京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第21443号 / 理博第4436号 / 新制||理||1637(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 北川 宏, 教授 竹腰 清乃理, 教授 吉村 一良 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

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Syftet med studien var att utforska tränares syn på och attityder till doping och antidopingarbete inom ungdomsidrott. De specificerade frågeställningarna var: hur uppfattar tränare föreningens roll inom antidopingarbete? hur ser tränarna på sin roll som förmedlare av normer, kroppsnormer, prestation och doping? hur anser tränare att de kan påverka och utveckla antidopingarbetet inom ungdomsidrott? Den metod som valdes var kvalitativa semistrukturerade intervjuer där sex tränare från olika ungdomslag medverkade. Intervjuerna genomfördes via zoom/teams och live. Analysverktyget som användes var tematisk innehållsanalys och via de verktyget framkom 78 koder som blev till fem teman. Resultatet av studien visade på att tränarna hade dålig kännedom om doping dock var det tydligt att doping inte var acceptabelt. Det saknas ett aktivt antidopingarbete i majoriteten av föreningarna och mycket var kopplat till tidsbrist och inställningen att doping inte förekommer inom deras sport. Tränarna påstod sig själva vara viktiga för ungdomarna och deras sätt att agera och uttrycka sig kan ha en bidragande effekt i hur ungdomarna formas. Slutsatsen av studien var att tränare saknar kunskap inom doping och föreningens antidopingarbete är väldigt vagt. Det finns förbättringsmöjligheter i utbildningar kopplat till doping. Då många tränare under sin utbildning inte blivit informerade om doping skulle möjligtvis en större del läggas till i tränarutbildningen som belyser antidoping. Tränarna har en betydande roll i sina attityder och värderingar kopplat till doping och kroppsnormer, att fortsätta prata med ungdomar om sunda värderingar till kroppen kan vara en viktig bidragande faktor för att undvika framtida dopningsproblematik.

Samhällsutvecklingen medför förändringar i hur människor lever sina liv. Traditioner och normer bryts ner och ifrågasätts i allt snabbare takt idag än tidigare. Den kulturella moderniseringen påverkar alla, i synnerhet ungdomar som befinner sig i en känslig livsfas där de söker sin identitet. Utseendet och kroppen har fått en central roll idag, vilket inte enbart leder till en sundare livsstil utan även till en oroande kroppsfixering. Just kroppsfixeringen tillsammans med svag självkänsla ligger många gånger bakom dopingmissbruk, ett missbruk som ökat bland ungdomar på sistone. Syftet med min undersökning är att visa hur idrottslärare på grundskolans senare år ser på dagens dopingsituation och behovet av dopinginformation i skolan, samt huruvida de förändrar denna information med hänsyn till aktuella samhällstendenser. Undersökningen grundade sig på fem intervjuer med olika idrottslärare på olika grundskolor. Det visade sig bl.a. att trots en klar insikt i dagens allvarliga dopingsituation hos samtliga idrottslärare var det endast två som berörde doping i undervisningen. Vidare hade ingen av dem förändrat sin information eller sättet att se på dopingundervisning över tiden. Mot bakgrund av det ifrågasätter jag skolans arbete med dopinginformation.

Rare earth oxides with trivalent lattice dopants have been of great interest to researchers in the recent years due to its potential applications in catalysis and high temperature protective coatings. The ability to store oxygen in rare earths is the basis for catalysis because of the ability to change valence states which causes the presence of intrinsic oxygen vacancies in the crystal lattice. Although, several doped-rare earth oxide systems in micron scale have been investigated, the doping effect in cerium oxide nanoparticles with well characterized particle size has not been studied. The doping of ceria at that small size can be very beneficial to further improve its catalytic properties and alter the high temperature phases in alloy systems. Cost effective room temperature chemical methods are used in the current work to synthesize uniformly distributed undoped and doped (dopants: La, Nd, Sm, Gd, Y and Yb) rare earth oxide nanoparticles. In the present study, the variation of the properties in nanocrystalline ceria (NC) synthesized by microemulsion method is studied as a function of dopant size and its concentration. To further understand, the role of dopant (cation) size on the oxygen vacancy concentration, doped nanocrystalline oxide powders were analyzed by Raman Spectroscopy, X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS). XRD studies showed that lattice parameter change in nanocrystalline oxide by doping trivalent rare earth elements is largely depending on size of trivalent ions. It showed that by doping larger cations (Gd3+ and Y3+) compare to Ce3+ causes lattice expansion where as smaller cations (Yb3+) leads to lattice contraction. It also showed that the lattice expansion or contraction is directly proportional to dopant concentration. The results of Raman Spectroscopy showed that the correlation length decreases resulting in increase in oxygen vacancies for larger trivalent dopants (Sm3+, Gd3+ and Y3+). However, the correlation length increases resulting in decrease in oxygen vacancies for smaller trivalent dopants (Yb3+) compare to nanocrystalline ceria. These nanostructured oxides are further applied to develop high temperature oxidation resistance coatings for austenitic steels. The present study investigates the role of oxygen vacancies in the performance of high temperature oxidation resistance as a function of various trivalent dopants and dopant concentration. NC and La3+ doped nanocrystalline ceria (LDN) particles were coated on AISI 304 stainless steels (SS) and exposed to 1243K in dry air for longer duration and subjected to cycling. The results are further compared with that of micro-ceria (MC) coatings. The coated samples showed 90% improvement in oxidation resistance compared to uncoated and MC coated steels as seen from the SEM cross-sectional studies. XRD analysis showed the presence of chromia in both NC and 20 LDN samples which is absent in uncoated steels. From SIMS depth profiles, Fe, Ni depletion zones are observed in presence of LDN coated sample indicating diffusion through the oxide layer. The role of oxygen vacancies in the nanoceria coatings on the early formation of protective chromia layer is discussed and compared to its micron counterpart. This study helps in understanding the role of oxygen vacancies to protect austenitic stainless steel at high temperature and confirms the oxygen inward diffusion rather cation outward diffusion in rare earth oxide coatings. It also gives an idea to identify the type of dopant and its concentration in nanocrystalline cerium oxide which supplies the critical oxygen partial pressure required at high temperature to form primarily impervious chromia layer.

<p> Research in the field of sol-gel derived materials has evolved dramatically over the past forty years. The developments in the past decade, in the field of bioanalytical chemistry, have revolutionized this field. Early research, as well as that done by our group, has confirmed that the commonly used alkoxysilane precursors (tetraethylorthosilicate - TEOS or tetramethylorthosilicate - TMOS) are not ideal for entrapment of biomolecules. They produce materials that are brittle, often undergo cracking due to hydration stresses and in some cases, can block the accessibility of the analyte to the entrapped biomolecules. My research project therefore focuses on the development of new sol-gel processing methods through the use of an additive-glycerol, which will produce new "second generation" glasses. I have focused on obtaining a basic understanding of glycerol-doped sol-gel derived materials and the effect they have on the entrapped biomolecules. Glycerol-doped sol-gel materials display larger pore size, decreased shrinkage and cracking as compared to the TEOS-based materials. Biocatalysts entrapped in glycerol-doped materials showed significantly smaller decreases in activity over a period of one month relative to enzyme entrapped in TEOS. Also, to gain further insight into the effects of glycerol doping on the properties of entrapped proteins, both steady-state and time-resolved fluorescence of Trp 214 was used to examine the conformation, dynamics, accessibility, thermal/chemical stability and the degree of ligand binding of human serum albumin (HSA) in solution and after entrapment of the protein in glycerol-doped TEOS-based materials.</p> / Thesis / Master of Science (MSc)

<p> A number of microwave measuring techniques for the measurement of the complex permittivity (^ɛ = ɛo ɛr - j σ/ω) have been investigated and a new method based on the replacement of the narrow wall of a rectangular wave-guide by a block of semi-conductor has been developed. This technique is shown to be suitable for the measurement of σ when σ >> ωɛo ɛr and for the measurement of σ and ɛr for σ ≃ ωɛo ɛr. </p> <p> An investigation has been made of the propagation characteristics of a rectangular wave-guide containing a centrally placed slab of semi-conductor parallel to the narrow walls of the guide. A comparison of exact solutions for the propagation constant in such a structure with the approximate solutions normally used has shown that the conditions for the validity of the approximate solutions are much more stringent than has been reported previously. It is further shown that under certain conditions the structure offers a convenient method of measuring the conductivity of a semi-conductor. In addition, a theoretical and experimental investigation of the effects of the higher order modes excited at the interface of such a structure with an empty wave-guide has been made. The study has shown that under certain conditions, the effects of these modes can be significant.</p> <p> A theoretical and experimental study has also been made of the effects of temperature, frequency and doping on the complex permittivity of lightly doped n-type germanium. Measurements of these effects which have not been reported previously have been made over a temperature range 100°K - 500°K at frequencies 9.25 and 34.5 GHz and confirm the theoretical model used.</p> / Thesis / Doctor of Philosophy (PhD)

Ternary III-nitride alloys have enabled the design of various devices ranging from optoelectronics to power electronics due to their tunable band gap. BxGa1-xN is a wide band gap semiconductor with applications in detecting devices, power electronics and light-emitting diodes. The band gap can be modulated by changing the Boron concentration. It can be grown by metal-organic chemical vapor deposition as a mixed thin film of wurtzite and zincblende structures. In this work, we investigate the structural and electronic properties of BxGa1-xN (x<0.2) by first-principles calculations for both the wurtzite and zincblende phases. The formation energies of Si and Mg impurities and of a Ga vacancy are also calculated. We find that the wurtzite structure is favored over the zincblende structure. Furthermore, the Si and Mg impurities have relatively low formation energies in their neutral state, which indicates compatibility with BxGa1-xN, while a Ga vacancy has very high formation energy, hence being less likely to form spontaneously. Moreover, in the charged states, the formation energy of Mg is reasonably low for most values of the Fermi level, while the formation energy of Si depends linearly on the Fermi level, indicating challenges in achieving n-type conductivity. For a Ga vacancy in a triple acceptor state, the formation energy is reasonably low close to the conduction band, therefore, Ga vacancies interfere with n-type conductivity.

This dissertation focuses on an uncooled Mid-Wave Infra-Red (MWIR) detector was developed by doping an n-type 4H-SiC with Ga using the laser doping technique. 4H-SiC is one of the polytypes of crystalline silicon carbide, a wide bandgap semiconductor. The dopant creates an energy level of 0.30 eV, which was confirmed by optical spectroscopy of the doped sample. This energy level corresponds to the MWIR wavelength of 4.21 µm. The detection mechanism is based on the photoexcitation of electrons by the photons of this wavelength absorbed in the semiconductor. This process modifies the electron density, which changes the refraction index and, therefore, the reflectance of the semiconductor is also changed. The change in the reflectance, which is the optical response of the detector, can be measured remotely with a laser beam such as a He-Ne laser. This capability of measuring the detector response remotely makes it a wireless optical detector. The variation of refraction index was calculated as a function of absorbed irradiance based on the reflectance data for the as-received and doped samples. A distinct change was observed for the refraction index of the doped sample, indicating that the detector is suitable for applications at 4.21 µm wavelength. The Ga dopant energy level in the substrate was confirmed by optical absorption spectroscopy. Secondary ion mass spectroscopy (SIMS) of the doped samples revealed an enhancement in the solid solubility of Ga in the substrate when doping is carried out by increasing the number of laser scans. Higher dopant concentration increases the number of holes in the dopant energy level, enabling photoexcitation of more electrons from the valence band by the incident MWIR photons. The detector performance improves as the dopant concentration increases from 1.15×1019 to 6.25×1020 cm-3. The detectivity of the optical photodetector is found to be 1.07×1010 cm·Hz1/2/W for the case of doping with 4 laser passes. The noise mechanisms in the probe laser, silicon carbide MWIR detector and laser power meter affect the performance of the detector such as the responsivity, noise equivalent temperature difference (NETD) and detectivity. For the MWIR wavelength 4.21 and 4.63 µm, the experimental detectivity of the optical photodetector of this study is found to be 1.07×1010 cm·Hz1/2/W, while the theoretical value is 2.39×1010 cm·Hz1/2/W. The values of NETD are found to be 404.03 and 15.48 mK based on experimental data for an MWIR radiation source of temperature 25°C and theoretical calculation respectively. The doped SiC also has a capability of gas detection since gas emission spectra are in infrared range. Similarly, the sensor is based on the semiconductor optics principle, i.e., an energy gap is created in a semiconductor by doping it with an appropriate dopant to ensure that the energy gap matches with an emission spectral line of the gas of interest. Specifically four sensors have been fabricated by laser doping four quadrants of a 6H-SiC substrate with Ga, Al, Sc and P atoms to detect CO2, NO, CO and NO2 gases respectively. The photons, which are emitted by the gas, excite the electrons in the doped sample and consequently change the electron density in various energy states. This phenomenon affects the refraction index of the semiconductor and, therefore, the reflectivity of the semiconductor is altered by the gas. The optical response of this semiconductor sensor is the reflected power of a probe beam, which is a He-Ne laser beam in this study. The CO2, NO, CO and NO2 gases change the refraction indices of Ga-, Al-, Sc- and Al-doped 6H-SiC, respectively, more prominently than the other gases tested in this study. Hence these doped 6H-SiC samples can be used as CO2, NO, CO and NO2 gas sensors respectively.

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