1,721,041 research outputs found
Supporting data for Surface Structure Dependent Circular Dichroism in Single and Double Gyroid Metamaterials
No full textFolders are divided by the gyroid's crystallographic orientation. All of the post-processed simulation results are saved as MATLAB .mat files. Files ending in _RTA contain the gyroid's simulated reflection, transmission, and absorption spectra. Files that end in _Fields contain electric field intensity enhancement information. Additional information can be found in Cote_et_al_2022_ReadMe.txt.Data includes the processed FDTD simulation results needed to recreate the figures in "Surface Structure Dependent Circular Dichroism in Single and Double Gyroid Metamaterials". The data files include single and double gyroids' reflection, transmission, and absorption spectra, near-field electric field intensity enhancements, and the gyroid 3D models used in the FDTD simulations.Sponsorship: University of Minnesota Materials Science Research and Engineering Center Award No. DMR-1420013William, Lenart R; Ellison, Christopher J; Ferry, Vivian E; Cote, Bryan M. (2022). Supporting data for Surface Structure Dependent Circular Dichroism in Single and Double Gyroid Metamaterials. Retrieved from the University Digital Conservancy, https://doi.org/10.13020/fp2j-xr45
Sustainable Polymer Framework
No full textThis document is intended to be a framework by which members of the NSF Center for Sustainable Polymers can assess and explain their own research within the broader field of sustainable polymers.The Sustainable Polymer Framework seeks to holistically define a sustainable polymer. The intended use is for members of the NSF Center for Sustainable Polymers to be able to identify and explain how their individual research project meets this definition. The goal is to introduce an integrated systems-thinking approach that considers the interconnection of all criteria and their net impact across the environment, economy, and society.The NSF Center for Sustainable Polymers is supported by the National Science Foundation (CHE-1901635).Wissinger, Jane E.; Ellison, Christopher J.; Dichtel, William R.; Chang, Alice B.; Trotta, Jacob T.; Yang, Anna B.; Bunyard, Clayton W.. (2020). Sustainable Polymer Framework. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/211643
Data for Boundary Frustration in Double-Gyroid Thin Films
No full textAll input and output files from PSCF used to generate the data in the paper are included in this dataset, as well as the code used to process the data and generate the figures. Users should be able to replicate all results of our calculations using the PSCF software and the inputs/scripts in this dataset.We have used self-consistent field theory to predict the morphology and preferred orientation of the double-gyroid phase in thin films of AB diblock polymers. A manuscript has been submitted containing this data, and is expected to appear shortly. The data were generated using the C++ version of the open-source software PSCF (https://pscf.cems.umn.edu/). All input and output files from PSCF used to generate the data in the paper are included in this dataset, as well as the code used to process the data and generate the figures.This work was supported primarily by the National Science Foundation through the University of Minnesota MRSEC under Award Number DMR-2011401. The software development for this project was supported by NSF award OAC-2103627.Magruder, Benjamin R; Morse, David C; Ellison, Christopher J; Dorfman, Kevin D. (2024). Data for Boundary Frustration in Double-Gyroid Thin Films. Retrieved from the Data Repository for the University of Minnesota (DRUM), https://doi.org/10.13020/j4ak-ps65
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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Mobility in polymer thin films : diffusion and Marangoni driven patterning
Get PDFtextPolymer thin films are ubiquitous in a variety of everyday applications from cookware to packaging. Light can be used to both probe and manipulate the mobility of polymers in thin films. The first project involves the self-diffusion of poly(isobutyl methacrylate) (PiBMA) in thin films using fluorescence recovery after patterned photobleaching (FRAPP). PiBMA is an ideal polymer for this study because it exhibits a film thickness-independent glass transition temperature (Tg) on silicon oxide substrates in film thicknesses down to 14 nm. Since the diffusion coefficient of a polymer depends on the proximity of the experimental temperature to its Tg, nanoconfined diffusion can be measured without superimposed influence from Tg nanoconfinement effects. In this study, self-diffusion of PiBMA parallel to the confining interfaces was found to be film thickness independent to ~30 nm. The reason for the film thickness independence of the Tg of PiBMA is the balance between enhanced mobility at the free interface and hydrogen bonding with the substrate. However, when hydroxyls on the substrate are masked, the Tg of PiBMA decreases with decreasing film thickness. In this case, the diffusion coefficient increases with decreasing film thickness in a way consistent with additional distance from Tg. The second project involves a new approach for creating topographic patterns in thin films via the Marangoni effect, which describes how small variations in surface energy can promote dramatic movement of fluids. Topographic patterns created using this method are potentially useful in a variety of applications, such as the creation of soft lithography stamps. Using a photomask, surface energy gradients can be patterned into solid polymer films. Upon heating the polymer film to a liquid state the Marangoni effect causes the polymer to flow creating three-dimensional topography. This technique was first demonstrated in polystyrene, which undergoes a partial dehydrogenation of the polymer backbone upon photoexposure. However, as exposed and unexposed regions inter-diffuse the topographic features decay. A solution to this problem is to use two orthogonally acting photosensitizers in the polymer film, one for topography creation, and the other for cross-linking which stabilizes the topography at high temperature.Chemical Engineerin
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Effects of nanoconfinement on structure and properties of side-chain liquid crystalline polymers
Get PDFtextSemi-crystalline polymers have shown increased crystalline order and size when confined in multilayered films by coextrusion1. The resulting large crystals lead to dramatic improvements in gas barrier properties. Ordered polymers whose characteristics are between that of the liquid phase and the crystalline phase are known as liquid crystalline polymers. The highly ordered mesogens in liquid crystalline polymers contribute to their exceptional bulk properties. In this research, side-chain liquid crystalline polymers were confined in multilayered films, made by either multilayer coextrusion or spin coating, with a non-liquid crystalline polymer in an attempt to improve the ordering of the liquid crystalline mesogens. The liquid crystalline behavior and morphology was studied to understand the correlation between the confinement size and the properties of the multilayer films. Commercial main chain liquid crystalline polymers and hydrogen bonded liquid crystalline polymers were also explored in this research for their use in multilayer coextrusion.Chemical Engineerin
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High interaction parameter block copolymers for advanced lithography
Get PDFtextBlock copolymers demonstrate potential in next-generation lithography as a solution for overcoming the limitations of conventional lithographic techniques. Ideal block copolymer materials for this application can be synthesized on a commercial scale, have high [chi]-parameters promoting self-assembly into sub-20 nm pitch domains, have controllable alignment and orientation, and have high etch contrast between the domains for facilitating pattern transfer into the underlying substrate. Block copolymers that contain silicon in one domain are attractive for nanopatterning since they often fulfill at least three of these requirements. However, silicon-containing materials are notoriously difficult to orient in thin films due to the low surface energy of the silicon-containing block, which typically wets the free surface interface. In this work, the methodology behind material choice and the synthesis of new silicon-containing block copolymers by a variety of polymerization techniques will be described. Thin film self-assembly of the block copolymers with domains oriented perpendicular to the plane of the substrate is achieved using different solvent annealing and neutral surface treatments with thermal annealing conditions. Block copolymer patterns are transferred to the underlying substrate by reactive ion etching and directed self-assembly of the polymers is demonstrated using chemical contrast patterns. Interesting thermodynamics governing the self-assembly of block copolymers with solvent annealing will also be discussed. Finally, new amphiphilic block copolymers will be described that were created with lithographic applications in mind but that are most useful for biological applications in drug delivery.Chemical Engineerin
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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