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1.
Nat Immunol ; 22(9): 1118-1126, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34326534

RESUMO

Transcription factors specialized to limit the destructive potential of inflammatory immune cells remain ill-defined. We discovered loss-of-function variants in the X-linked ETS transcription factor gene ELF4 in multiple unrelated male patients with early onset mucosal autoinflammation and inflammatory bowel disease (IBD) characteristics, including fevers and ulcers that responded to interleukin-1 (IL-1), tumor necrosis factor or IL-12p40 blockade. Using cells from patients and newly generated mouse models, we uncovered ELF4-mutant macrophages having hyperinflammatory responses to a range of innate stimuli. In mouse macrophages, Elf4 both sustained the expression of anti-inflammatory genes, such as Il1rn, and limited the upregulation of inflammation amplifiers, including S100A8, Lcn2, Trem1 and neutrophil chemoattractants. Blockade of Trem1 reversed inflammation and intestine pathology after in vivo lipopolysaccharide challenge in mice carrying patient-derived variants in Elf4. Thus, ELF4 restrains inflammation and protects against mucosal disease, a discovery with broad translational relevance for human inflammatory disorders such as IBD.


Assuntos
Proteínas de Ligação a DNA/genética , Doenças Hereditárias Autoinflamatórias/genética , Doenças Inflamatórias Intestinais/genética , Macrófagos/imunologia , Fatores de Transcrição/genética , Animais , Calgranulina A/metabolismo , Feminino , Regulação da Expressão Gênica/genética , Doenças Hereditárias Autoinflamatórias/imunologia , Doenças Hereditárias Autoinflamatórias/patologia , Humanos , Doenças Inflamatórias Intestinais/imunologia , Doenças Inflamatórias Intestinais/patologia , Proteína Antagonista do Receptor de Interleucina 1/imunologia , Lipocalina-2/metabolismo , Lipopolissacarídeos/toxicidade , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Células Th17/imunologia , Transcrição Gênica/genética , Receptor Gatilho 1 Expresso em Células Mieloides/antagonistas & inibidores , Receptor Gatilho 1 Expresso em Células Mieloides/metabolismo
2.
Proc Natl Acad Sci U S A ; 120(14): e2216231120, 2023 04 04.
Artigo em Inglês | MEDLINE | ID: mdl-36976764

RESUMO

Histamine is a conserved neuromodulator in mammalian brains and critically involved in many physiological functions. Understanding the precise structure of the histaminergic network is the cornerstone in elucidating its function. Herein, using histidine decarboxylase (HDC)-CreERT2 mice and genetic labeling strategies, we reconstructed a whole-brain three dimensional (3D) structure of histaminergic neurons and their outputs at 0.32 × 0.32 × 2 µm3 pixel resolution with a cutting-edge fluorescence microoptical sectioning tomography system. We quantified the fluorescence density of all brain areas and found that histaminergic fiber density varied significantly among brain regions. The density of histaminergic fiber was positively correlated with the amount of histamine release induced by optogenetic stimulation or physiological aversive stimulation. Lastly, we reconstructed a fine morphological structure of 60 histaminergic neurons via sparse labeling and uncovered the largely heterogeneous projection pattern of individual histaminergic neurons. Collectively, this study reveals an unprecedented whole-brain quantitative analysis of histaminergic projections at the mesoscopic level, providing a foundation for future functional histaminergic study.


Assuntos
Encéfalo , Histamina , Camundongos , Animais , Encéfalo/metabolismo , Neurônios/metabolismo , Mapeamento Encefálico , Histidina Descarboxilase/genética , Histidina Descarboxilase/metabolismo , Mamíferos/metabolismo
3.
Chemphyschem ; 25(8): e202300897, 2024 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-38323673

RESUMO

As a photocathode with a band gap of about 1.8 eV, copper bismuthate (CuBi2O4) is a promising material for photoelectrochemical (PEC) water splitting. However, weak charge transfer capability and severe carrier recombination suppress the PEC performance of CuBi2O4. In this paper, the conductivity and carriers transport of CuBi2O4 are improved via introducing Zn2+ into the synthesis precursor of CuBi2O4, driving a beneficial 110 mV positive shift of onset potential in photocurrent. Detailed investigations demonstrate that the introduction of an appropriate amount of zinc leads to in situ segregation of ZnO which serves as an electron transport channel on the surface of CuBi2O4, forming heterojunctions. The synergistic effect of heterojunctions and doping simultaneously promotes the charge transfer and the carrier concentration. OCP experiment proves that ZnO/Zn-CuBi2O4 possesses better charge separation; the Mott-Schottky curve shows that the doping of Zn significantly enhances the carrier concentration; carrier lifetime calculated from time-resolved photoluminescence confirms faster extraction of carriers.

4.
J Org Chem ; 89(3): 1633-1647, 2024 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-38235569

RESUMO

A metal-free and atom-economic route for the synthesis of naphtho[1,2-b]furan-3-ones has been realized via p-TsOH·H2O-catalyzed intramolecular tandem double cyclization of γ-hydroxy acetylenic ketones with alkynes in formic acid. The benzene-linked furanonyl-ynes are the key intermediates obtained by the scission/recombination of C-O double bonds. Further, the structural modifications of the representative product were implemented by reduction, demethylation, substitution, and [5 + 2]-cycloaddition.

5.
J Am Chem Soc ; 145(32): 17995-18006, 2023 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-37550082

RESUMO

The acidic oxygen evolution reaction (OER) has long been the bottleneck of proton exchange membrane water electrolyzers given its harsh oxidative and corrosive environments. Herein, we suggest an effective strategy to greatly enhance both the acidic OER activity and stability of Co3O4 spinel by atomic Ru selective substitution on the octahedral Co sites. The resulting highly symmetrical octahedral Ru-O-Co collaborative coordination with strong electron coupling effect enables the direct dioxygen radical coupling OER pathway. Indeed, both experiments and theoretical calculations reveal a thermodynamically breakthrough heterogeneous diatomic oxygen mechanism. Additionally, the active Ru-O-Co units are well-maintained upon the acidic OER thanks to the electron transfer from surrounding electron-enriched tetrahedral Co atoms via bridging oxygen bonds that suppresses the overoxidation and thus dissolution of active Ru and Co species. Consequently, the prepared catalyst, even with a low Ru mass loading of ca. 42.8 µg cm-2, exhibits an attractive acidic OER performance with a low overpotential of 200 mV and a low potential decay rate of 0.45 mV h-1 at 10 mA cm-2. Our work suggests an effective strategy to significantly enhance both the acidic OER activity and stability of low-cost electrocatalysts.

6.
Artigo em Inglês | MEDLINE | ID: mdl-35957537

RESUMO

OBJECTIVE: This meta-analytic study examined the effects of exercise training on depressive symptoms in mild stroke patients and the moderating effects of exercise type, therapeutic method, culture, sex, and gross domestic product (GDP) in the patient's country. METHODS: The Metafor package in R was chosen to conduct the meta-analysis, and the quality of each empirical study was evaluated according to the grading system in Cochrane. We included 36 empirical studies and 1477 patients. RESULTS: The results showed that the treatment effect of exercise training on depression in mild stroke patients was significant. The moderating effects of culture and therapeutic method were significant, but not for exercise type, sex, or GDP in the patient's country. The moderating effect of culture can be explained by the therapeutic method in different cultures. CONCLUSION: Fitness exercise is an effective method for improving depressive symptoms in mild stroke patients. Its effectiveness is moderated by the therapeutic method but is not affected by demographics, exercise type, gender, or GDP level.


Assuntos
Depressão , Acidente Vascular Cerebral , Idoso , Depressão/etiologia , Depressão/terapia , Exercício Físico , Terapia por Exercício/métodos , Humanos , Pessoa de Meia-Idade , Acidente Vascular Cerebral/complicações
7.
Nano Lett ; 21(21): 9233-9239, 2021 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-34709835

RESUMO

Understanding quantum tunneling principles over two-dimensional (2D) van der Waals (vdW) ferromagnets at the atomic level is essential and complementary to the fundamental study of low-dimensional strong correlated systems and is critical for the development of magnetic tunneling devices. Here, we demonstrate a local electric-field controlled negative differential conductance (NDC) in 2D vdW ferromagnet Fe3GeTe2 (FGT) by using scanning tunneling microscopy (STM). The STM reveals that NDC shows an atomic position dependence and can be precisely modulated by altering the tunneling junction. The band shift together with electric-field-driven 3d-orbital occupancy modulates the sensitive magnetic anisotropic energy (MAE) in 2D FGT and consequently leads to electric-field-tunable NDC, which is also verified by theoretical simulation. This work realizes the electric-field-driven NDC in 2D ferromagnet FGT, which paves a way to design and develop applications based on 2D vdW magnets.

8.
Nano Lett ; 21(14): 6117-6123, 2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34279960

RESUMO

Heavy Fermion (HF) states emerge in correlated quantum materials due to the intriguing interplay between localized magnetic moments and itinerant electrons but rarely appear in 3d-electron systems due to high itinerancy of d-electrons. Here, an anomalous enhancement of Kondo screening is observed at the Kondo hole of local Fe vacancies in Fe3GeTe2 which is a recently discovered 3d-HF system featuring Kondo lattice and two-dimensional itinerant ferromagnetism. An itinerant Kondo-Ising model is established to reproduce the experimental results and provides insight into the competition between Ising ferromagnetism and Kondo screening. Our work explains the microscopic origin of the d-electron HF states in Fe3GeTe2 and inspires future studies of the enriched quantum many-body effects with Kondo holes.

9.
Small ; 17(9): e1903769, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31531941

RESUMO

A moiré pattern results from the projection of one periodic pattern to another with relative lattice constant or misalignment and provides great periodic potential to modify the electronic properties of pristine materials. In this Review, recent research on the effect of the moiré superlattice on the electronic structures of graphene and silicene, both of which possess a honeycomb lattice, is focused on. The moiré periodic potential is introduced by the interlayer interaction to realize abundant phenomena, including new generation of Dirac cones, emergence of Van Hove singularities (vHs) at the cross point of two sets of Dirac cones, Mott-like insulating behavior at half-filling state, unconventional superconductivity, and electronic Kagome lattice and flat band with nontrivial edge state. The role of interlayer coupling strength, which is determined by twist angle and buckling degree, in these exotic properties is discussed in terms of both the theoretical prediction and experimental measurement, and finally, the challenges and outlook for this field are discussed.

10.
Entropy (Basel) ; 23(8)2021 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-34441123

RESUMO

A distributed arithmetic coding algorithm based on source symbol purging and using the context model is proposed to solve the asymmetric Slepian-Wolf problem. The proposed scheme is to make better use of both the correlation between adjacent symbols in the source sequence and the correlation between the corresponding symbols of the source and the side information sequences to improve the coding performance of the source. Since the encoder purges a part of symbols from the source sequence, a shorter codeword length can be obtained. Those purged symbols are still used as the context of the subsequent symbols to be encoded. An improved calculation method for the posterior probability is also proposed based on the purging feature, such that the decoder can utilize the correlation within the source sequence to improve the decoding performance. In addition, this scheme achieves better error performance at the decoder by adding a forbidden symbol in the encoding process. The simulation results show that the encoding complexity and the minimum code rate required for lossless decoding are lower than that of the traditional distributed arithmetic coding. When the internal correlation strength of the source is strong, compared with other DSC schemes, the proposed scheme exhibits a better decoding performance under the same code rate.

11.
Phys Chem Chem Phys ; 19(21): 13515-13523, 2017 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-28497833

RESUMO

Tautomerism in nucleotide bases is one of the possible mechanisms of DNA mutation. In spite of numerous studies on the structure and energy of protonated cytosine tautomers, little information is available on the process of their intra- and intermolecular tautomerizations. The catalytic ability of H2O, HCOOH, and the HCOOHH2O group to facilitate the tautomerism of the Cyt2t+ to CytN3+ isomer has been studied. It is shown that the activation free energies of tautomerism in the gas phase are 161.17, 58.96, 26.06, and 15.69 kJ mol-1, respectively, when the reaction is carried out in the absence and presence of H2O, HCOOH, or the HCOOHH2O group. The formation of a doubly hydrogen bonded transition state is central to lowering the activation free energy and facilitating the intramolecular hydrogen atom transfer that is required for isomerization. In the aqueous phase, although the solvent effects of water significantly decrease the activation free energy of intramolecular tautomerization, the isomerization of the Cyt2t+ to CytN3+ isomer remains unfavorable, and the HCOOH and HCOOHH2O group mediated mechanisms are still more favorable. Meanwhile, conventional transition state theory (CTST) followed by Wigner tunneling correction is then applied to estimate the rate constants. The rate constant with Wigner tunneling correction for direct tautomerization is obviously smaller than that of HCOOH-mediated tautomerization, which is the most plausible mechanism. Finally, another important finding is that the product complex (CytN3+HCOOH) is in the rapid tautomeric equilibrium with the reaction complex (Cyt2t+HCOOH) (τ99.9% = 3.84 × 10-12 s), which is implemented by the mechanism of the concerted synchronous double proton transfer. Its lifetime of the formed CytN3+HCOOH complex (τ = 8.33 × 10-9 s) is almost one order of magnitude larger than the time required for the replication machinery to forcibly dissociate a base pair into the monomers during DNA replication (several ns), which is further dissociated into the CytN3+ and HCOOH monomers. The results of the present study demonstrate the feasibility of acid catalysis for DNA base isomerization reactions that would otherwise be forbidden.


Assuntos
Citosina/química , Formiatos/química , Catálise , Isomerismo , Cinética , Modelos Químicos , Estrutura Molecular , Água/química
12.
Phys Chem Chem Phys ; 19(48): 32741, 2017 12 13.
Artigo em Inglês | MEDLINE | ID: mdl-29199299

RESUMO

Correction for 'Formic acid catalyzed isomerization of protonated cytosine: a lower barrier reaction for tautomer production of potential biological importance' by Lingxia Jin et al., Phys. Chem. Chem. Phys., 2017, 19, 13515-13523.

13.
Zhejiang Da Xue Xue Bao Yi Xue Ban ; 44(5): 511-6, 2015 09.
Artigo em Chinês | MEDLINE | ID: mdl-26713525

RESUMO

OBJECTIVE: To construct the expression vector pLCK-CD69-IRES-EGFP that contains mouse cell surface activation protein CD69 and enhanced green fluorescent protein(EGFP),and to generate CD69 transgenic mice based on this vector. METHODS: First, RNA was extracted from mouse lung tissue and cDNA was synthesized via reverse transcription. PCR primer was designed through the PubMed searching, then mouse CD69 DNA fragment was amplified with PCR. Second, this DNA fragment was subcloned to the pInsulater-LCK-IRES-EGFP plasmid and constructed the transgenic vector after the verification of nucleotide sequence. Third, the expression vector was then transfected into 293 T cells and its expression in 293 T cells was observed under fluorescence microscope. Last, microinjection was performed to transfer the expression vector pLCK-CD69-IRES-EGFP into fertilized eggs, which were implanted into pseudo-pregnant recipient mice. After birth the tail samples of the pups were obtained for the purpose of genotyping to determine the transgenic founders. Fluorescence microscope and flow cytometer were used to measure the expression of CD69 on cells. RESULTS: The construction of the expression vector pLCK-CD69-IRES-EGFP was verified by enzyme digestion and DNA sequencing. The transfected 293 T cell showed expression of the protein under fluorescence microscope. Identification of PCR for the tail tissue of the pups confirmed the present of CD69 transgene and resting lymphocytes demonstrated the expression of CD69. CONCLUSION: The construction of expression vector pLCK-CD69-IRES-EGFP and generation of CD69 transgenic mice have been successfully processed, which lays a foundation of the solid pattern studies in inflammatory diseases.


Assuntos
Antígenos CD/genética , Antígenos de Diferenciação de Linfócitos T/genética , Vetores Genéticos , Lectinas Tipo C/genética , Camundongos Transgênicos , Animais , DNA Complementar , Genótipo , Proteínas de Fluorescência Verde/genética , Camundongos , Plasmídeos , Reação em Cadeia da Polimerase , Análise de Sequência de DNA , Transfecção
14.
Data Brief ; 52: 109981, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38152489

RESUMO

Understanding neural mechanisms in design and creativity processes remains a challenging endeavor. To address this gap, we present two electroencephalography (EEG) datasets recorded in design and creativity experiments. We have discussed the details, similarities, differences, and corresponding cognitive tasks of the two datasets in the following sections. The design dataset (Dataset A) comprises EEG recordings of 27 participants during loosely controlled design creation experiments. Each experiment included six design problems. In each design problem, participants performed five cognitive tasks, including problem understanding, idea generation, rating idea generation, idea evaluation, and rating idea evaluation. The NASA Task Load Index was used in rating tasks. The creativity dataset (Dataset B) includes EEG signals recorded from 28 participants in creativity experiments which were based on a modified variant of the Torrance Test of Creative Thinking (TTCT-F). Participants were presented with three incomplete sketches and were asked to perform three creativity tasks for each sketch: idea generation, idea evolution, and idea evaluation. In both datasets, we structured the experiments into predefined steps, primarily to ensure participants' comfort and task clarity. This was the only control applied to the experiments. All the tasks were loosely controlled: open-ended (up to 3 min) and self-paced. 64-channel EEG signals were recorded at 500 Hz based on the international 10-10 system by the Brain Vision EEG recording system while the participants were performing their assigned tasks. EEG channels were pre-processed and finally referenced to the Cz channel to remove artifacts. EEGs were pre-processed using popular pipelines widely used in previous studies. Preprocessed EEG signals were finally segmented according to the tasks to facilitate future analyses. The EEG signals are stored in the .mat format. While the present paper mainly addresses pre-processed datasets, it also cites raw EEG recordings in the following sections. We aim to promote research and facilitate the development of experimental protocols and methodologies in design and creativity cognition by sharing these resources. There exist important points regarding the datasets which are worth mentioning. These datasets represent a novel contribution to the field, offering insights into design and creativity neurocognition. To our knowledge, publicly accessible datasets of this nature are scarce, and, to the best of our knowledge, our datasets are the first publicly available ones in design and creativity. Researchers can utilize these datasets directly or draw upon the considerations and technical insights provided to inform their studies. Furthermore, we introduce the concept of loosely controlled cognitive experiments in design and creativity cognition. These experiments strike a balance between flexibility and control, allowing participants to incubate creative ideas over extended response times while maintaining structured experimental sections. Such an approach fosters more natural data recording procedures and holds the potential to enhance the accuracy and reliability of future studies. The loosely controlled approach can be employed in future cognitive studies. This paper also conducts a comparative analysis of the two datasets, offering a holistic view of design and creativity tasks. By exploring various aspects of these cognitive processes, we provide an understanding for future researchers.

15.
Environ Sci Pollut Res Int ; 31(19): 27689-27698, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38519614

RESUMO

Cruciferae brassica oilseed rape is the third largest oilseed crop in the world and the first in China, as well as a fertilizer-dependent crop. With the increased application of organic fertilizers from livestock manure in agricultural production in recent years, the resulting antibiotic pollution and its ecological health effects have attracted widespread attention. In this study, typical tetracycline and sulfonamide antibiotics tetracycline (TC) and sulfamethoxazole (SMZ) were used to investigate the effects of antibiotics on rapeseed quality and oxidative stress at the level of secondary metabolism on the basis of examining the effects of the two drugs on the growth of soil-cultivated rapeseed seedlings. The results showed that both plant height and biomass of rapeseed seedlings were significantly suppressed and ROS were significantly induced in rapeseed by exposure to high concentrations (2.5 mg/kg) of TC and SMZ. Carotenoids, tocopherols, and SOD enzymes were involved in the oxidative stress response to scavenge free radicals in rapeseed, but phenolic acids and flavonoids contents were decreased, which reduced the quality of the seeds to some extent.


Assuntos
Antibacterianos , Estresse Oxidativo , Sementes , Estresse Oxidativo/efeitos dos fármacos , Sementes/efeitos dos fármacos , Brassica rapa/efeitos dos fármacos , Metabolismo Secundário/efeitos dos fármacos , Brassica napus/efeitos dos fármacos , Plântula/efeitos dos fármacos , China
16.
Sci Total Environ ; 940: 173349, 2024 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-38772487

RESUMO

The high toxicity and persistence of polychlorinated biphenyls (PCBs) in the environment require effective remediation of PCBs-contaminated soil. This study used polylactic acid (PLA) and polyethylene glycol 4000 (PEG-4000) to modify zero-valent iron nanoparticles (nZVI) and conducted characterization analysis. It was found that when the addition amount of PLA was 2 %, the dispersion of modified nZVI was better. The initial pH and water to soil ratio were subjected to single factor experiments and fitted using RSM response surface methodology. The optimal reaction conditions were obtained as follows: the addition amount was 84 g·kg-1, the initial pH was 5.41, and the optimal removal rate was 74 % when the ratio of water to soil was 1.8:1. PLA and PEG-4000 were biodegradable substances that played crucial roles in enhancing the effectiveness of nZVI for PCBs-contaminated soil. By encapsulating nZVI with PLA, we significantly reduced its oxidation when exposed to air. Additionally, the inclusion of PEG-4000 helped prevent the particles from clumping together. The synergistic effect of them increased the effective reaction of nZVI and PCBs and ultimately leading to more efficient remediation. This study offered a new pathway for the efficient green remediation of PCBs-contaminated soil.

17.
Eur J Pharmacol ; 968: 176418, 2024 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-38350590

RESUMO

The management of patients with acute myeloid leukemia (AML) remains a challenge because of the complexity and heterogeneity of this malignancy. Despite the recent approval of several novel targeted drugs, resistance seems inevitable, and clinical outcomes are still suboptimal. Increasing evidence supports the use of natural plants as an important source of anti-leukemic therapeutics. Licochalcone A (LCA) is an active flavonoid isolated from the roots of licorice, Glycyrrhiza uralensis Fisch., possessing extensive anti-tumor activities. However, its effects on AML and the underlying mechanisms remain unknown. Here, we showed that LCA decreased the viability of established human AML cell lines in a dose- and time-dependent manner. LCA significantly induced mitochondrial apoptotic cell death, accompanied by the downregulation of MCL-1, upregulation of BIM, truncation of BID, and cleavage of PARP. A prominent decline in the phosphorylation of multiple critical molecules, including AKT, glycogen synthase kinase-3ß (GSK3ß), ERK, and P38 was observed upon LCA treatment, indicating PI3K and MAPK signals were suppressed. Both transcription and translation of c-Myc were also inhibited by LCA. In addition, LCA enhanced the cytotoxicity of the BCL-2 inhibitor venetoclax. Furthermore, the anti-survival and pro-apoptotic effects were confirmed in primary blasts from 10 patients with de novo AML. Thus, our results expand the applications of LCA, which can be regarded as a valuable agent in treating AML.


Assuntos
Chalconas , Leucemia Mieloide Aguda , Proteínas Proto-Oncogênicas c-bcl-2 , Sulfonamidas , Humanos , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Linhagem Celular Tumoral , Leucemia Mieloide Aguda/patologia , Apoptose , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Mitocôndrias
18.
Adv Mater ; 36(24): e2312004, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38402422

RESUMO

Quantum anomalous Hall (QAH) insulators transport charge without resistance along topologically protected chiral 1D edge states. Yet, in magnetic topological insulators to date, topological protection is far from robust, with zero-magnetic field QAH effect only realized at temperatures an order of magnitude below the Néel temperature TN, though small magnetic fields can stabilize QAH effect. Understanding why topological protection breaks down is therefore essential to realizing QAH effect at higher temperatures. Here a scanning tunneling microscope is used to directly map the size of exchange gap (Eg,ex) and its spatial fluctuation in the QAH insulator 5-layer MnBi2Te4. Long-range fluctuations of Eg,ex are observed, with values ranging between 0 (gapless) and 70 meV, appearing to be uncorrelated to individual surface point defects. The breakdown of topological protection is directly imaged, showing that the gapless edge state, the hallmark signature of a QAH insulator, hybridizes with extended gapless regions in the bulk. Finally, it is unambiguously demonstrated that the gapless regions originate from magnetic disorder, by demonstrating that a small magnetic field restores Eg,ex in these regions, explaining the recovery of topological protection in magnetic fields. The results indicate that overcoming magnetic disorder is the key to exploiting the unique properties of QAH insulators.

19.
Adv Sci (Weinh) ; 11(21): e2310115, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38491872

RESUMO

In this work, 2D ferromagnetic M3GeTe2 (MGT, M = Ni/Fe) nanosheets with rich atomic Te vacancies (2D-MGTv) are demonstrated as efficient OER electrocatalyst via a general mechanical exfoliation strategy. X-ray absorption spectra (XAS) and scanning transmission electron microscope (STEM) results validate the dominant presence of metal-O moieties and rich Te vacancies, respectively. The formed Te vacancies are active for the adsorption of OH* and O* species while the metal-O moieties promote the O* and OOH* adsorption, contributing synergistically to the faster oxygen evolution kinetics. Consequently, 2D-Ni3GeTe2v exhibits superior OER activity with only 370 mV overpotential to reach the current density of 100 mA cm-2 and turnover frequency (TOF) value of 101.6 s-1 at the overpotential of 200 mV in alkaline media. Furthermore, a 2D-Ni3GeTe2v-based anion-exchange membrane (AEM) water electrolysis cell (1 cm2) delivers a current density of 1.02 and 1.32 A cm-2 at the voltage of 3 V feeding with 0.1 and 1 m KOH solution, respectively. The demonstrated metal-O coordination with abundant atomic vacancies for ferromagnetic M3GeTe2 and the easily extended preparation strategy would enlighten the rational design and fabrication of other ferromagnetic materials for wider electrocatalytic applications.

20.
Sci Total Environ ; 902: 165768, 2023 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-37516166

RESUMO

The secondary metabolism of plants is key for mediating responses to environmental stress, but few studies have examined how the relationship between secondary metabolism and the stress response of plants is affected by exposure to antibiotics. Here, we studied the effects of sulfamethoxazole (SMZ) on the secondary metabolism and antioxidant activity of oilseed rape (Brassica napus L.). SMZ significantly affected the growth of rape seedlings. Low and high concentrations of SMZ induced the production of a large number of reactive oxygen species (ROS) in rape seedlings, which damaged cells. SMZ stress altered the activity of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), as well as the content of malondialdehyde (MDA). SMZ promoted the activities of phenylalanine ammonia lyase (PAL), tyrosine ammonia lyase (TAL), cinnamic acid-4-hydroxylase (C4H), and 4-coumaric acid: coenzyme A ligase (4CL) by activating the phenylpropanoid pathway. The content of secondary metabolites changed. The content of phenolic acids and flavonoids increased, and the content of sinapine and anthocyanins was altered to cope with the oxidative damage induced by antibiotics. Transcriptomic and metabolomic analysis showed that differentially expressed genes and differentially expressed metabolites were mainly involved in Phenylpropanoid biosynthesis. SMZ alters the secondary metabolites of rapeseed, which mitigates the deleterious effects of stress, by modulating upstream secondary metabolism pathways and the production of plant hormones involved in signal transduction. In sum, these results provide a new perspective on the effects of SMZ on plants relative to secondary metabolites and improve our understanding of the toxicity of SMZ.


Assuntos
Brassica napus , Brassica rapa , Antioxidantes/metabolismo , Brassica napus/metabolismo , Sulfametoxazol/metabolismo , Antocianinas/metabolismo , Brassica rapa/metabolismo , Plântula , Antibacterianos/farmacologia
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