The heterogeneous Fenton reaction can generate highly reactive hydroxyl radicals（·OH）from reactions between recyclable solid catalysts and H2O2 at acidic or even circumneutral pH.Hence,it can ...effectively oxidize refractory organics in water or soils and has become a promising environmentally friendly treatment technology.Due to the complex reaction system,the mechanism behind heterogeneous Fenton reactions remains unresolved but fascinating,and is crucial for understanding Fenton chemistry and the development and application of efficient heterogeneous Fenton technologies.Iron-based materials usually possess high catalytic activity,low cost,negligible toxicity and easy recovery,and are a superior type of heterogeneous Fenton catalysts.Therefore,this article reviews the fundamental but important interfacial mechanisms of heterogeneous Fenton reactions catalyzed by iron-based materials..OH,hydroperoxyl radicals/superoxide anions（HO2./O2^-.）and high-valent iron are the three main types of reactive oxygen species（ROS）,with different oxidation reactivity and selectivity.Based on the mechanisms of ROS generation,the interfacial mechanisms of heterogeneous Fenton systems can be classified as the homogeneous Fenton mechanism induced by surface-leached iron,the heterogeneous catalysis mechanism,and the heterogeneous reaction-induced homogeneous mechanism.Different heterogeneous Fenton systems catalyzed by characteristic iron-based materials are comprehensively reviewed.Finally,related future research directions are also suggested.
• Ethylene (ET) and jasmonic acid (JA) play important roles in plant defenses against biotic stresses. Crosstalk between JA and ET has been well studied in mediating pathogen resistance, but its ...roles in piercing–sucking insect resistance are unclear.
• The brown planthopper (BPH; Nilaparvata lugens) is the most notorious piercing–sucking insect specific to rice (Oryza sativa) that severely affects yield. A genetic analysis revealed that OsEBF1 and OsEIL1, which are in the ET signaling pathway, positively and negatively regulated BPH resistance, respectively. Molecular and biochemical analyses revealed direct interactions between OsEBF1 and OsEIL1. OsEBF1, an E3 ligase, mediated the degradation of OsEIL1 through the ubiquitination pathway, indicating the negative regulation of the ET-signaling pathway in response to BPH infestation.
• An RNA sequencing analysis revealed that a JA biosynthetic pathway-related gene, OsLOX9, was downregulated significantly in the oseil1 mutant. Biochemical analyses, including yeast one-hybrid, dual luciferase, and electrophoretic mobility shift assay, confirmed the direct regulation of OsLOX9 by OsEIL1.
• This study revealed the synergistic and negative regulation of JA and ET pathways in response to piercing–sucking insect attack. The synergistic mechanism was realized by transcriptional regulation of OsEIL1 on OsLOX9. OsEIL1-OsLOX9 is a novel crosstalk site in these two phytohormone signaling pathways.
The dissolved organic matter (DOM) characterization in a full-scale landfill leachate treatment plant is of great importance for the design and operation of treatment processes. In this study, the ...long-term removal behaviors of DOM during landfill leachate treatment were explored using excitation emission matrix fluorescence spectroscopy (EEMs) coupled with parallel factor analysis (PARAFAC) and self-organizing map (SOM). Results indicated that the application of combining PARAFAC and SOM on EEMs analysis effectively characterized long-term removal behaviors of DOM during leachate treatment. The DOM in raw leachate was dominated by humic substances, while its composition exhibited significant seasonal differences. A large proportion of protein-like fluorescent dissolved organic matter (FDOM) and bulk DOM were removed within membrane bioreactor (MBR) system. Meanwhile the humic-like FDOM removal capacity in nanofiltration (NF) process was well comparable with those in the MBR system owing to the bio-recalcitrant nature of humic substances. The protein-like FDOM and bulk DOM were removed synchronously in both the process of MBR and NF. Moreover, samples distribution exhibited obvious differences among NF concentrate samples. In general, the performance of MBR-NF treatment for landfill leachate displayed reasonable stability in DOM removal irrespective of seasonal variations. This study enhanced our understanding of EEMs application in characterizing leachate-derived DOM composition and has potential implications for the associated monitoring investigations in engineered systems.
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•The long-term behaviors of DOM in landfill leachate treatment were investigated.•The coupling of PARAFAC and SOM was applied to a full-scale treatment plant.•The humic-like FDOM removal capacity of MBR was well comparable with those of NF.•The protein-like FDOM and bulk DOM were removed synchronously in MBR and NF.•MBR-NF system displayed reasonable stability regardless of seasonal variations.
The catalytic capacity of FMO-73 was due to the existence of MnO with electronic transfer from Mn (II) to Mn(III) or Mn (III) to Mn(IV). And the highest catalytic activity of FMO-46 was not only due ...to electronic transfer from Mn (II) to Mn(III) or Mn (III) to Mn(IV) but also the electronic transfer from lattice Fe(II) to Mn (III) or Mn(IV) for further accelerate the activation of PMS.
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•FMOs with various crystal structure were synthesized by sol–gel method.•Synergistic effects of iron and manganese remarkably enhance the catalytic activity.•Crystal structure has visible effects on reaction mechanism in FMS/FMO systems.•FMO-46 catalyst remained good stability and activity even after five recycles.
In this work, ferromanganese oxides (FMOs) synthesized with different Fe and Mn ratio using sol–gel method showed good activity in the activation of peroxymonosulfate (PMS) for tetracycline degradation. The structure and surface characterizations of the FMOs were measured using XRD, BET and XPS. The variation of the catalytic performance of FMOs in the degradation of TC was investigated with varied initial conditions. The FMO-46 structured as FeMnO3 with cubic structure could activate PMS efficiently due to the large surface area and surface Mn(III) sites. While the high catalytic activity of FMO-73 was attributed to the high percentage content of surface Fe(II) and Mn(II). The more vicinities of Fe and Mn exist on the surface of FMOs result in a better catalytic activity towards PMS and degradation of TC. The catalytic mechanism was elucidated by detecting the reactive oxidation species generated using ESR measurement and radical scavengers. It was found that Mn-oxides with Fe-regulated-surface active sites were expected to enhance the catalytic activity in the generation of SO4−. The experimental results demonstrated that SO4− had a higher contribution to degrade tetracycline in PMS/FMO system than OH. This study proves that surface regulated FMOs can efficiently activate PMS to degrade refractory organic pollutants as an environmentally friendly catalyst.
By simply changing the oxide support, the selectivity of a metal–oxide catalysts can be tuned. For the CO2 hydrogenation over PtCo bimetallic catalysts supported on different reducible oxides (CeO2, ...ZrO2, and TiO2), replacing a TiO2 support by CeO2 or ZrO2 selectively strengthens the binding of C,O‐bound and O‐bound species at the PtCo–oxide interface, leading to a different product selectivity. These results reveal mechanistic insights into how the catalytic performance of metal–oxide catalysts can be fine‐tuned.
By simply changing the oxide support, the selectivity of a metal–oxide catalyst can be tuned. For the hydrogenation of CO2 over PtCo bimetallic catalysts supported on different reducible oxides, replacing a TiO2 support by CeO2 or ZrO2 selectively strengthens the binding of C,O‐bound and O‐bound species at the PtCo–oxide interface, thereby leading to a different product selectivity.
The sorption of sodium silicate by synthetic magnetite (Fe
3O
4) at different pH conditions (pH 7–11) and initial silicate concentrations (
1
×
10
−3
and
10
×
10
−3
mol
L
−1
) was studied using in ...situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. The analysis of infrared spectra of sodium silicate in solution as well as adsorbed on magnetite nano-particles clearly showed the evolution of different silicate species depending on pH and silica concentration. The silicate concentration studied
(
10
×
10
−3
mol
L
−1
)
contained polymeric or condensed silicate species at lower pH as well as monomers at high pH, as evident from infrared spectra. Condensation of monomers resulted in an increased intensity of absorptions in the high frequency part (>1050 cm
−1) of the spectral region, which contains information about both silicate in solution and sorbed silicate viz. 1300 cm
−1–850 cm
−1. In the pH range studied, infrared spectra of sorbed silicate and sorbed silicate during desorption both indicated the presence of different types of surface complexes at the magnetite surface. The sorption mechanism proposed is in accordance with a ligand exchange reaction where both monodentate and bidentate complexes could exist at low surface loading level, the relative proportion of the complexes being due to both pH and concentration in solution. Oligomerization occurred on the magnetite surface at higher surface loading.
ATR-FTIR spectra of sorbed silicate on synthetic magnetite from 1 mM (left) and 10 mM (right) sodium silicate aqueous solutions.
Rising atmospheric CO2 is expected to have negative effects on the global environment from its role in climate change and ocean acidification. Utilizing CO2 as a feedstock to make valuable chemicals ...is potentially more desirable than sequestration. A substantial reduction of CO2 levels requires a large‐scale CO2 catalytic conversion process, which in turn requires the discovery of low‐cost catalysts. Results from the current study demonstrate the feasibility of using the non‐precious metal material molybdenum carbide (Mo2C) as an active and selective catalyst for CO2 conversion by H2.
Active, selective, and cheap: Mo2C and cobalt‐modified Mo2C were both shown to be effective catalysts for CO2 conversion by hydrogen in flow reactor experiments over powder catalysts. In‐situ XANES measurements verified that Mo2C can undergo an oxidation‐carburization cycle. Modifying Mo2C with small amounts of cobalt further improved catalytic performance.
Summary
Multi‐functional microRNAs (miRNAs) are emerging as key modulators of plant–pathogen interactions. Although the involvement of some miRNAs in plant–insect interactions has been revealed, the ...underlying mechanisms are still elusive. The brown planthopper (BPH) is the most notorious rice (Oryza sativa)‐specific insect that causes severe yield losses each year and requires urgent biological control. To reveal the miRNAs involved in rice–BPH interactions, we performed miRNA sequencing and identified BPH‐responsive OsmiR396. Sequestering OsmiR396 by overexpressing target mimicry (MIM396) in three genetic backgrounds indicated that OsmiR396 negatively regulated BPH resistance. Overexpression of one BPH‐responsive target gene of OsmiR396, growth regulating factor 8 (OsGRF8), showed resistance to BPH. Furthermore, the flavonoid contents increased in both the OsmiR396‐sequestered and the OsGRF8 overexpressing plants. By analysing 39 natural rice varieties, the elevated flavonoid contents were found to correlate with enhanced BPH resistance. Artificial applications of flavonoids to wild type (WT) plants also increased resistance to BPH. A BPH‐responsive flavanone 3‐hydroxylase (OsF3H) gene in the flavonoid biosynthetic pathway was proved to be directly regulated by OsGRF8. A genetic functional analysis of OsF3H revealed its positive role in mediating both the flavonoid contents and BPH resistance. And analysis of the genetic correlation between OsmiR396 and OsF3H showed that down‐regulation of OsF3H complemented the BPH resistance characteristic and simultaneously decreased the flavonoid contents of the MIM396 plants. Thus, we revealed a new BPH resistance mechanism mediated by the OsmiR396–OsGRF8–OsF3H–flavonoid pathway. Our study suggests potential applications of miRNAs in BPH resistance breeding.
miR156f modulates rice plant architecture by direct binding to the OsGH3.8 promoter through its target OsSPL7, to allow crosstalk with the auxin signaling pathway.
Abstract
Tiller number and plant ...height are two of the main features of plant architecture that directly influence rice yield. Auxin and miR156, an extensively studied small RNA (smRNA), are both broadly involved in plant development and physiology, suggesting a possible relationship between the two. In this study, we identified a rice T-DNA insertion cluster and dwarf (cd) mutant that has an increased tiller number and reduced plant height. The T-DNA insertion was in close proximity to the miR156f gene and was associated with its up-regulation. Plants overexpressing miR156f resembled the cd mutant. In contrast, plants overexpressing an miR156f target mimic (MIM156fOE) had a reduced tiller number and increased height. Genetic analysis showed that OsSPL7 is a target of miR156f that regulates plant architecture. Plants overexpressing OsSPL7 had a reduced tiller number, while OsSPL7 RNAi plants had an increased tiller number and a reduced height. We also found that OsSPL7 binds directly to the OsGH3.8 promoter to regulate its transcription. Overexpression of OsGH3.8 and OsGH3.8 RNAi partially complemented the MIM156fOE and cd mutant phenotypes, respectively. Our combined data show that the miR156f-OsSPL7-OsGH3.8 pathway regulates tiller number and plant height in rice, and this pathway may allow crosstalk between miR156 and auxin.
This meta-analysis of overweight and obesity (ow/ob) among children and adolescents in China from 1991 to 2015 provides a reference for promoting the healthy development of children and adolescents. ...The studies were retrieved from the China National Knowledge Infrastructure, Wanfang, and PubMed databases for the period from January 1991 to January 2018. The data were combined and analyzed, and the combined effect magnitude odds ratio and the 95% confidence interval were calculated. Publication bias was determined using Stata/SE12.0. We found that (1) the prevalence of ow/ob increased from 5.0% and 1.7% in 1991-1995 to 11.7% and 6.8% in 2011-2015, respectively, and the overweight rate was the greatest in 2006-2010; (2) from 1991 to 2015, the prevalence of ow/ob was greater in urban areas than in rural areas; (3) compared with girls, boys were more likely to be ow/ob; and (4) the prevalence rates of ow and ob were greater in infancy than in other growth stages, with values of 11.7% and 7.0%, respectively. The prevalence of ow/ob among Chinese children and adolescents showed significant differences based on region, sex, and age. An overall upward trend was observed that decreased slightly from 2011 to 2015.
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