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1.
Opt Express ; 24(11): 11387-95, 2016 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-27410067

RESUMO

In this study, high-performance InGaN-based green light-emitting diodes (LEDs) with a quaternary InAlGaN/GaN superlattice electron blocking layer (QSL-EBL) have been demonstrated. The band structural simulation was employed to investigate the electrostatic field and carriers distribution, show that the efficiency and droop behavior can be intensively improved by using a QSL-EBL in LEDs. The QSL-EBL structure can reduce the polarization-related electrostatic fields in the multiple quantum wells (MQWs), leading to a smoother band diagram and a more uniform carriers distribution among the quantum wells under forward bias. In comparison with green LEDs with conventional bulk-EBL structure, the light output power of LEDs with QSL-EBL was greatly enhanced by 53%. The efficiency droop shows only 30% at 100 A/cm2 comparing to its peak value, suggesting that the QSL-EBL LED is promising for future white lighting with high performance.

2.
Nanoscale Res Lett ; 9(1): 505, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25258616

RESUMO

The flip chip ultraviolet light-emitting diodes (FC UV-LEDs) with a wavelength of 365 nm are developed with the ex situ reactive plasma deposited (RPD) AlN nucleation layer on patterned sapphire substrate (PSS) by an atmospheric pressure metal-organic chemical vapor deposition (AP MOCVD). The ex situ RPD AlN nucleation layer can significantly reduce dislocation density and thus improve the crystal quality of the GaN epitaxial layers. Utilizing high-resolution X-ray diffraction, the full width at half maximum of the rocking curve shows that the crystalline quality of the epitaxial layer with the (RPD) AlN nucleation layer is better than that with the low-temperature GaN (LT-GaN) nucleation layer. The threading dislocation density (TDD) is estimated by transmission electron microscopy (TEM), which shows the reduction from 6.8 × 10(7) cm(-2) to 2.6 × 10(7) cm(-2). Furthermore, the light output power (LOP) of the LEDs with the RPD AlN nucleation layer has been improved up to 30 % at a forward current of 350 mA compared to that of the LEDs grown on PSS with conventional LT-GaN nucleation layer.

3.
Nanoscale Res Lett ; 9(1): 2417, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26088992

RESUMO

For the purpose of light extraction and efficiency enhancement, the nitride-based ultraviolet vertical-injection light-emitting diodes (UV-VLEDs) with non-insulation current blocking layer (n-CBL) and optimized textured surface were fabricated. The optical and electrical characteristics were investigated in this n-CBL UV-VLED. Furthermore, the efficiency of optimized structure was improved by 5 ~ 6 times compared to our reference.

4.
Lab Chip ; 10(15): 1993-6, 2010 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-20508876

RESUMO

This paper demonstrates the embellishment of existing microfluidic devices with integrated three dimensional (3D) micronanostructures via femtosecond laser micronanofabrication, which, for the first time, proves two-photon photopolymerization (TPP) to be a powerful technology for chip functionalization. As representative examples, microsieves with various pore shape and adjustable pore size were successfully fabricated inside a conventional glass-based microfluidic channel prepared by wet etching for microparticle separation. Moreover, a fish scale like microfilter was also fabricated and appointed as a one-way valve, which showed excellent performance as we expected. These results indicate that such embellishment of microfluidic devices is simple, low cost, flexible and easy to access. We believe that, combined with TPP, the application of lab-on-chip devices would be further extended.


Assuntos
Dispositivos Lab-On-A-Chip , Lasers , Técnicas Analíticas Microfluídicas/métodos , Processos Fotoquímicos , Técnicas Analíticas Microfluídicas/instrumentação
5.
J Sep Sci ; 28(3): 225-33, 2005 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-15776923

RESUMO

Inexpensive and permanently modified poly(methyl methacrylate)(PMMA) microchips were fabricated by an injection-molding process. A novel sealing method for plastic microchips at room temperature was introduced. Run-to-run and chip-to-chip reproducibility was good, with relative standard deviation values between 1-3% for the run-to-run and less than 2.1% for the chip-to-chip comparisons. Acrylonitrile-butadiene-styrene (ABS) was used as an additive in PMMA substrates. The proportions of PMMA and ABS were optimized. ABS may be considered as a modifier, which obviously improved some characteristics of the microchip, such as the hydrophilicity and the electro-osmotic flow (EOF). The detection limit of Rhodamine 6G dye for the modified microchip on the home-made microchip analyzer showed a dramatic 100-fold improvement over that for the unmodified PMMA chip. A detection limit of the order of 10(-20) mole has been achieved for each injected psiX-174/HaeIII DNA fragment with the baseline separation between 271 and 281 bp, and fast separation of 11 DNA restriction fragments within 180 seconds. Analysis of a PCR product from the tobacco ACT gene was performed on the modified microchip as an application example.


Assuntos
DNA/análise , Análise de Sequência com Séries de Oligonucleotídeos/instrumentação , Polimetil Metacrilato/química , Microscopia Eletrônica de Varredura , Reação em Cadeia da Polimerase , Reprodutibilidade dos Testes , Rodaminas
6.
J Chromatogr B Analyt Technol Biomed Life Sci ; 816(1-2): 145-51, 2005 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-15664344

RESUMO

The p16 tumor suppressor gene is inactivated by promoter region hypermethylation in many types of tumor. Recent studies showed that aberrant methylation of the p16 gene is an early event in many tumors, especially in lung cancer, and may constitute a new biomarker for early detection and monitoring of prevention trials. We detected tumor-associated aberrant hypermethylation of the p16 gene in plasma and tissue DNA from 153 specimens using a modified semi-nested methylation-specific PCR (MSP) combining plastic microchip electrophoresis or slab gel electrophoresis, respectively. Specimens were from 79 lung cancer patients, 15 abdominal tumor patients, 30 positive controls and 30 negative controls. The results showed that the positive rate obtained by microchip electrophoresis was more than 26.6% higher and the same specificity was kept when compared with slab gel electrophoresis. The microchip electrophoresis can rapidly and accurately analyze the PCR products of methylated DNA and obviously improve the positive rate of diagnosis of cancer patients when compared with gel electrophoresis. This method with the high assay sensitivity might be used for detection of methylation of p16 gene and even to facilitate early diagnosis of cancer patients.


Assuntos
Metilação de DNA , Eletroforese em Microchip/métodos , Genes p16 , Neoplasias/genética , Neoplasias Abdominais/sangue , Neoplasias Abdominais/genética , Eletroforese em Microchip/instrumentação , Estudos de Viabilidade , Humanos , Neoplasias Pulmonares/sangue , Neoplasias Pulmonares/genética , Polimetil Metacrilato , Sensibilidade e Especificidade
7.
Se Pu ; 20(2): 125-8, 2002 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-12541967

RESUMO

Domoic acid, a main component of amnesic shellfish toxin (one of the four sorts of marine red tide bio-toxins) was determined by capillary electrophoresis with UV detection. The shellfish samples were prepared by solvent extraction, cleaned-up with a strong anion-exchange cartridge (SAX: Part No. 1210-2044, Lot No. 182639, Varian) and a cation-exchange cartridge (SCX: Part No. 1211-3039, Lot No. 171069, Varian). The quantitative analysis was performed with external standard under the optimum conditions of capillary electrophoretic analysis. The calibration curve of domoic acid showed good linearity in the range of 0.2 mg/L-50 mg/L with r = 0.9990, and the detection limit was 0.063 mg/L(S/N > 3). Spiked with standard at three levels (5.00 micrograms/g, 10.00 micrograms/g and 20 micrograms/g), the samples had the recoveries of 97.24%, 96.92% and 97.55%, and the RSDs of 2.74%, 2.59% and 1.95%, respectively. Five kinds of shellfish samples normally consumed in Dalian sea area were collected and quantified. The method has the advantages of being simple, convenient, sensitive and low cost. Therefore it can be used as one of the routine monitoring methods for amnesic shellfish toxin.


Assuntos
Contaminação de Alimentos/análise , Ácido Caínico/análogos & derivados , Ácido Caínico/análise , Neurotoxinas/análise , Frutos do Mar/análise , Animais , Eletroforese Capilar , Toxinas Marinhas/análise
8.
Se Pu ; 20(2): 156-8, 2002 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-12541975

RESUMO

UV labeling detection has been commonly used to determine the association constants between lectins and saccharides, but the interaction is always between the labeled carbohydrates, rather than the truly underivatized carbohydrates, and lectins. In order to directly detect saccharides during the study on the interaction of glucose and its derivatives with lectins (e.g., concanavalin A), a capillary zone electrophoretic method with detection at a wavelength of 195 nm has been developed. The influences of various separation conditions including buffer concentration, pH and voltage were investigated. By using an uncoated silica capillary (50 microns i.d., 375 microns o.d., 48.5 cm of total length, and 44.0 cm to the detector) and 50 mmol/L Na2HPO(4)-50 mmol/L NaH2PO4 solution (near to the physiological pH of 7.4) as buffer, the underivatized sugars, including glucosamine, N-acetylglucosamine, glucose, and sodium gluconate, were sufficiently separated within 11 min at an applied voltage of 10 kV. On-column UV monitoring allowed the detection of these compounds at less than 4 mmol/L level, and quantification by the peak area method allowed reproducible determination of them at least at their respective concentration ranges. The method is characterized by its simplicity, rapidity, and reproducibility, and should be useful for the analysis of the interaction of glucose and its derivatives with lectins.


Assuntos
Eletroforese Capilar/métodos , Glucose/análise , Lectinas/análise , Concanavalina A/análise , Concanavalina A/isolamento & purificação , Gluconatos/análise , Gluconatos/isolamento & purificação , Glucose/análogos & derivados , Glucose/isolamento & purificação , Lectinas/isolamento & purificação , Espectrofotometria Ultravioleta
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