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Ship-radiated noise recognition is an essential but complex task in the construction of marine information systems and marine scientific research. Ambient noise, unstable frequency shifts, and irregular multipath interference make it complicated to recognize ship-radiated noise accurately. Existing recognition methods exhibit constrained proficiency in the identification of the motion states of ships, thus leading to disappointing application performance. To effectively recognize the ship movement with less computation, this work proposes the time-frequency Swin-Transformer (TFST) network. A hierarchical self-attention module is presented to extract multilayer time-frequency features so that the TFST network could learn moving targets' features in TF representations of the noise radiated by moving targets. A scale-difference simplified architecture is designed to reduce network complexity. Experiments reveal that the TFST network outperforms the state-of-the-art convolutional neural networks (CNNs) and Transformers on two underwater acoustic data sets. Moreover, the TFST network achieves at least 1.3 times improvement compared to five state-of-the-art methods on both average accuracy (OA) and kappa coefficient in three motion status recognition experiments.

Fluorescent silicon nanodots have shown great prospects for bioimaging and biosensing applications. Although various fluorescent silicon-containing nanodots (SiNDs) have been developed, there are few reports about renal-clearable multicolor SiNDs. Herein, renal-clearable multicolor fluorescent SiNDs are synthesized by using silane molecules and organic dyes through a facile one-step hydrothermal method. The fluorescence of the resulting SiNDs can be tuned to blue (bSiNDs), green (gSiNDs), and red (rSiNDs) by simply changing the categories of silane reagents or dye molecules. The as-prepared SiNDs exhibit strong fluorescence with a quantum yield up to 72%, excellent photostability, and good biocompatibility with 12 h renal clearance rate as high as 86% ID. These properties enabled the SiNDs for tumor fluorescence imaging and H2O2imaging in living cells and tissue through in situ reduction reaction-lighted fluorescence of the nanoprobe. Our results provide an invaluable methodology for the synthesis of renal-clearable multicolor SiNDs and their potential applications for fluorescence imaging and biomarker sensing. These SiNDs are also promising for various biological and biomedical applications.