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  1. Inertial migration of spherical particles has been investigated extensively using experiments, theory, and computational modeling. Yet, a systematic investigation of the effect of particle shape on inertial migration is still lacking. Herein, we numerically mapped the migration dynamics of a prolate particle in a straight rectangular microchannel using smoothed particles hydrodynamics (SPH). For the first time, we identified a new logrolling behavior of a prolate ellipsoidal particle in the confined channel. Our findings are especially relevant to the applications where particle shape and alignment are used for sorting and analysis, such as shape-based enrichment of microalgae, bacteria, and chromosomes.
    Free, publicly-accessible full text available October 1, 2023
  2. In this work, full 3-D numerical simulations are performed to study the combined effects of elastic and inertial forces along the Y and Z-midline of the channel. Ultimately, simulation results are compared and matched with experimental fluorescent streak images of the focusing of particles under the same parametric conditions. We reported that shear-gradient (FSG), N2-induced secondary flow transversal drag (FSF), and elastic (FEL) lift are the main forces responsible for the focusing of particles in the elasto-inertial regime.
    Free, publicly-accessible full text available October 1, 2023
  3. Free, publicly-accessible full text available September 9, 2023
  4. A. Weinberger ; W. Chen ; D.Hernández-Leo ; D., B. Chen (Ed.)
    Scientific argumentation and modeling are both core practices in learning and doing science. However, they are challenging for students. Although there is considerable literature about scientific argumentation or modeling practice in K-12 science, there are limited studies on how engaging students in modeling and scientific argumentation might be mutually supportive. This study aims to explore how 5th graders can be supported by our designed mediators as they engage in argumentation and modeling, in particular, model revision. We implemented a virtual afterschool science club to examine how our modeling tool – MEME (Model and Evidence Mapping Environment), provided evidence, peer comments, and other mediators influenced students in learning about aquatic ecosystems through developing a model. While both groups that we examined constructed strong arguments and developed good models, we show how the mediators played different roles in helping them be successful.
    Free, publicly-accessible full text available July 1, 2023
  5. Free, publicly-accessible full text available August 8, 2023
  6. Free, publicly-accessible full text available March 1, 2023
  7. Predicting the electrical properties of organic molecular crystals (OMCs) is challenging due to their complex crystal structures and electron-phonon (e-ph) interactions. Charge transport in OMCs is conventionally categorized into two limiting regimes − band transport, characterized by weak e-ph interactions, and charge hopping due to localized polarons formed by strong e-ph interactions. However, between these two limiting cases there is a less well understood intermediate regime where polarons are present but transport does not occur via hopping. Here we show a many-body first-principles approach that can accurately predict the carrier mobility in OMCs in the intermediate regime and shed light on its microscopic origin. Our approach combines a finite-temperature cumulant method to describe strong e-ph interactions with Green-Kubo transport calculations. We apply this parameter-free framework to naphthalene crystal, demonstrating electron mobility predictions within a factor of 1.5−2 of experiment between 100−300 K. Our analysis reveals that electrons couple strongly with both inter- and intramolecular phonons in the intermediate regime, as evidenced by the formation of a broad polaron satellite peak in the electron spectral function and the failure of the Boltzmann equation. Our study advances quantitative modeling of charge transport in complex organic crystals.
  8. Cyber-Physical Systems (CPS) are important components of critical infrastructure and must operate with high levels of reliability and security. We propose a conceptual approach to securing CPSs: the Cyber-Physical Immune System (CPIS), a collection of hardware and software elements deployed on top of a conventional CPS. Inspired by its biological counterpart, the CPIS comprises an independent network of distributed computing units that collects data from the conventional CPS, utilizes data-driven techniques to identify threats, adapts to the changing environment, alerts the user of any threats or anomalies, and deploys threat-mitigation strategies.
  9. Free, publicly-accessible full text available November 1, 2023