Oodles Of Undergrads Underground: Classroom Undergraduate Research At Wind Cave National Park

For the past three years, the Department of Chemistry and Biochemistry at the University of Northern Iowa has been leading undergraduate students on spectroscopic expeditions into the depths of Wind Cave National Park in South Dakota. Using some of the newest miniaturized spectrometers, portable XRFs, and Lego Mindstorms Kits, the team has been working with NPS park rangers to look at the cave in a new light while providing unique experiences for the students involved

Analysis of Mammut americanum Tusk for Asbestos

On September 23, 1933, a tusk was discovered in a gravel pit four miles south of Hampton, Iowa. After careful analysis, the tusk was determined to belong to a Mastodon americanus.1 The University of Northern Iowa museum records note that the tusk was patched with a prepared patching plaster in the 1960’s.2 In the United States at the time Alvar was the most commonly used consolidate to form a plaster. It was either mixed with acetone, alcohol and other solvents, or asbestos.3 The museum record notes indicate that the patching plaster was prepared in a can, like a spackling compound.2 It is unclear whether this is a professionally mixed conservation material, or a product purchased from a hardware store. In either case, the chance that the plaster compound contained asbestos is extremely high. Asbestos is a term used for a naturally occurring fibrous mineral of many types. These crystalline minerals consist of atoms that are arranged in a long-range order and are antistrophic. Due to this, asbestos fibers are polarizable, and can be seen and counted using Polarized Light Microscopy (PLM). If the fibers are too small and not visible via PLM, a Scanning Electron Microscope (SEM) can be used to identify the smallest fibers.4 The Occupational Safety and Health Administration (OSHA) has defined the Permissible Exposure Limit (PEL) for asbestos at 0.1 fiber per cubic centimeter of air per eight hours5, and the OSHA content limit is 1.0% in a bulk matrix.5https://scholarworks.uni.edu/mastodon_posters/1010/thumbnail.jp

OODLES OF UNDERGRADS UNDERGROUND: CLASSROOM UNDERGRADUATE RESEARCH AT WIND CAVE NATIONAL PARK

For the past two years, the Department of Chemistry and Biochemistry at the University of Northern Iowa has been leading undergraduate students on spectroscopic expeditions into the depths of Wind Cave National Park in South Dakota. Using some of the newest miniaturized spectrometers, portable XRFs, and Lego Mindstorms Kits, the team has been working with NPS park rangers to look at the cave in a new light while providing unique experiences for the students involved

Quantification of TrigonellineFrom Coffee Beans and its Correlation with the pH

This project analyzed the amount of trigonelline preseent in coffee beans at various stages of the roasting process.https://scholarworks.uni.edu/chemanaly_fa2018/1010/thumbnail.jp

Titan Aerosol Analogs from Aromatic Precursors: Comparisons to Cassini CIRS Observations in the Thermal Infrared

Since Cassini's arrival at Titan, ppm levels of benzene (C6H6) as well as large positive ions, which may be polycyclic aromatic hydrocarbons (PAHs). have been detected in the atmosphere. Aromatic molecules. photolytically active in the ultraviolet, may be important in the formation of the organic aerosol comprising the Titan haze layer even when present at low mixing ratios. Yet there have not been laboratory simulations exploring the impact of these molecules as precursors to Titan's organic aerosol. Observations of Titan by the Cassini Composite Infrared Spectrometer (CIRS) in the far-infrared (far-IR) between 560 and 20/cm (approx. 18 to 500 microns) and in the mid-infrared (mid-IR) between 1500 and 600/cm (approx. 7 to 17 microns) have been used to infer the vertical variations of Titan's aerosol from the surface to an altitude of 300 km in the far-IR and between 150 and 350 km in the mid-IR. Titan's aerosol has several observed emission features which cannot be reproduced using currently available optical constants from laboratory-generated Titan aerosol analogs, including a broad far-IR feature centered approximately at 140/cm (71 microns)

Titan Atmospheric Chemistry Revealed by Low-temperature N2-CH4 Plasma Discharge Experiments

Chemistry in Titan's N2-CH4 atmosphere produces complex organic aerosols. The chemical processes and the resulting organic compounds are still far from understood, although extensive observations, laboratory, and theoretical simulations have greatly improved physical and chemical constraints on Titan's atmosphere. Here, we conduct a series of Titan atmosphere simulation experiments with N2-CH4 gas mixtures and investigate the effect of initial CH4 ratio, pressure, and flow rate on the production rates and composition of the gas and solid products at a Titan relevant temperature (100 K) for the first time. We find that the production rate of the gas and solid products increases with increasing CH4 ratio. The nitrogen-containing species have much higher yield than hydrocarbons in the gas products, and the N-to-C ratio of the solid products appears to be the highest compared to previous plasma simulations with the same CH4 ratio. The greater degree of nitrogen incorporation in the low temperature simulation experiments suggests temperature may play an important role in nitrogen incorporation in Titan's cold atmosphere. We also find that H2 is the dominant gas product and serves as an indicator of the production rate of new organic molecules in the experiment, and that CH2NH may greatly contribute to the incorporation of both carbon and nitrogen into the solid particles. The pressure and flow rate affect the amount of time of the gas mixture exposed to the energy source and therefore impact the N2-CH4 chemistry initiated by the plasma discharge, emphasizing the influence of the energy flux in Titan atmospheric chemistry.Comment: Accepted in ACS Earth and Space Chemistry, 6 figure

Organic Hazes as a Source of Life’s Building Blocks to Warm Little Ponds on the Hadean Earth

Over 4 billion years ago, Earth is thought to have been a hazy world akin to Saturn’s moon Titan. The organic hazes in the atmosphere at this time could have contained a vast inventory of life’s building blocks and thus may have seeded warm little ponds for life. In this work, we produce organic hazes in the lab in atmospheres with high (5%) and low (0.5%) CH4 abundances and analyze the solid particles for nucleobases, amino acids, and a few other organics using GC/MS/MS to obtain their concentrations. We also analyze heated (200°C) samples from the high methane organic haze experiment to simulate these particles sitting on an uninhabitable surface. Finally, we use our experimental results and estimates of atmospheric haze production as inputs for a comprehensive numerical pond model to calculate the concentrations of nucleobases from organic hazes in these environments. We find that organic hazes typically provide up to 0.2-6.5 μM concentrations of nucleobases to warm little ponds for potentially habitable Hadean conditions. However, without seepage, uracil and thymine can reach ∼100 μM concentrations, which is the present lower experimental limit to react these species to form nucleotides. Heating samples leads to partial or complete decay of biomolecules, suggesting that biomolecule stockpiling on the hot surface is unlikely. The ideal conditions for the delivery of life’s building blocks from organic hazes would be when the Hadean atmosphere is rich in methane, but not so rich as to create an uninhabitable surface

A Cross-laboratory Comparison Study of Titan Haze Analogs: Surface Energy

In Titan’s nitrogen-methane atmosphere, photochemistry leads to the production of complex organic particles, forming Titan’s thick haze layers. Laboratory-produced aerosol analogs, or “tholins,” are produced in a number of laboratories; however, most previous studies have investigated analogs produced by only one laboratory rather than a systematic, comparative analysis. In this study, we performed a comparative study of an important material property, the surface energy, of seven tholin samples produced in three independent laboratories under a broad range of experimental conditions, and we explored their commonalities and differences. All seven tholin samples are found to have high surface energies and are therefore highly cohesive. Thus, if the surface sediments on Titan are similar to tholins, future missions such as Dragonfly will likely encounter sticky sediments. We also identified a commonality between all the tholin samples: a high dispersive (nonpolar) surface energy component of at least 30 mJ m−2. This common property could be shared by the actual haze particles on Titan as well. Given that the most abundant species interacting with the haze on Titan (methane, ethane, and nitrogen) are nonpolar in nature, the dispersive surface energy component of the haze particles could be a determinant factor in condensate−haze and haze−lake liquid interactions on Titan. With this common trait of tholin samples, we confirmed the findings of a previous study by Yu et al. that haze particles are likely good cloud condensation nuclei for methane and ethane clouds and would likely be completely wetted by the hydrocarbon lakes on Titan

A Cross-laboratory Comparison Study of Titan Haze Analogs: Surface Energy

In Titan’s nitrogen-methane atmosphere, photochemistry leads to the production of complex organic particles, forming Titan’s thick haze layers. Laboratory-produced aerosol analogs, or “tholins,” are produced in a number of laboratories; however, most previous studies have investigated analogs produced by only one laboratory rather than a systematic, comparative analysis. In this study, we performed a comparative study of an important material property, the surface energy, of seven tholin samples produced in three independent laboratories under a broad range of experimental conditions, and we explored their commonalities and differences. All seven tholin samples are found to have high surface energies and are therefore highly cohesive. Thus, if the surface sediments on Titan are similar to tholins, future missions such as Dragonfly will likely encounter sticky sediments. We also identified a commonality between all the tholin samples: a high dispersive (nonpolar) surface energy component of at least 30 mJ m−2. This common property could be shared by the actual haze particles on Titan as well. Given that the most abundant species interacting with the haze on Titan (methane, ethane, and nitrogen) are nonpolar in nature, the dispersive surface energy component of the haze particles could be a determinant factor in condensate−haze and haze−lake liquid interactions on Titan. With this common trait of tholin samples, we confirmed the findings of a previous study by Yu et al. that haze particles are likely good cloud condensation nuclei for methane and ethane clouds and would likely be completely wetted by the hydrocarbon lakes on Titan