Lifetime of an ocean island volcano feeder zone: constraints from U-Pb dating on coexisting zircon and baddeleyite, and 40Ar/39Ar age determinations, Fuerteventura, Canary Islands

High-precision isotope dilution - thermal ionization mass spectrometry (ID-TIMS) U-Pb zircon and baddeleyite ages from the PX1 vertically layered mafic intrusion Fuerteventura, Canary Islands, indicate initiation of magma crystallization at 22.10 +/- 0.07 Ma. The magmatic activity lasted a minimum of 0.52 Ma. Ar-40/Ar-39 amphibole dating yielded ages from 21.9 +/- 0.6 to 21.8 +/- 0.3, identical within errors to the U-Pb ages, despite the expected 1% theoretical bias between Ar-40/Ar-39 and U-Pb dates. This overlap could result from (i) rapid cooling of the intrusion (i. e., less than the 0.3 to 0.6 Ma 40Ar/39Ar age uncertainties) from closure temperatures (T-c) of zircon (699-988 degrees C) to amphibole (500-600 degrees C); (ii) lead loss affecting the youngest zircons; or (iii) excess argon shifting the plateau ages towards older values. The combination of the Ar-40/Ar-39 and U/Pb datasets implies that the maximum amount of time PX1 intrusion took to cool below amphibole T-c is 0.8 Ma, suggesting PX1 lifetime of 520 000 to 800 000 Ma. Age disparities among coexisting baddeleyite and zircon (22.10 +/- 0.07/0.08/0.15 Ma and 21.58 +/- 0.15/0.16/0.31 Ma) in a gabbro sample from the pluton margin suggest complex genetic relationships between phases. Baddeleyite is found preserved in plagioclase cores and crystallized early from low silica activity magma. Zircon crystallized later in a higher silica activity environment and is found in secondary scapolite and is found close to calcite veins, in secondary scapolite that recrystallised from plagioclase. close to calcite veins. Oxygen isotope delta O-18 values of altered plagioclase are high (+7.7), indicating interaction with fluids derived from host-rock carbonatites. The coexistence of baddeleyite and zircon is ascribed to interaction of the PX1 gabbro with CO2-rich carbonatite-derived fluids released during contact metamorphism.

Methodology used in studies reporting chronic kidney disease prevalence : a systematic literature review.

BACKGROUND: Many publications report the prevalence of chronic kidney disease (CKD) in the general population. Comparisons across studies are hampered as CKD prevalence estimations are influenced by study population characteristics and laboratory methods. METHODS: For this systematic review, two researchers independently searched PubMed, MEDLINE and EMBASE to identify all original research articles that were published between 1 January 2003 and 1 November 2014 reporting the prevalence of CKD in the European adult general population. Data on study methodology and reporting of CKD prevalence results were independently extracted by two researchers. RESULTS: We identified 82 eligible publications and included 48 publications of individual studies for the data extraction. There was considerable variation in population sample selection. The majority of studies did not report the sampling frame used, and the response ranged from 10 to 87%. With regard to the assessment of kidney function, 67% used a Jaffe assay, whereas 13% used the enzymatic assay for creatinine determination. Isotope dilution mass spectrometry calibration was used in 29%. The CKD-EPI (52%) and MDRD (75%) equations were most often used to estimate glomerular filtration rate (GFR). CKD was defined as estimated GFR (eGFR) <60 mL/min/1.73 m(2) in 92% of studies. Urinary markers of CKD were assessed in 60% of the studies. CKD prevalence was reported by sex and age strata in 54 and 50% of the studies, respectively. In publications with a primary objective of reporting CKD prevalence, 39% reported a 95% confidence interval. CONCLUSIONS: The findings from this systematic review showed considerable variation in methods for sampling the general population and assessment of kidney function across studies reporting CKD prevalence. These results are utilized to provide recommendations to help optimize both the design and the reporting of future CKD prevalence studies, which will enhance comparability of study results.

Estimativa da incerteza de medição em análise cromatográfica: abordagem sobre a quantificação de carbamato de etila em cachaça

The measurement uncertainty is useful to estimate the confidence of analytical results. Nowadays, a result without the uncertainty statement cannot be considered reliable, but the scientific literature still lacks examples of the estimate of the measurement uncertainty. This paper presents a practical and reliable description of the measurement uncertainty estimation of the analytical determination of ethyl carbamate in cachaça by GC-IDMS. The isotope dilution technique (ID) associated with GC-MS was used to improve the accuracy. The uncertainty estimated corresponds to 10% of the mass fraction of ethyl carbamate (115 ± 11) ng/g, which is in agreement with ppb level.

Plasma free and total carnitine measured in children by tandem mass spectrometry

Free and total carnitine quantification is important as a complementary test for the diagnosis of unusual metabolic diseases, including fatty acid degradation disorders. The present study reports a new method for the quantification of free and total carnitine in dried plasma specimens by isotope dilution electrospray tandem mass spectrometry with sample derivatization. Carnitine is determined by looking for the precursor of ions of m/z = 103 of N-butylester derivative, and the method is validated by comparison with radioenzymatic assay. We obtained an inter- and intra-day assay coefficient of variation of 4.3 and 2.3, respectively. Free and total carnitine was analyzed in 309 dried plasma spot samples from children ranging in age from newborn to 14 years using the new method, which was found to be suitable for calculating reference age-related values for free and total carnitine (less than one month: 19.3 ± 2.4 and 23.5 ± 2.9; one to twelve months: 28.8 ± 10.2 and 35.9 ± 11.4; one to seven years: 30.7 ± 10.3 and 38.1 ± 11.9; seven to 14 years: 33.7 ± 11.6, and 43.1 ± 13.8 µM, respectively). No difference was found between males and females. A significant difference was observed between neonates and the other age groups. We compare our data with reference values in the literature, most of them obtained by radioenzymatic assay. However, this method is laborious and time consuming. The electrospray tandem mass spectrometry method presented here is a reliable, rapid and automated procedure for carnitine quantitation.

Investigations of 2-alkyl-3-methoxypyrazines in three ladybug species and wine /

Investigations of 2-alkyl-3-methoxypyrazines (2-isopropyl-3-methoxypyra2ine, 2- secbutyl-3-methoxypyrazine and 2-isobutyl-3-niethoxypyrazine) in ladybug species {Coleoptera: Coccinellidae) and wine samples have been conducted. Headspace sampling coupled with gas chromatography-mass spectrometry was used to determine amounts of 2-alkyl-3-methoxypyra2ines in the ladybug species. Hippodamia convergens had the highest amount of alkybnethoxypyrazines, followed by Harmoma axyridis and the least in Coccinella septempunctata. Using a solvent extraction method, the precoccinelline alkaloid was found present in Hippodamia convergens and Coccinella septempunctata but not Harmonia axyridis. Steam distillation followed by a soHd phase extraction method as a sample preparation technique, enhanced detection while the isotope dilution method afforded accurate quantitation of the alkyknethoxypyrazines in the wine samples. Both ladybug-tainted and commercial wine samples were found to contain the 2- alkyl-3-methoxypyrazines. Wine samples prepared in 2001 generally contained higher levels than the corresponding 2003 samples. Levels of the 2-alkyl-3-methoxypyrazines found in the commercial wines ranged from a minimum value of 6 ng/L to 260 ±10 ng/L. Analyses revealed that for both ladybug species and wine samples, the 2- isopropyl-3-methoxypyrazine had the highest concentration, followed by 2-isobutyl- 3-methoxypyrazine and the least being the 2-secbutyl-3-methoxypyrazine. Possible contamination of the wine samples by ladybugs is thoroughly discussed. Furthermore, attempts to remove or reduce the levels of the alkylmethoxypyrazines with molecularly imprinted polymers from wine samples are presented in detail.

Accumulation of (5 ` S)-8,5 `-cyclo-2 `-deoxyadenosine in organs of Cockayne syndrome complementation group B gene knockout mice

Cockayne syndrome (CS) is a human genetic disorder characterized by sensitivity to UV radiation, neurodegeneration, premature aging among other phenotypes. CS complementation group B (CS-B) gene (csb) encodes the CSB protein (CSB) that is involved in base excision repair of a number of oxidatively induced lesions in genomic DNA in vivo. We hypothesized that CSB may also play a role in cellular repair of the DNA helix-distorting tandem lesion (5`S)-8,5`-cyclo-2`-deoxyadenosine (S-cdA). Among many DNA lesions. S-cdA is unique in that it represents a concomitant damage to both the sugar and base moieties of the same nucleoside. Because of the presence of the C8-C5` covalent bond, S-cdA is repaired by nucleotide excision repair unlike most of other oxidatively induced lesions in DNA, which are subject to base excision repair. To test our hypothesis, we isolated genomic DNA from brain, kidney and liver of wild type and csb knockout (csb(-/-)) mice. Animals were not exposed to any exogenous oxidative stress before the experiment. DNA samples were analysed by liquid chromatography/mass spectrometry with isotope-dilution. Statistically greater background levels of S-cdA were observed in all three organs of csb(-/-) mice than in those of wild type mice. These results suggest the in vivo accumulation of S-cdA in genomic DNA due to lack of its repair in csb(-/-) mice. Thus, this study provides, for the first time, the evidence that CSB plays a role in the repair of the DNA helix-distorting tandem lesion S-cdA. Accumulation of unrepaired S-cdA in vivo may contribute to the pathology associated with CS. Published by Elsevier B.V.

Nitrification processes in groundwaters evidenced by modification on the U contents and U-234/U-238 activity ratios

Groundwaters from the Botucatu-Piramboia aquifer system located at the Parana sedimentary basin in Brazil and sampled at Ribeirao Preto city, São Paulo State, were chemically and isotopically analysed, with the aim of evaluating how uranium isotopes U-234 and U-238 can be utilized to monitor the progress of nitrate, the main indicator of agrichemical pollution into an aquifer. Based on the isotope dilution analysis, the U-234/U-238 activity ratio and U content data in the groundwaters were utilized to deduce their proportions in a mixture, suggesting that the water not affected significantly by nitrification still dominates the exploitation system involving the studied wells.

Método de análise isotópica (δ13C) e limite de legalidade em néctar de laranja

Os objetivos deste trabalho foram desenvolver o método de análise isotópica para quantificar o carbono do ciclo fotossintético C3 em néctares de laranja comerciais e mensurar o limite de legalidade, baseado na legislação brasileira, para identificar as bebidas que não estão em conformidade com o Ministério da Agricultura, Pecuária e Abastecimento (MAPA). As bebidas foram produzidas em laboratório, conforme a legislação brasileira. Também foram produzidos néctares adulterados com quantidade de suco de laranja abaixo do limite mínimo permitido pelo MAPA. Na análise isotópica, foi mensurado o enriquecimento isotópico relativo dos néctares de laranja e também de suas frações, sólidos insolúveis (polpa) e açúcar purificado. Com esses resultados, foi estimada a quantidade de fonte C3 por meio da equação da diluição isotópica. Para determinar a existência de adulteração, foi necessária a criação do limite de legalidade de acordo com a legislação brasileira. Oito marcas comerciais de néctar de laranja foram analisadas. Todas foram classificadas como legais. O limite de legalidade foi uma importante inovação metodológica, que possibilitou identificar as bebidas que estavam em conformidade com a legislação brasileira. A metodologia desenvolvida provou ser eficiente para quantificar o carbono de origem C3 em néctares de laranja comerciais.

Análise isotópica (δ13C) e legalidade em suco e polpa de caju

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The Serido Group of NE Brazil, a late Neoproterozoic pre- to syn-collisional basin in West Gondwana: insights from SHRIMP U-Pb detrital zircon ages and Sm-Nd crustal residence (T-DM) ages

The Serido Group is a deformed and metamorphosed metasedimentary sequence that overlies early Paleoproterozoic to Archean basement of the Rio Grande do Norte domain in the Borborema Province of NE Brazil. The age of the Serido Group has been disputed over the past two decades, with preferred sedimentation ages being either Paleoproterozoic or Neoproterozoic. Most samples of the Serido Formation, the upper part of the Serido Group, have Sm-Nd T-DM ages between 1200 and 1600 Ma. Most samples of the Jucurutu Formation, the lower part of the Serido Group, have T-DM ages ranging from 1500 to 1600 Ma; some basal units have T-DM ages as old as 2600 Ma, reflecting proximal basement. Thus, based on Sm-Nd data, most, if not all, of the Serido Group was deposited after 1600 Ma and upper parts must be younger than 1200 Ma.Cathodoluminescence photos of detrital zircons show very small to no overgrowths produced during ca. 600 Ma Brasiliano deformation and metamorphism, so that SHRIMP and isotope dilution U-Pb ages must represent crystallization ages of the detrital zircons. Zircons from meta-arkose near the base of the Jucurutu Formation yield two groups of ages: ca. 2200 Ma and ca. 1800 Ma. In contrast, zircons from a metasedimentary gneiss higher in the Jucurutu Formation yield much younger ages, with clusters at ca. 1000 Ma and ca. 650 Ma. Zircons from metasedimentary and metatuffaceous units in the Serido Formation also yield ages primarily between 1000 and 650 Ma, with clusters at 950-1000, 800, 750, and 650 Ma. Thus, most, if not all, of the Serido Group must be younger than 650 Ma. Because these units were deformed and metamorphosed in the ca. 600 Ma Brasiliano fold belt during assembly of West Gondwana, deposition probably occurred ca. 610-650 Ma, soon after crystallization of the youngest population of zircons and before or during the onset of Brasiliano deformation.The Serido Group was deposited upon Paleoproterozoic basement in a basin receiving detritus from a variety of sources. The Jucurutu Formation includes some basal volcanic rocks and initially received detritus from proximal 2.2-2.0 Ga (Transamazonian) to late Paleoproterozoic (1.8-1.7 Ga) basement. Provenance for the upper Jucurutu Formation and all of the Serido Formation was dominated by more distal and younger sources ranging in age from 1000 to 650 Ma. We suggest that the Serido basin may have developed as the result of late Neoproterozoic extension of a pre-existing continental basement, with formation of small marine basins that were largely floored by cratonic basement (subjacent oceanic crust has not yet been found). Immature sediment was initially derived from surrounding land; as the basin evolved much of the detritus probably came from highlands to the south (present coordinates). Alternatively, if the Patos shear zone is a major terrane boundary, the basin may have formed as an early collisional foredeep associated with south-dipping subduction. In any case, within 30 million years the region was compressed, deformed, and metamorphosed during final assembly of West Gondwana and formation of the Brasiliano-Pan African fold belts. (C) 2003 Elsevier B.V. All rights reserved.

Spikes em espectrometria alfa para analise de amostras geologicas

The technique of isotope dilution has been extensively utilized for determining the content of trace elements in geological samples; it has been especially useful for the determination of 238U and 234U contents in crustal materials with measurements made by alpha spectrometry. 232U-228Th has usually been used as diluent (spike) during the application of this analytical technique. More recently, 236U and 229Th have been used. Some methodological problems concerning the utilization of these spikes are presented with examples of experimental data obtained in analyses of groundwater and borehole spoil samples from Morro do Ferro, Pocos de Caldas (MG). -from English summary

Turnover do carbono nos tecidos de suínos em diferentes fases de crescimento

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Evaluation of Fe uptake and translocation in transgenic and non-transgenic soybean plants using enriched stable Fe-57 as a tracer

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Turnover do carbono em sangue e plasma, nas fases crescimento e postura, de codornas japonesas (Coturnix coturnix japonica)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Uranium isotopes in groundwater occurring at Amazonas State, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)