En la presente Tesis Doctoral la técnica de ablación laser acoplada a ICP-OES/MS ha sido empleada para analizar muestras sólidas, como catalizadores usados en el refinado del petróleo y polímeros. Se han llevado a cabo dos tipos de análisis, un análisis global de las muestras que proporciona información general y un análisis localizado que permite obtener información acerca de la distribución espacial de los elementos de interés en las muestras. Las diferentes variables de la técnica ablación láser son estudiadas con el fin de seleccionar aquellas que conducen una señal alta y estable, así como a un menor grado de fraccionamiento. Este estudio se realiza para cada tipo de muestra, ya que los resultados dependen de la matriz estudiada. Además, en esta Tesis doctoral se desarrolla un método de calibración para llevar a cabo un análisis cuantitativo de las muestras sólidas, basado en la deposición de patrones líquidos sobre la muestra sólida. Este método es conocido como “dried droplet calibration approach” (DDCA), y permite cuantificar elementos presentes en muestras sólidas sin necesidad de usar materiales de referencia sólidos. Este nuevo método de calibración compensa el fraccionamiento elemental y los efectos de matriz, proporcionando resultados exactos y preciosos para muestras complejas tales como vidrios, catalizadores y polímeros.

The thesis summarizes the current state of research of thermonuclear fusion with magnetic confinement and decribes the possible role of stochastization of magnetic field lines and magnetic perturbations in solving some of the problems that are encountered on the road to the exploitation of fusion. It presents a theoretical introduction to deterministic chaos and explains the connection of this theory to magnetic perturbations in tokamak. The results are presented mainly in the form of publications in journals and conference proceedings. Among them are: the comparison of chaotic diffusion of particles and field lines, where significant differences were found; the application of chaotic diffusion of particles to the problem of runaway electrons originating in disruptions, where our simulations contributed to explaining the experimental results from the JET tokamak; the calculation of spectra of perturbations for the COMPASS tokamak, done as a preparation for the upcoming experiments; and modelling of screening of perturbations by plasma, where the observations of divertor footprints show as a promising method to detect the screening.

Falls are the leading cause of injuries among older adults (>65) and frequently result in reduced mobility, loss of independence, decreased quality of life, injury, and death.  Extensive research has been conducted regarding postural coordination and control, and other mechanisms/processes involved in maintaining postural stability.  However, there is relatively limited knowledge regarding the patterns of joint coordination, the underlying postural controller, and efficient methods to assess passive and active musculoskeletal properties relevant to balance.  In the current work, three new methods were developed to address these limitations and also to better understand the effects of localized ankle muscle fatigue, gender, and aging on postural coordination and control. First, two methods were used to evaluate postural coordination.  A wavelet coherence approach was developed and applied to assess the level and pattern of coordination between pairs of joints (i.e., ankle-knee, ankle-trunk, and ankle-head).  In addition, the uncontrolled manifold method was implemented for evaluation of potential whole-body coordination control goals.  Clear patterns of intermittent wavelet coherence were evident, indicating that joint coordination is intermittently executed.  Both in-phase and anti-phase coherence were detected over frequencies of 2.5 -- 4.0 Hz.  Shoulder and head kinematics appeared more likely than the whole-body center of mass as control goals for whole body coordination.  Both aging and ankle muscle fatigue led to a reduction of joint coordination. Second, an intermittent sliding mode controller was developed to model quiet upright stance.  In contrast to most previous postural controllers, which assume continuous control, an intermittent controller was considered more consistent with recent evidence on muscle activity and the results of the first study on postural coordination.  The sliding mode controller was able to accurately track kinematics and kinetics, and generated passive and active ankle torques comparable with previous results.  Ankle fatigue led to an increase in active ankle torque especially among young adults and males. Third, a new method was developed to estimate passive and active mechanical properties at the ankle (e.g., stiffness and damping).  This method was inspired from intermittent control theory, and the earlier results noted.  As opposed to conventional methods, this new method is computationally efficient and does not require external mechanical or sensory perturbations.  The method yielded a ratio of passive to active ankle torques consistent with earlier evidence, and larger passive and active ankle torques among males and older adults.  A post-fatigue increase of active ankle torque was estimated, especially among males and young adults. In addition to providing new analytical methods, the noted studies suggest that older adults have decreased joint coordination and increased ankle stiffness.  As a practical implication of this, fall prevention training programs may benefit from seeking to develop appropriate joint coordination strategies and ankle stiffness magnitudes.  To expand on the current work, future research should consider measuring muscle contraction characteristics at multiple joints and in different postures or activities. / Ph. D.

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Localized surface plasmon resonance (LSPR) is induced in metal nanoparticles by resonance between incident photons and conduction electrons in nanoparticles. For noble metal nanoparticles, LSPR can lead to strong absorbance of ultraviolet-violet light. Although it is well known that LSPR depends on the size and shape of nanoparticles, the inter-particle spacing, the dielectric properties of metal and the surrounding medium, the temperature dependence of LSPR is not well understood. By thermally annealing gold nanoparticle arrays formed by nanosphere lithography, a shift of LSPR peak upon heating has been shown. The thermal characteristics of the plasmonic nanoparticles have been further used to detect chemicals such as explosive and mercury vapors, which allow direct visual observation of the presence of mercury vapor, as well as thermal desorption measurements

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京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19481号 / 理博第4141号 / 新制||理||1595(附属図書館) / 32517 / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)准教授 藤 定義, 教授 佐々 真一, 教授 早川 尚男 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM