtained by dc reactive magnetron sputtering. The coatings thickness ranged from 1.7 to 4.2 µm and the nitrogen content varied between 0 and 55 at. %. According to structural characterization by XRD, the films revealed a hexagonal α-Ti phase with a strong [002] orientation for low nitrogen contents. For nitrogen contents of 20% and 30%, the ε-Ti2N phase appears with a [200] orientation and further increasing of nitrogen content showed that the δ-TiN phase was dominant. Potentiodynamic polarisation and Electrochemical Impedance Spectroscopy (EIS) techniques were used to study the corrosion properties of TiNx films when immersed in artificial sweat solutions. Results of potentiodynamic polarisation tests showed that all films have a high corrosion resistance reflected by corrosion current densities values lower than 0.7µA/cm2. Also, EIS tests corroborated the results obtained in the polarisation tests, showing that films containing low percentages of nitrogen (less than 8 %) reveal the best corrosion resistance. Further increases in nitrogen content lead to a decrease in corrosion resistance. An exception to this behaviour was found for the film, with 30 % N. This sample presents an excellent corrosion resistance which increases with the immersion time. Higher nitrogen contents (52 and 55 %) promote a relative increase in the corrosion resistance when compared with 45 and 50 at % films, but never reaching values obtained for nitrogen contents lower than 30 % at.Fundação para a Ciência e a Tecnologia - (FCT

Structural and corrosion behaviour of stoichiometric and substoichiometric TiN thin films

This paper reports the structural and electrochemical behaviour of TiN thin films prepared by d.c. reactive magnetron sputtering. x X-Ray diffraction showed the development of the hexagonal a-Ti phase, with strong w002x orientation, for low nitrogen contents. For nitrogen contents of 20 and 30 at.%, the ´-Ti N phase appears with w200x orientation. With further increasing the nitrogen 2 content, the d-TiN phase becomes dominant. Composition and the resulting changes in microstructure (crystalline phases and the lattice distortion induced by the growth conditions) are the two main parameters that seem to rule coating properties. Results of potentiodynamic polarisation tests showed that all films have a high corrosion resistance reflected by corrosion current densities below 0.7 mAycm . Also, electrochemical impedance spectroscopy tests corroborated the results obtained in the polarisation tests, 2 showing that films containing low percentages of nitrogen (less than 8%) reveal the best corrosion resistance. Further increases in nitrogen content lead to a decrease in the corrosion resistance. An exception to this behaviour was found for the film with 30 at.% N. This sample presents an excellent corrosion resistance, which in fact, increases with the immersion time. Higher nitrogen contents (52 and 55 at.%) promote a relative increase in the corrosion resistance when compared with 50 at.% films. This behaviour might be explained by the particular microstructural characteristics of the films

Structural evolution in ZrNxOy thin films as a function of temperature

Single-layered zirconium oxynitride (ZrNxOy) thin films have been deposited on steel substrates, at a constant temperature of 300 °C, by radiofrequency (rf) reactive magnetron sputtering of a pure Zr target in an argon-oxygen-nitrogen atmosphere. The variation of the flow rate of the reactive gases enabled changes in the composition and structure of the films. X-ray diffraction (XRD) and glancing incidence X-ray diffraction (GIXRD) were used to study the as-deposited films and their structural changes during or after heat treatment, from 400 to 900 °C, in controlled atmosphere and in vacuum.http://www.sciencedirect.com/science/article/B6TVV-4DPYN97-6/1/3785b40b130ad12af7221c230d2968c

Property change in ZrNxOy thin films: effect of the oxygen fraction and bias voltage

The main purpose of this work consists on the preparation of single layered zirconium oxynitride, ZrNxOy, thin films, deposited by rf reactive magnetron sputtering. The depositions were carried out by varying the process parameters such as substrate bias voltage and flow rate of the reactive gases. Independently of O content, the samples prepared with oxygen fractions revealed crystalline structures basically constituted by face centred cubic ZrN grains. Atomic force microscopy (AFM) observation showed lower values of surface roughness for low oxygen fractions and a second region where roughness grows significantly, corresponding to the highest oxygen fractions. Ion bombardment promoted a continuous smoothing of the surface up to a bias voltage of -66 V. At a bias voltage of -75 V, roughening is again observed. The small increase of film hardness in low oxygen fractions ZrNxOy films was attributed to lattice distortions occurring as a result of the possible oxygen incorporation within the ZrN lattice and also grain size reduction. Residual stresses appeared to be an important parameter to explain the observed behaviour, namely in the group of samples prepared with variation in the bias voltage. Regarding colour variations, it was observed a clear dependence of the obtained colorations with oxygen fraction.http://www.sciencedirect.com/science/article/B6TW0-4D98KMK-9/1/e9723e69843e56c913d089e23ec8ff2

Corrosion behaviour of single layered ZrNxOy thin films in artificial sweat solutions

Applications of coloured thin films can be found on the production of high-quality consumer products, such as eyeglass frames, wristwatch casings and wristbands. These components should possess scratch and corrosion resistant surfaces through the desired lifetime. Recently, metal oxynitrides, MeNxOy (Me = early transition metal) were proposed for decorative applications. In these materials, variations on the amount of oxygen allow the film properties to be tailored, originating a wide range of colours. Additionally, these materials should also fulfil the wear and corrosion requirements above referred. In the present work the corrosion behaviour of single layered zirconium oxynitride, ZrNxOy films, immersed in artificial sweat solutions, is described. Films were produced by rf reactive magnetron sputtering at a constant substrate temperature of 300 ºC, from a pure Zr target. The main processing variable was the flow rate of reactive. The corrosion resistance was evaluated by potentiodynamic polarisation tests and Electrochemical Impedance Spectroscopy (EIS) at different immersion times, at room temperature. The corrosion resistance of the films is strongly affected by the O/N ratio. A slight tendency to improving the corrosion resistance of the films was found with the increasing in the atomic fraction of oxygen. Nevertheless, pitting was found in all samples. However, the amount of pits seems to be strongly dependent not only on the composition of the film, but also on the processing-induced defects distribution.European Union, FCT- Portugal and European community (FEDER)

Tribocorrosion behaviour of zrNxOy thin films for decorative applications

The main aim of this work is the investigation of the tribocorrosion behaviour of single layered zirconium oxynitride, ZrNxOy, thin films in alternative linear regime of sliding and immersed in an artificial sweat solution at room temperature. The films were produced by rf reactive magnetron sputtering, using a pure Zr target at a constant temperature of 300º C. Two different sets of samples were produced. In the first set of films the substrate bias voltage was the main variable, whereas in the second set, the flow rate of reactive gases (oxygen/nitrogen ratio) was varied. The control of the amount of oxygen allowed the film properties to be tailored from those of covalent zirconium nitride to those of the correspondent ionic oxide. During the wear test both the open circuit potential and the corrosion current were monitored. Also, Electrochemical Impedance Spectroscopy (EIS) tests were performed before and after sliding in order to evaluate, in detail, the modification of the protective character of the coating introduced by the joint action of wear and corrosion. The modifications of the coating microstructure and/or chemical composition induced by the variation of the deposition parameters was also evaluated and correlated with the corrosion mechanisms occurring in each system