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Faculty of Science

 

Recent Submissions

  • Ketola, William (2024)
    As the demand for sustainable energy sources is continuously growing, green hydrogen produced by water splitting is considered one of the key energy sources of the future. In this thesis, catalysts with low noble metal content for the acidic Oxygen Evolution Reaction (OER) have been synthesized, and their electrochemical performance have been investigated. OER is one of the half-cell reactions in water-splitting, the other being the Hydrogen Evolution Reaction (HER). The OER is the more energy demanding and harder to optimize half-cell reaction, because of its more complex kinetics. The currently well-studied catalysts for the acidic OER, namely IrO2 and RuO2, are expensive, scarce and not feasible to use on a large scale. For these reasons, in this thesis, catalysts mainly consisting of WOx with low content of Ru and Ir have been developed. Five different catalysts of the general form RuxIryW1-x-yOz have been synthesized starting from RuCl3, IrCl3, WCl6 and EtOH in a three-step synthesis. These catalysts were characterized by UV-Vis spectroscopy, XRD, Raman spectroscopy, SEM and TEM, and their electrocatalytic performance was evaluated using Linear Sweep Voltammetry (LSV), Electrochemical Impedance Spectroscopy (EIS) and Cyclic Voltammetry (CV). SEM and TEM showed that the catalysts had a sphere-like morphology with some crystalline features, while Raman and XRD confirmed that the catalysts contained RuO2, IrO2 and WOx. The key findings of the electrochemical analysis were that the catalysts with increased Ir content compared to Ru and W performed better than commercial IrO2 in terms of current density and overpotential, while increased Ru content compared to Ir and W showed negligible improvement of the catalyst performance. The catalysts with increased Ru content also performed worse than commercial IrO2. The best performing catalyst, Ru0.1Ir0.3W0.6Ox, was also stability tested. The stability test showed that the catalyst was only stable for around 15 minutes. In addition to the poor stability, the electrochemical performance in terms of current density and overpotential of the catalysts are worse than the best performing materials already reported in literature.
  • Karvonen, Konsta (2024)
    This master’s thesis reviews the relatively rare class of organic compounds known as mixed geminal dihalides, in which a single carbon atom is bonded to two different halogen atoms. Synthesizing this functional group is a challenging chemical transformation, for which the methodology is still scarce. Chapter four outlines fifteen distinct approaches, condensing key information from a comprehensive literature review. Together these methods provide a relatively large scope for producing compounds with the desired mixed geminal dihalide functionality. Often, but not always, utilizing the electronic properties and reactivity of adjacent carbonyl groups. Several applications for these versatile synthons are presented in chapter three, most of which rely on differences in the leaving group tendencies among halogen atoms. Utilizing this property, these compounds are often employed in the formation of new carbon-carbon bonds. Another important class of applications involves the generation of carbon radicals. For example, in our laboratory, geminal bromoiodo alkanes were exposed to laser irradiation at a specific wavelength to produce the desired iodine-containing radicals for further reactions. The experimental section focuses primarily on the synthesis of vinyl bromides as starting materials and their iodination under acidic conditions. The scope of the literature review is much broader, encompassing all four halogens in all possible combinations. However, the experimental findings highlight an important property of mixed geminal dihalides: their separation is often challenging. Less sophisticated synthetic routes tend to yield mixtures of dihalogenated products that may be even impossible to separate using standard methods. This practical issue stems from the electronic configuration, which causes different halogens to exhibit relatively similar physicochemical properties, with fluorine being a notable exception.
  • Rantala, Julia (2024)
    In the first part of this thesis, the usage of sodium dodecyl sulfate (SDS) as a micelle in micellar electrokinetic chromatography (MEKC) combined with ultra-violet (UV) detection is explored. This section provides a literature overview of 66 studies from 2011 to 2023, highlighting the versatility of the method with applications in diverse matrices, including beverages, food products, pharmaceuticals, and cosmetics. Despite the method’s advantages—such as cost-effectiveness and minimal reagent consumption—limitations, including low sensitivity with UV detection, are also addressed. Future directions for improving MEKC, such as incorporating alternative surfactants or detectors, are discussed. The experimental part investigates interactions between liposome membranes and derivatives of butenafine, an antifungal agent, using capillary electrochromatography (CEC). Originally intended to employ liposome electrokinetic capillary chromatography (LEKC), practical limitations led to the adoption of open-tubular CEC (OT-CEC) method, which employs liposomes as a coating, that acts as an stationary phase. This study successfully determined the distribution coefficients (log K) for two butenafine derivatives and demonstrated the influence of structural modifications on drug-membrane interactions. The results of this study contribute to the understanding of current state of SDS-MEKC methodologies and provide a basis for future advancements in drug-liposome interaction studies, with potential implications for pharmaceutical drug development.
  • Santasalo, Sini (2024)
    The theme of the thesis was the role of ionic liquids in liquid chromatography. Ionic liquids have several different types of functionalities, which means that they are prone to have multiple simultaneous interactions with the stationary and mobile phases of liquid chromatography. Ionic liquids have been used as analytes, mobile phase additives and column stationary phase modifiers. All these applications exploit the diversity of interactions with the different phases in liquid chromatography. Common roles of ionic liquids as mobile phase additives have been to reduce unwanted silanol effects with the column stationary phase, to act ion pair reagents to separate polar compounds with reversed phase chromatography and to act as UV absorption reagents to detect compounds that do not absorb UV light. The aim of the experimental work was to develop a liquid chromatography method to separate and quantitate a superbase ionic liquid and its hydrolysis products. Another task was to get familiar with the interactions with different column stationary and mobile phases. Columns with different stationary phase types were tested for this application and one column type was used for the quantitation of the superbase and its hydrolysis products. Preliminary experiments were also done to get an understanding on how to separate a difficult sample mixture containing compounds with both hydrophilic and hydrophobic compounds.
  • Gyllström, Juri (2024)
    Tässä tutkielmassa tarkastellaan matematiikan suomenkielisen opetuksen sisältämiä maahanmuuttajataustaisille, erityisesti Suomi toisena kielenä -opetukseen osallistuville oppilaille haasteellisia kielellisiä piirteitä. Tutkielman tavoitteena on selvittää, millaisin ehkäisevin keinoin voitaisiin parantaa matematiikan oppimateriaalien luettavuutta suomen kieltä keskimäärin heikommin taitavien oppilaiden tapauksissa. Tutkielman sisältämän kartoituksen tarpeellisuutta korostaa lisääntynyt huoli maahanmuuttajataustaisten ja kantaväestöön kuuluvien oppilaiden suoriutumiserojen kasvusta vuoden 2022 PISA-tutkimuksen tulosten pohjalta. Kielitaidon keskeisyys maahanmuuttajataustaisten oppilaiden koulumenestystä ennakoivana tekijänä tekee matematiikan opetuksen kielellisestä tarkastelusta tärkeätä oppimistulosten parantamiseksi. Matematiikan opetuksen kielellisen soveltuvuuden arvioimiseen käytetään avuksi matematiikan kielentämisen menetemiä oppimateriaali-lähtöisestä näkökulmasta. Kielentämisen menetelmät ja niiden soveltaminen esitellään tutkielman yhteydessä. Vieraskielisten oppilaiden matematiikan opetuksen tutkimukseen pohjautuvien havaintojen kautta voimme laatia oppimateriaalien arvioimisessa käytettävän viitekehyksen. Kyseistä viitekehystä voidaan myös jatkossa käyttää soveltavasti muun matematiikan opetuksen kielellisen soveltuvuuden arviointiin. Laaditun viitekehyksen pohjalta tarkastellaan lopuksi yläasteen oppimateriaalin sisältämiä esiintymiä havaituista kielellisistä ongelmakohdista. Tarkastelun yhteydessä esitellään tapoja tunnistaa ja korjata haasteellisia kielellisiä piirteitä, materiaalien luet-tavuuden parantamiseksi. Jatkotutkimuksen kannalta tutkielman lopulla esitetään pohdintaa luettavuuden parantamisen mahdollisista vaikutuksista, Suomi toisena kielenä -opetuksen toteutuksen ongelmista, sekä vallitsevista asenteista Suomi toisena kielenä -opetusta kohtaan.