The Effect of Various Electrode Microstructure Parameters on the Effective Conductivity and Three-Phase Boundary Density of Infiltrated SOFC Electrodes

Solid oxide fuel cell (SOFC) technology has the potential to be a significant player in our future energy technology repertoire based on its ability to convert chemical energy into electrical energy. Infiltrated SOFCs, in particular, have demonstrated improved performance and at lower cost than traditional SOFCs. An infiltrated electrode comprises porous ceramic scaffolding (typically constructed from the oxygen ion conducting material) that is infiltrated with electron conducting and catalytic particles. Two important SOFC electrode properties are effective conductivity and three phase boundary density (TPB). Researchers study these electrode properties separately, and fail to recognize them as competing properties. This thesis aims to (1) develop a method to model the TPB density and use it to determine the effect of porosity, scaffolding particle size, and pore former size on TPB density as well as to (2) compare the effect of porosity, scaffolding particle size, and pore former size on TPB density and effective conductivity to determine a desired set of parameters for infiltrated SOFC electrode performance. A computational model was used to study the effect of microstructure parameters on the effective conductivity and TPB density of the infiltrated SOFC electrode. From this study, effective conductivity and TPB density are determined to be competing properties of SOFC electrodes. Increased porosity, scaffolding particle size, and pore former particle size increase the effective conductivity for a given infiltrate loading above percolation threshold. Increased scaffolding particle size and pore former size ratio, however, decreases the TPB density. The maximum TPB density is achievable between porosities of 45% and 60%. The effect of microstructure parameters are more prominent at low loading with scaffolding particle size being the most significant factor and pore former size ratio being the least significant factor.

Legality and Human Rights: Administrative Justice in Russia 1862-1917

The question of how far pre-revolutionary Russia was from the ideal of a lawful state has received little academic attention, particularly as relates to the legal regulation of relations between person, society and state within the state administration. Pravilova explored the methods of settling disputes between individuals and the administration, and the emergence of legal controls of the administration, analysed projects for the organisation of administrative justice and studied the particular nature of concepts from Russian administrative justice. The idea of an organisation of special bodies examining complaints by private persons against the actions of officials and state bureaucratic organs first appeared in the early 1860s. In the 1870s-1890s various projects for the reform of administrative justice (reorganisation of the Senate and local administrative institutions) were proposed by the Ministries of Justice and Finance, but none of these was put into practice, largely due to resistance from the bureaucracy. At the same time, however, the rapid development of private enterprise, the activities of the zemstvo and self-government produced new norms and mechanisms for the regulation of authorities and social relations. Despite the lack of institutional conditions, the Senate did consider complaints from private persons against illegal actions by administrative officials, playing a role similar to that of the supreme administrative courts in France and Germany. The spread of concepts of a 'lawful state' aroused support for a system of administrative justice and the establishment of administrative tribunals was seen as a condition of legality and a guarantee of human rights. The government was forced to understand that measures to maintain legality were vital to preserve the stability of the system of state power, but plans for liberal reforms were pushed into the background by constitutional reforms. The idea of guarantees of human rights in relations with the authorities was in contradiction with the idea of the monarchy and it was only when the Provisional Government took power in 1917 that the liberal programme of legal reforms had any chance of being put into practice. A law passed in June 1917 ordained the organisation of local administrative justice bodies, but its implementation was hampered by the war, the shortage of qualified judges and the existing absolute legal illiteracy, and the few administrative courts that were set up were soon abolished by the new Soviet authorities. Pravilova concluded that the establishment of a lawful state in pre-revolutionary Russia was prevented by a number of factors, particularly the autocratic nature of the supreme authority, which was incompatible with the idea of administrative justice as a guarantee of the rights of citizens in their relations with the state.

The impact of different glacial boundary conditions on atmospheric dynamics and precipitation in the North Atlantic region

Using a highly resolved atmospheric general circulation model, the impact of different glacial boundary conditions on precipitation and atmospheric dynamics in the North Atlantic region is investigated. Six 30-yr time slice experiments of the Last Glacial Maximum at 21 thousand years before the present (ka BP) and of a less pronounced glacial state – the Middle Weichselian (65 ka BP) – are compared to analyse the sensitivity to changes in the ice sheet distribution, in the radiative forcing and in the prescribed time-varying sea surface temperature and sea ice, which are taken from a lower-resolved, but fully coupled atmosphere-ocean general circulation model. The strongest differences are found for simulations with different heights of the Laurentide ice sheet. A high surface elevation of the Laurentide ice sheet leads to a southward displacement of the jet stream and the storm track in the North Atlantic region. These changes in the atmospheric dynamics generate a band of increased precipitation in the mid-latitudes across the Atlantic to southern Europe in winter, while the precipitation pattern in summer is only marginally affected. The impact of the radiative forcing differences between the two glacial periods and of the prescribed time-varying sea surface temperatures and sea ice are of second order importance compared to the one of the Laurentide ice sheet. They affect the atmospheric dynamics and precipitation in a similar but less pronounced manner compared with the topographic changes.

High-resolution computer simulations of stacking of weak bases using a transient pH boundary in capillary electrophoresis. 1. Concept and impact of sample ionic strength

The dynamics of focusing weak bases using a transient pH boundary was examined via high-resolution computer simulation software. Emphasis was placed on the mechanism and impact that the presence of salt, namely, NaCl, has on the ability to focus weak bases. A series of weak bases with mobilities ranging from 5 x 10(-9) to 30 x 10(-9) m2/V x s and pKa values between 3.0 and 7.5 were examined using a combination of 65.6 mM formic acid, pH 2.85, for the separation electrolyte, and 65.6 mM formic acid, pH 8.60, for the sample matrix. Simulation data show that it is possible to focus weak bases with a pKa value similar to that of the separation electrolyte, but it is restricted to weak bases having an electrophoretic mobility of 20 x 10(-9) m2/V x s or quicker. This mobility range can be extended by the addition of NaCl, with 50 mM NaCl allowing stacking of weak bases down to a mobility of 15 x 10(-9) m2/V x s and 100 mM extending the range to 10 x 10(-9) m2/V x s. The addition of NaCl does not adversely influence focusing of more mobile bases, but does prolong the existence of the transient pH boundary. This allows analytes to migrate extensively through the capillary as a single focused band around the transient pH boundary until the boundary is dissipated. This reduces the length of capillary that is available for separation and, in extreme cases, causes multiple analytes to be detected as a single highly efficient peak.