994 resultados para Isótopos de Pb e Nd
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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The electrocatalytic oxidation of 1-propanol was investigated on platinum electrodes modified by submonolayers of Pb and Sn in acid media. An increase of oxidation rates observed for both Pb and Sn, and the influence of theta values was investigated. The values of the apparent activation energy evaluated from the Arrhenius plots concerning the electrochemical oxidation of 1-propanol on modified platinzed platinum electrodes, reveal a significant decrease in the presence of upd Sn and Ph adatoms. A decrease from 56 to 26 U mol(-1) in the presence of Sn. and from 78 to 25 U mol(-1) for Ph adatoms are some illustrative values which reflect the promoting effect of the upd adatoms.
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After the isolation of Helicobacter pylori from an injury at the stomach mucosa by Marshall and Wareen, work that was recognized with the Nobel Prize of Medicine or Physiology in 2005, many other works showed the relationship between the presence of H. pylori and diseases at the digestive system, such as gastritis, gastric, duodenal and peptic ulcer, and stomach cancer. The 13C-Urea Breath Test - 13C-UBT is a non-invasive diagnostic method that utilizes the breath of a patient to determine the presence of H. pylori through stable isotopes. This work aimed to find an ideal 13C-UBT Isotopic Ratio Mass Spectroscopy cut-off value (a threshold between positive and negative) to diagnose H. pylori infection at Brazilian population. Patients were selected at the UNESP-Botucatu Clinical Hospital Endoscopy Section. With these results it was possible to indicate that the best cut-off value is between 2.5 to 6 ‰ of Delta Over Baseline (DOB)
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The use of stable isotopes in Brazil is being improved, mainly through research conducted at main universities in the country. Some applications in health allow to studying, for example, processes involving synthesis and protein degradation, energy expenditure, body composition, kinetics of vitamins, mineral absorption and diagnose diseases related to Helicobacter pylori. The big motivation is to encourage the growth of investments in health in the few centers that have mass spectrometers in Brazil, as the technique is harmless to humans, in other words, no has problems to use it like when you use radioactive isotopes
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This presente monograph propose the analysis and discussion of the production of urban space and the processes of their structuring intraurbana from the dynamics of the real estate market into three Medium-sized Cities, Campina Grande - PB, Mossoró - RN and Passo Fundo - RS, whereas the various agents producing this space, in a comparative perspective. From this urban dynamic search to analyze the processes and relations present in these spaces, which are important for its production. From the compilation of real estate advertisements in local newspapers, are analyzed offerings of urban land, houses and apartments in each one of these cities by highlighting their locations and differentiated prices. Thus, working with data from real estate ads from the period 1995 - 2010 and a comparative perspective of the characteristics of real estate markets of three medium-sized cities, it tried to apprehend processes that are common between them and other individuals, to each one. Therefore the comparative analysis developed in this monograph sought to verify whether there are similarities between the cities in relation to the trends of concentration/spatial dispersion of bids and movements throughout time, in addition to a further intensification of the activities of real estate agents in face of such trends and offerings. In addition, we sought to remove a set of problematization that allow them to understand with more acute, in this set of medium cities of Brazilian urban network, processes of change that is already being discussed in the recent period by ReCiMe.
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In order to to research, the region of Perau, base metal mineralization, Grupo Votorantim Metals conducted a soil sampling on targets predetermined holding its chemical analysis. These reviews have been provided by the company for this work was to evaluate the potential use of these data pedogeochemical multi-element for refinement of the work of geological mapping. We selected six targets: Varginha, Salvador, Guararema Taquara Lisa and Coffin of Mendes, in the municipalities of Adrianople, Cerro Azul and Tunas do Paraná, located in Vale do Ribeira (PR). Both have about 10 km2 and situated in the geological context of the Fold Belt Terrane and the Massif de Joinville. The main rock types are present metasedimentary rocks of low to medium grade metamorphic, interspersed the amphibolites ortoderivados, both belonging to the Complex Perau, gneisses and migmatitic Complex. Applied to the geochemical data descriptive statistical techniques (variogram, kriging and histogram). From the correlation between the distributions of elements with the geological data, we could assess the potential of the proposed methodology.
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The DGT technique has been used to determine and better understand the dynamics and bioavailability of metals in the sea near to marine outfalls. In this work, the DGT was assessed for the determination of Cd, Pb, Cu, Zn and Ni in marine water samples from Potiguar Basin in its conventional aspect (binding agent, Chelex-100 and diffusive agent: Diffusive polyacrylamide gel (D) and restrictive (R)) and determination of Pb and Cd through its alternative aspect (binding agent: Saccharomyces cerevisiae immobilized in agarose gels and diffusive agent: 3MM Chromatography Paper). The deployment curves for long periods of immersion in the sample, showed a good linear correlation for the conventional aspect to Zn (D: R²=0.9586, R: R²=0.9444), Ni (D: R²=0.9789, R: R²=0.9286) and Cu (D: R²=0.764, R: R²=0.8143), and alternative to Pb (R²=0.9228) and Cd (R²=0.9673). The results of the organic and inorganic composition analysis in conventional aspect, showed that for every element there is no significant fraction of organic compounds in the sample. In addition, considering the alternative aspect, the comparison of obtained and expected masses suggests that some of the Pb is not labile and that the main retention mechanism of Pb for S. Cerevisiae occurs through ion exchange
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To evaluate the effect of surface treatment with Er:YAG and Nd:YAG laser on resin composite bond strength to recently bleached dentin. Material and Methods: In this study 120 bovine incisors were used and distributed into two groups: Group C: without bleaching treatment; Group B: with bleaching treatment (35% hydrogen peroxide). Each group was divided into three subgroups: Subgroup N: without laser treatment; Subgroup Nd: irradiation with Nd:YAG laser; Subgroup Er: irradiation with Er:YAG laser. Next, the adhesive system (Adper Single Bond 2) was applied and composite buildups were constructed with Z350 composite. The teeth were sectioned to obtain dentin-resin sticks (1x1mm) and analyzed by microtensile bond testing. The data were statistically analyzed by the ANOVA and Tukey tests. Results: The results showed that the bond strength values in the bleached control group (16.17 MPa) presented no significant difference in comparison with the group bleached and irradiated with Er:YAG laser (14.69 MPa). The non bleached control group (26.79 MPa) presented significant difference in bond strength when compared with the non bleached group irradiated with Er:YAG laser (22.82 MPa) and with the group treated by bleaching and irradiation with Nd:YAG laser (28,792 MPa). The group without bleaching treatment and irradiated with Nd:YAG (36.1 MPa) presented a significant increase in bond strength in comparison with the other groups. Conclusion: The use of Nd:YAG laser on bleached specimens was able of completely reversing the immediate effects of bleaching, obtaining bond strength values similar to those of the control group
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The main objective of this study is to determine the activity of Po-210, Pb-210 and gross alpha/beta radioactivity in groundwater collected in Botucatu, municipality of the São Paulo state, Brazil. Samples were collected in wells to perform the radiochemical analysis. Most wells are registered in DAEE, Sabesp or CPRM. The activity of polonium was obtained by the method of alpha spectrometry, held in LABIDRO at UNESP, Rio Claro. All samples showed radioactivity values below the maximum allowed by WHO, that are: gross alpha radioactivity = 0,5 Bq/L, gross beta radioactivity = 1,0 Bq/L, Po210 = 0,2 Bq/L and Pb210 = 0,1 Bq/L. The results of hydrochemical analysis were compared with the 1469 Ordinance of the Health Ministry, and all values are bellow the maximum allowed. The data also allowed obtain the samples classification using the Piper diagram. The samples AAB, Quinta do Manacás, Faz. Quatro Irmãs, Sesi, Sitio São José and ITE are classified as calcic bicarbonate; the samples Staroup and Caio are potassic; the samples Banespa and BTC are bicarbonate and mixed interms of dissolved cations; Sitio das Palmeiras sample is sodium bicarbonate; the sample Faz. São Paulo is chlorinated calcic; the sample Sítio Btu-Pardinho chlorinated and mixed interms of dissolved cations
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Although several studies of Araxá Group in the region of Passos, just a few works deal with the age of metamorphism of this group. The current work aims to determine the cooling age of these rocks by in situ U-Pb dating in rutiles. Interestingly, the region of São Sebastião do Paraíso shows a condensed lithostratigraphic column from the Passos Nappe and exposes the higher metamorphic grade rocks described for this unit. The use of rutile as a geochronometer is based on its ability to incorporate U in its structure, facilitating the calculation of the age of the isotope ratio by U-Pb. Furthermore, the use of in situ dating technique with Laser Ablation has been a reliable and advantageous study because the analysis are punctual, and do not destroy the whole sample to be analyzed. The analyses of this work were made at the University of Gothenburg - Sweden and obtained 238U/206Pb ages between 608-566 ± 10 Ma and 235U/207Pb between 627-572 ± 10 Ma, showing that these ages are concordant with the literature in the area and are interpreted as the cooling age of metamorphism
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Pós-graduação em Cirurgia Veterinária - FCAV
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Devido a grande demanda do uso da energia atômica, as pesquisas sobre o processo de separação de isótopos tornam-se cada vez mais importantes. Neste trabalho mostramos uma técnica de separação de isótopos usando o efeito da ressonância.
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This research examines the merits of hallucinogenic plants considered and/or psychoactive substances, such as Cannabis sativa and Ipomoea violacea, using the isotope rates of stable isotope of oxygen (18O) and nitrogen (15N), continuing projects already developed by the research group at the Center for Stable Isotope (CIE), which evaluated the isotopes carbon-13. This paper helps in creating a database that we intent to use in evaluation of each plant merit. Through the IRMS (Isotope-Ratio Mass Spectrometry) technique, it has shown that some of the 24 samples of marijuana (Cannabis sativa L.) evaluated were similar to those grown in the regions of Fairbanks and Tanacross Alaska, USA. In turn, the 50 samples of Ipomoea violacea, coming from Botucatu (SP) and Três Lagoas (MS), got their differences detected, in order to clearly identify the discrepancies between their growing regions. Thus, it was possible not only to track the geographical differences between marijuana samples collected from different regions, but also evaluate the isotopic variation of leaf, flower and seed of Ipomoea violacea. With this database, it was possible to determine the origin region of the drug and/or detect where the cultivation was carried out, aiding in the search of the traffic control agencies, such as the Federal Police in Brazil
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Objectives: the aim of this work was to define the range of possible values for each isotope of carbon-13 and nitrogen-15 for cocaine and marijuana seized in Botucatu-SP, with the intention of distinguishing the geographical origin of the drug. Materials and Methods: samples of marijuana and cocaine were collected at the time of incineration. Then, at the Stable Isotope Center from São Paulo State University in Botucatu, São Paulo, Brazil, samples of marijuana were subjected to the drying process and subsequent grinding. Samples of cocaine were not submitted to the processes of drying and grinding because they were already in adequate granulometry. Subsequently, the samples of both drugs were weighed in accordance with the standards for carbon-13 and nitrogen-15. Lastly, CO2 and N2 gases were obtained from the samples through the elemental analyzer. They were then analyzed in a mass spectrometer to obtain values of δ13C and δ15N in ‰. Results and Discussion: the results of marijuana allowed for comparison with regions of Queensland, Australia, according to the range of δ13C between -29.9 ‰ and -29.3 ‰ and δ15N range from 4.1 ‰ to 5.8 ‰. The results were also consistent with those of the state of Pará, Brazil, where the values of δ13C and δ15N were -30.3 ± 0.7 ‰ and 5.0 ± 1.3 ‰, respectively. Also the results were in accordance with those from the state of Mato Grosso do Sul, Brazil, in which δ13C values varied by -28.7 ± 1.3 ‰, and δ15N values varied by 6.6 ± 1.1 ‰, respectively. In both regions, the samples identified as being from Pará and Mato Grosso do Sul showed an overlap. In addition, the results fitted with data from the state of Maranhão, in which the values of δ13C and δ15 N were -28.8 ± 1.6 ‰ and 2.9 ± 2.5 ‰, respectively. In the case of cocaine, the present study could not be related to the results from the literature. One possible explanation may be related to the non-purification of ...