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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]

Persistent free radicals (PFRs) are emerging substances with diverse impacts in biochar applications, necessitating accurate prediction of their content and types prior to their optimal use and minimal adverse effects. This prediction task is challenging due to the nonlinearity and intricate variable relationships of biochar. Herein, we employed data-driven techniques to compile a dataset from peer-reviewed publications, aiming to systematically predict the PFRs by developing supervised machine learning models. Notably, extreme gradient boosting (XGBoost) model exhibited the best predictive performance for both regression and classification tasks in predicting the PFRs, achieving a test R2 value of 0.95 for PFR content prediction, along with an Area Under the Receiver Operating Curve (AUROC) of 0.92 for PFR type prediction, respectively. Based on XGBoost model, a graphical user interface (GUI) was developed to access PFRs predictions. Analysis of feature importance revealed that the biochar properties, such as metal/non-metal doping, pyrolysis temperature, carbon content, and specific surface area were identified as the four most significant factors influencing PFRs contents. Regarding the types of PFRs in biochar, specific surface area, pyrolysis temperature, carbon content, and feedstock were top-ranked influencing factors. These findings provide valuable guidance for accurately predicting both the contents and types of PFRs in biochar, and also hold significant potential for highly efficient utilization of biochar across various applications. Highlights: • Recognizing dual nature of PFRs, a machine-learning framework predicts them in biochar. • XGBoost excels, achieving an R2 (0.95) for PFR content and an AUROC (0.92) for PFR type. • Important factors of PFR: doping, pyrolysis temp, carbon, and surface area. • GUI enhances accessibility, enabling PFR predictions before biochar preparation. [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]

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]

• 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]

[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]