The evolving science of astrobiology for the search for life beyond Earth has put focus on the possibility of subsurface bodies of liquid water beneath the surface of icy moons within our Solar System. Specifically, the Jovian moon of Europa and the Saturnian moon of Enceladus show telling characteristics of endogenous heating through their complex tidal resonances with their parent planets – suggesting the presence of oceans of liquid water and therefore a potential for astrobiology. Today, the planning of upcoming satellite missions to guarantee the identification of completely unknown, possibly habitable environments has become an intriguing task for space agencies worldwide. A method of guidance, ground-truthing, debugging and testing of the viability of planned satellite missions is to utilize relatively accessible analogue environments on the Earth. Fortunately, the research of Antarctic subglacial water environments has been acknowledged as the most suitable analogues to the environments of Europa and Enceladus. Given its recorded motions of ice dynamics, erosion, complex thermal systems, and occasions of sampled microbes within – these sensitive, exotic environments beneath the Antarctic ice bed are currently assessed for their suitability as habitats for extremophilic microorganisms, which may provide important insights into the potential existence of habitats, perhaps even life, on icy moons. Ultimately, viable lessons can be drawn from the research of Antarctic subglacial environments given the uncovering of reliable sanitary methodologies that are going to be required during future approaches and sampling of natural systems of extraterrestrial subglacial environments in order to minimize irreparable anthropogenic disturbances on any potential astrobiology. Regardless of the question if the future investigation of Europa’s and Enceladus environments is going to reveal astrobiology within beneath their icy surfaces; this investigation is going to be of invaluable information for the improving familiarity of physical systems beyond Earth. / Sedan länge har forskare vetat att flytande/rinnande vatten är en av de viktigaste förutsättningar för allt liv på Jorden. Under de senaste decennierna har frågan om liv på Jupiters måne Europa, och Saturnus måne Enceladus aktualiserats, efter upptäckten av frusna islager på deras månytor. Evidens från respektive månars omloppsbanor, gör att forskare idag tror att månarnas djupa islager hettas upp inifrån av en aktiv, inre geologi, vilket i sin tur kan tyda på större mängder av flytande vatten. I och med omvandlingen av is till flytande vatten, får detta forskare att tro att cirkulationen av vatten, ihop med den aktiva geologin, möjligtvis har skapat och upprätthåller beboliga förutsättningar för mikroskopiskt liv. I dagsläget planeras ett flertal satelliter skjutas upp till månarna med uppdrag att bekräfta fallet om flytande vatten och beboliga miljöer på månarna, och därmed även undersöka frågan om månarna möjligtvis bär på liv. På den frusna kontinenten Antarktis har ett flertal motsvarande subglaciala miljöer undersökts för att fastställa deras kvalifikationer att upprätthålla liv under extrema levnadsförhållanden. Under dessa undersökningar har ett flertal mikroorganismer påträffats i prover från iskärnor från två subglaciala sjöar (Vostoksjön och Whillanssjön), varav några blivit omstritt påstådda som inhemska extremofiler. Ifall detta stämmer, betyder det att de två subglaciala sjöarna underhålls av ett unikt samspel av drivande faktorer som upprätthåller de nödvändigaste levnadsförutsättningarna för att mikroorganismer kan överleva, även frodas i uppenbart extrema miljöförhållanden. Med forskningen av Antarktis subglaciala sjöar som rapporterar ett unikt samspel mellan is, vatten och underliggande geologi; kan den fortsatta fastställningen av detta fysiska samspel, samt vidare identifikationer av inhemska mikroorganismer att bli en viktig lärdom för framtida satelliters datainsamling av subglaciala vattenmiljöer på Europa och Enceladus. För att underlätta och effektivisera sökandet efter potentiella livsmiljöer, samt möjligtvis hitta utomjordiskt liv på isiga månar bör framtidens satellituppdrag dra stor lärdom och väga in de erfarenheter och resultat som gjorts på subglaciala sjöar i Antarktis.

The application of chemical additives, known as grinding aids (GA), dates back to 1930 in the cement industry. As opposed to the cement industry, where the use of GAs is on the final processing step, it could be one of the first process steps in ore beneficiation. A few investigations addressed the GA applications in ore dressing; therefore, further studies are required to better understand the GA effects on the product properties and downstream separation processes. This thesis undertakes a comparative study on the dry grinding of magnetite and the resulting product characteristics with and without GAs. The main aim is to reduce energy consumption and to address some of the challenges associated with dry processing.  The effects of GAs on the dry batch ball milling of magnetite were examined to analyze the energy consumption (Ec), particle size distribution, flow properties, bulk properties, surface morphology, particle fineness, and surface chemistry of products. Their effects on the ground product were systematically explored by sieve analysis, powder rheology, BET surface measurements, optical microscopy analysis, and zeta potential measurements. Compared with the absence of GAs, the dry grinding efficiency of magnetite increased after using GAs; however, an optimal dosage exists based on the GA type. Among GAs which considered in this investigation (Zalta™ GR20-587 (Commercial GA) and Zalta™ VM1122 (Commercial viscosity aid) as well as sodium hydroxide), Zalta™ VM1122, a polysaccharide-based additive, was the most effective GA where by using this GA; the Ec decreased by 31.1% from 18.0 to 12.4 kWh/t. The PSD became narrower and finer (P80 decreasing from 181 to 142 µm), and the proportion of the particles (38–150 µm) increased from 52.5 to 58.3%. In general, the results reveal that at sufficient GA dosages, they reduce the average particle size, increase the specific surface area, and narrow the particle size distribution. However, an excessive amount of GAs could be detrimental to the grinding performance.  Further studies on powder rheology indicated that the used GAs resulted in improved material flowability compared to grinding without additives (in the examined dosage range). The rheology measurements by the FT4 Powder Rheometer showed strong linear correlations between basic flow energy, specific energy, and the resulting work index when GAs was considered for grinding. There was a strong correlation between the grinding parameters and flow parameters (r > 0.93). These results confirmed the effect of GA on ground particles' flowability. Zalta™ VM1122 showed the best performance with 38.8% reduction of basic flow energy, 20.4 % reduction of specific energy, 24.6% reduction of aerated basic flow energy, and 38.3% reduction of aerated energy. The present investigation showed that the predominant mechanism of GAs is based on the alteration of rheological properties. Further investigation on the surface properties showed that using GAs could increase the surface roughness, which is beneficial for downstream processes such as froth flotation. Zalta™ VM1122 resulted in increased surface roughness and minimum microstructural defects from the optical microscope images. Furthermore, Zalta™ VM1122 (non-ionic) resulted in similar zeta potentials and pH values for the product compared to experiments without GA. These comparable product properties are advantageous as they minimize any potential negative effects on all possible downstream processes. / Kolarctic CBC (KO1030 SEESIMA)

Geographic space is not neutral or lifeless, but an intricate living structure composed of numerous small features and a few large ones across all scales. The living structure is crucial for comprehending how geographic space shapes human activities. With the emerging geospatial big data, researchers now have unprecedented opportunities to study the relationship between geographic space and human behaviour at a finer spatial resolution. This thesis leverages multisource geospatial big data, including Twitter check-in locations, street networks from OpenStreetMap, building footprints, and night-time light images, to explore the fundamental mechanisms of human activities that underlie geographic space. To overcome the limitations of conventional analytics in this era of big data, we propose the topological representation and living structure based on Christopher Alexander's conception of space. We utilize scaling and topological analyses to reveal the underlying living structure of geographic space with various big datasets. Our results demonstrate that tweet locations or human activities at different scales can be accurately predicted by the underlying living structure of street nodes. We also capture and characterize human activities using big data and find that building footprints and tweets show similar scaling patterns in terms of sizes of their spatial clusters. We also propose an improved spatial clustering method to increase the processing speed of geospatial big data. Finally, we adopt topological representation to identify urban centres by the fusion of multi-source geospatial big data. The living structure, together with its topological representation can help us better understand human activities patterns in the geographic space at both city and country levels.

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