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1.
Nanomaterials (Basel) ; 14(11)2024 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-38869611

RESUMO

Ferroelectric, phase-change, and magnetic materials are considered promising candidates for advanced memory devices. Under the development dilemma of traditional silicon-based memory devices, ferroelectric materials stand out due to their unique polarization properties and diverse manufacturing techniques. On the occasion of the 100th anniversary of the birth of ferroelectricity, scandium-doped aluminum nitride, which is a different wurtzite structure, was reported to be ferroelectric with a larger coercive, remanent polarization, curie temperature, and a more stable ferroelectric phase. The inherent advantages have attracted widespread attention, promising better performance when used as data storage materials and better meeting the needs of the development of the information age. In this paper, we start from the characteristics and development history of ferroelectric materials, mainly focusing on the characteristics, preparation, and applications in memory devices of ferroelectric wurtzite AlScN. It compares and analyzes the unique advantages of AlScN-based memory devices, aiming to lay a theoretical foundation for the development of advanced memory devices in the future.

2.
Front Cell Infect Microbiol ; 13: 1196084, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37621875

RESUMO

Purpose: To determine the role of Lactobacillus strains and their combinations in inhibiting the colonization of H. pylori and gastric mucosa inflammation. Methods: Human gastric adenocarcinoma AGS cells were incubated with H. pylori and six probiotic strains (Lactobacillus acidophilus NCFM, L. acidophilus La-14, Lactiplantibacillus plantarum Lp-115, Lacticaseibacillus paracasei Lpc-37, Lacticaseibacillus rhamnosus Lr-32, and L. rhamnosus GG) and the adhesion ability of H. pylori in different combinations was evaluated by fluorescence microscopy and urease activity assay. Male C57BL/6 mice were randomly divided into five groups (uninfected, H. pylori, H. pylori+NCFM, H. pylori+Lp-115, and H. pylori+NCFM+Lp-115) and treated with two lactobacilli strains (NCFM and Lp-115) for six weeks. H. pylori colonization and tissue inflammation statuses were determined by rapid urease test, Hematoxylin-Eosin (HE) staining, immunohistochemistry, and qRT-PCR and ELISA. Results: L. acidophilus NCFM, L. acidophilus La-14, L. plantarum Lp-115, L. paracasei Lpc-37, L. rhamnosus Lr-32, and L. rhamnosus GG reduced H. pylori adhesion and inflammation caused by H. pylori infection in AGS cells and mice. Among all probiotics L. acidophilus NCFM and L. plantarum, Lp-115 showed significant effects on the H. pylori eradication and reduction of inflammation in-vitro and in-vivo. Compared with the H. pylori infection group, the mRNA and protein expression levels of IL-8 and TNF-α in the six Lactobacillus intervention groups were significantly reduced. The changes in the urease activity (ureA and ureB) for 1-7h in each group showed that L. acidophilus NCFM, L. acidophilus La-14, L. plantarum Lp-115, and L. rhamnosus GG effectively reduced the colonization of H. pylori. We observed a higher ratio of lymphocyte and plasma cell infiltration into the lamina propria of the gastric mucosa and neutrophil infiltration in H. pylori+NCFM+Lp-115 mice. The infiltration of inflammatory cells in lamina propria of the gastric mucosa was reduced in the H. pylori+NCFM+Lp-115 group. Additionally, the expression of IFN-γ was decreased significantly in the NCFM and Lp-115 treated C57BL/6 mice. Conclusions: L. acidophilus NCFM and L. plantarum Lp-115 can reduce the adhesion of H. pylori and inhibit the gastric inflammatory response caused by H. pylori infection.


Assuntos
Gastrite , Helicobacter pylori , Humanos , Masculino , Animais , Camundongos , Camundongos Endogâmicos C57BL , Lactobacillus acidophilus , Urease , Modelos Animais de Doenças , Gastrite/prevenção & controle , Inflamação , Lactobacillus
3.
J Immunol ; 208(6): 1483-1492, 2022 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-35246494

RESUMO

Therapies targeting programmed cell death protein 1 (PD-1) have gained great success in patients with multiple types of cancer. The regulatory mechanisms underlying PD-1 expression have been extensively explored. However, the impact of long noncoding RNAs on PD-1 expression remains elusive. In this study, we identified the Notch1/lncNDEPD1 axis, which plays a critical role in PD-1 expression in human CD8+ T cells. RNA sequencing and quantitative reverse transcription PCR data showed that lncNDEPD1 was upregulated in activated T cells, especially in PD-1high subsets. Fluorescence in situ hybridization demonstrated that lncNDEPD1 was localized in the cytoplasm. A mechanistic study showed that lncNDEPD1 could bind with miR-3619-5p and PDCD1 mRNA to prevent PDCD1 mRNA degradation and then upregulate PD-1 expression. A chromatin immunoprecipitation assay showed that Notch1 directly binds to the promoter of lncNDEPD1 instead of PDCD1 Furthermore, chimeric Ag receptor T cells expressing lncNDEPD1-specific short hairpin RNAs were generated. Chimeric Ag receptor T cells with decreased lncNDEPD1 expression showed enhanced tumoricidal effects when PD-L1 was present. Our work uncovered a new regulatory mechanism of PD-1 expression and thus provided a potential target to decrease PD-1 without affecting T cell function.


Assuntos
MicroRNAs , RNA Longo não Codificante , Antígeno B7-H1/genética , Antígeno B7-H1/metabolismo , Linfócitos T CD8-Positivos/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/genética , Regulação Neoplásica da Expressão Gênica , Humanos , Hibridização in Situ Fluorescente , MicroRNAs/genética , MicroRNAs/metabolismo , Receptor de Morte Celular Programada 1/genética , Receptor de Morte Celular Programada 1/metabolismo , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismo
4.
Mater Sci Eng C Mater Biol Appl ; 120: 111771, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33545903

RESUMO

With the development and progress of science and technology, magnesium and magnesium alloys have attracted more and more researchers' attention because of their excellent biocompatibility. However, rapid degradation rate of magnesium alloy in vivo seriously limits its application (Arthanari et al., n.d.; Cui et al., 2013 [1,2]). In order to solve this problem, the surface modification of Mg-4.0Zn-0.8Sr alloy was adopted in this paper. According to the requirements of orthopedic materials, anodizing coating (AO), silane coating (SA) and chitosan coating (CS) coating were prepared on its surface, and magnesium alloy was prepared into intramedullary nail, and the corrosion resistance and biocompatibility of the corresponding samples was evaluated. The experimental results show that the AO-SA-CS coating sample has higher corrosion resistance, in addition, it also shows good biocompatibility, such as lower hemolysis rate and normal platelet adhesion morphology. After implantation into the femur, the femur of rats recovered well and the kidney tissue was normal.


Assuntos
Líquidos Corporais , Quitosana , Ligas , Animais , Materiais Revestidos Biocompatíveis/farmacologia , Corrosão , Teste de Materiais , Ratos , Silanos
5.
Artigo em Inglês | MEDLINE | ID: mdl-31671714

RESUMO

The Poyang Lake Watershed (PLW) is regarded as an air temperature moderator, as well as a wind energy, food resources and good habitat in the Jiangxi Province, People's Republic of China. However, with the increasing of anthropogenic disturbance on PLW, there are few studies focused on the effects of human activities on microbial composition in Poyang Lake. In the present study, a high-throughput sequencing method was used to identify the microbial composition in water and sludge in Dahuchi (DHC, sub-lake of Poyang Lake National Nature Reserve), Shahu (SH, sub-lake of Poyang Lake National Nature Reserve), Nanhu (NH, sub-lake out of Poyang Lake National Nature Reserve), Zhelinhu (ZLH, artificial reservoir), Sixiahu (SXH, sub-lake artificially isolated from Poyang Lake) and Qianhu (QH, urban lake). Results of the present study illustrated the various bacterial diversity between different lakes, for example, at the phylum level, Actinobacteria and Cyanobacteria showed low abundance in water samples of ZLH and QH, and high abundance in DHC. In addition, anthropogenic disturbance and human activities decreased the abundance of probiotic bacteria (Actinobacteria, Cyanobacteria, Chloroflexi and Acidobacteria) and increased the abundance of pathogenic bacteria (Acinetobacter, Aeromonas and Noviherbaspirillum). The enrichment of pathogenic bacteria in polluted lakes, in turn, may cause potential threats to human health.


Assuntos
Bactérias/isolamento & purificação , Lagos/microbiologia , Bactérias/classificação , China , Ensaios de Triagem em Larga Escala , Humanos , Vento
6.
Chem Commun (Camb) ; 55(81): 12188-12191, 2019 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-31544184

RESUMO

A YAG: Ce/MgY4Si3O13:Ce-Y2O3:Eu core-shell structure was designed and accomplished via a urea homogeneous precipitation method. The as prepared phosphors can emit photons with a broad range of wavelengths from 340 nm to 700 nm under excitation light of 330 nm. The internal quantum efficiency can reach up to 68%.

7.
Environ Sci Pollut Res Int ; 25(34): 34583-34594, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30315531

RESUMO

Plant roots in lakeshore areas can directly determine the survival of the aboveground plant parts. However, most current studies are focused on the aerial shoots, and less attention has been paid to the functions of the roots. In order to evaluate the effects of water level fluctuations (WLFs) on root architectural and morphological traits of plants in lakeshore areas, field investigations were conducted seasonally in three subtropical floodplain lakes with different types of WLFs. The results showed that both the pH and moisture contents of the soils were significantly different in all seasons among the three lakes, while the total nitrogen and total phosphorus in the soils only showed significant differences in certain seasons. Significant differences were also found in the two architectural trait parameters (root length density and root branching number) and three morphological trait parameters (root tissue density, root surface area, and root volume), all of which (except for root tissue density) were highest in the Dahuchi lake that experiences intermittent WLFs, and lowest in the Chaohu Lake with reservoir-like WLFs. With increasing lakeshore elevation gradients, we found that root length density, root branching number, root surface area, and root volume in the three lakes changed significantly, and all these root trait parameters increased first and then decreased. However, no significant differences were found for the above four root traits in the three lakes over the different seasons. Spearman correlation analyses indicated that both the hydrological and physicochemical factors were strongly correlated with the architectural and morphological root trait parameters, and the duration of submergence (duration) was the most important factor, judging from the correlation coefficients (R). The results of stepwise multiple regression further indicated the duration was the key factor affecting plant root traits. Based on the results of this study, we suggest that the WLFs in reservoir-like lakes should be changed in order to improve the ecological functions of the lakeshore.


Assuntos
Lagos , Raízes de Plantas/fisiologia , Solo/química , China , Hidrologia/métodos , Nitrogênio/análise , Fenótipo , Fósforo/análise , Estações do Ano
8.
PLoS One ; 13(5): e0197510, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29813094

RESUMO

Accurate estimation of the fraction of absorbed photosynthetically active radiation (fPAR) for maize canopies are important for maize growth monitoring and yield estimation. The goal of this study is to explore the potential of using airborne LiDAR and hyperspectral data to better estimate maize fPAR. This study focuses on estimating maize fPAR from (1) height and coverage metrics derived from airborne LiDAR point cloud data; (2) vegetation indices derived from hyperspectral imagery; and (3) a combination of these metrics. Pearson correlation analyses were conducted to evaluate the relationships among LiDAR metrics, hyperspectral metrics, and field-measured fPAR values. Then, multiple linear regression (MLR) models were developed using these metrics. Results showed that (1) LiDAR height and coverage metrics provided good explanatory power (i.e., R2 = 0.81); (2) hyperspectral vegetation indices provided moderate interpretability (i.e., R2 = 0.50); and (3) the combination of LiDAR metrics and hyperspectral metrics improved the LiDAR model (i.e., R2 = 0.88). These results indicate that LiDAR model seems to offer a reliable method for estimating maize fPAR at a high spatial resolution and it can be used for farmland management. Combining LiDAR and hyperspectral metrics led to better performance of maize fPAR estimation than LiDAR or hyperspectral metrics alone, which means that maize fPAR retrieval can benefit from the complementary nature of LiDAR-detected canopy structure characteristics and hyperspectral-captured vegetation spectral information.


Assuntos
Tecnologia de Sensoriamento Remoto/métodos , Zea mays/crescimento & desenvolvimento , Zea mays/efeitos da radiação , Biomassa , China , Lasers , Modelos Lineares , Fotossíntese , Tecnologia de Sensoriamento Remoto/estatística & dados numéricos , Luz Solar , Zea mays/metabolismo
9.
Materials (Basel) ; 11(3)2018 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-29498689

RESUMO

Smart garments, which can capture electrocardiogram signals at any time or location, can alert others to the risk of heart attacks and prevent sudden cardiac death when people are sleeping, walking, or running. Novel wearable electrodes for smart garments based on conductive chitosan fabrics were fabricated by electroless plating of silver nanoparticles onto the surfaces of the fibers. The electrical resistance, which is related to the silver content of the composite fabrics, can be as low as 0.0332 ± 0.0041 Ω/sq due to the strong reactivity between amine groups and silver ions. After washing these fabrics eight times, the electrical resistance remained below 1 Ω/sq. The conductive chitosan fabrics were applied to smart garments as wearable electrodes to capture electrocardiogram signals of the human body in static state, jogging state, and running state, which showed good data acquisition ability and sensitivity.

10.
Opt Express ; 25(16): A851-A869, 2017 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-29041100

RESUMO

Forest aboveground biomass (AGB) is critical for assessing forest productivity and evaluating carbon sequestration rates. Discrete-return LiDAR has been widely used to estimate forest AGB, however, fewer studies have estimated the coniferous forest AGB using airborne small-footprint full-waveform LiDAR data. The objective of this study was to extract a suite of newly proposed metrics from airborne small-footprint full-waveform LiDAR data and to evaluate the ability of these metrics in estimating coniferous forest AGB. To achieve this goal, each waveform was first preprocessed, including de-noising, smoothing, and normalization. Next, all the waveforms within each plot were aggregated into a large pseudo waveform and the return energy profile was generated. Then, the foliage profile was retrieved from the return energy profile based on the Geometric Optical and Radiative Transfer (GORT) model. Finally, a series of new return energy profile metrics and foliage profile metrics were extracted to estimate forest AGB. Simple linear regression was conducted to assess the correlation between each LiDAR metric and forest AGB. Stepwise multiple regression analysis was then carried out to select important prediction metrics and establish the optimal forest AGB estimation model. Results indicated that both return energy profile and foliage profile based height-related metrics were strongly correlated to forest AGB. The energy weighted canopy height (HEweight) (R = 0.88) and foliage area weighted height (HFweight) (R = 0.89) all had the highest correlation coefficients with forest AGB in return energy profile metrics and foliage profile metrics respectively. Energy height percentiles and foliage height percentiles also had the ability to explain AGB variation. The energy-related metrics, foliage area-related metrics, and bounding volume-related metrics derived from the return energy profile and foliage profile were not all sensitive to forest AGB. This study also concluded that combining return energy profile metrics and foliage profile metrics could improve the accuracy of forest AGB estimation, and the optimal model contained the metrics of HFweight, HEweight, and VolumemaxHE, which is the product of the maximum canopy return energy profile amplitude (maxCE) and the maximum height of return energy profile (maxHE).

12.
Sci Rep ; 6: 24096, 2016 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-27297030

RESUMO

Sub-gap density of states (DOS) is a key parameter to impact the electrical characteristics of semiconductor materials-based transistors in integrated circuits. Previously, spectroscopy methodologies for DOS extractions include the static methods, temperature dependent spectroscopy and photonic spectroscopy. However, they might involve lots of assumptions, calculations, temperature or optical impacts into the intrinsic distribution of DOS along the bandgap of the materials. A direct and simpler method is developed to extract the DOS distribution from amorphous oxide-based thin-film transistors (TFTs) based on Dual gate pulse spectroscopy (GPS), introducing less extrinsic factors such as temperature and laborious numerical mathematical analysis than conventional methods. From this direct measurement, the sub-gap DOS distribution shows a peak value on the band-gap edge and in the order of 10(17)-10(21)/(cm(3)·eV), which is consistent with the previous results. The results could be described with the model involving both Gaussian and exponential components. This tool is useful as a diagnostics for the electrical properties of oxide materials and this study will benefit their modeling and improvement of the electrical properties and thus broaden their applications.

13.
Mol Med Rep ; 14(2): 1255-62, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27277534

RESUMO

The expression and functions of microRNA (miR)-320 have been previously investigated in various types of cancer. However, to the best of our knowledge, no previous studies have investigated miR-320 in human lung cancer. The current study determined the expression, biological functions and molecular mechanisms of miR­320 in human lung cancer. The expression level of miR­320 in human non­small cell lung cancer (NSCLC) and normal adjacent tissue samples (NATs), NSCLC cell lines and non­tumorigenic bronchial epithelial cells was measured by reverse transcription­quantitative polymerase chain reaction. Following transfection with miR­320 mimics, 3­(4,5­dimethylthiazol­2­yl)­2,5­diphenyltetrazolium bromide, cell migration and cell invasion assays, western blot analysis and luciferase assay were performed in human NSCLC cell lines. The results demonstrated that miR­320 was significantly downregulated in NSCLC tissue samples and cell lines compared with NATs and a control cell line, respectively. Statistical analysis demonstrated that expression of miR­320 was significantly associated with the TNM classification and metastasis. It was also observed that miR­320 inhibited cell growth, migration and invasion in NSCLC cells. Additionally, the present study provided evidence that miR­320 may directly target fatty acid synthase. These results suggest that miR­320 may serve as a therapeutic biomarker of NSCLC in the future.


Assuntos
Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma Pulmonar de Células não Pequenas/patologia , Ácido Graxo Sintases/genética , Regulação Neoplásica da Expressão Gênica , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patologia , MicroRNAs/genética , Regiões 3' não Traduzidas , Adulto , Idoso , Sítios de Ligação , Linhagem Celular Tumoral , Movimento Celular/genética , Proliferação de Células , Regulação para Baixo , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Gradação de Tumores , Metástase Neoplásica , Estadiamento de Neoplasias , Interferência de RNA
14.
Inorg Chem ; 55(6): 3040-6, 2016 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-26925591

RESUMO

Gadolinium gallium aluminum garnet (GGAG) is a very promising host for the highly efficient luminescence of Ce(3+) and shows potential in radiation detection applications. However, the thermodynamically metastable structure would be slanted against it from getting high transparency. To stabilize the crystal structure of GGAG, Yb(3+) ions were codoped at the Gd(3+) site. It is found that the decomposition of garnet was suppressed and the transparency of GGAG ceramic was evidently improved. Moreover, the photoluminescence of GGAG:Ce(3+),xYb(3+) with different Yb(3+) contents has been investigated. When the Ce(3+) ions were excited under 475 nm, a typical near-infrared region emission of Yb(3+) ions can be observed, where silicon solar cells have the strongest absorption. Basing on the lifetimes of Ce(3+) ions in the GGAG:Ce(3+),xYb(3+) sample, the transfer efficiency from Ce(3+) to Yb(3+) and the theoretical internal quantum efficiency can be calculated and reach up to 86% and 186%, respectively. This would make GGAG:Ce(3+),Yb(3+) a potential attractive downconversion candidate for improving the energy conversion efficiency of crystalline silicon (c-Si) solar cells.

15.
PLoS One ; 10(8): e0135604, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26261984

RESUMO

Benthic bivalves are important links between primary production and consumers, and are essential intermediates in the flow of energy through estuarine systems. However, information on the diet of filter feeding bivalves in estuarine ecosystems is uncertain, as estuarine waters contain particulate matter from a range of sources and as bivalves are opportunistic feeders. We surveyed bivalves at different distances from the creek mouth at the Yangtze estuarine marsh in winter and summer, and analyzed trophic dynamics using stable isotope (SI) and fatty acid (FA) techniques. Different bivalve species had different spatial distributions in the estuary. Glauconome chinensis mainly occurred in marshes near the creek mouth, while Sinonovacula constricta preferred the creek. Differences were found in the diets of different species. S. constricta consumed more diatoms and bacteria than G. chinensis, while G. chinensis assimilated more macrophyte material. FA markers showed that plants contributed the most (38.86 ± 4.25%) to particular organic matter (POM) in summer, while diatoms contributed the most (12.68 ± 1.17%) during winter. Diatoms made the largest contribution to the diet of S. constricta in both summer (24.73 ± 0.44%) and winter (25.51 ± 0.59%), and plants contributed no more than 4%. This inconsistency indicates seasonal changes in food availability and the active feeding habits of the bivalve. Similar FA profiles for S. constricta indicated that the bivalve had a similar diet composition at different sites, while different δ13C results suggested the diet was derived from different carbon sources (C4 plant Spartina alterniflora and C3 plant Phragmites australis and Scirpus mariqueter) at different sites. Species-specific and temporal and/or spatial variability in bivalve feeding may affect their ecological functions in intertidal marshes, which should be considered in the study of food webs and material flows in estuarine ecosystems.


Assuntos
Bivalves , Ecossistema , Animais , Biodiversidade , China , Densidade Demográfica , Dinâmica Populacional , Estações do Ano , Áreas Alagadas
16.
Zhonghua Zhong Liu Za Zhi ; 37(11): 827-32, 2015 Nov.
Artigo em Chinês | MEDLINE | ID: mdl-26887512

RESUMO

OBJECTIVE: To study the expression and clinical significance of MTDH and VEGF in triple-negative breast cancer (TNBC). METHODS: Tissue samples of 168 breast cancers (including 112 TNBC tissue and 56 non-TNBC tissue), 10 breast fibroadenomas and 15 normal breast tissues were collected. Postoperative specimens were examined by immunohistochemistry for MTDH and VEGF expression. The correlation between the expression of MTDH and VEGF and clinicopathological features was analyzed. RESULTS: MTDH and VEGF were expressed in 57.1% and 49.4% of breast cancer patients, 64.3% and 56.3% in TNBC patients, respectively, significantly higher than that in the non-TNBC tissues, breast fibroadenomas and normal breast tissues (P<0.05 for all). Statistically significant correlation was found between the MTDH and VEGF expressions (r=0.356, P<0.001). Moreover, MTDH expression was correlated with tumor size, BMI index, lymph node metastasis, pathological stage, recurrence and metastasis, and the expression of p53 and Ki-67 proteins (P<0.05 for all). The VEGF protein expression was correlated with lymph node metastasis, pathological staging, recurrence and metastasis, and the expression of Ki-67 protein (P<0.05 for all). The patients with high expression of MTDH and VEGF showed a lower DFS and OS (P<0.05 for both). CONCLUSIONS: MTDH and VEGF expression may be correlated with tumor angiogenesis and progression and has the potential to be valuable prognostic factors in patients with TNBC.


Assuntos
Biomarcadores Tumorais/metabolismo , Moléculas de Adesão Celular/metabolismo , Fibroadenoma/metabolismo , Proteínas de Neoplasias/metabolismo , Neoplasias de Mama Triplo Negativas/metabolismo , Fator A de Crescimento do Endotélio Vascular/metabolismo , Mama/metabolismo , Intervalo Livre de Doença , Feminino , Fibroadenoma/irrigação sanguínea , Fibroadenoma/patologia , Humanos , Imuno-Histoquímica , Metástase Linfática , Proteínas de Membrana , Neovascularização Patológica , Prognóstico , Proteínas de Ligação a RNA , Neoplasias de Mama Triplo Negativas/irrigação sanguínea , Neoplasias de Mama Triplo Negativas/patologia
17.
Phys Chem Chem Phys ; 13(20): 9232-7, 2011 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-21461447

RESUMO

Two kinds of TiO(2) nanobelts were prepared from commercial P-25 powders via an alkaline hydrothermal method with and without an acid etching process. The uncauterized nanobelts (TNs) exhibited a smooth surface, and mixed phases of anatase and TiO(2) (B), whereas the cauterized ones (CTNs) displayed a rough surface and a pure anatase structure. TNs and CTNs were then deposited onto a glassy carbon electrode (GCE) surface with a conductive adhesive (CA), and the resulting chemically modified electrodes exhibited electrocatalytic activities in the oxidation of nucleobases in a 0.1 M phosphate buffer solution (PBS) at pH 7.4. For guanine and adenine, well-defined oxidation peaks were observed in voltammetric measurements at about +0.62 and +0.89 V, respectively, at a potential sweep rate of 100 mV s(-1), whereas for cytosine, uracil and thymine, the voltammetric features were not obvious. The average surface coverages (Γ) of guanine and adenine on the CTNs/CA/GCE electrode were estimated to be 4.75 × 10(-10) and 7.44 × 10(-10) mol cm(-2), respectively, which were about twice those at the TNs/CA/GCE electrode. The enhanced activity of the CTN-based electrode towards purine nucleobase oxidation was ascribed to the large specific surface area and anatase structures with enhanced (001) facets of the CTN that facilitated adsorption of the analytes onto the electrode surface and charge transport through the electrode surface layer.


Assuntos
Nanotubos/química , Nucleosídeos/química , Titânio/química , Adenina/química , Catálise , Citosina/química , Técnicas Eletroquímicas , Eletrodos , Guanina/química , Nanotubos/ultraestrutura , Oxirredução , Timina/química , Uracila/química
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