Insight into Core–Shell Dependent Anoxic Cr(VI) Removal with Fe@Fe₂O₃ Nanowires: Indispensable Role of Surface Bound Fe(II)

In this study, we investigated the anoxic Cr­(VI) removal with core–shell Fe@Fe₂O₃ nanowires. It was found the surface area normalized Cr­(VI) removal rate constants of Fe@Fe₂O₃ nanowires first increased with increasing the iron oxide shell thickness and then decreased, suggesting that Fe@Fe₂O₃ nanowires possessed an interesting core–shell structure dependent Cr­(VI) removal property. Meanwhile, the Cr­(VI) removal efficiency was positively correlated to the amount of surface bound Fe­(II). This result revealed that the core–shell structure dependent Cr­(VI) removal property of Fe@Fe₂O₃ nanowires was mainly attributed to the reduction of Cr­(VI) by the surface bound Fe­(II) besides the reduction of Cr­(VI) adsorbed on the iron oxide shell via the electrons transferred from the iron core. The indispensable role of surface bound Fe­(II) was confirmed by Tafel polarization and high-resolution X-ray photoelectron spectroscopic depth profiles analyses. X-ray diffraction patterns and scanning electron microscope images of the fresh and used Fe@Fe₂O₃ nanowires revealed the formation of Fe­(III)/Cr­(III)/Cr­(VI) composite oxides during the anoxic Cr­(VI) removal process. This study sheds a deep insight into the anoxic Cr­(VI) removal mechanism of core–shell Fe@Fe₂O₃ nanowires and also provides an efficient Cr­(VI) removal method

Protocatechuic Acid Promoted Alachlor Degradation in Fe(III)/H₂O₂ Fenton System

In this study, we demonstrate that protocatechuic acid (PCA) can significantly promote the alachlor degradation in the Fe­(III)/H₂O₂ Fenton oxidation system. It was found that the addition of protocatechuic acid could increase the alachlor degradation rate by 10 000 times in this Fenton oxidation system at pH = 3.6. This dramatic enhancement of alachlor degradation was attributed to the complexing and reduction abilities of protocatechuic ligand, which could form stable complexes with ferric ions to prevent their precipitation and also accelerate the Fe­(III)/Fe­(II) cycle to enhance the ·OH generation. Meanwhile, the Fe­(III)/PCA/H₂O₂ system could also work well at near natural pH even in the case of PCA concentration as low as 0.1 mmol/L. More importantly, both alachlor and PCA could be effectively mineralized in this Fenton system, suggesting the environmental benignity of PCA/Fe­(III)/H₂O₂ Fenton system. We employed gas chromatography–mass spectrometry to identify the degradation intermediates of alachlor and then proposed a possible alachlor degradation mechanism in this novel Fenton oxidation system. This study provides an efficient way to remove chloroacetanilide herbicides, and also shed new insight into the possible roles of widely existed phenolic acids in the conversion and the mineralization of organic contaminants in natural aquatic environment

Ascorbate Induced Facet Dependent Reductive Dissolution of Hematite Nanocrystals

The interaction between ascorbate and hematite facets was systematically investigated with attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, density functional theory (DFT) calculation, and kinetics model. Results of ATR-FTIR spectroscopy and DFT calculation suggested formation of nonprotonated inner-sphere bidentate mononuclear and monodentate mononuclear iron–ascorbate complexes on the hematite {001} and {012} facets, respectively. The estimated reductive dissolution rate constants at pH 5.0 were (4.04 ± 0.16) × 10^–4 and (1.59 ± 0.14) × 10^–4 min^–1 for hematite nanoplates and nanocubes, respectively, indicating that the bidentate mononuclear iron–ascorbate complexes on the {001} facets favored the hematite reductive dissolution process than the monodentate mononuclear iron–ascorbate counterparts on the {012} facets. These results also revealed that the hematite facet reduction with ascorbate was strongly dependent on the iron–ascorbate complexes formed on the hematite facets. This study provides new insights into the reductive interaction between ascorbate and hematite facets and also shed light on the environmental effects of hematite at the atomic level

Facet-Dependent Cr(VI) Adsorption of Hematite Nanocrystals

In this study, the adsorption process of Cr­(VI) on the hematite facets was systematically investigated with synchrotron-based Cr K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy, in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, density-functional theory calculation, and surface complexation models. Structural model fitting of EXAFS spectroscopy suggested that the interatomic distances of Cr–Fe were, respectively, 3.61 Å for the chromate coordinated hematite nanoplates with exposed {001} facets, 3.60 and 3.30 Å for the chromate coordinated hematite nanorods with exposed {001} and {110} facets, which were characteristic of inner-sphere complexation. In situ ATR-FTIR spectroscopy analysis confirmed the presence of two inner-sphere surface complexes with C_3ν and C_2ν symmetry, while the C_3ν and C_2ν species were assigned to monodentate and bidentate inner-sphere surface complexes with average Cr–Fe interatomic distances of 3.60 and 3.30 Å, respectively. On the basis of these experimental and theoretical results, we concluded that HCrO₄^– as dominated Cr­(VI) species was adsorbed on {001} and {110} facets in inner-sphere monodentate mononuclear and bidentate binuclear configurations, respectively. Moreover, the Cr­(VI) adsorption performance of hematite facets was strongly dependent on the chromate complexes formed on the hematite facets

Enhancing tomato resistance by exploring early defense events against Fusarium wilt disease

Abstract Studying plant early immunity, such as the unique immune mechanisms against pathogens, is an important field of research. Tomato wilt resulting from the infection by Fusarium oxysporum f. sp. lycopersici (Fol) is an important soil-borne vascular disease. In this study, we challenged tomato plants with Fol for a time-course RNA sequencing (RNA-seq) analysis. The result indicated that phenylpropanoid and flavonoid pathway genes were significantly enriched during the early invasion stage. Further study revealed that the flavonoids galangin and quercetin could effectively inhibit Fol growth and enhance wilt resistance in tomato. Moreover, the genes involved in plant-pathogen interactions, the MAPK signaling pathway, and plant hormone signal transduction were significantly enriched. These genes were also involved in plant pattern-triggered immunity (PTI) and effector-triggered immunity (ETI) signaling pathways. Strikingly, the transcription levels of pathogen-related protein 1 (SlPR1) were dramatically increased at 2 days post Fol inoculation, implying that SlPR1 is important in early immunity in tomato. SlPR1 does not have direct antifungal activity. Instead, its C-terminal peptide CAPE1 could activate root defense responses, such as the reactive oxygen species (ROS) burst, salicylic acid (SA)/jasmonic acid (JA) production, and defense-related gene expression, which collectively increased tomato resistance to Fol infection. In addition, CAPE1 could induce systemic acquired resistance (SAR). Application of CAPE1 onto tomato leaves induced local resistance to the pathogen Botrytis cinerea and systemic resistance to Fol infection. These results advanced our understanding for the early immunity against Fol in tomato and provide potential strategy for tomato disease control

Preparation of CdS Nanoparticles-TiO2 Nanorod Hererojunction and Their High-Performance Photocatalytic Activity

As a new and emerging technology, photocatalytic oxidation is widely used in the fields of sewage treatment and organic pollution control. In this study, CdS nanoparticles were prepared at room temperature by an innovative preparation method, then TiO2 nanorod–CdS nanoparticle heterojunction photocatalysts were prepared using the solvothermal method, with TiCl3 used as the precursor for TiO2 nanorods. This study mainly took advantage of the small size of the CdS nanoparticles in combination with TiO2 nanorods, and the resultant heterojunctions had large specific surface areas, thereby increasing the contact area between the catalysts and the contaminants. In addition, due to the lower band gap energy (2.4 eV) of CdS, the photo response range of the heterojunction photocatalysts was also increased. In an experimental study, through photocatalytic performance tests of the catalysts with different weight ratios, it was found that the TiO2(40%)@CdS composite had the best photocatalytic performance and the highest catalytic rate. BET, SEM, and other tests showed that the specific surface area of the TiO2(40%)@CdS composite was the largest. TiO2 nanorods and CdS particles were uniformly distributed in the composite, and the optical response range was extended to the visible light region

Endoplasmic reticulum and mitochondrial double-targeted NIR photosensitizer synergistically promote tumor cell death

The excessive production of reactive oxygen species (ROS) can damage the mitochondrial membrane and induce apoptosis, causing endoplasmic reticulum stress and triggering immunogenic cell death. Therefore, the combination of apoptosis and immunogenic death by the dual-targeted ROS generator has great potential to address inefficient cancer treatment. A near-infrared photosensitizer was developed for efficient ROS production and dual-targeted cancer treatment. Due to the modulation of electron structure, the reduced transition energy barrier affords TCy5-I-3F the highest efficiency to produce ROS. TCy5-I-3F has excellent mitochondrial and endoplasmic reticulum targeting ability, causing cell apoptosis and stress of the endoplasmic reticulum for destroying cancer cells. In the dual-targeted mode, high expression of GRP780, activation of heat shock protein (HSP70), the outflow of high mobility group protein B1, efflux of Calreticulin, and massive efflux of adenosine triphosphate are evaluated in the pharmacological experiments. In vivo experiments, the maturation of dendritic cells (DC, CD80+, CD86+), CD8+ T cells and CD3+ T cells also highlights the effectiveness. The tumors of mice treated with TCy5-I-3F and near-infrared (NIR) light are significantly inhibited. The multifunctional targeting design and corresponding mechanisms prove a new insight for exploring efficient photodynamic therapy drugs

Blood molecular markers associated with COVID-19 immunopathology and multi?organ damage

COVID-19 is characterised by dysregulated immune responses, metabolic dysfunction and adverse effects on the function of multiple organs. To understand host responses to COVID-19 pathophysiology, we combined transcriptomics, proteomics, and metabolomics to identify molecular markers in peripheral blood and plasma samples of 66 COVID-19 patients experiencing a range of disease severities and 17 healthy controls. A large number of expressed genes, proteins, metabolites and extracellular RNAs (exRNAs) exhibit strong associations with various clinical parameters. Multiple sets of tissue-specific proteins and exRNAs varied significantly in both mild and severe patients suggesting a potential impact on tissue function. Chronic activation of neutrophils, IFN-I signalling as well as a high level of inflammatory cytokines were observed in patients with severe disease progression. In contrast, COVID-19 patients experiencing milder disease symptoms showed robust T cell responses. Finally, we identified genes, proteins and exRNAs as potential biomarkers that might assist in predicting the prognosis of SARS-CoV-2 infection. These data refine our understanding of the pathophysiology and clinical progress of COVID-19