Synthesis and antibacterial activities of heterocyclic ring-fused 20(S)-protopanaxadiol derivatives.

Multidrug-resistant (MDR) bacterial infections are becoming a life-threatening issue in public health; therefore, it is urgent to develop novel antibacterial agents for treating infections caused by MDR bacteria. The 20(S)-protopanaxadiol (PPD) derivative 9 was identified as a novel antibacterial hit compound in screening of our small synthetic natural product-like (NPL) library. A series of novel PPD derivatives with heterocyclic rings fused at the C-2 and C-3 positions of the A-ring were synthesized and their antibacterial activities against Staphylococcus aureus (S. aureus) Newman strain and MDR S. aureus strains (USA300, NRS-1, NRS-70, NRS-100, NRS-108, NRS-271, XJ017, and XJ036) were evaluated. Among these compounds, quinoxaline derivative 56 (SH617) exhibited the highest activity with MICs of 0.5-4 µg/mL against the S. aureus Newman strain and the eight MDR S. aureus strains. Its antibacterial activity was comparable to that of the positive control, vancomycin. In the zebrafish, 56 revealed no obvious toxicity even at a high administered dose. In vivo, following a lethal infection induced by USA300 strains in zebrafish, 56 exhibited significantly increased survival rates in a dose-dependent manner.

Safety assessment of brexanolone in the FAERS database: real adverse event analysis and discussion of side effects.

BACKGROUND: Postpartum depression (PPD) is linked to hormonal changes. Brexanolone, the first FDA-approved drug for PPD, is a potential treatment. This study analyzes Brexanolone's safety using the FAERS database, highlighting its adverse effects and potential risk factors. METHODS: We analyzed FAERS data from Q3 2019 to Q3 2023, evaluating adverse reactions to Brexanolone. The analysis includes demographics, reporting regions, reporter identities, and types of adverse reactions. RESULTS: Most reports are from the United States, with consumers and physicians as primary reporters. Adverse reactions mainly involve severe systemic diseases, administration site reactions, injuries, intoxication, operational complications, and mental disorders. Specific adverse reactions include incorrect drug monitoring, PPD, intrusive thoughts, delayed treatment efficacy, sedation complications, product discontinuation, misuse, infusion site leakage and pain, and medication errors. CONCLUSION: The study confirms known safety information about Brexanolone and provides comprehensive data for medical practices and public health decisions. However, relying on spontaneous reports may introduce biases and incomplete information. Continued monitoring and reporting of adverse reactions to newer drugs like Brexanolone remain crucial.

Gossypium arboreum PPD2 facilitates root architecture development to increase plant resilience to salt stress.

The jasmonic acid (JA) signaling pathway plays an important role in plant responses to abiotic stresses. The PEAPOD (PPD) and jasmonate ZIM-domain (JAZ) protein in the JA signaling pathway belong to the same family, but their functions in regulating plant defense against salt stress remain to be elucidated. Here, Gossypium arboreum PPD2 was overexpressed in Arabidopsis thaliana and systematically silenced in cotton for exploring its function in regulating plant defense to salt stress. The GaPPD2-overexpressed Arabidopsis thaliana plants significantly increased the tolerance to salt stress compared to the wild type in both medium and soil, while the GaPPD2-silenced cotton plants showed higher sensitivity to salt stress than the control in pots. The antioxidant activities experiment showed that GaPPD2 may mitigate the accumulation of reactive oxygen species by promoting superoxide dismutase accumulation, consequently improving plant resilience to salt stress. Through the exogenous application of MeJA (methy jasmonate) and the protein degradation inhibitor MG132, it was found that GaPPD2 functions in plant defense against salt stress and is involved in the JA signaling pathway. The RNA-seq analysis of GaPPD2-overexpressed A. thaliana plants and receptor materials showed that the differentially expressed genes were mainly enriched in antioxidant activity, peroxidase activity, and plant hormone signaling pathways. qRT-PCR results demonstrated that GaPPD2 might positively regulate plant defense by inhibiting GH3.2/3.10/3.12 expression and activating JAZ7/8 expression. The findings highlight the potential of GaPPD2 as a JA signaling component gene for improving the cotton plant resistance to salt stress and provide insights into the mechanisms underlying plant responses to environmental stresses.

Comparative toxic effect of tire wear particle-derived compounds 6PPD and 6PPD-quinone to Chlorella vulgaris.

N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), a widely used antioxidant in rubber products, and its corresponding ozone photolysis product N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPD-Q), have raised public concerns due to their environmental toxicity. However, there is an existing knowledge gap on the toxicity of 6PPD and 6PPD-Q to aquatic plants. A model aquatic plant, Chlorella vulgaris (C. vulgaris), was subjected to 6PPD and 6PPD-Q at concentrations of 50, 100, 200, and 400 µg/L to investigate their effects on plant growth, photosynthetic, antioxidant system, and metabolic behavior. The results showed that 6PPD-Q enhanced the photosynthetic efficiency of C. vulgaris, promoting growth of C. vulgaris at low concentrations (50, 100, and 200 µg/L) while inhibiting growth at high concentration (400 µg/L). 6PPD-Q induced more oxidative stress than 6PPD, disrupting cell permeability and mitochondrial membrane potential stability. C. vulgaris responded to contaminant-induced oxidative stress by altering antioxidant enzyme activities and active substance levels. Metabolomics further identified fatty acids as the most significantly altered metabolites following exposure to both contaminants. In conclusion, this study compares the toxicity of 6PPD and 6PPD-Q to C. vulgaris, with 6PPD-Q demonstrating higher toxicity. This study provides valuable insight into the risk assessment of tire wear particles (TWPs) derived chemicals in aquatic habitats and plants.

Environmental concentrations of 6PPD and 6PPD-Q cause oxidative damage and alter metabolism in Eichhornia crassipes.

N-(1,3-dimethylbutyl)-N '-phenyl-p-phenylenediamine (6PPD) and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPD-Q) are ubiquitous in the environment and can cause toxicity to aquatic animals. However, research on the toxicological effects of 6PPD and 6PPD-Q on aquatic plants remains limited. The present study investigated the physiological, biochemical, and metabolic responses of the floating aquatic plant Eichhornia crassipes (E. crassipes) to environmentally relevant concentrations (0.1, 1, and 10 µg·L-1) of 6PPD and 6PPD-Q. We found that 6PPD and 6PPD-Q elicited minimal effects on plant growth, but 6PPD induced a concentration-dependent decrease in the content of photosynthetic pigments. Low doses (0.1 µg·L-1 and 1 µg·L-1) of 6PPD-Q significantly elevated Reactive Oxygen Species (ROS) content in E. crassipes roots, indicating oxidative damage. Furthermore, 6PPD-Q induced a more pronounced osmotic stress compared to 6PPD. Metabolic analyses revealed that carbohydrates were significantly altered under 6PPD and 6PPD-Q treatments. The findings of this study enhance the understanding of the environmental risks posed by 6PPD and 6PPD-Q to plants and reveal the potential mechanisms of phytotoxicity.

Automated Image-Based Fluorescence Screening of Mitochondrial Membrane Potential in Daphnia magna: An Advanced Ecotoxicological Testing Tool.

This study demonstrated the strengths of in vivo molecular staining coupled with automated imaging analysis in Daphnia magna. A multiwell plate protocol was developed to assess mitochondrial membrane potential using the JC-1 dye. The suitability of five common anesthetics was initially tested, and 5% ethanol performed best in terms of anesthetic effects and healthy recovery. The staining conditions were optimized to 30 min staining with 2 µM JC-1 for best J-aggregate formation. The protocol was validated with the model compound carbonyl cyanide 3-chlorophenylhydrazone (CCCP) and used to measure the effect of four environmental contaminants, 2,4-dinitrophenol, triclosan, n-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), and ibuprofen, on mitochondrial health. Test organisms were imaged using an automated confocal microscope, and fluorescence intensities were automatically quantified. The effect concentrations for CCCP were lower by a factor of 30 compared with the traditional OECD 202 acute toxicity test. Mitochondrial effects were also detected at lower concentrations for all tested environmental contaminants compared to the OCED 202 test. For 2,4-dinitrophenol, mitochondria effects were detectable after 2 h exposure to environmentally relevant concentrations and predicted organism death was observed after 24 h. The high sensitivity and time efficiency of this novel automated imaging method make it a valuable tool for advancing ecotoxicological testing.

Cotransport of 6PPD-Q and pristine/aged microplastics in porous media: An insight based on transport forms and mechanisms.

The environmental fate and risks of microplastics (MPs) and their associated contaminants have attracted increasing concern in recent years. In this study, the cotransport of six kinds of pristine and aged MPs and the antiager ozonation product N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPD-Q) were investigated via a series of batch and transport experiments, and characteristic analysis (e.g., SEM, FTIR and XPS). Generally, pristine MPs exhibit higher adsorption ability than aged MPs due to the hydrophobic interaction. The 6PPD-Q usually exhibited both free moving and bond-MPs moving during transport process in presence of MPs, but none free 6PPD-Q was detected in presence of pristine PP MPs. The mobility of 6PPD-Q was generally facilitated in presence of MPs by bond-MPs moving due to the hydrogen bonding, halogen bonding, π-π interaction (the maximum total mass recovery of 84.11%), which efficiency was influenced with the combined effect of adsorption ability and mobility of MPs. The pristine PVC MPs showed highest facilitation on 6PPD-Q transport. The retained 6PPD-Q in porous media also was released by various MPs with different mass recovery ranged from 15.72% to 56.26% via surface moving of MPs around porous media. Both the dissolved and retained 6PPD-Q decreased the MPs mobility with the minimum mass recovery of 34.02%. Findings from this study contribute to the prediction and assessment of the combined risks of MPs and 6PPD-Q.

Degradation and detoxification of 6PPD-quinone in water by ultraviolet-activated peroxymonosulfate: Mechanisms, byproducts, and impact on sediment microbial community.

N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone (6PPD-Q) has been identified to induce acute toxicity to multifarious aquatic organisms at exceptionally low concentrations. The ubiquity and harmful effects of 6PPD-Q emphasize the critical need for its degradation from water ecosystems. Herein, we explored the transformation of 6PPD-Q by an ultraviolet-activated peroxymonosulfate (UV/PMS) system, focusing on mechanism, products and toxicity variation. Results showed that complete degradation of 6PPD-Q was achieved when the initial ratio of PMS and 6PPD-Q was 60:1. The quenching experiments and EPR tests indicated that SO4•- and •OH radicals were primarily responsible for 6PPD-Q removal. Twenty-one degradation products were determined through high-resolution orbitrap mass spectrometry, and it was postulated that hydroxylation, oxidative cleavage, quinone decomposition, ring oxidation, as well as rearrangement and deamination were the major transformation pathways of 6PPD-Q. Toxicity prediction revealed that all identified products exhibited lower acute and chronic toxicities to fish, daphnid and green algae compared to 6PPD-Q. Exposure experiments also uncovered that 6PPD-Q considerably reduced the community diversity and altered the community assembly and functional traits of the sediment microbiome. However, we discovered that the toxicity of 6PPD-Q degradation solutions was effectively decreased, suggesting the superior detoxifying capability of the UV/PMS system for 6PPD-Q. These findings highlight the underlying detrimental impacts of 6PPD-Q on aquatic ecosystems and enrich our understanding of the photochemical oxidation behavior of 6PPD-Q.

Detection of 6-PPD and 6-PPDQ in airborne particulates and assessment of their toxicity in lung cells.

The extensive use of synthetic antioxidants, notably N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6-PPD), in rubber-related products, particularly in tire manufacturing, has induced concerns regarding their environmental impact and potential health hazards. Despite the identification of 6-PPD and its derivative, 6-PPD quinone (6-PPDQ), in various water samples and their lethal effects on certain aquatic species (e.g., coho salmon, rainbow trout and brook trout), the levels of airborne 6-PPD/6-PPDQ and their respiratory toxicity remain relatively unexplored. In this study, we aimed to evaluate the respiratory toxicity potential of 6-PPD and its derivatives, with a specific focus on detecting these compounds in airborne particulates and assessing their toxic effects on lung cells. Characterization of four airborne fine particulate (FP) samples revealed spherical morphologies with diameters ranging from 17.7 to 225.7 nm, displaying slight agglomeration and negative surface charge. methanol/acetonitrile extraction followed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) analysis confirmed the presence of both 6-PPD and 6-PPDQ on the surfaces of FPs, with significant variations (0.26-1.05 µg g-1) in loading capacity observed among the samples. Subsequent exposure of lung cells (THP-1, BEAS-2B, and A549) to 6-PPD and 6-PPDQ revealed dose-dependent declines in mitochondrial metabolic activity induced by 6-PPD, along with severe membrane damage, ATP depletion, and pro-inflammatory cytokine release. Conversely, 6-PPDQ exhibited negligible toxicity in all tested parameters. These findings underscore the potential health risks associated with airborne 6-PPD exposure and emphasize the importance of further research into the respiratory toxicity of 6-PPD derivatives.

Smartphone-based intervention for postpartum depressive symptoms (Smart-e-Moms): study protocol for a randomized controlled trial.

BACKGROUND: Postpartum depression constitutes a significant public health issue, with prevalence rates ranging between 8 and 19% in high-income nations. Nevertheless, numerous barriers, including time constraints, societal stigmatization, and feelings of shame, contribute to the limited utilization of healthcare services during the postpartum period. Digital interventions offer an opportunity to enhance care for women experiencing postpartum depressive symptoms. METHODS: We will conduct a two-arm randomized controlled trial to assess the effectiveness of a smartphone-based intervention in comparison to a treatment-as-usual control group in Germany. Our aim is to randomize 556 participants in a 1:1 ratio. Participants in the intervention group will be provided access to a preventive smartphone-based intervention called "Smart-e-Moms," which incorporates therapeutic support and comprises 10 concise modules rooted in cognitive-behavioral therapy. For the intervention group, evaluations will take place at baseline (t0), prior to sessions 4 and 8 (intermediate assessments), and upon completing the intervention 6 weeks after baseline (t1). The control group's assessments will be at baseline (t0) and 6 weeks after baseline. Follow-up assessments are scheduled at 12 and 24 weeks from baseline to examine the short-term stability of any observed effects. We anticipate that participants in the intervention group will exhibit improvements in their postpartum depressive symptoms (as measured with the Edinburgh Postnatal Depression Scale). Additionally, we will analyze secondary outcomes, including maternal bonding, stress levels, self-efficacy, satisfaction with the intervention, and healthcare utilization. DISCUSSION: If Smart-e-Moms proves to be effective, it has the potential to play a significant role in postpartum depression care within German-speaking regions. Ideally, this intervention could not only benefit maternal well-being but also improve the prospects for healthy child development. TRIAL REGISTRATION: German clinical trials registry DRKS00032324. Registered on January 26, 2024.

Mechanisms of exacerbation of Th2-mediated eosinophilic allergic asthma induced by plastic pollution derivatives (PPD): A molecular toxicological study involving lung cell ferroptosis and metabolomics.

Polystyrene microplastics (PS-MP) and dibutyl phthalate (DBP) are plastic pollution derivatives (PPDs) commonly found in the natural environment. To investigate the effects of PPD exposure on the risk of allergic asthma, we established a PPD exposure group in a mouse model. The dose administered for PS-MP was 0.1 mg/d and for DBP was 30 mg/kg/d, with a 5-week oral administration period. The pathological changes of airway tissue and the increase of oxidative stress and inflammatory response confirmed that PPD aggravated eosinophilic allergic asthma in mice. The mitochondrial morphological changes and metabolomics of mice confirmed that ferrotosis and oxidative stress played key roles in this process. Treatment with 100 mg/Kg deferoxamine (DFO) provided significant relief, and metabolomic analysis of lung tissue supported the molecular toxicological. Our findings suggest that the increased levels of reactive oxygen species (ROS) in the lungs lead to Th2-mediated eosinophilic inflammation, characterized by elevated IL-4, IL-5, and eosinophils, and reduced INF-γ levels. This inflammatory response is mediated by the NFκB pathway and exacerbates type I hypersensitivity through increased IL-4 production. In this study, the molecular mechanism by which PPD aggravates asthma in mice was elucidated, which helps to improve the understanding of the health effects of PPD and lays a theoretical foundation for addressing the health risks posed by PPD.

Effects of environmental concentrations of 6PPD and its quinone metabolite on the growth and reproduction of freshwater cladoceran.

The widespread occurrence and accumulation of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) and its quinone metabolite, 6PPD quinone (6PPD-Q), have been globally recognized as a critical environmental issue. However, knowledge on the adverse effects of 6PPD and 6PPD-Q on freshwater invertebrates is limited. This study investigated the effects of 6PPD and its oxidative byproduct, 6PPD-Q, on the growth and reproduction of Daphnia pulex. Through 21-day exposure experiments, we measured the uptake of 0.1, 1, and 10 µg/L 6PPD and 6PPD-Q by D. pulex and assessed the effects on growth and fecundity of D. pulex. While 6PPD and 6PPD-Q did not affect the mortality rate of D. pulex, 6PPD-Q exposure inhibited the growth of D. pulex, indicating potential ecological risks. In particular, the reproductive capacity of D. pulex remained unaffected across the tested concentrations of 6PPD and 6PPD-Q, suggesting specific toxicological pathways that warrant further investigation. This study underscored the importance of evaluating the sublethal effects of emerging contaminants such as 6PPD and 6PPD-Q on aquatic invertebrates, and highlighted the need for comprehensive risk assessments to better understand their environmental impacts.

P-phenylenediamine antioxidants and their quinone derivatives: A review of their environmental occurrence, accessibility, potential toxicity, and human exposure.

Substituted p-phenylenediamines (PPDs), a class of antioxidants, have been widely used to extend the lifespan of rubber products, such as tires and pipes. During use, PPDs will generate their quinone derivatives (PPD-Qs). In recent years, PPDs and PPD-Qs have been detected in the global environment. Among them, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone (6PPD-Q), the oxidation product of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), has been identified as highly toxic to coho salmon, with the lethal concentration of 50 % (LC50) being 95 ng/L, highlighting it as an emerging pollutant of great concern. This review summarizes the physicochemical properties, global environmental distribution, bioaccessibility, potential toxicity, human exposure risk, and green measures of PPDs and PPD-Qs. These chemicals exhibit lipophilicity, bioaccumulation potential, and poor aqueous stability. They have been found in water, air, dust, soil, and sediment worldwide, indicating their significance as emerging pollutants. Notably, current studies have identified electronic waste (e-waste), such as discarded wires and cables, as a non-negligible source of PPDs and PPD-Qs, in addition to tire wear. PPDs and PPD-Qs exhibit strong bioaccumulation in aquatic organisms and mammals, with a tendency for biomagnification within the food web, posing health threats to humans. Available toxicity data indicate that PPDs and PPD-Qs have negative effects on aquatic organisms, mammals, and invertebrates. Acute exposure leads to death and acute damage, and long-term exposure can cause a series of adverse effects, including growth and development toxicity, reproductive toxicity, neurotoxicity, intestinal toxicity, and multi-organ damage. This paper discusses current research gaps and offers recommendations to understand better the occurrence, behavior, toxicity, and environmental exposure risks of PPDs and PPD-Qs.

Estrogenic, Genotoxic, and Antibacterial Effects of Chemicals from Cryogenically Milled Tire Tread.

Tire and road wear particles (TRWP) contain complex mixtures of chemicals and release them to the environment, and potential toxic effects of these chemicals still need to be characterized. We used a standardized surrogate for TRWP, cryogenically milled tire tread (CMTT), to isolate and evaluate effects of tire-associated chemicals. We examined organic chemical mixtures extracted and leached from CMTT for the toxicity endpoints genotoxicity, estrogenicity, and inhibition of bacterial luminescence. The bioassays were performed after chromatographic separation on high-performance thin-layer chromatography (HPTLC) plates. Extracts of CMTT were active in all three HPTLC bioassays with two estrogenic zones, two genotoxic zones, and two zones inhibiting bacterial luminescence. Extracts of CMTT artificially aged with thermooxidation were equally bioactive in each HPTLC bioassay. Two types of aqueous leachates of unaged CMTT, simulating either digestion by fish or contact with sediment and water, contained estrogenic chemicals and inhibitors of bacterial luminescence with similar profiles to those of CMTT extracts. Of 11 tested tire-associated chemicals, two were estrogenic, three were genotoxic, and several inhibited bacterial luminescence. 1,3-Diphenylguanidine, transformation products of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, and benzothiazoles were especially implicated through comparison to HPTLC retention factors in the CMTT samples. Other bioactive bands in CMTT samples did not correspond to any target chemicals. Tire particles clearly contain and can leach complex mixtures of toxic chemicals to the environment. Although some known chemicals contribute to estrogenic, genotoxic, and antibacterial hazards, unidentified toxic chemicals are still present and deserve further investigation. Overall, our study expands the understanding of potential adverse effects from tire particles and helps improve the link between those effects and the responsible chemicals. Environ Toxicol Chem 2024;43:1962-1972. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Tire-derived contaminants 6PPD and 6PPD-Q: Analysis, sample handling, and reconnaissance of United States stream exposures.

The environmental ubiquity of tire and road wear particles (TRWP) underscores the need to understand the occurrence, persistence, and environmental effects of tire-related chemicals in aquatic ecosystems. One such chemical is 6PPD-quinone (6PPD-Q), a transformation product of the tire antioxidant 6PPD. In urban stormwater runoff 6PPD-Q can exceed acute toxicity thresholds for several salmonid species and is being implicated in significant coho salmon losses in the Pacific Northwest. There is a critical need to understand the prevalence of 6PPD-Q across watersheds to identify habitats heavily affected by TRWPs. We conducted a reconnaissance of 6PPD and 6PPD-Q in surface waters across the United States from sites (N = 94) with varying land use (urban, agricultural, and forested) and streamflow to better understand stream exposures. A rapid, low-volume direct-inject, liquid chromatography mass spectrometry method was developed for the quantitation of 6PPD-Q and screening for 6PPD. Laboratory holding times, bottle material, headspace, and filter materials were investigated to inform best practices for 6PPD-Q sampling and analysis. Glass bottles with PTFE-lined caps minimized sorption and borosilicate glass fiber filters provided the highest recovery. 6PPD-Q was stable for at least 5 months in pure laboratory solutions and for 75 days at 5 °C with minimal headspace in the investigated surface water and stormwaters. Results also indicated samples can be frozen to extend holding times. 6PPD was not detected in any of the 526 analyzed samples and there were no detections of 6PPD-Q at agricultural or forested sites. 6PPD-Q was frequently detected in stormwater (57%, N = 90) and from urban impacted sites (45%, N = 276) with concentrations ranging from 0.002 to 0.29 µg/L. The highest concentrations, above the lethal level for coho salmon, occurred during stormwater runoff events. This highlights the importance of capturing episodic runoff events in urban areas near ecologically relevant habitat or nursery grounds for sensitive species.

Elucidating Black α-CsPbI3 Perovskite Stabilization via PPD Bication-Conjugated Molecule Surface Passivation: Ab Initio Simulations.

The cubic α-CsPbI3 phase stands out as one of the most promising perovskite compounds for solar cell applications due to its suitable electronic band gap of 1.7 eV. However, it exhibits structural instability under operational conditions, often transforming into the hexagonal non-perovskite δ-CsPbI3 phase, which is unsuitable for solar cell applications because of the large band gap (e.g., ∼2.9 eV). Thus, there is growing interest in identifying possible mechanisms for increasing the stability of the cubic α-CsPbI3 phase. Here, we report a theoretical investigation, based on density functional theory calculations, of the surface passivation of the α-, γ-, and δ-CsPbI3(100) surfaces using the C6H4(NH3)2 [p-phenylenediamine (PPD)] and Cs species as passivation agents. Our calculations and analyses corroborate recent experimental findings, showing that PPD passivation effectively stabilizes the cubic α-CsPbI3 perovskite against the cubic-to-hexagonal phase transition. The PPD molecule exhibits covalent-dominating bonds with the substrate, which makes it more resistant to distortion than the ionic bonds dominant in perovskite bulks. By contrasting these results with the natural Cs passivation, we highlight the superior stability of the PPD passivation, as evidenced by the negative surface formation energies, unlike the positive values observed for the Cs passivation. This disparity is due to the covalent characteristics of the molecule/surface interaction of PPD, as opposed to the purely ionic interaction seen with the Cs passivation. Notably, the PPD passivation maintains the optoelectronic properties of the perovskites because the electronic states derived from the PPD molecules are localized far from the band gap region, which is crucial for optoelectronic applications.

The spatio-temporal accumulation of 6 PPD-Q in greenbelt soils and its effects on soil microbial communities.

6 PPD-Q (6 PPD-Quinone) is an ozone-induced byproduct derived from the degradation of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6 PPD), commonly found in road dust resulting from tire wear. However, the extent of 6 PPD-Q pollution in urban soil remains unclear. This study investigates the spatial and temporal accumulation patterns of 6 PPD-Q in greenbelt soils in Ningbo, and explores the correlation between 6 PPD-Q accumulation and soil microbial community composition and functions. Our findings indicate that 6 PPD-Q is present (ranging from 0.85 to 12.58 µg/kg) in soil samples collected from both sides of urban traffic arteries. Soil fungi exhibit higher sensitivity to 6 PPD-Q accumulation compared to bacteria, and associated fungi (Basidiomycota) may be potential biomarkers for environmental 6 PPD-Q contamination. Co-occurrence network analysis reveals that the bacterial microbial network in summer exhibits greater stability and resilience in response to 6 PPD-Q inputs than in winter. However, 6 PPD-Q accumulation disrupts the network structure of fungal communities to some extent, leading to reduced diversity in fungal microbial communities. Long-term accumulation of 6 PPD-Q weakens the nitrogen and phosphorus cycling potential within urban soil, while the enhancement of carbon cycling may further promote 6 PPD-Q degradation in urban soil. Taken together, this study provides new insights into the ecological risks of 6 PPD-Q in urban soils.

Synthesis of a cysteine functional covalent organic framework via facile click reaction for the efficient solid phase extraction of substituted p-phenylenediamine-derived quinones.

N,N'-Substituted p-phenylenediamine quinones (PPD-Qs) are the emerging toxicant, which transform from the rubber tire antioxidant N,N'-substituted p-phenylenediamines (PPDs). Because of their potential toxic and widespread occurrence in the environment, PPD-Qs have received great attention. However, efficiently extracting PPD-Qs from complex samples is still a challenge. Herein, a cysteine functional covalent organic framework (Cys-COF) designed according to the "donor-acceptor" sites of hydrogen bonding of PPD-Qs was synthesized via click reaction and then used as solid-phase extraction (SPE) adsorbent. Cys-COF can form the seven-member ring adsorption structure with PPD-Qs via hydrogen bonding. The adsorption mechanism was tentatively revealed by density functional theory (DFT). After optimizing the Cys-COF-SPE parameters, PPD-Qs were efficiently extracted from water, soil, sediment, and fish, followed by detection using ultra-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The Cys-COF-SPE-UHPLC-MS/MS method exhibited ideal linearity (R2 ≥ 0.9932), high relative recoveries (80.4-111 %), and low limits of detection (0.0001-0.0013 ng mL-1). In addition, the bioconcentration kinetics in goldfish provides a feasible platform to investigate the toxicity and accumulated ability of PPD-Qs.

p­Phenylenediamine antioxidants in PM2.5: New markers for traffic in positive matrix factorization source apportionment.

The extensive utilization of rubber-related products can lead to a substantial release of p-phenylenediamine (PPD) antioxidants into the environment. In recent years, studies mainly focus on the pollution characteristics and health risks of PM2.5-bound PPDs. This study presents long-time scale data of PPDs and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone (6PPD-Q) in PM2.5 and proposes the innovative use of PPDs as new markers for vehicular emissions in the Positive Matrix Factorization (PMF) source apportionment. The results indicate that PPDs and 6PPD-Q were detectable in 100 % of the winter PM2.5 samples, and the concentration ranges of PPDs and 6PPD-Q are 15.6-2.92 × 103 pg·m-3 and 3.90-27.4 pg·m-3, respectively, in which 6PPD and DNPD are the main compounds. Moreover, a competitive formation mechanism between sulfate, nitrate, ammonium (SNA) and 6PPD-Q was observed. The source apportionment results show that the incorporation of PPDs in PMF reduced the contribution of traffic source to PM2.5 from 13.5 % to 9.5 %. In the traffic source factor profiles, the load of IPPD, CPPD, DPPD, DNPD and 6PPD reaches 91.8 %, 91.6 %, 92.9 %, 80.6 % and 87.2 %, respectively. It`s amazing that traditional markers of traffic source, which often overlap with coal burning and industrial sources, over-estimated the contribution of vehicles by one third or more. The discovery of PPDs as specific markers for vehicular emissions holds significant utility, particularly considering the growing proportion of new energy vehicles in the future. The results may prove more accurate policy implications for pollution control. SYNOPSIS: PPDs are excellent indicators of vehicle emissions, and PMF without PPDs over-estimated the contribution of traffic source to PM2.5.