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1.
Ann Palliat Med ; 10(8): 9241-9248, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34488409

RESUMO

The large-scale exchange and spread of traditional Chinese medicine (TCM) in the West began in the 17th century. From the first English Chinese medicine book "gout collection" published in London in 1676, the British began to understand the mysterious and ancient oriental medicine of TCM. Britain is one of the earliest countries where TCM began to spread. TCM is an important carrier of China's excellent traditional culture. With the development of the world's medical technology and the continuous improvement of China's cultural soft power, the cross-cultural communication of TCM has become a characteristic business card for China to go to the world. For the research of a work, we must start from the source, so it is very important to first count the history of TCM external communication, and then systematically analyze and study the various phenomena in this history, so as to summarize the experience and inadequacy of TCM external communication process, and provide feasible guidance for future TCM research, And promote the effective development of TCM, and ultimately spread TCM culture to the international community more comprehensively and accurately. Although the greater than 300 hundred years' history of traditional Chinese medicine (TCM) spreading throughout Britain has been continuously mentioned in literature, studies on the historical development of TCM in Britain are rare. In this paper, the authors gathered information including the chronological statistics and stages of the 300 hundred years' dissemination of TCM in Britain, in order to provide more historical data and research materials for the spread of Chinese medicine in Britain.


Assuntos
Comunicação , Medicina Tradicional Chinesa , China , Londres
2.
Clin Interv Aging ; 16: 1337-1346, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34285478

RESUMO

Purpose: Limited information exists on fall-related fractures in older adults with cerebrovascular disease. This study aimed to determine the characteristics of older adults with cerebrovascular disease who sustained fall-related fractures and identify the associated risk factors for perioperative complications. Patients and Methods: This was a cross-sectional study, which included patients with cerebrovascular disease who sustained fractures between Jan. 2017 and Dec. 2019. The collected data included demographics (age and gender), time and place of fracture occurrence, mechanism of injury, fracture location, type of cerebrovascular disease, complications, and comorbidities. Results: A total of 768 patients with 815 fractures were included; there were 253 males and 515 females, with an average age of 78.3 years. For either males or females, 80-84 years was the most commonly involved age group. Most (61.0%) patients had their fractures occurring at home and most fractures (70.7%) occurred during the daytime. Most were hip fractures and limb weakness; instability-related falls were the most common cause of fracture, making a proportion of 34.5%. Patients who suffered falls were mainly combining ischemic cerebrovascular disease. Most (85.9%) patients presented with at least one comorbid disease and the perioperative complication rate was 76.9% in total cases. Age≥80 (OR: 1.772, 95% CI: 1.236-2.540) and the number of comorbidities≥3 (OR: 1.606, 95% CI: 1.035-2.494) were found independently associated with complications, while the type of cerebrovascular disease, fracture location, and comorbidities of prior fragility fracture and respiratory disease were not significantly correlated with complications. Conclusion: Our findings highlighted that more focus on improved physical function explored in intervention setting and the importance of primary home prevention measures seems justified in China and maybe other countries as well. It is the first study that presented the epidemiological characteristics of older adults with cerebrovascular disease who later experienced a fracture.


Assuntos
Acidentes por Quedas/estatística & dados numéricos , Transtornos Cerebrovasculares/epidemiologia , Fraturas Ósseas/epidemiologia , Idoso , Idoso de 80 Anos ou mais , Transtornos Cerebrovasculares/complicações , China/epidemiologia , Estudos Transversais , Feminino , Fraturas do Quadril/epidemiologia , Humanos , Masculino , Fatores de Risco
3.
ACS Nano ; 15(6): 9649-9657, 2021 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-34105943

RESUMO

Atomic structures and adatom geometries of surfaces encode information about the thermodynamics and kinetics of the processes that lead to their formation, and which can be captured by a generative physical model. Here we develop a workflow based on a machine-learning-based analysis of scanning tunneling microscopy images to reconstruct the atomic and adatom positions, and a Bayesian optimization procedure to minimize statistical distance between the chosen physical models and experimental observations. We optimize the parameters of a 2- and 3-parameter Ising model describing surface ordering and use the derived generative model to make predictions across the parameter space. For concentration dependence, we compare the predicted morphologies at different adatom concentrations with the dissimilar regions on the sample surfaces that serendipitously had different adatom concentrations. The proposed workflow can be used to reconstruct the thermodynamic models and associated uncertainties from the experimental observations of materials microstructures. The code used in the manuscript is available at https://github.com/saimani5/Adatom_interactions.

4.
Nanoscale Res Lett ; 16(1): 104, 2021 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-34114126

RESUMO

Two-dimensional Janus materials have great potential for the applications in spintronic devices due to their particular structures and novel characteristics. However, they are usually non-magnetic in nature. Here, different transition metals (TMs: Co, Fe, Mn, Cr, and V) adsorbed WSSe frameworks are constructed, and their structures and magnetic properties are comprehensively investigated by first-principles calculations. The results show that the top of W atom is the most stable absorption site for all the TM atoms, and all the systems exhibit magnetism. Moreover, their magnetic properties significantly depend on the adsorbed elements and the adsorbent chalcogens. A maximal total magnetic moment of 6 µB is obtained in the Cr-adsorbed system. The induced magnetism from S-surface-adsorption is always stronger than that for the Se-surface-adsorption due to its larger electrostatic potential. Interestingly, the easy magnetization axis in the Fe-adsorbed system switches from the in-plane to the out-of-plane when the adsorption surface changes from Se to S surface. The mechanism is analyzed in detail by Fe-3d orbital-decomposed density of states. This work provides a guidance for the modification of magnetism in low-dimensional systems.

5.
ACS Nano ; 2021 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-34181383

RESUMO

The adatom arrays on surfaces offer an ideal playground to explore the mechanisms of chemical bonding via changes in the local electronic tunneling spectra. While this information is readily available in hyperspectral scanning tunneling spectroscopy data, its analysis has been considerably impeded by a lack of suitable analytical tools. Here we develop a machine learning based workflow combining supervised feature identification in the spatial domain and unsupervised clustering in the energy domain to reveal the details of structure-dependent changes of the electronic structure in adatom arrays on the Co3Sn2S2 cleaved surface. This approach, in combination with first-principles calculations, provides insight for using artificial neural networks to detect adatoms and classifies each based on their local neighborhood comprised of other adatoms. These structurally classified adatoms are further spectrally deconvolved. The unexpected inhomogeneity of electronic structures among adatoms in similar configurations is unveiled using this method, suggesting there is not a single atomic species of adatoms, but rather multiple types of adatoms on the Co3Sn2S2 surface. This is further supported by a slight contrast difference in the images (or slight size variation) of the topography of the adatoms.

6.
Nanomaterials (Basel) ; 11(4)2021 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-33923517

RESUMO

The low-temperature scanning tunneling microscope and spectroscopy (STM/STS) are used to visualize superconducting states in the cleaved single crystal of 9% praseodymium-doped CaFe2As2 (Pr-Ca122) with Tc ≈ 30 K. The spectroscopy shows strong spatial variations in the density of states (DOS), and the superconducting map constructed from spectroscopy discloses a localized superconducting phase, as small as a single unit cell. The comparison of the spectra taken at 4.2 K and 22 K (below vs. close to the bulk superconducting transition temperature) from the exact same area confirms the superconducting behavior. Nanoscale superconducting states have been found near Pr dopants, which can be identified using dI/dV conductance maps at +300 mV. There is no correlation of the local superconductivity to the surface reconstruction domain and surface defects, which reflects its intrinsic bulk behavior. We, therefore, suggest that the local strain of Pr dopants is competing with defects induced local magnetic moments; this competition is responsible for the local superconducting states observed in this Fe-based filamentary superconductor.

7.
Nanotechnology ; 32(29)2021 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-33789254

RESUMO

The role of silver localized surface plasmons (LSPs) on the luminescence of a Si(111)-(7 × 7) surface has been investigated by scanning tunneling microscopy (STM) with a silver tip at 77 K. On a bare Si(111)-(7 × 7) surface, a characteristic peak at 1.85 eV dominates the STM-induced luminescence spectrum, although the luminescence intensity is extremely weak. Once Ag atoms are deposited onto the Si surface to form islands with a few atomic layers, it is found that the intensity of the characteristic peak from the Si surface underneath the Ag islands is significantly enhanced by about one order. In addition to the luminescence from the Si surface, light emission originating from the irradiation decay of the Ag plasmons is also detected. Such great enhancement of the luminescence from the Si surface is attributed to the strong coupling between the surface states of the Si and the LSPs of the Ag islands.

8.
Mol Med Rep ; 23(5)2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33760152

RESUMO

The aim of the present study was to investigate the neuroprotective effects of naringin on the memory impairment of hydrocortisone mice, and to elucidate the potential underlying molecular mechanisms. In the present study, a hydrocortisone model was constructed. Novel object recognition, Morris water maze and step­down tests were performed in order to assess the learning and memory abilities of mice. Hematoxylin and eosin staining was used to observe pathological changes in the hippocampus and hypothalamus. Transmission electron microscopy was used to observe the ultrastructural changes in the hippocampus. Immunohistochemistry was used to detect the expression of ERα and ERß. Western blotting was performed to detect the expression of each protein in the relevant system. It was found that naringin can significantly improve cognitive, learning and memory dysfunction in mice with hydrocortisone memory impairment. In addition, naringin can exert neuroprotective effects through a variety of mechanisms, including amyloid ß metabolism, Tau protein hyperphosphorylation, acetylcholinergic system, glutamate receptor system, oxidative stress and cell apoptosis. Naringin can also affect the expression of phosphorylated­P38/P38, indicating that the neuroprotective effect of naringin may also involve the MAPK/P38 pathway. The results of the present study concluded that naringin can effectively improve the cognitive abilities of mice with memory impairment and exert neuroprotective effects. Thus, naringin may be a promising target drug candidate for the treatment of Alzheimer's disease.


Assuntos
Doença de Alzheimer/tratamento farmacológico , Flavanonas/farmacologia , Transtornos da Memória/tratamento farmacológico , Proteínas tau/genética , Doença de Alzheimer/genética , Doença de Alzheimer/patologia , Animais , Modelos Animais de Doenças , Hipocampo/efeitos dos fármacos , Hipocampo/patologia , Humanos , Aprendizagem em Labirinto/efeitos dos fármacos , Transtornos da Memória/genética , Transtornos da Memória/patologia , Redes e Vias Metabólicas/efeitos dos fármacos , Camundongos , Fármacos Neuroprotetores/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Fosforilação/efeitos dos fármacos , Proteínas Quinases p38 Ativadas por Mitógeno/genética
9.
Sci Total Environ ; 763: 143028, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33129529

RESUMO

The growing incidence of microcystins (MCs) in the environment has become an issue of global concern for the high ecological and human health risks. Herein, a comparative adsorption of three MCs (MC-LR, MC-YR and MC-RR) by spent mushroom substrate (SMS)-derived biochars from contrasting pyrolytic conditions (temperature: 600/300 °C; and gas steam: CO2/N2) was surveyed to better understand the mechanisms and factors affecting the adsorption performance. For biochar preparation, 600 °C and CO2 led to greater levels of aromaticity, ash, SBET, and porosity, while 300 °C and N2 created more surface functional groups. The adsorption of MCs by biochars was a pH-dependent and endothermic physisorption process, following the pseudo-second-order kinetics (R2 = 0.99) and linear isotherm model (R2 > 0.88). The distribution coefficients Kd (0.98-19.2 L/kg) varied greatly among MCs (MC-YR > MC-RR > MC-LR) and biochars (BC600 > BN600 > BC300 > BN300), which depends on the combined effects of hydrophobicity, electrostatic attraction, H-bonding, cation bridging, and the amounts of adsorption sites on biochars. Higher ash, SBET, and total pore volume of BC600 facilitated the adsorption capacity for MCs relative to other biochars. Furthermore, the co-adsorption efficacy for MCs (Kd = 1.09-8.86 L/kg) was far below those for the single adsorption, indicating strong conflicts among competing MCs. This study sheds light on the roles of pyrolytic temperature and gas steam in biochar properties, and elucidates the mechanisms and factors affecting the adsorption performance of different MCs, which lays a foundation for MCs removal from water.


Assuntos
Carvão Vegetal , Microcistinas , Adsorção , Humanos , Pirólise
10.
Medicine (Baltimore) ; 99(47): e23246, 2020 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-33217845

RESUMO

BACKGROUND: This study aims to appraise the clinical efficacy of traditional Chinese medicine (TCM) for the management of patients with primary dysmenorrhea (PD) in the UK. METHODS: We will comprehensively search electronic databases (Cochrane Library, PUBMED/MEDLINE, EMBASE, PsycINFO, AMED, Web of Science, and CNKI) and additional resources for original articles on randomized controlled trials published in English, Chinese, German, Spanish, Korean and Japanese. Outcomes will be the pain intensity, pain duration, menstrual cramps, amount of bleeding, and severity of dysmenorrhea symptoms, quality of life, and adverse events. Two authors will independently check all citations, extract data, and assess study quality. All potential conflicts will be solved through discussion by consulting another experienced author. A narrative synthesis will summarize the characteristics and findings of eligible trials. If it is possible, we will also pool the data and carry out meta-analysis. RESULTS: The available evidence of the clinical efficacy of TCM for the treatment of PD in UK will be assessed through outcome measurements. CONCLUSION: The findings of this study will determine whether or not TCM is effective and safe for the treatment of PD in UK. OSF REGISTRATION NUMBER:: osf.io/jyc95.


Assuntos
Dismenorreia/terapia , Medicina Tradicional Chinesa , Feminino , Humanos , Ensaios Clínicos Controlados Aleatórios como Assunto , Projetos de Pesquisa , Revisões Sistemáticas como Assunto , Reino Unido
11.
J Tradit Chin Med ; 40(5): 870-874, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-33000589

RESUMO

OBJECTIVE: To investigate the clinical effects of Xinkeshu combined with levosimendan on perioperative heart failure in oldest-old patients with hip fractures. METHODS: Oldest-old patients over 80 years old with perioperative heart failure and hip fractures were randomly divided into the control and observation groups, with 50 patients in each group. All patients in both groups were treated with conventional anti-heart failure therapy and levosimendan, whereas patients in the observation group additionally received Xinkeshu tablets. Clinical manifestations; left ventricular ejection fraction (LVEF); left ventricular end-diastolic dimension (LVEDD); left ventricular end-systolic dimension (LVESD); B-type natriuretic peptide (BNP), superoxide dismutase (SOD), malondialdehyde (MDA), nitric oxide (NO), and endothelin-1 (ET-1) levels; and self-rating anxiety scale (SAS) and self-rating depression scale (SDS) scores were compared between before and after treatment to evaluate the curative effects of Xinkeshu combined with levosimendan. RESULTS: After treatment, the efficacy rate was significantly higher in the observation group than in the control group. LVEF and the levels of SOD and NO were higher in the observation group than in the control group after treatment. However, LVEDD; LVESD; BNP, MDA, and ET-1 levels; and the SAS and SDS scores were lower after treatment in the observation group than in the control group. CONCLUSION: Levosimendan combined with Xinkeshu can improve cardiac function, alleviate oxidative stress, and relieve anxiety and depression in oldest-old patients with perioperative heart failure and hip fracture.

12.
Vet Microbiol ; 247: 108750, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32768204

RESUMO

Streptococcus suis is a pig pathogen and a vector of zoonotic diseases that can cause severe systemic infection in humans. S. suis can colonize the nasal cavity, tonsils, and upper respiratory, genital, and digestive tracts in healthy pigs. Here, to determine prevalence, serotype distribution, and antimicrobial susceptibility of S. suis in healthy pigs, we collected 1813 nasal cavity samples from healthy pigs raised on 17 independent farms in six Chinese provinces between 2016 and 2018. We obtained 223 S. suis isolates (12.3 %) and the antimicrobial susceptibility to a panel of 11 antimicrobial agents was measured by microbroth dilution. Most S. suis isolates (98.7 %) were resistant to at least three classes of antimicrobial agents. The optrA gene conferring resistance to oxazolidinones and phenicols was identified in the chromosome of 27 isolates and on a ∼40-kb plasmid in one isolate; to the best of our knowledge, this was the first report of plasmid-borne optrA gene in S. suis. The genetic environment of optrA showed substantial diversity and could be divided into eleven different types. Interestingly, some fragments of the 89 K pathogenicity island (PAI) were observed together with optrA in 3 isolates, which warrants further attention. Capsular serotypes of S. suis isolates were determined by multiplex PCR. Serotype 29 was the most prevalent, followed by serotype 7 and serotype 2. The presence of highly virulent serotype 2 strains may pose a threat to public health.


Assuntos
Anti-Infecciosos/farmacologia , Cápsulas Bacterianas/classificação , Farmacorresistência Bacteriana Múltipla/genética , Oxazolidinonas/farmacologia , Infecções Estreptocócicas/veterinária , Streptococcus suis/efeitos dos fármacos , Animais , China/epidemiologia , Filogenia , Sorogrupo , Infecções Estreptocócicas/epidemiologia , Streptococcus suis/genética , Suínos , Doenças dos Suínos/epidemiologia , Doenças dos Suínos/microbiologia , Sequenciamento Completo do Genoma , Zoonoses/epidemiologia , Zoonoses/microbiologia
13.
Aging (Albany NY) ; 12(13): 13583-13593, 2020 07 10.
Artigo em Inglês | MEDLINE | ID: mdl-32649313

RESUMO

We aimed to investigate whether super elderly patients aged over 90 years had significantly worse functional outcomes, perioperative complications, and survival rates. Among 3560 patients aged over 65 years presenting with intertrochanteric fractures and treated surgically between Jan 2014 and Jan 2019, 2242 patients were included, including 206 in super elderly group and 2036 in elderly group. After using propensity score matching to minimize the effects of possible confounding variables, 192 remained in each group. No significant difference was observed in functional outcomes, perioperative complications, or 30-day, 90-day, and 1-year mortality after propensity score matching and McNemar's tests (p>0.05). After an average follow-up of 37 months, the Kaplan-Meier survival curve showed no significant difference between the two groups in terms of cumulative survival rate (p=0.081, log-rank). Our data demonstrated progressive increases in mortality and poor outcomes with increasing Elixhauser comorbidity scores, which represented the severity index of patients preoperatively. Our study also found that there were weak correlations between five characteristics and the patient age. These results all suggested that it is not the advanced age itself but other concomitant factors, that appear to be responsible for the adverse functional outcomes, perioperative complications, and mortality in super elderly patients.


Assuntos
Fixação Intramedular de Fraturas/efeitos adversos , Fraturas do Quadril/cirurgia , Complicações Pós-Operatórias/mortalidade , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Perda Sanguínea Cirúrgica/prevenção & controle , Perda Sanguínea Cirúrgica/estatística & dados numéricos , Transfusão de Sangue/estatística & dados numéricos , Comorbidade , Feminino , Fixação Intramedular de Fraturas/estatística & dados numéricos , Fraturas do Quadril/epidemiologia , Humanos , Estimativa de Kaplan-Meier , Masculino , Duração da Cirurgia , Complicações Pós-Operatórias/etiologia , Pontuação de Propensão , Medição de Risco/estatística & dados numéricos , Fatores de Risco , Taxa de Sobrevida , Resultado do Tratamento
14.
J Antimicrob Chemother ; 75(8): 2059-2065, 2020 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-32417908

RESUMO

BACKGROUND: Plasmid-mediated mechanisms of drug resistance accelerate the spread of polymyxin resistance, leaving clinicians with few or no antibacterial options for the treatment of infections caused by MDR bacteria, especially carbapenemase-producing strains. OBJECTIVES: To evaluate the associations among promoter sequence variation, mcr-1 expression, host factors and levels of colistin resistance and to propose antisense agents such as peptide nucleic acids (PNAs) targeting mcr-1 as a tool to restore colistin susceptibility through modulation of MCR-1 expression in Escherichia coli. METHODS: A ß-galactosidase assay was performed to study mcr-1 promoter activity. Quantitative real-time PCR and western blot assays were used to identify the expression level of MCR-1 in WT strains and transformants. Three PNAs targeting different regions of mcr-1 were designed and synthesized to determine whether they can effectively inhibit MCR-1 expression. MIC was measured to test colistin susceptibility in the presence or absence of PNA-1 in mcr-1-carrying E. coli. RESULTS: Variation in the mcr-1 promoter sequence and host species affect promoter activity, MCR-1 expression levels and colistin MICs. One PNA targeting the ribosome-binding site fully inhibited the expression of mcr-1 at a concentration of 4 µM, resulting in significantly increased susceptibility to colistin. The MIC90 of colistin decreased from 8 to 2 mg/L (P < 0.05) in the presence of 4 µM PNA. CONCLUSIONS: These findings suggest that the antisense approach is a possible strategy to combat mcr-1-mediated resistance as well as other causes of emerging global resistance.


Assuntos
Infecções por Escherichia coli , Proteínas de Escherichia coli , Ácidos Nucleicos Peptídicos , Antibacterianos/farmacologia , Colistina/farmacologia , Farmacorresistência Bacteriana , Escherichia coli/genética , Proteínas de Escherichia coli/genética , Humanos , Testes de Sensibilidade Microbiana , Ácidos Nucleicos Peptídicos/genética , Ácidos Nucleicos Peptídicos/farmacologia , Plasmídeos/genética
15.
Can J Physiol Pharmacol ; 98(5): 314-323, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32268073

RESUMO

The aim of this study was to investigate the effect and mechanism of miR-142-5p/212-5p on the proliferation and collagen formation of cardiac fibroblasts (CFs) after myocardial infarction (MI). The mouse MI model was established by ligation of the left anterior descending coronary artery. CFs were induced by transforming growth factor-beta 1 (TGF-ß1) or angiotensin (Ang II). The molecule expressions were measured by qRT-PCR and Western blot. CF proliferation was detected by an MTT assay. The effect of miR-142-5p/212-5p on the luciferase activity of c-Myc 3'UTR was assessed by the luciferase reporter assay. miR-142-5p and miR-212-5p were downregulated in cardiac tissues of MI mice and in TGF-ß1- or Ang II-induced CFs, while the protein levels of collagen I and III were upregulated. Moreover, simultaneous overexpression of miR-142-5p/212-5p inhibited the proliferation and collagen formation of TGF-ß1- or Ang II-stimulated CFs to a greater extent than either miR-142-5p or miR-212-5p overexpression alone. MiR-142-5p/212-5p targeted c-Myc and negatively regulated its expression. The effects of miR-142-5p/212-5p overexpression on the TP53INP1 protein level and the proliferation and collagen formation of CFs were reversed by c-Myc overexpression. Moreover, overexpression of miR-142-5p/212-5p improved cardiac function and collagen formation of MI mice. Overexpression of miR-142-5p/212-5p cooperatively suppresses the proliferation and collagen formation after MI by regulating c-Myc/TP53INP1.


Assuntos
Colágeno/biossíntese , Fibroblastos/citologia , MicroRNAs/genética , Miocárdio/citologia , Proteínas Nucleares/genética , Proteínas Proto-Oncogênicas c-myc/genética , Animais , Sequência de Bases , Proliferação de Células/genética , Fibroblastos/metabolismo , Camundongos , Infarto do Miocárdio/genética
16.
Nat Mater ; 19(6): 637-643, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32157191

RESUMO

Atomically thin two-dimensional (2D) metals may be key ingredients in next-generation quantum and optoelectronic devices. However, 2D metals must be stabilized against environmental degradation and integrated into heterostructure devices at the wafer scale. The high-energy interface between silicon carbide and epitaxial graphene provides an intriguing framework for stabilizing a diverse range of 2D metals. Here we demonstrate large-area, environmentally stable, single-crystal 2D gallium, indium and tin that are stabilized at the interface of epitaxial graphene and silicon carbide. The 2D metals are covalently bonded to SiC below but present a non-bonded interface to the graphene overlayer; that is, they are 'half van der Waals' metals with strong internal gradients in bonding character. These non-centrosymmetric 2D metals offer compelling opportunities for superconducting devices, topological phenomena and advanced optoelectronic properties. For example, the reported 2D Ga is a superconductor that combines six strongly coupled Ga-derived electron pockets with a large nearly free-electron Fermi surface that closely approaches the Dirac points of the graphene overlayer.

17.
J Phys Chem Lett ; 11(3): 740-746, 2020 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-31880944

RESUMO

The atomic and electronic structures of pristine PdSe2 as well as various intrinsic vacancy defects in PdSe2 are studied comprehensively by combining scanning tunneling microscopy, spectroscopy, and density functional theory calculations. Other than the topmost Se atoms, sublayer Pd atoms and the intrinsic Pd and Se vacancy defects are identified. Both VSe and VPd defects induce defect states near the Fermi level. As a result, the vacancy defects can be negatively charged by a tip gating effect. At negative sample bias, the screened Coulomb interaction between the scanning tunneling microscopy (STM) tip and the charged vacancies creates a disk-like protrusion around the VPd and crater-like features around VSe. The magnification effect of the long-range charge localization at the charged defect site makes sublayer defects as deep as 1 nm visible even in STM images. This result proves that by gating the probe, scanning probe microscopy can be used as an easy tool for characterizing sublayer defects in a nondestructive way.

18.
ACS Appl Mater Interfaces ; 11(27): 24132-24139, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31251572

RESUMO

Highly repeatable fabrication of compact perovskite films is crucial for large-area perovskite cells (PSCs) in commercial applications. In this work, a vapor-assisted method with the combination of spin-coating and thermal evaporation is employed to fabricate the double-layer PbI2/PbIxBr(2-x) precursor. It is found that surface morphologies of perovskite films could be tailored through tuning the spin-coating speed (the first precursor layer) and chemical compositions (the second precursor layer). The continuous pinhole-free perovskite films are successfully fabricated by double-layer PbI2/PbBr2 precursors. The open-circuit voltages of all the corresponding cells exceed 1.00 V, showing an average value of 1.02 V. The high mean voltage and small variation reveals high repeatability of this method. This work provides a potential method to achieve large-area and high-efficiency PSCs.

19.
BMC Med Inform Decis Mak ; 19(Suppl 2): 52, 2019 04 09.
Artigo em Inglês | MEDLINE | ID: mdl-30961607

RESUMO

BACKGROUND: Medical and clinical question answering (QA) is highly concerned by researchers recently. Though there are remarkable advances in this field, the development in Chinese medical domain is relatively backward. It can be attributed to the difficulty of Chinese text processing and the lack of large-scale datasets. To bridge the gap, this paper introduces a Chinese medical QA dataset and proposes effective methods for the task. METHODS: We first construct a large scale Chinese medical QA dataset. Then we leverage deep matching neural networks to capture semantic interaction between words in questions and answers. Considering that Chinese Word Segmentation (CWS) tools may fail to identify clinical terms, we design a module to merge the word segments and produce a new representation. It learns the common compositions of words or segments by using convolutional kernels and selects the strongest signals by windowed pooling. RESULTS: The best performer among popular CWS tools on our dataset is found. In our experiments, deep matching models substantially outperform existing methods. Results also show that our proposed semantic clustered representation module improves the performance of models by up to 5.5% Precision at 1 and 4.9% Mean Average Precision. CONCLUSIONS: In this paper, we introduce a large scale Chinese medical QA dataset and cast the task into a semantic matching problem. We also compare different CWS tools and input units. Among the two state-of-the-art deep matching neural networks, MatchPyramid performs better. Results also show the effectiveness of the proposed semantic clustered representation module.


Assuntos
Troca de Informação em Saúde , Redes Neurais de Computação , Algoritmos , China , Conjuntos de Dados como Assunto , Humanos , Semântica
20.
Phys Rev Lett ; 121(8): 086101, 2018 Aug 24.
Artigo em Inglês | MEDLINE | ID: mdl-30192587

RESUMO

Two-dimensional materials such as layered transition-metal dichalcogenides (TMDs) are ideal platforms for studying defect behaviors, an essential step towards defect engineering for novel material functions. Here, we image the 3D lattice locations of selenium-vacancy V_{Se} defects and manipulate them using a scanning tunneling microscope (STM) near the surface of PdSe_{2}, a recently discovered pentagonal layered TMD. The V_{Se} show a characterisitc charging ring in a spatially resolved conductance map, based on which we can determine its subsurface lattice location precisely. Using the STM tip, not only can we reversibly switch the defect states between charge neutral and charge negative, but also trigger migrations of V_{Se} defects. This allows a demonstration of direct "writing" and "erasing" of atomic defects and tracing the diffusion pathways. First-principles calculations reveal a small diffusion barrier of V_{Se} in PdSe_{2}, which is much lower than S vacancy in MoS_{2} or an O vacancy in TiO_{2}. This finding opens an opportunity of defect engineering in PdSe_{2} for such as controlled phase transformations and resistive-switching memory device application.

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