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Introduction: The immunological characteristics that could protect children with coronavirus disease 2019 (COVID-19) from severe or fatal illnesses have not been fully understood yet. Methods: Here, we performed single-cell RNA sequencing (scRNA-seq) analysis on peripheral blood samples of 15 children (8 with COVID-19) and compared them to 18 adults (13 with COVID-19). Results: The child-adult integrated single cell data indicated that children with the disease presented a restrained response to type I interferon in most of the major immune cell types, along with suppression of upstream interferon regulatory factor and toll-like receptor expression in monocytes, which was confirmed by in vitro interferon stimulation assays. Unlike adult patients, children with COVID-19 showed lower frequencies of activated proinflammatory CD14+ monocytes, possibly explaining the rareness of cytokine storm in them. Notably, natural killer (NK) cells in pediatric patients displayed potent cytotoxicity with a rich expression of cytotoxic molecules and upregulated cytotoxic pathways, whereas the cellular senescence, along with the Notch signaling pathway, was significantly downregulated in NK cells, all suggesting more robust cytotoxicity in NK cells of children than adult patients that was further confirmed by CD107a degranulation assays. Lastly, a modest adaptive immune response was evident with more naïve T cells but less activated and proliferated T cells while less naïve B cells but more activated B cells in children over adult patients. Conclusion: Conclusively, this preliminary study revealed distinct cell frequency and activation status of major immune cell types, particularly more robust NK cell cytotoxicity in PBMC that might help protect children from severe COVID-19.
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COVID-19 , Células Matadoras Naturais , SARS-CoV-2 , Análise de Célula Única , Humanos , COVID-19/imunologia , Criança , Adulto , SARS-CoV-2/imunologia , Masculino , Feminino , Células Matadoras Naturais/imunologia , Pré-Escolar , Adolescente , Monócitos/imunologia , Monócitos/metabolismo , Pessoa de Meia-Idade , Imunidade Adaptativa , Citotoxicidade Imunológica , Adulto Jovem , Interferon Tipo I/imunologia , Senescência Celular/imunologiaRESUMO
Groundwater contamination by nitrates presents significant risks to both human health and the environment. In groundwater characterized as oligotrophic-low in organic carbon, but abundant in carbonate and phosphate-chemolithoautotrophic bacteria, including nitrate-reducing Fe(II)-oxidizing bacteria (NRFeOB), play a vital role in denitrification. The chemoautotrophic nitrate reduction is sensitive to environmental factors, including widespread iron oxides like hematite in nature. However, the specific mechanisms of this influence remain unclear. We examined the mechanism of how hematite impacts autotrophic nitrate reduction in a model NRFeOB community known as culture KS. We found that hematite enhances the rate of autotrophic nitrate reduction by promoting Fe(II) oxidation. Mössbauer spectroscopy detected a significant amount of adsorbed Fe(II) when hematite was present, leading to a reduction in dissolved ferrous iron. In conjunction with XRD data, it can be inferred that the formation of vivianite decreased, thereby increasing the Fe(II) activity in the reaction system. Within the culture KS bacterial consortium, hematite fosters the proliferation of autotrophic microorganisms, specifically Gallionellaceae, and amplifies the presence of denitrifying microbes, notably Rhodanobacter. This dual enhancement improves Fe(II) utilization and nitrate reduction capabilities. Our findings highlight intricate interactions between hematite and a model NRFeOB community, offering insights into groundwater nitrate removal mechanisms and the ecological strategies of autotrophic bacteria in mineral-rich environments.
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Processos Autotróficos , Compostos Férricos , Água Subterrânea , Nitratos , Fosfatos , Compostos Férricos/metabolismo , Água Subterrânea/química , Água Subterrânea/microbiologia , Fosfatos/metabolismo , Carbonatos , Desnitrificação , Poluentes Químicos da Água/metabolismo , Oxirredução , Ferro/metabolismo , Bactérias/metabolismo , Compostos Ferrosos/metabolismoRESUMO
Background: Castleman disease (CD) is a rare lymphoproliferative disease. Idiopathic multicentric CD (iMCD), representing a distinct entity in CD, is partly attributed to autoimmune abnormalities and the hyperplastic process in iMCD involving the immune system. Consequently, iMCD presents a range of overlapping manifestations with connective tissue disorder (CTD), resulting in an inability to tell whether they coexist or imitate each other. Reports of CD combined with CTD are rare, more cases are needed to be summarized and analyzed to improve the efficiency of diagnosis and accelerate the development of novel treatments. Case Description: A male pediatric patient was diagnosed with CTD in October 2019 and had been receiving regular treatment with tocilizumab and glucocorticoid or methotrexate since April 2020. He was further diagnosed with iMCD of the hyaline vascular subtype according to biopsy-proven histopathological features and imaging-proven multiple involvement in August 2021. He received 4 doses of rituximab and then a combination of thalidomide and dexamethasone for about 1 year. His clinical symptoms were well controlled throughout the disease for a long period, but inflammatory markers were repeatedly elevated, which eventually turned normal after switching to siltuximab from July 2023, although a significant elevation of interleukin-6 occurred. Conclusions: We reported a pediatric case diagnosed as CTD and iMCD, whose inflammation finally be well controlled by siltuximab. Hopefully, our work will add insight into such rare situations and it is undoubtedly that the pathophysiological mechanism of CD and CTD coexistence and prediction models of treatment response remains to be explored to facilitate the clinical management and optimal treatment.
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Labile organic matter (OM) immobilized by secondary iron (Fe) minerals from chemodenitrification may be an effective way to immobilize organic carbon (OC). However, the underlying mechanisms of coupled chemodenitrification and OC sequestration are poorly understood. Here, OM immobilization by secondary Fe minerals from chemodenitrification was investigated at different C/Fe ratios. Kinetics of Fe(II) oxidation and nitrite reduction rates decreased with increasing C/Fe ratios. Despite efficient sequestration, the immobilization efficiency of OM by secondary minerals varied with the C/Fe ratios. Higher C/Fe ratios were conducive to the formation of ferrihydrite and lepidocrocite, with defects and nanopores. Three contributions, including inner-core Fe-O and edge- and corner-shared Fe-Fe interactions, constituted the local coordination environment of mineral-organic composites. Microscopic analysis at the molecular scale uncovered that labile OM was more likely to combine with secondary minerals with poor crystallinity to enhance its stability, and OM distributed within nanopores and defects had a higher oxidation state. After chemodenitrification, high molecular weight substances and substances high in unsaturation or O/C ratios including phenols, polycyclic aromatics, and carboxylic compounds exhibited a stronger affinity to Fe minerals in the treatments with lower C/Fe ratios. Collectively, labile OM immobilization can occur during chemodenitrification. The findings on OM sequestration coupled with chemodenitrification have significant implications for understanding the long-term cycling of Fe, C, and N, providing a potential strategy for OM immobilization in anoxic soils and sediments.
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Ferro , Minerais , Minerais/química , Ferro/química , Oxirredução , Carbono/química , CinéticaRESUMO
Elevated bone resorption and diminished bone formation have been recognized as the primary features of glucocorticoid-associated skeletal disorders. However, the direct effects of excess glucocorticoids on bone turnover remain unclear. Here, we explored the outcomes of exogenous glucocorticoid treatment on bone loss and delayed fracture healing in mice and found that reduced bone turnover was a dominant feature, resulting in a net loss of bone mass. The primary effect of glucocorticoids on osteogenic differentiation was not inhibitory; instead, they cooperated with macrophages to facilitate osteogenesis. Impaired local nutrient status - notably, obstructed fatty acid transportation - was a key factor contributing to glucocorticoid-induced impairment of bone turnover in vivo. Furthermore, fatty acid oxidation in macrophages fueled the ability of glucocorticoid-liganded receptors to enter the nucleus and then promoted the expression of BMP2, a key cytokine that facilitates osteogenesis. Metabolic reprogramming by localized fatty acid delivery partly rescued glucocorticoid-induced pathology by restoring a healthier immune-metabolic milieu. These data provide insights into the multifactorial metabolic mechanisms by which glucocorticoids generate skeletal disorders, thus suggesting possible therapeutic avenues.
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Remodelação Óssea , Glucocorticoides , Osteogênese , Animais , Camundongos , Glucocorticoides/farmacologia , Osteogênese/efeitos dos fármacos , Remodelação Óssea/efeitos dos fármacos , Macrófagos/metabolismo , Macrófagos/imunologia , Macrófagos/efeitos dos fármacos , Proteína Morfogenética Óssea 2/metabolismo , Proteína Morfogenética Óssea 2/genética , Ácidos Graxos/metabolismo , Osso e Ossos/metabolismo , Osso e Ossos/efeitos dos fármacos , Osso e Ossos/imunologia , Microambiente Celular/efeitos dos fármacosRESUMO
Mercury (Hg) contamination in paddy soils poses a health risk to rice consumers and the environmental behavior of Hg determines its toxicity. Thus, the variations of Hg speciation are worthy of exploring. In this study, microcosm and pot experiments were conducted to elucidate Hg transformation, methylation, bioaccumulation, and risk coupled with biogeochemical cycling of key elements in a Hg-polluted alkaline paddy soil. In microcosm and pot experiments, organic- and sulfide-bound and residual Hg accounted for more than 98% of total Hg, and total contents of dissolved, exchangeable, specifically adsorbed, and fulvic acid-bound Hg were less than 2% of total Hg, indicating a low mobility and environmental risk of Hg. The decrease of pH aroused from Fe(III), SO42-, and NO3- reduction promoted Hg mobility, whereas the increase of pH caused by Fe(II), S2-, and NH4+ oxidation reduced available Hg contents. Moreover, Fe-bearing minerals reduction and organic matter consumption promoted Hg mobility, whereas the produced HgS and Fe(II) oxidation increased Hg stability. During flooding, a fraction of inorganic Hg (IHg) could be transported into methylmercury (MeHg), and during drainage, MeHg would be converted back into IHg. After planting rice in an alkaline paddy soil, available Hg was below 0.3 mg kg-1. During rice growth, a portion of available Hg transport from paddy soil to rice, promoting Hg accumulation in rice grains. After rice ripening, IHg levels in rice tissues followed the trend: root > leaf > stem > grain, and IHg content in rice grain exceed 0.02 mg kg-1, but MeHg content in rice grain meets daily intake limit (37.45 µg kg-1). These results provide a basis for assessing the environmental risks and developing remediation strategies for Hg-contaminated redox-changing paddy fields as well as guaranteeing the safe production of rice grains.
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Mercúrio , Compostos de Metilmercúrio , Oryza , Poluentes do Solo , Compostos Férricos , Monitoramento Ambiental , Poluentes do Solo/análise , Mercúrio/análise , Compostos de Metilmercúrio/química , Solo/química , Oryza/química , Compostos FerrososRESUMO
Zero-valent iron (ZVI) is a promising material for the remediation of Cd-contaminated paddy soils. However, the effects of ZVI added during flooding or drainage processes on cadmium (Cd) retention remain unclear. Herein, Cd-contaminated paddy soil was incubated for 40 days of flooding and then for 15 days of drainage, and the underlying mechanisms of Cd immobilization coupled with Fe/S/N redox processes were investigated. The addition of ZVI to the flooding process was more conducive to Cd immobilization. Less potential available Cd was detected by adding ZVI before flooding, which may be due to the increase in paddy soil pH and newly formed secondary Fe minerals. Moreover, the reductive dissolution of Fe minerals promoted the release of soil colloids, thereby increasing significantly the surface sites and causing Cd immobilization. Additionally, the addition of ZVI before flooding played a vital role in Cd retention after soil drainage. In contrast, the addition of ZVI in the drainage phase was not conducive to Cd retention, which might be due to the rapid decrease in soil pH that inhibited Cd adsorption and further immobilization on soil surfaces. The findings of this study demonstrated that Cd availability in paddy soil was largely reduced by adding ZVI during the flooding period and provide a novel insight into the mechanisms of ZVI remediation in Cd-contaminated paddy soils.
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Oryza , Poluentes do Solo , Cádmio/análise , Ferro , Solo , Poluentes do Solo/análise , MineraisRESUMO
Environmental photocatalysis is a promising technology for treating antibiotics in wastewater. In this study, a supercritical carbonization method was developed to synthesize a single-atom photocatalyst with a high loading of Ni (above 5 wt.%) anchored on a carbon-nitrogen-silicate substrate for the efficient photodegradation of a ubiquitous environmental contaminant of tetracycline (TC). The photocatalyst was prepared from an easily obtained metal-biopolymer-inorganic supramolecular hydrogel, followed by supercritical drying and carbonization treatment. The low-temperature (300°C) supercritical ethanol treatment prevents the excessive structural degradation of hydrogel and greatly reduces the metal clustering and aggregation, which contributed to the high Ni loading. Atomic characterizations confirmed that Ni was present at isolated sites and stabilized by Ni-N and Ni-O bonds in a Ni-(N/O)6C/SiC configuration. A 5% Ni-C-Si catalyst, which performed the best among the studied catalysts, exhibited a wide visible light response with a narrow bandgap of 1.45 eV that could efficiently and repeatedly catalyze the oxidation of TC with a conversion rate of almost 100% within 40 min. The reactive species trapping experiments and electron spin resonance (ESR) tests demonstrated that the h+, and ·O2- were mainly responsible for TC degradation. The TC degradation mechanism and possible reaction pathways were provided also. Overall, this study proposed a novel strategy to synthesize a high metal loading single-atom photocatalyst that can efficiently remove TC with high concentrations, and this strategy might be extended for synthesis of other carbon-based single-atom catalysts with valuable properties.
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Compostos Heterocíclicos , Níquel , Fotólise , Temperatura , Tetraciclina , Antibacterianos , Carbono , Catálise , Hidrogéis , LuzRESUMO
Castleman disease (CD) is a rare lymphoproliferative disorder of undetermined etiology. Unicentric CD (UCD) and multicentric CD (MCD) are two phenotypes of CD diagnosed by the histopathology of lymph nodes. We attempted to describe a pediatric CD cohort to optimize the management of this disease. We reviewed the medical records of pediatric patients diagnosed with CD between April, 2004, and October, 2022, at the Children's Hospital of Fudan University. Prognosis information was collected in January, 2023, by telephone inquiry. Twenty-two patients with UCD and 2 patients with MCD were identified, all with hyaline vascular (HV) type. The median ages at diagnosis were 10.75 years (IQR 8, 12.81) for UCD and 14.42 years (IQR 13.42, 15.42) for MCD. The most common lesion location of UCD was the neck (9/22, 40.91%) and abdomen (9/22, 40.91%). Systematic symptoms occurred on 10/22 (45.45%) patients with UCD and 1/2 (50%) patients with MCD, and abnormal laboratory indexes were detected in both. Resection and biopsy were performed on all patients. One out of two patients with MCD also received rituximab for upfront therapy. After a median of 4 years (IQR 1.5, 6) of follow-up time, the overall survival was 100% and the complete remission rate in UCD was 63%. There was no relapse or progression. CONCLUSIONS: Our series demonstrated that HV-UCD was the most common type in children. Resection and biopsy were used for both deterministic diagnoses and treatments. Despite the high possibility to develop systematic inflammation, children with CD showed promising outcomes. WHAT IS KNOWN: ⢠Castleman disease is a rare lymphoproliferative disorder with limited cohort studies, especially in pediatrics. ⢠The ubiquity of delayed confirmations and misdiagnoses points to a lack of knowledge about etiology and characteristics, which is a prerequisite for novel therapeutics. WHAT IS NEW: ⢠We retrospectively reviewed and analyzed the clinical and pathological symptoms, laboratory and imaging features, and treatment outcomes of a Chinese pediatric cohort with Castleman disease. ⢠Our work may improve the recognition and optimize the management of this rare disease in children.
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Hiperplasia do Linfonodo Gigante , Humanos , Criança , Hiperplasia do Linfonodo Gigante/diagnóstico , Hiperplasia do Linfonodo Gigante/terapia , Hiperplasia do Linfonodo Gigante/patologia , Estudos Retrospectivos , Linfonodos/patologia , Resultado do Tratamento , ChinaRESUMO
Peucedanum praeruptorum Dunn extract (PPDE) is a well-known treatment used in traditional Chinese medicines, where it is most commonly used to treat coughs and symptoms such as headaches and fever. In the present study, the antioxidant capacity of PPDE in vitro was determined by scavenging experiments using DPPH, ABTS+·, ·OH, and ·O2-. The cell survival rate was determined by MTT assay. The MDA, SOD, CAT, GSH, and GSH-Px content were determined by colorimetry assays. The expression levels of antioxidant genes SOD, CAT, GSH, and GSH-Px were assessed by reverse transcription-quantitative PCR. HPLC was used to identify the PPDE components. The results suggested that PPDE had scavenging effects on DPPH, ABTS, hydroxyl, and superoxide anion radicals in a concentration-dependent manner; H2O2 treatment resulted in oxidative stress in LLC-PK1 cells, and the degree of injury of LLC-PK1 cells following PPDE treatment was improved, which was positively correlated with its concentration. Peucedanum praeruptorum Dunn extract treatment reduced the content of MDA and increased the content of CAT, SOD1, GSH, and GSH-Px. The mRNA expression levels of antioxidant genes detected by quantitative PCR were consistent with changes in CAT, SOD, GSS, and GSH-Px. Additionally, the trend in CAT, SOD1, GSH, and GSS protein expression levels was also consistent at the mRNA level. PPDE was found to consist of isochlorogenic acid C, myricetin, baicalin, luteolin, and kaempferol. Therefore, PPDE, which was formed of products derived from natural substances, functioned in the inhibition of oxidative damage. The present study aimed to obtain a better understanding of the traditional Chinese medicine Peucedanum praeruptorum Dunn and preliminarily elucidate its antioxidant mechanism at the cellular level. Further animal or human experiments are required to verify the antioxidant effects of PPDE for further development and utilization.
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Microbially mediated nitrate reduction coupled with Fe(II) oxidation (NRFO) plays an important role in the Fe/N interactions in pH-neutral anoxic environments. However, the relative contributions of the chemical and microbial processes to NRFO are still unclear. In this study, N-O isotope fractionation during NRFO was investigated. The ratios of O and N isotope enrichment factors (18ε:15ε)-NO3- indicated that the main nitrate reductase functioning in Acidovorax sp. strain BoFeN1 was membrane-bound dissimilatory nitrate reductase (Nar). N-O isotope fractionation during chemodenitrification [Fe(II) + NO2-], microbial nitrite reduction (cells + NO2-), and the coupled process [cells + NO2- + Fe(II)] was explored. The ratios of (18ε:15ε)-NO2- were 0.58 ± 0.05 during chemodenitrification and -0.41 ± 0.11 during microbial nitrite reduction, indicating that N-O isotopes can be used to distinguish chemical from biological reactions. The (18ε:15ε)-NO2- of 0.70 ± 0.05 during the coupled process was close to that obtained for chemodenitrification, indicating that chemodenitrification played a more important role than biological reactions during the coupled process. The results of kinetic modeling showed that the relative contribution of chemodenitrification was 99.3% during the coupled process, which was consistent with that of isotope fractionation. This study provides a better understanding of chemical and biological mechanisms of NRFO using N-O isotopes and kinetic modeling.
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Comamonadaceae , Nitratos , Nitritos , Dióxido de Nitrogênio , Oxirredução , Compostos Orgânicos , Isótopos , Compostos FerrososRESUMO
Paddy fields located around estuaries suffer from seawater intrusion, and how and to what extent salinity levels influence Cd accumulation in rice grains is still unclear. Pot experiments were carried out by cultivating rice under alternating flooding and drainage conditions with different salinity levels (0.2, 0.6 and 1.8). The Cd availability was greatly enhanced at 1.8 salinity due to the competition for binding sites by cations and the formation of Cd complexation with anions, which also contributed to Cd uptake by rice roots. The soil Cd fractions were investigated and found that the Cd availability significantly decreased during flooding stage, while it rapidly increased after soil drainage. During drainage stage, Cd availability was greatly enhanced at 1.8 salinity mainly attributed to the formation of CdCln2-n. The kinetic model was established to quantitatively evaluate Cd transformation, and it found that the release of Cd from organic matter and Fe-Mn oxides was greatly enhanced at 1.8 salinity. The results of pot experiments showed that there was a significant increase in Cd content in rice roots and grains in the treatment of 1.8 salinity, because the increasing salinity induced an increase in Cd availability and upregulation of key genes regulating Cd uptake in rice roots. Our findings elucidated the key mechanisms by which high salinity enhanced Cd accumulation in rice grains, and more attention should be given to the food safety of rice cultivated around estuaries.
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Oryza , Poluentes do Solo , Cádmio/metabolismo , Oryza/metabolismo , Poluentes do Solo/metabolismo , Solo/química , Óxidos/metabolismoRESUMO
Lead (Pb) can enter soil environment during flooding events such as surface runoff and intensive rainfall. However, the key transformation processes of exogenous Pb during anoxic-oxic alteration remain poorly understood particularly how phosphorus and organic matter contribute to Pb immobilization/release. Here, a kinetic model was established to investigate the Pb transformation in an acidic soil with two levels of Pb contamination under alternating anoxic-oxic conditions, based on the results of seven-step sequential extraction, dissolved organic carbon, sulfate, iron, phosphorus, and surface sites. Results showed that the potentially available Pb, including dissolved, exchangeable, and specifically adsorbed fractions, was gradually transferred to the fulvic complex, Fe-Mn oxides bound, and sulfides bound Pb after 40-day incubation under anoxic conditions, while the fulvic complex Pb further increased after 20-day incubation under oxic conditions. The concentration of phosphorus that was extracted by 0.5 M HCl or 0.03 M NH4F in 0.025 M HCl increased under anoxic conditions and decreased under oxic conditions. When Pb-binding to phosphorus is considered during kinetic modeling, the simulated results of Pb transformation suggest that phosphorus is more important than organic matter for Pb immobilization under anoxic conditions, while the phosphates, Fe-Mn oxides, and sulfides immobilized Pb is slowly released and then complexed by fulvic acids during the re-immobilization of dissolved organic matter in soil under oxic conditions. The model established with low Pb level has been successfully applied to describe the Pb transformation with high Pb level. This study provides a comprehensive understanding of the roles of phosphorus and organic matter in controlling Pb transformation in soil from kinetic modeling.
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Poluentes do Solo , Solo , Cinética , Fósforo , Chumbo , Óxidos , Poluentes do Solo/análise , OxirreduçãoRESUMO
Arsenic (As) from mine wastewater is a significant source for acidic paddy soil pollution, and its mobility can be influenced by alternating redox conditions. However, mechanistic and quantitative insights into the biogeochemical cycles of exogenous As in paddy soil are still lacking. Herein, the variations of As species in paddy soil spiking with As(III) or As(V) were investigated in the process of 40 d of flooding followed 20 d of drainage. During flooding process, available As was immobilized in paddy soil spiking As(III) and the immobilized As was activated in paddy soil spiking As(V) owing to deprotonation. The contributions of Fe oxyhydroxides and humic substances (HS) to As immobilization in paddy soil spiking As(III) were 80.16% and 18.64%, respectively. Whereas the contributions of Fe oxyhydroxides and HS to As activation in paddy soil spiking As(V) were 47.9% and 52.1%, respectively. After entering drainage, available As was mainly immobilized by Fe oxyhydroxides and HS and adsorbed As(III) was oxidized. The contribution of Fe oxyhydroxides to As fixation in paddy soil spiking As(III) and As(V) was 88.82% and 90.26%, respectively, and of HS to As fixation in paddy soil spiking As(III) and As(V) was 11.12% and 8.95%, respectively. Based on the model fitting results, the activation of Fe oxyhydroxides and HS bound As followed with available As(V) reduction were key processes during flooding. This may be because the dispersion of soil particles and release of soil colloids activated the adsorbed As. Immobilization of available As(III) by amorphous Fe oxyhydroxides followed with adsorbed As(III) oxidation were key processes during drainage. This may be ascribe to the occurrence of coprecipitation and As(III) oxidation mediated by reactive oxygen species from Fe(II) oxidation. The results are beneficial for a deeper understanding of As species transformation at the interface of paddy soil-water as well as an estimation pathway for the impacts of key biogeochemical cycles on exogenous As species under a redox-alternating condition.
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Arsênio , Oryza , Poluentes do Solo , Substâncias Húmicas , Arsênio/química , Solo/química , Ferro/química , Poluentes do Solo/análise , Oxirredução , Oryza/metabolismoRESUMO
Cr(VI) detoxification and organic matter (OM) stabilization are usually influenced by the biological transformation of iron (Fe) minerals; however, the underlying mechanisms of metal-reducing bacteria on the coupled kinetics of Fe minerals, Cr, and OM remain unclear. Here, the reductive sequestration of Cr(VI) and immobilization of fulvic acid (FA) during the microbially mediated phase transformation of ferrihydrite with varying Cr/Fe ratios were investigated. No phase transformation occurred until Cr(VI) was completely reduced, and the ferrihydrite transformation rate decreased as the Cr/Fe ratio increased. Microscopic analysis was uncovered, which revealed that the resulting Cr(III) was incorporated into the lattice structure of magnetite and goethite, whereas OM was mainly adsorbed on goethite and magnetite surfaces and located within pore spaces. Fine line scan profiles showed that OM adsorbed on the Fe mineral surface had a lower oxidation state than that within nanopores, and C adsorbed on the magnetite surface had the highest oxidation state. During reductive transformation, the immobilization of FA by Fe minerals was predominantly via surface complexation, and OM with highly aromatic and unsaturated structures and low H/C ratios was easily adsorbed by Fe minerals or decomposed by bacteria, whereas Cr/Fe ratios had little effect on the binding of Fe minerals and OM and the variations in OM components. Owing to the inhibition of crystalline Fe minerals and nanopore formation in the presence of Cr, Cr sequestration and C immobilization can be synchronously favored at low Cr/Fe ratios. These findings provide a profound theoretical basis for Cr detoxification and synchronous sequestration of Cr and C in anoxic soils and sediments.
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Óxido Ferroso-Férrico , Minerais , Minerais/química , Compostos Férricos/química , Cromo/química , OxirreduçãoRESUMO
Dissolved organic matter (DOM) leaching from biodegradable microplastics (BMPs) and its characteristics and corresponding environmental implication are rarely investigated. In this study, the main component of DOM leachate from the two BMPs (polyadipate/butylene terephthalate (PBAT)/polycaprolactone (PCL)) was verified by using excitation-emission matrix-parallel factor analysis (EEM-PARAFAC). The PBAT-DOM (PBOM) was aromatized and terrestrial. Comparatively, PCL-DOM (PLOM) had low molecular weight. PBOM contained protein-like components while PLOM contained tryptophan and tyrosine components. Interestingly, both PBOM and PLOM could accelerate the decomposition and oxidation of coexisting polystyrene (PS) under light irradiation. Further, the difference in composition and the properties of BMPs-DOM significantly affected its photochemical activity. The high territoriality and protein-like component of PBOM significantly promoted the generation of 1O2 and O2â¢-, which caused faster disruptions to the backbone of PS. Simultaneously, the microbial community's richness, diversity, and metabolism were obviously improved under the combined pressure of aged PS and BMPs-DOM. This study threw light on the overlooked contribution of DOM derived from BMPs in the aging process of NMPs and their impact on the microbial community and provided a promising strategy for better understanding of combined MPs' fate and environmental risk.
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Plásticos , Envelhecimento da Pele , Microplásticos , Matéria Orgânica Dissolvida , Espectrometria de Fluorescência , Análise Fatorial , Substâncias HúmicasRESUMO
Nickel is generally released from flooded soils; however, the key Ni transformation processes in soils that are freshly contaminated by Ni2+ during anoxic-oxic alteration remain unclear. We developed a kinetic model to investigate the Ni transformation in paddy soils under anoxic and oxic conditions based on the results of the seven-step sequential extraction, determination of dissolved and soil organic matter, and surface site quantification, which provide the kinetic data of different Ni fractions, organic matter, and reactive sites for modeling. The dissolved, exchangeable, and specifically adsorbed Ni was gradually transferred to fulvic complex, humic complex, Fe-Mn oxide bound, and sulfide bound Ni after 40 d of anoxic incubation due to the increase in pH and soil surface sites, which were mainly induced by Fe(III) oxide reduction and soil organic matter release. The introduction of oxygen triggered a rapid release of Ni, which was ascribed to the decrease in pH and soil surface sites caused by Fe(II) oxidation and carbon re-immobilization. Kinetic modeling demonstrated that complexation with soil organic matter dominated Ni immobilization under anoxic conditions, while organic matter and Fe-Mn oxides contributed similarly to Ni release under oxic conditions, although the majority of Ni remained complexed with soil organic matter. These findings are important for the evaluation and prediction of Ni behavior in paddy soils with exogenous Ni during flooding-drainage practices.
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Coupled reactions among chromium (Cr), organic matter (OM), and iron (Fe) minerals play significant roles in Cr and carbon (C) cycling in Cr-contaminated soils. Although the inhibitory effects of Cr or polysaccharides acid (PGA) on ferrihydrite transformation have been widely studied, mechanistic insights into detoxification of Cr(VI) and immobilization of Cr and C during the microbially mediated reductive transformation of ferrihydrite remain unclear. In this study, underlying sequestration mechanisms of Cr and C during dissimilatory Fe reduction at various Cr/Fe ratios were investigated. Solid-phase analysis showed that reductive transformation rates of ferrihydrite were impeded by high Cr/Fe ratio and more magnetite was found at low Cr loadings. Microscopic analysis showed that formed Cr(III) was immobilized by magnetite and goethite through isomorphous substitution, whereas PGA was adsorbed on the crystalline Fe mineral surface. Spectroscopic results uncovered that binding of Fe minerals and PGA was achieved by surface complexation of structural Fe with carboxyl functional groups, and that the adhesion order of PGA functional groups and Fe minerals was influenced by the Cr/Fe ratios. These findings have significant implications for remediating Cr contaminants, realizing C fixation, and developing a quantitative model for Cr and C cycling by coupling reductive transformation in Cr-contaminated environments.
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Compostos Férricos , Óxido Ferroso-Férrico , Compostos Férricos/química , Minerais/química , Cromo/química , Biotransformação , OxirreduçãoRESUMO
To estimate the risks and developing remediation strategies for the mercury (Hg)-contaminated soils, it is crucial to understand the mechanisms of Hg transformation and migration in the redox-changing paddy fields. In present study, a Hg-spiked acidic paddy soil (pH 4.52) was incubated under anoxic conditions for 40 d and then under oxic conditions for 20 d. During anoxic incubation, the water-soluble, exchangeable, specifically adsorbed, and fulvic acid-complexed Hg decreased sharply, whereas the humic acid-complexed Hg, organic, and sulfide-bound Hg gradually increased, which were mainly ascribed to the enhanced adsorption on the surface of soil minerals with an increase in soil pH, complexation by organic matters, precipitation as HgS, and absorption by soil colloids triggered by reductive dissolution of Fe(III) oxides. By contrast, after oxygen was introduced into the system, a gradual increase in available Hg occurred with decreasing soil pH, decomposition of organic matters and formation of Fe(III) oxides. A kinetic model was established based on the key elementary reactions to quantitatively estimate transformation processes of Hg fractions. The model matched well with the modified Tessier sequential extraction data, and suggested that large molecular organic matter and humic acid dominated Hg complexation and immobilization in acidic paddy soils. The content of methylmercury increased and reached its peak on anoxic 20 d. Sulfate-reducing bacteria Desulfovibrio and Desulfomicrobium were the major Hg methylating bacteria in the anoxic stage whereas demethylating microorganisms Clostridium_sensu_stricto_1 and Clostridium_sensu_stricto_12 began to grow after oxygen was introduced. These new dynamic results provided new insights into the exogenous Hg transformation processes and the model could be used to predict Hg availability in periodically flooded acidic paddy fields.
Assuntos
Mercúrio , Oryza , Poluentes do Solo , Solo/química , Substâncias Húmicas , Compostos Férricos , Poluentes do Solo/análise , Mercúrio/análise , Oxigênio , ÓxidosRESUMO
Tendon healing is a complex process involving inflammation, proliferation, and remodeling, eventually achieving a state of hypocellularity and hypovascularity. Currently, few treatments can satisfactorily restore the structure and function of native tendon. Bioactive glass (BG) has been shown to possess immunomodulatory and angiogenic properties. In this study, we investigated whether an injectable hydrogel fabricated of BG and sodium alginate (SA) could be applied to enhance tenogenesis following suture repair of injured tendon. We demonstrated that BG/SA hydrogel significantly accelerated tenogenesis without inducing heterotopic ossification based on histological analysis. The therapeutic effect could attribute to increased angiogenesis and M1 to M2 phenotypic switch of macrophages within 7 days post-surgery. Morphological characterization demonstrated that BG/SA hydrogel partially reverted the pathological changes of Achilles tendon, including increased length and cross-sectional area (CSA). Finally, biomechanical test showed that BG/SA hydrogel significantly improved ultimate load, failure stress, and tensile modulus of the repaired tendon. In conclusion, administration of an injectable BG/SA hydrogel can be a novel and promising therapeutic approach to augment Achilles tendon healing in conjunction with surgical intervention.