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Coming dissertations at TekNat

  • Additive Manufacturing of Ni-Fe Superalloys : Exploring the Alloying Envelope and the Impact of Process on Mechanical Properties

    Author: Carl Johan Hassila
    Publication date: 2022-09-16 11:29

    Additive manufacturing of metals has received a lot of attention in the last decade as this family of manufacturing processes allows the manufacturing of complicated geometries which would be difficult to produce using conventional manufacturing techniques. Additive manufacturing of the Ni-Fe based superalloys 625 and 718 using the Powder Bed Fusion – Laser Beam (PBF-LB) process is facilitated by the fact that these alloys were developed as weldable alternatives to other high-strength, high-temperature Ni-based superalloys. However, given that these alloys were developed with casting and forging as the main manufacturing route, the alloying composition of these alloys may possibly be tuned to better suit the PBF-LB process. In this thesis, small changes to the alloy 625 and 718 alloy compositions were made, with the goal of either improving material properties or reducing the environmental footprint of the produced materials. For alloy 718, the influence of carbon content on the resulting microstructure and mechanical properties was investigated both in the as-built and heat-treated conditions using tensile and impact testing. A similar study, but also including corrosion...

  • Comparative genomics of the genus Mycobacterium : Genome evolution, phylogeny and diversity

    Author: Phani Rama Krishna Behra
    Publication date: 2022-09-14 12:39

    The genus Mycobacterium includes more than 190 species, and many cause severe diseases such as tuberculosis and leprosy. According to the "World Health Organization", in year 2019 alone, 10 million people developed TB, and 1.4 million died. TB had been in decline in developed countries, but made its reappearance as an opportunistic pathogen targeting immuno-compromised AIDS victims. Also, non-tuberculosis mycobacteria (NTM) infections have emerged as a major infectious agent in recent times. NTM occupy diverse ecological niches and can be isolated from soil, tap water, and groundwater. This thesis has investigated the Mycobacterium species from a genomic perspective, focusing on the biology of virulence factors, mobile genetic elements, tRNAs, and non-coding RNAs and their evolutionary distribution and possible relationship with phenotypic diversity. 

    As part of this study, we have sequenced 153 mycobacterial genomes, including type strains, environmental samples, isolates from hospital patients, infected fish, and outbreak samples in an animal facility at Uppsala University. We have provided a phylogenetic tree based on 387 (and 56) core genes covering...

  • Live long and phosphor : synthesis of new 2,1,3-benzothiadiazole based scaffolds and novel organo-Au(I) luminophores

    Author: Mauricio Posada Urrutia
    Publication date: 2022-09-12 13:29

    2,1,3-Benzothiadiazole (BTD) has arisen as a scaffold of interest to a variety of fields including materials chemistry and medicinal chemistry. It is utilized in the development of light emitting materials, solar-cells, and batteries. This work describes the synthesis of new BTD derivatives with substitution patterns that are not commonly seen in publications that mention BTD-based materials. These substitutions are primarily based on functionalizations accessed through iridium catalyzed C–H borylation and subsequent oxidation with OXONE®. The selectivity arising from the C–H borylation of BTD has inspired further modifications of the BTD backbone in ways not previously explored. The borylation of BTD has allowed for the direct auration of this heteroaromatic core. Transmetalation of benzo[2,1,3]thiadiazol-4-ylboronic acid with five different Au(I) salts leads to the formation of aurated BTD complexes with a series of distinct coordinating ligands (PPh3, PtBu3, PCy3, IPr and IMes). Herein the synthesis of five BTD–Au(I)–L complexes is described and their structure was confirmed by NMR and X-ray diffraction. Aryl–Au(I) complexes have found uses in a variety of fields but their...

  • Transition metal dissolution from Li-ion battery cathodes

    Author: Yonas Tesfamhret
    Publication date: 2022-09-08 13:54

    Lithium-ion batteries (LIBs) have become reliable electrochemical energy storage systems due to their relative high energy and power density, in comparison to alternative battery chemistries. The energy density of current LIBs is limited by the average operating voltage and capacity of oxide-based cathode materials containing a variety of transition metals (TM). Furthermore, the low anodic stability of "conventional" carbonate-based electrolytes limits further extension of the LIBs voltage window. Here, ageing mechanisms of cathodes are investigated, with a main focus on TM dissolution and on strategies to tailor the cathode surface and the electrolyte composition to mitigate TM dissolution.

    Atomic layer deposition (ALD) coatings of the cathode surface with electrically insulating Al2O3 and TiO2 coatings is employed and investigated as a method to stabilize the cathode/electrolyte interface and minimize TM dissolution. The thesis illustrates both the advantages and limitations of amorphous oxide coating materials during electrochemical cycling. The protective oxide layer restricts auto-catalytic salt degradation and the consequent propagation of acidic species in the...

  • Exploring microfluidics as a tool to study cell-biomaterial interactions

    Author: Sarah-Sophia Carter
    Publication date: 2022-09-08 11:53

    Considering the tremendous amount of research on the development of novel biomaterials, relatively few of these have reached the patient. This can at least in part be explained by the lack of predictive power of the currently used in vitro models, which are nowadays recognized to be too reductionist to accurately predict in vivo complexity. 

    Recently, microfluidics-based (i.e. on-chip) systems have been proposed as a promising method to enhance physiological relevance in an in vitro environment. A key feature of such a system is that it contains one or multiple channels, with at least one dimension at the micrometer scale. Such channels enable cell confinement at more physiologically relevant length scales and a higher level of control over the microenvironment. In addition to this, there is the option to provide fluid flow, which does not only provide nutrients to and remove waste from the cells, but can also mechanically stimulate the cells. 

    The aim of this thesis was to explore microfluidics as a tool to evaluate cell-biomaterial interactions, particularly in the context of bone tissue. Two main themes can be distinguished,...

  • Effects of gangliosides and PEG-lipids on the structure, properties and interactions of lipid self-assemblies

    Author: Philipp Grad
    Publication date: 2022-09-08 09:13

    When developing or utilizing lipid-based nanocarriers detailed structural characterization of the lipid self-assemblies, as well as in depth knowledge and control of their interaction with solids materials, is necessary to understand the behaviour. Disregarding one of the parameters can lead to misinterpretation of the results due to non-uniform samples or experimental artifacts caused by undesirable interactions with solid surfaces. 

    Work included in this thesis show that gangliosides promote structural transitions of PEGylated liposomes to bilayer disks. The results suggest that the proposed ability of gangliosides to attenuate the anti-PEG immune response could be coupled to their ability to promote disk-formation.

    The results of this thesis further emphasize the importance of processes taking place at the solution-solid interface between self-assembled lipid particles and solid surfaces. Silica surfaces were here of particular interest, and the results showed that PEGylated lipid nanocarriers, such as liposomes and lipodisks, spontaneously attach to the material. It was further shown that an elevation of the temperature can lead to irreversible structural...

  • Organic Electrode Battery Materials : A Journey from Quantum Mechanics to Artificial Intelligence

    Author: Rodrigo P. Carvalho
    Publication date: 2022-09-07 14:00

    Batteries have become an irreplaceable technology in human life as society becomes progressively more dependent on electricity. The demand for novel battery technologies has increased fast, especially with the popularisation of different portable devices. However, the current battery industry relies heavily on non-renewable resources that are also prone to provoke environmental harm. Among the possible candidates for the next generation of batteries, organic electroactive materials (OEMs) have become attractive due to a series of advantages: vastly accessible from renewable raw materials; highly versatile due to the possible functionalisation mechanisms; possibly lower production costs; reduced environmental impacts; etc. Nevertheless, some drawbacks need to be overcome before OEMs become competitive. Issues with energy density, rate capability and cycling stability hinder their final technological application. This thesis thereby discusses fundamental aspects of OEMs and proposes novel techniques to accelerate the materials discovery process.

    The first part of this thesis presents a pathway to systematically investigate organic materials by combining quantum mechanics...

  • Remediation of per- and polyfluoroalkyl substance-contaminated soil and groundwater, using electrokinetic and stabilisation methods

    Author: Georgios Niarchos
    Publication date: 2022-09-06 11:32

    Per- and polyfluoroalkyl substances, commonly known as PFAS, are emerging contaminants with a worldwide environmental distribution and a concerning (eco)toxicological profile. The omnipresence of PFAS in various environmental media poses risks to the quality of our drinking water sources. Soils can act as inventories of PFAS plumes, which can slowly find their way into water resources. There is an imperative need for treatment applications at the pollution hotspots to prevent the spreading of PFAS into water bodies. This thesis aimed to investigate the potential of two technologies for treating PFAS-contaminated soils and groundwater: one focused on PFAS removal using electrokinetics and the other on their immobilisation in the subsurface using stabilisation with colloidal activated carbon (CAC). The findings of this thesis show that both methods can be promising; however, their effectiveness depends on compound-specific parameters and field considerations at the contaminated sites. The electrokinetic removal was highly effective for short-chain PFAS, with up to 99% removal for PFAS with C≤6 in their perfluorocarbon chain. Electrokinetic removal was also coupled with...

  • The induced magnetospheres and magnetotails of Mars and Venus

    Author: Aikaterini Stergiopoulou
    Publication date: 2022-09-05 13:38

    In this work we focus on several aspects of the ionospheres, induced magnetospheres, and magnetotails of the unmagnetized planets Mars and Venus. The solar wind interaction with unmagnetized planets differs from the magnetized planets: they are more directly exposed to the solar wind, and consequently can respond faster and more dynamically to solar wind variations, necessitating careful analysis of the driving conditions upstream simultaneously with plasma measurements in the system. This thesis is a compilation of an introductory part, and four articles. Three examine the ionosphere and the induced magnetosphere of Mars, while the last one investigates the properties of the induced magnetotail of Venus. Data from ESA’s Mars Express (MEX) and NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) missions are used in the Mars studies, while measurements from the two first Venus flybys of ESA’s Solar Orbiter (SolO) mission are used in the final paper. In our first study we investigate the nightside ionosphere of Mars using measurements from special high altitude operations of the ionospheric radar on board MEX. We find a consistent presence of plasma in the terminator region and...

  • Development of phosphorus-containing metallo-β-lactamase inhibitors : Synthesis and binding studies by solution NMR and molecular docking

    Author: Katarzyna Palica
    Publication date: 2022-09-05 11:18

    The rapidly growing bacterial resistance development is turning into one of the main challenges of the 21st century. Our antibiotics are becoming ineffective for the treatment of bacterial infections, and without successful action, simple infections, such as pneumonia or Septicemia, will soon carry a highly probable mortal prognosis. Among the most widely spread mechanisms of bacterial resistance are the degradation and modification of antibiotics, prior to them reaching the target site, by bacterial enzymes.

    This thesis work aims to contribute to solving a major societal challenge by providing new knowledge on the binding site of the NDM-1, which is one of the clinically most relevant enzymes used by bacteria to degrade antibiotics. The work includes the design and synthesis of potential β-lactamase inhibitors that mimic the transition state of the enzymatic hydrolysis of β-lactam antibiotics. These bioisosteric transition state analogues are expected to bind and inhibit NDM-1, without being hydrolysable. Thereby they could potentially slow down or even halt the degradation of our β-lactam antibiotics is use.

    The first chapter describes the specific aims, whereas...

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