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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

Interaction of JLP with PLK1 recruits FoxK1 to form a ternary complex during mitosis

Ramkumar, Poornima January 2015 (has links)
JLP (JNK associated Leucine zipper protein) is a scaffolding protein that has been shown to interact with and activate the JNK/p38MAPK pathway. Its interaction with various signaling proteins is associated with coordinated regulation of cellular processes such as endocytosis, motility, neurite outgrowth, cell proliferation and apoptosis. Here, we undertook a mass spectrometric approach to identify novel interaction partners of JLP and identified the mitotic Ser/Thr kinase, Polo like Kinase 1 (PLK1) and the Fox transcription factor, Forkhead box protein K1 (FoxK1), as proteins that interact with and form a ternary complex with JLP during mitosis. Domain mapping studies showed that the N-terminal domain of JLP interacts with the polo-box domain (PBD) of PLK1 in a phosphorylation-dependent manner. Our results indicate that, JLP is phospho-primed on Thr351, which is recognized by the PBD of PLK1 and leads to phosphorylation of JLP at additional sites. Moreover, treatment of cells with the PLK1 inhibitor BI2536 affects this interaction, demonstrating the importance of PLK1 kinase activity in this process. Because JLP is a scaffolding protein that recruits proteins to mediate specific cell signaling events, the interaction of JLP with PLK1 likely results in the recruitment of other proteins to this complex. To test this hypothesis, we carried out SILAC labeling of proteins in mitotic cells in the presence or absence of BI2536. Through mass-spectrometry, we identified the FoxK1 transcription factor as a PLK1-dependent JLP-interacting protein. Furthermore, we show that JLP, PLK1 and FoxK1 form a ternary complex that is present only during mitosis. Knockdown of PLK1 and not JLP affected the interaction between JLP and FoxK1, indicating that the formation of the ternary complex is PLK1-dependent. FoxK1 is a known transcriptional repressor of the cyclin dependent kinase inhibitor, p21/WAF1. Knockdown of JLP in U2OS cells resulted in increased FoxK1 protein levels and a reduction of p21 expression. Moreover, immunofluorescence studies in asynchronous cells showed that FoxK1 is excluded from the nucleus during mitosis and that a fraction of FoxK1 localizes to the midbody region during cytokinesis. Analysis of FoxK1 protein in cells exiting S-phase suggests that FoxK1 is post-translationally modified during mitosis. In this study we characterized the ternary complex formed between JLP, PLK1 and FoxK1 during mitosis. Based on our observations, we propose that formation of the JLP/PLK1/FoxK1 ternary complex regulates the stability and/or transcriptional activity of FoxK1. / Molecular Biology and Genetics
132

Formation and physicochemical properties of crystalline and amorphous salts with different stoichiometries formed between ciprofloxacin and succinic acid

Paluch, Krzysztof J., McCabe, T., Müller-Bunz, B., Corrigan, O.I., Healy, A.M., Tajber, L. 15 August 2013 (has links)
Yes / Multi-ionizable compounds, such as dicarboxylic acids, offer the possibility of forming salts of drugs with multiple stoichiometries. Attempts to crystallize ciprofloxacin, a poorly water-soluble, amphoteric molecule with succinic acid (S) resulted in isolation of ciprofloxacin hemisuccinate (1:1) trihydrate (CHS-I) and ciprofloxacin succinate (2:1) tetrahydrate (CS-I). Anhydrous ciprofloxacin hemisuccinate (CHS-II) and anhydrous ciprofloxacin succinate (CS-II) were also obtained. It was also possible to obtain stoichiometrically equivalent amorphous salt forms, CHS-III and CS-III, by spray drying and milling, respectively, of the drug and acid. Anhydrous CHS and CS had melting points at ∼215 and ∼228 °C, while the glass transition temperatures of CHS-III and CS-III were ∼101 and ∼79 °C, respectively. Dynamic solubility studies revealed the metastable nature of CS-I in aqueous media, resulting in a transformation of CS-I to a mix of CHS-I and ciprofloxacin 1:3.7 hydrate, consistent with the phase diagram. CS-III was observed to dissolve noncongruently leading to high and sustainable drug solution concentrations in water at 25 and 37 °C, with the ciprofloxacin concentration of 58.8 ± 1.18 mg/mL after 1 h of the experiment at 37 °C. This work shows that crystalline salts with multiple stoichiometries and amorphous salts have diverse pharmaceutically relevant properties, including molecular, solid state, and solubility characteristics. / Solid State Pharmaceutical Cluster (SSPC), supported by Science Foundation Ireland under grant number 07/SRC/ B1158.
133

Studies on degradation factors and their mitigation methods of cathode materials for advanced lithium-ion batteries / 先進リチウムイオン電池正極材料の劣化要因とその緩和方法に関する研究 / センシン リチウム イオン デンチ セイキョク ザイリョウ ノ レッカ ヨウイン ト ソノ カンワ ホウホウ ニカンスル ケンキュウ

橋上 聖, Satoshi Hashigami 22 March 2019 (has links)
再生可能エネルギーの大量導入に向けて、電力需給の安定化を目的として蓄電池を用いる電力貯蔵技術に注目が集まっている。現状のリチウムイオン電池(LIB)がベースの先進LIBは250Wh/kgの高エネルギー密度を有し、自動車のみならず電力貯蔵用途としても普及が期待されている。本研究では先進LIB正極材料として期待されるリチウム過剰系正極と高ニッケル三元系正極について容量低下などの劣化要因を明確にして、それら課題に対して正極粒子への酸化物修飾による解決を検討した。 / The development of energy storage technologies using batteries has attracted much attention to introduce the renewable energy. If we can achieve 250 Wh kg-1 with the advanced LIBs based on the principle of LIB, we can lower the cost of the total energy storage systems while ensuring the safety, and hence the advanced LIBs will accelerate the world-wide spread of large-scale power storage systems. In this thesis, the author focused surface modification of lithium-rich layered ternary transition metal oxide and high-nickel layered ternary transition metal oxide cathode particles with oxides as mitigation methods for capacity fading. / 博士(工学) / Doctor of Philosophy in Engineering / 同志社大学 / Doshisha University
134

Diffusivity and resistance to deterioration from freezing and thawing of binary and ternary concrete mixture blends

Beck, Lisa Elanna January 1900 (has links)
Master of Science / Department of Civil Engineering / Kyle Riding / Corrosion of reinforcing steel is one of the most common and serious causes of reinforced concrete deterioration. While corrosion is normally inhibited by a passive layer that develops around the reinforcing steel due to the high pH environment of the surrounding concrete, chlorides will break down this protective layer, leading to reinforcement corrosion. Decreasing the diffusivity of the concrete would slow the ingress of chlorides into concrete, and is one of the most economical ways to increase the concrete service life. Optimized concrete mixtures blending portland cement and supplementary cementing materials (SCMs) have become popular throughout the construction industry as a method of improving both fresh and long-term concrete properties such as workability, strength and porosity. It has been shown that use of Class F fly ash, silica fume and ground granulated blast furnace slag (GGBFS) in binary concrete mixture blends can result in a significant reduction in concrete diffusivity. This study investigates the ability of Class C fly ash and ternary concrete mixture blends to also aid in diffusivity reduction. In order to study the effect of incorporation of SCMs into concrete, mixtures containing Class C and Class F fly ash, silica fume and GGBFS were tested following the ASTM C 1556 procedures to measure the concrete’s apparent chloride diffusivity. Structure life cycles were modeled using the measured apparent chloride diffusivities with two finite-difference based life-cycle analysis software packages. To determine whether a correlation between diffusivity and deterioration due to freezing and thawing exists, samples were also tested for their ability to resist deterioration from freezing and thawing cycles using a modified ASTM C 666 Procedure B test. Results show that the use of Class C fly ash yields some service life improvements as compared to the portland cement control mixtures, while ternary mixture blends performed significantly better than the control mixture and equal to or better than the binary SCM mixtures tested. Freeze-thaw tests showed all mixtures to be equally resistant to deterioration due to freezing and thawing.
135

Formes quadratiques ternaires représantant tous les entiers impairs

Bujold, Crystel 11 1900 (has links)
Les calculs numériques ont été effectués à l'aide du logiciel SAGE. / En 1993, Conway et Schneeberger fournirent un critère simple permettant de déterminer si une forme quadratique donnée représente tous les entiers positifs ; le théorème des 15. Dans ce mémoire, nous nous intéressons à un problème analogue, soit la recherche d’un critère similaire permettant de détecter si une forme quadratique en trois variables représente tous les entiers impairs. On débute donc par une introduction générale à la théorie des formes quadratiques, notamment en deux variables, puis on expose différents points de vue sous lesquels on peut les considérer. On décrit ensuite le théorème des 15 et ses généralisations, en soulignant les techniques utilisées dans la preuve de Bhargava. Enfin, on démontre deux théorèmes qui fournissent des critères permettant de déterminer si une forme quadratique ternaire représente tous les entiers impairs. / In 1993, Conway and Schneeberger gave a simple criterion allowing one to determine whether a given quadratic form represents all positive integers ; the 15-theorem. In this thesis, we investigate an analogous problem, that is the search for a similar criterion allowing one to detect if a quadratic form in three variables represents all odd integers. We start with a general introduction to the theory of quadratic forms, namely in two variables, then, we expose different points of view under which quadratic forms can be considered. We then describe the 15-theorem and its generalizations, with a particular emphasis on the techniques used in Bhargava’s proof of the theorem. Finally, we give a proof of two theorems which provide a criteria to determine whether a ternary quadratic form represents all odd integers.
136

Study Of Covalent And Non-Covalent Interactions In Ternary Systems Involving: Metal/DNA-RNA/Protein, Where Metal = Platinum(II), Palladium(II)

Atilio, Anzellotti I. 01 January 2007 (has links)
Ternary systems comprising DNA/RNA, proteins and one (or more) metal ion are generating increased interest due to its biological relevance. The knowledge gained from the study of these systems could provide important clues regarding the precise mechanism for transcription factors, repair proteins and metal complexes with anti-tumoral/anti-viral activities.The interactions occurring among the components of these ternary systems can be broadly grouped into covalent and non-covalent. The first kind of interactions can lead to the irreversible transformation of the components in the system, while the second is thought to be reversible leading to transient states and fluxionality. Both kinds of interaction are generally present in living systems, complementing the function of each other.Monofunetional Platinum-nucleobase complexes (MPNs) are synthesized via substitution of a chloride ligand by a nucleobase in platinum complexes with trans geometry. MPNs are particularly interesting for the study of ternary systems since they mimic the first step in the formation of a platinum-DNA adduct and their interaction with aminoacids/proteins provide a good first approach for more complex systems.The presence of the nucleobase as a ligand, significantly modifies the biological activity of these complexes by reducing its cytotoxicity and generating a promising anti-viral activity, especially against HIV-1 virus. The specific role of the nucleobase ligand on these complexes as a non-covalent motif, important for protein recognition, was explored in models involving tryptophan/N-acetyl tryptophan and a small protein domain called zinc finger, containing also a tryptophan residue.The coordination of the nucleobase to a metal ion such as Pt(II) or Pd(II) was found to increase its π-stacking interaction towards aromatic residues in proteins, specifically tryptophan. The enhancing effect was found to depend on the nature of the metal ion, nature of nucleobase and size/complexity of the protein model. Furthermore, DFT studies revealed an important change in the energy for the lowest unoccupied molecular orbital (LUMO) in the coordinated nucleobases, which could place this orbital in an favored position to interact with the highest occupied molecular orbital (HOMO) in the tryptophan residue. Results from calculations showed a good correlation with experimental evidence and could indicate an important role for the frontier molecular orbitals (HOMO/LUMO) of the species involved in the π-stacking interaction.This study was extended to a zinc finger domain from an essential protein in HIV-1 virus, i.e. nucleocapsid protein NCp7. Findings showed that the nucleobase ligand in addition to modulate hydrolysis and reaction rates for MPNs can also be responsible for an initial non-covalent recognition towards a specific protein. This initial recognition has been proposed as the first stage in a two-step mechanism of action for these platinum complexes that ultimately can lead to zinc ejection from the zinc finger domain in the viral NCp7. The significance of the data presented show that is possible to modulate the ligand coordination sphere in metal complexes to can result in great differences in terms of biological effects.The novel chemistry derived from DNA adducts with platinum complexes with a trans geometry was also explored in silico. The molecular dynamics of two free DNA 20-mer is compared with the corresponding metallated-adducts, namely monofunctional, 1,2-bifunctional interstrand and 1,3-bifunctional intrastrand. The differences in terms of structure and energy are compared for these systems, in general the monofunctional adduct exhibited the most interesting feature in terms of structural change in the DNA double strand causing the destacking of the metallated nucleobase. Bifunctional adducts exhibited loss of Watson-crick bonds and localized change in sugar puckering. These results showed that important differences can be found for platinated DNA even at short simulation times < 1 ns.
137

Obtenção e caracterização de complexos binários e ternários de sinvastatina e ciclodextrinas / Attainment and characterization of binary and ternary complexes of simvastatin and cyclodextrins.

Takahashi, Andrea Ikeda 18 December 2009 (has links)
O objetivo do presente trabalho foi obter complexos binários e ternários de sinvastatina (SNV) e ciclodextrinas (CDs) utilizando diferentes tipos de CDs, métodos de secagem e polímeros para selecionar aquele que proporcionam um maior aumento da solubilidade aquosa do fármaco. Inicialmente complexos com diferentes CDs, a &#945;, &#946;, &#947;, e hidroxi-propil-&#946; (HP&#946;CD) foram obtidos através da secagem em estufa. Foram empregados os seguintes ensaios para sua caracterização: solubilidade, DSC, TG e difração de raios X. Adicionalmente, foi realizada a modelagem molecular com simulações de dinâmica molecular. O complexo com &#947;CD parece ser o mais adequado para a complexação com a SNV, pois, foi o mais estável (menor energia) na modelagem molecular, além de ter apresentado uma nova fase sólida na difração de raios X. Complexos de SNV, &#947;CD ou HP&#946;CD foram obtidos por diferentes métodos de secagem (estufa com circulação forçada de ar, coevaporação, liofilização e estufa a vácuo) e a caracterização foi realizada através da solubilidade, DSC, TG e difração de raios X. Todos os complexos melhoraram a solubilidade da SNV, mas quando comparados às respectivas misturas físicas, o ganho foi baixo. As curvas DSC e a difração de raios X indicam que, no máximo, pode ter ocorrido uma complexação parcial em alguns casos. O que se verifica é que mesmo o complexo que apresentou maior ganho de solubilidade (HP&#946;CD obtido pela coevaporação), a complexação do não foi total. Complexos ternários de SNV, &#946;CD e diferentes polímeros (polietilenoglicol 1500, polietilenoglicol 4000, povidona, copovidona, crospovidona, maltodextrina e hidroxipropil-metilcelulose) foram preparados utilizando-se a coevaporação. A caracterização dos complexos foi realizada através da solubilidade, DSC e TG. Para todos os complexos houve ganho de solubilidade, mas apenas quando foi utilizado a crospovidona e a maltodextrina, existe diferença significativa entre a solubilidade observada para a mistura física e aquela registrada para o complexo. As curvas DSC indicam que ainda existe fármaco na forma livre até mesmo nos complexos que apresentaram maior solubilidade, dessa forma, nenhum dos polímeros utilizados foi capaz de promover um complexação total da SNV. / The purpose of this study was to obtain binary and ternary complexes of simvastatin (SV) and cyclodextrins (CDs) using different types of CDs, drying methods and polymers, to select those that offer greater increase in aqueous solubility of the drug. Initially, different complexes with CDs, &#945;, &#946;, &#947;, and hydroxy-propyl-&#946; (HP&#946;CD), were obtained using oven drying. The following tests were performed for complexes´s characterization: solubility, DSC, TG and X-ray diffraction. Additionally, molecular modeling was performed with molecular dynamics simulations. The complex with &#947;CD seems to be the most suitable for complexation with the SV, since it has been the most stable (lowest energy) in molecular modeling, and has presented a new solid phase in X-ray diffraction. Complex of SV, &#947;CD or HP&#946;CD were obtained by different drying methods (forced air circulation oven, co-evaporation, freeze drying and vacuum oven) and the characterization was performed by solubility, DSC, TG and X-ray diffraction. All the complexes improved the solubility of SV, but when compared to their physical mixtures, the gain is low. The DSC curves and X-ray diffraction indicates that, at most, a partial complexation may have happened in some cases. It was verified that even the complex that had greater increase in solubility (HP&#946;CD obtained by co-evaporation), the complexation was not total. Ternary complexes of SV, &#946;CD and different polymers (polyethyleneglycol 1500, polyethyleneglycol 4000, povidone, copovidone, crospovidone, maltodextrin and hydroxypropyl-methyl-cellulose) were prepared using the co-evaporation. The characterization of the complexes was performed by solubility, DSC and TG. For all complexes there was a gain of solubility, but only when crospovidone and maltodextrin were used, there was a significant difference between the solubility observed for the physical mixture and the complex. The DSC curves indicate that non comlexed drug is still present, even in the complexes that had higher solubility. Thus, none of the polymers was able to promote a total complexation of SV.
138

Propriedades vibracionais de nitretos do grupo III e de suas ligas / Vibrational properties of group-III nitrides and their alloys

Santos, Adriano Manoel dos 23 April 2004 (has links)
Os nitretos do grupo III (BN, AIN,Gan e InN) e suas ligas ternárias Al-GaN e InGaN proporcionam, recentemente, um extraordinário avanço na fabricação de dispositivos opto-eletrônicos operando na região do espectro correspondente ao verde-azul-UV e na produção de dispositivos eletrônicos de alta frequência, alta temperatura e alta potência. Estes materiais semicondutores de gap largo atraíram enorme atenção dos pesquisadores nos últimos anos. O objetivo desta tese é o estudo das propriedades vibracionais dos nitretos do grupo III referente tanto ao cristal perfeito, quanto ao cristal com defeito. Utilizamos como base a Teoria Clássica do Crital Harmônico e o Método das Funções de Green. Com a Teoria Clássica do Cristal Harmônico, juntamente com o Método do Valence Force Filed e o Método da Soma de Ewald, que permitem gerar a matriz dinâmica do sistema, determinamos o comportamento vibracional dos nitretos binários e das ligas ternárias. A utilização destes métodos permitiu a obtenção do espectro de fônons dos nitretos binários, e o estudo do comportamento dos modos ópticos em para as ligas ternárias. A partir da Função de Green do cristal perfeito e da Função de Green do cristal com defeito, obtivemos as frequências e os modos vibracionais localizados e ressonantes introduzidos pela impureza de C e As em GaN. A partir das densidades de estados do cristal perfeito e do cristal com defeito, calculamos a entropia de formação da vacância de N em GaN. Os resultados obtidos foram usados na interpretação de dados experimentais disponíveis na literatura, relativos às propriedades vibracionais dos nitretos na estrutura wurtzita, e na predição e análise de dados experimentais obtidos pelo grupo do Laboratório de Novos Materiais Semicondutores do Instituto de Física da USP para os nitretos zincblende. / The group-III nitrides (BN, AIN, GaN and InN) and their ternary alloys AlGaN and InGaN generated recently an extraordirlary progress in the production of optoelectronic devices operating in the green-blue-UV region of the spectrum, and in the production of electronic devices of high frequency, high temperature and high power. These wide gap semiconductor materials attracted enormous attention in the last years. The objective of this Thesis was to study the vibrational properties of the bulk III nitrides, without and with defects. To accomplish this study we used the Classic Theory of the Harmonic Crystal and the Method of the Green\'s Functions. With the Classic Theory of the Harmonic Crystal, together with the Valence Force Field Method and the Method of the Ewald\'s Sum, that allow to generate the dynamic matrix of the system, we determined the vibrational behavior of the binary nitrides and of the ternary alloys. The use of these methods allowed us to obtain the phonon spectra of the binary nitrides and to study the behavior of the optical modes at of the ternary alloys. Starting from the Green\'s Function of the perfect crystal and the Green\'s Function of the crystal with defect, we obtained the frequencies and the localized and resonant vibrational modes introduced by the C and As impurities in GaN. Starting from the densities of states of the perfect crystal and of the crystal with defect, we calculated the formation entropy of the N vacancy in GaN. The obtained results were used in the interpretation of experimental data related to the vibrational properties of the wurtzite nitrides available in the literature, and in the prediction and analysis of experimental results obtained for zincblende nitrides by the group of the New Semiconductors Materials Laboratory of t11c Physics Institute at USP.
139

Un modèle théorique des mélanges ternaires de lipides et de cholestérol / Ternary mixtures of lipids and cholesterol : a theoretical model

Wolff, Jean 14 June 2013 (has links)
Nous proposons un modèle théorique original pour décrire le processus de formation et la coexistence de phase dans les mélanges ternaires de phospholipides et de cholestérol. Ce modèle combine les effets de transitions de phase liquide-gel, décrits à l'aide d'un paramètre d'ordre interne, et les effets de mélange non-idéaux inspirés des modèles de Flory pour décrire l'influence du cholestérol. Notre approche thermodynamique décrit avec un réel succès la coexistence de mélanges phospholipide binaires, tel que DOPC-DPPC. Le paramètre d'ordre inspiré de l'approche de Doniach et de l'analogie avec le modèle d'Ising sous champ magnétique modélise de façon simplifiée la thermodynamique des chaînes alkyles dans la bicouche lipidique. Nous obtenons d'une part des diagrammes ternaires ressemblant aux diagrammes expérimentaux mais aussi la dépendance en température des équilibres de phases. Nous décrivons également des diagrammes pour d'autres espèces, telles que PSM, POPC ou DiphytanoylPC. Notre approche, combinant géométrie discrète et résolution des équations analytiques pour la détermination des caractéristiques des diagrammes de Gibbs est novatrice, et s'applique à une classe étendue de modèles thermodynamiques avec paramètre d'ordre. Nous cherchons ensuite à décrire des systèmes inhomogènes à l'aide d'une généralisation de Ginzburg-Landau du modèle précédent. Une application importante consiste à déterminer la tension de ligne $\tau$ et le profil d'une interface entre macrodomaines de phase liquide ordonné et désordonné. Enfin, nous étendons la théorie du mouillage de Cahn à la description de l'environnement d'une inclusion circulaire de rayon fini $R$ dans un ``océan lipidique'', à coexistence et hors coexistence. Nous discutons pour finir les effets de la proximité du point critique et ses conséquences quant aux interactions entre impuretés induites par les effets de mouillage. / We propose a new theoretical model for describing the formation and the phase coexistence in ternary mixtures of phospholipids and cholesterol. This model combines the properties of the liquid-gel phase transition, described with an internal order parameter, with some non ideal mixing behavior accounting for the influence of cholesterol, and inspired by Flory's description of polymer melts. Our thermodynamical approach successfully accounts for the coexistence of binary phospholipid mixtures such as DOPC-DPPC. The order parameter, originally introduced by Doniach, describes in a simplified manner the thermodynamics of the alkyl chains in a lipid bilayer, by analogy with the Ising model under magnetic field. We not only obtain ternary diagrams resembling to experimental diagrams, but also discuss the evolution of these phase equilibria with temperature. This approach is then generalized to other lipid components, namely PSM, POPC and DiphytanoylPC.Our approach, made of a combination of discrete geometry calculations and numerical resolutions of the analytical equations for determining the properties of the Gibbs diagram is novel, and applies to a wide class of thermodynamic models with order parameters. A Landau-Ginzburg extension of the above model allows us to study inhomogeneous systems. A firstimportant application consists in determining the line tension $\tau$ and the profile of an interface separating macrodomains of ordered and disordered liquid phase. We extend Cahn's wetting theory to the case of a circular inclusion of finite radius $R$ in a ``lipid sea'', at coexistence and offcoexistence. We finally discuss the effects of the proximity of a critical point, and the consequences relative to mutual interactions between impurities induced by the wetting process.
140

Preparação, caracterização e estudo eletroquímico de ligas Pt/M e Pt/M/M1 (M, M1 = Mo, Sn, Ru, Os e W) para eletrooxidação de etanol com aplicações em DEFC / Preparation, characterization and electrochemical studies on Pt/M/M1 (M,M1 = Mo, Sn, Ru, Os and W) catalysts for ethanol oxidation and DEFC application

Anjos, Daniela Marques dos 14 December 2007 (has links)
A eletrooxidação de etanol foi investigada sobre catalisadores bi e trimetálicos constituídos de Pt-M1 e Pt-M-M1 M = Sn, Mo, W, Ru, Os e Ir). Os eletrodos foram preparados em três diferentes configurações: eletrodos lisos (preparados em forno a arco voltaico), filmes depositados em placas de Ti (Pt-M/Ti) e nanopartículas metálicas dispersas em carbono (Pt-M-M1/C), ambos preparados pelo método Pechini. Os resultados eletroquímicos mostraram que a adição dos diferentes metais à platina aumentou a atividade catalítica dos eletrodos. Este efeito se mostrou dependente da composição do eletrodo e para os eletrodos lisos apresentou resultados mais acentuados nas composições Pt-Os e Pt-Sn-W. Os intermediários e produtos de reação da oxidação de etanol os eletrodos lisos foram determinados pelas técnicas de FTIR in situ de SPAIRS e SNIFTIRS. Os resultados sugerem que a presença dos elementos modificadores da platina aumentam a velocidade da reação de oxidação de etanol pela dessorção de intemediários com dois átomos de carbono (como CH3CHOads) a potenciais mais baixos do que a Pt levando conseqüentemente a liberação dos sítios ativos para nova adsorção de etanol. Constatou-se contudo, que a presença desses elementos não favorece a quebra da ligação C-C para formação de CO2 em quantidades apreciáveis. As composições de catalisadores Pt-M/Ti (M = Sn, Ru, Ir e Mo) preparados pelo método Pechini que apresentaram os melhores resultados em densidades de corrente foram os eletrodos de Pt-Sn/Ti. As análise por HPLC mostraram o produto majoritariamente formado foi o acetaldeído independente da composição do catalisador, mas os catalisadores Pt-Sn/Ti tiveram a maior seletividade na formação de ácido acético. Os testes em célula unitária foram realizados para os catalisadores trimetálicos Pt-Sn-W/C em diferentes composições. A presença de Sn e W aumentou significativamente o desempenho da célula com relação à Pt pura. O melhor catalisador testado (Pt-Sn-W/C (85:8:7)) apresentou OCV de 777 mV contra 345 mV da Pt a 90oC. A densidade de potência máxima alcançada para essa composição foi de 33 mW cm-2. A análise de produtos ao final de 5 horas de reação a 90oC aplicando 30 mA cm-2 de corrente mostrou que os produtos principalmente formados foram ácido acético e acetaldeído. / Ethanol oxidation on Pt-M1 e Pt/M/M1 (M = Sn, Mo, W, Ru, Os e Ir) catalysts prepared by arc melting furnace process and Pechini method was investigated. The electrochemical data showed that the addition of these elements to Pt gives a highest current densities at lower potentials. The best composition of electrodes prepared by arc melting process based on current densities values was Pt-Os and Pt-Sn-W. The intemediates and reaction products for ethanol oxidation were detected by SPAIRS and SNIFTIRS. The results sugest that adding a foreign metal to Pt leads an increase of the reaction rate for ethanol oxidation because desorption of two carbon atoms intermediates (as CH3 CHOads) at lower potentials comparing to pure Pt. The active site become then available for the new ethanol adsorption. However, the presence of these metals doesn\'t increase the selectivity to CO2 generation. Pt-M/Ti (M = Sn, Ru, Ir e Mo) catalysts were prepared by Pechini method. The products of the ethanol oxidation on these electrodes were evaluated by HPLC. The results showed that acetaldehyde was the main product obtained for all compositions. DEFCs tests were carry on with Pt-Sn-W/C ternary catalysts in different compositions. It was obtained particles size about 3.9 to 11 nm, depending on the catalyst composition. The addition of Sn and W increased significantly the DEFC performance. The best result was obtained by Pt-Sn-W/C (85:8:7) catalyst. It presents OCV about 777 mV against 345 mV to Pt at 90oC. The maximum of power density for this catalyst was 33 mW cm-2. Acetaldehyde was the major product formed when applying a fixed current of 30 mA cm-2 at 90oC.

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