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Satellites have shown free-space quantum-communication ability; however, they are orbit-limited from full-time all-location coverage. Meanwhile, practical quantum networks require satellite constellations, which are complicated and expensive, whereas the airborne mobile quantum communication may be a practical alternative to offering full-time all-location multi-weather coverage in a cost-effective way. Here, we demonstrate the first mobile entanglement distribution based on drones, realizing multi-weather operation including daytime and rainy nights, with a Clauser-Horne-Shimony-Holt S-parameter measured to be 2.41 ± 0.14 and 2.49 ± 0.06, respectively. Such a system shows unparalleled mobility, flexibility and reconfigurability compared to the existing satellite and fiber-based quantum communication, and reveals its potential to establish a multinode quantum network, with a scalable design using symmetrical lens diameter and single-mode-fiber coupling. All key technologies have been developed to pack quantum nodes into lightweight mobile platforms for local-area coverage, and arouse further technical improvements to establish wide-area quantum networks with high-altitude mobile communication.

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In this current work, a series of cellulosebased flocculants, carboxymethyl cellulose-graftpoly[(2-methacryloyloxyethyl) trimethyl ammonium chloride] (CMC-g-PDMC) with different grafting ratios were successfully synthesized. CMC-g-PDMC bears high flocculation performance in removal of an anionic dye, Acid Green 25 (AG25), at various pH conditions, which is due to improvement of both positive charge and molecular weight after modification. Moreover, the dye removal efficiency is mostly improved with the increase of grafting ratio. Among the four tested salt additives, CMC-g-PDMC exhibits good salt resistance except for sodium chloride in the measured salt concentration range. Furthermore, the image analysis in combination with fractal theory has been employed to investigate the flocs properties including floc size and fractal structure for studying the flocculation mechanism in detail. It is confirmed that charge neutralization and bridging flocculation effects both play important roles in removal of AG25 from water.