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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]

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 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]

[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]

In the course of isolating the attenuated Japanese encephalitis vaccine SA14-14-2, two attenuated strains SA14-9-7 and SA14-5-3 were also obtained that elicited low antibody responses in humans (<10% and 62%, respectively) and exerted much weaker immune protection in animal challenge experiments. However, the reason for these differences remains unknown. In order to understand why SA14-14-2 is superior to SA14-9-7 and SA14-5-3, we employed a reverse genetics method to identify the key mutations in the virus genome that determine the immunogenicity of live attenuated Japanese encephalitis viruses. We first sequenced the full genomic sequences of SA14-9-7 and SA14-5-3 and found mutations that changed four amino-acid base pairs when compared to the envelope gene of SA14-14-2. We mutated the genome of SA14-14-2 to generate these mutations both singly (E-177, E-264, E-279 and E-315) and in combination (E-177/264, E-279/315 and E-177/264/279/315) and tested these mutants along with parental strains SA14-14-2, SA14-9-7 and SA14-5-3 for their immunogenicity in vivo . When mice were immunized with SA14-9-7 and SA14-5-3, lower levels of neutralizing antibodies were generated compared with the immune response to SA14-14-2. Furthermore, SA14-5-3 was more immunogenic than SA14-9-7, which replicated the results previously seen in humans. Point mutations E-177, E-264, E-279 and E-315 diminished the immunogenicity of SA14-14-2 with E-264 and E-315, contributing the most to this phenotype. The mutant rJEV (E-177/E-264/E-279/E-315) containing all four point mutations exhibited the lowest immunogenicity with a seroconversion rate of 0 at an inoculation dose of 10 3  PFU (plaque-forming unit). We have identified the key amino acids in the envelope protein that account for the superior immunogenicity of SA14-14-2., Competing Interests: The authors declare no conflict of interest.

The attenuated Japanese encephalitis virus (JEV) strain SA14-14-2 has been successfully utilized to prevent JEV infection; however, the attenuation determinants have not been fully elucidated. The envelope (E) protein of the attenuated JEV SA14-14-2 strain differs from that of the virulent parental SA14 strain at eight amino acid positions (E107, E138, E176, E177, E264, E279, E315, and E439). Here, we investigated the SA14-14-2-attenuation determinants by mutating E107, E138, E176, E177, and E279 in SA14-14-2 to their status in the parental virulent strain and tested the replication capacity, neurovirulence, neuroinvasiveness, and mortality associated with the mutated viruses in mice, as compared with those of JEV SA14-14-2 and SA14. Our findings indicated that revertant mutations at the E138 or E107 position significantly increased SA14-14-2 virulence, whereas other revertant mutations exhibited significant increases in neurovirulence only when combined with E138, E107, and other mutations. Revertant mutations at all eight positions in the E protein resulted in the highest degree of SA14-14-2 virulence, although this was still lower than that observed in SA14. These results demonstrated the critical role of the viral E protein in controlling JEV virulence and identified the amino acids at the E107 and E138 positions as the key determinants of SA14-14-2 neurovirulence., Competing Interests: The authors declare no conflict of interest.

HBx is an oncogenic tumor-associated antigen and is dominantly expressed in hepatitis and hepatoma tissues, the induction of active cellular responses against HBx should be a promising approach for the treatment of hepatitis B virus-related hepatocellular carcinoma. The present study was designed to test whether a replication-defective adenovirus vaccine expressing HBx antigen could be effectively used in the immunotherapy of hepatocellular carcinoma. To validate the possibility, we developed a novel HBx-positive hepatocellular carcinoma in mice by inoculated the pcDNA-HBx transfected Hepa1-6 cells subcutaneously into the right flank of mice. We found that immunotherapy with Ad-HBx was effective at both protective and therapeutic antitumor immunity in the hepatoma models in immune-competent mice. Histological examination revealed that Ad-HBx treatment led to significantly increased induction of apoptosis, tumor necrosis, and elevated CD8+ lymphocyte infiltration. In addition, the induction efficacy of the CTL response is dramatically enhanced by immunotherapy. Cytokine analysis confirmed that the antitumor efficacy of Ad-HBx may mostly result from cellular immunity. Our findings may prove useful in development of adenovirus vaccine based on HBx antigen to the treatment of HBV-associated hepatocellular carcinoma.