96 research outputs found

    Stable oxygen and carbon isotope composition of holocene mytilidae from the camarones coast (Chubut, argentina): Palaeoceanographic implications

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    The stable isotope composition of living and of Holocene Mytilidae shells was measured in the area of Camarones (Chubut, Argentina). The most striking results were the high δ18 O values measured in samples older than ca. 6.1 cal ka BP. In the younger samples, the δ18 O values remained substantially stable and similar to those of living specimens. Analysis of the data revealed the possibility for this isotopic shift to be driven mainly by changes in temperature probably accompanied by minor changes in salinity, suggesting cooler seawater before 6.1 cal ka BP, with a maximum possible temperature shift of ca. 5◦ C. A possible explanation of this change can be related to a northward position of the confluence zone of the Falkland and Brazilian currents. This is consistent with the data obtained in marine cores, which indicate a northerly position of the confluence in the first half of the Holocene. Our data are also in line with the changes in wind strength and position of the Southern Westerlies Wind, as reconstructed in terrestrial proxies from the Southernmost Patagonia region.Fil: Boretto, Gabriella Margherita. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Zanchetta, Giovanni. Università degli Studi di Pisa; Italia. Istituto di Geologia Ambientale e Geoingegneria; Italia. Consiglio Nazionale delle Ricerche; ItaliaFil: Consoloni, Ilaria. Università degli Studi di Pisa; ItaliaFil: Baneschi, Ilaria. Istituto di Geoscienze e Georisorse; Italia. Consiglio Nazionale delle Ricerche; ItaliaFil: Guidi, Massimo. Istituto di Geoscienze e Georisorse; Italia. Consiglio Nazionale delle Ricerche; ItaliaFil: Isola, Ilaria. Istituto Nazione di Geofisica e Vulcanologia; ItaliaFil: Bini, Monica. Consiglio Nazionale delle Ricerche; Italia. Università degli Studi di Pisa; ItaliaFil: Ragaini, Luca. Università degli Studi di Pisa; ItaliaFil: Terrasi, Filippo. Seconda Universita Degli Studi Di Napoli; ItaliaFil: Regattieri, Eleonora. Istituto di Geoscienze e Georisorse; ItaliaFil: Dallai, Luigi. Istituto di Geoscienze e Georisorse; Italia. Istituto Nazione di Geofisica e Vulcanologia; Italia. Università degli studi di Roma "La Sapienza"; Itali

    Geomorphologic Map of Northeastern Sector of San Jorge Gulf (Chubut, Argentina)

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    This paper presents a 1:100,000 scale geomorphologic map of the Northeastern sector of San Jorge Gulf (Chubut Province) in Patagonia, Argentina, covering more than 1,000 km 2. Derived from remote sensing data and validated by three field surveys, it has been compiled in order to understand the past and recent evolution of the area with particular reference to sea-level oscillation studies, for which this map is the basic tool. The very low human impact and rates of dynamic landscape change allow the preservation of extensive palaeo deposits and landforms, including those indicative of sea-level variations. The relative change of sea level dominates landscape evolution, allowing the formation of widespread marine and lagoon deposits often interfingering with fluvial deposits and reworked by aeolian process in the framework of consequent beach progradation.Facultad de Ciencias Naturales y Muse

    The effect of postmastectomy radiation therapy on breast implants. Material analysis on silicone and polyurethane prosthesis

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    The pathogenic mechanism underlying capsular contracture is still unknown. It is certainly a multifactorial process, resulting from human body reaction, biofilm activation, bacteremic seeding, or silicone exposure. The scope of the present article is to investigate the effect of hypofractionated radiotherapy protocol (2.66 Gy × 16 sessions) both on silicone and polyurethane breast implants.Silicone implants and polyurethane underwent irradiation according to a hypofractionated radiotherapy protocol for the treatment of breast cancer. After irradiation implant shells underwent mechanical, chemical, and microstructural evaluation by means of tensile testing, infrared spectra in attenuated total reflectance mode, nuclear magnetic resonance, and field emission scanning electron microscopy.At superficial analysis, irradiated silicone samples show several visible secondary and tertiary blebs. Polyurethane implants showed an open cell structure, which closely resembles a sponge. Morphological observation of struts from treated polyurethane sample shows a more compact structure, with significantly shorter and thicker struts compared with untreated sample. The infrared spectra in attenuated total reflectance mode spectra of irradiated and control samples were compared either for silicon and polyurethane samples. In the case of silicone-based membranes, treated and control specimens showed similar bands, with little differences in the treated one. Nuclear magnetic resonance spectra on the fraction soluble in CDCl3 support these observations. Tensile tests on silicone samples showed a softer behavior of the treated ones. Tensile tests on Polyurethane samples showed no significant differences.Polyurethane implants seem to be more resistant to radiotherapy damage, whereas silicone prosthesis showed more structural, mechanical, and chemical modifications

    Proteomics coupled with AhR-reporter gene bioassay for human and environmental safety assessment of sewage sludge and hydrochar

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    Today application of sewage sludge (SL) and hydrochar (HC) in agriculture is a common practice for soil conditioning and crop fertilization, however safety concerns for human and environmental health due to the presence of toxic compounds have recently been expressed. Our aim was to test the suitability of proteomics coupled with bioanalytical tools for unravelling mixture effects of these applications in human and environmental safety assessment. We conducted proteomic and bioinformatic analysis of cell cultures used in the DR-CALUX® bioassay to identify proteins differentially abundant after exposure to SL and the corresponding HC, rather than only using the Bioanalytical Toxicity Equivalents (BEQs) obtained by DR-CALUX®. DR-CALUX® cells exposed to SL or HC showed a differential pattern of protein abundance depending on the type of SL and HC extract. The modified proteins are involved in antioxidant pathways, unfolded protein response and DNA damage that have close correlations with the effects of dioxin on biological systems and with onset of cancer and neurological disorders. Other cell response evidence suggested enrichment of heavy metals in the extracts. The present combined approach represents an advance in the application of bioanalytical tools for safety assessment of complex mixtures such as SL and HC. It proved successful in screening proteins, the abundance of which is determined by SL and HC and by the biological activity of legacy toxic compounds, including organohalogens

    Geomorphologic Map of Northeastern Sector of San Jorge Gulf (Chubut, Argentina)

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    This paper presents a 1:100,000 scale geomorphologic map of the Northeastern sector of San Jorge Gulf (Chubut Province) in Patagonia, Argentina, covering more than 1,000 km 2. Derived from remote sensing data and validated by three field surveys, it has been compiled in order to understand the past and recent evolution of the area with particular reference to sea-level oscillation studies, for which this map is the basic tool. The very low human impact and rates of dynamic landscape change allow the preservation of extensive palaeo deposits and landforms, including those indicative of sea-level variations. The relative change of sea level dominates landscape evolution, allowing the formation of widespread marine and lagoon deposits often interfingering with fluvial deposits and reworked by aeolian process in the framework of consequent beach progradation.Facultad de Ciencias Naturales y Muse

    A Novel Ex Vivo Approach Based on Proteomics and Biomarkers to Evaluate the Effects of Chrysene, MEHP, and PBDE-47 on Loggerhead Sea Turtles (Caretta caretta)

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    The principal aim of the present study was to develop and apply novel ex vivo tests as an alternative to cell cultures able to evaluate the possible effects of emerging and legacy contaminants in Caretta caretta. To this end, we performed ex vivo experiments on non-invasively collected whole-blood and skin-biopsy slices treated with chrysene, MEHP, or PBDE-47. Blood samples were tested by oxidative stress (TAS), immune system (respiratory burst, lysozyme, and complement system), and genotoxicity (ENA assay) biomarkers, and genotoxic and immune system effects were observed. Skin slices were analyzed by applying a 2D-PAGE/MS proteomic approach, and specific contaminant signatures were delineated on the skin proteomic profile. These reflect biochemical effects induced by each treatment and allowed to identify glutathione S-transferase P, peptidyl-prolyl cis-trans isomerase A, mimecan, and protein S100-A6 as potential biomarkers of the health-threatening impact the texted toxicants have on C. caretta. Obtained results confirm the suitability of the ex vivo system and indicate the potential risk the loggerhead sea turtle is undergoing in the natural environment. In conclusion, this work proved the relevance that the applied ex vivo models may have in testing the toxicity of other compounds and mixtures and in biomarker discovery

    Características geoquímicas de las cuñas de hielo en Puerto Deseado (Santa Cruz, Argentina): implicancias paleoambientales y cronológicas

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    Ground wedge structures of cryogenic origin are common in the Quaternary sediments along the coast of the Patagonia, and their formation is related to climatic cold events experienced by this area in the Late Quaternary. The infilling sediments of two wedges generations were analyzed in the area of Puerto Deseado. Bulk chemistry (major elements), X-ray diffraction (XRD), morphoscopic observations with Scanning Electronic Microscope (SEM) and chemical analyses of volcanic glass shards were undertaken to provide indications about infilling sediment provenience, along with chronological constraint for wedge formation. Bulk chemistry and XRD patterns indicate a significant SiO2- enriched composition of the sediment infilling compared to the most of the loess deposits of the North Argentina and the present day dust originated in Patagonia. This was interpreted as due to the nature of the bedrock present over the Deseado Massif. SEM morphoscopic characteristics of glass shards evidence typical aeolian reworking features, with impact structures and indented edges of the volcanic fragments. Chemical analyses of the glass shards indicate that they were probably generated by the H0 eruption (17,300-17,400 cal yr BP) of the Hudson volcano. Volcanological data indicate that H0 eruption dispersed toward NE, but volcanic glasses were available for reworking due to a WNW component in the western wind direction. Over the Deseado Massif structural high the glass shards mixed with sediments enriched in SiO2, and were eventually deflated further to SE reaching the present coastal area and infilling the frost cracks. The age of the glass shards (17,300-17,400 cal yr BP) and that of the sandy layer affected by cryogenic structures (14,670±750 yr BP) well constrain to the Late Glacial both wedge generations.Las cuñas de hielo son estructuras comunes en sedimentos cuaternarios a lo largo de la costa patagónica, y su formación está relacionada con eventos climáticos fríos experimentados en esta área en el Cuaternario Tardío. Se analizaron sedimentos que rellenan dos generaciones de cuñas de hielo en la zona de Puerto Deseado. Análisis químicos de elementos mayores, difractometría de rayos X (DRX), observaciones con microscopio electrónico de barrido (SEM) y análisis químico de fragmentos de vidrio volcánico contenidos en el sedimento que rellena las cuñas proporcionaron información sobre la precedencia del relleno, además de inferir antecedentes cronológicos sobre su formación. La composición química del sedimento y la difracción de rayos X indican una composición enriquecida en SiO2 en comparación con la mayoría de los depósitos de loess del norte de Argentina y el polvo actual originado en la Patagonia. Esto fue interpretado como producto de la influencia de las rocas que constituyen el macizo del Deseado. Las características morfológicas de los fragmentos de vidrio evidencian rasgos típicos de retrabajo eólico, con presencia de estructuras de impacto y bordes dentados. Los análisis químicos de los fragmentos de vidrio son compatibles con un origen en la erupción H0 (17.300-17.400 cal yr BP) del volcán Hudson. Datos volcanológicos indican que la erupción H0 originó una pluma de dispersión hacia el NE. El material volcánico dispersado por esta erupción quedó disponible para ser retrabajado por una componente WNW de los vientos del W dominantes en la zona. Sobre el macizo del Deseado, los fragmentos de vidrio se mezclaron con sedimentos ricos en SiO2 y fueron adicionalmente, enriquecidos en este elemento hasta alcanzar el área de costa actual, rellenando las cuñas de hielo. La edad de los fragmentos de vidrio (17.300-17.400 cal yr BP) y de la capa arenosa afectada por las estructuras criogénicas (14.670±750 años BP) limitan al glacial tardío la formación de ambas generaciones de cuñas.Centro de Estudios Integrales de la Dinámica Exógen

    A Holocene tephra layer within coastal aeolian deposits north of Caleta Olivia (Santa Cruz Province, Argentina)

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    In this paper we illustrate the stratigraphy, geochronology, and geochemistry (major, minor, trace elements and Sr-isotopes) of a Holocene tephra layer found within coastal sedimentary deposits north of Caleta Olivia (Santa Cruz Province, Argentina). The stratigraphic succession comprises beach deposits with basal erosive surface resting on the local substrate (“Formación Patagonia”) followed by a poorly developed paleosoil. The paleosoil is covered by a lenticular fine grained (Mdφ: 5.2, 0.027 mm), well sorted (σφ: 1.2) volcanic ash layer and aeolian sands. The geochemical composition of shard fragments points to an origin from the Hudson volcano, located in the southern Andes, ca. 400 km to the west. The geochemistry, Sr-isotopes and the radiometric constraints (younger than the age of the underlying marine layer dated at ca. 4,100 a cal BP) further allow correlating this tephra with the so-called H2 eruption (ca. 3,900 a cal BP). This finding is of interest owing to the poor preservation potential of tephra within the Late Holocene sedimentary deposits of the Atlantic coast of Patagonia and represents the first finding of H2 eruption in this area, improving our knowledge of the dispersion of the fine-grained distal deposit of the Hudson volcanic explosive activity, thus allowing a better estimate of the eruptive dynamics and the risks associated with the Hudson volcano
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