アパタイト前駆体機能による生体環境調和インプラント材料の開発

京都大学0048新制・課程博士博士(エネルギー科学)甲第22796号エネ博第410号新制||エネ||78(附属図書館)京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻(主査)教授 坂口 浩司, 教授 佐川 尚, 准教授 高井 茂臣学位規則第4条第1項該当Doctor of Energy ScienceKyoto UniversityDFA

Plasmonic excitations and coupling in atomic wires

Metal-induced atomic wires on the semiconductor surfaces are the ultimate limit of long-range ordered quasi-one-dimensional electronic systems. In this thesis, the plasmonic excitations and their coupling with the structural parameters, as well as the role of the embedding medium on the Au atomic wires, self-organized on flat and high-indexed Si surfaces were investigated. The atomic wire systems in the focus of this thesis, Si(111)-(5×2)-Au and Si(hhk)-(1×2)-Au, were generated by adsorption of submonolayers of gold onto the reconstructed surfaces. These systems feature a broad range of characteristics that can exemplarily be classified based on the number of atomic chains per terrace, inter-wire spacing, local structure of step edges, number of metallic bands and band filling. High-resolution EELS-LEED and SPA-LEED were used as the main experimental methods to address the mentioned properties and furthers. These experimental results were compared with the atomistic DFT calculations. Moreover, for the Si(553)-Au system, IR transmittance experiments were performed to investigate the optically active standing wave formation after oxidation. As a prominent property of conductive electrons, collective excitation is strongly coupled to the crystal lattice, electronic band structure, electronic and spatial confinement as well as properties of the surrounding physical media. This makes plasmonic excitation an adequate tool to probe a variety of interactions and coupling between those parameters associated with metallic structures. Taking this advantage, the present thesis investigates plasmonic excitations and their coupling to structural and environmental parameters. As a result of this investigation, a strong cross-coupling of the electronic and structural properties was revealed. For example, electronic doping to the Si(553)-Au system enhances order along the wires, which also results in band gap opening at the same time. Moreover, modification of individual structural motifs on the Si(557)-Au surface leads to a unique rearrangement of the band structure while preserving the metallicity. Also, combining the plasmon dispersion with calculated band structures, the kinetic sequence of the oxidation of the different atomic groups could be studied. For most investigated systems, an almost quantitative agreement between atomistic calculations and plasmon spectroscopy results was achieved, validating the calculated band structure and model used. In particular, the unoccupied part of the band structure was investigated for atomic wire systems. As an example, for the very first time unoccupied electronic band structure of the Si(111)-(5×2)-Au surface was investigated by comparing plasmon dispersion with the available DFT calculated bands. Moreover, doping of the latter surface with surplus Au and atomic H resulted in a metal-insulator transition. However, due to their highly robust anisotropic structure and electronic properties, the doping and oxidation of Si(hhk)-Au systems underline more specific mechanisms in the fine-tuning of metallicity. Some of these particular mechanisms include switching of bands, electronic interaction of adjacent terraces, cross-talking of dimerization and band gap opening, self-healing of defects, robust metallicity due to the site-specific oxidation, and indirect charge transfer to the metallic states, etc. have been extensively studied in this thesis.Metallische atomare Drähte auf Halbleiteroberflächen stellen die physikalische die Grenze für langreichweitige geordnete quasi-eindimensionale elektronische Systeme dar. In dieser Arbeit wurden sowohl plasmonische Anregungen und deren Kopplung mit strukturellen Parametern, als auch die Rolle des Trägermaterials auf atomare Golddrähte untersucht, die durch Selbstorganisation auf flachen und gestuften Silizium-Flächen hergestellt wurden. Schwerpunkt der vorliegenden Arbeit sind die Systeme Si(111)-(5×2)-Au und Si(hhk)-(1×2)-Au, die durch die Adsorption von Submonolagen Gold auf rekonstruierte Siliziumoberflächen hergestellt wurden. Diese Systeme zeigen eine Reihe von Charakteristika, die anhand der Anzahl an atomaren Ketten pro Terrasse, dem Abstand der Ketten, der lokalen Struktur der Stufenkanten und der Anzahl metallischer Bänder klassifiziert werden können. Hochauflösendes EELS-LEED und SPA-LEED wurden als experimentelle Hauptmethoden zur Analyse der genannten Eigenschaften verwendet. Die experimentellen Ergebnisse wurden mit atomistischen DFT-Rechnungen verglichen und diskutiert. Weiterhin, wurden für das Si(553)-Au-system IR-Transmissionsexperimente durchgeführt, um die optisch stehenden Welle nach der Oxidation zu untersuchen. Als markante Eigenschaft metallischer Ladungsträger ist deren kollektive Anregung stark verknüpft mit dem Kristallgitter, der elektronischen Bandstruktur, der räumlichen Einengung sowie mit den Eigenschaften des umgebenden Materials. Dies macht plasmonische Anregung zu einem adäquaten Werkzeug um die vielen Wechselwirkungen und Kopplungen, die mit den metallischen Strukturen verbunden sind, zu untersuchen. Basierend auf diesem Ansatz, analysiert die vorliegende Arbeit die plasmonischen Anregungen und ihre Kopplung zu strukturellen und Umgebungsparametern. Als ein Ergebnis dieser Untersuchungen, konnte eine starke Kopplung zwischen den elektronischen und strukturellen Parametern aufgezeigt werden. Beispielweise verbessert elektronische Dotierung des Si(553)-Au-Systems die Ordnung in den Ketten, bei gleichzeitiger Öffnung einer Bandlücke. Weitere Modifikationen von strukturellen Gegebenheiten in dem System führen zu einer einzigartigen Neuordnung der Bandstruktur bei Aufrechterhaltung der metallischen Eigenschaften. Des Weiteren konnte durch eine Kombination der Plasmonendispersion und der Bandstruktur die kinetischen Sequenz des Oxidationsprozesses verschiedener atomarer Gruppen untersucht werden. Für einen Großteil der untersuchten Systeme, konnte eine nahezu quantitative Übereinstimmung zwischen den atomaren Berechnungen und den Ergebnissen der Plasmonenspektroskopie erzielt werden, wodurch sowohl die berechnete Bandstruktur als auch das verwendete Modell verifiziert wurden. Im Speziellen konnte erstmalig der unbesetzte Teil der Bandstuktur atomarer Kettensysteme untersucht werden, beispielweise die unbesetzte Bandstruktur von Si(111)-(5×2)-Au, die durch den Vergleich der Plasmonendispersion mit den durch DFT Rechnungen ermittelten Bändern untersucht wurde. Eine Dotierung der genannten Oberfläche mit überschüssigen Gold- oder Wasserstoffatomen führt zu einem Metall-Isolator-Übergang. Durch die Robustheit der anisotropen Struktur und der elektronischen Eigenschaften, stellt die Dotierung und Oxidation von Si(hhk)-Gold Systemen spezifische Mechanismen für die Feinabstimmung der metallischen Eigenschaften heraus. Einige dieser Effekte, wie das Abschalten von Bändern, elektronische Wechselwirkung zwischen benachbarten Terrassen, die gegenseitige Beeinflussung von Dimerisation und der Öffnung einer Bandlücke, Selbstheilung von Defekten, robuste metallische Charakteristika durch die positionsspezifische Oxidation, der indirekte Ladungsübertrag auf die metallischen Zustände, etc. wurden in dieser Arbeit detailliert untersucht

Building a Contemplative Research Writing Course: Theoretical Considerations, Practical Components, Challenges, and Adaptability

Responding to the call for the contemplative teaching of writing initiated by O’Reilley (1993) and extended by Kirsch (2008; 2009), Kroll (2013), Kroll (2008), Wenger (2015), and Harrison (2012), among others, this article explores the theoretical considerations, practical components, challenges, and adaptability involved in teaching a contemplative research writing course. This article takes up the theoretical considerations of teaching a contemplative research writing course by examining the growing need for contemplative writing as a practice of mindfulness in an increasingly de-selfed academic culture (Hurlbert, 2012). Relatedly, this article examines the challenges involved when a pedagogy makes attendant assumptions about students, knowledge creation, the role of mindfulness in higher education, and the holistic decentering of the classroom space. Concerning the practical components of a contemplative research writing course, this article describes the central roles of contemplative silence (Kirsch, 2009) and freewriting, sustained inquiry writing projects, stable writing groups, and cycles of revision and reflection. Following this, this article takes up the challenges often engendered by the deployment of contemplative pedagogies in the context of higher education. Finally, this article describes the use of this course as a model for fostering writers’ engagement with their own disciplinary knowledge that is adaptable for sustained writing courses across the disciplines

Unapparent information revelation for counterterrorism: Visualizing associations using a hybrid graph-based approach

Unapparent Information Revelation refers to the task in the text mining of a document collection of revealing interesting information other than that which is explicitly stated. It focuses on detecting possible links between concepts across multiple text documents by generating a graph that matches the evidence trail found in the documents. A Concept Chain Graph is a statistical technique to find links in snippets of information where singularly each small piece appears to be unconnected.In relation to algorithm performance, Latent Semantic Indexing and the Contextual Network Graph are found to be comparable to the Concept Chain Graph.These aspects are explored and discussed.In this paper,a review is performed on these three similarly grounded approaches. The Concept Chain Graph is proposed as being suited to extracting interesting relations among concepts that co-occur within text collections due to its prominent ability to construct a directed graph, representing the evidence trail. It is the baseline study for our hybrid Concept Chain Graph approac

Regenstrief Center for Healthcare Engineering Spring 2009 Conference Report

Following the successful spring 2009 conference, National Priorities and Goals, the Regenstrief Center for Healthcare Engineering released a brief summary document with speaker highlights and opportunities for future progress. The conference was based on the November 2008 report from the National Priorities Partnership (NPP), which brought together 28 national healthcare organizations to develop a handful of priority areas for research and improvement. Conference speakers addressed the six areas from the report -- patient and family engagement, population health, safety, care coordination, overuse, palliative and end-of-life care -- identifying areas that posed the greatest challenges and areas with the greatest potential for change. Building on this conference, RCHE\u27s fall conference will delve into greater detail about population health and care coordination. Visit the link below for conference information and registration

A High Speed Particle Phase Discriminator (PPD-HS) for the classification of airborne particles, as tested in a continuous flow diffusion chamber

© Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License.A new instrument, the High-speed Particle Phase Discriminator (PPD-HS), developed at the University of Hertfordshire, for sizing individual cloud hydrometeors and determining their phase is described herein. PPD-HS performs an in situ analysis of the spatial intensity distribution of near-forward scattered light for individual hydrometeors yielding shape properties. Discrimination of spherical and aspherical particles is based on an analysis of the symmetry of the recorded scattering patterns. Scattering patterns are collected onto two linear detector arrays, reducing the complete 2-D scattering pattern to scattered light intensities captured onto two linear, one-dimensional strips of light sensitive pixels. Using this reduced scattering information, we calculate symmetry indicators that are used for particle shape and ultimately phase analysis. This reduction of information allows for detection rates of a few hundred particles per second. Here, we present a comprehensive analysis of instrument performance using both spherical and aspherical particles generated in a well-controlled laboratory setting using a vibrating orifice aerosol generator (VOAG) and covering a size range of approximately 3-32 μm. We use supervised machine learning to train a random forest model on the VOAG data sets that can be used to classify any particles detected by PPD-HS. Classification results show that the PPD-HS can successfully discriminate between spherical and aspherical particles, with misclassification below 5% for diameters >3μm. This phase discrimination method is subsequently applied to classify simulated cloud particles produced in a continuous flow diffusion chamber setup. We report observations of small, near-spherical ice crystals at early stages of the ice nucleation experiments, where shape analysis fails to correctly determine the particle phase. Nevertheless, in the case of simultaneous presence of cloud droplets and ice crystals, the introduced particle shape indicators allow for a clear distinction between these two classes, independent of optical particle size. From our laboratory experiments we conclude that PPD-HS constitutes a powerful new instrument to size and discriminate the phase of cloud hydrometeors. The working principle of PPD-HS forms a basis for future instruments to study microphysical properties of atmospheric mixed-phase clouds that represent a major source of uncertainty in aerosol-indirect effect for future climate projections..Peer reviewe

High strength lightweight aggregate concrete using blended coarse lightweight aggregate origin from palm oil industry

The benefits of using structural lightweight concrete in construction industry, particularly in high rise buildings, over normal weight concrete are numerous. The main method of producing structural lightweight concrete is the use of lightweight aggregates instead of ordinary aggregates in concrete. Due to the limited resources for natural and artificial lightweight aggregates, the alternative sources for lightweight aggregates should be discovered from industrial wastes. Oil palm shell (OPS) and oil-palm-boiler clinker (OPBC) are two solid wastes from palm oil industry and are available in abundance in tropical regimes. The use of just OPS as coarse lightweight aggregate in concrete mixture has some drawbacks for concrete. The aim of this study was to investigate engineering properties of a lightweight concrete containing both of these aggregates. For this purpose, in this study, 50% (by volume) of OPS was replaced with OPBC in an OPS lightweight concrete. The test results showed that when OPS was substituted with OPBC, significant improvement was observed in the compressive, splitting tensile and flexural strengths. In addition, initial and final water absorption as well as drying shrinkage strain of blended coarse lightweight aggregate concrete were significantly less than OPS concrete

Political Instability and Lessons for Pakistan: Case Study of 2014 PTI Sit in/Protests

Abstract. It’s a short allegory to present the case for the importance of Political stability in the economic progress of a country. The Arab spring protests were seen as strengthening democracy in the Arab world. Notwithstanding the surprise Arab spring brought in shape of further destabilizing Middle East, a similar environment of unrest and protests in a practicing democracy like Pakistan capture same dynamics of uncertainty that dampen economic destabilization. The paper briefly covers PTI’s sit in protests in year 2014 to make a case for how political instability stifled economic progress in Pakistan though momentarily.Keywords. Political economy, Pakistan economy.JEL. D72, F59, P16