Trace Br- Inhibits Halogenated Byproduct Formation in Saline Wastewater Electrochemical Treatment.

The electrochemical technology provides a practical and viable solution to the global water scarcity issue, but it has an inherent challenge of generating toxic halogenated byproducts in treatment of saline wastewater. Our study reveals an unexpected discovery: the presence of a trace amount of Br- not only enhanced the electrochemical oxidation of organic compounds with electron-rich groups but also significantly reduced the formation of halogenated byproducts. For example, in the presence of 20 µM Br-, the oxidation rate of phenol increased from 0.156 to 0.563 min-1, and the concentration of total organic halogen decreased from 59.2 to 8.6 µM. Through probe experiments, direct electron transfer and HO• were ruled out as major contributors; transient absorption spectroscopy (TAS) and computational kinetic models revealed that trace Br- triggers a shift in the dominant reactive species from Cl2•- to Br2•-, which plays a key role in pollutant removal. Both TAS and electron paramagnetic resonance identified signals unique to the phenoxyl and carbon-centered radicals in the Br2•--dominated system, indicating distinct reaction mechanisms compared to those involving Cl2•-. Kinetic isotope experiments and density functional theory calculations confirmed that the interaction between Br2•- and phenolic pollutants follows a hydrogen atom abstraction pathway, whereas Cl2•- predominantly engages pollutants through radical adduct formation. These insights significantly enhance our understanding of bromine radical-involved oxidation processes and have crucial implications for optimizing electrochemical treatment systems for saline wastewater.

One-electron oxidant-induced transformation of dissolved organic matter: Optical and antioxidation properties and molecules.

Dissolved organic matter (DOM) is a major sink of radicals in advanced oxidation processes (AOPs) and the radical-induced DOM transformation influences the subsequent water treatment processes or receiving waters. In this study, we quantified and compared DOM transformation by tracking the changes of dissolved organic carbon (DOC), UVA254, and electron donating capacity (EDC) as functions of four one-electron oxidants (SO4•-, Cl2•-, Br2•-, and CO3•-) exposures as well as the changes of functional groups and molecule distribution. SO4•- had the highest DOC reduction while Cl2•- had the highest EDC reduction, which could be due to their preferential reaction pathways of decarboxylation and converting phenols to quinones, respectively. Br2•- and CO3•- induced less changes in DOC, UVA254, and EDC than SO4•- and Cl2•-. Additionally, DOM enriched with high aromatic contents tended to have higher DOC, UVA254, and EDC reductions. Decreases in hydroxyl and carboxyl groups and increases in carbonyl groups were observed in these four types of radicals treated DOM using Fourier transform infrared spectroscopy. High resolution mass spectrometry using FTICR-MS showed that one-electron oxidants preferred to attack unsaturated carbon skeletons and transformed into molecules featuring high saturation and low aromaticity. Moreover, SO4•- was inclined to decrease oxidation state of carbon and O/C of DOM due to its strong decarboxylation capacity. This study highlights the distinct DOM transformation by four one-electron oxidants and provides comprehensive insights into the reactions of one-electron oxidants with DOM.

Language Nativeness Modulates Physiological Responses to Moral vs. Immoral Concepts in Chinese-English Bilinguals: Evidence from Event-Related Potential and Psychophysiological Measures.

Morality has been an integral part of social cognition and our daily life, and different languages may exert distinct impacts on human moral judgment. However, it remains unclear how moral concept is encoded in the bilingual brain. This study, therefore, aimed to explore the emotional and cognitive involvement of bilingual morality judgement by using combined event-related potential (ERP) and psychophysiological (including skin, heart, and pulse) measures. In the experiment, thirty-one Chinese-English bilingual participants were asked to make moral judgments in Chinese and English, respectively. Our results revealed increased early frontal N400 and decreased LPC in L1 moral concept encoding as compared to L2, suggesting that L1 was more reliant on automatic processes and emotions yet less on elaboration. In contrast, L2 moral and immoral concepts elicited enhanced LPC, decreased N400, and greater automatic psychophysiological electrocardiograph responses, which might reflect more elaborate processing despite blunted emotional responses and increased anxiety. Additionally, both behavioral and P200 data revealed a reliable immorality bias across languages. Our results were discussed in light of the dual-process framework of moral judgments and the (dis)embodiment of bilingual processing, which may advance our understanding of the interplay between language and morality as well as between emotion and cognition.

Boosting Ammonium Oxidation in Wastewater by the BiOCl-Functionalized Anode.

Mixed metal oxide (MMO) anodes are commonly used for electrochlorination of ammonium (NH4+) in wastewater treatment, but they suffer from low efficiency due to inadequate chlorine generation at low Cl- concentrations and sluggish reaction kinetics between free chlorine and NH4+ under acidic pH conditions. To address this challenge, we develop a straightforward wet chemistry approach to synthesize BiOCl-functionalized MMO electrodes using the MMO as an efficient Ohmic contact for electron transfer. Our study demonstrates that the BiOCl@MMO anode outperforms the pristine MMO anode, exhibiting higher free chlorine generation (24.6-60.0 mg Cl2 L-1), increased Faradaic efficiency (75.5 vs 31.0%), and improved rate constant of NH4+ oxidation (2.41 vs 0.76 mg L-1 min-1) at 50 mM Cl- concentration. Characterization techniques including electron paramagnetic resonance and in situ transient absorption spectra confirm the production of chlorine radicals (Cl• and Cl2•-) by the BiOCl/MMO anode. Laser flash photolysis reveals significantly higher apparent second-order rate constants ((4.3-4.9) × 106 M-1 s-1 at pH 2.0-4.0) for the reaction between NH4+ and Cl•, compared to the undetectable reaction between NH4+ and Cl2•-, as well as the slower reaction between NH4+ and free chlorine (102 M-1 s-1 at pH < 4.0) within the same pH range, emphasizing the significance of Cl• in enhancing NH4+ oxidation. Mechanistic studies provide compelling evidence of the capacity of BiOCl for Cl- adsorption, facilitating chlorine evolution and Cl• generation. Importantly, the BiOCl@MMO anode exhibits excellent long-term stability and high catalytic activity for NH4+-N removal in a real landfill leachate. These findings offer valuable insights into the rational design of electrodes to improve electrocatalytic NH4+ abatement, which holds great promise for wastewater treatment applications.

Topics of questions and community interaction in social Q&A during the COVID-19 pandemic.

BACKGROUND: Considering social distancing requirements and isolation during the COVID-19 pandemic and the widespread health mis/disinformation on social media, filling the pandemic-related information gap is critical. OBJECTIVES: This study explored COVID-19-related question topics, topic correlation, evolving trends, and community interactions by leveraging data from a health question-answering (Q&A) community (public and health professionals) over a 2-year period. METHODS: A total of 828 questions were collected and manually reviewed from a health Q&A and classified into 2492 codes. Question topic correlations, trends, and community interactions were generated using different statistical techniques. RESULTS: Thirty-seven topics were identified, and strong topic correlations were observed between the cognitive layer and other layers. These topics changed as the pandemic developed. Community interaction analyses revealed topics that were popular but received comparatively fewer responses. DISCUSSION: The findings could illuminate the dynamic changes in people's interests and concerns related to COVID-19 and their experiences of exchanging information in social Q&A communities. CONCLUSION: This study examined the practical significance of understanding topics of interest during a pandemic. The findings can inform the design of social health Q&A platforms that could reduce the risks of misinformation and disinformation.

Reactive species conversion into 1O2 promotes substantial inhibition of chlorinated byproduct formation during electrooxidation of phenols in Cl--laden wastewater.

The generation of chlorinated byproducts during the electrochemical oxidation (EO) of Cl--laden wastewater is a significant concern. We aim to propose a concept of converting reactive species (e.g., reactive chlorines and HO• resulting from electrolysis) into 1O2 via the addition of H2O2, which substantially alleviates chlorinated organic formation. When phenol was used as a model organic compound, the results showed that the H2O2-involving EO system outperformed the H2O2-absent system in terms of higher rate constants (5.95 × 10-2 min-1vs. 2.97 × 10-2 min-1) and a much lower accumulation of total organic chlorinated products (1.42 mg L-1vs. 8.18 mg L-1) during a 60 min operation. The rate constants of disappearance of a variety of phenolic compounds were positively correlated with the Hammett constants (σ), suggesting that the reactive species preferred oxidizing phenols with electron-rich groups. After the identification of 1O2 that was abundant in the bulk solution with the use of electron paramagnetic resonance and computational kinetic simulation, the routes of 1O2 generation were revealed. Despite the consensus as to the contribution of reaction between H2O2 and ClO- to 1O2 formation, we conclude that the predominant pathway is through H2O2 reaction with electrogenerated HO• or chlorine radicals (Cl• and Cl2•-) to produce O2•-, followed by self-combination. Density functional theory calculations theoretically showed the difficulty in forming chlorinated byproducts for the 1O2-initiated phenol oxidation in the presence of Cl-, which, by contrast, easily occurred for the Cl•-or HO•-initiated phenol reaction. The experiments run with real coking wastewater containing high-concentration phenols further demonstrated the superiority of the H2O2-involving EO system. The findings imply that this unique method for treating Cl--laden organic wastewater is expected to be widely adopted for generalizing EO technology for environmental applications.

Rational Design of Oxazolidine-Based Red Fluorescent pH Probe for Simultaneous Imaging Two Subcellular Organelles.

A reversible pH-responsive fluorescent probe, BP, was rationally designed and synthesized, based on protonation and deprotonation gave rise to oxazolidine ring open and close. The fluorescence response of BP against pH ranges from 3.78 to 7.54, which is suitable for labeling intracellular pH-dependent organelles. BP displayed strong red emission at a relatively high pH in living HeLa cells and U87 cells. More importantly, this probe exhibited good colocalization with both mitochondria and lysosomes in these two cell lines, attributing to pH-induced structure tautomerism resulting in an oxazolidine ring open and close that triggered effective targeting of these two organelles. As organelle interactions are critical for cellular processes, this strategy of targeting dual organelles through the structure tautomerism is conducive to further developing more effective and advanced probes for real-time imaging of the interaction between mitochondria and lysosomes.

The glycoprotein Wnt6 regulates human dental papilla cells differentiation by canonical Wnt signaling pathway.

OBJECTIVE: The aim of this study was to test the hypothesis in vitro and in vivo, that the glycoprotein Wnt6 can regulate human dental papilla cell differentiation by ß-catenin signaling. DESIGN: The expression of Wnt6 was detected by quantitative polymerase chain reaction (qPCR). Wnt6 stealth RNA was used to knockdown the expression of Wnt6. The Wnt canonical signaling was detected by immunofluorescence staining, qPCR, and TOPflash/FOPflash dual-luciferase reporter assay. The differentiation was investigated by alkaline phosphatase staining or Alizarin Red staining after osteo/odontogenic medium culture and by Masson trichrome staining after subcutaneous transplantation. There are at least three samples in one group for each experiment. RESULTS: Wnt6 protein and mRNA were high expressed in dental mesenchyme tissue and cells. In human dental papilla cells, Wnt6 over-expression could activate ß-catenin dependent pathway, including ß-catenin accumulation in cell nuclei, lymphoid enhancer factor 1 mRNA up-regulation, and enhanced ß-catenin transcriptional activity. Wnt6 activated ß-catenin pathway in a similar way to Wnt3a but at a lower level. Wnt6 inhibited human dental papilla cells differentiation as alkaline phosphatase activity in vitro, and promoted differentiation as mineralization after subcutaneous transplantation in vivo, as same trend as Wnt3a but at a lower level. The Wnt/ß-catenin inhibitor XAV939 treatment attenuated Wnt6- or Wnt3a-induced human dental papilla cells mineralization. CONCLUSIONS: Wnt6 activated ß-catenin dependent pathway and regulated human dental papilla cells differentiation. Potential mechanism of Wnt6-regulated cell differentiation is the activation of Wnt/ß-catenin signaling pathway.

Peroxydisulfate activation by nano zero-valent iron graphitized carbon materials for ciprofloxacin removal: Effects and mechanism.

Since the discovery of the potential hazards of ciprofloxacin (CIP) to the ecosystem and human health, there has been an urgent need to develop effective technologies to solve the severe issue. In this work, the nanozero-valent iron graphitized carbon matrix (xFe@CS-Tm) were prepared via a hydrothermal method to activate peroxydisulfate (PDS) for degradation of CIP. Specifically, 0.5Fe@CS-T7 exhibited the excellent catalytic performance for PDS activation to degrade CIP. Moreover, the catalyst exhibited vigorous interference resistance at various pH values, in the presence of various inorganic anions and under humic acid conditions. The characterization results demonstrated that Fe was successfully embedded on the carbon matrix and became the active sites to promote ROS production. It is demonstrated that O2•- was the main active species rather than •OH and SO4•-, based on quench trapping, EPR experiments and steady state concentrations calculations. The possible pathways of CIP degradation were proposed using LC-MS results and density functional theory. The outcomes of the toxicity estimation software tool found that the toxicity of CIP was reduced. This study not only investigated a novel methodology for the degradation of antibiotic wastewater but also provides a feasible pathway for carbon-neutral wastewater treatment.

Designing NAZO@BC electrodes for enhanced elimination of hydrophilic organic pollutants in heterogeneous electro-Fenton system: Insights into the detoxification mediated by 1O2 and •OH.

Hydrophilic organic pollutants (HLOPs) in effluents of wastewater treatment plants are more prevalent than hydrophobic counterparts, therefore development of upstream processes that can effectively enhance the removal of HLOPs can substantially enhance overall treatment performance. To bridge this gap, 3D electrodes made of biochar-supported Al-ZnO nanoparticles (NAZO@BC) applied in heterogeneous electro-Fenton (EF) system, abbreviated as NBE-EF system, is rationally designed for enhanced elimination of HLOPs in wastewater. Our analysis indicates the NBE-EF system results in an efficient THM elimination, 42.4 times greater than that of conventional EF system. MoS2 as an efficient cocatalyst plays an important role in the conversion from Fe(III) to Fe(II). Singlet oxygen (1O2) and hydroxyl radical (•OH) are identified as the primary reactive oxygen species (ROS) in the NBE-EF system. NAZO@BC electrodes could concentrate HLOPs on their surface and degrade it effectively, achieving also a self-cleaning effect. Effective elimination of four HLOPs, i.e., thiamethoxam (THM), dinotefuran (DIN), nitenpyram (NIT), and acetamiprid (ACE), demonstrated the high degradation performance of the NBE-EF system, even at neutral and alkaline conditions. This study provides a new approach for enhanced elimination of HLOPs in wastewater treatment and mechanical insights into degradation pathways and toxicity attenuation.

Role of sulfide-modified nanoscale zero-valent iron on carbon nanotubes in nonradical activation of peroxydisulfate.

Sulfamethoxazole (SMX) is highly persistent and difficult to remove, making it urgent to find an efficient method for alleviating the enormous environmental pressure of SMX. In this study, sulfide-modified nanoscale zero-valent iron on carbon nanotubes (S-nZVI@CNTs) was prepared to activate peroxydisulfate (PDS) for the degradation of SMX. The results showed that SMX was completely removed within 40 min (kobs=0.1058 min-1) in the S-nZVI@CNTs/PDS system. By analyzing quenching experiments and electron paramagnetic resonance (EPR), singlet oxygen (1O2) was the main active species of the S-nZVI@CNTs/PDS system. 1O2 might be mediated by the abundant carbonyl groups (CO) on carbon nanotubes through spectroscopic analyses. In addition, sulfur doping transitioned the activation pathway to a nonradical pathway. Spectroscopic analyses and electrochemical experiments confirmed that the formation of CNTs-PDS complexes and S-nZVI could promote electron transfer on the catalyst surface. Furthermore, the main degradation intermediates of SMX were identified, and five possible transformation pathways were proposed. The S-nZVI@CNTs/PDS system possessed advantages including high anti-interference (Cl-, NO3-, HA), a strong applicability, recyclability and a low PDS consumption, offering new insight into the degradation of antibiotic wastewater.

Carbon materials in persulfate-based advanced oxidation processes: The roles and construction of active sites.

Many researchers have paid more attention to the progress of carbon materials owing to their advantages, such as high activity, low cost, large surface area, high conductivity and high stability. Carbon materials have been widely used in persulfate-based advanced oxidation processes (PS-AOPs), especially for graphene (G), carbon nanotubes (CNTs) and biochar (BC). Various strategies are applied to promote their activity, however, up to now, the relationship between the structures of carbon materials and their activities in PS-AOPs has not been specifically reviewed. The methods to switch reaction pathway (radical and nonradical pathways) in carbon-persulfate-based AOPs have not been systematically explored. Hereon, this review illustrated the active sites of G, CNTs, BC and other carbon materials, and generalized the modification methods to promote the activity of carbon materials and to switch reaction pathway in PS-AOPs. The roles of carbon materials in PS-AOPs were discussed around reactive oxygen species (ROS) and the structures. ROS are frequently complex in AOPs, but main ROS generation is related to the active sites on carbon materials. The structures of carbon materials (e.g., metal-carbon bonds, the electron-deficient C atoms, unbalanced electron distribution and graphitized structures) play a decisive role in the nonradical pathway. Finally, future breakthroughs of carbon materials were proposed for practical engineering and multi-field application.