384 research outputs found
Charcoal evidence that rising atmospheric oxygen terminated Early Jurassic ocean anoxia
This is the final version of the article. Available from Springer Nature via the DOI in this record.The Toarcian Oceanic Anoxic Event (T-OAE) was characterized by a major disturbance to the global carbon(C)-cycle, and depleted oxygen in Earth’s oceans resulting in marine mass extinction. Numerical models predict that increased organic carbon burial should drive a rise in atmospheric oxygen (pO2) leading to termination of an OAE after ∼1 Myr. Wildfire is highly responsive to changes in pO2 implying that fire-activity should vary across OAEs. Here we test this hypothesis by tracing variations in the abundance of fossil charcoal across the T-OAE. We report a sustained ∼800 kyr enhancement of fire-activity beginning ∼1 Myr after the onset of the T-OAE and peaking during its termination. This major enhancement of fire occurred across the timescale of predicted pO2 variations, and we argue this was primarily driven by increased pO2. Our study provides the first fossil-based evidence suggesting that fire-feedbacks to rising pO2 may have aided in terminating the T-OAE.We thank the Natural Environment Research Council for funding through a studentship grant NE/L501669/1 to S.J.B. C.M.B. acknowledges funding via an ERC Starter Grant ERC-2013-StG-335891-ECOFLAM. S.P.H., T.M.L. and C.M.B. acknowledge funding from the NERC ‘JET’ grant NE/N018508/1, as well as a Royal Society Wolfson Research Merit Award supporting T.M.L
Production of Oxidants by Ion Bombardment of Icy Moons in the Outer Solar System
Our groups in Brazil, France and Italy have been active, among others in the world, in performing experiments on physical-chemical effects induced by fast ions colliding with solids (frozen gases, carbonaceous and organic materials, silicates, etc.) of astrophysical interest. The used ions span a very large range of energies, from a few keV to hundreds MeV. Here we present a summary of the results obtained so far on the formation of oxidants (hydrogen peroxide and ozone) after ion irradiation of frozen water, carbon dioxide and their mixtures. Irradiation of pure water ice produces hydrogen peroxide whatever is the used ion and at different temperatures. Irradiation of carbon dioxide and water frozen mixtures result in the production of molecules among which hydrogen peroxide and ozone. The experimental results are discussed in the light of the relevance they have to support the presence of an energy source for biosphere on Europa and other icy moons in the outer Solar System.This research has been supported by the European COST Action CM0805: The Chemical Cosmos.Boduch, P.; Da Silveira, EF.; Domaracka, A.; Gomis Hilario, O.; Lv, XY.; Palumbo, ME.; Pilling, S.... (2011). Production of Oxidants by Ion Bombardment of Icy Moons in the Outer Solar System. Advances in Astronomy. 1-10. doi:10.1155/2011/327641S11
Warm afterglow from the Toarcian Oceanic Anoxic Event drives the success of deep-adapted brachiopods
This is the final version. Available from the publisher via the DOI in this record.Many aspects of the supposed hyperthermal Toarcian Oceanic Anoxic Event (T-OAE, Early Jurassic, c.
182Ma) are well understood but a lack of robust palaeotemperature data severely limits reconstruction
of the processes that drove the T-OAE and associated environmental and biotic changes. New oxygen
isotope data from calcite shells of the benthic fauna suggest that bottom water temperatures in the
western Tethys were elevated by c. 3.5°C through the entire T-OAE. Modelling supports the idea that
widespread marine anoxia was induced by a greenhouse-driven weathering pulse, and is compatible
with the OAE duration being extended by limitation of the global silicate weathering fux. In the
western Tethys Ocean, the later part of the T-OAE is characterized by abundant occurrences of the
brachiopod Soaresirhynchia, which exhibits characteristics of slow-growing, deep sea brachiopods. The
unlikely success of Soaresirhynchia in a hyperthermal event is attributed here to low metabolic rate,
which put it at an advantage over other species from shallow epicontinental environments with higher
metabolic demand.Natural Environment Research Council (NERC
Base of the Toarcian Stage of the Lower Jurassic defined by the Global Boundary Stratotype Section and Point (GSSP) at the Peniche section (Portugal)
This is the final version of the article. Available from the publisher via the DOI in this record.The Global Stratotype Section and Point (GSSP) for the base of Toarcian Stage, Lower Jurassic, is placed at the base of micritic limestone bed 15e at Ponta do Trovão (Peniche, Lusitanian Basin, Portugal; coordinates: 39°22'15''N, 9°23'07''W), 80km north of Lisbon, and coincides with the mass occurrence of the ammonite Dactylioceras (Eodactylites). The Pliensbachian/ Toarcian boundary (PLB/TOA) is contained in a continuous section forming over 450m of carbonate-rich sediments. Tectonics, syn-sedimentary disturbance, metamorphism or significant diagenesis do not significantly affect this area. At the PLB/TOA, no vertical facies changes, stratigraphical gaps or hiatuses have been recorded. The base of the Toarcian Stage is marked in the bed 15e by the first occurrence of D. (E.) simplex, co-occurring with D. (E.) pseudocommune and D. (E.) polymorphum. The ammonite association of D. (Eodactylites) ssp. and other species e.g. Protogrammoceras (Paltarpites) cf. paltum, Lioceratoides aff. ballinense and Tiltoniceras aff. capillatum is particularly significant for the boundary definition and correlation with sections in different basins. Ammonites of the PLB/ TOA are taxa characteristic of both the Mediterranean and Northwest European provinces that allow reliable, global correlations. The PLB/TOA is also characterized by other biostratigraphical markers (brachiopods, calcareous nannofossils, ostracods and benthic foraminifers) and by high-resolution stable carbon and oxygen isotopes, and 87Sr/86Sr ratios that show distinctive changes just above the PLB/TOA, thus providing additional, powerful tools for global correlations. The PBL-TOA lies at the end of a second (and third) order cycle of sea-level change, and the top of bed 15e is interpreted as a sequence boundary. Cyclostratigraphy analysis is available for the Lower Toarcian of Ponta do Trovão. Detailed correlations with the Almonacid de la Cuba section (Iberian Range, Spain) provide complementary data of the ammonite succession in the Northwest European Hawskerense and Paltum Subzones, and magnetostratigraphical data that allow supraregional correlations. The proposal was voted on by the Toarcian Working Group in June, 2012, and by the International Subcommission on Jurassic Stratigraphy in September, 2012, approved by the ICS in November, 2014, and ratified by the IUGS in December, 2014. With this Toarcian GSSP, all international stages of the Lower Jurassic have been officially defined.Several scientists have been members of the Toarcian Working Group. We would like to acknowledge all of them. We are also grateful to the ISJS and ICS members who have made valuable comments on a previous version of this manuscript. We warmly thank Marc Philippe for his help with the literature on Pliensbachian/Toarcian continental successions. We warmly thank Christian Meister and Jim Ogg for their helpful review. Constructive remarks by Jim Ogg on an early
version of the paper were greatly appreciated. We also acknowledge the precious help of David Besson for providing the ammonite specimens from the Mouterde collection (Musée des Confluences, Lyon). Ammonite photographs were taken by Emmanuel Robert (Collections de Géologie de Lyon). This paper is dedicated to the memory of Abbé René Mouterde and Serge Elmi, who died in 2007 after having been for years the main supporters of the Peniche section as GSSP of Toarcian Stage. Calcareous nannofossil slides are curated at the Collections de Géologie de Lyon (No. FSL 766535-766617). This work has been supported by the BIOSCALES Project (POCTI/
36438/PAL/2000), coordinated by the Universidade NOVA de Lisboa; R. B. Rocha thanks the support of A. F. Soares, J. C. Kullberg, P. S. Caetano and P. H. Verdial. Financial support was provided to L. V. Duarte, S. Pinto and M. C. Cabral by Projects PDCTE/CTA/44907/2002 and PTDC/CTE-GIX/098968/2008
Flavonoids in Kidney Health and Disease
This review summarizes the latest advances in knowledge on the effects of flavonoids on
renal function in health and disease. Flavonoids have antihypertensive, antidiabetic, and
antiinflammatory effects, among other therapeutic activities. Many of them also exert
renoprotective actions that may be of interest in diseases such as glomerulonephritis,
diabetic nephropathy, and chemically-induced kidney insufficiency. They affect several
renal factors that promote diuresis and natriuresis, which may contribute to their
well-known antihypertensive effect. Flavonoids prevent or attenuate the renal injury
associated with arterial hypertension, both by decreasing blood pressure and by acting
directly on the renal parenchyma. These outcomes derive from their interference with
multiple signaling pathways known to produce renal injury and are independent of their
blood pressure-lowering effects. Oral administration of flavonoids prevents or ameliorates
adverse effects on the kidney of elevated fructose consumption, high fat diet, and
types I and 2 diabetes. These compounds attenuate the hyperglycemia-disrupted renal
endothelial barrier function, urinarymicroalbumin excretion, and glomerular hyperfiltration
that results from a reduction of podocyte injury, a determinant factor for albuminuria
in diabetic nephropathy. Several flavonoids have shown renal protective effects against
many nephrotoxic agents that frequently cause acute kidney injury (AKI) or chronic kidney
disease (CKD), such as LPS, gentamycin, alcohol, nicotine, lead or cadmium. Flavonoids
also improve cisplatin- or methotrexate-induced renal damage, demonstrating important
actions in chemotherapy, anticancer and renoprotective effects. A beneficial prophylactic
effect of flavonoids has been also observed against AKI induced by surgical procedures
such as ischemia/reperfusion (I/R) or cardiopulmonary bypass. In several murine models
of CKD, impaired kidney function was significantly improved by the administration of
flavonoids from different sources, alone or in combination with stem cells. In humans,
cocoa flavanols were found to have vasculoprotective effects in patients on hemodialysis.
Moreover, flavonoids develop antitumor activity against renal carcinoma cells with no
toxic effects on normal cells, suggesting a potential therapeutic role in patients with renal
carcinoma.This study was supported by grants from the Carlos III Health
Institute of Spain, and the Red de Investigación Renal REDinREN
number 5 012/0021. FEDER una manera de hacer Europa
Effects of orofacial myofunctional therapy on masticatory function in individuals submitted to orthognathic surgery: a randomized trial
Synthesis and characterization of aliphatic polyesters from glycerol, by-product of biodiesel production, and adipic acid
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