Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 10 de 10
Filtrar
Filtros adicionais











Intervalo de ano
1.
ACS Appl Mater Interfaces ; 11(36): 33188-33193, 2019 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-31415147

RESUMO

Metal-semiconductor-metal (MSM)-structured GaAs-based nanowire photodetectors have been widely reported because they are promising as an alternative for high-performance devices. Owing to the Schottky built-in electric fields in the MSM structure photodetectors, enhancements in photoresponsivity can be realized. Thus, strengthening the built-in electric field is an efficacious way to make the detection capability better. In this study, we fabricate a single GaAs nanowire MSM photodetector with superior performance by doping-adjusting the Fermi level to strengthen the built-in electric field. An outstanding responsivity of 1175 A/W is obtained. This is two orders of magnitude better than the responsivity of the undoped sample. Scanning photocurrent mappings and simulations are performed to confirm that the enhancement in responsivity is because of the increase in the hole Schottky built-in electric field, which can separate and collect the photogenerated carriers more effectively. The eloquent evidence clearly proves that doping-adjusting the Fermi level has great potential applications in high-performance GaAs nanowire photodetectors and other functional photodetectors.

2.
Nanoscale Res Lett ; 13(1): 369, 2018 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-30460420

RESUMO

The enhancement of optical properties via thermal annealing on InP/ZnS core/shell quantum dot (QD) film was investigated in this work. The increase of emission intensities of the QD films was observed after thermal annealing at 180 °C for 5 min. Through temperature dependence photoluminescence (TDPL) and power dependence photoluminescence (PL) measurement, the peak located at the low-energy shoulder was confirmed to be localized state emission and the high energy one comes from free-carrier emission. Moreover, from the TDPL spectra of the sample annealed at 180 °C for 5 min, the full width at half maximum (FWHM) of localization state emission was nearly the same before which is 250 K and then decreased with increasing temperature. However, the FWHM was decreased significantly when temperature increased in the untreated sample. We conclude that the escape of localization states with increasing temperature contributes to this anomaly phenomenon. Our studies have significance on the application of QDs in electroluminescence devices and down-conversion light-emitting devices.

3.
Nanotechnology ; 29(9): 095201, 2018 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-29297469

RESUMO

Nanowire photodetectors, which have the advantages of fast response and high photoelectric conversion efficiency, can be widely applied in various industries. However, the rich surface states result in large dark current and can hinder the development of high-performance nanowire photodetectors. In this paper, the influence and mechanism of sulfur surface passivation on the dark current of a single GaAs nanowire photodetector have been studied. The dark current is significantly reduced by about 30 times after surface passivation. We confirm that the origin of the reduction of dark current is the decrease in the surface state density. As a result, a single GaAs nanowire photodetector with low dark current of 7.18 × 10-2 pA and high detectivity of 9.04 × 1012 cmHz0.5W-1 has been achieved. A simple and convenient way to realize high-performance GaAs-based photodetectors has been proposed.

4.
Am J Transl Res ; 9(11): 5169-5179, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29218114

RESUMO

Esophageal squamous cell carcinoma (ESCC) is widely regarded as one of the most lethal types of cancer around the world. The fact that early detection of ESCC could dramatically improve the treatment outcome of the patients has sparked considerable interest in searching for reliable and accurate diagnostic biomarkers. Recently, circular RNAs (circRNA) have emerged as a new type of non-coding RNAs with significant RNase resistance, wide abundance and remarkable internal diversity. There is also increasing evidence suggesting that circRNAs could be implicated in the pathogenesis of cancer and other diseases. In this study, we performed a comparative analysis of the global circRNA expression profiles in normal and malignant esophageal epithelial cell lines by a combination of RNA sequencing and bioinformatics analysis. We identified 813 significantly up-regulated and 445 down-regulated circRNA candidates, of which 32 were subsequently validated by quantitative real-time reverse transcription polymerase chain reaction analysis. The differentially expressed circRNAs were found to be associated with pathways involved in metabolism, cell apoptosis, proliferation and migration, which are commonly altered in cancer cells. Based on the obtained data, we constructed a circRNA-miRNA interaction network, in which circRNA9927-NBEAL1 represented the biggest node. Our study could lay the groundwork for further investigation concerning the pathological roles of circRNAs in ESCC.

5.
Sci Rep ; 7(1): 15124, 2017 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-29123167

RESUMO

With special quasirandom structure approach and cluster expansion method combined with first-principle calculations, we explore the structure and electronic properties of monolayer Mo1-xWxS2 alloy with disordered phase and ordered phase. The phase transition from ordered phase to disordered phase is found to happen at 41 K and 43 K for x = 1/3 and x = 2/3, respectively. The band edge of VBM is just related with the composition x, while the band edge of CBM is sensitive to the degree of order, besides the concentration of W. Near the CBM band edge, there are two bands with the Mo-character and W-character, respectively. It is found that in disordered phase the Mo-character band is mixed with the W-character band, while the opposite happens in ordered phase. This result leads to that the splitting of two bands near CBM in ordered phase is larger than in disordered phase and gives rise to the smaller band gap in ordered phase compared to the disordered phase. The electron effective mass in ordered phase is smaller than in disordered phase, while the heavy hole effective mass in ordered phase is larger than that in disordered phase.

6.
Cancer Biomark ; 21(1): 203-210, 2017 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-29081413

RESUMO

OBJECTIVE: Glioma-associated oncogene homolog 1 (Gli1) in Hedgehog signal pathway regulates Cyclin D1 expression, cell cycle or proliferation modulation. Esophageal cancer patients had significantly elevated Gli1 expression, which is related with survival and prognosis. It has been demonstrated that the level of miR-150 was decreased in esophageal cancer patients compared to normal control. As a complementary relationship exists between miR-150 and 3'-UTR of Gli1, this study investigated if miR-150 played a role in regulating Gli1 expression, and proliferation or cell cycle of esophageal cancer cells. PATIENTS AND METHODS: Esophageal squamous cell carcinoma (ESCC) patients from our hospital were recruited to collect tumor and adjacent tissues for miR-150 and Gli1 expression. Esophageal carcinoma cell line EC9706 and normal esophageal epithelial cell line HEEC were compared for expression of miR-150, Gli1 and Cyclin D1. Dual luciferase reporter gene assay examined the targeted relationship between miR-150 and 3'-UTR of Gli1. In vitro cultured EC9706 cells were treated with miR-150 mimic, si-Gli1 or the combination of miR-150 mimic and si-Gli1, respectively, to check their gene expression, cell cycle and proliferation. RESULTS: ESCC tissues had significantly higher Gli1 expression and lower miR-150 expression. EC9706 cell also had higher Gli1 expression than that in HEEC, whilst miR-150 was down-regulated. Via targeting 3'-UTR of Gli1 gene, miR-150 inhibited its expression. Transfection of miR-150 mimic, si-Gli1 or the combination of miR-150 mimic and si-Gli1, respectively, remarkably decreased expression of Gli1 and Cyclin D1 expression in EC9706 cells, whose cell cycle arresting at G0/G1 phase was enhanced with weakened proliferation. CONCLUSIONS: MiR-150 can induce G0/G1 cell cycle arresting and weaken proliferation of esophageal carcinoma cells via targeted inhibition on Gli1 and downstream expression of Cyclin D1.


Assuntos
Carcinoma de Células Escamosas/genética , Pontos de Checagem do Ciclo Celular/genética , Proliferação de Células/genética , Neoplasias Esofágicas/genética , MicroRNAs/genética , Proteína GLI1 em Dedos de Zinco/genética , Regiões 3' não Traduzidas/genética , Adulto , Idoso , Sequência de Bases , Carcinoma de Células Escamosas/patologia , Linhagem Celular , Linhagem Celular Tumoral , Neoplasias Esofágicas/patologia , Feminino , Regulação Neoplásica da Expressão Gênica , Células HEK293 , Humanos , Masculino , Pessoa de Meia-Idade , Homologia de Sequência do Ácido Nucleico
7.
Sci Rep ; 6: 29112, 2016 07 06.
Artigo em Inglês | MEDLINE | ID: mdl-27381641

RESUMO

We report the carrier dynamics in GaAsSb ternary alloy grown by molecular beam epitaxy through comprehensive spectroscopic characterization over a wide temperature range. A detailed analysis of the experimental data reveals a complex carrier relaxation process involving both localized and delocalized states. At low temperature, the localized degree shows linear relationship with the increase of Sb component. The existence of localized states is also confirmed by the temperature dependence of peak position and band width of the emission. At temperature higher than 60 K, emissions related to localized states are quenched while the band to band transition dominates the whole spectrum. This study indicates that the localized states are related to the Sb component in the GaAsSb alloy, while it leads to the poor crystal quality of the material, and the application of GaAsSb alloy would be limited by this deterioration.


Assuntos
Ligas/química , Teste de Materiais/métodos , Análise Espectral , Temperatura Ambiente
8.
Sci Rep ; 6: 21135, 2016 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-26887923

RESUMO

Rhombohedral phase CuGaO2 nanoplates with a diameter of about 10 µm were synthesized via low temperature hydrothermal method. Room temperature and low temperature photoluminescence of the obtained CuGaO2 nanoplates were characterized. CuGaO2 nanoplates exhibited blue emission at room temperature and free exciton emission were appeared at low temperature. The blue emission is originated from defects such as Cu vacancies, which is the possible origin of p-type conductivity. The appearance of free exciton emission can demonstrate the direct bandgap transition behavior of CuGaO2 nanoplates. The as-prepared p-type CuGaO2 nanoplates were further decorated by n-type ZnO nanoparticles via calcination method to fabricate p-n junction nanocomposites. The nanocomposites exhibited enhanced photocatalytic activity which can be ascribed to the effective separation of photogenerated carriers by the internal electrostatic field in the p-n junction region, and the enhanced light absorption properties resulted from sub-bandgap absorption effect of p-n junction. This work has offered a new insight into the design of p-n junction devices using p-type CuGaO2 nanoplates.

9.
ACS Appl Mater Interfaces ; 8(3): 1661-6, 2016 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-26710654

RESUMO

We investigate the electroluminescence (EL) from light emitting diodes (LEDs) of ZnO nanowires/p-GaN structure and ZnS@ZnO core-shell nanowires/p-GaN structure. With the increase of forward bias, the emission peak of ZnO nanowires/p-GaN structure heterojunction shows a blue-shift, while the ZnS@ZnO core-shell nanowires/p-GaN structure demonstrates a changing EL emission; the ultraviolet (UV) emission at 378 nm can be observed. This discrepancy is related to the localized states introduced by ZnS particles, which results in a different carrier recombination process near the interfaces of the heterojunction. The localized states capture the carriers in ZnO nanowires and convert them to localized excitons under high forward bias. A strong UV emission due to localized excitons can be observed. Our results indicated that utilizing localized excitons should be a new route toward ZnO-based ultraviolet LEDs with high efficiency.

10.
Guang Pu Xue Yu Guang Pu Fen Xi ; 33(1): 220-3, 2013 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-23586260

RESUMO

For determination of elements in the leaves of Prunus mongolica, the samples were digested by nitric acid-perchloric. The contents of Ca, Mg, Fe, Mn, Cu, Zn, Al, Sr, Sn and Pb in the leaves of Prunus mongolica were determined by ICP-AES, at the same time a blank experiment was carried out. The results showed that the recovery rate of the ten elements was between 93% and 110%, and the relative standard deviation was between 0.33% and 2.94%. This method is fast, simple and accurate.


Assuntos
Minerais/análise , Folhas de Planta/química , Prunus/química , Espectrofotometria Atômica/métodos , Cálcio/análise , Ferro/análise , Magnésio/análise
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA