In this work, a record high thermoelectric figure‐of‐merit ZT of 1.6 ± 0.2 at 873 K in p‐type polycrystalline Bi0.94Pb0.06CuSe1.01O0.99 by a synergy of rational band manipulation and novel ...nanostructural design is reported. First‐principles density functional theory calculation results indicate that the density of state at the Fermi level that crosses the valence band can be significantly reduced and the measured optical bandgap can be enlarged from 0.70 to 0.74 eV by simply replacing 1% O with 1% Se, both indicating a potentially reduced carrier concentration and in turn, an improved carrier mobility and a boosted power factor up to 9.0 µW cm−1 K−2. Meanwhile, comprehensive characterizations reveal that under Se‐rich condition, Cu2Se secondary microphases and significant lattice distortions triggered by Pb‐doping and Se‐substitution can be simultaneously achieved, contributing to a reduced lattice thermal conductivity of 0.4 W m−1 K−1. Furthermore, a unique shear exfoliation technique enables an effective grain refinement with higher anisotropy of the polycrystalline pellet, leading to a further improved power factor up to 10.9 µW cm−1 K−2 and a further reduced lattice thermal conductivity of 0.30 W m−1 K−1, which gives rise to record high ZT.
A record high thermoelectric figure‐of‐merit ZT of 1.6 ± 0.2 at 873 K in p‐type polycrystalline Bi0.94Pb0.06CuSe1.01O0.99 by a synergy of rational band manipulation and novel nanostructural design is reported.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
In recent years, unmanned aerial vehicles (UAV) or drones have become ubiquitous in our daily lives, bringing great convenience to our lives and playing a pivotal role in future wireless networks and ...the Internet of things. One of the major problems associated with the UAV is the heterogeneous nature of such deployments; this heterogeneity poses many challenges, particularly in the areas of security and privacy. The key to solving these problems is to accurately identify and authenticate drones. In this article, a reliable UAV identify framework based on radio frequency fingerprint is proposed. First, we established a wireless signal label architecture and systematically collected, analyzed, and recorded the radio frequency signals of different UAVs in different flight modes and different distances in the telemetry link, and established UAV signal datasets. Then, the intelligent algorithm and anti-UAV system are designed by using the collected dataset, and the feasibility of the developed dataset for detecting and identifying UAVs is verified by using machine learning and deep learning. The simulation results show that under the condition of Gaussian white noise, the method based on deep learning achieves high reliability, and when the SNR is not less than 5dB, the model achieves more than 95% of the monitoring and recognition accuracy. Finally, we discussed the possible applications of the dataset in the future.
Recent researches regarding to exosomal involvement in alpha-synuclein (α-syn) transmission relating to the pathological process of Parkinson's disease (PD) have attracted considerable attention. It ...is highly desirable to make clear the diffusion process and cellular uptake of α-syn-associated exosomes and the underlying mechanism of exosomes-involved communication in the synucleinopathy pathogenesis. To determine the contribution of α-syn-associated exosomes to the initiation and progression of PD, plasma exosomes derived from PD patients were stereotaxically injected into the striatum of mice brains. Exosomes extracted from plasma diagnosed with PD contained monomeric and oligomeric α-syn. Here, we found that microglia display a high potency for uptake of plasma exosomes derived from PD patients, and therefore could be activated by exogenous exosomes in vitro and in vivo. In addition, immunofluorescent double staining verified the transfer of exogenous human exosomal α-syn to neurons. The release of human exosomal α-syn from microglia may facilitate this propagation. Finally, we described a mechanism underlying this potential role of microglia in the transmission of exosomal α-syn. Specifically, exogenous exosomes were found to dysregulate autophagy of the BV2 mouse microglia cell line with presentation of increased accumulation of intracellular α-syn and accelerated secretion of α-syn into extracellular space. These results suggest that microglia play a crucial role in the transmission of α-syn via exosomal pathways, in additional to idea that the progression of PD may be altered by the modulation of exosome secretion and/or microglial states.
Yarn supercapacitors have great potential in future portable and wearable electronics because of their tiny volume, flexibility and weavability. However, low-energy density limits their development ...in the area of wearable high-energy density devices. How to enhance their energy densities while retaining their high-power densities is a critical challenge for yarn supercapacitor development. Here we propose a coaxial wet-spinning assembly approach to continuously spin polyelectrolyte-wrapped graphene/carbon nanotube core-sheath fibres, which are used directly as safe electrodes to assembly two-ply yarn supercapacitors. The yarn supercapacitors using liquid and solid electrolytes show ultra-high capacitances of 269 and 177 mF cm(-2) and energy densities of 5.91 and 3.84 μWh cm(-2), respectively. A cloth supercapacitor superior to commercial capacitor is further interwoven from two individual 40-cm-long coaxial fibres. The combination of scalable coaxial wet-spinning technology and excellent performance of yarn supercapacitors paves the way to wearable and safe electronics.
Silicon (Si) has been considered as one of the most promising anode material for the next generation lithium-ion batteries (LIBs) with high energy densities, due to its high theoretical capacity, ...abundant availability and environmental friendliness. However, silicon materials with low intrinsic electric and ionic conductivity suffer from huge volume variation during lithiation/delithiation processes leading to the pulverization of Si and subsequently resulting in severe capacity fading of the electrodes. Coupling of Si with carbon (C) realizes a favorable combination of the two materials properties, such as high lithiation capacity of Si and excellent mechanical and conductive properties of C, making silicon/carbon composite (Si/C) ideal candidates for LIBs anodes. In this review, recent progresses of Si/C materials utilized in LIBs are summarized in terms of structural design principles, material synthesis methods, morphological characteristics and electrochemical performances by highlighting the material structures. The mechanisms behind the performance enhancement are also discussed. Moreover, other factors that affect the performance of Si/C anodes, such as prelithiation, electrolyte additives, and binders, are also discussed. We aim to present a full scope of the Si/C-based anodes, and help understand and design future structures of Si/C anodes in LIBs.
The typical silicon/carbon based anodes utilized in lithium-ion batteries with various structure and excellent performance are summarized in this review. Display omitted
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Summary
Traits are critical in predicting decomposition that fuels carbon and nutrient cycling in ecosystems. However, our understanding of root trait–decomposition linkage, and especially its ...dependence on mycorrhizal type and environmental context, remains limited.
We explored the control of morphological and chemical (carbon‐ and nutrient‐related) traits over decomposition of absorptive roots in 30 tree species associated with either arbuscular mycorrhizal (AM) or ectomycorrhizal (ECM) fungi in temperate and subtropical forests in China.
Carbon‐related traits (acid‐unhydrolysable residue (AUR) and cellulose concentrations) had predominant control of root decomposition in AM species while nutrient‐related traits (magnesium concentration) predominately controlled that in ECM species. Thicker absorptive roots decomposed faster in AM species as a result of their lower AUR concentrations, but more slowly in ECM angiosperm species potentially as a result of their higher magnesium concentrations. Root decomposition was linked to root nutrient economy in both forests while root diameter–decomposition coordination emerged only in the subtropical forest where root diameter and decomposition presented similar cross‐species variations.
Our findings suggest that root trait–decomposition linkages differ strongly with mycorrhizal type and environment, and that root diameter can predict decomposition but in opposing directions and with contrasting mechanisms for AM and ECM species.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Rock-salt structured GeTe has been reckoned as a promising medium temperature thermoelectric material due to its decent thermal conductivity and multiple electronic valence bands that can be easily ...modified. However, the applications of GeTe-based thermoelectric materials are strongly impeded by their excessive hole concentration and detrimental phase transition, which deteriorates both thermoelectric performance and mechanical robustness. In this study, we simultaneously solve these two issues by co-doping Ti and Sb in GeTe, achieving an ultrahigh figure-of-merit (ZT) of ~2.2 at 725 K with an average ZT over 2.0 plateauing from 625 to 755 K. Our X-ray spectroscopy analysis and electron microscopy investigation, coupled with first-principle calculation, attribute the extraordinary thermoelectric performance of Ge1-x-yTixSbyTe to the synergetic effects of: a) resonant bonding properties induced by symmetrized crystal lattice; b) high Seebeck coefficient and quality factor due to enhanced band degeneracy and effective mass; c) optimized hole concentration by the aliovalent TiGe and SbGe substitution; and d) minimized thermal conductivity due to the evident frequency-selective phonon scattering by diverse types of defects. Our study indicates that manipulating structure and bonding properties by crystal symmetry modification can explore new-type and high-performance thermoelectric candidates in GeTe and its derivatives, as well as other phase-transition materials.
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•Comprehensive synthesis, characterization and modelling for Ti and Sb co-doped GeTe.•Lattice symmetrisation optimizes charge and phonon transport properties in GeTe.•Significant thermoelectric figure-of-merit and efficiency in Ge1-x-yTixSbyTe.•The thermoelectric properties of Ge1-x-yTixSbyTe is rationalized by rigorous first-principle calculation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Fine roots of woody plants comprise multiple root orders, which can be functionally partitioned into two pools: absorptive fine roots (AFRs, orders 1, 2) and transport fine roots (TFRs, orders 3–5). ...However, the function-based fine-root dynamics and especially their responses to increased nitrogen (N) availability remain unclear.
We explored dynamic responses of both AFRs and TFRs of Pinus elliottii to N addition in subtropical China based on a 4-yr minirhizotron experiment and a two-stage – early (0.5 yr) vs late (4 yr) – decomposition experiment.
N addition increased the production, mortality, and turnover of AFRs but not TFRs. High rates of N persistently inhibited AFR decomposition but affected TFR decomposition differentially at the early (no effect) and late (negative effect) stages. The increased production of AFRs was driven by N-induced decrease in foliar and soil phosphorus (P) concentrations. The decreased decomposition of AFRs might be due to the increased acid-unhydrolyzable residues in decomposing roots.
AFRs are the resource-acquiring module, the increased carbon allocation to AFRs may represent
a P-acquiring strategy when N no longer limits growth of P. elliottii. Our results suggest that AFRs and TFRs respond differently to N deposition, both in terms of production, mortality, and turnover and in terms of decomposition.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
• Strategies for deep soil water acquisition (WAdeep) are critical to a species’ adaptation to drought. However, it is unknown how WAdeep determines the abundance and resource economy strategies of ...understorey shrub species.
• With data from 13 understorey shrub species in subtropical coniferous plantations, we investigated associations between the magnitude of WAdeep, the seasonal plasticity of WAdeep, midday leaf water potential (Ψmd), species abundance and resource economic traits across organs.
• Higher capacity for WAdeep was associated with higher intrinsic water use efficiency, but was not necessary for maintaining higher Ψmd in the dry season nor was it an ubiquitous trait possessed by the most common shrub species. Species with higher seasonal plasticity of WAdeep had lower wood density, indicating that fast species had higher plasticity in deep soil resource acquisition. However, the magnitude and plasticity of WAdeep were not related to shallow fine root economy traits, suggesting independent dimensions of soil resource acquisition between deep and shallow soil.
• Our results provide new insights into the mechanisms through which the magnitude and plasticity of WAdeep interact with shallow soil and aboveground resource acquisition traits to integrate the whole-plant economic spectrum and, thus, community assembly processes.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Extending the length of time series forecasting has a long-term impact on smart grid energy consumption planning, residential electricity monitoring, extreme weather warning, and other real ...applications. This article studies the reliable long-term load trend forecasting approaches in smart grid environment. In recent years, the improved neural networks models based on self-attention mechanism show good performances in many sequence tasks, but most studies focus on reducing the complexity of networks layer, and can not restrain the increase of calculation error in longer distance forecasting scenarios. Also, most models lack the ability to mine potential high-dimensional features of time series. Based on these problems, we design a reliable hierarchical self-attention model named as long-term stability network (LTSNet), which adopts a tree-shaped decomposition neural network architecture based on hierarchical residual self-attention blocks, to top-down incrementally mine high-dimensional features of temporal components. At the same time, the attention matrix is used for feature interaction at each layer, to reduce the distribution gap between time series fragments in different domains. Compared with existing study models, LTSNet maintains stable forecasting performance and speed in long-term forecasting services, achieved the most reliable multivariate and univariate forecasting results in multiple domain scenarios. Compared with the latest models, the forecasting accuracy of the proposed model is improved by 22.8% and 13.8%, respectively, covering three applications: energy consumption, residential electricity consumption, and weather forecasting. At the same time, our experiments verify that the hierarchical decomposition networks can be used as a backbone architecture to effectively extended to longer dimensional load trend forecasting scenarios.
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