Dissertations / Theses: 'DGRT'

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Huger, Sandrine. "Adaptation interactive d'un traitement de radiothérapie par imagerie volumique : développement et validation d'outils pour sa mise en oeuvre en routine clinique." Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0231.

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Les changements anatomiques des patients au cours du traitement de radiothérapie peuvent engendrer des conséquences dosimétriques significatives sur les volumes cibles (VC) ou les organes à risques (OARs). Le processus de radiothérapie adaptative peut compenser ces variations, cependant son déploiement en clinique est ralentit par une charge de travail supplémentaire considérable pour les équipes médicales et aucun logiciel n'est disponible pour une utilisation en clinique. Nous avons développé un outil d'alerte dosimétrique in vivo simple permettant d'identifier rapidement les situations où une adaptation de traitement est requise pour un patient. L'évaluation dosimétrique des traitements délivrés a été réalisée sur l'imagerie embarquée 3D (CBCT) dont la précision des calculs de dose a dû être évaluée. L'outil d'alerte permet de s'affranchir d'une nouvelle délinéation de volumes d'intérêt et est basé sur des critères objectifs et quantifiables constitués par le dépassement des limites dosimétriques définies pour chacun des volumes considérés. La précision et la détectabilité de l'outil ont été validées puis il a été appliqué dans une étude rétrospective de 10 patients ORL afin de surveiller l'administration du traitement et d'identifier les patients pour lesquels une adaptation du traitement aurait pu être envisagée. Dans son implémentation clinique, le processus de radiothérapie adaptative requiert des algorithmes de recalage déformable capable de suivre les déformations locales d'un patient se produisant au cours du traitement, seulement leur utilisation n'est pas encore validée. Nous avons procédé à l'évaluation de la précision d'un algorithme de recalage déformable, de type Block Matching présentant l'avantage d'être adapté à l'imagerie multimodale CT/CBCT, en comparaison par rapport à un algorithme de recalage rigide. Une étude a été menée pour 10 patients ORL en se basant sur la comparaison de contours de volumes d'intérêt pour 76 CBCT. Les paramètres de similarité utilisés consistaient en l'Indice de Similarité Dice, la distance de Hausdorff robuste (en mm) et la différence de volume absolu (en cm3)
Changing anatomy during radiotherapy can lead to significant dosimetric consequences for organs at risk (OARs) and/or target volumes. Adaptive radiotherapy can compensate for these variations however its deployment for clinical work is hampered by the increased workload for the medical staff and there is still no commercialized software available for clinical use. We developed a simple in vivo dosimetric alert tool allowing rapid identification of patients who might benefit from an adaptive radiotherapy. Dosimetric evaluation of delivered treatment has been conducted onto 3D on board imaging (CBCT) whose dose calculation accuracy has been evaluated. The tool does not require a new volume of interest delineation. Tool alert is based on objectives and quantifiable criteria defined by the exceeding volumes of interest dose thresholds. Tool precision and detectability have been validated and applied in a retrospective study on 10 head and neck patients. The tool allows detecting patients where an adaptive treatment could have been considered. In its clinical implementation, adaptive radiotherapy process requires deformable matching algorithms to follow patient local's deformations occurring during treatment. Nevertheless, their use has not been validated. We conducted an evaluation of the Block Matching deformable algorithm, suitable for multimodality imaging (CT/CBCT), in comparison to rigid algorithm. A study has been conducted for 10 head and neck patients based on volume of interest contours comparison for 76 CBCT. Similarity parameters used consisted on Dice Similarity Index, Robust Hausdorff Distance (in mm) and the absolute volume difference (in cc)

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2

Huger, Sandrine. "Adaptation interactive d'un traitement de radiothérapie par imagerie volumique : Développement et validation d'outils pour sa mise en œuvre en routine clinique." Phd thesis, Université de Lorraine, 2013. http://tel.archives-ouvertes.fr/tel-00937604.

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Les changements anatomiques des patients au cours du traitement de radiothérapie peuvent engendrer des conséquences dosimétriques significatives sur les volumes cibles (VC) ou les organes à risques (OARs). Le processus de radiothérapie adaptative peut compenser ces variations, cependant son déploiement en clinique est ralentit par une charge de travail supplémentaire considérable pour les équipes médicales et aucun logiciel n'est disponible pour une utilisation en clinique. Nous avons développé un outil d'alerte dosimétrique in vivo simple permettant d'identifier rapidement les situations où une adaptation de traitement est requise pour un patient. L'évaluation dosimétrique des traitements délivrés a été réalisée sur l'imagerie embarquée 3D (CBCT) dont la précision des calculs de dose a dû être évaluée. L'outil d'alerte permet de s'affranchir d'une nouvelle délinéation de volumes d'intérêt et est basé sur des critères objectifs et quantifiables constitués par le dépassement des limites dosimétriques définies pour chacun des volumes considérés. La précision et la détectabilité de l'outil ont été validées puis il a été appliqué dans une étude rétrospective de 10 patients ORL afin de surveiller l'administration du traitement et d'identifier les patients pour lesquels une adaptation du traitement aurait pu être envisagée. Dans son implémentation clinique, le processus de radiothérapie adaptative requiert des algorithmes de recalage déformable capable de suivre les déformations locales d'un patient se produisant au cours du traitement, seulement leur utilisation n'est pas encore validée. Nous avons procédé à l'évaluation de la précision d'un algorithme de recalage déformable, de type Block Matching présentant l'avantage d'être adapté à l'imagerie multimodale CT/CBCT, en comparaison par rapport à un algorithme de recalage rigide. Une étude a été menée pour 10 patients ORL en se basant sur la comparaison de contours de volumes d'intérêt pour 76 CBCT. Les paramètres de similarité utilisés consistaient en l'Indice de Similarité Dice, la distance de Hausdorff robuste (en mm) et la différence de volume absolu (en cm3).

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Huger, Sandrine. "Adaptation interactive d'un traitement de radiothérapie par imagerie volumique : développement et validation d'outils pour sa mise en oeuvre en routine clinique." Electronic Thesis or Diss., Université de Lorraine, 2013. http://www.theses.fr/2013LORR0231.

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Abstract:

Les changements anatomiques des patients au cours du traitement de radiothérapie peuvent engendrer des conséquences dosimétriques significatives sur les volumes cibles (VC) ou les organes à risques (OARs). Le processus de radiothérapie adaptative peut compenser ces variations, cependant son déploiement en clinique est ralentit par une charge de travail supplémentaire considérable pour les équipes médicales et aucun logiciel n'est disponible pour une utilisation en clinique. Nous avons développé un outil d'alerte dosimétrique in vivo simple permettant d'identifier rapidement les situations où une adaptation de traitement est requise pour un patient. L'évaluation dosimétrique des traitements délivrés a été réalisée sur l'imagerie embarquée 3D (CBCT) dont la précision des calculs de dose a dû être évaluée. L'outil d'alerte permet de s'affranchir d'une nouvelle délinéation de volumes d'intérêt et est basé sur des critères objectifs et quantifiables constitués par le dépassement des limites dosimétriques définies pour chacun des volumes considérés. La précision et la détectabilité de l'outil ont été validées puis il a été appliqué dans une étude rétrospective de 10 patients ORL afin de surveiller l'administration du traitement et d'identifier les patients pour lesquels une adaptation du traitement aurait pu être envisagée. Dans son implémentation clinique, le processus de radiothérapie adaptative requiert des algorithmes de recalage déformable capable de suivre les déformations locales d'un patient se produisant au cours du traitement, seulement leur utilisation n'est pas encore validée. Nous avons procédé à l'évaluation de la précision d'un algorithme de recalage déformable, de type Block Matching présentant l'avantage d'être adapté à l'imagerie multimodale CT/CBCT, en comparaison par rapport à un algorithme de recalage rigide. Une étude a été menée pour 10 patients ORL en se basant sur la comparaison de contours de volumes d'intérêt pour 76 CBCT. Les paramètres de similarité utilisés consistaient en l'Indice de Similarité Dice, la distance de Hausdorff robuste (en mm) et la différence de volume absolu (en cm3)
Changing anatomy during radiotherapy can lead to significant dosimetric consequences for organs at risk (OARs) and/or target volumes. Adaptive radiotherapy can compensate for these variations however its deployment for clinical work is hampered by the increased workload for the medical staff and there is still no commercialized software available for clinical use. We developed a simple in vivo dosimetric alert tool allowing rapid identification of patients who might benefit from an adaptive radiotherapy. Dosimetric evaluation of delivered treatment has been conducted onto 3D on board imaging (CBCT) whose dose calculation accuracy has been evaluated. The tool does not require a new volume of interest delineation. Tool alert is based on objectives and quantifiable criteria defined by the exceeding volumes of interest dose thresholds. Tool precision and detectability have been validated and applied in a retrospective study on 10 head and neck patients. The tool allows detecting patients where an adaptive treatment could have been considered. In its clinical implementation, adaptive radiotherapy process requires deformable matching algorithms to follow patient local's deformations occurring during treatment. Nevertheless, their use has not been validated. We conducted an evaluation of the Block Matching deformable algorithm, suitable for multimodality imaging (CT/CBCT), in comparison to rigid algorithm. A study has been conducted for 10 head and neck patients based on volume of interest contours comparison for 76 CBCT. Similarity parameters used consisted on Dice Similarity Index, Robust Hausdorff Distance (in mm) and the absolute volume difference (in cc)

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Möller, Philipp [Verfasser], and Nora [Akademischer Betreuer] Zingler. "Identifizierung von diversitätsgenerierenden Retroelementen (DGRs) in Cyanobakterien und strukturelle Charakterisierung der Templat RNA eines DGRs aus dem Cyanobakterium Nostoc sp. PCC7120 / Philipp Möller. Betreuer: Nora Zingler." Kaiserslautern : Technische Universität Kaiserslautern, 2015. http://d-nb.info/1072621525/34.

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Finsterlová, Hana. "Studium vlastností sorpčních gelů pro stanovení rtuti technikou DGT." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2009. http://www.nusl.cz/ntk/nusl-216541.

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The aim of this thesis is testing of resin gels used in diffusive gradients in thin films technique (DGT) for determination of mercury in natural waters. The sorbets, chosen for preparation of resing gels were: Duolit GT- 73, Spheron- Thiol, and Chelex 100 and newly modified sorbent Iontosorb AV. At the beginning of work, the preparation procedure of all resing gels was optimized. After optimalization of preparation procedure the resin gels were tested in mercury model solutions. The recovery test and time dependence test were performed. When the basic tests were finished, they were followed by the tests of influence of natural ligand (humic acids and chlorides), and other parameters (above all pH and ionic strenght), on mercury determination by DGT technique.

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Gregušová, Michaela. "Modifikace techniky difúzních gelů (DGT) pro charakterizaci přírodních systémů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2010. http://www.nusl.cz/ntk/nusl-233319.

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Diffusive gradient in thin film technique (DGT) represents a relatively new approach for in situ determinations of labile metal-species in aquatic systems. The DGT device passively accumulates labile species from the solution while deployed in situ, and therefore contamination problems associated with conventional collection and filtration procedures are eliminated. This study deals with a possible modification of DGT technique. The key of using DGT technique for speciation analysis of metals is to find out suitable binding phase and diffusion layer. The new resin gel based on Spheron Oxin (5 sulphophenyl-azo-8-hydroxyquinoline) ion exchanger with a higher selectivity to trace metals than Chelex 100 could potentially provide more information on metals speciation in aquatic systems. The performance of this new binding phase was tested for the determination of Cd, Cu, Ni, Pb and U under laboratory conditions. The hydrogel layer based on poly(2-hydroxyethyl methacrylate) was synthesized and tested as a new diffusion gel for application in DGT technique.

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Caillat, Amélie. "Evaluation de la biodisponibilité du cuivre dans des sédiments artificiels par des méthodes biologiques avec la plante aquatique Myriophyllum aquaticum (hydroponie, biotest normalisé et Rhizotest) et géochimiques (DGT)." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4310.

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Les travaux menés durant cette thèse ont visé à évaluer la pertinence de la plante aquatique Myriophyllum aquaticum pour l'étude de la biodisponibilité du cuivre dans des sédiments ainsi que l'intérêt de la technique du gradient de diffusion en couche mince (DGT) comme outil biomimétique de cette plante. Une première expérimentation réalisée avec la plante M.aquaticum exposée selon le protocole du biotest normalisé (sous forme de verticilles) dans des sédiments artificiels dopés en cuivre a montré que ce biotest semble être un outil intéressant pour l'évaluation de la toxicité de sédiments contaminés en cuivre. En outre, aucune corrélation n'a été observée entre les mesures DGT et la bioaccumulation dans la plante M.aquaticum. Ceci est probablement lié aux conditions d'exposition des plantes. En effet, le développement des racines se faisant au cours de l'expérimentation, les processus d'incorporation du métal dans la plante ne sont donc pas constants au cours de l'expérience. Suite à ces résultats nous avons réalisé deux autres séries d'expérimentations (hydroponie et Rhizotest) dans lesquelles, les plantes ont été exposées selon un protocole modifié (plantes ayant déjà développé des racines avant leur exposition dans le sédiment). Ces expérimentations nous ont permis de montrer que la plante M.aquaticum est plutôt sensible au cuivre et qu'elle a une forte capacité à l'accumuler. De plus, les résultats obtenus ont permis de montrer que la technique DGT semble être un bon outil biomimétique de cette plante dans le cas où elle est exposée avec des racines car le prélèvement par la plante est limité par la capacité de la phase solide à réapprovisionner le métal en solution
The work carried out during this thesis aimed to assess the relevance of the aquatic plant Myriophyllum aquaticum to study the bioavailability of copper in sediments as well as the interest of the technique of diffusion gradient in thin film (DGT) as a biomimetic tool of this plant. A first experiment, performed with the plant M.aquaticum exposed according to the protocol of the standardized bioassay (as whorls) in an artificial sediment spiked with copper, showed that this bioassay appears to be a useful tool for assessing the toxicity of contaminated sediments copper. Furthermore, no correlation was observed between DGT measurements and bioaccumulation in the M.aquaticum plant. This is probably due to the exposure conditions of the plants. In fact, as the root development occurs during the experiment, the process of incorporating the metal into the plant is therefore not constant throughout the experiment.Following these results we conducted two other series of experiments (hydropony and Rhizotest) in which, plants were exposed following a modified protocol (plants having already developed roots before their exposure in the sediment). These experiments showed that the plant M.aquaticum is rather sensitive to copper and has a strong ability to accumulate it. Futhermore, the results have shown that the DGT technique seems to be a good biomimetic tool for this plant when it is exposed by roots because the plant uptake is limited by the capacity of the solid phase to replenish the metal in solution

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Uribe, Kaffure Ramiro. "Availability of Metal Cations in Aquatic Systems from DGT Measurements." Doctoral thesis, Universitat de Lleida, 2012. http://hdl.handle.net/10803/94522.

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Els nostres resultats indiquen que el gruix del disc de resina juga un paper fonamental en l'acumulació de metalls en sensors DGT. Per complexos parcialment làbils, la seva dissociació a l'interior del domini de resina és la principal font de metall acumulat. Aquest fenomen explica la independència del grau de labilitat amb respecte a la concentració de lligand d'un complex en DGT. Així mateix, ajuda a comprendre el reduït efecte barreja que es preveu amb els sensors DGT.
Un Análisis detallado de las características dinámicas de los sensores (DGT), nos indica que la penetración de los complejos en la capa de resina aumenta dramáticamente su labilidad. Aquí, presentamos expresiones analíticas aproximadas para calcular el flujo de metal, el grado de labilidad y los perfiles de concentración en un DGT, cuando se considera que los complejos pueden penetrar en la resina. La acumulación experimental de Cd en sensores DGT en el sistema Cd-NTA, confirma los análisis teóricos.
Our analysis of the dynamic features of (DGT) devices indicates that the penetration of complexes into the resin layer dramatically increases their lability. We report approximate analytical expressions for the metal flux, the lability degree and the concentration profiles in a DGT when complexes penetration is considered. The experimental accumulation of Cd by DGT sensors in Cd-NTA systems confirmed these theoretical analyses.

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Jiménez, Piedrahita Martín Emilio. "Interpreting DGT measurements beyond steady-state and perfect-sink conditions." Doctoral thesis, Universitat de Lleida, 2017. http://hdl.handle.net/10803/405372.

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La tècnica "Diffusive Gradients in Thin Films" (DGT) permet estudiar la disponibilitat de contaminants o nutrients en aigües a partir de la seva acumulació en dispositius DGT, que acumulen els analits objectiu durant un període conegut de temps. En aquesta tesi es desenvolupen models fisicoquímics que tenen en compte el transport i les reaccions químiques de les espècies presents per a la interpretació de les acumulacions. Es dedica especial atenció als efectes electrostàtics que sorgeixen a baixa força iònica (en el rang típic de valors d'aigües dolces) entre cations metàl•lics o complexos carregats i els setis de resina. La influència de l'acumulació territorial en el disc de resina i la dependència de les constants de velocitat cinètica amb la força iònica son fenòmens que es consideren explícitament. Es desenvolupa també una eina de simulació basada en la resolució de les equacions de Nernst-Plack per a reproduïr les acumulacions experimentals de Mg i Mn, així com per a comprovar l'exactitud d'algunes expressions analítiques aproximades que es presenten. També es consideren situacions en les quals els efectes d'equilibri i competició són rellevants.
Diffusive Gradients in Thin Films (DGT) technique allows studies of the availability of chemicals in waters by the deployment of DGT devices, which accumulate the target analytes for a known period of time. Physico-chemical models that consider the reactions and transport of species inside the device for the interpretation of the accumulations are developed in this thesis. Special attention is devoted to the electrostatic effects arising at low ionic strength (in the typical range of freshwaters) between metal cations or charged complexes and the resin sites. Influence of territorial binding in the resin disc and dependence of the kinetic rate constants on the ionic strength is explicitly considered. A simulation tool based on solving the Nernst-Plack equations is developped to reproduce the experimental aumulations of Mg and Mn, as well as to check the accuracy of some approximate analytical expressions here reported. Cases where the effective capacity or competition effects are relevant are also considered in this work.
La técnica analítica llamada Diffusive Gradients in Thin Films (DGT) permite estudiar la disponibilidad de contaminantes y nutrientes en aguas. Los dispositivos DGT se depositan en el medio para que acumulen el analito durante un período de tiempo determinado. En esta tesis se desarrollan modelos fisicoquímicos que consideran las reacciones y el transporte de especies dentro del dispositivo para la interpretación de las acumulaciones. Se presta especial atención a los efectos electrostáticos que se producen entre cationes metálicos o complejos cargados y los sitios de resina, para fuerzas iónicas en el rango de las aguas dulces. Se considera explícitamente la influencia del enlace territorial en el disco de resina y la dependencia de las constantes cinéticas de asociación y disociación con la fuerza iónica. Se desarrolla una herramienta de simulación basada en la resolución de las ecuaciones de Nernst-Plack para reproducir las acumulaciones experimentales de Mg y Mn, así como para comprobar la exactitud de algunas expresiones analíticas aproximadas presentadas en este trabajo. También se consideran situaciones en las cuales los efectos de equilibrio y competición son relevantes.

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Altier, Infantes Alexandra. "Diffusive Gradients in Thin-films (DGT) beyond perfect-sink conditions." Doctoral thesis, Universitat de Lleida, 2018. http://hdl.handle.net/10803/585874.

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La presencia d'elements metàl•lics en el medi ambient està fortament influenciada per les activitats antropogèniques entre les que emergeix l'ús de nous materials basats en nanopartícules metàl•liques i òxids metàl•lics. L'especiació d'ions metàl•lics juga un paper fonamental en la determinació de la biodisponibilitat, l’ecotoxicitat i en general en la seva circulació en mitjans naturals. Però la disponibilitat d'elements metàl•lics i les propietats tòxiques o nutritives depenen a mès d’un conjunt de processos fisicoquímics de caràcter dinàmic, on les condicions d'equilibri, malgrat el seu ampli ús, representen només un cas límit. La finalitat d'aquest treball ha estat la mesura dels fluxos de metalls a diferents escales de temps i espai mitjançant la tècnica analítica dinàmica DGT (Diffusive Gradient in Thin-films) així com el desenvolupament de models fisicoquímics adequats per a la interpretació dels resultats. El marc interpretatiu dels resultats DGT s'ha completat amb la inclusió d'efectes escassament descrits en la literatura recent, com ara la influència dels efectes de competició, d’equilibri o de saturació de la resina a més dels fenòmens electrostàtics a baixes forces iòniques. Es presenten expressions aproximades simples per a l'anàlisi d'aquests fenòmens, així com la seva aplicació a sistemes experimentals que permeten observar la seva bondat. Un cop abordat el treball de sistemes simples amb només ions metàl•lics, s'han estudiat sistemes amb un únic lligand i sistemes amb mescles de lligands. Amb aquests sistemes s'ha analitzat fins a quin punt la contribució dels complexos a la disponibilitat depèn de la composició del sistema, tot corroborant que mesures en sistemes amb un únic complex serveixen per predir el comportament de les mescles. A causa de les variacions espacials i temporals que poden patir les concentrations dels ions metàl•lics en aigües naturals, l'última part de l'estudi s'ha centrat en avaluar la capacitat de resposta de la tècnica DGT per mesurar fluctuacions en la concentració. Aquest estudi ha demostrat que a més de proporcionar concentracions mitjanes amb el temps en condicions relativament simples, aquesta tècnica és capaç de determinar concentracions representatives en una àmplia gamma de condicions naturals.
La presencia de elementos metálicos en el medio ambiente está fuertemente influenciada por actividades antropogénicas entre las que emerge el uso de nuevos materiales basados en nanopartículas metálicas y óxidos metálicos. La disponibilidad de elementos metálicos y sus propiedades tóxicas o nutritivas están determinadas por un conjunto de procesos físico-químicos de carácter dinámico, donde la especiación en condiciones de equilibrio, a pesar de su amplio uso, representa sólo un caso límite. La finalidad de este trabajo ha sido la medida de los flujos de metales disponibles a diferentes escalas de tiempo y espacio mediante la técnica analítica dinámica DGT (Diffusive Gradient in Thin-films) así como el desarrollo de modelos fisicoquímicos adecuados para la interpretación de los resultados. El marco interpretativo de los resultados DGT se ha completado con la inclusión de efectos escasamente descritos en la literatura reciente, tales como la influencia de los efectos de competición, equilibrio o saturación de la resina además de la relevancia de los fenómenos electrostáticos a bajas fuerzas iónicas. Se presenta el análisis de estos fenómenos, con expresiones analíticas aproximadas deducidas a partir de la formulación del problema y se aplican a sistemas experimentales para observar la validez de dichas aproximaciones. Una vez abordado el trabajo de sistemas simples con sólo iones metálicos, se han estudiado sistemas con un único ligando y sistemas con mezclas de ligandos. Con estos sistemas se ha analizado hasta qué punto la contribución de los complejos a la disponibilidad depende de la composición del sistema, corroborándose que medidas del grado de labilidad en sistemas con un único complejo pueden predecir el flujo en las mezclas. Se reportan los mecanismos fisicoquímicos que describen la influencia del efecto mezcla sobre el grado de labilidad de un complejo determinado. Debido a las variaciones espaciales y temporales que pueden sufrir los iones metálicos en aguas naturales, la última parte del estudio se ha centrado en evaluar la capacidad de respuesta de la técnica DGT para medir fluctuaciones en la concentración. Este estudio ha demostrado que además de proporcionar concentraciones promediadas con el tiempo en condiciones relativamente simples, esta técnica es capaz de determinar concentraciones representativas en una amplia gama de condiciones naturales.
The presence of heavy metals in the environment is strongly influenced by anthropogenic activities due to the emerging use of new materials based on metallic nanoparticles or metal oxides. The speciation of metal ions plays a fundamental role in the determination of bioavailability, ecotoxicity and in general in its circulation in natural media. The availability of metal ions and their toxic or nutritive properties are determined by a set of physical-chemical processes, where equilibrium conditions, despite its widespread use, only represent a limiting case. The aim of this work was to measure the flux of available metals at different time and space scales through the dynamic analytical technique DGT (Diffusive Gradient in Thin-films). The interpretative framework of the DGT results has also been completed with the inclusion of effects scarcely described in the recent literature, such as the influence of competition, saturation of the resin sites, kinetic effects in the binding of the target analyte to the resin domain or the relevance of electrostatic phenomena at low ionic strengths. Approximate analytical expressions were deduced from the basic formulation and applied to experimental systems to check the agreement with the experimental accumulations. Once the study of simple systems with only metal ions has been addressed, systems with a single ligand or systems with a mixture of complexes have been studied. These systems were analyzed to test if the composition of the system modifies the availability of the complexes. As a conclusion of this work, it was shown that the lability degree of complexes measured in single ligand systems can be used to approximately predict the accumulation in mixtures. A physicochemical explanation of the mechanism by which the lability of a complex changes in a mixture was reported. Since spatial and temporal variations in metal concentrations are common in natural waters, the last part of this study has focused on the assessment of the response capabilities of the DGT technique to measure concentration fluctuations. This study has shown that besides it provides time-weighted average concentrations over time for relatively simple conditions, this technique is able to determine accurate and representative metal concentrations in a wide range of natural conditions.

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Flores, Portal Daisy, Capcha Evangelina Gamero, and Alejos Jesica Magali Pereyra. "Propuesta de mejora de procesos de la Dirección General de Estrategia Turística-DGET MINCETUR." Master's thesis, Universidad del Pacífico, 2018. http://hdl.handle.net/11354/2103.

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El Ministerio de Comercio Exterior y Turismo (Mincetur) es el órgano rector en materia de comercio exterior y turismo. El Viceministerio de Turismo se encuentra estructurado en cinco direcciones generales, una de ellas es la Dirección General de Estrategia Turística (DGET), la cual está encargada de «formular, coordinar y ejecutar estrategias del sector orientadas al desarrollo de los productos y destinos turísticos, así como a la innovación de la oferta turística; dirigiendo, gestionando y supervisando los planes, programas, proyectos y acciones para el desarrollo de los productos y destinos turísticos. El presente trabajo de investigación es necesario para la DGET, porque pretende identificar las necesidades de sus diferentes clientes, así como los servicios públicos que debería brindar, a fin de determinar los procesos que debería desarrollar y así asegurar la calidad de sus servicios.

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Pedrobom, Jorge Henrique [UNESP]. "Especiação de urânio em águas tratada de drenagem ácida de mina usando a técnica de difusão em filmes finos por gradiente de concentração (DGT)." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/141920.

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Um dos fatores mais preocupantes na área de mineração de urânio é a drenagem ácida de mina (DAM), tal processo ocorre de maneira espontânea e descontrolada no complexo minério industrial de Poços de Caldas (CIPC). A DAM pode gerar espécies de urânio acima dos valores permitidos para lançamento em corpos hídricos. Durante o processo de DAM, o urânio, possivelmente, esta na forma de óxidos e hidróxidos de uranilo, ao atingir os corpos hídricos, sua forma pode mudar para espécies contendo grupos carbonato e sulfato. A concentração e labilidade dessas espécies são importantes para avaliação da biogeodisponibilidade do metal para o sistema aquático. A técnica de difusão em filmes finos por gradiente de concentração (DGT) tem sido utilizada para quantificação de metais na sua forma lábil e especiação de metais em diferentes tipos de amostra. Nesta pesquisa a técnica DGT foi utilizada em laboratório com diferentes fases ligantes para avaliar a aplicação em águas de DAM tratada e afluentes no entorno de mineração de urânio. A partir de imersões in situ, a técnica DGT foi utilizada juntamente com a técnica de extração em fase sólida (SPE) para avaliar a labilidade das espécies de urânio presente no sistema. Os resultados mostraram que grande parte do urânio presente nas amostras está na forma lábil. Por sua vez estes resultados se mostraram concordantes com a especiação via software MINTEQ. Por outro lado, os resultados obtidos pela SPE não foram concordantes com a técnica DGT, isso pode ser oriundo da saturação da fase ligante ou devido os diferentes tempos de residência dos íons nas diferentes técnicas.
One of the major concerns in uranium mining areas is the Acid Mine Drainage (AMD). This process occurs spontaneously and uncontrollably in Poços de Caldas Ore Industrial Complex (CIPC). DAM can generate levels of uranium species higher than the maximum allowed values for water bodies discharge. During the DMA process, uranium is possibly in the form of uranyl oxides and hydroxides and after reaching water bodies, it changes to species which contain carbonate and sulfate groups. The determination of concentration and lability of these species is important to evaluate the metal biogeoavailability to the water system. The Diffusion Gradients in Thin Films Technique (DGT) has been used for the quantification of labile metals and their speciation in several types of sample. In this research, DGT technique was used in lab with different binding layers to evaluate its suitability to DAM waters and uranium mining surrounding tributaries. Therefore, the developed method was performed in situ along the solid phase extraction technique (SPE) to assess the lability of uranium species present in the system. The results obtained by DGT technique showed that a large part of the uranium present in the samples is its labile form. Also, these results were consistent with speciation via the MINTEQ software. Moreover the results obtained by SPE were not consistent with those from DGT technique, probably because of the saturation of the binding phase or due to the different residence times of ions in different techniques.

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Panther, Jared Graeme. "Diffusive Gradients in Thin Films for Inorganic Arsenic Speciation and Electrothermal Atomic Absorption Spectrometry with a Coupled Microcolumn for Trace Metal Speciation." Thesis, University of Canterbury. Chemistry, 2008. http://hdl.handle.net/10092/3675.

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This thesis is directed towards the development of the diffusive gradients in thin films (DGT) technique for the measurement of total dissolved As, and for As speciation measurements. In addition, a preliminary investigation of a novel laboratory-based method for measuring labile metal species was carried out; this method involved the coupling of a microcolumn of adsorbent with a standard electrothermal atomic absorption spectrometer. An iron-oxide adsorbent was utilized for As measurements by DGT. The diffusion coefficients of inorganic Asv and AsIII> were measured through the polyacrylamide diffusive gel using both a diffusion cell and DGT devices. A variety of factors that may affect the measurement of total As by DGT were investigated. These factors, which included pH, anions, cations, fulvic acid, FeIII-fulvic acid complexes, and colloidal Fe, may affect the adsorption of the As species to the iron-oxide, or may affect the diffusion coefficients of the individual As species. The DGT method was further developed to selectively accumulate the AsIII species in the presence of Asv. This was achieved by the placement of a negatively charged Nafion membrane at the front of the DGT device which slowed the diffusion of the negatively charged Asv species (H₂AsO₄₂ ⁻) considerably, relative to the uncharged AsIII species (H₃AsO₃). The effect that pH, anions, and cations may have on the selective accumulation of AsIII, in the presence of Asv, was investigated. DGT devices without a Nafion membrane and with a Nafion membrane were deployed in natural waters to determine the total inorganic As and AsIII> concentrations, and to evaluate its performance. A preliminary investigation of the coupling of a microcolumn of Chelex-100 resin with a standard electrothermal atomic absorption spectrometer was undertaken to establish its value as a laboratory-based speciation method. This involved the examination of various microcolumn materials to accommodate the Chelex-100 resin, and finding an appropriate buffer that could be used to buffer the Chelex-100 resin without interfering with the ETAAS measurement. Furthermore, factors that may affect the uptake of metal by the Chelex-100 resin, such as concentration of buffer in solution, ionic strength, and conditioning of the Chelex-100 resin, were investigated.

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Hagen, Sarah. "Entwicklung einer DGT-Methode zur Erfassung von anionischen Metallkomplexen in Gewässern /." Sion, 2007. http://doc.rero.ch/record/10779?ln=fr.

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Habartová, Aneta. "Stanovení mikroprvků v mléce pomocí ICP-OES po extrakci technikou DGT." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2020. http://www.nusl.cz/ntk/nusl-433555.

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This thesis is focused on determination of microelements (Cd, Co, Cu, Fe, Mn, Ni, Pb a Zn) in milk by optical emission spectrometry with inductively coupled plasma (ICP-OES) after extraction by Diffusion Gradients in Thin films technique (DGT) containing Chelex 100 resin gel and agarose diffusion gel. The optimalization of DGT in model metal solutions was verified by recommended basic tests. The performance of the DGT technique in the diluted milk matrix was verified. By DGT technique was determined only Zn in real milk matrix with concentration 3,74 ± 0,02 mg/l. The other microelements in the prepared eluate were at or below the limit of detection of the instrumental method. The obtained results were compared with the analysis of milk after microwave digestion by ICP-OES. However, these results were below the detection limit of the device too, only Zn with concentration 3,91 ± 0,16 mg/l was measured. For the future analysis of the selected microelements in milk by DGT technique, further optimization of the preconcentration technique is required, or use of a more sensitive instrumental method.

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Schiefner, Jana [Verfasser]. "Untersuchungen zur Retrotransposition der mobilen Elemente TRE5-A und DGLT-A Dictyostelium discoideum / Jana Schiefner." Jena : Thüringer Universitäts- und Landesbibliothek Jena, 2014. http://d-nb.info/1064306667/34.

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Eliasson, Anna. "En studie av egenskaperna hos biokol som adsorberande agent i o‐DGTanordningar." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-12669.

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En ny komplex aspekt i frågan om vattenkvalité är ackumuleringen av organiska föroreningar.Den begränsade utbredningen av vattenrening i Brasilien såväl som i andra utvecklingsländervisar på ett tydligt behov av utveckling av billiga och effektiva metoder för provtagning ivatten. Bristen på den här typen av metoder försvårar idag möjligheterna att kontrolleravattenkvalitén och på så vis även arbetet med att säkerställa de sanitära förhållandena ivattentillgångar. Det här examensarbetet innehåller en sammanfattande genomgång avprinciperna för den passiva provtagningsmetoden med namnet ”Diffusive Gradients in Thin‐Films (DGT)”, som direktöversatt får det svenska namnet ”Diffusiva gradienter i tunnfilmer”.När metoden används för provtagning för att upptäcka olika organiska ämnen i vattnetbenämns den som o‐DGT.Målet med detta arbete är att ta fram en metod med målet att specifikt upptäcka olika typerav nya framväxande organiska föroreningar som i de flesta fall förekommer bara i väldigt lågakoncentrationer i vår miljö. Grundliga undersökningar genomfördes för att få svar på huruvidabiokol kan fungera som den bindande agenten i DGT apparatur och verka för att kunnaupptäcka och identifiera dessa ämnen på ett effektivt sätt.Resultaten från de undersökningar som genomförts hittills visar på att biokol har godpotential att tillämpas som bindande agent i filter för bruk i o‐DGT apparatur. De organiskaföreningarna av intresse i denna studie kunde alla detekteras, kvantifieras och identifieras.För optimering av provtagningsmetoden bör vidare studier vid varierande förhållanden medhänsyn till pH, temperatur och jonkoncentration genomföras, såväl som studier av detbindande lagrets egenskaper i förhållande till koncentration av biokol och lagrets tjocklek.Detta för att kunna optimera tekniken, och förhoppningsvis bidra till ett konventionelltanvändande av biokol på adsorberande agent i o‐DGT anordningar i framtiden.
A new complex aspect in the matter of water quality is the occurrence of emerging organicpollutants and contaminants in waste water. The currently low extent to which treatment ofwaste water is performed in Brazil, and in the world as a whole, there is a considerable needfor development of cheap and accurate in‐situ sampling methods for far‐reaching studies ofsurface water quality. The lack of such methods today makes the maintenance andestablishing of sanitary safety difficult. This diploma work gives a brief introduction to thebasic principles of the passive sampling method known as Diffusive Gradient in Thin‐films(DGT). A method that could be useful for such monitoring of quality in water bodies worldwide.The aim of this study is to develop a method, for the detection of organic emerging pollutantsand contaminants – i.e. compounds, which usually are present at very low concentrationswhen found in the environment as a result of human activity. More specifically, this workinvestigates the potential and usefulness of the application of DGT devices in detection oforganic compounds that can affect human health and ecosystems, even at lowconcentrations, however, their effects still are in need of further investigations.This study focuses on both purely technical as well as practical points of views. The efficiencyof organic DGT (o‐DGT) with biochar as the adsorbing agent is examined targeting thedetection of organic pollutants and contaminants in surface water. In this sense, the specificaim of the work is to evaluate the performance of biochar as adsorbing agent. This workshowed that the performance of biochar as the adsorbing agent in binding layers in o‐DGTsample devices can be considered as satisfactory since all compounds of interest in this studywas successfully detected, quantified an identified. Further investigations in the future areneeded to determine the effects of varying pH, temperature and ion concentration in thedeployment media, as well as the properties of the binding layer in relation to concentrationof biochar and the thickness of the layer. These in order to optimize the method for in‐situwater sampling, aiming conventional use of biochar as the adsorbing agent in the future.

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Bretier, Marie. "Évaluation de la variabilité spatio-temporelle du mercure et de l'arsenic dans les eaux de surface par échantillonnage passif." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1073.

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Les échantillonneurs passifs, développés il y a une vingtaine d’années, se présentent comme une alternative aux prélèvements ponctuels car ils permettent un échantillonnage in-situ et intégré des contaminants sur la période d’exposition. Ils présentent l’avantage d’abaisser les limites de quantification, de limiter les effets matrice lors de l‘analyse et de faciliter la conservation des échantillons. Pour les métaux, la DGT, technique la plus couramment employée, permet, dans sa configuration classique, d’échantillonner les métaux cationiques. Des adaptations de cette technique ont également permis de développer des DGT pour le mercure et l’arsenic. Néanmoins, la forme chimique de ces contaminants conditionne leur toxicité et leur biodisponibilité qui doivent être prises en compte dans la caractérisation de l’exposition des milieux aquatiques. Ainsi, cette thèse visait à : i) développer et valider, au laboratoire, des outils DGT pour la mesure de la spéciation chimique du mercure et de l’arsenic dans les eaux douces ; ii) évaluer la variabilité spatio-temporelle des concentrations en mercure et arsenic et de leur spéciation chimique à différentes échelles dans les eaux de surface par échantillonnage passif. L’étude de la spéciation de l’arsenic (AsIII + AsV) sur une unique DGT ne peut être réalisée selon le protocole habituel puisque l’extraction de l’arsenic de la phase réceptrice ferrihydrite engendre une oxydation de l’AsIII en AsV et donc une perte d’information sur la spéciation. La mise en place de plans de criblage a permis d’optimiser cette extraction et d’extraire respectivement 22 et 32 % d’AsIII et d’AsV à l’aide de dihydrogénophosphate d’ammonium (NH4H2PO4) 0.5 M à 75°C avec une conversion de 30 % de l’AsIII en AsV. Via l’application de facteurs correctifs, l’AsIII et l’AsV peuvent être mesurés à partir de 0.24 et 0.33 μg.L-1 en moyenne sur la période d’exposition des DGT (7 jours) dans un milieu aquatique à 20°C. Pour l’étude de la spéciation du mercure (HgII + MeHg) sur une unique DGT, l’étape d’analyse s’avère problématique puisqu’elle nécessite d’adapter la technique de double dilution isotopique à la DGT. Alors que le MeHg peut être mesuré par DGT à partir de 0.08 ng.L-1, les tests en laboratoire ont mis en évidence des difficultés de mesure spécifiques au HgII certainement en lien avec des propriétés de la phase réceptrice 3M qui n’ont pas pu être identifiées dans cette thèse. Les DGT ont ensuite été appliquées in-situ dans 4 contextes différents afin d’évaluer leur pertinence pour intégrer les variations spatio-temporelle des concentrations en métaux. Tout d’abord, durant les opérations de gestion sédimentaire sur le Rhône sur une quinzaine de jours, nous avons montré que les DGT étaient représentatives de la dynamique des concentrations en métaux et de la spéciation de l’As en comparaison avec l’échantillonnage ponctuel notamment en intégrant l’augmentation des concentrations en Mn, Ni, Co et As (AsIII puis AsV) dissous. Ensuite, les applications des DGT sur le Gier et la Deûle ont mis en évidence la concordance des concentrations en Hg et MeHg mesurées par DGT et échantillonnage ponctuel dans les eaux de surface dynamiques de l’échelle de quelques jours à l’échelle annuelle. Néanmoins, dans les conditions favorisant la production du mercure gazeux dissous, les concentrations en Hg estimées par DGT seraient surestimées en raison d’un piégeage de ces formes du mercure par la DGT, nécessitant d’interpréter les résultats avec précaution. Enfin, l’utilisation des DGT sur le bassin versant du lac Rapel au Chili a mis en évidence leur capacité à identifier les variations spatiales de contamination ainsi que leur pertinence pour intégrer des variations temporelles de concentrations en Hg en lien avec les opérations de gestion d’un barrage hydroélectrique
Developed around 20 years ago, passive samplers are an alternative to discrete sampling. The sampling of contaminants is realized in-situ and allows to integrate the contamination over the exposure period. Passive samplers have the advantage to lower the quantification limits, to avoid matrix effects during the analysis and to facilitate the sample preservation. For metals, DGT is the most employed technique and allow in its classic configuration to sample cationic metals. These tools were adapted in order to sample mercury and arsenic. Nevertheless, the chemical forms of these contaminants influence their toxicity and their bioavailability which have to be taken into account when characterizing the exposition of aquatic environments. Thus, this thesis aimed to: i) develop and validate, in the laboratory, DGT techniques for the measurement of arsenic and mercury chemical speciation in freshwaters; ii) assess the spatio-temporal variability of mercury and arsenic concentrations and their chemical speciation at different scales in surface freshwaters by passive sampling. Arsenic speciation (AsIII + AsV) with a unique DGT could not be assessed according to the usual procedure since arsenic elution from ferrihydrite binging gel cause an oxidation of AsIII to AsV and therefore a loss of information on the speciation. The setting up of screening plans allowed to optimize this elution step and to elute 22 and 32% AsIII and AsV, respectively, from the ferrihydrite binding gel, with ammonium dihydrogenophosphate (NH4H2PO4) 0.5 M at 75°C with a conversion of 30% of AsIII to AsV. Through the use of corrective factors, AsIII and AsV could be monitored from 0.24 et 0.33 μg.L-1 in average on the exposure period for DGT (7 days) in surface freshwaters at 20°C. For the monitoring of mercury speciation (HgII + MeHg) with a unique DGT, the analysis step proved to be problematic since it necessitates to adapt double isotopic dilution technique for the DGT. While MeHg could be measured by DGT from 0.08 ng.L-1 in surface freshwaters, laboratory tests have highlighted specific difficulties in the measurement of HgII certainly in relation to 3M binding gel properties that could not be identified during this thesis. DGT were then applied in-situ in 4 different contexts in order to evaluate their relevance for integrating spatio-temporal variations of metals concentrations. First, during dam flushing operations on the Rhône River during ~15 days, we have showed that DGT were highly representative of the dynamic of metals concentrations and As speciation in comparison with discrete sampling, notably integrating the increase of Mn, Ni, Co and As (AsIII and then AsV) dissolved concentrations. Then, the use of DGT on the Gier and Deûle sites for the monitoring of mercury speciation have evidenced the consistency between mercury and methylmercury concentrations measured by passive and discrete sampling measurements in dynamic surface freshwaters from weekly to annual scales. Nevertheless, in environmental conditions which favor dissolved gaseous mercury production, Hg concentrations estimated by DGT would be overestimated as a reason of an uptake of these mercury chemical forms by DGT, necessitating to interpret the results with caution. Finally, DGT applications on the Rapel lake watershed in Chile have highlighted DGT capacity to identify the spatial variation of contamination as well as DGT relevance to integrate temporal variations of Hg concentrations linked with hydropower production plant operations

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Lehto, Niklas J. "Developing a theoretical base for interpreting DGT measurements of bioavailability and lability." Thesis, Lancaster University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441792.

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Perez, Magali. "Développement de capteurs passifs pour le diagnostic et la gestion environnementale du cuivre en zone viticole." Thesis, Pau, 2015. http://www.theses.fr/2015PAUU3026/document.

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L’utilisation répétée de la bouillie bordelaise pour la lutte contre le mildiou a entrainé une accumulation de cuivre dans les sols viticoles. Afin d’évaluer l’impact de cette pollution, les capteurs passifs sont fréquemment utilisés pour renseigner sur la biodisponibilité du cuivre et donc sur sa toxicité. Toutefois, au vu de l’ensemble des principes de diffusion qui régissent l’échantillonnage par capteur passif, plusieurs modifications, notamment sur la géométrie, ont pu être apportées et constituent l’objet de cette étude au travers du développement de nouveaux capteurs passifs : les DMG (Diffusive MilliGel). Leur synthèse par un système millifluidique leur confère une géométrie unique, constituée de billes ellipsoïdales de dimension millimétrique. Leurs paramètres physico-chimiques ont été caractérisés. Différents paramètres tels que le temps d’exposition et les méthodes d’analyses ont été optimisés. Les DMG ont été testés au cours d’applications environnementales et leur aptitude à échantillonner la fraction labile du cuivre a été mise en évidence. Une première étude dans des eaux douces a permis de mettre en évidence l’influence de la matière organique sur la fraction retenue par DMG, ainsi que l’aptitude de ce capteur à évaluer la toxicité du cuivre. Pour cela, un organisme modèle, Ceriodaphnia dubia, a été exposé dans les mêmes conditions au cours d’une étude écotoxicologique. La comparaison entre les DMG, les DGT et une méthode par colonne de chelex a mis en évidence les avantages qu’offre ce capteur par rapport aux autres techniques. Enfin, une série d’expériences sur les sols viticoles a révélé les aptitudes des DMG à échantillonner du cuivre dans cette matrice complexe
Repeated use of copper in Bordeaux mixture to fight against mildew has led to an accumulation of this metal in the vineyard soils. To assess the impact of this pollution, the quantification of this element in the soil is essential and more precisely the quantification of the bioavailable fraction which give an indication of the copper toxicity. For that, the passive samplers appear as reliable and efficient tools. However, due to diffusion principles which control the uptake by passive samplers, an optimization of the geometry seems to be necessary and induced this study through the development of a new passive sampler: the DMG (Diffusive MilliGels). The synthesis by millifluidic process confers a unique geometry; DMG are composed of ellipsoidal beads of around 1 mm diameter. First of all, their physico-chemical parameters were characterized and analytical methods and the exposure time were optimized as well. DMG were then tested for an environmental application and their ability to sample the labile fraction of copper was thus demonstrated. Namely, analysis of freshwater by DMG allowed highlighting the influence of organic matter on the fraction retained by this passive sampler and their ability to evaluate the copper toxicity was confirmed. For that, a living organisms Ceriodaphnia dubia was exposed in the same condition during a comparative ecotoxicological study. Moreover, the comparison between DMG, DGT and a Chelex column method showed the advantages of our developed method particularly for in situ application. Finally, a series of experiments on vineyard soils was performed to reveal the abilities of DMG in copper sampling in this complex matrix

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Chostak, Cristiano Luiz. "Dispositivos DGT modificados com materiais alternativos para uso na especiação de elementos traço." reponame:Repositório Institucional da UFPR, 2014. http://hdl.handle.net/1884/36574.

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Orientador : Prof. Dr. Marco Tadeu Grassi
Dissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Química. Defesa: Curitiba, 28/03/2014
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Resumo: A técnica de difusão em filmes finos por gradiente de concentração (DGT) permite a determinação in situ de espécies químicas lábeis em águas naturais, solos e sedimentos. A sua aplicação é realizada com o uso de dispositivos compostos por uma fase difusiva (hidrogel), na qual são difundidas as espécies químicas lábeis e uma fase de ligação (Chelex-100), onde as espécies são acumuladas. Neste trabalho foi investigado o uso do argilomineral montmorilonita (MT-K10) imobilizado em agarose como fase sorvente nos dispositivos DGT, e a própria agarose como fase difusiva. Observou-se uma sorção média de 80% para as espécies metálicas Zn2+, Cu2+, Cr3+, Mn2+, Cd2+, Pb2+ e Ni2+, e a dessorção variou de 74% (Zn) a 90% (Pb e Cr). O fator de eluição estimado para a fase sorvente ficou de 0,74 (Zn) a 0,90 (Pb e Cr). Para a agarose foram encontrados coeficientes de difusão na faixa de 4,08 10-6 cm2 s-1 (Cr) a 5,77 10-6 cm2 s-1 (Pb) a 20 °C. Observou-se também uma acumulação linear das massas das espécies investigadas em função do tempo de exposição, evidenciando um comportamento como descrito pela primeira lei de difusão de Fick, sendo obtidos coeficientes de correlação que variaram entre 0,995 (Zn) e 0,999 (Cr, Ni e Pb). Em estudo de recuperação das espécies metálicas com o dispositivo proposto foram encontrados valores de 97% (Cd) a 102% (Mn e Zn). A aplicação do dispositivo modificado na determinação de espécies metálicas lábeis em amostra de água do Rio Itajaí-Açu gerou resultados satisfatórios, principalmente quanto a labilidade dos mesmos, o que evidencia que o dispositivo modificado pode vir a ser usado como uma ferramenta analítica para determinações in situ em águas naturais. Palavras-chave: Montmorilonita imobilizada, Agarose, Espécies lábeis.
Abstract: The technique of diffusion gradients in thin films (DGT) enables in situ determination of labile chemical species in natural waters, soils and sediments. Its application is carried out with the use of devices comprising a diffusive phase (hydrogel), in which labile chemical species are diffused and a binding phase (Chelex -100), where the species are accumulated. In this work we investigated the use of the clay mineral montmorillonite (MT-K10) immobilized on agarose as a sorbent phase in DGT devices, and the agarose itself as diffusive phase. There was an average sorption of 80% for the metallic species Zn2+ , Cu2+, Cr3+, Mn2+, Cd2+, Pb2+, and Ni2+, and desorption ranged from 74% (Zn) to 90% (Pb and Cr). The estimate for the sorbent phase elution factor was 0.74 (Zn) and 0.90 (Pb and Cr).. For agarose the diffusion coefficients were found in the range of 4.08 10-6 cm2 s-1 (Cr) to 5.77 10-6 cm2 s-1 (Pb). We also observed a linear accumulation of mass of the species investigated as a function of exposure time, showing a similar behavior as described by Fick's first law of diffusion, having been obtained correlation coefficients ranging from 0.995 (Zn) and 0.999 ( Cr, Ni and Pb ). In a study of recovery of metal species with the proposed device, values of 97% (Cd) to 102% (Mn and Zn) were found. The application of the modified device in the determination of labile metal species in a sample of natural water from the Itajaí-Açu river generated satisfactory results, especially regarding the lability of the species, which shows that the modified device may be used as an analytical tool for determinations in situ in natural waters. Keywords: Immobilized Montmorillonite, agarose, labile species

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Yabuki, Lauren Nozomi Marques [UNESP]. "Utilização de novos agentes ligantes obtidos a partir de biomassas para determinação de íons metálicos por meio de técnica de difusão em filmes finos por gradiente de concentração." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/150678.

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A técnica de difusão em filmes finos por gradiente de concentração (DGT) tem se consolidado como uma excelente ferramenta analítica capaz de fornecer concentrações lábeis por tempo, pré-concentração dos analitos e amostragem in situ, porém a aplicação desta técnica em águas de drenagem ácida de mina (DAM) é complicada devido à redução da adsorção do amostrador tradicional (resina ligante Chelex-100) para metais em baixo pH. Este estudo, avalia a utilização da técnica DGT para determinação das concentrações lábeis de Al, Cd, Cu, Mn, Ni, Pb U e Zn em águas de DAM, empregando novos agentes ligantes preparados a partir de biomassas (cascas de banana, borra de café e sementes de moringa) impregnadas em agarose. As medições DGT foram realizadas em soluções padrão em laboratório e in situ. Resultados laboratoriais mostram que os agentes ligantes podem ser empregados em águas com pH baixo (pH 3,5) para os íons Cd, Cu, Ni, Pb e Zn. Já os íons Al, Mn e U não apresentaram linearidade nas curvas de imersão para nenhuma biomassa pesquisada. Para a análise de amostras in situ de DAM, houve baixas recuperações dos íons Cd, Cu, Ni e principalmente para Zn com 5,7% da fração solúvel com o gel de agarose-moringa, podendo indicar a baixa eficiência dos agentes ligantes ou algum efeito matriz inerente durante a determinação por ICP-OES. Por outro lado, houve recuperações satisfatórias para a imersão em amostras do Rio Corumbataí e do Rio Piracicaba, ressaltando o emprego destes agentes ligantes pesquisados em matrizes aquáticas diferentes das matrizes de DAM. Este estudo mostra que o uso da técnica DGT pode ser estendido para águas com pH baixo (desde que sejam avaliados as limitações e condições de contorno avaliadas neste estudo) podendo ser uma ferramenta útil para o monitoramento em tempo integrado de concentrações lábeis em diferentes sistemas aquáticos.
The diffusive gradients in thin films (DGT) technique has consolidated as an excellent analytical tool capable of providing labile concentrations by time, analytical preconcentration and in situ sampling, but the application of this technique in acid mine drainage waters (AMD) is limited by the reduction of adsorption of the traditional binding layer (Chelex-100 chelating resin) to metals at low pH. This study proposes the use of the DGT technique to determine the concentrations of Al, Cd, Cu, Mn, Ni, Pb U and Zn in AMD using new binding agents prepared from biomass (Musa cavendishi banana peel, spent coffee grounds and shelled Moringa Oleifera seeds) impregnated with agarose. DGT measurements were performed in laboratory standard solutions and in situ. Laboratory results showed that the binding agents can be used in waters with low pH (pH 3.5) for Cd, Cu, Ni, Pb and Zn. Al, Mn and U ions did not present linearity in the deployment curves for any biomass studied. For the analysis of in situ AMD samples, there were low recoveries of the Cd, Cu, Ni, and mainly Zn ions with 5.7% of the soluble fraction with the agarose-moringa gel, indicating the low efficiency of the binding agents at low values pH or some inherent matrix effect during determination by ICP-OES. On the other hand, there were satisfactory recoveries for deployment in samples from the Corumbataí River and the Piracicaba River, highlighting the use of these binding layers in aquatic matrices other than AMD matrices. This study shows that the use of the DGT technique can be extended to waters with low pH (provided that the limitations and contour conditions evaluated in this study are evaluated) and can be a useful tool for the integrated time monitoring of labile concentrations in different aquatic systems.
CNPq: 142171/2014-0

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Devillers, Delphine. "Fiabilisation de la quantification des éléments traces cationiques et anioniques par la technique d'échantillonnage DGT en milieu aquatique naturel." Thesis, Limoges, 2017. http://www.theses.fr/2017LIMO0058/document.

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La technique d’échantillonnage passif DGT (« Diffusive Gradients in Thin Films ») possède de nombreux avantages (intégration des variations temporelles, abaissement des limites de quantification) qui font d’elle une méthode prometteuse pour une utilisation en réseaux de mesure pour quantifier les éléments traces dans les eaux naturelles. Cependant, il existe encore des zones d’ombre qui constituent des freins à son utilisation dans un contexte réglementaire. Ce travail a donc pour objectif d’identifier des biais potentiels et ainsi contribuer à fiabiliser la méthode. Cette étude montre que l’obtention d’un résultat avec une incertitude minimisée doit passer par la détermination expérimentale des facteurs d’élution ; cependant, l’utilisation d’une valeur standard de 0,8 pour le Cr(III) et de 0,85 pour Al(III), Cd(II), Co(II), Cu(II), Ni(II), Pb(II) et Zn(II) est proposée afin d’alléger les manipulations tout en conservant une incertitude raisonnable (<10%). L’étude de l’influence de l’encrassement des dispositifs DGT a montré que la sorption des cations Cd(II), Cu(II) et Pb(II) sur les filtres encrassés affectent respectivement peu, modérément et fortement leur accumulation dans les échantillonneurs et donc leur quantification. Des durées d’exposition de moins d’une semaine sont alors préconisées pour ces éléments. En revanche, l’encrassement a eu un impact négligeable sur le Ni(II) et sur les oxyanions As(V), Cr(VI), Sb(V) et Se(VI). Enfin, une méthode de quantification simultanée du Cr(III), essentiel à la vie, et du Cr(VI), toxique, a été développée en vue d’améliorer l’évaluation de la toxicité d’une eau. Un unique échantillonneur DGT fixe les deux formes tandis qu’elles sont ensuite sélectivement séparées par une étape d’élution. Cette méthode est robuste sur une large gamme de forces ioniques et de concentrations en sulfate mais sur une gamme de pH plus restreinte ne couvrant pas toutes les eaux naturelles (4 à 6)
The passive sampling DGT technique (Diffusive Gradients in Thin Films) has a lot of benefits (time-weighted average concentrations, low limits of quantification) and would therefore be a useful tool for monitoring studies to quantify trace elements in natural water. However, there are still some limitations and grey areas that put the brakes on the development of the method for regulatory applications. The aim of this work is to identify potential biases and contribute to increase the method reliability. This study shows that a minimized uncertainty on results can be obtained only if elution factors are experimentally determined; however, standard values of 0.8 for Cr(III) and 0.85 for Al(III), Cd(II), Co(II), Cu(II), Ni(II), Pb(II) and Zn(II) are suggested to reduce manipulations while keeping reasonable uncertainty (<10%). Studying the influence of fouling developed on DGT devices showed that the sorption of cations Cd(II), Cu(II) and Pb(II) had, respectively, a slight, moderate and strong impact on their accumulation in DGT samplers and therefore on their quantification. Samplers should then be deployed for less than one week. In contrast, fouling had a negligible impact on oxyanions As(V), Cr(VI), Sb(V) and Se(VI). Finally, a method was developed to simultaneously quantify both Cr oxidation states naturally occurring in natural waters, which are Cr(III), essential to life, and Cr(VI), toxic. Both forms are accumulated in a single DGT sampler before being selectively separated during an elution step. This method is robust for wide ranges of ionic strengths and sulfate concentrations but for a narrower range of pH (4 to 6)

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Österlund, Helene. "Applications of the DGT technique for measurements of anions and cations in natural waters." Licentiate thesis, Luleå tekniska universitet, Geovetenskap och miljöteknik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-16785.

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Since the toxicity and mobility of trace metals are related to the metals' speciation, robust methods for trace metal speciation analysis are of great interest. During the last 15 years, hundreds of scientific articles have been published on the development and applications of the diffusive gradients in thin films (DGT) passive sampling technique.In this work the commercially available DGT containing ferrihydrite adsorbent, used for determination of phosphate and inorganic arsenic, was characterised with respect to anionic molybdate, antimonate, vanadate and tungstate determination. Tests were performed in the laboratory as well as in the field. Diffusion coefficients were determined for the anions using two different methods with good agreement. Simultaneous measurements of arsenate were conducted as quality control to facilitate comparison of the performance with previous work. The ferrihydrite-backed DGT was concluded useful for application over the pH-range 4 to 10 for vanadate and tungstate, and 4 to <8 for molybdate and antimonate. At pH values ≥8, deteriorating adsorption was observed.The combination of a restricted pore (RP) version of DGT and the normal open pore (OP) DGT was used for speciation of copper and nickel at three brackish water stations with different salinities in the Baltic Sea. Time series and depth profiles were taken, and complementary membrane- (<0.22 μm) and ultrafiltration (<1 kDa) was conducted. Comparing DGT and ultrafiltration measurements indicated that copper and nickel were complexed. Due to small differences in results between the OP and RP DGTs it was suggested that the complexes were smaller than the pore size of the RP gel (~1 nm) resulting in that both DGTs accumulating essentially the same fraction. Further, there seemed to be a trend in copper speciation indicating higher degree of strong complexation with increasing salinity. The low salinity stations are more affected by fluvial inputs which will likely affect the nature and composition of the organic ligands present. Assuming that copper forms more stable complexes with ligands of marine rather than terrestrial origin would be sufficient to explain the observed trend.
Godkänd; 2010; 20100517 (helost); LICENTIATSEMINARIUM Ämnesområde: Tillämpad geologi/Applied Geology Examinator: Professor Johan Ingri, Luleå tekniska universitet Diskutant: Docent Per Andersson, Naturhistoriska Riksmuseet Tid: Fredag den 18 juni 2010 kl 10.00 Plats: F341, Luleå tekniska universitet

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Bouchard, Laurianne. "Rb-Sr Age Estimates of Pore Fluids in Sedimentary Rocks, DGR Site, Kincardine, Ontario." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/32271.

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This study is part of a project aiming for the long-term burying of nuclear wastes in Kincardine, Ontario. Bedrock formations as well as their associated waters were analyzed in drill cores from the Michigan sedimentary basin, southwest Ontario. This research utilizes geochemistry combined to strontium and rubidium isotope ratios in order to determine the origin of porewaters from Ordovician shales and limestones. It is demonstrated that these waters are the result of a mixing line between the Silurian (Guelph) and Cambrian groundwaters. This last end-member was also mixed with Precambrian brines to some extent. Strontium and rubidium isotopes also demonstrated rubidium in clays were leached by porewaters over time. Once in solution, radioactive rubidium decayed into strontium over time. This process explains the accumulation of radiogenic strontium observed in porewaters. An age estimate for the deposition of carbonates and other evaporates was calculated with the Rb-Sr isotope system. The calculated age is 453.7 million years before present for dolomites, which is consistent with the history of the site. It was possible to gen an approximate age of 339.7 million years for the formation of illites. This corresponds to the illitization process that occurred after the deposition of rocks, when the Silurian brines infiltrated the deeper Ordovician shale. It was also possible to estimate of porewaters ages.

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Szkandera, Roman. "Testování modifikovaných sorbetů Iontosorb pro užití v technice difúzního gradientu v tenkém filmu (DGT)." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2008. http://www.nusl.cz/ntk/nusl-216360.

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6-mercaptopurine was joined by diazotation and copulation reactions on Iontosorb AV. Presence of thiol groups in modified resin was showed by infrared spectrometry. Amount of thiol groups was determined by iodometric titration. Resin gel was preparated from modified resin and agarose and both of them were tested for mercury determination by DGT technique.

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Eliasson, Anna. "A study of the performance of biochar as adsorbing agent in o‐DGT devices." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-12793.

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A new complex aspect in the matter of water quality is the occurrence of emerging organic pollutants and contaminants in waste water. The currently low extent to which treatment of waste water is performed in Brazil, and in the world as a whole, there is a considerable need for development of cheap and accurate in-situ sampling methods for far-reaching studies of surface water quality. The lack of such methods today makes the maintenance and establishing of sanitary safety difficult. This diploma work gives a brief introduction to the basic principles of the passive sampling method known as Diffusive Gradient in Thin-films (DGT). A method that could be useful for such monitoring of quality in water bodies world wide. The aim of this study is to develop a method, for the detection of organic emerging pollutants and contaminants – i.e. compounds, which usually are present at very low concentrations when found in the environment as a result of human activity. More specifically, this work investigates the potential and usefulness of the application of DGT devices in detection of organic compounds that can affect human health and ecosystems, even at low concentrations, however, their effects still are in need of further investigations. This study focuses on both purely technical as well as practical points of views. The efficiency of organic DGT (o-DGT) with biochar as the adsorbing agent is examined targeting the detection of organic pollutants and contaminants in surface water. In this sense, the specific aim of the work is to evaluate the performance of biochar as adsorbing agent. This work showed that the performance of biochar as the adsorbing agent in binding layers in o-DGT sample devices can be considered as satisfactory since all compounds of interest in this study was successfully detected, quantified an identified. Further investigations in the future are needed to determine the effects of varying pH, temperature and ion concentration in the deployment media, as well as the properties of the binding layer in relation to concentration of biochar and the thickness of the layer. These in order to optimize the method for in-situ water sampling, aiming conventional use of biochar as the adsorbing agent in the future.

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Szkandera, Roman. "Vývoj techniky difúzního gradientu v tenkém filmu (DGT) pro stanoveni rtuti ve vodných systémech." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2011. http://www.nusl.cz/ntk/nusl-233340.

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The theoretical part of this doctoral thesis deals with determination of mercury and its species in aquatic systems. Special attention is paid to the use in situ sampling technique diffusive gradients in thin films technique (DGT) and its development. Current resin gels used for determination of mercury by DGT technique Duolite GT-73, Chelex-100 and Spheron-Thiol are described. Moreover, new types of resin gels including Iontosorb AV modified by imidazole or 6-mercaptopurine and commercially available titanium dioxide. Preparations of resin gels and their basic tests in model solution according to DGT Research are described. Mercury accumulation in relation to time and basic recovery test were tested and capacity of resins was determined. All tested resins meet the requirements of basic DGT Research tests and relative standard deviations of mercury in recovery tests were lower than 10 %. The sorption capacity of resins varied from 1,5 to 6 µmol.l-1 and decreased in following order: Duolite GT-73 > ISAV-IM > Chelex-100 > Spheron-Thiol > TiO2 > ISAV-MP. Mercury sorption on resins was investigated under conditions similar to those in natural waters. It was found that the ionic strength commonly occurring in natural waters does not affect the determination of mercury. The presence of chlorides significantly affects the determination of mercury using DGT with titanium dioxide and therefore this sorbent can not be recommended for the determination of mercury in sea waters. The accumulated amount of mercury, depending on the pH shows that all the sorbents can be used in natural waters with pH in the range form 4 to 8. Mercury sorption is most affected by the presence of humic acids, especially at ion-exchange resins containing other than thiol functional groups. The exception is titanium dioxide for which physical sorption of humic acid metal complexes is typical. Cadmium and copper in model solutions in the molar balance of the excess mostly influenced the sorption of mercury on Chelex-100 and Spheron-Thiol resins. After laboratory tests, the DGT units with studied sorbents were used for the determination of mercury in natural waters of South Moravia (Svratka, Jihlava and Svitava river). Mercury concentration determined using DGT units containing Duolite GT-73 resin was comparable to the total dissolved concentration of mercury in river water provided by direct determination using AAS technique. Order of magnitude smaller concentrations than the total dissolved mercury concentration were found using DGT containing Spheron-Thiol and ISAV-MP resins. These sorbents are probably able to capture only mercury present in the form of labile complexes. This can be used for speciation analysis if more DGT units with different resins are deployed together. Subtracting the measured DGT Spheron-Thiol or ISAV-MP concentrations from the DGT Duolite GT-73 concentration, information about the amount of mercury present in the form of stabile complexes can be obtained. The amount of mercury determined after application of DGT units containing ISAV-IM, Chelex 100 or TiO2 can probably represent the mercury fraction bound in even weaker complexes than fraction determined by Spheron-Thiol and ISAV-MP DGT.

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Andrade, Carlos Francisco Ferreira de. "Avaliação in situ da especiação de metais no estuário da Lagoa dos Patos utilizando o sistema DGT." reponame:Repositório Institucional da FURG, 2005. http://repositorio.furg.br/handle/1/3525.

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Dissertação(mestrado) - Universidade Federal do Rio Grande, Programa de Pós-Graduação em Oceanografia Física, Química e Geológica, Instituto de Oceanografia, 2005.
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A cidade de Rio Grande, localizada às margens do estuário da Lagoa dos Patos, possui uma intensa atividade portuária e industrial, fatores que promoveram nas últimas décadas, alterações significativas nas paisagens e na degradação dos recursos hídricos, incluindo a contaminação por nutrientes e por metais. Por ser um estuário semi-fechado, possui uma alta taxa hidrodinâmica, condicionada principalmente pela força e direção dos ventos. Os ciclos biogeoquímicos naturais dos metais na coluna dágua, podem ser alterados devido ao lançamento de metais oriundos das atividades humanas. Alterações na fração dos metais podem ocasionar uma maior biodisponibilidade destes elementos para os organismos. A determinação das espécies de metais biodisponíveis (lábil) por técnicas instrumentais ou analíticas, possuem implicações quanto à obtenção da concentração representativa do meio, por estar sujeita a erros de amostragem e preparo das amostras. Com o desenvolvimento da técnica de gradiente difusivo de membranas (DGT), obtem-se a concentração da fração lábil in situ em distintos ambientes sob diversas condições de pH, temperatura e salinidade. O presente trabalho tem como objetivo avaliar e aplicar a técnica DGT, para o monitoramento e detecção da concentração de elementos traço em distintos locais da área estuarina da Lagoa dos Patos. Para avaliar a aplicabilidade da técnica para o estuário, foram considerados dois períodos de exposição do sistema DGT em três locais: um com pouca influência (Ilha dos Marinheiros - IM) e dois com maior influencia dos despejos industriais e urbanos (Capitania dos Portos - CP e Museu Oceanográfico - MO). Para o primeiro período de exposição (2, 6 e 10 dias) das unidades de DGT foram analisados Cd, Co, Cu, Mn, Ni, Pb e Zn em DGT e água nos locais IM e CP. Para o segundo período de exposição (2, 4, 6 e 8 horas) DGT e água foram analisados para Cd, Cu, Pb e Zn no local MO em duas amostragens, uma com salinidade intermediária (MO1) e a outra com salinidade alta (MO2). Para ambos períodos de exposições, amostras de água analisadas para a fração lábil de metais com resina Chelex 100, demonstraram concentrações distintas em comparação ao DGT, evidenciando a diferença entre os dois métodos. Os resultados no DGT para o primeiro período de exposição (IM e CP) mostraram um decréscimo nas concentrações de todos os elementos, com o aumento do tempo de exposição. Isto provavelmente tenha ocorrido devido à baixa concentração de metais lábeis na água e/ou possível presença de biofilm nas unidades de DGT. Não foram reveladas concentrações significativas de Cu, Pb, Ni e Zn nos locais IM e CP. Para o segundo período de exposição, as concentrações de metais foram mais elevadas para Cd, Cu e Pb em alta salinidade (MO2), além de ter indicado aporte para este elementos no meio, quando comparado com outros estuários. Em conseqüência das variabilidades do estuário, conclui-se que uma resposta mais representativa para o sistema DGT, seria mantê-lo num período fixo de 8 a 48 horas em exposição no ambiente.
Rio Grande is a city located in the margin of the Patos Lagoon estuary and its maritime harbour and industries are very developed. During the last decades, these activities were responsible for many changes of the landscape and degradation of water resources, including contamination by nutrients and metals. This semi-closed estuary has a high hydrodynamic rate, which is determined manly by the wind direction and strength. The natural biochemical cycles of metals can be modified by discharge of metals originated by human activities. Changes in the metal fractions can lead to a higher bioavailability of these elements to the organisms. The determination of bioavailable (labile) metals by instrumental or analytical techniques can have implications on the representative environmental concentration, since errors during sample collection and preparation can occur. The development of the diffusive gradient thin-films (DGT) technique made possible the determination of labile metals in situ in distinct environments with different conditions of pH, temperature and salinity. The main objective of the present study is to apply and to evaluate the DGT technique, for the monitoring and detection of trace elements concentrations in different areas of the Patos Lagoon estuary. To evaluate the applicability of this technique to the estuary, two deployment periods of the DGT units were considered in three areas: one with low antropogenic influence (Ilha dos Marinheiros – IM) and two in high urban and industrial discharge areas (Capitania dos Portos – CP – and Museu Oceanográfico – MO). For the first period of the DGT deployment (2, 6 and 10 days) DGT and water samples were analyzed for Cd, Co, Cu, Mn, Ni, Pb and Zn at the IM and CP sites. For the second deployment period (2, 4, 6 and 8 hours), Cd, Cu, Pb e Zn were analyzed for DGT and water samples were collected at the MO point, during two different conditions of salinity, one with intermediate values (MO1) and the other with high salinity (MO2). For both deployment periods, water samples analyzed for labile fraction with Chelex-100 resin showed distinct concentrations, when compared with the DGT, indicating differences between the two methods. The DGT results showed for the first deployment period (IM and CP) a decrease with time in the concentration for all elements. Probably this had occurred due to variations on the labile form of the metals and/or the presence of biofilm. No significant differences were found in the concentration of Cu, Pb, Ni and Zn between IM and CP sites. For the second deployment period, trace metal concentrations showed higher values for Cd, Cu and Pb during high salinity (MO2) condition, as well as indicating input of these elements in the surroundings when compared with other estuaries. As a consequence of variability’s in the estuary, it can be concluded that for a more representative result of the DGT units, these should be deployed during 8 to 48h on a fixed period in the environment.

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Husson, Angélique. "Impact de la composition minéralogique des sédiments sur la biodisponibilité de l’Uranium ˸ Une approche intégrant laboratoire-terrain-bioindicateur-calcul de spéciation." Electronic Thesis or Diss., Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEM020.

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La directive cadre européenne sur l’eau initiée en 2000 a permis d’établir de nombreuses normes de qualité environnement au cours des 18 dernières années pour les composés issus de l’activité anthropique. Cependant la présence naturelle de l’uranium dans l’environnement ainsi que sa réactivité complique la construction des normes. Le transfert de l’uranium entre le sédiment, l’eau et le compartiment biologique est un sujet complexe. En effet, le passage de l’uranium au travers de la membrane cellulaire peut être lié à la composition minéralogique ainsi qu’aux paramètres physico-chimiques. L’objectif de cette étude est d’apporter des fondements scientifiques autour de ces différents paramètres et de déterminer ainsi leur impact sur l’accumulation. De cette façon, la future définition de ces nouvelles normes (NQE) prend en compte la notion de biodisponibilité des contaminants. L’impact fort de phases minéralogiques telles que la ferrihydrite est démontré tant en contexte post-mines qu’au sein d’expérimentations en laboratoire par opposition au quartz dont la capacité de sorption est faible. Une corrélation est notée entre l’accumulation obtenue par un bioindicateur.«Chironomus riparius» et celle mesurée par un système de capteurs passifs intégratifs nommés DGT. Cette corrélation est liée à la présence d’espèces potentiellement biodisponibles telles que UO2OH2(aq), dont l’abondance est obtenue par des calculs de spéciation. Ces premières conclusions permettent de donner les fondements scientifiques afin d’alimenter le débat autour de la construction des normes de qualité environnement
The European Water Framework Directive introduced in 2000 has allowed to establish numerous quality environment standards for the last 18 years for compounds stemming from anthropic activity. However, the natural presence of uranium in the environment as well as itsreactivity complicates the construction of standards. The transfer of uranium betweensediment, water and the biological compartment is complex. Indeed, the passage of uranium through the cellular membrane can depend on the mineralogical composition as well as on the physico-chemical parameters. The objective of this study is to bring scientific foundationsaround these various parameters and hence to determine their impact on the accumulation.This way, the future definition of these new standards (NQE) takes into account the notion of bioavailability of contaminants. The strong impact of mineralogical phases such as ferrihydrite is both demonstrated in a post-mining context as well as within experiments in laboratory, as opposed to the quartz whose sorption capacity is low. A correlation is noted between the accumulation obtained by bioindicator “Chironomus riparius” and the one measured by a system of integrative passive sensors called DGT. This correlation is linked to the presence of potentially bioavailable species such as UO2OH2(aq), whose abundance is obtained by speciation calculations. These first conclusions give scientific foundations to feed the debate around the construction of the environment quality standards

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Nia, Yacine. "Utilisation d'un échantillonneur passif (DGT) pour l'évaluation de la remobilisation des métaux dans les sédiments : expérimentation et modélisation." Thesis, Aix-Marseille 3, 2011. http://www.theses.fr/2011AIX30048.

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Les enjeux écologiques, réglementaires et économiques imposent que des méthodologies robustes d’évaluation des risques environnementaux des sédiments contaminés soient proposées aux gestionnaires et autres parties prenantes. Dans ce travail, nous avons développé une nouvelle démarche permettant d’évaluer le transport et la mobilité des métaux dans les sédiments.La DGT (Diffusion Gradient in Thin films) est un échantillonneur passif capable de prélever le métal labile en solution et le métal remobilisable par la phase particulaire. Dans cette étude, un modèle original permettant l’interprétation des cinétiques expérimentales de la DGT dans les sédiments appelé PRObabilistic multi-compartmental model for Finting DGT kinetics in Sediments (DGT-PROF) a été développé. Il considère la présence de deux pools de métal labile correspondants aux métaux labiles fortement et faiblement adsorbés sur la phase solide. La pertinence de l’approche DGT-PROFS a été évaluée sur un panel de 34 sédiments artificiels constitués en laboratoire qui diffèrent par : la présence ou pas d’hydroxydes de fer (goethite ou ferrihydrite), la présence ou pas d’acides humiques, le type de contaminant (Cd ou Cu) et l’âge de la contamination (8, 65 et 190 jours). Cette démarche permet aussi d’évaluer l’effet de ces paramètres sur la remobilisation des métaux dans les sédiments.Les résultats montrent que la capacité du sédiment à relarguer le métal dépend inversement du pH et de l’âge de la contamination. La présence des hydroxydes de fer augmente significativement la capacité de la phase solide du sédiment à fixer le métal. Cependant, la présence des AH augmente la labilité des métaux vis-vis la DGT via la formation de complexes humiques mobiles.La complémentarité des ces deux outils (DGT et DGT-PROFS) a ensuite été confrontée à des mesures DGT effectuées sur des sédiments naturels provenant de différentes régions de France, et possédant des seuils de contamination en Cd, Ni, Pb et Mn très contrastés
Evaluation of the mobility and bioavailability of metals associated to sediments have an important economic issue for the management of contaminated sites. Therefore, environmental, economic and regulation issues require to have access to a robust methodologies for environmental risk assessment of contaminated sediments. In this work, we developed a new approach for assessing the transport and mobility of metals in sediments. Diffusive gradients in thin-films (DGT) is a dynamic in-situ measuring technique that assesses the kinetics of metal resupply from the solid phase to the pore water. In this study, an original model for the interpretation of DGT experimental kinetics in sediments called DGT-PROFS model was developed. It allow to quantify metal partitioning between two particulate pools, describing weak and strong interactions with metals. The relevance of the DGT / DGT-PROFS approach was evaluated in a variety of formulated sediments that differed in the presence or not of humic acids (HA) and/or iron hydroxides (i.e., goethite and ferrihydrite). The impact of the time after contamination of the solid phase (aging effect) was also evaluated. Also, this approach allows to evaluate the effect of these parameters on the remobilization of metals in sediments. The results showed that sediments capacity to release metals depends strongly on the pH, HA and the age of the contamination. Results interpretation by DGT-PROFS model show that in the presence of HA and absence of iron hydroxides, Cd is mainly associated with weak sites, while Cu is bound to strong sites. Similarly, in the presence of both iron hydroxides and HA, Cu appeared to be more heavily associated with the strong sites than did Cd. When the incubation time increased from 8 to 190 days, a proportion of Cd initially adsorbed onto weak sites transferred to the strong sites, suggesting that the adsorption of Cd on sediments is partially controlled by slow kinetic processes. The complementarity of these tools (DGT device and DGT-PROFS model) was then evaluated on natural sediments from different regions of France, and having contamination levels of Cd, Ni, Pb and Mn very contrasting

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Fauvelle, Vincent. "Evaluation de la contamination en pesticides des tributaires du Bassin d’Arcachon et développement d’un échantillonneur passif spécifique des herbicides anioniques." Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14715/document.

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Le Bassin d’Arcachon souffre depuis le début des années 2000 de crises environnementales qui ont engendré la régression de l’herbier de zostères et la mortalité épisodique des naissains d’huîtres. Dès lors, la pression toxique et notamment phytosanitaire a été mise en cause et a fait l’objet de plusieurs suivis environnementaux dans la lagune et ses principaux tributaires depuis 2005. L’étude présentée ici porte sur le suivi des apports en pesticides vers le Bassin d’Arcachon par les eaux continentales. Sa plus-value réside dans l’élargissement du panel de molécules suivies, notamment avec la prise en compte des composés acides ; dans l’utilisation d’échantillonneurs passifs de type POCIS (Polar Organic Chemical Integrative Sampler) ; et dans l’acquisition d’une chronique pendant près de deux ans. Du fait de l’inadéquation du POCIS (et des autres échantillonneurs passifs aquatiques disponibles actuellement), une stratégie d’échantillonnage ponctuel mensuel a été mise en place pour le suivi des herbicides organiques acides. La mise en évidence par la suite de la prédominance de ce substances dans la contamination des tributaires du Bassin d’Arcachon a constitué une avancée majeure dans la caractérisation de la pression toxique du milieu, et a par ailleurs montré les besoins en matière d’échantillonnage passif pour ce type de contaminants. Par conséquent, des outils adaptés à leur échantillonnage ont été développés, en se basant sur des dispositifs préexistants. Le caractère intégratif de l’échantillonneur a été optimisé soit en adaptant la géométrie, soit en modifiant la nature de la phase réceptrice. Ensuite, l’aspect quantitatif des dispositifs a été amélioré en adaptant l’approche PRC (composé de performance et de référence), ou bien en utilisant un gel diffusif
From the early 2000s, the Arcachon Bay suffers from environmental crises that have led to the decline of the Zostera spp. meadows, and to the episodic mortality of oysters spats. Therefore, the toxic pressure (including pesticides) has been questioned, and several environmental monitoring programs have been established since 2005. This new monitoring program consisted to expand the range of monitored compounds (including acidic herbicides), to use POCIS (Polar Organic Chemical Integrative Sampler) for the passive sampling of polar compounds, and to monitor continuously the main Arcachon Bay tributaries for nearly two years. Because of the inadequacy of POCIS (and other devices currently available), a monthly grab sampling strategy has been implemented for the monitoring of acidic herbicides. The highlighting of the predominance of the acidic metabolites of chloroacetanilides in the Arcachon Bay tributaries has been a major advance in the characterization of the toxic pressure, and pointed out, otherwise, the needs for a specific passive sampling tool for these contaminants. Therefore, several passive samplers have been developed, based on existing devices (POCIS and Diffusive Gradient in Thin-film). The integrative behaviour of the samplers has been first optimized by adapting the geometry (exposure surface area, and amount of receiving phase), or by changing the nature of the receiving phase. Then, the quantitative behaviour has been improved by adapting the PRC (performance and reference compound) approach, or using a diffusive gel

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33

Daiminger, Christine. "WWW - eine Erfolgsgeschichte mit Differenzen ein Beitrag zur Geschichte der Professionalisierung der Verhaltenstherapie und der DGVT in der BRD /." [S.l.] : [s.n.], 2005. http://www.diss.fu-berlin.de/2005/64/index.html.

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Wurie, Haja R. "Determination of the intracellular localisation of the DGAT enzymes and the effect on metabolic function in different cell types." Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/80262/.

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Triglycerides (TAG) synthesis and secretion have major influences on postprandial and fasting triglyceridaemia and on hepatic steatosis, parameters that affect the development of insulin resistance and type-2 diabetes. Two main enzymes (diacylglycerol acyltransferases – DGATs) that catalyse the final reaction of TAG synthesis have been identified, DGAT1 and DGAT2. They play non-redundant roles in different tissues, highlighted by the very different phenotypes of Dgat1-/- and Dgat2-/- mice. Using three inhibitors with different actions on these enzymes, the differential localisation of DGAT2 (cytosolic aspect) and DGAT1 (both cytosolic and luminal aspects) activities within the endoplasmic reticular membranes of rat liver microsomes, HepG2 and Caco-2 cells and their relative contributions to total DGAT activity were determined. Subsequently, the sensitivity to these inhibitors on the processes of the incorporation of preformed (exogenously supplied) fatty acids, de novo synthesised fatty acids, and glycerol into the acyl and glyceroyl moieties of the TAG molecules was determined. Inhibition of DGAT2 affected primarily the incorporation of de novo synthesised fatty acids and of nascent diglycerides (into which glycerol was newly incorporated), whilst inhibition of DGAT1 affected primarily the retention of the glyceroyl moiety within the TAG fraction stoichiometrically with the incorporation of preformed fatty acid, but not with that of fatty acids derived from de novo lipogenesis. In spite of its modest contribution toward overall cellular DGAT activity, inhibition of DGAT2 was rate-limiting for TAG synthesis, indicating that DGAT2 and DGAT1 act in series with DGAT2 being upstream of DGAT1. Similar conclusions were drawn from data obtained with Caco-2 cells, with important differences owing to the expression of other enzymes expressing DGAT activity. The dual topology of DGAT1 in the ER membrane is suggested to enable the synthesis of TAG on either aspect of the membrane with DAG connecting the two pools of TAG in the cytosolic and ER luminal cellular compartments.

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Kane, David. "Evaluating phosphorus availability in soils receiving organic amendment application using the Diffusive Gradients in Thin-films (DGT) technique." Thesis, Cranfield University, 2013. http://dspace.lib.cranfield.ac.uk/handle/1826/8001.

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Phosphorus is a resource in finite supply. Use of organic amendments in agriculture can be a sustainable alternative to inorganic P, provided it can meet crop requirements. However a lack of consistent knowledge of plant P availability following application of organic amendments, limits its potential. Studies suggest chemical extraction procedures, may not reflect plant available P. The Diffusive Gradients in Thin-films (DGT) technique is based on natural diffusion of P via a hydrogel and sorption to a ferrihydrite binding layer; which should accurately represent soil P (CDGT) in a plant available form. The aim of this research was to evaluate changes in soil P availability, following the addition of organic amendments, cattle farmyard manure (FYM), green waste compost (GW), cattle slurry (SLRY) and superphosphate (SP) using Olsen P and DGT. The research included incubation, and glasshouse studies, using ryegrass (Lolium perenne L.). Soils with a history of application of the aforementioned organic amendments were used (Gleadthorpe), as well as a soil deficient in P (Kincraigie). The hypotheses were as follows H1 A build-up of P available by diffusive supply, from historic treatment additions and subsequent availability from fresh treatment additions will be demonstrated by DGT. H2 Historical treatment additions are more important at determining yield and P uptake than fresh additions. H3 DGT can detect changes in P available by diffusive supply following addition of different treatments and subsequently following lysis of microbial cells on a soil deficient in P. H4 DGT will provide a more accurate indication of plant P availability than organic amendments in a soil deficient in P. H5 P measurements using DGT will be lower from organic amendments than superphosphate.H6 DIFS simulations of soil kinetic parameters will provide additional information about how treatments influence P resupply from solid phase to solution following DGT deployment. Cont/d.

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Forsberg, Jerry. "Trace metal speciation in fresh and brackish waters using ultrafiltration, DGT and transplanted aquatic moss /." Luleå, 2005. http://epubl.luth.se/1402-1757/2005/77.

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Bořek, Tomáš. "Toxické kovy ve vodě a sedimentech vodní nádrže Brno." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2009. http://www.nusl.cz/ntk/nusl-216543.

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Diploma thesis deals with usage of the diffusive gradients in thin films technique (DGT) for the determination of labile metal species in the surface water and sediments of Brno water reservoir. Sediment and water samples were collected on the selected sides of Brno water reservoir on September and October 2008. The DGT technique was used for determination of depth profiles of Fe, Mn, Pb, Cd, Zn, Cu, Ni and Al. The DGT probes with three different thicknesses of diffusive layer were applied into the sediment samples. The obtained results gave the information about release of metals from solid phase into the pore water of sediment. The concentrations of Fe, Mn, Pb and Cd in sediments were determined by atomic absorption spectrometry after microwave decomposition. The DGT technique was used also for determination of Fe, Mn, Pb and Cd in surface water from Brno water reservoir.

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Guibal, Robin. "Adaptation du DGT et fiabilisation du POCIS pour le suivi des pesticides et résidus de médicaments dans les eaux de surfaces." Thesis, Limoges, 2018. http://www.theses.fr/2018LIMO0107/document.

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Les techniques d’échantillonnage passif comme le POCIS (« Polar Organic Chemical Integrative Sampler ») ou le o-DGT (« Diffusive Gradient in Thin films » pour composés organiques) permettent d’obtenir une bonne représentativité de la contamination des eaux de surface par les micropolluants organiques. Cependant, ces dispositifs sont soumis à des conditions environnementales qui engendrent des biais sur la quantification des analytes cibles. Une meilleure connaissance des données issues de l’échantillonnage passif a donc été essentielle afin de les utiliser sur deux têtes de bassin versant. Pour cela un dispositif innovant, utilisant la technique DGT, a été développé et testé sur 4 pesticides ioniques. La robustesse du o-DGT étudiée sur une plage de pH allant de 3 à 8 et de force ionique allant de 0,01 à 1 mol.L-1, lui permette d’être utilisé dans la plupart des eaux naturelles. Des déploiements en milieu naturel et dans une rivière artificielle, en même temps que le déploiement de POCIS, a permis de comparer les performances de ces 2 échantillonneurs. Le POCIS, avec des limites de quantification plus basses, était l’échantillonneur le plus adapté au suivi de contamination des têtes de bassin versant, cependant il a été nécessaire de l’améliorer pour fiabiliser les concentrations de micropolluants mesurées.. Une libération de polyéthylène glycol issu des membranes utilisées pour la fabrication de POCIS provoquant des effets de matrice a été supprimé grâce à deux bains successifs d’1h d’un mélange 50:50 méthanol:eau suivi d’un bain de rinçage à l’eau. De même, une quantification des molécules cibles est obtenue grâce à des taux d’échantillonnage (Rs) déterminés dans conditions proches de celle de l’environnement. Les Rs de 44 molécules pharmaceutiques ont été déterminés grâce à une rivière artificielle. Après cette étape de fiabilisation, le POCIS a été appliqué à deux têtes de bassin versant avec des suivis de 1 et 3 ans sur, respectivement, l’Aixette et l’Auvézère. Des prélèvements ponctuels ont également été réalisés et ont pu mettre en évidence des pics de pollution de pesticides (> 2,3 g.L-1). Ces suivis « semi-continus » ont permis de mettre en évidence et de caractériser l’existence d’une pollution des têtes de bassin versant par les pesticides et les résidus pharmaceutiques
Passive samplers, such as POCIS (Polar Organic Chemical Integrative Sampler) or o-DGT (Diffusive Gradient in Thin films for organic compounds), allow to estimate surface water contamination by organic micropollutants. However, these devices are influenced by environmental conditions and quantification error can occur. A better knowledge of passive sampling data was therefore essential before the samplers’ application on headwater streams. An innovative sampler, using DGT technique, has been developed and tested on 4 ionic pesticides. The sampler is robust in a pH range from 3 to 8 and an ionic strength range from 0,01 to 1 mol.L-1, which allows to use it in the most of natural waters. Field deployments of POCIS alongside o-DGT in natural waters and in an artificial river made it possible to compare their performances. POCIS with lower limits of quantification was the most suitable sampler for monitoring organic compounds in headwater stream. A release of polyethylene glycol from membranes used in POCIS causing matrix effects was removed by two successive baths of 1h of a 50:50 mix of methanol:water followed by a rinsing bath of water. Quantification is achieved through sampling rates (Rs) estimated under revelant conditions. Rs of 44 pharmaceuticals were estimated in an artificial river. After these steps, POCIS was applied in two headwater streams for 1 and 3 years on Aixette and Auvézère, respectively. Grab samples were also collected and pollution peaks of pesticides were detected (> 2,3 g.L-1). These “semi-continuous” monitorings highlighted a pollution of headwater streams by pesticides and pharmaceuticals

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Müller, Christian. "Ermittlung- und Berechnung des Eintrages von Schwermetallen in Fliessgewässer : Probennahme mittels DGT-Methode und automatischem Probenahmesystem /." Sion, 2006. http://doc.rero.ch/search.py?recid=8308&ln=fr.

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40

Belsaas, Kristin. "Bruk av DGT og HR-ICP-MS for studier av metallers døgn- og sesongvariasjoner i vassdrag." Thesis, Norges Teknisk-Naturvitenskaplige Universitet, Institutt for matematiske fag, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-10569.

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To vassdrag, Søra i Trondheim kommune og Vorma i Orkdal kommune, er blitt studert med hensyn på konsentrasjoner av oppløste metaller over en periode på fem-seks måneder fra oktober 2009 til april 2010. Det ble funnet tendenser til både døgn- og sesongvariasjoner i metallkonsentrasjoner som varierte mellom ulike metaller. Det ble tatt i bruk DGT, men resultatene fra disse skilte seg i de fleste tilfeller vesentlig fra resultatene fra manuelle vannprøver. Det ble derfor ansett som vanskelig å benytte seg av DGT for å kartlegge døgn- og sesongvariasjoner i metallkonsentrasjoner i vassdrag. Søra og Vorma ble også sammenlignet med hverandre og selv om begge vassdragene er forurenset kan Søra alt i alt likevel sies å være det vassdraget med størst forurensningsbelastning da det i Søra i tillegg til forhøyede metallkonsentrasjoner også er funnet høyt bakterieinnhold og høyt innhold av næringssalter, som er blitt beskrevet i tidligere studier.

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41

Seo, Sang Beom. "The isolation and characterization of mutations in the deoxyguanosine triphosphate triphosphohydrolase (dgt) gene of ESCHERICHIA COLI." Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/25334.

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42

Prokofyeva, Evgeniya. "The application of diffusion gradient method (DGT) for ecological risk assessment of natural and artificial matrixes." Doctoral thesis, Università Politecnica delle Marche, 2015. http://hdl.handle.net/11566/243013.

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Il lavoro presenta le attività condotte per studiare, nell'ambito della valutazione di rischio ambientale, un metodo che descriva quantitativamente la mobilità di inquinanti organici persistenti nella fase solida del suolo e dei sedimenti. Il lavoro ha implicato la progettazione e la realizzazione di una sonda passiva in grado di campionare per diffusione le molecole organiche (Organic Diffusive Probe, ODP). La sonda ODP riproduce le condizioni necessarie per attuare la tecnica del gradiente diffusivo su strato sottile (Diffusion Gradients in Thin-film, DGT) ed è stata progettata adattando lo schema della sonda DGT, originarialmente pensata per il campionamento dei metalli pesanti. Le principali modifiche sono quelle relative ai materiali utilizzabili, come recettori dei contaminanti e come riempimento dello strato diffusivo, e all'aspetto esteriore della sonda. La sonda è stata calibrata usando carbone attivo come materiale recettore. Quindi, sono stati studiati sia l'influenza della geometria della sonda (rapporto superficie/spessore diffusivo) che quella dei parametri chimicofisici del suolo sull'adsorbimento degli inquinanti organici. È stata anche presa in esame l'influenza delle diverse concentrazioni di inquinante a parità di suolo e di suoli con diverse proprietà chimicofisiche a parità di concentrazione inquinante. I risultati mostrano la fattibilità dell'applicazione della tecnica DGT alla valutazione del rischio ambientale da inquinanti organici persistenti. La ricerca ha infine preso in considerazione l'applicazione della sonda su due casi studio di suolo e sedimento. Il primo ha esaminato campioni di suolo provenienti dal sito contaminato dell'impianto di coke della Novolipetsk Steel. Nel secondo la tecnica DGT è stata applicata all'analisi di Idrocarburi Policiclici Aromatici su sedimenti marini dell'Adriatico. I risultati confermano la possiblità di applicare la sonda per la misura della frazione organica labile nel suolo e nel sedimento.
This work is devoted to describing the activities performed to test a method for measuring the mobility of persistent organic pollutants in the solid phase of soils or sediments within the context of environmental pollution risk assessment. The method is based on the design of a new probe for the passive sampling of organic pollutant in soils. The probe, namely an organic diffusive probe (ODP), was prepared to reproduce diffusion gradients in thin-films (DGT). The new probe is designed by adapting DGT, originally meant for heavy metals, to organic molecules. The main modifications relate to: the material suitable as organic pollutant receptor; the shape of the overall testing device and the materials filling the probe. The ODP was calibrated with activated carbon as a receptor material. Moreover, the influence of geometric characteristics of the probe and the influence of different physicochemical soil parameters on adsorption of organic pollutants were studied. Furthermore, were investigated influences of different concentration of pollutant in samples from one type of soil and the same concentration of the pollutant in samples with different physiochemical properties. Results from ODP experiments showed the feasibility of application of the diffusion gradient for environmental risk assessment of pollution by organic compounds. Further research has been focused on practical applications of the diffusion gradient method. The study included the testing of the principle of diffusion gradient on soil samples from coke production site, Novolipetsk Steel company. The latest work has been concentrated on analysing diffusion processes of polycyclic aromatic hydrocarbons (PAHs) in sediments of the Adriatic Sea. These results confirm the possibility of applying such adopted configurations of the passive probe that is able to measure the labile fraction of organic pollutants in soils and sediments.

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Freitas, Ana Cláudia de [UNESP]. "Polimorfismos nos genes DGAT-1 e A2M e suas associações com produção e qualidade do leite de búfalas da raça Murrah." Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/110562.

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A identificação de genes que influenciam características de produção e composição do leite tem sido o foco de vários estudos nos últimos anos, como o caso do gene candidato DGAT1, reconhecidamente envolvido com o conteúdo de gordura no leite sendo de grande interesse para o melhoramento de rebanhos leiteiros. Outro gene importante, o A2M, apresenta associação aos processos celulares do sistema imune, como a contagem de células somáticas (CCS), diretamente ligada à qualidade do leite e saúde dos animais. Nesse contexto, objetivou-se verificar a existência de polimorfismos em regiões específicas dos dois genes descritos e possíveis associações na produção de leite e seus constituintes em bubalinos. Para tanto, um grupo de animais formado inicialmente por 200 búfalas foi avaliado. Amostras de folículos pilosos dos referidos animais foram utilizadas para extração de DNA. Mediante PCR, foram amplificados fragmentos que, posteriormente, foram analisados através do sequenciamento. Foram identificados SNPs, avaliadas as frequências alélicas e genotípicas, foi realizado o teste de desequilíbrio de ligação e também, análises de variância dos efeitos dos SNPs. Foram identificados ao todo seis SNPs, sendo que apenas três encontravam-se em região codificante, dois no éxon 17 do gene DGAT1 (SNP 162G/A e 164C/T) e um no éxon 29 do gene A2M (SNP 241A/G). O SNP 164C/T apresentou associação com as características porcentagem de gordura e porcentagem de proteína no leite em nível de 5% de significância, já o SNP 241A/G além de apresentar associação com as mesmas características, apresentou também com a característica produção de gordura. Diante desses resultados, supõe-se a relação dos SNPs encontrados e identificados nas regiões codificantes do DNA com características de composição e qualidade do leite, podendo, estes SNPs serem utilizados como marcadores ...
The search for genes that affect milk yield and composition traits has been the aim of many studies in recent years, as the case of candidate gene DGAT1, admittedly involved with the fat content in milk being of great interest to breeders of dairy herds. Another important gene, A2M, has association with cellular processes of the immune system, such as somatic cell count (SCC), directly linked to milk quality and animal health. The aim of the present study was to verify the existence of polymorphisms in this two genes and their effects in composition and milk yield traits in breed buffaloes (Bubalus bubalis). The sample was constituted by 200 buffaloes cows. Hair were used for the extraction of DNA. After PCR, the samples were analyzed by sequencing techniques. Were found six SNPs, but only three in the coding region, two in exon 17 of the DGAT1 gene (SNP 162G/A and 164C/T) and one in exon 29 of the gene A2M (SNP 241A/G ). The SNP 164C/T was associated with the characteristics fat percentage and protein percentage in milk at 5% significance, since the SNP 241A/G besides having association with the same characteristics, also presented with the characteristic fat production. Before addition, is supposed there may be some relation of this SNPs and characteristics of composition from milk like, production and percents of fat and protein in to the milk. Therefore, it can be completed these SNPs can be used as moleculars markers in MAS in buffaloes

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Freitas, Ana Cláudia de. "Polimorfismos nos genes DGAT-1 e A2M e suas associações com produção e qualidade do leite de búfalas da raça Murrah /." Jaboticabal, 2014. http://hdl.handle.net/11449/110562.

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Orientador: Humberto Tonhati
Coorientador: Rúsbel Raúl Aspilcueta Borquis
Banca: Guilherme Costa Venturini
Banca: Nedenia Bonvino Stafuzza
Resumo: A identificação de genes que influenciam características de produção e composição do leite tem sido o foco de vários estudos nos últimos anos, como o caso do gene candidato DGAT1, reconhecidamente envolvido com o conteúdo de gordura no leite sendo de grande interesse para o melhoramento de rebanhos leiteiros. Outro gene importante, o A2M, apresenta associação aos processos celulares do sistema imune, como a contagem de células somáticas (CCS), diretamente ligada à qualidade do leite e saúde dos animais. Nesse contexto, objetivou-se verificar a existência de polimorfismos em regiões específicas dos dois genes descritos e possíveis associações na produção de leite e seus constituintes em bubalinos. Para tanto, um grupo de animais formado inicialmente por 200 búfalas foi avaliado. Amostras de folículos pilosos dos referidos animais foram utilizadas para extração de DNA. Mediante PCR, foram amplificados fragmentos que, posteriormente, foram analisados através do sequenciamento. Foram identificados SNPs, avaliadas as frequências alélicas e genotípicas, foi realizado o teste de desequilíbrio de ligação e também, análises de variância dos efeitos dos SNPs. Foram identificados ao todo seis SNPs, sendo que apenas três encontravam-se em região codificante, dois no éxon 17 do gene DGAT1 (SNP 162G/A e 164C/T) e um no éxon 29 do gene A2M (SNP 241A/G). O SNP 164C/T apresentou associação com as características porcentagem de gordura e porcentagem de proteína no leite em nível de 5% de significância, já o SNP 241A/G além de apresentar associação com as mesmas características, apresentou também com a característica produção de gordura. Diante desses resultados, supõe-se a relação dos SNPs encontrados e identificados nas regiões codificantes do DNA com características de composição e qualidade do leite, podendo, estes SNPs serem utilizados como marcadores ...
Abstract: The search for genes that affect milk yield and composition traits has been the aim of many studies in recent years, as the case of candidate gene DGAT1, admittedly involved with the fat content in milk being of great interest to breeders of dairy herds. Another important gene, A2M, has association with cellular processes of the immune system, such as somatic cell count (SCC), directly linked to milk quality and animal health. The aim of the present study was to verify the existence of polymorphisms in this two genes and their effects in composition and milk yield traits in breed buffaloes (Bubalus bubalis). The sample was constituted by 200 buffaloes cows. Hair were used for the extraction of DNA. After PCR, the samples were analyzed by sequencing techniques. Were found six SNPs, but only three in the coding region, two in exon 17 of the DGAT1 gene (SNP 162G/A and 164C/T) and one in exon 29 of the gene A2M (SNP 241A/G ). The SNP 164C/T was associated with the characteristics fat percentage and protein percentage in milk at 5% significance, since the SNP 241A/G besides having association with the same characteristics, also presented with the characteristic fat production. Before addition, is supposed there may be some relation of this SNPs and characteristics of composition from milk like, production and percents of fat and protein in to the milk. Therefore, it can be completed these SNPs can be used as moleculars markers in MAS in buffaloes
Mestre

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Cole, Russell Francis. "Determination of organotin compounds in coastal sediment pore-water by diffusive gradients in thin-films (DGT) technique." Thesis, University of Portsmouth, 2016. https://researchportal.port.ac.uk/portal/en/theses/determination-of-organotin-compounds-in-coastal-sediment-porewater-by-diffusive-gradients-in-thinfilms-dgt-technique(f452f268-d8c7-4ca9-acb3-ffd6fb733f8e).html.

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Organotin compounds still present a high risk to biota in the aquatic environment. Measuring the behaviour of the freely dissolved fractions of these compounds in sediment compartments is challenging, with costly and sensitive analytical techniques required for their measurement. Diffusive gradients in thin-films (DGT) allow for the uptake and pre-concentration of analytes in a binding gel and is used to measure dissolved metals and some organic compounds. The utility of novel silica-bound sorbents (C8, C18, mixed phases) as DGT binding gels for the sequestration of organotins in the marine environment was the primary focus of work in this project. The C8 sorbent showed the optimum performance in the uptake and recovery of organotins across pH, ionic strength and in filtered sea water. It was used subsequently as the binding layer in DGT sediment devices (160 mm × 34 mm) overlaid with a mixed-cellulose ester membrane (0.45 μm) as the single diffusion layer. These were used to investigate pore water mobilisation and concentrations of organotins in coastal sediment cores collected from a contaminated site. Organotins demonstrated a non-sustained uptake scenario, with DGT flux and freely dissolved concentrations in pore water measured to decline at 1 cm depth intervals over deployments of 2-28 days. Using time series, concentrations in pore water at t = 0 were calculated providing empirical pore water depletion curves for sediment cores. Using standard laboratory instrumentation (i.e. gas chromatography-mass spectrometry) low limits of detection were achieved (TBT = 0.4 ng L^-1 after 2 weeks of sampling).

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Lindfors, Sarah. "Metal Fractionation in Snowmelt Runoff : A Comparison between Ultrafiltration and Diffusive Gradients in Thin Films (DGT) techniques." Thesis, Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-65018.

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Urban runoff is a non-point pollution source deteriorating water quality of natural watersystems. The composition of urban runoff vary depending on land use, seasonal changes anddifferent surfaces that come into contact with the water. Urban runoff often contain metals andAl, Cd, Cr, Cu, Fe, Ni, Pb and Zn are of particular concern for the environment due to theirpotential toxicity. Metals in runoff can be present in different phases, associated with particles,colloids of different sizes or dissolved in the free phase. The different phases vary in size butalso overlap each other. Information about metal phases and species in runoff is essential tounderstanding metal transport and design runoff treatment systems.Membrane filtration followed by ultrafiltration is an established technique to distinguish theparticulate, colloidal and truly dissolved fractions. However, the “truly dissolved” fraction mayconstitute of the free phase, colloidal phase or both of them since the technique onlydiscriminates by size. Diffusive gradients in thin films (DGT) is a relatively new technique thatmeasures the labile fraction, sometimes referred to as the most bioavailable fraction. The labilefraction includes free metal ions and small complexes available to diffuse through a diffusivelayer under a reasonable period of time. Kinetically inert species are discriminated.The scope of this thesis was to investigate metal fractionation in snowmelt runoff from differenturban surfaces using two techniques, ultrafiltration and DGT. An additional aim was to studythe speciation described by the two techniques in the different types of runoff. Two types ofrunoff were sampled to conduct measurements on. Runoff from well-defined catchments (anindustrial area and a parking lot) and roof runoff from two roofing materials (zinc and coppersheet). In total, four runoff samples were membrane filtrated (pore size 0.45 μm) followed byeither ultrafiltration (delimiting 3 kNMWL) or DGT measurements in the laboratory. Analysisof metals was conducted in all steps and pH, electric conductivity, total suspended solids andtotal organic carbon was measured in the untreated samples.The results show that metal concentrations were generally higher in the catchment runoffcompared to the roof runoff with few exceptions, Cu and Pb from copper roof and Zn from zincroof. Regarding fractionation, the two types of runoff showed similarities when it came tometals mainly bound to particles. The metals that were abundant in several phases showeddifferent fractionations between the catchment runoff and the roof runoff. The metals releasedin roof runoff was to a higher extent found as free ions compared with the catchment runoff. Adiscussion was held about the different metal fractions and treatment possibilities. Comparingthe two techniques, the DGT measurements could be used to further interpret the results fromthe ultrafiltration regarding the colloidal and free phase.
Dagvatten är en diffus föroreningskälla som försämrar vattenkvalitén hos naturliga vattendrag.Samansättningen av föroreningar i dagvatten kan variera beroende på markanvändning,årstidsvariationer och de olika ytor som dagvattnet kommer i kontakt med. Dagvatten innehållerofta metaller och Al, Cd, Cr, Cu, Fe, Ni, Pb och Zn kan vara toxiska för miljön i högakoncentrationer. Metaller i dagvatten kan förekomma i olika faser beroende på om de är bundnamed partiklar, kolloider av olika storlek eller om de är i löst fas. De olika faserna varierar istorlek men överlappar även varandra något. Kunskap om de olika faserna är viktigt förförståelsen om metallernas transportmekanismer och för att kunna designa eller förbättrareningssystem.Membranfiltrering följt av ultrafiltrering är en etablerad teknik för att särskilja partikulärtmaterial, kolloider och den sanna lösta fraktionen. Dock så kan den ”sanna lösta” fraktioneninnehålla antingen den kolloidala fasen, lösta fasen eller båda två eftersom tekniken baseras påstorleksfördelning. DGT (på engelska diffusive gradients in thin films) är en relativt ny tekniksom mäter den labila fraktionen som ibland benämns som den mest biotillgängliga fraktionen.Den labila fraktionen inkluderar fria metalljoner men även små komplex som kan diffunderagenom en diffusionsgel under en rimlig tidsperiod. Species som är kinetisk inerta kommer intemätas.Syftet med detta arbete var att undersöka metallfraktionering i snösmälts-avrinning från olikaurbana ytor genom att använda två tekniker, ultrafiltrering och DGT. Ett delmål var även attgranska de species som beskrevs av de två teknikerna i de olika typerna av dagvatten. Två olikaslags dagvatten samlades in och undersöktes. Dagvatten från väldefinierade avrinningsområden(ett industriområde och en parkeringsplats) och takavrinning från två takmaterial (zink- ochkopparplåtar). Totalt fyra dagvattenprover genomgick membranfiltrering (porstorlek 0,45 μm)följt av antingen ultrafiltrering (avgränsning 3 kNMWL) eller DGT mätningar i laboratoriet.Metallanalyser genomfördes i alla steg och pH, konduktivitet, suspenderade partiklar ochorganiskt kol mättes på det obehandlade proverna.Resultaten visade att de uppmätta metallkoncentrationerna var generellt högre i takavrinningenjämfört med dagvattnet från de hela avrinningsområdena. Dock med några undantag, Cu ochPb från koppartak och Zn från zinktak. När det kom till fraktionering fanns det likheter mellanavrinning från hela områden och från taken beträffande de metaller som till största del varbundna till partiklar. Däremot var det skillnad mellan de olika avrinningstyperna gällandefraktionering av metallerna som förekom i flera av faserna. I takavrinningen fanns det i störreutsträckning metaller som fria joner jämfört med avrinningsområdena. En slutsats var att DGTmätningarna kunde användas till att tolka resultaten från ultrafiltreringen när det gälldekolloidala och fria faserna.

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Hopkins, (nee Kaup) Marianne. "Characterization of Genes involved In Development and Senescence." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/1257.

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Plant development is complex and highly regulated. Tens of thousands of genes have been sequenced for the model plant Arabidopsis thaliana, yet few have been functionally annotated and characterized. This thesis describes the expression analysis and characterization of four genes in Arabidopsis. Three of these belong to the eukaryotic translation initiation factor 5A (eIF5A) gene family, and the fourth encodes diacylglycerol acyltransferase 1 (DGAT1). Putative roles for these genes in the development of Arabidopsis thaliana are described.

eIF5A is the only known protein to contain the amino acid hypusine. It has been demonstrated previously that eIF5A acts as a shuttle protein, moving specific mRNAs from the nucleus to the cytoplasm for translation. In Arabidopsis thaliana (At), there are three isoforms of eIF5A, and it is clear from the present study that they each have a unique temporal and spatial expression pattern. AteIF5A-1 and -2 are up-regulated during natural senescence and wounding/pathogenesis, respectively, and it is proposed that they regulate the onset of programmed cell death during these events. AteIF5A-3 is up-regulated in elongating meristem of the root, and it is proposed that this isoform is involved in cell growth.

Over-expression of the individual AteIF5A isoforms in planta resulted in pleiotropic phenotypes. When AteIF5A-1 or AteIF5A-2 was over-expressed, the phenotypes observed were indicative of their putative roles in the translation of proteins required for programmed cell death. When AteIF5A-3 was over-expressed, the phenotypes were indicative of a role for this protein in the regulation of cell and tissue elongation.

Lipid analysis of rosette leaves from Arabidopsis thaliana revealed an accumulation of triacylglycerol with advancing leaf senescence coincident with an increase in the abundance and size of plastoglobuli. The terminal step in the biosynthesis of triacylglycerol in Arabidopsis is catalyzed by DGAT1. When gel blots of RNA isolated from rosette leaves at various stages of development were probed with the Arabidopsis EST clone, E6B2T7, which has been annotated as DGAT1, a steep increase in DGAT1 transcript levels was evident in the senescing leaves coincident with the accumulation of triacylglycerol. The increase in DGAT1 transcript correlated temporally with enhanced levels of DGAT1 protein detected immunologically. Two lines of evidence indicated that the triacylglycerol of senescing leaves is synthesized in chloroplasts and sequesters fatty acids released from the catabolism of thylakoid galactolipids. First, triacylglycerol isolated from senescing leaves proved to be enriched in hexadecatrienoic acid (16:3) and linolenic acid (18:3), which are normally present in thylakoid galactolipids. Second, DGAT1 protein in senescing leaves was found to be associated with chloroplast membranes. These findings collectively indicate that DGAT1 plays a role in senescence by sequestering fatty acids de-esterified from galactolipids into triacylglycerol.

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Zahradníčková, Olga. "Expresní přeprava nebezpečných věcí." Master's thesis, Vysoká škola ekonomická v Praze, 2009. http://www.nusl.cz/ntk/nusl-18443.

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The diploma thesis deals with the transport of dangerous goods in courier services. It is divided into three parts. The first part explains the term dangerous goods and its interpretation in different legal standards. In this part selected articles of the ADR Agreement and IATA DGR Regulations for road and air transport of dangerous goods are described. After the theoretical part the practical part begins, which deals with the practical aspects of transport of dangerous goods by selected courier companies and the service provided. This part also tries to identify the incidents which may happen during the transport of dangerous goods. The third part of the diploma thesis examines the transport possibilities of a particular shipment, vaccine of the fox against rabies produced by Bioveta, a.s. company. This part suggests two possible ways of transporting the vaccine, describes the necessary formalities to be followed and compares the price offers of the surveyed companies for this transport.

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Trávníčková, Jana. "Transport kovů v systému půda/rostlina. Porovnání metody aktivního a pasivního vzorkování (Technika difúzního gradientu v tenkém filmu)." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2011. http://www.nusl.cz/ntk/nusl-233341.

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The doctoral thesis deals with comparison between copper uptake by radish (Raphanus sativus L.) and concentration of copper measured by a DGT-device and concentration of copper obtained by extraction with generally used extraction agents (HNO3, NaNO3 and water). Plants were cultivated in pot experiments on a tested non-treated and gradually spiked soil. The amount of copper was determined in various part of radish (whole plant, above- and below-ground part) after mineralization in the APION mineralizer by ET – AAS. The highest concentration was in belowground part, especially in root tissues and sheel of root bulb. It confirms copper is associated with cell walls. The amount of copper taken by radish up does not pass beyond sanitary standards not even in spiked soils and consummation of radish is not unhealthy. Good correlations were found between copper concentration in radish and the amount of copper extracted with HNO3, NaNO3 and water and the amount found in soil solution. Results of extraction with HNO3 confirmed the amount of copper was stable in spiked soils during the pot experiments. The DGT experiments have shown that the rate of resupply from the solid phase to soil solution is constant during the deployment time. Whereas the release of copper decreases after 24 hours in natural soil. Copper added to soil in form of cupric ions is present in the different form after one month-equilibration than copper present in unspiked soils. The results obtained by DGT measurements were approximately up to two orders of magnitude lower than copper concentration obtained by leaching with sodium nitrate. The extraction with sodium nitrate does not provide true reflection of metal availability to plant root system and soil microorganism. High values of correlation coefficients (R2 > 0,9) were found between concentration of copper in radish plant and the concentration of copper in soil solution measured by DGT technique. Concentration of copper in soil solution was three times higher than concentration measured by DGT technique. Soil solution contains species of copper that are not measured by DGT technique and available to plants. Concentration of metals obtained by DGT measurements is more closely to real concentration of bioavailable forms of metal in soil. Therefore it is possible to recommend the DGT technique as a technique for determination of bioavailable forms of copper in soils.

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Jabbar, Rawaa Abdullatif Abdul. "Using the DGT to investigate the soil chemistry of P and Cd in sandy loam soil after the application of phosphorus fertilizers." Thesis, Griffith University, 2019. http://hdl.handle.net/10072/386826.

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A recently developed DGT with a mixed binding layer of Chelex and Metsorb (TiO2) was successfully deployed in fresh and seawater to simultaneously measure available cations and anions. But, to date, no studies have used similar DGTs in soils. This study used the Metsorb Gel in two types of DGTs the Metsorb Chelex Mixed Binding layer (MBL-DGT) and the Metsorb Chelex Double Binding layer (DBL-DGT) or sandwich DGT to determine the concentration of available P and Cd (CDGT) in soil. Three experiments were conducted to assess the accuracy, sensitivity, and capacity of the new DGTs to measure the availability of P and Cd (CDGT) in a sandy loam soil. The study also investigated the relationship between the CDGT of P and Cd in the soil and concentrations of available P and Cd in plants and leachate water. Three scenarios were prepared for the assessment of the DGTs. First, the MBL-DGT was deployed in a large-scale flume filled with sandy loam soil, which was fertilized with Single Super Phosphate (SSP) of three different doses (0.01, 0.1, and 0.5 mg P L-1). Second, a biological experiment was conducted in a greenhouse using the tomato plant (Lycopersicon esculentus) as an indicator to assess the reliability of the CDGT of the available P and Cd measured in soil solution and that absorbed by the plants. This experiment used the same type of sandy loam soil, with three types of P fertilizers: SSP, Egyptian Reactive Phosphate (ER) and phosphorus soft rock from Nutri-tech Solution (NTS) applied at four dosages (0, 100, 200 and 250 kg P ha-1). Third, three consecutive doses of the three fertilizers were added to the sandy loam soil to investigate the capacity of the MBL-DGT. The repeated fertilizer application simulated the repeating application of P fertilizer in the field cycle. The mobility of available P and Cd to the leachate water was monitored by deploying the DGTs at different depths in the soil. This technique was used to evaluate the sensitivity of the DGTs when deployed in the soil for 4, 7 and 14 days. In addition, the new DGT measurements were compared with conventional measurements of P and Cd, using the Olsen and NH4Cl extraction techniques, respectively. Results of all three experiments confirmed that the MBL-DGT and the DBL-DGT were versatile measures of P and Cd availability and mobility in soil. The Metsorb mixed binding layer uptake of iii P and Cd rose with increasing P fertilizer dose. The new DGTs were sensitive to fertilizer type due to the differences in the solubility properties of the three fertilizers. The new DGTs showed that the excessive use of P fertilizers in the sandy loam soil increased the mobility of available P and Cd to the leachate water. PDGT and CdDGT had stronger correlations with P and Cd content in the plants than the conventional P and Cd extraction methods. These findings indicated that the DBL-DGT mimicked the process of plant P uptake. The MBL-DGT was also able to measure the most plant accessible form of Cd from the soil solution. MBL-DGT measurements of P and Cd were also better correlated with total P and Cd than those of conventional extraction methods. The capacity of the MBL-DGT for Cd uptake did not exceed the effective capacity of the MBL-DGT previously recorded by Panther et al. (2010). On the other hand, the MBL-DGT capacity for available P uptake was 42,000 ng per disc which was slightly higher than that recorded by Panther et al. (2014). Quantitative assessment of available P in the soil which has recently received high doses of P fertilizer will require MBL-DGTs with higher capacity. Further research is needed on different soil types and different crops to obtain a more comprehensive understanding of when the MBL-DGT can be practically applied in the field.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
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