172 research outputs found

    Nanoscale Visualization of Elastic Inhomogeneities at TiN Coatings Using Ultrasonic Force Microscopy

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    Ultrasonic force microscopy has been applied to the characterization of titanium nitride coatings deposited by physical vapor deposition dc magnetron sputtering on stainless steel substrates. The titanium nitride layers exhibit a rich variety of elastic contrast in the ultrasonic force microscopy images. Nanoscale inhomogeneities in stiffness on the titanium nitride films have been attributed to softer substoichiometric titanium nitride species and/or trapped subsurface gas. The results show that increasing the sputtering power at the Ti cathode increases the elastic homogeneity of the titanium nitride layers on the nanometer scale. Ultrasonic force microscopy elastic mapping on titanium nitride layers demonstrates the capability of the technique to provide information of high value for the engineering of improved coatings

    Multicopy plasmid integration in Komagataella phaffii mediated by a defective auxotrophic marker

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    Background: A commonly used approach to improve recombinant protein production is to increase the levels of expression by providing extra-copies of a heterologous gene. In Komagataella phaffii (Pichia pastoris) this is usually accomplished by transforming cells with an expression vector carrying a drug resistance marker following a screening for multicopy clones on plates with increasingly higher concentrations of an antibiotic. Alternatively, defective auxotrophic markers can be used for the same purpose. These markers are generally transcriptionally impaired genes lacking most of the promoter region. Among the defective markers commonly used in Saccharomyces cerevisiae is leu2-d, an allele of LEU2 which is involved in leucine metabolism. Cells transformed with this marker can recover prototrophy when they carry multiple copies of leu2-d in order to compensate the poor transcription from this defective allele. Results: A K. phaffii strain auxotrophic for leucine (M12) was constructed by disrupting endogenous LEU2. The resulting strain was successfully transformed with a vector carrying leu2-d and an EGFP (enhanced green fluorescent protein) reporter gene. Vector copy numbers were determined from selected clones which grew to different colony sizes on transformation plates. A direct correlation was observed between colony size, number of integrated vectors and EGFP production. By using this approach we were able to isolate genetically stable clones bearing as many as 20 integrated copies of the vector and with no significant effects on cell growth. Conclusions: In this work we have successfully developed a genetic system based on a defective auxotrophic which can be applied to improve heterologous protein production in K. phaffii. The system comprises a K. phaffii leu2 strain and an expression vector carrying the defective leu2-d marker which allowed the isolation of multicopy clones after a single transformation step. Because a linear correlation was observed between copy number and heterologous protein production, this system may provide a simple approach to improve recombinant protein productivity in K. phaffii

    Circulating microRNAs in sera correlate with soluble biomarkers of immune activation but do not predict mortality in ART treated individuals with HIV-1 infection: A case control study

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    Introduction: The use of anti-retroviral therapy (ART) has dramatically reduced HIV-1 associated morbidity and mortality. However, HIV-1 infected individuals have increased rates of morbidity and mortality compared to the non-HIV-1 infected population and this appears to be related to end-organ diseases collectively referred to as Serious Non-AIDS Events (SNAEs). Circulating miRNAs are reported as promising biomarkers for a number of human disease conditions including those that constitute SNAEs. Our study sought to investigate the potential of selected miRNAs in predicting mortality in HIV-1 infected ART treated individuals. Materials and Methods: A set of miRNAs was chosen based on published associations with human disease conditions that constitute SNAEs. This case: control study compared 126 cases (individuals who died whilst on therapy), and 247 matched controls (individuals who remained alive). Cases and controls were ART treated participants of two pivotal HIV-1 trials. The relative abundance of each miRNA in serum was measured, by RTqPCR. Associations with mortality (all-cause, cardiovascular and malignancy) were assessed by logistic regression analysis. Correlations between miRNAs and CD4+ T cell count, hs-CRP, IL-6 and D-dimer were also assessed. Results: None of the selected miRNAs was associated with all-cause, cardiovascular or malignancy mortality. The levels of three miRNAs (miRs -21, -122 and -200a) correlated with IL-6 while miR-21 also correlated with D-dimer. Additionally, the abundance of miRs -31, -150 and -223, correlated with baseline CD4+ T cell count while the same three miRNAs plus miR- 145 correlated with nadir CD4+ T cell count. Discussion: No associations with mortality were found with any circulating miRNA studied. These results cast doubt onto the effectiveness of circulating miRNA as early predictors of mortality or the major underlying diseases that contribute to mortality in participants treated for HIV-1 infection

    Multiplicity and rapidity dependence of strange hadron production in pp, pPb, and PbPb collisions at the LHC

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    Measurement of inclusive jet production and nuclear modifications in pPb collisions at root s(NN)=5.02 TeV

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    Search for dark matter particles in proton-proton collisions at √s=8 TeV using the razor variables

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    A search for dark matter particles directly produced in proton-proton collisions recorded by the CMS experiment at the LHC is presented. The data correspond to an integrated luminosity of 18.8 fb−1, at a center-of-mass energy of 8 TeV. The event selection requires at least two jets and no isolated leptons. The razor variables are used to quantify the transverse momentum balance in the jet momenta. The study is performed separately for events with and without jets originating from b quarks. The observed yields are consistent with the expected backgrounds and, depending on the nature of the production mechanism, dark matter production at the LHC is excluded at 90% confidence level for a mediator mass scale Λ below 1 TeV. The use of razor variables yields results that complement those previously published

    Searches for R-parity-violating supersymmetry in pp collisions at √s=8  TeV in final states with 0–4 leptons

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    Searches for R-parity-violating supersymmetry in pp collisions at √s=8  TeV in final states with 0–4 leptons

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    Measurement of dijet azimuthal decorrelation in pp collisions at root s=8 TeV

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    Search for supersymmetry in electroweak production with photons and large missing transverse energy in pp collisions at √s=8TeV

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    Results are reported from a search for supersymmetry with gauge-mediated supersymmetry breaking in electroweak production. Final states with photons and large missing transverse energy ( ETmiss ) were examined. The data sample was collected in pp collisions at s=8TeV with the CMS detector at the LHC and corresponds to 7.4 fb−1 . The analysis focuses on scenarios in which the lightest neutralino has bino- or wino-like components, resulting in decays to photons and gravitinos, where the gravitinos escape undetected. The data were obtained using a specially designed trigger with dedicated low thresholds, providing good sensitivity to signatures with photons, ETmiss , and low hadronic energy. No excess of events over the standard model expectation is observed. The results are interpreted using the model of general gauge mediation. With the wino mass fixed at 10 GeV above that of the bino, wino masses below 710 GeV are excluded at 95% confidence level. Constraints are also set in the context of two simplified models, for which the analysis sets the lowest cross section limits on the electroweak production of supersymmetric particles
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