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Collectivity of Neutron-Rich 30,31Na Studied by Heavy-Ion Inelastic Scattering at Intermediate Energies
No full textThesis (Ph.D.)--Michigan State University. Physics - Doctor of Philosophy, 2025Within the framework of the nuclear shell model, the properties of a nucleus with a given number of protons and neutrons are governed by the occupation of the lowest energy single-particle levels allowed by the Pauli exclusion principle. The validity of this model was primarily evidenced through deviations in experimental observables, such as enhanced stability at certain proton and neutron numbers, leading to what is now known as the magic numbers. Understanding how nuclear structure evolves as a function of proton-to-neutron ratio underpins one of the primary goals of modern nuclear structure studies. In particular, the island of inversion is a neutron-rich region of the nuclear landscape where the expected shell gap between the and shells is reduced, leading to the emergence of collective phenomena. In this region, neutron-rich nuclei such as Na display ground states dominated by intruder configurations characterized by particle-hole excitations across the shell gap. Despite the evidence for dominant intruder configurations in the ground states of Na, it remains an open question as to whether the associated deformation is sufficiently robust enough to persist into their low-lying excited states. Addressing this issue is further complicated by the scarcity of data on rotational bands near the neutron drip line, where experimental challenges limit available measurements. In light of this, quantifying the reduced electric quadrupole transition strengths () to the low-lying excited states provides a sensitive probe of collective behavior, offering insight into the extent of the ground-state deformation. Particularly, procuring the transition strengths in Na within the island of inversion can reveal whether static deformation develops into the first and second excited states. Thus, it becomes paramount to accurately determine the values stemming from Coulomb excitations.This dissertation reports on the heavy-ion inelastic scattering measurement performed to investigate the reduced electric quadrupole transition strengths for low-lying excited states in Na and Na. The measurements were performed with the Coupled-Cyclotron Facility and A1900 fragment separator, with an experimental setup composed of the Gamma-ray Energy Tracking In-beam Nuclear Array (GRETINA), the TRIPLEX device, and the S800 Spectrograph. To extract the values, simultaneous measurements were carried out with Be and Ta foils separated by 25 mm, where the Be foil was utilized to constrain the nuclear contributions to the excitation cross section measured on the Ta foil. The present work details the excitation cross sections for the and states in Na, and the and in Na. These cross sections were utilized in conjunction with a coupled-channel calculation software (FRESCO) to extract the values for each excited state. The values determined from this analysis were compared to shell-model calculations utilizing three effective interactions to describe each nucleus: FSU, which assumes the promotion of two nucleons across the shell gap (i.e. pure 2-2 configuration), SDPF-M, which incorporates a mixture of particle-hole configurations between the and shells, and USDB, which serves as a reference for -shell calculations adopting a pure 0-0 configuration. The comparison between the experimental results and theoretical calculations suggests a persistence of ground-state deformation in the low-lying excited states of Na and Na.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
CHARACTERIZATION OF POSTHARVEST DISEASES, AND THEIR INTERACTION WITH IN-SEASON CERCOSPORA LEAF SPOT, IMPACTING SUGARBEET STORAGE IN MICHIGAN
No full textThesis (Ph.D.)--Michigan State University. Plant Pathology - Doctor of Philosophy, 2025Sugarbeet (Beta vulgaris) is a major agricultural crop in the United States, responsible for over half of domestic sugar production. Following harvest, sugarbeet roots grown in many regions are stored in large outdoor piles for up to 200 days before processing, making them vulnerable to postharvest degradation. Storage losses primarily occur through respiration and microbial rot, both of which reduce sucrose content and quality. Cercospora leaf spot (CLS) has been considered a potential predisposing factor for increased storage rot. In the current study, across three CLS-susceptible commercial varieties, there were no significant differences between storage rot susceptibility to any of the three tested pathogens in hand-harvested sugarbeets, regardless of CLS level, at any storage timepoint in 2020 or 2021 (P > 0.05). In studies using CLS-susceptible and -resistant germplasm and varieties, CLS effects were inconsistent and only significant in one parameter at two of six storage timepoints across years (P 0.05). These results showed that foliar CLS infection alone may not predispose beets to storage rot. Mechanical harvest, on the other hand, substantially increased disease severity across all treatments, confirming that physical damage is a more critical factor in postharvest rot than in-season foliar stress.Commercial storage facilities continue to stress anecdotal evidence of CLS impacting storability of sugar beets. To further investigate the impact of CLS on commercial storage, post-harvest symptom development was evaluated in bruised beets with relatively high or low in-season CLS severity in 2022 and 2023. Bruised and non-bruised tissue of roots of each CLS level were inoculated with known storage pathogens, and while bruising did significantly impact rot development at all timepoints (P < 0.05), CLS did not impact rate of rot development in bruised beets. To inform future breeding efforts, twelve commercial sugarbeet varieties were evaluated for their susceptibility to common storage rot pathogens across two storage seasons; Botrytis cinerea, Fusarium graminearum, and Penicillium vulpinum across two storage seasons. Roots were harvested in 2022 and 2023, sliced, and inoculated under controlled storage conditions. All varieties exhibited susceptibility to the pathogens, with B. cinerea consistently inducing the most severe rot. No variety demonstrated consistent resistance across both years and all pathogens. Interestingly, several varieties that showed minimal rot under hand-harvest conditions in 2022 developed significantly more severe symptoms following machine harvest in 2023, suggesting that mechanical damage may have a greater influence on rot development than varietal resistance alone. These findings highlight the need for broader screening efforts that incorporate diverse pathogen populations, harvest methods, and more representative storage conditions. Breeding for postharvest resistance remains a largely untapped avenue with strong potential to reduce losses and enhance the long-term storability of sugarbeet crops. A multi-year pathogen survey to identify the fungal organisms most commonly associated with storage rot in Michigan was conducted from 2020-2022 and in 2024. A focus on Penicillium spp. and Fusarium spp. collected in 2024 were further identified using DNA sequencing. Molecular analysis identified five primary Fusarium species: F. oxysporum, F. fujikuroi, F. solani, F. graminearum, and F. acuminatum, as well as one isolate of F. tricinctum. Penicillium isolates included P. expansum, P. polonicum, P. crustosum, P. paneum, and P. brasilianum. These findings emphasize that sugarbeet storage rot in Michigan is caused by a diverse, changing fungal community and that pathogen levels and type may vary by year and site. Together, this research highlights the importance of both identifying storage pathogens and understanding how field and postharvest factors interact to affect disease severity. This research contributes to ongoing efforts to reduce postharvest losses, enhance sugar yield, and support more sustainable sugarbeet production systems.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
PRAIRIE STRIPS WITHIN CROPLAND ARE REFUGES, NOT TRAPS, FOR BUTTERFLIES
No full textThesis (M.S.)--Michigan State University. Integrative Biology - Master of Science, 2025Small patch restoration of prairie habitat in crop fields provides disproportionate benefitsto natural resource conservation and biodiversity. However, creating habitat in close proximity to intensively managed crops could result in highly attractive habitat that puts species at risk of lower fitness. I tested the ecological trap potential of prairie plantings in crop fields by comparing butterfly habitat preference and fitness in agriculturally embedded prairie strips, conventionally managed crop field margins, and reference prairie habitat. I found that butterflies were attracted to prairie strips, with over 90% more eggs laid on sentinel plants in prairie strips than in conventional crop field margins or reference prairie. In addition, the predation of butterfly eggs was significantly lower in prairie strips than in reference prairie. Butterflies reared in prairie strips had 5% smaller wing lengths, but adult female egg load did not differ between treatments. Overall, prairie strips are a habitat refuge for butterflies in intensively managed agricultural landscapes, rather than ecological traps.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
CARBON-BASED MICROELECTRODE DEVELOPMENT FOR ENVIRONMENTAL MONITORING SYSTEM
No full textThesis (Ph.D.)--Michigan State University. Electrical and Computer Engineering - Doctor of Philosophy, 2025Analysis of trace-level metals in environmental samples (e.g., soil, water, and plant samples) is essential for assessing environmental quality and food safety. This dissertation reports a non-toxic, eco-friendly, and cost-effective sensing method, capable of in-situ detection of microgram per liter (\u3bcg/L) levels of heavy metal ions in plant and soil solutions using carbon-based electrodes, including carbon fiber electrodes (CFEs) and boron-doped diamond electrodes (BDDs). The electrochemical behaviors of the CFEs and BDDs were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements. As proof of principle, the CFEs and BDDs were validated for sensing selected heavy metals in buffer solutions as well as in extracted plant and soil solutions using differential pulse anodic stripping voltammetry (DP-ASV). The ideal pH range for heavy metal detection was also extensively investigated and was found to be between pH 4.0 and pH 5.0. Experimental results confirm that the CFEs were able to simultaneously measure cadmium (Cd), lead (Pb), and mercury (Hg) with a limit of detection (LOD) of 2.10 \u3bcg/L in buffer solution with an effective area (Aeff) of 0.123 cm2, showcasing good selectivity and sensitivity. On the other hand, the BDD electrodes showed simultaneous measurement of these metals with an LOD of 17.34 \u3bcg/L in buffer solution with Aeff of 0.122 mm2. Besides, BDD offers precise control over the fabrication by utilizing a microfabrication facility. Overall, the integration of these sensors with a microfluidics system lays a better foundation for long-term, in-situ, and stable electrochemical analysis for aqueous environment matrices.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
SEEDING PRACTICES FOR COOL-SEASON SOD GROWN ON PLASTIC PRODUCTION AND DOMED STADIUMS
Get PDFThesis (Ph.D.)--Michigan State University. Crop and Soil Sciences- Doctor of Philosophy, 2025The demand for natural turfgrass in professional sports is increasing due to concerns over higher injury rates associated with artificial turf. However, domed stadiums often use artificial turf because these venues host events that do not require natural grass. To provide a temporary natural turfgrass playing surface, a shallow turfgrass profile \u2013 consisting of big roll sod grown on plastic (SOP) over geocellular drainage modules \u2013 has been developed. Kentucky bluegrass (Poa pratensis L.; KBG) is a commonly used cool-season grass in SOP production for sports fields, but it faces challenges due to its slow germination, which can lead to potential soil erosion during the early stages of establishment. Perennial ryegrass (Lolium perenne L.; PRG), known for its rapid germination, may stabilize the soil while KBG is still germinating. However, the optimal seeding ratios for combining these grasses in SOP production and domed stadiums remain unclear. Three studies were conducted: the first two studies focused on SOP production at the Hancock Turfgrass Research Center in 2023 and 2024, and the third study focused on controlled environments at the FIFA Indoor Pitch Simulator Facility in 2024. The first study aimed to evaluate the effects of different KBG:PRG seeding ratios (100:0, 98:2, 96:4, 92:8, 84:16, 0:100) on cool-season SOP production. After four months, results indicated that even a small percentage of PRG significantly enhanced turfgrass cover, with the 84:16 KBG:PRG mix showing a 58% increase in tensile strength compared to the 100:0 ratio. This suggests that the 84:16 ratio is optimal for producing harvestable KBG-dominated sod in a short time frame. Unexpectedly, pure PRG (0:100) exhibited the highest turfgrass cover and tensile strength among treatments, highlighting the potential for PRG in SOP production. Hence, the second study aimed to determine the optimum PRG seeding rates (1.5, 3, 6, and 9 pure live seeds cm 122) for SOP production. Results showed that the 1.5 PLS cm 122 rate exhibited lower turfgrass coverage and shear strength at 4 weeks after seeding but higher tensile strength at 12 weeks compared to the higher seeding rates. The rates , 1.5 and 3 PLS cm 122 , were identified as optimal for balancing turfgrass coverage and sod harvestability. Lastly, the third study aimed to investigate the effects of different KBG:PRG seeding ratios (100:0, 98:2, 96:4, 92:8, 84:16, 0:100) during SOP production on turfgrass quality and performance under artificial lighting and trafficked conditions. Results indicated that traffic application significantly reduced turfgrass color and green cover, but KBG:PRG ratios showed similar performance in turfgrass color, percent green cover, maximum shear stress, and maximum displacement.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
THE IMPACT OF GRAPHENE NANOPLATELET LOADING AND UREA HARD SEGMENT FRACTION ON MORPHOLOGY AND MECHANICAL PROPERTIES OF POLYUREA NANOCOMPOSITES
Get PDFThesis (Ph.D.)--Michigan State University. Materials Science and Engineering - Doctor of Philosophy, 2025Lightweighting of automotives and ground vehicles has facilitated the use of a wide range of materials such as high strength aluminum, advanced high strength steel alloys, ceramics along with various composites based on the desired application. This inevitably leads to multi-material joints, where fusion welding process is not possible. Adhesive bonding offers an alternative to fusion welding for mixed or multi-material joints. In military ground vehicle applications, these types of multi material joints not only undergo quasistatic and fatigue loading but also high strain rate events such as a mine blast and ballistic penetration. Adhesives that exceed 10.0 MPa in shear strength and a displacement failure greater than 3.81 mm are classified as \u2018Group-1 adhesives\u2019 as they exhibit excellent stiffness-toughness balance which are needed for high strain rate applications. In this work a multidisciplinary approach (experimental and modeling) is used to elucidate the effect of the GnP on the processing (chemistry), structure (phase separation), and properties (quasi-static, and viscoelastic) relationship of PUa based nanocomposite. A model polyurea with hard segment weight fraction (HSWF) of 20, 30 and 40 percent was developed to explore the combined effect of HSWF and nano-additions of 0.5, 1.0 and 1.5 weight percent GnP on the quasi-static and viscoelastic properties. For model PUa formulation with higher HSWF the additions of GnP on quasi static tensile and viscoelastic properties were negligible but at lower HSWF some improvement was seen in the viscoelastic properties and simultaneously improvements in strength and ductility were seen. Despite the complexity of the phase separated microstructure of the PUa and the nanocomposite, time-temperature (TTS) super position was shown to be valid for both the neat PUa\u2019s and the PUa-GnP nano composite. Although the TTS shifts didn\u2019t fit Arrhenius nor the WLF models, they did fit a more recently developed two-state, two-(time) scale model. Furthermore, a micro mechanical model utilizing fractional calculus-based modeling showed excellent correlation between the experimentally obtained TTS curves and the mechanical modeling for both neat and composite PUa. The micromechanical model developed utilizes a few physical properties such as modulus and relaxation time to predict material viscoelastic behavior instead of the conventional Prony series which has a large number of parameters with no relation to material properties. The micro-mechanical model parameters were evaluated at various nano-loading and hard segment weight fraction which showed that the effect of GnP was significantly less pronounced than the effect of HSWF. In addition, Single Lap Joints were used for an initial exploration of multiple formulations from both a chemistry perspective (changing isocyanate type and diamine type) and a microstructural perspective (weight fraction of hard segments). Results indicate that Group-I adhesive with cohesive failures can be achieved with PUa, showcasing the potential of PU as an adhesive. Overall, this work supports the feasibility of utilizing PUa\u2019s in adhesive applications. The detailed characterization of PUas with varying HSWF and GnP content shows that the HSWF had a far greater effect on the properties of PUa than the additions of GnP. GnP did not have adverse or detrimental effects on the performance of the PUa. Future work can explore the advantage of GnP in creating multifunctionality to PUa such enhancing thermal and electrical conductivity. At the same time, GnP showed significant improvement in PUas with low HSWF creating a wide range of potential applications for PUa based bonded joints. Future work should also explore the high strain rate behavior of the PUa bonded joints.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references
CHARACTERIZATION OF PROMISCIOUS TERPENE BIOSYNTHETIC ENZYMES TO IDENTIFY THE SYNTHESES OF NOVEL TERPENOIDS
Get PDFThesis (Ph.D.)--Michigan State University. Biochemistry and Molecular Biology - Doctor of Philosophy, 2025The growing and aging population coupled with the demand for environmentally sustainable solutions necessitates innovative developments in pharmaceuticals and agrochemicals. Terpenoids, a diverse group of specialized metabolites, have the potential to address these mounting challenges. Chapter 1 reviews terpene biosynthesis, while the remaining chapters cover research advances that improve our understanding of plant terpene biosynthesis and its applications. These research chapters cover the characterization of multiple CYP76BK1 orthologs involved in furanoclerodane metabolism, the discovery of the notably promiscuous Ajuga reptans CYP736A358, and exploration of novel enzyme-synthetic substrate analog combinations to yield semi-synthetic products. The CYP76BK1 orthologs were shown to catalyze the production of furan and one of two distinct lactone ring moieties on primarily clerodane backbones. In contrast, CYP736A358 exhibited limited product promiscuity, yet remarkable substrate promiscuity towards diterpenes, suggesting its place as a biotechnology multi-tool. In the final chapter, evolutionarily distinct sesquiterpene synthases natively producing similar products demonstrated different preferences towards synthetic analogs of their native substrate, the products of which had varied anti-fungal activities. These findings not only underscore the enzymatic flexibility within terpene specialized metabolism but provide new tools to produce commercially relevant terpenoids.Description based on online resource. Title from PDF t.p. (Michigan State University Fedora Repository, viewed ).Includes bibliographical references