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INTERACTIONS OF HYDROXYLAMINES, ALDOXIMES AND NITRIC OXIDE WITH THE GROUP 8 & 9 METALS USING HEME AND NON-HEME MODELS
No full textThis dissertation investigates the interactions of biologically relevant small molecules, specifically hydroxylamines (RNHOH), aldoximes (RCH=NOH), and nitric oxide (NO), with metalloporphyrins containing iron (Fe), cobalt (Co), and rhodium (Rh) by employing a combination of experimental and computational techniques, including X-ray crystallography, IR and NMR spectroscopy, and density functional theory (DFT) calculations. This work aims to elucidate the structural and electronic factors that govern these interactions and their implications for biochemical processes observed in nature.
Chapter 1 provides a brief introduction to the significance of the interactions of hydroxylamines, aldoximes, and nitric oxide with heme-containing enzymes, such as cytochrome P450 and cytochrome P460. These interactions are crucial for essential biological processes, such as drug metabolism, detoxification, and nitrogen cycling. I set the stage for the detailed studies presented in the subsequent chapters, focusing on the fundamental chemistry of these interactions and their implications in bioinorganic chemistry.
Chapter 2 examines the role of a previously unrecognized internal H-bond interaction between a hydroxylamine RNHO–H group and porphyrin N-atoms of the (TPP)Fe(AmphNHOH)(AmphNO) and (TPP)Co(AmphNHOH) complexes using DFT calculations. This chapter provides new insights on heme-mediated hydroxylamine activation in the absence of a distal pocket. The DFT calculations show that the conformations with the internal H-bond represent global minima along the potential energy surfaces for both the Fe and Co heme models, confirming that the observed internal H-bond is an intrinsic feature of the complexes and not due to crystal packing effects. The natural bond orbital (NBO) analyses reveal a donor π (porN=C) to acceptor σ* (O-H) interaction of 3.04 kcal/mol for Fe, and 1.36 kcal/mol for Co. These results are consistent with a unique heme-based activation that weakens the hydroxyl O–H bond, thereby facilitating the conversion to its nitroso derivative in the Fe case. In contrast, the Co complex exhibits less π-to-σ* interaction energy, resulting in a lower O–H activation. This difference helps explain the experimentally observed conversion from Fe-AmphNHOH to its nitroso derivative Fe-AmphNO, and the increased stability of the Co–AmphNHOH adduct. Additionally, I extend these computational studies to the parent hydroxylamine (NH2OH). The DFT calculations on ferrous and ferric heme models with NH2OH also reveal the presence of internal H-bonds between hydroxylamine (R/H)NHOH moieties and heme N-atoms, suggesting that this feature might be more common than previously recognized.
Chapter 3 centers on the binding and activation of hydroxylamines and aldoximes with Group 9 metals, specifically cobalt and rhodium, using both heme and non-heme models. It examines whether the intramolecular H-bonds observed in alkylhydroxylamine heme derivatives with first-row transition metals (Chapter 2) could also occur in arylhydroxylamine and aldoximes derivatives with second-row transition metals. Additionally, I explore whether this internal hydrogen bonding is a unique characteristic of heme systems or if it could also occur in other nitrogen-containing molecules, such as those in non-heme models. In this chapter, the preparation, crystal structures, spectroscopic characterizations (IR and NMR), and DFT calculations of various cobalt and rhodium complexes with hydroxylamine and aldoxime adducts are presented. The crystal structure of (TPP)Rh(PhNHOH)(C6H4Cl) reveals, in addition to N-binding of PhNHOH to Rh, the presence of an intramolecular H-bond between the hydroxylamine –OH proton and a porphyrin N-atom. In contrast, the crystal structures of (TPP)Co(RCH=NOH)Cl (R = butylaldoxime, benzaldoxime) exhibit two intramolecular H-bonds between the oxime =N-OH and the methine -C(H)=N-OH protons with porphyrin N-atoms; these internal H-bonds were not observed in the Rh derivative (TPP)Rh(CH3(CH2)2CH=NOH)(C6H4Cl-p). While DFT calculations predict the presence of similar intramolecular H-bond interactions in the related aldoxime complexes (TPP)Rh(RCH=NOH)(C6H4Cl) (e.g., R = formaldoxime, butyraldoxime) in their global minima structures, the X-ray crystal structure obtained for the (TPP)Rh(CH3(CH2)2CH=NOH)(C6H4Cl-p) complex is consistent with the local (non-global) minima conformation. Direct comparison of the non-porphyrin cobalt complexes oxime adducts with their porphyrin analogues is also presented. The X-ray crystal structures of (Me2bpbMe2)Co(RCH=NOH)(H2O) (R = butylaldoxime, benzaldoxime) reveal that the NOH protons are not involved in internal H-bonding with the N4-chelate. I show that the π-to-σ* interaction contributes to the overall binding of RCH=NOH to the cobalt centers as evidenced by the experimental H-down conformations in the porphyrin systems but not in the bpb complexes.
Chapter 4 explores the reactivity of nitric oxide (NO) with a rhodium porphyrin complex in a solid crystal and in solution. A combination of spectroscopic techniques (e.g., IR, UV-vis, NMR), X-ray crystallography, and computational methods employed, and the results discussed. A notable gap in the existing literature is the lack of comprehensive studies on NO insertion into metal-carbon bonds of metalloporphyrin complexes. Previous work in our laboratory revealed a unique NO insertion in a crystalline rhodium porphyrin complex, but the reproducibility and detailed mechanistic understanding remain elusive. In this chapter, I re-examine the preliminary results where crystals of (TPP)Rh(C6H4Cl) are exposed to NO gas. The X-ray analysis reveals the formation of an NO-inserted product, (TPP)Rh(ONC6H4Cl-o) alongside with the unreacted (TPP)Rh(C6H4Cl-p). This finding suggests a specific reactivity pattern depending on the isomeric form of the chlorophenyl ligand. Advanced 1H NMR spectroscopic techniques (1D TOCSY) show a mixture of para, meta, and ortho Cl-isomers present in the bulk sample (TPP)Rh(C6H4Cl). DFT calculations confirm that the ortho-Cl isomer exhibits a longer Rh-C bond and higher relative energy, making it more susceptible to NO insertion. The freezing string calculation for the NO insertion pathway identifies a transition state with significant elongation of the Rh-C bond that is primed for the formation of a new Rh-N bond. The NPA charge analysis indicates electronic rearrangements favoring the NO-insertion process. Molecular orbital analysis highlights specific σ interactions that stabilize the transition state and product.
When (TPP)Rh(C6H4Cl) reacts with NO gas in solution, 1H NMR, IR and UV-vis spectroscopy indicate the formation of various Rh-NO adducts. However, there is no clear evidence of NO insertion; instead, a Rh-C bond cleavage occurs, leading to the formation of new C-N bonds (e.g., O2NC6H4Cl-p). This chapter provides new insights into the reactivity of NO with metalloporphyrin complexes and underscores the importance of reaction medium and crystal morphology in determining reaction pathways and products
Three Essays on Political Economy and Policy
Get PDFThe first chapter of this dissertation studies how campaign contribution laws affect welfare policies. The US political system is highly unequal as policy preferences of high-income citizens are often prioritized compared to low-income groups. It is also widely believed that interest groups employ campaign contributions to exercise bargaining power over political candidates. Evidence shows that stricter campaign contribution laws can reduce the bargaining power of interest groups over candidates and increase the say of low-income groups in policy matters. Thus, the effect of stricter contribution laws should also manifest as a shift towards relatively generous welfare policies. This paper analyzes the relationship between stricter campaign contribution laws and welfare policy across the state-wide legislative races from 1980 to 2018. The empirical results indicate that stricter contribution laws increase state real minimum wage and EITC rates. The effect of relatively stringent laws on welfare policy generosity is also evident when alternative welfare policy proxies are used.
The second chapter investigates how the political ideology of governments, specifically left-right partisanship, affects their decisions to enter into International Monetary Fund (IMF) loan programs and the conditionality requirements attached therein. Additionally, it explores how IMF programs and their conditionality requirements influence the ruling government's political ideology. Using an instrumental variable approach to address the endogeneity of IMF programs and conditions, the empirical analysis reveals that left-wing governments are less likely than right-wing governments to enter into IMF programs, while no significant effect is observed for centrist governments. However, left-leaning governments encounter fewer overall conditionality requirements compared to right-wing ones. The findings also indicate that the presence of an IMF program and a higher burden of conditionality requirements decrease the likelihood of left-wing or centrist parties winning or retaining public office, whereas they increase the probability of a right-wing party gaining power.
The third chapter analyzes the effect of left-wing, right-wing, and centrist political ideologies on productive capabilities across countries. Productive capabilities or export sophistication is the ability of an economy to produce and export a wide variety of highly sophisticated products. It is a strong determination of long-run economic growth and development. The ideology of incumbent political parties can determine a country's policy trajectory, thereby affecting the growth process. The evidence on the effect of political ideology on economic performance is mixed and inconclusive. The two-stage least-squares instrumental variable estimates show that left-wing governments do not affect productive capabilities, right-wing governments are hurt, and centrist ideology boosts a country's productive capabilities in the long run
Identification of geographic and cultural ancestry through chemical analysis of latent fingerprint residues
Get PDFThe permanence and uniqueness of fingerprints and the analysis of physical characteristics associated with fingerprints have allowed for the identification of individuals in forensic investigations. However, there is additional information that may be obtained from latent fingerprints. Fingerprint residues are comprised of chemical components - those which are created and secreted from the body naturally (endogenous) and those from products outside the body that are ingested or applied on the skin (exogeneous) - that have previously been used by researchers to identify an individual's age, gender, and even lifestyle. This information may be useful for the inclusion and exclusion of suspects when physical fingerprint characteristics may be unidentifiable or may be a means of adding additional information to preexisting physical characteristic analyses. However, there is currently no scientific literature regarding the ability to identify an individual's geographic and cultural ancestry through analysis of latent fingerprint residues. The purpose of this study was to identify a chemical pattern which might allow investigators to identify an individual's geographic and cultural ancestry through the analysis of latent fingerprint residues using Mass Spectrometry - specifically Desorption Electrospray Ionization - Mass Spectrometry - as a medium for analysis. Individuals from varying racial backgrounds (Hispanic, Asian, European, African, and Middle Eastern) were asked to deposit a single right index print onto a piece of Mylar film. Following collection of prints, samples were analyzed using the DESI Synapt G2 instrument. Results of the study indicated that identification of geographic and cultural ancestry based on latent fingerprint residues may be possible, but further study is needed. In most cases, it was seen that an individual has significant agreement of chemical residues within their fingerprints. However, for individuals of the same or even different geographic and cultural ancestries, there is less definitive results as to if the chemistry of their latent print residues are similar or significantly different. In total, no distinct observations can be made from the data obtained, and further investigation is required to establish any relationships between geographic and cultural ancestries and the chemistry of fingerprint residues
Modeling Aspects of Proteins in Biologically Relevant Environments
No full textProteins and protein interactions are fundamental components of biological processes. Using molecular dynamics, the physical properties of proteins at various stages, and their association with functional or disease-causing complexes, can be probed under conditions that are difficult to investigate experimentally.
The first project presented in this work addresses the transition of the protein Serum amyloid A into a disease-causing conformation. Serum amyloid A is an acute phase protein and as such responds to trauma in the body. When incorrectly folded the protein may form amyloid fibrils which leads to severe diseases. Therefore, it is important to understand the transition from the normal to the pathological conformation. An advanced sampling technique, Replica Exchange with Tunneling (RET), was used for this purpose and it was established that there is a low energy barrier between the two forms of the protein and that the transition depends on the unfolding of the N-terminus of the protein.
The second project is motivated by the search for antibiotics. Because of its ability to form pores in membranes, nisin is pernicious to bacterial cells; however, the mechanism by which the pores are formed and are stabilized is unknown. Additionally, instability and insolubility at physiological conditions limit the broader use of the protein as an oral drug. To investigate the pore formation mechanism of nisin in bacterial cells and how the pores affect the integrity of the membranes, all atomistic molecular dynamics simulations were performed. It was determined that residues 8-28 of nisin are important for the stability of the pore and that in the presence of lipid II, a component of the bilayer that is specific to bacteria cells, the pore is more stable. The integrity of the membrane is further reduced by local changes in thickness and viscosity.
In addition to having antimicrobial properties, nisin can inhibit cancer growth but does not appear to harm healthy human cells. As cancer cell membranes do not contain the bacteria-specific lipid II, there must be different mechanisms by which nisin induces cell death in cancer and bacteria cells. The third, and yet unfinished, project compares the interaction of nisin with different types of cell membranes – bacteria, cancer, and eukaryotic cells. Furthermore, simulating nisin in membrane environments allows for a more general inquiry into the not-well-understood physical dynamics of membranes. This is a promising area for future studies
ARE WORK-BASED LEARNING OPPORTUNITIES FOR STUDENTS ASSOCIATED WITH POSITIVE PLACEMENT AND PROGRAM COMPLETION?
Get PDFCareer technical education (CTE) is undergoing a resurgence in popularity. Amid this uptick in interest, one significant area of investment is in work-based learning (WBL) opportunities for students, which encompasses many types of learning activities that range from career exploration to internships. Existing studies examine the influence of WBL on outcomes while students are attending school, but few studies have examined whether WBL is related to student success after graduation from a program of study. This quantitative study tests the relationship between WBL hours and program completion and positive placement by using administrative and survey data (n = 3,881) from a standalone career technology center school district in Oklahoma that serves high school students and adults. Results indicated that the number of work-based learning hours were not associated with either program completion or positive placement. However, the type of learning provided was associated with these outcomes as students attending programs offering learning through active experimentation were 2.5 times more likely to receive a positive placement and 1.8 times more likely to complete their programs. Abstract conceptualization was also associated with these two outcomes, but not as strongly as active experimentation was. This study offers important contributions to the literature because it offers suggestive evidence that it is not necessarily the amount of time spent in work-based learning but the types of learning opportunities that are provided that influence program completion and positive placement
NeuDrift: Reimagining Matza's Criminology for Local Situational Crime Prevention
Get PDFThe research for Drift Theory and Neutralization Theory has remained stagnant in recent decades as criminologists tend to ignore drift while focusing only on identifying unique neutralizing techniques through interviews and ethnographies. Additionally, these theories suffer from a dearth of quantitative research due to long-standing critiques concerning how to properly conduct measurement, the lack of statistical significance, the competition for explanatory power among theories, and how to include a variable for the general acceptance of deviance. I remedy these previous issues by reimagining how these theories relate to the process of deviance and crime and how quantitative neutralization measures can be condensed into two outcomes that supplement current criminological scales. The product of this process, which I term NeuDrift, should be applied to situational theories in criminology that explain how internal/external controls (self-control and social bond) are neutralized rather than acting as a competing explanation. I use a convergent parallel mixed methods model with data gathered from a convenience sample of 335 university students to confirm NeuDrift as a measurable and viable path forward in situational crime prevention. Quantitatively, I find that neutralizations do not follow a tiered pattern of predictability, which also suggests that there is an element of drift that is routinely unacknowledged in most criminological literature. Qualitatively, I find that respondent written accounts serve as nuanced resources for determining the details of deviant events, what elements could have altered the outcomes, and how situational prevention can address unexpected social variables in these events. Finally, I provide a demonstration of the viability of NeuDrift for situational crime prevention and suggest practical applications
INFLUENCE OF FREESTREAM REYNOLDS NUMBER ON UNSTEADY REFLECTED NORMAL SHOCKWAVE-BOUNDARY LAYER INTERACTIONS IN SHOCK TUBE EXPERIMENTS
Get PDFShockwaves can sharply increase the temperature and pressure of a gas in a reliable and near-instantaneous manner, leading to their utility of producing desirable conditions for the study of chemical combustion and high-speed gas dynamics. Shock tubes effectively produce regions of high-pressure, high-temperature gas by generating shockwaves that reflect off of the end of the driven section and form a reflected shockwave. Though the flow conditions after this sequence are typically assumed to be steady, phenomena such as the growth and interaction of the boundary layer with the reflected shockwave cause non-ideal fluctuations in these parameters. The effect of the Reynolds number of the flow behind the incident shockwave on these flow phenomena was studied using a newly built test section added to the shock tube facility of the High-Speed Aerothermodynamics Laboratory at the University of Oklahoma. High-speed schlieren imaging and pointwise pressure measurements were used to assess the reflected normal shockwave/boundary layer interaction (SBLI) and pressure fluctuations present in the flow. It was found that increasing the freestream Reynolds number helped decrease the size of the shockwave bifurcation formed from the SBLI while also reducing the amount of pressure fluctuations in the region behind the reflected shockwave. These trends persisted across experiments performed at three distinct shock Mach numbers
Geophysical assessment on how near surface sediments impact seismic groundmotion due to induced seismicity
No full textIn Union City, Oklahoma, hydraulic fracturing and wastewater injection are a root cause
of increased induced seismicity that is felt by nearby homeowners who report damage to the
Oklahoma geological survey (OGS). To assess the source of the small magnitude earthquake
damage, we deployed over 60 continuously recording nodes and conducted nearly two
kilometers of electrical resistivity tomography (ERT). From the nodal data, we performed
horizontal-vertical spectral ratio (HVSR) to achieve the resonance frequency information from
each nodal location. Pairing the resonance frequency information with the high resolution ERT
allows the resonating body to be identified with the aid of in-situ sampling and grain size
analysis. Our results show that the northern portion of the study area contains the highest
resonance frequencies, which correlate to terrace deposits of the same depth and thickness
according to the USGS. In the southern nodes, the resonance frequencies are suggested to be
trapped in thick clays that are deeper than the alluvium from the Canadian river. Our findings
suggest that near surface sediments, particularly terrace deposits in Union City, OK, may
contribute to heightened property damage when high-frequency seismic waves resonate with
near-surface materials' resonance frequency due to the trapping mechanisms of the Canadian
river layered sediments. This study provides a detailed spatial image of the subsurface,
describing near-surface material impact on ground motion sourced from induced seismic energy.
The insights gained can potentially aid in creating more accurate risk analysis maps, benefiting
nearby suburbs in understanding and mitigating the impact of induced seismic energy
A PALEOCLIMATE AND PALEOFIRE HISTORY FROM THE EARLY PLEISTOCENE OF UNAWEEP CANYON, NORTHWESTERN COLORADO
No full textLacustrine systems capture high-resolution records of continental climate, including information on paleotemperatures, hydroclimate, and paleofire activity. An increasing number of studies have reported paleoclimate and paleofire records from Holocene and upper Pleistocene sedimentary archives across various regions of the arid western U.S., shedding light on possible future scenarios of linked climate-fire regimes attendant with continued climate change; however, records from older intervals are rare to nonexistent. Here, we report on an investigation of paleoclimate and paleofire from an upland lake of the early Pleistocene that records accumulation prior to the Mid-Pleistocene Transition. We recovered an exceptionally long (147 m) core from an early Pleistocene (~1.4-1.3 Ma) lake buried ~200 m subsurface in Unaweep Canyon, a high-relief, upland system of the Uncompahgre Plateau in western Colorado that hosts a thick sediment fill. The age (~1.4-1.3 Ma) is based on cosmogenic-nuclide dating of a previous, correlative section. The sediment comprises predominantly mass flow event beds such as turbidites, with grain sizes ranging from sand to mud. Over the ~147 m of the lacustrine section, prominent color variations occur: two intervals (20 - 32 m thick) exhibiting mostly red and ochre (oxidized) colors alternating with two intervals (35 - 53 m thick) exhibiting mostly drab olive to dark gray (reduced) colors. These color variations correspond to changes in palynological assemblages that indicate two cold-warm variations—inferred glacial-interglacial cycles—with glacials represented by high values of Picea and Abies pollen and generally oxidized colors, and interglacials represented by high values of Artemisia and Pinus pollen and generally drab colors. Climatic conditions are further explored through the variance of magnetic susceptibility (MS), Zr, Ti/Al and Mg/Al ratios between the cycles: glacials exhibit higher averages of MS, Zr, Ti/Al and Mg/Al, suggesting increased detrital input and runoff, interpreted to record wetter conditions. Charcoal accumulation rates vary between the glacial-interglacial hemicycles, with higher concentrations in warmer (interglacial) conditions. Additionally, mean daily insolation patterns were calculated for the general Unaweep region, demonstrating that higher charcoal accumulation rates correspond with times of higher insolation. Overall, the UDR 1A core records that interglacials at the beginning of the mid-Pleistocene transition record warmer and drier conditions that were accompanied by increased frequency of fire occurrence and intensity
God is a woman
Get PDFAs we step into the world of magical feminine power within literature, where women seem to have the unnatural ability to alter the fabric of reality, talk with the dead, or venture into unknown worlds parallel to our own, it becomes clear that connection to liminal space is required. The powers found within liminality are activated by women's ability of introspection and shapeshifting, transforming herself into a new woman time and time again. She gains powers over herself and her space in the process, often times creating a home or safe space that feels alive alongside her. For characters like Marimar and Orquídea Montoya from Zoraida Córdova's The Inheritance of Orquídea Divina (2021), Coraline from Neil Gaiman's Coraline (2002), and Eva and Sula Peace from Toni Morrison's Sula (1976), the connection to the liminal proves empowering as they show their abilities to transform themselves even through supernatural, haunting experiences. A darker side to feminine power is highlighted within these characters, proving the ambiguous and complex nature of feminine power. However, the notion of the "dark" feminine is itself a product of binary thinking. This binary is inherently flawed, as it fails to recognize the complexity of feminine power, which encompasses both life and death, knowledge and mystery. By re-imagining the binary light/dark feminine as the "Wild Woman" instead, the archetype can release her condemned image and reclaim feminine power. By releasing binaries, judgements, and classifications, she is free to use her magic to transform herself and restore her instinctual connection to life and the world around her. Victor Turner introduces his idea of liminality in his Liminalities and Communitas (1969), in which he describes the conditions of liminal spaces as the in-between places of culture and identity. When referring to people in liminal spaces, he states "... these persons elude or slip through the network of classifications that normally locate states and positions in cultural space." (Turner 359). Turner explains the space of liminality as a tool for transitioning through key moments in life, earning "rites of passage" to enter the unknown of the future after a transformation takes place within the liminal space, creating a new self. Gloria Anzaldúa ventures further into liminality with Borderlands (1987) and Light in the Dark (2015), adding a uniquely feminist point of view on life in the in-betweens of identity and culture. Anzaldúa's profound reflections on her own life within the liminal creates a narrative that challenges our understanding of binary language, culture, and spirituality in the understanding of feminine power. Combining these theories with Clarissa Pinkola Estes' Women Who Run With the Wolves (1992), an archetypal descendant of Carl Jung's shadow theory, provides an in-depth analysis on the journeys of women while inside liminal space. Through the analysis of folktales collected from many cultures, Pinkola Estes urges women to re-connect with their intuitive, instinctual inner beings, unlocking a creative and knowing spirit reflecting ambiguity within feminine nature. With these theories in mind, I analyze the shape-shifting woman within the selected texts as she creates her powerful and other-worldly essence, transforming herself and her space. This exploration challenges the traditional feminine binaries and reclaims the feminine power that has been historically condemned