Cryptic trends in the trace element chemistry of Fe-Ti oxide minerals have been used to elucidate the magmatic processes responsible for the formation of Fe-Ti-V deposits in the Rivière Bell Complex layered mafic-ultramafic intrusion near Matagami, Quebec, Canada. Although metamorphism at greenschist-amphibolite facies conditions has modified the primary igneous compositions of magnetite and ilmenite, their Cr and V contents appear to have been unaffected. Chemostratigraphic variations of these elements in Fe-Ti oxides therefore remain valid tracers of magmatic differentiation, even in metamorphosed settings. Injections of compositionally evolved, Fe-Ti oxide-laden magma into a more primitive ferrogabbroic host are presumably responsible for sharp decreases in the Cr and V concentrations of Fe-Ti oxides that coincide with lithostratigraphic changes from predominantly disseminated gabbros to ultramafic sequences closely interlayered with massive oxides. These injections highlight the multistage magmatic history of the layered series of the Rivière Bell Complex and its vanadium ore horizons.

O complexo R2TP está presente em eucariotos, de leveduras a humanos, e está envolvido no correto dobramento de outras proteínas e montagem de complexos multiproteicos. R2TP é formado pelas proteínas Rvb1, Rvb2, Tah1 e Pih1/Nop17 em levedura, e direciona as chaperonas à proteínas alvo durante a montagem dos complexos. Os clusters Fe/S são sintetizados nas mitocôndrias e posteriormente transferidos para o citoplasma. Dre2 é uma proteína que contém cluster Fe/S, e está envolvida na transferência desses clusterspara outras proteínas citoplasmáticas. Nosso laboratório identificou a interação entre a subunidade Nop17 do complexo R2TP e Dre2 pelo método de duplo-híbrido, mas o papel desta interação ainda não foi elucidado. O objetivo deste trabalho foi o de estudar o papel funcional da interação entre Dre2 e Nop17 e identificar seus domínios de interação. Nossos resultados mostram que a porção N-terminal de Nop17 interage com a porção C-terminal de Dre2 e esta interação é necessária para a manutenção dos níveis de Dre2 na célula, indicando que o complexo R2TP atue na montagem do complexo CIA, de proteínas citosólicas Fe/S, do qual Dre2 faz parte. Dre2 também afeta a estabilidade de Nop17, sugerindo que Dre2 possa transferir um clusterFe/S para Nop17. Os dados mostrados aqui, portanto, indicam que a interação Nop17-Dre2 seja mutuamente importante para a estabilidade das duas proteínas / The R2TP protein complex is present in eukaryotes from yeast to humans, and is involved in the correct assembly of other protein or ribonucleoprotein complexes. R2TP is formed by proteins Rvb1, Rvb2, Tah1 and Pih1/Nop17 in yeast, and directs chaperones to target proteins during complexes assembly. Fe/S clusters are synthesized in mitochondria and later transferred to the cytoplasm. Dre2 is a Fe/S cluster protein, involved in transferring of Fe/S clusters to cytoplasmic proteins. Our laboratory has identified the interaction between the R2TP subunit Nop17 and Dre2 in the two-hybrid system. The aim of this work was to study the functional role of the interaction between Dre2 and Nop17, and to identify their domains of interaction. The results show that the N-terminal portion of Nop17 interacts with the C-terminal region of Dre2, and that this interaction is necessary for maintaining the levels of Dre2 in the cell, which suggests that the R2TP complex affects the cytosolic iron-sulfur protein assembly complex (CIA), of which Dre2 is a subunit. Dre2 also affects Nop17 stability, suggesting that Dre2 may transfer a Fe/S cluster to Nop17. The data here indicate that the interaction Nop17-Dre2 is mutually important for these proteins stabilities.

The correlation of vacancy concentration with microhardness of Fe-Al alloys was studied on samples quenched from 1000 řC and subsequently annealed at lower temperatures. Using X-ray diffraction the lattice parameter and crystal structure were determined for samples of Fe-Al alloys. By measurements of positron lifetime was revealed the high concentration of vacancies in quenched samples and subsequent annealing caused significant decrease in vacancy concentration while in samples with Al content above 39% also the decrease of microhardness was measured. Measurements of coincidence Doppler broadening of annihilation peak helped to distinguish the annihilations coming from positron trapped or delocalized annihilated by electrons of both atoms, Fe and Al. Comparison of measured results with theoretical quantum-mechanics calculations performed in this diploma thesis determined the most probable defect type as a vacancy on A-sublatice of B2 structure.

Title: Investigation of vacancies in Fe-Al alloys Author: RNDr. František Lukáč Department: Department of Low Temperature Physics Supervisor: doc. Mgr. Jakub Čížek, Ph.D., Department of Low Temperature Physics, Faculty of Mathematics and Physics Abstract: Fe-Al alloys exhibit relatively high vacancy concentrations, which significantly influence the mechanical properties of these alloys. Positron annihi- lation spectroscopy was employed for investigations of vacancies in this work and the vacancy concentrations in Fe-Al alloys were determined by positron lifetime spectroscopy and measurements of positron diffusion length of implanted mono- genergetic positrons. The correlation of hardness with the vacancy concentration was characterized by determination of the vacancy hardening coefficient in Fe- Al alloys. The thermal evolutions of hardness and the vacancy concentration were compared during the annealing of the Fe-Al alloys with various composi- tions. Coincidence Doppler broadening of annihilation peak was employed for determination of the chemical composition of quenched-in vacancies in Fe-Al al- loys. Increased concentration of Al atoms in surrounding vacancies in Fe-Al alloys was related to the attractive interaction between the Al atoms and the vacancy. Quantum mechanical ab initio calculations were...

Eisen-Gallium-Legierungen sind aufgrund ihrer hohen Magnetostriktion und ihrer hervorragenden mechanischen Eigenschaften sehr interessant für Anwendungen sowohl in Form von Sensoren als auch Aktoren. Die fortschreitende Miniaturisierung erfordert die Herstellung von Bauteilen in eindimensionaler Struktur und komplexen Geometrien. Beide Herausforderungen sind mit templatbasierter elektrochemischer Abscheidung zugänglich. Es konnte gezeigt werden, dass dünne Fe-Ga-Schichten schon aus einfachen wässrigen Elektrolyten abgeschieden werden können. Gallium kann nur in Anwesenheit von Fe induziert reduziert werden. Gleichzeitig konnte nachgewiesen werden, dass durch die Hydrolyseneigung der Ga-Ionen immer Hydroxide gebildet und in das Deposit eingebunden werden. Durch die Einführung einer alternierenden potentiostatischen Abscheidung mit einem Reduktions- und einem Relaxationsschritt können dennoch dichte und homogene Fe80Ga20-Schichten mit wenigen Defekten und einem vernachlässigbar kleinen Sauerstoffgehalt hergestellt werden. Die Übertragung der so gefundenen Abscheideparameter zur templatbasierten Nanodrahtherstellung ist nur bis zu einem Porendurchmesser von 100nm möglich. Wird der Durchmesser der Porenkanäle weiter verringert, führt aufgrund eingeschränkter Diffusionsvorgänge die Abscheidung zu segmentierten und sauerstoffreichen Depositen. Die Modifizierung des Elektrolyten durch Komplexierung der Metallionen verhindert die Bildung und Einbindung der Hydroxide. Damit können auch für Porendurchmesser kleiner 100nm Drähte in AAO-Template abgeschieden werden. Diese sind dicht, defektfrei und weisen keinen Zusammensetzungsgradienten entlang der Wachstumsrichtung auf. Detaillierte TEM-Untersuchungen konnten zeigen, dass die Herstellung durch ein einfacheres potentiostatisches Abscheideregime zu weniger verspannten und dennoch homogenen und defektfreien Drähten führt. Für die Herstellung von magnetisch aktiven Drähten sollte daher die potentiostatische der gepulsten Abscheidung vorgezogen werden.

The macrophytes have the ability accumulating multiple metals/metalloids species from the terrestrial and aquatic environments. The environmental-friendly phytoremediation technologies via these plant species have been applied for non-degradable pollutants removal. The macrophytes derived rhizofiltration is a major and efficient technology for metals/metalloids removal, especially in aquatic environments (e.g. wetland). Comparing with the common metals/metalloids often studied, aquatic U rhizofiltration via macrophytes has been just considered recently. In this study, the field investigation in a U tailing basin wetland showed that the rhizofiltration was crucial for aquatic U retention via Phragmites australis Trin ex Steud. (water to root bioconcentration factor (BCF): 670 to 1556). The aquatic U retention efficiency in aboveground biomass of P. australis was insufficient (BCF: 0.4 to 5.3), comparing with the rhizofiltration. However, the high productivity (1.2 to 1.9 kg•m-2 per growing season) of P. australis still resulted in a notable yearly U accumulation in the areal total aboveground biomass (0.04 to 0.35 mg•m-2 per growing season). It was potentially promoted by the enhanced aquatic U rhizofiltration. The U within aboveground biomass could be released to submerse soil with the degradable or recalcitrant fallen litters. It enhanced the organic carbon supply in rhizosphere together with the root litter, and potential water to root U translocation within mobilized organic compounds. Hence the rhizofiltration stood in the crucial position of the plant-litter-water-soil U recycling in aquatic environment. The results from field investigation and mesocosm experiment further suggested that the Fe plaque (IP) on root surface was crucial for aquatic U rhizofiltration. The IP contained most of root retained U in both environments (proportion of U within IP: 55.8 to 82.6% in field and 66.7 to 86.0% in mesocosm). However, the efficiency of IP assisted aquatic U rhizofiltration was affected by the redox state gradient (-179 to 220 mV) related redox processes. Field investigation suggested that high content of dissolved oxygen (up to 8.2 mg•l-1) was capable to rapidly oxidize soluble Fe(II) as sparingly soluble Fe(III) oxides precipitated in subhydric soil. It consequently limited the aquatic Fe availability for root uptake and precipitation as IP. However, the strong oxidation ability also relatively increased aquatic U(VI) availability incorporated with inorganics and degradable organic matters. It was adverse for controlling the aquatic U concentration (66.7 to 92.0 μg•l-1 in field). On the other hand, it also benefited the U uptake by inner root tissue and upward translocation to aboveground biomass of P. australis. The different inorganic N species also significantly influenced IP assisted aquatic U rhizofiltration. The aquatic NH4+ sustained the reduction and acidification (via nitirification) potential for Fe(III) and U(VI) bioreduction in rhizosphere (-87 to 21 mV in NH4+ cultured mesocosm pots). It improved the root uptake (mainly within IP) of Fe and U (2992.9 to 5010.7 mg•kg-1 Fe and 45.7 to 62.8 mg•kg-1 U in NH4+ cultured root). On the contrary, the NO3- depended strong oxidation ability (23 to 224 mV in NO3- cultured mesocosm pots) inhibited the IP formation and the related aquatic U rhizofiltration efficiency (1568.5 to 2569.5 mg•kg-1 Fe and 26.2 to 49.6 mg•kg-1 U in NO3- cultured root). The aquatic U availability in rhizosphere was also increased via NO3- depended oxidation processes (aquatic U concentration in mesocosm: 1.6 to 589.3 μg•L-1 (NO3-) vs. 1.4 to 58.2 μg•L-1 (NH4+)). The sufficient nitrogen supply is also a significant driving force for high biomass productivity of P. australis. The higher biomass of P. australis increased the U accumulation capacity for root and aboveground tissues. The nitrogen related high biomass accumulation of P. australis also potentially enhanced the share of organic bound U in subhydric soil via plant litters supply. The IP assisted aquatic U rhizofiltration was also affected by the co-existing metals/metalloids in rhizosphere. The field investigation indicated that high As availability (aquatic As/U ratio: 0.7 to 1.6) inhibited the U retention within IP through the competitive absorption, due to its high affinity to IP. The Ca improved the aquatic U(VI) availability by forming the soluble Ca-uranyl-carbonate compounds. The Ca also potentially competed with hydrated Fe(III) oxides within IP by incorporating with U and encourage the U retention within inner root tissue. The P was beneficial for U retention within IP possibly in form of U-Fe-phosphate complexes. However, it was still need to be proofed in further studies. Despite of the biogeochemical conditions in rhizosphere, the aboveground transpiration of P. australis also affected the IP formation and related aquatic U rhizofiltration. The higher transpiration rate (TR) of P. australis (3.3±1.2 mm•d-1 in field, 4.5±2.0 mm•d-1 (NH4+)/5.0±2.2 mm•d-1(NO3-) in mesocosm) increased the aquatic nutrient/non-essential elements availability for root uptake. For this reason, the aquatic U rhizofiltration of P. australis (21.8±3.1 mg•kg-1 in field, 62.1±1.0 mg•kg-1 (NH4+)/47.6±1.8 mg•kg-1 (NO3-) in mesocosm) was enhanced under higher TR. The higher TR also promoted the formation of IP and its U retention capacity. Furthermore, the U translocation from root to above ground biomass (mainly in leaves) of P. australis was also enhanced under higher TR. It was potentially benefited by the increased transpirational pull and root uptake of other active mediator (e.g. Ca). The effect of transpiration was also coupled with the different N species on IP assisted aquatic U rhizofiltration. The higher TR depended strong root uptake and assimilation of N increased the biomass accumulation of P. australis. Furthermore, the higher TR also potentially increased the share of root in biomass partition of P. australis. Consequently, the stronger transpiration resulted in the higher aquatic U accumulation in area related root biomass (up to 84.0±3.6 mg•m-2 (NH4+) and 86.4±5.8 mg•m-2 (NO3-) U per season in mesocosm). In conclusion, it was possible for eutrophic P. australis stands to retain the aquatic U via rhizofiltration. The IP on root surface was a crucial mediator contributing the aquatic U rhizofiltration, especially in iron rich milieu. The efficiency of IP assisted aquatic U rhizofiltration could be further improved under suitable environmental conditions. In this study, these conditions might include: i) reductive rhizosphere environment with active reducers (e.g. NH4+) encouraging Fe(II) generation for IP formation and U retention within it; ii) limited competitive elements (e.g. As and Ca) co-existed with Fe and U in rhizosphere; iii) sufficient nutrients (e.g. N) supply and related high biomass productivity of plant; iv) strong transpiration effect improved the nutrient assimilation of root and also the aquatic U/Fe availability for root uptake. By adjusting these conditions (also include other potential factors not discussed in this study), an effective rhizofiltration technology was supposed to be applied for aquatic U removal.

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Det här projektet har gått ut på att med hjälp av FEdatorprogram analysera hållfastheten hos ett ställdon utvecklat av företaget Cascade Drives. Ställdonet ska användas för att driva en vattenpump som utsätts för laster på upp till 30 ton. Det består av ett växelhus, en elmotor och ett kuggstång-pinionsystem. Motorn sitter direkt på växelhuset med ett motorfäste. De egenskaper som skulle studeras var dels växelhusets deformation och vilka spänningar som uppstod i detta, samt dess egenfrekvenser. Dessutom skulle motorfästes egenfrekvenser och egensvängningar undersökas speciellt för att säkerställa att ingen av de frekvenser som kunde tänkas exciteras vid drift skulle kunna få motorfästet i egensvängning. Motorfästet skulle också modelleras som både aluminium och stål, för att bestämma vilket materialval som var bäst lämpat.  Alla delarna utom kuggstången och dess bussningar erhölls som CADmodeller från Cascade Drives, och analysen gjordes i FEprogrammet Ansys Academic Teaching Mechanical and CFD, 2020 R1, med modulerna Static Structural och Modal. Då licensen begränsade antalet noder som kunde användas i meshen för lösningen till max 256 000 noder, var en del av delarnas geometri tvungna att förenklas genom att ta bort hål, avrundningar och inre ihåligheter. Motorns inre geometri visade sig vara så komplicerad att en helt ny simplifierad modell av den togs fram. Likaså utvecklades enkla modeller av kuggstången och dess bussningar. Allt CADarbete utfördes i programmet Solid Edge 2019.  För att spara noder modellerades inte rullagren eller stängerna som CADmodeller, utan ersattes av joints respektive beam connections i Ansys. Lagerkrafterna som förs över från axlarna till lagersätena modellerades som bearing forces i radiell led. Lagrens och kugghjulens massor simulerades som punktmassor. Inspänningsrandvillkoren sattes på flänsarnas undersidor för att simulera att ställdonet stod på en stålställning. Remote displacement, frictionless support och elastic support användes för detta.  Resultaten visade att växelhuset med god marginal håller för påfrestningarna, och att ingen av dess egenfrekvenser direkt överlappar med excitationsfrekvenserna. Motorfästet görs med fördel av stål, då motorfästets resonansfrekvenser hamnade relativt nära motorfrekvenserna och stålfästets resonansfrekvenser låg högre i spektrumet än frekvenserna för fästet gjort i aluminium. / The purpose of this project was to use FE computer software to analyse the durability of an actuator developed by the company Cascade Drives. The actuator will be used to drive a water pump subjected to loads of up to 30 tonnes. It consists of a gearbox, an electric motor and a rack and pinion system. The motor is directly mounted to the gear housing. The characteristics studied were the deformation of the gearbox, the generated stresses as well as its natural frequencies. Furthermore, the eigenfrequencies of the motor mount were to be investigated to ensure that none of the frequencies excited in the gear housing by the gears and motor risked inducing self-oscillation.  The mount was also to be analysed as if made from steel or aluminium, in order to decide the most appropriate material. All parts except the rack and the bushings were obtained as CAD models from Cascade Drives. The analysis was done in the FE program Ansys Academic Teaching Mechanical and CFD, 2020 R1, with the modules Static Structural and Modal. As the license only allowed a maximum of 256 000 nodes in the mesh, some of the part’s geometries had to be simplified by removing holes, fillets, and cavities. The motor’s geometry was especially complex, and a completely new, simplified model was created, as well as a simple rack and bushing models. All CAD work was done in the software Solid Edge 2019 To further decrease the number of nodes used neither the bearings nor the bars were modelled as CAD models, but rather as joints and beam connections in Ansys. The feature ‘bearing forces’ was used to model the forces from the shafts on the bearing seats. The weight of the gears and bearings were simulated as point masses. In order to simulate the actuator as being mounted on a steel frame, the boundary conditions ‘remote displacement’, ‘frictionless support’ and ‘elastic support’ were added to the bottom of the flanges.  The results showed that the gear housing can withstand the stresses with a good margin, and that none of the eigenfrequencies matched those excited. It also showed that the best material for the mount is steel, as the eigenfrequencies of the steel mount were higher than those of the aluminium mount, which is preferable since they then are further from the motor’s frequency.

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