The studies in the present thesis explored the feasibility of using nanocellulose-based filters in virus removal filtration of plasma-derived proteins.   In Paper I, two-step nanofiltration of commercially available human serum albumin (HSA) product, which was diluted to 10 g L-1 by phosphate buffer saline (PBS) and adjusted pH to 7.4, was performed to remove soluble protein aggregates and reduce filter fouling. The two-step filtration of HSA employed nanocellulose-based filters of varying thickness, i.e. 11 μm and 22 μm filters.  The removal of HSA aggregates during filtration through 11 μm pre-filters dramatically improves the flow properties of the 22 μm filter, enabling high protein throughput and high virus clearance. A distribution of pore sizes between 50 nm and 80 nm, which is present in the 11 μm filter and is absent in the 22 μm filter, plays a crucial part in removing the HSA aggregates. With respect to virus filtration, 1 bar constant trans-membrane pressure filtration shows poor removal ability of ΦX174 bacteriophage (28 nm), i.e., log10 reduction value (LRV) ≤ 3.75, while that at 3 bar and 5 bar achieves LRV[MOU1] [LW2]  > 5 model virus clearance and overall rapid filtration. Removal of protein aggregates during bioprocessing of HSA products is key to improving the filtration flux, which makes it possible to apply virus removal filtration for HSA to ensure its virus safety.   In Paper II, nanofiltration of human plasma-derived intravenous immuno-globulin (IVIG) intermediate (11.26 g L-1, pH 4.9) was carried out to demonstrate high product recovery and high model virus clearance. Virus removal filtration of industrial-grade human IVIG was achieved using 33μm filters at both low (60 Lm-2) and high (288 Lm-2) volumetric load. No changes in IVIG structure were detected and high product recovery was recorded. High virus clearance (LRV ≥ 5-6) was achieved for the small-size model viruses (ΦX174 and MS2 bacteriophages) during the load volume of 60 Lm-2. Side-by-side comparisons with commercial virus removal filters suggest that the nanocellulose-based filter paper presents great potential for industrial bioprocessing of plasma-derived IVIG.   In Paper III, process analytical technology (PAT) approach was employed to identify the critical filter parameters, e.g. thickness, basis weight, pore size, and flux, affecting model virus removal efficiency using filters produced by different hot presses.  The quality parameters were analyzed with ANOVA and Shewhart charts. Compared with other studied parameters, the hydraulic flux appears as the most relevant final product quality attribute of the nanocellulose-based filter paper to reflect the virus removal efficiency. In particular, a 15% higher flux may be associated with a 0.5-1.0 log10 reduced virus clearance (p=0.007). The results are highlight the importance of continued systematic studies in quality assurance using statistical process control tools  [MOU1]Define LRV  [LW2]Defined in the line above

As current environmental challenges are gaining increased attention, development of clean energy solutions is becoming one of the essential strategies to keep within the boundaries of established environmental policies. Solid oxide cell (SOC) technology can provide clean energy conversion and storage when hydrogen is the energy carrier. The high total energy conversion efficiency resulting from the high operation temperature of SOCs make the technology promising, but material costs must be reduced to make it commercially viable. Therefore, this thesis aims to study the long- term performance of a novel cost-optimized cell interconnect at 650 and 850 °C. At high temperatures, chromium evaporation from the interconnect result in electrode poisoning, which may be mitigated by application of a protective coating. The studied interconnect is an AISI 441 steel with some different pre-oxidized copper and iron spinel coatings. Sample analysis was made mainly with scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and X-ray diffraction. It was found that the most promising pre-oxidation treatment was 24 h at 750 °C and that chromium migration was restrained at 650 °C long-term treatment but not at 850 °C where it wasfound available for evaporation at the surface. / När samtida milljöutmaningar får ökad uppmärksamhet blir gröna energilösningar en av de viktigaste strategierna för att hålla sig inom satta gränser från etablerade miljöriktlinjer. Teknologin bakom fastoxidceller, eller solid oxide cells (SOCs), kan bidra med grön omvandling och lagring av energi när energibäraren är väte. Den höga totala omvandlingseffektiviteten, som kommer med den höga verkningstemperaturen, gör SOC till en lovande teknologi, men materialkostnaderna måste först reduceras innan den blir komersiellt gångbar. Därför syftar detta examensarbete till att undersöka prestandan av en ny, kostnadsoptimerad cellinterkonnektor på lång sikt i 650 och 850 °C. Vid höga temperaturer förångas krom från interkonnektorn, vilket leder till elektrodförgiftning, men kan mildras genom applicering av en skyddande beläggning. Den undersökta interkonnektorn är ett stål som betäcknas AISI 441 belagt med några olika föroxiderade beläggningar av koppar- och järnspinell. Proverna analyserades i huvudsak genom svepelektronmikroskopi kobinerat med energidispersiv röntgenspektroskopi och röntgendiffraktometri. Det visades att den mest lovande föroxideringsbehandlingen var 24 h i 750 °C och att krom förblev återhållet vid 650 °men inte vid 850 °C då det fanns tillgängligt för förångning vidytan.

This licentiate thesis presents the density functional theory study on clean energy materials relevant for catalysis applications, and for solid oxide fuel cells. In the first part of the thesis the metal supported ultrathin films, namely ScN/Mo, MgO/Mo and NaF/Mo are considered, and the Cu atom adsorption and charging on them is explored.The comparative study of these different films allows us to provide recommendations regarding the choice of materials, in order to promote adatom charging. The modulation of the adatom charge, by changing the material of the film, also paves the way for the design of novel catalysts. Moreover, the detailed investigation of the Cu/NaF/Mo caseshows a correlation between the charge redistribution upon the adsorption and the anharmonicity of the accompanying distortion. Overall, the research commands a fresh view on the adatom charging mechanism. In the second part of the thesis the gadolinium doped ceria, used asoxide electrolyte in solid oxide fuel cells, is studied. The employment of the cluster expansion method together with the density functional theory calculations provides the description of the configurational energy spectrum of dopants and oxygen vacancies in terms of effective pair and three site interactions. The chosen method allows one to predict the energy of anarbitrary configuration. Moreover, the effect of volume change on the strength of interactions is investigated, which is relevant for the modelling ofoxide electrolytes at operating temperatures of solid oxide fuel cells,i.e. when volume expansion is notable. / <p>QC 20150521</p>

Very often defects are present in rolled products. For wire rods, defects are very deleterious since the wire rods are generally used directly in various applications. For this reason, the market nowadays requires wire rods to be completely defect-free. Any wire with defects must be rejected as scrap which is very costly for the production mill. Thus, it is very important to study the formation and evolution of defects during wire rod rolling in order to better understand and minimize the problem, at the same time improving quality of the wire rods and reducing production costs. The present work is focused on the evolution of artificial defects during rolling. Longitudinal surface defects are studied during shape rolling of an AISI M2 high speed steel and a longitudinal central inner defect is studied in an AISI 304L austenitic stainless steel during ultra-high-speed wire rod rolling. Experimental studies are carried out by rolling short rods prepared with arteficial defects. The evolution of the defects is characterised and compared to numerical analyses. The comparison shows that surface defects generally reduce quicker in the experiments than predicted by the simulations whereas a good agreement is generally obtained for the central defect. / QC 20101105

To make chemical analysis available both practically and economically, one approach is to miniaturise the equipment needed for the analysis. High-performance liquid chromatography (HPLC) is an example of a flow chemistry analysis system where active work is performed to achieve miniaturised systems. In this thesis, the focus is on creating a miniatyrised pump system constructed of pressurised CO2 (PCO) and a microfluidic chip with a restriction channel. The assignment of the PCO is to force a separate medium, which in this case is water, through the remaining system. The pump system will therefore be defined as pressure-driven, which has advantages as pulse-free flows. Utilising the latent energy from the PCO also reduces the need for electrical power, hence allowing a smaller battery. However, the pressure from the carbon dioxide source will gradually decrease as the content is consumed. To obtain continuous pressure, heaters have been integrated into the chip, and thus, the pressure drop can be controlled by changing the viscosity and density of the through-flowing fluid. A cooling table was also used to enable the cooling of the chip and thus further increase the pressure drop. PID control was implemented for the temperature to be adjusted to maintain a constant pressure downstream of the chip. By using this technology, runs of just over 80 minutes have been achieved with a pressure of 60 bar and a flow of 100 µl/min downstream, with a maximal error of around 0.03 bar. Then a chip adapted for water was used to control the water flow. Chips adapted for carbon dioxide placed right after the carbon dioxide source were also tested andruns of just over 10 minutes at 75 bar and 100 µl/min could be achieved with a maximal error closer to 1 bar. The pressure vessel used held a maximum of 100 ml of CO2 at 60 bar. The idea is that the pump system, in the end, will be applied for portable HPLC, and the PCO will then be stored in a cartridge, but in the experiments, a turned-off ISCO pump functioned as a carbon dioxide source.

The formation of liquid films is a widely known problem in aluminium heat exchanger materials. The phenomenon results in decreased brazeability along with severely deteriorated mechanical properties which might cause assembly collapse. In addition, low-melting-point elements like tin, bismuth and lead are thought to promote grain boundary sliding which is the main deformation mechanism during brazing. Their melting characteristics are not adequately reported in literature. It is therefore of great importance to examine the behaviour of these elements.The main objectives with this work is melting range determination of fin heat exchanger materials, melting detection of low-melting-point elements and calculation of tin, bismuth and lead solid-solubility in aluminium. This work does also involve distribution analysis of such elements in aluminium matrix after heat treatment.These investigations require development of a differential scanning calorimetry (DSC) technique that is applicable for analysis of aluminium fin heat exchanger material containing low-melting-point elements on ppm level. Optimization of the technique includes parameter control; like heating rate, sample mass, reproducibility and choice of crucible material. Laser ablation inductively coupled plasma mass spectroscopy (LA-ICP-MS) is additionally used in order to analyse solid solubility and distribution of low-melting-point elements in aluminium after heat treatment.The developed DSC technique shows a sensitivity limit in the range of 260-600 ppm. It means that it is not possible to detect melting of phases within and below that range. Solid solubility of tin was calculated for the three heat treatment temperatures, 400°C, 500°C and 625°C. Same procedure was applied on bismuth and lead. However, calculated values did not agree with Thermo-Calc. The distribution analysis indicate an exudation of trace elements i.e. diffusion toward surface during heat treatment.In conclusion, more knowledge regarding liquid films in aluminium fin heat exchanger material was obtained. Future work should be to further optimize the DSC technique for trace element analysis for concentrations below 100 ppm. The LA-ICP-MS technique is likely to improve experimentally unverified binary phase diagrams like Al-Bi, Al-Pb and Al-Sn phase diagrams. It can also be used to study exudation behaviour of liquid films.

The present thesis deals with the fundamental aspects of turbulent mixingand non-premixed combustion in wall-jet flows. Direct numerical simulations(DNS) of compressible turbulent flows are performed in a wall-jet configura-tion, which has a close resemblance to many industrial combustion applica-tions. The triple ”turbulence-chemistry-wall” interactions are also present inthis flow set-up. These interactions have been addressed by first focusing onturbulent flow effects on the isothermal reaction, including the near-wall issues.Then, by adding heat-release to the simulations, it has been concentrated onheat-release effects on various phenomena that occur in the reacting turbulentwall-jet flow. In the computational domain, fuel and oxidizer enter separatelyin a non-premixed manner and the flow is fully turbulent and subsonic in allsimulations. In the first phase of this study, the case of a turbulent wall-jetincluding an isothermal reaction without heat release is addressed in order toisolate the near-wall effects and the mixing characteristics of the flow and thekey statistics for combustion are studied in the absence of thermal effects. Adeeper insight into three-dimensional mixing and reaction characteristics in aturbulent wall-jet has been gained through investigation of the probability den-sity functions, higher order moments of velocities and reacting scalars and thescalar dissipation rates of different species. In the second phase, DNS of turbu-lent reacting wall-jets including heat release is performed, where a single-stepglobal exothermic reaction with an Arrhenius-type reaction rate is considered.The main target was to identify the heat-release effects on different mixingscales of turbulent wall-jet flow. The scalar dissipation rates, time scale ratios,two-point correlations, one and two-dimensional premultiplied spectra are usedto illustrate the heat release induced modifications. It is observed that heatrelease effects delay the transition process in the chemically reacting cases andenlarge the fluctuation intensities of density and pressure, but have a dampingeffect on all velocity fluctuation intensities. Finer small mixing scales were ob-served in the isothermal simulations and larger vortical structures formed afteradding significant amounts of heat-release. Simulations with different Damk ̈h-  oler numbers, but comparable temperature-rise are performed and the expectedbehavior, a thinner flame with increasing Damk ̈hler number, is observed. Finally, some heat transfer related quantities are examined. The wall heat fluxand the corresponding Nusselt numbers are addressed. The near-wall reactioneffects on the skin friction coefficient are studied and further the reaction char-acteristics are investigated throughout the domain. / QC 20110908

Increasing energy demand draws attention to new materials for improving current energy storage technologies. Particular interest is directed at solid state batteries and glass Na3ClO electrolyte is a promising candidate. In this report we explore some of the properties of this new glass and its capabilities as a potential electrolyte for a solid-state battery. The two aims of the study were to model the amorphous structure of the glass using the stochastic quenching method based on density functional theory as well as assessing the electrochemical stability of it against a metallic sodium electrode. Using VASP, a computational code based on density functional theory, we performed calculations of two 150 atom supercells, where the atoms were moved around until the systems were relaxed to obtain two glass models and the resulting structures were analyzed and characterized. The characterization of the structures was made by means of partial radial distribution functions, angle distribution functions, coordination numbers and bond lengths, which showed that the two models are statistically equivalent and either one can be used for the stability assessment of the glass. The electrochemical stability was assessed by inserting an extra sodium atom in possible holes in the glass model and calculating the energetics of Na insertion in each of these holes. This was made for 30 different hole positions. The reduction potential indicates the stability of each hole and the results was plotted as an energy distribution. Two peaks in the energy distribution, located at positive and negative energies, indicating stable and unstable holes, respectively. This indicates that the amorphous structure of the glass allows Na ions to travel (unstable holes). The stable peak has a greater probability density, which indicates a stable electrolyte against sodium metal electrode, though a larger sampling of holes is required for better statistics. / Ökande krav på energiefterfrågan uppmärksammar nya material för att förbättra nuvarande energilagringsteknik, med fokus på solida batterier och glaset Na3ClO som en lovande kandidat för elektrolyt. I denna rapport undersöks några av egenskaperna för glaset samt möjligheten för denna att fungera som elektrolyt i ett solid-state batteri. Målen med projektet var att modellera den amorfa strukturen av glaset genom att använda stochastic quenching method som baseras på density functional theory samt undersöka den elektrokemiska stabiliteten mot en metallisk natrium elektrod. Genom användning av VASP, beräkningskoder baserade på density functional theroy, beräknades två superceller med 150 atomer vardera där atomerna flyttas runt tills dess att systemet var relaxerat och två modeller av glaset erhölls. Dessa var sedan visualiserades och karakteriserade. Karakterisering av strukturerna gjordes genom en partiella radiella fördelningsfunktioner, vinkel distrubitionsfunktioner, koordinationsnummer och bindningslängder. Detta visade på statistisk ekvivalens, vilket innebär att båda modellerna kan användas för vidare stabilitetsundersökning. Den elektrokemiska stabiliteten undersöktes genom att sätta in en extra natrium atom i möjliga hål i glas modellen samt beräkna dess energier av Na insättning i respektive hål. Detta gjordes för 30 olika positioner för hålen. Reduktionspotentialen indikerar stabiliteten för respektive hål, och resultatet plottades som en energidistribution. Två toppar i energidistributionen, lokaliserade vid positiva och negativa energier, indikerar stabila respeltive instabila hål. Detta indikerar på att den amorfa strukturen för glaset tillåter Na joner att färdas (instabila hål). Den stabila toppen har en större sannolikhetstäthet vilket indikerar på en stabil elektrolyt mot en metallisk natrium elektrod, men en större samling hål krävs för en bättre statistisk säkerhet.

In the past few years, studies regarding new bio-based materials have led to an increased attention in the nanoscale product of cellulose, called nanocellulose. This biodegradable and renewable material has interesting physical, optical and thermal properties. The optical properties could be affected by tuning the nanostructure of the material, which makes it interesting for further investigation. The promising properties of nanocellulose can be useful in many different applications. The aim of this work was therefore to study the optical properties of nanocellulose, and to examine if the material is suitable for spectral design of camouflage or in passive cooling applications. The optical properties of a nanocellulose, specifically cellulose nanofiber (CNF), have been studied. Freestanding CNF films and CNF films deposited on glass substrates were made and characterized by spectroscopy, ellipsometry, BRDF measurements, and optical microscopy. The freestanding samples were examined with different CNF concentrations of 0.52% and 1.0%, and different thicknesses. The samples on glass substrates all had a concentration of 1.0% CNF, but with different amount deposited solution which was either drop or spin coated. The freestanding CNF samples show high transmission in the visual region and relatively high emissivity in the atmospheric windows. This implies that it can be used as an effective material for passive radiative cooling. A thicker sample could also be used to increase the emissivity in the atmospheric windows and improve the ability for passive cooling. The low reflectance, and high emissivity in the atmospheric windows can be promising for use in camouflage applications, according to earlier studies. However, the suitable properties are very dependent on the spectral response of the background. Additional measurements need to be performed and more specified scenarios are necessary to draw any further conclusions.

Machine learning is a growing topic with possibilities that seems endless with growing areas of applications. The field of metallography today is highly dependent on the operators’ knowledge and technical equipment to perform segmentation and analysis of the microstructure. Having expert dependents is both costly and very time-consuming. Some automatic segmentation is possible using SEM but not for all materials and only having to depend on one machine will create a bottleneck. In this thesis, a traditional supervised machine learning model has been built with a Random Forest (RF) classifier. The model performs automatic segmentation of complex microstructure features from images taken using light optical- and scanning electron microscopes. Two types of material, High-Strength-Low-Alloy (HSLA) steel with in-grain carbides and grain boundary carbides, and nitrocarburized steel with different amounts of porosity were analyzed in this work. Using a bank of feature extractors together with labeled ground truth data one model for each material was trained and used for the segmentation of new data. The model trained for the HSLA steel was able to effectively segment and analyze the carbides with a small amount of training. The model could separate the two types of carbides which is not possible with traditional thresholding. However, the model trained on nitrocarburized steel showcased difficulties in detecting the porosity. The result was however improved with a different approach to the labeling. The result implies that further development can be made to improve the model. / Maskininlärning är ett växande område där möjligheterna verkar oändliga med växande applikationsområden. Området för metallografi är idag till stor utsträckning beroende av operatörens kunskap och de tekniska instrumenten som finns tillgängliga för att genomföra segmentering och analys av mikrostrukturen. Viss automatisk segmentering är möjlig genom att använda SEM, men det är inte möjligt för alla material samt att behöva vara beroende av endast en maskin kommer skapa en flaskhals. I denna uppsats har en traditionell övervakad maskininlärnings modell skapats med en Random Forest klassificerare. Modellen genomför automatisk segmentering av komplexa mikrostrukturer på bilder från både ljusoptiskt- och svepelektron-mikroskop. Två olika typer av material, Hög-Styrka-Låg-Legerat (HSLA) stål med karbider och korngräns karbider, samt nitrokarburerat stål med varierande mängd porositet analyserades i detta arbete. Genom användningen av en särdragsextraktions bank tillsammans med annoterad grundsannings data tränades en modell för vartdera materialet och användes för segmentering av ny bild data. Modellen som tränades för HSLA stålet kunde effektivt segmentera och analysera karbiderna med en liten mängd träning. Modellen kunde separera de två typerna av karbider vilket inte varit möjligt med traditionellt tröskelvärde. Den modell som tränades för det nitrokarburerade stålet visade emellertid upp svårigheter i att detektera porositeten. Resultatet kunde dock förbättras genom ett annorlunda tillvägagångssätt för annoteringen. Resultatet vittnar om att vidareutveckling kan göras för att förbättra slutresultatet.