Microorganisms control many processes pertinent to the stability of radwaste inventories in nuclear storage and disposal facilities. Furthermore, numerous subsurface bacteria, such as Shewanella spp. have the ability to couple the oxidation of organic matter to the reduction of a range of metals, anions and radionuclides, thus providing the potential for the use of such versatile species in the bioremediation of radionuclide contaminated land. However, the organisms promoting these processes will likely be subject to significant radiation doses. Hence, the impact of acute doses of ionizing radiation on the physiological status of a key Fe(III)-reducing organism, Shewanella oneidensis, was assessed. FT-IR spectroscopy and MALDI-TOF-MS suggested that the metabolic response to radiation is underpinned by alterations to proteins and lipids. Multivariate statistical analysis indicated that the phenotypic response was somewhat predictable although dependent upon radiation dose and stage of recovery. In addition to the cellular environment, the impact of radiation on the extracellular environment was also assessed. Gamma radiation activated ferrihydrite and the usually recalcitrant hematite for reduction by S. oneidensis. TEM, SAED and Mössbauer spectroscopy revealed that this was a result of radiation induced changes to crystallinity. Despite these observations, environments exposed to radiation fluxes will be much more complex, with a range of electron acceptors, electron donors and a diverse microbial community. In addition, environmental dose rates will be much lower than those used in previous experiments. Sediment microcosms irradiated over a two month period at chronic dose rates exhibited enhanced Fe(III)-reduction despite receiving potentially lethal doses. The microbial ecology was probed throughout irradiations using pyrosequencing to reveal significant shifts in the microbial communities, dependent on dose and availability of organic electron donors. The radiation tolerance of an algal contaminant of a spent nuclear fuel pond was also assessed. FT-IR spectroscopy revealed a resistant phenotype of Haematococcus pluvialis, whose metabolism may be protected by the radiation induced production of an astaxanthin carotenoid. The experiments of this thesis provide evidence for a range of impacts of ionizing radiation on microorganisms, including the potential for radiation to provide the basis for novel ecosystems. These results have important implications to the long-term storage of nuclear waste and the geomicrobiology of nuclear environments.

Management of contamination from industrial activities and wastes from nuclear power generation and weapons development are arguably amongst the greatest challenges facing humanity currently and into the future. Understanding the mobility of toxic radioactive elements is essential for successful remediation strategies and safe management of our nuclear waste legacy (DEFRA, 2008). Interactions between minerals and radionuclides, such as sorption and precipitation, govern the mobility of the contaminants through the subsurface environment. Microbial metabolic processes (redox cycling or release of metabolites) have the potential to affect drastically these abiotic interactions. Microbially-driven mineralisation processes could provide long-term solid-phase-capture solutions to radionuclide contamination problems and support safety cases for geological disposal of radioactive waste. The recent advancements at the intersection between mineralogy, microbiology and radiochemistry were reviewed with the aid of a cluster analysis (Self-Organising Map). This is a relatively novel method of creating a map of the ‘research landscape’ which provides a visual summary of the reviewed literature and can help to identify areas of promising and active research as well as less researched interdisciplinary areas. It is the first time this tool has been applied to research literature on this interdisciplinary topic, and it highlighted the need to gain further understanding of ternary systems including bacteria, minerals and radionuclides. The analysis showed that phyllosilicates are of interest, but few studies have explored the properties of the Fe(II)/Fe(III)-containing micas biotite and chlorite. The ability of model Fe(III)-reducing microorganisms to reduce Fe(III) in biotite and chlorite was demonstrated in batch model systems. In chlorite, approximately 20% and in biotite ~40% of the bulk Fe(III) was transformed to Fe(II) by this reduction. To our knowledge, this is the first study to show the availability of Fe(III) in biotite for such reduction and the ability of the model organism Shewanella oneidensis MR-1 to conserve energy for growth using Fe(III) in biotite as the sole electron acceptor. The microbial Fe(III) reduction led to a decrease in the sorption of Cs and Sr by chlorite, but had very little effect on sorption to biotite. The data indicate that remediation strategies based on microbial Fe(III) reduction may exacerbate the movement of Cs and Sr through strata where sorption is dominated by phyllosilicates, particularly chlorite. While microbial Fe(III) reduction had only a slight effect on the sorption properties of biotite and chlorite, it drastically altered their redox properties. Previously bioreduced biotite and chlorite readily removed Cr(VI), Tc(VII) and Np(V) by surface-mediated reduction. The minerals were also able to reduce U(VI), but solution chemistry affected this reaction, reflecting the complexity of the biogeochemistry of this actinide. Overall, this work highlights the importance of decoupling microbial and geochemical processes in developing a holistic understanding of radionuclide behaviour in the environment. This body of work forms the thesis is entitled ‘Mineralisation and Biomineralisation of radionuclides’, and was prepared by Diana Roumenova Brookshaw for submission in August 2013 for the degree of Doctor of Philosophy to the University of Manchester.

Hoy en día no existe duda de que un convenio arbitral puede ser extendido a partes no signatarias. Un caso en el que esto puede ocurrir es cuando la parte no signataria tiene una participación activa en el iter contractual, es decir, en la negociación, celebración, ejecución y/o terminación del contrato que contiene un convenio arbitral. Diversos tribunales arbitrales internacionales han concluido que esta participación activa del no signatario prueba su consentimiento implícito al arbitraje.El consentimiento es un elemento fundamental del arbitraje y, como tal, su ausencia conlleva la anulación del laudo. En este contexto, más allá de la postura de los tribunales arbitrales, es necesario conocer cuál es la postura quehan adoptado las cortes (por ejemplo, en vía de anulación del laudo) al analizar la existencia de consentimiento implícito. ¿Han adoptado una postura rígida o flexible? Este artículo aborda esta cuestión. Concretamente, los autores presentan un estudio de las decisiones emitidas por las cortes de Inglaterra, Suecia, Suiza, España y Francia que refleja una distinta postura (más o menos rígida) respecto del consentimiento implícito.

This paper seeks to interpret Fear and Trembling’s paradox of faith together with Kant’s examination of the problem of freedom, in order to reconcile Kierkegaard’s thought with rationalism, but at the same time, to enrich the latter with a more existential language. It argues that, at the ground of all ethics, a certain experience beyond the limits of reason is found, albeit not an irrational one. / El siguiente trabajo busca interpretar la paradoja de la fe presente en Temor y temblor a la luz de la problemática kantiana en torno a la libertad, de tal modo que podamos reconciliar el pensamiento de Kierkegaard con el racionalismo, pero al mismo tiempo, enriquecer a este último con un discurso de carácter existencial. Sostendremos que a la base de toda ética se encuentra una experiencia más allá de los límites de la razón, pero no por ello irracional.

Increased DOC and Fe concentrations from terrestrial landscapes has led to the browning of boreal surface waters. The negative societal and ecological impacts of brownification are increased cost of water purification, increased presences of algae and cyanobacteria, loss of ecosystem services and reduced recreational value. Impacts of climate change, changes in land use and reduced sulfur deposition have been identified as drivers of brownification. While it has been recognized that DOC and Fe from terrestrial landscapes is increasing, little has been done to understand the impact of different land use practices on brownification. This research aims at evaluating the DOC and Fe runoff from spruce plantations, clear-cuts and wetland landscapes and determining the export of DOC from these landscapes into humic lakes. To do that, streams running through these three different land use types were sampled for water colour, pH, temperature, conductivity, DOC and Fe both at upstream and downstream of each land use type. Further, water discharge was calculated with the help of flow speed measurements and stream profiling (width, depth and channel shape). DOC (but not Fe) concentrations changed significantly depending on land use type. Wetlands lead to reduced DOC concentrations, whereas especially spruce plantations lead to increased stream water DOC concentrations.

Beta-titanium alloys for use as biomaterials are very interesting from the perspective of obtaining a reduction of the elastic modulus, which together with good mechanical properties, avoid the problems of stress shielding that, induce bone reabsorption. The obtaining process of these alloys is complex because the refractory elements that are normally used to stabilize the beta phase (Nb, Ta, Mo). Powder metallurgy is a relatively simple technology that allows the design of custom alloys, presenting ease in alloy modification, but this technique also presents some disadvantages, such as porosity, lack of diffusion or lack of grain size and phase transformation control. This thesis proposes the development of new alloys using conventional powder metallurgy techniques. The main objective is the study of the effect of the iron content on a Ti35Nb10Ta alloy (% wt.) on the beta phase stability and the final properties obtained, when the alloys are obtained by powder metallurgical techniques. The effect of small iron additions on porosity, microstructure and mechanical properties has been evaluated. It is also studied the behavior of these alloys in corrosion and the possibility of applying severe plastic deformation (SPD) to powder metallurgic beta alloys, as a means of microstructural control and improvement of mechanical properties. For the microstructural study, optical microscopy has been used to evaluate the porosity, and electron microscopy, both scanning (SEM) and transmission (TEM), to determine the phase distribution and the interaction between them. The orientation of the crystals is determined by electron backscatter diffraction (EBSD) and by automatic crystal orientation measurements (ACOM) in transmission electron microscopy when the nanometric characterization of the phases is required after the application of severe plastic deformation that has been performed by high-pressure torsion (HPT). The mechanical properties are determined by bending, compression and hardness tests. The elastic modulus, which can be estimated in the bending and compression tests, has been determined by nanoindentation and by ultrasounds. The corrosion resistance of the developed alloys, and therefore the effect of the iron addition on the Ti35Nb10Ta base alloy, has been performed by electrochemical corrosion tests with a three-electrode system using a simulated body fluid electrolyte (SBF). The results show that the iron produces an increase of the porosity that has a negative influence on the final mechanical properties. Complete stabilization of the beta phase is achieved, although there is an increase in grain size. The bending mechanical resistance decreases with the addition of iron, although it maintains the compression resistance. However, in spite of the greater stabilization of the beta phase, the addition of iron produces an increase in the elastic modulus of the studied alloys. The corrosion resistance is similar for all alloys studied, showing little influence with the variation of the iron content of the alloy. Finally, it has been possible to obtain a nanostructured material with the application of SPD by high-pressure torsion with different iron contents, which involves a smaller grain size and an increase of the mechanical properties with a smaller elastic modulus, which is very promising for future researches. / Las aleaciones de titanio beta para su uso como biomateriales resulta muy interesante desde la perspectiva de obtener una disminución del módulo elástico que, junto con unas buenas propiedades mecánicas, evite los problemas de apantallamiento de tensiones que inducen la reabsorción ósea. La obtención de estas aleaciones es compleja debido a que los elementos que normalmente se utilizan para estabilizar la fase beta (Nb, Ta, Mo) son refractarios. La pulvimetalurgia es una tecnología relativamente sencilla que permite el diseño de aleaciones a medida, presentando facilidad en la modificación de la aleación, pero esta técnica también presenta algunos inconvenientes, como la porosidad, falta de difusión o falta de control en el tamaño de grano y la transformación de fases. En esta tesis se propone el desarrollo de nuevas aleaciones mediante técnicas convencionales de pulvimetalurgia. Siendo el objetivo principal el estudio del efecto del contenido de hierro en una aleación Ti35Nb10Ta (% en peso) en la estabilidad de la fase beta y las propiedades finales obtenidas, cuando las aleaciones se obtienen mediante técnicas pulvimetalúrgicas. Se ha evaluado el efecto de pequeñas adiciones de hierro en la porosidad, microestructura y propiedades mecánicas. También se estudia el comportamiento de estas aleaciones respecto a la corrosión y la posibilidad de aplicar deformación plástica severa (SPD, Severe Plastic Deformation) a aleaciones beta de origen pulvimetalúrgico, como medio de control microestructural y para mejora de las propiedades mecánicas. Para el estudio microestructural se ha utilizado microscopía óptica, para evaluar la porosidad, y electrónica, tanto de barrido (SEM) como de transmisión (TEM), para determinar la distribución de las fases y la interacción entre ellas. La determinación de la orientación de los cristales se realiza mediante difracción de electrones retrodispersados (EBSD, Electron Backscatter Diffraction) y mediante un sistema automático de medida de la orientación cristalina (ACOM, Automatic Crystal Orientation Measurements) en Microscopía electrónica de transmisión cuando se requiere la caracterización nanométrica de las fases tras la aplicación de deformación plástica severa que se ha realizado mediante torsión a alta presión (HPT, High-Pressure Torsion). Las propiedades mecánicas se determinan mediante ensayos de flexión, y compresión, así como la determinación de la dureza. El módulo elástico, que puede estimarse en los ensayos de flexión y compresión, se ha determinado por nanoindentación y mediante ultrasonidos. La resistencia frente a la corrosión de las aleaciones desarrolladas, y por tanto el efecto de la adición de hierro en la aleación base Ti35Nb10Ta, se ha realizado mediante ensayos de corrosión electroquímica, con un sistema de tres electrodos, utilizando un electrolito de fluido corporal simulado (SBF, Simulated Body Fluid). Los resultados obtenidos muestran que el efecto del hierro produce un incremento de la porosidad que presenta una influencia negativa en las propiedades mecánicas finales. Se consigue una estabilización completa de la fase beta, aunque también se produce un incremento del tamaño de grano. La resistencia mecánica a flexión disminuye con la adición de hierro, aunque mantiene la resistencia en compresión. Sin embargo, pese a la mayor estabilización de la fase beta, la adición de hierro produce un incremento en el módulo de elasticidad de las aleaciones estudiadas. La resistencia a la corrosión es semejante para todas las aleaciones estudiadas, mostrando poca influencia con la variación del contenido de hierro de la aleación. Finalmente, se ha conseguido obtener una nanoestructuración del material con la aplicación de SPD mediante la técnica de torsión a alta presión con diferentes contenidos de hierro, que implica un menor tamaño de grano y un aumento de las propiedades mecánicas con un menor m / Els aliatges de titani beta per a utilitzar-los com biomaterials resulta molt interessant des de la perspectiva d'obtindre una disminució del mòdul d'elasticitat que, juntament amb unes bones propietats mecàniques, evite els problemes d'apantallament de tensions que indueixen la reabsorció òssia. L'obtenció d'aquests aliatges és complexa degut a que els elements que normalment s'utilitzen per estabilitzar la fase beta (Nb, Ta, Mo) son refractaris. La pulvimetal¿lúrgia és es una tecnologia relativament senzilla que permet el disseny d'aliatges a mesura, presentant la facilitat de modificació de l'aliatge, però aquesta tècnica també presenta alguns inconvenients, com la porositat, falta de difusió o falta de control en el tamany del gra i la transformació de les fases. En aquesta tesi es proposa el desenvolupament de nous aliatges mitjançant tècniques convencionals de pulvimetal¿lúrgia. Sent l'objectiu principal l'estudi de l'efecte del contingut de ferro en un aliatge Ti35Nb10Ta (% en pes) en l'estabilitat de la fase beta i les propietats finals obtingudes, quan els aliatges s'obtenen mitjançant tècniques pulvimetal¿lúrgiques. S'ha avaluat l'efecte de xicotetes addicions de ferro en la porositat, microestructura i propietats mecàniques. També s'estudia el comportament d'aquests aliatges front a la corrosió i la possibilitat d'aplicar deformació plàstica severa (SPD, Severe Plastic Deformation) a aliatges beta d'origen pulvimetal¿lúrgic, com mitjà de control microestructural i per millorar les propietats mecàniques. Per a l'estudi microestructural s'ha utilitzat microscòpia òptica, per avaluar la porositat, i electrònica, tant d'escombratge (SEM, Scanning Electron Microscope) com de transmissió (TEM, Transmision Electron Microscope), per a determinar la distribució de les fases y la interacció entre elles. La determinació de l'orientació dels cristalls es realitza mitjançant difracció d'electrons retrodispersats (EBSD, Electron Backscatter Diffraction) i mitjançant un sistema automàtic de mesura de l'orientació cristal¿lina (ACOM, Automatic Crystal Orientation Measurements) en microscòpia electrònica de transmissió quan es requereix la caracterització nanomètrica de les fases després de l'aplicació de deformació plàstica severa que s'ha realitzat mitjançant torsió a alta pressió (HPT, High-Pressure Torsion). Les propietats mecàniques es determinen amb assajos de flexió, compressió i durea. El mòdul elàstic, que pot estimar-se amb els assajos de flexió i compressió, s'ha determinat per nanoindentació i mitjançant ultrasons. La resistència front a la corrosió dels aliatges desenvolupats, i per tant l'efecte de l'addició de ferro en l'aliatge base Ti35Nb10Ta, s'ha realitzat mitjançant assajos de corrosió electroquímica, amb un sistema de tres elèctrodes, utilitzant un electròlit de fluid corporal simulat (SBF, Simulated Body Fluid). Els resultats obtinguts mostren que l'efecte del ferro produeix un increment de la porositat que presenta una influència negativa en les propietats mecàniques finals. S'aconsegueix una estabilització completa de la fase beta, encara que també es produeix un increment del tamany del gra. La resistència mecànica a flexió disminueix amb l'addició de ferro, encara que manté la resistència a compressió. No obstant açò, malgrat la major estabilització de la fase beta, l'addició de ferro produeix un increment en el mòdul d'elasticitat dels aliatges estudiats. La resistència a la corrosió es semblant per a tots els aliatges estudiats, mostrant poca influència amb la variació del contingut de ferro de l'aliatge. Finalment, s'ha aconseguit obtenir una nanoestructuració del material amb l'aplicació de SPD mitjançant torsió a alta pressió amb diferents continguts de ferro, que implica una menor grandària de gra i un augment de les propietats mecàniques amb un menor mòdul d'elasticitat, la qual cosa resulta molt p / Amigó Mata, A. (2017). Influencia de las adiciones de Fe en las aleaciones de Ti-Nb-Ta obtenidas mediante tecnología de polvos, para aplicaciones biomédicas [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/80618 / TESIS

Titanium dioxide (TiO2) is an important semiconducting metal oxide and is expected to play an important role in future applications related to photonic crystals, energy storage, and photocatalysis. Two aspects regarding the combustion synthesis have been investigated; scale-up in laboratory synthesis and advanced nanoparticle synthesis. Concerning the scale-up issue, a novel curved wall-jet (CWJ) burner was designed for flame synthesis. This was achieved by injecting precursors of TiO2 through a central port into different flames zones that were stabilized by supplying fuel/air mixtures as an annular-inward jet over the curved wall. This provides a rapid mixing of precursors in the reaction zone with hot products. In order to increase the contact surface between the precursor and reactants as well as its residence time within the hot products, we proposed two different modifications. The CWJ burner was modified by adding a poppet valve on top of the central port to deliver the precursor tangentially into the recirculating flow upstream within the recirculation zone. Another modification was made by adopting double-slit curved wall-jet (DS-CWJ) configuration, one for the reacting mixture and the other for the precursor instead of the central port. Particle growth of titanium dioxide (TiO2) nanoparticles and their phases were investigated. Ethylene (C2H4), propane (C3H8), and methane (CH4) were used with varying equivalence ratio and Reynolds number and titanium tetraisopropoxide (TTIP) was the precursor. Flow field and flame structure were quantified using particle image velocimetry (PIV) and OH planar laser-induced fluorescence (PLIF) techniques, respectively. TiO2 nanoparticles were characterized using high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Raman Spectroscopy, and BET nitrogen adsorption for surface area analysis. The flow field quantified by PIV consisted of a wall-jet region leading to a recirculation zone, an interaction jet region, followed by a merged-jet region. The modified CWJ burner revealed appreciable mixing characteristics between the precursor and combustion gases within these regions, with a slight increase in the axial velocity due to the precursor injection. This led to more uniformity in particle size distribution of the synthesized nanoparticles with the poppet valve (first modification). The double-slit modification improved the uniformity of generated nanoparticles at a very wide range of stable experimental conditions. Images of OH fluorescence showed that flames are tightly attached to the burner tip and TTIP has no influence on these flames structures. The particle size was slightly affected by the operating conditions. The phase of TiO2 nanoparticles was mainly dependent on the equivalence ratio and fuel type, which impact flame height, heat release rate and high temperature residence time of the precursor vapor. For ethylene and methane flames, the anatase content is proportional to the equivalence ratio, whereas it is inversely proportional in the case of propane flames. The anatase content reduced by 8% as we changed Re between 8,000 and 19,000, implying that the Re has a slight effect on the anatase content. The synthesized TiO2 nanoparticles exhibited high crystallinity and the anatase phase was dominant at high equivalence ratios (φ >1.6) for C2H4, and at low equivalence ratios (φ <1.3) for the C3H8 flame. Concerning advanced nanoparticle synthesis, a multiple diffusion burner and flame spray pyrolysis (FSP) were adopted in this study to investigate the effect of doping/coating on TiO2 nanoparticles. The nanoparticles were characterized by the previously mentioned techniques in addition to thermogravimetric analysis (TGA) for carbon content, X-ray photoelectron spectroscopy (XPS) for surface chemistry, ultraviolet-visible spectroscopy (UV-vis) for light absorbance, inductively coupled plasma (ICP) for metal traces, and superconducting quantum interference device (SQUID) for magnetic properties. Results from multi diffusion burner show that doping TiO2 with vanadium changes the phase from anatase to rutile while doping and coating with carbon or SiO2 does not affect the phase. Doping with iron reduces the band gab of TiO2 particles by reducing the conduction band. FSP results show that iron doping changes the valance band of the nanoparticles and enhances their paramagnetic behavior as well as better light absorption than pure titania, which make these particles good candidates for photocatalytic applications.

京都大学 / 0048 / 新制・論文博士 / 博士(農学) / 乙第13294号 / 論農博第2877号 / 新制||農||1073(附属図書館) / 学位論文||R1||N5239(農学部図書室) / (主査)教授 清水 浩, 准教授 中嶋 洋, 教授 飯田 訓久 / 学位規則第4条第2項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

The quasicrystals are characterized by unusual rotational symmetries that are not observed in the crystalline materials, which is the cause of their interesting material properties. Because of that a particular attention was paid to quasicrystalline structures in the literature research. The research also contains a description of electron beam technology, spark plasma sintering method and introduction to the problematics of wear. As the default materials for the experimental part were selected Titanium Grade 2 powder and Cristome A5 powder which was partially composed of quasicrystalline phase. The first series of samples was sintered only from powder Cristome A5. The second series was sintered from the mixture of 80 % Titanium Grade 2 powder and 20 % Cristome A5 powder. For the compaction of samples spark plasma sintering technology was selected. Samples were then systematically modified by electron beam and subjected to pin on disc tests. Samples modified at 750 °C had the best wear resistance. Samples modified at 1150 °C contained increased amount of quasicrystalline phase.

The master thesis deals with DSC measurments a calculation of kinetic parameters. In the theoretical part, iron alotropy is briefly described, followed by a description of the DSC analysis itself. The thesis also includes division and derivation of isoconversional methods for calculating the activation energy. In the experimental part, a series of measurments is perfomed on pure iron prepared by Cold Spray method. In the paper the influence of deformation on the Curie temperature of the magnetic transformation in -Fe and transformation > is investigated. The activation energy is calculated for transformation > for different degrees of deformation. The degree of deformation is monitored by channeling contrast.