LOUIS University of Alabama in Huntsville
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Canterbury Cathedral and English Architecture
Get PDFhttps://louis.uah.edu/honors-399/1002/thumbnail.jp
Identifying redox active metalloligands for catalytic applications with special focus on enabling photoredox processes on cerium(III) centers
Get PDFTerminal cerium(IV)-oxo (CeIV=O) species are known to be highly reactive and tend to oligomerize and degrade organic ligands. This is preventing their application as atomic oxygen radical anion (O.-) transfer reagents. CeIV=O species have been successfully stabilized via non-covalent interactions between the oxo-group and Lewis acids. However, our work is focused on incorporating CeIV=O species into robust polyoxometalates (POMs) to avoid stabilizing the terminal oxo-group and preserving its full reaction potential. Redox-active metalloligands, such as lacunary POMs, have the capability to act as electron reservoirs and promote multi-electron redox-processes as required for catalysis. Therefore, two all-vanadium(V) dodecavanadate, {V12}, metalloligands were studied for their capabilities to act as hosts for CeIV=O species. These metalloligands were synthesized according to literature procedures. The reaction of Ce(NO3)3 and Ce(OTf)3 with the metalloligands resulted in color changes, and the obtained cerium complexes were further studied using Infrared Spectroscopy (IR), Ultraviolet-Visible Spectroscopy (UV/Vis), Nuclear Magnetic Resonance (NMR) and Cylic Voltammetry (CV) characterization techniques
The role of surface processes in modulating land-sea breeze circulation : an observational and numerical modeling study in Java
Get PDFIn the Maritime Continent (MC), sea and land breezes (SLB), shaped by its numerous islands, are key drivers of the tropical climate. Island morphology, terrain, land cover, and orientation relative to prevailing winds affect these breezes and associated convection. While research has largely focused on larger islands, smaller islands like Java remain understudied. Java features a mountainous chain with several gaps and experienced significant land use and land cover changes (∆LULC) over the past two decades. This dissertation aims to: 1) adapt observational methods to detect mesoscale boundaries in numerical models, 2) analyze the role of Java’s topography and cloud- radiation feedback on SLB and convection, and 3) assess the impact of land use and land cover changes on SLB and convection. The first part of the study evaluated the efficiency of scatterometers in detect- ing coastal mesoscale boundaries at different spatial resolutions, identifying 3-km grid spacing as optimal for the wind gradient method. The second part involved numerical experiments that varied complex terrain and cloud-radiative feedback. Factor sepa- ration analysis using a 3-km grid output revealed that complex terrain weakens the diurnal precipitation cycle, especially offshore rainfall driven by land breezes. Gaps in Java’s mountains chain accelerate land breezes by 0.8 m/s, while cloud radiative forcing reduces cloudiness and rainfall, with a stronger effect in areas with complex terrain, enhancing down-valley flow by 2 m/s and intensifying land breezes. Finally, the study analyzed satellite observations over the past two decades and found significant ∆LULC in Java, including a 56% increase in savannas and an 11.5% decrease in forests. Frequency of occurrence of clouds (FOC) over mountain peaks increased by 10%, while precipitation in western Java increased by 2.2 mm/day. Numerical model experiments showed ∆LULC contributed to a 20% increase in FOC in some mountain areas, partially explaining these tendencies. ∆LULC impacts on clouds varied with Bowen ratio at low elevation, increasing or inhibiting formation. However, the effect of ∆LULC on offshore land breezes and rainfall was minimal. This research offers new insights into how surface processes modulate SLB on smaller islands in the MC
Unveiling the mechanisms of bromate formation and NOM treatment in drinking water via plasmon-enhanced catalytic ozonation
Get PDFHigh energy consumption and the formation of harmful byproducts are significant challenges in advanced oxidation processes (AOPs). While much research has focused on improving treatment efficiency, controlling byproduct formation requires more attention. The focus of this dissertation is divided into three main focuses: Firstly, the underlying mechanism of bromate formation inhibition during a plasmon-enhanced catalytic ozonation (PE catalytic ozonation) process using silver-doped spinel ferrite (0.5wt%Ag/MnFe2O4) as the catalyst was investigated by scrutinizing the effects of each factors involved in PE catalytic ozonation including irradiation, catalyst, and ozone, both individually and in combination, on major bromine species involved in bromate formation. The study found that accelerated ozone decomposition inhibited two main bromate formation pathways. Additionally, surface reduction of bromine species (e.g., HOBr/OBr− and BrO3−) was enhanced by the plasmonic effects of Ag and the strong affinity between Ag and Br, contributing to the inhibition of bromate formation. Secondly, the efficacy of plasmon-enhanced catalytic ozonation in treating dissolved organic matter (DOM) fractions was assessed by utilizing the same catalyst in the first focus. This included evaluating alterations in mass distribution and total organic nitrogen quantity, investigating transformations of organic structures, and characterizing structural changes before and after each ozonation processes. Experiments were conducted at two different ratios of transferred ozone dose to initial total organic carbon (TOD/TOC=0.9, 1.5) to assess the impact of ozone concentration on DOM availability. DOM was fractionated based on chemical features, including hydrophobic and hydrophilic fractions with acidic, basic, and neutral characteristics, using raw water samples from Huntsville water utilities. The results indicated that fast decomposition of ozone molecules to hydroxyl radical and other reactive oxygen species resulted in a higher removal of DOM fractions in terms of TOC and COD. Thirdly, raw water samples underwent similar analyses to understand the combined role of these fractions in more realistic water treatment scenarios. High proportion of hydrophobic acid fraction played a role in controlling the behavior of raw water samples under the different ozonation processes
Evaluating the susceptibility of the LEW.1WR1 rat to glucose intolerance, insulin resistance, and MASLD : is FAT10 the key?
No full textObesity is an epidemic that affects over 40% of adults in America. Obesity can be divided into metabolically healthy and metabolically unhealthy obesity, with the latter being characterized by symptoms closely associated with metabolic syndrome, type 2 diabetes, and metabolic dysfunction-associated steatotic liver disease (MASLD). What causes the transition from metabolically healthy to metabolically unhealthy obesity is not fully known. Further, it is unclear how this transition correlates with the onset of co-morbid conditions. We propose that Ubiquitin D (FAT10) may play a role in transitioning into a metabolically unhealthy state in response to obesity. This dissertation evaluated two main research questions: 1) would LEW.1WR1 rats, predisposed to overexpress FAT10, develop symptoms of metabolic dysfunction such as insulin resistance, obesity, and MASLD over time? and 2) does increased FAT10 expression in hepatocytes cause changes that could negatively impact cellular metabolism? We report that LEW.1WR1 rats have insulin resistance as measured using Insulin tolerance tests. LEW.1WR1 rats developed glucose intolerance and worsening insulin resistance as they aged but did not develop ꞵ-cell expansion on a moderate sucrose diet. LEW.1WR1 rats on a chow diet developed MASLD based on validated histological scoring criteria and decreased fatty acid oxidation gene expression, which we believe is due to a significant increase in FAT10 gene expression in their livers. We then pursued whether increased FAT10 impacts hepatocytes with fluorescent microscopy and observed that increased expression causes disrupted mitochondrial area and volume, which could indicate megamitochondria or stress-induced mitochondrial hyperfusion. Our results show that LEW.1WR1 rats developed glucose intolerance, insulin resistance, and severe MASLD on a chow diet, indicating they may be a more human-like rodent model for developing metabolic disorders. Our research also showed that increased FAT10 expression induced mitochondrial morphology dysfunction, further supporting FAT10 as a target for early detection of metabolic diseases
Enhancing accessibility : a pilot study for context-aware image-caption to American Sign Language (ASL) translation
Get PDFSince the advent of Artificial Intelligence (AI), and the explosion of Genera- tive AI, much work has been done around image captioning, providing wildly accurate captions from still images, and more recently videos [3]. Alt-Text has improved dra- matically with efforts to enhance context and sentiment captured during automated captioning. This thesis attempts to expand on a section on Natural Language Pro- cessing (NLP) and its relevance to promoting accessibility and context-awareness in the premise of the American Sign Language (ASL) application. This thesis explores what it means to give full context about a caption or image to the end user, includ- ing sentiments, and sentient features existing within the string of words. This thesis goes to great lengths to expand on accessibility features currently present in image- captioning. Is a user-reliant (dependent on the users to provide a caption for the image) or a generic machine-generated alt-text enough for full accessibility? Could adding a sign language, for example, American Sign Language (ASL), be crucial to giving users more information than what is conveyed in the collection of words called a caption? Most importantly, how can we make this image-caption translation more context-aware to capture the nuances that might be important for user understand- ing? Ultimately, the goal is to make a world where every voice is heard and every individual feels welcome, and this thesis is a starting step towards an AI revolution that could be instrumental in achieving that dream
Bias Against Severe Mental Illness on Treatment in Emergency Medical Situations
Get PDFhttps://louis.uah.edu/research-horizons/1348/thumbnail.jp
Application of a scale resolving turbulence model to a jet in supersonic crossflow
Get PDFThe Partially-Averaged Navier-Stokes (PANS) methodology is applied to variable-density flow to derive the Blended PANS (BPANS) model. A supersonic jet-in-crossflow problem is numerically simulated using the BPANS model to show its capabilities in a variable-density flow with complex physics. The shock systems and vortex structures of this problem observed during experiments are numerically reproduced. The time-averaged Mach number and streamwise velocity contours show good agreement compared to LES and experimental data. The streamwise and wall-normal velocity profiles, wall pressure distribution along the flat plate, and trajectory of the jet are compared to LES and experimental data to show that BPANS accurately predicts them. The filter control parameter fk is varied to show the effect of the unresolved to resolved ratio of the turbulent kinetic energy k and the specific dissipation rate ω. The results show that smaller fk results in better agreement with LES and experimental data near local extrema
