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Low degradation rate for a long degradation time and poor cycle stability caused by rapid recombination of generated electron-hole pairs are tough challenges for photo-Fenton degradation The unique microstructure catalyst can provide enough catalytic surface to prevent the recombination of electron-hole pairs and facilitate the barrier-free transport of active species. In addition, the special hollow microsphere structure can effectively accelerate the Rhodamine B (RhB) penetration and the photo-Fenton process. Introducing SrWO 4 can increase oxygen vacancies and optimize the electronic structure of ZnFe 2 O 4 , thus enhancing electron transport and RhB degradation in the photo-Fenton process. This kind of catalytic material ZnFe 2 O 4 /SrWO 4 (ZFO/SW) in the photo-Fenton process can effectively degrade the 99.18 % RhB dye only within 20 min with remarkable cycling stability. This work demonstrates the high efficiency of ZFO/SW as a photocatalyst and confirms the contribution of the current design concept to the development of photo-Fenton degradation materials. [ABSTRACT FROM AUTHOR]

To achieve environmental protection, high removal rates, reusability, and degradability, a carboxymethyl-functionalized porous hydrogel P-(CM-β-CD/HPCS/KHA/AC) was synthesized with carboxymethyl cyclodextrin (CM-β-CD), hydroxypropyl chitosan (HPCS), potassium humate (KHA), and activated carbon (AC) using polyacrylic acid (PAA) as the carrier. The gel materials before and after adsorption were characterized via FTIR, TG, XRD, and XPS. Results showed high adsorption capacity for antibiotics such as tetracycline hydrochloride (TCH). P-(CM-β-CD/HPCS/KHA/AC) hydrogel exhibits optimal TCH adsorption at 298 K with 0.8 g/L of the adsorbent at pH 4, resulting in the highest adsorption capacity of up to 108.81 mg/g, a removal rate of 69%, and an adsorption equilibrium time of 150 min. The maximum swelling ratio is 100.39 times at pH 7. The theoretical values of the TCH adsorption capacity obtained using the quasi-second-order kinetic equation at 298 K, 308 K, and 318 K are 114.8106, 98.4552, and 90.4159 mg/g, respectively, corresponding to the experimental values. The adsorption behavior follows a quasi-second-order kinetic equation, which is in accordance with the Langmuir model. It is driven by electrostatic interactions, π–π conjugation reactions, hydrogen bond interactions, entropy increase, and heat absorption, resulting in a spontaneous process. The regeneration and degradability of the P-(CM-β-CD/HPCS/KHA/AC) hydrogel were tested. After five cycles of adsorption–desorption experiments, the removal rate was 50.57%. After degradation for 6 months, the weight loss rates of the P-(CM-β-CD/HPCS/KHA/AC) hydrogel in acid, water, and alkali were 45.29%, 24.90%, and 29.50%, respectively, indicating the environment-friendly nature and repeated recyclability of the hydrogel. [ABSTRACT FROM AUTHOR]

Condition-based molecular generation can generate a large number of molecules with particular properties, expanding the virtual drug screening library, and accelerating the process of drug discovery. In this study, we combined a molecular graph structure and sequential representations using a generative pretrained transformer (GPT) architecture for generating molecules conditionally. The incorporation of graph structure information facilitated a better comprehension of molecular topological features, and the augmentation of a sequential contextual understanding of GPT architecture facilitated molecular generation. The experiments indicate that our model efficiently produces molecules with the desired properties, with valid and unique metrics that are close to 100%. Faced with the typical task of generating molecules based on a scaffold in drug discovery, our model is able to preserve scaffold information and generate molecules with low similarity and specified properties. [ABSTRACT FROM AUTHOR]

Usually we call a one-dimensional singular non-CSC extremal Kähler metric HCMU metric. In this article, we will prove that there does not exist a local holomorphic isometric immersion from an HCMU metric to ℂPN for N ≥ 2. The main method is to use the metric structure equations associated with the Frenet frame along a holomorphic curve in ℂPN. [ABSTRACT FROM AUTHOR]

Motivation In the field of pharmacochemistry, it is a time-consuming and expensive process for the new drug development. The existing drug design methods face a significant challenge in terms of generation efficiency and quality. Results In this paper, we proposed a novel molecular generation strategy and optimization based on A2C reinforcement learning. In molecular generation strategy, we adopted transformer-DNN to retain the scaffolds advantages, while accounting for the generated molecules' similarity and internal diversity by dynamic parameter adjustment, further improving the overall quality of molecule generation. In molecular optimization, we introduced heterogeneous parallel supercomputing for large-scale molecular docking based on message passing interface communication technology to rapidly obtain bioactive information, thereby enhancing the efficiency of drug design. Experiments show that our model can generate high-quality molecules with multi-objective properties at a high generation efficiency, with effectiveness and novelty close to 100%. Moreover, we used our method to assist shandong university school of pharmacy to find several candidate drugs molecules of anti-PEDV. Availability and implementation The datasets involved in this method and the source code are freely available to academic users at https://github.com/wq-sunshine/MomdTDSRL.git. [ABSTRACT FROM AUTHOR]

Molecules containing a difluoromethyl group or a propargylic stereocenter are widely used in pharmaceuticals and agrochemicals, and 1,2‐functionalization of olefins is an important method for introducing the two groups into molecules simultaneously. The construction of the propargylic stereocenter with terminal alkynes usually requires bases. However, difluoromethylating agents with high reduction potentials often decompose in the presence of bases because of their acidities, and those with low reduction potentials are stable but difficult to undergo the desired single electron transfer (SET) reduction. Using the linear relationship between reduction potential differences (ΔE) and Hammett substituent constants (σ) of difluoromethyl aryl sulfones, we solved the dilemma between acidities and reduction potentials of difluoromethylating agents. Herein, we report the first enantioselective difluoromethylation‐alkynylation of olefins with difluoromethyl 4‐chlorophenyl sulfone with high enantioselectivity (>90 % ee). We also extended this asymmetric fluoroalkylation‐alkynylation reaction with other fluoroalkyl sulfones, which enabled efficient installation of trifluoromethyl, difluoroalkyl, difluorobenzyl, (benzenesulfonyl)‐difluoromethyl and monofluoromethyl groups into products. [ABSTRACT FROM AUTHOR]

Molecules containing a difluoromethyl group or a propargylic stereocenter are widely used in pharmaceuticals and agrochemicals, and 1,2‐functionalization of olefins is an important method for introducing the two groups into molecules simultaneously. The construction of the propargylic stereocenter with terminal alkynes usually requires bases. However, difluoromethylating agents with high reduction potentials often decompose in the presence of bases because of their acidities, and those with low reduction potentials are stable but difficult to undergo the desired single electron transfer (SET) reduction. Using the linear relationship between reduction potential differences (ΔE) and Hammett substituent constants (σ) of difluoromethyl aryl sulfones, we solved the dilemma between acidities and reduction potentials of difluoromethylating agents. Herein, we report the first enantioselective difluoromethylation‐alkynylation of olefins with difluoromethyl 4‐chlorophenyl sulfone with high enantioselectivity (>90 % ee). We also extended this asymmetric fluoroalkylation‐alkynylation reaction with other fluoroalkyl sulfones, which enabled efficient installation of trifluoromethyl, difluoroalkyl, difluorobenzyl, (benzenesulfonyl)‐difluoromethyl and monofluoromethyl groups into products. [ABSTRACT FROM AUTHOR]

Quantifying the predictability limits of chaotic systems and their forecast models has attracted much interest among scientists. The attractor radius (AR) and the global attractor radius (GAR), as intrinsic properties of a chaotic system, were introduced in the most recent work (Li et al. 2018). It has been shown that both the AR and GAR provide more accurate, objective metrics to access the global and local predictability limits of forecast models compared with the traditional error saturation or the asymptotic value. In this work, we consider the AR and GAR of fractional Lorenz systems, introduced in Grigorenko and Grigorenko [Phys. Rev. Lett. 91, 034101 (2003)] using the Caputo fractional derivatives and their application to the quantification of the predictability limits. A striking finding is that a fractional Lorenz system with smaller Σ , which is a sum of the orders of all involved equal derivatives, has smaller attractor radius and shorter predictability limits. In addition, we present a new numerical algorithm for the fractional Lorenz system, which is the generalized version of the standard fourth-order Runge–Kutta scheme. [ABSTRACT FROM AUTHOR]

Carbon spheres are widely used in energy storage due to their adjustable particle size, controllable shape, and variable surface physical and chemical properties. However, there are still problems such as low specific surface area and unsatisfactory ion transport kinetics in K+ storage. Although increasing the specific surface area of the active material can increase the K+ storage sites, the contact area between the active material and the electrolyte also increases, aggravating the occurrence of side reactions and the consumption of the active materials. We developed an N-doped mesoporous hollow carbon sphere with a novel morphology-a smooth exterior and wrinkled interior structure with a carbon-supported pseudo-bilayer carbon structure (IW-MHCS). Its smooth outer structure sufficiently reduces the contact area with the electrolyte, and the wrinkled inner structure effectively increases the specific surface area. The obtained IW-MHCS exhibits superior rate performance (120.6 mAh g−1 at 5 A g−1) and sufficient capacity (202.7 mAh g−1 after 800 cycles at 1 A g−1) for K+ storage. This study provides a new insight into the structural design and morphological control of high-energy-storage carbon-based materials. [Display omitted] • A novel mesoporous hollow carbon spheres (HCSs) with pseudo-bilayer structure were synthesized. • The HCSs possess a smooth exterior surface and a wrinkled interior morphology. • The optimized sample exhibited excellent potassium storage performance. • The good electrochemical performance is ascribed to the unique microstructure of HCSs. [ABSTRACT FROM AUTHOR]

To improve the electrochemical performance of the supercapacitor, three electrode nanocomposites, NiO, NiS and NiCo2S4, have been obtained by simple hydrothermal process and high temperature pyrolysis, and further, the impact of electrolytes of different concentrations on electrochemical performance of supercapacitor has been researched. During the research processing, synergistic effect of Ni, Co and S is considered to enhance the electrical conductivity, and promote electron transfer, ion diffusion and structural stability. The experiment results show that bimetallic sulfides display high electrical conductivity, shorter ion diffusion channels, and faster electron and ion transport rate with the feature of topping electrochemical properties of specific capacity, excellent cycling stability and high rate capability, and besides show that it can improve the electrochemical performance of the material by increasing the concentration of electrolyte. The transition-metal sulfides provide a new promising pathway for the expansion of high-performance electrode materials for supercapacitors. In this paper, the three-dimensional structure of NiCo2S4 nanomaterial is prepared by two-step hydrothermal method and applied to the electrode material of supercapacitor. First, the microstructure of the material is analyzed through physical characterization, and then its electrochemical performance was tested in the three-electrode system. [ABSTRACT FROM AUTHOR]

Trifluoromethyl phenyl sulfone is traditionally a nucleophilic trifluoromethylating agent. Herein, we report the first example of the use of trifluoromethyl phenyl sulfone as a trifluoromethyl radical precursor. Arylthiolate anions can form electron donor–acceptor (EDA) complexes with trifluoromethyl phenyl sulfone, which can undergo an intramolecular single electron transfer (SET) reaction under visible light irradiation, thus realizing the S-trifluoromethylation of thiophenols under photoredox catalyst-free conditions. Similar S-perfluoroethylation and S-perfluoro-iso-propylation of thiophenols are also achieved using the corresponding perfluoroalkyl phenyl sulfones. [ABSTRACT FROM AUTHOR]

A surface-based duct (SBD) is an abnormal atmospheric structure with a low probability of occurrence buta strong ability to trap electromagnetic waves. However, the existing research is based on the assumption that the range direction of the surface duct is homogeneous, which will lead to low productivity and large errors when applied in a real-marine environment. To alleviate these issues, we propose a framework for the inversion of inhomogeneous SBD M-profile based on a full-coupled convolutional Transformer (FCCT) deep learning network. We first designed a one-dimensional residual dilated causal convolution autoencoder to extract the feature representations from a high-dimension range direction inhomogeneous M-profile. Second, to improve efficiency and precision, we proposed a full-coupled convolutional Transformer (FCCT) that incorporated dilated causal convolutional layers to gain exponentially receptive field growth of the M-profile and help Transformer-like models improve the receptive field of each range direction inhomogeneous SBD M-profile information. We tested our proposed method performance on two sets of simulated sea clutter power data where the inversion of the simulated data reached 96.99% and 97.69%, which outperformed the existing baseline methods. [ABSTRACT FROM AUTHOR]

In this study, we used a ~47.0-kyr record of Sr–Nd isotopic data derived from lake sediments in Dahu swamp in the eastern Nanling Mountains to explore the possible changes in the source of sediments, and to provide insights into the East Asian winter monsoon (EAWM) driven climatic signals. Based on Sr–Nd isotopic results, we argued that local weathered granitic residues were the dominant source of sediments throughout the past ∼47.0 kyr. However, variations of 87Sr/86Sr and 144Nd/143Nd ratios were likely disturbed by the mixture of an additional input from Chinese Loess Plateau (CLP). During some dry/cold millennial periods (e.g., Heinrich event 5, 4, and 2, and the 26.0–24.0 kyr B.P), similar Sr–Nd isotopic signatures between the lake sediments and the fine fraction (<20 μm) of the loess from CLP implied an aeolian dust source. Thus, variability of Sr-Nd isotopic ratios indirectly indicated two modes of climate patterns: the wet and warm intervals during which the sediments were mainly derived from the local weathered residues were expressed in increased 87Sr/86Sr and decreased 144Nd/143Nd ratios, whereas during the dry and cold intervals the increased input of fine dust from CLP transported by strengthened EAWM winds would favor declined 87Sr/86Sr and increased 144Nd/143Nd ratios. Our Sr‒Nd isotopic records revealed an anti-phase between the EAWM and the summer monsoon, and displayed a good consistency with the record of mean grain size of quartz of loess from CLP, which was regarded as a reliable proxy of EAWM, suggested they can indirectly reflect variability of EAWM strength. [ABSTRACT FROM AUTHOR]

Co‐doped Mo1‐xCoxS2(x=0, 0.1, 0.3, 0.5) nanoparticles with varying amounts of Co were compounded by hydrothermal channel. The microstructures of the samples were characterized. All the samples showed hexagonal structure, good crystallization, flower shape microspheres and agglomeration to a certain extent. Furthermore, the influence of Co doping on the electrochemical properties was evaluated by cyclic voltammetry (CV), galvanostatic charge‐discharge (GCD), cycle stability and electrochemical impedance spectra (EIS). CV curves present quasi‐triangular shapes with good symmetry, doped Mo1‐xCoxS2 nanoparticles exhibit better specific capacitance and excellent cyclic stability than that of MoS2 samples. The capacity ratios of MCS‐3 electrodes maintains 96 % of its premier capacitance after 3000 cycles. The remarkable electrochemical properties embodied in CV proof were proved via the GCD measurements. Nyquist spectra of doped Mo1‐xCoxS2 electrodes reveal lower resistance and perfect conductivity. This work reveals that Co doping can further effectively the electrochemical properties of MoS2 nanomaterials. [ABSTRACT FROM AUTHOR]

This study prepared foamed waste oil-activated rubberized asphalt (ORA) by activating crumb rubber (CR) with waste vegetable oil (WVO) to address the issue of undesirable foaming effect. Optimal foaming parameters for different rubberized asphalt were determined based on foaming characteristic experiments. Furthermore, rheological properties, fatigue resistance, and adhesion performance of various unfoamed or foamed rubberized asphalt were evaluated through dynamic shear rheometer, bending beam rheometer, pull-out tests. Finally, the analytic hierarchy process was utilized to select the optimum foamed rubberized asphalt. The results show that foaming pressure has a great influence on rubberized asphalt foaming effect, and is recommended at 300 kPa. Compared to conventional rubberized asphalt whether foamed or not, with the increase of activation degree, low-temperature performance, and fatigue resistance of ORA are significantly ameliorated, and the adhesion property of ORA first increases and then decreases, but detrimental to high-temperature performance. The foaming process and foaming agent addition are conducive to low-temperature performance but unfavorable to fatigue resistance and high-temperature property, and have little effect on adhesion performance. ORA (mass ratio of WVO to CR is 1:5) with foaming agent is determined as the optimum selection. • The foaming effect of rubberized asphalt is greatly affected by the foaming pressure. • Foamed ORA is prepared to address the undesirable foaming effect of rubberized asphalt. • CR activation can effectively enhance the foaming effect, fatigue resistance and low-temperature performance of foamed RMA. [ABSTRACT FROM AUTHOR]

Thermokarst lakes and ponds (hereafter referred to as thaw lakes) play an important role in the permafrost regions by regulating hydrology, ecology, and biogeochemistry. However, detailed quantitative information on thaw lake extent and distribution remains poorly resolved across the entire permafrost regions on the Qinghai‐Tibet Plateau (QTP). Here, we applied the random forest (RF) model and manual visual vectorization methods to extract thaw lake boundaries on the QTP based on Sentinel‐2 images. Accuracy assessment was comprehensively demonstrated regarding the inherent spatial resolution of imagery and RF model performance. The results showed that the accumulated uncertainty of the total thaw lake area was ±5.75 km2, and the mean accuracy (91.9%) from field‐measured boundaries of 132 thaw lakes supported the accuracy of this inventory. A total of ∼161,300 thaw lakes with sizes ranging from 500 m2 to 3 km2 were detected, with a total area of ∼2,825.45 ± 5.75 km2. Most thaw lakes were detected in the continuous permafrost type (94.1%) and within the elevations of 4,500–5,000 m (68.4%). The small thaw lakes (<10,000 m2) predominated the total lake number (78.9%) but contributed to a small portion of the total lake area (12.7%). Spatial distributions of thaw lakes in terms of different climatic and environmental conditions were also comprehensively explored, including temperature, precipitation, ground thermal stability, active layer thickness, vegetation, soil properties, and underground ice content. This inventory is expected to be incorporated into Earth system models for a more comprehensive projection of the large‐scale biogeochemical feedback of thermokarst landforms on the QTP under continued global warming. Plain Language Summary: Thaw lakes develop when warming soil melts ground ice, causing the surface to collapse and form pools of water. Such lakes can greatly influence local water resources and ecosystems, but also are important sources of greenhouse gas released into the atmosphere. Using Sentinel‐2 images, we provided robust information of thaw lake numbers, areas, and spatial distributions across the entire QTP permafrost regions by applying the random forest model and manual visual vectorization methods. The accuracy of the data set has been demonstrated in regard to the image spatial resolution, model performance, and field‐measured results. Within sizes ranging from 500 m2 to 3 km2, we extracted ∼161,300 thaw lakes with a total area of ∼2,825.45 ± 5.75 km2. We found that most thaw lakes were located in the continuous permafrost regions and within the elevations of 4,500–5,000 m. Most thaw lake sizes were smaller than 10,000 m2 but they only contributed to a little percentage of the total lake area. We also comprehensively explored the spatial distributions of thaw lakes in different climatic and environmental areas. This inventory would be useful for future Earth system models to predict the large‐scale biogeochemical feedback of thaw lakes on the Qinghai‐Tibet Plateau in the future. Key Points: Using Sentinel‐2 images, we established an inventory data set of thaw lakes on the QTP via random forest model and manual postprocessing methodsApproximately 161,300 thaw lakes with sizes ranging from 500 m2 to 3 km2 were extracted, with a total area of ∼2,825.45 ± 5.75 km2Distributions of thaw lakes were highly uneven in regard to different geospatial, climatic and environmental status [ABSTRACT FROM AUTHOR]

This paper investigates robust and secure multiuser multiple-input single-output (MISO) downlink communications assisted by a self-sustainable intelligent reflection surface (IRS), which can simultaneously reflect and harvest energy from the received signals. We study the joint design of beamformers at an access point (AP) and the phase shifts as well as the energy harvesting schedule at the IRS for maximizing the system sum-rate. The design is formulated as a non-convex optimization problem taking into account the wireless energy harvesting capability of IRS elements, secure communications, and the robustness against the impact of channel state information (CSI) imperfection. Subsequently, we propose a computationally-efficient iterative algorithm to obtain a suboptimal solution to the design problem. In each iteration, $\mathcal {S}$ -procedure and the successive convex approximation are adopted to handle the intermediate optimization problem. Our simulation results unveil that: 1) there is a non-trivial trade-off between the system sum-rate and the self-sustainability of the IRS; 2) the performance gain achieved by the proposed scheme is saturated with a large number of energy harvesting IRS elements; 3) an IRS equipped with small bit-resolution discrete phase shifters is sufficient to achieve a considerable system sum-rate of the ideal case with continuous phase shifts. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the detection problem for a massive machine-type communication (mMTC) system that has correlated user activities. Two deep learning assisted algorithms are proposed to exploit the user activity correlation to facilitate channel estimation and user identification. Due to the dependency among user activities, conventional element-wise minimum mean square error (MMSE) denoiser used in the orthogonal approximate message passing (OAMP) algorithm cannot achieve satisfying performance during the two-step iterative process. Therefore, we propose a deep learning modified OAMP (DL-mOAMP) algorithm, which iteratively modifies the user activity ratio via exploiting the user activity correlation in the MMSE denoiser based on the estimated sequence during each OAMP iteration. Moreover, given a specific false alarm probability, a constant threshold employed in the conventional user identification is not optimal in the presence of user activity correlation. Thus, we propose a neural network framework that is dedicated to the user identification (DL-mOAMP-UI algorithm), which minimizes the missed detection probability under a pre-determined false alarm probability. Numerical results show that the proposed DL-mOAMP algorithm provides a substantial mean squared error performance gain compared to the conventional OAMP algorithm and the DL-mOAMP-UI algorithm can further improve the user identification accuracy of an mMTC system. [ABSTRACT FROM AUTHOR]

Weather recognition is a significant technique for many potential computer vision applications in our daily lives. Generally, most existing works treat weather recognition as a single-label classification task, which cannot describe the weather conditions comprehensively due to the complex co-occurrence dependencies between different weather conditions. In this paper, we propose a novel Graph Convolution Networks with Attention (GCN-A) model for multi-label weather recognition. To our best knowledge, this is the first attempt to introduce GCN into weather recognition. Specifically, we employ GCN to capture weather co-occurrence dependencies via a directed graph. The graph is built over weather labels, where each node (weather label) is represented by word embeddings of a weather label. Furthermore, we design a re-weighted mechanism to build weather correlation matrix for information propagation among different nodes in GCN. In addition, we develop a channel-wise attention module to extract informative semantic features of weather for effective model training. Compared with the state-of-the-art methods, experiment results on two widely used benchmark datasets demonstrate that our proposed GCN-A model achieves promising performance. [ABSTRACT FROM AUTHOR]

One of the major challenges of learning to hash in large-scale image retrieval is the projective transformation from raw image to binary space with preserving semantic similarity. Recently, several deep hashing methods show many excellent properties compared with traditional hashing based on hand-designed representation. However, most of the existing hashing models only pay attention to the semantic similarity between image pairs, ignoring the ranking information of retrieval results, which limits its performance. In this paper, a novel deep hashing framework, named Deep Top Similarity Hashing with Class-wise loss (DTSH-CW), is proposed to preserve semantic similarity between top images of ranking list and query images. In this proposed framework, CNNs architecture with batch normalization module is adopted to extract deep semantic characteristics. With integrating the position information of images, a top similarity loss is carefully designed to ensure the similarities between top images of ranking list and query images. Unlike pair-wise or triplet-wise loss, by directly leveraging the class labels, a cubic constraint based on Gaussian distribution is introduced to optimize objective function so as to maintain semantic variations of different classes. Furthermore, in order to solve discrete optimization problem, Two-Stage strategy is developed to provide efficient model training. Quantities of comparison experiments on three multi-label benchmark datasets show that our proposed DTSH-CW achieves promising performance compared to several state-of-the-art hashing methods. [ABSTRACT FROM AUTHOR]

The iron‐catalyzed alkyl–aryl coupling reaction between sulfones and arylboron compounds has remained a challenge. We report the first iron‐catalyzed radical difluoroalkylation of arylborates with N‐heteroaryl sulfones. The coordination between the iron catalyst and the nitrogen atom of N‐heteroaryl sulfones was identified to be important in overcoming the reduction potential limitation of sulfones in the intermolecular single‐electron‐transfer process, which enables both fluoroalkyl N‐heteroaryl sulfones (with relatively high reduction potentials) and nonfluorinated alkyl N‐heteroaryl sulfones (with low reduction potentials) to serve as powerful alkylation reagents. [ABSTRACT FROM AUTHOR]

The iron‐catalyzed alkyl–aryl coupling reaction between sulfones and arylboron compounds has remained a challenge. We report the first iron‐catalyzed radical difluoroalkylation of arylborates with N‐heteroaryl sulfones. The coordination between the iron catalyst and the nitrogen atom of N‐heteroaryl sulfones was identified to be important in overcoming the reduction potential limitation of sulfones in the intermolecular single‐electron‐transfer process, which enables both fluoroalkyl N‐heteroaryl sulfones (with relatively high reduction potentials) and nonfluorinated alkyl N‐heteroaryl sulfones (with low reduction potentials) to serve as powerful alkylation reagents. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the impacts of transmitter and receiver windows on the performance of orthogonal time-frequency space (OTFS) modulation and propose window designs to improve the OTFS channel estimation and data detection performance. In particular, assuming ideal pulse shaping filters at the transceiver, we derive the impacts of windowing on the effective channel and its estimation performance in the delay-Doppler (DD) domain, the total average transmit power, and the effective noise covariance matrix. When the channel state information (CSI) is available at the transceiver, we analyze the minimum squared error (MSE) of data detection and propose an optimal transmitter window to minimize the detection MSE. The proposed optimal transmitter window can be interpreted as a mercury/water-filling power allocation scheme, where the mercury is firstly filled before pouring water to pre-equalize the time-frequency (TF) domain channels. When the CSI is not available at the transmitter but can be estimated at the receiver, we propose to apply a Dolph-Chebyshev (DC) window at either the transmitter or the receiver, which can effectively enhance the sparsity of the effective channel in the DD domain. Thanks to the enhanced DD domain channel sparsity, the channel spread due to the fractional Doppler is significantly reduced, which leads to a lower error floor in both channel estimation and data detection compared with that of rectangular window. Simulation results verify the accuracy of the obtained analytical results and confirm the superiority of the proposed window designs in improving the channel estimation and data detection performance over the conventional rectangular window design. [ABSTRACT FROM AUTHOR]

Although the electrospinning technique has been devoted to promoting therapeutic purposes as a drug carrier, however, there are still many fundamental problems in this area. This work focuses on a comparison of various diameter polyethersulfone (PES) electrospun ultrafine fibers as antimicrobial materials. The fibrous morphology, antimicrobial agent distribution, thermally property, and biocompatibility evaluation of PES-based ultrafine fibers were systematically investigated. The results demonstrated that the PES-based ultrafine fibers were suitable as antimicrobial material. Furthermore, the drug release behavior and mechanism were studied through total immersion. The release mechanism was confirmed to Fickian diffusion. It was revealed that the drug max release amount (71.5%) and release rate (7.71) are the highest for the smallest diameter ultrafine fibers. Meanwhile, the antimicrobial activity of PES ultrafine fibers is also inversely correlated with the diameter of fiber. The electrospun PES fibers would control their release behavior through the diameter and have a potential application in the wound dressings, such as chronic osteomyelitis and exposure injury. [ABSTRACT FROM AUTHOR]

Background: Hepatitis B virus (HBV) infection is difficult to cure. HBV-specific immune tolerance plays a key role in HBV persistence, and enhancing cellular and humoral immunity will improve the control of HBV infection. The purpose of the study was to explore the anti-HBV and immunostimulatory effects of msiRNAs that introduce unpaired uridine bulges in the passenger strand. Methods: msiRNAs targeting the HBV S and X genes were designed and named msiHBs and msiHBx, respectively. HepG2 cells were cotransfected with siRNA or msiRNA and the HBV replication-competent plasmid pHY106-wta or pHY106-X15. HepG2.215 cells were transfected with siRNA or msiRNA. The levels of HBsAg, HBeAg, and the cytokines TNF-α, IFN-α, IFN-β, IL-1α, and IL-6 in the culture supernatant was detected by ELISA. The levels of intracellular HBV RNA, nuclear HBV replication intermediates, and HBV DNA in the supernatant were measured by quantitative RT-PCR and PCR. The levels of HBV replication intermediates were detected by Southern blotting. Peripheral blood mononuclear cells were transfected with siRNA or msiRNA, and the levels of secreted cytokines IFN-α and IFN-β were detected by ELISA. The bioactivity of type I interferons in the supernatants was detected by the virus protection assay. Results: msiHBx treatment led to a significant decrease in HBsAg (to a negative level) and HBV DNA (95.5%) in the supernatant and intrahepatocellular HBV replication intermediates (89.8%) in HepG2 cells with transient HBV replication and in HepG2.2.15 cells. There was no significant difference between msiHBx and siHBx in terms of the reduction in HBV proteins and HBV replication (P > 0.05). Compared with siHBx, msiHBx treatment of HepG2 cells transfected with the HBV replication-competent plasmid led to a significant increase in the levels of the antiviral cytokines TNF-α (3.3-fold), IFN-α (1.4-fold), and IFN-β (2.5-fold) (P < 0.01), without upregulation of the proinflammatory cytokines IL-1α and IL-6. The virus protection assay results showed msiHBx-mediated type I interferons effectively protected L929 cells against ECMV infection. Conclusions: msiHBx could effectively inhibit HBV expression and replication and induce an antiviral innate immune response without proinflammatory activation. The dual RNAi and immunostimulatory activity of msiRNAs may play an important role in the control of HBV infection. [ABSTRACT FROM AUTHOR]

• BiOI is an excellent connector between ZnFe 2 O 4 and AgI to form a double Z-type heterojunction structure ZnFe 2 O 4 /BiOI/AgI composite through precise electronic regulation. • The existence of a double Z-heterojunction structure and Ag0 makes the electrons on the interface transfer and separate effectively. • Rich oxygen vacancies also provide more active sites for photocatalysis and photo-Fenton process. As a bridge, BiOI nanosheets connect ZnFe 2 O 4 nanoparticles and AgI clusters (∼300 nm) via hydrothermal-coprecipitation. A ternary composite with a double Z-type heterojunction structure is obtained through precise electronic regulation. Compared with ZnFe 2 O 4 and ZnFe 2 O 4 /BiOI, the photo-Fenton degradation RhB of ZnFe 2 O 4 /BiOI-AgI-3 samples is obviously improved under simulated sunlight. Rich oxygen vacancies also provide more active sites for photocatalysis and photo-Fenton process. The main active specie in photo-Fenton degradation is ·OH. The existence of a double Z-heterojunction structure and Ag0 makes the electrons on the interface transfer and separate effectively. Notably, the intensity of PL luminescence ZnFe 2 O 4 /BiOI/AgI is lower than that of ZnFe 2 O 4 and ZnFe 2 O 4 /BiOI because of reducing the recombination rate of photogenerated carriers. ZnFe 2 O 4 /BiOI/AgI composites have excellent stability of photo-Fenton degradation. Furthermore, the formation of a built-in electric field inhibits the recombination of electron-hole pairs, enhances visible light absorption, results in improving the efficiency of ternary composite materials to degrade pollutants. [Display omitted] [ABSTRACT FROM AUTHOR]

Person re-identification (Re-ID) has attracted more attention in computer vision tasks recently and achieved high accuracy in some public available datasets in a supervised manner. The performance drops significantly when datasets are unlabeled, which limits the scalability of Re-ID algorithms in practical applications. Despite some unsupervised methods are proposed to address the scalability problem of Re-ID, it's hard to learn discriminative feature representations due to the lack of pairwise labels in different camera views. To overcome this problem, we propose an end-to-end network named Adaptive Attention-Aware Network for unsupervised person re-identification. Specifically, we propose a novel adaptive attention-aware module that could be easily embedded into Re-ID architecture. The proposed module focuses on learning strong expressive relationship among channels of feature maps, and alleviating the key problems of Re-ID, e.g., occlusion and local deformation. In addition, we extract the camera-invariant features by adopting camera-style transfer feature learning since matching pairs in Re-ID suffers from appearance changes under different camera views. Besides, unsupervised hard negative mining is introduced to learn large intra-person appearance variance and discriminate high inter-person appearance similarity in an unlabeled target dataset with an auxiliary labeled dataset. Comprehensive experiments on three public available Re-ID datasets demonstrate that our method can achieve the state-of-the-art results of unsupervised Re-ID and is competitive with supervised learning. [ABSTRACT FROM AUTHOR]

In this paper, we study the resource allocation and trajectory design for secure unmanned aerial vehicle (UAV)-enabled communication systems, where multiple multi-purpose UAV base stations are dispatched to provide secure communications to multiple legitimate ground users (GUs) in the existence of multiple eavesdroppers (Eves). Specifically, by leveraging orthogonal frequency division multiple access (OFDMA), active UAV base stations can communicate to their desired ground users via the assigned subcarriers while idle UAV base stations can serve as jammer simultaneously for communication security provisioning. To achieve fairness in secure communication, we maximize the average minimum secrecy rate per user by jointly optimizing the communication/jamming subcarrier allocation policy and the trajectory of UAVs, while taking into account the constraints on the minimum safety distance among multiple UAVs, the maximum cruising speed, the initial/final locations, and the existence of cylindrical no-fly zones (NFZs). The design is formulated as a mixed integer non-convex optimization problem which is generally intractable. Subsequently, a computationally-efficient iterative algorithm is proposed to obtain a suboptimal solution. Simulation results illustrate that the performance of the proposed iterative algorithm can significantly improve the average minimum secrecy rate compared to various baseline schemes. [ABSTRACT FROM AUTHOR]

In this paper, we study the trajectory and resource allocation design for downlink energy-efficient secure unmanned aerial vehicle (UAV) communication systems, where an information UAV assisted by a multi-antenna jammer UAV serves multiple ground users in the existence of multiple ground eavesdroppers. The resource allocation strategy and the trajectory of the information UAV, and the jamming policy of the jammer UAV are jointly optimized for maximizing the system energy efficiency. The joint design is formulated as a non-convex optimization problem taking into account the quality of service (QoS) requirement, the security constraint, and the imperfect channel state information (CSI) of the eavesdroppers. The formulated problem is generally intractable. As a compromise approach, the problem is divided into two subproblems which facilitates the design of a low-complexity suboptimal algorithm based on alternating optimization approach. Simulation results illustrate that the proposed algorithm converges within a small number of iterations and demonstrate some interesting insights: (1) the introduction of a jammer UAV facilitates a highly flexible trajectory design of the information UAV which is critical to improving the system energy efficiency; (2) by exploiting the spatial degrees of freedom brought by the multi-antenna jammer UAV, our proposed design can focus the artificial noise on eavesdroppers offering a strong security mean to the system. [ABSTRACT FROM AUTHOR]

The emerging orthogonal time frequency space (OTFS) modulation technique has shown its superiority to the current orthogonal frequency division multiplexing (OFDM) scheme, in terms of its capabilities of exploiting full time-frequency diversity and coping with channel dynamics. The optimal maximum a posteriori (MAP) detection is capable of eliminating the negative impacts of the inter-symbol interference in the delay-Doppler (DD) domain at the expense of a prohibitively high complexity. To reduce the receiver complexity for OTFS scheme, this paper proposes a variational Bayes (VB) approach as an approximation of the optimal MAP detection. Compared to the widely used message passing algorithm, we prove that the proposed iterative algorithm is guaranteed to converge to the global optimum of the approximated MAP detector regardless the resulting factor graph is loopy or not. Simulation results validate the fast convergence of the proposed VB receiver and also show its promising performance gain compared to the conventional message passing algorithm. [ABSTRACT FROM AUTHOR]

Background: Osteoarthritis (OA) is a metabolic disorder and able to be relieved by traditional Chinese medicines. However, the effect of Ligusticum wallichii on OA is unknown. Methods: Cytokine IL-1β and L. wallichii extracts were used to stimulate the primary mouse chondrocytes. MTT assay was used to measure the cell viability. The mRNA and protein level of each gene were test by qRT-PCR and western blotting, respectively. The rate of apoptotic cell was measured by flow cytometry. GC/MS-based metabolomics was utilized to characterize the variation of metabolome. Results: Here, we found that L. wallichii attenuated the IL-1β-induced apoptosis, inflammatory response, and extracellular matrix (ECM) degradation in mouse chondrocytes. Then we used GC/MS-based metabolomics to characterize the variation of metabolomes. The established metabolic profile of mouse chondrocytes showed that the abundance of most metabolites (n = 40) altered by IL-1β stimulation could be repressed by L. wallichii treatment. Multivariate data analysis identified that cholesterol, linoleic acid, hexadecandioic acid, proline, l-valine, l-leucine, pyruvate, palmitic acid, and proline are the most key biomarkers for understanding the metabolic role of L. wallichii in IL-1β-treated chondrocytes. Further pathway analysis using these metabolites enriched fourteen metabolic pathways, which were dramatically changed in IL-1β-treated chondrocytes and capable of being reprogrammed by L. wallichii incubation. These enriched pathways were involved in carbon metabolisms, fatty acid biosynthesis, and amino acid metabolisms. Conclusions: These findings provide potential clues that metabolic strategies are linked to protective mechanisms of L. wallichii treatment in IL-1β-stimulated chondrocytes and emphasize the importance of metabolic strategies against inflammatory responses in OA development. [ABSTRACT FROM AUTHOR]

In this paper, we investigate and reveal the ergodic sum-rate gain (ESG) of non-orthogonal multiple access (NOMA) over orthogonal multiple access (OMA) in uplink cellular communication systems. A base station equipped with a single-antenna, with multiple antennas, and with massive antenna arrays is considered both in single-cell and multi-cell deployments. In particular, in single-antenna systems, we identify two types of gains brought about by NOMA: 1) a large-scale near-far gain arising from the distance discrepancy between the base station and users; 2) a small-scale fading gain originating from the multipath channel fading. Furthermore, we reveal that the large-scale near-far gain increases with the normalized cell size, while the small-scale fading gain is a constant, given by $\gamma = 0.57721$ nat/s/Hz, in Rayleigh fading channels. When extending single-antenna NOMA to M-antenna NOMA, we prove that both the large-scale near-far gain and small-scale fading gain achieved by single-antenna NOMA can be increased by a factor of M for a large number of users. Moreover, given a massive antenna array at the base station and considering a fixed ratio between the number of antennas, M, and the number of users, K, the ESG of NOMA over OMA increases linearly with both M and K. We then further extend the analysis to a multi-cell scenario. Compared to the single-cell case, the ESG in multi-cell systems degrades as NOMA faces more severe inter-cell interference due to the non-orthogonal transmissions. Besides, we unveil that a large cell size is always beneficial to the ergodic sum-rate performance of NOMA in both single-cell and multi-cell systems. Numerical results verify the accuracy of the analytical results derived and confirm the insights revealed about the ESG of NOMA over OMA in different scenarios. [ABSTRACT FROM AUTHOR]

In this paper, we propose a transmission control scheme for the approximate message passing (AMP)-based joint user identification and channel estimation in massive connectivity networks. In the proposed transmission control scheme, a transmission control function is designed to determine a user’s transmission probability, when it has a transmission demand. By employing a step transmission control function for the proposed scheme, we derive the channel distribution experienced by the receiver to describe the effect of transmission control on the design of AMP algorithm. Based on that, we modify the AMP algorithm by designing a minimum mean squared error (MMSE) denoiser, to jointly identify the user activity and estimate their channels. We further derive the false alarm and missed detection probabilities to characterize the user identification performance of the proposed scheme. Closed-form expressions of the average packet delay and the network throughput are obtained. Furthermore, we optimize the transmission control function to maximize the network throughput. We demonstrate that the proposed scheme can significantly improve the user identification and channel estimation performance, reduce the average delay, and boost the throughput, compared to the conventional scheme without transmission control. [ABSTRACT FROM AUTHOR]

An electrical stress-induced resistance change in an Fe–O film was studied in detail. Under constant voltage stress (CVS) and constant current injection, the resistance of the Fe–O film abruptly increased. The observed time-to-resistance increase (tr) was found to depend on the applied voltage as well as on the injected current density. The total input energy until tr also depended on the applied voltage. From these observations, the mechanisms of resistance change are considered to obey a field-enhanced reaction, and this resistance increase is attributed to a high-resistive Fe–O layer formation at the interface between the anode electrode and the low-resistive Fe–O layer. We proposed a simplified two-step model for the time evolution of the current under CVS [ICVS(t)]. The predicted ICVS(t) showed a good agreement with experimental results. The model also explained the field dependence of tr. [ABSTRACT FROM AUTHOR]

Bio-based flame retardants have been widely studied for their eco-friendly, renewable and sustainable advantages. However, the durability of bio-based flame retardants is usually poor due to the weak combination with textile substrates. In this study, based on the strategy of constructing a covalent anchoring network between flame retardants and textile substrates, epoxidized waste cooking oil (EWCO) was used as the bio-based crosslinking agents to covalently bind with phytic acid (PA) and chitosan (CH) forming the fully bio-based intumescent flame retardant (IFR) system. The wool fabrics were treated by PA/EWCO/CH IFR system through simple pad-dry-cure finishing process, and a large cross-linking system between the flame retardants and wool fabrics could form during the finishing process anticipating to enhance the interfacial binding strength. The limited oxygen index (LOI) value of PA/EWCO/CH treated wool fabric reached 30.5%, its char length reduced to 96 mm showing excellent flame retardancy, and it still possessed good wearability. The LOI value of PA/EWCO/CH treated wool fabrics after 4 times washing was 27.5%, which was higher than that without EWCO (26.3%) showing good washing durability. This research provides a new strategy for solving the interfacial binding fastness between bio-based flame retardants and substrates to enhance the flame retardant durability by using bio-based waste plant oil derivatives crosslinking agent. [Display omitted] • Epoxidized waste cooking oil (EWCO) was synthesized as bio-based crosslinking agent. • Covalently anchored network between flame retardants and wool was formed by EWCO. • Bio-based PA/EWCO/CH IFR system endowed wool fabric with excellent flame retardancy. • EWCO enhances the interfacial binding strength for durable flame retardant wool. [ABSTRACT FROM AUTHOR]

A series of Co-doped Zn1-xCoxMn2O nanocrystals with a spinel structure were successfully prepared by hydrothermal method, and the influence of Co doping concentration on the microstructure, morphology, elemental composition, and optical and photocatalytic properties of the samples was characterized. The experimental results show that all samples exhibit a tetragonal structure, Co2+ ions are successfully substituted for the lattice site of Zn2+ to generate ZnMn2O4 nanocrystals, and the crystalline size decreases as Co-doped concentration increase. The morphologies are loose hollow microsphere structures. The band gap of Zn1−xCoxMn2O samples is smaller than that of pure ZnMn2O4 and has been red shifted. The photocatalytic activity of doped Zn1−xCoxMn2O4 samples is obviously higher than that of pure ZnMn2O4 samples for the photodegradation of MO under visible light irradiation. All these results demonstrate that Co-doped spinel ZnMn2O4 nanocrystals are a meaningful choice for photocatalytic degradation of the pollutants. [ABSTRACT FROM AUTHOR]

In this paper, we propose a multi-beam non-orthogonal multiple access (NOMA) scheme for hybrid millimeter wave (mmWave) systems and study its resource allocation. A beam splitting technique is designed to generate multiple analog beams to serve multiple NOMA users on each radio frequency chain. In contrast to the recently proposed single-beam mmWave-NOMA scheme which can only serve multiple NOMA users within the same analog beam, the proposed scheme can perform NOMA transmission for the users with an arbitrary angle-of-departure distribution. This provides a higher flexibility for applying NOMA in mmWave communications and thus can efficiently exploit the potential multi-user diversity. Then, we design a suboptimal two-stage resource allocation for maximizing the system sum-rate. In the first stage, assuming that only analog beamforming is available, a user grouping and antenna allocation algorithm is proposed to maximize the conditional system sum-rate based on the coalition formation game theory. In the second stage, with the zero-forcing digital precoder, a suboptimal solution is devised to solve a non-convex power allocation optimization problem for the maximization of the system sum-rate which takes into account the quality of service constraints. Simulation results show that our designed resource allocation can achieve a close-to-optimal performance in each stage. In addition, we demonstrate that the proposed multi-beam mmWave-NOMA scheme offers a substantial spectral efficiency improvement compared to that of the single-beam mmWave-NOMA and the mmWave orthogonal multiple access schemes. [ABSTRACT FROM AUTHOR]

As the basis of the research on reducing wake vortex separations, numerical simulation and constructing of fast-models for simulating wake vortex have become the focus of many international ATM research institutes. In the research field of wake vortex numerical simulation, the formation, evaluation and decay of wake vortex are calculated based on RANS, LES or DES methods. These data can help to reveal the regulation of wake vortex, and can provide basic foundation for constructing wake vortex models. In the field of fast simulation of wake vortex, Some organizations have done many theoretical researches on the formation and dissipation of wake vortex, attempting to deduce the behavioural characteristics of wake vortex by establishing complex mathematical models, including CROW instability, Greene model, APA model, TDAWP model, D2P model and the three-phase decay model, etc. The research status quo is analyzed and the key works in the next phase are also provided. [ABSTRACT FROM AUTHOR]

Abstract The Sn 1- x Cr x S 2 ( x = 0, 0.01, 0.03, 0.05 and 0.07) nanoflowers with different molar ratios were prepared via hydrothermal at a low temperature of 180 °C. All samples were characterized by XRD, FT-IR, SEM, EDS, TEM, XPS, UV–vis and PL. The Sn 1- x Cr x S 2 nanoflowers are single-phase wurtzite structure with good crystallinity, which is confirmed by the XRD, and FT-IR results. XPS and EDS results demonstrate that Cr is present in the valence of Cr3+ ions. Based on the SEM and TEM analysis, the size of doped samples is nearly flower-like ~1.5 µm. The band gap of Sn 0.95 Cr 0.05 S 2 (2.24 eV) is the largest in the doped samples, which displays the most similar to that of the pure SnS 2 nanoflowers (2.27 eV). The photocatalytic activity of the Cr doped SnS 2 nanoflowers is evaluated towards the decolorization of rhodamine B under visible irradiation with good cyclability and stability. Moreover, the main active species are • OH and h+. Accordingly, Cr doped SnS 2 displays super photocatalytic performance in dyes decomposition showing the lowest intensity in the PL spectra with doped optimum 5% Cr concentration. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the system performance of a multi-cell multi-user (MU) hybrid millimeter wave communications in a multiple-input multiple-output (MIMO) network. Due to the reuse of pilot symbols among different cells, the performance of channel estimation is expected to be degraded by pilot contamination, which is considered as a fundamental performance bottleneck of conventional multi-cell MU massive MIMO networks. To analyze the impact of pilot contamination to the system performance, we first derive the closed-form approximation of the normalized mean-squared error of the channel estimation algorithm proposed by Zhaoet al. over Rician fading channels. Our analytical and simulation results show that the channel estimation error incurred by the impact of pilot contamination and noise vanishes asymptotically with an increasing number of antennas equipped at each radio frequency chain at the desired BS. Furthermore, by adopting zero-forcing precoding in each cell for downlink transmission, we derive a tight closed-form approximation of the average achievable rate per user. Our results unveil that the intra-cell interference and inter-cell interference caused by pilot contamination over Rician fading channels can be mitigated effectively by simply increasing the number of antennas equipped at the desired BS. [ABSTRACT FROM AUTHOR]

A novel hydrogen sensor has been developed by using an optimized 0.18- $\mu \text{m}$ resistive random access memory process with a Pt/Ta2O5/TaOx/TaN stack. This resistive hydrogen sensor (ReHsensor) conforms to the ISO26142 standard in which it exhibits exceptional sensing capabilities, including a short response time (about 20 s for 1 vol.% hydrogen gas), high sensitivity, wide hydrogen concentration detection range (up to 4 vol.%) in air and N2 ambient, high gas selectivity (no reaction with CH4, CO, CH3OH, or CH3COCH3) and is immune to poisoning by SO2 and hexamethyl disiloxane. As it does not require a heater, the power consumption of the ReHsensor is very low, at 0.4 mW. [ABSTRACT FROM AUTHOR]

Abstract Systematic studies of lacustrine magnetic sediments can provide useful information to decipher the catchment processes of specific environmental changes. To explore the magnetic mineral-paleoenvironment connections, we have conducted a mineral-magnetic investigation on a lacustrine sediment core recovered from a closed-basin lake in the eastern Nanling Mountains of southern China. Our results show that the magnetic minerals in the sediments were mainly catchment-derived, and the post-depositional effects, or biogenic and authigenic growth of secondary ferrimagnetic minerals, were probably insignificant or absent. The catchment soil erosion, pedogenic development, and vegetation coverage are interpreted as the main forcing in controlling the variations in magnetic parameters. During the last deglaciation period (~16,500–11,100 yr BP), the relatively high and significant variations in magnetic parameters of sediments could have corresponded to the rapid climate fluctuations after the cool and dry Last Glacial Maximum. In the Holocene (11,100 yr BP to present), the low magnetic concentrations and increases in finer magnetic particles likely resulted from the stabilization of the watershed and more intense pedogenic processes under the warm and wet climate. Because changes in surface-runoff, vegetation coverage, and soil pedogenic processes are closely related to Asian summer monsoon (ASM) intensity, the sedimentary magnetism of Dahu Swamp can provide another valuable source of information to investigate the development of the ASM in southern China. Highlights • A closed-basin lacustrine sediments in E. Nanling Mts. was chosen for magnetic study. • Magnetic minerals in sediments mainly originated from catchment surface soil. • The post-depositional effects were probably insignificant in the sediments. • Magnetic parameters mainly reflect changes in the local environmental conditions, which associate with ASM intensity. [ABSTRACT FROM AUTHOR]

An extremal Kähler metric with finite singularities on a compact Riemann surface is often called an HCMU metric. It can be regarded as a generalization of CSC (constant scalar curvature) metric. In this paper we will prove that any HCMU metric is a pullback of an HCMU metric on S 2 with only two singularities (we call it football) by a multi-valued holomorphic function. Then we study the monodromy group of the multi-valued function. [ABSTRACT FROM AUTHOR]

At present, the specific capacity and cyclic stability of single cobalt manganese oxide are still insufficient to meet the application requirements. In this work, (Co,Mn)(Co,Mn) 2 O 4 /g-C 3 N 4 electrode materials with different mass ratios were synthesized by adjusting the composite ratio of g-C 3 N 4 and (Co,Mn)(Co,Mn) 2 O 4. The results of the three-electrode test system show that the electrochemical performance of the composite sample is improved compared with that of pure (Co,Mn)(Co,Mn) 2 O 4. When the mass ratio of g-C 3 N 4 to (Co,Mn)(Co,Mn) 2 O 4 is 1:9, the electrochemical performance is the best. This is because layered g-C 3 N 4 can provide more active sites for electrochemical reactions and increase the wettability of the material, thus improving the electrochemical reaction process. The power density of the assembled asymmetric supercapacitor CMO/GCN-2//AC can reach 16800 ​W ​kg−1 at an energy density of 14 ​Wh kg−1. Schematic representation of the synthesized (Co,Mn)(Co,Mn) 2 O 4 /g-C 3 N 4 structure. The granular form represents (Co,Mn)(Co,Mn) 2 O 4 , and the coloured layered structure is g-C 3 N 4. This structure improves the electrochemical reaction kinetics of the material. [Display omitted] • The specific capacity and cyclic stability of single cobalt-manganese oxides are relatively poor. The presence of lone pair electrons in g-C 3 N 4 nitrogen atoms induces greater polarity in the molecule, enhancing the wettability and carrier mobility of the material. In this paper, (Co,Mn)(Co,Mn) 2 O 4 /g-C 3 N 4 electrode material with different composite ratio was prepared. • The results of the three-electrode test system show that the electrochemical performance of the composite sample is improved compared with that of pure (Co,Mn)(Co,Mn) 2 O 4. When the mass ratio of g-C 3 N 4 to (Co,Mn)(Co,Mn) 2 O 4 is 1:9, the composite sample has the best electrochemical performance. • The power density of the assembled asymmetric supercapacitor CMO/GCN-2//AC can reach 16800 ​W ​kg−1 at energy density of 14 ​Wh kg−1. [ABSTRACT FROM AUTHOR]

• We propose a new reweighted atomic norm minimization approach for line spectral estimation based on the Hankel–Toeplitz model. • The proposed approach promotes sparsity, enhances resolution and converges faster than existing reweighted atomic norm method. • The first step is a new formulation of atomic norm minimization for which theoretical guarantees are provided. • Numerical simulations show the superior performance of our proposed approach. This paper is concerned with the problem of line spectral estimation. Reweighted atomic norm minimization based on Toeplitz model (RAM-T) is a promising approach that promotes sparsity and enhances resolution as compared to atomic norm minimization (ANM) by generalizing the atomic norm with a new sparsity metric. To address the slow convergence issue of RAM-T, in this paper, we propose a reweighted atomic norm minimization approach by exploiting the recently proposed Hankel–Toeplitz model, which achieves a better performance and converges faster than RAM-T. Furthermore, we reveal the connection between reweighted atomic norm minimization based on Hankel–Toeplitz model (RAM-HT) and RAM-T and give sufficient conditions for successful signal recovery of the first iteration of RAM-HT. Numerical experiments demonstrate the superior performance of our proposed approach. [ABSTRACT FROM AUTHOR]

We show, from a 16.6 ka record of lead isotopes from a core sediments in Dahu Swamp in eastern Nanling Mountains, that the chemical weathering responds to changes in climatic conditions. Pb isotopic signals reveal that the local weathered granitoid was the dominant source of Pb deposition. However, two isotopic excursions appeared from 15.5–15.2 and 5.2–4.8 ka BP, which coincide with the dry/cold H1 event and the mid- and late-Holocene respectively, likely suggesting an additional contribution of aeolian dust from North China. Even more, more radiogenic Pb signal of E2 exhibits a mixed contribution of enhanced anthropogenic mining. We expect strong enough EAWM would dominate these two intervals. Supported by multi-proxy records, we conclude that variations Pb isotopic signals (e.g., 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios) are closely related to climate-induced chemical weathering. Synchronous variations of 208Pb/204Pb, 206Pb/204Pb and 207Pb/204Pb ratios in the core display a congruent Pb isotope signals released from both U- and Th-rich accessory minerals. During intensive chemical weathering under wetter/warmer conditions (e.g., the Bølling and Allerød events, and the Holocene Optimum period), more preferential release of radiogenic 206Pb, 207Pb and 208Pb can be absorbed by fine detritus and then eroded to the lake thus resulting in increased 208Pb/204Pb, 206Pb/204Pb and 207Pb/204 ratios in sediments, and vice versa if a drier/colder climate dominates (e.g., the H1, the Older and Younger Dryas events, and the mid- & late-Holocene). The inferred changes in chemical weathering from Dahu sediments have varied in tandem with multi-regional monsoonal proxies in China, and exhibited a sensitive response of chemical weathering to global climate change. [ABSTRACT FROM AUTHOR]

This study presents the results of TOC/TN (C/N) ratio, δ13C and δ15N analyses of lake sedimentary organic matter (OM) from the Hedong section, western Guangdong Province in south China, with the objective to reveal the history of hydrological and ecological variations in the region influenced by both the Indian summer monsoon (ISM) and East Asian summer monsoon (EASM). Variations in δ13C and δ15N of sedimentary OM may be closely related to past climatic conditions, which results in variations in surface runoff, lake level, allochthonous and autochthonous sources of OM, and lake productivity. Based on the interpretation of these proxies, four periods, i.e. 4370–4100, 3700–2900, 2400–2100 and 1900–900 cal. a BP, are characterized by low lake level, weakened surface runoff and deteriorated status of terrestrial and aquatic ecosystems, whereas the periods 4100–3700, 2900–2400, 2100–1900 and 900–600 cal. a BP are dominated by high lake level, strengthened surface runoff, and flourishing terrestrial and aquatic plants. A remarkable positive correlation between the δ13C values of the section and the ENSO number record obtained from the tropical Pacific implies that the impact of the ISM is greater than that of the EASM in the study area. The abnormal correspondence between the δ13C and solar activity reconstructed from 10Be and 14C records in GRIP ice‐core occurred from 1500–800 and particularly from 4200–4000 cal. a BP, suggesting that these two cool and dry intervals may be caused by stronger volcanic activities that are recorded in the GISP2 and Dome C ice‐cores. This study reveals that changes in solar insolation and solar activity, as well as changes in oceanic–atmospheric circulation (e.g. the ENSO intensity) and intensive volcano eruptions may have exerted influence on late Holocene climate variability in the study area. [ABSTRACT FROM AUTHOR]

Wetlands act as persistent natural carbon sinks over long time scales. Understanding the response of these carbon reservoirs to climate change is critical to assessing potential climate feedbacks. We conducted a study of an 860‐cm‐long sediment core in Dahu Swamp in south China to determine how the carbon accumulation rate (CAR) has varied as a function of palaeohydrology and palaeoclimate over the past 47 000 years. From an orbital time scale, our results show that the CAR in Dahu Swamp is relatively low in the wet periods of Marine Isotope Stage 3 (MIS 3) (mean: 46.7 gC m−2 a−1) and MIS 1 (mean: 28.2 gC m−2 a−1), compared to the dry periods of MIS 2 (mean: 59.9 gC m−2 a−1). At centennial and millennial scales, the highest CARs of Dahu Swamp mainly occur in organic‐rich silt or clay (gyttja) layers, which correspond to the relatively dry climate (e.g. c. 48 000–41 000, c. 33 000–32 000, c. 15 800–14 900 and c. 4400–4250 cal. a BP). The CAR of Dahu Swamp is mainly controlled by local hydrological variations that are closely related to the East Asian summer monsoon (EASM) intensity, which may be co‐influenced by orbitally induced summer insolation forcing and internal feedback processes (e.g. Atlantic Meridional Overturning Circulation and El Niño/Southern Oscillation). Based on comparison with the CARs in monsoonal regions of China, we consider that precipitation may be the key factor for wetland CAR in EASM areas, whereas temperature is more important in Qinghai–Tibetan Plateau regions under Indian summer monsoon influence. The CAR of Dahu Swamp provides valuable records of wetland carbon accumulation dynamics in subtropical monsoon regions, which contradict the traditional patterns in global northern wetlands. [ABSTRACT FROM AUTHOR]

A detailed environmental magnetic investigation has been performed on a sub-alpine sedimentary succession deposited over the past 15,400 years in Daping Swamp in the western Nanling Mountains of South China. Magnetic parameters reveal that fine grains of pseudo-single domain (PSD) magnetite or titanomagnetite are the dominant magnetic minerals in the lake sediments and surface soils collected from the catchment, which suggests that magnetic minerals in lake sediments mainly originated from surface soil erosion of the catchment. Variation of surface runoff caused by rainfall is interpreted as the main process for transportation of weathered soils into the lake. In the Last Deglacial period (LGP, 15,400–11,500 cal a BP), the influx of magnetic minerals of detrital material may have been significantly affected by the severe dry and cold conditions of the Last Glacial Maximum. Stabilised conditions of the catchment associated with increased vegetation coverage (e.g., 8000–4500 and 2500–1000 cal a BP) limited the input of magnetic minerals. Intensive soil erosion caused by increased human activity may have given rise to abnormal increases in multiple magnetic parameters after 1000 cal a BP. Because changes in runoff and vegetation coverage are closely related to Asian summer monsoon (ASM) intensity, the sedimentary magnetism of Daping Swamp provides another source of information to investigate the evolution of the ASM. [ABSTRACT FROM AUTHOR]