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1.
Nano Lett ; 2024 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-38607185

RESUMO

The enhanced Coulomb interaction in two-dimensional semiconductors leads to tightly bound electron-hole pairs known as excitons. The large binding energy of excitons enables the formation of Rydberg excitons with high principal quantum numbers (n), analogous to Rydberg atoms. Rydberg excitons possess strong interactions among themselves as well as sensitive responses to external stimuli. Here, we probe Rydberg exciton resonances through photocurrent spectroscopy in a monolayer WSe2 p-n junction formed by a split-gate geometry. We show that an external in-plane electric field not only induces a large Stark shift of Rydberg excitons up to quantum principal number 3 but also mixes different orbitals and brightens otherwise dark states such as 3p and 3d. Our study provides an exciting platform for engineering Rydberg excitons for new quantum states and quantum sensing.

2.
FASEB J ; 38(5): e23500, 2024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-38441537

RESUMO

Hepatitis E virus (HEV) persists in the male genital tract that associates with infertility. However, the presence of HEV in the female genital tract is unreported. Vaginal secretions, cervical smears, and cervix uteri were collected to explore the presence of HEV in the female genital tract. HEV RNA and/or antigens were detected in the vaginal secretions, cervical smears, and the cervix uteri of women. The infectivity of HEV excreted into vaginal secretions was further validated in vitro. In addition, HEV replicates in the female genital tract were identified in HEV-infected animal models by vaginal injection or vaginal mucosal infection to imitate sexual transmission. Serious genital tract damage and inflammatory responses with significantly elevated mucosal innate immunity were observed in women or animals with HEV vaginal infection. Results demonstrated HEV replicates in the female genital tract and causes serious histopathological damage and inflammatory responses.


Assuntos
Líquidos Corporais , Hepatite A , Vírus da Hepatite E , Hepatite E , Animais , Feminino , Masculino , Humanos , Vagina
3.
Nat Commun ; 14(1): 5042, 2023 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-37598211

RESUMO

Moiré superlattices of semiconducting transition metal dichalcogenides enable unprecedented spatial control of electron wavefunctions, leading to emerging quantum states. The breaking of translational symmetry further introduces a new degree of freedom: high symmetry moiré sites of energy minima behaving as spatially separated quantum dots. We demonstrate the superposition between two moiré sites by constructing a trilayer WSe2/monolayer WS2 moiré heterojunction. The two moiré sites in the first layer WSe2 interfacing WS2 allow the formation of two different interlayer excitons, with the hole residing in either moiré site of the first layer WSe2 and the electron in the third layer WSe2. An electric field can drive the hybridization of either of the interlayer excitons with the intralayer excitons in the third WSe2 layer, realizing the continuous tuning of interlayer exciton hopping between two moiré sites and a superposition of the two interlayer excitons, distinctively different from the natural trilayer WSe2.

4.
Nat Commun ; 14(1): 4604, 2023 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-37528094

RESUMO

Transition metal dichalcogenide (TMDC) moiré superlattices, owing to the moiré flatbands and strong correlation, can host periodic electron crystals and fascinating correlated physics. The TMDC heterojunctions in the type-II alignment also enable long-lived interlayer excitons that are promising for correlated bosonic states, while the interaction is dictated by the asymmetry of the heterojunction. Here we demonstrate a new excitonic state, quadrupolar exciton, in a symmetric WSe2-WS2-WSe2 trilayer moiré superlattice. The quadrupolar excitons exhibit a quadratic dependence on the electric field, distinctively different from the linear Stark shift of the dipolar excitons in heterobilayers. This quadrupolar exciton stems from the hybridization of WSe2 valence moiré flatbands. The same mechanism also gives rise to an interlayer Mott insulator state, in which the two WSe2 layers share one hole laterally confined in one moiré unit cell. In contrast, the hole occupation probability in each layer can be continuously tuned via an out-of-plane electric field, reaching 100% in the top or bottom WSe2 under a large electric field, accompanying the transition from quadrupolar excitons to dipolar excitons. Our work demonstrates a trilayer moiré system as a new exciting playground for realizing novel correlated states and engineering quantum phase transitions.

5.
J Phys Chem Lett ; 14(24): 5573-5579, 2023 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-37306346

RESUMO

Raman spectroscopy, a nondestructive fingerprinting technique, is mainly utilized to identify molecular species and phonon modes of materials. However, direct Raman characterization of two-dimensional materials typically synthesized on catalytic metal substrates is extremely challenging because of the significant electric screening and interfacial electronic couplings. Here, we demonstrate that by covering as-grown graphene with boron nitride (BN) films, the Raman intensity of graphene can be enhanced by two orders of magnitude and is also several times stronger than that of suspended graphene. This great Raman enhancement originates from the optical field amplification by Fabry-Pérot cavity in BN films and the local field plasmon near copper steps. We further demonstrate the direct characterization of the local strain and doping level of as-grown graphene and in situ monitoring of the molecule reaction process by enhanced Raman spectroscopy. Our results will broaden the optical investigations of interfacial sciences on metals, including photoinduced charge transfer dynamics and photocatalysis at metal surfaces.

6.
J Infect ; 87(1): 34-45, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37160209

RESUMO

BACKGROUND: Hepatitis E virus (HEV) infection in pregnant women causes adverse pregnancy outcomes, including maternal death, premature delivery, stillbirth, and fetal infection. However, the pathogenesis of maternal and fetal HEV infection is unclear. METHODS: Placenta and placental appendixes were collected from HEV-4 infected pregnant women to explore the vertical transmission of HEV from mothers to fetuses. RESULTS: HEV-4 replicated in the placenta, placental membrane, and umbilical cord and was vertically transmitted from mothers to fetuses. HEV-4 placental infection resulted in serious histopathological damage, such as fibrosis and calcification, and severe inflammatory responses. Adverse maternal outcomes were observed in 38.5% of HEV-4 infected pregnant women. The distinct cytokine/chemokine expression patterns of HEV-infected pregnant women and nonpregnant women may contribute to the adverse pregnancy outcomes. Furthermore, the impaired maternal and fetal innate immune responses against HEV-4 facilitated viral replication during pregnancy. CONCLUSION: HEV-4 replicates in the placenta and is vertically transmitted from mothers to fetuses, causing severe histopathological damage.


Assuntos
Vírus da Hepatite E , Hepatite E , Complicações Infecciosas na Gravidez , Gravidez , Feminino , Humanos , Vírus da Hepatite E/genética , Placenta/patologia , Hepatite E/patologia , Feto/patologia , Genótipo
7.
Environ Sci Technol ; 57(4): 1551-1567, 2023 01 31.
Artigo em Inglês | MEDLINE | ID: mdl-36661479

RESUMO

Toxic trace elements (TEs) can pose serious risks to ecosystems and human health. However, a comprehensive understanding of atmospheric emission inventories for several concerning TEs has not yet been developed. In this study, we systematically reviewed the status and progress of existing research in developing atmospheric emission inventories of TEs focusing on global, regional, and sectoral scales. Multiple studies have strengthened our understanding of the global emission of TEs, despite attention being mainly focused on Hg and source classification in different studies showing large discrepancies. In contrast to those of developed countries and regions, the officially published emission inventory is still lacking in developing countries, despite the fact that studies on evaluating the emissions of TEs on a national scale or one specific source category have been numerous in recent years. Additionally, emissions of TEs emitted from waste incineration and traffic-related sources have produced growing concern with worldwide rapid urbanization. Although several studies attempt to estimate the emissions of TEs based on PM emissions and its source-specific chemical profiles, the emission factor approach is still the universal method. We call for more extensive and in-depth studies to establish a precise localization national emission inventory of TEs based on adequate field measurements and comprehensive investigation to reduce uncertainty.


Assuntos
Poluentes Atmosféricos , Mercúrio , Oligoelementos , Humanos , Oligoelementos/análise , Poluentes Atmosféricos/análise , Ecossistema , Monitoramento Ambiental/métodos , Mercúrio/análise
8.
Liver Int ; 43(2): 317-328, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36305303

RESUMO

BACKGROUND: Hepatitis E virus (HEV) infection causes serious adverse pregnancy outcomes during pregnancy. However, the maternal and fetal damage induced by HEV infection is rarely reported. METHODS: A BALB/c pregnant mouse model was established to explore the maternal and fetal pathological damage and inflammatory responses caused by HEV infection. RESULTS: Notably, miscarriages and stillbirths were observed in HEV-infected pregnant mice. HEV infections were identified by qRT-PCR, immunohistochemical analysis and immunofluorescence assay in the uterus, placenta, umbilical cords and livers and brains of fetuses. Serious inflammatory responses and pathological damage were triggered in the uterus and placenta of HEV-infected pregnant mice. Vertical transmission of HEV resulted in severe pathological damage and inflammatory responses in the livers and brains of fetuses, as well as emerging apoptosis cells in the brains of fetuses. Most of the cytokines/chemokines in the sera were significantly increased in the HEV-infected pregnant mice. Remarkably, cytokines/chemokines were significantly different between HEV-infected pregnant and miscarriage mice; IL9, GM-CSF and IL1α were the most important three cytokines/chemokines in determining the pregnancy outcomes. CONCLUSION: HEV infections cause serious maternal/fetal pathological damage, inflammatory responses and apoptosis, which may be responsible for adverse pregnancy outcomes.


Assuntos
Aborto Espontâneo , Vírus da Hepatite E , Hepatite E , Complicações Infecciosas na Gravidez , Animais , Feminino , Camundongos , Gravidez , Aborto Espontâneo/etiologia , Citocinas , Hepatite E/complicações , Hepatite E/patologia , Camundongos Endogâmicos BALB C
9.
Nat Commun ; 13(1): 4810, 2022 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-35974047

RESUMO

Moiré coupling in transition metal dichalcogenides (TMDCs) superlattices introduces flat minibands that enable strong electronic correlation and fascinating correlated states, and it also modifies the strong Coulomb-interaction-driven excitons and gives rise to moiré excitons. Here, we introduce the layer degree of freedom to the WSe2/WS2 moiré superlattice by changing WSe2 from monolayer to bilayer and trilayer. We observe systematic changes of optical spectra of the moiré excitons, which directly confirm the highly interfacial nature of moiré coupling at the WSe2/WS2 interface. In addition, the energy resonances of moiré excitons are strongly modified, with their separation significantly increased in multilayer WSe2/monolayer WS2 moiré superlattice. The additional WSe2 layers also modulate the strong electronic correlation strength, evidenced by the reduced Mott transition temperature with added WSe2 layer(s). The layer dependence of both moiré excitons and correlated electronic states can be well described by our theoretical model. Our study presents a new method to tune the strong electronic correlation and moiré exciton bands in the TMDCs moiré superlattices, ushering in an exciting platform to engineer quantum phenomena stemming from strong correlation and Coulomb interaction.

10.
Math Biosci Eng ; 19(8): 7521-7542, 2022 05 20.
Artigo em Inglês | MEDLINE | ID: mdl-35801434

RESUMO

With the development of the field of survival analysis, statistical inference of right-censored data is of great importance for the study of medical diagnosis. In this study, a right-censored data survival prediction model based on an improved composite quantile regression neural network framework, called rcICQRNN, is proposed. It incorporates composite quantile regression with the loss function of a multi-hidden layer feedforward neural network, combined with an inverse probability weighting method for survival prediction. Meanwhile, the hyperparameters involved in the neural network are adjusted using the WOA algorithm, integer encoding and One-Hot encoding are implemented to encode the classification features, and the BWOA variable selection method for high-dimensional data is proposed. The rcICQRNN algorithm was tested on a simulated dataset and two real breast cancer datasets, and the performance of the model was evaluated by three evaluation metrics. The results show that the rcICQRNN-5 model is more suitable for analyzing simulated datasets. The One-Hot encoding of the WOA-rcICQRNN-30 model is more applicable to the NKI70 data. The model results are optimal for k=15 after feature selection for the METABRIC dataset. Finally, we implemented the method for cross-dataset validation. On the whole, the Cindex results using One-Hot encoding data are more stable, making the proposed rcICQRNN prediction model flexible enough to assist in medical decision making. It has practical applications in areas such as biomedicine, insurance actuarial and financial economics.


Assuntos
Algoritmos , Redes Neurais de Computação , Simulação por Computador , Probabilidade , Análise de Sobrevida
11.
Front Public Health ; 10: 813916, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35558544

RESUMO

Background: Congenital heart defects are the most common type of birth defects and bring a heavy disease burden in China. Examining the temporal and spatial trends of congenital heart defects epidemics can give some elementary knowledge for succeeding studies. Objective: To characterize the spatial-temporal patterns of the prevalence of congenital heart defects based on a substantial cohort of the perinatal fetus in south China in 2016-2020. Methods: This study was a retrospective population-based cohort study conducted in Guangdong, China from 2016 to 2020. Pregnant women and their infants received birth defect surveillance during pregnancy and seven days after delivery in more than 1,900 midwifery hospitals in 21 cities. Perinatal infants with congenital heart defects were identified and enrolled. The prevalence of congenital heart defects was calculated according to cities, years, urban and rural areas, regions of Guangdong, categories of maternal age at delivery, seasons of delivery, and infant's gender. Results: A total of 8,653,206 perinatal infants and 53,912 total congenital heart defects were monitored in Guangdong, including 46,716 (86.65%) without other defects and 7,736 (13.35%) with other defects. The average prevalence of total congenital heart defects was 62.30/10,000 (95% CI, 61.78/10,000-62.83/10,000), congenital heart defects without other defects was 53.36/10,000 (95% CI, 52.88/10,000-53.85/10,000), and congenital heart defects with other defects was 8.94/10,000 (95%CI, 8.74/10,000-9.14/10,000). From 2016 to 2020, the prevalence of total congenital heart defects was 54.92/10,000, 54.23/10,000, 63.79/10,000, 73.11/10,000, 68.20/10,000, respectively. We observed geographical variations within the prevalence of congenital heart defects. The prevalence of congenital heart defects was much higher in the Pearl River Delta region than in the non-Pearl River Delta region, as well as higher in urban areas than in rural areas. Conclusion: The findings of this study are helpful to the understanding of the etiology and epidemiology characteristics of congenital heart defects in south China. Our data likely reflect a better estimate of the spatiotemporal trends in congenital heart defects prevalence than reported previously.


Assuntos
Cardiopatias Congênitas , China/epidemiologia , Estudos de Coortes , Feminino , Cardiopatias Congênitas/epidemiologia , Humanos , Lactente , Gravidez , Prevalência , Estudos Retrospectivos
12.
Oncol Rep ; 48(1)2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35593315

RESUMO

The in­depth study of melanoma pathogenesis has revealed that epigenetic modifications, particularly DNA methylation, is a universal inherent feature of the development and progression of melanoma. In the present study, the analysis of the tumor suppressor gene growth arrest­specific transcript 5 (GAS5) demonstrated that its expression was downregulated in melanoma, and its expression level had a certain negative association with its methylation modification level. The promoter of GAS5 presented with detectable CpG islands, and methylation­specific polymerase chain reaction analysis demonstrated that GAS5 was actually modified by methylation in melanoma tissues and cells; however, no methylation modification of GAS5 was detected in normal tissues. Following the treatment of melanoma cells with 5­Aza­2'­deoxycytidine (5­Aza­dC), GAS5 methylation was significantly reversed. The analysis of melanoma cell proliferation revealed that 5­Aza­dC inhibited A375 and SK­MEL­110 cell proliferation in a time­dependent manner. Further analysis of apoptosis demonstrated that 5­Aza­dC significantly increased the apoptosis level of the two cell lines. Moreover, migration analysis of melanoma cells revealed that 5­Aza­dC significantly reduced cell migration. Furthermore, 5­Aza­dC significantly decreased the invasive ability of the two cell lines. However, when the expression of GAS5 was silenced, the effects of 5­Aza­dC on cell proliferation, apoptosis, invasion and migration were not significant. Furthermore, the subcutaneous injection of A375 cells in nude mice successfully resulted in xenograft tumor formation. However, following an intraperitoneal injection of 5­Aza­dC, the volume and weight of xenograft tumors and Ki­67 expression were significantly reduced, and caspase­3 activity and GAS5 expression were enhanced; following the silencing of GAS5, the antitumor effect of 5­Aza­dC was significantly blocked. On the whole, the present study demonstrates that 5­Aza­dC inhibits the growth of melanoma, and its function may be related to the methylation modification of GAS5.


Assuntos
Melanoma , RNA Longo não Codificante , Animais , Apoptose , Azacitidina/farmacologia , Linhagem Celular Tumoral , Proliferação de Células , Metilação de DNA , Regulação Neoplásica da Expressão Gênica , Humanos , Melanoma/genética , Camundongos , Camundongos Nus , RNA Longo não Codificante/genética
13.
J Affect Disord ; 309: 236-241, 2022 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-35489556

RESUMO

BACKGROUND: At present, few studies have explored the mediating effect of e-Health literacy and self-efficacy on prevention cognition and healthy lifestyle behaviors during the normalization stage of COVID-19 prevention and control. This study aimed to determine the associations among COVID-19-related prevention cognition, self-efficacy, e-Health literacy, and healthy lifestyle behaviors at university students. METHODS: By using a stratified cluster random sampling method, 971 students from five universities were recruited between May and August 2021 in Guangzhou, China. We collected participants' demographic characteristics, and assessed self-efficacy, COVID-19-related prevention cognition, e-Health literacy, and healthy lifestyle behaviors. A structural equation model was used for mediation analysis. RESULTS: The overall mean value of healthy lifestyle behaviors of college students was 0.307 (SD 0.389). Between COVID-19-related prevention cognition, e-Health literacy, self-efficacy, and healthy lifestyle behaviors (r = 0.132-0.505, P < 0.01) were a significant positive correlation. The COVID-19-related prevention cognition had a direct and positive predictive effect on healthy lifestyle behaviors, with a direct effect value of 0.136. e-Health literacy and self-efficacy played both an independent mediating and serial-multiple mediating roles in the association between COVID-19-related prevention cognition and healthy lifestyle behaviors, and the indirect effect values were 0.043, 0.020 and 0.035, respectively. CONCLUSIONS: The results showed that the emphasis on improving college students' prevention cognition, supplemented by improving e-Health literacy and self-efficacy, could improve college students' healthy lifestyle behaviors. LIMITATIONS: This study was a cross-sectional investigation with no causal relationship between variables.


Assuntos
COVID-19 , Letramento em Saúde , COVID-19/prevenção & controle , Cognição , Estudos Transversais , Letramento em Saúde/métodos , Estilo de Vida Saudável , Humanos , Autoeficácia , Estudantes , Inquéritos e Questionários , Universidades
14.
Risk Manag Healthc Policy ; 15: 665-676, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35444476

RESUMO

Background: Turnover of medical staff is a vital issue in the global healthcare system. Previous evidence has confirmed the critical effect of distributive justice on turnover intention, but few studies have focused on the mediating mechanism behind this relationship or the medical staff. This study aimed to examine the mediating roles of organizational commitment and work engagement in the relationship between distributive justice and turnover intention of medical staff, and explore potential occupational differences. Methods: Stratified random sampling was adopted to select qualified medical staff from each clinical department of a large general hospital in Shenzhen, China, at a physician-to-nurse ratio of 1:1.5. The medical staff were surveyed using the Distributive Justice Scale, the Organizational Commitment Scale, the Work Engagement Scale, and the Turnover Intention Scale from May to July 2020. Of the 500 medical staff sampled, 480 responded (response rate: 96.00%), and 457 were finally included for analysis (effective response rate: 95.21%). A mediation analysis was performed using Model 6 of the SPSS macro PROCESS program. Results: There were significant positive correlations among distributive justice, organizational commitment, and work engagement and significant negative correlations among distributive justice, organizational commitment, work engagement, and turnover intention. Distributive justice directly and negatively affected the turnover intention of physicians and nurses, but there were occupational differences in the underlying mechanism between distributive justice and turnover intention. Distributive justice indirectly affected turnover intention among physicians mainly through the mediating effect of organizational commitment, and indirectly among nurses through three different pathways: the mediating effect of organizational commitment, the mediating effect of work engagement, and the chain mediating effect of organizational commitment and work engagement. Conclusion: The relationship between distributive justice and turnover intention was found to be mediated by organizational commitment and work engagement among medical staff in Shenzhen, with variations between physicians and nurses. Thus, appropriately targeted interventions are needed for physicians and nurses to reduce turnover intention.

15.
Math Biosci Eng ; 19(12): 13747-13781, 2022 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-36654066

RESUMO

Microarray technology has developed rapidly in recent years, producing a large number of ultra-high dimensional gene expression data. However, due to the huge sample size and dimension proportion of gene expression data, it is very challenging work to screen important genes from gene expression data. For small samples of high-dimensional biomedical data, this paper proposes a two-stage feature selection framework combining Wrapper, embedding and filtering to avoid the curse of dimensionality. The proposed framework uses weighted gene co-expression network (WGCNA), random forest and minimal redundancy maximal relevance (mRMR) for first stage feature selection. In the second stage, a new gene selection method based on the improved binary Salp Swarm Algorithm is proposed, which combines machine learning methods to adaptively select feature subsets suitable for classification algorithms. Finally, the classification accuracy is evaluated using six methods: lightGBM, RF, SVM, XGBoost, MLP and KNN. To verify the performance of the framework and the effectiveness of the proposed algorithm, the number of genes selected and the classification accuracy was compared with the other five intelligent optimization algorithms. The results show that the proposed framework achieves an accuracy equal to or higher than other advanced intelligent algorithms on 10 datasets, and achieves an accuracy of over 97.6% on all 10 datasets. This shows that the method proposed in this paper can solve the feature selection problem related to high-dimensional data, and the proposed framework has no data set limitation, and it can be applied to other fields involving feature selection.


Assuntos
Neoplasias , Humanos , Neoplasias/genética , Máquina de Vetores de Suporte , Algoritmos , Aprendizado de Máquina , Expressão Gênica
16.
ACS Appl Mater Interfaces ; 13(27): 32450-32460, 2021 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-34196518

RESUMO

Lead iodide (PbI2) as a layered material has emerged as an excellent candidate for optoelectronics in the visible and ultraviolet regime. Micrometer-sized flakes synthesized by mechanical exfoliation from bulk crystals or by physical vapor deposition have shown a plethora of applications from low-threshold lasing at room temperature to high-performance photodetectors with large responsivity and faster response. However, large-area centimeter-sized growth of epitaxial thin films of PbI2 with well-controlled orientation has been challenging. Additionally, the nature of grain boundaries in epitaxial thin films of PbI2 remains elusive. Here, we use mica as a model substrate to unravel the growth mechanism of large-area epitaxial PbI2 thin films. The partial growth leading to uncoalesced domains reveals the existence of inversion domain boundaries in epitaxial PbI2 thin films on mica. Combining the experimental results with first-principles calculations, we also develop an understanding of the thermodynamic and kinetic factors that govern the growth mechanism, which paves the way for the synthesis of high-quality large-area PbI2 on other substrates and heterostructures of PbI2 on single-crystalline graphene. The ability to reproducibly synthesize high-quality large-area thin films with precise control over orientation and tunable optical properties could open up unique and hitherto unavailable opportunities for the use of PbI2 and its heterostructures in optoelectronics, twistronics, substrate engineering, and strain engineering.

17.
Nat Commun ; 12(1): 3608, 2021 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-34127668

RESUMO

Heterobilayers of transition metal dichalcogenides (TMDCs) can form a moiré superlattice with flat minibands, which enables strong electron interaction and leads to various fascinating correlated states. These heterobilayers also host interlayer excitons in a type-II band alignment, in which optically excited electrons and holes reside on different layers but remain bound by the Coulomb interaction. Here we explore the unique setting of interlayer excitons interacting with strongly correlated electrons, and we show that the photoluminescence (PL) of interlayer excitons sensitively signals the onset of various correlated insulating states as the band filling is varied. When the system is in one of such states, the PL of interlayer excitons is relatively amplified at increased optical excitation power due to reduced mobility, and the valley polarization of interlayer excitons is enhanced. The moiré superlattice of the TMDC heterobilayer presents an exciting platform to engineer interlayer excitons through the periodic correlated electron states.

18.
Front Psychol ; 12: 800183, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-35126252

RESUMO

OBJECTIVE: The psychological condition of healthcare workers since the COVID-19 pandemic has attracted the attention of many studies. However, few have reported on psychosocial problems of primary healthcare workers in the COVID-19 pandemic. This study aimed to examine the mediating roles of social support and resilience in COVID-19-related work stress and symptoms of anxiety and depression. METHODS: A total of 840 primary healthcare workers in 17 community health centers in Guangzhou, China, were recruited from May to July 2021. Data on demographic characteristics, COVID-19-related work stress, social support, resilience, anxiety and depression were collected. A structural equation model was used for mediation analysis. RESULTS: More than half of participants reported mild or more severe (at least borderline abnormal) symptoms of anxiety (68.1%) and depression (55.6%). Social support and resilience mediate the association between COVID-19-related work stress and symptoms of anxiety and depression, respectively. Furthermore, the association between work stress and symptoms of anxiety and depression was also mediated by an accumulation of social support and resilience. The indirect effect of COVID-19-related work stress on anxiety and depression through resilience was much greater than other indirect effects. CONCLUSION: Anxiety and depression were prevalent among primary healthcare workers. This study highlights the psychological impact of the COVID-19-related psychosocial work environment on primary healthcare workers. There is an urgent need to improve working conditions for primary healthcare workers in the COVID-19 and to implement intervention strategies aimed at increasing individual resilience alongside the establishment of external supportive work environments.

19.
Nanoscale ; 11(10): 4226-4230, 2019 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-30806651

RESUMO

Graphene quantum dots (GQDs), a zero-dimensional material system with distinct physical properties, have great potential in the applications of photonics, electronics, photovoltaics, and quantum information. In particular, GQDs are promising candidates for quantum computing. In principle, a sub-10 nm size is required for GQDs to present the intrinsic quantum properties. However, with such an extreme size, GQDs have predominant edges with lots of active dangling bonds and thus are not stable. Satisfying the demands of both quantum size and stability is therefore of great challenge in the design of GQDs. Herein we demonstrate the fabrication of sub-10 nm stable GQD arrays by embedding GQDs into large-bandgap hexagonal boron nitride (h-BN). With this method, the dangling bonds of GQDs were passivated by the surrounding h-BN lattice to ensure high stability, meanwhile maintaining their intrinsic quantum properties. The sub-10 nm nanopore array was first milled in h-BN using an advanced high-resolution helium ion microscope and then GQDs were directly grown in them through the chemical vapour deposition process. Stability analysis proved that the embedded GQDs show negligible property decay after baking at 100 °C in air for 100 days. The success in preparing sub-10 nm stable GQD arrays will promote the physical exploration and potential applications of this unique zero-dimensional in-plane quantum material.

20.
Nanoscale ; 10(20): 9450-9454, 2018 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-29749414

RESUMO

Materials used for outdoor radiative cooling technologies need not only be transparent in the solar spectral region, but also need to have a broadband perfect absorption in the infrared atmospheric transparency window (infrared-ATW). Silicon carbide (SiC) has been thought to be a potential candidate for such materials. However, due to the near-perfect reflection of electromagnetic waves in the whole reststrahlen band (RB) of SiC, which is within the infrared-ATW, perfect absorption in the whole RB remains a challenge. Here by constructing a cone-pillar double-structure surface on SiC, a near-perfect absorption (>97%) of normally incident electromagnetic waves in the whole RB has been realized experimentally. Simulation results reveal that the dominant reason for the near-perfect absorption is the efficient coupling of incident electromagnetic waves into the bulk evanescent waves in the free-space wavelength range (10.33 µm, 10.55 µm) and the efficient coupling of incident electromagnetic waves into the surface phonon polaritons in the free-space wavelength range (10.55 µm, 12.6 µm). Our findings open up an avenue to enhance the absorption performance of SiC in infrared-ATW, and may lead to many new applications.

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