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Molekularbiologische Untersuchungen zu zentralnervösen Alterungsprozessen der Reproduktionsfunktion in der weiblichen Ratte / Molecular Biological Analysis of Central Nervous Age-Related Processes of the Reproduction Functions in the Female RatMakhouly, Bassel 03 October 2002 (has links)
Die GABA-ergen Neurone als Teil des GnRH-Netzwerkes spielen eine Rolle bei den Veränderungen der altersabhängigen Prozesse der Reproduktionsfunktion. Um die Regulation der gonadalen Steroide auf die Expression von GAD in reproduktionsabhängigen Regionen zu untersuchen, wurde im ersten Teil der vorliegenden Arbeit das männliche Rattenmodell gewählt. Nach der Untersuchung des endokrinen Zustands der Tiere anhand der Radioimmunoassay-Methode (RIA) wurden die zellulären Gentranskripte der beiden Isoformen von GAD, GAD65 und GAD67, mittels der Methode der in situ Hybridisierung in der POA, im Nukleus suprachiasmaticus (SCN), im mediobasalen Hypothalamus (MBH) und im Gyrus dentatus bestimmt. In allen untersuchten Regionen konnte nach der Kastration und einer anschließenden dreiwöchigen Erholungszeit kein Effekt beobachtet werden. Die Administration von Estradiol bewirkt in der POA eine signifikante Erhöhung der Expression von GAD65 und GAD67 um nahezu 40%. In den restlichen Regionen konnte dagegen kein Effekt gemessen werden. Die Testosteronbehandlung zeigte eine negative Wirkung auf die Regulation nur von GAD67: Eine 30%-ige Abnahme in der POA und eine 15%-ige im SCN. Im Gegensatz dazu trat im MBH und im Gyrus dentatus eine Verminderung der Expression nur bei GAD65 auf. Aus den hier vorgestellten Ergebnissen kann folgendes abgeleitet werden: Testosteron und Estradiol regulieren in unterschiedlicher Weise die Expression von GAD und so wiederum die inhibitorische Funktion von GABA. Da in der SCN, im MBH und im Gyrus dentatus im Gegensatz zu Estradiol eine Testosteron-Wirkung gemessen wurde, existiert eine eigene androgene Regulation von GAD. Weil die Estradiol-Zugabe eine Zunahme der Expression von GAD bewirkte und dieser Effekt von einer Abnahme der LH-Konzentration im Serum der betroffenen Tiergruppe begleitet wurde, ist die These bestätigt, dass GABA mit ihren inhibitorischen Funktionen zur Übermittlung der positiven Rückkopplung von Estradiol auf die LH-Freisetzung auf der Ebene der POA und nicht auf der Ebene der Axone agiert. Im Gegensatz zu Estradiol kann eine Progesteronbehandlung bei persistent östrischen Ratten einen LH-Peak auslösen und somit den Östrus-Zyklus wieder in Gang bringen. Aufgrund dieser Tatsache wurde im zweiten Teil der vorliegenden Arbeit ein Tiermodell zur Untersuchung der molekularbiologischen altersabhängigen Veränderungen entwickelt. Dabei wurden drei Monate alte proöstrische Ratten (Y) und 12 Monate alte persistent östrische Ratten (MA) benutzt. Die MA-Ratten wurden mit Progesteron behandelt. Sowohl die MA-Ratten als auch die Y-Ratten wurden um 13 Uhr und um 17 Uhr getötet. Eine unbehandelte MA-Gruppe, deren Tiere um 10 Uhr getötet wurden, diente hier als Kontrollgruppe. Anhand der LH-Messung der untersuchten Gruppen wurde ein Kontrollwert (5 ng/ml LH) für die positive Reaktion der Tiere auf Progesteron (responding animals) festgestellt. Es konnte bei 44% der persistent östrischen Ratten ein erhöhter LH-Spiegel erfolgreich wieder erreicht werden. In den Gruppen dieses Modells entstand eine Analogie zwischen den Gruppen der behandelten MA-13-Uhr und Y-13-Uhr Tiere sowie zwischen den responding animals und den Y-17 Uhr-Tieren. Um aussagekräftige statistische Veränderungen entlang der hypothalamo-hypophysio-ovariellen Achse in individuellen Tieren zu erhalten, wurde die Taqman®-PCR und die quantitative, kompetitive RT-PCR eingesetzt. Dabei wurden die folgenden Gene untersucht: ER α und ER β, GnRH, GnRH-R, GAD65 und GAD67, sowie FSH-β. In der POA, Hypophyse und im Ovar wurde altersabhängigen Genexpression beobachtet: Eine signifikante Abnahme der Expression von ER β sowohl in der Gruppe responding animals als auch in deren analoger Gruppe wurde in der POA (34 %), Hypophyse (44 %) und im Ovar (um die 30 %) gemessen. In der Hypophyse verzeichneten die mRNA-Transkripte von ER α bei der Gruppe der behandelten mittelalten Ratten der 13 Uhr-Gruppe eine Zunahme von 55% und bei der 13-Uhr-Gruppe der jungen Ratten einen Anstieg von 153 %. Ebenso nehmen die mRNA-Konzentrationen von FSH-β sowohl bei den responding animals als auch bei deren analoger Gruppe in gleichem Masse (ungefähr 300 %) zu. Da die Veränderungen der Expression von ER β, ER α und FSH-β bei den zwei analogen Gruppen auftritt, ist zu vermuten, dass diese Gene altersabhängig expremiert und an der Zyklusregulation ursächlich beteiligt sind. Die restlichen Gene zeigten entlang der Achse keine altersrelevanten Veränderungen. Da ER β-Expressionsveränderungen in der POA, in der Hypophyse und im Ovar gemessen wurden, konnte der wichtigste Schluss der hier vorgestellten Untersuchungen gezogen werden, dass nämlich ER β für den Erhalt des Zyklus essentiell sein kann. In diesem Teil der vorliegenden Arbeit wurde ein Tiermodell zur molekular biologischen Untersuchung der altersabhängigen Veränderungen mit sehr zufriedenstellender Ausbeute zur Wiederherstellung des Östrus-Zyklus (44%) erfolgreich entwickelt. Dieses Modell ermöglichte darüber hinaus die Untersuchung einer relativ hohen Anzahl an Genen entlang der hypothalamo-hypophysio-ovariellen Achse.
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Traffic Prediction From Temporal Graphs Using Representation Learning / Trafikförutsägelse från dynamiska grafer genom representationsinlärningMovin, Andreas January 2021 (has links)
With the arrival of 5G networks, telecommunication systems are becoming more intelligent, integrated, and broadly used. This thesis focuses on predicting the upcoming traffic to efficiently promote resource allocation, guarantee stability and reliability of the network. Since networks modeled as graphs potentially capture more information than tabular data, the construction of the graph and choice of the model are key to achieve a good prediction. In this thesis traffic prediction is based on a time-evolving graph, whose node and edges encode the structure and activity of the system. Edges are created by dynamic time-warping (DTW), geographical distance, and $k$-nearest neighbors. The node features contain different temporal information together with spatial information computed by methods from topological data analysis (TDA). To capture the temporal and spatial dependency of the graph several dynamic graph methods are compared. Throughout experiments, we could observe that the most successful model GConvGRU performs best for edges created by DTW and node features that include temporal information across multiple time steps. / Med ankomsten av 5G nätverk blir telekommunikationssystemen alltmer intelligenta, integrerade, och bredare använda. Denna uppsats fokuserar på att förutse den kommande nättrafiken, för att effektivt hantera resursallokering, garantera stabilitet och pålitlighet av nätverken. Eftersom nätverk som modelleras som grafer har potential att innehålla mer information än tabulär data, är skapandet av grafen och valet av metod viktigt för att uppnå en bra förutsägelse. I denna uppsats är trafikförutsägelsen baserad på grafer som ändras över tid, vars noder och länkar fångar strukturen och aktiviteten av systemet. Länkarna skapas genom dynamisk time warping (DTW), geografisk distans, och $k$-närmaste grannarna. Egenskaperna för noderna består av dynamisk och rumslig information som beräknats av metoder från topologisk dataanalys (TDA). För att inkludera såväl det dynamiska som det rumsliga beroendet av grafen, jämförs flera dynamiska grafmetoder. Genom experiment, kunde vi observera att den mest framgångsrika modellen GConvGRU presterade bäst för länkar skapade genom DTW och noder som innehåller dynamisk information över flera tidssteg.
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Impact of Fabrication Processes of Small-Molecule-Doped Polymer Thin-Films on Room-Temperature PhosphorescenceThomas, Heidi, Haase, Katherina, Achenbach, Tim, Bärschneider, Toni, Kirch, Anton, Talnack, Felix, Mannsfeld, Stefan C. B., Reineke, Sebastian 18 April 2024 (has links)
The development of organic materials displaying room-temperature phosphorescence is a research field that has attracted more and more attention in the last years. Most studies focus on designing or optimizing emitter molecules to increase the phosphorescent performance in host:emitter systems. Rarely, the overall thin-film preparation routines are compared with respect to their triplet-state luminescence yield. Herein, different film preparation techniques are investigated using the very same emitter molecule. A variation of host polymer, post-annealing temperature, and fabrication procedure is evaluated with respect to the obtained phosphorescent lifetime, photoluminescent quantum yield, and phosphorescence-to-luminescence ratio. This study elaborates the importance of different film preparation techniques and gathers a concise set of data which is helpful to anyone optimizing the phosphorescence of a particular system.
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Fossilization : a case study of an adult learnerDe Wit, Veronica Diane 06 1900 (has links)
Linguistic fossilization is a prevalent phenomenon in adult ESLA and presents a perpetual
pedagogical challenge to teachers. Despite controversy about the theoretical concept, research is
increasingly showing that persistent erroneousness cannot be attributed to single causal factors.
This single case study examines controversial aspects surrounding the concept and formulates
criteria for identifying fossilization. The study investigates the conversational output of an
independent adult learner over a period of nine months and presents a holistic exploration of
causal influences. The findings substantiate that fossilization arises from changing combinations
of factors, and that such combinations are unique to the situation of each adult learner. The key
to the successful treatment of fossilized errors may lie in identifying their roots, which can be
achieved by analyzing output and through discussion with learners in order to gain insight into
their experience of the learning process. Results also suggest that a critical perspective on the
theoretical construct is needed in order to investigate the phenomenon in adult second language acquisition. / Linguistics / M.A. (Teaching English to Speakers of Other Languages (TESOL))
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探討大學實驗室之持續創新 / How do the university laboratories conduct persistent creation and innovation?戴君玲, Tai,Chun-Ling Unknown Date (has links)
大學,一向被視為知識的殿堂;大學裡的實驗室,更是激盪新概念、產生新知識的重要場域。因此,大學實驗室可說是知識殿堂裡的智慧泉源;新的知識,不論是對於基礎科學的貢獻,或是應用技術的開發,都可以不斷地在那裡被製造出來。
為了明瞭大學實驗室裡持續創新的樣貌,特別是經過多代傳承、創新成果仍如湧泉般不斷出現的實驗室,本研究針對已在科學界屹立不搖一百三十三年的卡文迪什實驗室與八十三年的台大藥理學教室,進行分析後發現:維持優良的傳統與學風、仔細選擇研究領域並用心地開拓與經營、選擇優秀人才並加以培育,是他們得以歷經艱困草創期、成長期與轉型期,經過多代的傳承,仍在不同研究時期或領域都能獨領風騷的三項重要因素。
「傳統與學風」所保存的是實驗室的核心價值觀;這些核心價值是用以支持創新的土壤。「研究領域的開拓與經營」則須掌握大環境的變化,選擇適合發展的領域,並依據手中的資源擬定經營策略;這樣做即可保持身段的柔軟、不斷刺激進步。「人才的選擇與培育」則提供了足量的優質人力,可以執行創造的工作。 / Universities are considered as the knowledge palace while the laboratories therein are the most important places where surging the new concepts and producing knowledge. Therefore, the university laboratories become the wellspring of knowledge. Both basic and applied researches produced therein will contribute to the domain knowledge.
In order to realize why some university laboratories can conduct persistent creation and innovation, two cases which have long history during several generations were analyzed; one is the Cavendish Laboratory of Cambridge University, U.K. and another one is the Pharmacology Laboratory of National Taiwan University, College of Medicine. Both laboratories are considered as the outstanding ones with very good performance in frontier researches. Moreover, many great scientists including Nobel Prize Laureates and Academicians were educated and trained in these laboratories. Most important of all, each generation of these laboratories kept producing creative and innovative accomplishments as well as the long-lived companies do in the business world.
The main findings of this research are: 1. retaining the excellent traditions and academic atmosphere; 2. choosing research area carefully and managing it attentively; 3. selecting outstanding talents and educating them, are the key success factors to foster the university laboratories toward incessant innovation. First of all, the traditions and academic atmosphere they preserved are considered to be the core values which cultivate the emerging of creation as well as innovation. Moreover, these long-lived laboratories devoted themselves to the research areas which had been chosen very carefully based on the macro-environment and resources they had in hands. By doing so, they can keep on going forwards. Nevertheless, a lot of talents are necessary for implementing researches in these laboratories. After all, great creation or innovation could not come true without the elite.
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Challenging the boundaries of criminal justice and social policy : responses to priority offendersDisley, Emma Rose January 2008 (has links)
This thesis examines the interaction of criminal justice policy and social policy within the Prolific and Priority Offenders Scheme (PPOS), a government initiative which aims to reduce offending by persistent offenders. The research on which this thesis is based takes an interpretative approach to social inquiry and employs a qualitative methodology. It examines the operation of four PPO Schemes in the Thames Valley through semi-structured interviews with 22 practitioners and 16 offenders, and participant observation of over 45 multi-agency meetings. The interaction between crime and social policy is explored through examination of three aspects of the PPOS: the coercion of offenders within the Schemes; the working practices and roles of the police and probation officers seconded to the Schemes; and the way in which information and intelligence is used and generated within the Schemes. The central argument of this thesis is that the widely-accepted idea that social policy is being ‘criminalised’ provides an inadequate account of the relationship between criminal justice and social policy in the PPOS. Rather, this Scheme evidences a merger of criminal justice and social welfare agendas, which includes elements of the ‘socialisation’ of crime policy in addition to elements of ‘criminalisation’ of social policy. Whilst the ultimate aim of the PPOS is to reduce crime, and whilst social welfare services such as health, housing and benefits are provided in pursuance of this aim, the ways in which these services are provided accords with the ethos and values of social policy. The idea of a merger of criminal justice and social policy has relevance beyond the PPOS, providing a framework for analysis of other contemporary criminal justice policies, and contributing to broader debates in criminology which have for so long been dominated by the ‘criminalisation’ thesis.
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Profil de pratique des médecins omnipraticiens en santé mentale au QuébecImboua, Armelle 06 1900 (has links)
Au Québec, face à la prévalence élevée des problèmes de santé mentale et à la pénurie de médecins psychiatres, le médecin omnipraticien (MO) occupe une place primordiale dans la prise en charge et le suivi des soins de santé mentale.
Dans le contexte de réforme du système de santé mentale axée sur un renforcement de la collaboration entre les MO, les psychiatres et les équipes de santé mentale, notre étude vise à mieux comprendre la pratique clinique et la pratique collaborative développée par les MO, leur appréciation des outils de travail et de la qualité des services de santé mentale, dans le but d’améliorer la complémentarité des soins au niveau primaire.
Cette étude transversale impliquait 1415 MO de neuf territoires de centre de santé et de services sociaux (CSSS) du Québec. L’échantillon final était constitué de 398 MO représentatifs de lieux de pratique diversifiés et le taux de réponse était de 41%.
Nos résultats mettent en évidence que la pratique clinique et la pratique collaborative des MO diffère selon le degré de gravité des problèmes de santé mentale des patients rencontrés, c’est à dire, trouble transitoire/modéré de santé mentale (TTM.SM) ou trouble grave de santé mentale (TG.SM), et que les MO sont favorables au fait de travailler en collaboration avec les autres professionnels de la santé mentale.
Ainsi, il apparaît important de renforcer l’accessibilité des MO aux professionnels de la santé mentale, particulièrement les psychiatres, et de les informer de l’existence des autres acteurs en santé mentale sur leur territoire, pour renforcer la collaboration et la qualité des soins primaires de santé mentale. / In Quebec, considering the high prevalence rate of mental health disorder and the scarcity of psychiatrists, general practitioners (GPs) hold an importante role in the management and the follow-up of mental health care.
In the context of the ongoing mental health system reform aimed at reinforcing collaboration between GPs, psychiatrists and mental health teams, our objectives are to have a better understanding of clinical practice and collaborative practice, developed by GP and their assessment of working tools and quality of mental health services, in order to improve the complementary of primary mental health care.
The study was carried out using a cross-sectional design, involving 1415 GPs from nine Quebec territories. The final sample included 398 GPs, representing diverse practice places, and the response rate was 41%.
The study highlighted that GPs have different clinical and collaboration practices according to the seriousness of mental disorder patients seen, i.e. transient and moderate mental disorder (TMMD) or serious and permanent mental disorder (SPMD); and GPs strongly support care coordination efforts with all mental health professionals.
Therefore, it appears important to reinforce GP accessibility to other mental health professionals, particularly psychiatrists, and to inform them on the presence of all actors in mental health in their territory, in order to develop collaboration and quality of primary mental healthcare.
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Évaluation de la densité osseuse et du statut nutritionnel en vitamine D chez des enfants prépubères avec allergie au lait non résoluePerrone, Vanessa 12 1900 (has links)
L'allergie au lait de vache (ALV) représente l'allergie alimentaire la plus fréquemment
rencontrée durant l'enfance. Cette allergie a longtemps été reconnue comme transitoire
mais des données récentes révèlent que celle-ci est persistante chez environ 15% des
enfants qui en sont touchés durant l'enfance, posant ainsi un risque à leur santé. La
présente étude examine 26 enfants avec ALV et 12 enfants contrôles recrutés au CHU
Sainte-Justine durant l’hiver 2011-2012. L'objectif étant de comparer la densité
minérale osseuse (DMO) et les niveaux sériques de 25(OH)D d'enfants prépubères
avec ALV non résolue à un groupe contrôle d'enfants avec autres allergies
alimentaires, en plus d'évaluer les apports en calcium et en vitamine D ainsi que
l'adhérence à la supplémentation chez cette population.
La DMO lombaire (L2-L4) ne diffère pas significativement entre les groupes.
Cependant, une faible densité osseuse, caractérisée par un score-Z entre -1,0 et -2,0
pour l'âge et le sexe, est détectée chez plus de 30% des enfants avec ALV et plus de
16% du groupe contrôle, sans allergie au lait. Tel qu'attendu, les apports en calcium
sont significativement moins élevés chez les enfants avec ALV comparé au groupe
contrôle, avec près de 90% de tous nos participants ne rencontrant pas les besoins pour
l’âge en vitamine D. Plus de la moitié des enfants avec ALV présentent une
concentration de 25(OH)D inférieure à 75 nmol/L. Cependant, notre étude n'a décelé
aucune différence entre les niveaux sériques de 25(OH)D des enfants avec ALV
comparativement au groupe contrôle. Enfin, l'adhérence à la supplémentation est jugée
adéquate chez plus de 75% de notre groupe d'enfants avec ALV, soit ≧ 4 journées par
semaine, un facteur aussi associé à une meilleure atteinte de leurs apports nutritionnels
en calcium et en vitamine D. Enfin, ces résultats soulignent l'importance de suivre la
santé osseuse d'enfants avec ALV ainsi qu'avec allergies multiples, qui présentent un
risque de faible densité osseuse. L'intervention nutritionnelle devrait suivre l'adhérence
à la supplémentation chez les enfants avec ALV non résolue, afin d'optimiser les
apports nutritionnels insuffisants en calcium et en vitamine D / Cow's milk allergy (CMA) is the most frequent food allergy seen during childhood.
Though usually recognized as transient, recent data suggest that the evolution of CMA
has changed over time, having become more persistent and therefore, more capable of
jeopardizing child growth and development. The following study included 26 children
with proven CMA and 12 controls, recruited at Sainte-Justine hospital, during the
winter of 2011-2012. The aim of this study was to compare bone density and vitamin D
status (25(OH)D) in prepubertal children with CMA to a control group of children
without milk allergy and to document calcium and vitamin D intake as well as the
adherence to supplementation in this population.
Bone mineral density did not differ significantly between groups. However, low bone
mass, as defined by a z score between -1,0 and -2,0 for gender and age, was detected in
over 30% of cow's milk allergic children and in over 16% of allergic controls. Calcium
intake was significantly lower in children with CMA. Overall, nearly 90% of our study
population failed to meet daily recommended intakes for vitamin D, with over 50% of
cow's milk allergic children presenting vitamin D status below 75 nmol/L. No
difference was detected regarding vitamin D status between groups. Finally, the
majority of children with CMA presented a good adherence to calcium and vitamin D
supplementation, ≧ 4 days per week, a factor that was associated with a better overall
dietary intake of these nutrients. It is therefore important to follow bone health of
children with CMA as well as with multiple food allergies, as they present a risk for
low bone mass during a period of skeletal growth. Nutrition interventions should
monitor supplement adherence in children with CMA to optimize dietary intake of
calcium and vitamin D, which are presently insufficient.
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Modélisation mécaniste de la bioaccumulation de contaminants organiques (PCB et PFAS) chez les poissons dans le contexte du changement global : application aux juvéniles de sole commune de l’estuaire de la Gironde. / Modelling mechanistic bioaccumulation of organic contaminants (PCBs and PFASs) in fish in the context of global change : application to the Gironde estuary juvenile common soleMounier, Florence 28 March 2019 (has links)
Les estuaires sont des écosystèmes aquatiques particulièrement soumis au changement global et notamment à la pollution par de nombreux xénobiotiques pouvant présenter un risque écotoxicologique et sanitaire. En toxicologie environnementale et en évaluation des risques la bioaccumulation est un processus fondamental car elle contrôle les doses internes de toxiques potentiels. Or les flux de contamination et de décontamination des organismes dépendent de processus internes (e.g. nutrition, croissance) eux-mêmes dépendant des conditions environnementales (e.g. température, nourriture) qui peuvent être affectées par le changement global.Dans ce contexte, cette thèse se propose de décrire, dans un cadre de modélisation mécaniste, les processus de bioaccumulation de deux familles de polluants organiques persistants (POP) halogénés potentiellement toxiques et bioaccumulables, aux propriétés physico-chimiques contrastées : les polychlorobiphényles (PCB, composés historiques fortement lipophiles) et les substances perfluorées (PFAS, composés émergents amphiphiles). Ce travail se focalise sur l’estuaire de la Gironde dont la fonction de nourricerie est fondamentale pour de nombreuses espèces de poissons marins dont la sole commune (Solea solea), souvent utilisée comme indicatrice de la qualité des nourriceries côtières et estuariennes.Pour permettre de tenir compte des fluctuations des conditions environnementales sur la bioaccumulation, dans la première partie de ce travail, j’ai développé un modèle de toxicocinétique(TK) couplé avec un modèle mécaniste bioénergétique basé sur la théorie DEB (Dynamic Energy Budget). Ce modèle DEB a été paramétré pour la sole commune et calibré pour chaque sexe (package DEB tool). Il permet de prédire les principales évolutions des fonctions physiologiques d’intérêt en bioaccumulation (ingestion, croissance, reproduction...), tout au long du cycle de vie d’un individu, en fonction de conditions environnementales dynamiques. Le modèle TK développé a été complexifié par l’ajout d’un flux d’élimination de contaminants, non considéré dans les précédents modèles DEB-TK.La calibration des paramètres toxicocinétiques (TK) du modèle, pour 4 congénères de PCB, est basée sur une méthode innovante de prise en compte de la variabilité individuelle d’ingestion, appliquée à une expérimentation de contamination de juvéniles de sole via leur nourriture. Ce travail a montré que même en tenant compte de l’ingestion de chaque poisson, l’assimilation efficace de contaminant était très variable et corrélée aux taux de lipides des individus. Dans une seconde partie, ce modèle a été appliqué aux conditions in situ de l’estuaire de la Gironde. Il a permis de mettre en évidence la forte influence de la composition du régime alimentaire sur la variabilité de l’âge à la maturité sexuelle et de la contamination des soles pour les deux familles de contaminant étudiées. La confrontation des prédictions du modèle aux mesures de contaminants dans les juvéniles de sole de l’estuaire a permis de calibrer les paramètres TK du composé majeur de chaque famille dans l’environnement (CB153 et PFOS). Cette calibration a conduit à deux constats dans le cadre de l’évaluation du risque : (1) un manque de connaissances pour extrapoler les calibrations de paramètres TK en conditions contrôlées vers les conditions naturelles ; (2) la différence d’erreur d’évaluation du risque liée à l’utilisation des mêmes paramètres TK «les plus pessimistes » quels que soient les composés. Enfin, des scenarios prospectifs simples ont été développés pour illustrer ces résultats et les possibles applications du modèle développé.In fine, ces prédictions de la contamination, de la croissance et du développement des soles pourront être reliées, lors de travaux ultérieurs, à des effets potentiels sur les fonctions physiologiques de la sole (modèles DEBtox), et aux conséquences sur la dynamique des populations de soles (e.g.modèles matriciels de population). / Estuarine ecosystems are particularly impacted by global change and, specifically, bychemical pollution from numerous xenobiotics that may be associated to ecotoxicological and health risks. In environmental toxicology and risk assessment, bioaccumulation is a fundamental process as it controls the internal doses of potential toxicants in organisms. However, the contamination and decontamination flows depend on internal processes thatare themselves dependent on environmental conditions (e.g. temperature, food) and thus on the other variables of global change.In this context, this manuscript aims at describing, within a mechanistic modelling framework, the bioaccumulation processes of two families of potentially toxic and bioaccumulable halogenated persistent organic pollutants (POPs) with contrasting physicochemical properties: the polychlorinated biphenyls (PCBs, highly lipophilic historical compounds) and the perfluorinated substances (PFAS, amphiphilic emerging compounds).This work focuses on the Gironde estuary whose nursery function is fundamental for many species of marine fish including the common sole (Solea solea), often used as an indicator of the quality of coastal and estuarine bursary grounds. In order to account for the influence of environmental conditions on bioaccumulation, the first part of this work consisted in developing a toxicokinetic model (TK) coupled with a mechanistic bioenergetic model based on the theory DEB (Dynamic Energy Budget). This DEBmodel has been parameterized for common sole and calibrated for each sex (packageDEBtool). It allows predicting the main evolution of the physiological functions of interest forbioaccumulation (ingestion, growth, reproduction...) throughout the life cycle of an individualaccounting for dynamic environmental conditions. The developed TK model was first calibrated for some PCBs, under controlled conditions, using an innovative method to take into account individual ingestion variability. This work showed that even if the individual ingestion of each fish is accounted for, the effective assimilation of contaminant is very variable and correlated with the lipid levels of the individuals. The application of the model tothe in situ conditions of the Gironde estuary led to identify that, whatever the contaminant family, the composition of the soles diet had a strong influence on the variability of soles contamination and age at sexual maturity. The comparison of model predictions with measurements made in juveniles of the estuary allowed calibrating the TK parameters values for the major compound of each family in the environment (CB153 and PFOS). This calibration led to two observations in the context of a risk assessment: (1) a lack of knowledge to extrapolate calibrations of TK parameters under controlled conditions to natural conditions;(2) the difference in risk assessment error related to the use of the same "worst case" TK parameters regardless of the compounds. Lastly, simple prospective scenarios have beendeveloped to illustrate these results and the possible applications of the model developed.Ultimately, these predictions of soles contamination, growth and development may be related in future work to potential effects on the physiological functions of sole (DEBtox models), and to consequences on soles population dynamics (e.g. matrix population models).
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Investigação da luminescência persistente dos materiais Lu2O3:TR3+,M (TR,M: Pr,HfIV; Eu, Ca2+ ou Tb,Ca2+) preparados pelo método de estado-sólido assistido por micro-ondas / Investigation of persistent luminescence of materials Lu2O3:TR3+,M (TR,M: PrHfIV; Eu, Ca2+ or Tb,Ca2+) prepared by the method of microwave assisted solid-statePedroso, Cássio Cardoso Santos 24 March 2017 (has links)
A luminescência persistente é um fenômeno em que o material emite radiação de segundos a várias horas após cessada a irradiação (luz, radiação UV, feixe de elétrons, etc.). No entanto, os mecanismos que geram o fenômeno da luminescência persistente ainda não são totalmente estabelecidos. Neste trabalho os materiais Lu2O3:TR3+,M (TR,M: Pr,HfIV; Eu, Ca2+ ou Tb,Ca2+) foram preparados pelo método de estado-sólido assistido por micro-ondas (MASS) e comparados com aqueles sintetizados pelo método cerâmico. As vantagens do método MASS incluem curto tempo de processamento, aquecimento dielétrico seletivo, baixo consumo de energia e uso de equipamentos de baixo custo (forno micro-ondas doméstico), muitas vezes produzindo produtos de alta pureza e alto rendimento. Os materiais foram caracterizados pelas técnicas de espectroscopia de absorção na região do infravermelho (IR), espectroscopia Raman, difração de raios X método do pó (DRX), microscopia eletrônica de varredura (MEV), X-ray absorption near edge structure (XANES), Extended X-ray absorption fine structure (EXAFS), X-ray Excited Optical Luminescence (XEOL), espectroscopia de fotoluminescência na região do UV-Visível, espectroscopia de fotoluminescência na região do UV-UV vácuo e termoluminescência (TL). Os fósforos Lu2O3:TR3+,M (TR,M: Pr,HfIV; Eu, Ca2+ ou Tb,Ca2+) foram preparados em um curto período de tempo (22-26 min) pelo método MASS utilizando forno micro-ondas doméstico, carvão ativado como susceptor, fluxos (H3BO3 ou Na2CO3) e sem a aplicação de gases. Todos materiais preparados com fluxo de H3BO3 exibem impurezas de LuBO3 que foram quantificadas por refinamento Rietveld. Os fluxos e os dopantes não alteraram consideravelmente a estrutura cristalina da matriz C-Lu2O3. As micrografias MEV sugerem que o fluxo de Na2CO3 e os precursores nitratos geram partículas de Lu2O3 com tamanho menor devido a evolução de gases provenientes da decomposição destes compostos. Por outro lado, quando é usado óxidos como precursores os materiais apresentam maiores tamanhos de partícula e na presença de H3BO3 leva a maior agregação. Os dados de XANES indicam que houve completa redução do íon TbIV → Tb3+ e parcial do PrIV → Pr3+, devido ao uso de carvão ativado que gera CO(g) durante o tratamento térmico. Os espectros da luminescência persistente indicam emissões nas regiões do vermelho/NIR, vermelho alaranjado e verde atribuídas as transições 4fN → 4fN características dos íons Pr3+, Eu3+ e Tb3+, respectivamente. As diferenças entre os espectros registrados sob excitação UV e após cessada a irradiação podem ser explicadas pela emissão da luminescência persistente predominante dos íons TR3+ no sítio S6 do que no C2. Além disso, a co-dopagem aliovalente com os íons HfIV e Ca2+ aumentam a intensidade e duração da luminescência persistente. Isto ocorre através da geração de armadilhas provenientes dos dois co-dopantes nos sítios de Lu3+ e por defeitos produzidos na compensação de carga. Os materiais fotônicos preparados pelo método MASS com fluxo de H3BO3 apresentam maior intensidade e duração da luminescência persistente comparados aos preparados pelo método cerâmico ou sem a presença de H3BO3. Os mecanismos da luminescência persistente foram desenvolvidos através de princípios similares baseados nos dados experimentais da energia do band gap, posição dos níveis de energia dos íons TR3+/2+ na matriz e energia das armadilhas. Isto confirma a solidez da interpretação dos dados experimentais dos materiais Lu2O3:TR3+,M exibindo luminescência persistentes e encoraja a expansão de modelos similares para outros materiais apresentando esse fenômeno. Os fósforos Lu2O3:Pr3+,HfIV,Lu2O3:Eu3+(,Ca2+) e Lu2O3:Tb3+,Ca2+) apresentaram sintonização de cores de emissão tanto para o fenômeno da fotoluminescência como da luminescência persistente, podendo atuar como bons candidatos nas aplicações de bioimageamento ou sensibilizadores de células solares. / Persistent luminescence is a phenomenon where the material emits radiation from seconds to several hours after cessation of irradiation (light, UV radiation, electron beam, etc.). The persistent luminescence mechanisms are not entirely established, however. In this work, the materials Lu2O3:TR3+,M (TR,M: PrHfIV; Eu, Ca2+ or Tb,Ca2+) were prepared by MASS method as well as compared to these materials synthetized by ceramic method. The advantages of MASS method include short processing time, selective dielectric heating, low energy consumption and use of inexpensive equipment (domestic microwave oven), often affording high-purity and high-yield products. The materials were characterized by Infrared absorption spectroscopy (IR), Raman spectroscopy, X-ray powder diffraction (XPD), Scanning electron microscopy (SEM), X-ray absorption near edge structure (XANES), Extended X-ray absorption fine structure (EXAFS), X-ray excited optical luminescence (XEOL), photoluminescence spectroscopy in the UV-Visible range, photoluminescence spectroscopy in the UV-UV vacuum region and thermoluminescence (TL). The phosphorsLu2O3:TR3+,M (TR,M: Pr,HfIV; Eu, Ca2+ or Tb,Ca2+) were rapidly (22-26 min) and successfully prepared by MASS method using a domestic microwave oven, carbon as susceptor, fluxes (H3BO3 or Na2CO3) and without special gases application. All materials prepared with H3BO3 flux exhibit LuBO3 impurities that were quantified by Rietveld refinement. The flux and dopants does not considerably affect the crystalline structure of the C-Lu2O3 host matrix. Scanning electron micrographs suggest that Na2CO3 flux and nitrates precursors produce Lu2O3 particles of small size due to the gases evolution from the decomposition of these compounds. On the other hand, the materials prepared from oxides precursors have particles of large size and H3BO3 flux induces particle xi aggregation. The carbon used as the susceptor generates CO gas, leading to complete reduction of TbIV to Tb3+ and partial conversion of PrIV to Pr3+ present in the Tb4O7 and Pr6O11 precursors, as indicated by XANES. Persistent luminescence spectra of the materials show emission in the red/NIR, reddish orange and green ranges assigned to the 4fN → 4fN transitions characteristics of Pr3+, Eu3+ and Tb3+ ions, respectively. Differences between the spectra recorded under UV excitation and after ceased the irradiation can be explained by the predominant persistent luminescence emission of TR3+ ion in the S6 site rather than TR3+ in the C2 site. In addition, inclusion of HfIV and Ca2+ codopants in the Lu2O3 host increases the emission intensity and duration of persistent luminescence due to generation of traps caused by charge compensation in the lattice as well as these metal ions in the Lu3+ sites. The photonic materials prepared by MASS method with H3BO3 flux show higher persistent luminescence performance than those prepared by the ceramic method or MASS without flux. The persistent luminescence mechanisms were developed through similar principles based on experimental data of band gap energy, energy level positions of TR3+/2+ ions in the host and traps energy. This similarity confirms the consistency of the interpretation of experimental data for the Lu2O3:TR3+,M materials and encourages the expansion of similar models for other persistent luminescence materials. Color tuning of persistent luminescence in Lu2O3:TR3+,M (TR,M: Pr,HfIV; Eu,Ca2+ or Tb,Ca2+) provides potential applications in bioimaging as well as in solar cell sensitizers.
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