We report on a detailed numerical study of the two-phase operation of a surface Alternating Current (AC) Dielectric Barrier Discharge (DBD) actuator. We showcase that when the quasi-periodic regime has been established, residual volume and surface charges play an important role on the discharge evolution strongly coupling the positive and negative phases. It is shown that the quasi-neutral streamer discharge found on the positive phase serves as both a positive and negative charge generator and acts as a virtual anode. As the streamer is not attached to the dielectric surface, most of the surface charging occurs during its after-burn (relaxation) phase. The positive surface charge leads to an distant zone of high electric field and thus ion drift but also interacts majorly with the negative discharge phase. During the latter, microdischarges form near the active electrode and an intense cathode layer feeds with charges the discharge volume. Each microdischarge is followed by a plasma layer formation attached to the dielectric layer expanding further at each repetition until it occupies a volume linked to the streamer elongation length and positively charged surface portion. The strong coupling between the positive and negative phases along with the strong impact of the streamer discharge on both suggest implications that have been ignored so far in terms of EHD force production and its spatiotemporal distribution.

ABSTRACTWe recently documented the neutrophil response to enterovirulent diffusely adherentEscherichia coliexpressing Afa/Dr fimbriae (Afa/Dr DAEC), using the human myeloid cell line PLB-985 differentiated into fully mature neutrophils. Upon activation, particularly during infections, neutrophils release neutrophil extracellular traps (NETs), composed of a nuclear DNA backbone associated with antimicrobial peptides, histones, and proteases, which entrap and kill pathogens. Here, using fluorescence microscopy and field emission scanning electron microscopy, we observed NET production by PLB-985 cells infected with the Afa/Dr wild-type (WT)E. colistrain C1845. We found that these NETs were able to capture, immobilize, and kill WT C1845 bacteria. We also developed a coculture model of human enterocyte-like Caco-2/TC7 cells and PLB-985 cells previously treated with WT C1845 and found, for the first time, that the F-actin cytoskeleton of enterocyte-like cells is damaged in the presence of bacterium-induced NETs and that this deleterious effect is prevented by inhibition of protease release. These findings provide new insights into the neutrophil response to bacterial infection via the production of bactericidal NETs and suggest that NETs may damage the intestinal epithelium, particularly in situations such as inflammatory bowel diseases.

Intravenous (i.v.) paracetamol is used as 1-g infusions with a maximal daily dose of 4 g/day. However, a higher initial analgesic dose could be of interest in the immediate postoperative period when the pain is maximal. The purpose of the present study was to determine in healthy subjects the safety and the pharmacokinetics of i.v. paracetamol, starting with a 2-g dose, followed by 1-g doses every 6 h, leading to a total of 5 g the first 24 h. This was an open-label, single-sequence study. The paracetamol pharmacokinetic profile was assessed in 26 subjects after both the 2-g starting dose and the 1-g doses. Safety, especially hepatotoxicity, was evaluated up to 72 h after the initial 2-g dose. Following the first 15-min i.v. administration of paracetamol 2 g, plasma concentrations ranged from 67.9+/-21.8 mug/ml (peak plasma concentration (C(max)) at the end of infusion) to 6.2+/-2.3 mug/ml (trough plasma concentration (C(min)) measured just before the next infusion) without any C(max) in the toxic range for any subject. After the repeated 1-g infusions, the plasma concentrations were approximately 35% lower than that measured after 2 g, showing the absence of accumulation. No clinical adverse events related to the drug administration nor clinically relevant changes in laboratory parameters, including biochemical signs of hepatotoxicity, were reported. After i.v. administration of paracetamol 2-g starting dose and 5 g during the first 24 h, the pharmacokinetics of paracetamol remain unchanged, with concentrations far below the toxic threshold. Overall, these results demonstrate that the i.v. administration of a 2-g starting dose of paracetamol, followed by three i.v. administrations of 1 g during the first 24 h is safe in healthy subjects.

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Introduction: Persistent peritonitis is a frequent complication of secondary peritonitis requiring additional reoperations and antibiotic therapy. This situation raises specific concerns due to microbiological changes in peritoneal samples, especially the emergence of multidrug-resistant (MDR) strains. Although this complication has been extensively studied, the rate and dynamics of MDR strains have rarely been analysed. Methods: We compared the clinical, microbiological and therapeutic data of consecutive ICU patients admitted for postoperative peritonitis either without subsequent reoperation (n = 122) or who underwent repeated surgery for persistent peritonitis with positive peritoneal fluid cultures (n = 98). Data collected on index surgery for the treatment of postoperative peritonitis were compared between these two groups. In the patients with persistent peritonitis, the data obtained at the first, second and third reoperations were compared with those of index surgery. Risk factors for emergence of MDR strains were assessed.

In the present study, the flow through the fan stage of a high bypass ratio turbofan at windmill is studied numerically. First, steady mixing plane simulations are validated against detailed experimental engine test-bed measurements, at several locations within the fan stage and close to the core/bypass flow splitter. Good agreement between the numerical and experimental results is obtained. A local flow analysis is proposed, evidencing several characteristics of the flow in windmilling: in the rotor, the size of the separation zone is found to increase from hub to tip, and in the stator, massive flow separation occurs at mid-span, which leads to the formation of two streamwise counter-rotating vortices. Then, the Nonlinear Harmonic (NLH) method is applied to a section (at 70 % of the relative span) of the fan stage. A modal analysis is performed, showing a specific behavior at windmill: the massively separated flows in the rotor and the stator entail strong rotor/stator interactions modes. Finally, the unsteady flow pattern is examined: the velocity defect of the rotor wake, which periodically increases the flow angle on the stator, is shown to trigger a periodic movement of the reattachment point at the trailing edge of the stator, associated with vortex shedding from the lower side of the vane. The implication of this qualitative flow behavior on the method to extract CFD results for comparisons with experiments is discussed.

Abstract. The aim of this paper is to present a method using both the ideas of sectional approach and moment methods in order to accurately simulate evaporation phenomena in gas-droplets flows. we propose an extension of this approach based on a more accurate representation of the droplet size number density in each section ensuring the exact conservation of two moments (as opposed to only one moment used in the classical approach). A corresponding second-order numerical scheme, with respect to space and droplet size variables, is also introduced and can be proved to be positive and to satisfy a maximum principle on the velocity and the mean droplet mass under a suitable CFL-like condition. Numerical simulations have been performed and the results confirm the accuracy of this new method even when a very coarse mesh for the droplet size variable (i.e.: a low number of sections) is used.Mathematics Subject Classification. 35Q35, 65Z05, 76T10.

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