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Coupling textural and.stable-isotope variations in fluvial stromatolites:Comparison of Pleistocene and.recent records in NE spain

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Journal of Palaeogeography 2019年第2期8卷 150-169页

作者： C.Arenas M.C.osácar L.Auqué C.sancho Department of Earth sciences University of Zaragoza Geotransfer Group and.Institute for research on Environmental sciences of Aragón(IUCA)

Textural and.stable isotopic features of two middle Pleistocene fluvial stromatolite profiles are compared to a recent stromatolite,both formed in the river Piedra system(NE spain),to test the reliability of climatic,hydrologic and.depositional information derived from ancient *** Pleistocene stromatolites formed in a multi-domed,highly-inclined *** recent stromatolite also formed in a highly-inclined cascade of the river Piedra,the sedimentary conditions of which were periodically examined between the years 2000 and.*** Pleistocene stromatolites are formed of an alternation of 1) thin large-crystal laminae(type A),with elongated crystals up to 1 mm long,and.2) thick small-crystal laminae(type B),consisting of cyanobacterial fan-and.bushshaped *** textural and.isotopic comparison with the recent stromatolite shows that each A–B couplet corresponds to one *** type-A laminae are comparable to the macrocrystalline laminae that occur in the cool-period deposits of the recent stromatolite,and.the type-B laminae are comparable to the warm-period deposits of the recent *** temperatures(Tw),calculated from δ^(18)O_(calcite) and.present measures of δ^(18)O_(water),were similar in the Pleistocene and.recent specimens,and.close to the measured river ***,the Pleistocene stromatolites formed not far from isotopic equilibrium,as did the recent *** Pleistocene δ^(18) O_(calcite) biannual oscillation is wider in amplitude than in the recent stromatolite,which suggests larger differences in Tw through the year in the Pleistocene than at *** Pleistocene δ^(13)C_(calcite) does not show any pattern;and.the values are slightly higher than the recent *** co-evolution of δ^(18)O and.δ^(13)C is parallel in the Pleistocene stromatolites,matching the recent stromatolite *** results and.their comparison with other ancient examples prove that textural and.isotopic features in ancient stromatolites

关键词： Tufa recent and ancient stromatolites stable isotopes Biotic and abiotic laminae Intra-annual and inter-annual water temperature variations

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Hepatocellular carcinoma and.food contamination: Ochratoxin A as a great prompter

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World Journal of Gastroenterology 2013年第24期19卷 3723-3725页

作者： raphael JF Felizardo Niels os Cmara Division of Nephrology Department of Medicine Federal University of Sao PauloSao Paulo CEP 05508-900 Brazil Department of Immunology Institute of Biomedical Sciences University of S o PauloSao Paulo CEP 05508-900 Brazil

Ochratoxin A (OTA) is a secondary metabolite of Asper-gillus and.Penicillium, microorganisms that can be haz-ardous to health when present as food contaminants. OTA is a potent member of a group of mycotoxins. Prolonged exposure to mycotoxins in the diet is related to cancer, among other diseases. Hepatocellular car-cinoma (HCC) accounts for 70%-90% of primary liver cancers and.is the third leading cause of cancer-related deaths worldwide. In a recent study, Ibrahim et al proposed a correlation between the incidence of HCC and.contamination with OTA. Analysis of OTA in serum samples showed that HCC patients had the highest incidence of OTA of the subjects examined (5-fold higher than that of the control group). OTA levels were significantly increased in HCC patients. This study demonstrates that chronic exposure to high levels of OTA may be associated with a high risk of liver cancer development. Future epidemiologic studies of HCC should focus on good practices in food preparation, food storage and.the consumption of OTA-containing foods.

关键词： Ochratoxin A Mycotoxin Food contamination Hepatocellular carcinoma Liver cancer Egypt

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