O enriquecimento isotópico de nitrogênio-15 por troca química no sistema NO/HNO3 foi estudado através de duas teorias distintas. Os fatores de fracionamento isotópicos, obtidos pela teoria de contracorrente e os estimados pela teoria da eqüipartição isotópica, foram confrontados através de um modelo. Construiu-se uma coluna de contracorrente, em escala de laboratório, e parâmetros tais como: número de placas teóricas, altura equivalente de uma placa teórica, tipo de enchimento, altura total da coluna, produção de H15NO3/semana, obtidos em condições de equilíbrio dinâmico isotópico, foram estudados comparativamente aos da literatura / Nitrogen-15 isotope enrichment by chemical exchange in NO/HNO3 system was studied using two different theories. The isotope fractionation factors obtained by the countercurrent theory was compared to those estimated by the isotope equipartition theory were confronted through a model. It was built a column in countercurrent at laboratory scale and parameters such as: number of theoretical plates, height equivalent to a H15NO3week, obtained under isotope dynamic equilibrium conditions, were studied in comparison to those in the literature

A dual phase gas diffusion-FIA system containing a tubular PTFE-membrane was studied as a mean of producing gas samples for routine 15N/14N isotopic ratio mass spectrometry. The method is based on Rittenberg's reaction; the ammonium sample is injected into a liquid alkaline stream containing hypobromite and the N2 gas produced in the reaction diffuses across a PTFE-membrane into a helium carrier stream which carries it to the detector. Initially here, the use of a tubular microporous PTFE-membrane as a device for the preconcentration of samples in aqueous solutions was investigated. The performance of such a membrane was studied under a variety of operating conditions. A qualitative model of the membrane mechanism was developed based on the diffusion transport of vapour away from the contained liquid surface through the connected pore space. The dispersion undergone by the sample in the GD-FIA system containing this preconcentration unit was also studied and this FIA system was applied as a practical device for the determination and speciation of aluminium in a river water sample. The procedure for generating nitrogen gas involved optimisation of the system parameters including the oxidation reaction step and the production on-line of the chemicals used. The nitrogen gas was generated easily and rapidly, allowing a sample throughput capability of the order of 20 h-1. The system was applied to the determination of total nitrogen content in agricultural sample prepared by the Kjeldahl digestion. The method offered precision and accuracy comparable to those of the standard distillationtitration procedure. Isotope ratios were determined with good precision and means for obtaining accuracy comparable with established techniques were developed. It was also shown that the DPGD-FIA system can be readily adapted to enable different forms of nitrogen e. g. N02-, N03- and NH4+ to be determined.

No description available.

No / We examined multiple natural abundance isotope ratios of human hair to assess biological variability within and between geographic locations and, further, to determine how well these isotope values predict location of origin. Sampling locations feature differing seasonality and mobile populations as a robust test of the method. Serially-sampled hair from Cambridge, MA, USA, shows lower δ2 H and δ18 O variability over a one-year time course than model-predicted precipitation isotope ratios, but exhibits considerable differences between individuals. Along a ∼13° northsouth transect in the eastern USA (Brookline, MA, 42.3 ° N, College Park, MD, 39.0 ° N, and Gainesville, FL, 29.7 ° N) δ18 O in human hair shows relatively greater differences and tracks changes in drinking water isotope ratios more sensitively than δ2 H. Determining the domicile of humans using isotope ratios of hair can be confounded by differing variability in hair δ18 O and δ2 H between locations, differential incorporation of H and O into this protein and, in some cases, by tap water δ18 O and δ2 H that differ significantly from predicted precipitation values. With these caveats, randomly chosen people in Florida are separated from those in the two more northerly sites on the basis of the natural abundance isotopes of carbon, nitrogen, hydrogen, and oxygen. / This work was partially supported by the National Geospatial Agency under grant [HM1582-08-0024]. / Originally presented at the IAEA International Symposium on Isotope Hydrology: Revisiting Foundations and Exploring Frontiers, 11–15 May 2015, Vienna, Austria

Le développement de nouveaux donneurs d’oxyde nitrique (NO) dans le traitement chronique des maladies cardiovasculaires nécessite l’étude de leur biodisponibilité après administration par voie orale. Les S-nitrosothiols (RSNOs) apparaissent d’intéressants candidats médicaments pour ce faire, et l’étude de leur perméabilité intestinale est une première étape indispensable. Il est nécessaire de disposer d’une méthodologie analytique suffisamment sensible et sélective, en particulier permettant de différencier entre la production endogène de NO, l’apport alimentaire en ions nitrites et nitrate et le médicament lui-même. Nos travaux de thèse ont consisté à utiliser le S-nitrosoglutathion (GSNO) comme modèle après son marquage par l’isotope stable 15 de l’azote (15N). La dérivation du 15NO libéré par deux méthodes conventionnelles (méthode de Griess conduisant à la formation d’un adduit azoïque ; réaction avec le 2,3-diaminonaphtalène (DAN) formant l’adduit 2,3-naphtotriazole (NAT)) et l’étude de la fragmentation en spectrométrie de masse tandem (MS/MS) des deux adduits correspondants ont mené à sélectionner la dérivation par le DAN comme étant la plus sensible. Une transition originale résultant de la fragmentation du NAT en mode Higher-energy Collisional Dissociation (HCD) au lieu du mode conventionnel Collisionally Induced Dissociation (CID) a été mise en évidence ; elle permet d’atteindre une limite de quantification de 5 nM (soit 20 fois plus basse que celle offerte par la fluorescence). La méthode LC-MS/MS a été validée et appliquée à l’étude de la perméabilité intestinale du GS15NO par deux modèles : l’un in vitro (monocouche de cellules épithéliales type Caco-2), l’autre ex vivo (intestin de rat isolé (ileum) dans une chambre de Ussing). Les valeurs de perméabilité apparente calculées à partir des concentrations des métabolites du GS15NO (ions nitrites, nitrates et RSNOs) le classent comme un médicament de perméabilité intermédiaire. En outre, des études sur les mécanismes de dénitrosation du GSNO ont été menées sur intestin isolé, démontrant en particulier le rôle d’enzymes telles que la γ-glutamyltransférase et la protein disulfide isomerase / The development of innovative nitric oxide (NO) donors for the chronic treatment of cardiovascular diseases implies their bioavailability studies after oral administration. S-nitrosothiols (RSNOs) look interesting drug candidates for this purpose and evaluating their intestinal permeability appears the first step to be realized. Thus, an analytical method offering high sensitivity is needed; moreover this method should be selective by differentiating between the endogenous production of NO, the intake of nitrite and nitrate ions via the diet, and the drug itself. Our work consisted in using S-nitrosoglutathione (GSNO) labeled with the stable nitrogen isotope 15 (15N) as a model. Released 15NO species were derivatized by two conventional methods: Griess method leading to the formation of an azo adduct; reaction with 2,3-diaminonaphthalene (DAN) producing 2,3-naphtotriazole (NAT); fragmentation studies of the two adducts by tandem mass spectrometry (MS/MS) allow the selection of DAN method because it provides the highest sensitivity. An original transition resulting from the NAT fragmentation in Higher-energy Collisional Dissociation (HCD) mode instead of the conventional Collisionally Induced Dissociation (CID) mode was pointed out and permitted to reach a limit of quantification of 5 nM (20 fold less than when using fluorescence). The LC-MS/MS method was validated and applied to the GS15NO intestinal permeability studies with two models: in vitro (a monolayer of Caco-2 epithelial cells), and ex vivo (isolated intestine of rat (ileum) in an Ussing chamber). The apparent permeability values calculated with concentrations of GS15NO metabolites (nitrite, nitrate ions and RSNOs) classify it as a middle permeable drug. Studies on GSNO denitrosating processes using isolated rat intestine demonstrate that the enzymes γ-glutamyltransferase and protein disulfide isomerase play a pivotal role

North American populations of white-winged scoters (<i>Melanitta fusca deglandi</i>) have declined markedly over the past several decades. The causes for decline are uncertain, but likely involve a complexity of events occurring on wintering and breeding areas. To gain insight into potential cross-seasonal effects, I delineated Atlantic and Pacific wintering scoter populations and linked them to a shared breeding area using stable isotope analysis of carbon (δ13C) and nitrogen (δ15N) ratios in feathers. By applying this methodology to a marked breeding population at Redberry Lake, Saskatchewan, I assigned females to putative wintering areas and determined: (1) population structure; (2) the extent of winter site philopatry; and, (3) differences in vital rates and other variates in relation to winter origin. Discriminant function analysis of isotopic ratios in feather samples from known wintering locations resulted in classification probabilities of 96% (<i>n</i> = 149) for Pacific and 78% (<i>n</i> = 32) for Atlantic wintering scoters. Using this methodology, I determined that the Redberry Lake breeding population is comprised of approximately 75% Pacific and 25% Atlantic wintering birds, and its members exhibit high degrees of winter region philopatry based on the classification of successive recaptures over three field seasons. Annual variations in population structure, as well as differences in nest initiation dates and blood contaminant loads in relation to winter area suggest seasonal interactions may influence survival and reproductive success of this population. To gain insight into potential seasonal interactions, I examined nest success and female survival in relation to winter area. No significant differences in nest success in relation to winter area were found, but nests that failed before mid-incubation were not sampled. Adult female survival rate for 2000-2004 was estimated as 0.85, with no significant difference detected between wintering areas. This study demonstrated that it is important to link breeding and wintering areas to better understand the factors influencing population dynamics and to effectively address conservation issues.

Energy demands can be particularly high in arctic-nesting birds that face harsh, unpredictable conditions during the breeding season. Consequences of these demands, particularly energy-partitioning during egg laying and incubation, are fundamentally important for arctic nesters. This study investigated differences in breeding strategies between Long-tailed Duck (<i>Clangula hyemalis</i>) and King Eider (<i>Somateria spectabilis</i>) in the central Canadian arctic. The focus was on ecological variables and influences of variation in nutrient resources used during incubation and egg production. Research was done at Karrak Lake, Nunavut, where both species nest sympatrically at relatively high densities, permitting comparative research about breeding strategies.<p>This study used stable-carbon (d13C) and nitrogen (d15N) isotope analysis to investigate origins and allocation of endogenous (stored) and exogenous (external) nutrients used in egg production. Remote temperature sensors were placed in nests to estimate and compare incubation rhythms and gain insight into capital and income incubating strategies of both species. Results suggest that breeding Long-tailed Ducks and King Eiders used a mixed breeding strategy, that is they relied on both exogenous and endogenous resources for reproduction. Close correspondence between d13C and d15N values of egg components and potential diet items indicated that King Eiders allocated exogenous nutrients for egg production (albumen 98.1%, yolk protein 96.8%, whole yolk 98.4%, and yolk lipids 84%). Female King Eiders relied on endogenous nutrients for incubation, as evidenced by high incubation constancy (96%). Conversely, the range of d13C values in components of Long-tailed Duck eggs and d13C values of diet items suggested that although some females allocated endogenous reserves for egg production, most females allocated exogenous resources for egg production (albumen 98.5%, yolk protein 78.3%, whole yolk 84.9%, and yolk lipids 38.3%). Long-tailed Duck females had an 84% incubation constancy, suggesting less reliance on endogenous nutrients for incubation than was estimated for female King Eiders. Knowledge about the relative importance of endogenous reserves and exogenous nutrients for egg production and incubation may help direct management decisions to specific winter/staging and or breeding areas used by King Eiders and Long-tailed Ducks.

Energy demands can be particularly high in arctic-nesting birds that face harsh, unpredictable conditions during the breeding season. Consequences of these demands, particularly energy-partitioning during egg laying and incubation, are fundamentally important for arctic nesters. This study investigated differences in breeding strategies between Long-tailed Duck (<i>Clangula hyemalis</i>) and King Eider (<i>Somateria spectabilis</i>) in the central Canadian arctic. The focus was on ecological variables and influences of variation in nutrient resources used during incubation and egg production. Research was done at Karrak Lake, Nunavut, where both species nest sympatrically at relatively high densities, permitting comparative research about breeding strategies.<p>This study used stable-carbon (d13C) and nitrogen (d15N) isotope analysis to investigate origins and allocation of endogenous (stored) and exogenous (external) nutrients used in egg production. Remote temperature sensors were placed in nests to estimate and compare incubation rhythms and gain insight into capital and income incubating strategies of both species. Results suggest that breeding Long-tailed Ducks and King Eiders used a mixed breeding strategy, that is they relied on both exogenous and endogenous resources for reproduction. Close correspondence between d13C and d15N values of egg components and potential diet items indicated that King Eiders allocated exogenous nutrients for egg production (albumen 98.1%, yolk protein 96.8%, whole yolk 98.4%, and yolk lipids 84%). Female King Eiders relied on endogenous nutrients for incubation, as evidenced by high incubation constancy (96%). Conversely, the range of d13C values in components of Long-tailed Duck eggs and d13C values of diet items suggested that although some females allocated endogenous reserves for egg production, most females allocated exogenous resources for egg production (albumen 98.5%, yolk protein 78.3%, whole yolk 84.9%, and yolk lipids 38.3%). Long-tailed Duck females had an 84% incubation constancy, suggesting less reliance on endogenous nutrients for incubation than was estimated for female King Eiders. Knowledge about the relative importance of endogenous reserves and exogenous nutrients for egg production and incubation may help direct management decisions to specific winter/staging and or breeding areas used by King Eiders and Long-tailed Ducks.

North American populations of white-winged scoters (<i>Melanitta fusca deglandi</i>) have declined markedly over the past several decades. The causes for decline are uncertain, but likely involve a complexity of events occurring on wintering and breeding areas. To gain insight into potential cross-seasonal effects, I delineated Atlantic and Pacific wintering scoter populations and linked them to a shared breeding area using stable isotope analysis of carbon (δ13C) and nitrogen (δ15N) ratios in feathers. By applying this methodology to a marked breeding population at Redberry Lake, Saskatchewan, I assigned females to putative wintering areas and determined: (1) population structure; (2) the extent of winter site philopatry; and, (3) differences in vital rates and other variates in relation to winter origin. Discriminant function analysis of isotopic ratios in feather samples from known wintering locations resulted in classification probabilities of 96% (<i>n</i> = 149) for Pacific and 78% (<i>n</i> = 32) for Atlantic wintering scoters. Using this methodology, I determined that the Redberry Lake breeding population is comprised of approximately 75% Pacific and 25% Atlantic wintering birds, and its members exhibit high degrees of winter region philopatry based on the classification of successive recaptures over three field seasons. Annual variations in population structure, as well as differences in nest initiation dates and blood contaminant loads in relation to winter area suggest seasonal interactions may influence survival and reproductive success of this population. To gain insight into potential seasonal interactions, I examined nest success and female survival in relation to winter area. No significant differences in nest success in relation to winter area were found, but nests that failed before mid-incubation were not sampled. Adult female survival rate for 2000-2004 was estimated as 0.85, with no significant difference detected between wintering areas. This study demonstrated that it is important to link breeding and wintering areas to better understand the factors influencing population dynamics and to effectively address conservation issues.

Submitted by Alexandre Sousa (alexandre.sousa@incqs.fiocruz.br) on 2016-05-11T13:46:20Z No. of bitstreams: 1 Thesis-1994-Jacob.pdf: 26119019 bytes, checksum: b8e19fd69a5cb720e5071df7ae1b03bb (MD5) / Approved for entry into archive by Alexandre Sousa (alexandre.sousa@incqs.fiocruz.br) on 2016-05-11T14:21:12Z (GMT) No. of bitstreams: 1 Thesis-1994-Jacob.pdf: 26119019 bytes, checksum: b8e19fd69a5cb720e5071df7ae1b03bb (MD5) / Made available in DSpace on 2016-05-11T14:21:12Z (GMT). No. of bitstreams: 1 Thesis-1994-Jacob.pdf: 26119019 bytes, checksum: b8e19fd69a5cb720e5071df7ae1b03bb (MD5) Previous issue date: 1994 / Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Departamento de Entomologia. Rio de Janeiro, RJ, Brasil. / A dual phase gas diffusion-FIA system containing a tubular PTFE-membrane was studied as a mean of producing gas samples for routine 15N/14N isotopic ratio mass spectrometry. The method is based on Rittenberg's reaction; the ammonium sample is injected into a liquid alkaline stream containing hypobromite and the N2 gas produced in the reaction diffuses across a PTFE-membrane into a helium carrier stream which carries it to the detector. Initially here, the use of a tubular microporous PTFE-membrane as a device for the preconcentration of samples in aqueous solutions was investigated. The performance of such a membrane was studied under a variety of operating conditions. A qualitative model of the membrane mechanism was developed based on the diffusion transport of vapour away from the contained liquid surface through the connected pore space. The dispersion undergone by the sample in the GD-FIA system containing this preconcentration unit was also studied and this FIA system was applied as a practical device for the determination and speciation of aluminium in a river water sample. The procedure for generating nitrogen gas involved optimisation of the system parameters including the oxidation reaction step and the production on-line of the chemicals used. The nitrogen gas was generated easily and rapidly, allowing a sample throughput capability of the order of 20 h-1. The system was applied to the determination of total nitrogen content in agricultural sample prepared by the Kjeldahl digestion. The method offered precision and accuracy comparable to those of the standard distillationtitration procedure. Isotope ratios were determined with good precision and means for obtaining accuracy comparable with established techniques were developed. It was also shown that the DPGD-FIA system can be readily adapted to enable different forms of nitrogen e. g. N02-, N03- and NH4+ to be determined.