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.


Recent Submissions

Leveraging the Dominant Pole: How Champions of an Industry-Wide Environmental Alliance Navigate Coopetition Paradoxes
(Journal of Management, 2024-05-29) Slawinski, Natalie; Smith, Wendy K.; Van der Byl, Connie A.
Companies increasingly collaborate with competitors to innovate, minimize risks, and address sustainability crises. However, these alliances often falter or fail due to challenges arising from coopetition paradoxes—contradictory yet interdependent tensions between competition and cooperation. Extant research predominantly focuses on addressing these paradoxes through seeking a stable balance between competition and cooperation; however, we lack in-depth processual understandings of how to navigate these paradoxes as they shift over time. To address this gap in the literature, we analyze longitudinal data over the 3 years it took to establish Canada’s Oil Sands Innovation Alliance (COSIA), the unlikely alliance across 13 competitive Canadian oil sands companies to improve their industry’s environmental performance. We noted the role of competition, which we label as the dominant pole—the more powerful of two paradoxical poles—and identify leveraging the dominant pole as a core mechanism for navigating intensifying coopetition paradoxes. Rather than diminishing the dominant competition pole, alliance champions leveraged competition to enable cooperation aided by a paradox mindset. These findings reorient coopetition scholarship away from seeking stability between the two forces, toward a processual understanding of how to navigate the shifting coopetition paradoxes in alliances over time.
Applicability of the Zintl Concept to Understanding the Crystal Chemistry of Lithium-Rich Germanides and Stannides
(Inorganic Chemistry, 2024-05-29) Ghosh, Kowsik; Rahman, Salina; Ovchinnikov, Alexander; Bobev, Svilen
With this contribution, we take a new, critical look at the structures of the binary phases Li5Ge2 and Li5Sn2. Both are isostructural (centrosymmetric space group R3̅m, no. 166), and in their structures, all germanium (tin) atoms are dimerized. Application of the valence rules will require the allocation of six additional valence electrons per [Ge2] or [Sn2] unit considering single covalent bonds, akin to those in the dihalogen molecules. Alternatively, four additional valence electrons per [Ge2] or [Sn2] anion will be needed if homoatomic double bonds exist, in an analogy with dioxygen. Therefore, five lithium atoms in one formula unit cannot provide the exact number of electrons, leaving open questions as to what is the nature of the chemical bonding within these moieties. Additionally, by means of single-crystal X-ray diffraction, synchrotron powder X-ray diffraction, and neutron powder diffraction, we established that the Li and Sn atoms in Li5Sn2 are partially disordered, i.e., the actual chemical formula of this compound is Li5–xSn2+x (0 < x < 0.1). The convoluted atomic bonding in the case where tin atoms partially displace lithium atoms results in the formation of larger covalently bonded fragments. Our first-principle calculations suggest that such disorder leads to electron doping. Contrary to that, both experimental and computational findings indicate that in the Li5Ge2 structure, the [Ge2] dimers are slightly oxidized, i.e., hole-doped, as a result of approximately 30% vacancies on a Li site, i.e., the actual chemical formula of this compound is Li5–xGe2 (x ≈ 0.3).
Language and LGBTQ Politics: The Effect of Changing Group Labels on Public Attitudes
(American Politics Research, 2024-05-24) Jones, Philip Edward
The labels used to describe sexual and gender minorities in the U.S. have shifted over time and become increasingly inclusive. Movement organizations have changed from describing the “lesbian, gay, and bisexual” (“LGB”) community to adding transgender (“LGBT”) and then also queer (“LGBTQ”) identities. Do these different labels affect public views of the group and support for their rights? I embedded a question wording experiment in a statewide survey, asking respondents about either LGB, LGBT, or LGBTQ people. The labels had no discernible effect on (1) support for requiring businesses to serve the group; nor (2) views of the group’s political leanings. There is no evidence that ideology and partisanship moderated these null effects: liberals and conservatives, Democrats and Republicans, were unaffected by the changing designations. This suggests public attitudes are not contingent on how the LGBTQ community is labelled, a finding with implications both for movement organizations and survey researchers.
Modeling Study on Heat Capacity, Viscosity, and Density of Ionic Liquid–Organic Solvent–Organic Solvent Ternary Mixtures via Machine Learning
(Processes, 2024-07-07) Shu, You; Du, Lei; Lei, Yang; Hu, Shaobin; Kuang, Yongchao; Fang, Hongming; Liu, Xinyan; Chen, Yuqiu
Physicochemical properties of ionic liquids (ILs) are essential in solvent screening and process design. However, due to their vast diversity, acquiring IL properties through experimentation alone is both time-consuming and costly. For this reason, the creation of prediction models that can accurately forecast the characteristics of IL and its mixtures is crucial to their application. This study proposes a model for predicting the three important parameters of the IL-organic solvent–organic solvent ternary system: density, viscosity, and heat capacity. The model incorporates group contribution (GC) and machine learning (ML) methods. A link between variables such as temperature, pressure, and molecular structure is established by the model. We gathered 2775 viscosity, 6515 density, and 1057 heat capacity data points to compare the prediction accuracy of three machine learning methods, namely, artificial neural networks (ANNs), extreme gradient boosting (XGBoost), and light gradient boosting machine (LightGBM). As can be observed from the findings, the ANN model produced the best results out of the three GC-based ML methods, even though all three produced dependable predictions. For heat capacity, the mean absolute error (MAE) of the ANN model is 1.7320 and the squared correlation coefficient (R2) is 0.9929. Regarding viscosity, the MAE of the ANN model is 0.0225 and the R2 is 0.9973. For density, the MAE of the ANN model is 7.3760 and the R2 is 0.9943. The Shapley additive explanatory (SHAP) approach was applied to the study to comprehend the significance of each feature in the prediction findings. The analysis results indicated that the R-CH3 group of the ILs, followed by the imidazolium (Im) group, had the highest impact on the heat capacity property of the ternary system. On the other hand, the Im group and the R-H group of ILs had the most effects on viscosity. In terms of density, the Im group of the ILs had the greatest effect on the ternary system, followed by the molar fraction of the organic solvent.
The Future of Mathematics Education Research: A Discussion Group
(Proceedings of the 14th International Congress on Mathematical Education, 2024-06) Bakker, Arthur; Cai, Jinfa
With help of a review study by Inglis and Foster published in Journal for Research in Mathematics Education, Jinfa Cai summarized trends in the past 50 years of mathematics education research. Next, Arthur Bakker presented a recent survey published in Educational Studies in Mathematics about the future of mathematics education research. Anna Sfard compared this survey with an earlier survey for ICMI. The presentations were discussed in the whole group, after which Jill Adler highlighted a few points she considered relevant.