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This thesis focuses on the topic of PBF-LB applied to titanium alloys. Of allalloys, an α + β is chosen, named Ti-6Al-4V. The selection of this particular alloy is driven by its current widespread use in many industrial applications where high strength coupled with low density are both desirable properties. For the last 50 years, parts made with this alloy have been cast or forged and then machined to achieve the final geometry. There is now an opportunity totransform this process chain by additive manufacturing, hence reducing material waste and achieving near net shape from powder feedstock. The process is summarised as follows: a laser selectively melts areas on a build plate where powder is pre-placed. Then a successive powder layer is spread and the process is repeated until completion. Upon removal of the part from the build plate, loose powder in the chamber is collected and recycled whenever possible. The design freedom provided by powder bed fusion methods enables production of intricate geometries and added functionality, despite the need for post-build consolidation and/or microstructural adjustments. Today’s fine and narrow powder cuts (e.g., 15-50μm) are designed to be coupled with low layer thicknesses (i.e., 30μm) to achieve smooth surfaces and high resolutions of small features e.g., internal cooling channels. However, costs associated with production of fine and narrow powder cuts are substantial as refinement of batches requires multiple sieving steps. In addition, resulting building times are considerably long (i.e., days), therefore a beneficial alternative could be that of exploring higher layer thicknesses together with wider and coarser powder cuts. The main idea of this work is to investigate the effects of employing a powder with a wider size distribution 15-90μm. The aim is to reduce the sievingrequired and consequently decrease the costs of developing and building parts made by PBF-LB. An extensive microstructural investigation is conducted on single tracks and cubes built with 27 different process parameter combinations, which also attempts to establish correlations between characteristics of tracks and responses measured in cubes. As a second step, the amount of residual porosity of asbuilt cubes is chosen as the discriminant for further mechanical testing of sub and super-β transus high-pressure heat treated material. / Den här avhandlingen fokuserar på additiv tillverkning av titanlegeringar med laser pulverbädd metoden. Den legering som främst är i fokus är Ti-6Al-4Vsom är en α+β legering. Anledningen till valet av denna titanlegering är att det är den vanligast förekommande titanlegeringen och att den används i ett antal olika industriella tillämpningar där hög styrka i kombination med låg vikt är önskvärda egenskaper. Under de senaste 50 åren har komponenter utav denna legering tillverkats med gjutning eller smide, följt av bearbetning till slutlig geometri. Med hjälp av additiv tillverkning finns nu en möjlighet att förändra tillverkningskedjan i vilket minskat materialspill och en mer nära-slutgeometri kan erhållas direkt genom användning av metallpulver som utgångsmaterial. Processen kan summeras enligt följande: en laser smälter ett förbestämt område på en byggplatta som täckts mer pulver. Därefter adderas ytterligare ett lager med metallpulver ovanpå, på vilket samma process sker igen, och igen osv, tills hela detaljen är färdigtillverkad. När detaljen ska tas loss ifrån byggplattan samlas det kvarvarande icke-smälta pulvret upp och återanvänds i så stor utsträckning som möjligt. Frihetsgraderna vid design i processen möjliggör tillverkning av komplexa geometrier och adderade funktionaliteter, även fast efterbehandling och/eller justeringar av mikrostrukturen kan behövas. Dagens smala pulverstorleksfördelning (tex 15-50μm) är avsedd att ge tunna lagertjocklekar (tex 30μm) för att åstadkomma en fin yta och hög upplösning av små geometrier, såsom exempelvis interna kylkanaler. Men kostnaderna som det innebär att framställa och sortera ut fina och smala kornstorleksfördelningarär avsevärd eftersom det innebär flera steg med silning. Vidare leder de tunnalagertjocklekarna till långa byggtider (typiskt dagar). Ett alternativ, som därför vore fördelaktigt, är att undersöka möjligheten med att bygga tjockare lager med en bredare och större pulverstorleksfördelning. Huvudfokuset i detta arbete fokuserar på att undersöka effekterna av att använda en bredare pulverpartikelstorleksfördelning 15-90μm, med syfte at minska silningsbehovet och därmed reducera kostnaden för att utveckla och tillverka detaljer med laser pulverbädd additiv tillverkning. En omfattande mikrostrukturundersökning har gjorts på enkelsträngar och kuber byggda med 27 olika processparameter-kombinationer, vilket samtidigt försöker identifiera korrelationer mellan enkelsträngarnas karaktäristik med resultaten uppmätta hos kuberna. I ett nästa steg har material, som tillverkats med processparametrar som renderade i minst/mest porer hos kuberna, mekaniskt provats efter att det högtrycksvärmebehandlats över- respektive under β-transus. / <p>Paper A is not included due to the copyright.</p><p>Paper B and C are to be submitted.</p>

The emphasis of this study is focusing on three-dimensional (3D) investigations of the manganese sulfide (MnS) inclusions characteristics in steels by using electrolytic extraction (EE). Two steel grades, 42CrMo4 and 157C, heat treated (HT) at 900 oC were investigated. 42CrMo4 steel samples were heat treated for 5, 10, 15 and 30 minutes while 157C steel samples were heat treated for 5 minutes. Samples of 42CrMo4 were taken from middle zone of an as-cast steel bar while that for grade 157C were taken from 3 different zones (centre, middle and surface). Inclusions were collected on film filters and analyzed by SEM for classification and determination of their characteristics including the size, number density (Nv), morphology and composition. The aspect ratio (AR) as well as particle size distribution (PSD) were also compared for steel samples conducted at various HT times. The result showed that EE is a reliable method of investigation inclusion characteristics. The inclusions were classified into 3 types according to their morphology and composition. Type I was elongated rod-like MnS, type II was coarsened sheet-like MnS and type III was spherical MnS inclusions. In addition, HT significantly reduced the Nv and fairly reduced AR but no significant reduction in size observed. The peak of PSD decreased with an increased HT time. The change of Nv, length, AR and PSD could be altered because of uneven inclusion distribution in filter and different sampling positions.

Pine tree substrate (PTS) is a relatively new substrate for container crop production. There are no detailed studies that elucidate how storage time impacts PTS chemical, physical, and biological aspects. The objective of this research was to determine how PTS storage time influenced PTS chemical and physical properties, nitrification, and plant growth. Pine tree substrate was manufactured by hammer-milling chips of loblolly pine trees (Pinus taeda L.) through two screen sizes, 4.76 mm (PTS) and 15.9 mm amended with peat (PTSP). PTS and PTSP were amended with lime at five rates. A peat-perlite mix (PL) served as a control treatment. Prepared substrates were placed in storage bags and stored in an open shed in Blacksburg, Virginia. Subsamples were taken at 1, 42, 84, 168, 270, and 365 days. At each subsampling day, twelve 1-L containers were filled with each substrate. Six containers were left fallow and six were planted with marigold (Tagetes erecta L. "Inca Gold") seedlings. Substrate was also collected from select treatments for Most Probable Number assays to estimate density of nitrifying microorganisms, and for chemical and physical property analyses. Pour-through extracts were collected from fallow containers at 0, 2, and 4 weeks, and from marigold containers at harvest for determination of pH, electrical conductivity, ammonium-N and nitrate-N. At harvest, marigold height, width, and dry weight were measured. At least 1 kg·m-3 lime for PTS, and 2 to 4 kg·m-3 lime for PTSP were needed to maintain pH values ≥ 5.5 for 365 days. Bound acidity of unlimed PTS increased but cation exchange capacity for unlimed PTS and PTSP decreased over 365 days. Carbon to nitrogen ratio and bulk density values were unchanged over time in all treatments. There were minor changes in particle size distribution for limed PTS and unlimed and limed PTSP. Marigold growth in PTS and PTSP was ≥ PL in all limed treatments, except at day 1. Nitrite-oxidizing microorganisms were present and nitrification occurred in PTS and PTSP at all subsampling days. Pine tree substrate is relatively stable in storage, but pH decreases, and lime addition may be necessary to offset this decrease. / Ph. D.

Climate change affects lakes, seas and running water globally, but the long-term effects on aquatic ecosystems, including fish communities, are complex and difficult to predict. Previous research has shown that changes in temperature, for example, can lead to shifts in fish species distribution and reductions in body size within fish communities. This study aims to investigate the impact of temperature on size distribution of individuals in fish communities by examining variations in so-called size spectrum and mean body size in ten Swedish lakes over the period 1994-2023. Data were collected from Swedish monitoring programs and analyzed using linear mixed-effects models. The result indicates a significant negative effect of temperature on the size spectrum and mean body size, meaning the number of small individuals increases while the number of large ones decreases. The size spectrum also shows a declining trend over time in several of the lakes, highlighting a shift in the size distribution of fish. These findings support the use of the size spectrum as an indicator of the impacts of climate change on freshwater ecosystems. The results of this study found a clearer link between temperature changes and size distribution compared to biomass, which supports the usefulness of size distribution as an indicator. Understanding these relationships is crucial for informing management and conservation strategies aimed at preserving lake ecosystems and the functions and ecosystem services that fish provide, including food and recreational opportunities. The study further contributes to the existing evidence that climate change is reshaping fish communities and aquatic ecosystems, underscoring the need for adaptive management to mitigate these effects and ensure sustainability of fish stocks for future generations. / Klimatförändringarna påverkar sjöar, hav och rinnande vatten globalt, men långsiktiga effekter på akvatiska ekosystem, inklusive fisksamhällens, är komplexa och svåra att förutse. Tidigare studier har visat att förändringar i temperatur till exempel kan leda till skiften i fiskarters utbredning och minskningar i kroppsstorlek i fisksamhällen. Denna studie syftar till att undersöka temperaturens inverkan på storleksfördelningen av individer i fisksamhällen genom att undersöka variation i det så kallade storleksspektrumets lutning och medelstorlek i tio svenska sjöar under perioden 1994–2023. Data samlades in från svenska övervakningsprogram för sjöar och analyserades med hjälp av linjära mixade effektmodeller. Resultaten indikerar en signifikant negativ effekt av temperatur på storleksspektrumets lutning och medelkroppsstorlek, dvs. antalet små individer ökar relativt antalet stora. Storlekspektrumets lutning visar också en nedåtgående trend över tid i flera av sjöarna, vilket belyser att fiskarnas storleksfördelning har skiftat mot relativt fler små individer i vissa sjöar. Dessa fynd styrker användningen av storleksspektrum som en indikator på klimatförändringarnas effekter på sötvattensekosystem. Resultat från denna studie visar också en tydligare koppling av förändrad temperatur på storleksfördelning än biomassor av fisk och växtplankton, vilket styrker nyttan av storleksfördelning som indikator. Att förstå dessa samband är avgörande för att vägleda förvaltnings- och bevarande strategier som syftar till att bevara sjöekosystem, de funktioner samt ekosystemtjänster som fiskar tillhandahåller, såsom mat och rekreationsmöjligheter. Studien bidrar till redan existerande bevis på att klimatförändringarna omformar fisksamhällen och akvatiska ekosystem, vilket tydliggör behovet av adaptiv förvaltning för att mildra dessa effekter och säkerställa starka fiskbestånd för framtida generationer.

No / Microcarrier cell culture systems provide an attractive alternative to the conventional monolayer cell culture for cell amplification, due to their high surface area-to-volume ratio. Unlike enzymatic methods for removing cells from microcarriers after cell culture, which can lead to irreversible damage of the cells, microcarriers which release cells by temperature adjustment have been developed. This was achieved by grafting a temperature-responsive polymer, poly(N-isopropylacrylamide) (PNIPAAm), on the microcarrier surface. This review comprehensively presents various methods to prepare such thermo-responsive microcarriers based on PNIPAAm. These methods include the grafting-to technique, grafting-from technique, grafting-through technique, along with methods leading to PNIPAAm hydrogel beads, seeded polymerization, and non-covalent adsorption. The methods for controlling PNIPAAm grafting density, molecular weight and molecular architecture are also outlined. Further, the efficiency of cell attachment, proliferation and thermally-induced detachment of such thermo-responsive microcarriers is introduced and compared. (C) 2015 Elsevier Ltd. All rights reserved.

This research investigates the optimization of the filtration and washing process during the transfer of X-Alfa production from a plant equipped with a centrifuge to a new plant equipped with a Nutsche filter dryer. The aim of this study is to determine the optimal pressure level to ensure an efficient isolation process at an industrial scale for three different filtrations, to assess the effects of increased pressure levels on the particle size distribution (PSD) within the filter cake, and to establish the most effective washing method for thoroughly removing N-methyl-2-pyrrolidone (NMP) content from the Molecule-11 intermediate. To achieve these objectives, the three filtrations were examined at different pressure levels on a laboratory scale. The collected filtration data were then used to estimate scaled-up filtration times at different pressures, enabling the determination of optimal pressure levels for the three filtrations. After that, the PSD was analyzed using microscopy and laser diffraction to ascertain the effect of pressure on the filter cakes. Finally, the washing process was investigated by washing equal amounts of filtered filter cakes with different numbers of wash cycles and different wash portions. The residual NMP content in the filter cake was then measured using 1H-NMR, and the amount of product loss to the process liquids was quantified using HPLC to identify the optimal washing method. Results indicated that the optimal pressure for the first filtration is 0.2 bar with a filtration time of approximately 22 minutes, and for the third filtration, it is 0.1 bar with a filtration time of about 4 minutes. No optimal pressure could be determined for the second filtration due to the negative compressibility index value generated by the used evaluation model. This negative value could have arisen from inhomogeneous suspensions that affected the filtration rate and consequently resulted in low linearity of the time/volume versus volume plots. Therefore, the experiment needs to be repeated for this filtration. Furthermore, increasing pressure levels during filtration showed no significant impact on PSD within the filter cakes. Finally, washing the filtered filter cakes with two wash cycles using half of the total wash volume in each cycle proved to be the optimal washing method, enhancing NMP removal efficiency by 30% compared to a single wash cycle using the same total wash volume. / Denna studie undersöker optimeringen av filtrerings- och tvättprocessen vid flyttningen av X-Alfa-produktionen från en fabrik utrustad med centrifug till en ny fabrik utrustad med Nutsche-filtertork. Syftet är att identifiera den optimala trycknivån för att uppnå en effektiv isoleringsprocess i fabriksskala för tre olika filtreringar, att undersöka hur en ökad trycknivå påverkar partikelstorleksfördelningen (PSD) i filterkakan samt att fastställa den bästa tvättmetoden för att maximalt avlägsna N-metyl-2-pyrrolidon (NMP) från molekyl-11-intermediatet. För detta syfte studerades först de tre filtreringar vid olika trycknivåer i en laboratorieskala och filtreringsdata som samlades in användes för att estimera uppskalade filtreringstider vid olika trycknivåer för att kunna därefter bestämma optimala trycknivåer för de tre filtreringar. Därefter analyserades PSD med hjälp av mikroskopi och laserdiffraktion för att bestämma tryckets påverkan på filterkakorna. Slutligen undersöktes tvättprocessen genom att tvätta lika mängder av filtrerade filterkakor med varierande antal tvättcykler och olika tvättportioner och därefter bestämdes den kvarvarande NMP-halt i filterkakan med hjälp av 1H-NMR och mängden förlorad produkt till processvätskorna med hjälp av HPLC för att sedan fastställa det optimala tvättmetoden. Resultatet visade att det optimala trycket för den första filtreringen är 0,2 bar med en filtreringstid på cirka 22 minuter och för den tredje filtreringen är det 0,1 bar med en filtreringstid på cirka 4 minuter. Inget optimalt tryck kunde fastställas för den andra filtreringen på grund av att den använda utvärderingsmodellen genererade ett negativt kompressibilitetsindex, vilket möjligtvis härstammar från inhomogena suspensioner som påverkade filtreringshastigheten och därmed resulterade i en icke-fullständig linjäritet av tid/volym mot volym-diagrammen. Därför krävs det att experimentet upprepas för denna filtrering. Ökningen av trycknivån under filtreringen visade ingen signifikant inverkan på PSD i filterkakorna och tvättningen av filtrerade filterkakor med två tvättcykler, där hälften av den totala mängden tvättvätska används i varje cykel, bevisades vara den optimala tvättmetoden med ett förbättrad NMP-borttagningseffektivitet på 30 vikt-% i jämfört med en cykels tvättning med samma total mängd tvättvätska.

L’imagerie médicale a longtemps été limitée à cause des performances médiocres des fluorophores organiques. Récemment la recherche sur les nanocristaux semi-conducteurs a grandement contribué à l’élargissement de la gamme d’applications de la luminescence dans les domaines de l’imagerie et du diagnostic. Les points quantiques (QDs) sont des nanocristaux de taille similaire aux protéines (2-10 nm) dont la longueur d’onde d’émission dépend de leur taille et de leur composition. Le fait que leur surface peut être fonctionnalisée facilement avec des biomolécules rend leur application particulièrement attrayante dans le milieu biologique. Des QDs de structure « coeur-coquille » ont été synthétisés selon nos besoins en longueur d’onde d’émission. Dans un premier article nous avons modifié la surface des QDs avec des petites molécules bi-fonctionnelles portant des groupes amines, carboxyles ou zwitterions. L’effet de la charge a été analysé sur le mode d’entrée des QDs dans deux types cellulaires. À l’aide d’inhibiteurs pharmacologiques spécifiques à certains modes d’internalisation, nous avons déterminé le mode d’internalisation prédominant. L’endocytose par les radeaux lipidiques représente le mode d’entrée le plus employé pour ces QDs de tailles similaires. D’autres modes participent également, mais à des degrés moindres. Des disparités dans les modes d’entrée ont été observées selon le ligand de surface. Nous avons ensuite analysé l’effet de l’agglomération de différents QDs sur leur internalisation dans des cellules microgliales. La caractérisation des agglomérats dans le milieu de culture cellulaire a été faite par la technique de fractionnement par couplage flux-force (AF4) associé à un détecteur de diffusion de la lumière. En fonction du ligand de surface et de la présence ou non de protéines du sérum, chacun des types de QDs se sont agglomérés de façon différente. À l'aide d’inhibiteur des modes d’internalisation, nous avons corrélé les données de tailles d’agglomérats avec leur mode d’entrée cellulaire. Les cellules microgliales sont les cellules immunitaires du système nerveux central (CNS). Elles répondent aux blessures ou à la présence d’inflammagènes en relâchant des cytokines pro-inflammatoires. Une inflammation non contrôlée du CNS peut conduire à la neurodégénérescence neuronale et est souvent observée dans les cas de maladies chroniques. Nous nous sommes intéressés au développement d’un nanosenseur pour mesurer des biomarqueurs du début de l’inflammation. Les méthodes classiques pour étudier l’inflammation consistent à mesurer le niveau de protéines ou molécules relâchées par les cellules stressées (par exemple monoxyde d’azote, IL-1β). Bien que précises, ces méthodes ne mesurent qu’indirectement l’activité de la caspase-1, responsable de la libération du l’IL-1β. De plus ces méthode ne peuvent pas être utilisées avec des cellules vivantes. Nous avons construit un nanosenseur basé sur le FRET entre un QD et un fluorophore organique reliés entre eux par un peptide qui est spécifiquement clivé par la caspase-1. Pour induire l’inflammation, nous avons utilisé des molécules de lipopolysaccharides (LPS). La molécule de LPS est amphiphile. Dans l’eau le LPS forme des nanoparticules, avec des régions hydrophobes à l’intérieure. Nous avons incorporé des QDs dans ces régions ce qui nous a permis de suivre le cheminement du LPS dans les cellules microgliales. Les LPS-QDs sont internalisés spécifiquement par les récepteurs TLR-4 à la surface des microglies. Le nanosenseur s’est montré fonctionnel dans la détermination de l’activité de la caspase-1 dans cellules microgliales activées par le LPS. Éventuellement, le senseur permettrait d’observer en temps réel l’effet de thérapies ciblant l’inflammation, sur l’activité de la caspase-1. / Medical imaging based on fluorescence has suffered from the poor photostability and mediocre performance of organic fluorophores. The discovery and subsequent improvements in nanocrystal synthesis and functionalization has greatly benefited the applications in medical imaging and the development of nanocrystal-based sensors for diagnostics. QDs are semi-conductor nanocrystals which have similar sizes as proteins (2-10 nm). They are highly luminescent, and can be made to emit at any desired wavelength by varying their size and composition. The surface of QDs can be easily functionalized with biomolecules. Hence, it is interesting to study how QDs interact in the biological world. Highly luminescent core-shell QDs emitting at different wavelengths were prepared according to our needs. In a first study, the surface of the QDs was modified with various small bi-functional thiolated ligands (carboxylated, aminated and zwitterionic). The modified-QDs of nearly identical sizes were administered in vitro to study the impact of surface charge and cell type on the mode and extent of cell uptake and elimination. Using specific inhibitors of cell uptake we determined which modes contributed to the internalization of the QDs. Endocytosis mediated by lipid rafts represented the predominant pathway for the internalization of QDs. However, other modes contributed to a lesser degree, depending on the surface ligand. We then analyzed the effect of QD agglomeration in cell culture media on its cellular uptake by microglia. Thorough characterization of QD agglomerate size distribution was conducted by asymmetrical flow field-flow fractionation (AF4) with a dynamic light scattering detector. Depending on the type of surface ligand and if serum proteins were present, the agglomeration pattern of the QDs was significantly different. With inhibitors of specific modes of cell uptake, we showed that the size distribution data, obtained by AF4, correlated with the modes of cell uptake. Microglia cells are immune cells of the central nervous system (CNS). They respond to injury or the presence of inflammagens by producing pro-inflammatory cytokine. Inflammation in the CNS may lead to loss of neurons, and can found in many chronic diseases. We were interested in building nanosensors to measure the onset of inflammation. Current methods to study inflammation consist in measuring levels of certain proteins or chemicals released by stressed cell (e.g. Western blot or ELISA assay for IL-1β). Although precise, these methods measure indirectly the activity of the enzyme responsible for releasing IL-1β, i.e. caspase-1. Moreover, these methods cannot be applied to live cells. We designed a sensor based on FRET between a QD and a dye linked by a peptide specifically cleaved by the caspase-1. To induce inflammation, we applied lipopolysaccharides (LPS), which are endotoxins present in Gram negative bacteria responsible for sceptic shock. The LPS form nanoparticles due to their amphiphilicity. The interior hydrophobic regions were used to load hydrophobic QDs, making the LPS luminescent. The microglia internalized LPS-QD predominantly through TLR-4 membrane receptors. We describe how the LPS induce inflammation and demonstrated the functionality of the QD-based sensor. Eventually, the sensor could be used to monitor in real time the action of therapeutics against inflammation.

A study was conducted to evaluate the properties and processes influencing the rate and magnitude of volume decrease and strength gain for oil sand fine tailings resulting from a change in bitumen extraction process (caustic versus non-caustic) and the effect of adding a coagulant to caustic fine tailings. Laboratory flume deposition tests were carried out with the objective to hydraulically deposit oil sand tailings and compare the effects of extraction processes on the nature of beach deposits in terms of geometry, particle size distribution, and density. A good correlation exists between flume deposition tests results using oil sand tailings and the various other tailings materials. These comparisons show the reliability and effectiveness of flume deposition tests in terms of establishing general relationships and can serve as a guide to predict beach slopes. Fine tailings were collected from the various flume tests and a comprehensive description of physical and chemical characteristics of the different fine tailings was carried out. The characteristics of the fine tailings is presented in terms of index properties, mineralogy, specific surface area, water chemistry, liquid limits, particle size distribution and structure. The influence of these fundamental properties on the compressibility, hydraulic conductivity and shear strength properties of the fine tailings was assessed. Fourteen two meter and one meter high standpipe tests were instrumented to monitor the rate and magnitude of self-weight consolidation of the different fine tailings materials. Consolidation tests using slurry consolidometers were carried out to determine consolidation properties, namely compressibility and hydraulic conductivity, as well as the effect of adding a coagulant (calcium sulphate [CaSO4]) to caustic fine tailings. The thixotropic strength of the fine tailings was examined by measuring shear strength over time using a vane shear apparatus. A difference in water chemistry during bitumen extraction was concluded to be the cause of substantial differences in particle size distributions and degree of dispersion of the comparable caustic and non-caustic fine tailings. The degree of dispersion was consistent with predictions for dispersed clays established by the sodium adsorption ratio (SAR) values for these materials. The biggest advantage of non-caustic fine tailings and treating caustic fine tailings with coagulant is an increased initial settlement rate and slightly increased hydraulic conductivity at higher void ratios. Thereafter, compressibility and hydraulic conductivity are governed by effective stress. The chemical characteristics of fine tailings (water chemistry, degree of dispersion) do not have a significant impact on their compressibility behaviour and have only a small influence at high void ratio (low effective stress). Fine tailings from a caustic based extraction process had relatively higher shear strengths than comparable non-caustic fine tailings at equivalent void ratios. However, shear strength differences were small and the overall impact on consolidation behaviour, which also depends on compressibility and hydraulic conductivity, is not expected to be significant.