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Neointimal hyperplasia is a pathological vascular remodeling caused by abnormal proliferation and migration of subintimal vascular smooth muscle cells (VSMCs) following intimal injury. There is increasing evidence that tRNA-derived small RNA (tsRNA) plays an important role in vascular remodeling. The purpose of this study is to search for tsRNAs signature of neointima formation and to explore their potential functions. The balloon injury model of rat common carotid artery was replicated to induce intimal hyperplasia, and the differentially expressed tsRNAs (DE-tsRNAs) in arteries with intimal hyperplasia were screened by small RNA sequencing and tsRNA library. A total of 24 DE-tsRNAs were found in the vessels with intimal hyperplasia by small RNA sequencing. In vitro, tRF-Glu-CTC inhibited the expression of fibromodulin (FMOD) in VSMCs, which is a negative modulator of TGF-ß1 activity. tRF-Glu-CTC also increased VSMC proliferation and migration. In vivo experiments showed that inhibition of tRF-Glu-CTC expression after balloon injury of rat carotid artery can reduce the neointimal area. In conclusion, tRF-Glu-CTC expression is increased after vascular injury and inhibits FMOD expression in VSMCs, which influences neointima formation. On the other hand, reducing the expression of tRF-Glu-CTC after vascular injury may be a potential approach to prevent vascular stenosis.
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Traumatismos de las Arterias Carótidas , Lesiones del Sistema Vascular , Animales , Ratas , Traumatismos de las Arterias Carótidas/genética , Traumatismos de las Arterias Carótidas/metabolismo , Movimiento Celular , Proliferación Celular , Células Cultivadas , Modelos Animales de Enfermedad , Fibromodulina/metabolismo , Hiperplasia/complicaciones , Hiperplasia/metabolismo , Hiperplasia/patología , Miocitos del Músculo Liso/metabolismo , Neointima/metabolismo , Neointima/patología , Neointima/prevención & control , Ratas Sprague-Dawley , ARN/metabolismo , ARN de Transferencia/metabolismo , Remodelación Vascular , Lesiones del Sistema Vascular/metabolismoRESUMEN
A new lipopeptide, N-desmethylmajusculamide B (1), was isolated from the Okinawan cyanobacterium Okeania hirsuta along with 2 known compounds majusculamide A (2) and majusculamide B (3). The planar structure of (1) was elucidated by a detailed analysis of mass spectrometry and nuclear magnetic resonance spectra. The absolute configurations of the amino acid residues were determined using Marfey's analysis. The configuration of C-16 in the α-methyl-ß-keto-decanoyl moiety was determined unambiguously to be S by conducting a semisynthesis of N-desmethylmajusculamide B from 3. The cytotoxicity against mouse L1210 leukemia cells was evaluated for majusculamides (1-3).
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Cianobacterias , Lipopéptidos , Cianobacterias/química , Ratones , Animales , Lipopéptidos/química , Lipopéptidos/aislamiento & purificación , Lipopéptidos/farmacología , Línea Celular Tumoral , Antineoplásicos/química , Antineoplásicos/farmacología , Antineoplásicos/aislamiento & purificación , Espectroscopía de Resonancia MagnéticaRESUMEN
Various activated persulfate (PS) technologies have been investigated and implemented to eliminate antibiotic contaminants from water. The investigation and evaluation of different activation systems are essential for the application of PS techniques. The degradation of amoxicillin (AMX) by heat, light, or heterogeneous catalyst of Fe-AC composite activated PS was investigated, and the kinetics, mechanisms and toxicities were compared in this work. The apparent activation energy of the Fe-AC system was lower than that of the heat system. Hydroxyl and sulfate radicals were demonstrated by electron paramagnetic resonance (EPR) spectroscopy and quenching tests. There were 22, 21 and 13 types of degradation intermediates detected in heat, light and Fe-AC system, respectively. Six pathways of AMX degradation were proposed and compared in the three activated PS systems. The toxicity prediction of degradation intermediates under different treatment processes was estimated by ecological structure-activity relationship model and toxicity estimation software tool. The genotoxicity of the AMX degradation solution was tested by Acinetobacter baylyi ADP1_recA, which indicated that the AMX solution after treatment in the Fe-AC system had almost no genotoxicity. The Fe-AC/PS system shows apparent advantages over the heat or light activated PS system in most cases, demonstrating that the Fe-AC/PS system is suitable for AMX-contaminated remediation in aqueous solution.
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Amoxicilina , Contaminantes Químicos del Agua , Calor , Oxidación-Reducción , Contaminantes Químicos del Agua/química , Antibacterianos , AguaRESUMEN
Sodium percarbonate (SPC) and peroxymonocarbonate (PMC) have been widely used in modified Fenton reactions because of their multiple superior features, such as a wide pH range and environmental friendliness. This broad review is intended to provide the fundamental information, status and progress of SPC and PMC based decontamination technologies according to the peer-reviewed papers in the last two decades. Both SPC and PMC can directly decompose various pollutants. The degradation efficiency will be enhanced and the target contaminants will be expanded after the activation of SPC and PMC. The most commonly used catalysts for SPC activation are iron compounds while cobalt compositions are applied to activate PMC in homogenous and heterogeneous catalytical systems. The generation and participation of hydroxyl, superoxide and/or carbonate radicals are involved in the activated SPC and PMC system. The reductive radicals, such as carbon dioxide and hydroxyethyl radicals, can be generated when formic acid or methanol is added in the Fe(II)/SPC system, which can reduce target contaminants. SPC can also be activated by energy, tetraacetylethylenediamine, ozone and buffered alkaline to generate different reactive radicals for pollutant decomposition. The SPC and activated SPC have been assessed for application in-situ chemical oxidation and sludge dewatering treatment. The challenges and prospects of SPC and PMC based decontamination technologies are also addressed in the last section.
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Contaminantes Químicos del Agua , Carbonatos , Descontaminación , Peróxido de Hidrógeno , Oxidación-Reducción , Contaminantes Químicos del Agua/análisisRESUMEN
Based on the chemiluminescence (CL) phenomenon of peroxymonosulfate (PMS) and Tb(III) enhanced by its ligand in a micelle microenvironment, a fast and sensitive flow injection CL method for PMS detection was proposed and applied to the analysis of different samples and PMS decomposition. Under the optimized conditions, a linear range was obtained from 4.0 × 10-6 mol L-1 to 2.0 × 10-4 mol L-1 with a high correlation coefficient (r = 0.9997), detection limit of 5.0 × 10-7 mol L-1 (S/N = 3) and relative standard deviation of 2.4% for 1.0 × 10-5 mol L-1 PMS (n = 9). This was successfully applied to the determination of PMS in Virkon powder, tap water, and swimming pool water samples with satisfactory recoveries from 94.8% to 104.8%. In particular, the analytical frequency could be as fast as five samples per minute because there was no reaction step before analysis and the CL phenomenon was instantaneous. Therefore, this CL method has also been successfully applied to investigate the PMS decomposition profiles in carbon material (carbon nanotubes, carbon nanofibres, activated carbon and graphene oxide) catalysis systems, which followed pseudo-first-order kinetics with good correlation coefficients (r > 0.9305). Quenching experiments and electron spin resonance spectra verified that the CL phenomenon was due to the formation of singlet oxygen, and that hydroxyl and sulfate radicals might be important in the generation of singlet oxygen. Tb(III) is the luminescent emitter according to the characteristics emission bands of the fluorescence and CL spectra in different media.
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Análisis de Inyección de Flujo , Colorantes Fluorescentes/química , Luminiscencia , Mediciones Luminiscentes , Peróxidos/análisis , Terbio/química , Análisis de Inyección de Flujo/instrumentación , Ligandos , Mediciones Luminiscentes/instrumentación , MicelasRESUMEN
A new aplysiatoxin derivative, neo-aplysiatoxin A (1), along with seven known compounds, neo-debromoaplysiatoxin A (2), dolastatin 3 (3), lyngbic acid (4), malyngamide M (5), hermitamide A (6), (-)-loliolide (7), and (+)-epiloliolide (8), was isolated from the Okinawan cyanobacterium Moorea producens. Their structures were elucidated on the basis of spectroscopic data, including high-resolution mass spectrometry and nuclear magnetic resonance. The compounds were evaluated for cytotoxic and diatom growth inhibition activities.
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Cianobacterias/metabolismo , Toxinas de Lyngbya/metabolismo , Depsipéptidos/metabolismo , Ácidos Grasos Monoinsaturados/metabolismo , Espectroscopía de Resonancia Magnética , Espectrometría de Masas , Estructura MolecularRESUMEN
The mobilization and redistribution of organic contaminants in groundwater is the basis and key to explore its dynamic evolution and appropriate remediation. The naturally occurring diametrical temperature gradient during freezing and thawing cycle leads to distinct behaviors of organic contaminants in groundwater. In this study, the pore-scale distribution of diesel oil in the porous media was quantitatively divided into capillary fluid state (CFS) and free fluid state (FFS) based on multiphase flow dynamics, employing low-field nuclear magnetic resonance (LF-NMR) technology. The pore-scale distribution of diesel oil depends not only on the freezing and thawing cycle but also on the temperature gradient according to LF-NMR results. The content of diesel oil in the CFS generally increases with a positive temperature gradient (e.g. freezing) compared to a negative temperature gradient (e.g. thawing), while the content of diesel oil in the FFS generally decreases. This dependence of the temperature gradient on pore-scale distribution of the diesel oil is positively correlated with the particle size of the porous medium. Furthermore, the pore-scale distribution of the diesel oil during the freezing and thawing cycle is influenced by the kinematic viscosity of the diesel oil. There is an exponential relationship between the diesel oil content and the kinematic viscosity, independent of the freezing or thawing process. During the freezing process, the diesel oil migrates from FFS to CFS, while this migration is reversed during the thawing process. The reverse migration of the diesel oil between the freezing and thawing processes leads to a spatial redistribution of the diesel oil, which is controlled by both the fluid energy and the capillary force. The present work provide meaningful guidance for the remediation of groundwater contamination in cold regions.
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Congelación , Gasolina , Agua Subterránea , Contaminantes Químicos del Agua , Agua Subterránea/química , Contaminantes Químicos del Agua/química , Temperatura , Espectroscopía de Resonancia MagnéticaRESUMEN
Parabens (PBs) are a class of preservatives commonly used in cosmetics and pharmaceuticals. Studies have shown that these compounds may act as endocrine disruptors, affecting thyroxine levels in humans. PBs with longer chain substituents, such as butylparaben (BuP), are less prone to complete biotransformation and are therefore more likely to accumulate in the body. In this study, the effect of high-dose exposure to BuP on thyroid microstructure, ultrastructure, and function was investigated in rats. 50 mg/kg bw per day of BuP was injected subcutaneously into the neck of rats for 4 weeks. Rat thyroid weight, microstructure, and ultrastructure were determined, and the levels of thyroid sodium/iodide symporter (NIS), serum thyroid hormones, and thyroid autoantibodies were measured. The human thyroid cell line was used to study the mechanism of BuP on thyroid epithelial cells. The weight of the thyroid gland of BuP-exposed rats was increased, the structure of the thyroid follicles was irregular and damaged, the mitochondria and rough endoplasmic reticulum were swollen and damaged, and the microvilli at the tip of the epithelium were reduced and disappeared. Serum total T3, total T4, free T3, and free T4 were decreased in BuP-exposed rats, and TSH, peroxidase antibody, and thyroglobulin antibody were increased. In vitro, BuP decreased the level of NIS in thyroid epithelial cells, inhibited proliferation and viability, and induced apoptosis in a dose-dependent manner. This study demonstrated that high-dose exposure to BuP induced structural, ultrastructural, and functional impairment to the thyroid gland of rats, which may be one of the factors leading to hypothyroidism.
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Hipotiroidismo , Parabenos , Ratas , Animales , Humanos , Parabenos/toxicidad , Parabenos/química , Hormonas Tiroideas , Hipotiroidismo/inducido químicamente , Tiroxina , TirotropinaRESUMEN
Trihydroxy fatty acids are oxidative metabolites of polyunsaturated fatty acids isolated from plants, bacteria, fungi, and microalgae and have a variety of biological activities. In this study, a new trihydroxy fatty acid, okeanic acid-A (1), was isolated together with malyngic acid (2) and 15,16-dihydromalyngic acid (3) from the cyanobacterium Okeania hirsuta collected in Okinawa, Japan. The planar structure of 1 was elucidated by detailed analyses using high-resolution ESI-MS and 1D and 2D NMR spectroscopy. The absolute configurations of the hydroxy groups in 1 were determined unambiguously by chemical derivatisation and a modified Mosher's method. These cyanobacterial trihydroxy fatty acids (1-3) have identical configurations at their respective trihydroxy parts. Okeanic acid-A (1) showed mild growth-inhibitory activity against the marine diatom Nitzschia amabilis.
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This study comprehensively investigated mercury (Hg) contents of various environmental compartments in a typical antimony-coal mining area with intensive industrial activities over the past 120 years to analyze Hg environmental behaviors and evaluate Hg risks. The total mercury (THg) contents in river water, sediments, soils, PM10, dust falls, vegetables and corns were 1.16 ± 0.63 µg/L, 2.01 ± 1.64 mg/kg, 1.87 ± 3.88 mg/kg, 7.87 ± 18.68 ng/m3, 13.01 ± 14.53 mg/kg, 0.30 ± 0.34 mg/kg and 3.11 ± 0.51 µg/kg, respectively. The δ202Hg values in soils and dust falls were - 1.58 â¼ 0.12 and 0.25 â¼ 0.30, respectively. Environmental samples affected by industrial activities in the Xikuangshan (XKS) presented higher THg and δ202Hg values. Binary mixing model proved that atmospheric deposition with considerable Hg deposition flux (0.44 â¼ 6.40, 3.12 ± 2.20 mg/m2/y) in the XKS significantly contributed to Hg accumulations on surface soils. Compared with soils, sediments with more frequent paths and higher burst probabilities presented higher dynamic Hg risks. Children were faced higher health risk of multiple Hg exposure than adults. Furthermore, the health risk of THg by consuming leaf vegetables deserved more attention. These findings provided scientific basis for managing Hg contamination.
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Minas de Carbón , Mercurio , Niño , Humanos , Mercurio/análisis , Antimonio , Ecosistema , Minería , Monitoreo del Ambiente , Sedimentos Geológicos , Suelo , Verduras , PolvoRESUMEN
Environmental factors, particularly dietary habits, play an important role in cardiovascular disease susceptibility and progression through epigenetic modification. Previous studies have shown that hyperplastic vascular intima after endarterectomy is characterized by genome-wide hypomethylation. The purpose of this study was to investigate whether methyl donor diet affects intimal hyperplasia and the possible mechanisms involved. Intimal hyperplasia was induced in SD rats by carotid artery balloon injury. From 8 d before surgery to 28 d after surgery, the animals were fed a normal diet (ND) or a methyl donor diet (MD) supplemented with folic acid, vitamin B12, choline, betaine, and zinc. Carotid artery intimal hyperplasia was observed by histology, the effect of MD on carotid protein expression was analyzed by proteomics, functional clustering, signaling pathway, and upstream-downstream relationship of differentially expressed proteins were analyzed by bioinformatics. Results showed that MD attenuated balloon injury-induced intimal hyperplasia in rat carotid arteries. Proteomic analysis showed that there were many differentially expressed proteins in the common carotid arteries of rats fed with two different diets. The differentially expressed proteins are mainly related to the composition and function of the extracellular matrix (EMC), and changes in the EMC can lead to vascular remodeling by affecting fibrosis and stiffness of the blood vessel wall. Changes in the levels of vasculotropic proteins such as S100A9, ILF3, Serpinh1, Fbln5, LOX, HSPG2, and Fmod may be the reason why MD attenuates intimal hyperplasia. Supplementation with methyl donor nutrients may be a beneficial measure to prevent pathological vascular remodeling after injury.
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Traumatismos de las Arterias Carótidas , Lesiones del Sistema Vascular , Ratas , Animales , Hiperplasia , Ratas Sprague-Dawley , Proteómica , Remodelación Vascular , Dieta , Traumatismos de las Arterias Carótidas/metabolismoRESUMEN
The concentrations, spatial-temporal distribution, and influencing factors of 16 polycyclic aromatic hydrocarbons (PAHs) in the sediments of Poyang Lake were studied, and a quantitative source analysis of PAHs in different areas of the lake was conducted. PAHs were widespread within the sediments. The concentrations of ∑16PAHs in the surface sediments of all sites ranged from 203 to 2 318 µg·kg-1. The concentrations of PAHs in the surface sediments of the lake body were higher than those in the surface sediments of the inlet rivers. The ratio of PAHs in Poyang Lake was 4 rings > 5 rings > 6 rings > 3 rings > 2 rings; the composition of 4-ring PAHs was dominant, and its content accounted for 86.11% of ∑16PAHs. The 2- and 3-ring and some 4-ring PAHs, including Flua and Pyr, were more susceptible to SOM, and the 4 through 6-ring PAHs were more susceptible to ORP and heavy metals and other environmental factors. Spatially, the higher concentration of ∑16PAHs occurred in the area of the lake adjacent to Duchang County and Poyang County, where the terrain was relatively closed, and the water exchange with the surrounding area was less than that in other sections, which was not conducive to the migration, transformation, and degradation of pollutants. In the temporal distribution, the changes in PAHs concentration level and the development of GDP in Jiangxi Province showed high consistency, and the influence of economic development and human activities might have been the main reason for the increasing PAHs concentration level. The main sources of PAHs in surface sediments of Poyang Lake included petroleum pollution and oil and coal and biomass combustion sources, and there were some spatial differences in PAHs sources in different regions. This study can provide a reference for PAHs pollution in surface sediments of Poyang Lake, which is important for the ecological environmental protection and management of Poyang Lake.
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To clarify the characteristics and source apportionment of the VOCs initial mixing ratio in Beijing in summer, continuous monitoring of VOCs was conducted in the Beijing urban area from May to August 2022, and the initial mixing ratio was calculated using the photochemical ratio method. The results showed that:â during the study period, initial φ(TVOCs) in the Beijing urban area were (30.0 ±11.5)×10-9, in which the proportion of VOCs and alkanes containing oxygen reached 34.2% and 33.2%, respectively. The species with high volume fractions were low carbon substances such as acetone, ethane, acetaldehyde, and propane. â¡ The initial TVOCs mixing ratio in Beijing showed a slightly unimodal trend, reaching the peak at 11:00 and slightly decreasing in the afternoon. ⢠Isoprene, acetaldehyde, n-butanal, and ethylene were the major contributors to the generation of O3, whereas toluene, isoprene, m-paraxylene, and ethylbenzene were the major contributors to the generation of secondary organic aerosols. ⣠Based on the initial mixing ratio of PMF analysis, it was found that aging background and secondary sources (30%) contributed the most to VOCs in Beijing, and motor vehicle sources (25%) were the main primary human sources. In addition, solvent and fuel volatile sources contributed 16%, combustion sources contributed 11%, industrial process sources contributed 9%, and natural sources contributed 9%. ⤠The anthropogenic sources of Beijing were mainly from the eastern and southern regions, whereas the natural sources were from the western and northwestern regions. This research showed that vehicle emissions should be further reduced, and regional joint prevention and control to reduce VOCs in the whole region is an effective means to control VOCs in Beijing.
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Thyroid nodules are frequently accompanied by degenerative changes, such as hemorrhage, cholesterol crystallization, fibrous tissue deposition, or filling with fat. Although calcification is also a common phenomenon, osteogenesis, characterized by mature bone formation, is very rare. Here, we describe a case of Hashimoto's thyroiditis with osseous metaplasia and ectopic bone formation case and discuss its possible causes.
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Calcinosis , Enfermedad de Hashimoto , Tiroiditis Autoinmune , Humanos , Tiroiditis Autoinmune/complicaciones , Osteogénesis , Enfermedad de Hashimoto/complicaciones , Calcinosis/complicaciones , Metaplasia/complicacionesRESUMEN
Migration of the embryonic thymus is thought to be the basis for the formation of ectopic thymic tumors. Thymic ectopy may be a result of the abnormal migration of the third or fourth branchial cleft to the anterior mediastinum during weeks 5-6 of embryonic development. However, ectopic thymic carcinoma has highly nonspecific histologic features and occurs in variable and unpredictable locations making it difficult to diagnose. However, the clinical diagnosis and treatment should not overlook the possibility of ectopic thymic tumors. Here, we report a case of ectopic thymic carcinoma diagnosed as thyroid cancer before surgery occurring in a location consistent with current assumptions. Furthermore, we briefly review the literature on ectopic thymic carcinoma and discuss current diagnostic and treatment approaches.
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Timoma , Neoplasias del Timo , Humanos , Timoma/patología , Glándula Tiroides/patología , Cuello/patología , Timo , Neoplasias del Timo/diagnóstico , Neoplasias del Timo/patologíaRESUMEN
There is increasing evidence that obesity is associated with the occurrence and development of malignant tumors. When studying the relationship between obesity and malignant tumors, it is very important to choose an appropriate animal model. However, BALB/c nude mice and other animals commonly used to study tumor xenograft (human-derived tumor cell lines) transplantation models are difficult to induce obesity, while C57BL/6 mice and other model animals commonly used for obesity research are not suitable for tumor xenograft transplantation. Therefore, it is difficult to replicate both obesity and malignancy in animal models at the same time. This review summarizes several experimental animal models and protocols that can simultaneously induce obesity and tumor xenografts.
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Traditional advanced oxidation processes suffer from low availability of ultrashort lifetime radicals and declining stability of catalysts. Co nanoparticles in hollow bimetallic metal-organic frameworks (Co@MOFs) were synthesized via a solvothermal method. Nanoconfinement and peroxymonocarbonate (PMC) degradation system endows Co@MOFs with high catalytic activity and stability even in the actual water matrices. The nanocomposites exhibited 100-200 nm polyhedron structure with irregular nanocavity between the 20 nm shell and multicores. Co nanoparticles were completely encapsulated by the FeIII-MOF-5 shell according to the X-ray diffraction and photoelectron spectra. Both 0.8 nm micropores and 3.6 nm mesopores were proven to be present. The yolk-shell Co@MOFs exhibited higher catalytic performance than that of Co nanoparticles, hollow FeIII-MOF-5 and its core-shell counterpart toward PMC activation during sulfamethoxazole degradation. The catalytic activities of Co@MOFs for the activation of unsymmetrical peroxides (PMC and peroxymonosulfate) were much higher than those for the symmetrical peroxides (H2O2 and persulfate) and the heterogeneous catalysis was dominant in the Co@MOFs activated H2O2 and PMC systems. The MOF stability was the highest and metal leakages were the least in the activated PMC system among the four peroxides because of mild reaction conditions and the alkalescent solution (pH = 8.3-8.4). Furthermore, the high removal efficiencies (>94%) and degradation rates could be maintained in the different actual water matrices due to the confinement effects. The contributions of carbonate and hydroxyl radicals were primary for sulfamethoxazole degradation, and superoxide anion and singlet oxygen also played essential roles according to scavenging experiments and time-series spin-trapping electron spin resonance spectra. Six degradation pathways were proposed according to 26 intermediate identification and the pharmacophores of more than 80% intermediates were destroyed, which would benefit subsequent biological treatment. Successful combination of nanoconfinement and PMC might provide a new effective solution for pollution remediation.
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Estructuras Metalorgánicas , Nanopartículas , Compuestos Férricos , Peróxido de Hidrógeno , Carbonatos , Peróxidos , AntibacterianosRESUMEN
In the area affected by non-ferrous metal mining activities, mercury (Hg) contamination in the water and sediments posed potential risks to ecology and human health. In this study, river water and sediment samples were collected in the Zijiang river - South Dongting Lake basin to analyze Hg residues, identify potential Hg sources and evaluate the ecological and health risks posed by Hg contamination. In this study, the average concentrations of THg, PHg, DHg and DMeHg in river water were 38.05 ± 27.13 ng/L, 25.18 ± 26.83 ng/L, 12.88 ± 9.64 ng/L and 0.29 ± 0.07 ng/L, respectively. The THg and MeHg contents in sediments were 234.24 ± 152.93 µg/kg and 0.48 ± 0.16 µg/kg, respectively. The more enrichment of Hg in sediments was observed in the Zijiang River than in the South Dongting Lake, especially in the upstream and midstream regions. Two potential Hg sources in the basin were identified by correlation matrix, principal component analysis (PCA) and positive matrix factorization (PMF) model. The comparable Hg flux with other rivers worldwide was found in the Zijiang River (0.53 Mg/y). Furthermore, it was found by the delayed geochemical hazard (DGH) model that the ecological risk of Hg was more significant in the Zijiang River with more frequent transformation pathways. For different populations, the health risk values caused by Hg were all lower than the USEPA's guideline value. This study provided sound evidence for further control of Hg contamination.
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Mercurio , Contaminantes Químicos del Agua , Humanos , Mercurio/análisis , Lagos , Agua/análisis , Contaminantes Químicos del Agua/análisis , Monitoreo del Ambiente , China , Medición de Riesgo , Sedimentos Geológicos/químicaRESUMEN
To deeply understand the formation mechanism of polybrominated dibenzo-p-dioxins/furans (PBDD/Fs) in the thermal disposal process of polybrominated diphenyl ether (PBDE)-containing waste, this paper studied the formation pathways of key intermediates (free radicals, FRs) in the formation process of PBDD/Fs. BDE-209, the most common PBDE in the environment, was selected as the object of study to analyze FR formation by simulating the key conditions such as temperature (850 °C) and Fe-based materials when PBDE-containing waste entering cement kiln precalciner. Electron paramagnetic resonance (EPR) spectroscopy and density functional theory (DFT) calculations were used to study the reaction. The result of simulation experiments revealed carbon-centered radicals, and DMPO-OH analysis further confirmed the generation of FRs. The findings confirmed previous calculations predicting the existence of radical intermediates during the formation of PBDD/Fs from BDE-209. DFT calculations revealed the existence of an inner ortho-position CBr bond in BDE-209. The priority order of the bond breaking of BDE-209 was ether bond, inner ortho-position CBr bond, and outside ortho-position CBr bond. BDE-209 can further form three kinds of FRs, namely, oxygen-centered radicals of single benzene rings, carbon-centered radicals of single benzene rings, and carbon-centered radicals of double benzene rings. The specific processes of FR formation were inferred: high-temperature homogeneous cleavage of chemical bonds, electron transfer, and chemisorption, where electron transfer and chemisorption may be more important pathways. The proposed inner ortho-position cleavage within BDE-209 provides new insights into the degradation of PBDEs and the formation of PBDD/Fs; the results regarding BDE-209 generation radicals further elucidate the synthesis mechanism of dioxins, which is important for controlling dioxin generation and emission during the treatment and disposal of waste containing PBDEs.
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The spatiotemporal distributions, influential factors, and ecological risks of 15 phthalate acid esters (PAEs) in the sediments of three typical lakes in Inner Mongolia were investigated in this work. PAEs were widespread in all surface sediments ranging from 598.3 to 3873.8 µg/kg dry weight. Average PAE concentrations were highest in the surface sediments of Wuliangsuhai Lake followed by Daihai and Hulun Lakes, which were consistent with population density and intensity of anthropogenic activities. Dibutyl phthalate, di-iso-butyl phthalate (DIBP), and diethyl phthalate (DEP) were the dominant PAEs with similar abundance orders for the three lakes. The cold climate could explain the higher DEP abundance in the sediments of lakes at higher latitudes. The highest Σ PAE and most individual PAE concentrations were located at one of the discharge river estuaries because most PAEs were terrestrial pollutants. Σ PAE concentrations in the core sediments increased with years and fluctuations owing to the increasing PAE usage and input. The second highest PAE concentration peaks were associated with the high gross domestic product growth rates in 2003-2008. Redundancy analysis revealed that butyl benzyl phthalate and diamyl phthalate in the surface sediments of Hulun Lake were principally positively influenced by organic matter (65.6% contribution among geochemical variables), Fe oxides (25.1% contribution among metals), and Mn oxides (23.8% contribution among metals). The DIBP and DEP exhibited high risks to sensitive fish according to a risk quotient assessment. This work presents new insights into PAE status and deposition mechanisms in the lakes within high latitudes or cold climates, and provides important information for future environmental protection and management.