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<p>Chemical weathering of highly reactive mafic and ultramafic igneous rocks may be a key sink in the global carbon cycle. Understanding how uplift of these rocks during arc-arc and arc-continent collisions through earth history has affected the evolution of global climate, including the onset of icehouse periods, requires improved constraints on the relative sensitivity of their weathering rates to physical erosion vs. climate. If weathering rates depend chiefly on erosion, then tectonic uplift of mafic and ultramafic rocks may have a strongly destabilizing effect on global climate. Conversely, if weathering rates are limited primarily by temperature or runoff, then a negative feedback mechanism between weathering and climate may attenuate the effects of rock uplift. This work characterizes the relationship between chemical weathering rates, physical erosion rates, and climate in tropical, montane watersheds in Puerto Rico that are underlain by volcanic arc rocks and associated ophiolitic serpentinite. Key to this analysis are new constraints on long-term erosion rates on these rocks from cosmogenic Cl-36 produced <em>in situ</em> in magnetite. These cosmogenic erosion rates are paired with classical measurements of stream solute fluxes and sediment geochemistry across runoff gradients to quantify the limits to volcanic arc rock and serpentinite weathering rates. </p> <p><br></p> <p>This work is divided into three chapters. Chapter 2 constrains the altitude scaling behavior of Cl-36 production in magnetite. This allows erosion rates to be determined more accurately in watersheds near sea level in Puerto Rico. Chapter 3 demonstrates that volcanic arc rock weathering rates in the humid tropics are more strongly limited by physical erosion than by climatic factors. However, a positive correlation between erosion and runoff observed in this landscape may enhance the coupling between climate and weathering rates. Chapter 4 finds that, in contrast to volcanic arc rocks, serpentinite weathering is strongly limited by runoff and weakly limited by erosion. These results are presented as empirical power-law relationships that can be readily applied in global carbon cycle modeling.  </p>

Airborne Wind Energy is an emerging technology that harnesses the power of the wind by using tethered wings. Among the flying devices are ram-air wings made from coated textiles that utilize dynamic pressure to gain their shape. During flight operation, the textiles are subject to long-term weathering exposure and high aerodynamic loads, leading to degradation processes and the ultimate loss of functional properties. Therefore, a key challenge in the Airborne Wind Energy industry is the improvement of the textile durability of ram-air kites. This thesis contributes to solving this problem by investigating the effects of 200 hours of artificial weathering and 36 weeks of natural weathering on the mechanical properties of selected state-of-the-art kite textiles and the underlying principles of degradation. The tested materials involve two polyamide 6.6 rip-stop weaves coated with polyurethane and silicone, as well as a coated plain weave and a flexible laminate made from high-modulus polyethylene. The results show that all materials are clearly affected by the exposure to weathering, but the implications on the mechanical properties and the rate of degradation vary significantly. The high-modulus polyethylene textiles demonstrate superior tensile properties, but severe coating degradation causes a significant rise in air permeability. Consequently, the high-modulus polyethylene textiles are considered unsuitable for application in ram-air kites, as the high permeability prevents the kite from maintaining sufficiently high pressure. In contrast, the silicone coated polyamide 6.6 textile exhibits superior air permeability after long-term exposure to weathering conditions. FTIR spectroscopy and TGA indicate that the reduced permeability could arise from curing processes in the silicone coating.

The weathering of plastics and composites is a problem because of the loss of both physical and mechanical properties that it causes in these materials. But this weathering effect has been difficult, and in some cases, impossible to characterize without the destruction of the plastic or composite part. Clearly a rapid, reliable, and non-destructive test for the extent of the weathering damage is critically needed. A recent problem that arose at Superyacht Solutions, a boat repair company in Australia, required a solution to just this problem. Such a test was developed for Superyacht Solutions, and is being applied across a wide range of plastic materials. The chemical foundation upon which this solution rests is also being confirmed. The Superyacht Solutions problem was that a boat was brought in for repair which was yellowing dramatically. Surface erosion was confirmed by scanning electron microscope (SEM) surface studies. A loss of mechanical properties was also suspected. A new spectroscopic method of analysis was developed that not only identified the problem as extensive oxidation, but was able to quantify the extent of damage that occurred through a non-destructive technique. This method has also been applied to other plastics with encouraging initial results. The method used and its theoretical basis are included in this thesis.

I vår snabba och upptagna värld med saker att göra, folk att träffa, platser att besöka, är det lätt att tappa kontakten med tidens gång, årstidernas förändring etc. Förändringar sker kring oss hela tiden men vi uppmärksammar dem ej, och rätt som det är har flera år flutit förbi. Vi brukade leva mer i synk med tiden och naturen, i ett naturligt förhållande till skiftningar och förändring, och jag tycker att det finns ett värde i att försöka återupprätta det förhållandet. Jag ville undersöka vårt förhållande till tid och närvaro och försöka hitta sätt som arkitektur kan hjälpa oss vara mer medvetna om vår plats i världen och tiden.Detta undersöks genom utformningen av ett kallbad som erbjuder besökaren en rituell resa av upplevelser. En plats där man kan slappna av och ha utrymme för eftertanke, ta sin tid att uppleva och se världen och sig själv på ett nytt sätt. Fokus ligger ej på eskapism och nöje utan på att skapa intensiva upplevelser som kan främja medveten närvaro. / In today's world we all live very fast, we all have places to be and stuff to do and most of the time we are not aware of time passing, seasons coming and going, changes happening etc. We used to live more closely connected with time and nature, and I think it is important to try to regain that connection. I wanted to look closer at our relationship to time and presentness, and try to find ways that architecture can help bring about an increased awareness of our place in the world.This is investigated through designing a cold bath which offers the user a ritual journey of experiences. A place where one can relax and reflect, and take ones time to experience and look at the world and one self in a new light. The focus is not on escapism or purely pleasure but rather on creating intense experiences to foster mindfulness.

Ignitable liquids consist of either a single organic compound or a complex organic mixture. In regards to fire debris analysis, the analyst is responsible for determining if an ignitable liquid residue is present. However, when extracted from soil-containing fire debris evidence, chemical degradation from microorganisms is observed to result in the loss of compounds based on chemical structure. It can also happen when the evidence container is stored at room temperature before analysis. This can present a challenge to the fire debris analyst when identifying and classifying the ignitable liquid residue based on the criteria established by standard test methods. The purpose of this research was to observe the microbial degradation of fourteen compounds, at room temperature over a period of time, for possible by-product formation that could coincide with compounds normally present in an ignitable liquid. Additionally, a quantitative assessment was performed to observe and record the loss rate of compounds in a representative simple mixture. Finally, the loss rate from the simple mixture was compared to commercially available ignitable liquids. Degradation studies were conducted to observe the microbial degradation of a representative compounds (individually and in a simple mixture, both weathered and unweathered) and seven ignitable liquids of different ASTM E1618 classifications. Potting soil was spiked with 20 µL of a liquid/compound and was allowed to stand at room temperature for a period of time. The simple mixture was evaporated to 50% and 90% using a steady nitrogen gas flow to compare the degradation process to the unweathered mixture. All samples were extracted and analyzed using passive-headspace concentration and gas chromatography-mass spectrometry. The formation of by-products was not observed when degrading the compounds from the simple mixture individually as seen in other research. The simple mixture, unweathered and 50% weathered, resulted in rapid degradation of their oxygenated compounds. The straight-chained alkanes and toluene were observed to be more susceptible to microbial attack than the highly-substituted aromatics and the branched and cyclic alkanes. The 90% weathered mixture followed the same degradation trend as the unweathered and 50% weathered samples, although it only contained two compounds. The loss rates/half-lives for each simple mixture sample (unweathered, 50% weathered, and 90% weathered) were determined to be approximately 3.5, 3.5, and 0.84 days. The unweathered and 50% weathered sample half-lives were similar due to containing compounds with similar susceptibility to degradation, while the 90% weathered sample contained one compound that was more highly susceptible to degradation. When comparing the 3.5 day half-life to the seven different ASTM class liquids, the isoparaffinic product and the naphthenic-paraffinic product had similar rates of degradation while aromatic solvent and normal alkane classes had the shortest half-lives. When observing the degradation of the gasoline, medium petroleum distillate and the miscellaneous, the constituent compounds were seen to exhibit a range of degradation rates that corresponded to half-lives less than and greater than 3.5 days.

This three-essay dissertation examines racial disparities in infant health outcomes and exposure to air pollution in Texas. It also asks whether the EPA's Risk-Screening Environmental Indicators Geographic Microdata (RSEI-GM) might be used to assess the effects of little-studied toxic air pollutants on infant health outcomes. Chapter 1 contributes to the ``weathering'' literature, which has shown that disparities in infant health outcomes between non-Hispanic black and non-Hispanic white women tend to widen with age. In this study, we ask whether the same patterns are observed in Texas and among Hispanic women, since other studies have focused on black and white women from other regions. We find that black and Hispanic women in Texas do ``weather'' earlier than white mothers with respect to rates of low birthweight and preterm birth. This differential weathering appears to be mediated by racial disparities in the distribution and response to socioeconomic risk factors, though a large gap between black and white mothers across all ages remains unexplained. Chapter 2 extends the statistical environmental justice literature by examining the distribution of toxic air pollution across infants in Texas. We find that, within Texas cities, being black or Hispanic is a significant predictor of how much pollution one is exposed to at birth. We further find that, among mothers who move between births, white mothers tend to move to significantly cleaner areas than black or Hispanic mothers. In Chapter 3, we use geocoded birth records matched to square-kilometer pollution concentration estimates from the RSEI-GM to ask whether the pollution-outcome relationships that emerge through regression analysis are similar to the effects found in previous research. If so, the RSEI-GM might be used to study the health effects of nearly 600 chemicals tracked in that dataset. We conclude, based on instability of results across various specifications and lack of correspondence to previous results, that the merged birth record-RSEI data are not appropriate for statistical epidemiology research.

Scope and contents: An investigation into some arctic soils located on Southwest Devon Island. Some aspects of chemical weathering in the area are considered and detailed studies of patterned ground are undertaken. A terrain map was compiled to locate the major areas of soils and mineral and organic covers and to show this relationship to relief units. / No abstract provided. / Thesis / Master of Science (MSc)