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1.
Pest Manag Sci ; 2021 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-33423351

RESUMO

BACKGROUND: Phytopathogenic bacteria, such as Xanthomonas oryzae pv. oryzae (Xoo) and Ralstonia solanacearum (Rs), seriously threaten crop production and cause enormous yield losses. Endophytic fungi are abundant sources of the bioactive metabolites, which can be potential candidates in the development of new agrochemicals. This work emphasized the discovery of bioactive polyketides from endophytic Alternaria alternata ZHJG5 and reported their structural elucidation, and antibacterial activities in detail. RESULTS: Five novel polyketide derivatives, isotalaroflavone (2), (±)-5'-dehydroxytalaroflavone (3a/3b), (+)-talaroflavone (4b), and bialternacin G (7), along with five known compounds (1, 4a, 5, 6, and 8), were obtained from the Cercis chinensis-derived fungus Alternaria alternata ZHJG5. The compound structures were characterized by spectroscopic methods and X-ray diffraction. Chiral HPLC was used to separate the racemates 3 and 4, whose absolute configurations were unambiguously confirmed by comparing their experimental and calculated ECD data. All isolated compounds were tested for antibacterial activities against the phytopathogenic bacteria Xoo, Xanthomonas oryzae pv. oryzicola (Xoc) and Rs. Compounds 1, 2 and 8 showed pronounced antibacterial activities against all tested bacteria, with MIC values ranging from 0.5 µg/mL to 64 µg/mL; in addition, compound 1 showed a potent protective effect against rice bacterial leaf blight caused by Xoo with the protective efficacy of 75.1% at a concentration of 200 µg/mL. CONCLUSION: These findings highlight the practical potential of the antibacterial compounds as candidates for the novel bactericide discovery. This article is protected by copyright. All rights reserved.

2.
ACS Nano ; 2021 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-33464036

RESUMO

Single-layer heterostructures exhibit striking quasiparticle properties and many-body interaction effects that hold promise for a range of applications. However, their properties can be altered by intrinsic and extrinsic defects, thus diminishing their applicability. Therefore, it is of paramount importance to identify defects and understand 2D materials' degradation over time using advanced multimodal imaging techniques. Here we implemented a liquid-phase precursor approach to synthesize 2D in-plane MoS2-WS2 heterostructures exhibiting nanoscale alloyed interfaces and map exotic interface effects during photodegradation using a combination of hyperspectral tip-enhanced photoluminescence and Raman and near-field nanoscopy. Surprisingly, 2D alloyed regions exhibit thermal and photodegradation stability providing protection against oxidation. Coupled with surface and interface strain, 2D alloy regions create stable localized potential wells that concentrate excitonic species via a charge carrier funneling effect. These results demonstrate that 2D alloys can withstand extreme degradation effects over time and could enable stable 2D device engineering.

3.
ACS Nano ; 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33450158

RESUMO

Realization of wafer-scale single-crystal films of transition metal dichalcogenides (TMDs) such as WS2 requires epitaxial growth and coalescence of oriented domains to form a continuous monolayer. The domains must be oriented in the same crystallographic direction on the substrate to inhibit the formation of inversion domain boundaries (IDBs), which are a common feature of layered chalcogenides. Here we demonstrate fully coalesced unidirectional WS2 monolayers on 2 in. diameter c-plane sapphire by metalorganic chemical vapor deposition using a multistep growth process to achieve epitaxial WS2 monolayers with low in-plane rotational twist (0.09°). Transmission electron microscopy analysis reveals that the WS2 monolayers are largely free of IDBs but instead have translational boundaries that arise when WS2 domains with slightly offset lattices merge together. By regulating the monolayer growth rate, the density of translational boundaries and bilayer coverage were significantly reduced. The unidirectional orientation of domains is attributed to the presence of steps on the sapphire surface coupled with growth conditions that promote surface diffusion, lateral domain growth, and coalescence while preserving the aligned domain structure. The transferred WS2 monolayers show neutral and charged exciton emission at 80 K with negligible defect-related luminescence. Back-gated WS2 field effect transistors exhibited an ION/OFF of ∼107 and mobility of 16 cm2/(V s). The results demonstrate the potential of achieving wafer-scale TMD monolayers free of inversion domains with properties approaching those of exfoliated flakes.

4.
ACS Nano ; 2021 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-33398991

RESUMO

In two-dimensional crystals, fractures propagate easily, thus restricting their mechanical reliability. This work demonstrates that controlled defect creation constitutes an effective approach to avoid catastrophic failure in MoS2 monolayers. A systematic study of fracture mechanics in MoS2 monolayers as a function of the density of atomic vacancies, created by ion irradiation, is reported. Pristine and irradiated materials were studied by atomic force microscopy, high-resolution scanning transmission electron microscopy, and Raman spectroscopy. By inducing ruptures through nanoindentations, we determine the strength and length of the propagated cracks within MoS2 atom-thick membranes as a function of the density and type of the atomic vacancies. We find that a 0.15% atomic vacancy induces a decrease of 40% in strength with respect to that of pristine samples. In contrast, while tear holes in pristine 2D membranes span several microns, they are restricted to a few nanometers in the presence of atomic and nanometer-sized vacancies, thus increasing the material's fracture toughness.

5.
J Alzheimers Dis ; 79(1): 237-247, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33252076

RESUMO

BACKGROUND: Predicting the prognosis of mild cognitive impairment (MCI) has outstanding clinical value, and the hippocampal volume is a reliable imaging biomarker of AD diagnosis. OBJECTIVE: We aimed to longitudinally assess hippocampal sub-regional difference (volume and asymmetry) among progressive MCI (pMCI), stable MCI (sMCI) patients, and normal elderly. METHODS: We identified 29 pMCI, 52 sMCI, and 102 normal controls (NC) from the ADNI database. All participants underwent neuropsychological assessment and 3T MRI scans three times. The time interval between consecutive MRI sessions was about 1 year. Volumes of hippocampal subfield were measured by Freesurfer. Based on the analysis of variance, repeated measures analyses, and receiver operating characteristic curves, we compared cross-sectional and longitudinal alteration sub-regional volume and asymmetry index. RESULTS: Compared to NC, both MCI groups showed significant atrophy in all subfields. At baseline, pMCI have a smaller volume than sMCI in the bilateral subiculum, molecular layer (ML), the molecular and granule cell layers of the dentate gyrus, cornu ammonis 4, and right tail. Furthermore, repeated measures analyses revealed that pMCI patients showed a faster volume loss than sMCI in bilateral subiculum and ML. After controlling for age, gender, and education, most results remained unchanged. However, none of the hippocampal sub-regional volumes performed better than the whole hippocampus in ROC analyses, and no asymmetric difference between pMCI and sMCI was found. CONCLUSION: The faster volume loss in subiculum and ML suggest a higher risk of disease progression in MCI patients. The hippocampal asymmetry may have smaller value in predicting the MCI prognosis.

6.
Food Chem ; 335: 127609, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-32739808

RESUMO

In this study, a fluorescence resonance energy transfer (FRET) immunoassay based on graphene oxide (GO) and up-converting nanoparticles (UCNPs) was established for rapid detection of imidacloprid, a commonly-used insecticide. Under 980 nm near-infrared light excitation, emission of UCNPs at 542 nm can be absorbed by the energy acceptor GO. The carboxyl-functionalized GO and UCNPs were coupled with competitive antigen and antibody against imidacloprid. After optimization, the FRET immunoassay showed a wide detection range of 0.08-50 ng/mL to imidacloprid, with cross-reaction toward other three neonicotinoids including imidaclothiz (74.4%), thiacloprid (36.9%) and clothianidin (31.9%). The average recoveries of spiked water, Chinese cabbage, cucumber, honey and tea samples were 76.8%-101.8%. The accuracy and reliability of the FRET immunoassay were verified by UPLC-MS/MS with a good correlation (R2 = 0.9816). In a summary, this study provides a sensitive and one-step method for monitoring imidacloprid residue in food and environmental samples within 1 h.


Assuntos
Grafite/química , Nanopartículas/química , Neonicotinoides/análise , Nitrocompostos/análise , Cromatografia Líquida , Transferência Ressonante de Energia de Fluorescência/métodos , Imunoensaio/métodos , Limite de Detecção , Reprodutibilidade dos Testes , Espectrometria de Massas em Tandem , Tiazóis
7.
BMJ Open ; 10(12): e039813, 2020 12 24.
Artigo em Inglês | MEDLINE | ID: mdl-33361074

RESUMO

INTRODUCTION: With the threat of a worldwide pandemic of COVID-19, it is important to identify the prognostic factors for critical conditions among patients with non-critical COVID-19. Prognostic factors and models may assist front-line clinicians in rapid identification of high-risk patients, early management of modifiable factors, appropriate triaging and optimising the use of limited healthcare resources. We aim to systematically assess the clinical, laboratory and imaging predictors as well as prediction models for severe or critical illness and mortality in patients with COVID-19. METHODS AND ANALYSIS: All peer-reviewed and preprint primary articles with a longitudinal design that focused on prognostic factors or models for critical illness and mortality related to COVID-19 will be eligible for inclusion. A systematic search of 11 databases including PubMed, EMBASE, Web of Science, Cochrane Library, CNKI, VIP, Wanfang Data, SinoMed, bioRxiv, Arxiv and MedRxiv will be conducted. Study selection will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Data extraction will be performed using the modified version of the Critical Appraisal and Data Extraction for Systematic Reviews of Prediction Modelling Studies checklist and quality will be evaluated using the Newcastle-Ottawa Scale and the Quality In Prognosis Studies tool. The association between prognostic factors and outcomes of interest will be synthesised and a meta-analysis will be conducted with three or more studies reporting a particular factor in a consistent manner. ETHICS AND DISSEMINATION: Ethical approval was not required for this systematic review. We will disseminate our findings through publication in a peer-reviewed journal. PROSPERO REGISTRATION NUMBER: CRD 42020178798.


Assuntos
/diagnóstico , Serviços de Laboratório Clínico , Estado Terminal/epidemiologia , Diagnóstico por Imagem/métodos , Pandemias , /epidemiologia , Saúde Global , Humanos , Morbidade/tendências , Prognóstico , Taxa de Sobrevida/tendências
8.
Sensors (Basel) ; 21(1)2020 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-33374281

RESUMO

Recognizing user emotions while they watch short-form videos anytime and anywhere is essential for facilitating video content customization and personalization. However, most works either classify a single emotion per video stimuli, or are restricted to static, desktop environments. To address this, we propose a correlation-based emotion recognition algorithm (CorrNet) to recognize the valence and arousal (V-A) of each instance (fine-grained segment of signals) using only wearable, physiological signals (e.g., electrodermal activity, heart rate). CorrNet takes advantage of features both inside each instance (intra-modality features) and between different instances for the same video stimuli (correlation-based features). We first test our approach on an indoor-desktop affect dataset (CASE), and thereafter on an outdoor-mobile affect dataset (MERCA) which we collected using a smart wristband and wearable eyetracker. Results show that for subject-independent binary classification (high-low), CorrNet yields promising recognition accuracies: 76.37% and 74.03% for V-A on CASE, and 70.29% and 68.15% for V-A on MERCA. Our findings show: (1) instance segment lengths between 1-4 s result in highest recognition accuracies (2) accuracies between laboratory-grade and wearable sensors are comparable, even under low sampling rates (≤64 Hz) (3) large amounts of neutral V-A labels, an artifact of continuous affect annotation, result in varied recognition performance.

9.
Artigo em Inglês | MEDLINE | ID: mdl-33317319

RESUMO

Rising health concerns and increasing obesity levels in human society have led some consumers to cut back on animal protein consumption and switch to plant-based proteins as an alternative. Soy protein is a versatile protein supplement and contains well-balanced amino acids, making it comparable to animal protein. With sufficient processing and modification, the quality of soy protein can be improved above that of animal-derived proteins, if desired. The modern food industry is undergoing a dynamic change, with advanced processing technologies that can produce a multitude of foods and ingredients with functional properties from soy proteins, providing consumers with a wide variety of foods. This review highlights recent progress in soy protein processing technologies. Using the current literature, the processing-induced structural changes in soy protein are also explored. Furthermore, the molecular structure of soy protein, particularly the crystal structures of ß-conglycinin and glycinin, is comprehensively revisited. Expected final online publication date for the Annual Review of Food Science and Technology, Volume 12 is March 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

10.
Drug Deliv ; 27(1): 1718-1728, 2020 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-33307846

RESUMO

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive pulmonary disease that can cause fibrotic remodeling of the surrounding lung, thus leading to respiratory failure. Although IPF is the most common form of idiopathic interstitial pneumonia, the precise mechanisms underlying this condition remain unknown. In this study, we used total saponins of Panax notoginseng inhalation solution (TIS) to induce idiopathic bleomycin-induced pulmonary fibrosis in rats. The uniformity of delivery dose was investigated by analyzing the aerodynamic particle size distribution and drug stability. The potential of hydrogen potential of hydrogen (pH) of the inhalation solution was 7.0 and the solvent 0.9% NaCl solution, thus meeting physiological requirements for pulmonary drug administration. The delivery rate was 1.94 ± 0.16 mg·min-1 and the total dose was 17.40 ± 0.04 mg. TIS was composed of five key components: notoginsenoside R1, ginsenosides Rg1, ginsenosides Re, ginsenosides Rb1, and ginsenosides Rd. The mass median aerodynamic diameter (MMAD) for these five components were 3.62 ± 0.05 µm, 3.62 ± 0.06 µm, 3.65 ± 0.10 µm, 3.62 ± 0.06 µm, and 3.61 ± 0.05 µm, respectively. Fine particle fraction (FPF) was 66.24 ± 0.73%, 66.20 ± 0.89%, 66.07 ± 1.42%, 66.18 ± 0.79%, and 66.29 ± 0.70%, respectively. The MMAD for inhalation solutions needs to be 1-5 µm, which indicates that the components of TIS are suitable for inhalation. It is important to control the particle size of targeted drugs to ensure that the drug is delivered to the appropriate target tissue. In vitro experiments indicated that TIS exhibited high rates of deposition in lung tissue, thus indicating that pulmonary delivery systems may represent a good therapeutic option for patients.

11.
Mol Divers ; 2020 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-33200293

RESUMO

Here, two series of novel ursolic acid-based 1,2,4-triazolo[1,5-a]pyrimidines derivatives were synthesized and screened for their anti-inflammatory activity by evaluating their inhibition effect of using LPS-induced inflammatory response in RAW 264.7 macrophages in vitro; the effects of different concentrations of the compounds on the secretion of nitric oxide (NO) and inflammatory cytokines including TNF-α and IL-6 were evaluated. Their toxicity was also assessed in vitro. Results showed that the most prominent compound 3 could significantly decrease production of the above inflammatory factors. Docking study was performed for the representative compounds 3, UA, and Celecoxib to explain their interaction with cyclooxygenase-2 (COX-2) receptor active site. In vitro enzyme study implied that compound 3 exerted its anti-inflammatory activity through COX-2 inhibition.

12.
Clin Interv Aging ; 15: 2095-2107, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33204075

RESUMO

Objective: Severe or critical patients with coronavirus disease 2019 (COVID-19) are at increased risk for developing acute kidney injury (AKI). However, the rate of AKI in patients of different severities and independent predictive factors associated with AKI are not well understood. Patients and Methods: We enrolled 107 severely or critically ill elderly patients with COVID-19 who were admitted to the intensive care unit (ICU) in Wuhan, China. AKI was defined according to the 2012 KDIGO criteria. We explored the association between AKI and in-hospital mortality using logistic regression. A predictive nomogram was formulated to predict the AKI development of patients with COVID-19 based on multivariate logistic regression. Results: A total of 107 elderly patients were enrolled during the study period. The mean age was 70 (64-78) years, and 69 (64.5%) were men. For the 107 patients, the degree of severity of COVID-19 was categorized as 37 patients with the severe type (34.6%) and 70 patients with the critical type (65.4%). Overall, 48 of the 107 patients (44.9%) developed AKI during their hospitalization, while AKI occurred in 7 (18.9%) out of the 37 severe patients and 41 (44.9%) out of the 70 critical patients. Of the AKI patients, 35.4% (17/48) required continuous renal replacement therapy, including 14.3% of AKI patients in severe cases and 39.0% of AKI patients in critical cases. Kaplan-Meier analysis demonstrated that patients with AKI had a significantly higher risk for in-hospital mortality than severely and critically ill patients without AKI. Multivariate logistic regression analysis showed that AKI (OR = 33.74; 95% CI = 3.34-341.29; P = 0.003), septic shock (OR = 15.58; 95% CI = 2.08-116.78; P = 0.008), invasive mechanical ventilation (OR = 18.44; 95% CI = 2.35-144.69; P = 0.006), and oxygenation index (OR = 0.99; 95% CI = 0.98-1.000; P = 0.014) were independent risk factors for in-hospital mortality. A nomogram was established based on the multivariate analysis results. The C-index for the developed AKI model was 0.935 (95% CI, 0.892-0.978); when 10-fold cross validation was used to validate the model, the corrected C-index was 0.825. Conclusion: AKI is common among COVID-19 patients admitted to the ICU and is recognized as a marker of disease severity. The proposed nomogram accurately predicted AKI development in ICU patients with COVID-19 based on individual characteristics. Therefore, the strategy for kidney protection against severe or critical pneumonia is appropriate.


Assuntos
Lesão Renal Aguda , Infecções por Coronavirus , Mortalidade Hospitalar , Pandemias , Pneumonia Viral , Lesão Renal Aguda/diagnóstico , Lesão Renal Aguda/epidemiologia , Lesão Renal Aguda/etiologia , Idoso , Betacoronavirus/isolamento & purificação , China/epidemiologia , Infecções por Coronavirus/complicações , Infecções por Coronavirus/mortalidade , Estado Terminal/mortalidade , Feminino , Humanos , Unidades de Terapia Intensiva/estatística & dados numéricos , Masculino , Nomogramas , Pneumonia Viral/complicações , Pneumonia Viral/mortalidade , Prognóstico , Estudos Retrospectivos , Fatores de Risco , Índice de Gravidade de Doença
13.
BMC Med Inform Decis Mak ; 20(1): 247, 2020 09 29.
Artigo em Inglês | MEDLINE | ID: mdl-32993652

RESUMO

BACKGROUND: The recent Coronavirus Disease 2019 (COVID-19) pandemic has placed severe stress on healthcare systems worldwide, which is amplified by the critical shortage of COVID-19 tests. METHODS: In this study, we propose to generate a more accurate diagnosis model of COVID-19 based on patient symptoms and routine test results by applying machine learning to reanalyzing COVID-19 data from 151 published studies. We aim to investigate correlations between clinical variables, cluster COVID-19 patients into subtypes, and generate a computational classification model for discriminating between COVID-19 patients and influenza patients based on clinical variables alone. RESULTS: We discovered several novel associations between clinical variables, including correlations between being male and having higher levels of serum lymphocytes and neutrophils. We found that COVID-19 patients could be clustered into subtypes based on serum levels of immune cells, gender, and reported symptoms. Finally, we trained an XGBoost model to achieve a sensitivity of 92.5% and a specificity of 97.9% in discriminating COVID-19 patients from influenza patients. CONCLUSIONS: We demonstrated that computational methods trained on large clinical datasets could yield ever more accurate COVID-19 diagnostic models to mitigate the impact of lack of testing. We also presented previously unknown COVID-19 clinical variable correlations and clinical subgroups.


Assuntos
Técnicas de Laboratório Clínico/métodos , Infecções por Coronavirus/diagnóstico , Influenza Humana/diagnóstico , Aprendizado de Máquina , Pneumonia Viral/diagnóstico , Betacoronavirus , Simulação por Computador , Infecções por Coronavirus/classificação , Conjuntos de Dados como Assunto , Diagnóstico Diferencial , Feminino , Humanos , Vírus da Influenza A , Masculino , Pandemias/classificação , Pneumonia Viral/classificação , Sensibilidade e Especificidade
14.
Eur J Med Chem ; 203: 112517, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32846314

RESUMO

Aberrant activation of p21-activated kinase 1 (PAK1) is associated with tumour progression, and PAK1 has been recognized as a promising target for anticancer drug discovery. However, the development of potent PAK1 inhibitors with satisfactory kinase selectivity and favourable physicochemical properties remains a daunting challenge. Herein, we identified the 1H-indazole-3-carboxamide derivatives as potential PAK1 inhibitors using a fragment-based screening approach. The representative compound 30l exhibited excellent enzyme inhibition (PAK1 IC50 = 9.8 nM) and high PAK1 selectivity toward a panel of 29 kinases. The Structure-activity relationship (SAR) analysis showed that substituting of an appropriate hydrophobic ring in the deep back pocket and introducing a hydrophilic group in the bulk solvent region were critical for PAK1 inhibitory activity and selectivity. Additionally, the hERG channel activity of 30l demonstrated its low risk of hERG toxicity. Furthermore, it significantly suppressed the migration and invasion of MDA-MB-231 cells by downregulating Snail expression without affecting the tumour growth. These results provide a new type of chemical scaffolds targeting PAK1 and suggested that 1H-indazole-3-carboxamide derivatives may serve as lead compounds for the development of potential and selective PAK1 inhibitors.

15.
J Tradit Chin Med ; 40(4): 690-702, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32744037

RESUMO

OBJECTIVE: To analyze clinical studies on correlations between Traditional Chinese Medicine (TCM) body constitution types and diseases published in the past 10 years, and to provide an evidence base to support the use of such correlations for health maintenance and disease prevention. METHODS: We searched five databases for the period April 2009 to December 2019: China National Knowledge Infrastructure Database, Wanfang Database, China Science and Technology Journal Database, PubMed and Embase. Three types of observational studies on correlation between constitution types and diseases were included: cross-sectional, case-control and cohort studies. Descriptive statistical methods were employed for data analysis. RESULTS: A total of 1639 clinical studies were identified: 1452 (88.59%) cross-sectional studies, 115 (7.02%) case-control studies and 72 (4.39%) cohort studies covering 30 regions of China and five other countries (Malaysia, South Korea, Singapore, Thailand and France). The collection of studies comprised 19 disease categories and 333 different diseases. The 10 most commonly studied diseases were hypertension, diabetes, stroke, coronary atherosclerotic heart disease (CAHD), sleep disorders, neoplasm of the breast, dysmenorrhea, fatty liver disease, chronic viral hepatitis B and dyslipidemia. We found high distributions for each biased constitution type in different patient populations as follows: Qi-deficiency constitution in stroke, diabetes, chronic obstructive pulmonary disease, acquired immunodeficiency syndrome and hypertension; Yang-deficiency constitution in female infertility, osteoporosis, irritable bowel syndrome, gonarthrosis and dysmenorrhea; Yin-deficiency constitution in hypertension, diabetes, constipation, female climacteric states and osteoporosis; phlegm- dampness constitution in hypertension, stroke, fatty liver disease, diabetes and metabolic syndrome; damp-heat constitution in acne, chronic gastritis, chronic viral hepatitis B, human papillomavirus infection and hyperuricemia; blood-stasis constitution in CAHD, endometriosis and stroke; Qi-stagnation constitution in hyperplasia and neoplasms of the breast, insomnia, depression and thyroid nodules; and inherited-special constitution in asthma and allergic rhinitis. CONCLUSION: Eight biased TCM constitutions were closely related to specific diseases, and could be used to guide individualized prevention and treatment. More rigorously designed studies are recommended to further verify the constitution-disease relationship.

16.
Artigo em Inglês | MEDLINE | ID: mdl-32727904

RESUMO

Stacking layers of atomically thin transition-metal carbides and two-dimensional (2D) semiconducting transition-metal dichalcogenides, could lead to nontrivial superconductivity and other unprecedented phenomena yet to be studied. In this work, superconducting α-phase thin molybdenum carbide flakes were first synthesized, and a subsequent sulfurization treatment induced the formation of vertical heterolayer systems consisting of different phases of molybdenum carbide-ranging from α to γ' and γ phases-in conjunction with molybdenum sulfide layers. These transition-metal carbide/disulfide heterostructures exhibited critical superconducting temperatures as high as 6 K, higher than that of the starting single-phased α-Mo2C (4 K). We analyzed possible interface configurations to explain the observed moiré patterns resulting from the vertical heterostacks. Our density-functional theory (DFT) calculations indicate that epitaxial strain and moiré patterns lead to a higher interfacial density of states, which favors superconductivity. Such engineered heterostructures might allow the coupling of superconductivity to the topologically nontrivial surface states featured by transition-metal carbide phases composing these heterostructures potentially leading to unconventional superconductivity. Moreover, we envisage that our approach could also be generalized to other metal carbide and nitride systems that could exhibit high-temperature superconductivity.

17.
Int J Mol Sci ; 21(14)2020 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-32708403

RESUMO

Chronic myeloid leukemia (CML) is a malignant tumor caused by the abnormal proliferation of hematopoietic stem cells. Among a new series of acridone derivatives previously synthesized, it was found that the methoxybenzyl 5-nitroacridone derivative 8q has nanomolar cytotoxicity in vitro against human chronic myelogenous leukemia K562 cells. In order to further explore the possible anti-leukemia mechanism of action of 8q on K562 cells, a metabolomics and molecular biology study was introduced. It was thus found that most of the metabolic pathways of the G1 phase of K562 cells were affected after 8q treatment. In addition, a concentration-dependent accumulation of cells in the G1 phase was observed by cell cycle analysis. Western blot analysis showed that 8q significantly down-regulated the phosphorylation level of retinoblastoma-associated protein (Rb) in a concentration-dependent manner, upon 48 h treatment. In addition, 8q induced K562 cells apoptosis, through both mitochondria-mediated and exogenous apoptotic pathways. Taken together, these results indicate that 8q effectively triggers G1 cell cycle arrest and induces cell apoptosis in K562 cells, by inhibiting the CDK4/6-mediated phosphorylation of Rb. Furthermore, the possible binding interactions between 8q and CDK4/6 protein were clarified by homology modeling and molecular docking. In order to verify the inhibitory activity of 8q against other chronic myeloid leukemia cells, KCL-22 cells and K562 adriamycin-resistant cells (K562/ADR) were selected for the MTT assay. It is worth noting that 8q showed significant anti-proliferative activity against these cell lines after 48 h/72 h treatment. Therefore, this study provides new mechanistic information and guidance for the development of new acridones for application in the treatment of CML.

18.
Nanoscale ; 12(33): 17196-17202, 2020 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-32667372

RESUMO

Zoledronic acid (ZA) is a bisphosphonate (BP) drug that has been widely used in clinical treatments as a potent bone resorption inhibitor. In recent years, an increasing number of cases of bisphosphonate-associated osteonecrosis of the jaw (BRONJ) have been reported. This is a severe maxillofacial complication characterized clinically by bone exposure, necrosis, pain, and halitosis. Its pathogenesis is still not clear, and there is no effective clinical treatment known. Therefore, prevention of BRONJ is especially important. To provide a new research direction for the treatment of BRONJ, this study used a new tetrahedral framework nucleic acid (TFNA), which can antagonize the inhibitory effect of ZA on the differentiation and maturation of osteoclasts (OCs). In vivo and in vitro experiments showed that TFNAs at a specific concentration exhibited no cytotoxicity and could reverse the inhibition of ZA on OC differentiation and maturation, effectively inhibiting the formation of BRONJ.

19.
Cereb Cortex ; 30(11): 5863-5873, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32537637

RESUMO

During the progression of Alzheimer's disease (AD), neuropathology may propagate transneuronally, cause disruption in memory circuit, and lead to memory impairment. However, there is a lack of in vivo evidence regarding this process. Thus, we aim to simulate and observe the progression of neuropathology in AD continuum. We included cognitively normal (CN), mild cognitive impairments (MCI), and AD subjects, and further classified them using the A/T/N scheme (Group 0: CN, A - T-; Group 1: CN, A + T-; Group 2: CN, A + T+; Group 3: MCI, A + T+; Group 4: AD, A + T+). We investigated alterations of three core memory circuit structures: hippocampus (HP) subfields volume, cingulum-angular bundles (CAB) fiber integrity, and precuneus cortex volume. HP subfields volume showed the trend of initially increased and then decreased (starting from Group 2), while precuneus volume decreased in Groups 3 and 4. The CAB integrity degenerated in Groups 3 and 4 and aggravated with higher disease stages. Further, memory circuit impairments were correlated with neuropathology biomarkers and memory performance. Conclusively, our results demonstrated a pattern of memory circuit impairments along with AD progression: starting from the HP, then propagating to the downstream projection fiber tract and cortex. These findings support the tau propagation theory to some extent.

20.
Luminescence ; 35(8): 1277-1285, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32524730

RESUMO

Carbon dots (CDs) have drawn increasing interests due to their unique optical properties and promising application in various fields. In this study, citric acid (CA) and 5-chloromethyl-8-hydroxyquinoline (LQ) were used to synthesize nitrogen-doped CDs as novel fluorescent probes using a one-step solvothermal route. The as-prepared CDs had strong blue-white fluorescence emission when excited at 405 nm wavelength with a quantum yield (QY) of 25%, behaving with high ion concentration stability. Water-soluble CDs with a 8-hydroxyquinoline structure on their surface could be used to detect Al3+ using a 'turn on' mechanism and trinitrophenol (TNP) using a 'turn off' mechanism with detection limits of 229 nM and 44.4 nM, respectively. Al3+ enhances the fluorescence of CDs by forming a coordination complex to generate a fluorescence synergistic role and limit CD nonradiative transition. TNP quenched the fluorescence with high selectivity and sensitivity, which was attributed to the inner filter effect and static quenching. These results indicated that these CDs with their unique 'turn on' and 'turn off' nature have potential application in the environmental protection field and in prevention of terrorist threats.

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