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Experimental data and numerical modeling of flashing jets of pressure liquefied gases
No full textInternational audienceIn industrial activities involving liquefied pressurized gases (LPG), there are several situations that can lead to hazardous flashing two-phase jets with toxic and explosive consequences. The objective of this study was to further our comprehension of such phenomena in order to develop tools that will enable operational decisions to be made within the framework of risk assessment. Experimental and numerical models were applied to study the two-phase jet resulting from any LPG releases. They focus especially on the cooling effect that was evidenced by large-scale trial experiments on releases of butane and propane carried out during the Flashing Liquids in Industrial Environment project. For LPG release, experimental observations show that the minimum temperature values are far below the boiling temperature. Experimental evidence completed by a new dedicated numerical model (thermodynamic equilibrium model) able to handle both boiling and vaporization phenomena gives a coherent picture of the two-phase flow behavior after the expansion zone. Experimental data analysis completed by comprehensive numerical simulations provides evidences that the system formed by air, vapor, and liquid droplets tends to reach an equilibrium locally
An efficient strategy, hyperspectral imaging based, for brominated plastics separation and sorting plastic in a circular economy perspective
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Évaluer les expositions cumulées aux pyréthrinoïdes des populations par la modélisation toxicocinétique
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The Use of sp-ICP-MS to Study the Behavior of Inhaled TiO2 NPs in Lung's Compartments
No full textInternational audienceThe purpose of the work was to assess the contribution of sp-ICP-MS for nanoparticle (NP) biodistribution studies, with the exemple of inhaled TiO2 NPs fate in rat lungs
Improving Quality in Nanoparticle-Induced Cytotoxicity Testing by a Tiered Inter-Laboratory Comparison Study
No full textInternational audienceThe quality and relevance of nanosafety studies constitute major challenges to ensure their key role as a supporting tool in sustainable innovation, and subsequent competitive economic advantage. However, the number of apparently contradictory and inconclusive research results has increased in the past few years, indicating the need to introduce harmonized protocols and good practices in the nanosafety research community. Therefore, we aimed to evaluate if best-practice training and inter-laboratory comparison (ILC) of performance of the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay for the cytotoxicity assessment of nanomaterials among 15 European laboratories can improve quality in nanosafety testing. We used two well-described model nanoparticles, 40-nm carboxylated polystyrene (PS-COOH) and 50-nm amino-modified polystyrene (PS-NH2). We followed a tiered approach using well-developed standard operating procedures (SOPs) and sharing the same cells, serum and nanoparticles. We started with determination of the cell growth rate (tier 1), followed by a method transfer phase, in which all laboratories performed the first ILC on the MTS assay (tier 2). Based on the outcome of tier 2 and a survey of laboratory practices, specific training was organized, and the MTS assay SOP was refined. This led to largely improved intra- and inter-laboratory reproducibility in tier 3. In addition, we confirmed that PS-COOH and PS-NH2 are suitable negative and positive control nanoparticles, respectively, to evaluate impact of nanomaterials on cell viability using the MTS assay. Overall, we have demonstrated that the tiered process followed here, with the use of SOPs and representative control nanomaterials, is necessary and makes it possible to achieve good inter-laboratory reproducibility, and therefore high-quality nanotoxicological data
Association Between Mobile Phone Radiation Exposure and the Secretion of Melatonin and Cortisol, Two Markers of the Circadian System : A Review
No full textInternational audienceThe extremely important use of mobile phones in the world, at all ages of life, including children and adolescents, leads to significant exposure of these populations to electromagnetic waves of radiofrequency. The question, therefore, arises as to whether exposure to these radiofrequencies (RFs) could lead to deleterious effects on the body's biological systems and health. In the current article, we review the effects, in laboratory animals and humans, of exposure to RF on two hormones considered as endocrine markers: melatonin, a neurohormone produced by the pineal gland and cortisol, a glucocorticosteroid synthesized by the adrenal glands. These two hormones are also considered as markers of the circadian system. The literature search was performed using PubMed, Medline, Web of Sciences (ISI Web of Knowledge), Google Scholar, and EMF Portal. From this review on RF effects on cortisol and melatonin, it appears that scientific papers in the literature are conflicting, showing effects, no effects, or inconclusive data. This implies the need for additional research on higher numbers of subjects and with protocols perfectly controlled with follow‐up studies to better determine whether the chronic effect of RF on the biological functioning and health of users exists (or not). Bioelectromagnetics
Impact of Cerebral Radiofrequency Exposures on Oxidative Stress and Corticosterone in a Rat Model of Alzheimer's Disease
No full textInternational audienceBackground: Alzheimer's disease (AD) is the most common type of neurodegenerative disease leading to dementia. Several studies suggested that mobile phone radiofrequency electromagnetic field (RF-EMF) exposures modified AD memory deficits in rodent models. Objective: Here we aimed to test the hypothesis that RF-EMF exposure may modify memory through corticosterone and oxidative stress in the Samaritan rat model of AD. Methods: Long-Evans male rats received intracerebroventricular infusion with ferrous sulphate, amyloid-beta 1-42 peptide, and buthionine-sufloximine (AD rats) or with vehicle (control rats). To mimic cell phone use, RF-EMF were exposed to the head for 1 month (5 days/week, in restraint). To look for hazard thresholds, high brain averaged specific absorption rates (BASAR) were tested: 1.5 W/Kg (15 min), 6 W/Kg (15 min), and 6 W/Kg (45 min). The sham group was in restraint for 45 min. Endpoints were spatial memory in the radial maze, plasmatic corticosterone, heme oxygenase-1 (HOl), and amyloid plaques. Results: Results indicated similar corticosterone levels but impaired memory performances and increased cerebral staining of thioflavine and of HOl in the sham AD rats compared to the controls. A correlative increase of cortical HOl staining was the only effect of RF-EMF in control rats. In AD rats, RF-EMF exposures induced a correlative increase of hippocampal HO1 staining and reduced corticosterone. Discussion: According to our data, neither AD nor control rats showed modified memory after RF-EMF exposures. Unlike control rats, AD rats showed higher hippocampal oxidative stress and reduced corticosterone with the higher BASAR. This data suggests more fragility related to neurodegenerative disease toward RF-EMF exposures
A comparison of behavior, reproductive parameters and response to pollutant between wild-type, transgenic and mutant zebrafish: could they all be considered the same "zebrafish" ?
No full textInternational audienceRegulatory assays available from the OECD for the testing of chemicals, such as endocrine disrupting chemicals (EDC) testing (TG229, TG230), can be performed with zebrafish without any recommendation regarding the strain that should be used. In addition to endpoints defined in the TG, transgenic fish could inform on mechanisms underlying EDC effects. By avoiding interference with pigmentation during imaging, use of casper background may improve tests sensitivity. In the present study, we compared 4 zebrafish lines (wild type AB, casper, cyp19a1a-eGFP and cyp19a1a-eGFP-casper) to determine whether transgene insertion and mutations could modify their basal physiology and their response to pollutant, thereby impeding their use for EDC testing. We thus compared the behavior (anxiety, sociability) and reproductive parameters (circulating vitellogenin (VTG) concentrations, female fecundity, egg viability) of control fish of the 4 lines and evaluated their responses to a model pollutant, e.g. clotrimazole. Sociability was evaluated by monitoring the time spent near congeners in a shuttle box while anxiety was evaluated using the novel tank diving test. No difference was observed between lines for either sociability or anxiety level. Concerning reproduction, no significant difference in the number of eggs laid per female, in the viability of eggs or in the female circulating VTG concentrations was noted between the 4 lines studied. Clotrimazole exposure (28 days; 250 µg/L) had similar effects in the 4 zebrafish lines despite a slightly higher sensitivity in wild type AB. Clotrimazole led to a masculinization of one part of the females, an inhibition of VTG, an inhibition of aromatase A expression (GFP measurement and qPCR) and an induction of 11-ketotestosterone. In summary, no critical difference in the behavior, reproductive parameters and response to pollutant was found between the 4 zebrafish lines, indicating that the transgene insertion and the mutations did not modify basal physiology of the fish. Therefore, their use in OECD tests for the study of EDC appears to be relevant. Further work will be conducted on strains sensitivity by evaluating dose-response effects of pollutants
Assessment of water quality through an active biomonitoring approach using three-spined stickleback (Gasterosteus aculeatus)
No full textInternational audienceThe Interreg DIADeM program (development of an integrated approach for the DIAgnosis of the water quality of the river Meuse) was created in order to develop new tools to evaluate the quality of water bodies in the Meuse waterway across the FrenchBelgian border. The project aimed to bring together the various crossborder stakeholders concerned with the protection of aquatic environments (academics, operators, users) while informing citizens of the risks caused by the degradation of water bodies. The use and the relevance of the multibiomarker approach in different model species (fish, crustacean, mussel) to assess the water quality was an important part of the program. Among the different model species used, the threespined stickleback has gained interest for biomonitoring for several years, due to its ubiquity and its tolerance to pollution. For many years, a new active strategy based on the importation of caged sticklebacks in a study site have been developed. Within the scope of the DIADeM program, the caging strategy was used with stickleback as model species to discriminate some sites in a large scale on the Meuse basin. In that way, sticklebacks were caged for 21 days upstream and downstream the wastewater treatment plants (WWTPs) of Namur (Belgiun), CharlevilleMézière (France), Bouillon (Belgium) and Avesnes-sur-Helpe (France). A battery of biomarkers was assessed to represent different physiological functions, such as innate immunity (leucocyte mortality and distribution, phagocytosis activity, respiratory burst, antioxidant system (GPx, CAT, SOD and GSH content) and oxidative damages (TBARS), biotransformation enzymes (EROD, GST), synaptic transmission (AChE) and reproduction system (spiggin and vitellogenin concentration). Physiological responses were compared between each site but also with biomarkers levels measured in sticklebacks under control conditions. Study highlighted a decrease of innate immune system downstream the WWTPs, especially through an increase of leucocyte mortality and a decrease in phagocytosis activity. A slight induction of EROD activity was also noticed downstream the WWTP of Bouillon and Namur. Moreover, the use of active biomonitoring clearly discriminated the different study sites from the reference but also amongst themselves, demonstrating the efficiency of used tools to assess the quality of water and characterize types of physiological impacts on fish
Impact of Physics Parameterizations on High-Resolution Air Quality Simulations over the Paris Region
No full textInternational audienceThe accurate simulation of meteorological conditions, especially within the planetary boundary layer (PBL), is of major importance for air quality modeling. In the present work, we have used the Weather Research and Forecast (WRF) model coupled with the chemistry transport model (CTM) CHIMERE to understand the impact of physics parameterizations on air quality simulation during a short-term pollution episode on the Paris region. A lower first model layer with a 4 m surface layer could better reproduce the transport and diffusion of pollutants in a real urban environment. Three canopy models could better reproduce a 2 m temperature (T2) in the daytime but present a positive bias from 1 to 5 degrees C during the nighttime; the multi-urban canopy scheme "building effect parameterization" (BEP) underestimates the 10 m windspeed (W10) around 1.2 m s(-1)for the whole episode, indicating the city cluster plays an important role in the diffusion rate in urban areas. For the simulation of pollutant concentrations, large differences were found between three canopy schemes, but with an overall overestimation during the pollution episode, especially for NO(2)simulation, the average mean biases of NO(2)prediction during the pollution episode were 40.9, 62.2, and 29.7 mu g m(-3)for the Bulk, urban canopy model (UCM), and BEP schemes, respectively. Meanwhile, the vertical profile of the diffusion coefficients and pollutants indicated an important impact of the canopy model on the vertical diffusion. The PBL scheme sensitivity tests displayed an underestimation of the height of the PBL when compared with observations issued from the Lidar. The YonSei University scheme YSU and Boulac PBL schemes improved the PBL prediction compared with the Mellor-Yamada-Janjic (MYJ) scheme. All the sensitivity tests, except the Boulac-BEP, could not fairly reproduce the PBL height during the pollution episode. The Boulac-BEP scheme had significantly better performances than the other schemes for the simulation of both the PBL height and pollutants, especially for the NO(2)and PM2.5(particulate matter 2.5 micrometers or less in diameter) simulations. The mean bias of the NO2, PM2.5, and PM10(particulate matter 10 micrometers or less in diameter) prediction were -5.1, 1.2, and -8.6 mu g m(-3), respectively, indicating that both the canopy schemes and PBL schemes have a critical effect on air quality prediction in the urban region