京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20353号 / 工博第4290号 / 新制||工||1664(附属図書館) / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 米田 稔, 教授 伊藤 禎彦, 准教授 松井 康人 / 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(工学) / 甲第20574号 / 工博第4354号 / 新制||工||1677(附属図書館) / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 今堀 博, 教授 秋吉 一成, 教授 白川 昌宏 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

I kommersiella litiumjonbatterier används ofta grafit i anodmaterialet, främst på grund av att det reversibelt kan placeras litiumjoner mellan dess lager. Grafit har dock en begränsad energitäthet och forskning bedrivs därför för att finna metoder som kan öka energitätheten hos anodmaterialet. Kisel, som har en betydigt högre energitäthet, kan interkalleras i grafiten för att öka energitätheten. För att undvika en förstörande volymexpansion som sker under litieringen när kisel tillämpas måste interkalleringen göras med kiselnanopartiklar. En skalbar metod för att framställa kiselnanopartiklar på nanografitflak har tagits fram och presenterats i en artikel av Phadatare et al. Syftet bakom det här arbetet har varit att lägga grund för en storskalig produktion av kiselbaserade anoder avsedda att användas i litiumjonbatterier för att ge dem en ökad kapacitet. Målet med arbetet var att genom laborativa undersökningar presentera hurvida metoden presenterad i artikeln är repeterbar samt hur olika parametrar påverkar resultatet inför en uppskalning. Resultaten bekräftade att metoden presenterad i artikeln är repeterbar och att den tillhörande ugnsprocessen bör utföras i en rörugn. Resultaten visade också att temperaturen för ugnsprocessen inte bör sänkas till så lågt som 600 °C, men att potential finns för att kunna sänka temperaturen från nuvarande 800 °C. Vid nuvarande temperatur bör andelen kisel inte ökas till ≥ 47 %, men bedöms ha potential att kunna ökas från nuvarande 33 %. Resultaten visade endast en liten bildning av kiselnanopartiklar då ett kiselpulver av annan kvalitet än det beskrivet i artikeln användes och visade på att valet av utgångsmaterialet är av stor vikt. Resultaten visade vidare att dispergeringsmedlet polyvinylakohol, PVA, inte kan uteslutas. Resultaten tydde på att det finns potential för att kunna minska andelen PVA, men att det inte bör reduceras till motsvarande en halverad koncerntration av vad som presenterats i artikeln. Resultaten visade också att processen måste utföras i en syrefattig miljö för att inte orsaka oxidaton av nanografiten. Däremot tydde resultaten på att mekanismen för bildningen av kiselnanopartiklar inte är syrekänslig och att mekanismen inte tycks vara beroende av att just PVA utgör den, om teorin stämmer, nödvändiga vätekällan. / In commercial lithium ion batteries graphite is often used in the anode material, mainly because it can reversibly contain lithium ions between the layers. However, graphite has a limited energy density and research is therefore being performed to find methods that will increase the energy density of the anode material. Silicon, which has a significantly higher energy density, can be intercalated in the graphite to increase the energy density. However, in order to avoid a destructive volume expansion that occurs during the lithiation, the intercalation must be performed with silicon nanoparticles. A scalable method for producing silicon nanoparticles on nanographite flakes has been developed and presented in an article by Phadatare et al. The purpose behind this work has been to lay the foundation for large-scale production of silicon- based anodes intended to be used in lithium-ion batteries to provide them with increased capacity. The aim of the work was to present whether the method is repeatable and how different parameters affect the results for an upscaling, which was done through laboratory investigations. The results confirmed that the method presented in the article is repeatable and that the process should be carried out using a tube furnace. The results also showed that the temperature of the oven process should not be lowered to 600 °C, but that there is potential to lower it from the current 800 °C. At the current temperature, the percentage of silicon should not be increased to ≥ 47 %, but is considered to have the potential to be increased from the current 33 %. Only a small proportion of silicon nanoparticles was formed when a silicon powder of a different quality than that described in the article was used and showed that the choice of the silicon starting material is of great importance. The results further revealed that the dispersant polyvinyl alcohol, PVA, cannot be excluded. The results showed that there is potential to reduce the proportion of PVA, but that it should not be reduced to as much as half the concentration that is presented in the article. The results showed that the process must be carried out in an oxygen-poor environment in order not to cause oxidation of the nanographite. However, the results also indicated that the mechanism for the formation of silicon nanoparticles is not oxygen sensitive and that the mechanism, if the existing theory is correct, does not appear to be dependent on PVA beeing the source of hydrogen.

Thesis advisor: Dunwei Wang / Metal organic frameworks (MOFs) are a class of compounds that show promising potential for a variety of applications due to their uniformity, highly porous structure, lack of dead volume, and fine-tunability. One of these significant applications is in selective ion transport, which makes MOF films a uniquely good separatory material for dual-electrolyte setups, such as those being investigated with Mg-Br batteries. This research has important environmental and industrial ramifications, considering the various drawbacks associated with commercially available batteries such as the lithium-ion battery. The MOF investigated was Mg-MOF-74, which showed promising selective Mg2+ transport abilities. Both Mg-MOF-74 powder and films were synthesized via a vapor-assisted conversion process to maximize efficiency. To characterize the MOF, XRD and SEM imaging was used. This allowed us to gain a nuanced understanding of the material and its properties for further applications. / Thesis (BA) — Boston College, 2022. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Departmental Honors. / Discipline: Chemistry.

No description available.

Accumulation of heavy metals in different environmental compartments and their toxicity even at trace level concentration necessitates the study of their efficient removal. Furthermore, metals could co-exist in the environment which is a complex scenario as there would be competition among the metals in terms of removal efficiency. This study presents the effective removal of trace level toxic metals (Hg2+, Cd2+, Pb2+) in both single and ternary metal solutions through adsorption on the successfully synthesized composite (SC) of pinewood-derived biochar (BC) and graphene oxide (GO) nanomaterials. Moreover, different linear regression tools (Gaussian Process (GP), Random Forest (RF), and Feed Forward Back Propagation (FFBP)) from the machine learning (ML) toolbox were used to make the comparison between actual and their predicted adsorption. The structural and morphological analysis of the SC showed that GO was successfully coated on the surface of the BC. GO coating increased the surface area, porosity, functional groups, and adsorption efficiency of these toxic metals on the SC as compared to the unmodified BC. The factors affecting adsorption efficiency were metal concentration, pH, and the ratio of BC and GO in the SC. The adsorption efficiency in single metal solution was found 94-98% for Hg2+, 92-94% for Cd2+, and 96-99% for Pb2+ and for ternary metal solutions 94-96% for Hg2+, 95-97% for Cd2+, and 97-99% for Pb2+ at pH 6 and SC with BC/GO (w/w) ratio as 1:10. However, for unmodified BC, the adsorption efficiency was less in both single and ternary solutions. Thus, results indicate that modification of BC with GO increases adsorption efficiency as compared to unmodified BC. Furthermore, for all three metals, Freundlich's adsorption isotherm was followed in both single and ternary solutions. Regeneration of the SC was also attained by adsorbate desorption, producing a competent and cost-effective adsorbent for the removal of toxic metals from our environment. Furthermore, from the ML toolbox mean squared error (MSE) values between the actual efficiency and predicted efficiency were calculated which was negligible in the case of GP, with regression coefficient (R2) equal to 1. This implied that GP was the most suitable linear regression model among other models (RF, FFBP) for the available data sets. These predicted values through different ML models could significantly reduce the experimental workload for various parameters in predicting the removal efficiency of the synthesized composite for the target toxic metals. Thus, these models help in reducing experimental time and predicting the most appropriate combination for the best result in the future.

Melanina é um polímero constituído por uma grande heterogeneidade de monômeros tendo como característica comum a presença de grupos indóis. Por outro lado, a eumelanina produzida pela oxidação enzimática da tirosina é um polímero mais simples constituído principalmente de monômeros 5,6-dihidroxindol (DHI) e de indol-5,6-quinona (IQ). Tirosinase é a enzima chave na produção de melanina, sendo que a sua atividade cinética é medida em função da formação do intermediário dopacroma. Nanopartículas (NPs) de sílica são partículas nanométricas compostas de oxido de silício e são obtidas pelo processo sol-gel desenvolvido por Stöber de hidrólise e condensação de tetraetilortosilicato (TEOS), usando etanol como solvente em meio alcalino. As NPs foram funcionalizadas com 3-Aminopropiltrietoxissilano (ATPES) e depois com glutaraldeído. Este último permitiu a imobilização da tirosinase na superfície da sílica. Caracterizamos as NPs antes e após a reação da enzima, a atividade catalítica da enzima ligada à NP e o mecanismos de formação de melanina na superfície da sílica. As NPs foram caracterizadas por espectrofotometria de absorção e de reflectância, termogravimetria e microscopia eletrônica. A síntese da NP de sílica retornou partículas esféricas com 55nm de diâmetro e a funcionalização da partícula mostrou modificar eficientemente a sua superfície. A imobilização da tirosinase por ligação covalente foi de 99,5% contra 0,5% da adsorção física. A atividade da tirosinase foi caracterizada pela formação de dopacroma. O Km da enzima imobilizada não sofreu alteração em comparação com a tirosinase livre, mas a eficiência catalítica - que considera a eficiência recuperada - foi de apenas 1/3 para a enzima ligada covalentemente, significando que 2/3 das enzimas ligadas não estão ativas. Obtivemos NPs revestidas com melanina a partir de oxidação de tirosina solubilizada em duas preparações: NP com tirosinase ligada covalentemente na superfície e NP funcionalizada com glutaraldeido dispersa em solução de DHI e IQ. O revestimento de melanina foi na forma de um filme fino com espessura ~1,9nm, conferindo perfil de absorção luminosa equivalente ao da própria melanina. Mostramos que o mecanismo de polimerização passa pela oxidação da tirosina pela tirosinase, que gera intermediários oxidados (principalmente DHI e IQ) que vão para solução (mesmo quando a tirosinase está ligada covalentemente na sílica). Estes intermediários ligam-se ao glutaraldeido e a superfície da sílica passa a funcionar como ambiente de polimerização da melanina. / Melanin is a polymer consisting of a large heterogeneity of monomers having as a common feature the presence of indole groups. Contrarily, eumelanin produced by enzymatic oxidation of tyrosine is a simpler polymer consisting mainly of 5,6-dihidroxindol (DHI) and indole-5,6-quinone (IQ) monomers. Tyrosinase is the key enzyme in melanin production, and its kinetic activity is measured by the formation of the intermediate dopacroma. Nanoparticles (NPs) are made of silica nanoparticles of silicon oxide and are obtained by sol-gel method developed by Stöber of hydrolysis and condensation of tetraethylorthosilicate (TEOS), using ethanol as solvent in an alkaline medium. NPs were functionalized with 3-Aminopropyltriethoxysilane (ATPES) and then with glutaraldehyde. The latter allows the immobilization of tyrosinase on the silica surface. We characterized NPs before and after the reaction of the enzyme, the catalytic activity of the enzyme bound to the NP and melanin-forming mechanisms on the silica surface. NPs were characterized by absorption spectrophotometry and reflectance, electron microscopy and thermogravimetric analysis. The synthesis of silica NP returned spherical particles of 55nm diameter and particle functionalization showed efficiently modify its surface. The immobilization of tyrosinase by covalent bond was 99.5% versus 0.5% by physical adsorption. The activity of tyrosinase was characterized by the formation of dopacroma. The Km of the immobilized enzyme did not change compared to the free tyrosinase, but the catalytic efficiency - considering the recovered efficiently - was only 1/3 for the enzyme covalently bound, meaning that 2/3 of the enzymes are not connected active. We obtained melanin coated NPs from tyrosine oxidation in two preparations: NP with covalently bound tyrosinase in the NP surface and NP functionalized with glutaraldehyde dispersed in DHI and IQ solution. The melanin coating was in the form of a thin film with the thickness of ~ 1,9 nm, giving light absorption profile equivalent to that of melanin itself. We showed that the polymerization mechanism involves the oxidation of tyrosine by tyrosinase, which generates oxidized intermediates (especially DHI and lQ) that go into solution (even when tyrosinase is covalently bound to the silica). These intermediates bind the glutaraldehyde and the surface of the silica begins to function as an environment for melanin polymerization.

Melanina é um polímero constituído por uma grande heterogeneidade de monômeros tendo como característica comum a presença de grupos indóis. Por outro lado, a eumelanina produzida pela oxidação enzimática da tirosina é um polímero mais simples constituído principalmente de monômeros 5,6-dihidroxindol (DHI) e de indol-5,6-quinona (IQ). Tirosinase é a enzima chave na produção de melanina, sendo que a sua atividade cinética é medida em função da formação do intermediário dopacroma. Nanopartículas (NPs) de sílica são partículas nanométricas compostas de oxido de silício e são obtidas pelo processo sol-gel desenvolvido por Stöber de hidrólise e condensação de tetraetilortosilicato (TEOS), usando etanol como solvente em meio alcalino. As NPs foram funcionalizadas com 3-Aminopropiltrietoxissilano (ATPES) e depois com glutaraldeído. Este último permitiu a imobilização da tirosinase na superfície da sílica. Caracterizamos as NPs antes e após a reação da enzima, a atividade catalítica da enzima ligada à NP e o mecanismos de formação de melanina na superfície da sílica. As NPs foram caracterizadas por espectrofotometria de absorção e de reflectância, termogravimetria e microscopia eletrônica. A síntese da NP de sílica retornou partículas esféricas com 55nm de diâmetro e a funcionalização da partícula mostrou modificar eficientemente a sua superfície. A imobilização da tirosinase por ligação covalente foi de 99,5% contra 0,5% da adsorção física. A atividade da tirosinase foi caracterizada pela formação de dopacroma. O Km da enzima imobilizada não sofreu alteração em comparação com a tirosinase livre, mas a eficiência catalítica - que considera a eficiência recuperada - foi de apenas 1/3 para a enzima ligada covalentemente, significando que 2/3 das enzimas ligadas não estão ativas. Obtivemos NPs revestidas com melanina a partir de oxidação de tirosina solubilizada em duas preparações: NP com tirosinase ligada covalentemente na superfície e NP funcionalizada com glutaraldeido dispersa em solução de DHI e IQ. O revestimento de melanina foi na forma de um filme fino com espessura ~1,9nm, conferindo perfil de absorção luminosa equivalente ao da própria melanina. Mostramos que o mecanismo de polimerização passa pela oxidação da tirosina pela tirosinase, que gera intermediários oxidados (principalmente DHI e IQ) que vão para solução (mesmo quando a tirosinase está ligada covalentemente na sílica). Estes intermediários ligam-se ao glutaraldeido e a superfície da sílica passa a funcionar como ambiente de polimerização da melanina. / Melanin is a polymer consisting of a large heterogeneity of monomers having as a common feature the presence of indole groups. Contrarily, eumelanin produced by enzymatic oxidation of tyrosine is a simpler polymer consisting mainly of 5,6-dihidroxindol (DHI) and indole-5,6-quinone (IQ) monomers. Tyrosinase is the key enzyme in melanin production, and its kinetic activity is measured by the formation of the intermediate dopacroma. Nanoparticles (NPs) are made of silica nanoparticles of silicon oxide and are obtained by sol-gel method developed by Stöber of hydrolysis and condensation of tetraethylorthosilicate (TEOS), using ethanol as solvent in an alkaline medium. NPs were functionalized with 3-Aminopropyltriethoxysilane (ATPES) and then with glutaraldehyde. The latter allows the immobilization of tyrosinase on the silica surface. We characterized NPs before and after the reaction of the enzyme, the catalytic activity of the enzyme bound to the NP and melanin-forming mechanisms on the silica surface. NPs were characterized by absorption spectrophotometry and reflectance, electron microscopy and thermogravimetric analysis. The synthesis of silica NP returned spherical particles of 55nm diameter and particle functionalization showed efficiently modify its surface. The immobilization of tyrosinase by covalent bond was 99.5% versus 0.5% by physical adsorption. The activity of tyrosinase was characterized by the formation of dopacroma. The Km of the immobilized enzyme did not change compared to the free tyrosinase, but the catalytic efficiency - considering the recovered efficiently - was only 1/3 for the enzyme covalently bound, meaning that 2/3 of the enzymes are not connected active. We obtained melanin coated NPs from tyrosine oxidation in two preparations: NP with covalently bound tyrosinase in the NP surface and NP functionalized with glutaraldehyde dispersed in DHI and IQ solution. The melanin coating was in the form of a thin film with the thickness of ~ 1,9 nm, giving light absorption profile equivalent to that of melanin itself. We showed that the polymerization mechanism involves the oxidation of tyrosine by tyrosinase, which generates oxidized intermediates (especially DHI and lQ) that go into solution (even when tyrosinase is covalently bound to the silica). These intermediates bind the glutaraldehyde and the surface of the silica begins to function as an environment for melanin polymerization.

La0.6Ca0.4Mn0.8Ni0.2O3-, La0.6Ca0.4Mn0.8Fe0.2O3- und La0.75Ca0.25Mn0.5Fe0.5O3-Volumenmaterialien wurden im potentiometrischen Messaufbau bereits erfolgreich auf ihre NO-Sensitivität getestet. Keramischen Nanomaterialien werden generell eine Reihe neuer oder verbesserter Eigenschaften (verbessertes Sinterverhalten, erhöhte NOx-Sensitivität, höhere Leitfähigkeit) zugesprochen. La0.6Ca0.4Mn0.8Ni0.2O3, La0.6Ca0.4Mn0.8Fe0.2O3 und La0.75Ca0.25Mn0.5Fe0.5O3 wurden mittels PVA/Sucrose-Methode, Aktivkohlemethode und Fällungssynthese als Nanomaterialien sowie mit Festkörperreaktion als Volumenmaterialien dargestellt und mit typischen Charakterisierungsmethoden untersucht. Die Materialien wurden in verschiedenen Schichtdicken auf YSZ-Substrate aufgetragen und potentiometrisch sowie impedanzspektroskopisch auf ihre NO-Sensitivität und die Querempfindlichkeit gegenüber NO2 und Propylen geprüft. Potentiometrische Messungen im NO-Gasstrom ergeben eine Abhängigkeit der NO-Sensitivität von der Partikelgröße, der Schichtdicke und der Beschichtungsmethode. Impedanzspektroskopische Messungen an beidseitig beschichteten YSZ-Substraten zeigen ebenfalls eine Abhängigkeit des Zellwiderstands von der NO-Konzentration und der Partikelgröße. Die Nanomaterialien zeigen bei unterschiedlichen Sauerstoffpartialdrücken im untersuchten Temperaturbereich (300°C bis 850°C) höhere Leitfähigkeiten als die Volumenmaterialien gleicher Zusammensetzung. Dieses Verhalten wird mit dem höheren Sauerstoffaustausch der Nanomaterialien in Verbindung gebracht, der zur Erzeugung zusätzlicher Defekte in der Kristallstruktur führt. Die Nanostruktur und somit eine entsprechend hohe Leitfähigkeit bleiben bei hohen Sintertemperaturen (T > 1000°C), die der Herstellung gasdichter Presslinge dienen, erhalten. XANES- und Photoelektronenspektroskopie wurden verwendet, um die Punktdefekte zu definieren.

Submitted by MARCIA ROVADOSCHI (marciar@unifra.br) on 2018-08-20T12:07:07Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese_MirkosOrtizMartins.pdf: 14740958 bytes, checksum: 7fbd6b5923fb58ef079c134775d7e50d (MD5) / Made available in DSpace on 2018-08-20T12:07:07Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Tese_MirkosOrtizMartins.pdf: 14740958 bytes, checksum: 7fbd6b5923fb58ef079c134775d7e50d (MD5) Previous issue date: 2016-07-22 / In this thesis is studied the interaction between the nitrogenous bases, adenine, cytosine, guanine and thymine with two nanostructures: the graphene and silicene nanoribbons through ab initio calculations based on DFT (Density Functional Theory) using the SIESTA (Spanish Initiative for Electronic Simulations with Thousands of Atoms) software. Prior to implementing the software to simulate the behavior at the atomic level of molecules all feature and variants was studied, for computer modeling and simulation; which applications using nanostructures and the best spatial con guration for construction of an initial parameter simulation. The nitrogenous bases as main constitution of the genetic code component, in the form of a double trainer strand of DNA, is the point of interest of this work, along with their behavior when the interaction, by positioning the walking distance - with nanoribbons graphene and silicene. The simulation of the nitrogenous bases and nanoribbons initially obey perpendicular position with the atoms of forming hydrogen bonds in DNA, pointing to the nanostructures. It was calculated, at the end of the simulations, the removal of nitrogenous bases of its current initial position, the di erence in the values of total energy and charge transfer. It has been shown that the interaction energy between nitrogenous bases and graphene nanoribbon are thinner than those found for the interaction with the silicene nanoribbon. When the nitrogenous bases are placed parallel to nanoribbons (both of graphene as silicene) they present chemical bonds, while when they are arranged perpendicularly to the surface of the material, they deviate in the course of its transverse path. It also follows that the silicene nanoribbon is more stable in the adsorption energy than nanoribbon graphene and the interaction of the bases is the energy bands that change xiii subtly, with respect of the gap values. For the graphene nanoribbon, the changes are associated with the position of the Fermi level. These results show, in an original way, di erent con gurations for the nitrogeneous basis on one dimensional carbon and silicon materials. / Nessa tese e estudada a intera c~ao entre as bases nitrogenadas, adenina, citosina, guanina e timina, com duas nanoestruturas: a nano ta de grafeno e a nano ta de siliceno, atrav es de c alculos ab initio baseados na Teoria do Funcional da Densidade (DFT), utilizando o software SIESTA (Spanish Initiative for Electronic Simulations with Thousands of Atoms), esse programa computacional executa c alculos de estrutura eletr^onica e simula c~oes ab initio de din^amica molecular de mol eculas e s olidos. Anterior a execu c~ao do software para simular o comportamento a n vel at^omico das mol eculas, foi estudada a caracter stica e variantes, para modelagem e simula c~ao computacional; quais as aplica c~oes utilizando nanoestruturas e a melhor con gura c~ao espacial para constru c~ao de um par^ametro inicial de simula c~ao. As bases nitrogenadas, sendo componente principal da constitui c~ao do c odigo gen etico, na forma de um duplo lamento formador do DNA (Deoxyribonucleic acid - Acido Desoxiribonucleico), e o ponto de interesse deste trabalho, juntamente com seu comportamento quando na intera c~ao, atrav es do posicionamento a pouca dist^ancia - com as nano tas de grafeno e siliceno. A simula c~ao entre as bases nitrogenadas e as nano tas inicialmente obedecem um posicionamento perpendicular com os atomos formadores das liga c~oes de hidrog^enio, no DNA, apontando para as nanoestruturas. Foi calculado, ao nal das simula c~oes, o afastamento das bases nitrogenadas da sua posi c~ao atual, a diferencia c~ao nos valores de energia total e a respectiva transfer^encia de carga. Foi demonstrado que a energia de adsor c~ao entre as bases nitrogenadas e a nano ta de grafeno s~ao mais t^enues do que aquelas encontradas para a intera c~ao com a nano ta de siliceno. Quando as bases nitrogenadas s~ao colocadas paralelas as nano tas (tanto de grafeno quanto de siliceno) elas fazem liga c~oes qu micas, enquanto se forem dispostas perpendicularmente a superf cie do material, as mesmas se xi afastam no decorrer de seu trajeto transversal. Tamb em se conclui que a nano ta de siliceno e mais est avel no sentido de energia de adsor c~ao do que a nano ta de grafeno e a intera c~ao das bases faz as bandas de energia dessa, alterar de forma sutil, via mudan ca no gap de energia. No caso da adsor c~ao na nano ta de grafeno observam-se altera c~oes na posi c~ao do n vel de Fermi, sem mudan cas nas caracter sticas met alicas do sistema original. Desta forma, este trabalho apresenta, de forma original, diferentes con gura c~oes para a intera c~ao de bases nitrogenadas em sistemas unidimensionais de carbono e sil cio, com aplica c~ao para a detec c~ao individual das bases nitrogenadas formadoras da mol ecula de DNA.