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Steady State Simulation of Pyrolysis Gases in an Inductively Coupled Plasma FacilityMartin, Nicholas C. 01 January 2017 (has links)
An important step in the more efficient use of PICA (Phenolic Impregnated Carbon Ablator) as a Thermal Protection System (TPS) material for spacecraft is the understanding of its pyrolysis mechanics. The gases released during pyrolysis and their subsequent interaction with the reactive plasma environment is not yet well understood. The surface recession of PICA as it ablates during testing only makes the study and characterization of the chemical reactions more difficult. To this end, a probe has been designed for this study to simulate, in steady state, the pyrolysis gases within the UVM 30kW Inductively Coupled Plasma (ICP) Torch Facility. This probe, which is an extension of previous work done at UVM, has been used to inject Carbon Dioxide, Hydrogen, and a mixture of the two into pure Argon and dilute Nitrogen, Oxygen, and air plasmas. During testing, spatially resolved, pointwise, line of sight emission measurements were taken in the boundary layer region. These results were then compared to temporally resolved PICA emission data taken in a previous study. After the correct temporal PICA scan was found the data sets closely matched. This indicates that the gas-injection probe is a viable method to simulate pyrolysis in a steady state environment. The key pyrolysis species of CN, NH, OH, Hydrogen Alpha (Hα), and Hydrogen Beta (Hβ) were spatially traced along the stagnation line for the pure Hydrogen and mixture injection cases. These measurements show evidence of spatial relationships between NH and Hα as well as between OH and Hβ. They also show that all of the molecules tend to follow the same general trend spatially. The work done for this study has both reintegrated gas-injection capability into the UVM facility as well as laid the groundwork for future gas-injection testing within the facility. Spatial emission analysis techniques currently being developed at UVM will provide a more resolved picture of the interactions occurring in the boundary layer once completed.
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Formation of Rapakivi Feldspars in the Deer Isle Granite Complex, Coastal Maine: <em>In Situ</em> Lead Isotope and Trace Element AnalysisOBrien, William Desmond 01 June 2017 (has links)
Rapakivi and alkali feldspar phenocrysts from the Deer Isle Granite Complex were investigated using in situ trace element and Pb isotope geochemistry to see if magma mixing or isothermal decompression was responsible for their formation. Pb isotope and trace element profiles, along with CL imagery of quartz phenocrysts, indicate compositional changes in the magma chamber occurred during rapakivi and alkali feldspar growth. Repeated episodes of magma mixing/replenishment by relatively isotopically primitive and LREE enriched magmas (along with hybridized variations with the host magma) created localized disequilibration. Alkali feldspar phenocrysts proximal to these zones of thermal perturbation were first resorbed and then mantled by plagioclase. Entrainment back into this zone of mixing caused multiple mantles of plagioclase to form on some phenocrysts. For grains more distal to these zones of mixing, complete disequilibration of the grain did not occur and continued growth resulted in Ba-rich alkali feldspar mantles over Ba-poor alkali feldspar cores. As crystallization of the chamber continued along solidification fronts, batches of cooler crystal-rich magmas settled en masse to the floor. Disaggregation of these batches during settling, and subsequent accumulation on the chambers floor, brought grains with disparate crystallization histories together. Filter pressing of the cumulate pile flushed highly evolved fluids out from interstitial pores. Small amounts of evolved liquid, trapped interstitial to the cumulate, formed LREE depleted albitic rims on some grains. The crystallization, transportation and juxtaposition of rapakivi, mantled alkali feldspar and plagioclase phenocrysts suggests that a relatively large and active magma chamber, periodically recharged by batches of melt, must have existed.
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An investigation of koi carp (Cyprinus carpio) movement in the Waikato region using laser ablation otolith microchemistryBlair, Jennifer Marie January 2008 (has links)
The koi carp Cyprinus carpio is an invasive fish that has reached high numbers and biomass in the North Island of New Zealand, particularly in the Waikato region. This species has a variety of negative effects on aquatic ecosystems, increasing turbidity, uprooting aquatic macrophytes, and affecting water column nutrient levels. Recent research in Australia and New Zealand has shown that adult carp, though largely restricted to small scale movements, are capable of moving long distances. Movement in adult carp may be underestimated by these studies, and comparatively little is known about the movement of smaller carp. This study examined the feasibility of using laser ablation otolith microchemistry to track koi carp movement and identify spawning areas. Water samples from six locations (Lake Waahi, Lake Whangape, Lake Waikare, the Whangamarino River, and the Waikato River at Aka Aka and Rangiriri) were analysed using inductively coupled plasma mass spectrometry (ICP-MS). Significant differences between sites were found in the water concentrations of many elements. Koi carp were collected from the above locations, as well as from Opuatia Stream, Pungarehu Stream, the Maramarua River and Lake Hakanoa. The elemental concentrations in the asteriscus otoliths were analysed using laser ablation inductively coupled plasma mass spectrometry (LA‐ICP-MS). Elemental concentrations in the edges and nuclei of adult koi carp and the edges of young-of-the-year (YOY) koi carp were significantly different between capture sites. No significant differences were found in elemental concentrations between sites in the nuclei of YOY koi carp. A discriminant function analysis (DFA) was carried out using the otolith edge elemental signatures of koi carp. The model used Ba, Sr, Mg, Rb and Zn concentrations to differentiate between four capture locations: the Waikato River, Pungarehu Stream, Lake Waahi, and Lake Waikare and Pungarehu Stream. The DFA was able to correctly predict the capture location of 82% of koi carp using their otolith edge elemental signatures. The classification functions created using koi carp otolith edge signatures were then used as a training set to classify otolith nucleus signatures. The otolith nuclei of 80% of YOY koi carp were classified to their site of capture, suggesting they had not moved between locations. The majority of adult koi carp caught at Lake Waikare, Whangamarino River, Pungarehu Stream and Opuatia Stream had nucleus signatures matching their capture sites, indicating that these fish originated from their capture location. Koi carp from other sites likely moved there from another location. The majority of adult koi carp (88%) caught at the Waikato River at Rangiriri had otolith nucleus signatures matching Lake Waikare and Pungarehu Stream. Adult koi carp caught at Lake Waahi and the Waikato River at Aka Aka had otolith signatures corresponding to a range of locations. While some areas (Lake Waikare, Pungarehu Stream) appear to have resident koi carp populations that likely originated there, others (Lake Waahi, the Waikato River) appear to have koi carp populations of mixed origin. These results indicate that Lake Waikare, Pungarehu Stream and the Whangamarino River may be important sources of koi carp recruits in the lower Waikato region.
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The optimisation of a method for total selenium analysis and application to cereal grain foodsElis, [forename not supplied], elis.cen@student.rmit.edu.au January 2008 (has links)
Cereal based foods, including breakfast cereals and Asian noodles are potentially good sources of selenium. Although these are major foods consumed globally, their contribution to dietary intakes of selenium is unclear. In addition, there has been very limited research into the effect of processing steps on the analysis and apparent retention of selenium. The low levels typically present in foods and the presence of multiple chemical forms of the element provide significant analytical challenges to research in this area. Therefore, the aims of this study were firstly to evaluate and validate procedures for extraction and measurement of selenium in wheat flour. Secondly, the procedure has been applied to analysis of selenium in cereal foods. The methods employed were firstly validated using wheat-based reference materials and then samples of various breakfast cereals as well as different styles of Asian noodles were analysed. Selenium was extracted using closed- v essels by microwave digestion with a mixture of nitric acid and hydrogen peroxide, followed by determination through Inductively Coupled Plasma - Mass Spectrometry (ICP-MS). The optimum conditions for selenium determination in cereal based foods involved the digestion of 0.1 g samples using 1 mL of nitric acid and 1 mL of hydrogen peroxide. The addition of 1% (v/v) methanol was found to enhance the sensitivity of the ICP-MS system. Two particular isotopes of selenium (77 and 82) could be effectively employed in the analysis and there was no significant decrease in total selenium in the digested extracts during storage for up to twelve days under refrigeration and room temperature conditions. Good precision levels were obtained and the total selenium levels in the breakfast cereal samples ranged from 0.059 to 0.378 µg/g. For white salted noodles the values varied between 0.057 and 0.712 µg/g, for yellow alkaline noodles, 0.109 to 0.265 µg/g and 0.077 to 0.284 µg/g for fried instant noodles. There was no appar ent change observed in total selenium during the processing of fried instant noodles, indicating the effectiveness of the extraction method developed here. It is concluded that microwave digestion is an effective approach to sample extraction, the procedures validated in this study are suitable for cereal grain foods and that there is considerable variation in the selenium contents of breakfast cereal and Asian noodle products.
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Determination of antimony in water, beverages, and fruitsXia, Yunlong 06 1900 (has links)
Antimony is naturally occurring in the environment. The assessment of human exposure to environmental antimony is limited. This research focuses on the determination of antimony in water, beverages, and fruit.
First, we explored whether there is a correlation between arsenic and antimony in water samples with a wide range of arsenic and antimony concentrations. The results showed absent correlation.
Second, we determined antimony concentrations in bottled beverages including bottled water, soft drinks, juices and alcoholic drinks from Canada. The results showed that the antimony in most of these samples were below the Health Canada Guideline (6 g/L) for drinking water except one alcoholic drink which contains 7 g/L antimony.
Further analysis of lemons and oranges using high performance liquid chromatography (HPLC) separation and inductively coupled plasma mass spectrometry (ICP-MS) detection demonstrated the presence of antimonycitrate species in these fruits, which has not been reported in literature.
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noneTai, Chia-yi 21 July 2010 (has links)
none
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Determination of Trace Multi-element in Foods and The Speciation Analysis of Cr¡BAs and Se Using ICP-MSLiao, Shu-ling 21 July 2011 (has links)
none
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Speciation Analysis of Mercury in Fish Samples by Capillary Electrophoresis Inductively Coupled Plasma Mass Spectrometry Speciation Analysis of Cobalt compounds by Reversed Phase High Performance Liquid Chromatography Inductively Coupled Plasma Mass SpectrometryYang, Fang-Yu 25 July 2011 (has links)
none
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Microwave-assisted volatilization of matrix for the determination of trace impurities in high purity Se¡BGe¡BSi and quartz by ICP-MSUeng, Ruey-Lin 27 June 2004 (has links)
Closed-vessel microwave assisted volatilization of Ge, Se, Si and quartz as their volatile compounds , for the determination of trace impurities in high purity Ge, Se, Si and quartz is reported. The volatilization of Ge is 98.7% using vapors of aqua regia whereas vapors generated from 72:1 ratio of HCl:HNO3 is required to volatilize 99.2% of Se. Using vapor of 10:5 ratio of HF:HNO3 , the volatilization of Si is 98.6%, and the volatilization of quartz is 99.0% with 15:3 ratio of the mixed acids. The recoveries of Mg, Cr, Mn,, Ni, Co, Cu, Zn, Cd, Ba and Pb are in the range 83-116%. Determinations are carried out using inductively coupled plasma mass spectrometer with Dynamic Reaction CellTM (DRC ICP-MS). Isobaric interferences, due to the formation of 40Ar12C+, 35Cl16OH+, 40Ar16O+ and 40Ar74Ge+ on the determination of 52Cr+, 56Fe+ and 114Cd+, have been alleviated using ammonia cell gas in DRC. Matrix volatilization using in situ generated acid vapors in closed containers resulted in sub ng mL-1 experimental blanks. Method detection limits are in the low ng g-1 level. The methods developed have been applied to determine trace impurities in high purity Ge, Se, Si and quartz samples.
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Determination of arsenic and selenium compounds in water samples and organotin compounds in fish samples by LC-ICP-MSLai, Pei-shan 12 July 2004 (has links)
Determination of arsenic and selenium compounds in water samples
organotin compounds in fish samples by LC-ICP-MS
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