Digitala Vetenskapliga Arkivet - Academic Archive On-line
Not a member yet
734120 research outputs found
Sort by
Exploring the Impact of Environmental Chemical Pollutants in Alzheimer's Disease: Insights from SH-SY5Y Cell Line Studies and Literature Review on Blood-Brain Barrier Involvement
No full textTo restrict transportation to and from the brain, the blood-brain barrier works as a border between the blood system and the brain. It is an important hinder for xenobiotics to reach the brain were molecules’ characteristics, such as lipophilicity can determine the cross over. Alzheimer's disease is a progressive neurodegenerative disease which is connected to old age and gene mutations. However, the cause for the disease has also been linked to environmental risk factors. Environmental pollutants are present in many different matrixes in the environment and can cause adverse health effects to living organisms. In recent years, environmental pollution has been connected to the development of diseases like Alzheimer's disease. The aim of this project was to combine in vitro studies with existing literature to assess the potential effects of environmental pollutants exposure on neuronal cells and their relevance to Alzheimer's disease. For the literature review, Web of Science was used where searches were limited by the occurrence of “chemical name” and “Blood-Brain- Barrier" in the abstract. A typical flow diagram was then used to narrow down the hits to relevant articles, which were then included. The literature review included 17-β-estradiol, Estrone, Erytromycine, Clarithromycin, Sulfamethoxazole, Paracetamol, Ibuprofen, Salbutamol, Oxazepam, Nicotine, α-Hexachlorocyclohexane, Lindane, Perfluorooctanoic acid and Perfluorooctane sulfonic acid. Findings from the literature review included different types of Alzheimer's markers, like tau protein aggregation, Blood-Brain Barrier transporter proteins like, breast cancer resistant protein and P glycoprotein and tight junction protein, such as Claudin-5 and Occludin. Other Blood-Barin barrier related markers, indicating inflammatory responses, permeability and dysfunction were also found. Negative effects which could be linked to Alzheimer's disease by chemicals tested was 17-β-estradiol which reduced breast cancer resistant protein transport. Positive effects relating to Alzheimer's disease was seen for Sulfamethoxazole and Salbutamol which inhibited tau aggregation. In the in vitro experiment, SH-SY5Y cells were exposed to chemicals (17-β-estradiol, Estrone, Erytromycine, Azithromycin, Dinclofenac, Paracetamol, Ibuprofen, Oxadiazon, Triallat, Imidacloprid, Thiacloprid, Thiamethoxam, Clothianidin, Acetamiprid, Mepanipyrim, Cyprodinil, 2,6-ditert-butyl-4-methylphenol and 4methoxycinnamate de 2-ethylhexyle) for 24 h in 1, 10, and 50 µM concentrations, with three replicas for each chemical. The cell viability was tested by the AlamarBlue assay. Based on the in vitro study, a significant effect (P-value=0.039) was seen for the chemical 4methoxycinnamate de 2-ethylhexyle where a metabolic activation increase was seen for the largest concentration (50 µM). Due to the lack of studies focusing on pollutants’ effect on Alzheimer's disease related markers, a large knowledge gap is yet to be filled.
A response to Populism? European Citizenship as a valid political instrument opposing populist challenges
No full textAir pollution and Climate Change
No full textIn order to evaluate the role of air pollution and air pollution control for climate policies, SwedishEnvironmental Protection Agency invited leading experts and scientists, senior administrators andnegotiators, international organisations and industry to an international workshop in Gothenburg, Sweden,19-21 October 2009
Multiscale integrated modeling of the Iron Oxide-Apatite Mineral System in Northern Norrbotten, Sweden
No full textThe subsurface has long supplied raw materials, yet with most giant surface-exposed deposits already discovered, exploration increasingly focuses on deeply buried mineral systems in frontier terrains. Collaborations across and beyond traditional geoscience disciplines are becoming increasingly important as deeper discoveries require multidisciplinary and integrated exploration tools. These multidisciplinary exploration tools aim to integrate the mineral system paradigm with existing geological and geophysical models and interrogate and characterize the spatial and temporal relationships of its components. This doctoral thesis employs geological modeling and integration with existing geophysical models within a multiscale framework to investigate the expression of the iron oxide-apatite mineral system in northern Norrbotten (Sweden). The region is regarded as a major metallogenic province hosting more than 40 iron oxide-apatite (IOA) deposits, including the giant Kiirunavaara deposit. More than a century of mining, exploration, and geological surveying in the area has led to an outstanding repository of geoscientific data, encompassing geological mapping, large drill core archives, and high resolution geophysical dataset, providing a solid foundation for integrated, multiscale modeling of the mineral system. At the deposit scale within the Kiruna mining district, integration of surface and drill-core structural measurements with geotechnical, structural, and lithological logging results in models that highlight how the interplay between ore-parallel and orthogonal structures controls mineralization. Low rock quality designation (RQD) values and coreorientation data systematically indicate weak rock mass at ore contacts, whereas orthogonal conjugate faults accommodated heterogeneous strain across adjacent blocks. Within the district, petrophysical measurements of major stratigraphic units establish diagnostic contrasts but also reveal pronounced intraformational variability controlled by alteration intensity and fabric development. Although stratigraphic formations can be discriminated geophysically, this heterogeneity complicates direct local-scale interpretations. The dataset provides a calibrated petrophysical reference, linking field-based geological observations and measurements with ground and airborne geophysical surveys. At the province scale, an integrated 3D model synthesizing deposit- and district-scale geological models with province- wide lithological and structural models and inversions of magnetic and gravity surveys constrain the crustal architecture of the northern Norrbotten ore province (NNOP; here defined as the area between Gällivare and Kiruna). Mafic-ultramafic intrusions occur as dense, magnetically heterogeneous domains systematically proximal to vertically extensive conductors imaged by magnetotellurics (MT), interpreted as the upper-crustal expression of transcrustal magmatic-hydrothermal conduits. IOA deposits are typically situated along second-order oblique structures that intersect or splay from major shear zones at the margin of dense and magnetic bodies, rather than within the firstorder shear zones themselves or directly coincident with MT conductors. Across deposits and prospects, diagnostic total magnetic intensity (TMI) responses, characterized by steep gradients with localized highs flanked by negative lobes constitute repeatable proximal indicators of IOA mineralization. The magmatic character of the intrusions is further constrained by petrography, whole-rock geochemistry, petrophysical characterization, and SIMS U-Pb zircon and titanite geochronology of mafic to intermediate intrusions. Two intrusive groups are distinguished, a cumulate set marked by olivine-pyroxene-plagioclase-rich assemblages, positive Eu/Eu*, elevated Sr/Yb, high density (>3.0 g/cm3) and variable magnetic susceptibilities, and another melt-proxy set of non-cumulates further subdivided into calc-alkaline and tholeiitic lineages with lower densities (2.84-3.00 g/cm3) and more uniform susceptibilities. Cumulate intrusions coincide with MT conductors, gravity highs, and concentric magnetic anomalies, supporting their interpretation as upper-crustal expressions of a deeper magmatic feeder zone. Their association with IOA deposits and complementary geochemical signatures indicates that early Svecokarelian intrusions supplied heat and likely magmatic input to the mineral system. Zircon U-Pb data place both cumulate and non-cumulate intrusions within the early Svecokarelian magmatic pulse, while titanite U-Pb results record both near-magmatic crystallization and later tectonothermal resetting events. At multiple scales, the analyses converge to show that IOA mineral systems in northern Norrbotten emerged from a dynamic interplay of magmatism, structural, and subsequent tectonothermal processes, recorded from deposit scale to province-wide crustal architecture. Embedding field-based geological observations and supporting analysis, mineral system concepts, and geophysical inversion results into integrated multiscale modeling, this thesis establishes a systematic link across scales and a coherent basis for interrogating the spatial and temporal organization of mineral system components. While the approach inevitably simplifies the complexity of a long-lived Paleoproterozoic terrain, it underscores the value of integrated geological modeling in reconciling diverse datasets into consistent frameworks. In doing so, the study refines current interpretations of IOA mineralization in northern Norrbotten and contributes to a more rigorous geological understanding of this major metallogenic province
Designed Fluorine-Free Ionic Liquid-Based Electrolytes for Next-Generation Supercapacitors
No full textEnergy storage is a crucial element of green transition that drives the growth of technology, and its importance is progressively increasing. The expanding demand for reliable power sources necessitates the development of innovative methods to balance energy production and consumption. Among energy storage devices (ESDs), supercapacitors are considered superior due to their outstanding power, swift charging, long lifespan, and sustainability. The ion mobilities in supercapacitors are mainly determined by the electrolyte, which further influences the charge transfer, voltage, and total power holding capacity. Due to the critical role of electrolytes in supercapacitors, several advancements are made in the design of the electrolyte to increase voltage strength and energy density. The electrolytes for supercapacitors include aqueous-based, organic solvent-based, ionic liquids (ILs) and solid-state electrolytes. Among them, IL-based electrolytes are the most suitable electrolytes due to their combination of beneficial physical and electrochemical properties. However, more than 95 % of the IL-based electrolytes are heavily based on fluorinated compounds, which are creating serious problems not only in the synthesis and implementation levels but also at the recycling stage. There is an urge to develop fluorine-free and non-flammable functional electrolytes for enabling next-generation supercapacitors. This thesis is an attempt to elevate energy storage technology by providing economically and environmentally efficient solutions in terms of fluorine-free IL-based electrolytes for next-generation supercapacitors. The main aim is to design and identify Fluorine-Free Ionic Liquids (FFILs) as electrolytes for efficient next-generation supercapacitors. The first part of this thesis (Paper I) is focused on the synthesis, physical characterization, and transport as well as electrochemical properties of a novel class of ten FFILs derived from biomass. The biomass derived anions such as furan-2-carboxylate [FuA] and tetrahydrofuran-2-carboxylate [HFuA] are coupled to a range of nitrogen heterocyclic cations to create the FFILs, for which the nature of cation controlled their properties. The second part (Paper II) is dedicated to the synthesis and characterization of dialkylphosphate-based FFILs, that offered high thermal decomposition and low glass transition temperatures, and high ionic conductivities as well as high electrochemical stabilities. Further, their performance as electrolytes in symmetric supercapacitors showed high coulombic efficiency and capacity retention even after long charge-discharge cycles. The part three (Paper III) presents the synthesis, physical and electrochemical characterization of two novel fluorine-free zinc salts and their electrolytes derived from artificial sweeteners. The three-component zinc electrolytes are composed of either zinc saccharinate (Zn(Sac)2 or zinc acesulfamate Zn(Asf)2 salt, tetrabutylphosphonium saccharinate [P4444][Sac] IL, and γ-valarolactone (VL). These electrolytes demonstrated significantly long cycle life in Zn||Zn symmetric cells, while maintaining high capacity retention after extended cycles at a lower current density in an asymmetric hybrid supercapacitors (Zn||Ac)
Continuous Change Through Professionalization : Fragmentation, Digitalization and Sustainabilization in Construction from the Perspective of Swedish Architects
No full textIn this thesis I discuss how change in the construction sector affects and is affected by individuals’ perceptions and actions. Previous research has shown that behavioral change at the individual level is needed to achieve change at the macro level. This thesis therefore highlights continuous change from a professional perspective. Specifically, it focuses on the change phenomena of fragmentation, digitalization, and sustainabilization,and is thus connected to ongoing debates in research on how to ‘manage fragmentation’ or ‘achieve digitalization and sustainability’. Some previous studies in these areas rely on assumptions that are problematized and presented in a new light in this thesis. By focusing on professionalization, the thesis unveils the complex and reciprocal relationship between these change phenomena. Previous research has rarely analyzed fragmentation, digitalization, and sustainabilization together, especially from a professionalization perspective. The thesis therefore fills a research gap while simultaneously addressing highly relevant issues that are discussed daily at individual, organizational, and sectoral levels.The thesis focuses particularly on the architectural profession. This is partly because increasing fragmentation has significantly altered the role of architects in construction projects, not least because they are seen as central actors in driving digitalization and sustainability efforts. However, the focus on architects is also motivated by their under-representation in existing research. The theoretical points of departure are institutional theory (with a focus on agency) as well as sociological concepts related to professional identity and professional roles.Methodologically, the thesis builds on interpretive qualitative studies at the individual level, where focus groups, interviews, and shadowing have been used. In total, 41 architects participated in these studies, sharing their perceptions of themselves and their everyday practices in construction projects.By focusing on the professionalization underpinning larger structural changes—fragmentation, digitalization, and the sustainability transition—the thesis explores new perspectives. It discusses: the nature of fragmentation (from static to dynamic); the impact of fragmentation on digital and sustainability change (from barrier to enabler); how fragmentation can be managed (from the architect’s perspective); professional roles (from fixed to flexible); the profession (from uniformity to diversity); agency (from “cultural dopes” via entrepreneurs to implicit agents); professional identity (from partly unexplored to a central source of institutional change); as well as how digitalization and the sustainability transition can be understood as institutional movements.The thesis contributes empirically to theoretical fields such as research on professions and institutional theory (especially concerning agency and institutional work). It also offers new perspectives on long-standing challenges within construction research. For example, the results show the significance of professional identity for achieving institutional change in the construction sector, as well as how professionals cope with, navigate, and adapt to continuous change—insights that are central for understanding and practically managing fragmentation.Finally, with this thesis I hope to contribute to a renewed discussion about the development and future of the architectural profession, as well as the need to consider individual experiences to understand larger structural phenomena
Behandling av partiklar och metaller från dagvatten : Laboratoriemetoder och utvärdering i fält
No full textSuspended solids and metals are recognized as key pollutants in stormwater runoff. Thus, stormwater treatment systems have become increasingly vital components of urban infrastructure, playing a key role in reducing pollutant loads entering receiving water bodies. This thesis focuses on evaluating the treatment of solids and metals in stormwater systems, through both controlled laboratory experiments and field-based assessments. Synthetic stormwater is widely used as a substitute for real runoff in both laboratory and field experiments. Its main advantages are the ability to control influent quality and quantity, as well as to improve the repeatability of experiments. However, no standardized formulation currently exists. A critical review which was conducted to evaluate the use of synthetic stormwater in experimental stormwater research revealed substantial variation among studies. Based on these findings, a narrower set of pollutant concentration ranges was suggested to enhance the comparability, repeatability, and reproducibility of future experiments. The experiments evaluating design parameters of a suggested Bottom Grid Structure demonstrated that hydraulic modifications of settling areas in the stormwater treatment systems could enhance sedimentation, though the results were not directly scalable to field conditions. Among the variable factors in the experiment, inclined cell walls of the Bottom Grid Structure had the strongest effect, increasing sedimentation by up to 22% compared to control runs. Column studies showed peat and bark to be the most effective filter materials for dissolved Zn removal, although the use of peat is associated with significant drawbacks regarding other pollutants and uncertainties about its long-term performance. Evaluated zeolite filter system treating copper roof runoff achieved high removal of Cu (49–85%) and Zn (48–94%) but exhibited declining performance over time. A field study examining the performance of two EcoVault facilities revealed relatively low TSS removal (40–46%), substantially below both previous EcoVault studies and manufacturer claims. Dissolved metals were inadequately removed, likely due to elevated hydraulic loading rates and progressive filter clogging. Sedimentation was identified as the dominant treatment mechanism, while the zeolite filter cassettes provided negligible additional metal removal. The field experiments underscored the importance of site-specific design of stormwater treatment systems, especially in cases where the influent is dominated by dissolved metals. Despite their limited performance, underground treatment systems remain a practical solution in densely built urban environments where surface space is constrained. However, targeted design improvements are essential to enhance treatment efficiency. Furthermore, comparisons with commonly used models for the prediction of the performance of stormwater treatment systems revealed that actual removal rates were approximately 50% lower than estimated values, highlighting the need for additional field-based data to improve model calibration and support the development of more reliable and context-sensitive stormwater treatment strategies
Assessment of Waveform Distortion Interactions in Electric Railway Power Systems
No full textRailway electrified systems are one of the most popular and essential forms of transportation globally, and the performance of those systems impacts society. The electric railway power systems (ERPS) comprehend the infrastructure and apparatus that aims to deliver power for the rolling stocks in different types of railway transportation. Due to the broad application of static power electronics, ERPS is characterized by several sources of waveform distortion. Waveform distortion is a critical power quality (PQ) issue and a challenge to managing electromagnetic compatibility (EMC) in railway systems. It englobes harmonics (disturbances synchronous with the fundamental power frequency up to 2 kHz), interharmonics (disturbances asynchronous with the fundamental power frequency up to 2 kHz), and supraharmonics (synchronous and asynchronous disturbances between 2 and 150 kHz). The ERPS has several system complexities that should be taken into consideration when assessing waveform distortion related to the characteristics of the phenomena: extensive distribution system with intricate circuit arrangements and moving single-phase loads; multiple voltage levels and electromagnetic environments, including railway grid and subsystems, as well as public grid; waveform distortion has time-varying behavior dependent on operating states of rolling stock, traffic plan, grid balancing, and spatial position of the vehicles; a mix between traditional equipment or infrastructure and population of new power electronic conversion stages with a lack of guidelines and standardization; and variety of waveform distortion sources and signatures. The objective of this research is to gain knowledge and a better understanding of waveform distortion, including not only harmonics but also interharmonics and supraharmonics in railways systems, to characterize emission sources, propagation, the impact of the operation on time-varying behaviors in several scales, interaction among systems and subsystems, and adverse effects. The focus of the work is alternating current (AC) electrified railways, with a deeper assessment of, but not limited to, the railway system solution of Sweden (15 kV 16 ⅔ Hz). The development and scope of this work provide a comprehensive literature review of waveform distortion assessment for electrical railway power systems and build up a framework for future contributions, characterization of waveform distortion for electrical railway power systems using measurements, conduct detailed measurements on waveform distortion in a traction converter station, modeling waveform distortion propagation for ERPS considering complexities of the system, application of unsupervised deep learning (DL) methods to find patterns in waveform distortion data and investigation of the impacts related with those issues. The research contributions from those defined scopes are summarized below. · Identification of the challenges of waveform distortion assessment in ERPS and categorizing the available literature to address some of those challenges. · Characterization and screening of the waveform distortion time-varying dependencies in different time scales. · Providing a methodology for assessing time-varying waveform distortion in railway systems, adapting traditional methodologies, advanced statistical analysis, and machine learning approaches. · Modeling waveform distortion interaction within the ERPS in Sweden, incorporating challenges such as moving loads, meshed grid analyses, and a wide range of disturbances propagation in ERPS. · Addressing the different mechanisms affecting waveform distortion at the catenary and public grid sides. · Investigation of the impact of waveform distortion performance on associated equipment. The work provides crucial steps for better establishing a PQ framework and future standardization for waveform distortion in ERPS by exploring multiple aspects and directions on the assessment side
Catalytic conversion of carbon dioxide into fuels
No full textHeterogeneous catalysis offers one of the sustainable solutions to the global warming challenge by converting greenhouse gases, particularly carbon dioxide (CO2), into valuable chemicals, notably methane (CH4). The CO2 methanation is a thermodynamically favorable and scalable process, typically carried out using nickel (Ni) based catalysts. However, the intense exothermicity of the methanation reaction poses challenges, including sintering of Ni nanoparticles and carbon deposition, which critically undermine the catalyst's stability. Resilience of the catalyst can be enhanced by tuning the metal-support interaction (MSI) and regulating the dispersion of Ni nanoparticles. The aim of this thesis was to develop stable and robust Ni catalysts by tuning the MSI and dispersion of Ni nanoparticles supported over the hierarchical zeolite 13X (h13X). Preliminary experiments demonstrated that Ni loading, activity, and instability of the catalyst are correlated. Under optimized synthesis conditions, grafting functional groups onto the support resulted in a stronger MSI and preferentially deposited Ni nanolayers, thereby enhancing the activity and stability of the catalyst. The addition of the cobalt cocatalyst strengthened the MSI and stabilized the catalyst's performance, notably during the initial stages of CO2 methanation. The synergistic effect of surface modification and cocatalyst resulted in lower activation energy, higher activity, and increased stability of the catalyst. Additionally, the influence of oxide promoters (La, Ca, Mg, Ce) proved to be dependent on their specific characteristics, with a notable increase in surface basicity, MSI, and catalyst stability. Based on the outcomes of surface modification and traditional catalyst design, a metal-chelation strategy was explored to regulate the size of Ni nanoparticles. The Ni was coordinated to the amine-based ligands, including pyridine, bipyridine, diethylenetriamine, and oleylamine, followed by their impregnation on the support. Remarkable differences were observed in the characteristics of the catalysts depending upon the type of ligand. A broader Ni distribution was observed for the heterocyclic ligand, whereas better textural properties were achieved by the aliphatic amines, which were attributed to the coordination of Ni in the metal-chelate complexes and the strength of interaction with the support. Besides the catalyst’s design, the process parameters, including temperature, pressure, H2/CO2 ratio, gas hourly velocity, and gas composition, showed a profound impact on the CO2 conversion, CH4 selectivity, and stability of the catalysts. overall, this thesis offers insights into regulating the catalyst's MSI, dispersion, distribution, activity, and stability
Experiments and CFD simulations of spillway discharge distribution
No full textHydropower plants in Sweden has a long history dating back to the early 20th century. In the design of these, now old facilities, expected probable flows were based on recorded precipitation data. As a safety valve of the dam various types of spillway can be installed, to either spill water when no power is produced. Or to regulate water levels above and below the dam to prevent or mitigate flooding, and to be able to prevent overtopping of a dam. As the climate is ever changing, and now average temperatures climb, this leads to an increase in both average annual precipitation and likelihood of expected flood events in Sweden. This leads to a case of old infrastructure designed for old conditions, which now may exceed flow discharge capabilities for safe operations. A need for reevaluation of the existing dam fleet is needed to explore if it can face the new conditions brought by increased precipitation. Previous work has been done by Computational Fluid Dynamics (CFD) to compare scale model data of existing dams, recorded when they were designed. Such comparisons show mostly low differences between the CFD simulations and scale model results, in the range of 1-2%. Some show as much as 10%. With CFD now being a standard tool in many industries involving fluid mechanics, there are several guidelines on how to perform CFD with respect to quality. However CFD is an approximate science and the physics needs to be simplified by a number of models with inherent limitations. Hence to gain trust in CFD simulations for dam operators there needs to be validation cases. Validation cases for single outlet spillway setup exist, but dams often do not have geometries as simple as the existing validation cases. Hence, a need for well defined experiments for CFD validation of hydraulic designs. This thesis aims to provide experimental data suitable for use in evaluating CFD methods for assessing spillway capacity. To this endeavour a purpose built experimental setup was designed to produce experimental data of a quality and complexity not found elsewhere today. The main feature of the experiment is three outlets with the capability of recording the discharge passing through each outlet individually. Other tools used for evaluating flow conditions in the channel include Acoustic Doppler Velocimetry. The results consists of experimental data gathered for three different variations of the experimental geometry. First a Deep channel flowing past a sharp corner, which produced low velocities in the channel leading up to the outlets. A second variation where the channel floor was raised to induce larger velocities in the flow leading up to the outlets, for increased differences in the flow distribution between the different outlets. As a final variation, the channel width was reduced leading to even higher velocities, and larger differences in both waterlevels at different points in the experimental channel, and in the discharge recorded in the different outlets. The distribution of the flow discharge across the outlets varies with the different geometries, and with the different inflows tested. At low flows differences in distribution between the outlets were negligible, especially with the first channel layout. At higher flows the differences grow, and show clear differences that should be replicable in simulations. Thus showing results that could be used for validation of CFD methods in regards to flow distribution across a spillway with multiple outlets. Additional data to use for validation include ADV data gathered in the channel leading up to the outlets, which documents recirculation zones introduced due to the geometries. As potentially simulations could produce flow distribution results that are correct while not simulating flow behaviour correctly