CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Dois experimentos foram conduzidos para determinar os melhores nÃveis nutricionais de sÃdio e cloro para codornas italianas destinadas à produÃÃo de carne (1 a 49 dias de idade). Em cada experimento, 384 codornas com um dia de idade foram distribuÃdas em um delineamento inteiramente casualizado, com seis tratamentos e oito repetiÃÃes de oito aves por unidade experimental. Os nÃveis de sÃdio e de cloro avaliados foram: 0,07; 0,12; 0,17; 0,22; 0,27 e 0,32%. Observou-se efeito quadrÃtico dos nÃveis de sÃdio sobre o consumo de raÃÃo, ganho de peso e sobre os rendimentos de carcaÃa e coxa+sobrecoxa, com nÃveis Ãtimos de 0,257%, 0,216%, 0,207% e 0,191%, respectivamente. O aumento do sÃdio na raÃÃo promoveu prejuÃzo linear na conversÃo alimentar e aumento na ingestÃo de Ãgua. Entretanto, a umidade das excretas e o rendimento de peito nÃo foram afetados significativamente pelos nÃveis de sÃdio. Para o cloro, nÃo foram observados efeitos significativos dos nÃveis de cloro das raÃÃes sobre todos os parÃmetros avaliados. Considerando os resultados, pode-se recomendar que as raÃÃes para codornas italianas destinadas à produÃÃo de carne, na fase de 1 a 49 dias, sejam formuladas com 0,22% de sÃdio e nÃveis de cloro entre 0,07% a 0,32% / Two experiments were conducted to determine the best sodium and chlorine nutritional levels to Italian quails for meat production (aged 1 to 49 days). In each trial, 384 one-day quails were distributed in a completely randomized design with six treatments and eight replications of eight birds of experimental unit. The levels of sodium and chlorine evaluated were: 0,07; 0,12; 0,17; 0,22; 0,27 and 0,32%. It was observed a quadratic effect of the sodium levels on feed intake, weight gain and yields of carcass and thigh plus drumstick, with optimal levels of 0,257%, 0,216%, 0,207% and 0,191% respectively. The increase in sodium level in the diet produced a linear decrease in feed conversion and an in increase in water intake. However, the excreta moisture and breast yield were not significantly affected by the sodium levels. As for chlorine, we did not observe any significant effects of the chlorine levels in the diets on all the parameters evaluated. From the results, we can recommend that the diets for Italian quails bred for meat production, in the phase from 1 to 49 days, are formulated with 0,22% of sodium level and chlorine levels from 0,07% to 0,32%

Electrolytic cells convert chemical energy directly into electrical energy cleanly and efficiently. An integral component of a fuel cell and an electrolytic cell is the electrolyte, a material that conducts ions. Liquid electrolytes can be aqueous as in the phosphoric acid and alkaline fuel cells, or molten, as in the molten carbonate fuel cells. A solid electrolyte is preferable because it allows sturdier, more efficient and corrosion resistant systems to be built. The main objective of this work is to develop a solid electrolyte for hydrogen production by electrolysis of hydrogen sulfide. Barium Hydrogen Phosphate, Barium Dihydrogen Phosphate, Cesium Hydrogen Carbonate, and Ammonium Iodide received brief attention but Cesium Hydrogen Sulfate was the primary candidate considered. Initial investigation has verified that Cesium Hydrogen Sulfate undergoes an impressive first-order phase transition at approximately 140°C at which the proton conductivity increases by almost four orders of magnitude. An electrochemical cell was designed and developed by Erik Todd for the production of hydrogen. Hydrogen sulfide can electrolyzed into hydrogen and sulfur in an electrochemical cell. Sulfur is in a low viscosity molten state at a temperature of 150°C. A cell with cesium hydrogen sulfate electrolyte canoperate at this temperature where liquid sulfur and gaseous hydrogen can move out of the cell as they are formed. Consequently, the electrolyte must possess a high conductivity at this temperature to facilitate the migration of hydrogen ions to the negative electrode through the electrolyte. Cesium Hydrogen Sulfate is known to act as an insulator at room temperature and a protonic conductor at 140°C. Hence it comes as an obvious choice as an electrolyte in a hydrogen sulfide electrochemical cell. The structural and chemical properties of Cesium Hydrogen Sulfate were investigated. • The CsHSO4 electrolyte was prepared by the reaction of cesium carbonate and cesium sulfate with sulfuric acid respectively. • A punch, die and base were designed and fabricated to 0.5" and 2.0" diameter pellets for that purpose. • X-ray diffraction was performed on the 0.5" diameter pellets to identify and characterize the polycrystalline phases of the solid acid electrolyte. • Differential Scanning Calorimetry was performed so as to ascertain the phase transition temperature. • The temperature at which the phase transition occurs was further confirmed by impedance measurements. A test setup was built in order to perform impedance measurements. An experiment to measure the impedance of a 0.5" diameter pellet of silver iodide was performed in order to test the validity of the setup. • An infrared analysis was performed on the prepared sample CsHSO4 in order to identify the bond environment of the electrolyte. • Differential scanning calorimetry was performed with Barium Hydrogen Phosphate, Barium Dihydrogen Phosphate, Cesium Hydrogen Carbonate and Ammonium Iodide to identify their phase transition temperatures. • A successful electrolysis of steam experiment was carried out using the CsHSO4 electrolyte to evaluate its performance. • Finally, the CsHSO4 electrolyte was tested in the hydrogen sulfide electrochemical cell for the production of hydrogen and sulfur.

Polymer electrolytes are the most obvious candidates for safe "all-solid" Li-ion batteries and other electrochemical devices. However, they still have relatively poor ionic conductivities, which limits their wider adoption in commercial applications. It has earlier been the conventional wisdom that only amorphous phases of polymer electrolytes show usefully high ionic conduction, while crystalline forms are insulators. However, this has been challenged in the last decade by the discovery of highly organized, low-dimensional ion-conducting materials. Specifically, the crystalline phases of LiXF6.PEO6 exhibit higher ionic conductivities than their amorphous counterparts, with the Li-ion conduction taking place along the PEO channels. Polymer chain-length and chain-end registry has emerged as potentially significant in determining ionic conduction in these materials. Molecular Dynamics simulations have therefore been made of short-chain, monodisperse (Mw~1000), methoxy end-capped LiPF6.PEO6 to examine relationships between ion conduction and mode of chain-ordering. Studies of smectic and nematic arrangements of PEO chains have revealed that ion-transport mechanisms within the smectic planes formed by cooperative chain-end registry appear to be more suppressed by ion-pairing than in-channel conduction. Disorder phenomena in the chain-end regions emerge as a critical factor in promoting Li-ion migration across chain-gaps, as does the structural continuity of the PEO channels. Simulations incorporating ~1% aliovalent SiF62- dopants further suggest an increase in Li-ion conduction when the extra Li-ions reside within the PEO channels, with the anion influencing charge-carrier concentration through enhanced ion-pair formation. XRD techniques alone are shown to be inadequate in ascertaining the significance of the various short-chain models proposed; atomistic modelling is clearly a helpful complement in distinguishing more or less favourable situations for ion conduction. Though providing valuable insights, it must be concluded that this work has hardly brought us significantly closer to breakthroughs in polymer electrolyte design; the critical factors which will make this possible remain as yet obscure.

As the demand for clean and renewable energy sources continues to grow, much attention has been given to solid oxide fuel cells (SOFCs) due to their efficiency and low operating temperature. However, the components of SOFCs must still be improved before commercialization can be reached. Of particular interest is the solid electrolyte, which conducts oxygen ions from the cathode to the anode. Samarium-doped ceria (SDC) is the electrolyte of choice in most SOFCs today, due mostly to its high ionic conductivity at low temperatures. However, the underlying principles that contribute to high ionic conductivity in doped ceria remain unknown, and so it is difficult to improve upon the design of SOFCs. This thesis focuses on identifying the atomistic interactions in SDC which contribute to its favourable performance in the fuel cell. Unfortunately, information as basic as the structure of SDC has not yet been found due to the difficulty in experimentally characterizing and computationally modelling the system. For instance, to evaluate 10.3% SDC, which is close to the 11.1% concentration used in fuel cells, one must investigate 194 trillion configurations, due to the numerous ways of arranging the Sm ions and oxygen vacancies in the simulation cell. As an exhaustive search method is clearly unfeasible, we develop a genetic algorithm (GA) to search the vast potential energy surface for the low-energy configurations, which will be most prevalent in the real material. With the GA, we investigate the structure of SDC for the first time at the DFT+U level of theory. Importantly, we find key differences in our results from prior calculations of this system which used less accurate methods, which demonstrate the importance of accurately modelling the system. Overall, our simulation results of the structure of SDCagree with experimental measurements. We identify the structural significance of defects in the doped ceria lattice which contribute to oxygen ion conductivity. Thus, the structure of SDC found in this work provides a basis for developing better solid electrolytes, which is of significant scientific and technological interest. Following the structure search, we perform an investigation of the electronic properties of SDC, to understand more about the material. Notably, we compare our calculated density of states plot to XPS measurements of pure and reduced SDC. This allows us to parameterize the Hubbard (U) term for Sm, which had not yet been done. Importantly, the DFT+U treatment of the Sm ions also allowed us to observe in our simulations the magnetization of SDC, which was found by experiment. Finally, we also study the SDC surface, with an emphasis on its structural similarities to the bulk. Knowledge of the surface structure is important to be able to understand how fuel oxidation occurs in the fuel cell, as many reaction mechanisms occur on the surface of this porous material. The groundwork for such mechanistic studies is provided in this thesis.

As the demand for clean and renewable energy sources continues to grow, much attention has been given to solid oxide fuel cells (SOFCs) due to their efficiency and low operating temperature. However, the components of SOFCs must still be improved before commercialization can be reached. Of particular interest is the solid electrolyte, which conducts oxygen ions from the cathode to the anode. Samarium-doped ceria (SDC) is the electrolyte of choice in most SOFCs today, due mostly to its high ionic conductivity at low temperatures. However, the underlying principles that contribute to high ionic conductivity in doped ceria remain unknown, and so it is difficult to improve upon the design of SOFCs. This thesis focuses on identifying the atomistic interactions in SDC which contribute to its favourable performance in the fuel cell. Unfortunately, information as basic as the structure of SDC has not yet been found due to the difficulty in experimentally characterizing and computationally modelling the system. For instance, to evaluate 10.3% SDC, which is close to the 11.1% concentration used in fuel cells, one must investigate 194 trillion configurations, due to the numerous ways of arranging the Sm ions and oxygen vacancies in the simulation cell. As an exhaustive search method is clearly unfeasible, we develop a genetic algorithm (GA) to search the vast potential energy surface for the low-energy configurations, which will be most prevalent in the real material. With the GA, we investigate the structure of SDC for the first time at the DFT+U level of theory. Importantly, we find key differences in our results from prior calculations of this system which used less accurate methods, which demonstrate the importance of accurately modelling the system. Overall, our simulation results of the structure of SDCagree with experimental measurements. We identify the structural significance of defects in the doped ceria lattice which contribute to oxygen ion conductivity. Thus, the structure of SDC found in this work provides a basis for developing better solid electrolytes, which is of significant scientific and technological interest. Following the structure search, we perform an investigation of the electronic properties of SDC, to understand more about the material. Notably, we compare our calculated density of states plot to XPS measurements of pure and reduced SDC. This allows us to parameterize the Hubbard (U) term for Sm, which had not yet been done. Importantly, the DFT+U treatment of the Sm ions also allowed us to observe in our simulations the magnetization of SDC, which was found by experiment. Finally, we also study the SDC surface, with an emphasis on its structural similarities to the bulk. Knowledge of the surface structure is important to be able to understand how fuel oxidation occurs in the fuel cell, as many reaction mechanisms occur on the surface of this porous material. The groundwork for such mechanistic studies is provided in this thesis.

No description available.

The focus of this thesis has been to determine the usable voltage range of carbon-based supercapacitors (SC). Supercapacitors are a relatively new type of capacitors with a vast increase in capacitance compared to capacitors which utilize a dielectric as charge separator. A SC consists of two electrodes and an electrolyte separating the electrodes. The charges are stored by electrostatic forces in the interface between the electrode and the electrolyte, forming the so called electrochemical double-layer (EDL). With porous electrodes the effective surface area of the interfacial zone can be made very large, giving SCs a large storage capacity. The limiting factors of a SC is the decomposition potential of the electrolyte and the decomposition of the electrodes. For commercially manufactured SCs the electrolyte is usually an organic solvent, which has a decomposition potential of up to 2.7-2.8 V. Compared to aqueous electrolytes with a thermodynamic limit of 1.23 V. The drawback of using non-aqueous electrolytes is that they are not environmentally friendly, and they increase the production cost. It is claimed that the voltage range can be up to 1.9 V using aqueous electrolytes. Some researchers have focused on aqueous electrolytes for these reasons. In this thesis two different electrolytes were tested to determine if the voltage range could be extended. The experiments were conducted using a three electrode cell and performing cyclic voltammogram measurements (CV). The carbon electrodes were made of  two different sources of grahite, battery graphite or exfoliated graphite, and nano fibrilated cellulose was added to increase the mechanical stability. The results show that the oxidation potential of the carbon electrode was the positive limit. A usable potential of about 1 V was shown. However, when cycling the electrodes to potentials below the decomposition limit, for hydrogen evolution, interesting effects were seen. A decrease in reaction kinetics, indicating a type of conditioning of the electrode was observed. An increase in charge storage capacitance was also observed when comparing the initial measurements with the final, probably corresponding to an increase in porosity. / KEPS projekt Sundsvall Mitt Universitet

As the demand for clean and renewable energy sources continues to grow, much attention has been given to solid oxide fuel cells (SOFCs) due to their efficiency and low operating temperature. However, the components of SOFCs must still be improved before commercialization can be reached. Of particular interest is the solid electrolyte, which conducts oxygen ions from the cathode to the anode. Samarium-doped ceria (SDC) is the electrolyte of choice in most SOFCs today, due mostly to its high ionic conductivity at low temperatures. However, the underlying principles that contribute to high ionic conductivity in doped ceria remain unknown, and so it is difficult to improve upon the design of SOFCs. This thesis focuses on identifying the atomistic interactions in SDC which contribute to its favourable performance in the fuel cell. Unfortunately, information as basic as the structure of SDC has not yet been found due to the difficulty in experimentally characterizing and computationally modelling the system. For instance, to evaluate 10.3% SDC, which is close to the 11.1% concentration used in fuel cells, one must investigate 194 trillion configurations, due to the numerous ways of arranging the Sm ions and oxygen vacancies in the simulation cell. As an exhaustive search method is clearly unfeasible, we develop a genetic algorithm (GA) to search the vast potential energy surface for the low-energy configurations, which will be most prevalent in the real material. With the GA, we investigate the structure of SDC for the first time at the DFT+U level of theory. Importantly, we find key differences in our results from prior calculations of this system which used less accurate methods, which demonstrate the importance of accurately modelling the system. Overall, our simulation results of the structure of SDCagree with experimental measurements. We identify the structural significance of defects in the doped ceria lattice which contribute to oxygen ion conductivity. Thus, the structure of SDC found in this work provides a basis for developing better solid electrolytes, which is of significant scientific and technological interest. Following the structure search, we perform an investigation of the electronic properties of SDC, to understand more about the material. Notably, we compare our calculated density of states plot to XPS measurements of pure and reduced SDC. This allows us to parameterize the Hubbard (U) term for Sm, which had not yet been done. Importantly, the DFT+U treatment of the Sm ions also allowed us to observe in our simulations the magnetization of SDC, which was found by experiment. Finally, we also study the SDC surface, with an emphasis on its structural similarities to the bulk. Knowledge of the surface structure is important to be able to understand how fuel oxidation occurs in the fuel cell, as many reaction mechanisms occur on the surface of this porous material. The groundwork for such mechanistic studies is provided in this thesis.

Thesis (Ph. D.)--Florida State University, 2005. / Advisor: Joseph B. Schlenoff, Florida State University, College of Arts and Sciences, Dept. of Chemistry and Biochemistry. Title and description from dissertation home page (viewed Feb. 1, 2006). Document formatted into pages; contains xvii, 167 pages. Includes bibliographical references.

Made available in DSpace on 2014-10-09T12:48:18Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:08Z (GMT). No. of bitstreams: 1 09307.pdf: 3599752 bytes, checksum: c720dc7c7bbb65919b1861882ea4796e (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP / FAPESP:01/08029-0