[diss] Kemian tekniikan korkeakoulu / CHEM

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    Sugar transport in Trichoderma reesei
    (Aalto University, 2024) Havukainen, Sami; Landowski, Christopher P., PhD, CTO, Onego Bio Ltd, Finland; Biotuotteiden ja biotekniikan laitos; Department of Bioproducts and Biosystems; Kemian tekniikan korkeakoulu; School of Chemical Technology; Frey, Alexander D., Prof., Aalto University School of Chemical Engineering, Department of Bioproducts and Biosystems, Finland
    Filamentous fungus Trichoderma reesei is well known for its high capacity to secrete proteins and is considered one of the most important fungal production hosts in the biotechnological industry. T. reesei has evolved to produce biomass-degrading enzymes as part of its saprotrophic lifestyle. These enzymes can be used in the production of second generation biofuels, which have been intensively studied as an alternative to fossil fuels. Similarly, the biomass-degrading enzymes of T. reesei and the improvement of their production, have been the subject of numerous studies. Less attention, however, has been paid to understand how T. reesei obtains nutrients, such as the various sugars released from the biomass by the aforementioned enzymes, from its environment. Transport of sugars across the cell membrane is crucial for many living organisms. Since sugars cannot simply diffuse through the membrane, their import is mediated by specialized transporter proteins. Although the genome of T. reesei has been predicted to code for many such proteins, only handful have been characterized in the literature. Given the wide variety of sugars derived from the biomass, many different sugar transporting activities are needed. Understanding of these processes would provide further insight into the physiology of this organism. Since the availability of sugars affects the production of biomass-degrading enzymes by T. reesei, the manipulation of sugar transport processes could be applied for strain improvement. The aim of this thesis was to characterize the most important members of T. reesei sugar transportome. Phylogenetics was employed to identify transporters for functional studies. Transporters were functionally characterized with two heterologous expression systems: yeast Saccharomyces cerevisiae and Xenopus laevis oocytes. Additionally, we manipulated the expression of some transporters in the native host to study their role in its physiology. This methodology allowed us to functionally characterize multiple T. reesei sugar transporters, including three which had not been described before. Importantly, we could demonstrate transport function for protein called CRT1, which has been shown to play a crucial role in the production of biomass-degrading enzymes. Another transporter, XLT1, was highly specific for L-arabinose and thus it could be potentially utilized for metabolic engineering of yeast for more efficient utilization of this sugar. Although expression of fungal sugar transporters in yeast is well-established, X. laevis oocytes have been seldomly used for this purpose. However, our results demonstrate that electrophysiological measurements which utilize X. laevis oocytes are powerful method for studying fungal sugar transporters. The obtained results provide valuable information about fungal sugar transporters. Unfortunately, we were not able to extend our analysis to study the roles of many of the identified transporters in T. reesei, or their applications to yeast metabolic engineering. There indeed remain many open questions to be answered by future studies.
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    Interfacial Adsorption and Stabilization of Nanopolysaccharides in Multifunctional Emulsion Systems
    (Aalto University, 2024) Zhu, Ya; Rojas, Orlando, Prof., Aalto University, Department of Bioproducts and Biosystems, Finland; Bai, Long, Dr., Aalto University, Finland; Siqi, Huan, Dr., Aalto University, Finland; Biotuotteiden ja biotekniikan laitos; Department of Bioproducts and Biosystems; Bio-based Colloids and Materials; Kemian tekniikan korkeakoulu; School of Chemical Technology; Rojas, Orlando, Prof., Aalto University, Department of Bioproducts and Biosystems, Finland
    This thesis explores the roles of biobased polysaccharide nanoparticles, including cellulose nanofibrils (CNF), cellulose II nanospheres (NPcats) and chitin nanofibrils (NCh), as stabilizers of emulsion systems. We demonstrate the potential application of these emulsions in the development of advanced materials. The thesis discusses phenomena relevant to colloidal behaviors and adsorption of nanopolysaccharides at oil/water and water/water interfaces, in the form of Pickering emulsions. Variables relevant to the emulsion behaviors, including the particle's interfacial wetting properties, hydrophilicity, functional groups, electrostatic charge, axial aspect ratio and entanglement were evaluated by complementary characterization platforms. The complexation of two oppositely charged nanopolysaccharides, CNF and NCh, were demonstrated to effectively stabilize oil-in-water Pickering emulsions with adjustable droplet size and stability against creaming and oiling-off, imparting long-term stability and remarkable environmental tolerance. Likewise, driven by electrostatic interactions, tuning the mass and charge ratio of NPcat and bovine serum albumin (BSA), the formation of a soft and dense NPcat/BSA layer, is shown to enable the formation of dense NPcat/BSA interfacial layers, stabilizing water-in-water emulsions. Furthermore, NCh was used to formulate high internal phase Pickering emulsions (HIPPEs) through pre-emulsification followed by continuous oil feeding that facilitated a "scaffold" with high elasticity, which arrested droplet mobility and coarsening, achieving edible oil-in-water emulsions with a high internal phase volume fraction (as high as 88%). These green Pickering emulsions offer potential in applications relevant to foodstuff, pharmaceutical, and cosmetic formulations. Direct ink writing (DIW) was applied as a platform to engineer biobased Pickering emulsions to extend their applications. The HIPPEs were easily textured by leveraging their elastic behavior and resilience to compositional changes, making them suitable for 3D printing edible functional foods via DIW. Additionally, we structured emulsion stabilized by NCh (50% oil fraction) through onestep processing into hierarchically and spatially-controlled porous structures defined by emulsion droplet size, ice templating, and DIW infill density. The obtained scaffolds are demonstrated for their excellent modulation of cell adhesion, proliferation, and differentiation, as tested with mouse dermal fibroblast expressing green fluorescent proteins. Taken together, the findings in this thesis are of interest in developing and understanding fundamental emulsion stabilization mechanisms and advancing practical applications. The obtained green Pickering emulsion systems are expected to have an important role in food emulsions, encapsulation, pharmaceuticals, (bio)catalysis, and advanced synthetic cell mimetics.
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    Evaluation of in vitro degradation and associated risks of novel biomaterials for implants
    (Aalto University, 2024) Bordbar-Khiabani, Aydin; Gasik, Michael, Prof., Aalto University, Department of Chemical and Metallurgical Engineering, Finland; Kemian tekniikan ja metallurgian laitos; Department of Chemical and Metallurgical Engineering; Materials Processing and Powder Metallurgy; Kemian tekniikan korkeakoulu; School of Chemical Technology; Gasik, Michael, Prof., Aalto University, Department of Chemical and Metallurgical Engineering, Finland
    The thesis explores innovative approaches to enhance the performance of orthopaedic metallic alloys by addressing the electrochemical behavior related to simulated post-implantation inflammatory conditions. The work comprises a detailed comparison between commercial purity titanium (Ti Group 2 alloy), Ti–6Al–4V alloy (Group 23) and novel Ti–Nb–Zr–Si (TNZS) alloy. Electrochemical studies include open circuit potential analysis, potentiodynamic polarization test, and electrochemical impedance spectroscopy (EIS), conducted in various media, mimicking normal, inflammatory, and severe inflammatory conditions. The major media differences were mimicked by varying concentration of H2O2, albumin, and lactate. The outcomes indicate i.a. a superior corrosion resistance of TNZS attributed to the presence of silicide phases. In addition, for Group 2 and Group 23 alloys this work examines the electrochemical behavior of additively manufactured (3D printed) patterned titanium layers made of titanium powder of the same composition. For this case, the results reveal an improved corrosion resistance in 3D patterned specimens compared to untreated titanium alloys surfaces. For analysis of more innovative methods of the improvement of the corrosion behavior of metallic alloys tantalum coated with trimanganese tetraoxide (Mn3O4) nanoparticles and 3D patterned titanium with alginate hydrogels laden with octacalcium phosphate (OCaP) particles were studies in these simulated inflammatory media. It was observed that electrophoretic deposition of Mn3O4 nanoparticles on anodized tantalum demonstrates superior corrosion protection for implants in acidic inflammatory conditions, and potential corrosion protection mechanism has been suggested, highlighting nanoparticles' catalytic activity and sealing role, offering valuable insights for developing corrosion-resistant implant materials. For hydrogel-coated titanium alloys, improved hydrophilicity and OCaP phase crystallinity were observed and an effective reduction of corrosion current density has been found, emphasizing the potential of such coatings to mitigate inflammatory-associated corrosion. This comprehensive work provides a combined understanding of metal alloys electrochemical behavior and corrosion resistance, offering novel insights and indicating potential advancements in biomedical materials for orthopedic and dental applications. The work was supported by EU Horizon 2020 project MSCA ITN "PREMUROSA" and has resulted in several peer-reviewed publications.
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    Conformality of atomic layer deposition analysed via experiments and modelling: case study of zinc oxide for catalytic applications
    (Aalto University, 2024) Yim, Jihong; Puurunen, Riikka L., Assoc. Prof., Aalto University, Department of Chemical and Metallurgical Engineering, Finland; Karinen, Reetta, D.Sc. (Tech.), Aalto University, Department of Chemical and Metallurgical Engineering, Finland; Kemian tekniikan ja metallurgian laitos; Department of Chemical and Metallurgical Engineering; Catalysis Research; Kemian tekniikan korkeakoulu; School of Chemical Technology; Puurunen, Riikka L., Assoc. Prof., Aalto University, Department of Chemical and Metallurgical Engineering, Finland
    Atomic layer deposition (ALD) has been used in various applications including microelectronics and heterogeneous catalysts. Ideally, ALD enables the growth of homogeneously distributed materials on solid supports including high aspect ratio (HAR) structures. However, to ob-tain conformal ALD coatings on HAR structures, process conditions should be optimized. The goals of this work were (i) to develop and apply a zinc oxide ALD process to prepare diverse copper-zinc oxide on zirconia catalysts for carbon dioxide hydrogenation into methanol and (ii) to investigate the effect of various process parameters on ALD conformality. Zinc oxide was added on mesoporous zirconia and alumina particles by the reaction of zinc acetylacetonate in a fixed bed ALD reactor. After the reaction, the remaining acac ligands were oxidatively removed in synthetic air at elevated temperatures. The reaction of zinc acetylacetonate on zirconia showed self-terminating behavior with the areal number density of zinc of approximately two atoms per square nanometer. The steric hindrance of bulky acac ligands was likely a saturation-determining factor for zinc obtained by ALD. Meanwhile, an eggshell-type zinc coating was obtained on alumina, and the zinc loading increased when the reactant dose increased. A diffusion–reaction model adapted to spherical supports was used to simulate the effect of reactant exposure on zinc loading. In the simulation, the zinc loading increased with an increase in the reactant exposure. The simulation results fit well with the experimental results. The zinc-after-copper catalyst was superior compared to other copper-after-zinc or copper-only catalysts for carbon dioxide hydrogenation into methanol. The current research showed the importance of tuning of the interaction of zinc and copper for catalytic performance and demonstrated the potential of zinc acetylacetonate as an ALD reactant. For future ALD conformality studies, a benchmark was proposed using an archetypical trimethylaluminum-water process on lateral HAR microchannels. The effect of process parameters on ALD thickness profiles was investigated using a diffusion–reaction model. For example, penetration depth into microchannels decreased with an increase in the molar mass of ALD reactant and growth per cycle (GPC). The trends of ALD thickness profiles in the free molecular flow regime and transition flow regime were illustrated. This work proposes that the free molecular flow regime and channel filling of less than 5% are the conditions required to obtain fingerprint thickness profile characteristics.
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    Structural Principles of A-site ordered double perovskites: ferroelectric CaMnTi2O6 as a model system
    (Aalto University, 2024) Albrecht, Elisabeth Katharina; Karttunen, Antti, Assoc. Prof., Aalto University, Department of Chemistry and Materials Science, Finland; Karppinen, Maarit, Prof., Aalto University, Department of Chemistry and Materials Science, Finland; Rautama, Eeva-Leena, Dr., Aalto University, Department of Chemistry and Materials Science, Finland; Kemian ja materiaalitieteen laitos; Department of Chemistry and Materials Science; Inorganic Materials Modeling; Kemian tekniikan korkeakoulu; School of Chemical Technology; Karttunen, Antti, Assoc. Prof., Aalto University, Department of Chemistry and Materials Science, Finland
    Perovskites are a broad and versatile class of crystalline materials. Their unique structure combined with the countless possible ionic combinations makes them highly tunable and gives rise to many possible properties such as piezo-, pyro-, and ferroelectricity as well as ferromagnetism and superconductivity. Double perovskites even enhance the possibilities of tuning the material. Perovskites as functional materials are used in many applications such as sensors and energy storage and the demand for new materials with tailored properties is still rising. Nowadays, many high-performing functional materials, such as the ferroelectric, perovskite-like material lead zirconate titanate (PZT) are made of harmful or rare elements. Using computational methods to find more sustainable materials and experiments to synthesize and analyze their properties is a major task for today's materials scientists. For this thesis, first principles hybrid density functional theory is used to computationally approach A-site double perovskites in general and CaMnTi2O6 in particular. High-pressure/high-temperature synthesis is used to synthesize bulk samples of Ca2-xMnxTi2O6 with x = 0.2 to 1.0 and single crystal samples of CaMnTi2O6 which are analyzed by powder and single crystal X-ray diffraction together with Rietveld refinement, scanning electron microscopy, ferroelectric measurements, and Raman spectroscopy. The predictive power of a new tolerance factor for A-site double perovskites is studied. While it still can be used as a starting point, the new tolerance factor does not perform as well for A-site double perovskites as it does for B-site double perovskites and simple perovskites due to possible large size differences in A-site ions. Computational methods to predict and confirm the cation ordering and tilt system in A-site ordered double perovskites, demonstrated on CaMnTi2O6, prove to be a suitable addition to the new tolerance factor. Structural changes, as well as changes in the dielectric (ferroelectric) behavior, determine the centrosymmetric to non-centrosymmetric symmetry transition in Ca2-xMnxTi2O6 to be around x = 0.3 and x =0.4. A synthesis of CaMnTi2O6 single crystals can be realized at lower temperatures and at lower pressures than previously reported.
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    Noble metal catalysts for the hydrodeoxygenation and hydrodenitrogenation of fatty amides
    (Aalto University, 2024) Verkama, Emma; Karinen, Reetta, Dr., Aalto University, Department of Chemical and Metallurgical Engineering, Finland; Tiitta, Marja, Dr., Neste Corporation, Finland; Kemian tekniikan ja metallurgian laitos; Department of Chemical and Metallurgical Engineering; Catalysis Research Group; Kemian tekniikan korkeakoulu; School of Chemical Technology; Puurunen, Riikka L., Assoc. Prof., Aalto University, Department of Chemical and Metallurgical Engineering, Finland
    The development of active catalysts for simultaneous hydrodeoxygenation (HDO) and hydrodenitrogenation (HDN) is important for the processing of renewable feedstocks to fuels. In this thesis, the hydrotreatment of fatty amides and their derivatives was studied on supported noble metal catalysts. Studies on competitive HDO and HDN reactions in the co-hydrotreatment of palmitic acid and 1-tetradecylamine over Pt/ZrO2 indicated that HDO proceeded more efficiently than HDN on all studied feed compositions. The preferential HDO of the oxygen-containing compounds and formation of secondary amides and amines via condensation reactions inhibited the HDN of 1-tetradecylamine in the co-hydrotreating experiments. The hydrotreatment of n-hexadecanamide was studied in a batch reactor at 300 °C and 80 bar H2, over Pt catalysts supported on SiO2, Al2O3, SiO2-Al2O3, TiO2, Nb2O5, ZrO2 and CeO2-ZrO2, as well as Pd, Rh, Ru and Ni supported on ZrO2. The Lewis acid properties of the support influenced the activity and selectivity towards the initial n-hexadecanamide conversion route, and the conversion of the oxygen-containing intermediate products. The oxygen-containing intermediate products were converted particularly efficiently on Pt/CeO2-ZrO2, which was attributed to the weak Lewis acid sites on the reducible support. The active metal influenced the activity and selectivity for condensation reactions and for the formation of n-pentadecane and n-hexadecane from the intermediate products. HDO proceeded more efficiently than HDN on the studied catalysts. Finally, monometallic and bimetallic catalysts supported on CeO2-ZrO2 were prepared, characterized and tested for their activity in the hydrotreatment of n-hexadecanamide. The catalytic properties of the bimetallic catalysts were markedly different compared to the corresponding monometallic catalysts, which, based on the characterization, appeared to be due to interactions between the active metals. The combination of Ni with a noble metal was particularly beneficial for the catalytic activity, and the RuNi/CeO2-ZrO2 catalyst exhibited the highest activity and selectivity towards the formation of n-pentadecane out of the catalysts studied in this thesis. The results of this thesis brought new insights into the influence of the catalyst composition on the activity, selectivity and reaction network in the hydrotreatment of fatty amides to n-paraffins.
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    Analytical ultracentrifugation as a tool to understand interactions in biomolecular materials
    (Aalto University, 2024) Fedorov, Dmitrii; Biotuotteiden ja biotekniikan laitos; Department of Bioproducts and Biosystems; Biomolecular Materials; Kemian tekniikan korkeakoulu; School of Chemical Technology; Linder, Markus, Prof., Aalto University, Department of Bioproducts and Biosystems, Finland
    The modern world dictates new rules and requirements for materials used in various applications. The development of human society has reached a point where, in addition to the requirements for good functional properties, the requirements for safety and sustainability of the materials are also increasing. Bio-based materials satisfy all these criteria. They are functional, sustainable, renewable and have a good mechanical properties. One of the most promising representatives is spider silk, the fibers of which are formed on the basis of triblock proteins. Spider silk stands out for its excellent mechanical properties. However, to achieve the properties similar to native spider silk using artificial analogues, a deep understanding of processes and interactions at the molecular level is required. In overall this is the true for any materials. The lack of the knowledge about molecular interactions is critical and significantly complicates the material development. It can be compared to forging a sword when one knows nothing about metal processing. Theoretically, it is possible to forge a sword that looks like a sword. Applying a lot of efforts, one even can make it beautiful. But most likely it will be either fragile or too soft, since the person does not know how to process it correctly. Applying even more efforts, after many attempts, one can find the conditions under which the sword would have the desired properties, but what if after sword it is needed to forge a horseshoe, for example. There could be different requirements for properties and all the process of searching the best conditions will be repeated all over again. However, knowing the rules of hardening and alloying of iron, everything would be much simpler. Absolutely the same situation occurs with biomaterials and intermolecular interactions. This work devoted to certain gaps in the understanding of protein interactions at the molecular level, how they affect intermediate states such as liquid-liquid phase separation (LLPS), shows the importance of understanding the interactions, and also demonstrates the capabilities of Analytical Ultracentrifugation (AUC) in combination with other techniques for material science application. Publication 1 demonstrates the effect of terminal domains on LLPS of engineered three-block spider silk proteins. The discovered patterns will serve for creation of coacervates with controlled properties. Publication 2 is devoted to the stability of NT-2Rep-CT, studying the component composition of NT-2Rep-CT solution and demonstrating the influence of the history of the sample on its properties and the observed state. Publication 3 investigated the dimerization of the CBM molecule and tested various methods for AUC data analysis. In publication 4, the shape of molecule of the CBM-AQ12-CBM protein was investigated using a combination of AUC and MD simulation. A similar approach was used in publication 5, where the polypeptides PLL and PGA were the objects of study. Solution composition, molecular weights and shape were determined.
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    Cellodextrin and β-D-1,3-glucan phosphorylases as biocatalysts for novel glucan structure synthesis
    (Aalto University, 2024) Pylkkänen, Robert; Penttilä, Merja, Prof., VTT Technical Research Centre of Finland, Finland; Biotuotteiden ja biotekniikan laitos; Department of Bioproducts and Biosystems; Synthetic Biology; Kemian tekniikan korkeakoulu; School of Chemical Technology; Penttilä, Merja, Prof., VTT Technical Research Centre of Finland, Finland
    Enzymatic synthesis of polysaccharides is a relatively new field of science which combines innovative materials with the biological precision of enzymes. The publications presented in this thesis demonstrate that enzyme-catalyzed reactions can be utilized to produce unique carbohydrate-based materials. The work focuses on enzymatic synthesis of cellulose and β-1,3-glucan with phosphorylase enzymes, aiming at the same to influence the structural properties of the produced polysaccharides for example by adjusting reaction conditions and performing the reactions with the enzyme's native and non-native glycosyl acceptors. Publication 1 focuses on a recombinantly produced cellodextrin phosphorylase from Clostridium thermocellum bacteria and its application in in vitro cellulose synthesis. The most relevant findings of this work were that the length of the synthetic cellulose polymers as well as their structural properties of the cellulose fibrils that formed, could be influenced based on the initial concentration of the glycosyl acceptors. These results lead towards tailored cellulose materials that can be used in different applications. Utilizing similar methodology, in publication 2 we investigated β-1,3-glucan synthesis with a recombinantly produced β-1,3-glucan phosphorylase. When the synthesis reactions were carried out at certain temperatures, unique layered hexagonal particles were produced. These results improve our understanding on the structural behaviour of triple-helical β-1,3-glucans and broaden the range of enzymatically synthesizable carbohydrate-based structures. Publication 3 broadens the scope of polysaccharide synthesis by utilizing chromophoric glycosyl acceptors as substrates for enzymatic synthesis reactions, which makes it possible to attach color molecules covalently to the structures that are formed as a product. This approach adds color molecules to the list of application areas for enzymatically synthesized materials and improves their attractability. Together, this research improves our understanding on the mechanisms of phosphorylase-catalyzed polysaccharide synthesis and leads towards tailored biomaterials. The implications of this research are far-reaching, and they have potential applications in smart materials, biocompatible and functional materials among other. This thesis highlights the broad potential of glycoside phosphorylases in biomaterial science and lays the groundwork for developing tailored carbohydrate-based materials.
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    Recovering Cobalt from Aqueous Solutions by Evaporative, Reactive, and Cooling Crystallization
    (Aalto University, 2024) Zhang, Jianxin; Louhi-Kultanen, Marjatta, Prof., Aalto University, Department of Chemical and Metallurgical Engineering, Finland; Lindberg, Daniel, Prof., Aalto University, Department of Chemical and Metallurgical Engineering, Finland; Kemian tekniikan ja metallurgian laitos; Department of Chemical and Metallurgical Engineering; Chemical Engineering in Aqueous System; Kemian tekniikan korkeakoulu; School of Chemical Technology; Louhi-Kultanen, Marjatta, Prof., Aalto University, Department of Chemical and Metallurgical Engineering, Finland
    With the challenge of climate change, the restructuring of transportation and power sectors is crucial for achieving greenhouse gas neutrality. Cobalt, which plays a key role in the energy transition, has been recognized as one of the critical materials globally. The hydrometallurgical process has shown great potential in extracting cobalt from both primary and secondary resources during cobalt manufacture. Recovering cobalt from aqueous solutions is an essential step in the hydrometallurgy process of cobalt extraction. Crystallization is a separation and purification technology by forming solids from solutions. In this study, the recovery of cobalt salts from aqueous cobalt sulfate solution using vacuum evaporative crystallization, cooling crystallization, and carbonate precipitation was investigated. The thermodynamic data includes the saturation vapor pressure for cobalt sulfate solution and the cobalt sulfate solubility in aqueous solutions was determined. The effects of operational conditions on crystallization and final products were indicated by recovering cobalt sulfate through vacuum evaporative crystallization, batch, and continuous cooling crystallization. At temperatures below 40 °C, cobalt sulfate primarily crystallizes in the heptahydrate form, while at temperatures of 60 and 80 °C, it crystallizes in the hexahydrate form. The CoSO4∙7H2O is prone to dehydration during the drying process. Additionally, the primary nucleation kinetics of CoSO4 were determined by measuring the solubility, metastable zone width (MSZW), and induction time in batch cooling crystallization. The secondary nucleation dominated crystal kinetics for cobalt sulfate in a continuous cooling crystallization were also investigated based on the Mixed-Suspension, Mixed-Product-Removal (MSMPR) theory, and Population balance equations (PBEs). In addition, operation conditions like temperature, mixing speed, and impurities significantly affect the crystal size and crystallization kinetics.  In the cobalt carbonate precipitation, the precipitation mechanism was successfully investigated using inline Focused Beam Reflectance Measurement (FBRM) and pH monitoring and offline measurement (Scanning electron microscope, X-ray powder diffraction, Raman spectroscopy). With the pH decreasing, the cobalt initially precipitated as Co2CO3(OH)2 and continuously transferred to CoCO3.  Raman spectrometry has been found to a great potential in studying the crystallization of metal salts for both solid phase identification and ionic concentration quantification. Moreover, UV-Vis spectrophotometry is efficient for the quantitative analysis of cobalt and nickel concentrations in solutions.
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    A Methodology for Systemic Plant Research: An Industrial Case Study Investigating the Effects of Water Quality on Pentlandite Flotation Recovery
    (Aalto University, 2024) Musuku, Benjamin; Heiskanen, Kari, Prof. Emer., Aalto University, Minerals Engineering, Finland; Saari, Eija, PhD, Ecosystem & Innovation Lead Metso, Finland; Biotuotteiden ja biotekniikan laitos; Department of Bioproducts and Biosystems; Kemian tekniikan korkeakoulu; School of Chemical Technology; Dahl, Olli, Prof., Aalto University, Department of Bioproducts and Biosystems, Finland
    The dynamicity and complexity of the recycled process water quality present mineral recovery challenges to the mining industry. Concentrator plant operations are usually optimized using an engineering-centric optimization approach. However, the impact of climate change on the recycled process water quality and pulp chemistry is overlooked. The Kevitsa concentrator plant has shown a cyclic nickel recovery pattern that coincides with the summer seasons. This thesis aims to show how process optimization and related methodologies need to evolve from an engineering-centric approach towards systemic thinking to enable the step change toward a more resilient conversion of mineral resources. This study is structured around the case of the Kevitsa concentrator plant's poor pentlandite recovery during the summer months and is divided into three main parts (a) reviewing the impact of flowsheet modifications and equipment installation, and showing the limitation of the engineering-centric approach, (b) studying the impact of process water quality on electrochemical reactivity of sulphide ore using artificially generated process water from D-loop protocol, and highlighting the gap between laboratory-based studies and plant-based studies, and (c) defining and applying the methods, techniques, and protocols for systemic plant based research on Kevitsa concentrator plant. This study demonstrates the inadequacy of the widely adopted engineering-centric optimization approach. Flowsheet reconfiguration and equipment installation alone are not sufficient to address process water quality effects on valuable mineral recovery. Systemic optimization approach is needed to encompass the effects of climate change on process water quality. The laboratory study has shown that the electrochemistry of the pulp strongly depends on the quality of the recycled process water and the residence time of the ore in the process. Such laboratory studies are not representative enough to mimic real process plant conditions, and as a result, are not able to predict water properties that arise due to process water connecting with the hydrological and climatic setting of the tailing storage facility (TSF). Protocols containing analytical and measurement methods to study the electrochemistry of pulp in the context of an operating concentrator plant are defined in this study. Such protocols allow for a systemic investigation at a plant scale and help to relate the dynamic water property matrix to changes in the mineral surface reactivity and further to plant recovery values. The study has shown that the cyclic variation in ore reactivity is driven by seasonal changes in the physicochemistry of recycled process water which consequently influences the extent of ore oxidation during milling and mineral surface passivation during flotation, resulting in a 20% loss in nickel recovery. The study shows that the process water recycled through the TSF differs significantly from the process waters within the flotation circuits. The knowledge acquired from this dissertation presents protocols and methods that can be used to carry out plant-based studies in optimising the process.
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    Synthesis and structure-property correlations of polyurethanes for additive manufactured biomedical materials
    (Aalto University, 2024) Farzan, Afsoon; Baniasadi, Hossein, Dr., Aalto University, Department of Chemical and Metallurgical Engineering, Finland; Lipponen, Sami, Dr., Aalto University, Department of Chemical and Metallurgical Engineering, Finland; Borandeh, Sedigheh, Dr., Aalto University, Department of Chemical and Metallurgical Engineering, Finland; Kemian tekniikan ja metallurgian laitos; Department of Chemical and Metallurgical Engineering; Polymer Technology; Kemian tekniikan korkeakoulu; School of Chemical Technology; Seppälä, Jukka, Prof., Aalto University, Department of Chemical and Metallurgical Engineering, Finland
    In recent decades, 3D printing has gained substantial attraction in the field of tissue engineering (TE) scaffold fabrication due to its exceptional precision, convenient manufacturing conditions, and rapid production capabilities. Among the various techniques, stereolithography (SLA) and direct ink writing (DIW) are the most applicable techniques in this field. However, the availability of biodegradable and biocompatible synthesized polymers, particularly from the polyurethane (PU) family, remains limited for the purpose of 3D printing. The primary objective of this research was to develop biodegradable and biocompatible PUs, encompassing both isocyanate-based and non-isocyanate-based (NIPUs) polyurethanes. These polymers were specifically designed for applications in nerve and skin regeneration. A solvent-free approach was utilized to synthesize photo-cross linkable PU resins, effectively applied for the SLA technique. Furthermore, the incorporation of PEGylated graphene oxide nanoparticles into the resin composite was executed to confer conductivity, a crucial attribute for scaffolds intended for nerve regeneration. Then the nerve guidance conduits (NGCs) were printed with very precise geometry by SLA. Additionally, a novel generation of isocyanate-free PUs was successfully synthesized utilizing six distinct diamines. This endeavor aimed to investigate the correlation between polymer structure and resultant properties. Based on the chemical and physical characteristics of the synthesized NIPUs, a specific variant containing cystamine (NIPU-Cys) was identified for further exploration in 3D printing applications. To enhance its properties, the chosen polymer was combined with an antibacterial chitosan derivative, synthesized by a doctoral researcher within the Polymer Technology Research Group at Aalto University (Isabella Lauren). This antibacterial hydrogel composite was effectively 3D printed using the DIW technique, presenting the potential for wound healing applications.
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    Investigation of Thermodynamics and Kinetics of Nitrogen Behavior in Steel Melts for Improved Nitrogen Control in the AOD Process when Producing Nitrogen-Alloyed Stainless Steels
    (Aalto University, 2024) Pitkälä, Jyrki; Holappa, Lauri, Prof. emerit., Aalto University, Department of Chemical and Metallurgical Engineering, Finland; Kemian tekniikan ja metallurgian laitos; Department of Chemical and Metallurgical Engineering; Kemian tekniikan korkeakoulu; School of Chemical Technology; Jokilaakso, Ari, Prof., Aalto University, Finland
    Stainless steel is a fundamental pillar of a developed society, without which our current way of life would not be possible. Stainless steels consist of several alloying elements, of which chromium is the key component regarding corrosion resistance. Nickel, molybdenum, and even manganese also play important roles in influencing the corrosion resistance, mechanical properties, machinability, and usability of stainless steel. Nitrogen has two functions in steels. In ferritic steels, nitrogen is considered a harmful impurity, whereas in austenitic and duplex stainless steels it often serves as a beneficial alloying element. Nitrogen stabilizes the austenitic structure, reducing the need for nickel, and enhances corrosion resistance and mechanical properties. However, its role and acceptable levels vary depending on the steel grade, and even minor changes in content can impact the steel properties. In stainless steelmaking, the argon oxygen decarburization (AOD) converter plays a central role and is primarily responsible for alloying and controlling nitrogen content. The ultimate objective of this work was to develop models for improved nitrogen control in the AOD converter, which is why all the experiments and measurements were carried out in an industrial AOD converter. First, the influence of different alloying elements and temperature on the equilibrium solubility of nitrogen at one-bar nitrogen pressure was investigated. This led to the development of a novel mathematical formula, which includes updated interaction parameters between nitrogen and the main alloying elements. Second, the applicability of Sieverts' law in the AOD Converter was investigated, and provided evidence supporting the idea that the nitrogen content in molten steel can be controlled by adjusting the nitrogen partial pressure in the process gases. Furthermore, to achieve a target nitrogen content in the AOD converter, a comprehensive understanding of the factors influencing the kinetics of nitrogen content change is crucial. On this account, both nitrogen absorption and desorption rates were investigated in several test series. Finally, the thermodynamic-kinetic models developed in this work were tested across a wide range of alloy compositions and nitrogen contents ranging from 0.150% to 0.400%. The results demonstrated that nitrogen content can be accurately predicted using these models. As a result of this work, equations for predicting nitrogen content can be integrated into the control models of the production process to enhance accuracy in achieving the target nitrogen range. These equations enable improved productivity of the AOD converter for nitrogen-alloyed steel grades. Additionally, when the nitrogen content does not need to be further regulated by reblowing, gas costs and quality losses can be reduced.
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    Exploring silk protein assembly mechanisms for high-performance materials
    (Aalto University, 2024) Välisalmi, Teemu; Linder, Markus, Prof., Aalto University, Department of Bioproducts and Biosystems, Finland; Biotuotteiden ja biotekniikan laitos; Department of Bioproducts and Biosystems; Biomolecular Materials; Kemian tekniikan korkeakoulu; School of Chemical Technology; Linder, Markus, Prof., Aalto University, Department of Bioproducts and Biosystems, Finland
    Silk proteins present remarkable potential as the building blocks for high-performance materials. Due to their unique protein structure, they exhibit a variety of properties, such as a combination very high tensile strength and elasticity, biodegradability, biocompatibility, and ability to be spun in natural conditions — qualities uncommon in synthetic fibres. While challenging to acquire through natural means, the application of gene engineering allows to produce substantial quantities of recombinant silk proteins. However, the assembly pathways leading to the formation of functional materials remain largely unknown, with the evidence suggesting that crucial insights lie within the intricate spinning mechanism of silk-producing animals. Publication 1 delves into an investigation of the native spinning system of Bombyx mori silkworm. Amino acid mapping throughout the middle silk gland revealed a gradual change in various amino acids, attributed to the increase in different sericin proteins. This change correlated with the extensional behaviour of the silk dope, which was further enhanced by a straightforward pH modification inspired by the native spinning system. Publication 2 introduces a more sophisticated silk pulling device designed for controlled pulling and tensile testing, with a focus in automation. The device was employed to pull fibers from regenerated silk solution. Although immune to the pH induced dimerization due to irreversible changes by the regeneration, the fibroin fibers displayed a considerable median tensile strength of 147 MPa. In addition, a recombinant silk protein was observed to preassemble at an air-water interface, allowing pulling of thin fibers from droplets of silk. Liquid-liquid phase separation was found to be a significant factor in creating stronger fibers, demonstrating the necessity of controlling this intricate aspect of molecular assembly. Not limited to fibers, silk proteins find application as building blocks for films. Publication 3 details the development of a simple deposition method to create highly hydrophobic silk films. These films, characterized by the arrangement of intrinsically hydrophobic regions of the silk protein, formed in the presence of a specific salt concentration and high relative humidity during drying. Notably, the phenomenon was not strictly dependent on the silk protein sequence or the type of salt, although certain variations displayed superior performance. The films were altered by wetting, disrupting the interaction between the silk and salt. Although the lack of durability limits applicability of the silk films, this work demonstrates the versatile nature of the amphiphilic silk proteins.
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    Matte–slag interaction simulation in the flash smelting settler using coupled CFD-DEM
    (Aalto University, 2024) Jylhä, Jani-Petteri; Jokilaakso, Ari, Prof. Emeritus, Aalto University, Department of Chemical and Metallurgical Engineering, Finland; Kemian tekniikan ja metallurgian laitos; Department of Chemical and Metallurgical Engineering; Metallurgy; Kemian tekniikan korkeakoulu; School of Chemical Technology; Jokilaakso, Ari, Prof. Emeritus, Aalto University, Department of Chemical and Metallurgical Engineering, Finland
    The flash smelting process is a major copper production method. However, a closed furnace with high temperatures makes physical observations of matte settling through the slag physically impossible and, thus, computer simulations are needed to study settling. Previously, settling simulations have been made using computational fluid dynamics (CFD). In this project, a new method of using coupled CFD-DEM (discrete element method) was developed and used to study copper matte droplets in a flash smelting settler. Traditionally, CFD-DEM is a fluid and solid particle simulation method; however, by simulating soft spheres and creating user-defined submodels for coalescence and reaction kinetics, liquid matte droplets settling through a slag layer could be studied. Due to the impossibility of observing a high-temperature process in situ, a room temperature physical model was needed to validate the chosen simulation method. Plastic spheres were fed into an oil bath, in which their settling was filmed and compared to simulation results of the same system. Both the experiments and the simulation produced a channeling flow, where drag from the settling spheres pulls the flow of droplets into a narrow channel, accelerating the settling velocity significantly. However, at the bottom of the oil, the flow turns sideways and then up, forming a vortex ring around the channel, which may entrain slowly settling objects. Several matte–slag simulations were made with CFD-DEM, utilizing either the coalescence model or the combined coalescence and reaction kinetics model. Channeling flow, similar to the sphere–oil experiment and simulation, occurred with every matte–slag simulation. The flow caused the matte droplets to settle through the slag significantly faster than predicted by Stoke's law. The coalescence and reaction kinetics models further accelerated the matte droplets as coalescence increased the size of the droplets while reaction kinetics caused copper to concentrate in the droplets as iron and sulfur were removed, which increased droplet density. The coalescence rate was increased by the channeling flow as it caused the droplets to enter a narrower channel, causing an increased number of collisions and, thus, coalescence.
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    Tailoring the properties of polysaccharides-based hydrogels - From cell interactions to biomedical applications
    (Aalto University, 2024) Teixeira Polez, Roberta; Valle-Delgado, Juan José, Aalto University, Department of Bioproducts and Biosystems, Finland; Morits, Maria, Aalto University, Department of Bioproducts and Biosystems, Finland; Biotuotteiden ja biotekniikan laitos; Department of Bioproducts and Biosystems; Bioproduct Chemistry; Kemian tekniikan korkeakoulu; School of Chemical Technology; Österberg, Monika, Prof., Aalto University, Department of Bioproducts and Biosystems, Finland
     This thesis focused on developing polysaccharides-based hydrogels designed to closely mimic the properties of the human extracellular matrix (ECM) through innovative 3D biofabrication techniques. While nanocellulose hydrogels have shown promise in the fields of biomedical engineering and regenerative therapy, they face challenges related to poor mechanical properties and limited 3D printing resolution. To overcome these challenges, nanocellulose was combined with heteropolysaccharides (tragacanth gum, xanthan gum, and quince seed mucilage). This strategic combination enhanced the processability of the hydrogels by improving their viscosity and shear-thinning behavior, ensuring smooth extrusion and deposition through the printing nozzle. These hydrogels closely resemble the scaffolds typically used in biomedical applications in terms of their porosity, pore size, and porous structure. Additionally, adjusting the nanocellulose content enabled tailoring the stiffness and swelling of the hydrogel, allowing further optimization according to the specific intended application. Furthermore, the study explored controlled drug delivery, particularly the development of chitosan (CS) hydrogels enriched with the phenolic compound phloroglucinol (PG). These hydrogels exhibited versatility, as they could be prepared with varying porosities and morphologies, resulting in distinct release kinetics. This versatility positions them as suitable biocompatible scaffolds and drug delivery systems, particularly for applications like wound dressing. In addition, the research delved into the molecular-level interactions between biomaterials and living cells using advanced Atomic Force Microscopy-based techniques such as colloidal probe microscopy (CPM), and single-cell force spectroscopy (SCFS). These results revealed insights into cell-biomaterial and cell-cell interactions, shedding light on adhesion protein dependencies and cellular behaviors within different biomaterial environments. In summary, this study advanced polysaccharides-based hydrogels for biomedical applications, combining innovative fabrication strategies with a deep understanding of molecular-level interactions. The findings have the potential to significantly impact biomedical research, paving the way for high-performance functional materials in various biomedical domains.
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    Studies on phenomena involved in impregnation of industrial wood chips
    (Aalto University, 2024) Määttänen, Marjo; Tikka, Panu, Prof., Finland; Biotuotteiden ja biotekniikan laitos; Department of Bioproducts and Biosystems; Kemian tekniikan korkeakoulu; School of Chemical Technology; Dahl, Olli, Prof., Aalto University, Department of Bioproducts and Biosystems, Finland
    In chemical pulping, cooking chemicals are used to dissolve lignin in wood to release the fibres from the wood tissue. Chemicals must be present in the parts of the wood tissue where delignification takes place before the cooking temperature is reached, as otherwise the quality of the pulp will suffer. The transport of the cooking chemicals takes place by two mechanisms. Penetration fills the fibre cavities with liquid under a pressure gradient enabling faster diffusion of the chemicals into the wood. Diffusion refers to the movement of ions through a liquid from a higher concentration to a lower concentration. Although both mechanisms occur in parallel, their separate and combined influences on impregnation have been seldom studied in the same research. The objectives of this thesis were to clarify and deepen the understanding of the impregnation of industrial chips and the phenomena occurring in the course of impregnation. Therefore, a new experimental method was developed. The experiments were divided into penetration and impregnation experiments. The data collected from the experiments were combined for calculating corrected penetration degree values and the mass and alkali balance involved in impregnation. Based on the data, quantitative results and deeper understanding for impregnation were achieved. The research work confirmed the three defined hypothesis dealing with the influence of the physical properties of industrial chips and the processing conditions on impregnation and the influence of the chemical diffusion and the dissolution of wood on the degree of penetration. Practical outcomes and guidelines for the impregnation of the industrial wood chips were the following. The moisture content and the basic density of wood chips determine the initial penetration degree (PDi) of wood chips: a low basic wood density and a low moisture content result in higher amounts of air inside the wood, which means a lower initial penetration degree of the wood. The lower PDi hinders the whole impregnation process. Therefore, it is recommended to use pre-steaming as a common practice and more emphasis must put on the use of fresh/moist wood chips.The prerequisites for fast diffusion are a high degree of penetration and a high concentration gradient between impregnation liquor and the alkali inside wood chips. On a laboratory scale, for high-concentration liquor, 15 minutes of impregnation time is sufficient for an adequate alkali charge for kraft cooking, but in the case of low-concentration liquor, even 60 minutes is insufficient. Part of the impregnated alkali is consumed during the impregnation, and more at higher temperature. Therefore, there is risk of running out of alkali if the temperature is raised quickly to the cooking temperature after low alkali impregnation. For successful impregnation, proper pre-steaming, a low impregnation temperature and moderate alkali concentration should be used for all wood species.
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    Highly active catalytic cathode and selective separator for elevated temperature lithium oxygen batteries
    (Aalto University, 2024) Qiu, Qianyuan; Pan, Zhengze, Asst., Prof., Tohoku University, Japan; Kemian tekniikan ja metallurgian laitos; Department of Chemical and Metallurgical Engineering; Research Group of Industrial Chemistry; Kemian tekniikan korkeakoulu; School of Chemical Technology; Li, Yongdan, Prof., Aalto University, Department of Chemical and Metallurgical Engineering, Finland
    Energy plays a vital role in the development of industry and human daily life. Various energy storage technologies have been investigated to meet the demands. Particularly, lithium oxygen battery (LOB) is a uniquely high energy density storage device. Theoretically, LOBs with Li2O2 and Li2O as the discharge products deliver energy densities as high as 3500 Wh kg−1 and 5200 Wh kg−1, respectively. LOB with molten salt electrolyte operating at elevated temperatures is developed which facilitates the reversible 4e−/O2 conversion to achieve Li2O as the discharge product. The molten salt electrolyte relieves the side reactions for the cases with organic solvent in the electrolyte and carbon as the component of the cathode. However, the electrochemical perfor-mance of this LOB still needs optimization. To achieve the high catalytic activity and long-term stability targets, highly active cathode catalyst and effective separator for the LOB operating at elevated temperature are the key enablers. In this work, LaNi0.5Co0.5O3 (LNCO) perovskite was introduced as the LOB cathode catalyst. The physical properties and catalytic activity of LNCO were investigated with different characterization and computational techniques. Moreover, the superior performance of LOB with LNCO cathode operating at 160 °C was demonstrated. A LNCO cathode prepared with a sol-gel method enabled a LOB with an energy efficiency as high as 98.2% and an ultra-low overall overpotential of 50 mV. The preparation of LNCO was further investigated, and a sample prepared with a coprecipitation method with nanostructure effectively reduced the amount of catalyst used to a level as low as 1 mg cm−2 with delivering comparable performance of the LOB. A LOB with a self-supported LNCO@Ni cathode achieved a long-term stability, running for 834 cycles with a 94% capacity retention. The Li2O as discharge product and the corresponding reaction pathways are also confirmed. A metal-organic framework (MOF) based membrane was employed as the separator for the LOB operating at 160 °C. The battery ran stably for over 180 cycles with a coulombic efficiency as high as 99.9%. The membrane not only provided sufficient Li+ transfer rate but also effectively impeded the cross over of discharge product during operation. The LOB with a highly active cathode catalyst and effective separator exhibited good electrochemical performance and stability at elevated temperature. The results also indicate that the LOB operating at elevated temperature is a potential strategy for future development.
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    Exploring structural diversity in quorum sensing signalling systems and strategies to control prokaryotic community-wide behaviour
    (Aalto University, 2023) Jonkergouw, Christopher; Biotuotteiden ja biotekniikan laitos; Department of Bioproducts and Biosystems; Biomolecular Materials Research Group; Kemian tekniikan korkeakoulu; School of Chemical Technology; Linder, Markus B., Prof., Aalto University, Department of Bioproducts and Biosystems, Finland
    Bacteria, despite being single-celled organisms, have the ability to establish intricate communities where individual cells collaborate for the collective benefit. This cooperative behaviours and spatial organization are facilitated by cell-to-cell communication mediated by quorum sensing (QS). Within these communities, bacteria engage in diverse cooperative activities, including the regulation of biofilm formation, virulence, production of antimicrobials, nutrient sharing, and defence against external challenges. The remarkable adaptability and resilience exhibited by bacteria in these communities underscore the significance of intercellular communication and collaboration, even in the most basic organisms. In this work, we studied the function of various QS signalling systems and explore how having control over QS communication, can be utilized towards several biotechnological applications. First, we theoretically explored the wide diversity in QS signalling systems and use novel computational tools to understand how QS signalling systems interact with one another. These predictions were used to experimentally investigate a set of 10 QS signalling systems, among which we identified six fully complementary QS signalling systems. Then, we investigated strategies to control and disrupt communication in bacterial pathogens that utilize QS to regulate their virulence during infections. We further studied the potential of QS disruption as a potent strategy to combat antibiotic resistance bacteria, both in vitro and in vivo. Finally, we explored novel microfluidic culturing techniques to build microbial communities in a bottomup approach. In this, QS signalling was utilized to coordinate the behaviour of distinct populations acting within the community. From these studies, we improved upon the method and developed a novel 2-photon polymerization technique to enable stable microbial communities of bacteria consisting of four individual populations. In summary, QS signalling systems play a crucial role in facilitating coordinated behaviours among bacteria, enabling them to act collectively as a group. Here, we show that by harnessing the power of QS, we can exert control over bacterial communities and shape and functionalize their collective behaviour.
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    CFD modeling of multiphase flows in bottom blown copper smelting furnace
    (Aalto University, 2023) Song, Kezhou; Jokilaakso, Ari, Prof., Aalto University, Department of Chemical and Metallurgical Engineering, Finland.; Kemian tekniikan ja metallurgian laitos; Department of Chemical and Metallurgical Engineering; Kemian tekniikan korkeakoulu; School of Chemical Technology; Jokilaakso, Ari, Prof., Aalto University, Department of Chemical and Metallurgical Engineering, Finland.
    The advancement of copper production techniques has witnessed significant developments, with the continual emergence of new copper smelting and converting equipment and processes. The application of Bottom Blown Copper Smelting (SKS, ShuiKouShan) technology has attracted increasing attention since its introduction into production. To reveal the dynamics of agitation within the bath and optimize the variable parameters, Computational Fluid Dynamics (CFD) simulations were conducted on scaled-down and industrial-scale models of SKS furnaces, with various furnace structures and operating conditions. In this modeling research, the Multi-Fluid Volume of Fraction (Multi-Fluid VOF) model wasemployed for the first time in the simulation of SKS furnaces. The simulated results were in good accordance with experimental water models concerning the gas plume geometrics and surface wave characteristics. The numerical model employed exhibits significant potential for broader applicability, not only within the domain of SKS furnaces but also for similar industrial vessels characterized by comparable geometry and gas flow regimes. The simulation results presented the persistent rotation of gas plumes, accompanied by thepresence of low-velocity regions on the opposite side of the plumes. To enhance agitation within these low-velocity regions and minimize the dead zones, it is favorable to install tuyeres on both sides of the furnace bottom centerline. Subsequent investigations revealed that maintaining a certain range for the difference in tuyere angles between the two rows of tuyeres strikes a balance between the enhancement of agitation performance and the extension of refractory lining lifespan. Apart from tuyere arrangements, tuyere diameter and bath depth emerged as influential factors in bath agitation performance. A relatively reduced tuyere diameter and a deeper bath are suggested to enhance fluid motion within the low-velocity regions, thereby improving mixing behavior. While melt density was observed to exert a relatively modest influence on bath agitation, it was noted that lower melt viscosity contributes to enhanced melt fluidity, improved agitation performance, and a weakened impact on refractory lining. It is noteworthy that copper bottom blown smelting technologies have undergone extensive optimization through resource-intensive onsite experiments, without systematic theoretical guidance. Conclusions derived from the simulation presented in this thesis offer valuable references for industrial practice, presenting diverse fundamental principles governing the bath flow field. Furthermore, the CFD modeling provides the industry with important modeling information, as the furnace structure parameters were selected from a commonly employed range, thereby ensuring the usefulness of the simulation results for broad application in SKS furnaces.
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    Thin films of self-assembled materials by dip-coating technique
    (Aalto University, 2023) Nguyen, Hoang M.; Vapaavuori, Jaana, Prof., Aalto University, Department of Chemistry and Materials Science, Finland; Kemian ja materiaalitieteen laitos; Department of Chemistry and Materials Science; Multifunctional Materials Design; Kemian tekniikan korkeakoulu; School of Chemical Technology; Vapaavuori, Jaana, Prof., Aalto University, Department of Chemistry and Materials Science, Finland
    Self-assembly processes, which manifest in various natural phenomena, involve the constituents merging to construct intricate and well-structured material systems. Motivated by nature's elegance, synthetic self-assembled materials have experienced remarkable progress over the past two decades, facilitating the creation of structures spanning diverse length scales, ranging from the molecular level to larger macromolecular systems and microscale particles. An essential determinant for the practical application of self-assembled materials lies in the ability to fine-tune their self-assembly behavior, within which various complex physicochemical processes can take place. Among the techniques for depositing self-assembled thin films, dip-coating emerges as a particularly promising candidate. It shares the simplicity and expediency of drop-casting and spin-coating, while retaining the exceptional control over film thickness characteristic for layer-by-layer deposition. Moreover, it offers unrestricted substrate shape and size as well as permits the minimization of solution waste. Dip-coating, therefore, appears as an ideal approach for generating self-assembled thin films. Nevertheless, research efforts in this area remain limited, and a thorough comprehension of the interplay between dip-coating parameters and self-assembly behavior remains elusive. This thesis attempts to fill this knowledge gap by expanding the scope of materials combining dip-coating and self-assembly process. The thesis begins with an extensive review of the dip-coating technique, followed by distinct chapters exploring the self-assembly of various materials, including block copolymers, breath figure, and virus nanoparticles. Within these chapters, the thesis strives to establish systematic relationship between dip-coating parameter and the behavior of the specific material, thereby providing valuable insights that can steer future research in this field.