Streams and rivers have been modified in the past centuries for agricultural purposes. The Baltic Sea suffers from problems regarding eutrophication. Regulations of point-sources have decreased nutrient levels, but for a scattered source of nutrient pollution, streams are important. One way of mitigating nitrogen is with coupled denitrification and nitrification processes when stream water is transported through flow paths in the hyporheic zone, an area in the stream sediments where groundwater and stream water mix. Tullstorps brook is an agricultural stream that flows into the Baltic Sea. It has had problems with high nutrient loads and poor water quality and has therefore been restored. The fieldwork in this project was conducted in Tullstorps brook in May 2019, where Rhodamine WT (RWT) tracer test and Hydraulic Conductivity (HC) measurements were done in 3 reaches, and compared to similar fieldwork since before restorations, during the summer of 2015. Two reaches in an agricultural setting that have been restored, Reach 4 and Reach 6, were measured, as well as a control reach, Reach 5, which is in a natural setting. The tracer tests indicated a significant decrease in the velocity in remediated reaches. The results of exchange velocity between the stream flow and the hyporheic zone suggest an increase after remediation of the reaches and the residence time seems to be decreasing simultaneously. When comparing the hydraulic characteristics, different stream flow during measurements was considered in a qualitative manner. The results of HC measurements show a decrease from 2015 to 2019 in the remediated reaches. In Reach 4 it decreased from 1.20E-03 m/s to 5.0E-4 m/s and in Reach 6, HC decreased from 7.70E-04 m/s before remediations to 5.6E-04 m/s after remediation actions. All the measurements have uncertainties, especially since homogeneity is assumed to some extent and the natural environment will always be heterogeneous.

Energy needs are projected to continue to increase in the coming decades, and with the drive to use more clean energy to combat climate change, nuclear energy is poised to become an important player in the energy portfolio of the world. Due to the unique nature of nuclear energy, it is always vital to have safe and efficient generation of that energy. In current light water reactors, the most common fuel is uranium dioxide (UO2), an oxide ceramic. There is also ongoing research examining uranium-based based metallic fuels, such as uranium-molybdenum (U-Mo) fuels with low uranium (U) enrichment for research reactors as part of a broader effort to combat nuclear proliferation, and uranium-zirconium-based fuels for Generation IV fast reactors. Each nuclear fuel has weaknesses that need to be addressed for safer and more efficient use. Two major challenges of using UO¬2 are the fission gas (e.g. xenon) release and the decreasing thermal conductivity with increasing burnup. In UMo alloys, the major weakness is the breakaway swelling that occurs at high fission densities. The challenges presented by both fuel types are heavily impacted by microstructure, and several studies have identified that the initial microstructure of the fuel in particular (e.g. initial grain size and grain aspect ratio) plays a large role in determining when and how quickly these processes occur. Thus, knowledge of how such initial microstructures evolve is paramount in having stable and predictable fission gas release and thermal conductivity decrease (in UO2) and fuel swelling (in UMo alloys). Mobility is a critical grain boundary (GB) property that impacts microstructural evolution. Existing literature examines GB mobility for a few specific boundaries but does not (in general) identify the anisotropy relationships that this property has. This work first examined the anisotropy in GB mobility, specifically identifying the anisotropy trend for the low-index rotation axes for tilt GBs in BCC γ U, and fluorite UO2 via molecular dynamics simulation. GB mobility is calculated using the shrinking cylindrical grain method, which uses the capillary effect induced by the GB curvature to drive grain growth. The mobilities are calculated for different rotation axes, misorientation angles, and temperatures in these systems. The results indicated that the density of the atomic plane perpendicular to the (tilt) GB plane (which is also perpendicular to the rotation axis) significantly impacts which GB rotation axis has the fastest boundaries. Specifically, the atomic plane that has a higher density tends to have a faster mobility, because it is more efficient for atoms moving across the GB along such planes. For example, for body-centered cubic materials, the <110> tilt GBs are determined to have the fastest mobilities, while face-centered cubic (FCC) and FCC-like structures such as fluorite have <111> tilt GBs as the fastest. Knowledge of GB mobility and its anisotropy in pure materials is helpful as a baseline, but real materials have solutes or impurities (both intentionally and unintentionally) which are known to affect GB mobility by processes such as solute drag and Zener pinning. Additionally, in reactors, nuclear fission can produce many fission products, each of which acts as an additional impurity that will interact with the GB in some way. Because the initial microstructure and its subsequent evolution are vital for addressing the challenges of using nuclear fuel as described above, knowledge of the impacts of these impurities on GB mobility is required. Therefore, this work examined the impact of solutes and impurities on GB mobility and its anisotropy. In particular, the solute effect was examined using the UMo alloy system, while the impurity effect was examined using Xe (a very common fission product) in the γ U, UMo, and UO2 systems. It is found that both Mo and Xe can cause a solute drag effect on GB mobility in the γ U system, with the effect of Xe being stronger than Mo at the same solute/impurity concentration. Xe also causes a solute drag effect in UO2, though the magnitude of the effect is interatomic-potential-dependent. The mobility anisotropy trend was found to disappear at high solute and impurity concentrations in the metallic U and UMo systems but was largely unaffected in the UO2 system. These results not only increase our fundamental understanding of GB mobility, its anisotropy, and solute/impurity drag effects, but also can be used as inputs for mesoscale simulations to examine polycrystalline grain growth with anisotropic GB mobility and in turn examine how the fuel performance parameters change with these properties. / Doctor of Philosophy / Worldwide, energy needs continue to increase each year. Concerns related to climate change have led to an increased emphasis on renewable energies such as solar and wind, but the limitations of these resources prevent them from being the only energy sources. Nuclear energy is uniquely positioned to address several energy concerns: it is clean (no carbon emissions and air pollution), reliable (for example, 24/7 energy production, independent of weather), and energy-dense (one kilogram of fissile uranium provides roughly the same amount of energy as 3000 metric tons of coal). Currently, nuclear energy provides roughly 20% of the energy of the United States, but future predictions show a decrease in the total share of energy generation due to aging systems and a limited number of new reactors being built. The safety and efficacy of existing and future reactors are among the primary concerns for being able to allow nuclear energy to increase its energy share. To determine the safety and efficacy of new reactor designs, a computer simulation tool called fuel performance modeling has been used over the last few decades. This tool requires several material properties as input, one of which is how the nuclear reactor fuel microstructure changes based on a variety of conditions. A significant process contributing to microstructural change is grain growth. Grains (crystallites that make up the whole material) meet at interfaces called grain boundaries (GBs), and these GBs have two properties that largely determine how grain growth occurs: energy and mobility. Significant effort is being put into understanding these properties and their anisotropy, or how they change based on the GB character which is the relative mismatch between the two grains. This work contributes additional understanding of GB mobility anisotropy in two nuclear fuels: uranium dioxide (UO2, the primary fuel in current reactors) and a uranium-molybdenum (UMo) alloy (the primary fuel for newer research reactors). In particular, computer simulation is used to determine GB mobility for several unique GB systems. It is found that for pure nuclear fuels, GB mobility anisotropy is largely determined by which atomic plane has the highest density perpendicular to the GB. When the fuel is no longer pure (through the addition of alloying elements or other impurities) the anisotropy changes significantly in UMo fuels, such that at high concentrations of solute or impurities there is little to no anisotropy, while very little change is observed in the anisotropy in UO2.

Developing low-cost and effective technologies to upgrade phosphorus (P) removal from the catchment runoffs and rural wastewater treatment facilities is one of the main research agendas to save the Baltic Sea from eutrophication. In Sweden, the construction of the constructed wetlands has been one of the environmental objectives for wastewater quality improvement in the small communities. However, the insufficiently understanding of the mechanisms underlying the process of phosphorus mobility and sorption in the constructed wetlands has limited design of the effective constructed wetlands. To provide the better understanding of sorption process in the catchment and constructed wetland system, this thesis used the GIS-based Soil and Water Assessment Tool (SWAT) to predict phosphorus mobility and identify the critical diffusing sources of phosphorus loss in the Oxunda catchment (Paper I). Then, the study developed the three-dimensional numerical Reactive TRAnsPort Model (RETRAP - 3D) in the COMSOL Multiphysics® for evaluating the long - term sorption processes and removal efficiencies of the porous reactive media for upgrading the performance of constructed wetlands (Paper II and III). The latter model coupled many physics equations to solve process of water flow, reaction kinetics and solute transport in the porous reactive adsorbent media for application in the constructed wetlands. The data from the field measurements and column experiments have been used to demonstrate the model simulation accuracy to capture the process of phosphorus sorption in the real environment. Modeling results ranked the phosphorus removal efficiency of the adsorbent media as follows: Polonite® (88 %), Filtralite P® (85%), BFS (62%), Wollastonite (57 %). The satisfactory agreement which obtained between the simulated outputs and measured data confirmed that the SWAT and RETRAP-3D are useful tools for describing various processes in the complicated system. However, further study is required to generate and validate more experimental data to evaluate the sensitivity of local parameters. / <p>This reserch project was finacially supported by Lars Erik Lundberg scholarship foundation for projectnumber (2015/34 and 2016/12), ÅkeochGreta Lissheds Stiftelsen for project number (2015-00026), J.Gust. Richert Stiftelsen and Ecopool researchproject for smart and sustainable environment. QC 20170523</p>

Chronic kidney disease (CKD) is a common disease that affects millions across the US and the globe. Patients with CKD experience an increased risk of venous thrombosis. Here we use two longstanding robust murine models of nephropathies in conjunction with a reliable murine model of venous thrombosis to model venous thrombosis risk in CKD. We show that in the adenine diet-induced CKD, increased concentrations of adenine in the diet result in increased histological evidence of nephropathy and increased venous thrombosis risk assessed by Inferior Vena Cava ligation. Next, we demonstrate that in unilateral ureteric obstruction models, the duration of obstruction is proportional to the nephropathies developed by histological assessment. In both models, we relate nephropathy to venous thrombosis risk. When probed for aryl hydrocarbon receptor (AHR) activation, adenine diet-induced CKD mice show increased activation assessed by nuclear translocation of the receptor. This phenotype was confirmed in vitro when treating human telomerase immortalized human umbilical endothelial cells with uremic serum. Nuclear AHR was not observed in control conditions in vivo or in vitro. Pharmacologic AHR inhibition using a novel drug, BAY Compound, and a well-known AHR inhibitor were both able to abrogate uremic activation of AHR in vitro, which was then corroborated with in vivo studies. Tissue factor (TF) and plasminogen activator inhibitor 1 (PAI-1) are prothrombogenic proteins linked to AHR activation. TF and PAI-1 showed upregulation in CKD mice which were blocked when CKD mice were given AHR inhibitor BAY Compound. This work demonstrates a unique model of venous thrombosis in CKD and suggests that AHR inhibition may be able to limit the elevated risk of venous thrombosis associated with uremia. / 2026-03-08T00:00:00Z

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Wastewater treatment plants (WWTPs) play a vital role in protecting the environment from much of the waste produced by humans. This includes not only human waste, but everything that makes its way into a sewerage system including greywater, stormwater, and potentially hazardous chemicals from, inter alia, chemical spills. The effects of a chemical spill if it enters a WWTP can be disastrous, resulting in the ineffective treatment of incoming water for prolonged periods of time (Söhr, 2014). This can lead to one of the dilemmas of urban wastewater systems, notably, whether it is more damaging to allow a chemical spill to bypass a WWTP, or to attempt to treat all or some of the spill and risk damaging the microbes working in the biological treatment processes (Schütze, 2002). In order to better inform policy makers and process engineers at WWTPs of which measures to take in the event of a spill, solute transport characteristics of a specific sewerage network must be defined.  A series of tracer tests were performed along The Käppala Association’s northern sewerage network to determine these solute transport characteristics, notably the dispersion coefficient which strongly affects the level of dilution that occurs between the injection point and the inlet. A simple solute transport model, carried out in Excel, was created using the Advection-Dispersion Equation (ADE) and the Manning-Strickler equation to relate flow measurements to flow velocity. Results from the experiments show that a dispersion coefficient of 1.55m2/s appears to be applicable throughout the whole of the tunnel network. A depth dependent Manning-Strickler coefficient seems to describe the flow-velocity relationship, however, this method has not been validated. The ADE begins to lose accuracy in describing solute transport as the distance from the inlet and the number of pumping stations the plume goes through increases. / Avloppsreningsverk spelar en viktig roll för att skydda miljön från mycket av det avfall som produceras av människor. Detta inkluderar inte bara mänskligt avfall utan allt som tar sig in i ett avloppssystem, till exempel gråvatten, dagvatten och potentiellt farliga kemikalier från bland annat industriutsläpp. Effekterna av ett kemiskt utsläpp kan vara katastrofala om det kommer in i ett avloppsreningsverk, vilket resulterar i ineffektiv behandling av inkommande vatten under längre perioder (Söhr, 2014). Detta är ett dilemma i urbana avloppssystem – ska man låta ett kemiskt utsläpp ledas förbi ett avloppsreningsverk, eller försöka behandla hela eller en del av utsläppet och riskera att skada mikroberna i den biologiska reningsprocessen (Schütze, 2002). För att beslutsfattare och processingenjörer vid avloppsreningsverk ska kunna fatta rätt beslut om vilka åtgärder som ska vidtas vid utsläpp måste egenskaperna för det specifika avloppsnätet definieras.  Syftet med detta projekt är att uppskatta transportparametrar och karakterisera utspädning i nätverket genom att utföra en serie spårningsförsök i Käppalaverkets upptagningsområde. För att nå syftet fanns det flera mål som genomförts: Genomföra en litteraturstudie  Skapa en förutsägbar modell i Excel baserad på flödesdata längs Käppalaförbundets tunnelsystem Genomföra en serie spårningsförsök vid flera punkter längs tunnelsystemet  Strukturerad datalagring av resultaten så att data är lätt att hitta för framtida projekt  Metoderna kan delas i två: modellering och försök. För att skapa en modell och simulera transport av ett ämne i nätet får man definiera relevanta ekvationer. För den hydrauliska delen av modellen användes Manning-Strickler-ekvationen. Resultaten från detta användes sedan i den förenklade formen av advektion-spridningsekvationen (ADE). Tunnelsystemet uppdelades i flera sektioner med samma egenskaper såsom form och geometri, och en anpassad form av ADE användes emellan sektionerna. För att nå framgång i försöken krävdes att rätt spårämne valdes. Uranin användes i försöken på grund av sina ogiftiga och stabila egenskaper och den låga detektionsgränsen. Injiceringspunkterna låg gradvis längre bort från inloppet; Försök 1 var 9km från verket till nästan 46km vid Arlanda flygplats för Försök 3.  Resultaten från simuleringarna användes för att planera injiceringstid, start- och stopptid för provtagningen och provtagningsfrekvens. Resultatet från första försöket användes för att kalibrera modellen inför de andra försöken. Resultaten från alla försök visade att en dispersionskoefficient på 1.55m2/s, som är ett mått på utspädning i nätet, verkar tillämpligt till hela tunnelsystemet. Koefficienten kan dock vara högre i de kommunala näten. En djupberoende metod för att härleda Mannings tal formulerades, men det kräver ytterligare validering.  Från alla tre försöken kan vi härleda ett förhållande mellan avstånd från inlopp och toppkoncentration samt avstånd från inlopp och varaktigheten av genombrottskurvan. Toppkoncentration visar ett linjärt eller kanske logaritmiskt förhållande med distans, och varaktigheten av genombrottskurvan visar ett starkt linjärt förhållande. Kunskaper om detta är viktigt när man vill genomföra en riskbedömning av ett kemiskt utsläpp i upptagningsområdet eftersom det ger en insikt om hur det kan påverka den biologiska reningen i ett avloppsreningsverk.  Sammanfattningsvis fungerar den enkla formen av ADE bra, men viss avvikelse ses i experiment 3. Detta beror kanske på möjliga övergående lagringsprocesser vid pumpstationerna längs tunnelsystemet. En enda dispersionskoefficient, som är ett mått på utspädning, är tillämplig i hela huvudtunnelsystemet, men spridningen i kommunala nätverk är sannolikt högre. Ytterligare arbete behövs inom dessa kommunala nätverk för att kvantifiera deras effekter.  På grundval av resultaten från detta projekt rekommenderas ytterligare forskningsundersökningar om vad som händer med föroreningar i avloppsreningsverket. Eftersom slammet vid Käppalaverket används för biogasproduktion och är Revaq-certifierat för användning på jordbruksmark är föroreningsnivån i slammet mycket viktigt både ur produktivitets- och hälso- och säkerhetsperspektiv.

<p>Rapid solidification is a well established method to produce novel materials with improved mechanical or electrical properties. The sharp-interface kinetics of rapid solidification for a binary alloy is summarized. A Phase Field model mapping to this sharp interface model is summarized and solved by a new adaptive mesh refinement algorithm. Simulation results are consistent with experiments: The solidification velocity increases in power-law like fashion at low undercooling and approximately linearly at high undercooling; The solid/liquid interface undergoes a transition from four-fold dendritic to circular crystal structures; Solute trapping emerges and the solute partitioning approaches unity as the solidification velocity increases. Our Phase Field simulations are the first self -consistent predictions of velocity selection and morphological selection at both low and high undercoolings and also the first independent check of the solute trapping model in two dimensions.</p> / Thesis / Master of Applied Science (MASc)