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Coming dissertations at TekNat

  • The multifunctional role of carbon in electrochemical energy storage : Graphitic foams for 3D microbatteries and dual-ion batteries

    Author: Antonia Kotronia
    Publication date: 2019-11-12 12:38
  • Method development for the analysis of complex samples with inductively coupled plasma mass spectrometry

    Author: Marcus Korvela
    Publication date: 2019-11-08 12:28

    In this thesis the development of methods for handling the problems associated with analyzing trace elements in complex matrixes using inductively coupled plasma mass spectrometry is presented. Trace elements such as Cu, Fe, Se, and Zn, to name a few, do play important roles in different organisms. Therefore it can be of importance to study trace elements in different samples of biological origin. As trace elements are low in abundance, sensitive instrumental techniques such as inductively coupled plasma mass spectrometry (ICP-MS) are required for accurate determination. Due to the complexity of samples with biological origin, careful method development, both regarding the sample preparation and instrumental analysis has to be performed to minimize negative effects on the instrument signal and introduction of interferences.

    For example the metal contents of mink livers were analyzed, after bomb digestion to investigate if the metal concentration could be linked to changes in the organ morphology as well as the minks’ environment. Morphological changes and capture locations could be linked to the metals investigated. The investigation of the elemental composition of...

  • A geophysical investigation of carbonate build-ups in the Baltic Basin using reflection seismic and well data

    Author: Tegan Levendal
    Publication date: 2019-11-08 09:31

    During the Late Ordovician, the region around Gotland was part of a shallow epicratonic basin in the southern subtropics. Low latitudes, relatively warm sea temperatures and the presence of a shallow marine environment promoted algae to flourish and diverse carbonate build-ups such as carbonate mounds and reefs developed on the southern margin of Baltica. Locations where these build-ups can be found today include the Palaeozoic sequence beneath the island of Gotland, Sweden and surrounding areas offshore Gotland. Ordovician mud mounds on Gotland were exploited for their hydrocarbon potential during the 1970’s and 1980’s, with large amounts of seismic and well data being acquired by the oil company Oljeprospecketering AB (OPAB). In recent years this largely unpublished dataset has become available for research purposes. Furthermore, the islands of Gotland and Öland have been the target of helicopter-borne electromagnetic investigations conducted by the Geological Survey of Sweden (SGU) (SkyTEM and VLF). Moreover, new seismic reflection data acquired on a research vessel during 2017 complement the OPAB data over certain areas. In published scientific literature, carbonate mounds...

  • New aspects of electronic interactions of keV ions with matter

    Author: Barbara Bruckner
    Publication date: 2019-11-08 08:24

    Low- and medium-energy ion scattering are powerful techniques to perform high-resolution depth profiling with sub-nanometer resolution. Typically, ions with primary energies between a few keV and a few hundred keV are used to probe the sample and backscattered projectiles are detected. To obtain highly accurate composition profiles, knowledge on physical processes governing ion-matter interaction is crucial. Apart from the main (back-)scattering process, which yields a detectable signal, the projectile loses energy in interactions with both electrons and nuclei (stopping) along its path in matter. In all these interactions, also the charge state of the probing particle can be altered. Information on this multitude of interaction mechanisms can be deduced from two different experimental approaches: either in backscattering or transmission geometry. Especially towards lower primary energies, available experimental data are found more scarce. This situation is particularly true for more complex targets, i.e. reactive transition metals and their compounds. This absence of quantitative information on energy loss or charge exchange processes hampers in many cases the quality of...

  • Non-cyanobacterial nitrogen fixation insights in humic freshwater lakes and ponds

    Author: Leyden Fernandez-Vidal
    Publication date: 2019-11-07 13:08

    The biological basis of nitrogen fixation beyond the canonical role of Cyanobacteria is not well understood in freshwater ecosystems. To address this gap in knowledge, the main objective of this thesis is to study non-cyanobacterial nitrogen fixation in freshwater lakes and ponds.

    Microbial communities and diazotrophic potential were characterized by direct metagenome sequencing from seasonally stratified lakes and permafrost thaw ponds, both of which are systems featuring strong redox gradients. To quantify the nitrogen fixation process, we also adopted and applied a 15N tracer method to estimate realized diazotrophic activity in five of the studied lakes. Chemical characteristics were also measured concomitantly to link diazotroph distribution patterns to chemical features and metabolic traits in the studied freshwaters.

    Exploring a 3-year metagenomic time series of a humic lake (Trout Bog), widespread and stable occurrence of nifH genes were detected. This marker gene for nitrogen fixation appeared with accessory genes, validating the marker. The diazotrophic community was diverse and dynamic with contributions from Geobacter, Desulfobacterales,...

  • Ribosomal translocation in real time : Method development to Applications

    Author: Chang-il Kim
    Publication date: 2019-11-07 10:40

    Translational elongation is the process in which the ribosome adds one amino acid at a time to the nascent peptide chain. As the ribosome elongates the peptide chain by 14 - 20 amino acids per second and performs hundreds of such cycles per protein, ‘elongation’ is one of the most crucial steps in translation. During elongation, the ribosome must move precisely by one codon along the mRNA after peptidyl transfer. This step is known as ‘ribosomal translocation’, which is catalyzed by the elongation factor G (EF-G). Despite extensive research, the exact sequence of events in translocation is still unclear. Thus, development of an in vitro assay, which would allow precise kinetic measurement of the steps involved in ribosomal translocation, is highly important. In 2003, a research group led by Simpson Joseph designed a fluorescence-based assay to monitor translocation in stopped-flow using a short mRNA labeled with fluorescent-dye pyrene at the 3’ end. Although optimized for the highest fluorescence change, this assay showed significantly slower translocation than what has been measured by conventional translocation assays. Moreover, when performed with a popular peptidyl...

  • Predictive Healthcare : Cervical Cancer Screening Risk Stratification and Genetic Disease Markers

    Author: Nicholas Baltzer
    Publication date: 2019-11-06 12:51

    The use of Machine Learning is rapidly expanding into previously uncharted waters. In the medicine fields there are vast troves of data available from hospitals, biobanks and registries that now are being explored due to the tremendous advancement in computer science and its related hardware. The progress in genomic extraction and analysis has made it possible for any individual to know their own genetic code. Genetic testing has become affordable and can be used as a tool in treatment, discovery, and prognosis of individuals in a wide variety of healthcare settings. This thesis addresses three different approaches to-wards predictive healthcare and disease exploration; first, the exploita-tion of diagnostic data in Nordic screening programmes for the purpose of identifying individuals at high risk of developing cervical cancer so that their screening schedules can be intensified in search of new dis-ease developments. Second, the search for genomic markers that can be used either as additions to diagnostic data for risk predictions or as can-didates for further functional analysis. Third, the development of a Ma-chine Learning pipeline called ||-ROSETTA that can effectively...

  • Fat-IBC : A New Paradigm for Intra-body Communication

    Author: Noor Badariah Asan
    Publication date: 2019-11-06 10:13

    In the last two decades, a significant development in the field of medical technology occurred worldwide. This development is characterized by the materialization of various body implants and worn devices, that is devices attached to the body. These devices assist doctors and paramedical staff in effectively monitoring the patient’s health and helping increase patients’ average life expectancy. Furthermore, the various implants inside the human body serve different purposes according to the humans’ needs. As this situation became more prominent, the development of protocols and of reliable transmission media is becomes essential to improve the efficiency of inter-device communications. Positive prospects of the use of human tissue for intra-body communication were proven in recent studies. Fat tissues, for example, which also work as energy banks for human beings, can be potentially used in intra-body communications as transmission media. In this thesis, the fat (adipose) tissue’s function as an intra-body communication channel was investigated. Therefore, various simulations and experimentations were performed in order to characterize the reliability of the fat tissue in terms...

  • Sustainable methods for the preparation of diverse Au(I) complexes

    Author: Fredric Ingner
    Publication date: 2019-10-25 14:53

    Over the last three decades, the role of Au(I) complexes has become increasingly important within medicinal chemistry, material applications and synthesis. Alas, their preparation remains reliant on harsh reaction conditions, hazardous solvents, exogenous additives and, often, high reaction temperatures. Within this thesis we develop mild, sustainable, methods for the preparation of Au(I) complexes, that takes place in ambient conditions and omits the use of hazardous solvents. These goals are realized in two different manuscripts. The first manuscript utilizes a nucleophilic borate to afford Au(I) aryl complexes in green solvents without the requirement for exogenous additives. Purification consists of a simple filtration and washing step and affords products in very good to excellent yields for most examples. The second manuscript employs a mechanochemical protocol for expedient preparation of Au(I) aryl complexes from a number of parent aryl sources such as borates, arenes and heteroarenes. This includes the first mechanochemical preparation of Au(I) aryl complexes from borate or hetroarene sources. The developed mechanochemical C-H auration protocols allow for significantly...

  • Genomic and evolutionary exploration of Asgard archaea

    Author: Eva F. Caceres
    Publication date: 2019-10-24 10:32

    Current evolutionary theories postulate that eukaryotes emerged from the symbiosis of an archaeal host with, at least, one bacterial symbiont. However, our limited grasp of microbial diversity hampers insights into the features of the prokaryotic ancestors of eukaryotes. This thesis focuses on the study of a group of uncultured archaea to better understand both existing archaeal diversity and the origin of eukaryotes.

    In a first study, we used short-read metagenomic approaches to obtain eight genomes of Lokiarchaeum relatives. Using these data we described the Asgard superphylum, comprised of at least four different phyla: Lokiarchaeota, Odinarchaeota, Thorarchaeota and Heimdallarchaoeta. Phylogenetic analyses suggested that eukaryotes affiliate with the Asgard group, albeit the exact position of eukaryotes with respect to Asgard archaea members remained inconclusive. Comparative genomics showed that Asgard archaea genomes encoded homologs of numerous eukaryotic signature proteins (ESPs), which had never been observed in Archaea before. Among these, there were several components of proteins involved in vesicle formation and membrane remodelling.

    In a second...