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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.
191

Predicting the Geographic Origin of Heroin by Multivariate Analysis of Elemental Composition and Strontium Isotope Ratios

DeBord, Joshua S 12 June 2018 (has links)
The goal of this research was to aid in the fight against the heroin and opioid epidemic by developing new methodology for heroin provenance determination and forensic sample comparison. Over 400 illicit heroin powder samples were analyzed using quadrupole and high-resolution inductively-coupled plasma mass spectrometry (Q-ICP-MS and HR-ICP-MS) in order to measure and identify elemental contaminants useful for associating heroin samples of common origin and differentiating heroin of different geographic origins. Additionally, 198 heroin samples were analyzed by multi-collector ICP-MS (MC-ICP-MS) to measure radiogenic strontium isotope ratios (87Sr/86Sr) with high-precision for heroin provenance determination, for the first time. Supervised discriminant analysis models were constructed to predict heroin origin using elemental composition. The model was able to correctly associate 88% of the samples to their region of origin. When 87Sr/86Sr data were combined with Q-ICP-MS elemental data, the correct association of heroin samples improved to ≥90% for all groups with an average of 93% correct classification. For forensic sample comparisons, quantitative elemental data (11 elements measured) from 120 samples, 30 from each of the four regions, were compared in order to assess the rate of discrimination (5400 total comparisons). Using a match criterion of ±3 standard deviations about the mean, only 14 of the 5400 possible comparison pairs were not discriminated resulting in a discrimination rate of 99.7%. For determining the rate of correct associations, 3 replicates of 24 duplicate samples were prepared and analyzed on separate days. Only 1 of the 24 correct pairs were not associated for a correct association rate of 95.8%. New methods for provenance determination and sample comparison are expected to be incredibly useful to intelligence agencies and law enforcement working to reduce the proliferation of heroin.
192

Assessment of hepatic micronutrient disruption and the hepatotoxicity of 3,3',4,4',5-pentachlorobiphenyl (PCB126)

Klaren, William Delbert 01 May 2016 (has links)
The prevalent and ongoing exposures to polychlorinated biphenyls (PCBs) demands an understanding of the threat they pose and also a means in which to mitigate their potential toxicity. This thesis set out to investigate a phenomenon associated with a specific PCB congener, 3,3',4,4',5-pentachlorobiphenyl (PCB126), for the underpinnings of its mechanism, and also its usefulness as a toxin against which to establish a mitigative strategy. The phenomenon in particular is the disruption of hepatic trace elements, specifically an increase in copper and decreases in zinc, selenium, iron, and manganese in the liver. Four questions were posed to address the overarching goals: 1) When does micronutrient disruption occur in the context of liver pathology? 2) What metal transporters or chaperones are involved? 3) Can the previously shown beneficial micronutrient, zinc, alter the disruption and improve outcome? 4) What is occurring spatially within the liver acinus where micronutrients are distributed? By answering these four questions, a fundamental understanding of this occurrence will be ascertained. A chronology of PCB126-hepatotoxicity showed onset of liver pathology at 36 hours and later alterations in micronutrients at 3 days, suggesting disruption of hepatic trace elements is likely the result of liver degeneration. In addition, a key metal transport protein, metallothionein, was induced by PCB126. Utilizing a double knockout animal model, metallothionein was shown to abrogate some toxicity but had little involvement of micronutrient perturbation. Previous investigations have suggested the unique property of zinc in rescuing/preventing hepatic damage by a variety of toxic agents. Dietary zinc had a modest effect in ameliorating PCB126 hepatotoxicity and preserving micronutrient homeostasis. This suggests that the mitigative potential of zinc supplementation on PCB126 exposure is limited. Finally, a fine spatial investigation of the liver acinus was conducted to establish the levels of trace elements from the portal triad to the central vein. In addition, novel findings of high concentrations of extracellular zinc were discovered. In all, this dissertation has shown that disruption of hepatic micronutrients caused by PCB126 are likely the result of liver degeneration by means of disturbing the spatial trace element gradients and provides appropriate context for therapeutic/preventive strategies against PCBs.
193

Mantle-crust Interaction in Granite Petrogenesis in Post-collisional Settings: Insights from the Danubian Variscan Plutons of the Romanian Southern Carpathians

Stremtan, Ciprian Cosmin 19 November 2014 (has links)
The issue of granite petrogenesis plays a key role in our overall understanding of the growth and differentiation of continents, as well as in our ability to unravel the tectonic histories of orogenic belts. Granites are ubiquitous magmatic products found in almost all tectonic settings: oceanic and continental rifts (i.e., plagiogranites - extreme basalt differentiates), active continental margins (e.g,. the granitic batholiths of central and southern Andes), continent-continent collision zones (e.g., the orogenic batholiths of the Himalayas, Western Anatolia), post-collisional settings (e.g., the Variscan provinces of Europe), complex within-plates settings (e.g., Limmo massif, Afar, Ethiopia). Furthermore, granitoids are characterized by considerable petrological and geochemical heterogeneity, as they can form from a vast array of sources: sediments (e.g., pelites, arkoses, psammites), metamorphic rocks (e.g., (mica)schists, gneisses, etc.), and igneous rocks (e.g. andesites, dacites, tonalites, etc.). Aside from fertile sources (i.e., protoliths), granite petrogenesis is dependent upon two critical parameters: temperature (to promote melting of the protoliths) and water availability - either as freely available aqueous solutions/vapors (e.g., water input in subduction zones); or water released via dehydration melting of hydrous minerals (e.g., micas, amphiboles). The presence of water in protoliths depresses the melting temperature of mineral components and provides the environment for redistribution of chemical components. Understanding the origins of granitic rocks presents unique challenges, given that in many of the tectonic settings where granites are encountered, it is clear that their modes of formation can involve a spectrum of igneous and metamorphic processes that are not readily accessible for examination, either through the study of modern environments or via analogy to "classical" localities. The petrogenesis and emplacement of granites in post-collisional tectonic settings is one of the thornier challenges, as these rocks appear to be derived via thermal and magmatic processes within highly deformed and compositionally diverse continental crust for which we lack a clear understanding. A number of unconventional and difficult-to-test mechanisms have been posited to drive crustal heating, melting, and subsequent pluton post-collisional emplacement. Although large volumes of granitic magmas have been emplaced in post-collisional settings, the complexities of the processes active in such settings make it challenging to put forward testable models that effectively combine available geochemical, petrologic, and geophysical data. Models for granite genesis away from plate margins (by means of crustal thickening, thermal blanketing, and internal heating from radioactive decay of 40K, 230Th, 235U, and 238U; delamination of the crustal lithosphere and juxtaposition of hot mantle melts at the base of the crust; underplating of mantle melts; or slab brake-off and upwelling of mantle melts) have been successfully applied in comparatively young orogenic regions, such as the Himalayas, the Carpathians, and Turkey. These models have proven challenging to employ in older orogenic belts, given their sometimes intricate tectonic and metamorphic histories, and the loss of pertinent evidence due to the effects of post-emplacement tectonic reworking, and often extensive alteration and erosion. A series of ancient but fresh, age-correlative granitic plutons are exposed in Alpine nappes on the flanks of the Carpathians Mountains in southwestern Romania. These granites, all mapped as intruding the Neoproterozoic basement of the Danubian tectonic terrane, were emplaced during the post-collisional stages of two world-scale orogenies: an older, Pan-African event (~600 Ma) and a younger, Variscan event (~330- 280 Ma). My dissertation is focused on the study of late Variscan post-collisional plutons and associated sub-volcanic dykes, as they are tremendous tools for understanding and quantifying the mantle-crust interaction in post-collisional environments and the overall evolution of the continental crust during the Variscan orogeny. Originally believed to be Proterozoic in age, zircon U/Pb dating showed that the plutons are much younger (Chapter 1 - Post-collisional Late Variscan magmatism in the Danubian domain (South Carpathians, Romania) documented by zircon U/Pb LA-ICP-MS) and correspond to the latest stages of the Variscan orogeny, as recorded elsewhere in the European Variscan provinces. The granitic plutons are relatively small and are generally concordant with the structures preserved by the country rocks. The extraordinary petrological and geochemical heterogeneities, even at pluton scale (Chapter 2 - Petrology and geochemistry of the Late Variscan post-collisional Furătura granitic pluton South. Carpathian Mts. (Romania)) argue against unique protoliths and simple evolutionary processes (e.g., closed-system fractional crystallization; anatexis). Trace elemental data for the Furătura pluton shows that the melts were formed in equilibrium with a garnet-amphibole restite, under pressure-temperature conditions deeper than the plagioclase stability field, implying that the melting took place at depths in excess of 40 km in the continental crust. Stable and radiogenic isotope data suggest that a protolith was of (possibly enriched) mantle affinities, and that the melts were subsequently contaminated in various degrees by deep crustal lithologies. In comparison, other post-collisional Variscan plutons from the Danubian domain (Chapter 4 - The role of the continental crust and lithospheric mantle in Variscan post-collisional magmatism - insights from Muntele Mic, Ogradena, Cherbelezu, Sfârdinu, and Culmea Cernei plutons (Romanian Southern Carpathians)) have trace elemental compositions that suggest they were formed at different levels in the crust, under P-T conditions corresponding to both garnet-amphibole and plagioclase stability fields. Some of the plutons lack mantle geochemical signatures and their isotopic compositions are indicative of substantial involvement of both lower- and upper-crustal rocks in their formation and subsequent evolution. On the other hand, plutons emplaced during the same time interval and most likely in close geographical proximity have trace elemental and isotopic compositions indicating strong input from previously enriched mantle components which experienced various degrees of assimilation fractionation-crystallization and/or assimilation of continental crust material during their evolution. This variability in both protoliths and processes responsible for the formation of the granites, coupled with the presence of mantle signatures in late-orogenic post-collisional melts are strong evidence to support delamination as means of providing both the mantle-derived input and energy required for generation of granitoids in the crust. The pronounced variation in petrological and chemical compositions of synchronous plutons suggests that delamination in the Danubian domain was not a single, large scale event that affected the entire crust, but rather a collection of disparate, spatially and chronologically limited event, that affected the Variscan crust during the latest stages of the orogeny. This hypothesis is further tested on a series of sub-volcanic dykes (the Motru Dyke Swarm) crosscutting the entire Danubian basement (Chapter 3 - Post-collisional magmatism associated with Variscan orogeny in the Danubian Domain (Romanian Southern Carpathians): the Motru Dyke Swarm). Initially, the emplacement age of these dykes was assumed as "pre-Silurian" but our mapping has showed that they intrude components of the Danubian domain that shared a documented common history not earlier than the Carboniferous. Furthermore, the dykes are in intrusive relationship with two of the Danubian Variscan plutons, thus arguing for an early Permian emplacement age. Geochemical data show extraordinary heterogeneities in the dykes' composition and record both mantle and crust involvement in their formation. The dykes were emplaced at much shallower depths in the crust, as compared with the granitic plutons. Still, their isotopic compositions clearly indicate that they sampled both lower- and upper-crustal compositions during their evolution. This means that after the crustal thickening episodes that define continent-continent collisions, during the latest stages of the Variscan orogeny, the crust became progressively thinner, as a way to compensate for its metastable state. Thinning of the crust is greatly favored by delamination of the lithosphere. A delamination event, which usually postdates the cessation of continental collision or prolonged crustal shortening, involves the geologically rapid foundering of negatively buoyant lithosphere comprised of mantle and (potentially) lower crust into underlying hotter and less dense asthenosphere. Such a process will remove the lithospheric mantle (and potentially segments of the lower crust) along pre-existing lineaments or mechanical flaws, and juxtapose hot upwelling asthenosphere against the base of the crust, leading to partial melting. Field, petrological, and geochemical data presented in my dissertation document pronounced variations in the overall composition of synchronous plutons and dykes, and further suggest that delamination in the Danubian domain was an active process. This bears great importance in our understanding of the evolution of the crust and argues that mantle-crust interactions are responsible for the generation of continental crust even in the latest stages of an orogen.
194

Selenium and trace mineral interaction in the nutrition of the growing pig.

Morrison, Linda L. January 1981 (has links)
No description available.
195

The biochemical basis of the effects of cobalt deficiency in sheep / Richard Miln Smith.

Smith, Richard Milne January 1975 (has links)
Includes 25 papers previously published in Journals / 114, 16 leaves : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (D.Sc.)--University of Adelaide, Dept. of Biochemistry, 1975
196

Studies of chemical speciation of trace metals in natural waters using an on-line electrochemical cell and ion exchange system

Sule, Pushkar Anant 22 April 1991 (has links)
Graduation date: 1991
197

Geochemical study of the Mesoproterozoic Belt-Purcell Supergroup, western North America : implications for provenance, weathering and diagenesis

Gonzalez-Alvarez, Ignacio Jose 04 January 2006
Provenance in the lower Belt-Purcell Supergroup is constrained based on geochemical systematics and chemical monazite ages of argillites and sandstones. Rare earth element (REE), Cr-Ni, and Th/Sc-Sc systematics is equivalent for both facies and consistent with a dominantly post-Archean source area. Detrital monazite chemical ages restrict major provenance for the Appekunny and Grinnell sandstones and argillites to Paleoproterozoic terranes at ~1800-1600 Ma, minor contributions at ~1600-1500 Ma, and marginal contributions from Archean terranes at ~2600, likely in Laurentia. Similar detrital age spectra for monazites of argillites and sandstones of the Appekunny Formation are consistent with a common provenance for the two facies.</p> <p>The Belt-Purcell sequence records three major diagenetic stages displayed in argillites and sandstones: (1) K-addition and rare earth element post-Archean upper continental crust (PA-UCC)-like pattern; (2) a stage characterized by heavy REE enrichment relative to light REE and HFSE fractionation, and U and Ce mobility; and (3) local dolomitization with REE and high field strenght elements (HFSE) mobility. REE and HFSE mobility are interpreted as the result of oxidized alkaline brines developed by dissolution of evaporites. Monazites from the Appekunny and Grinnell formations differ compositionally and texturally in two groups. Rounded or inclusions with ages >~1400 Ma, interpreted as detrital, have higher Th2O, Y2O3 and lower LREE/HREE contents than euhedral individual monazite grains with chemical ages <~1400 Ma that posses opposed compositional characteristics, and viewed as diagenetic. Monazites that span <~1400 to 300 Ma could be the result of basinal brine activity during stages (2) and (3). </p> <p>Chemical index of alteration (CIA) for argillites and sandstones, corrected for a diagenetic K-addition average 73 and 66 respectively. These results, coupled with correlation of CIA with Eu/Eu*, low K/Cs ratios, and low Sr, Ca, and Na relative to PA-UCC, could be interpreted as the result of an moderate weathered provenance in a hot, wet climate being drained by a large-scale river system. Presence of minor pristine feldspars lowers the CIA values, and may signify minor contributions from proximal source with short-river transport under the arid to semi-arid climate in the depositional setting. Moderate to intense weathering of the larger provenance may be associated with elevated levels of atmospheric CO2 degassed from a mantle plume implicated in the rifting of the supercontinent Columbia at ~1500 Ma.
198

Effect of Zinc, Copper and Selenium supplementation on the humoral immune response of weaned beef steers

Dill, Thomas O. 03 May 1991 (has links)
Two studies were conducted to determine the effects of zinc (Zn), copper (Cu) and/or selenium (Se) on the humoral immune response of weaned steers fed diets deficient in these minerals. Steers were bled weekly for eight weeks to measure plasma mineral levels. Humoral immune response was measured as antibody response to Keyhole limpet hemocyanin (KLH) over seven weeks of the trials. Steers were injected with 0.5 ml KLH vaccine on weeks 2 and 5 of the Zn study. Ten steers (5 per treatment) were randomly assigned to either a Zn supplemented (z), 3.25 ml injectable zinc-oxide suspension (100 mg/ml oil) or a control (c) treatment. Plasma Zn was maintained at higher (P<.05) levels in supplemented steers from week 3 through week 8. Humoral immune response was not different (P>.10) between treatments. In 1988, 20 steers were stratified by weaning weight and randomly assigned to one of four treatments: 1) Injectable Se 1 ml Mu-Se/ 90.9 kg body weight, 2) Injectable Molycu 2 ml, 3) control, or 4) Se + Cu. Plasma Cu was higher (P<.05) in treatments 2 and 4 from week 2 through 8. Steers were injected with 0.5 ml of KLH vaccine on weeks 2 and 6. Immune response was not different (P>.10) between Cu supplemented steers and other treatments. Plasma Se was higher (P<.05) in treatment 1 as compared to 2 and 3, but not different (P>.10) from 4. Immune response was highest (P<.05) in treatment 1 with others not different(P>.10). In 1990, a second trial was conducted with 48 steers stratified by weight and randomly assigned to one of the same four treatments. Plasma Cu was higher (P<.05) on week 3 for both groups receiving Cu. Plasma Se was higher (P<.05) on weeks 2 through 5 for both groups receiving Se. Humoral immune response was higher (P<.05) on weeks 7 and 8 for both groups receiving Se. Humoral immune response was uneffected by Zn status of weaned beef steers. Selenium had a positive effect and Cu had no effect on humoral immune response of weaned beef steers. Copper also tended (P=.07) to reduce the positive response from Se. / Graduation date: 1991
199

Trace Elemental Variation in Dosidicus Gigas Statoliths Using LA-ICP-MS

Arbuckle, Nancy 1980- 14 March 2013 (has links)
Range expansion events of the Humboldt squid reveal our inadequate understanding of populations of this species. Despite recent hatching, reproductive, tagging, genetic and dietary studies of Dosidicus gigas, much speculation remains concerning geographic migration, stock assessment and habitat preferences. This study provides evidence that statolith trace elemental variations can be useful in distinguishing among geographic populations. Specimens were collected from the Galapagos Islands, southern California, and Washington State. A dissection method was recorded and published. By using laser ablation methods, discrete measurements of 10 elements were collected at 6 to 7 ablation sites covering embryonic, paralarval, juvenile and adult stages. Analysis of Variance revealed important ontogenic elemental variations among ablation locations. Multivariate Analysis of Variance, ordination techniques and discriminant function analysis with permutation testing were all utilized to compare and characterize the variations found in elemental concentrations. Significant ontogenic variations were found for 8 out of the 10 focus elements; this is the first report for 5 of these elements for this species. The geographic populations were effectively classified as distinct group for the first time using these methods. Elemental fingerprint signatures were found to be significantly different at multiple ontogenic growth regions of the statolith. Seattle and California paralarvae exhibited similar elemental signatures despite significant differences in those found in the embryonic core and juvenile regions of the statolith. These methods are a useful tool in providing stock assessment and can be improved for use in future population dynamics models.
200

Origin of rutile-bearing ilmenite Fe-Ti deposits in Proterozoic anorthosite massifs of the Grenville Province

Morisset, Caroline-Emmanuelle 11 1900 (has links)
The Saint-Urbain and Big Island rutile-bearing ilmenite Fe-Ti oxide deposits are located in the composite 450 km² Saint-Urbain anorthosite (1055-1046 Ma, U-Pb zircon) and in the Lac Allard intrusion (1057-1062 Ma, U-Pb zircon) of the 11,000 km² Havre-Saint Pierre anorthosite suite, respectively, in the Grenville Province of Eastern Canada. Slow cooling rates of 3-4°C/m.y. are estimated for both anorthosites, based on combined U-Pb zircon/rutile/apatite and ⁴⁰Ar/³⁹ Ar biotite/plagioclase geochronology, and resulted from emplacement during the active Ottawan Orogeny. Slow cooling facilitated (1) diffusion of Zr from ilmenite and rutile, producing thin (10-100 microns) zircon rims on these minerals, and (2) formation of sapphirine via sub-so lidus reactions of the type: spinel + orthopyroxene + rutile ± corundum → sapphirine + ilmenite. New chemical and analytical methods were developed to determine the trace element concentrations and Hf isotopic compositions of Ti-based oxides. Rutile is a magmatic phase in the deposits with minimum crystallization temperatures of 781°C to 1016°C, calculated by Zr-in rutile thermometry. Ilmenite present in rutile-free samples has higher Xhem (hematite proportion in ilmenite), higher high field strength element concentrations (Xhem = 30-17; Nb = 16.1-30.5 ppm; Ta 1.28-1.70 ppm), and crystallized at higher temperatures than ilmenite with more fractionated compositions (Xhem = 21-11; Nb = 1.36-3.11 ppm; Ta = <0.18 ppm) from rutile-bearing rocks. The oxide deposits formed by density segregation and accumulation at the bottom of magma reservoirs, in conditions closed to oxygen, from magmas enriched in Fe and Ti. The initial ¹⁷⁶Hf/¹⁷⁷ Hf of rutile and ilmenite (Saint Urbain [SU] = 0.28219-0.28227, Big Island [BI] = 0.28218-0.28222), and the initial Pb isotopic ratios (e.g.²⁰⁶Pb/²⁰⁴ Pb: SU = 17.134-17.164, BI = 17.012-17.036) and ⁸⁷Sr/⁸⁶ Sr (SU = 0.70399-0.70532, BI = 0.70412-0.70427) of plagioclase from the deposits overlap with the initial isotopic ratios of ilmenite and plagioclase from each host anorthosite, which indicates that they have common parent magmas and sources. The parent magmas were derived from a relatively depleted mantle reservoir that appears to be the primary source of all Grenvillian anorthosite massifs and existed for --600 m.y. along the margin of Laurentia during the Proterozoic.

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