Functional nanoparticles have garnered considerable attention due to their intriguing physical properties at the nanoscale for a broad range of applications, such as photocatalysis, capacitive energy storage, thermoelectric power generation, solar energy harvesting, flexible and transparent electronics, drug delivery, biomolecular electronics, and analytic chemistry, etc. Successful synthesis of nanoparticles and precise control over their shapes are critical to achieving desired functions. In the first part of my thesis, an effective synthetic route to plain nanoparticles is briefly introduced. Based on this general route, the synthesis of solid iron oxide nanoparticles and a slightly modified synthetic method of solid silica nanoparticles are presented in detail. In the second part of my thesis, simulation of optical absorption spectra and plasmonic near-field maps of gold nanoparticle and gold/titanium oxide nanoparticle are explored, and the effectiveness of simulation in predicting, optimizing, and guiding experimental design is emphasized.

Policy goals for lifelong learning prioritise a need to motivate people to participate in purposeful learning and to become autonomous lifelong learners. As the latest of a series of initiatives in the vocational curriculum, Advanced GNVQs adopted a controversial assessment model to achieve these aims. The implementation of the model in the further education (FE) sector has taken place at a time of protracted restructuring in colleges. This study evaluates the effects of Advanced level GNVQ policy on students' autonomy and motivation. It focuses on the 'policy trajectory' created by the interplay between macro, meso and micro-level factors. The research developed and tested a theoretical typology to connect types of motivation and autonomy to formative assessment practices through three layers of analysis: (a) the structural and ideological context of policy for lifelong learning; (b) the particular policy debates and processes that surrounded the GNVQ assessment model and (c) the social processes of assessment within two GNVQ courses in two FE colleges. By combining these three layers, the thesis set out to relate to a tradition of policy scholarship and to contribute to the sociological study of the political, cultural, social and pedagogic roles that assessment systems play in the UK. The study draws upon a wide range of data collection techniques, including interviews with policy-makers, teachers and students, participant observation in colleges, documentary analysis and questionnaires. It adopts multiple perspectives for analysing data to raise issuesa bout assessmenpt olicy and practice in four broad areas.F irst, policy development for GNVQs shows that extreme ad hocery, chaos and controversy continue to beset assessment policy in the UK, particularly over what 'standards' of assessment mean. This, together with the speed of development, lack of funding and turf wars between different constituencies has created an 'assessment regime' where new forms of regulation, pedagogy and organisational practices shape meanings associated with 'autonomy' and 'motivation'. Second, this regime affects teachers' and students' values and beliefs about vocational education and their formative assessmenpt ractices. The study argues that a combination of mechanisms for regulating teachers' assessmenpt ractices, resource pressuresa nd student expectations about acceptable engagement with learning create and shape students' 'assessment careers'. In this respect, the study contributes evidence to a growing body of work on the social and cultural processes and effects of assessment and to research which explores learners' identities and 'learning careers'. Third, the study highlights barriers to improving formative assessmentin postcompulsory education but offers recommendations to various interested constituencies that might contribute to this goal. Last, the study offers tentative suggestionsa bout how current assessmenpt olicy and pedagogy' might relate to specific ideological trends associated with 'risk consciousness'.

Thesis (Ph. D.)--University of Michigan, 1915. / Maps on lining-papers. Published also without thesis note. "Source materials": p. 272-279.

Thesis (Ph. D.)--University of Michigan, 1915. / Maps on lining-papers. Published also without thesis note. "Source materials": p. 272-279.

This dissertation research resulted in the development of a Fe based catalyst with Co as a co catalyst, and Ru and ZnO as promoters. The role of Cu and K as promoters and the effect of SiO2 as an alternate support to gamma- Al2O3 were also investigated. A series of Fe-based catalysts for Fischer-Tropsch (F-T) synthesis were prepared. The different promoters were incorporated into the catalyst by impregnation The catalysts were characterized by several methods. The catalytic performance of these materials for F-T synthesis were investigated in a newly designed fixed bed reactor system in the gas phase. It should be noted that the three phase slurry bubble reactors systems are commercially preferred. The reaction conditions were varied for benchmarking the Fe-Zn-K/ gamma- Al2O3 catalyst and for the bimetallic Fe-Co-Zn/ gamma- Al2O3 catalyst and to identify optimal process parameters for further catalyst designs. The H2:CO ratio used in this study was 2. The newly designed catalysts showed significantly high activity towards CO conversion (>70 %), along with low selectivity towards CO2 (5 -15 %) and methane (ND - 3 %). The data show that varying the process conditions, it is possible to achieve narrow distribution of the liquid products. The results employing Fe-Zn-K catalysts showed that an increase in pressure increased the mean carbon chain length. In contrast, an increase in temperature resulted in a decline in the average carbon chain length. Increasing the feed flow rate, or in other words decreasing the residence time of the reactants and the intermediates, resulted in a decrease in the average carbon number in the product hydrocarbons. The evaluation of the effect of process conditions on the performance of Fe-Co-Zn catalysts revealed that the effect of pressure on the carbon chain length was reversed. Increasing the pressure from 250 to 350 psig decreased the carbon chain length. The increase in temperature, however, resulted in a decrease in the carbon chain length as observed in the Fe-Zn-K catalysts. Fe catalysts groups containing different proportions of Co were prepared. It was determined that an Fe:Co ratio of 4:1 is sufficient to obtain high CO conversions with a high selectivity towards liquid hydrocarbons. The hydrocarbon distribution on the other hand remained almost unchanged due to a change in the Co content. The use of silica, as opposed to alumina as the catalyst support, enhanced the CO conversion and the selectivity of the process towards liquid hydrocarbons. The methane and CO2 selectivities on both the supports remained unchanged. However, a significant difference in the liquid hydrocarbon distribution was observed. Addition of K to the catalyst resulted in a change in the liquid hydrocarbon distribution in that a slight increase in the heavier hydrocarbons was observed. A series of Fe4Co1Zn0.04 based catalysts for Fischer-Tropsch (F-T) synthesis, in which the different amounts of Ru are incorporated by the impregnation were also studied. The results showed the incorporation of Ru suppressed the CH4 formation at the cost of increasing the CO2 selectivity.

No description available.

ABSTRACT This thesis presents the results from research conducted on Fischer-Tropsch synthesis (FTS) in supercritical CO2 from syngas (H2:CO =1:1) typically produced from coal gasification and using a Fe-Zn-K catalyst. Experiments were conducted with syngas alone at different pressures (200 psi - 1050 psi) and temperatures (275, 350 and 375 oC). Experiments were also conducted with a syngas pressure of 200 psi and at different partial pressures of an inert diluent (N2) such that the total pressure varied from 200 psi to 1050 psi. Finally, experiments were conducted with CO2 as a diluent and at a syngas pressure of 200 psi. The CO2 partial pressure was increased from 0 psi to 1400 psi (non critical to supercritical conditions). The data show an enhancement in the hydrocarbon selectivity and reduction in the parasitic loss of carbon efficiency due to CO2 formation along with significant improvement in the conversion rates. The experiments were conducted in a unique reactor setup that can conduct gas phase or supercritical phase FT synthesis in both batch or flow modes. The use of the supercritical CO2 (ScCO2) inhibited both CH4 and CO2 selectivities while enhancing the rates of synthesis. In addition, the use of supercritical CO2 is expected to prolong the life of the catalyst presumably by removing the heat of reaction from the catalyst's surface and solubilizing the waxes that tend to deposit on the surface. Although not within the scope of this thesis, the products from such a reactor system can be easily separated without the need of an additional unit process simply by tuning the pressure and temperature. The product spectrum and the selectivities for the different products are presented for each set of experiments. The effects of process parameters such as temperature, pressure, N2 partial pressure, and CO2 partial pressure on the product spectrum are also discussed. The clear increase in CO conversion at H2:CO ratio of 1:1 in supercritical phase as compared to gas phase reaction, the decrease in CO2 and CH4 selectivity, and an overall shift in the product distribution towards higher hydrocarbons have been demonstrated. Thus the use of supercritical CO2 has the potential through the FT process to convert coal to liquid fuels using Fe based catalysts, especially since the reactions can be conducted in a two phase regime without losing the benefits of the 3-phase slurry reactor systems

Increase in carbon dioxide emissions due to economic activity induce global warming. The strong increase in energy demand, mainly based on oil and coal, induces a rapid increase in CO2 in the atmosphere. Within Canada, the amount of human-produced carbon dioxide is considerable because a large portion of energy is supplied by burning of fossil fuels. The Reverse Water Gas Shift (RWGS) reaction is a promising catalytic process for the utilization and subsequent activation of carbon dioxide to carbon monoxide, which can be further converted into fuels such as gasoline. The current thesis studies the development of nano-catalytic systems for the RWGS reaction. Mono- and bi-metallic nanoparticles based on Cu, Fe, Ru and Pt were prepared using a polyol synthesis method. The catalytic performance of three different types of metal oxides (ionically conductive, mixed ionic-electronic conductive and non-conductive) was investigated for the RWGS reaction. Conductive metal oxides including samarium-doped ceria (SDC), ceria (CeO2), yttria-stabilized zirconia (YSZ) and iron III oxide (Fe2O3) were further used as the catalyst supports and the nanoparticles of Cu, Fe, CuxFe1-x (x = 50 and 95 at.%), Ru, Pt, Ru50Pt50 and RuxFe1-x (x = 80 and 90 at.%) were subsequently deposited on them. A stoichiometric mixture of H2 and CO2, i.e. H2/CO2 = 1, was used under atmospheric pressure in the temperature range of 300 - 600°C in order to evaluate the catalyst performance in terms of activity, stability and selectivity. Nanoparticles deposited on ceria-based supports (CeO2 and SDC) showed superior catalytic performance compared to other metal oxides. Among all the catalyst tested, 5 wt.% Ru50Pt50/CeO2 showed the highest CO yield and satisfactory stability for RWGS reaction. The second best catalytic systems were based on Ru90Fe10/CeO2 and Ru80Fe20/CeO2, which are more attractive from the practical point of view.

This diploma thesis deals with analysis and modification of thin layers using ion beams. The first part of this diploma thesis deals with phenomena accompanying ion beam bombardment of solid matter. The second part of this diploma thesis is concerned with Secondary Ion Mass Spectroscopy (SIMS) and Low Energy Ion Scattering (LAIS). This work convey some basic information about these two techniques and it also deals with some benefits result in their connection into parallel depth profiling mode (such as better depth resolution of the LEIS profile, quantification of the SIMS). These benefits are demonstrated on MoSi film measurement. Within the framework of this thesis a new UHV manipulator was designed. This new UHV manipulator is equipped with precise stepper UHV motor and since the proportions are smaller, the manipulation with a sample in a space limited UHV chamber is much more comfortable and more precise. The third part of this diploma thesis deals with ion-beam induced transformation of epitaxially grown Fe films with thickness of 22 monolayer (ML) and 44 ML on Cu(100) single crystal at room temperature. Metastable Fe films of 22 ML thickness were prepared in CO pressure and 44 ML Fe films were prepared by co-evaporation of Fe with Fe64Ni36 (invar). Structural changes are analyzed by scanning tunneling microscopy and low-energy electron diffraction. The aim of this thesis is to discuss the influence of the sputtering parameters such as ion dose and ion energy on the nucleation of bcc nanocrystals, their growth, final shape and size. The influence of different Ni concentration on stability of 44 ML thick Fe films is also discussed.

En el presente trabajo se aborda un estudio completo sobre los consumos de los bienes culturales públicos en la ciudad de Santa Fe, Argentina. Se abordan en diferentes bloques una contextualización histórica, social, económica y política de la Argentina y más concretamente de Santa Fe, para a continuación abordar los consumos de los bienes culturales públicos en la primera década del nuevo siglo.