Flexible nanogenerators (NGs) with high power output and high efficiency have attracted extensive interests in recent years. Herein, we report highly efficient, mechanoradical-based NGs based on porous carboxymethyl cellulose/poly(butyl acrylate and butyl methacrylate) (CMC/P(BA-BMA)) composite aerogel film. An open circuit voltage (Voc) of 31 V and a short circuit current (Isc) of 10 μA were achieved under a periodic stress of 0.08 MPa at 10 Hz. Meanwhile, the calculated power density was up to 3308 W m–3, which can power 11 blue light-emitting diodes (LEDs). A potential mechanism was proposed wherein the mechanoradical is generated during bond breaking of P(BA-BMA) which would lead to large number of transient dipole moments, and permanent electric dipole moments are generated by mechanoradical-induced polar groups. As a result, a potential difference would be formed between the bottom and top surface of CMC/P(BA-BMA) porous aerogel film. The finding and the proposed concept may open a new avenue to design mechanoradical-based NGs in specific applications.
Target detection task plays the most fundamental and important role in computer vision. The appearance of deep learning method has produced a positive effect on target detection, but multi-scale target detection is poor. The reasons could be attributed to two aspects; the first one is that the small target tends to contain less semantic information, which leads algorithm be hard to detect it; the other is that the sample distribution in the practical application scenarios is random, and the different-scaled target features will interfere with each other, which poses negative effect on multi-scale target detection. Based on existing technical issues, we propose an anchor-free frame for the multi-scale target detection (AFMTD) algorithm as solution. First, from the direction of feature fusion, we propose a spatial attention fusion module (SAFM), which designs same scale transformation (SST) based on Bi-FPN, strengthens the valuable information between adjacent feature layers, and suppresses interference features, improving the detection accuracy and resolution ability of targets of different scales. Then, from the direction of anchor-free frame detection, the heatmap-based multi-scale detection module (HMDM) is proposed; by introducing a scale distribution mechanism (SDM) and Heatmap-IOU (HIOU) loss function, the module allocates different targets to different corresponding feature maps, which makes the model converge faster and more accurately. Through experiments on the MS COCO dataset, our approach achieved 40.5% average precision (AP), and the AP of large, medium, and small-scale targets is 24.5%, 44.1%, and 53.9%, respectively.
Solid-state carbon dots (CDots) have great potential applications in photonics and optoelectronic devices due to their excellent optical properties, such as broad absorption bands, and tunable photoluminescence wavelengths. However, owing to the aggregation-induced quenching and thermal quenching effect, it is a challenge to achieve strong luminescent solid-state CDots with excellent thermal stability. Herein, solid-state CDots were designed and fabricated using a triple confinement nanoporous glass. The triple confinement in nanoporous glass by a highly rigid network, stable covalent bonding, and 3D spatial restriction efficiently inhibited the Föster resonance energy transfer of the CDots in the solid-state and highly confined the CDots in the nanopores and nanochannels of the nanoporous glass. The as-designed triple confined solid-state CDots exhibit dual emission wavelengths at 448 nm and 638 nm, 51 times enhanced photoluminescence intensity, and exceptional thermal stability up to 400 °C. This work provides design principles and a universal strategy to construct dual emission fluorescence materials with high photoluminescence intensity, and high thermal stability for promising applications.
A TENG with high output performance containing a high surface area polymeric β-phase PVDF aerogel is constructed. The obtained TENG can easily lights up 30 blue LEDs, which can be used as a self-powered human motion sensor.
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