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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
221

Sulphur Isotope Fractionation in Smelter Emission Streams and Precipitation Sudbury, Ontario

Snyder, Warren 04 1900 (has links)
<p> International Nickel Company's 1250 ft. stack located in Sudbury, Ontario emits an estimated 3,000 tons of sulphur oxide daily. The purpose of this study is to investigate the use of stable sulphur isotopes as a means of tracing the movement of these sulphur oxide emissions. Sulphur isotope analysis were done for lakewater, rainwater and sediment samples taken from the Sudbury-Timagami district and also for particulate and gas samples taken from the 600 ft. level of the International Nickel Company's 1250 ft. stack. </p> <p> The s s^34 values of lake surface samples showed a decrease related directly to the increase of the logarithm of the distance from Sudbury. The maximum s s^34 value for the lakewater samples was + 8.49 p.p.t. at a distance of 7 miles from Sudbury. The minimum s s^34 value for lakewater samples was+2.97 p.p.t. at a distance of 55 miles from Sudbury. </p> <p> The rainwater s s^34 values vary from + 4.85 p.p.t. recorded for a station 5 miles north of Sudbury to + 2.07 p.p.t. for a station 60 miles east north east of Sudbury. </p> <p> The increase in s s^34 values in the lakewater relative to rainwater strongly suggest that the oxidation of so2(g) to s4^2- is occurring in the lakes in the Sudbury-Timagami district. </p> / Thesis / Bachelor of Arts (BA)
222

A Stable Isotope Investigation of Diet at Vagnari

Semchuk, Lisa January 2016 (has links)
This thesis applies stable isotope analysis to the study of diet from a rural Roman estate, Vagnari (1st – 4th centuries AD), in southern Italy. The major objectives of this research are to identify the types of food eaten in the Vagnari skeletal sample from stable isotope ratios, as well as to explore individual variation in diet in the sample. Isotopic composition of collagen and carbonate indicate a diet heavy in C₃ plants with the incorporation of some animal-based proteins. Isotopes of carbon from collagen (δ¹³C) were relatively consistent across the sample, with some variation according to burial type. Nitrogen (δ¹⁵N) values varied with age-at-death and the number of grave goods buried with an individual, suggesting possible status-based variation in diet. Carbon isotopes from carbonate (δ¹³Cₐₚ) suggested variation in total diet with increased age-at-death. Isotope ratios from Vagnari were also compared with other Imperial Italian sites to situate the diet within a broader Roman context. Isotopically, diets at Vagnari were most similar to other inland and rural sites, and distinct from coastal urban diets based on marine fish. These results indicate the diversity in foods eaten in the Roman Empire, both at a local site level and between different settlements. Studying diet from Vagnari provides another window into the lives of people who lived and worked on industrial estates, and bolsters knowledge of the diets of rural residents, which are underrepresented in the literature. / Thesis / Master of Arts (MA)
223

Oxygen isotope fractionation between hydroxyapatite (HAP)-bound carbonate and water at low temperatures

Ie, Kesia January 2016 (has links)
Calcium phosphates are important compounds as they exist in natural aqueous systems such as rivers, lakes, ocean, and soil. These calcium phosphates are widely used to provide information on paleotemperatures as well as many anthropological features, such as paleodiets. One of the most ubiquitous forms of calcium phosphate is hydroxyapatite (Ca10(PO4)6(OH)2) which is a major component of hard tissue such as bones, fossils, and tooth enamel. The oxygen isotope systematics in the hydroxyapatite associated with carbonate-water system will provide further information to allow for the reconstruction of terrestrial and marine environments. For example, Fricke et al. (1998) used oxygen isotope analysis of the carbonate components of hydroxyapatite in tooth enamel of mammals to investigate changes in terrestrial climate. Therefore, the purpose of this research study was to examine the oxygen isotope systematics in inorganic carbonate-bearing hydroxyapatite and water at low temperatures. This Master’s thesis followed and modified the methods described in Lécuyer et al. (2010) in an attempt to synthesize hydroxyapatite crystals and carbonate-bearing hydroxyapatite. The crystals synthesized were characterized in terms of several conditions (i.e., influence of mixing rate and maturations, pH, and concentrations of NaHCO3). Methods to produce hydroxyapatite were developed and analyzed using X-Ray diffraction analysis. The results demonstrated a strong dependence of pH in the hydroxyapatite solutions. Moreover, the effect of concentrations of NaHCO3 was deemed to be essential in order to obtain the desired amount of structural carbonates in the hydroxyapatite crystals. Furthermore, this research evaluated the temperature dependence of oxygen isotopic fractionation between HAP-bound carbonate and water at 10, 25, and 40 oC. Our study is the first to assess the two mixing-rates experiments with different maturations (7 and 14 days) on the oxygen isotope effects and fractionation behaviour between HAP-bound carbonate and water. Both maturation time and the effect of initial concentration of NaHCO3 were found to be the most important in determining the equilibrium conditions in our experiments. / Dissertation / Master of Science (MSc)
224

δ<sup>13</sup>C of Cave Speleothems Located in Kentucky and Ohio, U.S.A.: Implication for Paleovegetation and Paleoclimate Studies

Miller, Brett Alan 23 March 2008 (has links)
No description available.
225

Oxygen isotope studies of zeolites: Stilbite, analcime, heulandite and clinoptilolite

Feng, Xiahong January 1991 (has links)
No description available.
226

The Evolution of a Chemically Zoned Magma Chamber: the 1707 Eruption of Fuji Volcano, Japan

Watanabe, Shizuko 05 December 2003 (has links)
No description available.
227

Os-Sr-Nd-Pb ISOTOPIC AND TRACE ELEMENT STUDY OF MAGMATIC PROCESSES WITHIN THE SIERRA DEL CHICHINAUTZIN VOLCANIC FIELD, TRANS-MEXICAN VOLCANIC BELT

Cosky, Brian Wright 10 December 2010 (has links)
No description available.
228

Application of Internal Competition Kinetics to Probe the Catalytic Strategies of RNA 2’-O-transphosphorylation

Kellerman, Daniel 27 January 2016 (has links)
No description available.
229

Oxygen and Carbon Stable Isotope Analysis of the Otoliths of Atlantic Cod (Gadus Morhua L.)

Browne, David. R 01 May 1995 (has links)
The purpose of this study was to apply oxygen and carbon stable isotope microsampling techniques to the seasonal banding of the otoliths of the Atlantic cod, Gadus morhu~ in order to determine their potential use in reconstructing the environmental conditions experienced by cod. A reconstruction of the changes in environmental temperature is seen as particularly applicable to the determination of cod migration routes based on the known temperature profile of the North Atlantic. Transverse thin sections of six otoliths from cod taken off the coast of Atlantic Canada were prepared using standard methods. Material was sampled from each semiannual band of the otoliths and run on a Finnigan MAT 251 ratio mass spectrometer to determine 0180 and 013C. The results for 0180 indicated that the otoliths had an approximate initial value of either 1.4%o or l.O%o for sample material taken from the nucleus. The 0180 signal was characterized by oscillating values in which sample material from hyaline bands corresponded predominantly with the troughs and sample material from the opaque bands corresponded with the peaks. The average range of 0180 was found to be 0.87%o corresponding to a temperature range of 3.6°C which was within the expected 3 to 4 °C seasonal average temperature shift experienced by cod. Seasonal cycling was apparent in three of the otoliths, with semi-annual values alternating between high opaque bands and low hyaline bands. It was concluded that seasonal temperature changes due to migration from offshore to inshore waters are recorded in the 0180 signal and that future sampling should attempt to resolve several samples within each seasonal band in order to resolve the migratory changes in temperature on an sub-annual basis. It is also suggested that experiments be carried out to determine the species specific 0180 versus temperature relationship for cod to make accurate interpretation of the data possible. The o13C signal was found to be characterized by an increasing logarithmic trend in o13C. The 013C signal was observed to increase over the first three years of growth and to level off at age 4 and fluctuate at a value close to O%o. The otoliths of cod were found to contain a high proportion of inorganic carbon with a minimum 013C value of -4.53%o and a maximum of 0.23%o. It was suggested that the initial increase in 013C was a product of a combination of factors affecting metabolic rate and therefore, indirectly, the amount of metabolically derived carbon circulating in the blood. It was concluded that further research into the growth and development of cod was necessary in order to reach a comprehensive understanding of the biological processes responsible for the observed trends in 013C. 0180 was plotted against 013C for samples from growth bands of age four or greater and found to have a positive correlation with a slope of 0.269 (S.E. 0.049) and an r-squared of 0.537, P < 0.0001 when the results for otolith 176 were excluded due an anomalous trend in that data set. Two hypotheses were suggested to account for the observed positive correlation, a metabolic/temperature effect, and a depth/temperature effect. It was concluded that, with further research into the controlling factors behind the fluctuations in 013C, the 013C signal may provide a second source of information with regards to changes in habitat and environmental characteristics over the life time of the cod. It is suggested that a study be carried out to determine the amount of metabolic carbon incorporated into the otolith in order to clarify the observed trends. / Thesis / Candidate in Philosophy
230

Ultratrace Lithium and Boron Analysis by Neutron Activation and Helium Isotope Mass Spectrometry / Li and B Analysis by NAA and He Isotope Mass Spectrometry

Olson, Edith 08 1900 (has links)
The binding of the elements lithium and boron to human plasma proteins is investigated through the techniques of thermal neutron activation and helium isotope mass spectrometry. Since normal physiological levels of lithium and boron in blood and plasma are in the ultratrace (ppb) range, lithium in particular is frequently below the detection limit of many instruments. The success of the detection method used in this work is due to the extremely large cross section of ⁶Li for the thermal neutron reaction ⁶Li(n,³H)⁴He, and of ¹⁰B for the thermal neutron reaction ¹⁰B(n,α)⁷Li. The high sensitivity of the mass spectrometer, originally designed for oceanographic studies of helium isotopes and tritium, allows measurement of as little as 2x10⁴ atoms of ³He from the decay of tritium, and 2x10¹⁰ atoms of ⁴He from alpha-particles. It has frequently been stated that lithium does not bind to plasma proteins. However, our results clearly show that lithium does bind to a number of these proteins, at least 𝘪𝘯 𝘷𝘪𝘵𝘳𝘰. Boron is also shown to bind to proteins, with a pattern similar to that of lithium . Although a clear identification of the specific plasma proteins which bind lithium and boron must await further investigation, a number of possibilities are suggested here, based on the data obtained. / Thesis / Master of Science (MSc)

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