The heterogeneous Fenton reaction can generate highly reactive hydroxyl radicals (UOH) from reactions between recyclable solid catalysts and H 2 O 2 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
The sorption of sodium silicate by synthetic magnetite (Fe 3 O 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.
Summary Multi‐functional micro RNA s (mi RNA s) are emerging as key modulators of plant–pathogen interactions. Although the involvement of some mi RNA s 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 mi RNA s involved in rice– BPH interactions, we performed mi RNA sequencing and identified BPH ‐responsive OsmiR396. Sequestering OsmiR396 by overexpressing target mimicry ( MIM 396) in three genetic backgrounds indicated that OsmiR396 negatively regulated BPH resistance. Overexpression of one BPH ‐responsive target gene of OsmiR396, growth regulating factor 8 ( Os GRF 8 ), showed resistance to BPH . Furthermore, the flavonoid contents increased in both the OsmiR396‐sequestered and the Os GRF 8 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 Os GRF 8. 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 MIM 396 plants. Thus, we revealed a new BPH resistance mechanism mediated by the OsmiR396–Os GRF 8–OsF3H–flavonoid pathway. Our study suggests potential applications of mi RNA s 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.
a b s t r a c tAttenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was used to monitor the in situ sorption of sodium metasilicate from aqueous solution onto synthesized magnetite and maghemite particles in the pH range of 10.8-7.0 using silicate concentrations between 0.1 mM and 5 mM. The spectral data showed that both pH and silicate concentration had great influence on the interfacial reaction between soluble silicate and the iron oxide surfaces, regarding the amount adsorbed per unit mass of iron oxide and the surface species formed. A pH dependent sorption of silicate on iron oxides was observed, implying that a maximum sorption took place in the pH range of 9.5-7.0. All experiments showed a fast initial increase in the absorption intensity followed by a slower sorption stage which was strongly dependent on the concentration of silicate in solution and the pH value. The amount of sorption onto magnetite was 3-5 times larger than onto maghemite, but there was no significant difference in the line shape of corresponding absorption bands. At pH 8.5 and low concentration (≤0.1 mM), the silicate monomers dominate in solution and on the iron oxide surface also monomeric species were dominating as evident from the infrared band at 950 cm −1 . However, at higher concentration (0.4-5.0 mM), the dominating absorption band at about 1000 cm −1 shifted to higher frequency during the sorption indicating that oligomeric surface silicate species were formed on the iron oxide surface. Desorption of silicate from the surface of the iron oxides was easier to accomplish at low silicate concentration, whilst the highest concentration showed a comparatively low relative amount of desorbed silicate, suggesting that polymerized species had a stronger affinity for the iron oxide surface as compared to monomeric species.
Summary 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.
BackgroundDue to the extensive use of phosphates in industry, agriculture and households, the phosphate - γ-alumina interactions are important for understanding its detrimental contribution to eutrophication in lakes and rivers. In situ Fourier transform infrared (FTIR) spectroscopy can provide more detailed information on the adsorbate-adsorbent interaction and the formation of hydrogen bonds.ResultsIn situ ATR-FTIR spectroscopy was used to identify phosphate complexes adsorbed within the three-dimensional network of mesoporous γ-alumina at pH 4.1 and 9.0. The integrated intensity between 850 cm-1 and 1250 cm-1 was used as a relative measure of the amount of adsorbed phosphate. The integrated intensity proved to be about 3 times higher at pH 4.1 as compared with the corresponding intensity at pH 9.0. The adsorption of phosphate at the two pH conditions could be well described by the Langmuir adsorption isotherm at low concentrations and the empirical Freundlich adsorption isotherm for the whole concentration range, viz. 5 – 2000 μM.ConclusionsFrom the band shape of infrared spectra at pH 4.1 and pH 9.0, it was proposed that the symmetry of the inner-sphere surface complex formed between phosphate and γ-alumina was C1 at the lower pH value, whilst the higher value (9.0) implied a surface complex with C2v or C1 symmetry. The difference in adsorbed amount of phosphate at the two pH values was ascribed to the reduced fraction of ≡ AlOH2+ surface sites and the increased fraction of ≡ AlO- sites upon increasing pH from 4 to 9.
The reaction of N-diphenylphosphinoyl imines 1 with [3-(trimethylsilyl)allyl]dimethylsulfonium bromide (5) in the presence of NaH at room temperature predominantly gave trans-vinylaziridines 4. On the other hand, cis-vinylaziridines 4 were the main products when the preformed ylide prepared from the reaction of [3-(trimethylsilyl)allyl]diphenylsulfonium perchlorate (6) was reacted with the same imines 1 at low temperature. trans-Aziridines were also obtained when imines 1 and sulfinimines 9 were reacted with N,N-dimethylacetamide-2-dimethylsulfonium bromide (7) in the presence of a base, respectively. A mechanistic study showed that the stereochemistry of these reactions was controlled by the reactivity of the imines and ylides. A higher reactivity of imines and ylides favors the formation of cis-aziridines, whereas a lower reactivity leads to trans-products.
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