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• A multiple-drought cascading framework based on causal inference was proposed. • Multiple-drought cascading risks were quantified by considering multiple time lags and complex factors. • The cascading risk of SD and GD peaks at a 3-7 month lag, during which time GD is most significantly influenced by vegetation. Comprehensively evaluating evolution of drought has an important guiding significance to drought early warning systems and disaster control. Drought is a major natural disaster. Although there are multiple methods including statistics to study drought propagation at present, the evolution of droughts is a complex phenomenon, existing physical and data-driven methods demonstrate unsatisfactory estimation performance. To address this issue, a new type of multiple-drought cascading framework was proposed. The peculiarity of this framework is that based on the principle of causal inference, a generalized linear regression model was established to quantify cascading effect of multiple droughts in disaster chain systems and explore influences of complicated factors outside the system on the cascading effect. The proposed framework was evaluated based on meteorological, soil and groundwater drought conditions of the Yanhe River basin, China. The results prove that study from the perspective of cascading disasters can intuitively characterize disasters of different types of drought signal propagation in the disaster chain system. The results also revealed a top-to-down drought long-chain cascading relationship in moisture transfer in the atmosphere, pedosphere, and lithosphere and discovered that climate change and vegetation restoration are the primary influencing factors of different links. In the framework, a novel model was constructed to quantify multiple-drought cascading effect considering influences of complex factors to facilitate the enhancement of policy planning and can help reduce negative influences of multiple cascading disasters. This framework is also expected to be applied in other areas to enrich the understanding of mechanisms underlying multiple-drought cascading disasters. [ABSTRACT FROM AUTHOR]

The use of conventional antibiotic therapies is in question owing to the emergence of drug-resistant pathogenic bacteria. Therefore, novel, highly efficient antibacterial agents to effectively overcome resistant bacteria are urgently needed. Accordingly, in this work, we described a novel class luminogen of 6-Aza-2-thiothymine-decorated gold nanoclusters (ATT-AuNCs) with aggregation-induced emission property that possessed potent antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA). Scanning electron microscopy was performed to investigate the interactions between ATT-AuNCs and MRSA. In addition, ATT-AuNCs exhibited excellent ROS generation efficiency and could effectively ablate MRSA via their internalization to the cells. Finally, tandem mass tag-labeling proteome analysis was carried out to investigate the differential expression proteins in MRSA strains. The results suggested that ATT-AuNCs killed MRSA cells through altering the expression of multiple target proteins involved in DNA replication, aminoacyl-tRNA synthesis, peptidoglycan and arginine biosynthesis metabolism. Parallel reaction monitoring technique was further used for the validation of these proteome results. ATT-AuNCs could also be served as a wound-healing agent and accelerate the healing process. Overall, we proposed ATT-AuNCs could serve as a robust antimicrobial aggregation-induced emission luminogen (AIEgen) that shows the ability to alter the activities of multiple targets for the elimination of drug-resistant bacteria. [Display omitted] • Provide a novel antimicrobial AIEgen of ATT-AuNCs for the treatment of MRSA. • Propose possible mechanism of ATT-AuNCs in killing MRSA. • Depth understanding the mode of action of ATT-AuNCs against MRSA at the proteome level. • Find 13 important differentially expressed proteins and their biological pathways. • Promote the healing of MRSA-infected wound. [ABSTRACT FROM AUTHOR]

• CUE had different sensitivity to clipping and warming. • Clipping significantly increased CUE due to the stronger positive effects of clipping on GEP than on ER. • Warming had a minor effect on CUE attributed to the synchronized increase in GEP and ER. Ecosystem carbon use efficiency (CUE) is a critical variable in quantifying the efficiency and capacity of an ecosystem to sequestrate carbon (C) from the atmosphere. However, how CUE responds to land-use change and climate warming remains elusive and lacks empirical evidence. We implemented a field manipulative experiment to examine the effects of clipping and warming on CUE in an alpine meadow on the Qinghai-Tibetan Plateau over 7 years. The results showed that clipping significantly increased CUE by 7.1%, which was mainly attributed to the stronger positive effects of clipping on gross ecosystem productivity (GEP, 13.0%) than on ecosystem respiration (ER, 5.3%). In contrast, warming had a minor effect on CUE due to the synchronized increase in GEP (8.8%) and ER (7.3%). There was no significant interactive effect of clipping and warming on CUE. Moreover, the dominance of grasses played a pivotal role in controlling the responses of CUE to clipping and warming by increasing ecosystem C uptakes but decreasing microbial decomposition. Soil temperature and above-ground net primary productivity also contributed to the changes in CUE under clipping and warming. These results suggest that clipping once a year at the end of the growing season could increase the efficiency of this alpine meadow for C sequestration, while climate warming could not change ecosystem C use efficiency. We highlight that the dominance of grasses is an emerging property in determining CUE under land-use change and climate warming in grasslands. [ABSTRACT FROM AUTHOR]

To guide a robotic swarm in a cluttered environment, a curve virtual tube is designed in this paper. There is no obstacle within the curve virtual tube, and the area inside can be seen as a safety zone. Then, a distributed swarm controller is proposed with three elaborate control terms. Formal analyses and proofs show that the curve virtual tube passing-through control problem can be solved in a finite time. For convenience in practical use, a modified controller with an approximate control performance is put forward. Some control laws for different types of robots to track their vector fields are also presented. The effectiveness of the proposed method is validated by numerical simulations and real experiments. To show the advantages of the proposed method, the comparisons between our method and other methods are also presented. [ABSTRACT FROM AUTHOR]

• A novel social-ecological coupling model was established. • The degree of coordinated development of human-water relationship in the basin was quantified by the characteristic parameters in the Budyko framework. • The human-water relationship will reach moderate coordination development in the future is predicted. Correctly understanding the coordinated development between the social economy and the ecological environment is the key to achieving the sustainable development of river basins. Previous coupling coordination degree models are empirical ones and very complex, without physical parameters. Here, a novel social-ecological coupling model was established to meet the challenge. Within the Budyko framework, n D was adopted to characterize the social-ecological coupling coordination degree of the human-water relationship in basins. In addition, a social-ecological coupling coordination model with basins in northern Shaanxi Province, China as units. The multiple linear regression (MLR) model was used to quantitatively analyze the evolutional relationship between economic development and ecological environment. Research results show that R2 is larger than 0.6 in the comprehensive evaluation results of the novel model. This means that the model can well reflect changes in vegetation coverage and simplify expression of the coordinated development of social-ecological systems. The evaluation results of the human-water relationship in the basins are gradually improved year by year and the coordination state evolved constantly. The two systems have positive promotion effects on each other. The social-ecological coupling coordination degree (D) is spatially different, and various basins are listed in a descending order as the Yanhe, Wuding, and Kuye river basins according to D. D of the three basins all evolves from 0.2 (moderate incoordination) to 0.6 (mild coordination). Combined with analysis of ARIMA time series, it is anticipated that the human-water relationship will reach moderate coordination by 2030. Finally, without changing the premise of the social-ecological coupling model, limitations of the current model factors can be improved for future research to provide policy suggestions exploring ways to coordinate development of social-ecological systems in northern Shaanxi. [ABSTRACT FROM AUTHOR]

• Machine learning techniques are applied to predict long-term prestress loss of prestressed reinforced concrete cylinder structures. • Explicit functions of concrete shrinkage and creep are proposed by using genetic programming (GP). • Finite element analysis model considers the long-term prestress loss under multi-factor coupling is established to expand the experimental database. • The prediction models of the long-term prestress loss based on GP, ANN and CNN are validated to be accurate and efficient by practical engineering. The long-term prestress loss caused by shrinkage and creep of concrete and stress relaxation of prestressed tendons has significant effects on the sealability and safety of prestressed concrete cylinder structures such as nuclear reactor containments and liquified natural gas (LNG) tanks. By utilizing machine learning (ML) techniques, this study aims to establish an intelligent approach for the long-term prestress loss prediction of concrete cylinder structures. Firstly, based on the Infrastructure Technology Institute of Northwestern University (NU-ITI) database of concrete shrinkage and creep performance, the explicit expressions are presented for concrete shrinkage and creep function using genetic programming (GP); Moreover, the concrete constitutive model is incorporated into a general finite-element software package based on the ABAQUS UMAT platform. Then finite element analysis (FEA) models are established and calibrated based on the existing long-term prestress loss tests of prestressed concrete beams. In addition to the experimental results in the literature, the numerical results of the FEA model are also used to form the database of the long-term prestress losses for concrete cylinder structures. Finally, three prediction models of long-term prestress loss are proposed by utilizing the artificial neural network (ANN), one-dimensional convolutional neural network (1D CNN) and genetic programming (GP). Compared with the measured results of nuclear containments in practical engineering, the ML based prediction models are demonstrated to be accurate and efficient in evaluating the long-term prestress loss for prestressed concrete cylinder structures. [ABSTRACT FROM AUTHOR]

A promising bio-based and biodegradable polybutyrolactam (PBY) fiber with health care function was prepared for the first time by dry-jet-wet spinning. As-prepared PBY fibers possesses the degree of crystallization upto 45.61%, appreciable thermal stability, excellent strength upto 2.1 cN•dtex−1, as well as good resistance to alkalis based on the results of X-ray diffraction, thermal and physical properties. The bio-degradability of PBY fibers were evaluated by the degraded behavior in soil, UV aging irradiation and seawater, showing commendable bio-degradation within 100 days. The analysis of the degradation based on TGA demonstrates that the removal of oligomers preferentially occurs, and then PBY macromolecules are broken. More interestingly, pharmaceutical γ -aminobutyric acid (GABA) is released during the degradation process, and it is beneficial to health care. As a biomass-derived and bio-degradable fiber, the sustainable PBY fiber exhibits an impressively competitive tensile strength among the existing degradable man-made fibers, showing great potential in bio-based fiber materials and health care textiles. [Display omitted] • Polybutyrolactam fiber was prepared for the first time by dry-jet-wet spinning. • The tensile strength of fiber reaches to 2.1 cN.•dtex−1. • Showing a commend bio-degradation performance within 100 days. • Pharmaceutical GABA is released during the degradation process. [ABSTRACT FROM AUTHOR]

• FE model for PC slab subjected to hard missile impact is established and verified. • Prestress in concrete is the main reason for the ballistic resistance increase. • Contribution of prestressing bars to ballistic resistance increase is moderate. • Semi-empirical formula for crucial perforation velocity of PC slabs is proposed. Prestressed concrete (PC) structure has been extensively used in civil engineering like nuclear and protective structures. But systematic studies on its ballistic performance are still inadequate, hindering its ballistic design and applications. In this paper, the ballistic performance of PC slabs subjected to hard missile impact is numerically investigated through finite element (FE) modeling. The method to introduce prestressing force is specially investigated and the feasibility of the established models is verified against existing experimental results. The models are then employed to conduct a comparative study between PC and reinforced concrete (RC) slabs, in which the influences of the prestress and prestressing bars are decoupled. The variations of concrete tensile strain and energy dissipation capacities of PC slabs with different failure modes are analyzed to understand the mechanism of the ballistic resistance. It is revealed that the prestress is the main reason for the enhancement of ballistic resistance of PC slabs, while the increase of reinforcement ratio due to prestressing bars is the secondary reason. It is also proved that the confinement effect applied to the concrete is the major reason for the increase in ballistic resistance. Based on the mechanism, by using mechanical and regression analysis, a semi-empirical formula for the critical perforation velocity of the PC slabs is proposed, which gives better predictions compared to existing formulas. The proposed formula also allows a straightforward parametric study, the results of which could be used for simplified estimations in the ballistic design of PC slabs. [ABSTRACT FROM AUTHOR]

• A total-sliding-mode-control (TSMC)-based distributed secondary control (TSMC-DSC) scheme is designed. • Using an adaptive fuzzy-neural-network (FNN) to mimic the TSMC-DSC law. • A model-free control structure with favorable convergence speed, no chattering phenomenon, and strong robustness. • Training AFNN-DSC parameters online adaptively. • The network convergence as well as the Lyapunov stability. In this study, an adaptive fuzzy-neural-network (FNN) control scheme is proposed for an islanded micro-grid (MG) as a distributed secondary controller (DSC) to achieve the aims of voltage and frequency restoration and the optimal power sharing. Firstly, the dynamic model of an islanded MG is built, which consists of an inverter-interfaced distributed generation (DG) model and a MG architecture model. The DG model can be represented by considering the dynamics of a primary controller with an optimal active power sharing scheme. The MG architecture model is composed of power flow dynamics and loads. Then, a consensus-algorithm-based error function is defined, and a model-dependent total sliding-mode control (TSMC) technique is presented for dealing with synchronization and tracking problems. Moreover, an adaptive FNN (AFNN) scheme is designed to mimic the TSMC law to inherit its fast dynamic response with robust properties. Meanwhile, the requirement of precise information of the MG dynamic model in the TSMC law can be relaxed by the AFNN scheme. Adaptive tuning algorithms for FNN network parameters of the AFNN-based DSC (AFNN-DSC) strategy are derived by using the projection algorithm and the Lyapunov stability theorem, which can guarantee the stability of the AFNN-DSC-controlled system. The effectiveness of the proposed control method is verified by numerical simulations for real scenarios. © 2017 Elsevier Inc. All rights reserved. [ABSTRACT FROM AUTHOR]

The abuse of antibiotics has triggered the rise of drug-resistance bacteria, which has seriously threatened public health globally. As a result, carrying out efficient and accurate antibiotic and bacteria identification are quite significant but challenge. Herein, an unprecedented Cd-MOF-based sensor, [CdL] n [ 1 , H 2 L = 4-(2-methyl-1H-benzo[ d ]imidazol-1-yl) isophthalic acid] with multiple fluorescence response behaviours towards antibiotics and bacteria was developed. Single-crystal X-ray diffraction revealed that 1 is a mesomeric 2D bilayer, which is comprised of two opposite chiral mono-layers, each assembled by left-handed or right-handed helixes. More interestingly, 1 represented multiplex detection capability towards antibiotics and bacteria through two detection behaviors: toward nitro-antibiotics and chlortetracycline (CTC) via fluorescent quenching, while toward Staphylococcus albus (S. albus) via fluorescent enhancement. Remarkably, 1 showed a low limit of detection (LOD, 47 CFU/mL) accompanied with specificity in the detection of S. albus compared to other bacteria, such as Staphylococcus aureus , Acinetobacter baumannii , Klebsiella pneumonia , Pseudomonas aeruginosa and Escherichia coli. In addition, the LOD could reach to ppm level for nitro-antibiotics and CTC. Moreover, the practical application of 1 was further reinforced through the detection of nitro-antibiotics and CTC, as well as S. albus in fetal calf serum and river water. [Display omitted] • An unprecedented highly stable Cd-MOF multiple fluorescence sensor was reported. • This sensor can rapidly and efficiently identify antibiotics or bacteria. • It can be as "turn-off" sensor towards nitro antibiotics and chlortetracycline. • It can be as "emission enhancement" sensor towards Staphylococcus albus. [ABSTRACT FROM AUTHOR]

Multicopters have been attracting increasing attention in recent years, while it is significant to consider the flight safety of multicopters in the presence of propulsor faults or failures. Therefore, this paper presents a methodology to analyze the controllable probability of a multicopter with arbitrary configurations based on controllability theory and an available control authority index. The methodology is then used to analyze the controllable probability of multicopters with different propulsor numbers and configurations to show its effectiveness. Based on the controllable probability results, an optimal configuration method is given. [ABSTRACT FROM AUTHOR]

The emergence of drug-resistant bacterial strains has challenged the use of traditional antibiotic therapies. Therefore, there is an urgent need to develop novel antibacterial materials or methods to effectively eradicate bacteria. Herein, we demonstrated a novel antibacterial system consisting of cupric oxide nanoparticles combined with ascorbic acid (CuO NPs/AA), which could act as a potent nanoantibiotic targeting both Escherichia coli (gram-negative) and Staphylococcus aureus (gram-positive) in vivo and in vitro , without noticeable cytotoxicity to mammalian tissue. The CuO NP/AA antibacterial system killed these microbes through a combined mechanism involving biofilm inhibition, cell membrane destruction, DNA damage, and enzyme inactivation. The antibacterial properties of CuO NPs/AA were mainly attributed to the generation of reactive oxygen species (e.g., ·OH) produced through the intrinsic ascorbate oxidase- and peroxidase-like activities of CuO NPs, highlighting their use as antibacterial nanozymes to treat bacterial infections. • CuO NPs/AA was demonstrated as a novel antibacterial system. • CuO NPs/AA has potent nanoantibiotics targeting both E. coli and S. aureus in vivo and in vitro. • CuO NPs/AA killed microbes through a combined mechanism. • CuO NPs/AA generated ·OH through the CuO NPs' intrinsic ascorbate oxidase- and peroxidase-like activities. • The biological applications of bifunctional CuO NPs can be extended. [ABSTRACT FROM AUTHOR]

The Weihe River Basin (WRB) in a monsoon transition zone of East Asia interacts with multiple weather systems and is susceptible to floods and droughts. We developed a framework based on the Empirical Orthogonal Function analysis, Complete Ensemble Empirical Mode Decomposition with Adaptive Noise analysis, and moving-average based Spearman rank correlation to identify the spatial patterns of the dry/wet conditions from 1470 to 2016, decompose the dry/wet index into the leading components with a period between 2 and 3 years and 100+ years, and discover their driving forces on multiple time scales. Results show that WRB can be divided into four distinguishable hydroclimatic subregions located in the southeast, west, central, and north. The East Asian summer monsoon and South Asian summer monsoon impact this region mainly on the inter-annual and inter-decadal scales, while the impacts of ENSO, PDO, AO, and NAO are dominant on the multi-decadal and centennial scales. [Display omitted] • Developed a new framework to attribute dry/wet spatiotemporal variability on multiple time scales. • Revealed four unique hydroclimatic subregions for the Weihe River Basin. • Identified the effects of monsoons, plateau circulation, westerly, and solar activities on Weihe. • Dry/wet conditions of the subregions show opposite responses to solar activity. [ABSTRACT FROM AUTHOR]

• R h and R a are highly sensitive to warming and clipping. • Increased allocation of C toward below-ground cause the increasing in R a and R s. • Due to the changes in ANPP/BNPP and ST, warming effect vary largely with years. • Plant C allocation is an emerging property in determining R s under warming. Global warming and land-use change have profound impacts on soil respiration (R s), with consequent changes in carbon exchange between terrestrial ecosystem and atmosphere and its feedback to climate change. However, it is not clear how soil respiration and its components (heterotrophic respiration, R h ; and autotrophic respiration, R a) respond to long-term warming and clipping in alpine meadow, and what are the controlling factors for the responses of soil respiration. To answer these questions, we conducted a field experiment of warming and clipping in an alpine meadow on the Qinghai-Tibet Plateau from 2014 to 2019. Infrared heaters were used to simulate climate warming and plots were clipped once a year to mimic hay or biofuel harvest. The results showed that warming decreased R h by 5.06% but stimulated R a by 10.08% across years, while clipping enhanced R s , R h and R a by 12.31%, 18.65% and 1.29%, respectively, and marginally interacted with warming in impacting R a across the years. Furthermore, the warming effect on soil respiration and its components varied largely over years, which was mostly attributable to the changes in the ratio of above-ground to below-ground net primary productivity (ANPP/BNPP, A/B) and soil temperature. Increased allocation of photosynthate toward below-ground caused the gradual increase in R a and R s under long-term warming. While soil temperature changes explained the variation of warming effects on R h across years. The results demonstrated that soil respiration and its components in the alpine meadow are highly sensitive to climate warming and hay harvest but with large interannual variations in their responses. We highlight that plant carbon allocation is an emerging property in determining soil respiration under climate warming. [ABSTRACT FROM AUTHOR]

The rapid urbanization and frequent occurrence of extreme weather have made flooding more frequent; tide-sensitive areas are more prone to flooding due to tide level. However, the extent of their respective impacts on flood variability in the context of the combined effects remains to be explored. Therefore, analysis of the driveability of the water level is important for regional flood control. Land use data from 1985 to 2015 was used in this study to analyze the characteristics of the changes. General trends, abrupt variability, and persistence of rainfall, tide, and water level data from 1957 to 2018 were analyzed. The influence of rainfall, tide level factors and underlying surface on water level variation was analyzed qualitatively and the contribution of the three factors to water level variation was quantified. The results indicate that the most important directions of land-type transformation were the construction land and arable land. Within the rainfall sequence, only the 3d rainfall sequence exhibited a significant increasing trend, while both tide level and water levels showed significant increasing trends. The 3d rainfall sequence and tide level sequence are significantly positively correlated with water level sequences, whereas among the underlying surface factors, only construction land and unused land are significantly positively correlated with water levels. Furthermore, the contribution rates of driving factors vary across different regions. In the Changzhou region, the underlying surface factors dominated with a relative influence of 62%., whereas for other regions, the combined relative influences of rainfall and tide level are 57.2%, 52.8%, 60.4%, and 66.9%, The methods and results of this study contribute to regional flood regulation. • The main directions of conversion of land type are construction land and arable land. • Rainfall and tide level are positively correlated with water level in an upward trend. • The rainfall and tide level factors are the dominant factors influencing the rise in water level. • The net effect of human activities on changes in water level is actually not very strong. [ABSTRACT FROM AUTHOR]

• Ecosystem service supply is related to regional natural conditions. • Ecosystem service demand is related to regional socio-economic development. • Land-use change was intense and urban expansion was noticeable from 2000 to 2020. • Ecosystem service supply and demand show significant spatial correlation. • Study scale has impacts on coupled matching of ecosystem service supply and demand. Ecosystem services are the environmental basis of human living and sustainable development, and the coupled matching of ecosystem service supply and demand (ESSD) plays an important role in socioeconomic and eco-environmental development. As one of the major regions supplying ecological products in China, the Shandong Peninsula urban agglomeration (SPUA) has unique geographical advantages and a strategic position. Based on high-resolution land-use and regional socioeconomic development data in SPUA, this study used value quantity assessment and an ecosystem service demand model to quantify ecosystem service supply (ESS) and ecosystem service demand (ESD) at both the city and county scale in 2000, 2010 and 2020. Meanwhile, the CA-Markov model was used to predict the potential land-use, the Moran index and Getis-Ord Gi* index were used to analyze spatial clusters of ESS and ESD, and a coupling coordination degree model and matching index were used to analyze the relationship between ESS and ESD. The results show that: (1) The most prominent land-use change in SPUA from 2000 to 2020 was the conversion of cropland to other land-use types; the process of land-use change was more intense from 2010 to 2020 than from 2000 to 2010; and the center of city activities might expand by 2030, which is related to the regional development plan. (2) The ESS was related to the regional natural conditions. Coastal regions or regions with abundant natural resources in SPUA had higher ESS, and the southwest region had lower ESS in SPUA. The ESS presented high–high clusters, low–low clusters and hot spots, and the cluster phenomena gradually diminished from 2000 to 2020. (3) The ESD was related to the regional location and economic development, with the southwest region of SPUA having a higher ESD than the northeast. The ESD presented low–low clusters, and Jinan and Qingdao had hot spots, which are the most developed cities in SPUA. (4) The study scale had impacts on coupled matching of ESSD. Coupled matching of ESSD was found to be unbalanced at the county scale from 2000 to 2020, but tended to be balanced at the city scale, which was related to resource management at different spatial scales. This study reveals the evolution and coupled matching of ESSD at different scales, which has important implications for the sustainable development of regional urban agglomerations. [ABSTRACT FROM AUTHOR]

The photocatalysis for environment purification and clean energy production has attracted widespread attention, however, traditional powder-form photocatalysts cannot meet the practical application due to their poor recyclability, especially in slurry system. Here, polypyrrole/cadmium sulfide/nickel (PPy/CdS/Ni) multi-layer hollow fibrous photocatalyst with favorable photocatalytic activity for pollutants removal and hydrogen (H 2) evolution was successfully fabricated, which possesses a narrow band gap of ∼1.87 eV and enhanced visible-light photocatalytic activity. The removal efficiency of methylene blue (MB) and tetracycline can reach up to ∼94.76% and ∼76.1%, respectively. Simultaneously, the TOC removal efficiency with regard to MB can reach up to 78.1% and Cd2+ leakage is extremely low (<3 mg⋅L−1). More interestingly, H 2 evolution rate of PPy/CdS/Ni hollow fiber is up to as high as 665.7 μmol⋅g−1⋅h−1, which is about 1.43 and 1.86 folds higher than the PPy/CdS/Ni/PET fiber (466.3 μmol⋅g−1⋅h−1) and CdS/Ni/PET fiber (357.1 μmol⋅g−1⋅h−1), respectively. As a fiber-form intrinsic photocatalyst, our catalytic fiber shows great promise for pollutants removal and hydrogen energy production due to its easy-handling and recyclement. [Display omitted] • A novel PPy/CdS/Ni hollow fiber with photocatalytic activity was synthesized. • Pollutant removal efficiency and H 2 evolution rate are appreciable. • Possible photocatalytic mechanism was proposed. • PPy/CdS/Ni hollow fiber shows good photocatalytic stability and recyclability. [ABSTRACT FROM AUTHOR]

• Both multiple quadcopters grouped to different blocks and one block are considered. • Spraying time is reduced by 10.8% and 13.2% in simulation and actual flight tests. • The optimization complexity of one quadcopter's path planning is significantly reduced. • A simulation prototype by MATLAB GUIs and Stateflow is built for mission planner. As the approaching of Agriculture 4.0 era and advancements of new technologies of Unmanned Aerial Vehicles (UAVs) and particularly quadcopter UAVs, plant protection quadcopters are becoming increasingly popular and practical in pesticide spraying, fertilization, pollination, seeding, and other agricultural activities. One of the main problems for plant protection quadcopters is completing planning tasks efficiently and quickly. Therefore, this paper proposes an autonomous task assignment and decision-making method for coverage path planning by multiple cooperative quadcopters. The Sequential Quadratic Programming (SQP) method is adopted to acquire the optimal solution for the proposed problem. Then, a simulation platform by MATLAB Graphical User Interfaces (GUIs) is established using the Stateflow technique, and multiple ZY-UAV-680 quadrotor UAVs are employed to carry out the actual flight tests. Finally, simulations and actual flight tests are conducted to demonstrate the effectiveness of the autonomous optimal task assignment and decision-making method. The final results show that: the proposed method can divide multiple UAVs reasonably to several blocks; the time differences between the simulation test and real flight test are only 39.8 sec and 20.6 sec, and accounts for 6.6% and 3.9% of the spraying time spent on real flight test by three cooperative quadrotors, respectively; the optimal scheme can save 60.8 sec and 80.0 sec in the simulation tests and the real flight tests, which accounts for 10.8% and 13.2% of the time spent on average scheme, respectively. Therefore, it can be concluded that the simulation results can match the real flight test results quite well regardless of average scheme or optimal scheme, and the optimal scheme is more efficient and timesaving than the average scheme. [ABSTRACT FROM AUTHOR]

Low-altitude aircraft is being developed as a new mode of urban transport; consequently, the penetration of low-altitude aircraft into the urban airspace is inevitable in the near future. This will give rise to new urban air transport systems, called low-altitude air city transport (LAAT) systems. Such systems will include aircraft operated with or without pilots, transferring passengers and goods in urban areas using low-altitude levels of urban airspace. This paper investigates the collective and aggregate aircraft traffic flow diagrams, i.e. Macroscopic Fundamental Diagrams (MFDs), for LAAT systems. A LAAT plant model that captures the microscopic and macroscopic levels is established to construct the MFD curve, which links flow, density, and speed. The MFD allows us to identify the airspace traffic conditions, and to detect congested regimes. Different case study examples were simulated to analyze the full shape of MFD curves for LAAT systems, considering different algorithms (waypoints and destination plane), aircraft, and airspace settings. In this paper, a unique modeling framework for LAAT operation and a real-time synchronized implementation of large-scale LAAT simulation were developed. The findings of the current paper, the development of LAAT simulation environment, and the identification of airspace traffic conditions, can lead to the development of aggregate models and new control strategies to minimize congestion in futuristic urban airspace. • Investigating the collective and aggregate aircraft traffic flow diagrams. • Developing a LAAT plant model that captures the microscopic and macroscopic levels. • Developing a real-time synchronized implementation of large-scale LAAT simulation. [ABSTRACT FROM AUTHOR]

Sesamol (SEM), a lignan from sesame oil, exhibited potential benefits on obesity treatment by promoting browning of adipocytes, and the current study is aimed to explore the molecular mechanisms of SEM from the aspect of systemic liver-adipose crosstalk that mediated by hepatic fibroblast growth factor 21 (FGF21). Our in vivo data showed that SEM induced energy expenditure and white adipose tissue (WAT) browning by increasing the expression level of uncoupling protein-1 in high fat diet induced obese C57BL/6J mice. Elevated levels of circulating FGF21 associated with the increased expression of hepatic FGF21 were observed after SEM intervention. Simultaneously, the increased adipose fibroblast growth factor tyrosine kinase receptor 1/beta-klotho indicated that FGF21 sensitivity was enhanced by SEM in WAT. Furthermore, our in vitro results from HepG2 and 3T3-L1 cell lines confirmed the effects and revealed the mechanism of SEM on the white adipocytes browning. We found that with the specific inhibitors of PPARα, the SEM-mediated hepatic FGF21 expression was decreased, and with the specific inhibitors of PPARγ, the browning effect of adipocytes by SEM combining with FGF21 was significantly suppressed. Taken together, the mechanism of SEM for inducing the WAT browning might be the modulation of SEM on liver-adipose crosstalk mediated by FGF21, and the PPARs family might be the targets of SEM. The novel findings from the present study provided evidence that SEM could be a potent obesity-treating compound. [Display omitted] [ABSTRACT FROM AUTHOR]

• The process of making sea-slurry ice with specific ultrasonic wave can reduce the subcooling degree during seawater crystallization. • When the experimental working condition is 33 kHz and 600 W, its overall performance is the best. • The subcooling degree is effectively reduced by 8.6 °C, the preparation process time is shortened by 90 s, the average crystal size of sea-slurry ice is refine to 20 µm. • The actual energy consumption rate is effectively reduced by 40%, and the evaporator temperature is risen 10 °C. In order to reduce the energy consumption in the process of making sea-slurry ice, this research is based on the related theory of the promotion of solution crystallization by ultrasonic wave, and conducts an experimental study on the energy-saving effect of the process of making sea-slurry ice from seawater under the action of ultrasonic wave. The orthogonal experimental study was carried out on the production of sea-slurry ice from seawater solution by using ultrasonic waves of different frequencies under a specific power. The results show that the process of making sea-slurry ice with specific parameters (power/frequency) can increase the seawater crystallization speed and reduce the subcooling degree during seawater crystallization. When the experimental working condition is 33 kHz and 600 W, its overall performance is the best. Compared with the no ultrasonic condition its subcooling degree is effectively reduced by 8.6 °C, the preparation process time is shortened by 90 s, the average crystal size of sea-slurry ice is refine to 20 µm, the actual energy consumption rate is effectively reduced by 40%, and the evaporator temperature is risen to −5 °C. [ABSTRACT FROM AUTHOR]

Autopilot systems on unmanned aerial vehicles (UAVs) are safety-critical systems whose requirements on reliability and safety are ever-increasing. However, testing a complex autopilot control system is an expensive and time-consuming task, which requires massive outdoor flight tests during the whole development stage. This paper presents an indoor automatic test platform for autopilot systems aiming to significantly improve the development efficiency and safety level of UAVs. First, a unified modeling framework is proposed for different types of aerial vehicles to make it convenient to share common modeling experience and failure modes. Then, a real-time simulation platform is developed by using automatic code generation and FPGA-based hardware-in-the-loop simulation methods to ensure simulation credibility on software and hardware levels. Finally, an automatic test framework is proposed to traverse test cases during real-time flight simulation and assess the test results. In the verification part, the accuracy and credibility of the simulation platform are verified by comparing the obtained results with experimental results, and several successful applications on multicopters demonstrate the practicability of the proposed platform. [ABSTRACT FROM AUTHOR]

• A novel of bionic rectangular microchannel(BRM) with a hydraulic diameter of 1000 um was designed based on the bionic wall roughness(BWR) of dragonfly wings structure. • Using k-w (SST) model on the calculation of turbulence in the microchannel are effectiveness and reliability. • The existence of BWR can effectively increase the temperature and velocity fluctuation range of the fluid, and enhance the fluid disturbance and velocity, and generate a large number of regular vortex flow in a wide scope. • The effects of the bionic rectangular microchannel (BRM) on flow and heat transfer is significantly better than that of the smooth rectangular microchannel (SRM), and an enhancement of 218% in heat transfer was achieved compared to a SRM, and the thermal enhancement factor is 1.34. • Transition occurs when the re number range of flow in BRM is 933–1166. In order to strengthen flow and heat transfer performance of the smooth rectangular microchannel (SRM), a novel of bionic rectangular microchannel (BRM) with a hydraulic diameter of 1000 um was designed based on the bionic wall roughness(BWR) of dragonfly wings structure. The effect of BWR and different microchannel lengths, and BWR with different tiny structures on flow and heat transfer was investigated, and the optimal of BWR's parameter, arrangement, combination and Re number range were studied. The results indicated that the influence of BWR on the flow and heat transfer performance is significantly better than that of SRM. When the Re is 5830, the heat transfer performance of the BRM model is 2.08 times that of SRM, and the heat enhancement factor is 1.233. Moreover, the optimal BRM's maximum velocity of the fluid is 19.6 m/s, which is 3.1 times of that of SRM, and the maximum temperature is 14.3 K lower than that of SRM, and an enhancement of 218% in heat transfer was achieved compared to a SRM, and the thermal enhancement factor is 1.34. Compared with BWR effect, the influence of the entry effect on heat transfer can be ignored, and the existence of BWR increases the number and scope of fluid disturbance and brings a large number and a wide range of high speed vortex flow appears in BRM, and they are regularly distributed after each group of BWR and the central of the microchannel, which further increases the flow velocity and disturbance, and reduces the range of low-speed and high-temperature region near the wall, and finally enhances flow and heat transfer performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • ZnS/Ag 2 S@PES photocatalytic membrane with UV–vis-NIR full-spectrum response ability. • High photodegradation efficiency (MB ∼ 70 % & TC ∼ 58 %) can be achieved in dead-end filtration. • High-efficient pollutant photodegradation under NIR/solar light on high-turbidity wastewater. • The responsive longer-wavelength NIR light can penetrate high-turbidity wastewater. By the combination of photocatalysis with membrane separation technology, a concurrent strategy of near-infrared (NIR) photocatalytic degradation and flow-through filtration for the treatment of antibiotics and dye effluent are proposed. After the deposition of homogeneous polyether sulfone (PES) layer with zinc acetate seeds as zinc oxide (ZnO) precursor on PES substrate membrane fabricated by non-solvent induced phase separation (NIPs), a photocatalytic membrane comprising of zinc sulfide (ZnS), silver sulfide (Ag 2 S), and PES substrate (ZnS/Ag 2 S@PES) was fabricated using successive ion layer adsorption and reaction (SILAR) and ion exchange method based on the conversion of ZnO into ZnS. ZnS/Ag 2 S@PES photocatalytic membrane with UV–vis-NIR full-spectrum response ability due to the construction of p -Ag 2 S/ n -ZnS heterojunction can fulfil high pollutant photodegradation efficiency (methylene blue (MB) ∼ 70 % & tetracycline (TC) ∼ 58 %) in dead-end filtration by single pass. By simply two successive repeating units in flow-through filtration, more than 95 % of photodegradation efficiency for MB and TC can be achieved. More importantly, under NIR irradiation by the penetration of high-turbidity media and real turbidity wastewater, 68 % and 72 % of MB photodegradation efficiency can be respectively reached by only one unit within 1 h, which is expected to achieve the catalytic degradation to high-turbidity real industrial wastewater. [ABSTRACT FROM AUTHOR]

To navigate and control a single mobile robot or a robotic swarm with higher efficiency, a novel non-potential orthogonal vector field method is proposed in this paper, which is modified from the traditional artificial potential field method. The improvement strategy aims at making the overall repulsive vector field orthogonal to the attractive vector field in some conditions. And the same potential field function is still applied to the Lyapunov-based stability analysis. In short, such an improvement strategy combines the advantages of the artificial potential field method with the non-potential vector field method, namely a combination of theoretical completeness and control efficiency. Finally, the effectiveness of the proposed method is validated both by numerical simulations with statistical significance and real experiments. The comparisons between our method and other methods are also presented. [ABSTRACT FROM AUTHOR]

Additive manufacturing technologies have been proved as a promising method to achieve electrocatalysts with periodic micro-size pores, while the nano-sized interspace of the material structures and their corresponding gas bubbles transfer process are not explored in detail. Herein, we employ the shear force alignment in additive manufacturing to design NiMo-based structures with anisotropic porous channels as electrocatalysts for hydrogen evolution reaction (HER) in seawater. Based on the complementary experimental and theoretical investigation, the unique anisotropic structure not only fully exposes the active sites in the electrolyte, but also facilitates the rapid electrolyte-hydrogen phase conversion during electrochemical reactions. In this case, the obtained 3D electrode exhibits superior electrocatalytic performance and excellent long-term operational stability with an extremely low overpotential of ∼150 mV at a current density of 500 mA/cm2 in 1 M KOH seawater. This work will provide a practical scenario for designing highly-efficient HER electrocatalysts. [Display omitted] • Electrocatalysts with the anisotropic structure were fabricated with 3D printing technology. • The anisotropic porous structure was beneficial for gas bubble transfer behaviors. • The catalyst exhibits an overpotential of ∼150 mV (500 mA/cm2) in 1 M KOH seawater. [ABSTRACT FROM AUTHOR]

Continuously encircling and monitoring an individual static target is an important application scenario for a multi-UAV system. In this paper, to address the problem of multi-UAV encircling the target arbitrarily, evenly and densely in 3D space, a distributed vector field control method with an annular virtual tube is proposed. Some Lyapunov-like functions are designed elaborately, and a formal analysis based on the invariant set theorem is made to show that all UAVs can complete the encirclement task successfully. Simulations and experiments are carried out to show the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Due to the multiple electronic transmission channels established at the interface between NiMo cores and C 3 N 5 shells, the obtained NiMo@C 3 N 5 hybrids exhibit stable and efficient HER performance in seawater, which is superior to that of commercial Pt/C. [Display omitted] • Multiple electronic transmission channels were established between NiMo and C 3 N 5. • Induced electron redistribution effect optimized the HER reaction pathway. • The NiMo@C 3 N 5 catalyst shows excellent HER performance and stability in seawater. Designing highly efficient and stable electrocatalysts for hydrogen evolution reaction (HER), particularly in seawater, still remains a challenging task. Herein, the unique heterostructures composed of 1D NiMo cores and 2D C 3 N 5 shells (NiMo@C 3 N 5) are rationally designed and demonstrated as the robust HER catalysts in both alkaline electrolytes and natural seawater, where the carbon-based shell can effectively protect the catalyst core from seawater poisoning. Based on the experimental investigation and density functional theory calculation, multiple electronic transmission channels were found to establish at the interface between NiMo cores and C 3 N 5 shells, thus providing efficiently optimized HER pathways to achieve minimized overpotential with a reduced energy barrier of the rate-determining step. More importantly, the NiMo@C 3 N 5 hybrids exhibit stable HER performance with a high Faradaic efficiency of 94.8% in seawater, which is superior to that of commercial Pt/C. All these results can evidently highlight a feasible strategy to develop high-performance HER electrocatalysts via interface engineering. [ABSTRACT FROM AUTHOR]

Solar thermal membrane distillation is a promising technology for low-cost desalination and water purification. A novel photo-thermal conversion membrane composited by polyacrylonitrile (PAN) nanofiber layer and polyvinylidene fluoride (PVDF) with antimony tin oxide (ATO) as solar-thermal nanoparticles (PVDF-ATO/PAN nanofiber membrane) was fabricated by sequent electrospinning techniques. The dual-layer membrane with hydrophilic PAN and hydrophobic PVDF-ATO was examined by microscopic evaluation and contact angle measurement. In situ temperature increase on membrane superficial layer (PVDF-ATO) driven by solar light illumination was confirmed by thermal imaging system. PAN layer provides water transport channels for facilitating water flow of highly efficient membrane distillation and avoids the salting assembly during the vigorous evaporation. With the help of hydrophilic PAN layer, our PVDF-ATO/PAN nanofiber membrane can fulfill highly effective localized heating transfer with an evaporate rate of 0.93 kg m−2 h−1, showing great potential for low-cost water desalination and scalable water purification. [Display omitted] • A solar-thermal PVDF-ATO/PAN fiber membrane was yielded by sequent electrospinning. • PAN and PVDF-ATO contribute moisture transport and localized heating, respectively. • The resulting membrane has an appreciable evaporation rate of 0.93 kg m−2 h−1. • It exhibits robust heat localization, excellent durability, and good anti-fouling. • A desired solution to low-cost desalination & scalable water purification was done. [ABSTRACT FROM AUTHOR]

• N addition enhanced GEP and NEP only when volumetric soil moisture exceeded 15%. • GEP and NEP showed saturating responses to N addition only at high soil moisture. • N effects on C exchange were mediated by changes in species composition. • Temperature and soil moisture interactively regulate N effects on NEP, ER and GEP. Primary productivity in terrestrial ecosystems can be significantly altered by the predicted increases in nitrogen (N) deposition, but it is still unclear how N deposition influences the carbon (C) exchange processes especially in dryland ecosystems. In this study, a 3-year experiment with two types of fertilizers and five N addition levels was conducted in a semiarid steppe of Erguna, Inner Mongolia to assess the effects of exogenous N input on net ecosystem productivity (NEP), gross ecosystem productivity (GEP) and ecosystem respiration (ER). Our results showed that enhanced N input significantly increased NEP and GEP when the volumetric soil water content (VWC) was greater than 15% (v/v%), but had trivial and inconsistent effects when VWC was less than that threshold. Moreover, the NEP and GEP increased significantly with increasing N addition but leveled off when the N input reached 10 g N m–2 year–1 and the VWC was above 15%. However, the ER showed a significant increase with N addition rates, regardless of soil water content. Our main findings are as follows. First, the ecosystem C exchange can be significantly enhanced by addition of N only when soil moisture exceeds certain threshold, suggesting co-limitation of water and N in the grassland ecosystem that we studied. Second, in addition to concurrent consideration of water, temperature and N as well as their interactions also need to be accounted for. Third, the frequency of days with the VWC being higher than 15% accounted only around one third of days during the three growing seasons. Taken together, our findings imply that the expected increases of carbon sequestration should be minimal under N deposition in the Inner Mongolia grassland ecosystems. [ABSTRACT FROM AUTHOR]