High speed visualizations of the cavitating vortices of 2D mixing layer

The present study investigates experimentally vortex dynamics of a cavitating two-dimensional mixing layer at a high Reynolds number in order to determine the effect of growth and collapse of cavitation. The dynamics and the topology of the vorticity regions corresponding to the low pressure area where cavitation effects take place are studied from the single phase state to highly cavitating conditions. LDV techniques are used in order to characterize the pattern of the turbulent single phase flow. Highspeed visualizations have been performed using a specific image processing of time series to highlight the behaviour and dynamics of the vapour phase. Visualizations, image processing and statistical analysis enable the estimation of the convective velocity and the shedding frequency of the cavitating Kelvin–Helmholtz vortices. The measured visual vapour thickness grows linearly as the Kelvin–Helmholtz instability develops and its expansion rate stays constant for the range of cavitation levels studied. The vortex pairing phenomenon is also analysed. Results show that the spatial development of the mixing area is slightly affected by the vapour phase allowing a self-similar behaviour of the mean motion

Influence of alkylphosphonic acid grafting on the electronic and magnetic properties of La2/3Sr1/3MnO3 surfaces

Self-assembled monolayers (SAMs) are highly promising materials for molecular engineering of electronic and spintronics devices thanks to their surface functionalization properties. In this direction, alkylphosphonic acids have been used to functionalize the most common ferromagnetic electrode in organic spintronics: La2/3Sr1/3MnO3 (LSMO). However, a study on the influence of SAMs grafting on LSMO electronic and magnetic properties is still missing. In this letter, we probe the influence of alkylphosphonic acids-based SAMs on the electronic and magnetic properties of the LSMO surface using different spectroscopies. We observe by X-ray photoemission and X-ray absorption that the grafting of the molecules on the LSMO surface induces a reduction of the Mn oxidation state. Ultraviolet photoelectron spectroscopy measurements also show that the LSMO work function can be modified by surface dipoles opening the door to both tune the charge and spin injection efficiencies in organic devices such as organic light-emitting diodes.The research leading to these results was financially supported by the EU project NMP3-SL-2011-263104 HINTS and ANR agency (MELAMIN 2011-NANO-021). S.T. acknowledges the European Union FP7 CIG Marie Curie Actions under project SAMSFERE (FP7/2012–321739) and the Spanish MICINN for his JdC contract. P.S. wishes to thank the Institut Universitaire de France for a junior Fellowship. The research leading to these results was partly funded by the SFB/TRR 88 ‘3MET’ from the DFG. Experiments were performed on the “DEIMOS” beamline at SOLEIL Synchrotron, France (project No. 20100960)

Unsteady Cavitation Analysis Using Phase Averaging and Conditional Approaches in a 2D Venturi Flow

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Velocity field analysis in an experimental cavitating mixing layer

International audienceThe present study was carried out on a 2D shear layer test bed where no wall effect interfered with the flow. The objective was to obtain refined database and informations concerning the behavior of the liquid phase under different cavitation levels. This reference test has provided us a well documented test case to be used for numerical simulations of the complex turbulent two-phase flow and in order to quantify the turbulence-cavitation interactions

Efficacy and tolerance of corticosteroids and methotrexate in patients with juvenile dermatomyositis: a retrospective cohort study

International audienceAbstract Objectives To assess the efficacy and tolerance of the conventional first-line treatment by MTX and CS in patients with JDM regardless of severity. Methods We conducted a monocentric retrospective study of patients with newly diagnosed JDM treated with MTX and CS from 2012 to 2020. The proportion of clinically inactive disease (CID) within 6 months of MTX initiation was evaluated using both Paediatric Rheumatology International Trials Organisation (PRINTO) criteria (evaluating muscle inactive disease) and DAS (evaluating skin inactive disease). We compared responders and non-responders using univariate analyses. Results Forty-five patients with JDM, out of which 30 (67%) severe JDM, were included. After 6 months of treatment with MTX and CS, complete CID, muscle CID and skin CID were achieved in 14/45 (31%), 19/45 (42%) and 15/45 (33%) patients, respectively. The absence of myositis-specific (MSA) or myositis-associated autoantibodies (MAA) at diagnosis was associated with a better overall, cutaneous and muscular therapeutic response, compared with antibody-positive forms (P < 0.01). Requirement for ICU (P = 0.029) and cutaneous ulcerations (P = 0.018) were associated with a less favourable muscle response. MTX was stopped due to intolerance in six patients (13%) before month 6. Conclusions Conventional first-line treatment with MTX was not efficient in a large subset of JDM patients, especially in patients with MSA-positive forms, and in patients with severe JDM. Larger, multicentre cohorts are required to confirm these data and to identify new predictive biomarkers of MTX response, in order to treat patients with JDM as early as possible with appropriate targeted drugs

A child with severe juvenile dermatomyositis treated with ruxolitinib

International audienceSir,We read with interest the article by Ladislau et al. (2018), highlighting the key role of type I interferon (IFN) in the pathophysiology of the muscle disease observed in dermatomyositis and reporting the short-term efficacy of ruxolitinib in four adult patients. Type I IFNs bind a unique common receptor (IFNAR) and subsequently activate the Janus Kinase 1 (JAK1) and tyrosine kinase 2, which, in turn, leads to the phosphorylation of signal transducer of activator of transcription (STAT) 1 and STAT2 driving the expression of IFN-stimulated genes (ISGs). Here, we describe the use of the JAK1/2 selective inhibitor ruxolitinib in a child with severe vasculopathic refractory juvenile dermatomyositis (JDM). Informed parental consent was obtained for the use of ruxolitinib on a compassionate basis and the associated experimental work, conducted in compliance with the 1975 Declaration of Helsinki [...