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Browsing by study line "Kemi"

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  • Peltoniemi, Martta (2023)
    The glymphatic system is a waste clearance system in the brain to prevent protein accumulation that negatively affects neural functions, leading to neurogenerative diseases such as Alzheimer's. Perivascular spaces surround the brain vasculature allowing cerebrospinal fluid (CSF) inflow into the brain parenchyma during NREM sleep. The CSF moves from perivascular spaces into the white matter through AQP4 water channels, and flows towards the efflux routes, from where the interstitial solutes are drained into the lymphatic system. The existence and functions of the glymphatic system raise controversies due to the lack of quantitative data. Imaging tools that do not negatively affect the flow are required to visualize the glymphatic system in health and disease. If the glymphatic flow could be intensified in a preventive or therapeutic manner or harness for CNS drug delivery, it would be revolutionary. Positron emission tomography (PET) is a rising imaging modality in glymphatic research. It provides an efficient and non-invasive method, even with nanomolar tracer concentrations, to follow the CSF within the entire animal, being also fully translatable for human studies. Albumin is the dominant protein the CSF and can act as a carrier for tracers extending the circulation time. More recently, truncated Evans Blue (EB) and 4-(p-iodophenyl)butyric acid (IP) have shown promising results in modulating the pharmacokinetics of radiopharmaceuticals through albumin-binding. This study aimed to develop and evaluate six new albumin- binding tracers ( three NODAGA conjugated and three DFO conjugated) for the PET imaging of the glymphatic fluid flow via binding of endogenous albumin in the CSF. The precursors were synthesized using coupling reactions and radiolabeled with [68Ga]GaCl3 (0.2M sodium acetate buffer, pH=4, 95°C or 25°C, 15 min). Radiochemical purities were determined by radio-TLC and radio-HPLC and LogD (octanol:PBS) with shake-flask method. The in vitro stability assays were done in rat serum, rat CSF, 2 mM EDTA, and 0.2 mM FeCl3 solutions at 37°C over 6 h of incubation. The in vitro albumin binding affinities were investigated at physiological rat CSF albumin concentration at 37°C over 1 h of incubation using radio-SEC- HPLC. The in vivo and ex vivo experiments of the three most stable tracers were done using healthy female Swiss mice, and the experiments included blood kinetic studies, ex vivo biodistribution studies, and analysis of urine, bile, and blood fractions (plasma, blood cells, proteins) for in vivo stability. The precursors were synthesized with high yields (69–96%) and radiolabeled with high radiochemical yield (64– 82%), radiochemical purity (97–99.5%), and molar activities sufficient for low-volume infusion into the CSF (9.2– 17.2MBq/nmol). The NODAGA conjugated tracers had higher radiochemical yield and molar activity than the DFO conjugated tracers. The radiolabeled DFO conjugated products were stable in rat serum and rat CSF, but stability assays with EDTA and FeCl3 showed major transchelation. The NODAGA conjugated tracers were stable in each medium, maintaining the percent of intact labeled compound above 97%. The albumin binding affinity studies showed full binding from the first time point of 5 min incubation until the last time point of 1 h. The blood kinetic studies of the three stable NODAGA conjugates showed decreasing %ID/g with varying biological half- lives depending on the tracers’ lipophilic properties. The ex vivo analysis of urine and bile showed eliminated free tracer or some metabolite of the free tracer with similar retention time with radio-HPLC, no free gallium was observed. The analysis of blood samples after fractionation showed that each tracer had the most significant %ID/g in the protein fraction, and no activity was observed in the plasma. The in vivo investigated tracers showed promising properties for possible future use as CSF tracer due to high radiolabel stability and rapid stable binding to albumin in vivo.
  • Suuronen, Markus (2021)
    People spend more than 90% of time indoors. That has made the analysis of indoor air quality an subject of interest. There is a growing popularity of miniaturized sample extraction techniques utilizing solid adsorbent materials and thermal desorption allowing direct sample introduction for analysis. This approach is solvent free and there is possibility for reusing adsorbent materials depending of adsorbent properties. This thesis covers the basics of adsorption-desorption process and takes detailed look on different adsorbent materials such as activated carbon (AC), metal-organic framework (MOF) and carbon nanotubes (CNT) and evaluates the effect of surface functionality and pore size distribution for adsorption process. In experimental part, a self-made autosampler functionality and its injection parameters were optimized. The autosampler is able to independently inject up to six in-tube extraction (ITEX) needles with complete desorption. The ITEX was constructed during this experiment with TENAX-GR adsorbent and the repeatability of autosampler and ITEXs were tested and compared to commercial system with extraction of different amines. The effectiveness of this system was also demonstrated for indoor volatile organic compound (VOC) analysis.
  • Meriläinen, Veronika (2022)
    As nuclear reactors come to the end of their lifetime, they undergo decommissioning. All the construction materials and spend nuclear fuel must be characterized according to their activities before final disposal. For the analysis of difficult to measure radionuclides, such as beta emitters, sample decomposition methods are used. Acid digestion, alkaline fusion and thermal combustion are examples of sample decomposition methods. In this work, alkaline fusion methods were tested to gain knowledge on the suitability of the method for volatile and non-volatile radionuclides in decommissioning waste. The sample materials tested were concrete and two difficult to dissolve reference materials: soil and coal fly ash. Results obtained with alkaline fusion were compared with that of routinely used acid digestion method. In addition, activated graphite was studied to familiarize with the analysis of difficult to measure radionuclides. Non-volatile 63Ni and 55Fe and volatile 3H and 14C were studied. The results were compared with modelled activities. Alkaline fusions were performed with a borate flux in an automated fusion oven as well as with a carbonate flux in a muffle furnace. Acid digestion was performed in an open vessel with aqua regia. The dissolved samples were analysed with ICP-OES and ICP-MS for determination of elemental concentrations. Borate fusion seemed to be the most effective method, as it was suitable for all the sample materials and released even refractory elements. Some of the volatile elements were lost during the fusion methods (Cd and Zn), while some were not affected by the high temperatures used (Pb). Alkaline fusion methods appeared to be suitable for decommissioning studies, however further research is needed. In analysis of graphite, non-volatile elements were analysed by acid digestion. 55Fe and 63Ni were separated from the matrix by hydroxide precipitation and from each other by ion exchange in an AG-resin. Ni fraction was further purified by extraction chromatography with a Ni-resin. Volatile elements were analysed by thermal combustion in a pyrolyser. The activities of 55Fe, 63Ni, 3H and 14C were measured with liquid scintillation counting. The measured activity concentrations of 63Ni were partially in agreement with the modelled values, but some samples gave higher activities. No 55Fe activities were found in any samples, as was expected based on the modelled values and the short half-life of the radionuclide. Activities of the volatile 3H and 14C were accurate and close to the modelled values. In the future, the determined activity results will be used for improving scaling factors, for the assessment of radionuclide concentrations in graphite.
  • Niskala, Iiro (2023)
    This study focuses on analyzing dust samples with gas chromatography coupled with mass spectrometer. Humans get exposed to dust daily and it is important to know the risks this exposure brings. Dust is a complex, mainly organic matrix, which absorbs compounds easily. Some of these absorbed compounds have adverse effects on human health. To identify these harmful compounds from samples, they must be extracted into a solvent and possibly cleaned, so that they can be analyzed with gas chromatography coupled with a mass spectrometer system. Analysis of dust samples requires the right gas chromatography column, which can separate analytes of interest and a mass spectrometer with an ion source that can be used to analyze the sample qualitatively and/or quantitatively depending on the depth and type of the study. Along with samples, standards are used in quality control of the analysis method and in finding limitations of the method. Methods and results of the studies used in this thesis are compiled into tables. Sources and health effects of found compounds are discussed. In the experimental part of the thesis, analysis of dust samples from Finnish museums was done for the Finnish Institute of Occupational Health. These samples were concentrated and analyzed with gas chromatography coupled with a mass spectrometer system. The system had calibration issues, which had to be solved before the data it provided was usable. After the calibration issue was fixed, the analysis results were obtained and studied. In these results many harmful compounds were found, of which many were related to the preservation of the items housed in the museums. The compounds' health effects were studied and tabulated. These results show that further studies are required for dust samples to avoid exposure to compounds found in them.
  • Kyökari, Mikko Matias (2023)
    The literature part of the thesis gives an overview of the occurrence, properties, biological activities, and analytical approaches used for the quantification of resin acids and their derivatives in tree resins, with the emphasis being on a balanced discussion of specific analytical merits and limitations. The quantification of resin acids is challenging due to their isomeric nature and limited stability, with these marker compounds being sensitive to light, oxygen, and strong acids. Methods employing reversed phase liquid chromatographic (LC) approaches in combination with UV/Vis, fluorescence, and mass spectrometric (MS) detection are covered. Gas chromatographic (GC) approaches, involving various derivatization schemes, are discussed, with detection being typically achieved by flame ionization (FI) and MS. Less frequently employed protocols, utilizing zone capillary electrophoresis with cyclodextrin additives and UV and/or fluorescence detection (FLD) are reviewed. Finally, emerging protocols employing supercritical fluid chromatography in combination with FI and MS detection are outlined. Baseline resolution of all major resin acids can only be readily achieved with GC and supercritical fluid chromatography (SFC) methods, while LC and CE protocols suffer from partial peak overlap. In terms of practical convenience, SFC may provide currently the most favorable analytical approach, obviating the need for derivatization and allowing for superior sample throughput. The objective of the experimental part of the thesis was to develop robust and expediate HPLC/UV methods for the detection and quantification of selected active marker compounds, i.e., vanillin, p-coumaric acid, pinoresinol and dehydroabietic acid, in Norwegian spruce resin extracts. Emphasis was placed on obtaining protocols characterized by operational simplicity and ready transferability to production settings. The developed methods involved continuous hot extraction of milled resin samples with 96% EtOH, followed by a simple filtration step and isocratic reversed phase HPLC/UV analysis. A preliminary validation of the developed reversed phase HPLC/UV methods was carried out to assess the limits of detection and quantification (LOD and LOQ); calibration linearity/range; precision and accuracy. LOD and LOQ values were lower than 3 µg/mL and 8.5 µg/mL for all quantified active marker compounds, respectively. To demonstrate the applicability of the developed methods, two batches of Norwegian spruce resin samples were analyzed in three replicate samples.
  • Ilmarinen, Jenni (2023)
    Sizing agents are chemical additives used in paper and board making to improve hydrophobicity and to control the water penetration into the fiber network. This thesis reviews various analytical methods that have been reported to analyze three sizing agents: alkyl ketene dimer (AKD), alkenyl succinic anhydride (ASA), and rosin. Overview of the analytical methods includes gas chromatography, high-performance liquid chromatography, and Fourier transform infrared spectroscopy, along with newer techniques like ultraviolet-visible absorption spectroscopy and near infrared spectroscopy. These agents are analyzed from various paper products, like paper, process waters and dispersion. While the goal is to retain all added sizing agents within the paper or board, complete retention is not achievable, and some agents are present in process waters. Analyzing sizing agent levels in process waters allows for the evaluation of sizing agent retention. In the experimental section, Kemira Oyj's AKD analysis method for process waters from paper mills is updated. The hazardous and possibly carcinogenic extraction Solvent A is replaced with the greener and safer Solvent B. Sample preparation is improved, reducing analysis time from six hours to one. Additionally, a new high performance liquid chromatography – evaporative light scattering detector (HPLC-ELSD) method is introduced, capable of simultaneously analyzing AKD and hydrolyzed AKD (HAKD) in a single chromatogram. This is the first time a HPLC method is reported for analyzing HAKD from process waters. This method achieves 99% recovery rates with 0.2 ppm LOQ for both AKD and HAKD.
  • Youngren, Cristina (2023)
    Novichok nerve agents are persistent, highly toxic chemical weapons which were added to the Chemical Weapons Convention in 2020 after their use on civilians in England. The detection and characterization of Novichok nerve agents and the degradation products formed after their exposure to decontamination products can be accomplished through complementary instrumental analyses. Chromatographic methods such as LC-MS/MS can be utilized to qualitatively detect Novichok degradation products such as hydrolysates and LC-HRMS can provide information about their structure via the elemental composition and fragmentation pathways. By contrasting these data to spectroscopic techniques such as 1H and 31P NMR, structural elucidation of decontamination products is possible as well as the determination of the kinetics of the decontamination process itself. The literature review contains a summary of all published instrumental methods with which Novichok nerve agents, degradation products, biomarkers and adducts have been analyzed and the efficacy of those methods. In the experimental research, Novichok nerve agent A-234 was decontaminated via six different decontaminants and analyzed by LC-MS/MS to identify the mass spectra of the degradation products of each, followed by LC-HRMS analysis to determine the elemental composition and fragmentation patterns of the degradation products. The A-234 rate of hydrolysis kinetics were measured by 1H and 31P NMR spectroscopy in three of the decontaminants and when possible, two dimensional analysis was used to correlate the structural data from the chromatographic analysis. Lastly, the A-234 hydrolysate was derivatized via TMSDAM methylation for GC-MS/MS analysis after testing with two silylating and three methylating agents. Decontamination of A-234 was successful within 48 hours with three decontamination agents and complete hydrolysis was observed within 5 hours with an oxidizer-containing quaternary salt based decontamination agent.
  • Fu, Shu Yi Vicky (2022)
    Biomacromolecules are large particles found in biological fluids. The upregulations and downregulation of some biomacromolecules, such as extracellular vesicles (EVs) have been linked to cancer and infectious diseases. The study of these biological particles can help us in understanding the progression of those conditions better. Furthermore, studying naturally occurring biological molecules, e.g., immunoglobulin G (IgG), DNA, nucleic acids and glycoproteins can help us to gain more insight to important biological processes in the human body. The first part of this thesis is a literature review of monolithic columns in the separation of large biological molecules in liquid chromatographic and capillary electrochromatographic applications. Columns, including novel monolithic stationary phases, also known as monoliths, have been developed to counter some of the problems associated with the traditionally used packed beds in separation science. Monoliths have a unique structure of interconnecting porous channels, which allows faster separation with better resolution, reproducibility and mass transfer characteristics compared to packed beds. Organic-based polymer monoliths are the most widely used monolithic materials in biological applications, but the use of inorganic-based silica monoliths and hybrid monoliths have grown in the last couple of decades. Monolithic columns are versatile and they can be utilized in several chromatographic techniques, such as reversed-phase chromatography, affinity chromatography, ion-exchange chromatography, capillary electrochromatography and mixed-mode chromatography. Due to the growing interest, miniaturized monoliths e.g. in microfluidic devices, small capillaries and microarrays have been exploited to allow faster separation using sample volumes even as low as a few femtolitres. For higher sample throughput, monoliths in the format of 96-well plates, tips, sheets and disks have been introduced, especially for sample pre-treatment purposes. In the experimental part, affinity monolithic chromatography was employed for the isolation of lipoproteins and EVs in both exomere and exosome size range. The main function of EVs is transporting signal molecules from cell-to-cell to maintain homeostasis of the body. Low-density lipoprotein (LDL), very-low-density lipoprotein and chylomicrons are lipoproteins that transport different lipids in the human blood stream. The study of these particles is important because lipoproteins and especially LDL have been associated with atherosclerotic cardiovascular diseases. The experimental part of this thesis is focused on studying the feasibility of Convective Interaction Media (CIM) monoliths in disk (1.3 µm pores, 0.34 ml) and 96-well plate (2.1 µm pores, 0.1 ml) formats in purifying nanosized biomacromolecules from human plasma. The preparation of the affinity monoliths and the isolation of particles in the disk format was conducted following existing protocols and methods, which were modified for the monolithic 96-well plate. Six different monoclonal antibodies (mAbs), anti-CD9, anti-CD34, anti-CD61, anti-CD63, anti-CD81 and anti-CD82 were immobilized on the monolithic supports to target EVs. Anti-apoB100 mAb was used in targeting apolipoprotein B100 present on the surface of apoB100-containing lipoproteins. The isolation in the disk format was done using an on-line immunoaffinity chromatography – asymmetric flow field-flow fractionation method connected to ultraviolet, dynamic light scattering and diode array detectors. To compare the two different formats with different pore sizes in lipoprotein and EV isolation, the immobilization protocol and isolation conditions were optimized for the monolithic well plate. The isolation on the monolithic 96-well plate was done within 20 minutes, and the operation consumed three times less sample and buffer than in the disk format. Both monolithic formats were suitable for LDL isolation and the disks could also be used in EV isolation and separation. However, due to the larger pore size, EVs were found to be unstable in the monolithic wells.
  • Puumi, Jukka (2021)
    An overview on utilization of dual nickel/photocatalyst protocols to conduct aryl-heteroatom cross-coupling reactions is presented. Basic concepts of photocatalysis, including different relaxation pathways, the difference of singlet and triplet states, and parameters used to predict reactivity are first disclosed. The general components used in dual nickel/photocatalyst protocols are presented followed by the discussion on reactivity trends. The reactivity trends are compared with other common aryl-heteroatom cross-coupling protocols (Buchwald-Hartwig-, Ullmann- and Chan-Lam couplings) illustrating the general advantages and disadvantages of each cross-coupling method. The scope of different dual nickel/photocatalyst protocols are then explored, concentrating on cross-coupling of amines, alcohols/thiols and carboxylic acids. The developments in mechanistic understanding on the dual nickel/photocatalyst aryl-heteroatom cross-couplings in recent years are reviewed. It is concluded that photocatalytic single electron transfer-based cycles, proposed for a number of coupling protocols, are very unlikely to take place. It is made clear that, based on the current knowledge, two principle mechanism are reasonable: energy transfer or thermal Ni(I)/Ni(III) cycles. Problems concerning energy transfer mechanisms are also discussed. Finally, applicability of dual nickel/photocatalyst aryl-heteroatom cross-coupling for industrially significant transformations is briefly discussed.
  • Känsäkoski, Silja (2023)
    Lignin is an abundant aromatic polymer found in renewable biomass sources such as trees and grasses. Lignin is largely formed as a side product in paper and pulping industries, and recent research has been trying to valorize it for value-added products such as fuels and chemicals through catalytic depolymerization. This thesis work consists of two parts: a literature review on lignin and it depolymerization methods and the experimental part where lignin is depolymerized, and the products are analyzed. In the literature review an overview of lignin, its structure and different sources is given. Furthermore, different extraction methods of lignin from the biomass source are reviewed, and more specifically the organosolv process is highlighted. Different products formed in the depolymerization of lignin are presented along with their applications. Depolymerization methods including pyrolysis, oxidative depolymerization, solvolysis and reductive depolymerization are reviewed. Finally, different metal catalysts, with a focus on molybdenum-based ones, used in reductive lignin depolymerization are presented. In the experimental part two molybdenum phosphide catalysts are synthesized and characterized. They are used in the depolymerization of fraunhoferk130 and GVL lignin using ethanolysis in a batch or autoclave reactor. The mass balance of product fractions and monophenol yields are presented. Monophenol yields ranged from 3.5 wt.% to 22.8 wt.%. Additional hydrogen pressure suppresses repolymerization and char formation but has negative impact on monomer yields so the true role of hydrogen gas remains unclear. Increasing reaction temperature led to smaller molar mass but higher char formation. The different catalysts used are compared in the results with the help of the monomer yields, mass balance and molar masses. Overall, the molybdenum-based catalysts showed promise as monomer yields were in lieu of those found in literature and can be synthesized with lower costs than noble metal catalysts.
  • Gabbouj, Selma (2022)
    Chemical attribution encompasses the detection and characterization of compounds of interest to find signature impurity, isotopic, and elemental profiles, which can be used to link illegal material to specific manufacturers, stocks, precursors, synthetic routes, or geographical locations. Explosives have been increasingly used for criminal purposes world-wide due to the availability of explosive material, precursors, and synthesis instructions. Nitrate ester, nitramine, and nitroaromatic military explosives as well as homemade organic peroxides are examples from over 250 explosive materials listed in the 2020 Federal Register of the US Bureau of Alcohol, Tobacco, Firearms, and Explosives. The first part of the thesis is a literature review, which aims to 1) present published mass spectrometric (MS) and liquid chromatographic (LC) detection methods for explosives and 2) explore chemical attribution studies of explosives and related compounds, such as illicit drugs and chemical warfare agents. The second part presents the experimental research carried out at the Finnish Institute for Verification of the Chemical Weapons Convention (VERIFIN), which aims to 3) develop an analysis method for multiclass explosives using liquid chromatography-high resolution mass spectrometry (LC-HRMS) and 4) perform chemical attribution of the nitrate ester explosive pentaerythritol tetranitrate (PETN) from different sources by isotopic and impurity profiling. Multiclass explosives detection required optimization of MS parameters, such as lower ion transfer tube and vaporizer temperatures and negative ion detection mode, as well as introduction of additives into LC eluents to promote adduct formation. PETN, 1,3,5-trinitro-1,3,5-triazinane (RDX), 1,3,5,7-tetranitro- 1,3,5,7-tetrazocane (HMX), 2,4,6-trinitrophenyl-methylnitramine (tetryl), 2-amino-4,6-dinitrotoluene (2- ADNT), and 4-amino-2,6-dinitrotoluene (4-ADNT) were detected from a mixture as nitrate adducts. Optimal parameters for the isotopic profiling of PETN were found to be 500 000 resolution, 2E4 (5 %) automatic gain control (AGC) target, and 50 ms injection time. Student’s t-tests revealed statistically significant differences between oxygen isotope ratio (18O/16O) values of PETN from two different sources. However, lack of repeatability of the isotope ratio results was an issue. 7 different methods were tested for the impurity profiling of PETN. Samples were rather pure but clear differences in the high mass range (m/z 600–900) impurity profiles of the two types of PETN were discovered, leading to the conclusion that they are indeed from different sources. Tentative structures of PETN homologue derivatives were assigned to the impurities using MS2 fragmentation and literature. Based on the results of this work, LC-HRMS is suitable for impurity analysis even for pure samples, but not very efficient or practical for analyzing isotope ratios.
  • Lempinen, Antti (2023)
    Development of machine learning models for reaction design has garnered growing interest. Notably, the benefits of predictive models include the elimination of trial and error in selecting suitable reaction conditions. In addition, mechanistic insight may be gained to help rational catalyst design. The aim of this study is to develop modeling and parametrization method for transition metal complexes which would enable the combined parametrization of mono- and bidentate ligands for the first time. Performance of novel parametrization method is demonstrated through a ligand classification model for Suzuki–Miyaura reaction. In this literature review, an overview of the computational catalyst modeling and performance prediction is presented. The history of physical and computational chemistry is reviewed, ranging from early structure-property relationships and linear models to modern physical organic density functional theory (DFT) parameters and machine learning models. The necessary theoretical background for reaction modeling is presented in terms of transition state theory, which can be used to model selectivity or reaction rate. Additionally, the reaction yield is discussed as typical performance score for reaction modeling. Furthermore, the initial structures of typical transition metal complexes used for modeling are presented, along with the methods employed for structure optimization and ligand parametrization. By utilizing this background, the evolution of modeling methods from linear free energy relationships to machine learning is discussed. Additionally, modern classification methods for catalyst design are reviewed. Finally, the mechanistic details of Suzuki–Miyaura reaction are explored to justify the modeling methodologies in the experimental part. In the experimental study, a novel method to combine parametrization for mono- and bidentate ligands was successfully invented. As a proof of concept, performance classification of ligands for Suzuki– Miyaura reaction was conducted. Suzuki–Miyaura reaction was chosen as the model reaction due to wide data availability. Initial transition metal complexes were built according to ligation state of nickel. The initial structures always included two carbonyl ligands and either one bidentate ligand, or two monodentate ligands, or one bulky monodentate ligand. The structures were optimized with semiempirical quantum mechanical method xTB and parametrized using a newly developed in-house parametrization method. Calculated parameters include global and local steric and electronic descriptors, and local geometric descriptors. Classification models were built with selected training data. Models were used to predict the performance of new ligands. Successful results were achieved, and ligands that provided better yields were identified. In addition, it was discovered that model reaction proceeds without the presence of phosphine ligand if superbase is used as a base. Nitrogen-containing bases were screened, additional active superbases were found, and correlating descriptor with activity was detected. Based on results, more active superbases were designed.
  • Tuna, Yasemin (2023)
    Nuclear power plant decommissioning is a difficult process that combines industrial decommissioning techniques, radiation safety standards, and legal requirements for the final disposal of nuclear waste. The goal of nuclear decommissioning is to completely purge the plant of all radioactive material so that it can be released from regulatory oversight. The range of corrosion products generated on the steel surface are known to have a significant impact on the corrosion process of steel. Corrosion products have a complicated structure. The corrosion products are created when metallic components, mostly iron, react with oxygen and water that are drawn from the atmosphere, and their structure is then significantly influenced by environmental factors. Quantitative characterisation of the atomic scale structure of corrosion products is critically needed for identifying the corrosion products reliably. This thesis provides the characterization process of corrosion products formed on the steel surfaces and this process was executed with the help of XRD (X-ray Diffraction), SEM/EDS Scanning Electron Microscope/ Energy Dispersive Spectrometry, and Raman spectroscopy. Within the scope of this project, besides characterization of steel samples, Loviisa ground water and synthetic water samples which have been in a long-term contact with activated steel samples were also examined. Separation processes was carried out for determining Fe-55 and Ni-63 in the waters and the presence of Co-60 was removed from the samples before the activity determination of Fe-55 and Ni-63 by LSC (Liquid Scintillation Counting). This master's thesis has been carried out in connection with the DEMONI project, which has been a coordinated project of VTT and the University of Helsinki (KYT2022 Research Program). The outcome of the thesis will benefit possible decommissioning and disposal strategies for the nuclear power plant's reactor pressure vessels.
  • Ruotsalainen, Sini (2022)
    The literature review of this thesis presents the most utilized sample preparation and analysis methods for determination of trace elements from refinery feedstocks and end products during the last decade. The advantages and disadvantages of used methods and trends are presented. The challenges associated especially on silicon determination are discussed and possible solutions provided by publications are highlighted. The experimental part of this thesis is conducted in Neste’s Research and Development unit in Porvoo. The experimental part includes method development, study of siloxane compounds behavior and method validation for various sample matrices. The method development was performed by introduction of peristaltic pump to inductively coupled plasma- mass spectrometer (ICP-MS) sample introduction for two different methods (ASTM D8110M, NM 534) to replace previously used free aspiration method. The study of behavior of volatile siloxane compounds in different sample matrices including liquified waste plastics (LWP), and determination of these compounds was done with ICP-MS. The studied siloxanes showed great challenges due to their high volatility with the chosen methods. The method (ASTM D8110M, NM534) validation for different sample matrices were also done with ICP-MS. The validated matrices included several renewable matrices such as liquified waste plastics, fatty acids and other liquified waste samples and heavy fossil distillates. Repeatabilities of silicon concentration of sample as such and as spiked in intra- and inter-day, and spiked recoveries played an important role for method validation.
  • Åström, Hugo (2022)
    I discuss recent work regarding electronic structure calculations on quantum computers. I introduce quantum computing and electronic structure theory, and then discuss different mappings from electrons and excitation operators, to qubits and unitary operators, mainly Jordan–Wigner and Bravyi–Kitaev. I discuss adiabatic quantum computing in connection to state preparation on quantum computers. I introduce the most important algorithms in the field, namely, quantum phase estimation (QPE) and variational quantum eigensolver (VQE). I also mention recent modifications and improvements to these algorithms. Then I take a detour to discuss noise and quantum operations, a model for understanding how quantum computations fail because of noise from the environment. Because of this noise, quantum simulators have risen as a tool for understanding quantum computers and I have used such simulators to do electronic structure calculations on small atoms. The algorithm I have used, QPE, yields the exact result within the employed basis. As a basis I use numerical orbitals, which are very robust due to their flexibility.
  • Vierinen, Taavi (2023)
    A geopolymer waste form containing gasified ion exchange resin loaded with stable analogues of radionuclides (e.g., Sr, Co, Ni, Cr, Cs) was studied using semi-dynamic batch leaching experiments. The experiments were conducted for 180 days using an alkaline groundwater simulant in a glove box with controlled N2 atmosphere with < 10 ppm CO2 and O2. The experiments were conducted to investigate the leaching behavior of the geopolymer in conditions relevant to a low- and intermediate-level waste repository. The leaching results of the geopolymers showed leaching of cesium, sodium, aluminum, and silicon from the geopolymer, while potassium and calcium in the leachant sorbed to the geopolymer. The leaching and sorption rates were at their highest for the first 28 days of the experiment, before slowing down to a steady state which were maintained until the end of the experiment. This suggests that the geopolymers immobilized the waste analogues effectively with exception of cesium which had leached by 55 wt% of the initial fraction by day 180. The leaching indices of sodium, aluminum, silicon, and cesium were determined as: 9.9 ± 0.38, 10.1 ± 0.47, 10.5 ± 0.40, and 9.1 ± 0.30 respectively. The leaching indices are well above 6, which is considered a minimum value for WAC of cementitious waste forms by USNRC. The solid phase analysis of the geopolymer samples showed both presence of calcium rich secondary phases and increasing calcium concentration in the bulk matrix on the leachant contact surface of the geopolymer. It was concluded that the secondary phases consisted of CaCO3 minerals.
  • Mustaniemi, Tuomas (2022)
    The thesis gives an overview of indoor air pollution sources, health effects, and the detection of the fungal markers in indoor environment. In the experimental part of the thesis, solid phase extraction-liquid chromatography-tandem mass spectrometry method was developed for the quantitative analysis of 23 fungal secondary metabolites. The method was used to analyze the condensate water in indoor air from two sick houses in the Southern part of Finland. Furthermore, the practice was used to find other possible fungal marker compounds. The concerns of the indoor air pollution have been steadily increasing for the past couple decades since the prevalence of the irritative symptoms, such as skin, eye and respiratory track problems, that have been increasing without any clear reasoning. These symptoms are therefore being referred as building related symptoms since no other functionality have been discovered to be responsible for those. The general sources that could be linked to the cause of these symptoms are comfort parameters, material and burning related sources, and microbial metabolism products. From the microbes, the fungal species exhibit biggest concerns related to the indoor air quality since the growth of the fungus in the suitable conditions can lead to sizeable emissions of the particles and secondary metabolites which might be toxic, irritating or otherwise unhealthy. The traditional way of detecting the fungal contamination has required highly trained professional who investigates the interiors of the suspected contaminated house with the help of a moisture detector. When the contaminated spot is detected, the expert would conduct a visual inspection, and take a sample of the fungal growth for the microscopic analysis. Since then, methods focusing on the detection of the fungal particles and compounds have been developed. These include the collection of the bioaerosols and the detection of the volatile organic compounds originating from the fungal metabolism. However, there are challenges and limitations on these methods such as dependencies on time, low concentrations, and other pollution sources having similar chemical profiles than the fungal sources. Therefore, diverse ways to analyze the chemical profile of the sick houses is needed. Consequently, in the experimental part of this thesis, the method was developed to analyze fungal secondary metabolites from the condensate of the indoor air. The investigation consisted of the two fungal contaminated sick houses and from the one reference laboratory air sample. The results revealed twelve compounds to be elevated in the indoor air compared to the outdoor air and seven of these compounds were not detected in the reference sample. From these seven compounds, the studied amino acids and caffeine were the most promising fungal marker compounds since these compounds had consistently larger concentrations indoors than outdoors. Furthermore, the precursor ion scan revealed nine more potential marker compounds.
  • Pettilä, Lauri (2023)
    Radiocesiumin erotusmateriaaleille on jatkuvaa kysyntää maailmanlaajuisesti ydinjätteen käsittelyyn ja ympäristön dekontaminointiin liittyen. Tämän takia tarvitaan edelleen lisää tutkimusta tehokkaampien ja selektiivisempien cesiumadsorbenttien kehittämiseksi. Lisäksi näiden adsorbenttien regenerointitapojen kehittäminen on oleellinen tapa vähentää muodostuvan kiinteän radioaktiivisen jätteen määrää. Metalliheksasyanoferraatit ovat paljon käytettyjä ja tutkittuja materiaaleja cesiumin erotukseen ja yhdistettynä sähköisesti ohjattuun ioninvaihtoon niistä voidaan valmistaa tehokkaita, selektiivisiä, kestäviä ja uudelleenkäytettäviä ioninvaihtimia. Työn tavoitteena oli valmistaa tällainen sähköllä regeneroitava ja selektiivinen grafeeniaerogeelistä ja heksasyanoferraatista koostuva komposiitti-ioninvaihdin cesiumin erotukseen. Työn kokeellisessa osassa valmistettiin onnistuneesti erilaisia kylmäkuivattuja aerogeelejä eli kryogeelejä, joiden korkea hapettuneisuus teki niistä joustavia ja kestäviä ilmassa. Toisaalta vastaavat askorbiinihapolla pelkistetyt kryogeelit olivat kovia ja soveltuivat mekaanisilta ominaisuuksiltaan paremmin käytettäväksi adsorbenttina vesiliuoksissa. Yksi merkittävimmistä havainnoista oli sentrifugoinnin tärkeys grafeenioksidisuspension homogenisoinnin kannalta, jotta saatiin valmistettua yhtenäinen tuote. Valmistettujen grafeenikryogeelien ja indiumtinaoksidin pinnalle saostettiin nikkeliheksasyanoferraattia, jonka hapettumis-pelkistymisreaktioita mitattiin onnistuneesti syklisellä voltammetrialla. Näiden komposiitti-ioninvaihtimien avulla radiocesium voitiin erottaa vesiliuoksesta lähes kvantitatiivisesti, mutta kiinnittyneestä cesiumista saatiin eluoitua tämän jälkeen jännitteen avulla vain noin 10 %. Tuotteita karakterisoitiin myös jauheröntgendiffraktiolla ja energiadispersiivisellä röntgenspektroskopialla.
  • Rantanen, Noora-Kaisa (2022)
    In chemical forensics inorganic analysis is for example used to detect traces of explosives and drugs, to find residues of firearms, and as aid when searching for hidden burial sites. Forensic investigators also utilise inorganic information in chemical source attribution or fingerprinting, which seeks to identify chemical profiles of inorganic and/or organic compounds and elements that can provide information on the origin of the sample, how it has been produced and using which raw-materials. As the chemical profiles typically contain information for several compounds, comparison of profiles have to be analysed by multivariate statistical tools such as principal component analysis (PCA), hierarchical cluster analysis (HCA) and linear discriminant analysis (LDA). In this work the applicability of inorganic source fingerprinting on soil samples was investigated. For this an extraction procedure and an ion chromatographic (IC) method for the determination of F–, Cl–, Br–, NO3–, PO43–, SO42– and AsO43– in soil were developed and validated. Extraction of anions was done by microwave assisted solvent extraction, with good recoveries (86.15 % – 115.23 %) for nearly all recovery samples. The recovery of F– from soil was 174.77 %, due to enhanced extraction efficiency caused by the high extraction temperature. AsO43– could not be quantified due to low extractability and interfering matrix components. Development of a method for elemental analysis of soil samples by inductively coupled plasma mass spectrometry (ICP-MS) was also attempted. Complete dissolution was not achieved with microwave assisted acid digestion mainly because of the large particle size of the soils analysed. Samples were analysed for As, Co, Cr, Cu, Fe, Mn, Mo, Ni, V and Zn, but Ni could not be quantified from any of the samples because of the high detection limit caused by contamination of samples. Due to contamination and incomplete dissolution the variation in the results were large, leading to a large uncertainty for the results. Analysis of variance (ANOVA) revealed that there is a significant (α = 0.05) difference in the concentrations of all analytes but Mo and V between the samples. Two step PCA and LDA were performed on tha anion and elemental results separately. Better clustering of sample results were typically got with LDA than with PCA. LDA on the anion results was able to discriminate all samples while only four out of seven samples were identified by PCA. The large variation in the data meant that only the reference soil could be identified when all elemental concentrations were included. Removal of outliers from the data lead to identification of all samples by both PCA and LDA. This work showed that samples can be identified by their inorganic profiles, but large variations in the measured concentrations will make the discrimination by multivariate statistics difficult. Further work should focus on improving the separation of the IC method and on decreasing the variation in the data by decreasing sample heterogeneity and contamination during the sample preparation.
  • Pöllänen, Topias (2023)
    Bioorthogonal chemistry and click chemistry have gained tremendous attention during the past few years. They do not refer to a single reaction but to a class of reactions that take inspiration from nature. Click reactions are driven by a strong thermodynamic driving force and therefore they proceed via well-controlled and consistent reaction pathways. Click reactions afford specific products in high yields with negligible by-products. Bioorthogonal chemistry builds on the boundaries set by click chemistry. Bioorthogonal reactions can occur within a living system without interacting or interfering with the natural biological processes therefore both the reactants and the products must be inert and stable under physiological conditions. Bioorthogonal reactions have allowed the real-time study of several biomolecules such as glycans, lipids, nucleic acids, and proteins within living systems without cytotoxicity. In the literature section of the thesis, the most important physical properties of both the isonitrile and chlorooxime are introduced and the most important bioorthogonal reactions for both functionalities are highlighted. The bioorthogonal isonitrile-chlorooxime ligation is discussed in more detail and an example is given of how the ligation can be used to label the cell membrane of living cells with fluorescent moieties. To install a moiety on the cell membrane it must first be modified with small non-natural chemical functionalities also called “chemical reporters.” which can be installed with metabolic oligosaccharide engineering (MOE) using monosaccharide analogues. After installation of the “chemical reporters” onto the cell surface, molecules containing the corresponding bioorthogonal counterpart can be attached to the cell membrane. Lastly, the sulfur(VI) fluoride exchange (SuFEx) click chemistry is discussed. Traditionally, SuFEx click chemistry has been used in organic chemistry to build inorganic connecting bridges between two carbon centres. More recently, SuFEx chemistry has found utility in the radiosynthesis of fluorine-18 containing [18F]sulfonyl fluorides and [18F]fluorosulfates. Fluorine-18 is one of the most commonly used and important positron emitters utilized in radiopharmaceutical chemistry and positron emission tomography (PET). The experimental section of the thesis presents the synthesis routes of the bioorthogonal reaction partners, a peracetylated isonitrilepropanoylmannosamine (Ac4ManNC) and an aryl fluorosulfate chlorooxime. The research hypothesis of the study was that the isonitrile of the Ac4ManNC could be installed onto the cell surface of living Jurkat cells (human T lymphoblast) with MOE. Afterwards, the fluorine-18 labelled aryl [18F]fluorosulfate chlorooxime could have been attached to the cell surface from the isonitrile with the bioorthogonal isonitrile-chlorooxime ligation. This cell surface labelling method could have then been used in the future to research and develop cell therapy treatments by utilizing PET imaging.