We report here the results of a de Haas-van Alphen (dHvA) investigation of the coupled orbit system in magnesium. The data were taken for magnetic fields extending to 52 kG and temperatures down to 0.29° K. The experimental data are interpreted in the light of coupled orbit system theories of Pippard and of Falicov and Stachowiak; these are each reviewed in some detail. The data are found to disagree qualitatively with the predictions of Falicov and Stachowiak. Since this theory has been assumed, for more than a decade, to be equivalent to Pippard's theory, a detailed comparison of these was made. Full spectrum Fourier analysis of Pippard's band structure density of states shows that the two models disagree qualitatively and, therefore, that they are not equivalent. These experimental results, which do not appear to disagree with Pippard's theory, are interpreted to mean that it is fnally possible to obtain crystals of sufficient purity and perfection to make it necessary to use a band structure description of the delocalized electrons on the couple network. Evidence is presented for the existence of a new type of dHvA frequency corresponding to the ΓKM plane cross-section of the Brillouin zone. A proposed explanation for this dHvA frequency involves the field dependent modulation of the zero frequency component of the Fourier transform of the coupled orbit system density of states. Also included are discussions of crystal preparation and handling, cryogenic apparatus, analogue detection apparatus, digital data acquisition and processing hardware based on a microcomputer, and a new software system ideally suited to small computer research environments.

No description available.

No description available.

No description available.

Vibrational spectroscopy is used to elucidate the adsorption mechanisms of model volatile organic pollutants with a variety of mineral oxides. Vapor phase adsorption processes are particularly important in the vadose zone of an aquifer, where void spaces are filled with air and vapor transport is significant. Gaining a better understanding of the interactions occurring at the oxide-air interface is critical in developing or improving remediation strategies. In this work, Raman and infrared spectroscopy are used to obtain molecularly specific information concerning model pollutant-oxide adsorption processes. The choices of pollutants are varied to include several classes of compounds. The interactions of azaarenes, aromatics, chlorinated aromatics, trichloroethylene, and tributyl phosphate are investigated with several mineral types. Pure mineral phases such as silica, alumina, hydrated iron oxide, and montmorillonite clay are used to provide a basis set of interactions, which can be extended to more complex systems in the future. Pollutantoxide interactions, including weak physisorption, hydrogen bonding, Bronsted acid-base, and Lewis acid-base, were identified in this work and varied depending on the specific pollutant-oxide system. This research provides surface adsorption information on environmentally relevant contaminants and the techniques may be utilized to verify the accuracy of pollutant fate and transport models and to improve remediation strategies for such pollutants.

Viruses cause 60% of human infections and are probably the most common cause of infectious disease acquired indoors. Rapid spread of viral illness in indoor establishments facilitates disease morbidity and mortality. The goal of this dissertation is to clarify the role of fomites in the viral infection cycle. Research methods include investigation of published literature, and the use of polymerase chain reaction (PCR) for viral detection. The Appendix A study reviewed published literature to assess the significance of fomites in the transmission of ten common respiratory and enteric viruses (rhinovirus, respiratory syncytial virus (RSV), influenza A, parainfluenza 1 (HPIV1), coronavirus, rotavirus, calicivirus, hepatitis A virus (HAV), astrovirus and adenovirus). Results suggest that fomites play an important role in the transmission of common viral pathogens, and the use of disinfectants may limit the spread of viral disease. The Appendix B study examined PCR primer detection limits by determining the time length viruses can be isolated on fomites. Results indicated that poliovirus 1 and hepatitis A virus could be detected for up to 60 days. Parainfluenza 1 virus isolation yielded detection at 30 days and 50 days. Norovirus isolation yielded detection at 20 days and 30 days. Influenza virus isolation results were inconsistent, yielding no initial detection and detection up to 20 days. Appendix C assessed the occurrence of human parainfluenza 1 virus (HPIV1) on surfaces in office settings. HPIV1 was detected on 37% of fomites. HPIV1 was detected most on desktops (47%), and least on light switches (19%). Study results indicated a statistically significant difference between positive fomites in different buildings (Chi-square p < 0.011), and between building cubicles and conference room fomites (Chi-square p < 0.011). Appendix D evaluated the prevalence of influenza A virus on surfaces in day care and home settings. Influenza A was isolated on 23% of fall day care fomites and 53% of spring day care fomites. Influenza was isolated on 59% of home fomites sampled during March, and no influenza was detected on home fomites sampled during the summer. Overall, Influenza A virus was isolated on over 50% of fomites in homes and day care centers.

No description available.

In this thesis, the spectral behavior of the fundamental and sum-frequency waves, generated from the surface of a thin metal film in the Kretschmann configuration, is theoretically studied with coherent ultrashort pulses. As a first exploration of considering spectral response in nonlinear plasmonics, it is shown that the spectra of reflected sum-frequency waves exhibit pronounced shifts for the incident fundamental waves close to the plasmon coupling angle, whereas meanwhile those of reflected fundamental waves display energy holes. We also demonstrate that the scale of discovered plasmon-enhanced spectral changes is strongly influenced by the magnitude of the incidentce angle and the source pulse duration, and at a certain angle a spectral switch is observed. The appearance of large sum-frequency wave shifts can serve as an unambiguous plasmon signatur in nonlinear surface spectroscopy. Also, the discovered spectral switch can trigger extremely surface-sensitive nonlinear plasmonic sensors.

No description available.

No description available.