京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22459号 / 工博第4720号 / 新制||工||1737(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 作花 哲夫, 教授 安部 武志, 教授 阿部 竜 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / 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22798号 / エネ博第412号 / 新制||エネ||79(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応用科学専攻 / (主査)教授 平藤 哲司, 教授 土井 俊哉, 教授 馬渕 守 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

Hierarchical systems that integrate nano- and macroscale structural elements can offer enhanced stability over traditional immobilization methods. Microparticles were synthesized using interfacial assembly of lipase with (CLMP-N) and without (CLMP) nanoparticles into a crosslinked polymeric core, to determine the impact of the highly ordered system on lipase stability in extreme environments. Kinetic analysis revealed the macrostructure significantly increases the turnover rate (kcat) following immobilization. The macrostructure also stabilized lipase at neutral and basic pH values, while the nanoparticles influenced stability under acidic pH conditions. A greener solvent, choline chloride and urea, was applied to produce sugar ester surfactants. Microparticles exhibited decreases in the turnover rate (kcat) and catalytic efficiency (kcat/Km) following exposure, but retained over 60% and 20% activity after exposure at 50 ºC and 60 ºC, respectively. CLMP and CLMP-N outperformed the commercially available lipase per unit protein in the production of sugar esters. The utilization of greener solvent systems with hierarchical immobilized enzyme systems has the potential to improve processing efficiency and sustainability for the production of value-added agricultural products.

Content: Nowadays, tannery pollution is of great concern worldwide. The unhairing and fiber bundle-opening processes contribute the majority of the pollution by the use of sodium sulfide and calcium hydroxide, which were proposed to be replaced by neutral protease combined with (potassium chloride) KCl, (lithium bromide)LiBr/1-allyl-3-methylimidazolium chloride([AMIm]Cl) in the present work. Proper amount of KCl can speed up the unhairing with the grain not destroyed by the neutral protease. Four methods for unhairing and fiber bundle-opening were used as follows: 1. Two steps in different floats as KCl/neutral protease unhairing, followed by LiBr/[AMIm]Cl for fiber bundle-opening; 2. Two steps in different floats as neutral protease unhairing, followed by LiBr/[AMIm]Cl for fiber bundle-opening; 3. One step in the same float as neutral protease for unhairing firstly and then LiBr/[AMIm]Cl for fiber bundle-opening. 4. One step in the same float as neutral protease/KCl for unhairing firstly and then LiBr/[AMIm]Cl for fiber bundle-opening. It was found that using neutral protease/KCl solution for unhairing and LiBr/[AMIm]Cl solution for fiber bundle-opening is the best in fiber bundle-opening at the liming process. Besides, all the methods used here are better than the traditional liming processes (C) from viewpoints of unhairing and fiber bundleopening. Take-Away: 1. The addition of potassium chloride can improve the stability of neutral protease solution. 2. The catalytic efficiency of the enzyme was improved because of adding potassium chloride can enhance the contact rate of neutral protease with substrate. 3. Ionic liquids have less hydrolysis of collagen and larger dissolution of polysaccharides.

The master's thesis deals with experimental study of tribological characteristics of smart fluids. Smart fluids are substances in liquid state reacting to the presence of magnetic or electric field by change in rheological properties. For possible application in devices using conventional lubricants is necessary to choose suitable smart fluid and study the influence of excitation on formation of lubricating layer, friction and wear. Comprehensive description of excitation influence is executed using three experimental devices and theoretical model for measurements parameters specification. Assessed are lubricant film thickness, friction coefficient and wear under smart fluid activation in non-conformal contact. Results show significant observable influence of smart fluids excitation on all assessed aspects. Understanding the mechanisms of smart fluids excitation can be a key step in development of intelligent devices with active external control of lubricant behaviour and character, that could lead to maintenance cost reduction and effectivity improvement.

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第22795号 / エネ博第409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 萩原 理加, 教授 佐川 尚, 教授 野平 俊之 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第22860号 / エネ博第413号 / 新制||エネ||79(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 萩原 理加, 教授 佐川 尚, 教授 野平 俊之 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

La chimie se doit de développer de nouveaux axes de recherche à la fois respectueux de la nature et s’inscrivant dans une démarche globale éco-compatible. Dans ce contexte, l’utilisation des polymères naturels, notamment les polysaccharides, permet de synthétiser des matériaux innovants des applications dans de nombreux secteurs industriels. L’objectif de ce travail est de valoriser les polysaccharides marins tels que le chitosane et le κ-carraghénane à travers l’exploration de deux axes de recherches. Le premier axe est consacré à l’amélioration des propriétés mécaniques, électriques et de sorption de biopolymères par l’incorporation de graphène. Un protocole original a permis de disperser très efficacement du graphène au sein du chitosane pour la conception de films et d’aérogels nanocomposites. L’analyse des films a mis en évidence une amélioration simultanée de la rigidité, de la résistance, et de l’élongation à rupture, pour de faibles teneurs en graphène. Le seuil de percolation permettant l’obtention d’une conductivité électrique n’a pas été atteint aux faibles taux de charges utilisés. L’étude des aérogels chitosane/graphène a, quant à elle, révélé que l’incorporation de graphène aux aérogels de chitosane permettait d’augmenter leur capacité d’adsorption de colorants.Le deuxième axe concerne l’introduction d’hétéroatomes dans la structure carbonée du graphène. Pour obtenir du graphène dopé en azote et en soufre, des aérogels de polysaccharides marins ont été synthétisés, puis pyrolysés dans des conditions contrôlées. Les aérogels carbonés obtenus sont ensuite exfoliés dans l’eau par l’utilisation d’ultrasons. Les groupements amine du chitosane ont permis d’obtenir avec un haut rendement un graphène dopé avec un taux de 5 % d’azote. De plus, il a été possible de moduler de 5 % à 11 %ce taux d’azote par l’emploi de liquide ionique tel que le [EMIm][dca]. De façon similaire, les groupements sulfate du κ-carraghénane ont permis de doper du graphène en soufre avec un taux d’atomes de soufre de 1,5 %. / The chemistry have to develop new research axis both respectful of the nature and joining an eco-compatible global approach. In this context, use natural polysaccharides allow to synthesize innovative materials for applications in many industries fields. The aim of this work is add value to the marine polysaccharide such as chitosan and κ-carrageenan through two research axis.The first axis is consecrated to increase the mechanical, electrical and color sorption properties by introduce graphene filler in biopolymer matrice. An easy and original protocol allowed scattering very effectively graphene in chitosan to design films and aerogels nanocomposites. The analyse of nanocomposite films show an improvement of stiffness, tensile strength and elongation break at the same time with low content of graphene. However, the percolation threshold was not reach to bring electrics properties in films. The study of chitosan/graphene aerogel reveals that graphene allows an increase of color agent adsorbing power such as eosin Y compared with aerogels chitosan.The second axis concerns the introduction of heteroatom in graphene carbon structure. To obtain nitrogen-doped graphene and sulphur-doped graphene, it requires the synthesis of marine polysaccharide aerogel, and their pyrolysis under controlled conditions. The carbon aerogels are exfoliated in water with sonification. Amine groups in chitosan allowed through this process a nitrogen-doped graphene with high yield and nitrogen rate of 5 %. Moreover, it was possible to modulate nitrogen rate with ionic liquid such as [EMIm][dca]. So the nitrogen atom rate increases from 5% to 11%. In similar way, sulfate group in κ-carrageenan gives sulphur-doped graphene with sulphur rate of 1,5%.

Ionic liquids are continuously finding more and more applications, both in research and in the industry. Many attempts have been made to find parameters that could be used to describe all ionic liquid systems. Five years ago a Japanese group applied the work of Gutmann on ionic liquids to use ionic association to describe solvation effects. The group calculated ionic association from conductivity and diffusion measurements. This report presents a direct approach through electrophoretic NMR to measure ionic association in ionic liquids.  The report contains a brief introduction to ionic liquids and their properties as well as a short explanation of Nuclear Magnetic Resonance (NMR) spectroscopy, diffusion NMR and a more detailed explanation of electrophoretic NMR (eNMR). Experimental setups, taken from previous work by the NMR group at Physical Chemistry KTH, have been modified to allow for measurements in ionic liquid systems. The report discusses the issues that can arise when measuring eNMR in ionic liquids and suggests solutions. The method developed is principally built upon experiments on 1-butyl-3-methyl-imidazolium trifluoroacetate and is directly applicable to other ionic liquid systems. For more viscous systems than the one investigated here, slight changes will need to be made, as explained in the report.  In order to evaluate the method developed during the project the degree of association for 1-butyl-3-methyl-imidazolium trifluoroacetate has been calculated from experimental results and results in similar values as reported by Tokuda et al.. Furthermore, the temperature variation due to Joule heating during a complete eNMR experiment was also investigated by observing change in chemical shift.

Electrochemical quartz crystal microbalance has been employed to investigate electro-responsiveness of an ionic liquid as an additive in lubricant oils on a gold surface. Polarisation of the surface reveals changes in frequency where an increase in magnitude amplified the observed response, corresponding to a controllable alternation of the ionic liquid configuration on the surface as a function of applied potential. The frequency changes are due to different packing of the anion and cation, respectively, on the surface as their mass densities and geometries are different. Relaxation of the system was reversible to the application of a potential and it was also found to be diffusion dependent, where the ratio between the ion diffusivities could be extracted from the results. Measurement of the system relaxation reveals a potential decay of that of a discharging capacitor, with an internal resistance inducing an initial potential drop due to the resistivity of the oil medium. The discharge behaviour was also proven to show high internal reproducibility validity within experiments. This newly discovered insight in responsive differences of ion packing is of importance, not only for ionic liquid additives in tribology, but for understanding and exploiting ionic liquids in an array of electrochemical applications.