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Open Access Publications from the University of California

Scholarly Works (581 results)

  • Article
IURD Policy Notes (2012)
    Cover page: Alternative Fuels, Vehicle Technologies and Urban Logistics
    • Article
    • Peer Reviewed
    Dermatology Online Journal, Volume 16, Issue 1 (2010)
      • Thesis
      • Peer Reviewed
      UC Irvine Electronic Theses and Dissertations (2015)

      Next-generation energy storage materials aim to combine the best characteristics of batteries and supercapacitors, producing devices that concurrently deliver high energy and power densities. In order to achieve this goal, the kinetics of ion and electron transport within the electrodes must be enhanced while maintaining a large volume fraction of electrolytically active material for energy storage. In this regard, the idealized electrode microstructure has been envisioned as a three-dimensional, co-continuous arrangement of percolating domains that allow for large interfacial contact between the constituent phases and low-resistance paths for ion and electron transport. In this dissertation, I report a novel method to produce this unique microstructure through the use of soft matter templates derived from bicontinuous interfacially jammed emulsion gels (bijels). These non-equilibrium soft materials inherently have a co-continuous microstructure, where two interpenetrating fluid domains are kinetically arrested through jamming of particles at the fluid-fluid interface during spinodal decomposition. The neutrally-wetting colloids adsorb to the fluid interface upon phase separation and become jammed when the interfacial area is sufficiently reduced to just accommodate them. The characteristic domain size, which establishes both the pore diameter and the internal surface area, is controlled solely through the overall colloid volume fraction and can be tuned over a wide range. Through simple chemical post processing steps, bijels are converted to electrolytically active composites. Combined, the morphological control afforded during bijel formation and our chemical processing steps allow for independent tailoring of the microstructural parameters that govern the electrode’s electrochemical performance. In this work, I present composite electrodes that I have synthesized through this route and demonstrate how their salient electrochemical characteristics are dictated by these morphological parameters, allowing for concurrent delivery of high energy and power, bridging the gap between modern batteries and supercapacitors.

        Cover page: High Energy and Power Co-­Continuous Electrodes Derived from Bijels
        • Article
        UC Irvine Law Review , Volume 1, Issue 3 (2011)
          Cover page: The Dismal History of the Laws of War
          • Article
          • Peer Reviewed
          UC Irvine Previously Published Works (2016)
          Emerging demands for national security, transportation, distributed power, and portable systems call for energy storage and conversion technologies that can simultaneously deliver large power and energy densities. To this end, here we report three-dimensional Ni/Ni(OH)2 composite electrodes derived from a new class of multi-phase soft materials with uniform, co-continuous, and tunable internal microdomains. These remarkable morphological attributes combined with our facile chemical processing techniques allow the electrode's salient morphological parameters to be independently tuned for rapid ion transport and a large volumetric energy storage capacity. Through microstructural design and optimization, our composite electrodes can simultaneously deliver energy densities equal to that of batteries and power densities equivalent to or greater than that of the best supercapacitors, bridging the gap between these modern technologies. Our synthesis procedure is robust and can be extended to a myriad of other chemistries for next generation energy storage materials.
            Cover page: Microstructural tunability of co-continuous bijel-derived electrodes to provide high energy and power densities
            • Article
            • Peer Reviewed
            Proceedings of the Annual Meeting of the Cognitive Science Society, Volume 39 (2017)
            In a comparison setting (two stimuli), we tested 4- and 6-year- old children’s generalization of novel names for objects. We manipulated the semantic distance between the two learning items (e.g., two bracelets versus a bracelet and a watch), and the semantic distance between the learning items and the test items (e.g., a pendant versus a bow tie). We tested whether smaller semantic distance between learning items would lead to more taxonomic (vs. perceptual) choices at test, than broader semantic distance during learning, especially in the case of distant test stimuli. Results revealed main effects of learning distance, of generalization distance and that only children aged 6 years benefited from broader semantic during learning at test. Four year-old children failed to generalize to far test stimuli even with semantically distant learning items. We discuss how conceptual distance during learning differentially affects generalization performance across age groups.
              Cover page: Generalizing novel names in comparison settings: Role of conceptual distance during learning and at test
              • Article
              • Peer Reviewed
              Proceedings of the Annual Meeting of the Cognitive Science Society, Volume 44 (2022)
              A common result in novel word generalization is that comparison settings (i.e., several stimuli introduced simultaneously) favor conceptualization and generalization. We investigated which type of items four-, five- and six-year-old children would choose as referents in a free-choice novel noun generalization task. We manipulated the generalization items availability at test (i.e., generalization stimuli introduced sequentially or simultaneously). We also manipulated the semantic distance between items. In a signal detection theory framework, results showed that a simultaneous presentation of generalization items improves children’s sensitivity and helps them use a neutral strategy to generalize. Conceptual distance at learning also affects generalization performance. We discuss the cognitive constraints that both types of presentation bring into the task, and how distance might impede or favor conceptual alignments.
                Cover page: How Stimuli Availability Effects Novel Noun Generalization in a Free-Choice Design.Creative Commons 'BY' version 4.0 license
                • Article
                • Peer Reviewed
                UC Davis Previously Published Works (2024)
                Salt metathesis routes to five new -N(SiMe3)2 nickel derivatives were studied to illuminate their mode of formation, structures, and spectroscopy. The reaction between NiI2 and K{N(SiMe3)2} afforded the Ni(II) and Ni(I) complexes [K][Ni{N(SiMe3)2}3] (1) and [K][Ni{N(SiMe3)2}2] (2). Dissolving 1 in tetrahydrofuran (THF) gave the Ni(II) species [K(THF)2][Ni{N(SiMe3)2}3] (3). The Ni(I) salt [K(DME)][Ni2{N(SiMe3)2}3] (4) was obtained by using NiCl2(DME) (DME = 1,2-dimethoxyethane) as the nickel source rather than NiI2. The isolation of the Ni(I) complexes 2 and 4 highlights the tendency for K{N(SiMe3)2} to function as a reducing agent. Introduction of adventitious O2 to solutions of [K][Ni{N(SiMe3)2}2] (2) gave the nickel inverse crown ether (ICE) species [K2][O(Ni{N(SiMe3)2}2)2] (5). Complex 5 is the first ICE complex of nickel and is one of four known ICE complexes for the 3d metals. The experimental results indicate that the reduced Ni(I) bis(trimethylsilyl)amides are relatively easily generated, whereas Ni(III) derivatives that might be expected from a disproportionation of a Ni(II) derivative are apparently not yet isolable by the above routes. Overall, the new species crystallize readily from the reaction mixtures, but under ambient conditions, they begin to decompose as solids within ca. 24 h, which hinders their characterization.
                  Cover page: Ni(I) and Ni(II) Bis(trimethylsilyl)amides Obtained in Pursuit of the Elusive Structure of Ni{N(SiMe3)2}2.
                  • Article
                  Proceedings of the Vertebrate Pest Conference, Volume 13 (1988)
                  In 1986, the U.S. Environmental Protection Agency (EPA) initiated an effort to comply more fully with the Endangered Species Act. This effort became their "Endangered Species Protection Program.'' The possibility of such a program was forecast in 1982 when Donald A. Spencer gave a presentation to the Tenth Vertebrate Pest Conference on "Vertebrate Pest Management and Changing Times." This paper focuses on current plans for implementing the EPA's Endangered Species Protection Program as it relates to the USDA Forest Service. It analyzes the potential effects this program will have on the agency, using the pocket gopher (Thomomys spp.), strychnine, and the grizzly bear (Ursus arctos horribilis) as examples of an affected pest, pesticide, and predator.
                    Cover page: Effects of implementing EPA's endangered species protection program on national forest system lands
                    • Article
                    • Peer Reviewed
                    Proceedings of the Annual Meeting of the Cognitive Science Society, Volume 43 (2021)
                    Comparison settings (i.e. several stimuli introduced simultaneously) favor novel word learning and generalization. This study investigates the temporal dynamics of 6-year-olds solving strategies in a relational noun (e.g. “x is the dax for y”) comparison and generalization task with eye tracking data. We manipulated conceptual distance between the task’s items and recorded children’s performances and eye tracking data. We analyze and interpret solving strategies following the predictions made by two hypotheses, the Projection-First and Alignment-first. Eye tracking data clearly revealed that children, first, extract the relation from comparisons of items within a pair and search for a match for the extracted relation, which confirms the predictions of the projection-first hypothesis. Further analyses on error and correct trials suggest that errors occurred in the late, choice, phase of a trial.
                      Cover page: Children’s Generalization of Novel Relational Nouns in Comparison Contexts: An Eye Tracking AnalysisCreative Commons 'BY' version 4.0 license
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