LOUIS University of Alabama in Huntsville
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Analysis of Mach Diamond Formation on Compressed Air Nozzles
Get PDFhttps://louis.uah.edu/research-horizons/1393/thumbnail.jp
The effect of micro-sized tin/hard carbon composition on sodium-ion battery performance
Get PDFSodium-ion batteries represent a promising alternative to lithium-ion technology for large-scale energy storage due to sodium\u27s abundance, global availability, and cost advantages. However, developing high-capacity anodes that simultaneously deliver substantial energy density and stable cycling performance remains a critical challenge for its commercial viability. This dissertation investigates tin/hard carbon composite anodes as a solution to the fundamental trade-off between specific capacity and cycling stability in sodium-ion battery systems. While tin offers exceptional theoretical capacity through alloying reactions, it suffers from massive volume expansion during sodiation/desodiation, leading to particle pulverization and rapid capacity degradation. On the other hand, hard carbon has good chemical, thermal and structural stability, but with lower specific capacity. The composite approach aims to leverage tin\u27s high capacity while mitigating its mechanical instability through carbon\u27s buffering properties. Systematic evaluation of tin/hard carbon composites with varying weight ratios revealed distinct performance trends. Anodes with tin as the sole active material achieved the highest initial capacities but experienced severe degradation due to rapid structural failure. Progressive incorporation of hard carbon systematically improved cycling stability of the tin-based anodes, although with reduced capacities. The higher carbon content compositions demonstrated better stability over fifty cycles, with retained capacities eventually surpassing those of high-tin formulations due to improved cycling durability. Comprehensive characterization through electrochemical, microstructural, and crystallographic analysis provided insights into composite behavior. Cyclic voltammetry demonstrated that hard carbon incorporation preserved tin\u27s multi-phase electrochemical signature during extended cycling, maintaining phase reversibility that was lost in pure tin systems. The carbon framework prevented particle agglomeration and maintained electrical connectivity, enabling consistent access to tin\u27s capacity. Microstructural analysis provided visual evidence of the underlying degradation mechanisms and behavior. For the pure tin anode, increased structural failure with particle pulverization and electrode delamination was observed, while carbon-rich composites maintained coherent electrode architecture. This difference is attributed to the carbon matrix providing both mechanical support and electrical connectivity through percolated conductive networks. The research establishes that modest carbon additions can achieve significant improvements in cycling stability while maintaining energy densities substantially higher than conventional hard carbon anodes. This scalable synthesis approach using direct mixing of commercially available materials provides a practical approach to increasing capacity while ensuring compatibility with existing battery manufacturing infrastructure
Manganism and the development of a green sustainable low-threshold spectrophotometric test for the monitoring of manganese in consumable water
Get PDFManganism, a neurotoxic disease from the hyperaccumulation of manganese, follows an etiology that parallels Parkinsonism. Non-occupational Manganism is acquired by the lifelong accumulation of manganese through water contaminated by natural and industrial sources. Biologically active manganese (II) eludes flocculation and filtration removal methods at water utilities. The U.S. Standard Methods For the Examination of Water and Wastewater persulfate testing method uses mercury sulfate, concentrated nitric and phosphoric acids, silver nitrate, and ammonium persulfate. The low detection limit of 210 µg/L is an order of magnitude greater than the World Health Organization (WHO) allowable limit of 10-50 µg/L. In 2004, the EPA chose not to adopt the WHO inclusion of manganese monitoring as a primary drinking water contaminant. They established a limit of 300 µg/L as a “health advisory” and 50 µg/L as an “aesthetic standard” to prevent staining, bad taste, and smell from the water. These limits are voluntary because manganese is a secondary drinking water contaminant where routine testing is not required. The Global International Standard ISO Method 6333 utilizes formaldoxime, a chemical not approved for use in the U.S. by the American National Standards Institute (ANSI). To address the need for a safer, greener, and compliant testing method, reagents were synthesized, characterized, and used to develop a spectrophotometric quantitative testing method that spans the full compliance range established by WHO. This low-cost testing method enables on-site monitoring at water utilities, obviating the need for costly outsourced testing. Manganese can become a primary drinking water contaminant, with utilities testing daily and taking preventative action to toxic exposure before water release, rather than reporting after a harmful event. Manganese, as a trace metallomics requirement in all biological systems, is presented herein, and why too much of a good thing manifests as neurological pathologies. Modes of toxicity in humans are discussed as occupational and non-occupational sources. The history of Manganism, from its discovery in 1837 to the current day, is presented with manganese toxicity sources within each appropriate section. Legislative policies that are currently outdated can be reviewed and revised utilizing these metrics
Exploration of various in-space fuels with differing characteristic timescales for small-scale rotating detonation rocket engines
No full textThis thesis summarizes the performance of a small-scale rotating detonation rocket engine (RDRE) using methane or hydrogen as the fuel with oxygen as the oxidizer. Specifically, a 25 mm RDRE with a 5 mm annular width and 31.2 mm length is experimentally evaluated at varying equivalence ratio for a fixed total mass flow rate of 0.076 kg/s, as well as varying total mass flow rate for fixed equivalence ratios of 1.25 and 1.00. Experimental measurements for the hot-fire tests include thrust, chamber pressure, specific impulse, and detonation mode parameters. For both sensitivity studies, hydrogen outperforms methane with a peak thrust of 128 N, while methane produces a maximum thrust of 88 N. Additionally, a characteristic timescales analysis is used to generate analytical models that are applied to this engine to understand the underlying physics governing the behavior of small-scale detonation-based engines. Overall, this work serves to demonstrate fuel sensitives and baseline scaling methodologies for small-scale RDREs
Design of a 1940s British Lunar Space Suit
No full textIn the late 1940s, long before the eventual Apollo program was developed across the pond, a group of space enthusiasts gather in a small house in London to discuss a new design for a space suit designed to allow an individual to live and work on the moon. Harry Ross’s design shows that consideration was given to a number of possible issues that would be faced by a lunar astronaut. Temperature extremes on the surface of the moon vary from 248 °F at noon to -238 °F at night. Several precautions were taken to protect the explorers from these extremes, including reflective materials designed to keep heat away and a black chest piece designed to radiate it out. As the moon has no breathable atmosphere, air supply was another vital concern. Oxygen was to be stored in onboard tanks, and carbon dioxide removed by a special sodium peroxide scrubber. The reaction of this chemical with CO2 would produce breathable oxygen, limiting the need for onboard oxygen storage. This chemical removal method parallels the eventual designs found in the Apollo Lunar Module, which used Lithium Hydroxide for this purpose. The outer surface of the suit was to be made of a layered composite. Outwards in layers of closely woven cloth, a heat resistant material such as kapok or wool, an airtight sheath of fabric backed rubber, and an interior lining for comfort. A dual walled design limited conduction of heat into and out of the suit, similar to how a thermos keeps a beverage warm. In the center of the chest a small airlock was placed to allow an object of scientific interest to be placed inside and inspected more closely by the wearer.https://louis.uah.edu/honors-399/1019/thumbnail.jp
The Global Extent and Impact of Kew Royal Botanic Garden\u27s Research and Exploration
No full textBy the late 18th and 19th centuries, Kew Royal Botanic Gardens established itself as a leading hub for botanical science. This global standing was influenced by British imperial expansion, enabling collections, classifications, and plant exchanges from practically every continent. With the work of individuals like Joseph Banks and J.D. Hooker, Kew’s status bolstered as a renowned botanical garden and scientific institution.https://louis.uah.edu/honors-399/1026/thumbnail.jp
Cognitive Behavioral Therapy (CBT) as Primary Treatment for Adult ADHD: A Scoping Review
No full texthttps://louis.uah.edu/rceu-hcr/1490/thumbnail.jp
Prompt Taxonomy A Student Ownership, Creativity, and Interest Intervention Through Creative and Writing Assignment Prompts
No full texthttps://louis.uah.edu/rceu-hcr/1494/thumbnail.jp
Step By Step: Enhancing Stair Use with Augmented Reality Cues
No full texthttps://louis.uah.edu/rceu-hcr/1502/thumbnail.jp
Water Electrolysis for Rotating Detonation Rocket Engine Propellant Generation
No full texthttps://louis.uah.edu/rceu-hcr/1508/thumbnail.jp