关键词：
Photonic spin Hall effect;Transverse beam shift;Tuning range;Insulating-metallic phase transition
摘要：
The photonic spin Hall effect (PSHE) can manifest as the spin-dependent splitting (perpendicular to the plane of incidence) of a light beam, i.e., transverse beam shift. Introducing dynamically tunable PSHE into post-fabricated systems has great potential for the new type of photonic devices and its tuning range can be manipulated with different reconfigurable methods. Most of these methods are based on modifying the refractive index of bulk or interface materials. However, the perturbation on the refractive index is usually small, leading to difficulty in enhancing PSHE. Fortunately, the changes in the refractive index of Vanadium Dioxide (VO2) with insulating-metallic phase transition can be larger in several orders than that of other materials, making it possible for enhancing PSHE to have greater tuning range. Here, to explore the dynamically tunable PSHE based on the insulating-metallic phase transition of VO2, the transverse beam shift (as an indicator of PSHE) was calculated with a full wave theory at a wavelength of 1550 nm in a layered structure. Without a gold layer, only the PSHE of the H-polarized beam shows significant tunability in the insulating-metallic phase transition of VO2. With the Au layer, the PSHE of the H- and V-polarized beam is enhanced around the Brewster and Brewster-like (originating from the destructive interference between the nanosized layers) angle, respectively. For H- and V-polarized beams, the tuning range of PSHE is mainly determined by the insulating phase of VO2 and can be enhanced with the Au layer. Finally, as an example, the enhanced tuning range makes the output of a two-digit binary code conversion based on PSHE easier to recognize. These results offer us possible ways to control the tuning range of PSHE in post-fabricated systems and provide more potential for new applications.
摘要：
Metal single-atom catalysts offer the dual advantages of high electrochemical activity and near 100 % metal atom utilization, leading to their potential use in low-cost electrochemical sensor development. Herein, a novel electrocatalyst comprising atomically-dispersed Mn on B,N co-doped bamboo-derived carbon (MnSAs-BN-BC) was synthesized via a facile pyrolysis procedure. A high dispersion of Mn single atoms in MnSAs-BN-BC was confirmed by aberration-corrected transmission electron microscopy and elemental mapping. The Mn loading in the MnSAs-BN-BC determined by inductively coupled plasma mass spectrometry was 255 mg kg-1. MnSAs-BNBC displayed outstanding electrocatalytic performance for levodopa (LD) oxidation, allowing a robust electrochemical sensing platform for LD detection to be established. The MnSAs-BN-BC/GCE sensing platform offered a wide LD detection range (concentrations from 2 to 683 mu M) and a very low limit of detection (LOD) of 0.45 mu M, outperforming almost all electrochemical sensors reported to date for LD sensing. The MnSAs-BN-BC/GCE platform also featured outstanding repeatability, reproducibility, selectivity, and stability. The as-developed sensing platform was successfully applied to LD quantification in commercial tablets with satisfactory recoveries (85.2-102.4 %), with the analytical precision of method validated against a traditional UV-vis spectrophotometry method. Density functional theory (DFT) calculations showed that Mn single atom sites lowered the reaction energy barrier for LD oxidation, with the favorable d-band center position of Mn single atom sites in MnSAs-BN-BC contributing to the enhanced LD sensing performance. This work encourages the use of singleatom metal catalysts in design of high-performance electrochemical sensors for the rapid detection of LD.
通讯机构：
[Feng, C ] H;Hengyang Normal Univ, Coll Geog & Tourism, Hengyang 421002, Peoples R China.
关键词：
Event-based extreme precipitation;Time distribution pattern;Contribution rate of urbanization;Xiangjiang River Basin
摘要：
An in-depth understanding of event-based extreme precipitation (EEP), emphasizing precipitation process, can help to prevent the risk posed by regional high-intensity and persistent precipitation. The concept of time distribution pattern (TDP) is used to distinguish EEPs, which classifies EEPs according to the occurrence time of extreme precipitation. Furthermore, TDP1,2,3 is that the distribution of daily precipitation above the threshold is in the first half, in the second half, and both the first half and second half of EEP, respectively. We analyze temporal characteristics, spatial distribution, future trends of EEP, and the contribution rate of urbanization to EEP in this study. EEP thresholds exhibit a latitudinal gradient from central to northern and southern regions except for Nanyue Station (NY). TDP1 and TDP2 account for more than 60% among the total of EEPs. However, TDP3 is the dominant precipitation type observed at each station from the perspective of precipitation, intensity, duration, especially, in summer. EEP is less and TDP is unstable in autumn and winter. In general, there is an increasing trend in EEP and it is predicted that the trend of EEP will continue to rise. Moreover, the contribution rate of urbanization to EEP varies significantly, with a more pronounced inhibitory effect observed. The inhibitory effect of urbanization on the frequency and duration of TDP3 reached 60.83% and 72.77%, respectively. However, it is more significant on the extreme nature of TDP1 under urbanization, with a positive contribution rate of 9.63% and 21.83% to precipitation and intensity of TDP1, respectively. The results conclude that the higher the level of urbanization, the more pronounced the extreme trend of TDP1 becomes.
摘要：
Uranium mining operations produce large volumes of acidic uranium mining wastewater, necessitating the development of environmentally friendly and recyclable materials for efficient uranium removal and recovery. The current study successfully produced hydroxyapatite (HAP-L) and magnetic phosphate composites (CaFeP-1, CaFeP-2, and FePO4) through a combination of mixing, ultrasonication, hydrothermal precipitation, and calcination methods. The research explores the influence of various parameters such as pH, solid-liquid ratio, contact time, initial uranium concentration, co-existing ions, and recyclability on the uranium removal efficiency of these materials. The findings indicate exceptional uranium adsorption capacities, with CaFeP-1 exhibiting the highest capacity among the materials, especially in acidic environments. Moreover, CaFeP-1 displays strong resistance to interference from other ions and can be recycled multiple times while maintaining high removal rates. Treatment of acidic uranium mining wastewater by CaFeP-1 results in pH adjustment and the reduction of uranium and other ion concentrations, making it a promising solution for comprehensive remediation of acidic uranium mining wastewater. The U(VI) removal mechanism by CaFeP-1 was validated through XRD, FT-IR, and XPS results. The U(VI) removal was attributed to processes such as dissolution-precipitation, surface complexation, and ion exchange. The formation of sodium uranyl phosphate hydrate was identified as a new product following U(VI) abatement by CaFeP-1. In summary, CaFeP-1 shows great potential for the effective treatment of acidic uranium mining wastewater.
摘要：
The massive collection and transmission of various crop and livestock data in smart agriculture leads to serious security concerns. Furthermore, many Internet of Things (IoT) devices in smart agriculture are battery-powered, with limited energy resources. Therefore, a low energy lightweight block cipher (LELBC) is proposed to overcome the data leakage problem during sensor data transmission in smart agriculture. Firstly, a new permutation substitution permuta-tion (PSP) structure is proposed, taking into account the energy resource constraints of unified encryption and decryption (ED) circuits. It has highly consistent encryption and decryption and a good diffusion effect. Secondly, a 4-bit low energy involutive S-box is obtained based on a genetic algorithm. The proposed S-box has lower area and latency compared to the existing S-boxes. The experimental data show that LELBC consumes 1864 gate equivalents (GE) in area and 6.99 mu J/bit in energy (encryption + decryption) under the UMC 0.18 mu m 1P6M process library. LELBC decreases energy and area consumption by 24.02% and 24.04%, respectively, compared to Midori. Finally, a temperature collection and encryption transmission platform is established. LELBC is deployed on the platform to encrypt the collected data, establishing the first line of defense for the secure transmission of smart agriculture sensor data.
期刊：
FRONTIERS IN PEDIATRICS,2024年12:1337158 ISSN：2296-2360
作者机构：
College of Physical Education, Hunan Normal University, China;School of Physical Education, Hunan First Normal University, China;School of Physical Education, Hunan University of Technology, China;English Course Group, Hengyang First High School, China;School of Physical Education and Health Sciences, Guangxi University for Nationalities, China
关键词：
24-hour movement behaviour;Externalizing problems;Internalizing problems;Light-intensity physical activity;Moderate-to-vigorous physical activity;prosocial behaviour;Sedentary behaviour;screen time
摘要：
Background: Limited research has explored the relationship between adhering to 24-h Movement Behaviour guidelines and mental health in Chinese preschool children. The objectives of this study encompassed two primary goals: (1) to investigate the adherence of preschool children in China to the 24-h Movement Behaviour guidelines; and (2) to analyze the relationship between fulfilling various combinations of these guidelines and mental health, identifying the most advantageous combination.
作者：
Li Ji;Song Sheng;Fangyuan Shen;Lili Yang;Shizhi Wen;...
期刊：
CATENA,2024年237:107816 ISSN：0341-8162
通讯作者：
Li Ji<&wdkj&>Xu Wang<&wdkj&>Lixue Yang
作者机构：
[Song Sheng; Lili Yang; Shizhi Wen; Gongxiu He] School of Forestry, Central South University of Forestry and Technology, 410004 Changsha, PR China;[Fangyuan Shen; Lixue Yang] Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education, School of Forestry, Northeast Forestry University, 150040 Harbin, PR China;Hunan Key Laboratory for Conservation and Utilization of Biological Resources in the Nanyue Mountainous Region, Hengyang Normal University, 421008 Hengyang, PR China;School of Life Science, Hengyang Normal University, 421008 Hengyang, PR China;[Xu Wang] Research Institute of Tropical Forestry, Chinese Academy of Forestry, 510520 Guangzhou, PR China
通讯机构：
[Li Ji] S;[Xu Wang] R;[Lixue Yang] K;Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education, School of Forestry, Northeast Forestry University, 150040 Harbin, PR China<&wdkj&>Research Institute of Tropical Forestry, Chinese Academy of Forestry, 510520 Guangzhou, PR China<&wdkj&>School of Forestry, Central South University of Forestry and Technology, 410004 Changsha, PR China<&wdkj&>Key Laboratory of Sustainable Forest Ecosystem Management-Ministry of Education, School of Forestry, Northeast Forestry University, 150040 Harbin, PR China
摘要：
Soil bacteria, as integral components of the soil microbial community, play pivotal roles in biogeochemical cycles and ecosystem functions in boreal forests. The altitudinal patterns of soil bacteria have been widely reported, but their community assembly is uncertain. Here, we investigated the soil bacterial community attributes (diversity, taxonomic and functional composition, and bacterial interactions) and ecological processes associated with community assembly on Mt. Oakley in the northern Greater Khingan Mountains via Illumina MiSeq sequencing and functional annotation tools. The alpha diversity indices of the soil bacteria exhibited a progressively decreasing trend with increasing altitude across seasons. The relative abundance of the dominant bacterial taxa was more sensitive to altitude than to season. More complex (more nodes and links) bacterial interactions were detected at the lowest and highest altitudinal sites, as well as in September. The variations in the taxonomic and functional compositions of the soil bacteria induced by altitude were mainly driven by the variations in soil pH and extracellular enzyme activities. Stochastic (dispersal limitation and drift) processes largely controlled the soil bacterial community assemblages across spatiotemporal scales. The community assemblages of soil bacteria were affected by altitude-induced changes in the taxonomic composition and functional groups. Collectively, our results have significant implications for understanding bacterial biogeography and community assembly mechanisms along altitudinal gradients in boreal forest ecosystems.
通讯机构：
[Tang, LW ] H;Hengyang Normal Univ, Sch Comp Sci & Technol, Hengyang, Peoples R China.;Hunan Prov Key Lab Intelligent Informat Proc & Ap, Hengyang, Peoples R China.
摘要：
The energy epsilon(G) of a graph G is the sum of the absolute values of all eigenvalues of G. Two graphs of the same order are said to be equienergetic if their energies are equal. As pointed out by Gutman, it is not known how to systematically construct any pair of equienergetic, non-cospectral trees until now. Inspired by the research of integral trees, we proposed a construction of infinite pairs of equienergetic trees of diameter 4.
期刊：
Journal of Hydrology: Regional Studies,2024年52:101690 ISSN：2214-5818
通讯作者：
Zhang, XP
作者机构：
[Xiao, Xiong; Rao, Zhiguo; Li, Jiajie; Zhang, Xinping; Dai, Junjie; He, Xinguang; Zhang, Cicheng] Hunan Normal Univ, Coll Geog Sci, Changsha, Peoples R China.;[Xiao, Xiong; He, Xinguang; Zhang, Xinping] Hunan Normal Univ, Key Lab Geospatial Big Data Min & Applicat Hunan P, Changsha, Peoples R China.;[Liu, Na] Hengyang Normal Univ, Coll Geog & Tourism, Hengyang, Hunan, Peoples R China.
通讯机构：
[Zhang, XP ] H;Hunan Normal Univ, Coll Geog Sci, Changsha, Peoples R China.
关键词：
Stable isotopes;Seasonal origin index;Xylem water;Leaf water;Soil water
摘要：
Study region: From 2017 to 2019, xylem and leaf samples of Cinnamomum camphora were sampled and soil water samples at 0-100 cm depth were sampled 65 times simultaneously in a typical East Asian monsoon region. Study focus: The seasonal origin of plant and soil water from precipitation was inferred based on the stable isotope techniques, including the evaporation line slope (SEL) estimations and the seasonal origin index (SOI) calculation. New hydrological insights for the region: The regression SEL of leaf water was close to the theoretical SELs estimated based on the Craig-Gordon model, but xylem water and soil water showed higher regression SELs than the theoretical SELs, this may be due to the seasonality of the precipitation isotopes and evaporative fractionation. The fractionation-compensated isotopic values calculated based on the theoretical SELs of different water types were close, with the differences within 2.4%o for 618O and 20.0%o for 62H of each other, and the uncertainty of the fractionationcompensated isotopic values was low enough in the calculation of SOI. The SOI results showed that summer precipitation was more prevalent in plant and soil water, and more winter precipitation may recharge runoff when evapotranspiration demand is weak. Overall, the leaf sampling and the theoretical method have the potential to infer the seasonal water origin over a relatively long period.
作者机构：
School of Geospatial Engineering and Science, Sun Yat-sen University, Guangzhou 510275, China;Author to whom correspondence should be addressed.;[Haibo Zhang] College of Geography and Tourism, Hengyang Normal University, Hengyang 421002, China;[Jiejie Li; Fanyi Zhang] Department of Intelligent Transportation and Spatial Informatics, School of Transportation, Southeast University, Nanjing 211102, China;Key Laboratory of Safety and Risk Management on Transport Infrastructures, Ministry of Transport, PRC, Nanjing 210000, China
通讯机构：
[Mi Jiang] S;School of Geospatial Engineering and Science, Sun Yat-sen University, Guangzhou 510275, China<&wdkj&>Author to whom correspondence should be addressed.
摘要：
The accurate estimation of forest aboveground biomass is of great significance for forest management and carbon balance monitoring. Remote sensing instruments have been widely applied in forest parameters inversion with wide coverage and high spatiotemporal resolution. In this paper, the capability of different remote-sensed imagery was investigated, including multispectral images (GaoFen-6, Sentinel-2 and Landsat-8) and various SAR (Synthetic Aperture Radar) data (GaoFen-3, Sentinel-1, ALOS-2), in aboveground forest biomass estimation. In particular, based on the forest inventory data of Hangzhou in China, the Random Forest (RF), Convolutional Neural Network (CNN) and Convolutional Neural Networks Long Short-Term Memory Networks (CNN-LSTM) algorithms were deployed to construct the forest biomass estimation models, respectively. The estimate accuracies were evaluated under the different configurations of images and methods. The results show that for the SAR data, ALOS-2 has a higher biomass estimation accuracy than the GaoFen-3 and Sentinel-1. Moreover, the GaoFen-6 data is slightly worse than Sentinel-2 and Landsat-8 optical data in biomass estimation. In contrast with the single source, integrating multisource data can effectively enhance accuracy, with improvements ranging from 5% to 10%. The CNN-LSTM generally performs better than CNN and RF, regardless of the data used. The combination of CNN-LSTM and multisource data provided the best results in this case and can achieve the maximum R2 value of up to 0.74. It was found that the majority of the biomass values in the study area in 2018 ranged from 60 to 90 Mg/ha, with an average value of 64.20 Mg/ha.
通讯机构：
[Tang, ZK ] U;Univ Hunan Prov, Key Lab Micronano Energy Mat & Applicat Technol, Hengyang 421002, Peoples R China.
摘要：
Two-dimensional material-supported single metal atom catalysts have been extensively studied and proved effective in electrocatalytic reactions in recent years. In this work, we systematically investigate the OER catalytic properties of single metal atoms supported by the NiN(2) monolayer. Several typical transition metals with high single atom catalytic activity, such as Fe, Co, Ru, Rh, Pd, Ir, and Pt, were selected as catalytic active sites. The energy calculations show that transition metal atoms (Fe, Co, Ru, Rh, Pd, Ir, and Pt) are easily embedded in the NiN(2) monolayer with Ni vacancies due to the negative binding energy. The calculated OER overpotentials of Fe, Co, Ru, Rh, Pd, Ir and Pt embedded NiN(2) monolayers are 0.92 V, 0.47 V, 1.13 V, 0.66 V, 1.25 V, 0.28 V, and 0.94 V, respectively. Compared to the 0.57 V OER overpotential of typical OER noble metal catalysts IrO(2), Co@NiN(2) and Ir@NiN(2) exhibit high OER catalytic activity due to lower overpotential, especially for Ir@NiN(2). The high catalytic activity of the Ir embedded NiN(2) monolayer can be explained well by the d-band center model. It is found that the adsorption strength of the embedded TM atoms with intermediates follows a linear relationship with their d-band centers. Besides, the overpotential of the Ir embedded NiN(2) monolayer can be further reduced to 0.24 V under -2% biaxial strain. Such findings are expected to be employed in more two-dimensional material-supported single metal atom catalyzed reactions.
