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  1. Free, publicly-accessible full text available May 1, 2025
  2. Free, publicly-accessible full text available February 1, 2025
  3. Nanolenses are gaining importance in nanotechnology, but their challenging fabrication is thwarting their wider adoption. Of particular challenge is facile control of the lens’ curvature. In this work, we demonstrate a new nanoimprinting technique capable of realizing polymeric nanolenses in which the nanolens’ curvature is optically controlled by the ultraviolet (UV) dose at the pre-curing step. Our results reveal a regime in which the nanolens’ height changes linearly with the UV dose. Computational modeling further uncovers that the polymer undergoes highly nonlinear dynamics during the UV-controlled nanoimprinting process. Both the technique and the process model will greatly advance nanoscale science and manufacturing technology. 
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  4. Low-cost, high-performance oxygen catalysts are critical for electrochemical water splitting and metal-air batteries. Herein, carbon aerogels with skeletons consisting of few-layer graphene are derived pyrolytically from a hydrogel precursor using an array of NaCl crystals as the template, exhibiting a high electrical conductivity (869 S m−1) and an ultralow mass density (11.1 mg cm−3). The deposition of NiFe layered double hydroxide (NiFeLDH) nanocolloids renders the aerogels active towards both the oxygen reduction/evolution reactions (ORR/OER), with the performances highly comparable to those of commercial benchmarks in both alkaline and neutral media. Results from operando Raman spectroscopy measurements and first principles calculations suggest that Fe(OH)3 colloids facilitate the oxidation of Ni2+, which lowers the energy barrier to 0.42 eV for OER, whereas the nitrogen-doped carbon aerogels are responsible for the ORR activity. With the composites used as bifunctional oxygen catalysts for electrochemical water splitting and rechargeable zinc-air batteries, the performances in both alkaline and neutral media are markedly better than those based on the mixture of commercial Pt/C and RuO2. Results from this study highlight the unique advantages of ultrathin graphene aerogels in the development of effective catalysts for electrochemical energy devices. 
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  5. Abstract Ultrafast control of structural and electronic properties of various quantum materials has recently sparked great interest. In particular, photoinduced switching between distinct topological phases has been considered a promising route to realize quantum computers. Here we use first-principles and effective Hamiltonian methods to show that in ZrTe 5 , lattice distortions corresponding to all three types of zone-center infrared optical phonon modes can drive the system from a topological insulator to a Weyl semimetal. Thus achieved Weyl phases are robust, highly tunable, and one of the cleanest due to the proximity of the Weyl points to the Fermi level and a lack of other carriers. We also find that Berry curvature dipole moment, induced by the dynamical inversion symmetry breaking, gives rise to various nonlinear effects that oscillate with the amplitude of the phonon modes. These nonlinear effects present an ultrafast switch for controlling the Weyltronics-enabled quantum system. 
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  6. Free, publicly-accessible full text available August 21, 2024