Abstract-As battery-powered mobile devices become more popular and energy hungry, wireless power transfer technology receives intensive interests, as it allows the power to be transferred from a charger to ambient devices wirelessly. The existing studies mainly focus on the power transfer efficiency but overlook the health impairments caused by RF exposure. In this paper, we study the Safe Charging Problem (SCP) of scheduling power chargers so that more energy can be received while no location in the field has electromagnetic radiation (EMR) exceeding a given threshold Rt. We prove that SCP is NP-hard and propose a solution which provably outperforms the optimal solution to SCP with a relaxed EMR threshold (1 − )Rt. Testbed results based on 8 Powercast TX91501 chargers validate our results. Extensive simulation results show that the gap between our solution and the optimal one is only 6.7% when = 0.1, while a naive greedy algorithm is 34.6% below our solution.

Regenerable nanozymes with high catalytic stability and sustainability are promising substitutes for naturally-occurring enzymes but are limited by insufficient and non-selective catalytic activities. Herein, we developed single-atom nanozymes of RhN4, VN4, and Fe-Cu-N6 with catalytic activities surpassing natural enzymes. Notably, Rh/VN4 preferably forms an Rh/V-O-N4 active center to decrease reaction energy barriers and mediates a “two-sided oxygen-linked” reaction path, showing 4 and 5-fold higher affinities in peroxidase-like activity than the FeN4 and natural horseradish peroxidase. Furthermore, RhN4 presents a 20-fold improved affinity in the catalase-like activity compared to the natural catalase; Fe-Cu-N6 displays selectivity towards the superoxide dismutase-like activity; VN4 favors a 7-fold higher glutathione peroxidase-like activity than the natural glutathione peroxidase. Bioactive sutures with Rh/VN4 show recyclable catalytic features without apparent decay in 1 month and accelerate the scalp healing from brain trauma by promoting the vascular endothelial growth factor, regulating the immune cells like macrophages, and diminishing inflammation.

Natural enzymes are efficient and versatile biocatalysts but suffer in their environmental tolerance and catalytic stability. As artificial enzymes, nanozymes can improve the catalytic stability, but it is still a challenge to achieve high catalytic activity. Here, we employed atomic engineering to build the artificial enzyme named Au24Ag1 clusterzyme that hosts an ultrahigh catalytic activity as well as strong physiological stability via atom manipulation. The designed Au24Ag1 clusterzyme activates the Ag–S active site via lattice expansion in the oligomer atom layer, showing an antioxidant property 72 times higher than that of natural antioxidant Trolox. Enzyme-mimicked studies find that Au24Ag1 clusterzyme exhibits high catalase-like (CAT-like) and glutathione peroxidase-like (GPx-like) activity with a maximum reaction rate of 68.9 and 17.8 μM/min, respectively. Meanwhile, the unique catalytic landscape exhibits distinctive reactions against inflammation by inhibiting the cytokines at an early stage in the brain. Atomic engineering of clusterzymes provides a powerful and attractive platform with satisfactory atomic dispersion for tailoring biocatalysts freely at the atomic level.

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NIR-II imaging is developed rapidly for noninvasive deep tissue inspection with high spatio-temporal resolution, taking advantage of diminished autofluorescence and light attenuation. Activatable NIR‐II fluorescence probes are widely developed to report pathological changes with accurate targeting, among which organic fluorescent probes achieve significant progress. Furthermore, the activatable NIR‐II fluorescent probes exhibited appealing characteristics like tunable physicochemical and optical properties, easy processability, and excellent biocompatibility. In the present review, we highlight the advances of activatable NIR-II fluorescence probes in design, synthesis and applications for imaging pathological changes like reactive oxygen species (ROS), reactive nitrogen species (RNS), reactive sulfur species (RSS), pH, hypoxia, viscosity as well as abnormally expressed enzymes. This non-invasive optical imaging modality shows a promising prospect in targeting the pathological site and is envisioned for potential clinical translation.

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