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Metal Oxide Impact on Thermodynamic and Steric Behavior of Adsorbates for Sustainable Energy and Carbon Transformation
Get PDFMetal oxides have the potential to catalyze carbon-based resource transformation chemistries that are prerequisites to a sustainable energy economy. While metal-oxides have demonstrated carbon transformation benefits and been widely adopted, the nanoscale understanding of surface chemistry still has knowledge gaps that have yet to be elucidated. The computational studies contained in this thesis are sub-grouped into three applications of metal-oxide catalysts: those that target (i) biomass transformations, (ii) plastic upcycling, and (iii) hydrogen production. The associated computational studies of these systems provide important thermodynamic, steric, and energic information to real-world experimental efforts to innovate such catalyst systems.Biomass transformation encompasses the primary focus of this work. One application is sustainable aviation fuel production through the dehydration of short-chain alcohols. 2,3-butanediol(BDO) as a fuel precursor to or as a value-added by-product of upstream processes in an ethanol-to-jet process can be dehydrated on a rutile RuO2(110) catalyst. Using density functional theory (DFT) calculations, a P-T phase diagram was constructed for BDO adsorbed on rutile RuO2(110), revealing the thermodynamically stable ground state configurations of BDO that can be expected under experimental conditions. From this, it was determined that a high-pressure reactor would be necessary as the phase diagram predicts BDO will desorb before reaching the elevated temperatures (~500 K) needed for dehydration. The relevant ground state configurations of BDO expose the most favorable site as one with the BDO hydroxyl functional groups bonded to five-fold coordinated surface ruthenium (“Ru5c”) atoms with BDO’s methyl groups in gauche conformation. Lateral interactions between adsorbed BDO molecules were extracted from all BDO configurations. They showed that the only attractive lateral interaction with the surface is from BDOs interaction separated by a bridge-bonded O2c atom row. All other interactions are repulsive and dictate which configurations of BDO are most favorable up to saturation coverage.We also investigated the stability and acid-base properties of anatase TiO2 nanocrystals with low-index facets (101) and (001) for dehydration reactions. Surface models of both facets were analyzed with respect to H2O and OH adsorption. Computational modeling allowed the assignments of the experimental in situ DRIFTS spectra of both facets. In the (101) facet, the OH* region reveals a previously misrepresented, red-shifted terminal v(OH) (OH stretch) at 3605 cm-1. The (001) facet undergoes reconstruction under UHV conditions due to strain. Although this was not observed experimentally due to surface contamination, the stabilized hydroxylated stoichiometric surface yields peak assignments for undercoordinated edge titania. A broad range of water peaks from 2400-3400 cm-1 exhibit delocalization with bridging v(OH) and vs(OH) (symmetric OH stretch in a molecular water molecule), with the experimental peak identified at 3133 cm-1. A partially hydroxylated anatase (101) surface was utilized to absorb methanol as a probe molecule for the acid-base chemistry of TiO2(101). By projecting vibrational normal modes into internal molecular coordinates, we could differentiate bridging (MeOb) versus terminal (MeOt) methoxy and methanol in the IR spectra. The frequencies associated to the vibration methyl groups of adsorbed methanol and methoxy follow the order MeOH > MeOb > MeOt trend of MeOH>MeOb>MeOt. Partially deuterated methanol species were also analyzed computationally and experimentally to determine the symmetry of the methanol adsorbates, as well as offering an unobscured view of the methyl stretching modes for assignment. Symmetry point groups give spatial and molecular orbital information on adsorbates and demonstrated differences between methanol and methoxy. Our findings indicated that methanol possessed C1, the lowest symmetry point group, whereas methoxy displayed Cs symmetry, indicative of a mirror plane within the molecule. This information enhances our understanding of spatial positioning and provides tools to distinguish between dissociated versus molecular water and methanol adsorbates for further chemical transformation.Metal oxides serve also as a support for metal nanoparticles in a variety of catalytic applications, such as hydrogenolysis. Plastic upcycling hydrogenolysis can convert waste plastics into usable carbon chains for lubricants and fuels. Nanoparticle metals, particularly ruthenium, are desirable candidates for this reaction due to their high surface-to-volume ratio. CeO2 has been demonstrated as a support for Ru nanoparticle clusters in hydrogenolysis. TiO2 is tested as an additional support for Ru nanoparticle clusters and used as a control to evaluate the support advantages of CeO2. Computational modeling found that the wetting capability (flatness of the Ru clusters) of the Ru nanoparticles on CeO2 is significantly stronger, influenced by the characteristic oxygen vacancies that are present under reaction conditions. For both CeO2 and TiO2 supports, only small nanoparticle sizes remained stable when wetting the surface (Ru7 for CeO2, Ru4 for TiO2). The larger size of the Ru clusters on CeO2 was evident from the low-loading wetting observed experimentally.In all the carbon transformations mentioned, additional hydrogen is required to make the chemistry accessible. However, the main form of hydrogen used industrially comes from environmentally costly steam reformation in the petrochemical industry. Therefore, there is a push for hydrogen, which comes from the electrochemical water-splitting reaction. The water-splitting hinges on the hydrogen evolution reaction, whose bottleneck is the oxygen evolution reaction (OER). A new class of materials called topological Weyl semi-metals are candidate materials for this reaction as they are poison-resistant and stable. Co3In2S2 has been proven to be a strong material and, in this work, was the modeled catalyst for the OER reaction. The catalyst formed an indium oxide complex layer during the reaction that was poison-resistant and effective at carrying out the OER reaction. The modeled reaction energy pathwaydetermined that the OER reaction is inaccessible on the surface without this amorphous layer.First-principles analysis of metal oxide systems is used to analyze and compare to experiments and provide foundational understanding in the applications of i) biomass transformation ii) plastics upcycling and iii) hydrogen production. Through the analysis provided, thermodynamic and steric information highlights the importance of metal and oxygen in carbon transformation for sustainable energy. This was achieved by illustrating the stability at various temperatures and pressures and affixing the adsorbates in a favorable confirmation. Adaptations toward sustainable energy are necessary for increased energy demand without destroying organic life through fossil fuel production. The work contained in this dissertation provides a pathway for metal oxide catalyst technology to be implemented for sustainable energy and carbon transformation for environmental and societal benefits
DESIGN, INTEGRATION, AND EVALUATION OF A DUAL-ARM ROBOTIC SYSTEM FOR HIGH-THROUGHPUT TISSUE SAMPLING FROM POTATO TUBERS
Get PDFMolecular-based pathogen detection from potato tubers offers a promising alternative to traditional post-harvest grow-out tests, which are field-based, time-consuming, and costly. However, manual tuber tissue extraction for molecular detection remains a significant bottleneck as the process is labor-intensive and physically demanding. To overcome these limitations, this study developed an automated tissue sampling system using a machine-vision-guided dual-arm coordinated inline robotic platform. This system integrated tuber grasping and tissue sampling mechanisms, enabling precise and rapid tissue extraction from specific regions of the tuber, such as the eyes and stolon scars.The first phase of the study investigated various deep-learning-based object detectors, including multiple variants of the You Only Look Once (YOLO), namely, YOLOv5, YOLOv6, YOLOv7, YOLOv8, YOLOv9, YOLOv10, and YOLOv11, for detecting eyes and stolon scars from a robust image dataset obtained from tubers of five potato cultivars (three russet-skinned, one red-skinned, and one purple-skinned). The class-wise mean average precision at an intersection over union threshold of 0.5 ([email protected]) ranged from 0.832–0.854 with YOLOv5n to 0.903–0.914 with YOLOv10l across the cultivars. Among all the tested models, YOLOv10m demonstrated the optimal balance between detection accuracy ([email protected] of 0.911) and inference time (92 ms), along with satisfactory generalization performance when cross-validated across the cultivars used in this study. The model benchmarking and findings from this phase of the study provided valuable insights into the development of a reliable machine-vision system for robotic tuber sampling applications.In the second phase, an in-line dual-arm robotic system incorporating a machine-vision-based control scheme was developed. The system functioned by transporting tubers onto a conveyor, which halts when a YOLO11-based vision system detects a tuber entering the workspace of the tuber-gripping mechanism. The gripping-mechanism consisted of a one-prismatic (P)-degree-of-freedom (DoF) arm equipped with a gripping end-effector that securely grasped the tuber and positioned it for sampling. The second robotic arm, a 3-P-DoF Cartesian manipulator with a biopsy punch-based end-effector, performed tissue sampling. Tissue sampling was carried out at specific locations on the tubers (eyes or stolon scars), which were detected and localized by the YOLOv10m-enabled vision system. A four-stage tissue-sampling process was introduced, involving the insertion of the end-effector into the tuber, rotation of the biopsy punch for tissue detachment from the tuber, biopsy punch extraction, and deposition of the tissue core onto a designated collection area. The results showed an average positional error of 1.84 mm in reaching the sampling location along the tuber surface, and an average depth deviation of 1.79 mm from the intended 7.00 mm punching depth. The system achieved an overall success rate of 81.5% in tissue core extraction and deposition onto the designated collection area, with an average sampling cycle time of 10.4 seconds. With a total cost of system components less than $1,900, the system demonstrates promising potential as a cost-effective alternative to labor-intensive manual tissue sampling. To summarize, this study developed a robotic platform that offers a cost-effective and scalable solution for potato tuber tissue sampling thereby facilitating the adoption of high-throughput molecular-based diagnostic workflows
IMPROVING EMERGENCE IN WINTER CANOLA IN THE PACIFIC NORTHWEST
Get PDFFor farmers who use tillage in the inland Pacific Northwest (PNW), winter canola can struggle to establish stands due to soil crusting. Winter canola is typically planted at 2.5 cm or deeper into moisture in August or early September, but rainfall and subsequent dry downs can create a soil crust that the seedlings cannot penetrate. A lightweight and inexpensive low-intensity nozzle-type rainfall simulator was constructed and used to induce soil crusting within a two-factor greenhouse experiment to evaluate emergence of winter canola planted into soil columns. The simulator is equipped with three flat-fat TeeJet nozzles mounted to an oscillating spray boom to evenly cover a 1.25 meter x 1 meter area. A pump mounted to a 100 liter water tank supplies a flow delivered at a constant pressure through the system. The spatial distribution of the simulated rainfall event was measured using 42 water cups evenly spaced throughout the 1.25 square meter area. The uniformity of the distribution was calculated with the Christiansen uniformity coefficient. Factors were rainfall accumulation (0-, 2.5-, 5-, and 10-mm) and the closing tool used to create the soil pack over the seed row (split rubber wheels, spiked wheels, and a Technotill drill). Measurement included daily emergence, penetration resistance at days 5 and 10, and bulk density in the seed row. Matric potential and soil temperature were monitored in the columns throughout the study. The 10-mm rainfall accumulation led to an increase in penetration resistance in the crust as well as a reduction in emergence. The spiked wheel closer improved emergence within the 10-mm rainfall accumulation group, but had its most significantly positive effect on emergence when paired with a light (2.5-mm accumulation) or medium (5-mm accumulation) amount of rainfall. Our trial shows that farmer options for improving stand establishment in tilled field canola production that are prone to soil crusts are limited but using a spiked wheel closer can improve emergence results
BEES AS KEY POLLINATORS UNDERSTANDING THEIR ROLES AND THE CHALLENGES THEY FACE IN THE PACIFIC NORTHWEST
Get PDFBees are ecologically and agriculturally important. However, their populations are in decline due to a combination of factors, including parasitic infestations, pesticide exposure, and habitat loss. This dissertation seeks to improve wild bee conservation through an extension publication, which alerts the public to local scale factors driving pollinator decline in the Pacific Northwest and promotes pollinator-friendly practices. Additionally, this dissertation presents an observational natural history survey of bees in the Palouse. This survey catalogues bees, the pollen they collect, their parasitic communities, and pesticides they’re exposed to in the field. Bees in this region were found to host diverse phoretic mite communities, with limited pesticide exposure. They were also found to collect pollen from a multitude of sources, congruent with other studies. The necessity of diverse ecosystems has led to the implementation of wildflower plantings in apple orchards throughout central Washington. These plantings were sampled to determine the communities of bees which utilize them. These plantings were found to promote the abundance and richness of wild bees throughout the growing season. However, orchard spaces in central Washington are heavily stocked with honey bees, which are the single most important species in pome fruit production in the US. To assess if pollination efficiency of honey bees could be enhanced with attractants, seven experiments were conducted across three years in apple and pear orchards here. Additionally, one experiment was conducted to determine if honey bees could be used to clean fruit damaging honeydew produced by pestiferous pear psylla. Honey bee attractants were not consistently found to increase visitation, and did not have an impact on fruit weight, diameter, or seed set. Attractants did not increase visits to honeydew laden trees, nor did they lead to a reduction in honeydew concentration as measured by °Brix. Despite the utilization of honey bees, prioritizing the conservation of wild pollinators is critical for the maintenance of agricultural and ecosystem stability
Two Essays on Consumer Choice of Canned Tuna Ecolabels and An Essay on Water Disconnection Theory and Nonpayment Contagion Behavior
Get PDFThere are two analyses on consumer choice of canned tuna ecolabels and an analysis on disconnection theory in this dissertation. In the first chapter, I investigate consumer preferences and willingness to pay for canned tuna ecolabels among supermarket shoppers in Jakarta, Indonesia. Despite being one of the largest tuna producers in the world, Indonesia is facing serious environmental and resource sustainability problems including overfishing and harmful fishing practices. The presence of ecolabels can potentially shift consumer preferences from non-ecofriendly products to the ecofriendly ones. I find that participants are willing to pay a price premium for local, Marine Stewardship Council (MSC), fairtrade, and dolphin-safe labels. Dolphin-safe presents the highest average premium price of 17%, whereas the other three labels exhibit 4%. The average price premium for MSC increases up to 11% towards those who are well-educated and always read labels before buying. Building on the findings of price premiums associated with ecolabels from the first chapter, the second chapter answers a question on how the presence of ecolabels affects the changes of canned tuna purchased. Using a hypothetical volumetric choice experiment (VCE), I find that all ecolabeled canned tunas are own-price elastic. The results also suggest that respondents became more sensitive to the changes in price as the number of ecolabels increased. My study examines how multiple ecolabels influence consumer behavior, price sensitivity, and demographic profiles in the Indonesian market of canned tuna. Canned tuna companies and policy makers in Indonesia could use these two studies as a reference in analyzing the feasibility and the potential of launching or adding new ecolabels on canned tuna. The third chapter discusses a different topic on water disconnection theory and nonpayment contagion behavior. In this chapter, I extend a two-stage game theory from a previous study by analyzing the interaction between a water utility and two households. Aligned with the findings from the previous study, I find that higher political and disconnection costs make the water utility less likely to disconnect, while lower moral aversion makes them more likely to ignore the payment. With two households, nonpayment is easier to occur because the moral cost of a nonpaying household decreases by half after knowing that her neighbor does not pay her bill either. I also created a new Agent-Based Model (ABM), simulating the game with many customers to capture nonpayment contagion behavior. The simulations show how disconnection threat and repayment rate affect the changes in the nonpayment rate and customers’ total debt. Finally, a water utility could use this model and adjust the provided parameters to simulate water disconnection depending on its need
CAREGIVING AND CULTURAL CONNECTEDNESS COMMUNITY PERSPECTIVES OF THE URBAN INDIGENOUS EXPERIENCE
Get PDFAlthough over 70% of the Indigenous population in the United States reside in metropolitan areas, urban Indigenous peoples have often been invisible and their experiences misrepresented in the literature (Yuan et al., 2014; Urban Indian Health, 2013). The current study centers the voices and the lived experiences of caregiving adults within the urban Indigenous community of one metropolitan area to identify what encompasses a strong sense of cultural connection, belongingness, and resource needs for families and communities to promote healing and break cycles of intergenerational trauma transmission. With the guidance of a Community Advisory Board, four talking circles, an Indigenous research method, were held with 14 adult participants who identified as urban Indigenous caregivers (i.e., parents, guardians, Elders, educators, practitioners) of children. Transcripts underwent qualitative hybrid coding, integrating both an inductive and deductive approach to reflexive thematic analysis (Braun & Clarke, 2022; Kovach, 2009; Swain, 2018). Six primary themes were identified: (1) Grounding in Identity; (2) Barriers to Belongingness and Strong Sense of Self; (3) Fostering Belongingness; (4) Caregiving Practices as specific to the urban Indigenous context; (5) Pathways for Healing; and (6) Community Needs. Each theme included respective subthemes, adding detail and specificity. Participants called for culturally and trauma-informed caregiving and healing initiatives that are inclusive of the diversity and multiplicities of urban Indigenous populations. Implications of these efforts inform strengths-based program development to promote generational healing through an Indigenous worldview