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Over the past two decades, there has been a growing body of work on wireless devices that can operate on the length scales of biological cells and even smaller. A...

Magnetic microrobots have potential applications in various fields of biomedicine, such as minimally invasive surgery, targeted diagnosis, and treatment. In this work, the crystalline properties of ZnO on twodimensional (2D) magnetic microrobot precursors were tuned by annealing at different temperatures. On this basis, zeolite-imidazole framework 8 (ZIF-8) was then synthesized on the precursor surface. Through conventional characterization studies, the results showed that the precursor tuned by annealing treatment (from 350 to 500 °C) could be used for the synthesis of ZIF-8 on microrobots with specific two-dimensional structures, thus becoming metal−organic framework (MOF)-based microrobot. Also, the optimal temperature was around 410 °C, which contributed to surface roughening of the precursor and provided more reaction sites for the growth of cubic ZIF-8 particles. The MOF-based 2D microrobots were tested for their locomotive capabilities using a three-dimensional (3D) Helmholtz coil system and were able to reach a maximum forward swimming speed of 107 μm/s under a 12 Hz rotating magnetic field of 4 mT. The steerability of the microrobots was validated through successful navigation inside a microfluidic channel. The high drug loading efficiency of the MOF-based microrobots was validated using a drug loading test. In summary, MOF-based microrobots have high drug loading capacity and strong locomotive capabilities, which suggest a strong potential for in vivo biomedical applications in hard-to-reach areas of the human body.

Magnetically-driven mobile micro/nanorobots have a significant influence on the application and development of intelligent targeted drug delivery. However, the potential risk of biological toxicity is one of the major main...

We explored the spatial and temporal characteristics of the urban forest area soundscape by setting up monitoring points (70 × 70 m grid) covering the study area, recorded a total of 52 sound sources, and the results showed that: (1) The soundscape composition of the park is dominated by natural sounds and recreational sounds. (2) The diurnal variation of sound sources is opposite to that of temperature, 6:00–9:00 is the best time for the public to perceive birdsong, and after 18:00, the park is dominated by insect chirps. (3) The PSD (power spectral density) and the SDI (soundscape diversity index) of the park are greatly affected by public recreation behaviors, and some recreation behaviors may affect the vocal behavior of organisms such as birds. (4) Spaces with high canopy density can attract more birdsong and recreational sounds in summer, and the combination of “tree + lake” can attract more birdsong. Vegetation has a significant dampening effect on traffic sound. (5) Landscape spatial elements, such as the proportion of hard ground, sky, trees, and shrubs, have a significant impact on changes in the PSD, the SDI and different kinds of sound sources. The research results provide effective data support for improving the soundscape of urban forests.