• Engineered nanocomposites in asphalt binders

      Cheraghian, G.; Wistuba, M.P.; Kiani, S.; Behnood, A.; Afrand, M.; Barron, A.R.; Arizona Institutes for Resilience (AIR), University of Arizona (De Gruyter Open Ltd, 2022)
      Recently, nanotechnology has been effectively used in the field of road pavement. Oxidation and aging of asphalt cause deterioration of road pavements and increase asphalt-related emissions. We propose an anti-aging strategy to interrupt the asphalt deterioration by using engineered clay/fumed silica nanocomposites. In this research, the morphological, chemical, thermal, mechanical, and rheological properties of nano-modified asphalt binders are meticulously analyzed in various conditions. The experiment results proved that this composite efficiently disrupts the chemical oxidation and decomposition in the mixture and reduces the aging rate. Remarkably, asphalt binder rheology experiments revealed that the addition of 0.2-0.3 wt% of nano-reinforced materials maximized their rheological resistance after short- and long-term aging. Moreover, nanoparticles improve the moisture resistance efficiency and in turn overcome the critical issue of moisture in low production temperature within the framework of warm mix asphalt technology. This cost-effective, facile, and scalable approach in warm mix asphalt mixtures can contribute to increased sustainability and lifespan of pavements and a reduction in greenhouse gas emissions. © 2022 Goshtasp Cheraghian et al., published by De Gruyter.
    • How culture, institutions, and individuals shape the evolving gender gap in science and mathematics: An equity provocation for the scientific community

      Lozano, G.I.; Department of Mathematics, Center for University Education Scholarship, The University of Arizona (De Gruyter Open Ltd, 2021)
      This essay contextualizes recently measured global gender gaps in science and mathematics within three different themes relevant for enhancing equity in science: journal peer review policies, academic service at US higher education institutions, and parental leave policies and usage. The article aims to problematize potential approaches for reducing such gender gaps, and thus build capacity to advance evidence-grounded transformative change. Framed as an equity provocation for the science community, this piece hopes to elicit productive thought and evidence-based action through informed perspective taking. The vision is not just to enhance gender equity in science and mathematics, but also to ensure the continued quality and relevance of our scientific endeavors for today's diverse and global world. © 2021 IUPAC & De Gruyter. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. For more information, please visit: http://creativecommons.org/licenses/by-nc-nd/4.0/ 2021.
    • An ultrabroadband 3D achromatic metalens

      Balli, Fatih; Sultan, Mansoor A.; Ozdemir, Aytekin; Hastings, Jeffrey Todd; College of Optical Sciences, University of Arizona (De Gruyter Open Ltd, 2021-01-25)
      We design and fabricate ultra-broadband achromatic metalenses operating from the visible into the short-wave infrared, 450-1700 nm, with diffraction-limited performance. A hybrid 3D architecture, which combines nanoholes with a phase plate, allows realization in low refractive index materials. As a result, two-photon lithography can be used for prototyping while molding can be used for mass production. Experimentally, a 0.27 numerical aperture (NA) metalens exhibits 60% average focusing efficiency and 6% maximum focal length error over the entire bandwidth. In addition, a 200 μm diameter, 0.04 NA metalens was used to demonstrate achromatic imaging over the same broad spectral range. These results show that 3D metalens architectures yield excellent performance even using low-refractive index materials, and that two-photon lithography can produce metalenses operating at visible wavelengths.