Search

Habitat loss and fragmentation are critical threats that cause biodiversity loss. However, the driving factors of species diversity in fragmented habitats are complex. This study was conducted in the agro-pastoral ecotone of northern China, a region that has suffered from severe habitat fragmentation due to agricultural activities. Based on the plant species richness, patch characteristics (patch area, fractal dimension, and isolation), landscape characteristics (grassland area ratio within buffer zones with different radii (50–500 m) around each patch), and environmental characteristics (mean annual precipitation, mean annual temperature, altitude, extremely high temperature, extremely low temperature, slope, and aspect) of 82 remnant grassland patches, we first explored the appropriate buffer zone with the most powerful impact on species richness of remnant grassland patches (SRP). Furthermore, we analyzed the relationships between a series of predictors and SRP. Finally, we confirmed the critical driving factors of SRP through a random forest analysis. The results showed that the landscape scale with the most powerful impact on SRP was 150 m. The patch area, grassland area ratio of a buffer zone with a 150 m radius, mean annual precipitation, and slope all had significantly positive effects on SRP. Among these factors, patch area and patch isolation were the top two driving factors of SRP. Our study suggests that large and highly connected patches should be protected for the construction of natural reserves. Meanwhile, the habitat around patches within a suitable range should also not be ignored. We highlight that the island biogeography theory could be used to predict plant species richness of remnant grassland patches in the agro-pastoral ecotone of northern China.

Elucidating physiological mechanisms underlying the plant N uptake benefits breeding of high N use efficiency (NUE) crop cultivars. In this study, we investigated the growth and N uptake-associated processes in wheat under N deprivation and deficit irrigation, using two contrasting NUE cultivars. Compared with sufficient-N (SN), deficient-N (DN) treatment reduced plant biomass, N accumulation, and yields in two cultivars (high NUE Shinong 086 and N deprivation-sensitive Jimai 585), suggesting that N deprivation negatively regulates plant growth and N uptake. Shinong 086 was better on growth and N uptake-associated traits than Jimai 585 due to the improved root biomass across soil profile, which was consistent with the decrease of available N contents in soil layers. These results suggested that the improved root system architecture (RAS) enhances plant acquirement for soil N under N- and water-deprivation condition, contributing to the plant N uptake and yield formation capacities. Transcriptome investigation revealed that numerous genes were differentially expressed (DE) in the N-deprived Shinong 086 plants, which involve the regulation of complicate biochemical pathways. These results suggested that the modified RAS and N uptake in high NUE plants are accomplished underlying the regulation of numerous DE genes. TaWRKY20, a gene in ZFP transcription factor family, was functionally characterized for the role in mediating plant N uptake. Overexpression of it conferred plants improved growth and N uptake under DN due to its regulation on TaNRT2.1 and TaNRT2.2, two nitrate transporter genes. Our investigation provides insights in high NUE mechanisms in wheat under N deprivation.

Effective mass in the Dirac equation model is generally applied to condensed-matter systems for describing the state of electrons and determining the topological character. In these systems, the si...

Lithium sulfur batteries with high energy density are thought to be the most potential energy storage technology that can be commercialized. However, the shuttle effect of polysulfides deteriorates its electrochemical performance. Herein, a novel Co9S8 nanostructure derived from metal organic framework material (MOF) was explored by simple liquid phase reaction and heat vulcanization of 2-methylimidazole and Co(NO3)2·6H2O on the surface of the original PP separator. The Co9S8 nano-flower cluster array wall was vertically and closely arranged with the thickness of 200 nm, and the polysulfide can be adsorbed by its physical and chemical action to slow down the “shuttle effect”. It is found that the cell with the modified separator can achieve an ideal discharge capacity of about 600 mAh/g at 1 C. The specific capacity is maintained at 500 mAh/g after 200 cycles, with only 0.11 % of capacity decay per cycle. It provides a new way for the utilization of MOF material derivatives to modify the separator in order to improve the electrochemical performance of lithium-sulfur batteries.

The weft-knitted reduced graphene oxide (r-GO) textile that is made up of many conductive r-GO coated fibers was successfully prepared dependent on the electrospray deposition technique. Interestingly, the r-GO textile presents negative resistance variation not only in axial direction as the pressure increases but also in transverse direction as the lateral stretch increases which makes it has the advantage to fabricate the reliable sensors based on strain-resistance effect. The transverse-strain and pressure sensors based on the r-GO textiles all show the excellent sensing characteristics such as high sensitivity, reliability, and good durability, etc. The maximum gauge factors (GF) of the transverse-sensor are 27.1 and 153.5 in the x- and y-direction, respectively. And the practical detection range can up to 40% in the x-direction and 35% in the y-direction, respectively. The r-GO textile pressure sensor also shows high sensitivity for a broad pressure range that with a GF up to 716.8 kPa−1 for less than 4.5 kPa region and still has more sensitive pressure sensing characteristics even the pressure goes up to 14 kPa. Based on those good performances of r-GO textile sensors, its potential applications in human body states monitoring have been studied.

The vertical stability (VS) coil is a set of circle-shaped multilayer in-vessel coil that is arranged in the vacuum vessel. For International Thermonuclear Experimental Reactor (ITER) prototypical VS coil, to avoid the interference with other in-vessel components some small bending arcs are designed. They are the R600 S-shaped bending arc with the angle of 9.2°, the R600 W-shaped bending arc with the angle of 20.3°, 38.1°, 20.3°, and the R215 S-shaped bending arc with the angle of 53.6°. The forming parameters of these arcs are studied in the article. Given the fact of conductor rebound after bending, the key issues of forming the arcs are to determine the suitable wheel mold radius and rotation angle. With regard to the determination of wheel mold radius, the forming deformation states of conductor under different wheel mold radius are simulated. Then the conductor displacement data after rebound are extracted to acquire the conductor inner and outer arcs fitting equations and the corresponding conductor radii are obtained simultaneously. If the calculated conductor central radius is different with the target value, the wheel mold radius will be adjusted and new simulation is employed. The reiteration work is terminated until the target radius is obtained. Subsequently, the wheel mold radius obtained in the data fitting process is referenced to fabricate the matching wheel mold. And the forming experiment is launched to verify the feasibility of conductor bending based on the above wheel mold radius. As to the determination of wheel mold rotation angle, the bending simulation and data fitting are carried out first. Then the process is repeated continuously until the target bending angle is obtained. Finally, the obtained wheel mold rotation angle is assigned as the preliminary bending angle in the forming experiment. If the forming results fail to satisfy the angle requirement, the preliminary bending angle is adjusted slightly and the forming experiment is performed again until the target bending angle is achieved. In addition, wrinkles are found during the forming process for the R215 S-shaped arc. To deal with the wrinkle issue a series of forming technology are attempted, while nearly all of them seem to be not feasible. Finally, bushing is installed at the outer surface of conductor jacket to reinforce its strength and resist the buckling impact from magnesium oxide (MgO). The forming experiments indicate bushing technology successfully eliminates the large wrinkles on the jacket.

Outer-rotor switched reluctance machines (SRMs) have drawn much attention as promising candidates for in-wheel direct-drive motors of future electric vehicles. This article presents a systematic performance comparison of three outer-rotor SRM topologies for in-wheel traction applications in terms of the specific torque, electromagnetic efficiency, torque ripple, radial force, and mechanical aspects. A generalized design optimization framework for SRMs is proposed to enable the fast evaluation of large numbers of designs generated from the differential evolution by incorporating an analytical current profile estimation into the transient finite element analysis. The relationship between the saliency ratio and converter volt-ampere rating is also discussed. The calculations are then benchmarked with the experimental results from an existing prototype. The effectiveness of the performance prediction method and the proposed optimization approach is validated.

The branching crack model for earthquakes was developed by Vere-Jones and Kagan in the 1970s and the 1980s, respectively. With some simple and rational assumptions, its simulation results explain the Gutenberg-Richter magnitude-frequency relationship and the Omori-Utsu aftershock decay formula. By introducing the concept of the critical zone, this model can be connected with the asperity model, the barrier model, and the nucleation model through a parameter – criticality. Particularly, the size of the critical zone determines the maximum magnitude of potential earthquakes and the source of their anomalies. The key to earthquake forecasting is to determine whether the concerned area is in a critical state and how large the critical zone is. We discuss what kinds of anomalies are meaningful as candidates of earthquake precursors. Finally, we outline modelling strategies for earthquake precursors with low probability gains that are due to the inherent randomness of earthquake source processes.

In this paper, we propose a model for the transverse oscillation of a square-section cylinder under flow. The fluctuating transverse force due to vortex shedding is represented using a coupled nonlinear wake oscillator, while the unsteady force for galloping caused by the varying incidence angle effects is modelled using the quasi-steady approach. First, we analytically investigate the lift behavior and phase angle variation of the square cylinder under forced vibrations. Comparison with experimental data is used to determine the form of the coupling terms and its values. The present model shows advantages in predicting the phase angle, and it successfully captures the change in sign of the phase. Second, the proposed model is directly applied in predicting free oscillation cases without any tuning. The dynamical behaviors predicted by this model are compared with published experiments under different Scruton numbers, and reasonable agreement can be found. The results indicate that the model can not only be applied in simulating the “pure galloping” and “pure VIV,” but also is able to capture the interactions of VIV and galloping, including combined and separate VIV-galloping motions.

Smart materials with a combination of tough solid-like properties, fast self-healing and optical responsiveness are of interests for the development of new soft machines and wearable electronics. In this work, tough physically cross-linked elastomers that show high mechanical strength, intriguing temperature-adaptable self-healing and fluorochromic response properties are designed using aluminum (Al) and fluorescent europium (Eu) ions as cross-linkers. The ionic Al-COOH binding is incorporated to construct the strong polymer network which mainly contributes to the mechanical robustness of the elastomer consisting of two interpenetrated networks. The Eu-iminodiacetate (IDA) coordination is mainly used to build the weaker but more dynamic network which dominate the elasticity, self-healing and luminescence of the elastomer. Moderate Eu3+ and Al3+ contents give these supramolecular elastomers high toughness. The temperature-sensitive Eu-IDA coordination enables tunable self-healing rate and efficiency along with fast Eu-centered “ON/OFF” switchable red emission. The mechanical, self-healing and luminescence properties of these elastomers can be adjusted by tuning the ratio of the two types of metal ions. This elastomer is potentially applicable for biosensors, wearable optoelectronics and anticounterfeiting materials.

The safety issues and lower energy density of the lithium metal batteries are the two main challenges that hinder their applications in the fields of electric vehicles and portable devices. In this work, the semi-interpenetrated polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP)-based gel polymer electrolyte was synthesized through UV-curing method by employing the ethoxylated trimethylolpropane triacrylate (ETPTA) monomer. The semi-interpenetrating networks formed by polymerization of ETPTA and the high liquid absorption rate of the PVdF-HFP impart the as-prepared electrolyte with a high room temperature ionic conductivity of 3.17 × 10−3 s cm−1 and a high mechanical strength of 3.46 MPa. LiFePO4 was selected as cathode materials, and the active material loading of the cathode is about 4.2 mg cm−2. The electrolyte shows superior long-term cycling properties (127 mAh g−1 after 200 cycles at 0.5 C), excellent rate performance (113 mAh g−1 at 1 C, 80 mAh g−1 at 2 C, and the discharge capacity of 135 mAh g−1 can be restored when the rate goes back to 0.1 C) as well as good ability to inhibit the growth of lithium dendrite (about 150 h). The facile synthesis strategy and great electrochemical performance of the electrolyte make it a potential candidate for lithium metal batteries.

This paper addresses the problem of suboptimal control for repointing maneuver of a staring-mode spacecraft where the optical axis is required to point to the target orientation. Different from the traditional reorientation maneuver, the angle of the spacecraft around the optical axis does not need to be controlled. First, a simple yet efficient representation for repointing error is introduced and kinematical descriptions are established correspondingly. Then, two different control algorithms are proposed for repointing control of a staring-mode spacecraft. The first one is the inverse optimal PD-like controller that drives the spacecraft to complete repointing maneuver and the optimality properties of the proposed control law are investigated by using dynamic programming theory. The other one is a control Lyapunov function (CLF) based suboptimal control scheme incorporated with the idea of equivalent control in sliding mode control theory. The switch mechanism between CLF control and sliding mode control is established where only one control switch is needed when the state reach the sliding surface. Compared with the classical CLF method, the sliding mode based CLF approach not only guarantees the optimality, but also enhances the system robustness against model uncertainties and disturbances. Finally, numerical investigations are conducted to demonstrate the utility and optimality of the proposed control algorithm.

The investigation of single-pixel terahertz (THz) imaging opens up a new research direction for the development of THz imaging technology. In this work, we exploit a reflective single-pixel THz imaging system based on photoinduced dynamic masks. By combining the compressed sensing and inverse Fresnel diffraction algorithms, a reflective THz spectral image is accurately reconstructed and the morphology of a sample is clearly observed. Three application potentials of the THz imaging system are fully proved, including time-of-flight measurement of a sample with multiple interfaces, noninvasive testing of a hidden object, and spectral identification of different chemical substances. The reflection-type measurement mode effectively improves the practicability of single-pixel THz imaging.

With the rapid development of the global economy, maritime transportation has become much more convenient due to large capacities and low freight. However, this means the sea lanes are becoming more and more crowded, leading to high probabilities of marine accidents in complex maritime environments. According to relevant historical statistics, a large number of accidents have happened in water areas that lack high precision navigation data, which can be utilized to enhance navigation safety. The purpose of this work was to carry out ship route planning automatically, by mining historical big automatic identification system (AIS) data. It is well-known that experiential navigation information hidden in maritime big data could be automatically extracted using advanced data mining techniques; assisting in the generation of safe and reliable ship planning routes for complex maritime environments. In this paper, a novel method is proposed to construct a big data-driven framework for generating ship planning routes automatically, under varying navigation conditions. The method performs density-based spatial clustering of applications with noise first on a large number of ship trajectories to form different trajectory vector clusters. Then, it iteratively calculates its centerline in the trajectory vector cluster, and constructs the waterway network from the node-arc topology relationship among these centerlines. The generation of shipping route could be based on the waterway network and conducted by rasterizing the marine environment risks for the sea area not covered by the waterway network. Numerous experiments have been conducted on different AIS data sets in different water areas, and the experimental results have demonstrated the effectiveness of the framework of the ship route planning proposed in this paper.

Understanding the ecology and sustainability of the Inner Mongolian Grassland is crucial for improving land management policies in the Mongolian Plateau and beyond. However, a systematic and comprehensive review of the relevant literature is still lacking. This review was intended to: (1) assess the current state of the ecological and sustainability research of the Inner Mongolian Grassland region, and (2) identify critical research topics and challenges for understanding pathways to sustainability of the region. We conducted a bibliometric analysis of 2571 English articles indexed in the Web of Science during 1998–2019. Multiple methods, including descriptive statistics, principal component analysis, change point detection, theme mining, and association strength analysis, were combined to analyze the sampled literature. All reviewed studies can be grouped into four types: description of ecological and biogeochemical characteristics of degraded grasslands (type I), the impacts of climate change and human activities on aboveground (type II) and belowground grassland ecosystem functioning (type III), and the impacts of different management strategies on grassland ecosystem services and human well-being (type IV). The number of publications in all four themes has rapidly increased after 2007–2009. The four types of articles were related to each other in terms of the interannual publication consistency. Keyword co-occurrence network analysis showed that climate change and grazing were the major research topics, which are closely related to all other topics. Three perspectives have persisted in the ecology and sustainability research of the Inner Mongolian Grassland: Ecology in the Grassland, Ecology of the Grassland, and Sustainability of the Grassland. Based on the emerging landscape sustainability science framework, the transdisciplinary approach to landscape sustainability diagnostics and landscape planning and design should become a priority in advancing sustainability research of the region.

Nanobubbles have been reported to have many novel applications due to their unique physicochemical properties. Ethanol-water exchange is regarded as one of the most convenient methods for producing nanobubbles; however, it is still questioned whether this method can produce bulk nanobubbles or not. In this paper, we present a method to monitor the ethanol-water exchange process based on a setup that combines the equipment of the ethanol-water exchange with an apparatus for dynamic light scattering. In contrast to the previous works where the measurements were performed after the exchanges were completed, our method measures the intensity of the scattered light from the beginning of the process to the end. We found that three different stages of the exchange process can be easily distinguished and that the diameters of the particles produced decrease as the exchange time increases. Furthermore, the measured diameters agree very well with a theoretical model presented very recently for the stability of the bulk nanobubbles in the liquid. Based on these findings, we believe that the products of the ethanol-water exchange are bulk nanobubbles. In addition, since our experimental setup provides the details of the ethanol-water exchange process, it can be used to investigate how to control the parameters of the final nanobubbles, such as their size, concentration, etc., which might promote the potential applications of bulk nanobubbles.

Soil abiotic stresses can trigger bottom-up effects on insect pests. However, it remains unknown whether the bottom-up effects differentially affect leaf chewers and sap-feeders, and whether abiotic stresses alter the extent of indirect interactions between insect herbivores sharing a host plant. We carried out a set of manipulative experiments to investigate how abiotic and biotic stresses affected performance associated with insect herbivory (eating by leaf chewer or sap-feeder) and plant physiological conditions (manipulating water and/or salt inputs). We examined the performance of response species (sap-feeder Macrosiphum euphorbiae and leaf chewer Tuta absoluta) on tomato plants Solanum lycopersicum that were exposed to eight conditions in a full factorial design based on (1) optimal or limited water inputs, (2) with or without 100 mM NaCl, and (3) with or without pre-infestation by insect herbivors showing distinct feeding habit. Water and salt stresses slowed down plant growth in terms of plant height and node number, which subsequently negatively affected the herbivores via bottom-up effects. Tuta absoluta larval development was adversely affected by water limitation, while M. euphorhiae survival and fertility were adversely affected by salinity stress. After pre-infestation by the inducing species (i.e. feeding activity on the plant), the test species (either M. euphorbiae or T. absoluta) exhibited a lower performance, that is, lower M. euphorbiae survival and fewer offspring, and extended T. absoluta developmental duration and reduced pupal weight. These results suggested an apparent competition between the herbivores; however, neither water limitation nor salt stress affected the magnitude of the negative indirect interactions between the two insect species. Our findings shed light on how cascading force(s) and induced indirect resistance(s) could be used to improve integrated pest management programs.

Searching for energetic photovoltaic absorbers is a favorable solution to the current energy crisis. As a star material for solar cells, MAPbI3 (MA = CH3NH3) has a suitable band gap, strong optical...

In oxygen steelmaking, one important aspect is to depict the splashing induced by the impingement of multiple jets quantitatively. In this paper, experiments were conducted to investigate the splas...

Progress towards analysing transitions between steady states demands improvements in time-resolved imaging, both for fundamental research and for applications in information technology. Transmission electron microscopy is a powerful technique for investigating the atomic structure, chemical composition and electromagnetic properties of materials with high spatial resolution and precision. However, the extraction of information about dynamic processes in the ps time regime is often not possible without extensive modification to the instrument while requiring careful control of the operation conditions to not compromise the beam quality. Here, we avoid these drawbacks by combining a delay line detector with continuous illumination in a transmission electron microscope. We visualize the gyration of a magnetic vortex core in real space and show that magnetization dynamics up to frequencies of 2.3 GHz can be resolved with down to ∼122ps temporal resolution by studying the interaction of an electron beam with a microwave magnetic field. In the future, this approach promises to provide access to resonant dynamics by combining high spatial resolution with sub-ns temporal resolution., Ultramicroscopy, 233

The concentration levels of 36 airborne heavy metals and atmospheric radioactivity in total suspended particulate (TSP) samples were measured to investigate the chemical characteristics, potential sources of aerosols, and health risk in Beijing, China, from September 2016 to September 2017. The TSP concentrations varied from 6.93 to 469.18 μg/m3, with a median of 133.97 μg/m3. The order for the mean concentrations of heavy metals, known as hazardous air pollutants (HAPs), was as follows: Mn > Pb > As > Cr > Ni > Se > Cd > Co > Sb > Hg > Be; Non-Designated HAPs Metals: Ca > Fe > Mg > Al > K > Na > Zn > P > Ba > Ti > Cu > Sr > B > Sn > I > V > Rb > Ce > Mo > Cs > Th > Ag > U > Pt. The median concentration of As was higher than China air quality standard (6 ng/m3). The gross α and β concentration levels in aerosols were (1.84 ± 1.59) mBg/m3 and (1.15 ± 0.85) mBg/m3, respectively. The enrichment factor values of Cu, Ba, B, Ce, Tl, Cs, Pb, As, Cd, Sb, Hg, Fe, Zn, Sn, I, Mo, and Ag were higher than 10, which indicated enriched results from anthropogenic sources. Pb, As, and Cd are considered to originate from multiple sources; fireworks released Ba during China spring festival; Fe, Ce, and Cs may come from stable emissions such as industrial gases. The health risks from anthropogenic metals via inhalation, ingestion, and dermal pathway were estimated on the basis of health quotient as well as the results indicated that children faced the higher risk than adults during the research period. For adults, the health risk posed by heavy metals in atmospheric particles was below the acceptable level.

The design and fabrication of uniform and compact nanocomposite coating with excellent anticorrosion performances are critical in reducing the metal consumption. Herein, we describe a facile and ingenious strategy to obtain a polymer coating that consists of well-dispersed nanosheet fillers via preparing highly ordered layered double hydroxides (LDHs) nanosheet arrays on oxidized graphite fiber (OGF) (as support body and dispersion phase). We found that the incorporation of 0.5 wt.% OGF-LDHs into the polyvinyl butyral (PVB) matrix caused excellent long-term anti-corrosion performance of mild steel in 3.5 wt.% NaCl solution. The uniformly staggered OGF-LDHs acted as a three-dimensional shielding against the corrosive media. The present study, together with a facile and highly efficient method of excellent anticorrosion nanocomposite coating fabrication paved an important step towards real-world applications of anticorrosive coatings using polymer/LDHs composites.

In this study, the Harmonia axyridis vitellogenin gene 2 (HmVg2) sequence was identified from transcriptomic databases of female adult H. axyridis and cloned into pMD18-T vector. The HmVg2 gene was 5460 bp in length, and formed with an open reading frame (ORF) of 5 361 nucleotides (GenBank accession no. KY794939). The putative molecular weight of the primary HmVg2 protein was 203.459 kDa and the predicted isoelectric point (pI) was 8.59. HmVg2 contained a signal peptide, vitellogenin N-terminal (vitellogenin-N) domain, domain of unknown function 1943 (DUF1934) domain and von Willebrand factor type D (VWD) domain. The developmental expression profiling showed that HmVg2 was extremely highly expressed in female insects, but was expressed at lower levels in male insects. In female insects, HmVg2 was mainly expressed in the wing and fat body. The double-stranded RNA-HmVg2/-GFP was injected into H. axyridis, and qRT-PCR results showed that the HmVg2 gene was specifically silenced. The eggs laid during the first five days and the hatching rate of eggs was lower than controls after dsHmVg2 injection. This investigation demonstrated that the HmVg2 gene plays an important role in H. axyridis reproduction and enriches the function of the insect vitellogenin gene.

Tartary buckwheat peptides (TBPs), produced from tartary buckwheat through solid-state fermentation, were used as a dip treatment solution to preserve tilapia fillets. Fillets were dip treated with different concentrations of TBPs (0.5, 1, and 2% [v/v]) and stored at 4°C for 12 days. The effect of TBPs on thiobarbituric acid, total volatile base nitrogen, surface color, texture profile analysis, total viable counts, and changes in sensory properties of tilapia fillets during storage was investigated. Compared with the control group, the groups treated with TBPs displayed reduced rates of quality deterioration in physicochemical, bacteriological, and sensory characteristics. Based on total volatile base nitrogen content, total viable counts, and sensory scores, the shelf life of control tilapia fillets was 4 days and that for TBP-treated fillets was 8 days, twice as long as that of the control group. Thus, TBPs can be used as preservatives to maintain the quality and extend the shelf life of tilapia fillets stored at 4°C.

The electrochemical nitrogen reduction reaction (NRR) under mild conditions is significantly challenging, due to the extremely high stability of dinitrogen (N2) molecules. The NRR pathway also confronts the competitive water reduction reaction that takes places universally in an aqueous solution. Herein, a Fe2O3/Cu catalyst is demonstrated as an efficient NRR electrocatalyst. The electronic interactions elevate the d-state electron center, enabling strong back-bonding for N2 molecules. The altering of d-electron distribution promotes the adsorption of N2, leading to a high catalytic activity. As a result, the Fe2O3/Cu catalyst exhibits an outstanding ammonia production rate of 15.66 μg·h−1·mgcat.−1 at −0.1 V versus reversible hydrogen electrode (RHE), a Faradaic efficiency of 24.4%, and a good electrochemical stability.

Electric conductivity and rheological responses of colloidal electrolytes consisting of lithium bis(trifluoromethanesulfon) imide, polyethylene glycol (PEG) oligomer, and fumed silica have been investigated. Incorporating silica could improve ionic conductivity of the electrolytes at the same lithium/oxygen ratios. The colloidal electrolytes demonstrate a sol to gel transition with increasing silica content while they exhibit shear thickening behaviors during steady flow at intermediate range of strain rate. The presence of lithium salt, on the one hand, could lower the crystallinity of PEG or forbid the crystallization and on the other hand, interferes the chain adsorption on the surface of silica. Furthermore, lithium salt strongly retards the segmental relaxation of PEG in the colloidal electrolytes.

Objective: This study aims to investigate the effects of TRPV4 on acute hypoxic exercise-induced central fatigue, in order to explore the mechanism in central for exercise capacity decline of athletes in the early stage of altitude training. Methods: 120 male Wistar rats were randomly divided into 12 groups: 4 normoxia groups (quiet group, 5-level group, 8-level group, exhausted group), 4 groups at simulated 2500 m altitude (grouping as before), 4 groups at simulated 4500 m altitude (grouping as before), 10 in each group. With incremental load movement, materials were drawn corresponding to the load. Intracellular calcium ion concentration was measured by HE staining, enzyme-linked immunosorbent assay, immunohistochemistry, RT-qPCR, Fluo-4/AM and Fura-2/AM fluorescence staining. Results: (1) Hypoxic 2–5 groups showed obvious venous congestion, with symptoms similar to normoxia-8 group; Hypoxic 2–8 groups showed meningeal loosening edema, infra-meningeal venous congestion, with symptoms similar to normoxia-exhausted group and hypoxic 1-exhaused group. (2) For 5,6-EET, regardless of normoxic or hypoxic environment, significant or very significant differences existed between each exercise load group (normoxic − 5 level 20.58 ± 0.66 pg/mL, normoxic − 8 level 23.15 ± 0.46 pg/mL, normoxic - exhausted 26.66 ± 0.71 pg/mL; hypoxic1-5 level 21.72 ± 0.43 pg/mL, hypoxic1-8 level 24.73 ± 0.69 pg/mL, hypoxic 1-exhausted 28.68 ± 0.48 pg/mL; hypoxic2-5 level 22.75 ± 0.20 pg/mL, hypoxic2-8 level 25.62 ± 0.39 pg/mL, hypoxic 2-exhausted 31.03 ± 0.41 pg/mL) and quiet group in the same environment(normoxic-quiet 18.12 ± 0.65 pg/mL, hypoxic 1-quiet 19.94 ± 0.43 pg/mL, hypoxic 2-quiet 21.72 ± 0.50 pg/mL). The 5,6-EET level was significantly or extremely significantly increased in hypoxic 1 environment and hypoxic 2 environment compared with normoxic environment under the same load. (3) With the increase of exercise load, expression of TRPV4 in the rat prefrontal cortex was significantly increased; hypoxic exercise groups showed significantly higher TRPV4 expression than the normoxic group. (4) Calcium ion concentration results showed that in the three environments, 8 level group (normoxic-8 190.93 ± 6.11 nmol/L, hypoxic1-8 208.92 ± 6.20 nmol/L, hypoxic2-8 219.13 ± 4.57 nmol/L) showed very significant higher concentration compared to quiet state in the same environment (normoxic-quiet 107.11 ± 0.49 nmol/L, hypoxic 1-quiet 128.48 ± 1.51 nmol/L, hypoxic 2-quiet 171.71 ± 0.84 nmol/L), and the exhausted group in the same environment (normoxic-exhausted 172.51 ± 3.30 nmol/L, hypoxic 1-exhausted 164.54 ± 6.01 nmol/L, hypoxic 2-exhausted 154.52 ± 1.80 nmol/L) had significant lower concentration than 8-level group; hypoxic2-8 had significant higher concentration than normoxic-8. Conclusion: Acute hypoxic exercise increases the expression of TRPV4 channel in the prefrontal cortex of the brain. For a lower ambient oxygen concentration, expression of TRPV4 channel is higher, suggesting that TRPV4 channel may be one important mechanism involved in calcium overload in acute hypoxic exercise. Keywords: TRPV4, Prefrontal cortex, Acute hypoxic exercise, Ga2+

The capability of electrocatalytic reduction of carbon dioxide (CO2) using nitrogen (N)-doped carbon strongly depends on the N-doping level and their types. In this work, we developed a strategy to generate mesoporous N-doped carbon frameworks with tunable configurations and contents of N dopants, by using a secondary doping process via the treatment of N,N-dimethylformamide (DMF) solvent. The obtained mesoporous N-doped carbon (denoted as MNC-D) served as an efficient electrocatalyst for electroreduction of CO2 to CO. A high Faradaic efficiency of ∼ 92% and a partial current density for CO of −6.8 mA·cm−2 were achieved at a potential of −0.58 V vs. RHE. Electrochemical analyses further revealed that the active sites within the N-doped carbon catalysts were the pyridinic N and defects generated by the DMF treatment, which enhanced the activation and adsorption CO2 molecules. Our study suggests a new approach to develop efficient carbon-based catalysts for potential scalable CO2RR to fuels and chemicals.

Di-n-butyl phthalate (DBP) is a kind of ubiquitous chemical linked to hormonal disruptions that affects male reproductive system. However, the mechanism of DBP-induced germ cells toxicity remains unclear. Here, we demonstrate that DBP induces reduction of proliferation, increase of apoptosis and DNA damage dependent on the PTEN/AKT pathway. Mechanistically, DBP decreases PTEN promoter methylation and increases its transcriptional activity, leading to increased PTEN expression. Notably, DNMT3b is confirmed as a target of miR-29b and miR-29b-mediated status of PTEN methylation is involved in the effects of DBP treatment. Meanwhile, DBP decreases AKT pathway expression via increasing PTEN expression. In addition, the fact that DBP decreases the sperm number and the percentage of motile and progressive sperm is associated with downregulated AKT pathway and sperm flagellum-related genes. Collectively, these findings indicate that DBP induces aberrant PTEN demethylation, leading to inhibition of the AKT pathway, which contributes to the reproductive toxicity.

The present paper theoretically demonstrates tunable Goos–Hanchen (GH) shift and beam splitting of the polarized light reflected from the cavity containing the double ladder energy level system. Simultaneously opposite GH shifts for left-circularly polarized (LCP) and right-circularly polarized (RCP) beams can be achieved under asymmetric field conditions. By adjusting the intensity (Rabi frequency) of probe or drive field, the GH shifts of LCP and RCP probe beams are manipulated at the same time. We also discuss the effects of probe field frequency detuning on GH shifts and identify the parameters region to obtain a large separate distance (∼320 μ m) between LCP and RCP probe beams.

Alternating hydrostatic pressure (AHP) is the main cause of the marine coating failure of deep-sea tools and equipment. Herein, we synthesized a novel nanostructure, namely, graphene oxide–mesoporous silicon dioxide layer–nanosphere structure loaded with tannic acid (GSLNTA), as a self-healing coating additive. The anti-corrosion and anti-AHP performance and the self-healing capability of GSLNTA coating were evaluated through electrochemical impedance spectroscopy, field emission scanning electron microscopy, Fourier-transform infrared spectroscopy, and alternating current scanning electrochemical microscopy (AC-SECM). Results showed that the nanolayer structure of GSLNTA effectively inhibited corrosion mass transmission under simulated deep-sea AHP. The nanospheres of GSLNTA released inhibitors to form a ferric tannate film on the exposed metal surface under AHP. The nanolayer and nanosphere of GSLNTA self-healing coating exerted a synergistic effect on anti-corrosion and anti-AHP performance and blocked corrosion factor transmission and coating failure in deep-sea applications. AC-SECM revealed the advantages of local impedance complementation of different electrochemical parameters (|Z| and –phase) to monitor the self-healing of coatings with GSLNTA. This work also investigated the self-healing performance of alkyd varnish coating embedded with synthetic GSLNTA in protecting steel surfaces. Self-healing materials have an “active healing” capability to prolong the life of organic coatings after unwanted external damage in deep-sea environments.

Wild apple Malus sieversii (Ledeb.) M. Roem. (Rosales: Rosaceae), the ancestor of cultivated apples, is widely distributed in Central Asia and is recognized as an important germplasm bank. Recently, the invasive pest Agrilus mali Matsumura (Coleoptera: Buprestidae), originally distributed in eastern Asia, has damaged endemic apple forests in the Yili River valley, Xinjiang, China, and has spread rapidly, infesting more than 80% of wild apple trees in this region. We investigated the life-history traits and native natural enemies in the recently invaded range during 2016 and 2017. Agrilus mali has a univoltine life cycle and overwinters as young larvae in galleries in the cambium. Adults emerged from early June to mid-August and their density peaked in mid-July. Several native natural enemies were identified from Agrilus mali larvae, including Atanycolus denigrator (L.) (Hymenoptera: Braconidae), the mite Pyemotes moseri Yu et Liang (Acari: Pyemotidae) and fungal entomopathogens. Combined, these natural enemies were responsible for mortality rates ranging from 20% to 80% during the summer and autumn. The most abundant and important natural enemy was A. denigrator, which was responsible for up to 15% mortality of A. mali. The results of the present study suggest that augmentation and conservation of A. denigrator and P. moseri should be considered with respect to biological control against this devastating pest.

Graphene quantum dots (GQDs) are emerging as environmentally friendly, low-cost, and highly tunable building blocks in solar energy conversion architectures, such as solar (fuel) cells. Specifically, GQDs constitute a promising alternative for organometallic dyes in sensitized oxide systems. Current sensitized solar cells employing atomically precise GQDs are based on physisorbed sensitizers, with typically limited efficiencies. Chemisorption has been pointed out as a solution to boost photoconversion efficiencies, by allowing improved control over sensitizer surface coverage and sensitizer-oxide coupling strength. Here, employing time-resolved THz spectroscopy, we demonstrate that chemisorption of atomically precise C42-GQDs (hexa-peri-hexabenzocoronene derivatives consisting of 42 sp(2) carbon atoms) onto mesoporous metal oxides, enabled by their functionalization with a carboxylate group, enhances electron transfer (ET) rates by almost 2 orders of magnitude when compared with physisorbed sensitizers. Density functional theory (DFT) calculations, absorption spectroscopy and valence band X-ray photoelectron spectroscopy reveal that the enhanced ET rates can be traced to stronger donor-acceptor coupling strength enabled by chemisorption.

Fast recombination of photogenerated charge carriers in bulk remains the major obstacle for photocatalysis nowadays. Developing ferroelectrics directly as photoactive semiconducting catalysts may be promising in view of the strong ferroelectric polarization that induces the anisotropic charge separation. Here, we report a ferroelectric layered perovskite SrBi4Ti4O15 as a robust photocatalyst for efficient CO2 reduction. In the absence of co-catalysts and sacrificial agents, the annealed SrBi4Ti4O15 nanosheets with the strongest ferroelectricity cast a prominent photocatalytic CO2 reduction activity for CH4 evolution with a rate of 19.8 μmol h−1 g−1 in the gas-solid reaction system, achieving an apparent quantum yield (AQY) of 1.33% at 365 nm, outperforming most of the reported photocatalysts. The ferroelectric hysteresis loop, piezoresponse force microscopy (PFM) and ns-level time-resolved fluorescence spectra uncover that the outstanding CO2 photoreduction activity of SrBi4Ti4O15 mainly stems from the strong ferroelectric spontaneous polarization along [100] direction, which allows efficient bulk charge separation along opposite direction. DFT calculations also disclose that both electrons and holes show the smallest effective masses along a axis, verifying the high mobility of charge carriers facilitated by ferroelectric polarization. This study suggests that the traditionally semiconducting ferroelectric materials that have long been studied as ferro/piezoelectric ceramics now may be powerfully applied in the photocatalytic field to deal with the growing energy crisis.

We investigated observational data from 20 geomagnetic observatories at longitudes of 130°E to 150°E between 2009 and 2012 in order to detect possible anomalous changes in the geomagnetic solar quiet daily (Sq) variation related to the 2011 off the Pacific coast of Tohoku earthquake (Mw 9.0) that occurred on March 11, 2011, in Japan. We selected the five quietest days in every month and analyzed three-component magnetic data with 1-min resolution using the natural orthogonal component method to identify Sq variations from observations, and performed spherical harmonic analysis (SHA) to separate the internal and the external equivalent Sq current systems of Je and Ji. We found that Je and Ji were distorted near the epicenter on two geomagnetic quiet days, January 23 and 27, 2011. This was about 2 months before the earthquake. We then employed backward computation on the external and internal parts of the SHA model geomagnetic fields, Be and Bi, to determine the possible anomalous magnetic field variations at each station. The results showed significant differences in daily variation for all components on January 23 and 27, 2011. On the other days, we could not recognize any apparent anomalous behaviors apart from known secular, seasonal, and solar activity dependence. A possible connection between this anomaly and the very strong Tohoku earthquake, which followed only 1.5 months after the geomagnetic anomaly, is of extreme interest for research on earthquake precursors.

The Quaternary Chinese loess is one of the most continuous terrestrial sediments, and preserves excellent palaeoclimate records at different timescales. The conventional land-ocean palaeoclimatic comparison has been established by correlation between magnetic susceptibility of the Chinese loess and deep-sea δ 18 O records during the 1980s. However, such a correlation results in long-standing debates on the lock-in depth of the palaeomagnetic polarity boundaries in Chinese loess. In this study, the lock-in depth of palaeomagnetic signals for loess

The manipulation of magnetic states in nanoparticle supercrystals promises new pathways to design nanocrystalline magnetic materials and devices. Trench-patterned silicon substrates were used as templates to guide the self-assembly of iron oxide nanoparticles. Grazing incidence small angle X-ray scattering shows that the nanoparticles form a long-range ordered structure along the trench direction while in the direction perpendicular to the trenches, no coherent structure is observable. Electron holography provides evidence of an ordered magnetic state of nanoparticle moments in the remanent state after the application of a saturation magnetic field parallel to the trenches. However, a disordered magnetic state was observed in a perpendicular geometry. Hysteresis loops indicate that the nanoparticle moments form a superferromagnetic state for the geometry parallel to the trenches. Memory effect investigations reveal that the disordered magnetic state corresponds to a collective superspin glass state in the perpendicular geometry, while the superferromagnetic state in the parallel geometry suppresses the superspin glass state.

The rational synthesis of earth-abundant materials with excellent electrocatalytic performances plays a critical role in electrochemical CO2 reduction (ECR) to obtain value-added chemical products or fuels. Here we demonstrate a defective graphene (DG) as such an electrocatalyst candidate via a nitrogen removal method. The graphene with a large amount of topological defects offered abundant catalytically active sites, high electronic conductivity and strong adsorption of CO2. Attributed to these features, the DG exhibited significantly higher electrocatalytic CO2 reduction performances with an excellent faradaic efficiency of ∼84% at −0.6 V vs. reversible hydrogen electrode and a larger current density, compared to pristine graphene, nitrogen-doped graphene and edge-rich graphene. This work suggests a promising method for further designing efficient metal-free electrocatalysts for CO2 reduction.

Acoustic-gravity waves are generally considered to be one of the major factors that drive changes of the total electron content in the ionosphere. However, causal mechanisms of couplings between sources in the lithosphere and responses in the atmosphere and the ionosphere are not fully understood, yet. A barometer in the cave of the SBCB station records an unusual phenomenon of larger amplitudes in air pressure changes inside than those at the Xinwu station (outside). Accordingly, the comparison between the recorded data at the SBCB and Xinwu station can drive investigations of potential sources of the unusual phenomenon. Analytical results of phase angle differences reveal that the air pressure outside the cave at the Xinwu station often leads air pressure changes inside at the SBCB station at relatively low frequency bands. In contrast, the larger pressure changes at frequencies > ~ 5 × 10–4 Hz inside the cave at the SBCB station lead smaller changes outside at the Xinwu station. To expose causal mechanisms of the unusual phenomenon, continuous seismic waveforms are further conducted for examination. When the horizontal and vertical ground velocities of ground vibrations yield a difference in the phase angle close to 90°, coherence values between the air pressure changes and ground vibrations become large. This suggests that the pressure-shear vertical ground vibrations can drive air pressure changes. Meanwhile, the results shed light on investigating the existence of acoustic waves near the Earth’s surface using a partially confined space underground due to that the assumptions of the waves can propagate upward into the atmosphere driving changes in the ionosphere.

Many studies have shown that b values tend to decrease prior to large earthquakes. To evaluate the forecast information in b value variations, we conduct a systematic assessment in Yunnan Province, China, where the seismicity is intense and moderate–large earthquakes occur frequently. The catalog in the past two decades is divided into four time periods (January 2000–December 2004, January 2005–December 2009, January 2010–December 2014, and January 2015–December 2019). The spatial b values are calculated for each 5-year span and then are used to forecast moderate-large earthquakes (M ≥ 5.0) in the subsequent period. As the fault systems in Yunnan Province are complex, to avoid possible biases in b value computation caused by different faulting regimes when using the grid search, the hierarchical space–time point-process models (HIST-PPM) proposed by Ogata are utilized to estimate spatial b values in this study. The forecast performance is tested by Molchan error diagram (MED) and the efficiency is quantified by probability gain (PG) and probability difference (PD). It is found that moderate–large earthquakes are more likely to occur in low b regions. The MED analysis shows that there is considerable precursory information in spatial b values and the forecast efficiency increases with magnitude in the Yunnan Province. These results suggest that the b value might be useful in middle- and long-term earthquake forecasts in the study area.

Early studies have shown evidence of the seismo-ionospheric perturbations prior to large earthquakes. Due to dynamic complexity in the ionosphere, the identification of precursory ionospheric changes is quite challenging. In this study, we analyze the total electron content (TEC) in the global ionosphere map and investigate the TEC changes prior to M ≥ 6.0 earthquakes in the Chinese Mainland during 1998–2013 to identify possible seismo-ionospheric precursors. Singular spectrum analysis is applied to extract the trend and periodic variations including diurnal and semi-diurnal components, which are dominated by solar activities. The residual ΔTEC which is mainly composed of errors and possible perturbations induced by earthquakes and geomagnetic activities is further investigated, and the root-mean-square error is employed to detect anomalous changes. The F10.7 and Dst index is also used as criterion to rule out the anomalies when intense solar or geomagnetic activities occur. Our results are consistent with those of previous studies. It is confirmed that the negative anomalies are dominant 1–5 days before the earthquakes at the fixed point (35°N, 90°E) during 0600–1000 LT. The anomalies are more obvious near the epicenter area. The singular spectrum analysis method help to establish a more reliable variation background of TEC and thus may improve the identification of precursory ionospheric changes.

The paper presents a study of the torque production in a novel vernier-type axial-flux permanent magnet (PM) machine topology named MAGNUS. Two computational methods are employed, one based on the 3D FEA Maxwell stress calculations on individual stator and rotor components and one based on the analytical derivation of the air-gap flux density harmonics. Examples are provided for a design with a 40-pole spoke-type PM rotor and two stators, one active including a 3-phase winding with 6 concentrated coils wound around main teeth in a single layer arrangement and a second stator that has neither coils nor main slots and is profiled towards the airgap in the same way as the active stator. It is shown that auxiliary small teeth included in the stator main teeth yield a significant increase in the output torque and that the profiled stator has a lower contribution than the active stator to the total torque. A brief report on the ongoing development of a prototype motor is included.

We have theoretically investigated the use of a simple combined amplitude structure to produce a sub-diffracted Bessel beam via diffraction interference. This powerful structure is composed of a spiral slit and radial grating. When a vortex beam illuminates this combined amplitude structure, a subwavelength Bessel beam with a size of 0.39λ and a long working distance of approximately 100 µm is numerically realized. By tailoring the parameters of the spiral slit, we can obtain a longer sub-diffracted Bessel beam. Moreover, the observed Bessel beam has low-energy side-lobes. The peculiar features of our theoretically generated Bessel beam have numerous potential applications, such as in nanoparticles manipulation, super-resolution imaging, and lithography.

Ultramicroscopy 229, 113340 (2021). doi:10.1016/j.ultramic.2021.113340, Published by Elsevier Science, Amsterdam

ACS photonics 8(12), 3394-3405 (2021). doi:10.1021/acsphotonics.1c00951, Published by American Chemical Society, Washington, DC

In order to find out whether the geomagnetic storms and large-mega earthquakes are correlated or not, statistical studies based on Superposed Epoch Analysis (SEA), significance analysis, and Z test have been applied to the Dst index data and M &ge, 7.0 global earthquakes during 1957&ndash, 2020. The results indicate that before M &ge, 7.0 global earthquakes, there are clearly higher probabilities of geomagnetic storms than after them. Geomagnetic storms are more likely to be related with shallow earthquakes rather than deep ones. Further statistical investigations of the results based on cumulative storm hours show consistency with those based on storm days, suggesting that the high probability of geomagnetic storms prior to large-mega earthquakes is significant and robust. Some possible mechanisms such as a reverse piezoelectric effect and/or electroosmotic flow are discussed to explain the statistical correlation. The result might open new perspectives in the complex process of earthquakes and the Lithosphere-Atmosphere-Ionosphere (LAI) coupling.

This study put forward a real-time motion control scheme for space manipulator to avoid collisions with complex space environment during performing tracking task. Considering the situation where obstacles locate on the desired trajectory, the proposed strategy is based on the idea of task priority transition to realize the main mission of obstacle avoidance and the minor mission of trajectory tracking. An on-line detecting method is employed to obtain the closest position on the space manipulator system to the obstacles. Depending on the variation of the minimal distance to the obstacles, the priority orders of obstacle avoidance and end-effector tracking are transformed continuously to deal with the conflict between tasks. The effectiveness of the proposed strategy is verified via two simulation cases on a seven-degrees-of-freedom kinematical redundant space manipulator system. The simulation results demonstrate the proposed method ensures the space manipulator avoid collisions with multiple obstacles in the workspace, while achieving smooth and continuous movement.

We present a simple method to enable flexible tuning of non-diffracting beams in a two-dimensional nonlinear photonic crystal, based on the interference of two or more non-collinear second-harmonic beams. By manipulating the wavelengths of the beams and the angle of incidence of the fundamental wave, the arbitrary period and propagation length, as well as the wavelength of the generated nonlinear non-diffracting array beams, can be tuned flexibly. These light beams can trap and manipulate multiple particles, create new forms of optical imaging systems, and act within nonlinear devices to bring novel functionalities to integrated optics.

The underwater target detection method with traditional line spectrum is insufficient for low SNR signals. The theory of stochastic resonance (SR) provides a feasible method to improve the detection ability for Low SNR signals due to SR have multiple steady states with different excitations. In order to improve the detection ability of the line spectrum feature of the target, the combined detection algorithm is tested in this paper, which combines adaptive line enhancement based on LMS algorithm with the parameter adjustment method of stochastic resonance, analyzing the characteristics of different combined methods and their processing performance. Based on the above analysis, a kind of joint line spectrum detection scheme (JLSDS) of underwater targets is proposed, which is efficient to extract the corresponding line spectrum feature information for low SNR signals.

Single unit recording has an important application in neuroscience, especially in the vestibular system such as visual stabilization, posture maintenance, spatial orientation and cognition. However, single unit recording conducted in living animals is a demanding technique and non-ideal mechanical stability between the recording location of nerve tissues and the tip of microelectrode always results in failure to obtain successful recordings in the vestibular system. In order to improve the mechanical stability during single unit recording, we constructed a novel head fixation method based on skull cap. This article describes in detail how to construct this novel head fixation. Following the step-by-step procedure mentioned in this article will provide a high-quality mechanical stability for single unit recording in the vestibular system, allowing us to successfully record the nonlinear neural dynamic response over a big magnitude motion stimulation. This improvement of head fixation contributes to the in-depth understanding of the vestibular system., Graphical abstract Image, graphical abstract