Silicon quantum dots were synthesised wet-chemically by three different methods based on reduction of silicon tetrachloride with the reduction agents potassium naphthalide, sodium cyclopentadiene and the alkalide of potassium. The purpose of these quantum dots was to deposit them on a substrate in order to use them as down converters on top of photovoltaic solar cells for enhanced solar cell efficiency. One possible method for the formation of down converting layers is to incorporate quantum dots into silica thin films by deposition of quantum dots in an ethanol based silica sol, followed by spin coating. It is believed that when the quantum dots are water dispersible, this will make it easier to bind them to the silica network, and a good dispersion in the film is facilitated. The different hydrophilic functionalisations investigated were pentenoxy capping, oxidised pentenoxy capping, oxidised acrylic acid capping and ethanolamine capping. Challenges were encountered during the synthesis of water dispersible quantum dots, the most important were related to agglomeration and purification of the quantum dots. This was believed to be due to the tendency of hydrophilic surface groups to attract each other, interaction with the polar solvent and similar solubility characteristics of the quantum dots and the byproduct salts.Si quantum dots with hydrophobic octoxy capping were also synthesised. Dispersions of these quantum dots were deposited onto solid substrates followed by solvent evaporation. This was done to see whether it was possible to deposit the synthesised quantum dots by this simple approach, to investigate the fundamentals upon evaporation, the degree of agglomeration and the byproducts present in the quantum dot dispersions. It was found that agglomeration was very pronounced after the solvent had evaporated and that quite large amounts of byproducts were present in the final quantum dot dispersions. The most important reasons to this were believed to be too weak steric repulsive forces between the particles, too fast evaporation of the solvent and an insufficient purification procedure. For the use of Si quantum dots synthesised wet-chemically as down converters in solar cells, improvements of the particles are needed.

This work explores the hydrothermal synthesis of LaFeO3 (LFO) nanorods with a high aspect ratio. Synthesis of rod shaped LFO is a stepping stone to the synthesis of strontium doped LFO (LSF) nanorods with high aspect ratio. These LSF rods can be used to structure and increase the area of dense LSF oxygen permeable membranes, which can be applied in the partial oxidation of methane for the production of synthesis gas. Obtaining a larger surface area can increase the oxygen transport through the membrane when the transport is limited by surface exchange reactions. Increasing the oxygen transport is the objective of the work. LFO was attempted synthesised by a direct and a two-step synthesis. Product morphology and phase composition have been explored by the use of SEM and XRD. In the direct synthesis the effect of potassium hydroxide concentration, molar ratio of iron to lanthanum and synthesis duration were varied to investigate the effect of these parameters. LFO was not produced in the direct synthesis; the products consisted of La(OH)3 and Fe2O3. Since LFO was not obtained, a calculation exploring the temperature where LFO become more stable than La(OH)3 and Fe2O3 was performed. The calculations show that the transition temperature where LFO is thermodynamically favoured is close to the operating synthesis temperature. The small driving force for formation of LFO at a temperature close to the transition temperature is the reason why LFO have not formed in the direct syntheses.The two-step method consists of hydrothermal synthesis of La(OH)3 nanorods, which were covered by iron nitrate solution and attempted converted into LFO by a topochemical reaction. In the study performed, the rod structure is lost when the product is calcined at 400 ºC. LFO is not observed formed at this temperature, and LFO nanorods were therefore not obtained in the two-step synthesis.

A thermal barrier coating (TBC) is used as thermal protection of metallic components exposed to hot gas streams in e.g. gas turbine engines. Due to a high thermal expansion coefficient, low thermal conductivity, chemical- and thermal stability, yttria stabilized zirconia (YSZ) is the most widely used material for TBCs today. In the work presented in this master thesis an aqueous nitrate precursor solution was prepared and deposited on stainless steel substrates by spray pyrolysis to produce 8YSZ coatings (8 mol% of Y2O3 in ZrO2). The precursor solution concentration and deposition parameters, including set-point temperature and volume sprayed, were optimized to produce continuous and crack-free green coatings.The deposited green coatings were characterized by scanning electron microscopy, thermogravimetry and Fourier transform infrared spectroscopy to study the influence of substrate temperature on the microstructure of the green coatings. A substantial change in microstructure was observed for the green coatings in a certain temperature range indicating that a minimum deposition temperature was necessary to obtain crack-free green coatings.Heat treatment was necessary to decompose the nitrate species in the deposited film. During heat treatment, vertical cracks were introduced into the coatings due to the nitrate decomposition. The cracking behavior of the coatings was studied for different drying times and conditions, and it was found that the crack propagation can be controlled to obtain the preferred size and geometry of the cracks. Due to built-up stresses in the coating, which can exceed the fracture toughness of the material, it was found that there was a maximum film thickness achievable before spallation of the coating for a given precursor solution. Therefore, the possibility of spraying multi-layered coatings was investigated. The introduction of a second layer showed that it was possible to double the thickness of the coating.

A study of the effect of various amounts of manganese in solid solution on the recovery and recrystallization behavior of an AlMn-alloy, for different annealing conditions after different degrees of deformation (cold rolling) has been carried out. The alloy studied was a 3xxx-type model alloy with 0.5 wt% Fe, 0.15 wt% Si and 1.0 wt% Mn. The studies were a contribution to the MOREAL-project, where the main objective is to quantify and characterize the softening behavior of recyclable aluminium alloys, with small amounts of manganese, iron and silicon, as a basis to validate and further develop the ALSOFT-model. 5 variants of the AlMn-alloy, with respect to strain and homogenization, were prepared and further investigated.Based on electrical conductivity measurements the different amounts of Mn in solid solution, after the different homogenization (hom.) treatments, were estimated to be approximately 0.85 wt% (as cast), 0.55 wt% (hom. nr. 2) and 0.49 wt% (hom. nr. 3). The reductions of Mn in solid solution by hom. nr. 2 and hom. nr. 3 resulted in less concurrent precipitation and consequently a larger effective driving force for recovery and recrystallization. The high amount of Mn in solid solution for the as cast variants resulted in much concurrent precipitation. Concurrent precipitation was found to delay and suppress the recovery and recrystallization processes. At high annealing temperatures, with no (or little) concurrent precipitation occurring, the recrystallised grain structures were found to be homogeneous, fine grained and consisting of equiaxed grains. In these cases the recrystallised textures were found to be approximately random after a strain of 0.7, while they showed cube textures of weak and medium strength after a strain of 3.0. At low annealing temperatures, with concurrent precipitation occurring, the recrystallised grain structures were found to be inhomogeneous and coarse grained, with grains elongated in the rolling direction. In these cases the recrystallised textures were found to consist of P-textures and ND-rotated cube textures of medium and high strength.A high degree of deformation was found to increase the rate and degree of the recovery and recrystallization processes during the isothermal annealing procedures, and to result in fine recrystallised grain structures, consistent with the increased effective driving force for recovery and recrystallization. A high degree of deformation was also found to increase the rate and magnitude of precipitation during the isothermal annealing procedures.Non-isothermal annealing experiments were carried out to investigate if they could result in significantly different grain structures and textures compared to the isothermal annealing experiments. No significantly different results were achieved, only results directly comparable to the results from the isothermal annealing experiments.

The economical feasibility of commercial, single-junction solar cells is limited by high costs and limited efficiencies. New solar cell concepts and materials are sought to decrease the production costs and increase the efficiency. Intermediate band solar cells (IBSCs) show a promising concept for increased efficiency up to 46.77% as they employ three band gaps that can be matched to the solar spectrum to minimize fundamental losses. Doping of copper gallium disulphide (CuGaS2) with transition metals like Fe and Ni to high concentrations can theoretically form an intermediate band (IB), which for Fe doping gives nearly optimal band gaps for IBSC applications. Copper gallium disulphide is synthesized in an environmentally friendly, inexpensive and simple hydrothermal synthesis which may contribute to decreased costs of solar cell production.The hydrothermal synthesis is developed to produce copper gallium disulphide from copper(I) chloride (CuCl), gallium(III) chloride (GaCl3) and excess thiourea (Tu) (SC(NH2)2) in deionized water. The influence of varying synthesis parameters on product purity, yield and morphology has been investigated through X-ray diffraction (XRD) and scanning electron microscopy (SEM). Energy dispersive X-ray spectroscopy (EDS) is used to investigate doping of copper gallium disulphide and identify particle morphologies formed by different phases. Formation of copper gallium disulphide proceeds through slow decomposition of Tu, driven by an equilibrium shift due to hydrogen disulphide (H2S) evolution and precipitation of sulphides like the intermediate phase digenite (Cu2-δS) into which Ga3+ ions are incorporated. An additional impurity of copper(II) sulphide (CuS) is commonly formed, and gallium(III) hydroxyoxide (GaO(OH)) forms at pH > 0.5. Products of high purity and yield are obtained at 250 °C with concentrations above 0.060 M copper(I) chloride and gallium(III) chloride with the complexing agent 1-pentanethiol, and 0.319 M without 1-pentanethiol. Introducing nickel(II) chloride (NiCl2) or iron(III) chloride (FeCl3) in the hydrothermal synthesis forms vaesite (NiS2) or iron pyrite (FeS2) impurities, respectively, and copper gallium disulphide is not doped to a desirable concentration for IB formation.Color variations in the products reveal off-stoichiometries which contribute to a wide range of particle and crystallite morphologies within each product. Yellow, stoichiometric copper gallium disulphide particles have been deposited on a Si(100) substrate and growth of a red, Ga-rich film was achieved with 1-pentanethiol. These products were subject to photoluminescence spectroscopy (PL) along with off-stoichiometric powders of doped and undoped products, but no luminescence was obtained, possibly due to high defect densities and non-radiative recombination. Dispersions of powders were also subject to absorption spectroscopy which indicate extensive scattering due to wide ranges of particle sizes. The morphology of powder products shows particularly large variations within and between the products. Nanoplate and pyramidal crystallites are produced through nucleation and growth to form network structures and polycrystalline spheres, rods and rose-like particles, which along with the crystallites have varying irregularities and sizes.

There are currently no standard test methods for testing the cathodic disbonding properties of organic coatings at temperatures above 100 C. There are several subsea oil and gas reservoirs with high temperatures, some as high as 200 C. The main goal of this work was the development of a new apparatus and testing procedure for high temperature cathodic disbonding, hereby referred to as HTCD (High Temperature Cathodic Disbonding).A test method for the cathodic disbonding of organic coatings from submerged steel subjected to high temperatures was studied. The test method requires the use of a specialized HTCD apparatus. In this test method, sample plates were mounted between two channels, one containing a hot (150 C) oil flow and the other containing a pressurized, cold, salt (3.5 % NaCl) water flow. Accelerated conditions made it possible to test the cathodic disbonding properties of several coatings in four weeks. Four weeks is a typical duration for coating prequalification tests. Several commercial coating products of different generic types provided by different manufacturers were tested. The results indicate that adequate coating products for high temperature underwater exposure are available.The required cathodic protection current for the samples tested in the HTCD apparatus was continuously monitored. No correlation between the required cathodic protection current and the extent of cathodic disbonding was observed.A long term test with more field like conditions and a duration of 400 days was performed. Low levels of disbonding for most of the tested products in the 400 day test made comparison to the accelerated tests difficult.An attempt was made to determine the oxygen diffusion coefficient of five coating products. The attempt was unsuccessful. The same method had previously been used to study coatings with a thickness of up to 300 micro m, the coatings studied in this work were between 600 micro-metres and 1200 micro-metres. It remains uncertain whether the chosen method can be used for coatings this thick.Results from electrochemical impedance spectroscopy, performed in a pressurized vessel, showed a large reduction in the ionic resistance of a submerged organic coating upon heating from 30 C to 150 C. This showed that elevated temperatures throughout the coating can reduce the ionic resistance to a level where even an intact coating is incapable of protecting the substrate. Studies of coating samples at ambient temperatures after exposure to higher temperatures showed that exposure to heat causes a lasting reduction in impedance. High impedances correlated with good performance in the HTCD tests.Investigation with a scanning electron microscope (SEM) provided images where the extent of the cathodic disbonding was clearly visible. Electron-dispersive X-ray spectroscopy (EDS) enabled the identification of oxides discovered at the holiday and beneath the disbonded coating. Zinc and calcium oxides were identified at and near the holiday; iron oxide was identified beneath the disbonded coating.

Tap hole refractories constitute critical parts of the refractory lining in submerged arc furnaces. For several hours every day, molten slag and metal flow through the tap hole calling for thorough selection of refractory materials able to withstand the intense thermal, corrosive and erosive conditions present in this area. Carbon-based refractories have shown excellent thermal properties and high strength, as well as low wettability towards process materials, and are therefore utilized in silicomanganese production furnaces both as side lining, in the hearth, and in the tap hole area. The aim of this investigation was to determine the compatibility of five refractory materials utilized in the tap hole area of an industrial silicomanganese furnace with two industrial silicomanganese slags: •Investigate the suitability of the selected refractory materials for confining the process materials during industrial production of silicomanganese alloys. •Identify critical refractory wear mechanisms upon slag-refractory interaction at industrial tapping temperatures.Compatibilities were investigated through 12 static crucible tests and two static plate tests in a vertical tube furnace redesigned during this investigation. Slag-refractory interaction was studied after two and four hours holding time at 1367°C ± 1.8°C, 1464°C ± 2.1°C and 1600°C - 0.6°C /+ 0.2°C. Holding temperatures were verified through the wire-bridge method at the melting points of gold and palladium. Visual inspection, as well as optical microscopy and SEM, were utilized to examine the samples after heat treatment.During compatibility experiments, dissolution of refractory matrix due to solubility of oxide refractory binder phases in silicomanganese slags was observed, as well as disintegration of refractory particles due to gas formation at slag-refractory interface, or expansion as a result of phase transformations in refractory material. Direct reduction of manganese oxide from slags and iron oxide present in refractories by carbon and silicon carbide was also observed. Establishment of partial slag-metal equilibriums between iron oxide and silicon metal originally present in slag was observed, as well as formation of silicon carbide at the slag-refractory interfaces. The latter may serve to protect the refractory from wear caused by slags.Based on observations of extensive interaction between silicomanganese slag sample I and ramming paste at 1600°C, the ramming paste investigated cannot be recommended for usage during tap block repair in an industrial silicomanganese furnace. Incipient electrode paste disintegration by slags and silicon carbide tap block – slag interaction were observed after compatibility tests at 1464°C, calling for further investigations of these refractory materials. Tap hole clay and carbon tap block showed minimal signs of interaction with process materials at 1464°C. Refractory porosity seemed to have a larger effect on refractory wear than refractory ash content. Contrary to industrial observations, silicomanganese slag sample I was more corrosive towards the ramming paste and electrode paste investigated than silicomanganese slag sample II.

The aim of this thesis was to create an understanding between the electrochemical performance of a porous Ni-CGO anode used in SOFC, and its microstructural parameters when subjected to redox-cycling. The anode samples were produced consisting of two different layers, and subjected to different number of redox-cycling. Their electrical resistance was measured using electrochemical impedance spectroscopy (EIS), and their parameters were obtained by analyzing cross-section images from the samples obtained by the focused ion beam (FIB) or from simulated 3D-models. A large increase of Ohmic resistance was observed after 3-4 redox-cycles, while there was only a slight increase of the polarization resistance. The high increase of the Ohmic resistance is believed to be due to the observed Ni-coarsening and the net increase of the anode volume due to oxidation of Ni to NiO and subsequently reduced back to Ni. Both the Ni-coarsening and the net volume expansion decrease the Ni connectivity which increases the Ohmic resistance. More electrons are also forced to go through the lower-conducting CGO phase, which increases the Ohmic resistance, though preventing a higher increase since it is connecting the isolated Ni grains together. The low increase of polarization resistance is believed to be due to the large pore-CGO interfacial area, which compensates for the decrease in triple-phase boundaries (TPB). The resolution of synthetic microstructures is not enough to capture constrictivity and tortuosity effects realistically. The dimensions of most of the bottle necks are below 100 nm and hence the size classes must be in the range of 10 nm, which is similar as the resolution of FIB-tomography.

Proteases are found in all living kingdoms and are absolute essential for a functional cell to beable to break down peptide bonds. Metacaspases are proteases with the ability to cleave afterarginine and lysine residues. Research that has been done so far on a specific subgroup ofmetacaspases called Metacaspase-IIf from Arabidopsis thaliana (AtMCA-IIf), has shown thatan autocleavage is necessary for the activation process and it will then start to degrade itself.In this project the amino acids which is necessary for the activation and degradation ofAtMCA-IIf has tried to be identified. Based on the predictions of an already determined crystal structure, mutations were produced to generate a more long-lived enzyme. Biochemicalstudies involving activity-and stability assays were performed to get a better understanding ofthe wild type and mutant. The amino acids thought to have an important role in these processes turned out to not have the effect on the enzyme as was predicted, but the experimentsalso did show interesting results.

An unexpected biological removal of phosphorous in IVL Hammarby Sjöstadsverket pilot membrane bioreactor (MBR) wastewater treatment process was investigated by three distinct methods. a) Investigation and quantification of the biological phosphorous uptake (bio-P) capacity by phosphate release tests (PRT), b) validation of bio-P occurrence by granular polyphosphate (poly-P) staining and microscopy and c) metagenomic community structure analysis to map the sludge habitat. Validation of phosphate accumulating organisms (PAO) was successfully performed using the Neisser Methylene Blue Metachromatic staining protocol. Quantification by a novel staining protocol gave indications of the relative activity of bio-P in the bioreactor process line. The bio-P activity by PRT showed high capacity of phosphate accumulation in the treatment process. Furthermore, the use of ethylenediaminetetraacetic acid (EDTA) to induce stressful conditions was successfully shown to increase the release rate and depletion of intracellular poly-P of PAO. Finally, the impact of temperature dependency in PRT was investigated.A metagenomic community structure analysis by 16S rRNA successfully prepared 28 samples for sequencing and analysis. The project has successfully validated and quantified bio-P with an improved methodology as a foundation for upcoming studies of the treatment process. / En oväntad biologisk fosforrening (bio-P) i IVL Hammarby Sjöstadsverkets membranreaktorpilot undersöktes med tre distinkta metoder. Kvantifiering av det biologiska fosforupptaget undersöktes med fosforsläppstest (PRT). Validering av förekomsten av fosfatackumulerande organismer (PAO) via infärgning av polyfosfatgranuler med Neissers protokoll för infärgning med metylenblå. Ett nytt protokoll för kvantifiering av polyfosfatgranulkluster gav indikationer på relativ aktivitet av bio-P i reningsprocessens bioreaktorer. Bio-P aktiviteten som uppmättes med PRT visade på hög kapacitet av biologisk fosforackumulation. Vidare visades framgångsrikt att stresspåslag av PAO med etylendiamintetraättiksyra (EDTA) ökade fosfatsläppshastigheten och uttömningen av intracellulär poly-P. Slutligen undersöktes temperaturberoendet i PRT. En 16S rRNA metagenomikstudie gav 28 st prover redo att sekvensieras och analyseras. Projektet har framgångsrikt validerat och kvantifierat bio-P med en utvecklad metodologi som kan utgöra grunden för kommande studier vid reningsverket.