Réutilisation maîtrisée des eaux usées : approfondir les connaissances pour lever les freins et relever les défis

Le recyclage des eaux usées représente une solution pour faire face à la demande croissante des ressources hydriques pour l’irrigation agricole. Mais leur réutilisation pose des problèmes de sécurité, de réglementation et bien sûr de techniques adaptées, que cet article nous propose de mieux comprendre

Flow, thermal and structural application of Ni-foam as volumetric solar receiver

Open-cell nickel foams with 92% porosity and uniform pore size and distribution were used in this study. The main objective of this work was to evaluate the behaviour of Ni-foam, when treated as volumetric receivers under concentrated solar radiation while improving their oxidation resistance, in order to make them attractive for such applications. The experimental investigation showed that their efficiency was depending on both materials parameters and flow conditions, the latter affecting the pressure drop and the heat transfer behaviour. The microstructural characterisation of oxide surface morphologies formed on the open-cell Ni foams exposed to concentrated solar radiation is investigated by the use of SEM and EDXS. SEM observations revealed a rapid homogeneous oxidation in the Ni-foam with three different surface oxide structures formed in relation with the process temperature. A novel slurry-based process for aluminising nickel foams while retaining their geometrical properties is applied in order to develop an aluminide-nickel intermetallic coating on a Ni foam thus enhancing the oxidation resistance. Scanning electron microscopy and X-ray diffraction were applied to assess the effectiveness of the aluminising process and determine the optimum parameters of the procedure (slurry composition, holding temperature and time).The authors would like to thank the PROcedes Materiaux et Energie Solaire (PROMES)–Centre National de la Recherche Scientifique (CNRS) for their support in the experimental procedure in the frame of the European Project SOLFACE.Publicad

Heavy Flavor Probes of Quark Matter

A brief survey of the role of heavy flavors as a probe of the state of matter produced by high energy heavy ion collisions is presented. Specific examples include energy loss, initial state gluon saturation, thermalization and flow. The formation of quarkonium bound states from interactions in which multiple heavy quark-antiquark pairs are initially produced is examined in general. Results from statistical hadronization and kinetic models are summarized. New predictions from the kinetic model for J/Psi at RHIC are presented.Comment: Based on invited plenary talk at Strange Quark Matter 2004, Cape Town, South Africa, September 15-20, 2004, references completed, published in J. Phys. G: Nucl. Part. Phys. 31 (2005) S641-S64

Variations in water use by a mature mangrove of Avicennia germinans, French Guiana

In the tropical intertidal zones, little is known on water uptake by mangroves. Transpiration rates are generally measured at leaf level, but few studies exist on water use at tree or stand levels. The objective of this study was to measure sap flow in trees of different sizes to appreciate the range of variation in water use that may exist in a site dominated by 80% mature Avicennia germinans. The results showed that from the dry to the wet season the mean water use increased from 3.2 to 5.3 dm3 d−1 in small trees (DBH ∼ 13 cm), from 11.5 to 30.8 dm3 d−1 in medium trees (∼24 cm) and from 40.8 to 64.1 dm3 d−1 in large ones (∼45 cm). Sapwood remained active up to a depth of 8 cm with radial variations within the stem. Weak correlations were obtained with VPD and net radiation. This study confirmed that transpiration was larger under low levels of salinity. Water use at stand level (∼1900 living stems ha−1) was estimated to be in the range of 5.8 to 11.8 m3 ha−1 d−1 according to the season

Status and overview of development of the Silicon Pixel Detector for the PHENIX experiment at the BNL RHIC

We have developed a silicon pixel detector to enhance the physics capabilities of the PHENIX experiment. This detector, consisting of two layers of sensors, will be installed around the beam pipe at the collision point and covers a pseudo-rapidity of | \eta | < 1.2 and an azimuth angle of | \phi | ~ 2{\pi}. The detector uses 200 um thick silicon sensors and readout chips developed for the ALICE experiment. In order to meet the PHENIX DAQ readout requirements, it is necessary to read out 4 readout chips in parallel. The physics goals of PHENIX require that radiation thickness of the detector be minimized. To meet these criteria, the detector has been designed and developed. In this paper, we report the current status of the development, especially the development of the low-mass readout bus and the front-end readout electronics.Comment: 9 pages, 8 figures and 1 table in DOCX (Word 2007); PIXEL 2008 workshop proceedings, will be published in the Proceedings Section of JINST(Journal of Instrumentation

Somatostatin triggers rhythmic electrical firing in hypothalamic GHRH neurons

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Ozone anomalies in the free troposphere during the COVID-19 pandemic

Using the CAM-chem Model, we simulate the response of chemical species in the free troposphere to scenarios of primary pollutant emission reductions during the COVID-19 pandemic. Zonally averaged ozone in the free troposphere during Northern Hemisphere spring and summer is found to be 5%-15% lower than 19-yr climatological values, in good agreement with observations. About one third of this anomaly is attributed to the reduction scenario of air traffic during the pandemic, another third to the reduction scenario of surface emissions, the remainder to 2020 meteorological conditions, including the exceptional springtime Arctic stratospheric ozone depletion. For the combined emission reductions, the overall COVID-19 reduction in northern hemisphere tropospheric ozone in June is less than 5 ppb below 400 hPa, but reaches 8 ppb at 250 hPa. In the Southern Hemisphere, COVID-19 related ozone reductions by 4%-6% were masked by comparable ozone increases due to other changes in 2020