Institutional Repository
The UDSpace Institutional Repository collects and disseminates research material from the University of Delaware.
- Faculty, staff, and graduate students can deposit their research material directly into UDSpace. Faculty may use UDSpace to fulfill the University of Delaware Faculty Senate Open Access Resolution, and in many cases may use it to fulfill open access requirements from grant funding agencies.
- Departments can use UDSpace to publish or distribute their working papers, technical reports, or other research material.
- UDSpace also includes all doctoral dissertations from winter 2014 forward, and all master's theses from fall 2009 forward.
To learn more about UDSpace, and how you can make your research openly accessible to the public, visit our UDSpace Policies website.
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Recent Submissions
How manganese affects rice cadmium uptake and translocation in vegetative and mature plants
(Plant and Soil, 2024-04-19) Hu, Ruifang; Limmer, Matthew A.; Seyfferth, Angelia L.
Background and aims
Rice is prone to Cd uptake under aerobic soil conditions primarily due to the OsNramp5 Mn transport pathway. Unlike Cd, Mn availability in rice paddies decreases as redox potential increases. We tested whether increasing Mn concentrations in solution would decrease Cd accumulation in rice through competition between Mn and Cd for uptake and/or suppression of OsNramp5 expression.
Methods
Rice was grown to maturity under Mn concentrations that spanned three orders of magnitude (0.30 to 37 μM) that corresponded to free Mn2+ activities of 10–7.9 to 10–5.0 M while free Cd2+ activity was held as constant as achievable (10–10.2 to 10–10.4 M). Plant biomass and elemental concentrations were measured in roots and shoots at each stage. Fold changes in the expression of OsNramp5, OsCd1, OsHMA3, OsCCX2, and OsYSL6 genes in vegetative and grain-filling stages of rice plants were determined.
Results
Competition between Mn and Cd for root uptake and accumulation in shoots was observed at the highest concentration of Mn tested. OsNramp5 expression was significantly higher in rice plants at the vegetative stage compared to the grain-filling stage, while OsCd1 and OsHMA3 showed the opposite. Solution Mn concentrations previously thought to be tolerable by rice grown to the vegetative stage led to Mn toxicity as plants matured.
Conclusions
Mn competes with Cd during uptake into rice with OsNramp5 expression unaffected. Different translocation paths may occur for Mn and Cd within the rice plant and over the rice life cycle, with OsCCX2 correlated with shoot Cd concentration.
Moths are less attracted to light traps than they used to be
(Journal of Insect Conservation, 2024-04-19) Battles, Ian; Burkness, Eric; Crossley, Michael S.; Edwards, Collin B.; Holmstrom, Kristian; Hutchison, William; Ingerson-Mahar, Joseph; Owens, David; Owens, Avalon C.S.
As evidence of global insect declines continues to mount, insect conservationists are becoming increasingly interested in modeling the demographic history of at-risk species from long-term survey data. However, certain entomological survey methods may be susceptible to temporal biases that will complicate these efforts. Entomological light traps, in particular, may catch fewer insects today than they once did due solely to increases in anthropogenic light pollution. Here we investigate this possibility by comparing the demographic histories of corn earworm moths (Helicoverpa zea) estimated from pairs of blacklight and pheromone traps monitored at the same farms. We find a stark decline in blacklight trap efficacy over 25 years of monitoring in Delaware, USA, mirrored over 10 years of monitoring in New Jersey, USA. While the precise causes of this decline remain a subject for discussion, the practical consequences are clear: insect conservationists cannot fully rely on long-term trends from entomological light traps.
Working at the Top of Their Capabilities: How Teamwork Support Attenuates Leader Role Conflict
(Group Dynamics: Theory, Research, and Practice, 2024-01-11) Carter, Kameron M.; Astrove, Stacy L.; Firth, Brady M.; Stewart, Greg L.; Solimeo, Samantha L.
Objective: To understand whether team member support reduces team leader stress. Method: In Phase 1, we used hierarchical linear modeling with survey data and administrative records from 45 Veterans Health Administration teams (73 providers and 228 associated members) to investigate how teamwork support mitigates leader stress. In Phase 2, we adopted a parallel/simultaneous mixed methods design, utilizing open- and close-ended responses from 267 additional Veterans Health Administration providers. With the mixed methods design, we first analyzed open-ended responses using directed content analysis and hypothesis coding. Next, we transformed our codes into counts and compared them with closed-ended responses to understand whether teamwork support allows leaders to engage in work aligned with their qualifications. Results: As predicted, providers’ role conflict corresponded with decreased performance under low teamwork support, but this negative relationship was attenuated with high teamwork support as such support allows leaders to focus on tasks they are uniquely qualified to perform. Conclusions: These findings emphasize the facilitative nature of teams in supporting leaders: Followers provide teamwork support that helps leaders navigate role conflict by allowing leaders to work on tasks consistent with their qualifications.
Highlights and Implications:
- Team leaders experience greater role conflict compared to team members during team-based empowerment initiatives.
- Teamwork support from team members attenuates the negative effect of leader role conflict on performance.
- Although leaders might drive team performance, team member contributions should also be acknowledged as an important aspect of the leader–team relationship.
- Drawing from a real organizational issue, we found that having a high-functioning team allows leaders to work on tasks that align with their capabilities.
2024, 16th Issue
(Newark, Del.: Chesapeake Pub. Corp., 2024-04-19) Newark post
A novel digital lifecycle for Material-Process-Microstructure-Performance relationships of thermoplastic olefins foams manufactured via supercritical fluid assisted foam injection molding
(Polymer Engineering and Science, 2024-03-15) Pradeep, Sai Aditya; Deshpande, Amit M.; Lavertu, Pierre‐Yves; Zheng, Ting; Yerra, Veera Aditya; Shimabukuro, Yiro; Li, Gang; Pilla, Srikanth
This research significantly enhances the applicability of thermoplastic olefins (TPOs) in the automotive industry using supercritical N2 as a physical foaming agent, effectively addressing the limitations of traditional chemical agents. It merges experimental results with simulations to establish detailed material-process-microstructure-performance (MP2) relationships, targeting 5–20% weight reductions. This innovative approach labeled digital lifecycle (DLC) helps accurately predict tensile, flexural, and impact properties based on the foam microstructure, along with experimentally demonstrating improved paintability. The study combines process simulations with finite element models to develop a comprehensive digital model for accurately predicting mechanical properties. Our findings demonstrate a strong correlation between simulated and experimental data, with about a 5% error across various weight reduction targets, marking significant improvements over existing analytical models. This research highlights the efficacy of physical foaming agents in TPO enhancement and emphasizes the importance of integrating experimental and simulation methods to capture the underlying foaming mechanism to establish material-process-microstructure-performance (MP2) relationships.
Highlights
- Establishes a material-process-microstructure-performance (MP2) for TPO foams
- Sustainably produces TPO foams using supercritical (ScF) N2 with 20% lightweighting
- Shows enhanced paintability for TPO foam improved surface aesthetics
- Digital lifecycle (DLC) that predicts both foam microstructure and properties
- DLC maps process effects & microstructure onto FEA mesh for precise prediction