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Convolutional neural network (CNN)-based and Transformer-based methods for hyperspectral image (HSI) classification have rapidly advanced due to their unique characterization capabilities. However, the fixed kernel sizes in convolutional layers limit the comprehensive utilization of multi-scale features in HSI land cover analysis, while the Transformer's multi-head self-attention (MHSA) mechanism faces challenges in effectively encoding feature information across various dimensions. To tackle this issue, this article introduces an HSI classification method, based on multi-scale convolutional features and multi-attention mechanisms (i.e., MSCF-MAM). Firstly, the model employs a multi-scale convolutional module to capture features across different scales in HSIs. Secondly, to enhance the integration of local and global channel features and establish long-range dependencies, a feature enhancement module based on pyramid squeeze attention (PSA) is employed. Lastly, the model leverages a classical Transformer Encoder (TE) and linear layers to encode and classify the transformed spatial–spectral features. The proposed method is evaluated on three publicly available datasets—Salina Valley (SV), WHU-Hi-HanChuan (HC), and WHU-Hi-HongHu (HH). Extensive experimental results have demonstrated that the MSCF-MAM method outperforms several representative methods in terms of classification performance. [ABSTRACT FROM AUTHOR]

Objective: To evaluate and compare the image quality of T2-weighted abdominal scans using a respiratory belt trigger (RBT) and frequency- modulated continuous wave (FMCW)-trigger (FT) techniques and to explore the feasibility of FT in abdominal magnetic resonance imaging (MRI). Methods: The study prospectively included 28 subjects, each undergoing abdominal scans with both RBT and FT. The analysis focused on 64 inconsistent trigger segments from the respiratory curves triggered by RBT and FMCW. Parameters such as inconsistent trigger type (ITT), number of inconsistent trigger points (ITPs), ratio of ITP (ITR), and single-segment ITR (SITR) were derived from these curves. Image quality was evaluated by two observers using subjective scoring, signal-to-noise ratio (SNR), and contrast- to-noise ratio (CNR). The assessments classified image quality as either "good" or "poor." Consistency in image quality assessment between observers was determined using the kappa test and intraclass correlation coefficient (ICC). The chi-square test, Student's t-test, and the Mann-Whitney U test were employed to compare the categorical and continuous variables between the RBT and FT groups. Results: The observers showed a high level of agreement in image quality assessment. There were no significant differences in ITR, SITR, acquisition time, SNR, and CNR between the RBT and FT groups (all p > 0.05). Both subjective and objective evaluations indicated no notable difference in image quality between the two groups (p > 0.05). Conclusion: The FMCW trigger technique is a viable alternative to the traditional respiratory belt trigger in scenarios of relatively stable breathing. It offers potential benefits, such as reducing operational demands on technicians and improving MRI workflow efficiency. [ABSTRACT FROM AUTHOR]

The phase junction of nano-TiO2 plays an important role in enhancing its photocatalytic activity. However, the achievement of the green, mild and controllable synthesis of phase-junction nano-TiO2 still remains a big challenge for the large-scale preparation and application. Deep eutectic solvents (DESs) show many advantages in the green and mild preparation of highly active nanomaterials due to their low cost, high environmental friendliness, easy large-scale preparation, tailored structures and tunable properties. In this study, by sharing two H-bond acceptors with one H-bond donor, we successfully used DES as a solvent, template, inhibitor and crystalline phase control agent simultaneously to controllably synthesize heterophase-junction nano-TiO2 with different phase ratios under green and mild reaction conditions (at 180 °C for 18 h). The H2 production rate of photocatalytic water splitting with this catalyst reached up to 14.51 mmol h−1 g−1, which was 20-fold greater than that of commercial P25 TiO2 and also much higher than those of other TiO2 nanostructures. To the best of our knowledge, this rate is the highest value reported so far for photocatalytic H2 production catalyzed by sole TiO2. This higher activity was mainly attributed to the phase junctions and defects. This study will provide a new way for the green, mild, easily controllable and versatile preparation of phase-junction photocatalysts with high efficiency. [ABSTRACT FROM AUTHOR]

Copper-incorporated α-Ni(OH)2 nanoarrays with a unique hierarchical wire-on-sheet structure and local Ni3+ species are explored as efficient trifunctional electrocatalysts for urea oxidation and water electrolysis. The unique hierarchical morphology can not only provide abundant reactive sites for the in situ generation of catalytically active species for electrooxidation reactions, but also guarantee a robust and conductive skeleton for facile charge transport and offer effective buffering space for the volume change during the Ni2+-to-Ni3+ pre-oxidation process. Besides, the presence of local Ni3+ ions and the optimal Cu concentration further enhance the electrooxidation behaviors such as the UOR and OER, and the role of the Cu dopant in boosting the HER activity toward long-term operation is illustrated as the generation of low-valence Cu that could effectively facilitate the electron transfer process. As a result, remarkable UOR, HER and OER performance can be achieved with the synergistic benefits of large surface area, enhanced charge transfer and robust structural stability, which can be beneficial for electrolytic cells for efficient coupled urea electrolysis and overall water splitting. [ABSTRACT FROM AUTHOR]

NIR light induced H2 evolution was realized by metal-free photocatalysis for the first time. The considerable H2 production at 808 nm and large promotion of the photocatalytic activity in both UV-Vis and Vis regions originated from the synergistic effect on spectral and electronic coupling of g-C3N4 nanosheets and carbon quantum dots. [ABSTRACT FROM AUTHOR]

The ever-growing requirement of ammonia for industry and energy supply motivates people to find clean and cost-effective alternatives to overcome the shortcomings of the century-old Haber-Bosch process. Electrocatalytic N 2 reduction (NRR) is considered a prospective way for ammonia production at ambient conditions. Recently, two-dimensional (2D) metal-free materials are emerging as highly efficient and robust electrocatalysts for NRR owing to their advanced features: highly exposed surface, abundant active sites, tunable electronic states, and long-term stability compared to metal-based and bulk catalysts. In this minireview, we briefly summarize the latest edge reports on 2D metal-free materials catalyzed NRR. Also, we discuss the challenges and perspectives on the design and synthesis of novel 2D metal-free catalysts., (Copyright © 2020 Xia, Li, Liu and Tang.)

Poly-o-phenylenediamine modified TiO 2 nanocomposites were successfully synthesized via an 'in situ' oxidative polymerization method. The modified nanocomposites were characterized by BET, XRD, TEM, FT-IR, TGA, XPS, EA and UV-Vis DRS. The photocatalytic degradation of methylene blue was chosen as a model reaction to evaluate the photocatalytic activities of TiO 2 and PoPD/TiO 2 . The results indicated that PoPD/TiO 2 nanocomposites exhibited good photocatalytic activity and stability. The photocatalytic activity of PoPD/TiO 2 increased as the initial pH increased because of electrostatic adsorption between the photocatalyst and MB as well as the generation of ·OH, whereas it exhibited an earlier increasing and later decreasing trend as the concentration of the photocatalyst increased owing to the absorption of visible light. The photocatalytic stability of the PoPD/TiO 2 nanocomposite was dependent on the stability of its structure. Based on radical trapping experiments and ESR measurements, the origin of oxidizing ability of PoPD/TiO 2 nanocomposites on photocatalytic degradation of MB was proposed, which taking into account of ·OH and ·O 2 - were the first and second important ROS, respectively. The possible photocatalytic mechanism and photocatalytic activity enhanced mechanism has been proposed, taking into account the photosensitization effect and synergetic effect of TiO 2 with PoPD.

NIR light induced H2 evolution was realized by metal-free photocatalysis for the first time. The considerable H2 production at 808 nm and large promotion of the photocatalytic activity in both UV-Vis and Vis regions originated from the synergistic effect on spectral and electronic coupling of g-C3N4 nanosheets and carbon quantum dots.