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311	Development of covalent organic frameworks for energy storage applications : DAAQ-TFP COF and MXene composite electrodes for proton cycling Singh, Simanjit January 2022 (has links) The demand for today's material resources for energy storage is rapidly increasing and can result in both environmental and political conflicts that can affect the development of electronic devices due to high prices and limitations of raw materials for batteries. In this study, potential future composite electrodes were synthesised with an ex-situ approach by compositing redox-active 2,6-Diaminoanthraquinone and 1,3,5-Triformylphloroglucinol covalent organic framework (DAAQ-TFP COF) with conductive delaminated Ti3C2Tx MXene to maximise the number of redox-active moieties during cycling. In addition, solvothermal synthesis with the implementation of mechanical grinding as an exfoliation method was used to try to obtain DAAQ-TFP nanosheets to increase both the contact area between the two materials and the number of charge carriers. The sample was analysed with PXRD and BET surface analysis to characterise the crystallinity meanwhile SEM was utilised to study the morphology of the COF and the composite material. The specific capacitance of each electrode was estimated by cyclic voltammetry. The study showed a decrease in reduced specific capacitance with lower MXene content. Hence, this concludes pure Ti3C2Tx sheets have the highest capacitance contribution with a value of 48.79 Fg-1 meanwhile the composite electrode with a ratio of 1:1 was estimated to 32.26 Fg-1 with 0.0928 % of its moieties undergoing a redox reaction. A reduced capacitance with an increased COF-MXene ratio indicates that MXene contributes with more capacity relative to the COF, in combination with a non-successful exfoliation of DAAQ-TFP to single-layered nanosheets, reducing the interactions between the two materials. covalent organic framework DAAQ-TFP MXene composite electrodes 1 3 5-Triformylphloroglucinol 2 6-Diaminoanthraquinone nanosheets exfoliation ex-situ Ti3C2Tx Organic Chemistry Organisk kemi Inorganic Chemistry Oorganisk kemi Materials Chemistry Materialkemi
312	Computational Studies of Chemical Interactions: Molecules, Surfaces and Copper Corrosion Halldin Stenlid, Joakim January 2017 (has links) The chemical bond – a corner stone in science and a prerequisite for life – is the focus of this thesis. Fundamental and applied aspects of chemical bonding are covered including the development of new computational methods for the characterization and rationalization of chemical interactions. The thesis also covers the study of corrosion of copper-based materials. The latter is motivated by the proposed use of copper as encapsulating material for spent nuclear fuel in Sweden. In close collaboration with experimental groups, state-of-the-art computational methods were employed for the study of chemistry at the atomic scale. First, oxidation of nanoparticulate copper was examined in anoxic aqueous media in order to better understand the copper-water thermodynamics in relation to the corrosion of copper material under oxygen free conditions. With a similar ambition, the water-cuprite interface was investigated with regards to its chemical composition and reactivity. This was compared to the behavior of methanol and hydrogen sulfide at the cuprite surface. An overall ambition during the development of computational methods for the analysis of chemical bonding was to bridge the gap between molecular and materials chemistry. Theory and results are thus presented and applied in both a molecular and a solid-state framework. A new property, the local electron attachment energy, for the characterization of a compound’s local electrophilicity was introduced. Together with the surface electrostatic potential, the new property predicts and rationalizes regioselectivity and trends of molecular reactions, and interactions on metal and oxide nanoparticles and extended surfaces. Detailed atomistic understanding of chemical processes is a prerequisite for the efficient development of chemistry. We therefore envisage that the results of this thesis will find widespread use in areas such as heterogeneous catalysis, drug discovery, and nanotechnology. / Den kemiska bindningen – en hörnsten inom naturvetenskapen och oumbärlig för allt liv – är det centrala temat i den här avhandlingen. Både grundläggande och tillämpade aspekter behandlas. Detta inkluderar utvecklingen av nya beräkningsmetoder för förståelse och karaktärisering av kemiska interaktioner. Dessutom behandlas korrosion av kopparbaserade material. Det sistnämnda är motiverat av förslaget att använda koppar som inkapslingsmaterial för hanteringen av kärnavfall i Sverige. Kvantkemiska beräkningsmetoder enligt state-of-the-art har använts för att studera kemi på atomnivå, detta i nära sammabete med experimentella grupper. Initialt studerades oxidation av kopparnanopartiklar under syrgasfria och vattenrika förhållanden. Detta för att bättre kartlägga koppar-vattensystemets termodynamik. Av samma orsak detaljstuderades även gränsskiktet mellan vatten och kuprit med fokus på dess kemiska sammansättning och reaktivitet. Resultaten har jämförts med metanols och vätesulfids kemiska beteende på ytan av kuprit. En övergripande målsättningen under arbetet med att utveckla nya beräkningsbaserade analysverktyg för kemiska bindningar har varit att överbrygga gapet mellan molekylär- och materialkemi. Därför presenteras teoretiska aspekter samt tillämpningar från både ett molekylärt samt ett fast-fas perspektiv. En ny deskriptor för karaktärisering av föreningars lokala elektrofilicitet har introducerats – den lokala elektronadditionsenergin. Tillsammans med den elektrostatiska potentialen uppvisar den nya deskriptorn förmåga att förutsäga samt förklara regioselektivitet och trender för molekylära reaktioner, och för interaktioner på metal- och oxidbaserade nanopartiklar och ytor. En detaljerad förståelse av kemiska processer på atomnivå är en nödvändighet för ett effektivt utvecklande av kemivetenskapen. Vi förutspår därför att resultaten från den här avhandlingen kommer att få omfattande användning inom områden som heterogen katalys, läkemedelsdesign och nanoteknologi. / <p>QC 20170829</p> computational chemistry density functional theory chemical interactions reactivity descriptors copper corrosion surface and materials science nucleophilic substitution reactions heterogeneous catalysis transition metal oxides nanotechnology beräkningskemi täthetsfunktionalteori kemiska interaktioner reaktivitetsdeskriptorer kopparkorrosion yt- och materialvetenskap nukleofila substitutionsreaktioner heterogen katalys överångsmetalloxider nanoteknologi Chemical Sciences Kemi Materials Chemistry Materialkemi Organic Chemistry Organisk kemi Physical Chemistry Fysikalisk kemi Theoretical Chemistry Teoretisk kemi
313	Methane and Carbon Dioxide Emissions From Three Smallscale Hydropower Stations in South of Sweden / Metan- och Koldioxidutsläpp Från Tre Småskaliga Vattenkraftverk i Södra Sverige Danielsen, Edevardt Johan, Jonsson Valderrama, Alexandra January 2022 (has links) Over the past decades, evidence show that the anthropogenetic greenhouse gases (GHG) emissions of carbon dioxide (CO₂) and methane (CH₄) are the main drivers behind global warming and are becoming stronger. Globally, hydropower is among the main sources of renewable energy and the popular notion that hydropower electricity is carbon neutral has been under debate as evidence from measurements in different regions of the globe show significant and highly variable carbon emissions from hydropower reservoirs. But these global estimates are still highly uncertain since they are restricted to a few locations in the south of Europe, North America, and South America, and lack both the temporal and spatial variability in addition to some of the flux pathways (often downstream emission and degassing). This study assesses the CH4 and CO₂ emissions from reservoirs associated to three small hydropower stations in the south of Sweden and aims to understand potential spatial and temporal variability in the temperate region. The study performed flux measurements of CH4 and CO₂, an analysis of CH4 and DIC concentration in the water, and a depth profile of temperature, DO, CH4 and DIC at the hydropower station’s reservoirs. In summation this study finds significant CH4 and DIC concentrations, as well as CH4 and CO₂emissions from the studied reservoirs. The findings of this study underline the notion that hydropower might be a `blind spot` in the Swedish GHG budget report, and if so, the carbon emissions from hydropower electricity need to be re-evaluated. Hydropower Reservoir Freshwater (automated) Flux chambers Emissions Ebullition Diffusion Greenhouse gases GHGs Methane CH4 Carbon dioxide CO2 Dissolved oxygen DO Variability Spatial Temporal Dissolved inorganic carbon. Vattenkraft Reservoar Sötvatten (automatiserade) Fluxkammare Utsläpp Ebullition Diffusion Växthusgaser GHHs Metan CH4 Koldioxid CO2 Löst syre DO Variabilitet Rumslig Temporal Löst oorganiskt kol. Earth and Related Environmental Sciences Geovetenskap och miljövetenskap Biological Sciences Biologiska vetenskaper Other Natural Sciences Annan naturvetenskap Environmental Sciences Miljövetenskap Climate Research Klimatforskning Organic Chemistry Organisk kemi Inorganic Chemistry Oorganisk kemi
314	Synthesis of Thiophene-Vinyl-Benzothiazole Based Ligand Analogues for Detection of Aβ and Tau Pathology in Alzheimer's Disease Johansson, Joel January 2024 (has links) As of today, Alzheimer’s disease is the leading cause of dementia among neurodegenerative disorders, affecting many millions of people worldwide. As the average life span of populations increase, more and more people succumb to the illness each year. Like other neurodegenerative disorders, Alzheimer’s disease can be attributed to the accumulation of protein aggregates in the brain. These amyloid-β peptides and tau proteins can presumably be detected in the brain many years before the onset of clinical symptoms. Development of fluorescent ligands, capable of binding to these neuropathological hallmarks and highlighting them, could serve as molecular diagnostic tools and facilitate an early diagnosis of the disease. The method could also be useful in studying disease progression and evaluating the effects of novel treatments. One such ligand is HS-259. The aim of this project was to synthetize different analogues of HS-259, and test their selectivity towards the aforementioned aggregates in brain tissue from an individual with Alzheimer’s disease. Staining of tissue samples with analogue solution enables visualization of aggregate sites through fluorescence imaging. In the end, five analogues were synthetized, albeit in relatively low overall yields. Synthetic methods included Suzuki-Miyara cross-couplings, Ullmann-type arylations and condensations. Liquid Chromatography-Mass Spectrometry (LC-MS) and Nuclear Magnetic Resonance (NMR) were used for analysis of the compounds. Two of the five analogues could be tested for staining of aggregates and assessed for photophysical characteristics, i.e. absorption- and emission spectra. One analogue stained both amyloid-β aggregates and some tau aggregates, whereas the other stained neither. Since only two analogues were tested and rendered inconsistent results, further studies are needed to assess the binding properties of HS-259 analogues in general. Alzheimer's disease neurodegenerative disorders protein aggregates molecular ligands amyloid-β Aβ amyloid-beta tau diagnosis HS-259 staining brain tissue Suzuki coupling Ullmann arylation condensation NMR nuclear magnetic resonance LC-MS liquid chromatography neuropathological hallmarks absorption spectra emission spectra synthesis plaques symptoms neuropathology thiophene-vinyl-benzothiazole TVBT ligand analogues N-arylation Knoevenagel preparative LC PBS phosphate buffered saline treatments AD mechanisms thiophene benzothiazolium fluorescence imaging bTVBT bi-thiophene-vinyl-benzothiazole detection Suzuki-Miyara Organic Chemistry Organisk kemi

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