A long-period grating is obtained by introducing a periodic refractive index modulation in the core of a hydrogen-sensitized germanosilicate fiber. The phase-matching condition causes light from the fundamental guided mode to couple to discrete, forward-propagating cladding modes. These cladding modes attenuate rapidly on propagation and result in loss bands at distinct wavelengths in the grating transmission spectrum. We present a comprehensive analysis of the spectral modulation provided by long-period gratings. An analytical model is developed to predict the location of the resonance bands as functions of the grating period and the parameters of the host fiber. These gratings with small insertion loss and negligible back-ret1ection are shown to possess two different regions of operation, namely, normal and anomalous. The fabrication and high temperature annealing of these devices is detailed, and a novel method to obtain these gratings without employing ultra-violet radiation is presented. Long-period gratings are proposed as simple yet versatile optical fiber sensors. It is demonstrated that external temperature and axial strain introduce large spectral shifts in the resonance bands. A theoretical evaluation of the sensitivity reveals a strong dependence on the properties of the optical fiber, the grating periodicity, the order of the cladding mode, the writing and annealing conditions, and the index of refraction of the surrounding medium. Temperature-insensitive and strain-insensitive long-period gratings written in standard optical fibers are studied for their sensing characteristics. Long period grating-based refractive index sensors are obtained without etching the cladding of the fiber. It is demonstrated that long-period grating sensors can be implemented with simple demodulation schemes. Applications of these devices to structural health monitoring and biochemical sensing are presented. Finally, long-period gratings are demonstrated as effective sensors that can be used to separate temperature and axial strain acting simultaneously on the fiber. Strain-insensitive gratings are used to extend the dynamic range of the system in the presence of non-linearities and cross-sensitivities. / Ph. D.

The overall focus of this dissertation is on how chronic shear stress alters the synthesis and secretion of important regulatory molecules by endothelial cells. Our hypothesis was that inclusion of chronic pulsatile shear stress in our model would lead to changes in endothelial cell release of regulatory molecules. We distinguished between high arterial shear stresses and low venous shear stresses and used static cell cultures as reference. The first part of this research thus entailed the complete characterization of the flow dynamics in our experimental biomechanical model. Cell stretching can have a physiological effect on endothelial cells; hence we implemented a laser based optical technique for real time strain measurement of the growth fibers used in our culture system, and found that no significant strains were occurring during shear treatment. After characterization of the mechanical environment of the cells, we focused the scope of our research on metabolism of proteoglycans and insulin-like growth factor-I (IGF-I) and related IGF binding proteins (IGFBPs) in bovine aortic endothelial cells cultured under chronic pulsatile shear. We found that shear stress increased the release of proteoglycans and significantly altered proteoglycans distribution. We also found that there was an inverse relationship between the shear level treatment used to obtain the purified proteoglycans from endothelial cells and their potency in inhibiting coagulation. IGF-I release and message (IGF-I mRNA) was decreased at high shear stress compared to low shear stress. Further, the levels found under shear were significantly greater than those observed in the static cell culture model. IGFBPs released were also significantly increased by shear. This research thus establishes a link between chronic pulsatile shear stress and the metabolism of both primary (IGF-I) and secondary (IGFBPs, proteoglycans) regulators of vascular cell activity. The improved realism of our experimental biomechanical model has proved to be a valuable tool in improving the relevance of this study to vascular research. Ultimately, this research calls for further investigation in the molecular mechanisms underlying the phenomenological effects documented, which may help in understanding fundamental aspects in cardiovascular disease and its link to hemodynamics but our work is an important first step. / Ph. D.

Distributed temperature and strain sensing is demanded for a wide range of applications including real-time monitoring of industrial processes, health monitoring of civil infrastructures, etc. Optical fiber distributed sensors have attracted tremendous research interests in the past decade to meet the requirements of such applications. This research presents a multiplexed sensor array for distributed temperature and strain sensing that can multiplex a large number of UV-induced sensors along a single fiber. The objective of this research is to develop a quasi-distributed sensing technology that will greatly increase the multiplexing capacity of a sensor network and can measure temperature and strain with a high accuracy and high resolution. UV-induced intrinsic Fabry-Perot interferometric (IFPI) optical fiber sensors, which have low reflectance and low power loss, are good candidates for multiplexed sensors networks. Partial reflectors are constructed by irradiating photosensitive fiber with a UV laser beam. A pair of reflectors will form a Fabry-Perot interferometer that can be used for temperature and strain sensing. A sensor fabrication system based on a pulsed excimer laser and a shadow mask is developed. A spectrum-based measurement system is presented to measure the interference fringes of IFPI sensors. A swept coherent light source is used as the light source. The spectral responses of the IFPI sensors at different wavelengths are measured. A frequency division multiplexing (FDM) scheme is proposed. Multiple sensors with different optical path differences (OPD) have different sub-carrier frequencies in the measured spectrum of the IFPI sensors. The multiplexing capacity of the sensor system and the crosstalk between sensors are analyzed. Frequency estimation based digital signal processing algorithms are developed to determine the absolute OPDs of the IFPI sensors. Digital filters are used to select individual frequency components and filter out the noise. The frequency and phase of the filtered signal are estimated by means of peak finding and phase linear regression methods. The performance of the signal processing algorithms is analyzed. Experimental results for temperature and strain measurement are demonstrated. The discrimination of the temperature and strain cross sensitivity is investigated. Experimental results show that UV-induced IFPI sensors in a FDM scheme have good measurement accuracy for temperature and strain sensing and potentially have a large multiplexing capacity. / Ph. D.

In the current mechanistic-empirical (M-E) design procedures for flexible pavements, the primary transfer functions are those that relate (a) maximum tensile strain in the hot-mix asphalt (HMA) surface layer to fatigue cracking and (b) compressive strain at the top of the subgrade layer to rutting at the surface. These functions, called fatigue and rutting equations, are usually derived from statistically based correlations of pavement condition with observed laboratory specimen performance, full-scale road test experiments or by both methods. Hot-mix asphalt fatigue behavior is an important component of a M-E design procedure; unfortunately, most of the existing models do not reflect field fatigue behavior. This is manifested in the fact that HMA fatigue failure is achieved much faster under a laboratory setting than in a field environment. This difference has been typically accounted for by the use of a single shift factor based mainly on engineering experience. The flexible pavement portion of the Virginia Smart Road includes 12 different flexible pavement designs. Each section is approximately 100m long. The sections are instrumented with pressure cells, strain gages, time-domain reflectometry probes, thermocouples, and frost probes. The instruments were embedded as layers were built. Laboratory fatigue tests of field cores and field-mixed laboratory-compacted specimens along with measured response from the instrumented pavement sections at the Virginia Smart Road were used to quantify the differences between laboratory and field environments. Four shift factors were identified to correlate field and lab fatigue behavior: stress-state, material difference, traffic wander, and healing. Field-measured critical strains and strain energy exerted during truck loading were both used to determine the stress state shift factor. Strain measurements of truck loading distribution (wander) were used to determine the wander shift factor. Finally, results from laboratory fatigue tests on cores and laboratory compacted specimens were used to evaluated a shift factor to account for the difference in compaction procedures. While the derived shift factors utilize the measured stresses and strains at the Virginia Smart Road, calculated strains and stresses, based on appropriate pavement and loading modeling, may also be used. / Ph. D.

Low substrate regulated microaerophilic behavior (LSRMB), as measured by changes in microaerophilic band formation in semi-solid medium, was observed in several aerobic bacteria isolated from subsurface soils, Antarctic dry valley soils, an eutrophic pond, a mesophilic pond, an oligotrophic lake and activated sludge. Similar behavior was also exhibited by five Pseudomonas and two Bacillus type strains from culture collection. Isolates identified with LSRMB formed a typical band of growth below the surface of low substrate (10 mg/l of peptone, tryptone, yeast extract and glucose) semi-solid medium. Surface growth was obtained when the substrate concentration was increased (1000 mg/l of each of the above mentioned substrates). LSRMB was observed in phylogenetically disparate groups, with all the Pseudomonas and two Bacillus species testing positive for the trait. One of the Gram-negative isolates, strain VT10, was identified by phylogenetic analysis based on its 16S rDNA sequence. High 16S rDNA sequence similarity (99%) was observed with the recently discovered Pseudomonas jessenii (CIP 105274T) type strain. Strain VT10 was used as a model to examine this LSRMB, and show the relationship between oxygen stress and low-substrate growth media. The concentration of 17:0 cyclopropane fatty acid, a common stress indicator, increased 5-fold, and four additional proteins were produced when P. jessenii strain VT10 was grown at low-substrate levels and when the dissolved oxygen concentration was increased from 26 microM to 241 microM. The stress responses by P. jessenii could be due its LSRMB. This study shows that low-substrate regulated microaerophilic behavior helps some microorganisms to track the oxygen minima in their habitat and thus effectively move to an environment, which allows them to thrive. In addition to the above mentioned taxis in response to oxygen concentration, organisms may use chemotaxis to a chemical compound. Quantification of chemotaxis can be extremely difficult. To quantify chemotaxis in an easier fashion, a simplified capillary chemotaxis assay, utilizing a hypodermic needle, syringe and disposable pipette tip was developed. The method was applied to two strains of subsurface microaerophilic bacteria. Strain VT10 was chemotactically attracted toward dextrose, glycerol, and phenol, which could be used as sole carbon sources, and toward maltose, which could not be used. The deep subsurface isolate MR100 (phylogenetically related to P. mendocina) showed no tactic response to these compounds although it could use dextrose, maltose, and glycerol as carbon sources. The chemotaxis results obtained by the new method were verified by using the swarm plate assay technique. The simplified technique may be useful for routine chemotactic testing. / Ph. D.

The opportunistic pathogen Legionella is the leading cause of reported waterborne disease outbreaks in the United States. Legionella can thrive under the warm, stagnant, low-disinfectant conditions characteristic of premise (i.e., building) plumbing systems, making it challenging to identify effective interventions for its control. Copper (Cu) is a promising antimicrobial that can be dosed directly to water via copper-silver ionization systems or released naturally via corrosion of Cu pipes to help control growth of Legionella and other pathogens. However, prior research has shown that Cu does not always reliably control Legionella and sometimes seems to even stimulate its growth. A deeper understanding of the mechanistic effects of Cu on Legionella, at both pure-culture and real-world scales, is critical in order to inform effective controls for Legionella. The overarching objective of the research embodied by this dissertation was aimed at elucidating the chemical and microbial interactions in premise plumbing that govern efficacy of Cu for Legionella control through a series of complementary bench-, pilot-, and field-scale studies. A critical review and synthesis of the literature identified important knowledge gaps in relation to antimicrobial effects of Cu. In particular, changes in the pH, phosphate corrosion control, and rising levels of natural organic matter (NOM) in distributed water are predicted to be important controlling factors. The type of sacrificial anode rod material employed in water heaters was also identified as an underappreciated factor, which directly affects pH, evolution of hydrogen gas as a microbial nutrient, and release of metals (such as aluminum) that bind copper. Microbiological factors: including growth phase of Legionella (e.g., exponential or stationary), strain-specific Cu tolerance, background microbiome composition, and the possibility that viable but non-culturable (VBNC) Legionella might still cause human disease, were also identified as major confounding factors. These knowledge gaps are addressed from various dimensions across each chapter of the dissertation. The effects of pH, orthophosphate corrosion inhibitor concentration, and NOM were examined in bench-scale pure culture experiments over a range of conditions relevant to drinking water. Cupric ions and antimicrobial effects were drastically reduced at pH >7.5, especially in the presence of phosphate, which precipitates copper, or NOM, which complexes the Cu in a form that is less bioavailable. Chick-Watson disinfection models indicated that soluble Cu was the most robust correlate with observed Cu antimicrobial effects across a range of tested waters. This new knowledge suggests that measuring soluble rather than total Cu would be much more informative to guide practitioners in dosing. The research also demonstrated that changes in pH or orthophosphate that have been made to control corrosion over the last few decades, have significantly altered Cu chemistry in buildings, undermining antimicrobial capacity and increasing likelihood of Legionella growth. Pilot-scale experiments confirmed that soluble Cu is an effective indicator of Cu antimicrobial capacity, even in more complex environments represented by realistic hot water plumbing systems. In particular, dosing of orthophosphate, which is widely added by drinking water utilities to control corrosion, directly reduces soluble copper and overall antimicrobial capacity. In some cases, Cu added together with orthophosphate apparently promoted the growth of Legionella, providing an example of at least one circumstance where Cu addition can induce interactive effects that elevate Legionella compared to a control system with trace Cu. It was also demonstrated for the first time that different water heater sacrificial anode types are subject to different corrosion processes, which indirectly influence Cu antimicrobial capacity. Specifically, aluminum ions released from aluminum anode corrosion at 1 mg/L can form an Al(OH)3 gel, which can remove >80% of the soluble Cu from water and reduce Cu antimicrobial effects by >2-log at pH=7. Corrosion from magnesium anodes was found to dramatically increase the pH from 6.8 to >8, which correspondingly reduces Cu antimicrobial capacity. Cu deposition further increased the anode corrosion rate and promoted evolution of hydrogen gas, which is a potent electron donor that stimulates autotrophic microbial growth especially with a magnesium anode. Electric powered anodes did not release metals or alter pH and thus did not diminish Cu antimicrobial capacity. Still, across the pilot-scale experiments, even very high levels of Cu (>1.2 mg/L) at low pH (<7) failed to fully eradicate culturable Legionella. The much lower than expected antimicrobial efficacy of Cu in the pilot-scale hot water plumbing systems was found to be partially explained by the properties of the strain that colonized the systems. Based on fitting the data to a Chick-Watson disinfection model, the outbreak-associated strain that was inoculated into the systems was estimated to be 7 times more tolerant to Cu compared to the common lab strain applied in the bench-scale tests. Further, exponential growth phase L. pneumophila were found to be 2.5 times more susceptible to Cu relative to early stationary phase cultures. It is important to also recognize that, in the pilot-scale systems, drinking water biofilms and the amoeba hosts that colonize them can further shield Legionella from the antimicrobial effects of Cu. Application of shotgun metagenomic sequencing offered the opportunity to more deeply examine the response of Legionella and other pathogens to Cu dosed to the pilot-scale hot water systems in the context of the broader microbiome. It was found that metagenomic analysis provided a sensitive indication of the bioavailability of Cu to the broader microbial community inhabiting the hot water systems, further confirming that the outbreak-associated strain of Legionella that colonized the rigs was relatively tolerant of Cu. Functional gene analysis provided further insight into the mechanistic action of Cu, suggesting multi-modal action of both membrane damage and interruption of nucleic acid replication. The metagenomic analysis further revealed that protozoan host numbers tended to increase in the pilot-scale systems with time, and this could also increase the potential for Legionella proliferation with time. Additional pure culture studies aiming to further assess the mechanistic action of Cu provided strong evidence that Cu can induce a VBNC state for Legionella. This is a concern, given that other studies have indicated that VBNC Legionella are still capable of causing legionellosis. However, VBNC cells are not detected by conventional culturing. Multiple lines of evidence supported the conclusion that Cu induced a VBNC state for Legionella, including membrane integrity, enzyme activity, ATP generation, and Amoebae resuscitation assays applied to two different strains of L. pneumophila. After exposure to Cu, up to a 5-log (99.999%) reduction in culturable Legionella was observed, whereas corresponding reductions in the various viability measures were only by <1-log (90%). In other words, conventional culturing may miss up to 99.99% of the Legionella that is still capable of causing disease. To our knowledge, this is the first study that has assessed the potential for Cu-induced VBNC Legionella. Additional research is needed to further quantify the contribution of VBNC status to challenges in effective Cu-based control of Legionella in premise plumbing. This research further examines, for the first time, the proteomic response of Legionella to Cu, comparing both presumably VBNC and culturable cells. Functional annotation of proteins that were differentially produced by the cells in response to Cu addition revealed that VBNC L. pneumophila modulated its proteome to favor cell membrane- and motility-related proteins, while reducing production of other proteins related to primary metabolism compared to culturable cells. These observations are consistent with the metagenomic-based observations and support the hypothesis that Cu inactivates cells by damaging the cell membrane. The findings also confirmed reduced general cell metabolism that is characteristic of a VBNC state. This dissertation highlights the important and complex effects of Cu on Legionella growth in potable water systems as modified by water chemistry, water heater anode type, characteristics of the surrounding microbiome, and Legionella strain characteristics and growth status. The findings raise important questions about how to measure disinfectant efficacy and provide fundamental new knowledge that can help to better optimize the application of Cu as an antimicrobial to drinking water systems and better protect public health. / Doctor of Philosophy / The opportunistic pathogen Legionella is the leading cause of reportable waterborne disease outbreaks in the United States. Legionella is capable of growing in drinking water plumbing systems in homes, hospitals, hotels, and other buildings. Legionella is spread by inhaling tiny droplets of water that are suspended in the air when using the water, for example when showering, resulting in a severe and deadly form of pneumonia called Legionnaires' Disease. Copper is a promising antimicrobial that can be dosed directly into a building's water system by installing a copper-silver ionization system. There is also interest in understanding whether copper released naturally from copper pipes could help control Legionella. However, prior research indicates that copper sometimes inhibits, sometimes has no effect, and sometimes even seems to stimulate Legionella growth. The purpose of this dissertation was to better understand how the chemical properties of the drinking water, such as pH, presence of corrosion inhibitors that are commonly added to the water by utilities, and natural organic matter impact the ability of copper to kill Legionella. Impacts of the design of the drinking water system were also examined, for example, the material used in the anodes of water heaters to prevent corrosive damage to other system components was hypothesized to change the water chemistry in such a way that could also interfere with copper disinfection. Finally, the effect of the strain of Legionella, its growth phase (exponential or stationary), and culturability status (culturable versus viable but non-culturable) was also examined. Experiments were conducted over a wide range of conditions, from bench-scale pure culture experiments of a few days to full-scale plumbing systems over a period of 3.5 years. The complementary approaches maximize the strength of scientific conclusions about approaches that can more effectively control Legionella. Several discoveries were made as a result of this research that can help to improve the use of copper for controlling Legionella in drinking water systems. In particular, it was found that it is best to keep the pH less than 7.5, because above pH 7.5 copper reacts with orthophosphate corrosion inhibitor or natural organic matter in the water in a manner that makes it less potent to microbes. Through disinfection modeling it was found that soluble copper was the best predictor of the ability to kill Legionella. Therefore, it is recommended from this research that practitioners should monitor soluble copper instead of total copper for the purpose of assessing Legionella control. From the pilot-scale experiments, it was further found that the type of anode installed in the water heater can affect the ability of copper to kill Legionella. Magnesium anodes performed the worst, likely because they raised the pH above the recommended level of 7.5. Aluminum anodes were also a problem because aluminum ions released form an aluminum hydroxide gel that can remove more than 80% of the soluble copper from water. Electric powered anodes did not reduce copper antimicrobial effects by raising pH or forming a gel, but they are much less commonly used. A surprising finding throughout this study was that very high levels of copper (>1.2 mg/L) were required to measurably reduce Legionella in the pilot-scale systems. In the pure culture experiments, it was found that the outbreak-associated strain from Quincy, IL, that was inoculated into the system was highly copper tolerant. This demonstrated that the strain of Legionella that colonizes a particular drinking water system could be the reason why copper is sometimes less effective. Pure culture experiments also found that stationary phase Legionella are more difficult to kill than exponential phase Legionella, which could explain some discrepancies among lab studies reported in the literature. A particularly noteworthy discovery of this research was that copper can make it appear as if Legionella have been killed, because the traditional culture media indicate that there is no growth on the Petri dish; however, they are in fact still alive and capable of causing human disease. This is referred to as a "viable but non-culturable (VBNC)" state. The VBNC state of Legionella was confirmed using an array of techniques (membrane integrity, enzyme activity, ATP generation, and amoebae resuscitation) for two strains of L. pneumophila. We also examined how VBNC Legionella cellular functions were impacted by copper using whole cell proteome, i.e., analysis of all of the proteins extracted from Legionella. Copper induced VBNC Legionella modulated its proteome to favor cell membrane and motility related proteins, and reduced others related to primary metabolism compared with culturable cells. These results were consistent with those obtained via shotgun metagenomic analysis of the microbial community DNA in the pilot-scale water systems. Given the potential for VBNC organisms to prevail in systems disinfected with copper, it is recommended to supplement culture-based monitoring with molecular-based monitoring, e.g., with quantitative polymerase chain reaction. This dissertation highlights the important and complex effects of copper on Legionella growth in potable water systems. The findings help to inform guidance on how to improve the antimicrobial effect of copper, through adjusting the water chemistry, selecting appropriate water heater anodes, and optimizing the overall hot water system design. The dissertation also helps to inform improved strategies for monitoring the efficacy of copper for killing Legionella in real-world systems. Overall, the findings can help to improve policy and practice aimed at reducing the incidence of Legionnaires' Disease and protecting public health.

Although bond-normal stresses have been shown to be responsible for the failure of most laboratory adhesive joint geometries, the measurement of these stresses has been accomplished only through the use of very sophisticated optical techniques. In order to develop a more versatile measurement technique, poly(vinylidene fluoride) film was used to develop piezoelectric stress sensors. The sensitivities of the film to normal stresses in the three principal material directions of the orthotropic film were accurately measured using a charge amplifier and a storage oscilloscope. These measured sensitivities comprised the calibration constants of the film. In order to reduce the detrimental effect on bond strength caused by embedding the low surface energy film into adhesive bondlines, surface treatment methods were investigated using contact angle studies, XPS analysis and 1800 peel and tapered double cantilever beam adhesion specimens. An acid etch using a mixture of acetic, phosphoric and nitric acids was found to greatly improve the bond strengths to an epoxy adhesive without reducing the piezoelectric activity of the film. The bond-normal stresses in both the elastomeric butt joint and the single lap shear joint were measured using the developed stress sensors. Comparison of the measured stresses with calculated values obtained from closed-form analytical solutions and finite element analysis for the stresses was excellent. The piezoelectric sensors do have several important limitations. The piezoelectric activity of the film is lost at temperatures above 100°C (210°F). Also, the sensors are only sensitive to dynamic loads. Nonetheless, the sensors provide an accurate means of measuring peel stresses in many adhesive joints of practical interest. / Ph. D.

We use molecular mechanics (MM) simulations with the tight-binding (TB) potential to study local and global instabilities in initially defect-free finite specimens of gold crystals deformed in shear, simple shear, tension/compression, simple tension/compression, and triaxial tension/compression. The criteria used to delineate local instabilities in a system include the following: (i) a second order spatial derivative of the displacement field having large values relative to its average value in the body, (ii) the minimum eigenvalue of the Hessian of the potential energy of an atom becoming nonpositive, (iii) and structural changes represented by a high value of the common neighborhood parameter. A specimen becomes globally unstable when its potential energy decreases significantly with a small increase in its deformations. It is found that the three criteria for local instability are satisfied essentially simultaneously at the same atomic position. Deformations of a specimen are quite different when it is deformed with some bounding surfaces free from external forces as opposed to essential boundary conditions prescribed on all bounding surfaces. It is found that the initial unloaded configuration (or the reference configuration) of the minimum potential energy has significant in-plane stresses on the bounding surfaces and nonzero normal stresses at interior points. In tensile/compressive deformations of a rectangular prismatic nanobar the yield stress defined as the average axial stress when the average axial stress vs. the average axial strain curve exhibits a sharp discontinuity depends upon the specimen size; a similar result holds for simulations of shear deformations. Specimens deformed with essential boundary conditions on all bounding surfaces experience instabilities at a higher value of the average strain than identical specimens deformed similarly but with one or more pairs of opposite bounding surfaces traction free. For the former set of deformations, the response of a specimen prior to the onset of instability is the same as that of a hyperelastic body with the strain energy derived from the TB potential and deformations obeying the Cauchy-Born rule. Specimens with some traction free bounding surfaces experience local instabilities prior to the onset of a global instability but the two instabilities occur simultaneously in specimens with essential boundary conditions prescribed on all bounding surfaces. It is believed that because of residual stresses in the reference configuration, the average axial stress at yield in compression is nearly one-half of that in tension. / Ph. D.

Brucella abortus is a zoonotic agent that primarily infects cattle and causes brucellosis. B. abortus strain RB51 is a live, attenuated vaccine licensed for cattle. However, there is no available vaccine to prevent human brucellosis. Outer membrane vesicles have been tested as potential vaccines to prevent diseases caused by bacterial species. OMV are constantly released from Gram-negative bacteria. They are comprised principally of the outer membrane components and periplasmic proteins from the bacterial cell envelope. The research in this thesis examined the adjuvant property of non-replicative, metabolically active irradiated strain RB51 and the protective ability of OMV derived from strain RB51. Irradiated B. abortus strain RB51 was assessed for its ability to act as an adjuvant to induce protection against malaria. It was found that irradiated B. abortus strain RB51 administered along with fasciclin related adhesive protein (FRAP) to mice induced a protective immune response and a significant decrease in parasitemia after challenge with Plasmodium berghei. Strain RB51 and strain RB51 over-producing Cu/Zn superoxide dismutase (Cu/Zn SOD) were used to produce OMV. Western blotting and SDS-PAGE gel staining confirmed the presence of OMV and the over-production of Cu/Zn SOD. OMV were delivered to mice using an intraperitoneal route and, in some cases, with aluminum hydroxide adjuvant. The immune response was assessed by antibody isotyping with respect to OMV and measuring splenic clearance (i.e. protection) from a B. abortus strain 2308 challenge. The results demonstrate that OMV from B. abortus strain RB51 or strain RB51 over producing Cu/Zn SOD produced a Th1 polarized immune response as measured by specific OMV antibodies and cytokines but no statistically significant protection was observed. / Master of Science

The split Hopkinson bar test is the most commonly used method for determining material properties at high rates of strain. The theory governing the specifics of Hopkinson bar testing has been around for decades. It has only been the last decade or so, however, that significant data processing advancements have been made. It is the intent of this thesis to offer the insight of its author towards new advancements. The split Hopkinson bar apparatus consists of two long slender bars that sandwich a short cylindrical specimen between them. By striking the end of a bar, a compressive stress wave is generated that immediately begins to traverse towards the specimen. Upon arrival at the specimen, the wave partially reflects back towards the impact end. The remainder of the wave transmits through the specimen and into the second bar, causing irreversible plastic deformation in the specimen. It is shown that the reflected and transmitted waves are proportional to the specimen's strain rate and stress, respectively. Specimen strain can be determined by integrating the strain rate. By monitoring the strains in the two bars, specimen stress-strain properties can be calculated. Several factors influence the accuracy of the results, including longitudinal wave dispersion, impedance mismatch of the bars with the specimens, and transducer properties, among others. A particular area of advancement is a new technique to determine the bars dispersive nature, and hence reducing the distorting effects. By implementing numerical procedures, precise alignment of the strain pulses is facilitated. It is shown that by choosing specimen dimensions based on their impedance, the transmitted stress signal-to-noise ratio can be improved by as much as 25dB. An in depth discussion of realistic expectations of strain gages is presented, along with closed form solutions validating any claims. The effect of windowing on the actual strains is developed by analyzing the convolution of a rectangular window with the impact pulse. The thesis concludes with a statistical evaluation of test results. Several recommendations are then made for pursuing new areas of continual research. / Master of Science