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Anthropogenic global warming is actively changing nutrient supply and the food web of the Arctic Ocean and the subpolar regions. This study uses the stable isotopes of dissolved silicon and nitrate, two vital nutrients for marine life, to investigate the marine biogeochemical cycling of nutrients in these regions. This work analyses datasets acquired from 7 oceanographic expeditions in three key regions: the Laptev Sea shelf, polar outflow waters of the Fram Strait (79˚N) and a full transect across the subpolar North Atlantic (50-60˚N). Hydrographic data, alongside concentrations of nitrate (NO3), dissolved silicon (DSi) and their isotopic composition (d15N-NO3, d18O-NO3, d30Si(OH)4) is presented to provide spatially and temporally integrated information on biogeochemical cycling in these regions. The overall objective of this work is to determine the processes which control nutrient budgets and cycling in the Arctic Ocean, export to the subpolar regions and the sensitivity of these processes to ongoing climate change. On the shallow Eurasian shelves of the Arctic Ocean, nitrogen is strongly depleted. This results from intense biological utilisation and significant benthic denitrification in the coastal regions, coupled with nitrogen-poor freshwater sources. Primary production in these regions is limited by N availability as a result of this. This puts a biological control on the extent of DSi utilisation in surface waters and modulates its export to the central Arctic Ocean. Over 40% of riverine DSi supplied by the Lena river is consumed and buried into the sediments of the Laptev shelf, enabled by vigorous recycling of nitrogen. Extrapolating these burial rates to the Eurasian shelf leads to an excess riverine DSi export of 3.10 ± 0.71 kmol/s through the Transpolar Drift to the central Arctic Ocean and outflowing currents. Consequently, Eurasian rivers significantly contribute to the DSi inventory of outflow polar surface waters, providing 40 ± 4% of the total DSi. By contrast, Pacific sources, which were previously estimated to be an important source of export of DSi, only contribute to 8 ± 1% of the total inventory. Glacial DSi influence from melting of the Greenland Ice sheet was found to be negligible. The Si budget is thus primarily controlled by biological processes on Arctic shelves, which currently act to enrich the d30Si(OH)4 outflowing water masses by 0.1‰ compared to Atlantic inflow (1.7‰). Climate change is increasing riverine inputs of DSi faster than N. As the export of DSi from the Arctic Ocean is dependent on N-availability, outflow waters could transport a larger flux of DSi in the future, with lowered isotopic signature. In the subpolar North Atlantic, nutrient properties of surface waters are integrated into the deep through convective water mass formation. Thus, biological assimilation and regeneration of nutrient stocks at high and low latitudes impact the nutrient inventory of North Atlantic deep waters. Surface waters of the North Atlantic have lighter d30Si(OH)4 (1.7‰) than predicted considering its nutrient deplete nature. Important processes at low latitudes act to dilute DSi concentrations of Atlantic surface waters and dampen their isotopic signature. This signal is integrated with the one of heavily utilised surface waters from the subpolar regions and the Nordic Seas into the deep North Atlantic. In recent years, deviation of the Labrador Current to the subpolar North Atlantic has reduced N assimilation. The freshwater content of the subpolar regions is predicted to increase from increased glacial melt and freshwater supply. This can act to increase stratification and decrease primary production of the region in the future. Due to the interconnectivity of the subpolar regions on the global scale, this can be reflected into the deep convective waters of the Atlantic and affect nutrient availability in the Eurasian Arctic.

Polarimetric synthetic aperture radar (PolSAR) has been widely used in ocean and cryospheric applications. This is because, PolSAR can be used in all-day operations and in areas of cloud cover, and therefore can provide valuable large-scale monitoring in polar regions, which is very helpful to shipping and offshore maritime operations. In the last decades, attention has turned to the potential of PolSAR to detect icebergs in the Arctic since they are a major hazard to vessels. However, there is a substantial lack of literature exploring the potentialities of PolSAR and the understanding of iceberg scattering mechanisms. Additionally, it is not known if high resolution PolSAR can be used to detect icebergs smaller than 120 metres. This thesis aims to improve the knowledge of the use of PolSAR scattering mechanisms of icebergs, and detection of small icebergs. First, an introduction to PolSAR is outlined in chapter two, and monitoring of icebergs is presented in chapter three. The first data chapter (Chapter 4) is focused on developing a multi-scale analysis of icebergs using parameters from the Cloude-Pottier and the Yamaguchi decompositions, the polarimetric span and the Pauli scattering vector. This method is carried out using ALOS-2 PALSAR quad polarimetric L-band SAR on icebergs in Greenland. This approach outlines the good potential for using PolSAR for future iceberg classification. One of the main important outcomes is that icebergs are composed by a combination of single targets, which therefore may require a more complex way of processing SAR data to properly extract physical information. In chapter five, the problem of detecting icebergs is addressed by introducing six state-of-the-art detectors previously applied to vessel monitoring. These detectors are the Dual Intensity Polarisation Ratio Anomaly Detector (iDPolRAD), Polarimetric Notch Filter (PNF), Polarimetric Matched Filter (PMF), reflection symmetry (sym), Optimal Polarimetric Detector (OPD) and the Polarimetric Whitening Filter (PWF). Cloude-Pottier entropy, and first and third eigenvalues (eig1 and eig3) of the coherency matrix are also utilised as parameters for comparison. This approach uses the same ALOS-2 dataset, but also evaluates detection performance in two scenarios: icebergs in open ocean, and in sea ice. Polarimetric modes (quad-pol, dual-pol, and single intensities) are also considered for comparison. Currently it is very difficult to detect icebergs less than 120 metres in length using this approach, due to the scattering mechanisms of icebergs and sea ice being very similar. However, it was possible to obtain detection performances of the OPD and PWF, which both showed a Probability of Detection (PF) of 0.99 when the Probability of False Alarms (PF) was set to 10-5 in open ocean. Similarly, in dual pol images, the PWF gave the best performance with a PD of 0.90. Results in sea ice found eig3 to be the best detector with a PD of 0.90 while in dual-pol mode, iDPolRAD gave a PD of 0.978. Single intensity detector performance found the HV channel gave the best detection with a PD of 0.99 in open ocean and 0.87 in sea ice. In the previous two approaches, only satellite data is used. However, in chapter six, data from a ground-based Ku-band Gamma Portable Radio Interferometer (GPRI) instrument is introduced, providing images that are synchronised with the satellite acquisitions. In this approach, the same six detectors are applied to three multitemporal RADARSAT-2 quad pol C-band SAR images on icebergs in Kongsfjorden, Svalbard to evaluate the detection performance within a changing fjord environment. As before, we also make use of Cloude-Pottier entropy, eig1 and eig3. Finally, we evaluate the target-to-clutter ratio (TCR) of the icebergs and check for correlation between the backscattering coefficients and the iceberg dimension. The results obtained from this thesis present original additions to the literature that contributes to the understanding of PolSAR in cryospheric applications. Although these methods are applied to PolSAR and ground-based radar on vessels, they have been applied for the first time on icebergs in this thesis. To summarise, the main findings are that icebergs cannot be represented as single or partial targets, but they do exhibit a collection of single targets clustered together. This result leads to the fact that entropy is not sufficient as a parameter to detect icebergs. Detection results show that the OPD and PWF detectors perform best in an open ocean setting and using quad-pol mode. These results are degraded in dual-pol mode, while single intensity detection is best in the HV cross polarisation channel. When these detectors are applied to the RADARSAT-2 in Svalbard, the OPD and PWF detectors also perform best with PD values ranging between 0.5-0.75 for a PF of 0.01-0.05. However, the sea ice present in the fjord degrades performance across all detectors. Correlation plots with iceberg size show that a regression is not straightforward and Computer Vision methodologies may work best for this.

The polar regions represent two of the most extreme environments on Earth, with sub-zero temperatures, sustained light in the summer and complete darkness in the winter. Marine diatoms are prevalent in the polar oceans, significantly contributing to primary productivity and ecosystem functioning. They are characterized by having optimal growth at low temperatures (< 10°C) and have developed various genetic adaptations to cope with these extreme environments. The polar regions, however, are experiencing unprecedented environmental changes because of regional climate change. We currently lack detailed knowledge on polar diatom ecophysiology and metabolism, which means we do not know how these species may be impacted by future environmental changes. One barrier to our understanding of polar diatoms is the availability of living strains for experimental study. The number of polar diatom strains in public collections is low and of those that are available, many have been kept in culture for many decades. Hence, there is an urgent requirement to isolate new environmental strains that have not been exposed to artificial conditions for many decades and also to increase the number and diversity of species available. In this project I conducted fieldwork in Antarctica to isolate several new Antarctic strains and used these alongside Arctic and Antarctic strains from culture collections to study whether physiological and metabolic characteristics are conserved between diatoms from the two regions. My studies focused primarily on the response to temperature with the aim of predicting the effects of future climate change on polar diatom physiology and metabolism. The project also aimed to identify potential candidate strains for biotechnological exploitation. Conducting fieldwork on the Western Antarctic Peninsula, I isolated 36 strains encompassing 12 different species of polar diatoms. These have been genetically and morphologically identified and representatives deposited in the Culture Collection for Algae and Protozoa. I investigated the ecophysiology of two diatom species found in both polar regions, Fragilariopsis cylindrus and Porosira glacialis. My results showed how the thermal tolerance differed between Arctic and Antarctic strains with optimal growth temperatures of the Arctic F. cylindrus being 3°C higher than the Antarctic strain. On the contrary, P. glacialis from the Arctic had an optimal growth temperature 5.5°C lower than the Antarctic strain. In addition, the thermal tolerance of newly isolated strains of F. cylindrus was investigated and found to be similar to the laboratory strain except for one, which was able to grow at 12°C. The difference in temperature tolerance between the Arctic and Antarctic F. cylindrus strains led me to investigate the vitamin B12 requirements of these strains. Previously it had been suggested that there are links between B12 dependency and temperature tolerance, and the Antarctic F. cylindrus was previously found to be B12 independent. My results demonstrated that all three Arctic F. cylindrus strains had an obligate requirement for exogenous vitamin B12, whereas all three Antarctic strains did not. Further investigation failed to isolate and identify the B12-independent methionine synthase gene (METE) in Arctic strains, but this gene was identified in Antarctic strains. In contrast, the B12-dependent methionine synthase gene (METH) was identified and partially sequenced in all strains. Several single nucleotide polymorphisms were identified in the Arctic strains which are hypothesised to be non-deleterious. These results provide a potential explanation for the B12 dependency in Arctic isolates, and reasons for how this might have arisen are considered. Lastly, polar diatoms are thought to offer a unique resource for biotechnology offering potentially novel metabolites or increased biomass production during winter months when temperatures decrease. Pilot experiments indicate that there is no advantage in growth over a temperate strain during the winter months in the UK, but further work focusing on optimisation is needed.

In this project, a combination of field measurements, remote sensing data and regional climate model outputs were used to study recent and projected future changes in Northern Fennoscandian snow cover. The research questions considered in this thesis are: What are the uncertainties in remote sensing and climate modelling datasets used in snow studies? How has snow cover been changing since the 1960s and how will it change over the next century, at a regional level over Northern Fennoscandia? Field measurements were made over two field seasons in the Khibiny Mountains in Arctic Russia. This ground data was used to gain an understanding of snow cover behaviour in the Western Mountain Regions (WMR) of the Kola Peninsula and to ground-truth 500 m resolution satellite data (MODIS: Moderate Resolution Imaging Spectroradiometer) snow products. The overall root mean square error (RMSE) for both MODIS instruments was found to be less than 10 %. The ground-truthed MODIS snow product was then used with station data to analyse past changes in snow cover in the WMR over the past 16 years. Though there is high inter-annual and spatial variability in the long-term snow cover trends in the WMR, overall, the duration of the snow cover season has increased at lower elevations and decreased at higher elevations. Field measurements and MODIS data were used in the sensitivity analysis of the Weather Research and Forecasting (WRF) regional climate model. Twelve experiments with different physics parameterisations were run over the first field season, and a statistical scores evaluation was undertaken to determine the optimised parameter setup for modelling snow in the region. Three CMIP5 (Coupled Model Intercomparison Project 5) models were used to force WRF in historical (1990 - 1999) and two future climate (2090 - 2099) emission scenarios over Northern Fennoscandia. Outputs from the historical runs were compared to data from 10 stations across Northern Fennoscandia in order to further validate WRF. WRF makes excellent temperature estimates, with a mean bias in the yearly mean temperature outputs of the runs of -1.89 °C. The precipitation outputs are less accurate with values often higher than observations, especially for extreme precipitation events (CMIP5 ‘ensemble’ mean RMSE of 24.0 mm for 20 + mm precipitation events). Finally, the future runs were compared to historical runs to study projected future changes in temperature, precipitation, snowfall and snow cover. The three models give a range of different future predictions for regional climate change over Northern Fennoscandia. However, all CMIP5 models agree that in both emission scenarios mean snow cover duration will be lower over 2090 to 2099 than it was between 1990 and 1999. Importantly, changes in temperature, precipitation and snowfall are all higher, and snow cover is most impacted, in the higher emission scenario. RCP 8.5 consistently sees a higher decrease in solid precipitation than RCP 4.5 at all stations, and for all models and seasons, for example. Thus, aiming to reduce greenhouse gas emissions is still crucial to reducing anthropogenic impact on Northern Fennoscandian snow.

How long has the extant flora been present in the Antarctic? Glaciological reconstructions propose that most areas in Antarctica were covered by thick ice sheets throughout the Last Glacial Maximum (LGM; ~22-18 kya) as well as previous glaciations, suggesting terrestrial life must have been extremely limited during these periods. In contrast, recent biogeographic and genetic studies support most extant groups of Antarctic terrestrial fauna having survived past glaciations in situ. However, studies on the origin and age of the Antarctic flora remain sparse. Applying population genetic, phylogeographic and divergence time analyses I assessed the global biogeography, origin and age of several abundant Antarctic moss species, including: four Polytrichaceae mosses, characterised by having bipolar distributions, the most common (~45% of species) distribution pattern amongst Antarctic mosses; the globally widespread moss Ceratodon purpureus; the bank-forming moss Chorisodontium aciphyllum, also known for its old sub-fossils in Antarctica and long-term viability from revival experiments; and, lastly, the genus Schistidium, the most species-rich moss genus in Antarctica, including many endemic species. Genetic analyses revealed evidence of long-term (multi-million year) survival of plants in Antarctica (several species of Schistidium, Ceratodon purpureus, and possibly Polytrichum juniperinum). However, evidence for a likely more recent (< 100 ky) arrival of Chorisodontium aciphyllum was also found. Some species revealed multiple separate dispersal events to the Antarctic, suggesting the region may be less isolated for spore-dispersed organisms than previously thought. Evidence for increased genetic diversity in the northern maritime Antarctic compared to other regions point at it including potential refugial areas. Furthermore, genetic patterns revealed geographic features that enable and limit the connectivity of bryophytes globally as well as in Antarctica. This study suggests that, despite the harsh polar climate during glaciation periods, many bryophytes have had a much longer presence in Antarctica than previously thought.

Over eighty polar-themed exhibitions were held in Britain between 1819 and the 1930s, a time of intense exploration of both the Arctic and Antarctic. These varied from panoramas and human exhibits to displays of ‘relics', equipment, photographs and artwork, waxworks and displays shown as part of a Great Exhibition. This period also saw the creation of the first dedicated polar museums. These displays were visited by thousands of people throughout the country, helping to mediate the subject of exploration for a public audience. Despite this, the role exhibitions played in forming popular views of the polar regions has not been fully assessed. This thesis addresses this gap. It is the first to consider all the polar exhibitions held during this period as a collective body, making it possible to study how they developed over time and in response to changing circumstances. The thesis uses a variety of archival sources to both reconstruct the displays and place them in their historical and museological contexts. The study shows that exhibitions evolved in response to changes both in the museum sector and in exploration culture. It demonstrates that, while they were originally identified with the shows of the entertainment industry, polar exhibitions began to take on more of the characteristics of museum displays. At the same time their dominant themes changed; the natural world was relegated in favour of ideas relating to the human experience of the regions such as heroism, adventure and everyday life in an exotic environment. While other media may have been more effective in disseminating ideas about exploration, visitors could find the experience of visiting an exhibition more compelling. This thesis contributes to our understanding of this distinct role that exhibitions played in presenting the polar regions to the British public.

Generic methods were developed using different columns for analysis and purification of hydrophilic compounds by hydrophilic interaction chromatography (HILIC). Mobile phases were investigated in detail, and across each column chemistry tested (BEH Amide, Atlantis bare silica, ZIC-HILIC and Cogent Hydride), salt-buffered mobile phase offered good to excellent peak shape for acids, bases and neutral solutes with a range of hydrophilicities. Additionally, cation exchange occurred on the bare silica column even when rubidium nitrate was added to the mobile phase, which should block all cation exchange sites. Measurement of mobile phase pH in hydroorganic solvent (ACN-water mixture with buffer) better represented the environment solutes experience on column than fully-aqueous pH measurement. The performance of HILIC with Charged Aerosol Detection (CAD) was evaluated with a hydrophilic acid, a hydrophobic base and a hydrophilic neutral solute; limits of detection and quantitation were 1-3 ng and 5-9 ng on column, respectively. This compared favourably to literature values for other universal detectors. HILIC-CAD was further investigated by flow injection analysis (FIA) using 29 solutes containing acids, bases and neutrals. HILIC and CAD had excellent compatibility: peak areas were double compared to reversed-phase conditions, response was reasonably uniform for 21 non-volatile solutes considering the solutes’ diversity. HILIC-CAD was viable for retention and detection of highly hydrophilic species without chromophores: salts, sugars and amino acids. Salts travelled down the column as independent cations and anions. Resolution of sugars and amino acids was challenging and was incomplete due to project time constraints. Generic methods were developed on an analytical system in the labs of the industrial collaborator and applied to purifications on wide-bore columns at scaled-up flow rates (21mm id, 20mL/min prep vs. 4.6mm id 1 mL / min analytical analytical). A standard prep system was capable of usable productivity using HILIC with 1mL injections (22 mg of crude purified per hour) and use of At-Column Dilution enhanced this around 10-fold with scope for 4mL injections (223 mg of crude purified per hour).

The Arctic is a region undergoing unprecedented and unequivocal climate change. The seas of this extreme region form a major component of the oceanic thermohaline conveyor and natural carbon cycle. Using a combination of recent and historical datasets this study examines the distribution, diversity, photophysiology and primary productivity of phytoplankton in the Atlantic sector of the Arctic Ocean. CHEMTAX analysis reveals a diverse phytoplankton community structure in the Greenland Sea comprising six main phytoplankton groups. The influence of sea-ice and water column stratification are key factors in the presence or absence of groups such as haptophytes and prasinophytes. Group-specific differences are observed in spectral absorption and photophysiological parameters. However, the influence of environmental factors has a stronger influence than taxonomic composition on photophysiology. A clear division between the photoacclimatory response of algal communities beneath sea-ice and those of open-ocean stations is predominantly due to ‘Ek independent’ photoacclimation beneath sea-ice. This occurs due to the combined effect of sea-ice decreasing irradiance entering the water column and a positive correlation between Pm B and temperature. This variation in photophysiology is important for primary production models as a sensitivity analysis shows that errors in these parameters propagate to give the largest final errors in primary production values. The importance of other model parameters varies with the level of biomass in the water column and the presence or absence of sea ice. Accelerated ice-melt and an increase in open water due to climate change are likely to increase primary production in the Atlantic Arctic alongside an altered distribution of phytoplankton groups, with an increase in the importance of prasinophytes or haptophytes.

The dynamics of the Mesosphere and Lower Thermosphere (MLT) at polar and middle latitudes are investigated using VHF meteor radars. High-frequency gravity-wave activity and momentum fluxes are examined using Skiymet meteor radars based at Esrange, in Arctic Sweden (68°N, 21°E) and Rothera, Antarctica (68°S, 68°W). The 8-hour tide is investigated at middle latitudes using a meteor radar based in Castle Eaton, UK (52°N, 2°W).A novel technique for studying high-frequency gravity-waves with meteor radar is developed and applied to data from the radars at Rothera and Esrange. This technique is used to investigate the activity of gravity-waves with periods between about 5 minutes and 2 hours and horizontal scales less than about 400 km. A strong semi-annual cycle is revealed with solsticial peaks and equinocial minima. This behaviour is explained in terms of the critical-level filtering imposed by the stratospheric winds. Strong inter-hemispheric differences are also revealed. The theory is advanced that this is the result of the smaller winds speeds in the northern hemisphere in spring (due to the more rapid break-up of the stratospheric vortex).Variances calculated using this new technique are used to investigate interactions between the high-frequency gravity-wave field and tides and planetary-waves. Clear modulations of the gravity-wave field at tidal and planetary-wave frequencies are shown and reveal a relationship between the phase of the tide and the maxima in gravity-wave activity. It is proposed that the likely mechanism for this modulation is critical-level filtering by the tidal winds, acting on an anisotropic gravity-wave field. Zonal and meridional variances and momentum fluxes are calculated using data from the radars at Rothera and Esrange. Monthly-mean variances confirm the semi-annual seasonal cycle and reveal higher meridional activity over Rothera, particularly in summer. Again this is explained in terms of interactions with the mean winds as the waves ascend to the MLT. Zonal and meridional momentum fluxes reveal a somewhat more variable seasonal cycle, which is clearer over Rothera and indicates that at heights of about 90 km and below, momentum flux has a north-west direction in winter and south-east in summer. Data from the radar based at Castle Eaton is used to demonstrate that the 8-hour tide is of significant amplitude in both the mid-latitude and polar MLT. Climatologies reveal a seasonal cycle with a maxima in amplitude in autumn and a secondary maxima in winter. An interesting result is that the seasonal behaviour varies with latitude and the secondary winter-time maximum seen over the UK is not present in the Arctic. Analysis of hourly-mean amplitudes reveal possible interactions between the 8-hour tide, the 12- and 24-hour tides and planetary waves. An analysis based the 17 years of available data indicates a weak relationship between solar activity and the 8-hour tide. Tidal amplitudes tend to increase while phase tends to decrease as solar activity increases.

This research exhibits a new foundation for the rates of change in CO2 and water ice on the southern polar cap of Mars, where the annual precipitation cycles are known to fluctuate seasonally between the north and south pole, based on observations from the Compact Reconnaissance Imaging Spectrometer (CRISM). The conventional belief is that both CO2 ice and water ice on the southern polar cap condenses and evaporates over the course of a Martian year (MY), condensing during the Martian spring and summer and evaporating during the Martian fall and winter. With this theory in mind, CO2 and water ice sublimation will be observable in the CRISM imagery. By using CRISM, a quantitative analysis can be done to evaluate and extract an accurate representation of the water and CO2 ice both lost and gained over Martian seasons and years. This data can also provide estimated rates of change between these variables for future use in determining the expected water and CO2 ice on the southern polar cap at any given time. To show these rates of change, a series of images are created using time series change detection over the course of available imagery in three separate areas on the southern polar cap of Mars. Each area is separated by Martian seasons and Martian years, and well as analyzed by the water ice band and the CO2 ice band. The numerical changes in the ice are then extrapolated and turned into change analysis histograms. Analyses of the data show that both CO2 and water ice increase from spring to summer, increases from summer to autumn, and increases between 2007 and 2009. This analysis both supports the conventional theory on condensation and evaporation throughout the MY, and demonstrates a reproducible methodology for ongoing observation of the CO2 and water ice cycles.

This dissertation investigates the emergence and evolution of United States' national interests in the Arctic region, as well as examines the factors that influence how the U.S. engages in cooperative endeavors in the region with other Arctic states. Though geographically located on the periphery of broader global politics, the region nevertheless is geopolitically situated at the convergence of three continents—North America, Asia, and Europe—in an area historically significant to, but often underappreciated by, the U.S. Government. Two research questions frame this study. The primary research question asks: How have U.S. national interests in the Arctic region evolved over time, and what factors help explain the evolution of U.S. engagement in the region? U.S. perceptions of the region's geopolitical significance gives rise to a subsidiary question: To what degree has the U.S viewed the Arctic region as a zone of competition or a zone of cooperation? Drawing on a range of archival sources, academic literature, historical and contemporary U.S. Government documents—including several declassified documents, as well as personal interviews of key Arctic experts, this study analyzes the development of U.S. interests in the Arctic over four distinct time periods, collectively spanning over a hundred years. These time periods are pre-World War I to the end of World War II (1906-1945); the first half of the four-decade-long Cold War (1945-1967); the second half of the Cold War (1968-1989); and the post-Cold War period (1990-2017). The study produces three major findings. First, U.S. overall interest in the Arctic region increased and decreased in conjunction with how the U.S. perceived the region's overall geopolitical significance. This waxing and waning of U.S. involvement in the polar north generally aligned with the U.S. viewing the Arctic as either a zone of insignificance, competition, or cooperation at different phases over the study's time period. The study's second major finding is that U.S. security interests in the Arctic singularly dominated and shaped America's overall set of national interests that emerged in the region, particularly since World War II. While constituting a number of issues, the most important U.S. security interest in the Arctic has been ensuring freedom of navigation in and through the Arctic. The region's overwhelming maritime composition, along with freedom of navigation's centrality to America's broader global power and interests, ensures the security-driven focus of America's overall Arctic national interests. The final key finding reveals that U.S. Arctic cooperative engagement is conditional. Geopolitical perceptions of the Arctic as either a zone of competition or a zone of cooperation conditions America's willingness to engage with other Arctic states in the region. Since the end of the Cold War and the ensuing period of circumpolar cooperation, U.S. participation in Arctic cooperative arrangements has been conditioned on how much it perceives such arrangements intrude on U.S. autonomy and freedom to act in and through the region.

The shape, size, chemistry, mineralogy, and number of atmospheric nano- and micro-particles all affect the amount of solar radiation reaching Earth’s surface, and thus affect Earth’s climate. While there have been measurements of individual particles larger than 200 nm in polar ice cores, to date, there have been very few measurements of individual particles less than 200 nm in polar ice cores, due to limitations of the analytical techniques used. This study serves as an initial investigation to document the physical and chemical characteristics of ancient particles entrapped in Antarctic ice, where the focus is heavily on method development.Fifty-seven individual particles, contained within two Antarctic ice core sections, have been measured using Transmission Electron Microscopy. The samples, dating to the Last Glacial Period at ~32 ky BP and Holocene at 9.5 ky BP, mark two distinct periods of Earth’s climate and ice coverage. These two distinct periods in Earth’s history affect both the source regions and transportation of particles in the atmosphere, which in turn affects the shape, size, chemistry, mineralogy, and number of particles measured. Previous measurements of the bulk trace element composition and Coulter Counter measurements of particle size distributions in melted ice core samples show that the chemistry and number of particles in the Last Glacial Period and the Holocene are quite different. We see no notable difference between shape, size, chemistry, and minerology between these two samples, although the number of measured particles (n = 57) may be too small to see any subtle differences.Eighty-five percent of the particles measured were smaller than 600 nm and would not have been detected by Coulter Counter which has been the most widely used technique to measure size distributions of particles in ice cores in the past. Sixty-seven percent of the particles measured were smaller than 200 nm, where this study serves as one of the first to show any relationship between size, shape, and chemistry of particles in Antarctic ice, within this size region. On average the measured particles show an elongation by ~50% along one axis. Further, the results of this study suggest that smaller particles are more spherical than large particles.For the first time, elemental maps of individual particles from Antarctic ice cores were obtained to assess the spatial heterogeneity of the elemental chemical composition of individual particles. Sixty-four percent of particles show spatially homogenous chemistry, suggesting that for single particle inductively coupled plasma - mass spectrometry measurements, which measure the bulk elemental composition of an individual particle, the chemical regions within a spatially heterogenous particle will not be documented.All the measured particles can be organized into 12 chemical groups and for each particle, by using a new logic system and a mineral database, minerals consistent with the measured elemental chemical composition have been identified. Common mineral species of quartz, kaolinite, kyanite/andalusite/sillimanite, anhydrite, calcite, were all identified with similar abundances to previous studies of minerals in ancient Antarctic ice. Species of covellite, elemental sulfur, and iron-oxy-hydroxides were observed over 5 times each, indicating the need for further exploration and documentation. Particles with chemical compositions such as sulfur, silica, and silicate particles measured in this study were nearly exclusively smaller than 200 nm.

Due to an increase in wildfires across the US and world, prescribed fires are implemented to reduce fuel loads. Obvious changes occur in the total organic matter by visual observations made after a fire, however, events lead to a production of hydrophobic substances due to the incomplete combustion of organic matter that have the potential to alter soil sorption capabilities. The objective of this research is to determine the sorption capabilities of field collected soil profiles subjected to various levels of prescribed burning using polar and nonpolar compounds. Laboratory controlled soil heating was also conducted to compare the sorption capabilities of the burned soil to that of the collected bulk soil. Soil from Frances Marion National Forest in Cordesville, South Carolina was collected from three locations. WS80 serves as a control, which has never been exposed to prescribed burning, WS77 has been managed with prescribed burns for over 15 years, and WSAA was collected following a low-intensity prescribed burn the day prior to sampling. Field samples were collected at 2.5 cm incremental depths up to a total depth of 25 cm. Using nonpolar 1,3,5 trichlorobenzene and polar 1,3,5 trinitrobenzene, batch sorption experiments were conducted to compare the sorption capabilities of the soil at the surface and lower depths. This study demonstrated a long term prescribed burning has an impact on soil physical and chemical properties. Additionally, a gradient in sorption properties as a function of depth of burned soil. Key findings of this study include increased sorption capability of top layer soil from prescribed burned watershed WS77 increased for polar and nonpolar compounds compared to control site, WS80 (increase of 34% for TCB and 64% for TNB).

Richly productive polar marine ecosystems are hypothesized to have evolved within the last ~30 million years through the rise of diatoms to ecological dominance and diversification of distinctive polar fish, sea birds, seals and whales. Today, short diatom-based food chains support substantial fish biomass, but whether polar fish production is high enough to sustain current industrial fishing is unknown. To this end, we compared ichthyolith accumulation rates (IAR), a proxy for fish production, across ocean ecosystems to trace the development of global fisheries stocks over the past 1.8 million years. We find that the magnitude of polar fish production, based on the flux of fish teeth to deep-sea sediments, is an order of magnitude lower than seen in subtropical and tropical sites. We suggest that polar fish production is systematically suppressed by extreme seasonality, phenological mismatch, low functional redundancy, and extreme glacial-interglacial climatic variability in the high latitude oceans. Comparisons of our Pleistocene data to similar records from the Eocene and Oligocene oceans (~42-28 Ma) show that fish production in high latitudes has been consistently low for the last 30-40 Ma relative to most of the tropical and subtropical locations. We conclude that the stock crashes observed in the polar regions over the past several decades reflect overexploitation of ecosystems that have had low fish production for tens of millions of years.

Abstract: The phenomena of droplet spreading and imbibition has widespread application in membrane science. It is widely believed that the membrane flux increases with greater hydrophilicity. In porous membranes, the spreading and permeation occur at the same time, and these separate but competitive phenomena must be considered when reporting the contact angle results. In the first phase, the role of characteristic parameters (radius and height of droplet) is investigated by considering an existing mathematical model formulated on the basis of lubrication approximation. Under partial wetting conditions, the contact line singularity prevails which is relieved using precursor film assumption and disjoining pressure. Based on two main stages of spreading (initial and equilibrium), characteristic radius and height were first evaluated. The model predictions were then compared with experimental results in literature for both impermeable and permeable substrates. It was found that the choice of characteristic length scales based on either stage enables accurate prediction of the droplet base radius and contact angle. A new scaling relation for the prediction of the numerical disjoining pressure for both impermeable and permeable wetting systems, with an error of ±5%, is proposed. In the second part, experimental and numerical study of water droplet spreading and imbibition on lab-fabricated and commercial polyethersulfone (PES) membranes is performed. The characterization technique used for permeability is filtration test, for cross-section thickness is FESEM images, for surface roughness is AFM data, and for hydrophilicity is dynamic contact angle experiments. The theoretical disjoining pressure calculated in the case of apolar and polar interactions is found to be related to the numerical disjoining pressure parameter obtained after good agreement with experiments. The pinning observed in the contact angle experiments is well predicted by the mathematical model used in the first phase of the study. The hydrodynamic permeability of a membrane as a function of its cross-section thickness and resistance is compared to the effective permeability which is calculated after validating numerical predictions with contact angle experiments. An attempt has been made to correlate the local property realized through droplet dynamics to its global property interpreted through resistance of the membrane.

Aeolian processes play an important role in the transport of both geological and biological materials globally, on the biogeochemistry of ecosystems, and in landscape evolution. As the largest ice free area on the Antarctic continent (approximately 4800 km2), the McMurdo Dry Valleys (MDV) are potentially a major source of aeolian material for Antarctica, but information on the spatial and temporal variability of this material is needed to understand its soluble and bulk geochemistry, deposition and source, and hence influence on ecosystem dynamics. 53 samples of aeolian material from Alatna Valley, Victoria Valley, Miers Valley, and Taylor Valley (Taylor Glacier, East Lake Bonney, F6 (Lake Fryxell), and Explorer’s Cove) were collected at five heights (5, 10, 20, 50, 100 cm) above the surface seasonally for 2013 through 2015. The sediment was analyzed for soluble solids, total and organic carbon, minerology, and bulk chemistry. Of the soluble component, the major anions varied between Cl- and HCO3-, and the major cation was Na+ for all sites. Soluble N:P ratios in the aeolian material reflect nutrient limitations seen in MDV soils, where younger, coastal soils are N-limited, while older, up valley soils are P-limited. Material from East Lake Bonney was P-limited in the winter samples, but N-limited in the full year samples, suggesting different sources of material based on season. Analysis of soluble salts in aeolian material in Taylor Valley compared to published soil literature demonstrates a primarily down valley transport of materials from Taylor Glacier towards the coast. The bulk chemistry suggests that the aeolian material is highly unweathered (CIA values less than 60 %), but scanning electron microscope images show alteration for some individual sediment grains. The mineralogy was reflective of local rocks, specifically the McMurdo Volcanics, Ferrar Dolerite, Beacon Sandstone and granite, but variations in major oxide percentages and rare earth element signatures could not be explained by mixing lines between these four rock types. This potentially suggests that there may be an additional, and possibly distant, source of aeolian material to the MDV that is not accounted for. This work provides the first fully elevated spatial and temporal analysis of the geochemistry of aeolian material from the Dry Valleys, and contributes to a better understanding of sediment provenance and how aeolian deposition may affect surface biological communities.

The North Polar Layered Deposits of Mars are a formation of water ice ~1000 km across and ~2 km thick. For years, scientists have looked to these layers of ice and dust as a possible source of information regarding how the planet’s climate has changed over the past ~4 million years. However, connecting these layers to specific climate conditions remains a challenge. Previous research has attempted to tie both radar stratigraphy and outcrop stratigraphy to the orbital cycles of Mars, but the proposed relationships are often contradictory, and struggle identify how specific layer properties might be tied to ancient climate. To help resolve these issues, I synthesized a combination of SHARAD radar data, HiRISE imagery, topography, and electromagnetic modeling in an effort to quantify layer properties such as thickness and composition, and connect those properties to past climate conditions. I was able to quantitatively show that a set of layers known as marker beds is likely responsible for causing radar reflectors, and was able to show how radar reflectors could be used to infer the composition and relative thickness of these layers throughout the polar cap. With this information in hand, scientists can, for the first time, begin to realize the full potential of the North Polar Layered Deposits as a global climate record of Mars.

Cinder cones in the Erebus Volcanic Province provide important markers of climate, erosion, and stress in the Ross Sea region of Antarctica, but they have not previously been systematically studied. Cinder cones provide ideal subjects for morphological analysis because they consistently form as radially symmetric landforms with approximately constant slopes. DEMs are used in tandem with satellite images and parameterization algorithms in this study to characterize landforms and surface properties of glaciated and non-glaciated Erebus Volcanic Province cinder cones.Cone dimensions are similar to those in other intraplate environments and generally smaller than cones in subduction- and rift-related settings. Average height/width ratios are more characteristic of volcano cone fields than platform cone fields, but the volcanic terrain of the Erebus Volcanic Province is likely a complex combination of both field types. Elongation of cinder cones in the Erebus Volcanic Province is common and most elongated cones have long axes oriented parallel or subparallel to the slope direction of terrain underlying them, indicating topographic control of cone asymmetry. Some cones with orientations independent of terrain controls suggest that regional stresses exert control on cone elongation, as suggested by previous research. Shape modification by wind and overriding glaciers may also play a role in producing cone asymmetry.Erosion rates on cinder cones in the Erebus Volcanic Province are generally slower and more linear than in other, more temperate regions. This is most likely due to a decreased influence of the role of liquid water, as evidenced by lack of increasing surface irregularity with time. Previous research has shown that wind has significant abrading power when persistent, and that volcanic terrain has increased shear strength because of surface roughness and angularity. Both of these factors likely contribute to the relatively slow rate of erosion in the EVP compared with fields in the southwestern US, the Canary Islands, Mexico, and Russia.The role of cold-based glaciers in polar erosion regimes was evaluated for the Pleistocene and remains unclear. Rates of slope degradation for glaciated and non-glaciated cones are similar, and statistical analysis indicates that the trends are statistically indistinguishable from one another. Therefore it may be that overriding by cold-based glaciers does not markedly affect cone morphology. Surface irregularity does increase after repeated overriding by polar glaciers compared with glacier-free cones. This might be linked to meltwater channel activity at the base of polar glaciers during times of glacial cover.Morphologic study of cinder cones has established an age-calibrated rate of surface change in a polar desert environment. Establishment of an absolute age classification based on the degree of cone slope and height/width degradation can potentially be used to assign ages to the hundreds of undated cones in Antarctica, and may also prove applicable as a dating tool for volcanism in other cold-desert environments, such as those on Mars and other terrestrial planets. Because of error ranges in parameters and age values, absolute age can currently only be assigned to broad age groups with a reasonable degree of certainty. However, a more comprehensive understanding of the factors that affect initial cone formation and morphological change over time may allow better constraints for more precisely predicting cinder cone age.

Despite significant work done in the field of the dynamics of soft matter, the microscopic mechanisms controlling various relaxation processes (structural relaxation, diffusion, chain dynamics in polymers) in vitreous materials still remain unclear. The situation is even worse when one tries to understand the interrelation between different relaxation phenomena. Resolving the mechanisms controlling various aspects of glassy structure and dynamics is of obvious fundamental and industrial importance. In this work, mechanisms controlling different relaxation phenomena occurring over a broad range of length and time-scales in vitreous materials were characterized with several experimental techniques: dielectric spectroscopy, light and neutron scattering, and rheology. The effect of polar interactions on the temperature dependences of structural (segmental) and chain dynamics in polymeric liquids was studied. The glass transition temperature, Tg, and fragility index, m, are found to depend on the monomer’s polarity and the relative position of the polar group. The effect of polar interactions on Tg and m is discussed in terms of a balance between changes in the cohesive energy and conformational rigidity. Intriguing and unusual results were obtained on the effect of polar interactions on chain dynamics. It was demonstrated that the presence of polar interactions leads to a significant coupling of segmental and chain dynamics in polar materials in comparison to non-polar polymers with similar fragilities. Apparently, polar interactions have long range effects that are yet to be understood. The temperature dependences of the self-diffusion rate and structural dynamics in a room temperature ionic liquid (RTIL) were analyzed in an extremely broad temperature range. The results clearly demonstrate that the self-diffusion coefficient in this molecular liquid has a temperature dependence that is weaker than the temperature dependence of the structural relaxation time. However, the observed decoupling of the structural relaxation and self-diffusion in the polar RTIL is much weaker than expected for a van der Waals molecular glass-forming liquid with comparable fragility. Combination of these results with the data obtained on dynamics in polar polymers allows one to speculate that the large length scale dynamic processes can be significantly affected by the presence of delocalized polar interactions in a broad range of organic glass-forming liquids, polymers and molecular liquids. The relationship between the temperature dependences of ionic conductivity and segmental dynamics in polymers uncovered here also points to intriguing aspects of dynamics in soft matter. Ionic conductivity was found to decouple from segmental dynamics with the degree of decoupling correlating with the fragility of the polymer. It is speculated that frustration in packing is the main driving mechanism of the decoupling between ionic and segmental dynamics. These results suggest that ionic conductivity can be decoupled from segmental dynamics in a material specific way. With the right approach it should be possible to decouple the ionic motion from segmental dynamics in a manner that would result in high conductivity even in the glassy state. This opens new routes for material design of truly solid polymer electrolytes.

Abstract: Recent research indicates climate change will be amplified in Polar Regions, which will cause decreases to sea ice thickness and extent throughout the Arctic. Polar bears (Ursus maritimus) will be directly affected by changes to Arctic sea ice conditions because they rely on the ice substrate for numerous aspects of their life history. Perhaps of most importance, polar bears use the sea ice platform to access their main prey, pagophilic seals. Determining specific effects of climate-induced environmental change on polar bears will require monitoring at numerous spatiotemporal scales and across various levels of biological organization. In this dissertation I used and refined a variety of ecological monitoring tools that evaluated the effects of seasonal and longer-term unidirectional sea ice changes to various aspects of polar bear ecology. At a molecular level, I used urea to creatinine ratios in polar bear blood to show that an increased number of polar bears were in a physiological fasting state during spring captures in 2005-2006 compared to the mid-1980s. These changes corresponded to broad-scale changes in Arctic sea ice composition, which may have altered prey availability. I also used measurements of naturally occurring stable isotopes (δ13C, δ15N) in polar bear tissues to examine their diet, which included both lipid-rich blubber and the proteinaceous tissues of their marine mammal prey. Because the proportion of proteins and lipids consumed likely depended on prey type and size, it was necessary to consider metabolic routing of these macromolecules separately when using isotope mixing models to determine and monitor polar bear diet. I also monitored polar bear movement and migration behaviour at the population level. Specific landscape sea ice metrics corresponded to seasonal population migration patterns and fidelity to particular geographic regions. Trends in the timing of these seasonal population migration patterns were likely associated with climate-induced changes to sea ice dynamics. Finally, I examined migration behaviour in relation to local sea ice dynamics in individual polar bears and demonstrated a mechanistic understanding of the relationship between sea ice and polar bear migration patterns.

Antarctic formations of science, property, and governance complicate how the commercial use of genetic and biochemical data derived from biota (bioprospecting) might be managed there. Antarctic science should be cooperative, but patents that arise from bioprospecting could generate competition. If Antarctica is perceived as a global commons, exclusive rights to its resources could threaten that status. The peaceful governance of Antarctica is based on the Antarctic Treaty of 1959, but its authority could be threatened by other groups seeking to govern over this new activity. This dissertation explores these issues through two territorial approaches: one focused on the hierarchical bureaucracy of Antarctica and another focused on alternative geographical imaginaries of the continent. While there has been a great deal of concentration on states and the Antarctic Treaty System, this study reveals that careful reconsideration of geographical imaginaries can present alternate solutions.

Antarctica is the most remote and isolated continent on Earth and is generally thought to have low biodiversity due to environmental extremes. These relatively simple ecosystems are important to study because they can be used to improve understanding of more complex systems world-wide that are difficult to analyze directly. The isolation of the continent, extreme environmental conditions and the lack of functional redundancy in ecosystem processes make it particularly vulnerable to human disturbance and require improved understanding. The results of this research support the hypothesis that fungal abundance and distribution are generally linked to the presence of primary producers and their effect on carbon and nitrogen quantities in the soil. Experiments introducing sterile plant-derived nutrient sources (wood and cellulose) to soils resulted in increased fungal abundance up to three to four orders of magnitude greater than background soil levels. This suggests that the extremes of the Antarctic environment (low moisture, high salinity, cold temperatures) are primarily affecting fungi by limiting the distribution of flora and direct effects on the fungi are relatively less important as these indigenous soil fungi appear well adapted to Antarctic environment. A survey of fungal diversity near historic sites and areas where materials were introduced to the Antarctic Peninsula reveals a very similar composition to those affecting historic sites on Ross Island. The fungi found in greatest abundance were species of Geomyces and Cadophora. These two genera also formed a large percentage of the fungal colonization of buried nutrient substrates. The frequent reports of these fungi from many areas in Antarctica and the large diversity of species found indicates they are well adapted to their environment and suggests they are indigenous to Antarctica. The dominance of these fungi on human-introduced material indicates direct human influences may be of more benefit to generalist indigenous decomposer fungi which are pre-adapted to the environmental extremes rather than human-introduced fungi which may be better adapted to utilizing these substrates but not well adapted to the Antarctic environment. It also supports the hypothesis of indigenous Antarctic fungi being primarily limited by nutrient availability.

The progress in modern, widely-defined information technology strongly depends on the ability of precise characterization of variety of materials in the wide range of anticipated parameters. Novel magnetic materials and magnetic structures are the core of the spintronics in which a manipulation of electrons spins opens a door to new concepts of practical applications. The magneto-optic is an interesting approach to effectively assess properties of spintronic materials due to the strong interaction of photons with spins mediated through spin-orbit coupling. This is manifested by observation of Faraday, Voigt and Kerr effects in magnetic materials. These effects crucially depend on the spin-orbit interactions in the starting and/or the ending state of the optical transition considered. In this work we exclusively focused on the magneto-optical Kerr effect through the development of and testing of the automated Magneto-Optical Kerr Effect (MOKE) spectrometer operating in polar and longitudinal geometries at room temperature. The constructed MOKE system has proven to be central to perform magneto-optical and magnetic characterizations of selected test and research samples. In particular, we were able to confirm the functionality of the MOKE by measuring Kerr rotation hysteresis loops of the Pt/Co superlattice test samples. Furthermore, a set of new results was obtained for the different epitaxially grown GaN/Fe material systems. The observed Kerr rotation signal for GaN/Fe was interpreted as the clear evidence for a strong spin-orbit interaction occurring in these novel magnetic materials. In addition to the conducted experimental work, special attention was dedicated to derive an analytically comprehensive description of the Kerr rotation and Kerr ellipticity in the general case of polar and longitudinal geometries. Finally, relying on the expertise gained during the MOKE spectrometer construction and testing, we proposed to upgrade the system necessary to improve its reliability and expand the scope of available magneto-optical measurement techniques at Ohio University.

Microcalorimetric measurements and contact angle measurements were conducted to assess the surface chemistry of the mineral talc. The contact angles were performed on both flat and powdered samples and the results were used to determine the surface free energy components and parameters (SFEC) using the acid-base theory for solids, according to the van Oss-Chaudhury-Good approach. It was found that the surface hydrophobicity of talc increases with decreasing particle size up to a limit after which hydrophilicity (polarity) increases. The increase in hydrophobicity was attributed to the increase of the delamination of the lamellar talc particles. Delamination is a comminution mechanism that preferentially exposes talc's hydrophobic basal planes, while fracture is another mechanism that breaks the lamellae, rupturing covalent bonds thus exposing more hydrophilic edge surfaces. The decrease in hydrophobicity, beyond a given particle size, could be related to the prevail of fracture over delamination during grinding which generated more hydrophilic edge surfaces. The flow microcalorymetry combined with thin layer wicking allowed the separate estimation of the SFEC at the basal plane and edge surfaces of talc. The results suggested that the basal surface of talc is monopolar basic, while the edge surface is monopolar acidic, which are in agreement with the crystal structure of the mineral. The combination of two particle size distribution techniques, which are based on different physical principles, permitted the quantitative determination of the aspect ratio of highly anisometric particles, such as talc. The same trend obtained using flow microcalorimetry was observed for the evolution of the aspect ratio as a function of particle fineness, i.e. the fracture prevails over delamination after achieving a maximum aspect ratio value of about 35. The agreement between two distinct methods was considered rather encouraging.

Microcalorimetric measurements and contact angle measurements were conducted to study the surface chemistry of powdered minerals. The contact angle measurements were conducted on both flat and powdered talc samples, and the results were used to determine the surface free energy components using Van Oss-Chaudhury-Good (OCG) equation. It was found that the surface hydrophobicity of talc increases with decreasing particle size. At the same time, both the Lifshitz-van der Waals (gSLW) and the Lewis acid-base (gSAB) components (and, hence, the total surface free energy (gS)) decrease with decreasing particle size. The increase in the surface hydrophobicity and the decrease in surface free energy (gS) can be attributed to preferential breakage of the mineral along the basal plane, resulting in the exposure of more basal plane surfaces to the aqueous phase. Heats of immersion measurements were conducted using a flow microcalorimeter on a number of powdered talc samples. The results were then used to calculate the contact angles using a rigorous thermodynamic relation. The measured heat of immersion values in water and calculated contact angles showed that the surface hydrophobicity of talc samples increase with decreasing particle size, which agrees with the direct contact angle measurements. A relationship between advancing water contact angle qa, and the heat of immersion (-DHi) and surface free energies was established. It was found that the value of -DHi decrease as qa increases. The microcalorimetric and direct contact angle measurements showed that acid-base interactions play a crucial role in the interaction between talc and liquid. Using the Van Oss-Chaudhury-Good's surface free energy components model, various talc powders were characterized in terms of their acidic and basic properties. It was found that the magnitude of the Lewis electron donor, gS-, and the Lewis electron acceptor, gS+, components of surface free energy is directly related to the particle size. The gS- of talc surface increased with decreasing particle size, while the gS+ slightly decreased. It was also found that the Lewis electron-donor component on talc surface is much higher than the Lewis electron-acceptor component, suggesting that the basal surface of talc is basic. The heats of adsorption of butanol on various talc samples from n-heptane solution were also determined using a flow microcalorimeter. The heats of adsorption values were used to estimate % hydrophilicity and hydrophobicity and the areal ratios of the various talc samples. In addition, contact angle and heat of butanol adsorption measurements were conducted on a run-of-mine talc sample that has been ground to two different particle size fractions, i.e., d50=12.5 mm and d50=3.0 mm, respectively. The results were used to estimate the surface free energy components at the basal and edge surfaces of talc. It was found that the total surface free energy (gS) at the basal plane surface of talc is much lower than the total surface free energy at the edge surface. The results suggest also that the basal surface of talc is monopolar basic, while the edge surface is monopolar acidic. The results explain why the basicity of talc surface increases with decreasing particle size as shown in the contact angle and microcalorimetric measurements. Furthermore, the effects of the surface free energies of solids during separation from each other by flotation and selective flocculation were studied. In the present work, a kaolin clay sample from east Georgia was used for the beneficiation tests. First, the crude kaolin was subjected to flotation and selective flocculation experiments to remove discoloring impurities (i.e., anatase (TiO2) and iron oxides) and produce high-brightness clay with GE brightness higher than 90%. The results showed that a clay product with +90% brightness could be obtained with recoveries (or yields) higher than 80% using selective flocculation technique. It was also found that a proper control of surface hydrophobicity of anatase is crucially important for a successful flotation and selective flocculation process. Heats of immersion, heats of adsorption and contact angle measurements were conducted on pure anatase surface to determine the changes in the surface free energies as a function of the surfactant dosage (e.g. hydroxamate) used for the surface treatment. The results showed that the magnitude of the contact angle and, hence, the surface free energy and its components on anatase surface varies significantly with the amount of surfactant used for the surface treatment.

Exploration was a defining aspect of how European societies encountered and established relations with the wider world. It set the stage for worldwide empires and laid the foundations for understandings of planetary existence. Exploration facilitated the exchange of commodities and ideas, the migration of peoples and the construction of scientific knowledge. This dissertation examines the nexus between ice and imperium through a study of how citizens of the Habsburg Monarchy contributed to polar exploration. In the long nineteenth century, the two main objects of European exploration were Africa and the polar regions. In the former, the dynamic between exploration and empire was fairly straightforward. But how did imperialism function in the frozen, uninhabited, latitudes of the world? This question becomes more problematic for the Habsburg Monarchy, a multinational polity with eleven officially recognized languages, and a self-professed empire that was the one European "Great Power" at the time without overseas colonies. This dissertation analyzes how the symbology and practice of polar exploration was used in the service of sundry - and frequently contradictory - political projects, including various nationalist activisms, Habsburg loyalism, and the liberal politics of notables. The analysis incorporates a case study in the convoluted road between discovery and empire, Franz Josef Land, the northernmost terrain in Eurasia, discovered by an Austro-Hungarian expedition in 1873. This dissertation then traces fractures within the Austro-Hungarian culture of exploration, as explorer/scientists could reach little consensus on the goals and practices for expeditions to the farthest latitudes of the globe. Finally, it examines how the rise of mass-data driven inductive sciences, such as geomagnetism, caused a fundamental redefinition in the practice of polar research toward a model of corporate, coordinated scientific effort and transnational cooperation. With the emergence of nation states and colonial empires, the basic frameworks of sovereignty, legitimacy and political meaning were changing and this study highlights how Habsburg subjects contributed to these modernization processes. In so doing, it brings to light neglected but lasting aspects of nineteenth century imperialism and treats both nationalism and empire as research problems rather than given ends., History

The low polarity of the supercritical fluid extraction (SFE) solvent, CO₂, causes problems when applying this technique to polar compounds. The objective of this research was to expand the applicability of SFE to include polar compounds. The first phase of this research investigated "inverse SFE", which is the selective extraction of the matrix while leaving behind the target analytes, as a means of isolating four polar polymyxin sulfate compounds from several challenging matrices due to the liquid-like consistency and the low concentrations (ppm) of the target analytes. Higher recoveries (>100%) were achieved with low RSD's (5.0 and 1.9% for two separate matrices), compared to the conventional method of isolation, solid phase extraction. The second portion of this research investigated the effect of high levels of polar modifier on trapping efficiency. The mode of modifier introduction was found to have a considerable effect on trapping efficiency, as in-line modifier addition rather than matrix spiking was determined to be best when introducing high levels of liquid modifier. Also, three separate mechanisms, aerosol formation, blow-by, and modifier elution, were identified which caused analyte loss at the solid phase trap, and the extraction and trapping conditions for which each mechanism was most favorable were identified. The next phase of this research developed two separate SFE methods which were used to isolate two pharmaceuticals from leaves. Each SFE method reduced the time, sample handling, costs, and liquid solvents needed as compared to the conventional liquid extraction technique. While achieving comparable recoveries, reproducibilities were much improved for the two SFE methods with RSD's of 3.8 and 5.2%, respectively, while the liquid extraction technique yielded RSD's of 14%. The last phase of this research investigated several strategies for improving selectivity in SFE. Three separate strategies for improving selectivity were studied: 1) alternative fluids (pure and modified fluoroform and tetrafluoroethane), 2) pre-extraction, and 3) selective rinsing of the solid phase trap. Advantages were realized with each technique, and it was concluded that they be used in conjunction with one another in order to maximize selectivity.

The major objective of these studies was to examine the in vivo permeation of polar molecules through hairless and hairy rat skin upon topical application of various formulations. The deposition of progesterone, a small lipophilic molecule, was also investigated in order to contrast the results with those of polar penetrants. Finally, formulation factors influencing deposition of a topically applied polar macromolecule, a monoclonal antibody to doxorubicin (MAD11), were assessed. Our major conclusions were: (1) Hairless rodent skin acted as a leaky barrier to mannitol, a prototypical polar permeant, after either in vitro or in vivo topical application of simple aqueous solutions or liposomal dispersions. In vitro conditions exaggerated the transport, which may have been a result of excessive hydration. (2) Differences in permeation of hairless and hairy rat skin may be partly explained by gross histological differences between the species. Hairless rat skin seemed to have been leaky due to cysts, numerous, enlarged sebaceous glands and underdeveloped hair follicles. Fully developed hair follicles in hairy rat skin seemed to act as drug depots for liposome-associated molecules, whereas systemic transport may have been restricted by the deep location of small follicle-associated sebaceous glands. Deposition of liposomal carboxyfluorescein was visualized in the stratum corneum and upper portion of hair follicles by confocal microscopy. Regardless of formulation, only transient fluorescence was visualized throughout hairless rat hair follicles. (3) Localized and systemic deposition of progesterone was greater in hairless rat skin than in hairy rat skin, which again may reflect the presence of enlarged sebaceous glands and cysts in hairless rat skin. (4) Acetone-induced delipidization of the stratum corneum dramatically increased mannitol transport through hairy rat skin, but not hairless rat skin. The results suggest that the treatment failed to completely remove sebaceous lipids from hairless rat skin, which may have a greater overall lipoidal character. (5) The primary factor influencing liposomal deposition of MAD11 into hairless and hairy rat skin was liposome surface charge. Enhanced deposition was observed to a lesser degree by phospholipid liposome particle size reduction and by lipid concentration optimization for nonionic lipid-based liposomes.

The high latitude ionosphere and polar wind outflow at Saturn were studied with a sophisticated numerical model. The importance of the polar wind as a source of plasma to the Saturnian magnetosphere was analyzed. In addition, we wished to better understand the data that was taken during the fly-by missions to Saturn, and we developed a tool that may be used in future studies during the Cassini mission. The time-dependent and gyrotropic continuity, momentum, and energy equations with heat flow were solved for a quasineutral, currentless plasma comprised of H$\sp+$ and H$\sbsp{3}{+}$ ions. In addition, the electron temperature equation was solved. This coupled set of equations was solved with a combination Godunov and Crank-Nicolson scheme. The model was run to steady-state with several neutral atmospheric temperatures ($T\sb{n}$) and variations on the densities of the neutral species. The model produced reasonable agreement with electron densities derived from Voyager 1 radio occultation data at 73$\sp\circ$ at and above the observed peak with a neutral atmosphere that was consistent with observations. In order to match the observed profile throughout the entire observed region, it was necessary to include additional losses due to either methane or water at lower altitudes, and to increase the source of ions (by increasing the amount of H$\sb2$). Plasma is expected to be transported upward above $\approx$2000 km, and steady-state fluxes to the magnetosphere were estimated to be on the order of $\rm 2\times 10\sp7\ cm\sp{-2}s\sp{-1}$. With a downward heat flux of $20\times 10\sp{-3}$ ergs cm$\rm\sp{-2}s\sp{-1}$ applied to the electrons at the top of the simulation, their temperature reached values of $\approx$7000 K. The temperatures of the positive species significantly departed from the neutral temperature at altitudes of $\approx$3000-3500 km above the 1-bar pressure level $\rm (n\sb{H\sb2}\approx 10\sp8$) when $T\sb{n}$ = 800 and 1000 K. Time-dependent simulations revealed that H$\sp+$ is the dominant ion throughout most of the ionosphere 3 hours after the sun sets, and that the altitude of the electron peak rises during the night. An asymmetry in the source of H$\sbsp{3}{+}$ to the magnetosphere is expected, as the flux of H$\sbsp{3}{+}$ becomes negligible by the end of the night.