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MICROWAVE ASSISTED SYNTHESES AND CHARACTERIZATIONS OF NEAR-INFRARED RATIOMETRIC PROBES FOR MITOCHONDRIAL pH DETECTION AND MONITORING
Get PDFWithin the field of biochemistry, there has been a significant development of ratiometric fluorescent probes designed for mitochondrial pH detection; however, many of these probes have emissions within the visible spectrum and require long synthesis times with low-yield reactions. However, in recent years, microwave-assisted syntheses of organic molecules have led to significant increases in reaction yields and quicker reaction times. In this work, two common reactions in probe synthesis, Heck coupling, and Knoevenagel condensations are investigated using microwave-assisted synthesis. It was found the low-concentration Heck coupling reactions using palladium (II) acetate led to extremely efficient Heck coupling. Also, a novel method for completing Knoevenagel condensations with multiple reactive sites with high selectively and increased reaction yields using microwave-assisted synthesis was completed. Moreover, two novel ratiometric pH-sensing probes, AH+ and BH+, were developed; both probes have emissions within the near-infrared range, with AH+ featuring ratiometric emission bands at 725 nm and 820 nm. Probe AH+ was evaluated for mitochondrial pH changes in living HeLa cells via fluorescence emission measurements of both ratiometric peaks. This probe was also used to measure the pH response within mitochondria with respect to different stimuli, such as starvation, oxidative stress, and hypoxia. Probe AH+ was also used to evaluate the pH effects of Metformin, a commercially available drug used in the treatments of diabetes, on mitochondrial pH, which allowed for the visualization of Metformin’s action within the intermembrane space of mitochondria
Impacts of riverine heatwaves on rates of ecosystem metabolism in the United States
Get PDFRivers produce and decompose large amounts of carbon globally due, in part, to high rates of gross primary production (GPP) and ecosystem respiration (ER), collectively known as ecosystem metabolism. Water temperature is a major driver of ecosystem metabolism, and in-stream temperatures are increasing globally, including extreme temperature events called heatwaves. This study used published estimates of daily GPP and ER from 48 stream and river locations in the United States to examine how ecosystem metabolism responds to riverine heatwaves. During low-severity heatwaves, GPP and ER increase proportionally, resulting in no net difference. However, during severe and extreme heatwaves, GPP declined up to 82% while ER increased up to 47%, resulting in greater rates of heterotrophy (ER \u3e GPP). While rivers were typically heterotrophic outside of heatwave conditions, these results suggest that during heatwaves, rivers become stronger sources of carbon dioxide
Life Cycle Cost Analysis of Prestressed Concrete Poles Subjected to Wind, Surges, and Waves
No full textPrestressed concrete (PC) poles are becoming popular choices to support coastal power transmission systems. However, the existing literature does not offer a detailed analysis of the effectiveness of PC poles in terms of long-Term vulnerabilities and the direct and indirect costs. This is due to (1) lack of fragility models for PC poles and (2) lack of probabilistic wind, storm surge, and wave models in coastal settings. In this study, we address these gaps through a series of Monte Carlo simulations to estimate fragility of PC poles as a function of age and hazard (wind, surges, and waves) intensity, and the development of a probabilistic hazard model based on 10,000 years of synthetic tropical cyclone data. The probabilistic hazard model is used in conjunction with high-resolution hydrodynamic models to generate realizations of coastal wind, storm surges, and waves for the Louisiana and Mississippi coasts. A comprehensive life cycle cost analysis for a service life of 70 years considering direct and indirect losses is conducted to compare the performance of a transmission line located in Pascagoula, Mississippi, when wood poles are replaced by PC poles. Results showed that aging has a minor effect on the reliability of PC poles, highlighting the advantages of replacing wood poles with PC poles, especially in coastal areas. In addition, PC poles are significantly more cost-effective compared with wood poles over their life cycle, leading to an estimated saving of $11.55 million (68.17% reduction). The results of this study provide key insight to inform decision-making processes to keep the coastal power grids resilient and cost-effective against future storm hazards
Extended TeV Halos May Commonly Exist around Middle-Aged Pulsars
No full textExtended gamma-ray emission around isolated pulsars at TeV energies, also known as TeV halos, have been found around a handful of middle-aged pulsars. The halos are significantly more extended than their pulsar wind nebulae but much smaller than the particle diffusion length in the interstellar medium. The origin of TeV halos is unknown. Interpretations invoke either local effects related to the environment of a pulsar or generic particle transport behaviors. The latter scenario predicts that TeV halos would be a universal phenomena for all pulsars. We searched for extended gamma-ray emission around 36 isolated middle-aged pulsars identified by radio and gamma-ray facilities using 2321 days of data from the High-Altitude Water Cherenkov (HAWC) Observatory. Through a stacking analysis comparing TeV flux models against a background-only hypothesis, we identified TeV halolike emission at a significance level of 5.10σ. Our results imply that extended TeV gamma-ray halos may commonly exist around middle-aged pulsars. This reveals a previously unknown feature about pulsars and opens a new window to identify the pulsar population that is invisible to radio, x-ray, and GeV gamma-ray observations
Exploring New Applications of Municipal Solid Waste
Get PDFThis study aimed to (i) characterize municipal solid waste (MSW) sourced from Utah and Michigan transfer stations and (ii) upcycle, produce, and evaluate composites derived from this MSW. Composition analysis showed that the MSW was composed of a variety of commodity plastics, paper/cardboard, and inorganic materials. Detailed chemical analysis for lignin, cellulose, hemicellulose, and lipids was performed. The plastics identified were mainly polyethylene, polypropylene, polystyrene, and poly (ethylene terephthalate). The compoundability of the MSW was assessed by torque rheometry. Composites were prepared by compounding the MSW in an extruder. A composite flexural strength of 29 MPa and a modulus of 1.0 GPa was achieved. The thermal properties of the composites were also determined. The melt flow behavior of the MSW composites at 190 °C was comparable to wood plastic composite formulations
Efficacy of baits and lures for weasel detection
Get PDFSmall mustelids are difficult to survey due to their low density and cryptic nature. Population status of North American weasels (Mustela erminea, Mustela nivalis, and Neogale frenata) are believed to be in decline, but there are no standardized monitoring protocols to evaluate their status. To support weasel monitoring, we compared the attractiveness of various combinations of baits and lures to weasels in sites located throughout the eastern and central USA. We baited a total of 122 clusters of 4 camera traps, across 14 states, with random combinations of 4 baits and 3 scent lures in the winters of 2022 and 2023. Cameras baited with meat were 3.5 times more likely to detect both short- and long-tailed weasels on average (mean percentage of cameras detecting weasels: 20–30%) than those with scent lures (3–11%). Red meat was twice as effective at attracting short-tailed weasels (50%) as chicken or cat food (20%; Z = 2.49, p \u3c 0.01). While red meat marginally increased detections of long-tailed weasels (21%) compared to chicken and cat food (19%), its effectiveness was influenced by whether the bait was stolen (Z = 2.08, p = 0.04). Additionally, long-tailed weasels were detected in half the time when raw chicken was used (median days to detection: red meat = 39.5 days, raw chicken = 14.5 days). When salmon oil was added to meat bait, it increased the likelihood of detecting short-tailed weasels and reduced the time to detection for both species. A variety of non-target species stole meat bait during the survey, making the camera traps less effective. The addition of salmon oil may have allowed for continual attraction of weasels until stolen meat bait could be replenished. In summary, red meat was the best all-purpose bait for weasels, although raw chicken is similarly effective for long-tailed weasels, and the addition of salmon oil is helpful. We also recommend a specific bait enclosure design that was the most effective at minimizing theft of bait. We propose our baiting strategy can be used as a survey standard to evaluate the distribution and population status of weasels
Autoxidation-Induced Curing of 6-Hydroxycatechol-Containing Adhesive
No full textCatechol is an oft-used crosslinking precursor and adhesive molecule for designing in situ curable biomaterials and adhesives and the addition of chemical or enzymatic oxidants is required to initiate fast curing. Here, the feasibility for 6-hydroxydopamine (6-OHDA)-modified 8-armed polyethylene glycol (PEG) (8-arm PEG-DA-OH) to cure through autoxidation is evaluated. The modification of catechol side chain with an electron-donating hydroxyl group at the six-position drastically increased the rate of oxidation and the adhesive cured in just over 1 min through autoxidation. The cure time is decreased to under 40 s with the addition of branched polyethyleneimine (PEI). UV–vis spectra revealed that the deprotonated quinone of 6-OHDA is a key oxidation intermediate for chemical crosslinking between 6-OHDA and with primary amine. PEG functionalized with unmodified catechol do not solidify through autoxidation, which highlights the contribution of the electron-donating hydroxyl group in promoting fast oxidation and crosslinking. Eight-arm PEG-DA-OH and PEI mixture also demonstrated significantly higher adhesion strength to pericardium tissues when compared to a commercial PEG-based adhesive, DuraSeal. This report highlights 6-OHDA as an effective crosslinking precursor and adhesive molecule for designing injectable adhesives that do not require externally added oxidants and the adhesive is activated by simple dissolution in an aqueous solution
Dominating Grief: An Ambiguously Augustinian Approach to Pregnancy Loss
No full textThis chapter explores the nature of pregnancy, the soul, and the profound loss experienced in miscarriage through the lens of Augustine\u27s writings. In the first section, “Augustine, Pregnancy, and the Soul,” I revisit my previous work, highlighting how Augustine\u27s thoughts on these topics may offer a Christian perspective on miscarriage discourse. The second section, “Domination through Language: Miscarriage as the Absent Referent of Abortion Discourse,” examines how miscarriage victims are rendered invisible, as their experience is often appropriated as a metaphor in broader abortion debates. In the third section, “Domination through Legislation: a Personal Account,” I intertwine my own experiences with pregnancy loss with recent US legislative actions, discussing how political and legal measures contribute to the domination of women. Finally, in “Consolations in Grief: Towards An Augustinian Ambiguity,” I draw on Augustine\u27s uncertainty regarding the nature and origin of the human soul to propose an ambiguous yet consoling perspective on miscarriage. Through these reflections, the chapter invites a nuanced engagement with the complex emotional, spiritual, and political dimensions of pregnancy loss
LIFE CYCLE ASSESSMENT AND TECHNO-ECONOMIC ANALYSIS OF MINE TAILINGS AS A SUSTAINABLE RAW MATERIAL FOR MINERAL CARBONATION AND RECOVERY OF CRITICAL MINERALS
Get PDFThis study assesses the feasibility of using mine tailings for mineral carbonation and nickel recovery through a comprehensive Life Cycle Assessment (LCA) and Techno-Economic Analysis (TEA). The LCA quantifies greenhouse gas emissions, energy use, and resource consumption, while the TEA evaluates capital investment, operational costs, and process efficiency. The conventional beneficiation process at Eagle Mine serves as a baseline, highlighting its environmental footprint and operational costs. Results indicate that tailings reprocessing incurs higher costs (25.90 per tonne) due to increased energy consumption and material handling requirements. Additionally, several mineral carbonation scenarios and an acid leaching experiment were explored to improve CO2 sequestration and nickel extraction. LCA and TEA modeling of these experiments under baseline scenarios showed significantly higher CO2 emissions and cost due to higher energy and reagent consumption. In particular, heating demand and reagent consumption were identified as the primary contributors to environmental impact. However, process modifications - such as increasing solids content, increasing water and reagents recycling, reducing agitation speed and modifying other reaction kinetics, resulted in a reduction in CO2 emissions and energy costs reinforcing its potential for climate change mitigation and critical mineral (Ni) recovery
Performance of high-rubber-content modified asphalt chip seal in wet-freezing environments
No full textTo achieve cleaner production of asphalt materials for paving, recycling waste tires has become a valuable option. The rubber from waste tires enhances pavement performance, making it an effective and sustainable solution. This study explores the feasibility of using high-rubber-content modified asphalt in hot asphalt chip seal applications under wet-freezing environments. Materials from a field construction project were used to prepare two types of chip seal samples in the lab: one using modified asphalt with 25 % crumb rubber content and the other using emulsified asphalt. The asphalt binder properties, aggregate chip retention, surface friction, and bonding strength of both chip seals were evaluated. Simulated freeze-thaw testing over 1–5 cycles was conducted to assess shear and tensile bond strength loss. Field pull-off test, smoothness, and distress evaluation were performed at the construction site. The results indicate that using high-rubber-content modified asphalt outperformed in both binder and chip seal performance tests, demonstrating improved viscosity, enhanced resistance to high and low temperatures, superior bonding strength, and reduced surface cracking. High-rubber-content modified asphalt chip seal is ideal for regions with wet and freeze-thaw conditions. The successful implementation of this study promotes cleaner production by enhancing waste tire recycling efficiency in road construction and supporting resource sustainability