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Plasmonic technology offers one of the most promising solutions to achieve on-chip integration of nanoscale and fast modulation circuits using surface plasmon polaritons (SPPs) as the information carriers. However, the potential of modulation speed of plasmonic signals has not been fully tapped. In this paper, we have demonstrated the plasmonic signal can be modulated at the bandwidth of sub-GHz (>100 MHz) via the on-chip integration of tunnel junctions. We also find that the lifetime of tunnel junctions under AC conditions can be improved significantly compared with the DC counterparts, which allows us to investigate and visualize the real-time breakdown process of tunnel junctions. Our implementation of plasmonic signal modulation at sub-GHz frequency paves the way toward potential industrial applications of on-chip plasmonic circuits.

A compact electrical source capable of generating surface plasmon polaritons would represent a crucial step for on-chip plasmonic circuitry. The device fabrication of plasmonic actuator based on Au/SiO2/n++Si tunnel junction and performance have been reported in [ACS photonics, 2021, 8, 7, 1951–1960]. This work focuses on the underlying mechanisms of electroluminescence. The n-type Si samples were doped with concentrations ranging from 1.6 × 1015 cm−3 to 1.0 × 1020 cm−3. A low voltage of 1.4 V for intense light emission was achieved at the highest concentration. The electrical/spectral characteristics and energy band diagrams calculation show two distinct behaviors indicating two distinct mechanisms of light emission are at work in the heavily doped versus the lightly doped Si. In the heavily doped case, the light output is correlated to tunneling current and the subsequent conversion of surface plasmons to photons, while that for the lightly doped case is due to indirect band-to-band recombination in silicon. The results are validated by numerical simulation which indicates that the heavy doping of the n++-Si is necessary to achieve surface plasmon generation via electron tunneling due to the presence of band tail states and their effect on lowering the barrier height.

The turbine disk-drum is one of the key components of an aero-engine and its assembly is connected with high-strength refined screws. But due to the uncoordinated rotation and deformation, the screws have abnormal wear damage. Through detailed contact stress analysis of screw body and component level using the finite element method, combined with experimental observation, the mechanism of wear damage of screw surface in screws is determined. It mainly includes the following: Firstly, the finite element method is used to calculate the deformation and stress distribution of the connecting screw of the turbine disk-drum assembly. Then, after the overspeed test, the morphology of the screws disassembled from the disk-drum assembly is evaluated. It was found that the wear degree in the circumferential direction and axial direction of the screw was quite different, that is, the screw wear experiment was consistent with the finite element analysis results. Finally, the influence of different rotation states and screw tightening states on screw wear was compared and analyzed. Conclusions obtained in this paper will be helpful to improve the assembly reliability of turbine drum. [ABSTRACT FROM AUTHOR]

Wearable health monitoring sensors, when employed to monitor pulse and sweat volume in real‐time during human physical activity, serve as an effective preventative measure against abnormal health conditions, such as elevated heart rate or excessive dehydration. Herein, a dual‐functional sensor based on a sandwich structure composed of polyvinylidene fluoride hexafluoropropylene / conductive carbon black perforated film (named PCp film) and corncob sponge is designed to monitor pulse and sweat volume. The PCp film prepared by the breath figure method serves as a piezoresistive sensor with high sensitivity (0.06 kPa−1), a fast response time (0.9 ms), and high reusability for pulse monitoring. Furthermore, the PCp film has excellent water permeability (27.3 L m−2 h−1); thus, the sweat permeating through the PCp film can be absorbed by the corncob sponge. The sandwich‐structured capacitive sensor is also highly sensitive (6.021 pF nL−1) to the absorbed sweat and is highly reusable. In addition, the dual‐functional sensor is successfully integrated into a sports bracelet system to display real‐time pulse and sweat‐volume data of the wearer. This approach provides a dependable foundation for the advancement of multifunctional sensors in the field of sports monitoring. [ABSTRACT FROM AUTHOR]

Aims: General anesthesia has been used in surgical procedures for approximately 180 years, yet the precise mechanism of anesthetic drugs remains elusive. There is significant anatomical connectivity between the ventral tegmental area (VTA) and the prelimbic cortex (PrL). Projections from VTA dopaminergic neurons (VTADA) to the PrL play a role in the transition from sevoflurane anesthesia to arousal. It is still uncertain whether the prelimbic cortex pyramidal neuron (PrLPyr) and its projections to VTA (PrLPyr‐VTA) are involved in anesthesia‐arousal regulation. Methods: We employed chemogenetics and optogenetics to selectively manipulate neuronal activity in the PrLPyr‐VTA pathway. Electroencephalography spectra and burst‐suppression ratios (BSR) were used to assess the depth of anesthesia. Furthermore, the loss or recovery of the righting reflex was monitored to indicate the induction or emergence time of general anesthesia. To elucidate the receptor mechanisms in the PrLPyr‐VTA projection's impact on anesthesia and arousal, we microinjected NMDA receptor antagonists (MK‐801) or AMPA receptor antagonists (NBQX) into the VTA. Results: Our findings show that chemogenetic or optogenetic activation of PrLPyr neurons prolonged anesthesia induction and promoted emergence. Additionally, chemogenetic activation of the PrLPyr‐VTA neural pathway delayed anesthesia induction and promoted anesthesia emergence. Likewise, optogenetic activation of the PrLPyr‐VTA projections extended the induction time and facilitated emergence from sevoflurane anesthesia. Moreover, antagonizing NMDA receptors in the VTA attenuates the delayed anesthesia induction and promotes emergence caused by activating the PrLPyr‐VTA projections. Conclusion: This study demonstrates that PrLPyr neurons and their projections to the VTA are involved in facilitating emergence from sevoflurane anesthesia, with the PrLPyr‐VTA pathway exerting its effects through the activation of NMDA receptors within the VTA. [ABSTRACT FROM AUTHOR]

Three-dimensional unfavourable geology models with complex structures and various attributes have become crucial for optimal design and risk control during tunnel construction. In practical applications, it is necessary to integrate multi-source advanced prediction data, including tunnel seismic prediction data, geological radar data, and transient electromagnetic data, to perform dynamic model construction. However, due to the implicit representation of the spatial distribution of single-source data and the heterogeneity of multi-source data, existing methods mainly rely on manual interpretation to perform comprehensive analysis, causing an increase in data uncertainty and unreliable, inaccurate modelling results. Therefore, this study proposes a dynamic implicit modelling method of tunnel unfavourable geology based on multi-source data fusion using a support vector machine (SVM). This method uses the SVM to fuse multi-source data and output unfavourable geological categories, including faults, fracture zones, water-rich areas, and weak rock masses, represented as spatially continuous unfavourable geological points. A globally supported radial basis function combined with a Boolean implicit calculation is used for model construction and local adaptive update. Experiments were implemented in a deep-buried tunnel, and by comparing the results with the realistic status throughout the excavation, the accuracy and adaptive ability of the proposed modelling method were well proven. [ABSTRACT FROM AUTHOR]

Near‐infrared (NIR) radiation has demonstrated significant promise in skin tissue engineering and wound healing. However, the high cost and operational complexity associated with current specialized apparatuses have hindered their practical household use. In response to these issues, a flexible, battery‐free, wireless sensor–actuator NIR therapy system, offering real‐time physiological monitoring and active treatment to cutaneous wounds, is developed. The wound management system can be wirelessly powered, and transmits data to any near‐field communication‐compatible smartphone. The therapeutic prowess of our system for wound closure is computationally and experimentally demonstrated by promoting epithelial migration and modulating inflammation. Moreover, a novel feature is reported: the smartphone‐enabled system can precisely predict the wound stage via a temperature sensor pair, which can provide an effective timely intervention strategy for NIR wound therapy. Studies based on rat wound model successfully confirm the efficacy of the proposed strategy, showcasing a remarkable 30% enhancement in wound closure compared to control groups. The user‐friendly, effective wound management platform promises a revolutionary step toward accessible and efficient at‐home wound care. [ABSTRACT FROM AUTHOR]

Combining the nano- and macroworlds in nanophotonics is always a great challenge for manufacturing uniform plasmonic nanogratings to achieve overall extraordinary optical properties. This work reports a method to apply large-area nanostructured gratings to tune the fluorescence behavior of quantum dots (QDs). The angle-resolved spectral measurements on the Ag NPs-based nanogratings show that the transverse electric (TE) polarized incident light has suffered very little scattering, demonstrating photon energy is coupled with plasmonic energy on the Ag NP-based lines. This plasmon-induced energy transferring effect was further used to tune the plasmon-induced QD fluorescence on the nanogratings. The QDs on Ag NP-based nanogratings, exhibiting up to 5 times higher photoluminescence (PL) intensity than that on a random Ag NP-based film, are carefully characterized using PL spectroscopy. In contrast, the bare QDs directly coupled onto the nanogratings. Spectral measurements in combination with numerical simulations demonstrate that anisotropic plasmon-induced energy transfer in the nanocomposite system plays a critical role in overall fluorescent tuning. Such nanogratings exhibit multifunctionality, offering an efficient way to fabricate plasmonic nanograting-QD composites with great potential applications in plasmonic sensors, QD displays, and fluorescent spectroscopy. [ABSTRACT FROM AUTHOR]