京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20186号 / 理博第4271号 / 新制||理||1614(附属図書館) / 京都大学大学院理学研究科地球惑星科学専攻 / (主査)准教授 齊藤 昭則, 教授 田口 聡, 教授 塩谷 雅人 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第21434号 / エネ博第376号 / 京都大学大学院エネルギー科学研究科エネルギー変換科学専攻 / (主査)教授 木村 晃彦, 教授 星出 敏彦, 教授 今谷 勝次 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DGAM

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Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has risen to among the top tier techniques for the direct analysis of solid samples. However, significant problems remain that must be solved to achieve the full analytical potential of LA-ICP-MS. Inefficient conversion of aerosol to ions within the ICP or transmission through the MS interface may decrease precision, sensitivity, and/or accuracy. Although fundamental mechanisms that govern ion production and transmission have been studied extensively in solution-nebulization (SN) ICP-MS instruments, significant gaps in our understanding remain. Furthermore, it is unclear to what extent differences between the aerosols generated during SN and LA influence either ion production or transmission. In this work, I initially investigated differences in the spatial distributions of Ca, Ba, and Sc ions generated by LA and SN using high-resolution LIF imaging. Ions formed from aerosol generated by LA at low fluence were distributed over much greater axial and narrower radial distances than SN aerosol. Additionally, I investigated the effects of solvent, laser fluence, and ablation atmosphere (He vs Ar) on ion distributions in the ICP. Unlike solvent, changing laser fluence and ablation atmosphere produced considerable changes in the ion signal intensity and spatial distribution during LA. At greater laser fluence, the radial distance over which ions were distributed dramatically increased. Surprisingly, when helium was mixed with argon as carrier gas, ion signals decreased. Many of these effects were assumed to be related to changes in the number and size of particles generated during LA. In a follow-up study, relative contributions to ion densities in the ICP from particles of different sizes were investigated. LIF images were recorded while filtering particles above a threshold size on-line. Micron-sized particles contributed the majority of ions formed in the ICP. For Ba, Ca, and Sc, differences in the axial position where nanometer- and micron-sized particles vaporized were 2, 1, and less than 1 mm, respectively. I also performed experiments to identify changes in the ion signal related to changing ablation conditions vs. changing ICP conditions associated with helium additions to the carrier gas. LIF images were recorded during different combinations of He/Ar added upstream and/or downstream of the ablation cell. Changes in the ion signal during ablation in helium vs argon did not always match expectations based on changes in particle numbers and sizes measured with SEM. The results force re-examination of some of the fundamental assumptions about the effect of carrier gas composition on the performance of LA-ICP-MS. The research described in this dissertation provides valuable insight into fundamental aspects of key ICP processes related to LA generated aerosol.

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<p> An age of approximately 55K years was found for the St. Clair basin clays using helium isotope dating. This is about 5 times larger than the date obtained from the more accepted carbon-14 method and from other geological evidence. Diffusion of helium from crustal rocks against a flow of approximately 0.03-0.05 cm a· ' is the primary reason for this discrepancy. Mixing of the groundwater with a meteoric component has an opposite effect tending to lower the helium age. </p> / Thesis / Bachelor of Science (BSc)

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I denna uppsats analyseras bilderboken Musse &amp; Helium, i duvjägarnas klor (2020) skriven av Camilla Brinck. Syftet med bilderboksanalysen är att undersöka hur karaktärerna i bilderboken Musse &amp; Helium, i duvjägarnas klor (2020) gestaltas utifrån ett genusperspektiv samt hur de förhåller sig till traditionella könsmönster i barnlitteratur. Utöver bilderboksanalysen diskuterar vi hur bilderböcker i allmänhet kan användas för att främja lärande om genus. Uppsatsen har ett hermeneutistiskt förhållningssätt som utgår från en kvalitativ bild- och textanalys där vi med fokus på vår tolkning skapar mening utifrån det som vi anser mest väsentligt i text och bild i förhållande till våra forskningsfrågor. Karaktärerna som analyseras är huvudkaraktärer, motståndare och medhjälpare. För att synliggöra traditionella könsmönster hos karaktärerna gjordes analysen med hjälp av litteraturvetaren Maria Nikolajevas (2004) karaktärsdrags-schema för barnlitteratur. Studiens resultat visar att bokens huvudkaraktärer utmanar traditionella könsmönster medan medhjälpare och motståndare bekräftar dem. Vidare visar studiens resultat att lärare bör besitta mycket goda kunskaper kring genus. Lärare bör kunna sätta in sådant som rör kön och genus i ett större sammanhang för att se till att skolans jämställdhetsmål uppnås.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Science, 1982. / Microfiche copy available in Archives and Science. / Bibliography: leaves 265-290. / by Mark David Kurz. / Ph.D.