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The environmental concern posed by toxic heavy metal pollution in soil and water has grown. Ca-based layered double hydroxides (LDHs) have shown exceptional efficacy in eliminating heavy metal cations through the formation of super-stable mineralization structures (SSMS). Nevertheless, it is still unclear how the intricate coordination environment of Ca2+ in Ca-based LDH materials affects the mineralization performance, which hinders the development and application of Ca-based LDH materials as efficient mineralizers. Herein, we discover that, in comparison to a standard LDH, the mineralization efficiency for Cd2+ ions may be significantly enhanced in the pentacoordinated structure of defect-containing Ca-5-LDH utilizing both density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations. Furthermore, the calcination-reconstruction technique can be utilized to successfully produce pentacoordinated Ca-5-LDH. Subsequent investigations verified that Ca-5-LDH exhibited double the mineralization performance (421.5 mg g-1) in comparison to the corresponding pristine seven coordinated Ca-7OH/H2O-LDH (191.2 mg g-1). The coordination-relative mineralization mechanism of Ca-based LDH was confirmed by both theoretical calculations and experimental results. The understanding of LDH materials and their possible use in environmental remediation are advanced by this research.
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The metal-catalyzed sulfur reaction in lithium-sulfur (Li-S) batteries usually suffers from the strong binding of sulfur species to the catalyst surface, which destroys the electric double layer (EDL) region there. This causes rapid catalyst deactivation because it prevents the desorption of sulfur species and mass transport through the EDL is hindered. This work introduces a competitive adsorption factor (fsulfur) as a new indicator to quantify the competitive adsorption of sulfur species in the EDL and proposes an alloying method to change it by strengthening the p-d hybridization of alloying metals with electrolyte solvents. A cobalt-zinc alloy catalyst with a moderate fsulfur lowers the activation energy of the rate-limiting step of the conversion of lithium polysulfides to lithium sulfide, giving a platform capacity proportion that is 96% of the theoretical value and has a greatly improved anti-passivation ability, especially at high sulfur loadings and lean electrolyte conditions (a low E/S ratio of 5 µL mgS -1). A pouch cell using this approach has a high energy density of up to 464 Wh kg-1. Such a competitive adsorption indicator and alloying strategy offer a new guideline for catalyst design and a practical electrocatalysis solution for Li-S batteries.
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BACKGROUND: MicroRNA (miRNA)-processing machinery may modify the risk of primary Sjögren's syndrome (pSS) by altering miRNA expression profiles. Inflammatory cytokines and reactive oxygen species (ROS) are also involved in pSS; however, the role of altered miRNAs expression in its pathogenesis is still unclear. We aimed to evaluate the relationship between single-nucleotide polymorphisms (SNPs) in miRNA processing machinery genes, including XPO5 (rs11077), RAN (rs14035), Dicer (rs3742330), TNRC6B (rs9623117), GEMIN3 (rs197412), and GEMIN4 (rs2740348), and the risk of pSS in female patients. The potential associations of cytokines and ROS with pSS-susceptible SNPs were also evaluated. MATERIALS AND METHODS: The SNPs confirmed by polymerase chain reaction ligase detection reaction were genotyped in 74 female patients with pSS and 77 controls. The relationship was analyzed by Student's t-test, Wilcoxon rank-sum test, chi-square test, Pearson's correlation test, and binary logistic regression analysis. RESULTS: For rs197412 of the GEMIN3 gene, the genotype TT carrier was associated with a 2.172-fold increased risk for pSS when compared with that of CT+CC carrier (odds ratio: 2.172, 95% CI, 1.133-4.166, p=0.019). Simultaneously, the pSS-susceptible TT carriers were associated with increased interferon-γ (IFN-γ) (P < 0.001) and tumor necrosis factor-α (TNF-α) (P = 0.003) levels when compared with that of CT+CC genotype carriers in female patients with pSS. The subsequent analysis also showed a weak positive correlation between IFN-γ and TNF-α levels (r=0.271, P = 0.019). CONCLUSION: The predictors of GEMIN3 SNPs might modify pSS development in females by mediating the expression of miRNAs and therefore regulate the levels of IFN-γ and TNF-α.
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Toxicity assessments of pollutants often overlook the impact of environmental factors like hypoxia, which can alter chemical toxicity with unexpected consequences. In this study, Mugilogobius chulae, an estuarine fish, was used to investigate the effects of hypoxia (H), aspirin (ASA), and their combination (H_ASA) exposure over 24, 72, and 168 h. We employed RNA-seq analysis, expression of key gene expression profiling, enzymatic activity assays, and histopathological and ultrastructural examinations of liver tissue to explore the effects and mechanisms of ASA-coupled hypoxia exposure in fish. Results showed that glycolysis was inhibited, and lipolysis was enhanced in ASA/H_ASA groups. The PPAR signaling pathway was activated, increasing fatty acid ß-oxidation and lipophagy to mitigate energy crisis. Both ASA and H_ASA exposures induced p53 expression and inhibited the TOR pathway to combat environmental stress. However, a greater energy demand and heightened sensitivity to ASA were observed in H_ASA compared to ASA exposure. Disruptions in energy and detoxification pathways led to increased stress responses, including enhanced antioxidant activities, autophagy, and apoptotic events, as observed in organelle structures. Overall, sub-chronic H_ASA exposure caused liver injury in M. chulae by affecting energy metabolism, antioxidant regulation, and autophagy processes. This study highlights the influence of hypoxia on ASA toxicity in fish, providing valuable insights for ecological risk assessment of NSAIDs.
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Antioxidantes , Aspirina , Autofagia , Metabolismo Energético , Hipoxia , Hígado , Contaminantes Químicos del Agua , Animales , Autofagia/efectos de los fármacos , Metabolismo Energético/efectos de los fármacos , Aspirina/toxicidad , Contaminantes Químicos del Agua/toxicidad , Hígado/efectos de los fármacos , Hígado/metabolismo , Hígado/patología , Antioxidantes/metabolismo , Perciformes/metabolismo , Enfermedad Hepática Inducida por Sustancias y Drogas/metabolismoRESUMEN
BACKGROUND: Approximately half of all patients with hepatocellular carcinoma (HCC) develop cachexia during the course of the disease. It is important to be able to predict which patients will develop cachexia at an early stage. PURPOSE: To develop and validate a nomogram based on the magnetic resonance imaging (MRI) features of HCC and body composition for potentially predicting cachexia in patients with HCC. MATERIAL AND METHODS: A retrospective two-center study recruited the pretreatment clinical and MRI data of 411 patients with HCC undergoing abdominal MRI. The data were divided into three cohorts for development, internal validation, and external validation. Patients were followed up for six months after the MRI scan to record each patient's weight to diagnose cachexia. Logistic regression analyses were performed to identify independent variables associated with cachexia in the development cohort used to build the nomogram. RESULTS: The multivariable analysis suggested that the MRI parameters of tumor size > 5â cm (P = 0.001), intratumoral artery (P = 0.004), skeletal muscle index (P < 0.001), and subcutaneous fat area (P = 0.004) were independent predictors of cachexia in patients with HCC. The nomogram derived from these parameters in predicting cachexia reached an area under receiver operating characteristic curve of 0.819, 0.783, and 0.814 in the development, and internal and external validation cohorts, respectively. CONCLUSION: The proposed multivariable nomogram suggested good performance in predicting the risk of cachexia in HCC patients.
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A stimulus can be familiar for multiple reasons. It might have been recently encountered, or is similar to recent experience, or is similar to 'typical' experience. Understanding how the brain translates these sources of similarity into memory decisions is a fundamental, but challenging goal. Here, using fMRI, we computed neural similarity between a current stimulus and events from different temporal windows in the past and future (from seconds to days). We show that trial-by-trial memory decisions (is this stimulus 'old'?) were predicted by the difference in similarity to past vs. future events (temporal asymmetry). This relationship was (i) evident in lateral parietal and occipitotemporal cortices, (ii) strongest when considering events from the recent past (minutes ago), and (iii) most pronounced when veridical (true) memories were weak. These findings suggest a new perspective in which the brain supports memory decisions by comparing what actually occurred to what is likely to occur.
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Heterogeneous catalysis promises to accelerate sulfur-involved conversion reactions in lithium-sulfur batteries. Solid-state Li2S dissociation remains as the rate-limiting step because of the weakly matched solid-solid electrocatalysis interfaces. We propose an electrochemically molecular-imprinting strategy to have a metal sulfide (MS) catalyst with imprinted defects in positions from which the pre-implanted Li2S has been electrochemically removed. Such tailor-made defects enable the catalyst to bind exclusively to Li atoms in Li2S reactant and elongate the Li-S bond, thus decreasing the reaction energy barrier during charging. The imprinted Ni3S2 catalyst shows the best activity due to the highest defect concentration among the MS catalysts examined. The Li2S oxidation potential is substantially reduced to 2.34 V from 2.96 V for the counterpart free of imprinted vacancies, and an Ah-level pouch cell is realized with excellent cycling performance. With a lean electrolyte/sulfur ratio of 1.80 µL mgS -1, the cell achieves a benchmarkedly high energy density beyond 500 Wh kg-1.
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PURPOSE: Tumor-associated macrophages (TAMs) play a critical role in hepatocellular carcinoma (HCC) progression and metastasis. Systematic investigation of the cross-talk between TAMs and HCC may help in searching for the critical target to guard against HCC metastasis. METHODS AND RESULTS: Herein, we found that TREM1 highly expressed in HCC tissue by analyzing the data obtain from GEO database. Interestingly, the results indicated that TREM1 was primarily expressed by monocytes. Immune infiltration studies further validated that TREM1 expression was positively related with increased infiltration of macrophages in HCC tissues. In vitro, we observed that TREM1 knockdown significantly abrogated the effect of TAMs in promoting the metastasis and epithelial-mesenchymal transition (EMT) of HCC cells. Additionally, cytokine array detection identified CCL7 as the main responsive cytokine following with TREM1 knockdown in TAMs. CONCLUSION: Taken together, our findings strongly suggested that high expression of TREM1 was positively associated with metastasis and poor prognosis of HCC. Furthermore, TAMs expressing TREM1 contribute to EMT-based metastasis through secreting CCL7. These results provide a novel insight into the potential development of targeting the TREM1/CCL7 pathway for preventing metastatic HCC.
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Carcinoma Hepatocelular , Transición Epitelial-Mesenquimal , Neoplasias Hepáticas , Receptor Activador Expresado en Células Mieloides 1 , Femenino , Humanos , Masculino , Carcinoma Hepatocelular/patología , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/metabolismo , Línea Celular Tumoral , Neoplasias Hepáticas/patología , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/metabolismo , Metástasis de la Neoplasia , Pronóstico , Receptor Activador Expresado en Células Mieloides 1/metabolismo , Receptor Activador Expresado en Células Mieloides 1/genética , Macrófagos Asociados a Tumores/metabolismo , Macrófagos Asociados a Tumores/inmunología , Macrófagos Asociados a Tumores/patologíaRESUMEN
Background: The genus Helius Lepeletier & Serville, 1828 is globally distributed with 232 species and subspecies, of which 25 have been known to occur in China. Amongst the Chinese Helius crane flies, 24 species are distributed in southern China. The species diversity of Helius in other Chinese regions may be severely underestimated due to a lack of investigation. Some investigations on crane flies in Inner Mongolia, China have been initiated by the authors together with other entomologists, with Helius being one of the key targets of attention. New information: Two Helius species, H. (Helius) flavus (Walker, 1856) and H. (H.) gracillimus Alexander, 1938, are added to the Chinese fauna. The two newly-recorded species also represent the first records of the crane fly tribe Elephantomyiini in Inner Mongolia. Re-descriptions and illustrations of the two newly-recorded species are presented.
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Part-set cuing facilitation and impairment effects are rarely found in spatial memory, which is a challenge to the theories of part-set cuing effects based on lexical stimulus. This study aims to investigate whether there part-set cuing facilitation and impairment effects are present in spatial memory by constructing two types of memory scenes with high and low degrees of interitem associations, achieved by manipulating the presentation of miniatures. This study examined the effects of different part-set cues on free recall, recognition, and reconstruction tasks. The results of two experiments revealed that matrix cues impaired the performance of three recall tasks in memory scenes with a high degree of interitem associations, and scene cues facilitated the reconstruction performance (Experiment 1). Conversely, in memory scenes with a low degree of interitem associations, the impairment effect of matrix cues was not observed in the three recall tasks, but scene cues still facilitated the reconstruction performance (Experiment 2). These findings supported the retrieval strategy disruption hypothesis, the two-mechanism and the multi-mechanism accounts, demonstrating the significance of interitem associations in spatial memory. Furthermore, the results provided direct evidence for the importance of the encoding-retrieval strategy matching principle in spatial memory tasks.
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Catalysis is crucial to improve redox kinetics in lithium-sulfur (Li-S) batteries. However, conventional catalysts that consist of a single metal element are incapable of accelerating stepwise sulfur redox reactions which involve 16-electron transfer and multiple Li2Sn (n = 2-8) intermediate species. To enable fast kinetics of Li-S batteries, it is proposed to use high-entropy alloy (HEA) nanocatalysts, which are demonstrated effective to adsorb lithium polysulfides and accelerate their redox kinetics. The incorporation of multiple elements (Co, Ni, Fe, Pd, and V) within HEAs greatly enhances the catalytically active sites, which not only improves the rate capability, but also elevates the cycling stability of the assembled batteries. Consequently, HEA-catalyzed Li-S batteries achieve a high capacity up to 1364 mAh g-1 at 0.1 C and experience only a slight capacity fading rate of 0.054% per cycle over 1000 cycles at 2 C, while the assembled pouch cell achieves a high specific capacity of 1192 mAh g-1. The superior performance of Li-S batteries demonstrates the effectiveness of the HEA catalysts with maximized synergistic effect for accelerating S conversion reactions, which opens a way to catalytically improving stepwise electrochemical conversion reactions.
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Near-infrared light-driven photocatalytic CO2 reduction (NIR-CO2PR) holds tremendous promise for the production of valuable commodity chemicals and fuels. However, designing photocatalysts capable of reducing CO2 with low energy NIR photons remains challenging. Herein, a novel NIR-driven photocatalyst comprising an anionic Ru complex intercalated between NiAl-layered double hydroxide nanosheets (NiAl-Ru-LDH) is shown to deliver efficient CO2 photoreduction (0.887â µmol h-1) with CO selectivity of 84.81 % under 1200â nm illumination and excellent stability over 50 testing cycles. This remarkable performance results from the intercalated Ru complex lowering the LDH band gap (0.98â eV) via a compression-related charge redistribution phenomenon. Furthermore, transient absorption spectroscopy data verified light-induced electron transfer from the Ru complex towards the LDH sheets, increasing the availability of electrons to drive CO2PR. The presence of hydroxyl defects in the LDH sheets promotes the adsorption of CO2 molecules and lowers the energy barriers for NIR-CO2PR to CO. To our knowledge, this is one of the first reports of NIR-CO2PR at wavelengths up to 1200â nm in LDH-based photocatalyst systems.
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The application of supramolecular assembly (SA) with room temperature phosphorescence (RTP) in aqueous phase has the potential to revolutionize numerous fields. However, using simple molecules with crystalline RTP to construct SA with aqueous phase RTP is hardly possible from the standpoint of forces. The reason lies in that the transition from crystal to SA involves a structure transformation from highly stable to more dynamic state, leading to increased non-radiative deactivation pathways and silent RTP signal. Here, with the benefit of the confinement from the layered double hydroxide (LDH), various simple molecules (benzene derivatives) can successfully form metastable SA with aqueous phase RTP. The maximum of RTP lifetime and efficiency can reach 654.87â ms and 5.02 %, respectively. Mechanistic studies reveal the LDH energy trap can strengthen the intermolecular interaction, providing the prerequisite for the existence of metastable SA and appearance of aqueous phase RTP. The universality of this strategy will usher exploration into other multifunctional monomer, facilitating the development of SAs with aqueous phase RTP.
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Some aplastic anemia(AA) patients only have partial hematological responses after immunosuppressive therapy. Failure to achieve complete normalization of blood counts, particularly hemoglobin, will reduce their quality of life. This open-label pilot study was conducted to evaluate the efficacy and safety of roxadustat in this setting. A total of 14 patients with AA who had inadequate erythroid response after immunosuppressive therapy were included in the study. The primary efficacy endpoint was hemoglobin response at week 8 after roxadustat treatment. The median duration of roxadustat therapy was 14 (4-30) weeks, with 12 patients receiving roxadustat for ≥ 8 weeks. At week 8, nine patients (9/14, 64.3%) had their hemoglobin rising for at least 15 g/L, with two patients (2/14, 14.3%) achieving normal hemoglobin levels. By the last follow-up, hemoglobin responses were observed in 10 patients (10/14, 71.4%), with 4 patients(4/14, 28.6%) having normal hemoglobin levels. Roxadustat was tapered or discontinued in four responded patients; one relapsed after 12 weeks of tapering, and three maintained their response. Four patients (4/14, 28.6%) experienced mild adverse effects during therapy. Roxadustat is safe and well tolerated by patients with AA. Treatment with the hypoxia-inducible factor prolyl hydroxylase inhibitor improves hemoglobin levels in AA patients with inadequate erythroid responses.
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Anemia Aplásica , Glicina , Isoquinolinas , Humanos , Masculino , Femenino , Adulto , Persona de Mediana Edad , Proyectos Piloto , Isoquinolinas/uso terapéutico , Isoquinolinas/efectos adversos , Isoquinolinas/administración & dosificación , Anemia Aplásica/tratamiento farmacológico , Anemia Aplásica/sangre , Glicina/análogos & derivados , Glicina/uso terapéutico , Glicina/efectos adversos , Anciano , Hemoglobinas/análisis , Resultado del Tratamiento , Adulto Joven , Datos Preliminares , AdolescenteRESUMEN
PURPOSE: This study aimed to assess the predictive efficacy of intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in parametrial invasion (PMI) in cervical cancer patients. METHODS: A total of 83 cervical cancer patients (32 PMI-positive and 51 PMI-negative) retrospectively underwent pretreatment IVIM-DWI and DCE-MRI scans. IVIM-DWI parameters included apparent diffusion coefficient (ADC), slow apparent diffusion coefficient (D), fast apparent diffusion coefficient (D*), and perfusion fraction (f). DCE-MRI parameters included volume transfer constant (Ktrans), flux rate constant (Kep), and fractional extravascular extracellular space volume (Ve). Logistic regression analyses were conducted to identify independent variables associated with PMI. Receiver operating characteristic curves were generated to assess the predictive performance of significant parameters. RESULTS: Multivariable analysis revealed that the MRI parameters D (odds ratio [OR]: 7.05; 95% CI 1.78-27.88; P = 0.005), D* (OR 6.58; 95% CI 1.49-29.10; P = 0.01), f (OR 5.12; 95% CI 1.23-21.37; P = 0.03), Ktrans (OR 4.60; 95% CI 1.19-17.81; P = 0.03), and Kep (OR 4.90; 95% CI 1.25-19.18; P = 0.02) were independent predictors of PMI in cervical cancer patients. The combined parameter incorporating these parameters demonstrated the highest performance in predicting PMI, yielding an area under the curve of 0.906, sensitivity of 84.4%, and specificity of 86.3%. CONCLUSION: The proposed combined parameter exhibited favorable performance in identifying PMI in cervical cancer patients.
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Medios de Contraste , Imagen de Difusión por Resonancia Magnética , Invasividad Neoplásica , Neoplasias del Cuello Uterino , Humanos , Femenino , Neoplasias del Cuello Uterino/diagnóstico por imagen , Neoplasias del Cuello Uterino/patología , Imagen de Difusión por Resonancia Magnética/métodos , Persona de Mediana Edad , Estudios Retrospectivos , Adulto , Imagen por Resonancia Magnética/métodos , Anciano , Valor Predictivo de las Pruebas , Interpretación de Imagen Asistida por Computador/métodos , Aumento de la Imagen/métodosRESUMEN
Bimetallic alloy nanoparticles have garnered substantial attention for diverse catalytic applications owing to their abundant active sites and tunable electronic structures, whereas the synthesis of ultrafine alloy nanoparticles with atomic-level homogeneity for bulk-state immiscible couples remains a formidable challenge. Herein, we present the synthesis of RuxCo1-x solid-solution alloy nanoparticles (ca. 2 nm) across the entire composition range, for highly efficient, durable, and selective CO2 hydrogenation to CH4 under mild conditions. Notably, Ru0.88Co0.12/TiO2 and Ru0.74Co0.26/TiO2 catalysts, with 12 and 26 atom % of Ru being substituted by Co, exhibit enhanced catalytic activity compared with the monometallic Ru/TiO2 counterparts both in dark and under light irradiation. The comprehensive experimental investigations and density functional theory calculations unveil that the electronic state of Ru is subtly modulated owing to the intimate interaction between Ru and Co in the alloy nanoparticles, and this effect results in the decline in the CO2 conversion energy barrier, thus ultimately culminating in an elevated catalytic performance relative to monometallic Ru and Co catalysts. In the photopromoted thermocatalytic process, the photoinduced charge carriers and localized photothermal effect play a pivotal role in facilitating the chemical reaction process, which accounts for the further boosted CO2 methanation performance.
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Evaluating the impact of global warming on rice production and greenhouse gas (GHG) emissions is critical for ensuring food security and mitigating the consequences of climate change. Nonetheless, the impacts of warming on crop production, GHG emissions, and microbial mechanisms in the single-cropping rice systems remain unclear. Here, a two-year field experiment was conducted to explore the effects of warming (increased by 2.7-3.0 °C on average) in the rice growing season on crop production and functional microorganisms associated with GHG emissions. Results showed that warming resulted in significant reduction (p < 0.01) in the aboveground biomass and grain yield as well as in grain weight, the number of spikelets per panicle, and the seed-setting rate. However, it caused a significant increase (p < 0.01) in the number of panicles by 15.6 % and 34.9 %, respectively. Furthermore, warming significantly increased (p < 0.01) seasonal methane (CH4) emissions but reduced nitrous oxide (N2O) emissions, particularly in 2022.The relative abundance of genes associated with CH4 metabolism and nitrogen metabolism was increased by 40.7 % and 32.7 %, respectively, in response to warming. Moreover, warming had a positive impact on the abundance of genes related to CH4 production and oxidation processes but did not affect the denitrification processes associated with N2O production. These results showed that warming decreased rice yield and biomass in the single cropping rice system but increased CH4 emissions and global warming potential. Taken together, to address the increasing food demand of a growing population and mitigate the impacts of global warming, it is imperative to duce GHG emissions and enhance crop yields.
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Gases de Efecto Invernadero , Oryza , Gases de Efecto Invernadero/análisis , Oryza/metabolismo , Agricultura/métodos , Calentamiento Global , Producción de Cultivos , Óxido Nitroso/análisis , Metano/análisis , Suelo , ChinaRESUMEN
Atorvastatin (ATV) is one of the most commonly prescribed lipid-lowering drugs detected frequently in the environment due to its high use and low degradation rate. However, the toxic effects of residual ATV in the aquatic environment on non-target organisms and its toxic mechanisms are still largely unknown. In the present study, embryos of a native estuarine benthic fish, Mugilogobius chulae, were employed to investigate the developmental and behavioral toxic effects of ATV including environmentally relevant concentrations. The aim of this study was to provide a scientific basis for ecological risk assessment of ATV in the aquatic environment by investigating the changes of biological endpoints at multiple levels in M. chulae embryos/larvae. The results showed that ATV had significantly lethal and teratogenic effects on M. chulae embryos/larvae and caused abnormal changes in developmental parameters including hatch rate, body length, heart rate, and spontaneous movement. ATV exposure caused oxidative stress in M. chulae embryos/larvae subsequently inhibited autophagy and activated apoptosis, leading to abnormal developmental processes and behavioral changes in M. chulae embryos/larvae. The disruptions of lipid metabolism, autophagy, and apoptosis in M. chulae embryos/larvae caused by ATV exposure may pose a potential ecological risk at the population level.
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Atorvastatina , Autofagia , Embrión no Mamífero , Larva , Metabolismo de los Lípidos , Perciformes , Contaminantes Químicos del Agua , Animales , Atorvastatina/toxicidad , Contaminantes Químicos del Agua/toxicidad , Embrión no Mamífero/efectos de los fármacos , Metabolismo de los Lípidos/efectos de los fármacos , Autofagia/efectos de los fármacos , Larva/efectos de los fármacos , Conducta Animal/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Apoptosis/efectos de los fármacos , Desarrollo Embrionario/efectos de los fármacosRESUMEN
The exploration of powerful, efficient and precious metal-free electrocatalysts for facilitating the sluggish kinetics of the oxygen reduction reaction (ORR) is a crucial endeavor in the development and application of energy conversion and storage devices. Herein, we have rationally designed and synthesized bimetallic CoFe species consisting of CoFe nanoparticles and atomically dispersed dual atoms anchored on an ordered mesoporous carbon matrix (CoFe/NC) as highly efficient ORR electrocatalysts. The pyrolyzation temperature for CoFe/NC plays a vital role in regulating the morphology and composition of both the carbon matrix and CoFe species. The optimized CoFe/NC-750 exhibits a favorable ORR performance in 0.1 M KOH with a high half-wave potential (E1/2) of 0.87 V vs. RHE, excellent tolerance to methanol and remarkable durability (no obvious decrease in E1/2 value after 3000 cycles), all of which are superior to the performance of commercial Pt/C. Experimental measurements and density functional theory (DFT) calculations reveal that the improved ORR performance of CoFe/NC-750 is mainly attributed to the electronic structure of atomically dispersed Fe active sites modulated by the surrounding CoFe alloys and Co single atoms, which accelerates the dissociation and reduction of intermediate OH* species and promotes the ORR process.