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In this paper, a wideband polarization reconfigurable omnidirectional antenna (PROA) based on a single-substrate active metasurface is proposed. By controlling the states of the PIN diodes, the antenna can selectively radiate an omnidirectional linearly polarized wave and an omnidirectional circularly polarized wave. The reflection coefficient, axial ratio (AR), radiation pattern, and gain of the proposed antenna have been analyzed from the perspective of simulation and measurement. The measured results show that the PROA has a wide overlapped bandwidth from 2.87 to 3.67 GHz (relative bandwidth 24.46%). To the authors' best knowledge, this is the first reported wideband PROA based on a single-substrate reconfigurable polarization converter. This study not only offers a novel approach to design PROAs, but also greatly reduces the design complexity of the feed source compared with the traditional design method of PROAs. [ABSTRACT FROM AUTHOR]

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Dynamic stall control is of great significance for enhancement of the airfoil aerodynamic characteristics. In the present study, the co-flow jet(CFJ) flow control method is numerically investigated to control the dynamic stall caused by the pitching airfoil. Two aspects regarding the CFJ implementation are studied: one is the effect of the CFJ channel on the dynamic stall characteristics when the jet is switched off and another is the effect of jet momentum coefficient on the dynamic stall control effectiveness when the CFJ is activated. Results show that the jet channel will significantly affect the aerodynamic characteristics in the attached flow regime during pitching up, but not have obvious influence on the aerodynamic characteristics in the massively separating regime during the pitching down process. When the jet is activated, the dynamic stall characteristics is significantly improved. The areas of the hysteresis lines are significantly reduced, and the lift is significantly increased, and drag is reduced. The peaks of the drag and moment are significantly reduced. Moreover, the negative damping existing in the moment coefficient hysteresis line of the baseline airfoil is removed, leading to a completely positive damping during the entire pitching cycle.

Organophosphate esters (OPEs) are widely used as flame retardants and plasticizers in industry and daily life, but the partition of OPEs to particles is still unclear because of the wide range of their physicochemical properties. In this study, six target OPEs with different vapor pressures (log P L) were measured from 30 total suspended particulate (TSP) samples collected from an urban area of Zhengzhou from June to November in 2018. The total concentration of OPEs ranged from 0.30 to 3.46 ng/m3, with average concentration of 1.04 ng/m3. Tris (chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCPP), and tributyl phosphate (TnBP) were most abundant in TSP, accounting for approximately 86.0% to the total OPEs. The temporal variations showed a specific trend that OPE concentrations in TSP were much higher in autumn than those of summer. Significant positive correlations were observed between TSP concentration in air and the total concentration of OPEs in TSP, with r up to 0.596. Particle concentrations caused major changes on OPE concentrations in TSP with octanol-air partition coefficient (log K OA) between 7.7 and 10 but had no significant influence on the OPEs with log K OA higher than 12. Temperature had significant influence on the total and individual OPEs with high vapor pressures (log P L > −4.0), indicating that log K OA and log P L had significant influence on the OPE concentrations in TSP and may be one of the key factors on their temporal variations. Temperature had significant influence on OPE concentrations in TSP due to the strong temperature dependency of log K OA and log P L. No significant relationships were found between the wind speed and OPE concentrations in TSP, suggesting that OPEs detected in TSP might be emitted from the local sources. The hazards quotient (HQ) values were 6–8 orders of magnitude lower than 1, indicating that there was a low risk to local residents from the exposure to OPEs in TSP. This study preliminarily illuminates the potential affecting factors on the temporal variations of OPEs in TSP. It would be helpful for investigating the gas-particle partitioning behaviors and human health risks of OPEs in air. • Particle concentration in air might be one of the key factors on the temporal variations of OPEs in TSP. • TSP concentration has significant influence on the concentrations of OPEs with log K OA between 7.7 and 10. • No significant correlations were found between TSP concentration and OPEs with log K OA higher than 12. • There was still low risk to local residents from the exposure to OPEs in TSP at the current concentration levels. [ABSTRACT FROM AUTHOR]

Organophosphate esters (OPEs) are widely used as flame retardants and plasticizers in many products and materials. Because of the potential biologic toxicity on human beings, OPEs are regarded as a class of emerging pollutants. Dissolved organic matters (DOM) have significant effects on the bioavailability and toxicity of the pollutants in the environment. Negligible-depletion solid-phase microextraction (nd-SPME) is an efficient way for measuring the freely dissolved pollutants but suffers from long equilibrium time. Metal-organic frameworks (MOFs) are a class of porous crystalline materials with unique properties such as high pore volume, regular porosity, and tunable pore size, being widely used for the extraction of various organic compounds. Here we developed a novel method for quick determination the sorption coefficients of OPEs to DOM in aquatic phase using Fe 3 O 4 @MIL-100 (Fe) core-shell magnetic microspheres. The mesoporous structures of the as-synthesized microspheres hindered the extraction of OPEs which associated with humic acid due to the volume exclusion effect. However, the freely dissolved OPEs can access into the mesoporous and then were extracted by MIL-100 (Fe). Due to the small pore size (4.81 nm), large surface area (141 m 2  g −1 ), high pore volume (0.17 g 3  g −1 ), and ultra-thin MOFs layers, Fe 3 O 4 @MIL-100 (Fe) core-shell magnetic microspheres have large contact area for the analytes in aqueous phase and therefore the diffusion distance was largely shortened. Besides, the microspheres can be collected conveniently after the extraction process by applying a magnetic field. Compared to the nd-SPME method with 35 h equilibration time ( t 90% ), the proposed method for these studied OPEs only need 24 min to achieve equilibration. The sorption coefficients (log K DOC ) of the OPEs to humic acid were ranged from 3.84–5.28, which were highly consistent with the results by using polyacrylate-coated fiber and polydimethylsiloxane-coated fiber with nd-SPME. [ABSTRACT FROM AUTHOR]

Subway fires are a major threat to the safe and smooth operation of subway stations. In this paper, an island-type subway station was taken as an example to conduct a series of numerical simulations using Fire Dynamics Simulator (FDS). The temperature, visibility, and CO concentration in the subway station were analysed under different thicknesses and jet velocities of the air curtains. The smoke-prevention performance of the air curtains in the subway station was investigated. As the thickness and jet velocity increase, the flame tilts significantly, which greatly hinders the spread of smoke toward the stairs. The smoke temperature and CO concentration on the left side of the air curtains gradually decrease, while the visibility increases significantly. For a 3 MW fire scenario, to satisfy the evaluation criteria, the results show that the thickness of the air curtains needs to be at least 0.3 m, and the jet velocity needs to be at least 2 m/s. The sealing effectiveness (Esealing) tends to increase and then remains constant with increasing momentum, and the maximum is obtained when the momentum of the air curtains (Ia) is 12.5 kg·m/s2. Meanwhile, it is found that an energy-saving efficiency of 85.2% can be achieved by replacing positive pressure ventilation with air curtains. The results of this work can provide a significant reference for the design of smoke protection in subway stations. [ABSTRACT FROM AUTHOR]

Organophosphate esters (OPEs) are widely used as flame retardants and plasticizers in industrial and commercial products. It is generally believed that OPEs in street dust mainly originate from road traffic and anthropogenic activities. The influence of atmospheric deposition is still unknown. In this study, leaves were employed as a novel passive air sampler to collect particle matters (PM) in 12 cities in the central province of Henan, China. Similar compositional profiles of OPEs were found in street dust and PM samples. The concentrations of individual OPEs in PM were 1–4 times higher than in street dust. Chlorinated OPEs concentration in PM shows a moderate correlation (r 2 = 0.538, p < 0.01) with that in street dust. The concentration of alkyl OPEs in PM has a high correlation (r 2 = 0.843, p < 0.01) with that in street dust. No significant correlation (r 2 = 0.133, p = 0.132) was found on the aryl OPEs concentrations between street dust and PM. Spearman correlation reveals that the emission sources of tricresyl phosphate (TCrP) and triethyl phosphate (TEP) may be different from other OPEs in dust and PM samples. Principle component analysis (PCA) provides an appropriate explanation that tris (2-chloroethyl) phosphate (TCEP), triphenyl phosphate (TPhP), tris (chloropropyl) phosphate (TCPP), tributyl phosphate (TnBP), and TEP in street dust and PM may be emitted from the same sources, suggesting that PM has a significant influence on the occurrence of OPEs in street dust. The estimated dry deposition fluxes of particle-bound OPEs show a significant correlation (R 2 = 0.969, p < 0.01) with OPEs concentrations in street dust, revealing that the input of atmospheric deposition could be a major source of OPEs in street dust. [Display omitted] • Spatial phytosampling was used to study the potential source of OPEs in street dust. • Leaves were used as passive sampler for comparative applications. • Most OPEs in PM had positive correlation with those in the street dust. • The input of atmospheric deposition is a major source of OPEs in street dust. [ABSTRACT FROM AUTHOR]

In this study, the gas-phase retention volume behavior of four highly volatile organophosphate esters (OPEs) on polyurethane foam (PUF) was studied using a frontal chromatogram. The breakthrough volumes (V B) of trimethyl phosphate (TMP), triethyl phosphate (TEP), tripropyl phosphate (TPrP), and tri-n-butyl phosphate (TnBP) were 0.33, 0.59, 10.5, and 32.4 m3, respectively. A significant negative correlation was found between the logarithm value of V B and the subcooled liquid vapor pressure (P L) with an r 2 of 0.905, indicating that the vapor penetration depends on both the volatility and total air volume. The enthalpy of desorption and vaporization (Δ H S −Δ H V) showed a significant difference between the tested OPEs and polycyclic aromatic hydrocarbons (PAHs), revealing that the strength of the sorption interaction of the tested OPEs vapor on PUF should be different from that of PAHs. The PUF-air partition coefficients (K PUF-air) of the tested OPEs ranged from 4.3 to 8.1, which were lower than those of three-to four-ring PAHs (7.02–10.2) and organochlorines (8.01–9.72), revealing that the partition of highly volatile OPEs on PUF is lower than that of low-volatile compounds. The PUF/XAD cartridge improved the absorption efficiency of the tested OPEs; however, its sorptive capacity was still limited. [Display omitted] • The breakthrough volumes of four high volatile OPEs on PUF column were determined by frontal chromatograms. • The breakthrough volumes of the tested OPEs are much lower than three to four ring PAHs. • There are significant differences in the sorption interaction on PUF between the tested OPEs and low volatile compounds. • XAD resins can improve the sorptive capacity for high volatile OPEs. [ABSTRACT FROM AUTHOR]

For cobalt-rich crusts in a contract area, the regular-shaped cells for relinquishment are obviously different from the natural ore distribution, and this brings challenges in evaluating the resources within them. Based on survey data in the China Ocean Mineral Resources Research and Development Association (COMRA) contract area, this study analyzed factors that could influence the relinquishment of cobalt-rich crusts. According to the guidelines of the International Seabed Authority, each original block of the COMRA contract area was subdivided into 16 cells. The contract areas were then divided into orebodies, unclear areas, and non-resource areas based on the distribution of the orebodies. Then, these attributions were assigned to the cells and the resources inside each cell were evaluated and identified, according to resource quantity, as resource cells, unclear cells, and non-resource cells. Finally, relinquishment was assessed by a step-by-step method in the following priority order: non-resource cells, unclear cells, and resource cells. This method was applied to the Caiqi Guyot (a guyot in the COMRA contract area) as a case study. The results show that the proposed method is suitable for the relinquishment of cobalt-rich crusts in the COMRA contract area and can also be applied to other contract areas worldwide. [ABSTRACT FROM AUTHOR]

Hepatitis B is a leading cause of death worldwide. Here, we performed a large, population-based, cross-sectional study in Chongqing, China from 2011 to 2016 to assess the prevalence of HBsAg among couples of reproductive age, to predict subsequent trends, and to provide evidence for the WHO goal of "the elimination of viral hepatitis as a public health threat by 2030". A total of 386,286 couples aged 20 to 49 years were enrolled in the study. Approximately 14.35% of couples were HBsAg positive, including 95.00% with discordant HBsAg positivity. HBsAg prevalence was higher in men than in women. Among different occupations, the two categories of "houseworker" (female 6.73%, male 9.99%) and "unemployed" (female 6.64%, male 9.94%) showed the highest HBsAg positivity. In different regions, the lowest prevalence appeared in southeastern Chongqing (female 4.87%, male 7.71%). In 2030, the HBsAg positivity rate is expected to be 2.79%, 7.27% and 5.13% in females, males, and the whole population, respectively. According to the trends, this rate would drop to less than 2% in 2034, 2078 and 2051. In conclusion, the HBsAg prevalence in Chongqing is still relatively high compared with that in other parts of western China, especially among reproductive-age men. HBsAg-positive couples should be taken as an important unit of care. Vaccination is necessary before pregnancy if no antibody is found. More attention should be given to people without stable jobs. HBsAg-positive rate will decrease perceptibly by 2030 and will reach the level of low in epidemic areas by 2050. [ABSTRACT FROM AUTHOR]

• Mutation of 244-site (G → E) enhances the virulence of JEV SA14-14-2 in mice. • JEV E244 (G → E) exhibits different virulence in the context of JE vaccine. • Minor mutations in vaccine cannot be detected by Sanger sequencing. • Minor variants in vaccine do not develop to the dominant population. Japanese encephalitis (JE) poses a serious threat to the world's public health yet without a cure, the only way to prevent Japanese encephalitis virus (JEV) infection is vaccination. Live attenuated vaccine (SA14-14-2 strain) is the most widely used JE vaccine, and clinical data have confirmed its safety and effectiveness. Eight sitesassociated with virulence in the Envelope (E) protein are often the focus of quality control of JE vaccine. However, sequences retrieved from NCBI, as well as our previous results showed that the wild strain SA14 may harbor two different amino acids at amino acid residue 244 of the E glycoprotein (E244), and it may be related to virulence. In this study, we introduced a single mutation at nt1708 (G → A) in the full-length cDNA clone of SA14-14-2, replacing a Gly with Glu at amino acid residue 244 of the E glycoprotein, and successfully constructed the mutant virus (JEV E244). JEV E244 exhibited a similar plaque morphology and growth characteristics to JEV SA14-14-2 in cell culture. However, it had lethal neurovirulence in mice and could enter the brain following intraperitoneal inoculation. Moreover, the virulence of JEV E244 in the context of vaccine in mice is significantly different from that of the JEV E244 alone. These results suggested that E244 site should be included in the assessment of the genetic stability of the attenuated JE vaccine. The detection of minor mutations in vaccine population and influence on the safety of vaccine is discussed. [ABSTRACT FROM AUTHOR]

Purpose For the climbing rod object with large diameter variation and the need of obstacle crossing, this paper aims to propose a new embracing-type climbing robot named as EVOC-I robot.Design/methodology/approach The design philosophy and structural scheme are introduced. The kinematic analysis of embracing and telescoping mechanisms is carried out to provide the theoretical foundation for the effective climbing of the robot. Based on the prototype robot, three preliminary experiments are carried out to verify the effectiveness of the designed robot.Findings The theoretical and experimental analyses have verified the reasonability and effectiveness of the proposed robot design.Research limitations/implications As the preliminary study, the prototype still need a lot of improvement. The experimental verification is also limited. Future work will focus on improving the design and increasing the theoretical analysis, especially increasing experimental study and designing the next generation of the rod climbing robot.Practical implications The designed climbing robot can be used for climbing the rod with variation diameter and flange obstacle, especially the lightening rod in the transformer substation.Originality/value The paper designs a new climbing robot that integrates the ability of large variation diameter adaptation and obstacle crossing. [ABSTRACT FROM AUTHOR]

This paper presents an experimental investigation of the fatigue properties of limestone subjected to triaxial compression with axial cyclic loading. Tests were conducted on intact limestone samples with a loading frequency of 0.5 Hz and a confining pressure of 10 MPa. The test results show the following five points. (1) Under triaxial conditions, the axial and circumferential deformations at the failure point induced by cyclic loading are slightly larger than the corresponding deformations at the peak stress achieved by conventional compression tests. (2) The first level cyclic loading process has a strong influence on rock deformation in the primary phase during subsequent level cyclic loading. A smaller difference in stress amplitude between the two loading stress levels leads to less deformation during the latter. (3) Circumferential and volumetric changes are more sensitive to fatigue failure in terms of deformation and strain rate than axial changes. (4) The three phases of dissipated energy evolution are consistent with a sample’s deformation such that the energy dissipation characteristics reflect the fatigue damage evolution process. (5) A new damage formula is proposed that can concisely describe a rock’s zero-cycle damage and damage evolution. [ABSTRACT FROM AUTHOR]

[Display omitted] • MATF and MRP enriched substantial heavy metals and PAHs from the environment. • MATF and MRP from actual artificial turf had significantly higher cytotoxicity. • EPFRs and ROS had limited contributions to the cytotoxicity of aged MATF and MRP. • Heavy metals and PAHs played important roles in the toxicity of MATF and MRP. Numerous micro-sized artificial turf fragments (MATF) and rubber particles (MRP) are generated and accumulated during the use of the artificial playing field. However, attention has rarely been paid to the potential toxic effects of MATF and MRP on sportsmen. In this study, the active components and chemical composition of aged MATF and MRP derived from laboratory photoaging and actual field sampling were detected, and their effects on cytotoxicity were examined correspondingly. Laboratory photoaging significantly increased environmental persistent free radicals (EPFRs), reactive oxygen species (ROS) abundances and oxidative potential (OP) levels on MATF and MRP, but they have limited cytotoxicity. Unfortunately, in the actual field, aged MATF and MRP with higher heavy metals and polycyclic aromatic hydrocarbons (PAHs) contents exhibited markedly higher cytotoxicity with the survival rate of cells of 78 % and 26 % (p < 0.05), although they had lower EPFRs and ROS yields. Correlation analysis revealed that the cell viability was closely linked to heavy metals of MATF (p < 0.05), and to organic hydroperoxide (OHP), PAHs and heavy metals of MRP (p < 0.05). By systematically considering the above results, heavy metals and PAHs enriched on MATF and MRP from the surrounding environment played the important role in the cytotoxicity, which was different from conventional perspectives. Our findings demonstrate that MATF and MRP associated with an artificial turf field contain potent mixtures of pollutants and can, therefore, be relevant yet underestimated factors contributing to the health risks. [ABSTRACT FROM AUTHOR]

TREE submodel affiliated with TREEDYN was used to simulate biomass dynamics of Masson pine ( Pinus massoniana) forest under different managements (including thinning, clear cutting, combining thinning with clear cutting). The purpose was to represent biomass dynamics involved in its development, which can provide scientific arguments for management of Masson pine forest. The results showed the scenario that 10% or 20% of biomass of the previous year was thinned every five years from 15 to 40 years made total biomass of pine forest increase slowly and it took more time to reach a mature community; If clear cutting and thinning were combined, the case C (clear cutting at 20 years of forest age, thinning 50% of remaining biomass at 30 years of forest age, and thinning 50% of remaining biomass again at 40 years of forest age) was the best scenario which can accelerate speed of development of Masson pine forest and gained better economic values. [ABSTRACT FROM AUTHOR]

Background: Spinibarbus hollandi is an economically important fish species in southern China. This fish is known to have nutritional and medicinal properties; however, its farming is limited by its slow growth rate. In the present study, we observed that a compensatory growth phenomenon could be induced by adequate refeeding following 7 days of fasting in S. hollandi. To understand the starvation response and compensatory growth mechanisms in this fish, the muscle transcriptomes of S. hollandi under control, fasting, and refeeding conditions were profiled using next-generation sequencing (NGS) techniques. Results: More than 4.45 × 108 quality-filtered 150-base-pair Illumina reads were obtained from all nine muscle samples. De novo assemblies yielded a total of 156,735 unigenes, among which 142,918 (91.18%) could be annotated in at least one available database. After 7 days of fasting, 2422 differentially expressed genes were detected, including 1510 up-regulated genes and 912 down-regulated genes. Genes involved in fat, protein, and carbohydrate metabolism were significantly up-regulated, and genes associated with the cell cycle, DNA replication, and immune and cellular structures were inhibited during fasting. After refeeding, 84 up-regulated genes and 16 down-regulated genes were identified. Many genes encoding the components of myofibers were significantly up-regulated. Histological analysis of muscle verified the important role of muscle hypertrophy in compensatory growth. Conclusion: In the present work, we reported the transcriptome profiles of S. hollandi muscle under different conditions. During fasting, the genes involved in the mobilization of stored energy were up-regulated, while the genes associated with growth were down-regulated. After refeeding, muscle hypertrophy contributed to the recovery of growth. The results of this study may help to elucidate the mechanisms underlying the starvation response and compensatory growth. [ABSTRACT FROM AUTHOR]