Comparing satellite and ground-based observations of paroxysmal degassing events at Etna volcano, Italy

Mount Etna, Italy, is one of the most active volcanoes in the world, and is also regarded as one of the strongest volcanic sources of sulfur dioxide (SO2) emissions to the atmosphere. Since October 2004, an automated ultraviolet (UV) spectrometer network (FLAME) has provided ground-based SO2 measurements with high temporal resolution, providing an opportunity to validate satellite SO2 measurements at Etna. The Ozone Monitoring Instrument (OMI) on the NASA Aura satellite, which makes global daily measurements of trace gases in the atmosphere, was used to compare SO2 amount released by the volcano during paroxysmal lava-fountaining events from 2004 to present. We present the first comparison between SO2 emission rates and SO2 burdens obtained by the OMI transect technique and OMI Normalized Cloud-Mass (NCM) technique and the ground-based FLAME Mini-DOAS measurements. In spite of a good data set from the FLAME network, finding coincident OMI and FLAME measurements proved challenging and only one paroxysmal event provided a good validation for OMI. Another goal of this work was to assess the efficacy of the FLAME network in capturing paroxysmal SO2 emissions from Etna, given that the FLAME network is only operational during daylight hours and some paroxysms occur at night. OMI measurements are advantageous since SO2 emissions from nighttime paroxysms can often be quantified on the following day, providing improved constraints on Etna’s SO2 budget

Toxicity Assays in Nanodrops Combining Bioassay and Morphometric Endpoints

BACKGROUND: Improved chemical hazard management such as REACH policy objective as well as drug ADMETOX prediction, while limiting the extent of animal testing, requires the development of increasingly high throughput as well as highly pertinent in vitro toxicity assays. METHODOLOGY: This report describes a new in vitro method for toxicity testing, combining cell-based assays in nanodrop Cell-on-Chip format with the use of a genetically engineered stress sensitive hepatic cell line. We tested the behavior of a stress inducible fluorescent HepG2 model in which Heat Shock Protein promoters controlled Enhanced-Green Fluorescent Protein expression upon exposure to Cadmium Chloride (CdCl(2)), Sodium Arsenate (NaAsO(2)) and Paraquat. In agreement with previous studies based on a micro-well format, we could observe a chemical-specific response, identified through differences in dynamics and amplitude. We especially determined IC50 values for CdCl(2) and NaAsO(2), in agreement with published data. Individual cell identification via image-based screening allowed us to perform multiparametric analyses. CONCLUSIONS: Using pre/sub lethal cell stress instead of cell mortality, we highlighted the high significance and the superior sensitivity of both stress promoter activation reporting and cell morphology parameters in measuring the cell response to a toxicant. These results demonstrate the first generation of high-throughput and high-content assays, capable of assessing chemical hazards in vitro within the REACH policy framework

Volatile transport of metals in the andesitic magmatic-hydrothermal system of White Island

Volcanic gases observed at active volcanoes originate from the magma at depth. These volatiles exsolve as a result of decompression, crystallization and cooling of the silicate melt. The transport of metals in a magmatic volatile phase arises from complexation with the main volatile species, sulfur and halides. Composition of the magma, temperature, pressure and redox state have thus strong implications on metal mobility in these environments. Moreover, a variety of interactions and phase separations can affect these fluids after exsolution from the parental magma. This thesis aims at constraining the volatile transport of trace metals at White Island, a subduction-related magmatic-hydrothermal system, through a characterization and metal budget of the magmatic reservoir and the different atmospheric discharges. The metal content of the reservoir, as well as the effects of degassing and magma mixing on the magma are explored through the study of ejecta from the 1976-2000 eruptive cycle. CO₂, SO₂ and H₂O are degassing from a mafic melt at ~ 5 km depth, regularly feeding a shallower and evolved reservoir at ~ 800 m. Average contents of 164 ppm of Cu, 73 ppm of Zn, 12 ppm of Pb and 0.4 ppm of Au and Ag were detected in melt inclusions. A fraction of these metals partition into the exsolving aqueous fluid. Onset of magnetite crystallization may trigger exsolution of sulphide melt, found to contain around 30 wt% of Cu, and as much as 36 wt% Ni, 21 wt% Ag, 0.10 wt% Au in small inclusions, representing a considerable source of metals available for an aqueous fluid phase upon resorption. The volatile transport of metals is indicated by their enrichment in a variety of discharges at the surface. The hyperacidic waters of the crater lake absorb metals from the magmatic gases injected at subaqueous vents. Concentrations of ~ 12 ppm of As and Zn, 6 ppm of Cu and Pb were observed. Hydrolysis of the host rock by the reactive waters is responsible for the high cation contents of the fluids. Precipitation of secondary minerals such as silica, anhydrite, gypsum, sulfur and alunite occurs within and underneath the crater lake. The predicted speciation of metals greatly varies, dominated by CuI and FeII chloride complexes in the more reduced environment at the lake bottom, whereas CuII and FeIII are stable in the oxidized surficial waters. Arsenic is mainly present as As(OH)₃ at depth, with H₃AsO₄ dominating at the surface. Ag, Pb and Zn are complexed with chloride, and are not redox dependent. The presence of a body of molten sulfur at the bottom of the lake is indicated by sulfur spherules, both floating at the lake surface and in sediments. Pyrite crystals coat the surface of some globules, and chemical analyses reveal an enrichment in a variety of chalcophile metals (Tl, Sb, Bi, Au, As, Ag. Re, Cu). The volcanic gases emitted at fumaroles are enriched in metals compared to the magma. The effective transport of Se, Te, Sb, B, Au, As, and Bi is indicated by enrichment factors larger than 1000. In contrast, Cu is relatively depleted, suggesting deposition in the subsurface environment. Variations in composition are observed with time, mainly depending on temperature and major composition of the emissions. Values > 100 ppb of Sb, Bi, Ni, Zn, As and Se, > 10 ppb of Te, Pb, and Cu, and up to 8 ppb of Tl were recorded. Chloride is predicted to be the main ligand responsible for metal transport, even at higher temperature. The lack of thermodynamic data for complex solvated metal clusters may nevertheless bias our results. The low temperature of the studied fumaroles (maximum 192.5 °C) is in accordance with the small abundance of sulfides in the sublimates, whereas the high proportion of sulfates indicates oxidized conditions. The volcanic plume is enriched in metals such as Bi, Cd, Tl, Se, Te and Sb. The most common particles emitted are sulfates, halides, silicates, sulphuric acid and Zn ± Cu oxides. Metal emission rates are in the range of 1-10 kg/day for As, Se, Cu and Zn, 0.1-1 kg/day for Pb, Tl and Bi. Emissions of high-temperature magmatic gases are indicated by elevated SO₂/HCl ratio and the presence of Au in the particulate phase. Mass balance calculations in White Island magmatic-hydrothermal system indicate a segregation of around 4900 tons of copper per year, either accumulated from a dense brine at ~ 500 m depth, or deposited by low-density vapors on their way to the surface. Metal-rich sulfide blebs trapped in phenocrysts may also retain Cu at depth. These results thus reinforce the belief that White Island is an actively forming porphyry copper deposit

Mise au point d'un bioessai à cellules entières, pour la détection de pollutions, basé sur la technologie du promoteur de stress

L'objectif de ce travail est la mise au point d'un bioessai luminescent, permettant d'apprécier rapidement la toxicité globale d'un milieu complexe, grâce à des systèmes biologiques génétiquement modifiés. Le principe est basé sur l'association d'un promoteur de stress (hsp22 ou hsp23 de drosophile) et d'un gène rapporteur, codant une protéine bioluminescente (luciférase) ou fluorescente (EGFP), insérés dans une matrice cellulaire. Les premiers essais, réalisés grâce à des levures, ont montré que cet organisme ne correspondait pas aux critères de sensibilité de ce système. La génération de promoteurs génétiquement manipulés a permis de produire des clones recombinants de lignées cellulaires humaines (HeLa ou HepG2) et d''améliorer les performances du test. Les résultats en présence de composés toxiques tels que des métaux lourds, des perturbateurs endocriniens et d'échantillons environnementaux, ont permis l'induction de la transcription du gène rapporteur avant la manisfestatin de cytotoxicitéLYON1-BU.Sciences (692662101) / SudocSudocFranceF

Adding biomolecular recognition capability to 3D printed objects : 4D printing

International audienceThree-dimensional (3D) printing technologies will impact the biosensor community in the near future, at both the sensor prototyping level and the sensing layer organization level. The present study aimed at demonstrating the capacity of one 3D printing technique, digital light processing (DLP), to produce hydrogel sensing layers with 3D shapes that are unattainable using conventional molding procedures. The first model of the sensing layer was composed of a sequential enzymatic reaction (glucose oxidase and peroxidase), which generated a chemiluminescent signal in the presence of glucose and luminol. Highly complex objects with assembly properties (fanciful ball, puzzle pieces, 3D pixels, propellers, fluidic and multicompartments) with mono-, di-, and tricomponents configurations were achieved, and the activity of the entrapped enzymes was demonstrated. The second model was a sandwich immunoassay protocol for the detection of brain natriuretic peptide. Here, highly complex propeller shape sensing layers were produced, and the recognition capability of the antibodies was elucidated. The present study opens then the path to a totally new field of development of multiplex sensing layers, printed separately and assembled on demand to create complex sensing systems

3D-4D printed objects : new bioactive material opportunities

International audienceOne of the main objectives of 3D printing in health science is to mimic biological functions. To reach this goal, a 4D printing might be added to 3D-printed objects which will be characterized by their abilities to evolve over time and under external stimulus by modifying their shape, properties or composition. Such abilities are the promise of great opportunities for biosensing and biomimetic systems to progress towards more physiological mimicking systems. Herein are presented two 4D printing examples for biosensing and biomimetic applications using 3D-printed enzymes. The first one is based on the printing of the enzymatic couple glucose oxidase/peroxidase for the chemiluminescent detection of glucose, and the second uses printed alkaline phosphatase to generate in situ programmed and localized calcification of the printed object

Bioinspired Multi‐Activities 4D Printing Objects: A New Approach Toward Complex Tissue Engineering

International audience4D printing is an innovative approach which might in a near future lead to the achievement of highly complex smart materials. The authors describe a new strategy for the achievement of 4D printed objects with multiple biological activities. These activities are generated through the entrapment, during 3D printing, of two distinct enzymes (alkaline phosphatase and thrombin). These two enzymes give then the ability to the 4D printed object to generate bioactivities useful for in vitro tissue engineering. Indeed, it is shown that the entrapped alkaline phosphatase enables the localized and pre-programmed calcification of some 3D object parts while the diffusion of thrombin from the object permits the formation of fibrin biofilm (including living cells) directly at the surface of 3D object. Both activities and enzyme behavior within the 4D printed hydrogel are characterized through enzymatic measurements, microscopy, magnetic resonance imaging (MRI), and cell seeding

Les micropolluants dans les eaux pluviales : quelles représentations en ont les acteurs de la gestion ?Micropollutants in stormwater: how do stakeholders address this issue?

International audienceLes eaux pluviales (EP) sont un des principaux vecteurs de contamination diffuse des milieux aquatiques en micropolluants. De nouvelles stratégies de gestion doivent être envisagées par les collectivités pour répondre aux exigences de la DCE en termes de qualité des milieux. Dans ce contexte, une attention est portée à la manière dont les acteurs de la gestion se représentent les enjeux associés aux micropolluants dans les EP et les modalités d’action qu’ils mettent en œuvre ou envisagent. Il s’agit plus particulièrement d’interroger l’efficacité associée aux différents ouvrages de gestion alternative – centralisés et décentralisés – en termes de piégeage de micropolluants. Pour cela, l’exemple du Grand Lyon est choisi. Des enquêtes par entretiens semi-directifs ont été conduits auprès d’acteurs de la gestion (maîtres d’ouvrage, maîtres d’œuvre et gestionnaires) pour cerner la diversité des représentations portées sur les dispositifs techniques et sur les micropolluants. Une analyse d’un corpus, constitué de revues professionnelles spécialisées, invite à mieux comprendre les évolutions des discours tenus. Les résultats montrent que la gestion des eaux pluviales est avant tout envisagée de manière quantitative et partielle. La production de connaissances concrètes sur les performances des systèmes de gestion alternatives des eaux pluviales pourrait accompagner ces acteurs vers des démarches de gestion plus qualitatives

Biomolecules immobilization using the aryl diazonium electrografting

International audienceThe electrografting of aryl-diazonium was proven to be an efficient way to immobilize antibodies, oligonucleotides and enzymes onto conductive supports. Biomolecules chemically functionalized with aniline derivates or diazotated derivates could be used to build complex architectures acting as sensing layers for biosensors, biochips or others bioelectronic devices. Additionally, the use of SPR offers new opportunities to characterize the grafted surfaces as well as to develop label-free assays. Here, we give an overview of our group achievements in the field during the last 7 years. We highlight the applications of these functionalized surfaces in multiparametric sandwich assays, in the label free detection and imaging of macromolecular interactions by SPRi and in the immobilization of dehydrogenase via its cofactor