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Transport and Anisotropy inside Ionic Polymer MembranesHou, Jianbo 26 October 2012 (has links)
Water and ion transport critically determine the performance of many functional materials and devices, from fuel cells to lithium ion batteries to soft mechanical actuators. This dissertation aims to address some fundamental issues regarding transport and anisotropy, structural heterogeneity and molecular interactions inside ionic polymers.
I first discuss a main deficiency of a standard protocol for calibrating high pulsed-field-gradient NMR. I show that high gradient calibration using low γ nuclei is not amenable to measurements on slow diffusing high γ nuclei. Then I employ NMR diffusometry to investigate transport and anisotropy for a series of ionic polymers, from poly(arylene ether sulfone) hydrophilic-hydrophobic multi-block copolymers to polymer blends to perfluorosulfonate random copolymers.
For the multi-block copolymers, NMR diffusion measurements yield diffusion anisotropy as a function of water uptake and block lengths. ²H NMR spectroscopy on absorbed D₂O probes membrane alignment modes. These measurements also provide insights into average defect distributions.
For the blend membranes, we examine the impact of compatibilizer on their transport properties. An increase in compatibilizer significantly improves the membrane phase homogeneity confirmed by SEM and transport studies. Theories of diffusion in porous media yield changes in domain size and tortuosity that correspond to drastic changes in local restrictions to water diffusion among different blend membranes. NMR relaxometry studies yield multi-component T₁ values, which further probe structural heterogeneities on smaller scales than diffusion experiments.
For the random copolymer, the exploration of ion transport reveals inter-ionic associations of ionic liquids (ILs) modulated by hydration level and ionic medium. When ILs diffuse inside ionic polymers, isolated anions diffuse faster (≥ 4X) than cations at high hydration whereas ion associations result in substantially faster cation diffusion (≤ 3X) at low hydration inside membranes, revealing prevalent anionic aggregates.
Finally, I present the strategy and analytical protocol for studying ionomer membranes using ILs. The normal cation diffusion contrasts to the anomalous anion diffusion caused by local confinement structures inside the membranes, which vary drastically with temperature and hydration level. These structures correspond to a density variation of SO₃⁻ groups, which define a distribution of local electrical potentials that fluctuate with temperature and nature of ionic media. / Ph. D.
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Nitrogênio com ou sem calcário superficial para recuperação do capim-marandu /Balieiro Neto, Geraldo. January 2007 (has links)
Resumo: A degradação de cerca de 60 milhões de hectares de pastagens no Brasil afeta diretamente o estado nutricional dos rebanhos, conduzindo os pecuaristas a abrirem novas áreas de floresta, resultando em grave impacto de ordem econômica e ambienta!. A recuperação direta por meio da reposição dos nutrientes extraídos do solo ao longo dos anos representa menor risco ao produtor e reais possibilidades de adoção pela maior parte dos pecuaristas. Com este trabalho, objetivou-se avaliar os efeitos de nitrogênio (O, 100, 200, 300 e 400 kg/halano) com ou sem aplicação superficial de calcário nos atributos químicos de um Latossolo Vermelho distroférrico, nutrição mineral da planta, composição química, digestibilidade in vitro da matéria seca (DIVMS), características estruturais e massa de forragem de capim-Marandu. Foi utilizado um delineamento em blocos ao acaso em arranjo fatorial 2 X 5 com quatro repetições no esquema de parcela subdividida com medidas repetidas no tempo. A aplicação de calcário aumentou o pH e reduziu a acidez potencial nas camadas de O a 5 e 5 a 10 cm, 20 meses após aplicação, aumentou os teores de Ca e Mg, incrementou SB e a CTC na camada de O a 5 cm e saturação por bases nas camadas de O a 5 e 5 a 10 cm. O nitrogênio provocou acidificação do solo nos tratamentos sem calcário. O calcário aumentou a concentração de Ca nas lâminas foliares 11 meses após sua aplicação... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The degradation of 60 million hectares of pastures in Brazil directly affects the nutritional status os cattle herds drives farmers the open new forest areas resulting in great economic and environmental impact. The recovery through the replacement of nutrients extracted from the soil along the years represents lower risk to farmers and real possibilities of adoption by the majority of farmers. It was aimed at to evaluate the effects of nitrogen doses (O, 100, 200, 300 and 400 kg/ha of N by year) with or without surface liming on the chemical attributes of a red Latosol (Oxisol), plant mineral nutrition, chemical composition, "in vitro" digestibility, structural characteristic and herbage mass of Marandu-grass. The analysis of variance was performed based on a complete randomized block at factorial arrangement 2 X 5 with four replications design in a split-split-plot scheme with repeated measures over time. The lime increased the pH and reduced the acidity potential in the layers from O to 5 and 5 to 10 cm, increased the content of Ca, Mg, base sum and cation exchange capacity in the layer from O to 5 cm and base saturation in the layers from O to 5 and 5 to 10 cm. There was positive linear effect of N on the content of K in the layer from O to 5 cm of the soil and negative linear effect on the content of S in the soil layers from 10 to 20 and 20 to 30 cm of depth. There was positive linear effect of dose of N on the content of Ca, P, Mg and S during the summer months and negative linear effect on the same characteristics during the winter months. The content of N and K increased linearly to the increase of the doses of N in ali of months. In the months January and August there was quadratic effect of N doses on the leaf N content... (Complete abstract, click electronic access below) / Orientador: Ricardo de Andrade Reis / Coorientadora: Ana Cláudia Ruggieri / Banca: Valdo Rodrigues Haerling / Banca: Francisco Antonio Monteiro / Banca: Mauro Dal Secco de Oliveira / Banca: Ciniro Costa / Doutor
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Nitrogênio com ou sem calcário superficial para recuperação do capim-maranduBalieiro Neto, Geraldo [UNESP] 12 February 2007 (has links) (PDF)
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balieironeto_g_dr_jabo.pdf: 1088543 bytes, checksum: 541947f11b756954d1dabca944d1c19a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A degradação de cerca de 60 milhões de hectares de pastagens no Brasil afeta diretamente o estado nutricional dos rebanhos, conduzindo os pecuaristas a abrirem novas áreas de floresta, resultando em grave impacto de ordem econômica e ambienta!. A recuperação direta por meio da reposição dos nutrientes extraídos do solo ao longo dos anos representa menor risco ao produtor e reais possibilidades de adoção pela maior parte dos pecuaristas. Com este trabalho, objetivou-se avaliar os efeitos de nitrogênio (O, 100, 200, 300 e 400 kg/halano) com ou sem aplicação superficial de calcário nos atributos químicos de um Latossolo Vermelho distroférrico, nutrição mineral da planta, composição química, digestibilidade in vitro da matéria seca (DIVMS), características estruturais e massa de forragem de capim-Marandu. Foi utilizado um delineamento em blocos ao acaso em arranjo fatorial 2 X 5 com quatro repetições no esquema de parcela subdividida com medidas repetidas no tempo. A aplicação de calcário aumentou o pH e reduziu a acidez potencial nas camadas de O a 5 e 5 a 10 cm, 20 meses após aplicação, aumentou os teores de Ca e Mg, incrementou SB e a CTC na camada de O a 5 cm e saturação por bases nas camadas de O a 5 e 5 a 10 cm. O nitrogênio provocou acidificação do solo nos tratamentos sem calcário. O calcário aumentou a concentração de Ca nas lâminas foliares 11 meses após sua aplicação... / The degradation of 60 million hectares of pastures in Brazil directly affects the nutritional status os cattle herds drives farmers the open new forest areas resulting in great economic and environmental impact. The recovery through the replacement of nutrients extracted from the soil along the years represents lower risk to farmers and real possibilities of adoption by the majority of farmers. It was aimed at to evaluate the effects of nitrogen doses (O, 100, 200, 300 and 400 kg/ha of N by year) with or without surface liming on the chemical attributes of a red Latosol (Oxisol), plant mineral nutrition, chemical composition, in vitro digestibility, structural characteristic and herbage mass of Marandu-grass. The analysis of variance was performed based on a complete randomized block at factorial arrangement 2 X 5 with four replications design in a split-split-plot scheme with repeated measures over time. The lime increased the pH and reduced the acidity potential in the layers from O to 5 and 5 to 10 cm, increased the content of Ca, Mg, base sum and cation exchange capacity in the layer from O to 5 cm and base saturation in the layers from O to 5 and 5 to 10 cm. There was positive linear effect of N on the content of K in the layer from O to 5 cm of the soil and negative linear effect on the content of S in the soil layers from 10 to 20 and 20 to 30 cm of depth. There was positive linear effect of dose of N on the content of Ca, P, Mg and S during the summer months and negative linear effect on the same characteristics during the winter months. The content of N and K increased linearly to the increase of the doses of N in ali of months. In the months January and August there was quadratic effect of N doses on the leaf N content... (Complete abstract, click electronic access below)
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Analýza prístupu krajín strednej a východnej Európy k členstvu v bankovej únii / Analysis of the approaches of Central and Eastern European countries towards their membership in the Banking unionSamuelis, Tomáš January 2014 (has links)
The goal of this thesis is to analyze the approaches of countries in Central and Eastern European region towards their membership in the Banking Union. The selected topic has been investigated based on structural characteristics of the banking sectors of the impacted countries. The comparison of these characteristics resulted in identification of inconsistencies between the 2 standpoints (Opt-in and Opt-out). The thesis monitors the motivation of banks in choosing or changing the legal form of 'their' banks in host markets. The work identifies areas in which the host government can act to prevent banks from converting into branches, thus retaining the regulatory powers in local authorities. The thesis in the first 2 chapters maps the first and the second pillar of the Banking Union, Single Supervisory Mechanism and the Single Resolution Mechanism respectively. Furthermore, it summarizes the results of the European Central Bank in carrying out the Comprehensive Assessment exercise.
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