Experimental evaluation of contact stress during cold rolling process with optical fiber Bragg gratings sensors measurements and fast inverse method

International audienceThere is a strategic importance for the steel rolling industry to get a better understanding of the strip–roll interaction to improve roll-gap models, increase strip quality and decrease roll degradation. This requires roll-gap sensors able to measure this interaction under industrial rolling conditions and in real time in order to propose a feed-back control of process parameters. To reach these goals, this paper proposes a new roll-gap friction sensor based on an inverse method that interprets optical fiber Bragg gratings(FBG) strain measurements under the roll surface (fully embedded), which enables to evaluate contact stresses with very short computation times, compatible with real time interpretation. This elastic inverse method is analytical and relies on plane-strain and isothermal assumptions. The experimental apparatus is detailed, technical issues are clearly exposed as well as calibration procedures. Several pilot cold rolling tests have been performed at various rolling speeds and different strip thicknesses in order to demonstrate the industrial feasibility. Resulting evaluations of contact stresses are then compared with numerical simulations. Reasonable agreement is obtained for normal stress (i.e., pressure) but not for shear stress(only an order of magnitude is obtained)

Gas chromatography–mass spectrometry analysis of organic pollutants in French soils irrigated with agro-industrial wastewater

The use of agro-industrial wastewater in the agricultural sector is an interesting practice to save resources but it can bring various contaminants to the receiving soils. In this study 19 organic pollutants [8 polycyclic aromatic hydrocarbons (PAH), 6 BTEX, 4-tert-octylphenol, 4-octylphenol, 4-n-nonylphenol, tributyltin and diethylphtalate] were analyzed by gas chromatography-mass spectrometry (GC-MS) in soils irrigated with agro-industrial wastewater from sugar refinery. The soils were sampled at five different locations to evaluate the contamination heterogeneity. Microwave-assisted extraction (MAE) was performed using methanol and hexane and extraction yields ranged from 44% to 96%. The detection limits of the method were between 1.6 and 64 μg·L−1 for polycyclic aromatic hydrocarbons, 0.42 μg·L−1 for diethylphthalate, 0.77 μg·L−1 for tributyltin and until 9.8 μg·L−1 for phenol compounds. The highest contaminant concentrations measured in the soil samples, between 0.4 and 1.2 ng·g−1, were monitored for polycyclic aromatic hydrocarbons molecules, including napthalene, anthracene, fluoranthene, indeno(1,2,3-c,d)pyrene, benzo[a]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, and benzo[ghi]perylene. Toluene, ethylbenzene, xylene isomers accounted from 21 to 66 ng·g−1 (mostly toluene). Benzene, 4-tert-octylphenol, 4-octylphenol, 4-n-nonylphenol, tributyltin and diethylphtalate were not detected in soils. The proposed method enables analysis of a wide variety of regulated compounds in a unique preparation step and a unique analytical method. The mean amounts of pollutants were in agreement with measurements or estimates performed in similar contexts

The impact of aerosols on stratiform clouds over southern West Africa: a large-eddy-simulation study

Low-level stratiform clouds (LLSCs) covering a large area appear frequently during the wet monsoon season in southern West Africa. This region is also a place where different types of aerosols coexist, including biomass burning aerosols coming from central and southern Africa and aerosols emitted by local anthropogenic activities. We investigate the indirect and semi-direct effects of these aerosols on the life cycle of LLSCs by conducting a case study based on airborne and ground-based observations from the field campaign of Dynamic-Aerosol-Chemistry-Cloud-Interaction in West Africa (DACCIWA). This case is modeled using a large-eddy-simulation (LES) model with fine resolution and in situ aerosol measurements, including size distribution and chemical composition. The model has successfully reproduced the observed life cycle of the LLSC, from stratus formation to stabilization during the night and to upward development after sunrise until break-up of the cloud deck in the late afternoon. Additional sensitivity simulations using different measured aerosol profiles also suggest that aerosols can affect the cloud life cycle through both the indirect and semi-direct effects. As expected, modeled cloud microphysical features, including cloud droplet number concentration, mean radius, and thus cloud reflectivity, are all controlled by aerosol concentration. However, it is found that the variation in cloud reflectivity induced by different aerosol profiles is not always the only factor in determining the incoming solar radiation at the ground and thus for the cloud life cycle after sunrise. Instead, the difference in cloud fraction brought by dry-air entrainment from above and thus the speed of consequent evaporation – also influenced by aerosol concentration – is another important factor to consider. Clouds influenced by higher aerosol concentrations and thus with a higher number concentration and smaller sizes of cloud droplets are found to evaporate more easily and thus impose a lower cloud fraction. In addition, our sensitivity runs including versus excluding aerosol direct radiative effects have also demonstrated the impacts specifically of solar absorption by black carbon on the cloud life cycle. The semi-direct effect resulting from an excessive atmospheric heating of up to 12 K d−1 by black carbon in our modeled cases is found to lower the cloud top as well as the liquid water path, reducing surface incoming solar radiation and dry entrainment and increasing the cloud fraction.</p

Toward an Understanding of the Microstructure and Interfacial Properties of PIMs/ZIF-8 Mixed Matrix Membranes

A study integrating advanced experimental and modeling tools was undertaken to characterize the microstructural and interfacial properties of mixed matrix membranes (MMMs) composed of the zeolitic imidazolate framework ZIF-8 nanoparticles (NPs) and two polymers of intrinsic microporosity (PIM-1 and PIM-EA-TB). Analysis probed both the initial ZIF-8/PIM-1 colloidal suspensions and the final hybrid membranes. By combination of dynamic light scattering (DLS) and transmission electron microscopy (TEM) analytical and imaging techniques with small-angle X-ray scattering (SAXS), the colloidal suspensions were shown to consist mainly of two distinct kinds of particles, namely, polymer aggregates of about 200 nm in diameter and densely packed ZIF-8-NP aggregates of a few 100 nm in diameter with a 3 nm thick polymer top-layer. Such aggregates are likely to impart the granular texture of ZIF-8/PIMs MMMs as shown by SEM-XEDS analysis. At the molecular scale, modeling studies showed that the surface coverage of ZIF-8 NPs by both polymers appears not to be optimal with the presence of microvoids at the interfaces that indicates only a moderate compatibility between the polymer and ZIF-8. This study shows that the microstructure of MMMs results from a complex interplay between the ZIF-8/PIM compatibility, solvent, surface chemistry of the ZIF-8 NPs, and the physicochemical properties of the polymers such as molecular structure and rigidity

Study of two promising MOFs, MIL-91(Ti) and MIL-160(Al), for CO2 capture from flue gas

editorial reviewedFor two decades, the reduction of anthropogenic CO2 emissions from industries has become one of the most crucial issue to combat global warming. Shifting towards a low-carbon economy needs cost-effective novel carbon capture utilization or sequestration (CCUS) solutions. Current benchmark technique, absorption-regeneration amine-based process, suffers from high energy penalties due to solvent regeneration and high environmental impacts. So, adsorption process is widely considered as a promising alternative. In this regard, MOFs as adsorbent offer tremendous potential, owing to their large CO2 adsorption capacity and high CO2 affinity. However, the performances of these materials have rarely been fully evaluated in real industrial conditions. In this context, this study focuses on the determination of performances on two promising MOFs, MIL-91(Ti)1 and MIL-160 (Al)2,3 in conditions close to real industrial conditions (presence of water, NOx, SOx…) for the purpose of being used in a post-combustion capture process based on a Vacuum Pressure Swing Adsorption (VPSA) process.4686 - MOF4AIR - Metal Organic Frameworks for carbon dioxide Adsorption processes in power production and energy Intensive - Sources publiques européennes13. Climate actio

Identification of Keratinocyte Growth Factor as a Target of microRNA-155 in Lung Fibroblasts: Implication in Epithelial-Mesenchymal Interactions

International audienceBACKGROUND: Epithelial-mesenchymal interactions are critical in regulating many aspects of vertebrate embryo development, and for the maintenance of homeostatic equilibrium in adult tissues. The interactions between epithelium and mesenchyme are believed to be mediated by paracrine signals such as cytokines and extracellular matrix components secreted from fibroblasts that affect adjacent epithelia. In this study, we sought to identify the repertoire of microRNAs (miRNAs) in normal lung human fibroblasts and their potential regulation by the cytokines TNF-alpha, IL-1beta and TGF-beta. METHODOLOGY/PRINCIPAL FINDINGS: MiR-155 was significantly induced by inflammatory cytokines TNF-alpha and IL-1beta while it was down-regulated by TGF-beta. Ectopic expression of miR-155 in human fibroblasts induced modulation of a large set of genes related to "cell to cell signalling", "cell morphology" and "cellular movement". This was consistent with an induction of caspase-3 activity and with an increase in cell migration in fibroblasts tranfected with miR-155. Using different miRNA bioinformatic target prediction tools, we found a specific enrichment for miR-155 predicted targets among the population of down-regulated transcripts. Among fibroblast-selective targets, one interesting hit was keratinocyte growth factor (KGF, FGF-7), a member of the fibroblast growth factor (FGF) family, which owns two potential binding sites for miR-155 in its 3'-UTR. Luciferase assays experimentally validated that miR-155 can efficiently target KGF 3'-UTR. Site-directed mutagenesis revealed that only one out of the 2 potential sites was truly functional. Functional in vitro assays experimentally validated that miR-155 can efficiently target KGF 3'-UTR. Furthermore, in vivo experiments using a mouse model of lung fibrosis showed that miR-155 expression level was correlated with the degree of lung fibrosis. CONCLUSIONS/SIGNIFICANCE: Our results strongly suggest a physiological function of miR-155 in lung fibroblasts. Altogether, this study implicates this miRNA in the regulation by mesenchymal cells of surrounding lung epithelium, making it a potential key player during tissue injury

Les droits disciplinaires des fonctions publiques : « unification », « harmonisation » ou « distanciation ». A propos de la loi du 26 avril 2016 relative à la déontologie et aux droits et obligations des fonctionnaires

The production of tt‾ , W+bb‾ and W+cc‾ is studied in the forward region of proton–proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98±0.02 fb−1 . The W bosons are reconstructed in the decays W→ℓν , where ℓ denotes muon or electron, while the b and c quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions.The production of $t\overline{t}$, $W+b\overline{b}$ and $W+c\overline{c}$ is studied in the forward region of proton-proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an integrated luminosity of 1.98 $\pm$ 0.02 \mbox{fb}^{-1}. The $W$ bosons are reconstructed in the decays $W\rightarrow\ell\nu$, where $\ell$ denotes muon or electron, while the $b$ and $c$ quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions

Observation of the B0 → ρ0ρ0 decay from an amplitude analysis of B0 → (π+π−)(π+π−) decays

Proton–proton collision data recorded in 2011 and 2012 by the LHCb experiment, corresponding to an integrated luminosity of 3.0 fb−1 , are analysed to search for the charmless B0→ρ0ρ0 decay. More than 600 B0→(π+π−)(π+π−) signal decays are selected and used to perform an amplitude analysis, under the assumption of no CP violation in the decay, from which the B0→ρ0ρ0 decay is observed for the first time with 7.1 standard deviations significance. The fraction of B0→ρ0ρ0 decays yielding a longitudinally polarised final state is measured to be fL=0.745−0.058+0.048(stat)±0.034(syst) . The B0→ρ0ρ0 branching fraction, using the B0→ϕK⁎(892)0 decay as reference, is also reported as B(B0→ρ0ρ0)=(0.94±0.17(stat)±0.09(syst)±0.06(BF))×10−6