Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 14 de 14
Filtrar
1.
Nature ; 615(7950): 56-61, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36859579

RESUMO

Correlating atomic configurations-specifically, degree of disorder (DOD)-of an amorphous solid with properties is a long-standing riddle in materials science and condensed matter physics, owing to difficulties in determining precise atomic positions in 3D structures1-5. To this end, 2D systems provide insight to the puzzle by allowing straightforward imaging of all atoms6,7. Direct imaging of amorphous monolayer carbon (AMC) grown by laser-assisted depositions has resolved atomic configurations, supporting the modern crystallite view of vitreous solids over random network theory8. Nevertheless, a causal link between atomic-scale structures and macroscopic properties remains elusive. Here we report facile tuning of DOD and electrical conductivity in AMC films by varying growth temperatures. Specifically, the pyrolysis threshold temperature is the key to growing variable-range-hopping conductive AMC with medium-range order (MRO), whereas increasing the temperature by 25 °C results in AMC losing MRO and becoming electrically insulating, with an increase in sheet resistance of 109 times. Beyond visualizing highly distorted nanocrystallites embedded in a continuous random network, atomic-resolution electron microscopy shows the absence/presence of MRO and temperature-dependent densities of nanocrystallites, two order parameters proposed to fully describe DOD. Numerical calculations establish the conductivity diagram as a function of these two parameters, directly linking microstructures to electrical properties. Our work represents an important step towards understanding the structure-property relationship of amorphous materials at the fundamental level and paves the way to electronic devices using 2D amorphous materials.

2.
Proc Natl Acad Sci U S A ; 121(5): e2313397121, 2024 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-38252815

RESUMO

Non-small cell lung cancer (NSCLC), a major life-threatening disease accounting for 85% of all lung cancer cases, has been treated with tyrosine kinase inhibitors (TKIs), but often resulted in drug resistance, and approximately 60% of TKI-resistant cases are due to acquired secondary (epithelial growth factor receptor) EGFR-T790M mutation. To identify alternative targets for TKI-resistant NSCLC with EGFR-T790M mutation, we found that the three globo-series glycosphingolipids are increasingly expressed on this type of NSCLC cell lines, and among them, the increase of stage-specific embryonic antigen-4 (SSEA-4) expression is the most significant. Compared to TKI-sensitive cell lines, SSEA-4 and the key enzyme ß3GalT5 responsible for the synthesis of SSEA3 are more expressed in TKI-resistant NSCLC cell lines with EGFR-T790M mutation, and the expression levels strongly correlate with poor survival in patients with EGFR mutation. In addition, we demonstrated that a SSEA-4 targeted monoclonal antibody, especially the homogeneous glycoform with well-defined Fc glycan designed to improve effective functions, is highly effective against this subpopulation of NSCLC in cell-based and animal studies. These findings provide a direction for the prediction of tumor recurrence and treatment of TKI-resistant NSCLC with EGFR-T790M mutation.


Assuntos
Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Antígenos Embrionários Estágio-Específicos , Animais , Humanos , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Carcinoma Pulmonar de Células não Pequenas/genética , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/genética , Receptores ErbB/genética , Mutação , Inibidores de Proteínas Quinases/farmacologia , Inibidores de Proteínas Quinases/uso terapêutico , Recidiva Local de Neoplasia
3.
Nano Lett ; 22(7): 2725-2733, 2022 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-35293751

RESUMO

In van der Waals (vdW) heterostructures, the interlayer electron-phonon coupling (EPC) provides one unique channel to nonlocally engineer these elementary particles. However, limited by the stringent occurrence conditions, the efficient engineering of interlayer EPC remains elusive. Here we report a multitier engineering of interlayer EPC in WS2/boron nitride (BN) heterostructures, including isotope enrichments of BN substrates, temperature, and high-pressure tuning. The hyperfine isotope dependence of Raman intensities was unambiguously revealed. In combination with theoretical calculations, we anticipate that WS2/BN supercells could induce Brillouin-zone-folded phonons that contribute to the interlayer coupling, leading to a complex nature of broad Raman peaks. We further demonstrate the significance of a previously unexplored parameter, the interlayer spacing. By varying the temperature and high pressure, we effectively manipulated the strengths of EPC with on/off capabilities, indicating critical thresholds of the layer-layer spacing for activating and strengthening interlayer EPC. Our findings provide new opportunities to engineer vdW heterostructures with controlled interlayer coupling.

4.
Nanotechnology ; 31(30): 30LT02, 2020 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-32259802

RESUMO

The transition metal dichalcogenides (TMDCs) have been intensively investigated as promising nanoelectronic and optoelectronic materials. However, the pervasive adsorbates on the surfaces of monolayer TMDCs, including oxygen and water molecules from the ambient environment, tend to degrade the device performance, thus hindering specific applications. In this work, we report the effect of laser irradiation on the transport and photoresponse of monolayer MoS2 and WSe2 devices, and this laser annealing process is demonstrated as a straightforward approach to remove physically adsorbed contaminants. Compared to vacuum pumping and in situ thermal annealing treatments, the field-effect transistors after laser annealing show a more than one order of magnitude higher on-state current, and no apparent degradation of device performance at low temperatures. The mobility of the monolayer WSe2 devices can be enhanced by three to four times, and for single-layered MoS2 devices with the commonly used SiO2 as the back-gate, the mobility increases by 20 times, reaching [Formula: see text]. The efficient cleaning effect of laser annealing is also supported by the reduction of channel and contact resistance revealed by a transmission line experiment. Further, an enhanced photocurrent, by a factor of ten, has been obtained in the laser annealed device. These findings pave the way for high-performance monolayer TMDC-based electronic and optoelectronic devices with a clean surface and intrinsic properties.

5.
RSC Adv ; 14(24): 17032-17040, 2024 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-38808236

RESUMO

Nanopore technology, re-fueled by two-dimensional (2D) materials such as graphene and MoS2, controls mass transport by allowing certain species while denying others at the nanoscale and has a wide application range in DNA sequencing, nano-power generation, and others. With their low transmembrane transport resistance and high permeability stemming from their ultrathin nature, crystalline 2D materials do not possess nanoscale holes naturally, thus requiring additional fabrication to create nanopores. Herein, we demonstrate that nanopores exist in amorphous monolayer carbon (AMC) grown at low temperatures. The size and density of nanopores can be tuned by the growth temperature, which was experimentally verified by atomic images and further corroborated by kinetic Monte Carlo simulation. Furthermore, AMC films with varied degrees of disorder (DOD) exhibit tunable transmembrane ionic conductance over two orders of magnitude when serving as nanopore membranes. This work demonstrates the DOD-tuned property in amorphous monolayer carbon and provides a new candidate for modern membrane science and technology.

6.
Eur Eat Disord Rev ; 20(2): 169-73, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21830260

RESUMO

OBJECTIVE: Decision making is impaired in female patients with anorexia nervosa (AN), but it is unclear if the same impairment is present in male patients with AN. METHOD: Decision making was assessed in 48 AN individuals (19 male and 29 female patients) and 61 healthy controls (20 male and 41 female patients) using the Iowa Gambling Task (IGT). RESULTS: Both male and female patients with AN performed significantly worse than healthy controls on the IGT. No gender differences in IGT performance were found across groups. Male patients had higher impulsivity scores, but impulsivity had not predicted poor decision-making performance. DISCUSSION: Impaired decision making is present in male and female patients with AN. These data suggest that male patients with AN are very similar to female patients in decision making, and as a result, treatment approaches that seek to improve this ability should be similar in both genders.


Assuntos
Anorexia Nervosa/psicologia , Tomada de Decisões , Adolescente , Adulto , Anorexia Nervosa/fisiopatologia , Função Executiva , Jogo de Azar/psicologia , Humanos , Comportamento Impulsivo/psicologia , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Distribuição por Sexo , Espanha , Análise e Desempenho de Tarefas , Reino Unido , Adulto Jovem
7.
Fish Physiol Biochem ; 38(3): 777-87, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21986810

RESUMO

In mammals, androgens appear to enhance the development of primary ovarian follicles, but PI3K (phosphoinositide 3-kinases) pathway is well recognized as one of the critical pathways in early follicular development. Roles of the PI3K were revealed by deletion of PTEN (phosphatase and tensin homolog on chromosome 10). PTEN is demonstrated to play an important role in the early stage of follicle development. In the Japanese eel, two forms of PTEN have been cloned, but what their functions on the development of early ovarian follicles are still not clear. The natural blockage and inducible of ovarian development was a benefit to address this question in the eel. Testosterone (T) shows to ameliorate the early ovarian development in the eel. The aims of this study were to elucidate the two forms of PTEN by cellular and physiological criteria and to study the effects of T on the ovarian PTEN production in the exogenous pituitary extracts-stimulated eel. Our results suggested that two forms of PTEN are existing in the Japanese eel, and eel ovarian development corresponded to the decrease in ovarian PTEN expression, vice versa. In addition, the supplement of T on eel early ovarian development can be attributed to its PTEN inhibitor role.


Assuntos
Anguilla/crescimento & desenvolvimento , Anguilla/metabolismo , Proteínas de Peixes/metabolismo , Oócitos/efeitos dos fármacos , Oócitos/metabolismo , PTEN Fosfo-Hidrolase/metabolismo , Testosterona/administração & dosagem , Anguilla/genética , Animais , Sequência de Bases , DNA Complementar/genética , Feminino , Proteínas de Peixes/genética , Perfilação da Expressão Gênica , Isoenzimas/genética , Isoenzimas/metabolismo , Oócitos/crescimento & desenvolvimento , Ovário/efeitos dos fármacos , Ovário/crescimento & desenvolvimento , Ovário/metabolismo , PTEN Fosfo-Hidrolase/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais/efeitos dos fármacos
8.
Sci Rep ; 11(1): 6086, 2021 03 17.
Artigo em Inglês | MEDLINE | ID: mdl-33731735

RESUMO

Amaranthus tricolor L., a vegetable Amaranthus species, is an economically important crop containing large amounts of betalains. Betalains are natural antioxidants and can be classified into betacyanins and betaxanthins, with red and yellow colors, respectively. A. tricolor cultivars with varying betalain contents, leading to striking red to green coloration, have been commercially produced. However, the molecular differences underlying betalain biosynthesis in various cultivars of A. tricolor remain largely unknown. In this study, A. tricolor cultivars with different colors were chosen for comparative transcriptome analysis. The elevated expression of AmCYP76AD1 in a red-leaf cultivar of A. tricolor was proposed to play a key role in producing red betalain pigments. The functions of AmCYP76AD1, AmDODAα1, AmDODAα2, and AmcDOPA5GT were also characterized through the heterologous engineering of betalain pigments in Nicotiana benthamiana. Moreover, high and low L-DOPA 4,5-dioxygenase activities of AmDODAα1 and AmDODAα2, respectively, were confirmed through in vitro enzymatic assays. Thus, comparative transcriptome analysis combined with functional and enzymatic studies allowed the construction of a core betalain biosynthesis pathway of A. tricolor. These results not only provide novel insights into betalain biosynthesis and evolution in A. tricolor but also provide a basal framework for examining genes related to betalain biosynthesis among different species of Amaranthaceae.


Assuntos
Amaranthus , Betalaínas/biossíntese , Folhas de Planta , Amaranthus/genética , Amaranthus/metabolismo , Regulação Enzimológica da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Folhas de Planta/genética , Folhas de Planta/metabolismo
9.
Nanoscale ; 13(25): 11223-11231, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34151929

RESUMO

High-quality hexagonal BN (hBN) crystals, owing to their irreplaceable roles in new functional devices such as universal substrates and excellent layered insulators are exceedingly required in the field of two-dimensional (2D) materials. Although large-scale monolayer hBN crystals have been successfully grown on catalytic metals, the synthesis of large-area continuous hBN films with thickness in microns is challenging, hindering their applications at the mesoscopic level. Herein, we report the single-metal flux growth of centimeter-large, micron-thick, and high-quality continuous hBN films by balancing the grain size and coverage. The as-grown films can be readily exfoliated and transferred onto arbitrary substrates. Isotopically engineered hBN crystals can be obtained as well by the method. The narrow Raman line widths of the intralayer E2g mode peak (2.9 cm-1 for h11BN, 3.3 cm-1 for h10BN, and 7.9 cm-1 for hNaBN) and ultrahigh thermal conductivity (830 W m-1 K-1 for 4L h11BN) demonstrate high crystal quality and low defect density. Our results provide the foundation for the cost-efficient and lab-achievable synthesis of high-quality hBN films aimed at its mesoscopic applications.

10.
Phys Sportsmed ; 47(4): 427-432, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31027445

RESUMO

Objectives: Deformation of the coracoacromial ligament during overhead movement has been linked to shoulder pathologies such as impingement and rotator cuff tear. We, therefore, explored this relationship in a group of elite adolescent badminton players.Method: We performed bilateral shoulder physical and ultrasonographic examination in 35 adolescent asymptomatic badminton players, 13 players with unilateral shoulder pain, and 15 non-athletes of similar age. Coracoacromial ligament deformation, defined as the maximal vertical distance between the ligament apex to a line connecting the acromion and coracoid process, was measured during shoulder abduction and internal rotation and compared within and between groups. Other ultrasonographic measurements and the incidence of shoulder pathologies were also evaluated.Result: Among badminton athletes who reported dominant shoulder pain, coracoacromial ligament deformation was significantly larger in their dominant shoulder than in their non-dominant shoulder (3.5 and 2.0 mm, respectively; p = 0.013); this difference was not present in other groups. Regardless of the presence or absence of pain, athletes displayed more coracoacromial ligament deformation and increased supraspinatus tendon thickness in their dominant shoulder than did the control group. Abnormal ultrasound findings were noted in all groups; however, the incidence was not significantly different.Conclusion: Increased coracoacromial ligament deformation during overhead movement is associated with shoulder pain in elite adolescent badminton players. Our findings may help clinicians identify athletes at risk of subacromial impingement syndrome.


Assuntos
Articulação Acromioclavicular/lesões , Traumatismos em Atletas/patologia , Movimento , Esportes com Raquete , Síndrome de Colisão do Ombro/patologia , Articulação do Ombro/patologia , Ombro , Acrômio , Adolescente , Feminino , Humanos , Ligamentos/lesões , Masculino , Rotação , Manguito Rotador/patologia , Dor de Ombro
12.
J Med Food ; 13(6): 1415-23, 2010 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-20946021

RESUMO

Resveratrol has been shown to possess anticancer, anti-aging, anti-inflammatory, antimicrobial, and neuroprotective activities. In this study, we examined the antiproliferative properties of resveratrol and its molecular mechanism(s) of action in Huh-7 cells, a new human hepatoma cell line system for hepatitis C virus. Results showed that resveratrol significantly inhibited Huh-7 cell proliferation (50% inhibitory concentration = 22.4 µg/mL) and effectively induced cell cycle arrest and apoptosis. It up-regulated p21/WAF1 expression in a p53-independent manner, but the expressions of cyclin E, cyclin A, and cyclin-dependent kinase 2 were down-regulated. It also caused an increase in the ratio of pro-apoptotic/anti-apoptotic protein, which was associated with the mitochondrial membrane depolarization and the increase in caspase activity. Resveratrol showed no effect on Fas, Fas ligand, extracellular signal regulated kinase (ERK) 1/2, and p38 expression but down-regulated phospho-ERK and phospho-p38 expression. In addition, resveratrol was noted to trigger autophagic cell death through the increased expression of autophagy-related Atg5, Atg7, Atg9, and Atg12 proteins. These results suggest that resveratrol could be an important chemoprevention agent for hepatoma of hepatitis C virus infection.


Assuntos
Antineoplásicos Fitogênicos/farmacologia , Apoptose/efeitos dos fármacos , Carcinoma Hepatocelular/tratamento farmacológico , Ciclo Celular/efeitos dos fármacos , Neoplasias Hepáticas/tratamento farmacológico , Estilbenos/farmacologia , Autofagia/efeitos dos fármacos , Carcinoma Hepatocelular/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Quinase 2 Dependente de Ciclina/metabolismo , Inibidor de Quinase Dependente de Ciclina p21/metabolismo , Ciclinas/metabolismo , Regulação para Baixo/efeitos dos fármacos , Humanos , Concentração Inibidora 50 , Neoplasias Hepáticas/metabolismo , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Resveratrol , Fase S/efeitos dos fármacos , Fatores de Tempo , Regulação para Cima/efeitos dos fármacos
13.
J Clin Exp Neuropsychol ; 31(4): 455-61, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-18720180

RESUMO

BACKGROUND: Patients with eating disorders favor immediate gratification and ignore long-term negative consequences. This study investigated decision making in bulimia nervosa using the Iowa Gambling Task (IGT) and skin conductance responses (SCR). METHOD: A total of 26 bulimia nervosa patients and 51 healthy controls took part in this study; 29 patients with anorexia nervosa were included for comparison. RESULTS: Bulimia nervosa patients performed poorly in the IGT, but showed no decrease in anticipatory SCR, whereas a markedly diminished anticipatory SCR was seen in the anorexia nervosa group. CONCLUSIONS: This finding does not support the somatic marker hypothesis. Impaired decision making was associated with obsessive-compulsive traits.


Assuntos
Bulimia Nervosa/fisiopatologia , Bulimia Nervosa/psicologia , Tomada de Decisões/fisiologia , Testes Neuropsicológicos , Adolescente , Adulto , Feminino , Resposta Galvânica da Pele/fisiologia , Jogos Experimentais , Humanos , Pessoa de Meia-Idade , Tempo de Reação/fisiologia , Análise de Regressão , Adulto Jovem
14.
J Int Neuropsychol Soc ; 13(4): 635-41, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17521482

RESUMO

The objective of this study is to determine (a) if decision making ability is impaired in patients with anorexia nervosa (AN) and in people with good recovery from AN and (b) whether any impairment in decision making is associated with alterations in skin conductance responses (SCR). Patients with AN (n = 29), healthy controls comparable in age and IQ (HC, n = 29), and women long term recovered from AN (n = 14), completed the Iowa Gambling Task (IGT) while their SCR were measured. AN patients performed poorly in the IGT compared to the HC and to the recovered AN participants. AN patients had decreased anticipatory SCR prior to choosing cards and reduced SCR after losses compared to HC. IGT performance and the SCR of recovered AN participants did not differ from the HC. Decision making ability is impaired in AN. It is associated with a significantly attenuated SCR. Neither of these features are found in recovered AN. The association between impaired decision making ability and a decreased autonomic response is consistent with the predictions of the Somatic Marker Hypothesis.


Assuntos
Anorexia Nervosa/fisiopatologia , Anorexia Nervosa/psicologia , Tomada de Decisões/fisiologia , Resposta Galvânica da Pele/fisiologia , Jogo de Azar/psicologia , Adulto , Análise de Variância , Feminino , Jogos Experimentais , Humanos , Testes Neuropsicológicos/estatística & dados numéricos , Estatística como Assunto
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA