Genome-wide association study and genomic prediction for resistance to brown planthopper in rice.

The brown planthopper (BPH) is the most destructive insect pest that threatens rice production globally. Developing rice varieties incorporating BPH-resistant genes has proven to be an effective control measure against BPH. In this study, we assessed the resistance of a core collection consisting of 502 rice germplasms by evaluating resistance scores, weight gain rates and honeydew excretions. A total of 117 rice varieties (23.31%) exhibited resistance to BPH. Genome-wide association studies (GWAS) were performed on both the entire panel of 502 rice varieties and its subspecies, and 6 loci were significantly associated with resistance scores (P value < 1.0e-8). Within these loci, we identified eight candidate genes encoding receptor-like protein kinase (RLK), nucleotide-binding and leucine-rich repeat (NB-LRR), or LRR proteins. Two loci had not been detected in previous study and were entirely novel. Furthermore, we evaluated the predictive ability of genomic selection for resistance to BPH. The results revealed that the highest prediction accuracy for BPH resistance reached 0.633. As expected, the prediction accuracy increased progressively with an increasing number of SNPs, and a total of 6.7K SNPs displayed comparable accuracy to 268K SNPs. Among various statistical models tested, the random forest model exhibited superior predictive accuracy. Moreover, increasing the size of training population improved prediction accuracy; however, there was no significant difference in prediction accuracy between a training population size of 737 and 1179. Additionally, when there existed close genetic relatedness between the training and validation populations, higher prediction accuracies were observed compared to scenarios when they were genetically distant. These findings provide valuable resistance candidate genes and germplasm resources and are crucial for the application of genomic selection for breeding durable BPH-resistant rice varieties.

Facilitated Unidirectional Electron Transmission by Ru Nano Particulars Distribution on MXene Mo2C@g-C3N4 Heterostructures for Enhanced Photocatalytic H2 Evolution.

Precious metals exhibit promising potential for the hydrogen evolution reaction (HER), but their limited abundance restricts widespread utilization. Loading precious metal nanoparticles (NPs) on 2D/2D heterojunctions has garnered considerable interest since it saves precious metal consumption and facilitates unidirectional electron transmission from semiconductors to active sites. In this study, Ru NPs loaded on MXenes Mo2C by an in-site simple strategy and then formed 2D/2D heterojunctions with 2D g-C3N4 (CN) via electrostatic self-assembly were used to enhance photocatalytic H2 evolution. Evident from energy band structure analyses such as UV-vis and TRPL, trace amounts of Ru NPs as active sites significantly improve the efficiency of the hydrogen evolution reaction. More interestingly, MXene Mo2C, as substrates for supporting Ru NPs, enriches photoexcited electrons from CN, thereby enhancing the unidirectional electron transmission. As a result, the combination of Ru-Mo2C and CN constructs a composite heterojunction (Ru-Mo2C@CN) that shows an improved H2 production rate at 1776.4 µmol∙g-1∙h-1 (AQE 3.58% at 400 nm), which is facilitated by the unidirectional photogenerated electron transmission from the valence band on CN to the active sites on Ru (CN→Mo2C→Ru). The study offers fresh perspectives on accelerated unidirectional photogenerated electron transmission and saved precious metal usage in photocatalytic systems.

Modulating the pore and electronic structure for targeted recovery of platinum: Accelerated kinetic and reinforced coordination.

Adsorption for recovery of low-concentration platinum (Pt) from the complex composition of acidic digestates was challenging because of slow kinetic and poor affinity. It was expected to be overcome by the improvement of pore size distribution and adsorption site activity. Herein, a series of Prussian blue etchings (PBE) with porosity-rich and activity-high cyano (CN) was synthesized to recover low-concentration Pt. The N2 isotherm results showed that the pore structure evolved from mesoporous to microporous. The Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations results revealed that the modulation of electronic structure converted FeII to FeIII in [FeII(CN)6]4-. The coexistence of micro- and meso-pore structures provided channels to accelerate adsorption and ensured PtII enrichment. The regulation of Fe valence state activated CN, which reinforced the strength of coordination interaction between Pt and Fe-CN- at N-atom. The adsorption rate and maximum capacity of PBE1 were 4.4 and 2.5 times higher than those of PB, respectively, due to the dual efficacy of accelerated kinetic and reinforced coordination. This study systematically analyzes the pivotal role of pore and electronic structure modulation in adsorption kinetic and affinity, which provides a novel strategy for PtII targeted recovery.

What We Do Not Know About Stretching in Healthy Athletes: A Scoping Review with Evidence Gap Map from 300 Trials.

BACKGROUND: Stretching has garnered significant attention in sports sciences, resulting in numerous studies. However, there is no comprehensive overview on investigation of stretching in healthy athletes. OBJECTIVES: To perform a systematic scoping review with an evidence gap map of stretching studies in healthy athletes, identify current gaps in the literature, and provide stakeholders with priorities for future research. METHODS: Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 and PRISMA-ScR guidelines were followed. We included studies comprising healthy athletes exposed to acute and/or chronic stretching interventions. Six databases were searched (CINAHL, EMBASE, PubMed, Scopus, SPORTDiscus, and Web of Science) until 1 January 2023. The relevant data were narratively synthesized; quantitative data summaries were provided for key data items. An evidence gap map was developed to offer an overview of the existing research and relevant gaps. RESULTS: Of ~ 220,000 screened records, we included 300 trials involving 7080 athletes [mostly males (~ 65% versus ~ 20% female, and ~ 15% unreported) under 36 years of age; tiers 2 and 3 of the Participant Classification Framework] across 43 sports. Sports requiring extreme range of motion (e.g., gymnastics) were underrepresented. Most trials assessed the acute effects of stretching, with chronic effects being scrutinized in less than 20% of trials. Chronic interventions averaged 7.4 ± 5.1 weeks and never exceeded 6 months. Most trials (~ 85%) implemented stretching within the warm-up, with other application timings (e.g., post-exercise) being under-researched. Most trials examined static active stretching (62.3%), followed by dynamic stretching (38.3%) and proprioceptive neuromuscular facilitation (PNF) stretching (12.0%), with scarce research on alternative methods (e.g., ballistic stretching). Comparators were mostly limited to passive controls, with ~ 25% of trials including active controls (e.g., strength training). The lower limbs were primarily targeted by interventions (~ 75%). Reporting of dose was heterogeneous in style (e.g., 10 repetitions versus 10 s for dynamic stretching) and completeness of information (i.e., with disparities in the comprehensiveness of the provided information). Most trials (~ 90%) reported performance-related outcomes (mainly strength/power and range of motion); sport-specific outcomes were collected in less than 15% of trials. Biomechanical, physiological, and neural/psychological outcomes were assessed sparsely and heterogeneously; only five trials investigated injury-related outcomes. CONCLUSIONS: There is room for improvement, with many areas of research on stretching being underexplored and others currently too heterogeneous for reliable comparisons between studies. There is limited representation of elite-level athletes (~ 5% tier 4 and no tier 5) and underpowered sample sizes (≤ 20 participants). Research was biased toward adult male athletes of sports not requiring extreme ranges of motion, and mostly assessed the acute effects of static active stretching and dynamic stretching during the warm-up. Dose-response relationships remain largely underexplored. Outcomes were mostly limited to general performance testing. Injury prevention and other effects of stretching remain poorly investigated. These relevant research gaps should be prioritized by funding policies. REGISTRATION: OSF project ( https://osf.io/6auyj/ ) and registration ( https://osf.io/gu8ya ).

Endosymbiotic Fungal Diversity and Dynamics of the Brown Planthopper across Developmental Stages, Tissues, and Sexes Revealed Using Circular Consensus Sequencing.

Endosymbiotic fungi play an important role in the growth and development of insects. Understanding the endosymbiont communities hosted by the brown planthopper (BPH; Nilaparvata lugens Stål), the most destructive pest in rice, is a prerequisite for controlling BPH rice infestations. However, the endosymbiont diversity and dynamics of the BPH remain poorly studied. Here, we used circular consensus sequencing (CCS) to obtain 87,131 OTUs (operational taxonomic units), which annotated 730 species of endosymbiotic fungi in the various developmental stages and tissues. We found that three yeast-like symbionts (YLSs), Polycephalomyces prolificus, Ophiocordyceps heteropoda, and Hirsutella proturicola, were dominant in almost all samples, which was especially pronounced in instar nymphs 4-5, female adults, and the fat bodies of female and male adult BPH. Interestingly, honeydew as the only in vitro sample had a unique community structure. Various diversity indices might indicate the different activity of endosymbionts in these stages and tissues. The biomarkers analyzed using LEfSe suggested some special functions of samples at different developmental stages of growth and the active functions of specific tissues in different sexes. Finally, we found that the incidence of occurrence of three species of Malassezia and Fusarium sp. was higher in males than in females in all comparison groups. In summary, our study provides a comprehensive survey of symbiotic fungi in the BPH, which complements the previous research on YLSs. These results offer new theoretical insights and practical implications for novel pest management strategies to understand the BPH-microbe symbiosis and devise effective pest control strategies.

Rapid separation of the low concentration Pd from Pd-Pt coexisting systems: Cyano-group's monomer-specific affinity.

Rapid separation of low concentration palladium (Pd) from Pd-Platinum (Pt) coexisting systems remains a formidable challenge, primarily due to the undifferentiated substitution of ligands in Pd/Pt complexes by adsorption sites. The development of an adsorbent featuring monomer-specific affinity adsorption sites for Pd/Pt could mitigate this drawback. Herein, Manganese hexacyanoferrate (MnHCF) possessing the sensitivity and specificity to Pd ions (Pd(II)) was synthesized via the facile co-precipitation method. MnHCF could rapidly and selectively capture 90.30 % of Pd(II) from a 10 ppm Pd-Pt coexisting system within just 5 min. Spectroscopic analyses and density functional theory (DFT) calculations indicated that cyano-group (CN) in MnHCF exhibited the monomer-specific affinity for targeted capturing Pd via the direct and strong coordination interaction (Fe-CN-PdCl2), which was co-determined by the electron-losing of C (0.06 e) and N (0.07 e) atom. At the same time, CN could neither react directly with the fully coordinated [PtCl6]2- species nor substitute the Cl- ligand, both of which contributed to the non-adsorption of Pt, thus triggering the Pd-Pt separation. This study provides a promising candidate adsorbent for practical applications in platinum group metals recovery by the design of adsorption sites with monomer-specific affinity.

Surface reconstructed Fe@C1000 for enhanced Fenton-like catalysis: Sustainable ciprofloxacin degradation and toxicity reduction.

The Fe-based catalysts typically undergo severe problems such as deactivation and Fe sludge emission during the peroxymonosulfate (PMS) activation, which commonly leads to poor operation and secondary pollution. Herein, an S-doped Fe-based catalyst with a core-shell structure (Fe@CT, T = 1000°C) was synthesized, which can solve the above issues via the dynamic surface evolution during the reaction process. Specifically, the Fe0 on the surface of Fe@C1000 could be consumed rapidly, leaving numerous pores; the Fe3C from the core would subsequently migrate to the surface of Fe@C1000, replenishing the consumed active Fe species. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses demonstrated that the reaction surface reconstructed during the PMS activation, which involved the FeIII in-situ reduction by S species as well as the depletion/replenishment of effective Fe species. The reconstructed Fe@C1000 achieved near-zero Fe sludge emission (from 0.59 to 0.08-0.23 mg L-1) during 5 cycles and enabled the dynamic evolution of dominant reactive oxygen species (ROS) from SO4·- to FeIVO, sustainably improving the oxidation capacity (80.0-92.5% in following four cycles) to ciprofloxacin (CIP) and reducing the toxicity of its intermediates. Additionally, the reconstructed Fe@C1000/PMS system exhibited robust resistance to complex water matrix. This study provides a theoretical guideline for exploring surface reconstruction on catalytic activity and broadens the application of Fe-based catalysts in the contaminants elimination.

Large scale rice germplasm screening for identification of novel brown planthopper resistance sources.

Rice (Oryza sativa L.) is a staple food crop globally. Brown planthopper (Nilaparvata lugens Stål, BPH) is the most destructive insect that threatens rice production annually. More than 40 BPH resistance genes have been identified so far, which provide valuable gene resources for marker-assisted breeding against BPH. However, it is still urgent to evaluate rice germplasms and to explore more new wide-spectrum BPH resistance genes to combat newly occurring virulent BPH populations. To this end, 560 germplasm accessions were collected from the International Rice Research Institute (IRRI), and their resistance to current BPH population of China was examined. A total of 105 highly resistant materials were identified. Molecular screening of BPH resistance genes in these rice germplasms was conducted by developing specific functional molecular markers of eight cloned resistance genes. Twenty-three resistant germplasms were found to contain none of the 8 cloned BPH resistance genes. These accessions also exhibited a variety of resistance mechanisms as indicated by an improved insect weight gain (WG) method, suggesting the existence of new resistance genes. One new BPH resistance gene, Bph44(t), was identified in rice accession IRGC 15344 and preliminarily mapped to a 0-2 Mb region on chromosome 4. This study systematically sorted out the corresponding relationships between BPH resistance genes and germplasm resources using a functional molecular marker system. Newly explored resistant germplasms will provide valualble donors for the identification of new resistance genes and BPH resistance breeding programs. Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-023-01416-x.

A tripartite rheostat controls self-regulated host plant resistance to insects.

Plants deploy receptor-like kinases and nucleotide-binding leucine-rich repeat receptors to confer host plant resistance (HPR) to herbivores1. These gene-for-gene interactions between insects and their hosts have been proposed for more than 50 years2. However, the molecular and cellular mechanisms that underlie HPR have been elusive, as the identity and sensing mechanisms of insect avirulence effectors have remained unknown. Here we identify an insect salivary protein perceived by a plant immune receptor. The BPH14-interacting salivary protein (BISP) from the brown planthopper (Nilaparvata lugens Stål) is secreted into rice (Oryza sativa) during feeding. In susceptible plants, BISP targets O. satvia RLCK185 (OsRLCK185; hereafter Os is used to denote O. satvia-related proteins or genes) to suppress basal defences. In resistant plants, the nucleotide-binding leucine-rich repeat receptor BPH14 directly binds BISP to activate HPR. Constitutive activation of Bph14-mediated immunity is detrimental to plant growth and productivity. The fine-tuning of Bph14-mediated HPR is achieved through direct binding of BISP and BPH14 to the selective autophagy cargo receptor OsNBR1, which delivers BISP to OsATG8 for degradation. Autophagy therefore controls BISP levels. In Bph14 plants, autophagy restores cellular homeostasis by downregulating HPR when feeding by brown planthoppers ceases. We identify an insect saliva protein sensed by a plant immune receptor and discover a three-way interaction system that offers opportunities for developing high-yield, insect-resistant crops.

Spontaneous FeIII/FeII redox cycling in single-atom catalysts: Conjugation effect and electron delocalization.

The mechanism of spontaneous FeIII/FeII redox cycling in iron-centered single-atom catalysts (I-SACs) is often overlooked. Consequently, pathways for continuous SO4 ·-/HO⋅ generation during peroxymonosulfate (PMS) activation by I-SACs remain unclear. Herein, the evolution of the iron center and ligand in I-SACs was comprehensively investigated. I-SACs could be considered as a coordination complex created by iron and a heteroatom N-doped carbonaceous ligand. The ligand-field theory could well explain the electronic behavior of the complex, whereby electrons delocalized by the conjugation effect of the ligand were confirmed to be responsible for the FeIII/FeII redox cycle. The possible pyridinic ligand in I-SACs was demonstrably weaker than the pyrrolic ligand in FeIII reduction due to its shielding effect on delocalized π orbitals by local lone-pair electrons. The results of this study significantly advance our understanding of the mechanism of spontaneous FeIII/FeII redox cycling and radical generation pathways in the I-SACs/PMS process.

Synergistic effect of hydrogen bonding and π-π interaction for enhanced adsorption of rhodamine B from water using corn straw biochar.

Dyes adsorption to biochar via hydrogen bonding, and π-π interaction alone have attracted much research attention, however, their synergism in adsorption mechanisms remains largely unnoticed. The synergistic effects of the hydrogen bonding and π-π interaction might improve the adsorption capacity and need more understanding to prepare high-capacity biochar. In this work, we evaluated the adsorption of various dyes on biochar prepared via the activation of potassium bicarbonate and urea (named BC-KN) to explore their synergistic effects. Batch experiments indicated the BC-KN showed a high adsorption capacity to rhodamine B at 4839.0 mg/g, azure B at 4477.7 mg/g, and methylene blue at 2223.0 mg/g, respectively. The mechanism of such significant adsorption was investigated by their comparative experiments, characterizations, and computational analyses. The computational analyses suggested that the synergism of the hydrogen bonding and π-π interaction improves the adsorption energies of BC-KN/RhB system from -10.35 kcal/mol to -20.49 kcal/mol. It can be concluded that the hydrogen bonding and π-π interaction can synergize to significantly improve the adsorption by increasing the π-electron density and shortening the distance of aromatic rings, thus dyes with H-donor show significantly better adsorption capacities. The insight of hydrogen bonding being the governing factor in the synergistic system will help produce high-capacity biochar in removing aromatic dyes and suggest a sustainable technology for the efficient decolorization of dye effluent to minimize its damage to the health and environment.

Bulked Segregant RNA Sequencing Revealed Difference Between Virulent and Avirulent Brown Planthoppers.

The brown planthopper (Nilaparvata lugens Stål, BPH) is one of the most devastating insect pests of rice (Oryza sativa L.), but BPH populations have varying degrees of virulence to rice varieties carrying different resistance genes. To help efforts to characterize these variations we applied bulked segregant RNA sequencing (BSR-seq) to identify differentially expressed genes (DEGs) and genetic loci associated with BPH virulence to YHY15 rice plants carrying the resistance gene Bph15. BPHs that are highly virulent or avirulent to these plants were selected from an F2 population to form two contrasting bulks, and BSR-seq identified 751 DEGs between the bulks. Genes associated with carbohydrate, amino acid and nucleotide metabolism, the endocrine system, and signal transduction were upregulated in the avirulent insects when they fed on these plants. The results also indicated that shifts in lipid metabolism and digestive system pathways were crucial for the virulent BPHs' adaptation to the resistant rice. We identified 24 single-nucleotide polymorphisms (SNPs) in 21 genes linked with BPH virulence. Possible roles of genes apparently linked to BPH virulence are discussed. Our results provide potentially valuable information for further studies of BPH virulence mechanisms and development of robust control strategies.

Necessity of rice resistance to planthoppers for OsEXO70H3 regulating SAMSL excretion and lignin deposition in cell walls.

The planthopper resistance gene Bph6 encodes a protein that interacts with OsEXO70E1. EXO70 forms a family of paralogues in rice. We hypothesized that the EXO70-dependent trafficking pathway affects the excretion of resistance-related proteins, thus impacting plant resistance to planthoppers. Here, we further explored the function of EXO70 members in rice resistance against planthoppers. We used the yeast two-hybrid and co-immunoprecipitation assays to identify proteins that play roles in Bph6-mediated planthopper resistance. The functions of the identified proteins were characterized via gene transformation, plant resistance evaluation, insect performance, cell excretion observation and cell wall component analyses. We discovered that another EXO70 member, OsEXO70H3, interacted with BPH6 and functioned in cell excretion and in Bph6-mediated planthopper resistance. We further found that OsEXO70H3 interacted with an S-adenosylmethionine synthetase-like protein (SAMSL) and increased the delivery of SAMSL outside the cells. The functional impairment of OsEXO70H3 and SAMSL reduced the lignin content and the planthopper resistance level of rice plants. Our results suggest that OsEXO70H3 may recruit SAMSL and help its excretion to the apoplast where it may be involved in lignin deposition in cell walls, thus contributing to rice resistance to planthoppers.

Rice functional genomics: decades' efforts and roads ahead.

Rice (Oryza sativa L.) is one of the most important crops in the world. Since the completion of rice reference genome sequences, tremendous progress has been achieved in understanding the molecular mechanisms on various rice traits and dissecting the underlying regulatory networks. In this review, we summarize the research progress of rice biology over past decades, including omics, genome-wide association study, phytohormone action, nutrient use, biotic and abiotic responses, photoperiodic flowering, and reproductive development (fertility and sterility). For the roads ahead, cutting-edge technologies such as new genomics methods, high-throughput phenotyping platforms, precise genome-editing tools, environmental microbiome optimization, and synthetic methods will further extend our understanding of unsolved molecular biology questions in rice, and facilitate integrations of the knowledge for agricultural applications.

Effects of pH on light absorption properties of water-soluble organic compounds in particulate matter emitted from typical emission sources.

Water-soluble organic compounds (WSOC) have a significant impact on aerosol radiative forcing and climate change, and there is considerable uncertainty in predicting and mitigating their climate and environmental effects. Here, the effects of pH on the light absorption properties of WSOC in particulate matter from different typical emission sources and ambient aerosols were systematically investigated using UV-vis spectrophotometer. pH (2-10) had an important impact on the light absorption properties of WSOC. The absorption, aromaticity, and the light absorption capacity of WSOC increased significantly with increasing pH for all samples. The difference absorbance spectra (∆absorbance) showed that the change of light absorption properties with pH was related to the deprotonate of carboxyl and phenolic groups resonating with aromatic and conjugated systems, with the most likely structures being carboxylic acids and phenols. Coal combustion and summer samples exhibited much higher susceptibility of light absorption properties to pH variation (increased by 27.0% and 65.9% relative to the pH 2 level, respectively). Absorption indices of almost all samples were significantly correlated with pH, indicating that the light absorption properties of WSOC may be quantitatively related to pH. The pH-dependent light absorption properties may have profound implications for evaluating the climate impacts of aerosol WSOC such as radiative forcing.

Achieving stably enhanced biological phosphorus removal from aerobic granular sludge system via phosphorus rich liquid extraction during anaerobic period.

In order to sustainably manage wastewater treatment plants and the environment, enhanced biological phosphorus (P) removal (EBPR) was proposed to achieve P recovery through extracting P-rich liquid (i.e., Phostrip) from the bottom of aerobic granular sludge (AGS)-based sequencing batch reactors (SBRs) under no mixing during the anaerobic phase. Results showed both tested bacterial AGS (BAGS) and algal-bacterial AGS (A-BAGS) systems stably produced low effluent P (<0.05 mg-P/L) with little impact on their organics and NH4+-N removals (>99%). The collected P-rich liquids (55-83 mg-P/L) from both systems showed great potential for P recovery of about 83.85 ± 0.57 % (BAGS) or 83.99 ± 0.77% (A-BAGS), which were contributed by the influent P (>95%) and P reserves in granules based on P balance analysis. This study suggests that the AGS-based SBRs coupling the Phostrip holds great potentials for P recovery profit and further reduction in energy consumption.

Evaluation of potassium ferrate activated biochar for the simultaneous adsorption of copper and sulfadiazine: Competitive versus synergistic.

Combined pollution caused by organic pollutants and heavy metals pose a significant challenge to the adsorption process. In this study, iron-modified biochar (Fe-BC) was prepared by using ferrate (K2FeO4) and wheat stalk as the precursors for the adsorption of copper (Cu2+) and sulfadiazine (SDZ), especially under combined pollution scenarios. Iron modification not only enlarged the surface area but also loaded iron oxide nanoparticles on biochar surface. Accordingly, Fe-BC exhibited better adsorption capability of Cu2+ and SDZ than the pristine biochar (BC). The corresponding maximum adsorption capacities of Fe-BC700 were 46.85 mg g-1 and 45.43 mg g-1 towards Cu2+ and SDZ, respectively. Interestingly, the adsorption was elevated in binary-pollutants system, suggesting a synergistic effect, which was probably attributed to the mutual bridging effects and complexation between Cu2+ and SDZ. The loaded iron oxide particles could serve as a physical barrier to separate the adsorptions of Cu2+ and SDZ and thus inhibited the competitive adsorption. Meanwhile, theoretical calculation demonstrated that sulfonamide group was the most probable binding site. Columns packed with Fe-BC700 showed better performances for Cu2+ and SDZ removal in binary system (635.73 BV for Cu2+ and 4846.26 BV for SDZ) than in single systems (571.60 BV for Cu2+ and 3572.06 BV for SDZ), which was consistent with batch adsorption experiments. These results demonstrated the potential application of Fe-BC700 for simultaneous adsorption of Cu2+ and SDZ and provided a cost-effective way for the remediation of organic and inorganic pollutants.

Mutual-activation between Zero-Valent iron and graphitic carbon for Cr(VI) Removal: Mechanism and inhibition of inherent Side-reaction.

The low reactivity of zero-valent iron (ZVI) usually limits its application for pollutant remediation. Therefore, a microscopic galvanic cell (mGC) with short-circuited cathode and anode was synthesized to intensify its galvanic corrosion. The prepared mGC exhibited 7.14 times higher Fe(II) release performance than ordinary nanoscale-ZVI (nZVI), rendering efficient Cr(VI) removal performance. Density functional theory (DFT) revealed mutual-activation of the cathode and anode due to close proximity, dramatically enhancing the galvanic corrosion of Fe(0) in mGC. The corrosion potential of mGC was measured as -0.77 V, which was 100 mV more negative than nZVI. The released electrons and surface-bond Fe(II) from anode in mGC was proved to be the dominant reductive species. More importantly, Cr(VI) reduction was slightly inhibited by hydroxyl radicals generated by a series of inherent side-reactions in the system, which could be well eliminated by low concentrations of 4-acetamido phenol. This study provides a promising strategy for ZVI activation, and sheds light on its environmental applications.

Source apportionment of VOCs in a typical medium-sized city in North China Plain and implications on control policy.

Characteristics of atmospheric VOCs (volatile organic compounds) have been extensively studied in megacities in China, however, they are scarcely investigated in medium/small-sized cities in North China Plain (NCP). A comprehensive research on possible sources of VOCs was conducted in a medium-sized city of NCP, from May to September 2019. A total of 143 canister samples of 8 sites in Xuchang city were collected, and 57 VOC species were detected. The average VOC concentrations were 42.6 ± 31.6 µg/m3, with 53.7 ± 31.0 µg/m3 and 32.1 ± 27. 8 µg/m3, in the morning and afternoon, respectively. Alkenes and aromatics contributed 80% of the total ozone formation potential (OFP). Aromatics accounted for more than 95% of secondary organic aerosol potential (SOAP). VOCs were dominated by the local emission with significant transport from the southeast direction. PMF analysis extracted 6 sources, which were combustion (33.1%), LPG usage (19.3%), vehicular exhaust & fuel evaporation (15.8%), solvent usage (15.2%), industrial (9.11%) and biogenic (7.51%), respectively and they contributed 33.4%, 17.6%, 12.9%, 18.6%, 9.28% and 8.22% to the OFP, respectively. Combustion and LPG usage were the dominant VOC sources; and combustion, solvent usage and LPG usage were the main sources of OFP in Xuchang city, which were different to megacities in China with a high contribution from vehicular exhaust, solvent usage and industry, suggesting specific control strategies on VOCs need to be implemented in medium-sized city such as Xuchang city.

Oxygen vacancies-enriched CoFe2O4 for peroxymonosulfate activation: The reactivity between radical-nonradical coupling way and bisphenol A.

Oxygen vacancies (OV) play a vital role in catalytic activity. Herein, a series of MOF-derived CoFe2O4 nanomaterials with OV tuned by a simple thermal aging strategy are prepared for peroxymonosulfate (PMS) activation. Remarkably, the stability, structural and catalytic properties show dependence on the annealing temperature. The abundant surface OV and functional groups on CoFe2O4 were verified as active sites to boost catalytic activity. Based on the density functional theory (DFT) calculations, (1 1 1), (2 2 2) and (4 2 2) planes exposed at higher temperatures facilitate catalytic performance, ascribed to the intense surface adsorption energy. The quenching and electron paramagnetic resonance (EPR) experiments indicate catalysis degradation is a radical-nonradical coupling process. The reactivity between reactive oxygen species (ROS) and bisphenol A and the radical-nonradical dual degradation pathways are systematically explored by combined DFT and HPLC-MS.