Metal-induced malformations in early Palaeozoic plankton are harbingers of mass extinction

Glacial episodes have been linked to Ordovician–Silurian extinction events, but cooling itself may not be solely responsible for these extinctions. Teratological (malformed) assemblages of fossil plankton that correlate precisely with the extinction events can help identify alternate drivers of extinction. Here we show that metal poisoning may have caused these aberrant morphologies during a late Silurian (Pridoli) event. Malformations coincide with a dramatic increase of metals (Fe, Mo, Pb, Mn and As) in the fossils and their host rocks. Metallic toxins are known to cause a teratological response in modern organisms, which is now routinely used as a proxy to assess oceanic metal contamination. Similarly, our study identifies metal-induced teratology as a deep-time, palaeobiological monitor of palaeo-ocean chemistry. The redox-sensitive character of enriched metals supports emerging ‘oceanic anoxic event’ models. Our data suggest that spreading anoxia and redox cycling of harmful metals was a contributing kill mechanism during these devastating Ordovician–Silurian palaeobiological events

Validation of NIEL for >1MeV electrons in silicon using the CCD47-20

For future space missions that are visiting hostile electron radiation environments, such as ESA’s JUICE mission, it is important to understand the effects of electron irradiation on silicon devices. This paper outlines a study to validate and improve upon the Non-Ionising Energy Loss (NIEL) model for high energy electrons in silicon using Charge Coupled Devices (CCD), CMOS Imaging Sensors (CIS) and PIPS photodiodes. Initial results of radiation effects in an e2v technologies CCD47-20 after irradiation to 10 krad of 1 MeV electrons are presented with future results and analysis to be presented in future publications

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Choral church song with clapping accompaniment

Surface characteristics of the iron-oxyhydroxide layer formed during brick coatings by ESEM/EDS, ²³Na and ¹H MAS NMR, and ToF-SIMS

Brick made locally by craftsmen in Bangui (Central African Republic) was modified first by HCl activation and second by iron-oxyhydroxide impregnation through the precipitation of ferric ions by NaOH at various fixed pH values (ranging from 3 to 13). The elemental analyses of synthesized compounds were performed using ICP-AES, and their surface chemistry/properties were investigated by environmental scanning electron microscopy (ESEM/EDS), 1H and 23Na MAS NMR spectroscopy, and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The evidence of different 23Na chemical environments and the coexistence of Si and Al bound to ferrihydrite were made. The surface properties of this material which was found to be dependent upon synthesis pH, contributed to enhance metal uptake from water

Surface reconstructions of LaCo1−xFexO3 at high temperature during N2O decomposition in realistic exhaust gas composition: Impact on the catalytic properties

International audienc

Cerium modified birnessite-like MnO2 for low temperature oxidation of formaldehyde: Effect of calcination temperature

International audienceCerium modified birnessite-like MnO2 were synthesized (CexMn; x = 0.01; 0.1) from a simple and inexpensive redox method involving the reduction of potassium permanganate by sodium lactate in the presence of Ce(NO3)3 at ambient temperature. The as-synthesized samples were calcined at different temperatures (Tc: 200, 300 and 400 °C) to be tested in HCHO total oxidation in dry air at low temperature. The Ce0.01Mn catalyst calcined at 400 °C showed the best catalytic activity in HCHO oxidation with a T50 (temperature at which 50 % of HCHO was converted into CO2) of 50 °C and was found to be air and moisture stable (up to 75 %RH) upon time. The beneficial effects of a calcination step at 400 °C allowed to get enhanced asymmetric Ce-O-Mn surface interactions along with highly dispersed Ce4+/3+ related species and enhanced TCMn3+ (TC: triple corner) amounts which contributed to a great extent for its high activity in HCHO oxidation