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In order to solve the problems of difficult feature extraction and low recognition rate of radar signal at low signal-to-noise ratios, a dual channel convolutional neural network model based on Choi-Williams distribution (CWD) and multisynchrosqueezing transform (MSST) is proposed, which obtains two-dimensional time-frequency images by CWD and MSST time-frequency analyses on radar signals. Respectively, the time-frequency images are preprocessed and sequencely fed to a dual channel convolutional neural network for deep feature extraction. Finally, the features acquired by the two channels are fused, and the radar signal is classified and recognized through the convolutional neural network classifier. The simulation results show that when the signal-to-noise ratio is -10 dB, the overall recognition accuracy can reach above 96%, which is excellent at low signal-to-noise ratios.

Flexibility is a key advantage of organic solar cells (OSCs), and the power conversion efficiencies (PCEs) of flexible OSCs (FOSCs) are primarily constrained by flexible transparent electrodes (FTEs). While much attention has been devoted to the study of conductive layers on FTEs, the importance of flexible substrates in influencing the properties of FTEs and the performance of FOSCs is often overlooked. In this study, an FTE is developed using an eco‐friendly ethyl cellulose (EC) substrate and silver nanowires (AgNWs) as the conductive electrode. The FTE exhibits a high transmittance of up to 88% at 550 nm and a low sheet resistance of 17.65 Ω/□. Consequently, FOSCs based on the EC/PI FTEs achieve a remarkable PCE of 18.05%, comparable to that on the rigid ITO substrate. The flexible devices also demonstrate excellent bending and peeling durability even under extreme bending conditions. [ABSTRACT FROM AUTHOR]

Abstract Background Surgical patients are asked to fast for a sufficient duration to ensure that the amount of residual liquid in the stomach is within the safe range, thereby reducing the risk of gastric reflux perioperatively. The authors hypothesized that subjective hunger numerical rating scale (NRS) score could also help assess the process of gastric emptying and determine the amount of fluid remaining in the stomach. Methods The current study consisted of healthy volunteers recruited by advertisement and mutual introduction. Participants were asked to rate their subjective hunger feeling every 30 min after oral administration of 8 mL/kg carbohydrate nutrient solution that contained 10% maltodextrin and 2.5% sucrose. Consecutively, the gastric residual fluid was measured by magnetic resonance imagining (MRI). The Spearman’s correlation coefficient, the ROC curves and the stepwise regression were used to analyze the predictive value of NRS for the gastric emptying process. Results The cohort consisted of 29 healthy volunteers enrolled in this study. The area under ROC curves estimated by the NRS score for the gastric residual volume of 2 mL/kg, 1 mL/kg, and 0.5 mL/kg were AUC2.0 = 0.78, AUC1.0 = 0.76, and AUC0.5 = 0.72, respectively. The correlation coefficient between the NRS score and the residual liquid in the stomach was −0.57 (P

Due to the unique structural and optical anisotropy, colloidal quasi-two-dimensional nanoplatelets (NPLs) have been proposed as an important material platform for realizing quantum information technology. However, the optical and structural instability of emerging perovskite NPLs after rapid dilution is preventing such studies, along with an unknown intermediate evolution process. Herein, we investigate the photoluminescence evolution of CsPbBr3 NPLs during stepwise dilutions. Upon decreasing the concentration, a red shift of the emission peak can be observed in CsPbBr3 NPLs with different thicknesses and synthesis methods. The dilution ripening mechanism dominates this red-shifted photoluminescence, in which larger NPLs capture monomers when smaller NPLs are dissolved, and then the accumulated monomers increase the lateral size and thickness of large NPLs. Interestingly, the simple aging treatment can help improve the dilution stability of thicker NPLs of the hot-injection method. Moreover, it is confirmed that the dilution ripening effect can be suppressed by introducing PbBr2-saturated solution or exchanging pristine ligands with stronger binding ligands such as lecithin. [ABSTRACT FROM AUTHOR]

Two exotic 6‐cantilever small molecular platforms, characteristic of quite different molecular configurations of propeller and quasi‐plane, are established by extremely two‐dimensional conjugated extension. When applied in small molecular acceptors, the only two cases of CH25 and CH26 that could contain six terminals and such broad conjugated backbones have been afforded thus far, rendering featured absorptions, small reorganization and exciton binding energies. Moreover, their distinctive but completely different molecular geometries result in sharply contrasting nanoscale film morphologies. Finally, CH26 contributes to the best device efficiency of 15.41 % among acceptors with six terminals, demonstrating two pioneered yet highly promising 6‐cantilever molecular innovation platforms. [ABSTRACT FROM AUTHOR]

The T-type tee is a crucial part of liquid distribution systems and is widely used in irrigation, drainage, water delivery, and agricultural fertilizer injection, among other areas. Confluence angle, pipe diameter ratio, and flow rate ratio have been the main focus of previous research. Research on the hydraulic characteristics and resistance optimization brought about by the main-side pipe intersection's chamfering treatment is, nevertheless, incredibly rare. Optimizing the structure of the T-type tee could improve its sustainability in many aspects, such as its energy consumption, durability, and production process. In order to fill this void in the literature, the current investigation concentrated on the resistance reduction and flow properties of T-type tees by means of chamfering treatment. Using a newly proposed coefficient called the integrated local resistance coefficient, the integral flow characteristics and resistance reduction effects of T-type tees were addressed. Through the use of the verified computational fluid dynamics (CFD) method, the crossed effects of five chamfer ratios (R = 0D, 0.5D, 1D, 2D, and 3D), nine flow rate ratios (0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 0.9), and two pipe diameter ratios were examined. When the Reynolds number exceeded 3 × 105, the flow remained in the quadratic drag region, meaning that the local resistance coefficient of T-type tees was no longer dependent on the flow velocity. In both confluence and shunt conditions for equal tees, chamfering treatment was proven to be an efficient method for reducing local resistance under these conditions. For instance, following a 1D chamfering treatment on the T-type confluence tee, at a flow ratio of 0.5, the local resistance coefficients ζ1 and ζ2 dropped by 68% and 82%, respectively, in comparison to the 0D condition. The effects of resistance reduction were improved by a wider chamfer radius and a higher side pipe flow rate ratio. The highest overall performance was obtained by chamfering a T-type tee with a curvature radius of 1D, taking into account flow characteristics, sustainability, processing technology, economic cost, and promotion difficulties. The chamfering procedure produced a more noticeable reduction in resistance for unequal tees with comparable velocities in the main and side pipes when the pipe diameter ratio was greater than 0.5. [ABSTRACT FROM AUTHOR]

The concentration of microbes settled in rooms at different humidification levels (none-humidification, relative humidity is 40%, 55% and 70%) and in the humidifier storage water were investigated through experimental simulations and community analysis using a real office room as a prototype, to clarify the concentration and spatial distribution of microbes settled in winter heating rooms after ultrasonic humidification. The results show that the concentration of microbes settled indoors increases markedly after ultrasonic humidification and is closely related to the humidification level. The concentration is the largest under the medium humidification level. After 10-day humidification at medium target relative humidity (55%), the concentration of the settled bacteria (8.8x104 CFU/g) and fungi (5.9x104 CFU/g) roares to 13 times and 5 times of their original concentrations, respectively, far exceeding the standard's limitation (5x104 CFU/g) for microbes concentrations. The distribution of settled microbes shows significant spatial distribution characteristics, mainly accumulated on the floor and followed by the humidifier sprayer's leeward side, windward side, and flank side. The pathogenic bacterial genera, such as Brevundomonas spp., Legionella spp., expand fast in the water of the humidifier reservoir and are significantly correlated with the concentration of the bacteria settled indoors. [ABSTRACT FROM AUTHOR]

It is a challenge to fabricate organic solar modules with the combination of high efficiency, good stability, and green solvent treatment. To address the issue, active layer materials still play crucial roles. Herein, a non‐fullerene acceptor CH7 with the extended conjugation central unit and long‐branched side chains is reported for the fabrication of high‐performance large‐area modules. The long‐branched alkyl chains can ensure CH7 to have good solubility in non‐halogen solvent o‐xylene (OX). Meanwhile, the steric hindrance of long‐branched alkyl chains can suppress molecular excessive aggregation. The inverted structure prototype device based on PM6:CH7 and processed with OX showed a promising power conversion efficiency (PCE) of 17.49% mainly due to the favorable active layer morphology. Based on the small area device results, processed from OX, a 25.2 cm2 module is fabricated and demonstrates a high PCE of 14.42% and good photo stability with maintaining 93% of its initial efficiency after 500 h continuous illumination. Moreover, the module also shows decent thermal stability, maintaining with 82% of its original efficiency after the thermal stress at 65 °C for 500 h. [ABSTRACT FROM AUTHOR]

A large amount of mineral-generated lithium slag will be produced after extracting lithium from spodumene. However, most lithium slag has not been well utilized. In this study, lithium slag was added to MOC, and its setting time, compressive strength, water resistance, phase composition, and microscopic morphology were studied. The results showed that although lithium slag prolonged the setting time and reduced the compressive strength of MOC, its water resistance improved. When the content of lithium slag was 20 wt%, the softening coefficient of the specimen reached a maximum value, and the softening coefficients at 3, 7, and 14 days were 1.47, 1.91, and 1.51 times that of MOC without lithium slag, respectively. A microscopic morphology analysis showed that the lithium slag transformed the MOC crystals from needle-like to column-like or block-like, the crystallization range expanded, and the binding force weakened. Magnesium oxychloride cement with excellent mechanical properties and good workability was combined with magnesium slag in this paper to provide the basis for the application of magnesium slag in building materials. [ABSTRACT FROM AUTHOR]

Side chain engineering is an efficient strategy for modifying molecular properties and regulating active layer morphologies, thus improving the performance of organic solar cells (OSCs). Here, we design two acceptors, namely FEH2C8-2Cl and F3EH-2Cl, based on an acceptor F-2Cl by introducing isomerized side chains on the molecular backbones. Film absorptions, energy levels and packing behaviors of the three isomer acceptors show a considerable difference with the isomer side chains. Using PM6 as a donor, the FEH2C8-2Cl-based device affords the best power conversion efficiency (PCE) of 14.60% with a high fill factor of 79.04% owing to the more favorable active layer morphology. Moreover, the device based on FEH2C8-2Cl shows good active layer thickness tolerance with an efficiency of 12.14% at a thickness of 300 nm, which is favored for the fabrication of large area OSCs. Finally, a large area module fabricated with PM6:FEH2C8-2Cl as the active layer shows a PCE of 11.71% with an area of 25 cm2. [ABSTRACT FROM AUTHOR]

The dominant hole transport material (HTM) in state‐of‐the‐art perovskite solar cells (PSCs) is Spiro‐OMeTAD, which needs to be doped using hydrophilic dopants to improve its hole mobility and conductivity, resulting in inferior device stability. Here, we propose an effective molecular design strategy to construct dopant‐free polymer HTMs by selecting four structurally related polymers and investigating their structure–property relationship. It is found that the donor and acceptor units with longitudinal conjugate extension, such as BDT‐T and BDD, could not only enhance the planarity of the conjugated polymer backbone and tune the energy levels but also promote the face‐on orientation, resulting in superior charge extraction and transport. The optimized device utilizing dopant‐free polymer HTM shows a high open‐circuit voltage of 1.19 V and a champion efficiency of 24.04 % with greatly improved operational stability, making it among the best performance PSCs based on dopant‐free HTMs. [ABSTRACT FROM AUTHOR]

• The undirected and directed functional connectivity during awake, sedation, and anesthesia by propofol were compared based on high-density EEG data. • Propofol anesthesia induced evident reductions in the strength of functional connectivity. • Propofol anesthesia induced decreases in prefrontal to frontal, parietal to frontal, and occipital to frontal information flows. General anesthesia might disrupt neuronal network communications measured by functional connectivity (FC; undirected connectivity) and directional information flow (directed connectivity). We sought to characterize the state-dependent effects of propofol on cortico-cortical undirected and directed FC. We collected 256-channel high-density EEGs from 14 patients undergoing surgery while awake (AWA) or in propofol-induced moderate sedation (SED) or loss of consciousness (LOC) states. Using source-space EEG, we estimated neuronal oscillatory activity for 68 cortical regions of interest. FC was analyzed using the weighted phase lag index. Directed connectivity was computed using directed phase transfer entropy (dPTE) as a measure of information flow in the bilateral prefrontal, frontal, parietal, and occipital areas. FC strength evidently reduced during LOC compared with those during the AWA and SED states. The dPTE analysis showed significant propofol-induced changes in directed connectivity. In the alpha band, the prefrontal-to-frontal information flow was significantly stronger in the AWA than in the SED (p = 0.033) and LOC states (p = 0.033). The parietal-to-frontal dPTE was significantly weaker during LOC than during the AWA (p = 0.033) and SED states (p = 0.007). Finally, a loss of occipital-to-frontal connectivity occurred during LOC but not the AWA state (p = 0.001). In the beta band, the dominant occipital-to-frontal direction of information flow in the AWA state was gradually converted to a frontal-to-occipital direction during LOC. Propofol-induced unconsciousness is marked by a decrease in FC and posterior-to-anterior (feedforward) directed connectivity, which may be useful as a measure to discriminate different conscious states caused by propofol administration. The study demonstrates that propofol produces state-dependent effects on cortico-cortical undirected and directed FC, supporting the idea that propofol induces loss of consciousness may through disrupting network interactions and cortical coordination. [ABSTRACT FROM AUTHOR]

Double network hydrogels (DN gels) demonstrate extremely high strength and toughness; however, conventional DN gels are fully chemically crosslinked, which are often softening and lack self‐healing. Here, a new type of fully physical DN (P‐DN) gels, that is, K+ ions crosslinked κ‐carrageenan (K+C) microgel (MG) composite hydrophobically crosslinked polyacrylamide (HPAAm) gels or K+C‐MG/HPAAm gels, in which the HPAAm gel was physically crosslinked by hydrophobic interactions as well as topologically crosslinked by P‐DN microgels, were prepared by a facile one‐pot method. At the optimal condition, K+C‐MG/HPAAm gel exhibited high strength (0.36 MPa) and high toughness (968 J/m2). In addition, it can rapidly recover from softening and display good fatigue resistance. Notably, K+C‐MG/HPAAm gel also demonstrated self‐healing properties on account of its physical nature. Because there are anionic κ‐carrageenan and KCl, K+C‐MG/HPAAm gels are ionic conductive, which were used as strain sensors to monitor the human motions. We believe our K+C‐MG/HPAAm gels provide a new insight in the field of DN gels. [ABSTRACT FROM AUTHOR]

Although organic solar cells (OSCs) have delivered an impressive power conversion efficiency (PCE) of over 19 %, most of them demonstrated rather limited stability. So far, there are hardly any effective and universal strategies to improve stability of state‐of‐the‐art OSCs. Herein, we developed a hybrid electron‐transport layer (ETL) in inverted OSCs using ZnO and a new modifying agent (NMA), and significantly improved the stability and PCEs for all the tested devices. In particular, when applied in the D18 : N3 system, its inverted OSC exhibits so far the highest PCE (18.20 %) among inverted single‐junction OSCs, demonstrating an extrapolated T80 lifetime of 7572 h (equivalent to 5 years under outdoor exposure). This is the first report with T80 over 5000 h among OSCs with over 18 % PCE. Furthermore, a high PCE of 16.12 % can be realized even in a large‐area device (1 cm2). This hybrid ETL strategy provides a strong stimulus for highly prospective commercialization of OSCs. [ABSTRACT FROM AUTHOR]

Aiming at improving the accuracy of radar signal recognition under a low signal-to-noise ratio, a radar signal recognition algorithm based both on time-frequency image and high-order spectrum feature was proposed. Firstly, the time-frequency image was obtained by Choi-Williams distribution (CWD) transform, based on which the time-frequency image was preprocessed and the texture features were extracted by gray level co-occurrence matrix (GLCM) in sequence. Meanwhile, the symmetrical holder coefficient was used to extract the high-order spectral features of the signal. Then, the texture features and high-order spectrum features were form a new set of joint feature vectors. Finally, with the proposed feature vector the classification and recognition of radar signals were implemented by a support vector machine. The algorithm was verified on the data set with eight typical radar signals. Experimental results show that the recognition accuracy of different radar signals can achieve higher than 90% when the signal-to-noise ratio is -8 dB. [ABSTRACT FROM AUTHOR]

Graphene-based metal-free aerogel is desirable for lightweight electromagnetic wave (EMW) absorbing materials. However, the weak van-der-Waals combination between graphene sheets, accompanied by the repulsion from surface oxygen-related polar groups, significantly hinder the transfer of electrons between the sheets, and lead to poor mechanical strength. These become bottlenecks for the further improvement of EMW absorption and have a huge impact on achieving multi-functions. Here, we used an iodine modification strategy to fabricate reduced graphene oxide (RGO) aerogel, in which graphene sheets are bridged by iodine cations (I+). Meanwhile, iodine promotes the conversion of epoxy groups to hydroxyl groups on graphene, thereby facilitating the adhension of I+ on the surface. These iodine cations rather than iodine anions are essential to strengthen the interconnection between graphene sheets, which enables the RGO aerogel to exhibit higher electrical conductivity, larger mechanical strength, higher thermal stability, and significantly improved EMW absorbing capability. With the improvement in conduction loss and impedance matching, the iodine-bridged RGO aerogel exhibits a maximium reflection loss of −52.8 dB and an effective absorption bandwidth of 7.2 GHz at 2 wt% filler loading, which are 3.8 and 1.5 times of pure RGO, respectively. Besides, the improved mechanical strength and resistance to temperature change benefit expanding the application fields of this aerogel. [Display omitted] [ABSTRACT FROM AUTHOR]