Formation and characterization of metal and metal oxide nanoparticles

This dissertation contains two parts. The first part is focused on Laser Vaporization Controlled Condensation (LVCC). Silver nanoparticles of controlled size were synthesized by this method in order to produce a Surfaced Enhanced Raman Scattering (SERS) active material. We have investigated the effects of particle size on SERS enhancement and how the addition of halides can further increase the limits of detection. We have also explored using LVCC to synthesize cobalt oxide nanoparticles. This is significant since a simple chemical route doesn\u27t currently exist. Finally, we have reported the synthesis of cobalt nitrate hexahydrate by this method using cobalt metal, oxygen and nitrogen as starting materials. The second part of this dissertation focuses on synthesizing transition metal doped titanium dioxide and zinc oxide by various novel sol-gel techniques for applications in spintronics. Spintronics is based on the concept of carrying information due to the relative spins of electrons. Utilizing spin up and spin down allows twice as much information to be carried on the flow of the electrons. One of the key requirements for a spintronic material is that it must exhibit room temperature ferromagnetism (RTFM). Thus, we synthesized 10% cobalt and iron doped titanium dioxide by a novel synthesis which displays RTFM. We have also explored synthesizing 5% cobalt doped zinc oxide by a room temperature process which also displays RTFM. Finally, RTFM 5% cobalt and iron doped zinc oxide were synthesized by a novel process involving microwave irradiation

Effects of the electric Kelvin force on spray cooling performance

Spray cooling is an efficient thermal management technique that may possibly be improved by employing an electric Kelvin force to control the fluid motion and delay the onset of critical heat flux. In the present study, a spray cooling apparatus consisting of a spray chamber (housing a spray nozzle and electrically heated surface) and a flow generating base package has been built and tested for varying nozzle-to-heater distances and also varying electrode geometries for a range of spray conditions and electrode voltages. The two part goal was to first determine the qualitative sensitivity of the distance between the heated surface and nozzle exit, and second, to determine the magnitude of the effects of the electric Kelvin force on the performance of the spray cooling apparatus for the various electrode geometries.;An experimental nozzle-to-heater spacing comparison performance test indicated that confined flows provide less efficient cooling than unconfined flows but are less dependent on the nozzle-to-heater distance. An experimental and numerical study of four cap electrode designs showed no significant effect of the electric Kelvin force on spray cooling performance. This may have been due to the non-optimal electrode geometries and also possibly due to the properties of the FC-72 fluid used. A redesigned electrode configuration that has been designed using the electric field module of the multiphysics code CFD ACE+ and the use of a different fluid, HFE-7000, showed a cooling effect of the heated surface as well as an increase of approximately 5% in the convection heat transfer coefficient

Reversible paramagnetism to ferromagnetism in transition metal-doped TiO2 nanocrystals prepared by microwave irradiation

TiO2nanoparticlesdoped with 1%, 5%, and 10% M (M=Co, Fe, and Ni) were prepared by microwave irradiation and characterized using x-ray diffraction, transmission electron microscopy, and magnetometry. The as-prepared samples are found to be paramagnetic at room temperature, with the magnetic susceptibility following the Curie-Weiss law in the investigated range of 2–300K. However, transformation from paramagnetism to room-temperature ferromagnetism (RTFM) was observed by hydrogenating the samples at 400°C. Reheating in air converted the samples back to paramagnetic while rehydrogenating the samples again induced ferromagnetism. It is argued that the reversible RTFM observed is due to interaction between the dopant metal ions and oxygen vacancies produced during hydrogenation. X-ray diffraction of the hydrogenated Co- and Fe-doped samples shows only a single TiO2 phase suggesting that the observed RTFM may be intrinsic, but for the Ni-doped samples the magnetism may arise from metallic Ni on the surfaces of the TiO2nanoparticles

The Relationship between Traditional Ecological Knowledge, Evolving Cultures, and Wilderness Protection in the Circumpolar North

There are many unique issues associated with natural resource management in the far north as a result of legislative direction, historic settlement and occupation patterns, northern cultural traditions, ecotourism, economic depression, pressures for energy development, and globalization and modernization effects. Wilderness designation in Canada, the USA, and Finland is aimed at preserving and restoring many human and ecological values, as are the long-established, strictly enforced, nature reserves in Russia. In Alaska and Finland, and in some provinces of Canada, there is a variety of values associated with protecting relatively intact relationships between indigenous people and relatively pristine, vast ecosystems. These values are often described as “traditional means of livelihood,” “traditional means of access,” “traditional relationships with nature,” or “traditional lifestyles.” Traditional ecological knowledge (TEK) forms part of these relationships and has been acknowledged as a contributor to understanding the effects of management decisions and human-use impacts on long-term ecological composition, structure, and function. Wilderness protection can help maintain opportunities to continue traditional relationships with nature. As cultures continue to evolve in customs, attitudes, knowledge, and technological uses, values associated with both TEK and relationships with relatively pristine ecosystems will also evolve. Understanding these relationships and how to consider them in wilderness protection and restoration decision making is potentially one of the most contentious, widespread natural resource management issues in the circumpolar north

Spectrally tunable magnetic nanoparticles designed for distribution/recollection applications

The comprehensive goal of this research is the synthesis and characterization of nanomaterials that are spectrally tunable in terms of their electromagnetic signal, are robust, magnetic (allowing their piloted movement), and have the potential to be functionalized for the detection of CBRNE threats. Various chemical methods were utilized for synthesis of magnetic (iron) and luminescent rare earth (RE) components, and their mixtures. Effects of integrating an iron core into RE luminescent lattices (excited by UV, emit in the VIS) were investigated. The determination of the optimum balances between magnetic and luminescent components such that the magnetism was maximized while maintaining acceptable fluorescence integrity will be discussed. The emphasis of this work is focused on developing a distributed sensor suitable for use in the terrestrial environment. The robust properties of using a RE luminescent shell would allow the particles to be resistant to photobleaching. Additionally the chemical stability of the RE shell would allow operation in a variety of pH conditions. The magnetic core will ultimately allow the distributed particles to be recollected