Adhesion of human gingival fibroblasts/Streptococcus mitis co-culture on the nanocomposite system Chitlac-nAg

10noComposite materials are increasingly used as dental restoration. In the field of biomaterials, infections remain the main reason of dental devices failure. Silver, in the form of nanoparticles (AgNPs), ions and salt, well known for its antimicrobial properties, is used in several medical applications in order to avoid bacterial infection. To reduce both bacterial adhesion to dental devices and cytotoxicity against eukaryotic cells, we coated BisGMA/TEGDMA methacrylic thermosets with a new material, Chitlac-nAg, formed by stabilized AgNPs with a polyelectrolyte solution containing Chitlac. Here we analyzed the proliferative and adhesive ability of human gingival fibroblasts (HGFs) on BisGMA/TEGDMA thermosets uncoated and coated with AgNPs in a coculture model system with Streptococcus mitis. After 48 h, HGFs well adhered onto both surfaces, while S. mitis cytotoxic response was higher in the presence of AgNPs coated thermosets. After 24 h thermosets coated with Chitlac as well as those coated with Chitlac-nAg exerted a minimal cytotoxic effect on HGFs, while after 48 h LDH release raised up to 20 %. Moreover the presence of S. mitis reduced this release mainly when HGFs adhered to Chitlac-nAg coated thermosets. The reduced secretion of collagen type I was significant in the presence of both surfaces with the co-culture system even more when saliva is added. Integrin β1 localized closely to cell membranes onto Chitlac-nAg thermosets and PKCα translocated into nuclei. These data confirm that Chitlac-nAg have a promising utilization in the field of restorative dentistry exerting their antimicrobial activity due to AgNPs without cytotoxicity for eukaryotic cells.openopenCataldi, Amelia; Gallorini, Marialucia; Di Giulio, Mara; Guarnieri, Simone; Mariggiò, Maria Addolorata; Traini, Tonino; Di Pietro, Roberta; Cellini, Luigina; Marsich, Eleonora; Sancilio, SilviaCataldi, Amelia; Gallorini, Marialucia; Di Giulio, Mara; Guarnieri, Simone; Mariggiò, Maria Addolorata; Traini, Tonino; Di Pietro, Roberta; Cellini, Luigina; Marsich, Eleonora; Sancilio, Silvi

Coherent structures in wall turbulence with drag reduction

LAUREA MAGISTRALEIn questo lavoro vengono studiati i meccanismi fisici che si manifestano quando una corrente subisce una variazione di attrito dovuta ad una tecnica di controllo come la parete oscillante o le onde di velocità trasversale viaggianti in direzione della corrente. Per fare ciò 5 Direct Numerical Simulations (DNS) di canale piano turbolento a Reτ = 200 sono stati utilizzati: un primo caso privo di forzamento, due casi con parete oscillante e due casi con onde viaggianti. La prima parte della tesi è basata sullo studio delle Strutture Coerenti (CS) presenti nella corrente, in particolare dei Quasi-Streamwise Vortices (QSV). La speranza è quella di mettere in relazione i cambiamenti indotti dal controllo sulla corrente con le variazione della dinamica dei QSV e conseguentemente comprendere come e perché l’attrito viene modificato. Per far ciò sono stati sviluppati diversi programmi che ci hanno consentito di estrarre i QSV, farne una media condizionata e ricavare alcune quantità fisiche di rilievo (come gli sforzi di Reynolds). Da ciò è stato possibile confermare la presenza degli stessi meccanismi di soppressione degli eventi Q2 e miglioramento degli eventi Q4 evidenziati in Yakeno et al. [2014] per i vortici sottoposti ad un controllo con parete oscillante, mentre per la prima volta ne è stata osservata la rilevanza per le onde viaggianti. L’ultima parte del lavoro si concentra sulla proposta di una formula che consenta di prevedere, dato il numero d’onda kx e la frequenza ω associati ad un’onda viaggiante, la variazione di attrito, in modo da provare la rilevanza dei fenomeni fisici osservati nel corso della tesi. Per far ciò siamo partiti nuovamente da una proposta di Yakeno et al. [2014] che è stata modificata tenendo conto dell’accelerazione del GSL e di un fenomeno di rotazione dei QSV osservato per le onde viaggianti che abbiamo legato alla modi- fica dello stato di sforzo dovuto alla derivata di w in direzione x. Una formulazione alternativa, legata alla derivata seconda di w in y, è stata altresì proposta, dopo aver osservato la sorprendente somiglianza tra la mappa di riduzione di attrito di Yakeno et al. [2014] e la rappresentazione di tale quantità nello spazio (kx, ω) come suggerito in Duque-Daza et al. [2012]. A tal proposito bisogna tener presente che quest’ultima analisi prende in considerazione la crescita di perturbazioni di un flusso base considerate le equazioni di Navier- Stokes linearizzate: ciò suggerisce la rilevanza di fenomeni lineari per la riduzione di attrito.In this work the physical mechanisms which appear when a flow undergo a drag variation due to a control technique as oscillating wall or streamwise waves of spanwise velocity are studied. To do that 5 Direct Numerical Simulation (DNS) of a turbulent channel flow at Reτ = 200 were used: a first case without forcing, two cases with oscillating wall and two cases with travelling waves. The first part of the thesis is based on the study of the Coherent Structures (CS) of the flow, in particular of the Quasi-Streamwise Vortices (QSV). The hope is to relate the changes induced by the control on the flow with the variation of the QSV dynamics and subsequently understand how and why the friction is modified. To do that several programs, that allowed us to educe QSV, conditionally average them and extract some relevant physical quantities (as Reynolds stresses), were developed. From that it was possible to confirm the presence of the same Q2 suppression and Q4 enhancement mechanisms underlined in Yakeno et al. [2014] for the vortices under an oscillating wall control, while for the first time their relevance for travel- ling waves was observed. The last part of the work is focused on the proposal of a formula which allows to predict, given the wavenumber kx and the frequency ω associated to a travelling wave, the friction variation, in order to prove the relevance of the physical phenomena observed during the thesis. To do that we started again from a proposal of Yakeno et al. [2014] which was modified taking into account the GSL acceleration and the QSV-roll phenomenon we observed for the travelling waves, that we related to the modification of the stress state due to the x derivative of w. An alternative formulation, based on the y second derivative of w, was proposed, observing the striking similarity between the drag reduction map of Yakeno et al. [2014] and the repre- sentation of that quantity in the (kx, ω) space as suggested in Duque-Daza et al. [2012]. Regarding that, we must take into account that this last analysis studies the growth of perturbations in a base flow considering linearized Navier-Stokes equations: this suggest a relevance of linear phenomena for the friction reduction

The Termination of Intra-EU Investor- state Arbitration and the Enforceability of Intra-EU Awards in the United States District Courts

Over the past 20 years, the gradual termination of ISDS mechanisms in intra-EU BITs and the ECT have received considerable attention within the EU. The CJEU judgments in Achmea, Komstroy and PL Holdings accelerated this termination process. This article aims to contribute to the debate. After providing an assessment of how the EU anti-investment arbitration policy started and is gradually leading to a complete termination of intra-EU investment arbitration, the article analyses arbitral tribunals’ possible reaction to Komstroy. The article proposes that nothing suppresses tribunals of the jurisdiction to hear intra-EU disputes under Article 26 ECT and Kompetenz-Kompetenz. At the same time, the possibility for tribunals to render awards that are enforceable within the EU is seriously at stake. Aware of that, European investors are seeking enforcement of favourable intra-EU awards outside the EU. One of the preferred venues is the US District court for the District of Columbia which, however, has not yet taken a firm position on the matter. The article concludes that while arbitration under the intra-EU BITs is barely breathing, under the ECT investors should prefer the recourse to ICSID. In the final section, it discusses whether the enhanced protection of international investment law is still offered to European investors while investing in the EU

The photon veto system in the NA62 experiment

The NA62 experiment at CERN SPS aims to collect O(100)K+ → π+νν events in two years of data taking with a S/B ratio of about 10:1. The Branching Ratio (BR) for this decay is ∼ 10 −11 and can be predicted with minimal theoretical uncertainties, making it a sensitive probe for New Physics. The guiding principles for the construction of the NA62 detectors are an accurate particle ID, precise timing and excellent veto efficiency. In particular, the veto inefficiency for photons from K+ → π+π0 decays should be smaller than 10−8. The photon veto system of NA62 consists of three detectors covering different angular regions: Large Angle Veto (LAV), Liquid Krypton calorimeter (LKr) and Small Angle Veto (SAV). The status of the project and present preliminary results from the recent tests will be reviewed

Recent NA48/2 and NA62 results

The NA48/2 Collaboration at CERN has accumulated and analysed unprecedented statistics of rare kaon decays in the $K_{e4}$ modes: $K_{e4}(+-)$ ($K^\pm \to \pi^+ \pi^- e^\pm \nu$) and $K_{e4}(00)$ ($K^\pm \to \pi^0 \pi^0 e^\pm \nu$) with nearly one percent background contamination. It leads to the improved measurement of branching fractions and detailed form factor studies. New final results from the analysis of 381 $K^\pm \to \pi^\pm \gamma \gamma$ rare decay candidates collected by the NA48/2 and NA62 experiments at CERN are presented. The results include a decay rate measurement and fits to Chiral Perturbation Theory (ChPT) description.Comment: Prepared for the Proceedings of "Moriond QCD and High Energy Interactions. March 22-29 2014." conferenc

Prospects for K+→π+ννˉK^+ \to \pi^+ \nu \bar{ \nu } at CERN in NA62

The NA62 experiment will begin taking data in 2015. Its primary purpose is a 10% measurement of the branching ratio of the ultrarare kaon decay $K^+ \to \pi^+ \nu \bar{ \nu }$, using the decay in flight of kaons in an unseparated beam with momentum 75 GeV/c.The detector and analysis technique are described here.Comment: 8 pages for proceedings of 50 Years of CP

Spatial discretization effects in spanwise forcing for turbulent drag reduction

Wall-based spanwise forcing has been experimentally used with success by Auteri et al. (Phys. Fluids, vol. 22, 2010, 115103) to obtain large reductions of turbulent skin-friction drag and considerable energy savings in a pipe flow. The spatial distribution of the azimuthal wall velocity used in the experiment was not continuous, but piecewise constant. The present study is a numerical replica of the experiment, based on a set of direct numerical simulations (DNS); its goal is the identification of the effects of spatially discrete forcing, as opposed to the idealized sinusoidal forcing considered in the majority of numerical studies. Regardless of the discretization, with DNS the maximum drag reduction is found to be larger: the flow easily reaches complete relaminarization, whereas the experiment was capped at 33 % drag reduction. However, the key result stems from the observation that, for the piecewise-constant forcing, the apparent irregularities of the experimental data appear in the simulation data too. They derive from the rich harmonic content of the discontinuous travelling wave, which alters the drag reduction of the sinusoidal forcing. A detailed understanding of the contribution of each harmonic reveals that, whenever for example technological limitations constrain one to work far from the optimal forcing parameters, a discrete forcing may perform very differently from the corresponding ideal sinusoid, and in principle can outperform it. However, care should be exercised in comparison, as discrete and continuous forcing have different energy requirements

Differential branching fraction and angular analysis of Λb0→Λμ+μ−\Lambda^{0}_{b} \rightarrow \Lambda \mu^+\mu^- decays

The differential branching fraction of the rare decay $\Lambda^{0}_{b} \rightarrow \Lambda \mu^+\mu^-$ is measured as a function of $q^{2}$, the square of the dimuon invariant mass. The analysis is performed using proton-proton collision data, corresponding to an integrated luminosity of 3.0 \mbox{ fb}^{-1}, collected by the LHCb experiment. Evidence of signal is observed in the $q^2$ region below the square of the $J/\psi$ mass. Integrating over 15 < q^{2} < 20 \mbox{ GeV}^2/c^4 the branching fraction is measured as d\mathcal{B}(\Lambda^{0}_{b} \rightarrow \Lambda \mu^+\mu^-)/dq^2 = (1.18 ^{+ 0.09} _{-0.08} \pm 0.03 \pm 0.27) \times 10^{-7} ( \mbox{GeV}^{2}/c^{4})^{-1}, where the uncertainties are statistical, systematic and due to the normalisation mode, $\Lambda^{0}_{b} \rightarrow J/\psi \Lambda$, respectively. In the $q^2$ intervals where the signal is observed, angular distributions are studied and the forward-backward asymmetries in the dimuon ($A^{l}_{\rm FB}$) and hadron ($A^{h}_{\rm FB}$) systems are measured for the first time. In the range 15 < q^2 < 20 \mbox{ GeV}^2/c^4 they are found to be A^{l}_{\rm FB} = -0.05 \pm 0.09 \mbox{ (stat)} \pm 0.03 \mbox{ (syst)} and A^{h}_{\rm FB} = -0.29 \pm 0.07 \mbox{ (stat)} \pm 0.03 \mbox{ (syst)}.Comment: 27 pages, 10 figures, Erratum adde

Measurement of the mass and lifetime of the Ωb−\Omega_b^- baryon

A proton-proton collision data sample, corresponding to an integrated luminosity of 3 fb$^{-1}$ collected by LHCb at $\sqrt{s}=7$ and 8 TeV, is used to reconstruct $63\pm9$ $\Omega_b^-\to\Omega_c^0\pi^-$, $\Omega_c^0\to pK^-K^-\pi^+$ decays. Using the $\Xi_b^-\to\Xi_c^0\pi^-$, $\Xi_c^0\to pK^-K^-\pi^+$ decay mode for calibration, the lifetime ratio and absolute lifetime of the $\Omega_b^-$ baryon are measured to be \begin{align*} \frac{\tau_{\Omega_b^-}}{\tau_{\Xi_b^-}} &= 1.11\pm0.16\pm0.03, \\ \tau_{\Omega_b^-} &= 1.78\pm0.26\pm0.05\pm0.06~{\rm ps}, \end{align*} where the uncertainties are statistical, systematic and from the calibration mode (for $\tau_{\Omega_b^-}$ only). A measurement is also made of the mass difference, $m_{\Omega_b^-}-m_{\Xi_b^-}$, and the corresponding $\Omega_b^-$ mass, which yields \begin{align*} m_{\Omega_b^-}-m_{\Xi_b^-} &= 247.4\pm3.2\pm0.5~{\rm MeV}/c^2, \\ m_{\Omega_b^-} &= 6045.1\pm3.2\pm 0.5\pm0.6~{\rm MeV}/c^2. \end{align*} These results are consistent with previous measurements.Comment: 11 pages, 5 figures, All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-008.htm