ENERGETIC BIOCIDAL MATERIALS AND SPORE NEUTRALIZATION

The objective of this dissertation is to explore a more accurate and versatile approach to investigating the neutralization of spores suffered from ultrafast heating and biocide based stresses, and further to explore and understand novel methods to supply ultrafast heating and biocides through nanostructured energetic materials A surface heating method was developed to apply accurate (± 25 ˚C), high heating rate thermal energy (200 - 800 ˚C, ~103 - ~105 ˚C/s). Uniform attachment of bacterial spores was achieved electrophoretically onto fine wires in liquids, which could be quantitatively detached into suspension for spore enumeration. The spore inactivation increased with temperature and heating rate, and fit a sigmoid response. The neutralization mechanisms of peak temperature and heating rate were correlated to the DNA damage at ~104 ˚C/s, and to the coat rupture by ultrafast vapor pressurization inside spores at ~105 ˚C/s. Humidity was found to have a synergistic effect of rapid heating and chlorine gas to neutralization efficiency. The primary neutralization mechanism of Cl2 and rapid heat is proposed to be chlorine reacting with the spore surface. The stress-kill correlation above provides guidance to explore new biocidal thermites, and to probe mechanisms. Results show that nano-Al/K2S2O8 released more gas at a lower temperature and generated a higher maximum pressure than the other nano-Al/oxysalts. Given that this thermite formulation generates the similar amount of SO2 as O2, it can be considered as a potential candidate for use in energetic biocidal applications. The reaction mechanisms of persulfate and other oxysalts containing thermites can be divided into two groups, with the reactive thermites (e.g. Al/K2S2O8) that generate ~10× higher of pressure and ~10× shorter of burn time ignited via a solid-gas Al/O2 reaction, while the less reactive thermites (e.g. Al/K2SO4) following a condensed phase Al/O reaction mechanism. These different ignition mechanisms were further re-evaluated by investigating the roles of free and bound oxygen. A constant critical reaction rate for ignition was found which is independent to ignition temperature, heating rate and free vs. bound oxygen.

Ionospheric Turbulence Near the Upper Hybrid Layer: Theory and Experiment

The thesis presents experimental results, simulations, and theory on turbulence excited in magnetized plasmas near the ionosphere’s upper hybrid layer. The results include: The first experimental observations of super small striations (SSS) excited by the High-Frequency Auroral Research Project (HAARP) The first detection of high-frequency (HF) waves from the HAARP transmitter over a distance of 16x10^3 km The first simulations indicating that upper hybrid (UH) turbulence excites electron Bernstein waves associated with all nearby gyroharmonics Simulation results that indicate that the resulting bulk electron heating near the upper hybrid (UH) resonance is caused primarily by electron Bernstein waves parametrically excited near the first gyroharmonic. On the experimental side we present two sets of experiments performed at the HAARP heating facility in Alaska. In the first set of experiments, we present the first detection of super-small (cm scale) striations (SSS) at the HAARP facility. We detected density structures smaller than 30 cm for the first time through a combination of satellite and ground based measurements. In the second set of experiments, we present the results of a novel diagnostic implemented by the Ukrainian Antarctic Station (UAS) in Verdansky. The technique allowed the detection of the HAARP signal at a distance of nearly 16 Mm, and established that the HAARP signal was injected into the ionospheric waveguide by direct scattering off of dekameter-scale density structures induced by the heater. On the theoretical side, we present results of Vlasov simulations near the upper hybrid layer. These results are consistent with the bulk heating required by previous work on the theory of the formation of descending artificial ionospheric layers (DIALs), and with the new observations of DIALs at HAARP’s upgraded effective radiated power (ERP). The simulations that frequency sweeps, and demonstrate that the heating changes from a bulk heating between gyroharmonics, to a tail acceleration as the pump frequency is swept through the fourth gyroharmonic. These simulations are in good agreement with experiments. We also incorporate test particle simulations that isolate the effects of specific wave modes on heating, and we find important contributions from both electron Bernstein waves and upper hybrid waves, the former of which have not yet been detected by experiments, and have not been previously explored as a driver of heating. In presenting these results, we analyzed data from HAARP diagnostics and assisted in planning the second round of experiments. We integrated the data into a picture of experiments that demonstrated the detection of SSS, hysteresis effects in simulated electromagnetic emission (SEE) features, and the direct scattering of the HF pump into the ionospheric waveguide. We performed simulations and analyzed simulation data to build the understanding of collisionless heating near the upper hybrid layer, and we used these simulations to show that bulk electron heating at the upper hybrid layer is possible, which is required by current theories of DAIL formation. We wrote a test particle simulation to isolate the effects of electron Bernstein waves and upper hybrid layers on collisionless heating, and integrated this code to work with both the output of Vlasov simulations and the input for simulations of DAIL formation.

VIOLA MUSIC FROM THE AMERICAS: MUSIC FROM CANADA, UNITED STATES, CUBA, VENEZUELA, MEXICO, AND BRAZIL

The enthusiasm towards writing music for the viola that flourished in the early 1900’s thanks to the efforts of a number of twentieth-century violists and composers rapidly spilled over to North and South America. Viola works by American and Canadian composers have already become cornerstones of the viola repertoire worldwide. On the other hand, compositions from other parts of the American continent remain lesser known outside of their country of origin. This is due in part to the less developed publishing and recording industry in these countries which makes it difficult for performers and programmers from other countries to buy or rent performing materials. As a violist born and trained in Venezuela, performing works by important Latin American composers to new audiences is deeply important to me. This dissertation was completed by performing selected works by Canadian, American, Cuban, Mexican, Brazilian, and Venezuelan composers. Composers from these countries have mixed their rich musical traditions with modern compositional techniques, creating original works that have greatly enriched the viola repertoire. This eclectic mixture of styles makes the music from Latin American composers not only very different from that of American and Canadian composers, but also very different from those of their neighboring countries. Through my three dissertation recitals, I intend to share this music with new audiences and inspire other violists to become familiar with this repertoire. The first recital includes compositions by American composers George Rochberg (1918-2015), Elliott Carter (1908-2012), and Alan Shulman (1915-2002) and Canadian composer Elizabeth Raum (b. 1945). The second recital includes works by Cuban composers Cesar Orozco (b. 1980), and Keyla Orozco (b. 1969), Venezuelan composers Aldemaro Romero (1928-2007) and Modesta Bor (1926-1998), and Venezuelan-Uruguayan composer Efrain Oscher (b. 1974). The third recital includes works by Mexican composers Carlos Chavez (1899-1978), José Pablo Moncayo (1912-1958) and Manuel M Ponce (1882-1948), and Brazilian composers Francisco Mignone (1897-1986) and Brenno Blauth (1931-1993). This music represents a bouquet of a distinctive mixture of styles from different parts of the American continent. Recordings of all three recitals can be accessed at the University of Maryland Hornabake Library.