Este trabalho apresenta a síntese e os estudos foto e eletroluminescentes dos complexos de β-dicetonatos (dibenzoilmetanato -DBM) de terras raras trivalentes (TR=Eu3+, Sm3+ e Gd3+) hidratados e contendo ligantes sulfóxidos (L= dibenzilsulfóxido - DBSO, dimetisulfóxido - DMSO, difenilsulfóxido - DPSO e p-toluilsulfóxido - PTSO). Os complexos obtidos foram caracterizados através das seguintes técnicas: i) análise elementar de carbono e hidrogênio; ii) análise dos íons TR3+ por titulação complexométrica; iii) difração de Raios X (método do pó); iv) análise térmica; v) espectroscopia vibracional de absorção no infravermelho (IV); e vi) microscopia eletrônica de varredura (MEV). As curvas TG/DTG dos complexos [TR(DBM)3H2O] e [TR(DBM)3(L)2] apresentam as etapas de decomposição térmica bem definidas e indicam que os complexos com ligantes sulfóxidos apresentam maior estabilidade térmica que os hidratados. Os espectros de absorção na região do IV evidenciam que a coordenação dos ligantes orgânicos (DBM e sulfóxidos) ao íon TR3+ ocorre através dos átomos de oxigênio. As fotomicrografias dos filmes indicam que as técnicas de deposição de filmes a vácuo e em solução podem fornecer filmes de boa qualidade. Os difratogramas de Raios X permitem o agrupamento dos complexos [TR(DBM)3(L)2] em uma mesma série isomórfica. Os espectros de emissão exibem desdobramentos das transições 5D0→7FJ (J=O-4) para os complexos de Eu3+ e 4G5/2→ 6HJ (J=5/2-11/2) para o Sm3+, que obedecem à regra de seleção 2J+1 e J+½, respectivamente. Os altos valores de parâmetros de intensidade Ω2 dos complexos de Eu3+ indicam que o íon TR encontra-se em um ambiente químico altamente polarizável. As curvas de decaimento dos níveis emissores 5D0 (Eu3+) e 4G5/2 (Sm3+) apresentam comportamento mono-exponencial para os complexos indicando a inexistência de outro processo de depopulação. Os valores de tempos de vida (τ) do nível emissor 5D0 dos Eu3+ complexos com ligantes sulfóxidos são maiores do que o complexo hidratado. Os complexos contendo ligantes sutfóxidos apresentam valores de eficiência quântica de emissão (η) e rendimento quântico experimental (q) superiores aos complexos hidratados devido os osciladores OH. Os espectros de emissão do [Eu(DBM)3(PTSO)2] em soluções (etanol ou acetona) e em filmes apresentam perfis similares ao complexo no estado sólido. Tais resultados indicam que os dispositivos podem ser confeccionados através das técnicas em solução (spin coating, dip coating, \"silk screening e ink jetting). Os espectros de fosforescência dos complexos de Gd3+ apresentam as bandas referentes aos estados tripletos (T) do DBM (~486 nm); as quais estão ausentes nos espectros de emissão dos complexos de Eu3+ e Sm3+, indicando uma eficiente transferência de energia do estado T do ligante para os níveis emissores 5D0 do íon Eu3+ e 4G5/2 do íon Sm3+. O complexo [Eu(DBM)3(PTSO)2] foi utilizado como camada emissora de luz vermelha na confecção dos dispositivos eletroluminescentes (EL); os quais foram confeccionados através da técnica de deposição física a vapor e apresentam as seguintes estruturas: (1) ITO / MTCD / [Eu(DBM)3(PTSO)2] / Alq3 / AI; (2) ITO / NPB / [Eu(DBM)3(PTSO)2] / Alq3 / Al; e (3) ITO / NPB / [Eu(DBM)3(PTSO)2] / Al. O filme depositado de MTCD= 1-(3-metilfenil)-1,2,3,4-tetrahidroquinolina-6-carboxialdeído-1,1-difenilhidrazona e NPB= N, N\'-bis(1-naftil) - N, N\'- difenil - 1,1\' - bifenil - 4, 4\'- diamina, atuam como transportadores molecuares de lacunas (buracos). O composto Alq3 [tris(8-quinolinonato)alumínio(III)] atua como transportador de elétrons. Deve-se ressaltar que o [Eu(DBM)3(PTSO)2] também apresentam propriedades de transportadores de elétrons, o que tende a reduzir os custos de produção dos dispositivos EL orgânicos. A última camada do dispositivo eletroluminescente corresponde ao alumínio, o qual atua como catodo e refletor. Os espectros eletroluminescentes dos dispositivos exibem emissões características das transições 5D0→ 7FJ oriundas do íon Eu3+. A caracterização elétrica dos dispositivos indica que o dispositivo bi-camada apresenta maior eficiência do que o tri-camada. As coordenadas CIE (Commission Internationale de l\'Eclairage) dos dispositivos EL apresentam contribuições da emissão do NPB (400-600 nm) e da transição 5D1→ 7F1 do íon . Este problema pode ser solucionado com a alteração da arquitetura dos dispositivos (NPB, MTCD, TDP e Alq3). / This work presents the synthesis and photo and electroluminescent study of rare earth (RE3+= Eu3+, Gd3+ and Sm3+) β-diketonate (dibenzoylmethane - DBM) complexes with hydrated and sulfoxide ligands (L= benzyl sulfoxide -DBSO, methyl sulfoxide - DMSO, phenyl sulfoxide - DPSO and p-tolylsulfoxide - PTSO). The complexes were characterized by the following techniques: i) elemental analysis of carbon and hydrogen; ii) analysis of RE3+ by complexometric titration; iii) X Rays diffraction patterns; iv) thermal anaiysis; v) IR spectroscopy and vi) scanning electron microscope (SEM). The TG/DTG curves of [RE(DBM)3H2O] and [RE(DBM)3(L)2] complexes present stages of thermal decomposition well defined for the complexes and indicate higher thermal stability when compared with hydrated complex. The IR spectral data indicate that the coordination of organic ligands (DBM and sulfoxides) to RE3+ ions occur through the oxygen atoms. The photomicrographs obtained from films indicate which vacuum and solution techniques can give films with good quality. The X Rays diffraction patterns suggest that the [RE(DBM)3(L)2] complexes are in the same isomorfic series. The emission spectra of the complexes exhibit the 5D0→7FJ transitions (J=0-4) from the Eu3+ ion and 4G5/2→6HJ (J=5/2-11/2) from the Sm3+ ion, which follow the selection rule 2J+1 and J+½, respectively. The high values of the Ω2 intensity parameters of Eu3+ complexes indicate that the RE ion is in a highly polarizable chemical environment. The luminescence decay curves show a mono- exponential behavior for the complexes indicating the inexistence of other channel depopulation. The lifetimes (τ) values of the emitting level from RE3+ -complexes with sulfoxide ligands are higher than hydrated complexes. The complexes containing sulfoxide ligands present higher values of emission quanturn efficiency (η) and quantum yield (q) than hydrated complexes due OH oscillators. The emission spectra of [Eu(DBM)3(PTSO)2] in solutions and fiIms show the similar spectrum profles compared with that in solid state. These results indicate device construction could be realized from solution techniques as spin coating, dip coating, silk screening and ink jetting. The phosphorescence spectra of the Gd3+-complexes show broaden bands arising from the triplet states (T) of the DBM-(~486nm); which are absent in the emission spectra for the RE3+ complexes indicating an efficient energy transfer from the (T) state of the ligand to the emitting level 5D0 and 4G5/2 of Eu3+ and Sm3+ ions, respecfively. The complex [Eu(DBM)3(PTSO)2] was utilized as emitting layer of red light in construction of electroluminescent (EL) devices. These devices were constructed through Physical Vapour Deposition (PVD) technique and they present the following structures: (1) ITO / MTCD / [Eu(DBM)3(PTSO)2] / Alq3 / AI; (2) ITO / NPB / [Eu(DBM)3(PTSO)2] / Alq3 / Al; e (3) ITO / NPB / [Eu(DBM)3(PTSO)2] / Al The MTCD =1-( 3-methylphenyl)-1,2,3,4-tetrahydroquinoline-6-carboxyaldehyde-1,1-diphenyilhydrazone; and NPB =N,N-diphenyl-N,N-bis(1-naphthyl)-1,1-biphenyl-4,4\'-diamine, act as hole transporting layer (HTL). The Alq3, (8-hydroxyquinoline aluminum) thin film act as electron transporting layer (ETL). The [Eu(DBM)3(PTSO)2] complex shows electron transport properties; which tend to reduce the cost of production of this type of organic electroluminescent (EL) devices. The last layer is the Al (aluminum) thin íilm, which act as cathode and reflector of emitted light. The CIE (Commission Internationale de l\'Eclairage) coordinates of the EL devices show contributions of emission from the NPB (400-600 nm) and 5D1→ 7F1 transition from the Eu3+ ion. This problem can be solved with alteration h the architecture of the device (NPB, MTCD, TPD and Alq3.

Orientador: Ítalo Odone Mazali / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-22T20:07:38Z (GMT). No. of bitstreams: 1 Oliveira_CristineSantosde_M.pdf: 3527061 bytes, checksum: 7dfe90cc79337811bc7955e8a1531586 (MD5) Previous issue date: 2013 / Resumo: O trabalho consistiu na síntese de sistemas nanoestruturados de ZnO contendo Eu em sílica mesoporosa, o vidro poroso Vycor (PVG), utilizando o método de ciclos de impregnação-decomposição (CIDs). Sistemas de nanopartículas puras de ZnO, na forma PVG/10ZnO mostraram que o ZnO apresentou-se predominantemente na forma de sítios de ZnO monodispersos com absorção em 245-250 nm e na forma de nanopartículas, com tamanho médio em torno de 4,5 nm, para as quais inicialmente não se observou uma absorção característica. Através de espectroscopia de luminescência observou-se transferência de energia do ZnO monodisperso para a matriz, porém nenhuma emissão no visível característica de defeitos. Para o sistema PVG/10Eu observou-se transições f-f características nos espectros de emissão e excitação, e a transferência de carga O¿¿Eu. Os sistemas seguintes sintetizados na forma PVG/ZnO@ZnO/M@ZnO, com M = Eu, Al, Sr, Pr e Yb visaram o estudo do sistema principal PVG/ZnO@ZnO/Eu@ZnO, o qual apresentou emissões do Eu relativamente mais intensas do que no sistema PVG/10Eu além de apresentar o favorecimento do crescimento do ZnO sob a forma de nanopartículas, crescendo sobre os aglomerados de dopante. Nessas condições, surge a banda proibida do ZnO em torno de 360 nm, cuja borda é deslocada para menores energias com o número de CIDs, em acordo com uma equação da literatura, indicando um regime de confinamento quântico. Esta banda é observada na luminescência e também transfere energia para a matriz, ainda não sendo observadas emissões de defeitos do ZnO. Estudos com Sr e Al não confirmaram a formação de defeito do tipo Zni decorrente da inserção do íon Eu na rede do óxido. Os espectros de excitação para os sistemas de ZnO contendo Eu não foram conclusivos quanto à transferência de energia devido à presença de bandas do Eu, e num sistema similar substituindo-se por Yb não foi observada esta transferência. Medidas de tempo de vida mostraram um aumento da estabilidade do Eu no sistema com a presença prévia do ZnO, e também sob seu recobrimento. Através das emissões excitônicas do ZnO observou-se o efeito de confinamento quântico também na luminescência, o qual se deu de forma similar ao observado para a análise por absorção no UV-Vis / Abstract: The work consisted in the synthesis of nanostructured systems of ZnO containing Eu loaded in a mesoporous silica, the porous Vycor glass (PVG), using the impregnation-decomposition cycles method (IDCs). Pure ZnO nanoparticles systems synthesized in the form PVG/10ZnO have shown that ZnO presents itself predominantly as monodisperse ZnO sites with absorption at 245-250 nm, and nanoparticles, with mean size around 4,5 nm, for which initially no characteristic absorption had been observed. Through luminescence spectroscopy an energy transfer from monodisperse ZnO to the matrix was observed, but no defect-related emissions. For the PVG/10Eu system Eu characteristic f-f transitions were observed in both emission and excitation spectra, as well as the O¿¿Eu charge transfer. The following systems synthesized in a PVG/ZnO@ZnO/M@ZnO pattern, with M = Eu, Al, Sr, Pr e Yb sought the study of the main system PVG/ZnO@ZnO/Eu@ZnO, which presented Eu emissions relatively more intense than the PVG/10Eu system, also showing favoring growth of ZnO under the form of nanoparticles, which now grow over dopant clusters. Under such condition the ZnO band gap is now observed in UV-Vis absorption analysis, with peaks around 360 nm, whose edge is displaced towards lower energies with increasing number of IDCs, also in agreement with a theoretical equation from the literature, pointing to a condition of quantum confinement. This band is observed in luminescence, and also transfers energy to the matrix, and yet no defect-related emissions are observed for ZnO. Studies with Sr and Al did not confirm the formation of a Zni defect due to the insertion of Eu ions into the oxidefs structure. Excitation spectra for Eu-containing ZnO systems were not conclusive as to the existence of an energy transfer due to the presence of Eu bands in the same range, and in the similar system exchanging Eu3+ for Yb3+ such transfer was not observed. Lifetime measurements have shown an increase in Eu stability within the system with ZnO presence previous to its insertion, or after its coating layer(s). Quantum confinement effect was also observed for the ZnO excitonic emissions in luminescence, showing a similar behavior to that obtained thru UV-Vis absorption analysis / Mestrado / Quimica Inorganica / Mestre em Química

Abstract New rapid methods for sensitive and specific detection of pneumococci are not only needed to improve the diagnosis of pneumococcal disease but are also essential for vaccine and carriage studies. The purpose of this study was to develop sensitive PCR methods for the detection and quantification of S. pneumoniae and to study the applicability of these methods to detecting pneumococci in clinical samples. A previously described PCR method was first developed further by introducing a Europium-labelled hybridisation probe for the detection of amplification products. The hybridisation method was easy to use and improved the specificity of the PCR assay. The developed PCR assay was established as a sensitive method for detecting pneumococcal DNA when the presence of pneumococcal DNA in over 2500 middle ear fluid (MEF) samples of children with acute otitis media (AOM) was studied by using the method. Pneumococcal findings increased by 76% when using PCR detection in addition to culture, compared to using culture alone. However, the PCR-positive, culture-negative AOM events represented a less severe type of disease compared to the culture-positive events. A positive PCR finding seems to indicate the presence of viable, although often non-culturable pneumococci within the middle ear cleft. To be able to rapidly detect and quantify the initial numbers of pneumococcal genome copies in clinical samples, a real-time PCR method for the detection and quantification of pneumococcal DNA was developed. In real-time PCR, amplification and detection of amplification products occur simultaneously, which makes it possible to monitor the phase of the reaction at a particular stage or continuously. The method developed here was applied to the analysis of MEF samples and to investigating the nasopharyngeal carriage of pneumococcus. The sensitivities of bacterial culture and real-time PCR in detecting pneumococci were also compared. The real-time PCR assay was found to be rapid and sensitive and to provide information about the differences between the numbers of bacteria in samples. However, the quantitative results were shown to be dependent on the DNA extraction method applied. The real-time PCR method developed appears to be a good aid in research where an accurate and sensitive pneumococcal diagnosis is needed.

No description available.

Les cristaux dopés par des ions de terre rare (TR) apparaissent prometteurs pour des applications dans le traitement quantique de l'information. Parmi ces matériaux, les cristaux massifs d'Eu3+:Y2O3 présentent un long temps de cohérence optique (T2), un paramètre fondamental pour les technologies quantiques. Ce travail de thèse porte sur l'étude de ce système à l'échelle nanométrique, ce qui pourrait permettre de développer des systèmes hybrides dans lesquels les TR sont couplées à d'autres systèmes quantiques. Des nanocristaux de différentes tailles ont été élaborés par précipitation homogène. La largeur optique inhomogène diminue avec des recuits à haute température et peut atteindre les valeurs mesurées dans des cristaux massifs. Une corrélation quasi-linéaire avec les largeurs de raie Raman a aussi été observée. Les temps de vie de population sont plus longs que dans les échantillons massifs et peuvent être modélisés par un indice de réfraction effectif. Les T2 optiques ont ensuite été déterminés par écho de photon et creusement de trou spectral. Nous avons mesuré un temps de cohérence de 7.1 µs à 1.7 K dans un échantillon dopé à 0.5 % en Eu3+, la valeur la plus élevée observée pour un nanocristal. Une étude en température et de la diffusion spectrale indique que le déphasage est dominé par des fluctuations de la structure et des basculements de spins. / Rare earth (RE) doped crystals are promising materials for quantum information processing (QIP). In particular, Eu3+:Y2O3 bulk crystals present long optical coherent lifetimes (T2), a fundamental parameter for QIP. In this thesis, we investigated this system at the nanoscale, which could be used to build hybrid devices where RE are coupled to other quantum systems. This work focuses on the development of Eu3+: Y2O3 particles with sub-wavelength size and on the static and dynamical contributions to Eu3+ optical linewidth. Systems with different particle and crystallite sizes were prepared using homogeneous precipitation. Optical inhomogeneous linewidths were found to decrease with high temperature annealing and reached values close to those of bulk crystals, showing that low defect concentrations can be obtained. A quasi-linear correlation with Raman linewidths was also observed. T1 population decays were measured by fluorescence and found longer than in the bulk, in good agreement with a model based on an effective refractive index model. Optical T2 were investigated by photon echo (PE) and holeburning techniques. We observed a coherence lifetime of 7.1 µs at 1.7 K in a 0.5 % Eu3+ doped sample, the highest value reported for any nanocrystal. Temperature dependence and spectral diffusion studies indicate that structure fluctuations and spin flips dominate dephasing.

No description available.

Die sichere Entsorgung hochradioaktiver Abfälle stellt eine wichtige wissenschaftli-che und gesellschaftliche Herausforderung dar. Tongesteine sind potentielle Wirts-gesteine für die Endlagerung dieser Abfälle in einem geologischen Tiefenlager. Ben-tonite sollen dabei als Verfüllmaterial nicht nur für ein Endlager in Tonformationen, sondern auch in kristallinem Gestein dienen. Für eine langfristige Sicherheitsbewer-tung müssen verschiedene Aspekte berücksichtigt werden. Neben geologischen, ge-ochemischen und geophysikalischen Gesichtspunkten spielen auch natürlich vor-kommende Mikroorganismen eine entscheidende Rolle in der Umgebung eines sol-chen Endlagers. Gelangt in einem Worst-Case-Szenario Wasser in das Endlager, können diese mit den freigesetzten Radionukliden wechselwirken und beispielswei-se die chemische Speziation oder den Oxidationszustand verändern. In dieser Arbeit wurden die Wechselwirkungen des anaeroben, sulfatreduzierenden Bakteriums Desulfosporosinus hippei DSM 8344T, einem Vertreter der Gattung Desul-fosporosinus, die in Tongestein und Bentonit vorkommt, mit Uran(VI) und Europi-um(III) mit Hilfe verschiedener mikroskopischer, spektroskopischer und molekular-biologischer Methoden untersucht. Die Ergebnisse lieferten einen umfassenden Einblick in die ablaufenden Wechselwirkungsprozesse und zeigten deutliche Unter-schiede zwischen den untersuchten Elementen auf. Im Zuge dessen wurde ein be-sonderes Augenmerk auf die Untersuchung der Reduktion von Uran(VI) durch D. hippei DSM 8344T gelegt. Für dieses Element konnte eine Immobilisierung in einem gekoppelten Assoziations-Reduktionsmechanismus nachgewiesen werden. Im Ge-gensatz dazu wechselwirkte nur ein geringer Anteil des gelösten Europium(III) mit den Zellen des anaeroben Mikroorganismus, wobei eine teilweise Biopräzipitation von Europiumphosphat beobachtet werden konnte. Die Wechselwirkung des Mikroorganismus mit Uran(VI) wurde zunächst in einem Bikarbonat-gepufferten System untersucht, wobei keine Abnahme der Urankon-zentrationen nachgewiesen werden konnte und damit wahrscheinlich auch keine Reduktion von Uran(VI) in den Überständen erfolgte. Zusätzlich wurden die Expe-rimente in synthetischer Opalinustonporenlösung durchgeführt. Die Untersuchun-gen mit zwei verschiedenen Uran(VI)-Ausgangskonzentrationen (100 µM und 500 µM) zeigten dabei in beiden Fällen eine fast vollständige Entfernung des Urans aus den Überständen. Um genauere Informationen über die Uran(VI)-Speziation in den Überständen zu erhalten, wurden thermodynamische Berechnungen der auftretenden Komplexe sowohl in Bikarbonat-Puffer, als auch in synthetischer Opalinustonporenlösung durchgeführt. Ergänzend dazu wurden die Überstände der Versuche in der Poren-lösung lumineszenzspektroskopisch untersucht. Die thermodynamische Modellie-rung zeigte bei dem pH-Wert des Bikarbonat-Puffersystems (pH 6,8) die Dominanz des 1:3-Uranyl(VI)-Carbonat-Komplexes, wohingegen im Porenwasser (pH 5,5) ein Uranyl(VI)-Laktat-Komplex die vorrangige Spezies darstellte. Die Anwesenheit eines zusätzlichen Carbonat-Komplexes spielte in diesem Fall nur eine untergeordnete Rolle. Die Berechnungen konnten mit Hilfe der Lumineszenzspektroskopie bestätigt werden. Sowohl der dominante Laktat-Komplex, als auch ein geringer Anteil eines Uranyl(VI)-Carbonat-Komplexes konnten im Opalinustonporenwasser verifiziert werden. Die Speziesverteilung zeigte, dass nur der Anteil des Laktat-Komplexes mit steigenden Inkubationszeiten abnahm, wohingegen der Anteil des Carbonat-Komplexes konstant blieb. Dies bestätigte die Ergebnisse der Experimente in Bikar-bonat-Puffer und ließ Schlussfolgerungen dahingehend zu, dass der Carbonat-Komplex von den Zellen offenbar nicht reduziert werden konnte und dadurch die Bioreduktion von der Ausgangsspeziation des Uran(VI) abhängig ist. Fluoreszenzmikroskopische Aufnahmen wiesen einen Einfluss des Urans auf die Zellvitalität und die Biofilmbildung nach. Mit Hilfe der Transmissionselektronenmik-roskopie konnte die Assoziation von Uran vorrangig auf der Zelloberfläche gezeigt werden. Zudem bildeten die Zellen Membranvesikel als mögliche Abwehrreaktion aus, um eine Verkrustung der Zellen zu verhindern. Diese Beobachtungen deuten auf eine Immobilisierung des Urans durch Wechselwirkung mit den Zellen hin. Die Reduktion des Uran(VI) wurde mit Hilfe verschiedener spektroskopischer Me-thoden bestätigt. Dabei zeigten UV/Vis-Untersuchungen der aufgelösten Zellpellets zunächst einen steigenden Anteil an Uran(IV) mit fortschreitender Inkubationszeit. Eine vollständige Reduktion des Urans konnte hingegen nicht nachgewiesen wer-den. HERFD-XANES-Messungen bestätigten die Reduktion des Uran(VI) in den Zell-pellets. Darüber hinaus konnte die Anwesenheit von Uran(V) während des Redukti-onsprozesses beobachtet werden, wodurch ein Ein-Elektronen-Prozess als Redukti-onsmechanismus für diesen Mikroorganismus verifiziert werden konnte. Des Weite-ren handelte es sich dabei um den erstmaligen Nachweis von Uran(V) während der Bioreduktion von Uran(VI) durch sulfatreduzierende Mikroorganismen im Allge-meinen. Ergänzende EXAFS-Untersuchungen konnten die Struktur der Uran(IV)-Verbindung hingegen nicht abschließend aufklären. Mittels Proteomikuntersuchungen als systembiologische Methode konnten Hinweise auf verschiedene während der Uraninkubation stattfindender Prozesse, wie bspw. die Biofilmbildung, den Zellwandumbau und eine Hochregulierung verschiedener Proteine, die in anderen Mikroorganismen für die Reduktion von Uran und anderen Metallen verantwortlich sind, gefunden werden. Des Weiteren konnten auch ver-schiedene Enzyme die an einer Stressreaktion der Zellen beteiligt sind nachgewiesen werden. In den Experimenten mit Europium(III), welches häufig als nicht radioaktives Ana-logon für die dreiwertigen Actinide zum Einsatz kommt, zeigten die Zellen nur eine geringe Wechselwirkung mit dem Lanthanid. Der toxische Einfluss des Schwerme-talls war geringer als in den Untersuchungen mit Uran(VI). Transmissionselektro-nenmikroskopische Aufnahmen zeigten eine Biopräzipitation von Europium(III) mit Phosphaten auf der Zelloberfläche und dadurch eine teilweise Immobilisierung des Metalls. Die aquatische Speziation des Europium(III) zeigte eine vollständige Komplexierung mit Laktat in den Überständen. Dies könnte eine mögliche Erklärung der geringen Wechselwirkung mit den Zellen liefern aufgrund einer Abschirmung des Lanthanids gegenüber zellulären Liganden. In den Zellspektren, ließen sich drei unterschiedli-che Spezies voneinander unterscheiden, eine lose mit den Zellen assoziierte Spezies und zwei zellulär gebundene Komplexe wahrscheinlich mit Carboxyl- oder Phos-phatgruppen. Eine ortsaufgelöste Speziation war mit Hilfe einer Kopplung von kon-fokaler Mikroskopie und Laserspektroskopie möglich. Zusammenfassend liefert diese Arbeit neue Erkenntnisse über die Wechselwirkung sulfatreduzierender Mikroorganismen mit Uran(VI) und Europium(III) und trägt zu einem besseren Verständnis mikrobieller Reduktionsprozesse in der Umwelt bei. Die Immobilisierung von Uran durch eine teilweise Reduktion zu weniger löslichen Uran(IV)-Verbindungen, sowie eine verstärkte Biofilmbildung wirken sich positiv auf die Sicherheit eines Endlagers für hochradioaktive Abfälle in Tongestein aus. Es konnte allerdings auch gezeigt werden, dass stattfindende Wechselwirkungsprozes-se von der Ausgangsspeziation des Metalls abhängen, wodurch die Retention der Radionuklide möglicherweise eingeschränkt wird. Dadurch spielen die erhaltenen Ergebnisse nicht nur eine wichtige Rolle für ein umfassendes Sicherheitskonzept eines nuklearen Endlagers in Tongestein, sondern liefern auch neue Impulse für verschiedene Bioremediationsstrategien radioaktiv kontaminierter Umgebungen. / The safe disposal of high-level radioactive waste is a major scientific and societal challenge. Clay rocks are potential host rocks for the final disposal of the nuclear waste in a deep geological repository. Bentonites should serve as backfill material for a repository not only in clay formations, but also in crystalline rocks. Various aspects have to be considered for a long-term safety assessment. In addition to geological, geochemical and geophysical aspects, naturally occurring microorganisms in the en-vironment of such a repository play a decisive role. In the event of a worst-case sce-nario, if water enters the repository, these microorganisms can interact with the re-leased radionuclides and, for example, change the chemical speciation or oxidation state. In this work, the interactions of the anaerobic sulfate-reducing bacterium Desul-fosporosinus hippei DSM 8344T, a member of the genus Desulfosporosinus, which can be found in clay rock and bentonite, with uranium(VI) and europium(III) were in-vestigated using various microscopic, spectroscopic and molecular biological meth-ods. The results provided a comprehensive insight into the interaction processes and revealed significant differences between the investigated elements. Special attention was paid to the reduction of uranium(VI) by D. hippei DSM 8344T. For this element, an immobilization in a coupled association-reduction mechanism was demonstrated. In contrast, only a small fraction of the dissolved europium(III) interacted with the cells of the anaerobic microorganism, and a partial bioprecipitation of europium phosphate was observed. The interaction of the microorganism with uranium(VI) was first investigated in a bicarbonate-buffered system, where no decrease in uranium concentrations was observed, and thus probably no reduction of uranium(VI) occurs. In addition, ex-periments in synthetic Opalinus Clay pore solution were carried out. The investiga-tions with two different initial uranium(VI) concentrations (100 µM and 500 µM) showed an almost complete removal of uranium from the supernatants in both cas-es. Thermodynamic calculations of the complexes formed were performed in both, bi-carbonate buffer and synthetic Opalinus Clay pore water solution, to obtain more detailed information on uranium(VI) speciation in the supernatants. In addition, the supernatants of the pore water solution were analyzed by luminescence spectrosco-py. Thermodynamic modeling showed the dominance of the 1:3 uranyl(VI)-carbonate complex at the pH of the bicarbonate buffered system (pH 6.8), whereas in the pore water (pH 5.5) a uranyl(VI) lactate complex was the predominant spe-cies. The presence of an additional carbonate complex plays only a minor role in this case. The calculations were confirmed by luminescence spectroscopy. Both the dom-inant lactate complex and a small fraction of a uranyl(VI) carbonate complex could be detected in the Opalinus Clay pore water. The species distribution showed that only the proportion of the lactate complex decreased with increasing incubation times, while the proportion of the carbonate complex remained constant. This con-firmed the results of the experiments in bicarbonate buffer and led to the conclu-sion that the carbonate complex could not be reduced by the cells and therefore the bioreduction was dependent on the initial speciation of uranium(VI). Fluorescence microscopic images showed an influence of uranium on cell viability and biofilm formation. Transmission electron microscopy showed the association of uranium primarily on the cell surface. In addition, the cells formed membrane vesi-cles as a possible defense mechanism to prevent cell incrustation. These observa-tions indicated an immobilization of uranium by its interaction with the cells. The reduction of uranium(VI) was confirmed by various spectroscopic methods. UV/Vis studies of the dissolved cell pellets showed an increasing amount of urani-um(IV) with increasing incubation time. However, a complete reduction of uranium could not be detected. HERFD-XANES measurements verified the reduction of ura-nium(VI) in the cell pellets. In addition, the presence of uranium(V) was observed during the reduction process, confirming a one-electron process as the reduction mechanism for this microorganism. Furthermore, this was the first detection of ura-nium(V) during a bioreduction experiment of uranium(VI) by a sulfate-reducing microorganism in general. However, additional EXAFS studies could not conclusively elucidate the structure of the formed uranium(IV) compound. Using proteomics as a system biology method, evidence was found for various pro-cesses occurring during uranium incubation, such as biofilm formation, cell wall re-modeling, and up-regulation of various proteins responsible for the reduction of uranium and other metals in other microorganisms. In addition, several enzymes involved in a stress response of the cells were detected. In experiments with europium(III), which is often used as a non-radioactive analog of the trivalent actinides, the cells showed little interaction with the lanthanide. Compared to the studies with uranium(VI), the toxic influence of the heavy metal was less pronounced. Transmission electron microscopic images showed a bioprecip-itation of europium(III) with phosphates on the cell surface, resulting in partial im-mobilization of the metal. The aqueous speciation of europium(III) showed a complete complexation with lac-tate in the supernatants. This could be a possible explanation for the low interaction with the cells due to a shielding of the lanthanide from cellular ligands. In the cell spectra, three different species could be distinguished, one loosely associated with the cells and two cellularly bound complexes, probably with carboxyl or phosphate groups. A spatially resolved speciation could be detected by coupling confocal mi-croscopy and laser spectroscopy. To summarize, this work provides new insights into the interaction of sulfate-reducing microorganisms with uranium(VI) and europium(III) and contributes to a better understanding of microbial reduction processes in the environment. The im-mobilization of uranium by a partial reduction to less soluble uranium(IV) com-pounds, as well as the enhanced biofilm formation, have a positive effect on the safety of a repository for highly radioactive waste in clay rock. However, it has also been shown that the interaction processes that take place depend on the initial spe-ciation of the metal, which may limit the retention of radionuclides. Thus, the ob-tained results not only play an important role for a comprehensive safety concept of a repository for nuclear waste in clay rock, but also provide new impulses for differ-ent bioremediation strategies of radioactively contaminated environments.

Pu (III) is one of the key elements in the safety assessments of Canadian deep geological repository program (DGR). Sorption is a potential mechanism for retarding radionuclide transport from a DGR to the environment. In the current scenario, Pu (III) is considered to be a dominant radioactive element in the deep geological groundwater. Eu, considered to be a chemical analogue of Pu (III), its sorption behavior is now the target of our research. This thesis investigates the sorption properties of Eu on MX-80 under saline reducing conditions, and highly saline reducing conditions. The thermodynamic sorption modelling of Eu is also need to be applied. A surface sorption model is also developed by applying computer program for Eu (III) on MX-80 to investigate the sorption mechanisms of Eu (III) sorption. / Thesis / Master of Applied Science (MASc)

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