Biofilms are highly organized bacterial structures that are attached to a surface. They are ubiquitous in nature and may be detrimental, causing numerous types of illnesses in living organisms. Biofilms in the human oral cavity are the main cause of dental caries and periodontal diseases and can act as a source for pathogenic organisms to spread within the body and cause various types of systemic diseases. Streptococcus mutans is the primary etiological agent of dental caries, the single most chronic childhood disease. In many cases, quorum sensing (QS) is required for initial formation and subsequent development of biofilms and the signaling molecule autoinducer 2 (AI- 2) has been well studied as an inter-species QS signaling molecule. However, recent reports also suggest that AI-2-mediated signaling is important for intra-species biofilm formation in both Gram-negative and positive bacteria. Therefore, there is significant interest in understanding the role of different QS signals such as AI-2 in oral biofilm formation. Microfluidic devices provide biomimetic environments and offer a simple method for executing multiple stimuli experiments simultaneously, thus, can be an extremely powerful tool in the study of QS in biofilms. In this study, we report conditions that support the development of S. mutans biofilms in microchannel microfluidic devices, and the effects of extracellular addition of chemically synthesized (S)-4,5-dihydroxy-2,3-pentanedione (DPD; precursor of AI-2) on mono-species S. mutans luxS (AI-2 deficient strain) biofilm formation using a gradient generating microfluidic device. S. mutans wild type (WT) and luxS biofilms were developed in nutrient rich medium (25% brain heart infusion medium, BHI + 1% sucrose) for up to 48 h. Maximum biofilm formation with both strains was observed after 24 h, with distinct structure and organization. No changes in S. mutans luxS biofilm growth or structure were observed upon exposure to different concentrations of AI-2 in a gradient generating device (0 to 5 M). These results were also validated by using a standard 96-well plate assay and by verifying the uptake of AI-2 by S. mutans luxS. Our data suggest that extracellular addition of AI-2 does not complement the luxS deletion in S. mutans with respect to biofilm formation.

Autoinducer 2 (AI-2) molecules produced by bacterial cells are thought to be involved in controlling a variety of bacterial cellular processes by coordinated gene and protein expression. Previous work in our laboratory has shown that ground beef contains compounds that can interfere with AI-2-mediated bioluminescence expression in Vibrio. harveyi. The underlying hypothesis of this work was that AI-2 molecules affect the protein expression in Escherichia coli O157:H7 and AI-2 inhibitory molecules negate the influence of AI-2 molecules. The main objectives of this study were to identify, characterize, and isolate the factors responsible for inhibition of AI-2 molecules from ground beef extracts, elucidate the role of LuxS/AI-2 cell signaling system in E. coli O157:H7 protein expression, and determine if inhibitory factors present in ground beef extract can negate the influence of AI-2 molecules on the protein expression. Using a solvent extraction procedure and gas chromatography analysis, AI-2 inhibitory factors present in ground beef extracts were identified as both medium and long chain fatty acids. When identified fatty acids were tested at different concentrations for AI-2 inhibition, AI-2 inhibition ranging from 25% to 90% was observed. Both ground beef extracts and mixture of selected fatty acids also resulted in 2- to 4-fold reduced AI-2 influenced biofilm formation by E. coli K12 cells. Identification of LuxS/AI-2-mediated protein expression in E. coli O157:H7 was conducted using two dimensional gel electrophoresis. Protein expression analysis showed that the LuxS/AI-2 system modulates the expression of proteins involved in different cellular processes such as carbohydrate and amino acid metabolism, stress response, and formation of flagella and motility. When AI-2 inhibitory factors were added along with AI-2 molecules, the expression patterns of three AI-2-influenced proteins (GlmS, SpeE, and NikA) were changed suggesting that AI-2 inhibitors can negate the influence of AI-2 molecules on protein expression of selected proteins. Collectively, these results highlight that proteins associated with different cellular processes in E. coli O157:H7 can be modulated depending on whether cells are in contact with AI-2 molecules in the presence or absence of AI-2 inhibitory factors.

From Jimmy Carter’s self-identification as a “born again Christian” in the 1976 presidential campaign to George W. Bush’s declaration of “Christ” as his favorite political philosopher “because he changed my heart” in a Republican primary debate of the 2000 campaign, presidential speeches and campaigns are often laced with religious language. Such an observation is nothing new. However, many scholars and political observers do not know what to make of such religious references. Such language is often dismissed as either shameless pandering to religious constituencies or something hopelessly out of place in American politics. This dissertation attempts a deeper analysis of this controversial subject by identifying how presidents use the rhetorical resources of religion by employing religious argument patterns stemming from the Jewish and Christian religious traditions in presidential speeches. Specifically, this dissertation explores how the last five presidents (Jimmy Carter through George W. Bush) have used such religious rhetorical forms in attempts to strike a symbolic chord within the larger American public. The religious rhetorical forms explored herein, if employed judiciously, can serve as political shibboleths—or passwords—which indicate a basic level of identification with the public thanks to the basic elements, such as transformation, atonement, and renewal, which comprise the mythical core of these forms.

A new synthetic method toward 5-substituted isoxazolidines by [3 plus 2] cycloaddition of nitrones generated from nitrosobenzene and styrene was discovered. The formation of nitrones from nitrosobenzene and mono-substituted aromatic styrenes was demonstrated. The cycloaddition reactions between styrenes and nitrosobenzenes work well when a moderate excess of styrenes was employed. The labeling studies support that cleavage of the styrene double bond occurred and accounted for all the carbons in the starting materials and products. A [3 plus 2] dipolar cycloaddition is implicated by the available mechanistic data and allows for the rapid assembly of various substituted isoxazolidines directly from nitrosobenzenes, electron deficient alkenes, and styrene.

The existing 3-stage research turbine at Turbomachinery Performance and Flow Research Laboratory (TPFL) facility, Texas A & M University (TAMU) was replaced with a newly designed and manufactured 2-stage turbine in accordance with the design requirements as per DooSan, DHI. This new design of turbine consisted of bowed stator and rotor blades to study the effect on reduction of secondary ow losses and thus improvement in turbine efficiency if any. The new design also incorporated labyrinth seals on both inner and outer shrouds. Extensive Inter-stage and Performance experiments were carried out on this new turbine. Inter-stage measurements were accomplished by traversing three 5-hole probes radially and circumferentially, using the existing probe traverse system in TPFL. Performance tests were conducted for varying pressure ratio, at fixed rotational speed and for varying rotational speed with fixed pressure ratio and the efficiency was plotted against u/c_0. Each condition was tested and measured two to three times to check for reproducibility of the data. The results from inter-stage experiments show that the rotor row loss coefficient is about four times higher than the stator row loss coefficient. This high rotor loss coefficient reduces the total to static efficiency. From the performance tests, the maximum total-to-static efficiency observed was 85.2 percent located at around u/c_0 = 0.75. This relatively low efficiency is in consonance with the inter-stage results (high rotor loss coefficient).

To support the transmission of real-time multimedia stream, Stream Control Transmission Protocol (SCTP) developed by IETF is considered to be more efficient because of its high-degree expandability and compatibility. Today we can observe that instead of using SCTP may become the transmission protocol of next-generation IP network. In this Thesis, we propose a mechanism to upgrade TCP and UDP, the multi-home feature of SCTP to ensure that multiple paths can exist between two SCTP ends. Not only can the primary path continue to function, but the secondary paths covey part of data packets once the network congestion occurs. Considering the dynamic change of our Internet, the proposed mechanism can enhance the effectiveness of SCTP data transmission, and increase overall network utilization. Cutting user data into chunks in SCTP, we can analyze the transmission performance of individual path by measuring the transmission delay from the sender to the receiving end. By modifying the simulator of NS-2, we set up different topologies in the experiment to analyze the performance of our mechanism. We compare the modified SCTP with the original SCTP to highlight our proposed mechanism in increasing throughput and network utilization by adjusting the background traffic on the paths.

We have developed an one-pot reaction procedure to polysubstituted pyroglutamates with three contiguous chiral centers. The results were applied to the synthetic studies toward kainic acid and lycorane.

In the latest years, many studies especially on characterization and synthesis of polyoxazolines have been made. During these studies, new polyoxazolines such as poly(2-isopropyl-2-oxazoline) (PIPOX), poly(2-(3-butenyl)-2-oxazoline) (PBOX) and modified PBOX were synthesized. However, there has been no investigation on their thermal characteristics such as thermal stability and thermal degradation products. In this study, thermal degradation characteristics, thermal degradation products and thermal stability of PIPOX, PBOX and modified PBOX polymers PBOX-Perf, PBOX-Thiop, PBOX-Sug, PBOX-SP and PBOX-TP were investigated. In this study mercaptans 1H,1H,2H,2H-perfluoro-octanethiol, 3-mercapto-1,2 propanediol, thio-&beta / -D-glucose derivative and their mixture were used in PBOX modifications. The effect of modification of PBOX with different mercaptans on thermal characteristics was also analyzed. For the PIPOX, formations of protonated monomer and oligomers from dimer to heptamer were observed. However, when the isopropyl group changes with 3-butenyl group, protonated oligomers up to trimer were observed because the crosslinking formed during the polymerization of unsaturated butenyl inhibited the production of oligomers. In addition to this, thermal degradation at lower temperatures was observed. The change in thermal stability and thermal degradation products were observed as a result of modification of PBOX with different mercaptans. Unlike PBOX-Sug thermal degradation started at very low temperatures for PBOX-Thiop and PBOX-Perf. This degradation observed at lower temperatures disappeared for PBOX-SP and PBOX-TP. For PBOX-Perf, PBOX-Sug and PBOX- Thiop, decomposition of side chains at low temperatures and decomposition of the main chain at high temperatures were observed. Although the same thermal degradation behavior for PBOX-TP and PBOX-Thiop was expected, since PBOX-TP was obtained as a result of modification of PBOX with high amounts of mercaptan used in PBOX-Thiop and small amounts of mercaptan used in the PBOX-Perf, the results show that neither PBOX-Thiop nor PBOX-Perf thermal degradation behavior are dominant. This is also valid for PBOX-SP. PBOX-SP has higher thermal stability when compared to PBOX-Sug.

The subject of this thesis is divided into two parts: (1) Treatment of 2-ethyl hexanol (2-EH) in an air stream by a pilot-scale biotrickling filter, and (2) Treatment of gaseous VOC emissions from a resin manufacturing plant by a full-scale biotrickling filter. Treatment of 2-Ethyl Hexanol in An Air Stream by A Pilot-Scale Biotrickling Filter 2-Ethyl Hexanol (2-EH) may release from the thermal breakdown of di-isooctyl phthalate (DOP), a commonly-used plasticizer, in the curing stage when manufacturing PVC synthetic leather and gloves. This paper reports the results of studies using a biotrickling filter (BTF) with blast-furnace slag packings (sizes = 2-4 cm and specific surface area = 120 m2/m3) for treatment of 2-EH in an air stream. The experimental setup consisted of a set of two-stage-in-series biotrickling filters. Each stage of the biotrickling filter was constructed from a 19.5-cm x 200-cm (ID x H) acrylic column packed with slags of 125 cm in height. The operation started with the conditions of recirculation liquid pH = 8.0 and rate (VL) = 8.83 m3/m2.h, a steady nutrient (ammonia nitrogen and phosphate phosphorus) addition, and without a special microbial seeding. Results indicate that, yellowish-brown biofilms on the surface of packing slags could be observed in one week and well developed in two weeks after the start-up operation. The effects of volumetric 2-EH loading (L) and superficial gas velocity (U0) on the 2-EH elimination capacity (K) and the removal efficiency (K/L) were tested. Long-term experimental results show that, in the conditions of influent 2-EH concentration C0 = 250 mg/m3, U0 = 162 m3/m2.h, and gas empty-bed-retention time EBRT = 55 s, K/L could be correlated by the equation K/L = 71.9/(72.4+L) with a correlation coefficient (R) of 0.9988. The 2-EH elimination rate was mass-transfer controlled when L<16 g/m3.h and reaction-controlled when L>16 g/m3.h. Results also indicate that nutrient addition and liquid recirculation were important for the normal operation of the BTF in eliminating the influent 2-EH. Treatment of Gaseous VOC Emissions from A Resin-Manufacturing Plant by A Full-Scale Biotrickling Filter A resin and chemical company located in Tainan County, Taiwan engages in the manufacture of PU (poly urethane), PVAC (poly vinyl acetate), PS (poly styrene), and PMMA (poly methyl methacrylate) resins from various chemical stocks. Gaseous volatile organic compounds (VOCs) emitted from the reactors include toluene, methyl ethyl ketone (MEK), acetone, vinyl chloride, styrene, butyl acetate, 2-ethyl hydroxyl acetate, and methyl methacrylate. These VOCs should be properly eliminated before discharging the reactor vents to the atmosphere. This paper reports the performance results of using a biotrickling filter (BTF) with wood packings (sizes = 2-12 cm and specific surface area = 97 m2/m3) for treating the reactor vents with a total flowrate of 80 m3/min at 20-30¢J. The BTF was constructed from a 7.0 m x 6.0 m (ID x H) SUS 304 column with wood packings of 4.0 m in height. The operation started with the conditions of recirculation liquid pH = 7.0-8.0 and rate (VL) = 1.56 m3/m2.h, a steady nutrient (urea and phosphate phosphorus) addition, and without a special microbial seeding. Results indicate that, yellowish-brown biofilms on the surface of packings could be observed in one week and well developed in two weeks after the start-up operation. Long-term operation results show that, in the conditions of influent VOC concentration C0 = 200-10000 ppm (expressed in terms of methane), U0 = 125 m3/m2.h, and gas empty-bed-retention time EBRT = 115 s, K/L could be correlated by the equation K/L = 345/(467+L) with a correlation coefficient (R) of 0.9913. The VOC elimination rate was mass-transfer limited when L<45 g/m3.h, with the mass of VOCs expressed as that of methane. Results also indicate that the liquid recirculation might be interrupted for a hour without influencing the performance. Toluene was the most difficult one to eliminate among the VOCs in the gas stream.

Adiposity has been shown to secrete bioactive cytokines and growth factor known as adipocytokines, they can contribute to obesity, diabetes and complications of diabetes. Visfatin is a novel adipocytokine, and it was shown to exert insulin-mimetic effects in stimulating glucose transport and induced triglyceride accumulation in preadipocytes and triglyceride synthesis from gluvose. Visfatin plasma levels are increased in morbid obesity and type 2 diabetes mellitus. These finding indicate that visfatin may play a role in the association between visceral obesity and increased metabolic risk, visfatin gene suggested that genetic variation in the visfatin gene may, indeed, have a minor effect on visceral and subcutaneous visfatin messenger RNA expression profiles and parameters of glucose and insulin metabolism. In this study, we explored the relationships between the plasma level of visfatin and genetic single nucleotide polymorphisms (SNPs) of visfatin gene in type 2 diabetes mellitus (T2DM) with and without macrovascular disease. Plasma visfatin was found to be elevated significantly in T2DM with macrovascular disease patients. Moreover, waist to hip ratio was independently associated with plasma visfatin level. There were statistically significant differences in visfatin -948 G/T genetic variants distribution between T2DM with macrovascular disease and the T2DM control group. The visfatin -948 G/T heterozygotes showed higher mean high-density lipoprotein cholesterol than the carriers of the G allele. The results of the current study indicated that plasma visfatin levels were associated with macrovascular complications in type 2 diabetes. However, the definite roles of visfatin in the pathogenesis of insulin resistance, glucose and lipid metabolism are unclear. The observation of changes in the plasma concentrations of visfatin seen in T2DM and T2DM with macrovascular diseases may exert beneficial effects in understanding roles of visfatin in physiologic activity and metabolic disorder. Further studies are needed to elucidate the mechanisms behind visfatin overexpression in humans.