The liquid-liquid phase separation (LLPS) of biomolecules is a phenomenon which received a lot of attention in the last years because it is not only related to theformation of membraneless organelles but also to neurodegenerative diseases. Lysozyme is a globular protein that undergoes LLPS in a buffer salt system andfor that it is well investigated with several techniques like microscopy, dynamic lightscattering (DLS) or small-angle X-ray scattering. In this work we investigate the effect of temperature, solvent and sample con-centration on the diffusion coefficient, the hydrodynamic radius and the viscosity oflysozyme using a DLS setup. Furthermore, the influence of these parameters on thecluster formation is addressed. Finally, we investigate the question if the LLPS oflysozyme in a buffer environment effects the formation of dynamic clusters.

No description available.

Three-dimensional nanocomposite networks consisting of percolated Si nanowires in a SiOx matrix, Si:SiO2, were studied. The structures were obtained by reactive ion beam sputter deposition of SiOx (x~0.6) thin films at 450 °C and subsequent crystallization using conventional oven as well as millisecond line focus laser annealing. Rutherford backscattering spectrometry, Raman spectroscopy, X-ray diffraction, cross-sectional and energy-filtered transmission electron microscopy were applied for sample characterization. While oven annealing resulted in a mean Si wire diameter of 10 nm and a crystallinity of 72 % within the Si volume, almost single-domain Si structures with 30 nm in diameter and almost free of amorphous Si were obtained by millisecond laser application. The structural differences are attributed to the different crystallization processes: Conventional oven tempering proceeds via solid state, millisecond laser application via liquid phase crystallization of Si. The 5 orders of magnitude larger diffusion constant in the liquid phase is responsible for the three times larger Si nanostructure diameter. In conclusion, laser annealing offers not only significantly shorter process times but moreover a superior structural order of nano-Si compared to conventional heating.

No description available.

The phase separation process of a rubber modified epoxy system during cure was analyzed by a model developed on the basis of a thermodynamic description of binary mixture and constitutive equations for nucleation and growth rates. As epoxy resins are cured, rubber molecules are precipitated from the epoxy matrix to a non-equilibrium composition due to the decrease in the configurational entropy and the increase in the viscosity with conversion. If phase separation takes place in a metastable region, this model can monitor the changes of rubber compositions in both phases as well as the changes in the number and size of rubber particles upon conversion of polymerization. The particle size distribution at the completion of phase separation was also calculated. The effect of cure temperature on the final morphologies of a rubber modified epoxy system was discussed. The computed particle size distributions for piperidine and diaminodiphenyl sulfone cured systems showed good agreements with experimentally measured values. Depending on the activation energy for viscous flow of the epoxy matrix relative to that for the polymerization, the particle size distribution may show bimodal or unimodal distribution. The size of rubber rich phase increases to a maximum and then decreases with an increase in cure temperature. However, due to limitations of temperature range to probe in an actual experiment, one may observe only either decreasing or increasing particle size as cure temperature increases. The number of rubber particles per unit volume increases for the DGEBA/DDS/ETBN system as cure temperature increases in the temperature range of 30 °C to 220 °C. Fracture toughness of cured DGEBA/DDS/ETBN system was analyzed in terms of morphologies generated by the temperature variation. Since the volume fraction of rubber particles did not change with cure temperature, the critical stress intensity factor did not vary significantly with cure temperature as expected. However, increases in cure temperature produced smaller but more numerous particles. The critical stress intensity factor normalized by the number density of particles exhibited dependence on the radius of particles to the third power. On the other hand, the critical stress intensity factor normalized by the radius of particles showed a linear dependence with respect to the number density of particles. / Ph. D.

In this thesis the deployment of a methodological combination of two single molecule techniques, the planar bilayer technique and fluorescence fluctuation spectroscopy, is presented. The newly devised electro-optical setup will serve as a sophisticated model system for electrical excitable biological membranes. The expectation on a combined electro-optical setup is to be able to correlate the function of membrane channels (electrical activity) with its structural properties (fluorescence assays). The thesis is grouped into four chapters: A general introduction, providing the biological and methodological background, is followed by two studies on the application of the electro- optical setup in the field of membrane biophysics. In the first study the electrical and diffusion properties of planar bilayer membranes made of simple and ternary lipid mixtures are characterized. Additionally, the influence of temperature dependent lipid phase separation on the electrical activity of the ion channel gramicidin A is studied. The second study addresses the conformational changes of the pore-forming toxin Colicin A during membrane binding and ion channel formation. Finally, the potentials and the limitation of the presented setup are discussed.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19007号 / 工博第4049号 / 新制||工||1623(附属図書館) / 31958 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 伊藤 紳三郎, 教授 赤木 和夫, 教授 辻井 敬亘 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19478号 / 理博第4138号 / 新制||理||1595(附属図書館) / 32514 / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)講師 市川 正敏, 教授 佐々 真一, 教授 山本 潤 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19519号 / 理博第4179号 / 新制||理||1600(附属図書館) / 32555 / 京都大学大学院理学研究科化学専攻 / (主査)准教授 中西 和樹, 教授 北川 宏, 教授 有賀 哲也 / 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(工学) / 甲第21273号 / 工博第4501号 / 新制||工||1700(附属図書館) / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 辻井 敬亘, 教授 山子 茂, 教授 秋吉 一成 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM