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1.
Nature ; 600(7890): 641-646, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34937897

RESUMO

Electron correlation and topology are two central threads of modern condensed matter physics. Semiconductor moiré materials provide a highly tuneable platform for studies of electron correlation1-12. Correlation-driven phenomena, including the Mott insulator2-5, generalized Wigner crystals2,6,9, stripe phases10 and continuous Mott transition11,12, have been demonstrated. However, non-trivial band topology has remained unclear. Here we report the observation of a quantum anomalous Hall effect in AB-stacked MoTe2 /WSe2 moiré heterobilayers. Unlike in the AA-stacked heterobilayers11, an out-of-plane electric field not only controls the bandwidth but also the band topology by intertwining moiré bands centred at different layers. At half band filling, corresponding to one particle per moiré unit cell, we observe quantized Hall resistance, h/e2 (with h and e denoting the Planck's constant and electron charge, respectively), and vanishing longitudinal resistance at zero magnetic field. The electric-field-induced topological phase transition from a Mott insulator to a quantum anomalous Hall insulator precedes an insulator-to-metal transition. Contrary to most known topological phase transitions13, it is not accompanied by a bulk charge gap closure. Our study paves the way for discovery of emergent phenomena arising from the combined influence of strong correlation and topology in semiconductor moiré materials.

2.
Nature ; 597(7876): 350-354, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34526709

RESUMO

The evolution of a Landau Fermi liquid into a non-magnetic Mott insulator with increasing electronic interactions is one of the most puzzling quantum phase transitions in physics1-6. The vicinity of the transition is believed to host exotic states of matter such as quantum spin liquids4-7, exciton condensates8 and unconventional superconductivity1. Semiconductor moiré materials realize a highly controllable Hubbard model simulator on a triangular lattice9-22, providing a unique opportunity to drive a metal-insulator transition (MIT) via continuous tuning of the electronic interactions. Here, by electrically tuning the effective interaction strength in MoTe2/WSe2 moiré superlattices, we observe a continuous MIT at a fixed filling of one electron per unit cell. The existence of quantum criticality is supported by the scaling collapse of the resistance, a continuously vanishing charge gap as the critical point is approached from the insulating side, and a diverging quasiparticle effective mass from the metallic side. We also observe a smooth evolution of the magnetic susceptibility across the MIT and no evidence of long-range magnetic order down to ~5% of the Curie-Weiss temperature. This signals an abundance of low-energy spinful excitations on the insulating side that is further corroborated by the Pomeranchuk effect observed on the metallic side. Our results are consistent with the universal critical theory of a continuous Mott transition in two dimensions4,23.

3.
Nature ; 579(7799): 353-358, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32188950

RESUMO

The Hubbard model, formulated by physicist John Hubbard in the 1960s1, is a simple theoretical model of interacting quantum particles in a lattice. The model is thought to capture the essential physics of high-temperature superconductors, magnetic insulators and other complex quantum many-body ground states2,3. Although the Hubbard model provides a greatly simplified representation of most real materials, it is nevertheless difficult to solve accurately except in the one-dimensional case2,3. Therefore, the physical realization of the Hubbard model in two or three dimensions, which can act as an analogue quantum simulator (that is, it can mimic the model and simulate its phase diagram and dynamics4,5), has a vital role in solving the strong-correlation puzzle, namely, revealing the physics of a large number of strongly interacting quantum particles. Here we obtain the phase diagram of the two-dimensional triangular-lattice Hubbard model by studying angle-aligned WSe2/WS2 bilayers, which form moiré superlattices6 because of the difference between the lattice constants of the two materials. We probe the charge and magnetic properties of the system by measuring the dependence of its optical response on an out-of-plane magnetic field and on the gate-tuned carrier density. At half-filling of the first hole moiré superlattice band, we observe a Mott insulating state with antiferromagnetic Curie-Weiss behaviour, as expected for a Hubbard model in the strong-interaction regime2,3,7-9. Above half-filling, our experiment suggests a possible quantum phase transition from an antiferromagnetic to a weak ferromagnetic state at filling factors near 0.6. Our results establish a new solid-state platform based on moiré superlattices that can be used to simulate problems in strong-correlation physics that are described by triangular-lattice Hubbard models.

4.
Nat Mater ; 20(5): 645-649, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33479527

RESUMO

Moiré superlattices of two-dimensional van der Waals materials have emerged as a powerful platform for designing electronic band structures and discovering emergent physical phenomena. A key concept involves the creation of long-wavelength periodic potential and moiré bands in a crystal through interlayer electronic hybridization or atomic corrugation when two materials are overlaid. Here we demonstrate a new approach based on spatially periodic dielectric screening to create moiré bands in a monolayer semiconductor. This approach relies on reduced dielectric screening of the Coulomb interactions in monolayer semiconductors and their environmental dielectric-dependent electronic band structure. We observe optical transitions between moiré bands in monolayer WSe2 when it is placed close to small-angle-misaligned graphene on hexagonal boron nitride. The moiré bands are a result of long-range Coulomb interactions, which are strongly gate tunable, and can have versatile superlattice symmetries independent of the crystal lattice of the host material. Our result also demonstrates that monolayer semiconductors are sensitive local dielectric sensors.

5.
J Clin Microbiol ; 59(8): e0007921, 2021 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-33952598

RESUMO

While China experienced a peak and decline in coronavirus disease 2019 (COVID-19) cases at the start of 2020, regional outbreaks continuously emerged in subsequent months. Resurgences of COVID-19 have also been observed in many other countries. In Guangzhou, China, a small outbreak, involving less than 100 residents, emerged in March and April 2020, and comprehensive and near-real-time genomic surveillance of SARS-CoV-2 was conducted. When the numbers of confirmed cases among overseas travelers increased, public health measures were enhanced by shifting from self-quarantine to central quarantine and SARS-CoV-2 testing for all overseas travelers. In an analysis of 109 imported cases, we found diverse viral variants distributed in the global viral phylogeny, which were frequently shared within households but not among passengers on the same flight. In contrast to the viral diversity of imported cases, local transmission was predominately attributed to two specific variants imported from Africa, including local cases that reported no direct or indirect contact with imported cases. The introduction events of the virus were identified or deduced before the enhanced measures were taken. These results show the interventions were effective in containing the spread of SARS-CoV-2, and they rule out the possibility of cryptic transmission of viral variants from the first wave in January and February 2020. Our study provides evidence and emphasizes the importance of controls for overseas travelers in the context of the pandemic and exemplifies how viral genomic data can facilitate COVID-19 surveillance and inform public health mitigation strategies.


Assuntos
COVID-19 , SARS-CoV-2 , África , Teste para COVID-19 , China/epidemiologia , Genômica , Humanos
6.
Nat Mater ; 19(8): 838-842, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32572203

RESUMO

Remarkable properties of two-dimensional (2D) layer magnetic materials, which include spin filtering in magnetic tunnel junctions and the gate control of magnetic states, were demonstrated recently1-12. Whereas these studies focused on static properties, dynamic magnetic properties, such as excitation and control of spin waves, remain elusive. Here we investigate spin-wave dynamics in antiferromagnetic CrI3 bilayers using an ultrafast optical pump/magneto-optical Kerr probe technique. Monolayer WSe2 with a strong excitonic resonance was introduced on CrI3 to enhance the optical excitation of spin waves. We identified subterahertz magnetic resonances under an in-plane magnetic field, from which the anisotropy and interlayer exchange fields were determined. We further showed tuning of the antiferromagnetic resonances by tens of gigahertz through electrostatic gating. Our results shed light on magnetic excitations and spin dynamics in 2D magnetic materials, and demonstrate their potential for applications in ultrafast data storage and processing.

7.
J Appl Toxicol ; 39(10): 1394-1404, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31423616

RESUMO

Atorvastatin (ATO) is a 3-hydroxy-3-methylglutaryl-CoA reductase inhibitor widely used to treat hypercholesterolemia. However, clinical application is limited by potential hepatotoxicity. Nuclear factor-erythroid 2-related factor 2 (Nrf2) is a master regulator of cellular antioxidants, and oxidative stress is implicated in statin-induced liver injury. This study investigated mechanisms of ATO-induced hepatotoxicity and potential mitigation by Nrf2 signaling. ATO reduced Nrf2 and antioxidant enzyme superoxide dismutase-2 (SOD2) expression in human hepatocarcinoma HepG2 cells. ATO also induced concentration-dependent HepG2 cell toxicity, reactive oxygen species (ROS) accumulation, and mitochondrial dysfunction as evidenced by decreased mitochondrial membrane potential (MMP) and cellular adenosine triphosphate (ATP). Further, ATO induced mitochondria-dependent apoptosis as indicated by increased Bax/Bcl-2 ratio, cleaved caspase-3, mitochondrial cytochrome c release and Annexin V-fluorescein isothiocyanate/propidium iodide staining. Tert-butylhydroquinone enhanced Nrf2 and SOD2 expression, and partially reversed ATO-induced cytotoxicity, ROS accumulation, MMP reduction, ATP depletion and mitochondria-dependent apoptosis. In conclusion, the present study demonstrates that ATO induces mitochondrial dysfunction and cell apoptosis in HepG2 cells, at least in part, via inhibition of the Nrf2 pathway. Nrf2 pathway activation is a potential prevention for ATO-induced liver injury.


Assuntos
Apoptose/efeitos dos fármacos , Atorvastatina/efeitos adversos , Células Hep G2/efeitos dos fármacos , Inibidores de Hidroximetilglutaril-CoA Redutases/efeitos adversos , Hipercolesterolemia/tratamento farmacológico , Mitocôndrias/efeitos dos fármacos , Fator 2 Relacionado a NF-E2/efeitos dos fármacos , Atorvastatina/uso terapêutico , Humanos , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Fator 2 Relacionado a NF-E2/metabolismo
8.
Regul Toxicol Pharmacol ; 90: 116-125, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28866266

RESUMO

Concerns regarding the adverse effects of long-term exposure to low levels of rare earth elements (REEs) from foods on human health have arisen in recent years. Nevertheless, no official acceptable daily intake (ADI) has yet been proposed for either total REEs or individual REE. In accordance with the Organization for Economic Co-operation and Development (OECD) testing guideline, the present study was undertaken to evaluate the subchronic toxicity of yttrium, a representative heavy REE with higher contaminated level in foods in China, to achieve a no observed adverse effect level (NOAEL) which is a critical basis for the establishment of an ADI. Yttrium nitrate was orally administered to rats at doses of 0, 10, 30 and 90 mg/kg/day for 90 days followed by a recovery period of 4 weeks. The following toxicity indices were measured: mortality, clinical signs, daily food consumption and weekly body weight; urinalysis, hematology, blood coagulation, clinical biochemistry and histopathology at the end of administration and recovery periods. No toxicologically significant changes were found in any yttrium-treated group as compared to the concurrent control group. Under the present experimental condition, the NOAEL in rats was thus set at 90 mg/kg for yttrium nitrate, i.e. 29.1 mg/kg for yttrium.


Assuntos
Nitratos/toxicidade , Nível de Efeito Adverso não Observado , Testes de Toxicidade Subcrônica , Ítrio/toxicidade , Adulto , Animais , Peso Corporal/efeitos dos fármacos , China , Relação Dose-Resposta a Droga , Feminino , Humanos , Masculino , Nitratos/administração & dosagem , Ratos , Ratos Sprague-Dawley , Ítrio/administração & dosagem
9.
Xenobiotica ; 46(8): 715-25, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26599915

RESUMO

1. Cardiotoxicity is an important factor that limits the clinical use of doxorubicin (Dox). Metallothionein (MT) can antagonize the Dox-induced cardiotoxicity. Using a proteomics approach we have detected that major peroxiredoxins (Prxs) may be involved in this process. In the present study, we further investigate the mechanisms of the MT effects against Dox-induced cytotoxicity and the interactions between MT and Prxs. 2. We have established a primary cardiomyocyte culture system from MT-I/II null (MT(-/-)) and corresponding wild type (MT(+/+)) neonatal mice, and pretreated the MT(+/+) cardiomyocytes with ZnCl2 to establish the MT overexpression cardiomyocyte model. 3. Based on the results, in MT(+/+) cardiomyocytes, ZnCl2 pretreatment significantly increased the cardiomyocytes MT levels and inhibited the cardiotoxicity of Dox; it can resist LDH leakage, cardiomyocyte apoptosis, DNA damage, ROS accumulation and inhibit the decrease in activity of antioxidant enzymes induced by Dox. Moreover, ZnCl2 enhanced the expression of Prx-2, -3, -5 and -6, it can inhibit the expression of Prxs decrease in MT(+/+) cardiomyocytes induced by Dox, but had no effect in MT(-/-) cardiomyocytes. 4. Therefore, the present study suggests that ZnCl2 can protect the cardiomyocytes from the Dox-induced oxidative injury and can inhibit the changes in Prxs expression through induced MT overexpression.


Assuntos
Cardiotônicos/farmacologia , Cardiotoxinas/toxicidade , Cloretos/farmacologia , Doxorrubicina/toxicidade , Metalotioneína/metabolismo , Peroxirredoxinas/metabolismo , Compostos de Zinco/farmacologia , Animais , Camundongos , Miócitos Cardíacos
10.
Environ Toxicol ; 31(12): 2028-2044, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26472167

RESUMO

Airborne fine particulate matter (PM2.5 ) is an "invisible killer" to human health. There is increasing evidence revealing the adverse effects of PM2.5 on the early embryonic development and pregnancy outcome, but the molecular mechanism underlying PM2.5 -induced embryotoxicity is largely unknown. Previous studies have documented that exposure to PM triggers ROS generation, leads to subsequent activation of MAPKs signaling, and results in corresponding cell biological changes including enhanced apoptosis and altered cell cycle in the cardiopulmonary system. Here, we investigated whether ROS-MAPKs-apoptosis/cell cycle arrest pathways play an important role in PM2.5 -induced embryotoxicity using the rat whole embryo culture system. The results showed that PM2.5 treatment led to embryonic growth retardation at concentrations of 50 µg/ml and above, as evidenced by the reduced yolk sac diameter, crown-rump length, head length and somite number. PM2.5 -induced embryonic growth retardation was accompanied by cell apoptosis and G0/G1 phase arrest. Furthermore, ROS generation and subsequent activation of JNK and ERK might be involved in PM2.5 -induced apoptosis and G0/G1 phase arrest by downregulating Bcl-2/Bax protein ratio and upregulating p15INK4B , p16INK4A , and p21WAF1/CIP1 transcription level. In conclusion, our results indicate that ROS-JNK/ERK-apoptosis and G0/G1 arrest pathways are involved in PM2.5 -induced embryotoxicity, which not only provides insights into the molecular mechanism of PM2.5 -induced embryotoxicity, but also may help to identify specific interventions to improve adverse pregnancy outcomes of PM2.5 . © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 2028-2044, 2016.


Assuntos
Poluentes Atmosféricos/toxicidade , Apoptose/efeitos dos fármacos , Embrião de Mamíferos/efeitos dos fármacos , Fase G1/efeitos dos fármacos , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Material Particulado/toxicidade , Espécies Reativas de Oxigênio/metabolismo , Animais , Técnicas de Cultura Embrionária , Embrião de Mamíferos/citologia , Embrião de Mamíferos/metabolismo , Desenvolvimento Embrionário/efeitos dos fármacos , Humanos , Ratos Sprague-Dawley , Transdução de Sinais/efeitos dos fármacos
11.
Int J Toxicol ; 35(3): 317-26, 2016 05.
Artigo em Inglês | MEDLINE | ID: mdl-26526549

RESUMO

Doxorubicin (Dox) is one of the most important anticancer agents; however, its clinical application is limited by its severe cardiotoxicity. In our previous study, we found that the gene expression levels of the Janus-activated kinase/signal transducer and activator of transcription 3 (JAK2/STAT3) pathway were different between MT(-/-) cardiomyocytes and MT(+/+) cardiomyocytes when they were treated with Dox. Thus, this study was intended to investigate the role of JAK2/STAT3 pathway in metallothionein (MT) protection of Dox-induced cardiotoxicity. Tyrphostin AG490 (α-cyano-(3,4-dihydroxy)-N-benzylcinnamide) is a synthetic protein tyrosine kinase inhibitor which at first has been considered as a specific JAK2 inhibitor and can inhibit the JAK2/STAT3 signaling pathway. In the present study, AG490 was used to assess the role of JAK2/STAT3 in MT protection against Dox-induced cardiotoxicity. The AG490 can attenuate the MT protection by increasing lactate dehydrogenase and the number of apoptotic cells. Interestingly, pretreated with AG490, MT(-/-) cardiomyocytes were more sensitive than MT(+/+) to Dox-induced cytotoxicity as measured by reactive oxygen species generation, lipid peroxidation, and protein carbonylation. Metallothionein 1 and MT-2 messenger RNA were upregulated by Dox, and AG490 decreased the protein expression of MT-1 and MT-2. After Dox treatment, the protein expression of p-Jak2 and p-Stat3 levels was significantly increased in MT(+/+) cardiomyocytes, suggesting that the JAK2/STAT3 pathway was partially involved in MT protection against Dox-induced cardiotoxicity.


Assuntos
Antineoplásicos/toxicidade , Doxorrubicina/toxicidade , Janus Quinase 2/metabolismo , Metalotioneína/metabolismo , Miócitos Cardíacos/efeitos dos fármacos , Fator de Transcrição STAT3/metabolismo , Animais , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Janus Quinase 2/antagonistas & inibidores , Metalotioneína/genética , Camundongos , Camundongos Knockout , Miócitos Cardíacos/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Carbonilação Proteica/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacologia , RNA Mensageiro/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Fator de Transcrição STAT3/antagonistas & inibidores , Transdução de Sinais
12.
Ecotoxicol Environ Saf ; 122: 537-44, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26432026

RESUMO

Growing evidence has confirmed that exposure to ambient particulate matters (PM) is associated with increased morbidity and mortality of cardiovascular and pulmonary diseases. Ambient PM is a complex mixture of particles and air pollutants. Harmful effects of PM are specifically associated with ultrafine particles (UFPs) that can adsorb high concentrations of toxic air pollutants and are easily inhaled into the lungs. However, combined effects of UFPs and air pollutants on human health remain unclear. In the present study, we elucidated the combined toxicity of silica nanoparticles (nano-SiO2), a typical UFP, and lead acetate (Pb), a typical air pollutant. Lung adenocarcinoma A549 cells were exposed to nano-SiO2 and Pb alone or their combination, and their combined toxicity was investigated by focusing on cellular oxidative stress and DNA damage. Factorial analyses were performed to determine the potential interactions between nano-SiO2 and Pb. Our results showed that exposure of A549 cells to a modest cytotoxic concentration of Pb alone induced oxidative stress, as evidenced by elevated reactive oxygen species generation and lipid peroxidation, and reduced glutathione content and superoxide dismutase and glutathione peroxidase activities. In addition, exposure of A549 cells to Pb alone induced DNA damage, as evaluated by alkaline comet assay. Exposure of A549 cells to non-cytotoxic concentration of nano-SiO2 did not induce cellular oxidative stress and DNA damage. However, exposure to the combination of nano-SiO2 and Pb potentiated oxidative stress and DNA damage in A549 cells. Factorial analyses indicated that the potentiation of combined toxicity of nano-SiO2 and Pb was induced by additive or synergistic interactions.


Assuntos
Poluentes Atmosféricos/toxicidade , Dano ao DNA , Células Epiteliais/efeitos dos fármacos , Chumbo/toxicidade , Pulmão/efeitos dos fármacos , Nanopartículas/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Dióxido de Silício/toxicidade , Poluentes Atmosféricos/análise , Antioxidantes/análise , Linhagem Celular , Ensaio Cometa , Sinergismo Farmacológico , Células Epiteliais/enzimologia , Células Epiteliais/patologia , Humanos , Chumbo/análise , Peroxidação de Lipídeos/efeitos dos fármacos , Pulmão/enzimologia , Pulmão/patologia , Nanopartículas/análise , Tamanho da Partícula , Material Particulado/análise , Material Particulado/toxicidade , Espécies Reativas de Oxigênio/análise , Dióxido de Silício/análise , Propriedades de Superfície
13.
Nat Nanotechnol ; 19(1): 28-33, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37591935

RESUMO

The spin Hall effect (SHE), in which an electrical current generates a transverse spin current, plays an important role in spintronics for the generation and manipulation of spin-polarized electrons. The phenomenon originates from spin-orbit coupling. In general, stronger spin-orbit coupling favours larger SHEs but shorter spin relaxation times and diffusion lengths. However, correlated magnetic materials often do not support large SHEs. Achieving large SHEs, long-range spin transport and magnetism simultaneously in a single material is attractive for spintronics applications but has remained a challenge. Here we demonstrate a giant intrinsic SHE coexisting with ferromagnetism in AB-stacked MoTe2/WSe2 moiré bilayers by direct magneto-optical imaging. Under moderate electrical currents with density <1 A m-1, we observe spin accumulation on transverse sample edges that nearly saturates the spin density. We also demonstrate long-range spin Hall transport and efficient non-local spin accumulation that is limited only by the device size (about 10 µm). The gate dependence shows that the giant SHE occurs only near the interaction-driven Chern insulating state. At low temperatures, it emerges after the quantum anomalous Hall breakdown. Our results demonstrate moiré engineering of Berry curvature and electronic correlation for potential spintronics applications.

14.
Virus Res ; 324: 199038, 2023 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-36599394

RESUMO

Enterovirus A71 (EV-A71) is neurotropic and one of the primary enteric pathogens responsible for severe central nervous system infection in infants and young children. Neonatal mice are ideal models for studying the pathogenesis of infection caused by EV-A71. In this study, we assessed the susceptibility of neonatal BALB/c, C57BL/6, ICR, Kunming, and NIH mice to a clinically isolated EV-A71 strain. One-day-old mice were challenged with a clinical isolate of EV-A71 via intraperitoneal injection, then observed for 13 days for mortality, body-weight changes, and limb paralysis. RT-qPCR was performed to quantify viral RNA in the brain, spinal cord, skeletal muscle, and lungs of BALB/c and C57BL/6 mice. The expression of murine scavenger receptor class B member 2 (mSCARB2) was measured by western blotting. Finally, lesions were assessed by histological examination. We found that neonatal BALB/c and C57BL/6 mice were both susceptible to EV-A71, leading to decreased survival rate, greater body weight loss, and prominent hind-limb paralysis. Tissue viral loads of C57BL/6J mice were markedly higher than those of BALB/c mice, indicating that EV-A71 replicated more efficiently in C57BL/6 mice. Increased expression of mSCARB2 was observed 5 days after infection in C57BL/6 mice, which coincided with the peak in EV-A71 replication. Histological examination indicated that infection caused obvious pathogenic lesions. In conclusion, C57BL/6 are most susceptible to infection caused by EV-A71 and can be used as a model for studying its pathogenesis and test therapeutic options.


Assuntos
Enterovirus Humano A , Infecções por Enterovirus , Enterovirus , Animais , Camundongos , Enterovirus/genética , Enterovirus Humano A/fisiologia , Modelos Animais de Doenças , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos ICR , Antígenos Virais/genética , Camundongos Endogâmicos BALB C
15.
Microbiol Spectr ; 11(6): e0232023, 2023 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-37889044

RESUMO

IMPORTANCE: This study combines quantitative polymerase chain reaction (qPCR) and microfluidics to introduce MONITOR, a portable field detection system for multiple pathogens causing influenza-like illness. MONITOR can be rapidly deployed to enable simultaneous sample-in-result-out detection of eight common influenza-like illness (ILI) pathogens with heightened sensitivity and specificity. It is particularly well suited for communities and regions without centralized laboratories, offering robust technical support for the prompt and accurate monitoring and detection of ILI. It holds the potential to be a potent tool in the early detection and prevention of infectious diseases.


Assuntos
Influenza Humana , Viroses , Humanos , Reação em Cadeia da Polimerase em Tempo Real , Influenza Humana/diagnóstico , Microfluídica , Sensibilidade e Especificidade
16.
Nat Nanotechnol ; 18(3): 233-237, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36646827

RESUMO

Electrons in two-dimensional semiconductor moiré materials are more delocalized around the lattice sites than those in conventional solids1,2. The non-local contributions to the magnetic interactions can therefore be as important as the Anderson superexchange3, which makes the materials a unique platform to study the effects of competing magnetic interactions3,4. Here we report evidence of strongly frustrated magnetic interactions in a Wigner-Mott insulator at a two-thirds (2/3) filling of the moiré lattice in angle-aligned WSe2/WS2 bilayers. Magneto-optical measurements show that the net exchange interaction is antiferromagnetic for filling factors below 1 with a strong suppression at a 2/3 filling. The suppression is lifted on screening of the long-range Coulomb interactions and melting of the Wigner-Mott insulators by a nearby metallic gate. The results can be qualitatively captured by a honeycomb-lattice spin model with an antiferromagnetic nearest-neighbour coupling and a ferromagnetic second-neighbour coupling. Our study establishes semiconductor moiré materials as a model system for lattice-spin physics and frustrated magnetism5.

17.
Nanomaterials (Basel) ; 12(14)2022 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-35889679

RESUMO

Developing suitable photocatalysts for the oxygen evolution reaction (OER) is still a challenging issue for efficient water splitting due to the high requirements to create a significant impact on water splitting reaction kinetics. Herein, n-type Bi2WO6 with flower-like hierarchical structure and p-type Cu2O quantum dots (QDs) are coupled together to construct an efficient S-scheme heterojunction, which could enhance the migration efficiency of photogenerated charge carriers. The electrochemical properties are investigated to explore the transportation features and donor density of charge carriers in the S-scheme heterojunction system. Meanwhile, the as-prepared S-scheme heterojunction presents improved photocatalytic activity towards water oxidation in comparison with the sole Bi2WO6 and Cu2O QDs systems under simulated solar light irradiation. Moreover, the initial O2 evolution rate of the Cu2O QDs/Bi2WO6 heterojunction system is 2.3 and 9.7 fold that of sole Bi2WO6 and Cu2O QDs systems, respectively.

18.
DNA Cell Biol ; 41(8): 716-726, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35834647

RESUMO

Sulfur mustard (SM), a chemical warfare agent, can form adducts with DNA, RNA, and proteins. Reactions with DNA lead to the formation of both DNA monoadducts and interstrand cross-links, resulting in DNA damage, and is an important component of SM toxicity. Our previous in vivo studies indicated that dividing cells such as hematopoietic stem cells and intestinal villi stem cells seemed to have increased sensitivity to SM. Therefore, to compare the sensitivity of somatic and stem cells to SM and to investigate the mechanism of SM cytotoxicity, we isolated human foreskin fibroblasts, reprogrammed them into pluripotent stem cells, and then compared the DNA damage repair pathways involved upon SM treatment. Our results indicated that proliferating stem cells were more sensitive to SM-induced DNA damage, and the damage mainly comprised single-stranded breaks. Furthermore, the pathways involved in DNA repair in stem cells and somatic cells were different.


Assuntos
Substâncias para a Guerra Química , Gás de Mostarda , Substâncias para a Guerra Química/toxicidade , DNA , Dano ao DNA , Humanos , Gás de Mostarda/toxicidade , Células-Tronco
19.
Virus Res ; 311: 198691, 2022 04 02.
Artigo em Inglês | MEDLINE | ID: mdl-35143909

RESUMO

OBJECTIVE: Fever with thrombocytopenia syndrome virus (SFTS) is a tick-borne infection now known to spread among humans as an aerosol, which has resulted in several outbreaks across Asia over the past decade. As mortality is substantial, it is vital to establish a rapid, on-site nucleic acid detection method for diagnosis. Here we describe such a method for SFTSV (Dabie bandavirus) based on CRISPR-Cas13a. METHODS: Specific recombinase-aided amplification (RAA) primers and CRISPR (cr)RNA nucleic acid detection targets were designed and synthesized for the conserved sequence of the SFTSV genome, and fluorescent CRISPR detection was used to screen for high-sensitivity crRNAs. Colloidal immunochromatography test paper was used to read CRISPR detection results. Sensitivity and specificity were evaluated by running tests on gradient dilutions of SFTSV nucleic acid and the nucleic acids of other pathogens with similar transmission routes or clinical manifestations. RESULTS: One crRNA with high detection sensitivity was screened out of 5 crRNAs with conserved sequences from the SFTSV genome. This CRISPR nucleic acid-based detection method was able to detect a single crRNA copy per microliter but not the nucleic acids of similar pathogens. CONCLUSION: This CRISPR test strip detection method permits rapid, sensitive, and specific diagnosis of SFTS without the need for advanced nucleic acid detection equipment, thus allowing for on-site application.


Assuntos
Infecções por Bunyaviridae , Ácidos Nucleicos , Phlebovirus , Febre Grave com Síndrome de Trombocitopenia , Infecções por Bunyaviridae/epidemiologia , Humanos , Técnicas de Amplificação de Ácido Nucleico , Phlebovirus/genética , Recombinases , Sensibilidade e Especificidade , Febre Grave com Síndrome de Trombocitopenia/diagnóstico
20.
Sci Adv ; 8(12): eabk1911, 2022 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-35333575

RESUMO

Moiré superlattices constructed from transition metal dichalcogenides have demonstrated a series of emergent phenomena, including moiré excitons, flat bands, and correlated insulating states. All of these phenomena depend crucially on the presence of strong moiré potentials, yet the properties of these moiré potentials, and the mechanisms by which they can be generated, remain largely open questions. Here, we use angle-resolved photoemission spectroscopy with submicron spatial resolution to investigate an aligned WS2/WSe2 moiré superlattice and graphene/WS2/WSe2 trilayer heterostructure. Our experiments reveal that the hybridization between moiré bands in WS2/WSe2 exhibits an unusually large momentum dependence, with the splitting between moiré bands at the Γ point more than an order of magnitude larger than that at K point. In addition, we discover that the same WS2/WSe2 superlattice can imprint an unexpectedly large moiré potential on a third, separate layer of graphene (g/WS2/WSe2), suggesting new avenues for engineering two-dimensional moiré superlattices.

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