Дисертації з теми "Oxygen isotopes, atmospheric effects"
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Soens, Bastien. "Petrographic and geochemical characterization of the micrometeorite collection from the Sør Rondane Mountains: Nature and origin of the extraterrestrial flux to Earth." Doctoral thesis, Universite Libre de Bruxelles, 2021. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/331729.
Le continent antarctique a traditionnellement été un terrain de recherche fructueux pour le matériel extraterrestre en raison de son climat froid et sec. Les météorites et leurs analogues microscopiques, les micrométéorites, ont été à l'origine échantillonnés dans la glace et la neige de l'Antarctique. Plus récemment, une grande collection de micrométéorites a été découverte dans des pièges sédimentaires et des dépôts de moraine des montagnes transantarctiques, où des particules de poussière extraterrestres se sont accumulées pendant une période prolongée (environ 3-4 Ma). Les micrométéorites (ou « poussière cosmique ») présentent des signatures chimiques et isotopiques uniques, qui proviennent d'une quantité importante et diversifiée de corps astéroïdes et cométaires au sein du système solaire. En outre, elles documentent des événements majeurs tels que l'origine et l'évolution du système solaire et donnent un aperçu de la région source de leurs corps parents. Ces dépôts sédimentaires représentent par conséquent une archive précieuse qui documente le flux de matière extraterrestre vers la Terre et les événements météoritiques anciens au-dessus de l'Antarctique.Pourtant, une grande partie de cette information est perdue au cours de l'étape d'entrée dans l'atmosphère, où la poussière cosmique est soumise à un chauffage par friction et est partiellement ou complètement fondue. Cela peut altérer considérablement les propriétés physico-chimiques et isotopiques d'origine des particules de poussière extraterrestres. Une compréhension approfondie de ces processus physico-chimiques est donc nécessaire pour reconstituer l'entrée atmosphérique des poussières cosmiques (mais aussi des objets plus gros) et interpréter leurs données chimiques et isotopiques. Au cours de cette recherche de doctorat, plusieurs dépôts sédimentaires des montagnes Sør Rondane (Dronning Maud Land, Antarctique de l'Est) ont été examinés pétrographiquement et caractérisés chimiquement et isotopiquement. En outre, diverses expériences et modèles numériques ont été construits pour reproduire l'étape d'entrée dans l'atmosphère de matériaux météoritiques de petite et de grande taille.Cette étude a démontré que les dépôts sédimentaires des montagnes Sør Rondane contiennent une variété riche et peu altérée de matériaux extraterrestres et de cratères d’impacts, notamment des micrométéorites, des microtektites et des sphérules de condensation météoritique. L'analyse statistique suggère que la collection de micrométéorites des montagnes Sør Rondane est représentative du flux contemporain de poussière cosmique vers la Terre. La matière extraterrestre est soumise à une interaction complexe de processus d'oxydo-réduction et de volatilisation lors de l'entrée dans l'atmosphère, ce qui permet d'expliquer les tendances chimiques observées dans la poussière cosmique. Des études isotopiques suggèrent également qu'au moins une fraction mineure de la population de micrométéorites a échantillonné de nouveaux types inconnus d’astéroïdes et/ou de comètes. Les microtektites et les sphérules de condensation météoritiques ont été liées à des événements météoritiques majeurs sur Terre il y a ~790 ka et ~430 ka, respectivement, et soulignent l'importance de l'atmosphère terrestre lors de leur formation. Les résultats de cette recherche doctorale soulignent la valeur scientifique des dépôts sédimentaires de l'Antarctique et donnent un meilleur aperçu des processus qui se déroulent lors de l'entrée dans l'atmosphère de matière extraterrestre
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
Missell, Christine Ann. "Thermoregulatory adaptations of Acrocanthosaurus atokensis - evidence from oxygen isotopes." NCSU, 2004. http://www.lib.ncsu.edu/theses/available/etd-12312003-115912/.
Warrington, Anita Glasgow. "Stable isotopes of carbon and oxygen in the shells of terrestrial molluscs." Thesis, University of Liverpool, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316976.
Dejwakh, Navid Rene. "Using 15N, 18O, and 17O to Determine Nitrate Sources and Removal Processes from Groundwater, Tucson, Arizona." Thesis, The University of Arizona, 2008. http://hdl.handle.net/10150/193327.
Webb, Mathew Douglas. "Carbon, chloride, and oxygen isotopes as tracers of interbasin groundwater flow at La Selva Biological Station, Costa Rica." NCSU, 2007. http://www.lib.ncsu.edu/theses/available/etd-03262007-111350/.
Valdez, Adelia Christina. "Analysis of Atmospheric Effects Due to Atmospheric Oxygen on a Wideband Digital Signal in the 60 Ghz Band." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/35234.
Master of Science
Adiatma, Yoseph Datu. "Did early land plants produce a step-change in atmospheric oxygen centered on the Late Ordovician Sandbian Age ~458 Ma?" The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1546386257035643.
Mercer, A. P. "The effects of atmospheric humidity and oxygen on the wear of metals by fine abrasives." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356659.
Wilson, Jessica Norman. "Stable Isotopes and Trace Elements in Tooth Enamel Bioapatite: Effects of Diagenesis and Pretreatment on Primary Paleoecological Information." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4965.
Howard, Evan M. (Evan Michael). "Ecosystem metabolism in salt marsh tidal creeks and ponds : applying triple oxygen isotopes and other gas tracers to novel environments." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/109021.
Cataloged from PDF version of thesis. Page 216 blank.
Includes bibliographical references (pages 179-215).
Salt marshes are physically, chemically, and biologically dynamic environments found globally at temperate latitudes. Tidal creeks and marshtop ponds may expand at the expense of productive grass-covered marsh platform. It is therefore important to understand the present magnitude and drivers of production and respiration in these submerged environments in order to evaluate the future role of salt marshes as a carbon sink. This thesis describes new methods to apply the triple oxygen isotope tracer of photosynthetic production in a salt marsh. Additionally, noble gases are applied to constrain air-water exchange processes which affect metabolism tracers. These stable, natural abundance tracers complement traditional techniques for measuring metabolism. In particular, they highlight the potential importance of daytime oxygen sinks besides aerobic respiration, such as rising bubbles. In tidal creeks, increasing nutrients may increase both production and respiration, without any apparent change in the net metabolism. In ponds, daytime production and respiration are also tightly coupled, but there is high background respiration regardless of changes in daytime production. Both tidal creeks and ponds have higher respiration rates and lower production rates than the marsh platform, suggesting that expansion of these submerged environments could limit the ability of salt marshes to sequester carbon.
by Evan M. Howard.
Ph. D.
Hall, Veronica. "Addressing Water Resource Issues In Barbados Through An Isotopic and Atmospheric Characterization of Precipitation Variability." TopSCHOLAR®, 2014. http://digitalcommons.wku.edu/theses/1356.
Morin, Samuel. "Analyse de la composition isotopique de l'ion nitrate dans la basse atmosphère polaire et marine." Phd thesis, Université Paris-Est, 2008. http://tel.archives-ouvertes.fr/tel-00326229.
Davis, John Christopher. "Understanding the origin of 35/37Cl and 16/18O isotope effects on 195Pt and 103Rh NMR nuclear shielding in selected Pt(IV) and Rh(III) complexes : a DFT study." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/95484.
Amrhein, Daniel Edward. "Inferring ocean circulation during the last glacial maximum and last deglaciation using data and models." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/107085.
Ph. D. Joint Program in Oceanography (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2012
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 179-192).
Since the Last Glacial Maximum (LGM, ~ 20,000 years ago) air temperatures warmed, sea level rose roughly 130 meters, and atmospheric concentrations of carbon dioxide increased. This thesis combines global models and paleoceanographic observations to constrain the ocean's role in storing and transporting heat, salt, and other tracers during this time, with implications for understanding how the modem ocean works and how it might change in the future. -- By combining a kinematic ocean model with "upstream" and "downstream" deglacial oxygen isotope time series from benthic and planktonic foraminifera, I show that the data are in agreement with the modem circulation, quantify their power to infer circulation changes, and propose new data locations. -- An ocean general circulation model (the MITgcm) constrained to fit LGM sea surface temperature proxy observations reveals colder ocean temperatures, greater sea ice extent, and changes in ocean mixed layer depth, and suggests that some features in the data are not robust. -- A sensitivity analysis in the MITgcm demonstrates that changes in winds or in ocean turbulent transport can explain the hypothesis that the boundary between deep Atlantic waters originating from Northern and Southern Hemispheres was shallower at the LGM than it is today.
by Daniel Edward Amrhein.
Ph. D.
Leavitt, William Davie. "On the mechanisms of sulfur isotope fractionation during microbial sulfate reduction." Thesis, Harvard University, 2014. http://dissertations.umi.com/gsas.harvard:11511.
Earth and Planetary Sciences
Pollack, Gerald D. "Timing and Characterization of the Change in the Redox State of Uranium in Precambrian Surface Environments: A Proxy for the Oxidation State of the Atmosphere." unrestricted, 2008. http://etd.gsu.edu/theses/available/etd-12052008-125923/.
Title from file title page. Eirik J. Krogstad, committee chair; Andrey Bekker, committee co-chair; W. Crawford Elliott, Timothy E. LaTour, committee members. Description based on contents viewed Aug. 27, 2009. Includes bibliographical references (p. 207-219).
Vicars, William. "Transfert de l'anomalie isotopique portée par l'ozone dans la troposphère : vers une interprétation quantitative de la composition isotopique en oxygène du nitrate atmosphérique." Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00856960.
Köhler, Iris [Verfasser], Johannes [Akademischer Betreuer] Schnyder, Margaret [Akademischer Betreuer] Barbour, and Rainer [Akademischer Betreuer] Matyssek. "The interactive effects of rising atmospheric CO2 and nutrient supply on carbon and water relations in grassland ecosystems : an analysis of stable carbon isotopes and water-use efficiency in vegetation samples from the Park Grass Experiment / Iris Köhler. Gutachter: Margaret Barbour ; Rainer Matyssek ; Johannes Schnyder. Betreuer: Johannes Schnyder." München : Universitätsbibliothek der TU München, 2013. http://d-nb.info/1033403032/34.
Brandon, Margaux. "Les changements majeurs de la productivité biologique au cours du Quaternaire et leurs impacts sur les cycles du carbone et de l’oxygène." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASJ010.
During glacial-interglacial cycles of the Quaternary, the atmospheric CO₂ (pCO₂) concentration is associated with important variations, in particular during transitions between glacial and interglacial periods, also called terminations, with increases of up to 100 ppm of pCO₂ in a few thousand years. While the roles of oceanic circulation and sea-ice cover on pCO₂ are studied for several years now, little is known on the impact of biological productivity. The goal of this thesis is to reconstruct the past changes in biological productivity and to estimate their contributions on atmospheric pCO₂ variations over the last 800 000 years (ka), with particular attention to Termination V (~425 ka) and Marine Isotope Stage (MIS) 11, the interglacial period around 400 ka. Two different approaches were combined to reconstruct global and local variations of biological productivity. Measurements of Δ¹⁷O of O₂ in the air trapped in the Antarctic EPICA Dome C ice core between 400 and 800 ka allowed to complete the pre-existing record and trace back variations of global biosphere productivity expressed in oxygen fluxes over the past 800 ka. Micropaleontological (coccoliths, foraminifera) and geochemical (TOC, CaCO₃, XRF) analyses were performed on a sediment core of the Indian sector of the Southern Ocean (MD04-2718) to reconstruct the changes in biological pump efficiency over the past 800 ka. The results obtained during this thesis showed that, at the scale of glacial-interglacial cycles, global biospheric productivity and Southern Ocean carbonate production are more important during interglacial periods compared to glacial periods, minimizing the impact of marine organic productivity on atmospheric pCO₂. Termination V and MIS 11 register the strongest biosphere productivity of the past 800 ka and the highest marine carbonate production of the past 9 interglacial periods in the Southern Ocean. While the important carbonate production is a source of CO₂ for the atmosphere, the rise in biosphere productivity would counterbalance the increase in pCO₂ through photosynthesis
"Oxygen isotope effects in La0.67Ca0.33MnO3 thin films." 2005. http://library.cuhk.edu.hk/record=b5892665.
Thesis (M.Phil.)--Chinese University of Hong Kong, 2005.
Includes bibliographical references.
Text in English; abstracts in English and Chinese.
Li Chak Ming = 18O yang tong wei su xiao ying dui La0.67Ca0.33MnO3 bo mo zhi ying xiang / Li Zeming.
Acknowledgement --- p.i
Abstract --- p.ii
論文摘要 --- p.iii
Table of Contents --- p.iv
List of Figures --- p.viii
List of Tables --- p.xi
Chapter Chapter 1 --- Introduction
Chapter 1.1 --- Magnetoresistance (MR) 1 - --- p.1
Chapter 1.1.1 --- Magnetoresistance (MR) 1 - --- p.1
Chapter 1.1.2 --- Giant Magnetoresistance (GMR) 1 - --- p.1
Chapter 1.1.3 --- Anisotropy Magnetoresistance (AMR) 1 - --- p.2
Chapter 1.1.4 --- Colossal Magnetoresistance (CMR) --- p.1-4
Chapter 1.1.5 --- Double exchange mechanism 1 - --- p.6
Chapter 1.1.6 --- Jahn-Teller effect --- p.1-6
Chapter 1.1.7 --- Tolerance factor 1 - --- p.7
Chapter 1.1.8 --- The effect of doping --- p.1-10
Chapter 1.2 --- Possible origin of oxygen isotope effect --- p.1-12
Chapter 1.3 --- Our approach --- p.1-14
Chapter 1.4 --- Scope of this thesis work --- p.1-14
Chapter Chapter 2 --- Experimental methods
Chapter 2.1 --- Thin film deposition --- p.2-1
Chapter 2.1.1 --- Facing Target Sputering (FTS) --- p.2-1
Chapter 2.1.2 --- Vacuum system --- p.2-4
Chapter 2.2 --- Annealing systems --- p.2-6
Chapter 2.2.1 --- Oxygen annealing system --- p.2-6
Chapter 2.2.2 --- Oxygen exchange system --- p.2-8
Chapter 2.2.3 --- Vacuum annealing system --- p.2-10
Chapter 2.3 --- Characterization --- p.2-12
Chapter 2.3.1 --- a -step profilometer --- p.2-12
Chapter 2.3.2 --- X-ray diffraction (XRD) --- p.2-12
Chapter 2.3.3 --- Resistance measurement --- p.2-15
Chapter Chapter 3 --- Epitaxial growth of LCMO single layer thin film
Chapter 3.1 --- Fabrications and characterization of La0.67Ca0.33MnO3 target --- p.3-1
Chapter 3.2 --- Substrate materials --- p.3-6
Chapter 3.3 --- Preparation of LCMO thin film --- p.3-8
Chapter 3.3.1 --- Deposition conditions --- p.3-8
Chapter 3.3.2 --- Deposition procedure --- p.3-10
Chapter 3.3.3 --- Post-annealing effect --- p.3-13
Chapter Chapter 4 --- Oxygen in LCMO thin film
Chapter 4.1 --- Introduction --- p.4-1
Chapter 4.2 --- High Pressure Oxygenation --- p.4-2
Chapter 4.3 --- Characterization --- p.4-7
Chapter 4.3.1 --- Determination of oxygen content --- p.4-9
Chapter 4.3.2 --- "Tolerance factor, t" --- p.4-12
Chapter Chapter 5 --- Oxygen isotope effect in LCMO thin film
Chapter 5.1 --- Introduction --- p.5-1
Chapter 5.2 --- Identification on successiveness of oxygen exchange --- p.5-4
Chapter 5.2.1 --- Sample preparation --- p.5-4
Chapter 5.2.2 --- Oxygen annealing treatment --- p.5-4
Chapter 5.2.3 --- Identification of 18O by SIMS --- p.5-4
Chapter 5.3 --- Investigation of isotope effect on LCMO thin film --- p.5-7
Chapter 5.3.1 --- Sample preparation --- p.5-7
Chapter 5.3.2 --- Oxygen exchange --- p.5-7
Chapter 5.3.3 --- Vacuum annealing --- p.5-9
Chapter 5.3.4 --- Isotope effect --- p.5-9
Chapter 5.4 --- Conclusions --- p.5-19
Chapter Chapter 6 --- Isotope effect on the hopping activation energy
Chapter 6.1 --- Introduction --- p.6-1
Chapter 6.1.1 --- Variable range hopping --- p.6-2
Chapter 6.1.2 --- Small polaron models --- p.6-2
Chapter 6.2 --- Activation energy --- p.6-4
Chapter 6.3 --- Discussions --- p.6-9
Chapter Chapter 7 --- Conclusions --- p.7-1
St, Amour Natalie Ann. "A Multi-Proxy Study of Holocene Atmospheric Circulation Dynamics Recorded in Lake Sediments in Fennoscandia." Thesis, 2009. http://hdl.handle.net/10012/4225.
Jasechko, Scott. "Stable isotope mass balance of the North American Laurentian Great Lakes." Thesis, 2011. http://hdl.handle.net/10012/6302.
LIN, CHIA-YU, and 林家宇. "Effects of oxygen concentrations on the antibacterial efficiency of AgOx and TaOxNy-Ag thin films as well as TaN-Ag thin films treated by atmospheric pressure plasma jet." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/e8584x.
明志科技大學
材料工程系碩士班
105
AgxO thin films were deposited by reactive co-sputtering with various oxygen flow rates.The films' structural and mechanical properties were examined. Then, the samples were tested for their antibacterial behaviors against Escherichia coli. It was first found that the dissolution of Ag ion was varied depending on oxygen contents. The Ag ion concentration would reach a maximum value with the increase of oxygen contents, then level off. The antibacterial efficiency of TaOxNy-Ag films against Escherichia coli could be much improved, comparing with that of TaN-Ag films, i.e. the higher oxygen content, the better antibacterial efficiency. The reasons for this were found to be due to smaller metal particles for TaOxNy-Ag, and, more importantly, the existence of silver oxide. This result was proved with ICP-OES by measuring the solubility of metal ions. The annealed TaN-Ag thin films were then treated in either wet (immersed) environments by APPJ. It is found, after activation, the dissolution rate of Ag ions could be increased significantly. Hence the antibacterial efficiency was increased tremendously.