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1.
Nat Commun ; 11(1): 101, 2020 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-31900395

RESUMO

Sensitive photodetection is crucial for modern optoelectronic technology. Two-dimensional molybdenum disulfide (MoS2) with unique crystal structure, and extraordinary electrical and optical properties is a promising candidate for ultrasensitive photodetection. Previously reported methods to improve the performance of MoS2 photodetectors have focused on complex hybrid systems in which leakage paths and dark currents inevitably increase, thereby reducing the photodetectivity. Here, we report an ultrasensitive negative capacitance (NC) MoS2 phototransistor with a layer of ferroelectric hafnium zirconium oxide film in the gate dielectric stack. The prototype photodetectors demonstrate a hysteresis-free ultra-steep subthreshold slope of 17.64 mV/dec and ultrahigh photodetectivity of 4.75 × 1014 cm Hz1/2 W-1 at room temperature. The enhanced performance benefits from the combined action of the strong photogating effect induced by ferroelectric local electrostatic field and the voltage amplification based on ferroelectric NC effect. These results address the key challenges for MoS2 photodetectors and offer inspiration for the development of other optoelectronic devices.

2.
Intervirology ; 54(5): 268-75, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21242657

RESUMO

AIMS: To evaluate the stability of coxsackievirus B (CVB) genome integrated with the enhanced green fluorescent protein gene (egfp) and provide valuable information for the use of the recombinant CVB variant. METHODS: A CVB3 variant expressing eGFP was constructed by insertion of the egfp open-reading frame (ORF) at the 5' end of CVB3 ORF. The recombinant virus CVB3-eGFP was serially passaged in HeLa cells. The deletions in the CVB3-eGFP genome around egfp were examined by reverse transcription polymerase chain reaction and sequencing. RESULTS: Genomic deletions of CVB3-eGFP could be observed as early as the 2nd passage. Sequencing showed that the genomic deletions caused either viral ORF shifts or partial deletions of the viral VP4 coding sequence. The 6th passage of CVB3-eGFP was checked by plaque assay for eGFP expression. All plaque-like foci showed eGFP expression. eGFP expression was also viewed in HeLa cells infected with plaque-forming viruses. CONCLUSIONS: The insertion of egfp destabilized the CVB3 genome. The genomic deletions led to lethal mutations because of the termination of viral protein synthesis due to viral ORF shift and loss of partial viral gene. These findings imply that experimental data based on CVB integrated with the reporter gene should be interpreted with caution.


Assuntos
Enterovirus Humano B/genética , Genoma Viral , Instabilidade Genômica , Proteínas de Fluorescência Verde/genética , Recombinação Genética , Células HeLa , Humanos , Viabilidade Microbiana , RNA Viral/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Deleção de Sequência , Inoculações Seriadas
3.
Scand J Gastroenterol ; 44(11): 1332-9, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19891584

RESUMO

OBJECTIVE. miR-122 is highly abundant in liver and a hepato-specific microRNA. There is evidence to show that miR-122 expression is down-regulated in human hepatocellular carcinoma (HCC). It is not known whether miR-122 affects the cellular behavior of hepatoma cells. The aim of this study was to investigate the effects of miR-122 on the viability and apoptosis of hepatoma cells. MATERIAL AND METHODS. The viability and apoptosis of Huh-7 and HepG2 cells treated with miR-122 or miR-122 antisense RNA (anti-miR-122) were analyzed by adenosine triphosphate (ATP)-based luminescent assay, annexin V-based flow cytometry, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) detection. The miR-122 coding genes in both cell lines were sequenced. RESULTS. Although two putative promoter sequences for the miR-122 gene at 18q21.31 were detected, the miR-122 coding sequence was missing in HepG2 cells, which might be the reason for the absence of miR-122 expression. There was no significant difference between the viabilities of HepG2 cells transfected with miR-122 and mock HepG2 cells (p >0.05). However, the viability of Huh-7 transfected with anti-miR-122 was significantly elevated at 24, 36, and 48 h posttransfection compared with that of mock cells (p <0.01). Both the flow cytometry and TUNEL assay showed that the apoptotic level of Huh-7 transfected with anti-miR-122 was significantly decreased at 48 h posttransfection (p <0.01). CONCLUSIONS. miR-122 down-regulated the viability but up-regulated the apoptosis of hepatoma cell Huh-7. The absence of miR-122 expression in HepG2 cells was due to the loss of the miR-122 coding sequence in chromosome 18. These results imply that aberrant expression of miR-122 may contribute to hepatocarcinogenesis.


Assuntos
Apoptose/genética , Carcinoma Hepatocelular/genética , Regulação Neoplásica da Expressão Gênica , Neoplasias Hepáticas/genética , MicroRNAs/genética , RNA Neoplásico/genética , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/patologia , Linhagem Celular Tumoral , Sobrevivência Celular/genética , Citometria de Fluxo , Humanos , Marcação In Situ das Extremidades Cortadas , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patologia , MicroRNAs/biossíntese , RNA Neoplásico/biossíntese , Reação em Cadeia da Polimerase Via Transcriptase Reversa
4.
Virus Res ; 135(2): 255-9, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-18514346

RESUMO

Two mutants of coxsackievirus B1 (CVB1), CVB1c and CVB1e, with mutations in the stem-loop H of 5'-UTR were generated by site-directed mutagenesis. The A at nt579 of CVB1c was substituted by G. The U at nt573 and A at nt579 of CVB1e were substituted by A and G. The virulences of these mutants had been assessed by means of cytopathic effect (CPE), plaque formation, one-step growth curve, and 50% lethal dose (LD50) assays. The pathogenesis of these mutants was evaluated by attacking suckling Balb/c mice. Plaque assay and one-step growth curve showed that the replication of CVB1c and CVB1e on HeLa cells was significantly faster than that of their prototype CVB1n. Data of CPE assay, LD50, and pathological examination showed that CVB1c and CVB1e were more virulent than CVB1n. These data showed that mutation at nt579 (A-->G) alone and mutations at nt579 (A-->G) and nt573 (U-->A) together within 5'-UTR caused significant augment of the virulence and pathogenesis of coxsackievirus B1, and suggested that nt573 and nt579 might be molecular determinants for the virulence of coxsackievirus B1.


Assuntos
Regiões 5' não Traduzidas/genética , Enterovirus Humano B/genética , Enterovirus Humano B/patogenicidade , Mutação , Regiões 5' não Traduzidas/química , Animais , Animais Lactentes , Sequência de Bases , Células HeLa , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Virulência
5.
Zhonghua Yu Fang Yi Xue Za Zhi ; 42(11): 831-5, 2008 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-19176145

RESUMO

OBJECTIVE: To develop and evaluate the efficiency of air purification and sterilization instrument based on nano-sized TiO(2) photocatalytic technique. METHODS: The nano-sized TiO(2) photocatalytic air purification and sterilization instrument was designed and a sample had been prepared. The sterilization efficiencies for E.coli and Klebsiella by the nano-sized TiO(2) photocatalytic instrument and ultraviolet (UV) were measured in closed labs. The on-site efficiency of the instrument was evaluated, too. RESULTS: The nano-sized TiO(2) photocatalytic air purification and sterilization instrument was composed of five units: rough filter, nano-sized TiO(2) photocatalytic unit, activated carbon fiber filter, negative ion generator, and programmed control unit. The E.coli killing rates by the nano-sized TiO(2) photocatalytic instrument were 76.0%, 81.8%, 77.5%, and 80.7% at 30, 60, 90, and 120 minutes, respectively. There was no significant difference between the E.coli killing rates of the instrument and UV (P > 0.05), except the 120 minutes timepoint. The Klebsiella killing rates by the instrument were 78.4%, 79.5%, 67.3%, and 58.5% at 30, 60, 90, and 120 minutes, respectively. The Klebsiella killing efficiencies of the instrument at 30 and 60 minutes were better than that of UV (P < 0.01). There was no significant difference between the Klebsiella killing efficiencies of the instrument and UV (P > 0.05). CONCLUSION: The air sterilization efficiency of the nano-sized TiO(2) photocatalytic instrument should be equivalent or better as compared with the UV. This instrument might be used for the air purification and sterilization of the public locations.


Assuntos
Poluição do Ar/prevenção & controle , Descontaminação/métodos , Desinfecção/métodos , Nanoestruturas , Fotoquímica , Titânio
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