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1.
Clin Lab ; 67(7)2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34258977

RESUMO

BACKGROUND: Analytical performance should be evaluated before a new coagulation analyzer is adopted in a clinical laboratory. The objective of this study was to evaluate analytical performances of three new coagulation analyzers (STA-R Max3, CN-6000, and Cobas t511) and compare them based on the following four coagulation parameters: prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen, and D-dimer. METHODS: A total of 427 plasma samples, including fresh and frozen/thawed plasma spanning wide ranges. Each of the manufacturers' quality control samples were used for the evaluation. Analytical performances were evaluated. Parameters considered were precision, carryover, verification of analytical measurement range, auto-dilution, and reference range according to the CLSI guidelines (H57-A). The results of each parameter were compared between STA-R compact (currently in use) and three new analyzers using fresh plasma. The results were compared among three new analyzers using fresh and frozen/thawed plasma, and samples with interferences of hemolysis/icterus/ lipemia (H/I/L). RESULTS: Analytical performances were excellent for all analyzers within each manufacturer's target based on results of precision, carryover, linearity, and verifications of auto-dilution, and reference range. Results for four parameters (PT/aPTT/fibrinogen/D-dimer) with the three new analyzers using fresh samples were well-correlated with those of STA-R Compact except for D-dimer tests (Pearson's r: 0.84 to 1.00). Good correlations were observed between the new analyzers with the total samples (fresh and frozen/thawed samples) (Pearson's r, 0.86 to 0.97). However, weaker correlation and/or higher mean bias% were observed for aPTT and D-dimer with total samples and for four parameters with normal samples rather than abnormal samples across the three analyzers. Differences were more prominent with H/I/L samples, especially between STA-R Max3 and CN-6000 or Cobas t511 for PT, aPTT, and D-dimers. CONCLUSIONS: With excellent analytical performances, the three new coagulation analyzers demonstrated good correlations, although high variabilities were seen for aPTT and D-dimers. High variability in comparison analysis might be mainly attributed to differences in reference and reportable ranges of each parameter across the three different analyzers.


Assuntos
Coagulação Sanguínea , Laboratórios , Testes de Coagulação Sanguínea , Humanos , Tempo de Tromboplastina Parcial , Tempo de Protrombina
2.
Cancers (Basel) ; 12(11)2020 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-33143045

RESUMO

A complimentary biomarker test that can be used in combination with LDCT for lung cancer screening is highly desirable to improve the diagnostic capacity of LDCT and reduce the false-positive rates. Most importantly, the stage I lung cancer detection rate can be dramatically increased by the simultaneous use of a biomarker test with LDCT. The present study was conducted to evaluate 9G testTM Cancer/Lung's sensitivity and specificity in detecting Stage 0~IV lung cancer. The obtained results indicate that the 9G testTM Cancer/Lung can detect lung cancer with overall sensitivity and specificity of 75.0% (69.1~80.3) and 97.3% (95.0~98.8), respectively. The detection of stage I, stage II, stage III, and stage IV cancers with sensitivities of 77.5%, 78.1%, 67.4%, and 33.3%, respectively, at the specificity of 97.3% have never been reported before. The receiver operating characteristic curve analysis allowed us to determine the population-weighted AUC of 0.93 (95% CI, 0.91-0.95). These results indicate that the 9G testTM Cancer/Lung can be used in conjunction with LDCT to screen lung cancer. Furthermore, obtained results indicate that the use of 9G testTM Cancer/Lung with LDCT for lung cancer screening can increase stage I cancer detection, which is crucial to improve the currently low 5-year survival rates.

3.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 4302-4305, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018947

RESUMO

Micro Bio Processor version 1.5 (MBPv15) Development Kit is specially engineered to support various function-alities of implantable devices such as bio-signal sensing, neural stimulation, and dual-band wireless connectivity & charging. It provides a convenient way to evaluate the MBPv15 chip solution as a system component by a modular design of hardware and software. As a result, MBPv15 chip solution enables to develop wireless neural implants in a mm-scale form factor with ultra-low power consumption by achieving 1.6 mW for neural spike detection and 9.8 mW for neural stimulation, respectively.


Assuntos
Próteses e Implantes , Processamento de Sinais Assistido por Computador , Potenciais de Ação , Software
4.
Anticancer Res ; 39(12): 6723-6730, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31810937

RESUMO

BACKGROUND/AIM: Phosphoserine aminotransferase 1 (PSAT1) is an enzyme implicated in serine biosynthesis, and its overexpression has been linked to cancer cell proliferation. Therefore, targeting PSAT1 is considered to be an anticancer strategy. MATERIALS AND METHODS: The viability of non-small cell lung cancer (NSCLC) cells was measured by MTT assay. Protein and mRNA expression were determined by western blot and reverse transcription polymerase chain reaction, respectively. RESULTS: Glutamine-limiting conditions were generated through glutamine deprivation or CB-839 treatment, which induced PSAT1 expression in NSCLC cells. PSAT1 expression induced by glutamine-limiting conditions was regulated by activating transcription factor 4. Knock-down of PSAT1 enhanced the sensitivity of NSCLC cells to glutamine-limiting conditions. Interestingly, ionizing radiation induced PSAT1 expression, and knocking down PSAT1 increased cell sensitivity to ionizing radiation. CONCLUSION: Inhibiting PSAT1 might aid in the treatment of lung cancer, and PSAT1 may be a therapeutic target for lung cancer.


Assuntos
Carcinoma Pulmonar de Células não Pequenas/metabolismo , Glutamina/metabolismo , Neoplasias Pulmonares/metabolismo , Transaminases/metabolismo , Fator 4 Ativador da Transcrição/metabolismo , Benzenoacetamidas/farmacologia , Carcinoma Pulmonar de Células não Pequenas/patologia , Carcinoma Pulmonar de Células não Pequenas/radioterapia , Linhagem Celular Tumoral , Sobrevivência Celular , Técnicas de Introdução de Genes , Glutaminase/antagonistas & inibidores , Glutamina/antagonistas & inibidores , Humanos , Pulmão/metabolismo , Neoplasias Pulmonares/patologia , Neoplasias Pulmonares/radioterapia , RNA Mensageiro/metabolismo , Tolerância a Radiação , Tiadiazóis/farmacologia , Transaminases/genética
5.
Chem Commun (Camb) ; 55(73): 10984, 2019 09 10.
Artigo em Inglês | MEDLINE | ID: mdl-31475260

RESUMO

Correction for 'Quantification of CYFRA 21-1 and a CYFRA 21-1-anti-CYFRA 21-1 autoantibody immune complex for detection of early stage lung cancer' by Keum-Soo Song et al., Chem. Commun., 2019, 55, 10060-10063.

6.
Chem Commun (Camb) ; 55(68): 10060-10063, 2019 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-31328750
7.
Radiat Res ; 192(1): 23-27, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31021708

RESUMO

Epidemiologic studies using clinical indicators are limited in the assessment of the biological effects of low-dose ionizing radiation for medical purposes. We evaluated the biological effect of low-dose radiation by comparing translocation frequencies in patients with repeated computed tomography (CT) exposure and CT-naïve patients. The goal of this prospective case-control study was to determine whether repeated CT exposure is associated with increased frequency in chromosomal translocations. Two cohorts, comprised of case patients with a history of repeated CT exposure and age- and sex-matched CT-naïve control patients (n = 48 per cohort), were consecutively enrolled in this single-institution study. CT-radiation exposure was estimated using dose-length products, and translocation frequencies of peripheral blood lymphocytes were assessed using whole chromosome paints by fluorescence in situ hybridization (FISH). Comparison of translocation frequencies between cases and controls was performed using the Wilcoxon rank sum test (paired samples), and the relationship between cumulative radiation exposure and translocation frequency was assessed using a partial correlation analysis. Translocation frequencies were significantly different between cases and controls (P = 0.0003). The median translocation frequency was 7 [95% confidence interval (CI): 6, 8] for cases and 4 (95% CI: 3, 6) for controls. By using cumulative radiation exposure as the effect variable and translocation frequency as the response variable, we found a significant correlation between cumulative radiation exposure and translocation frequency (r = 0.6579, P < 0.0001). Chromosomal translocations were more frequent with repeated CT-exposed patients than in CT-naïve patients, and a positive dose-response relationship was present between cumulative radiation exposure and translocation frequency.


Assuntos
Exposição à Radiação/efeitos adversos , Tomografia Computadorizada por Raios X/efeitos adversos , Translocação Genética/efeitos da radiação , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de Tempo , Adulto Jovem
8.
Biopreserv Biobank ; 17(4): 319-325, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30888199

RESUMO

Precision medicine has received increased attention as an effective approach for the treatment of cancer patients. Because of challenges associated with the availability of archived tissue, liquid biopsies are often performed to detect cancer-specific mutations. One of the major advantages of the liquid biopsy is that the treatment can be monitored longitudinally, even after the tumor tissue is no longer available. In a clinical setting, one component of precision medicine is the detection of cancer-specific mutations using archived samples. In this study, we evaluated the epidermal growth factor receptor (EGFR) mutation status of samples of lung cancer patients stored before introduction of the plasma EGFR test at our institution. The aim of this study was to validate the utility of archived plasma samples for detection of the EGFR mutation in nonsmall cell lung cancer (NSCLC) patients. The Cobas® EGFR Mutation Test v2 was the first liquid biopsy test approved as a companion diagnostic test for patients with NSCLC treated with tyrosine kinase inhibitors. We tested for the EGFR mutation in 116 plasma samples archived in the biobank, and the results were compared with those obtained in the tissue or cytology EGFR mutation test. The EGFR mutation-positive rate from archived plasma was lower than that determined from tissue or cytology at 19.0% and 53.4%, respectively, and the concordance rate between the two tests was 58.6%. Of interest, five (4.3%) samples showed the T790M mutation in the plasma test, whereas this mutation was only detected in two (1.7%) tissue/cytology samples. Five (4.3%) samples were additionally positive in the plasma test. Overall, these results indicate that archived plasma samples can serve as an alternative source for the plasma EGFR mutation test when tissue samples are not available, and can improve precision medicine and long-term follow-up in a noninvasive manner.


Assuntos
Bancos de Espécimes Biológicos , Carcinoma Pulmonar de Células não Pequenas/genética , Neoplasias Pulmonares/genética , Mutação/genética , Plasma , Adulto , Idoso , Idoso de 80 Anos ou mais , Receptores ErbB/genética , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Medicina de Precisão
9.
Oncol Rep ; 41(5): 3119-3126, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30864724

RESUMO

Redd1 is a stress response protein that functions as a repressor of mTORC1, a central regulator of protein translation, resulting in the inhibition of cell growth and metabolism. However, paradoxically, high Redd1 expression favors cancer progression and generates resistance to cancer therapy. Herein, we revealed that constitutive overexpression of Redd1 induced HSP27 and HSP70 expression in lung cancer cells. The expression of Redd1, HSP27 and HSP70 was highly increased in lung cancer tissues compared with that in normal lung tissues. Inhibition of HSP27 or HSP70 suppressed AKT phosphorylation, which was induced by constitutive overexpression of Redd1 and enhanced the inhibitory effects on viability of Redd1­overexpressing cells. Inhibition of AKT phosphorylation resulted in a decrease of HSP27 and HSP70 expression in Redd1­overexpressing cells. These data indicated that HSPs and AKT in Redd1­overexpressing cells positively regulated the function and expression of each other and were involved in lung cancer cell survival. Knockdown of HSP27, HSP70 or AKT enhanced ionizing radiation (IR) sensitivity, particularly in lung cancer cells in which Redd1 was stably overexpressed. Collectively, constitutive overexpression of Redd1 led to HSP27 and HSP70 induction and AKT activation, which were involved in lung cancer cell survival and resistance to IR, suggesting that Redd1 may be used as a therapeutic target for lung cancer.


Assuntos
Proteínas de Choque Térmico HSP27/metabolismo , Proteínas de Choque Térmico HSP70/metabolismo , Neoplasias Pulmonares/radioterapia , Tolerância a Radiação , Fatores de Transcrição/metabolismo , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos da radiação , Proteínas de Choque Térmico , Humanos , Pulmão/patologia , Neoplasias Pulmonares/patologia , Chaperonas Moleculares , Fosforilação , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , RNA Interferente Pequeno/metabolismo , Radiação Ionizante , Transdução de Sinais/efeitos da radiação , Fatores de Transcrição/genética
10.
Clin Lab ; 64(9): 1573-1579, 2018 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-30273999

RESUMO

BACKGROUND: This study aimed to investigate the detection of methylated Septin 9 (mSEPT9) in Korean patients with colorectal cancer (CRC) and compare the results with those of previous studies. METHODS: A total of 127 plasma samples (111 patients with untreated CRC, 5 patients with adenomas, and 11 CRC patients treated with concurrent chemoradiotherapy before surgery) were collected. mSEPT9 was measured qualitatively with the Abbott RealTime ms9 Colorectal Cancer Assay. RESULTS: mSEPT9 was detected in 44 of 111 (39.6%) cases of untreated CRC but was not detected in the adenoma cases. The difference in the sensitivity of mSEPT9 among patients with adenomas and those with each stage of untreated CRC was statistically significant (Dukes' staging, p = 0.002 and TNM staging, p = 0.008). The sensitivity of mSEPT9 for each of the stages (I - IV) of untreated CRC patients were 20.7%, 54.1%, 36.6%, and 75.0%, respectively. The positive mSEPT9 results in untreated CRC patients reverted to negative in 19 of 21 patients (90.5%) after treatment. CONCLUSIONS: Compared to previous studies, the overall sensitivity of mSEPT9 was lower, but similar patterns were found in the sensitivities for each stage. Additionally, mSEPT9 appeared to have potential as a monitoring tool for CRC.


Assuntos
Adenoma/genética , Biomarcadores Tumorais/genética , Neoplasias Colorretais/genética , Metilação de DNA , Septinas/genética , Adenoma/etnologia , Adenoma/patologia , Adenoma/terapia , Adulto , Idoso , Idoso de 80 Anos ou mais , Grupo com Ancestrais do Continente Asiático/genética , Neoplasias Colorretais/etnologia , Neoplasias Colorretais/patologia , Neoplasias Colorretais/terapia , Feminino , Predisposição Genética para Doença , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Fenótipo , Valor Preditivo dos Testes , Estudos Prospectivos , Reação em Cadeia da Polimerase em Tempo Real , República da Coreia/epidemiologia
11.
Nanoscale ; 9(45): 17991-17999, 2017 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-29131226

RESUMO

New mechanisms were found for the formation of metal oxide microspheres with yolk-shell and filled structures by applying carbonaceous template microspheres with high porosity. Repeated impregnation first adopted to achieve a high loading rate of metal precursor in the carbonaceous template provided the breakthrough. The carbonaceous template with an appropriate loading rate of the metal precursor produced metal oxide microspheres with filled and yolk-shell structure depending on the ramping rate and oxygen concentration during the post-treatment process. Combustion of the carbonaceous template-which occurs during the moderate post-treatment process in air with a high oxygen concentration-must occur to form yolk-shell structured microspheres. On the other hand, the decomposition of carbon by post-treatment at a slow ramping rate in an atmosphere with a low oxygen concentration without burning produced filled-structured metal oxide microspheres. The carbonaceous template with a high loading rate of the metal precursor produced metal oxide microspheres with filled structures even at a fast ramping rate and high oxygen concentration during the post-treatment process. The new strategy was applied to synthesize various metal oxide microspheres including SnO2, Fe2O3, NiO, and Mn2O3 microspheres.

12.
Biomed Opt Express ; 8(5): 2649-2659, 2017 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-28663896

RESUMO

Non-thermal atmospheric-pressure plasma has been introduced in various applications such as sterilization, wound healing, blood coagulation, and other biomedical applications. The most attractive application of non-thermal atmospheric-pressure plasma is in cancer treatment, where the plasma is used to produce reactive oxygen species (ROS) to facilitate cell apoptosis. We investigate the effects of different durations of exposure to dielectric-barrier discharge (DBD) plasma on colon cancer cells using measurement of cell viability and ROS levels, western blot, immunocytochemistry, and Raman spectroscopy. Our results suggest that different kinds of plasma-treated cells can be differentiated from control cells using the Raman data.

13.
Biochem Biophys Res Commun ; 486(4): 1083-1089, 2017 05 13.
Artigo em Inglês | MEDLINE | ID: mdl-28377224

RESUMO

HER family receptors are frequently deregulated in breast cancer and the deregulation of these receptors is associated with poor prognosis. Thus, these receptors are considered therapeutic targets. In the present study, we found that piperlongumine (PL) downregulates the expression of HER family receptors HER1, HER2, and HER3 in breast cancer cells. Downregulation of these receptors by PL is mediated through the generation of reactive oxygen species (ROS), as N-acetyl-cysteine blocks it. Interestingly, the HER2-overexpressing cell lines BT474 and SkBr3 are somewhat more sensitive to PL than the low HER2-expressing cell line MCF7. In addition, the overexpression of HER2 increases the sensitivity of MCF7 cells to PL. Collectively, our data indicate the therapeutic potential of PL in the treatment of breast cancer.


Assuntos
Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/metabolismo , Dioxolanos/administração & dosagem , Receptores ErbB/biossíntese , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Antineoplásicos/administração & dosagem , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Regulação para Baixo/efeitos dos fármacos , Humanos , Células MCF-7
14.
Sci Rep ; 6: 28945, 2016 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-27358039

RESUMO

As the activation of autophagy contributes to the efficacy of many anticancer therapies, deciphering the precise role of autophagy in cancer therapy is critical. Here, we report that the dual mTORC1/2 inhibitors PP242 and OSI-027 decreased cell viability but did not induce apoptosis in the non-small cell lung cancer (NSCLC) cell lines H460 and A549. PP242 induced autophagy in NSCLC cells as demonstrated by the formation of massive vacuoles and acidic vesicular organelles and the accumulation of LC3-II. JNK was activated by PP242, and PP242-induced autophagy was blocked by inhibiting JNK pathway with SP600125 or JNK siRNA, suggesting that JNK activation is required for the mTORC1/2 inhibitor-mediated induction of autophagy in NSCLC cells. Inhibiting JNK or autophagy increased the sensitivity of H460 cells to mTORC1/2 inhibitors, indicating that JNK or autophagy promoted survival in NSCLC cells treated with mTORC1/2 inhibitors. Together, these data suggest that combining mTORC1/2 inhibitors with inhibitors of JNK or autophagy might be an effective approach for improving therapeutic outcomes in NSCLC.


Assuntos
Autofagia/efeitos dos fármacos , Carcinoma Pulmonar de Células não Pequenas/patologia , MAP Quinase Quinase 4/metabolismo , Alvo Mecanístico do Complexo 1 de Rapamicina/antagonistas & inibidores , Alvo Mecanístico do Complexo 2 de Rapamicina/antagonistas & inibidores , Antineoplásicos/metabolismo , Linhagem Celular Tumoral , Inibidores Enzimáticos/metabolismo , Humanos , Imidazóis/metabolismo , Indóis/metabolismo , Purinas/metabolismo , Triazinas/metabolismo
15.
Small ; 12(31): 4229-40, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27357165

RESUMO

The humidity dependence of the gas sensing characteristics of metal oxide semiconductors has been one of the greatest obstacles for gas sensor applications during the last five decades because ambient humidity dynamically changes with the environmental conditions. Herein, a new and novel strategy is reported to eliminate the humidity dependence of the gas sensing characteristics of oxide chemiresistors via dynamic self-refreshing of the sensing surface affected by water vapor chemisorption. The sensor resistance and gas response of pure In2 O3 hollow spheres significantly change and deteriorate in humid atmospheres. In contrast, the humidity dependence becomes negligible when an optimal concentration of CeO2 nanoclusters is uniformly loaded onto In2 O3 hollow spheres via layer-by-layer (LBL) assembly. Moreover, In2 O3 sensors LBL-coated with CeO2 nanoclusters show fast response/recovery, low detection limit (500 ppb), and high selectivity to acetone even in highly humid conditions (relative humidity 80%). The mechanism underlying the dynamic refreshing of the In2 O3 sensing surfaces regardless of humidity variation is investigated in relation to the role of CeO2 and the chemical interaction among CeO2 , In2 O3 , and water vapor. This strategy can be widely used to design high performance gas sensors including disease diagnosis via breath analysis and pollutant monitoring.


Assuntos
Cério/química , Nanoconjugados/química , Óxidos/química , Umidade
16.
ACS Appl Mater Interfaces ; 8(27): 17239-44, 2016 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-27315135

RESUMO

Multishelled, Pt-loaded Ce0.75Zr0.25O2 yolk-shell microspheres were prepared by a simple spray pyrolysis process for use in the water-gas shift (WGS) reaction. The Pt-loading was optimized, obtaining highly active Pt/Ce0.75Zr0.25O2 yolk-shell nanostructures for the WGS. Of the prepared catalysts, a 2% Pt loading of the Ce0.75Zr0.25O2 yolk-shell microspheres showed the highest CO conversion. The high catalytic activity of the 2% Pt/Ce0.75Zr0.2O2 catalyst was mainly due to its easier reducibility and the maintenance of active catalytic Pt species. The Pt-loaded Ce0.75Zr0.25O2 catalyst microspheres were highly resistant to Pt sintering because of their unique yolk-shell structure. Spray pyrolysis was found to be highly efficient for the production of precious-metal-loaded, multicomponent metal oxide yolk-shell microspheres for catalytic applications.

18.
Oncol Lett ; 10(2): 829-834, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26622578

RESUMO

Breast cancer cells possess a deregulated apoptotic pathway with increased expression levels of anti-apoptotic B-cell lymphoma-2 (Bcl-2) family proteins and ribosomal S6 kinase 1 (S6K1) protein activity. Therefore, combined interference of anti-apoptotic Bcl-2 family and S6K1 protein expression may be a reasonable therapeutic strategy for the treatment of patients with breast cancer. In the present study, it was identified that the administration of a combination of ABT263 [navitoclax; a Bcl-2/Bcl-extra large (Bcl-xL) inhibitor] and PF4708671 (an S6K1 inhibitor) markedly increased apoptotic cell death in the BT474 breast cancer cells compared with the administration of either agent alone. Furthermore, the downregulation of Bcl-2/Bcl-xL and S6K1 with small interfering RNA induced a significant increase in cell death compared with RNA interference of either agent alone. Notably, combination treatment with ABT263 and PF4708671 decreased the expression level of survivin protein, with this ectopic expression of survivin attenuating cell death. Thus, the present study determined that the combined inhibition of Bcl-2/Bcl-xL and S6K1 may be a good strategy for treating patients with breast cancer.

19.
Chemistry ; 21(50): 18202-8, 2015 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-26542385

RESUMO

Nanofibers composed of hollow CoFe2 O4 nanospheres covered with onion-like carbon are prepared by applying nanoscale Kirkendall diffusion to the electrospinning process. Amorphous carbon nanofibers embedded with CoFe2 @onion-like carbon nanospheres are prepared by reduction of the electrospun nanofibers. Oxidation of the CoFe2 -C nanofibers at 300 °C under a normal atmosphere produces porous nanofibers composed of hollow CoFe2 O4 nanospheres covered with onion-like carbon. CoFe2 nanocrystals are transformed into the hollow CoFe2 O4 nanospheres during oxidation through a well-known nanoscale Kirkendall diffusion process. The discharge capacities of the carbon-free CoFe2 O4 nanofibers composed of hollow nanospheres and the nanofibers composed of hollow CoFe2 O4 nanospheres covered with onion-like carbon are 340 and 930 mA h g(-1) , respectively, for the 1000th cycle at a current density of 1 A g(-1) . The nanofibers composed of hollow CoFe2 O4 nanospheres covered with onion-like carbon exhibit an excellent rate performance even in the absence of conductive materials.

20.
Chemistry ; 21(31): 11082-7, 2015 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-26119328

RESUMO

Phase-pure anatase TiO2 nanofibers with a fiber-in-tube structure were prepared by the electrospinning process. The burning of titanium-oxide-carbon composite nanofibers with a filled structure formed as an intermediate product under an oxygen atmosphere produced carbon-free TiO2 nanofibers with a fiber-in-tube structure. The sizes of the nanofiber core and hollow nanotube were 140 and 500 nm, respectively. The heat treatment of the electrospun nanofibers at 450 and 500 °C under an air atmosphere produced grey and white filled-structured TiO2 nanofibers, respectively. The initial discharge capacities of the TiO2 nanofibers with the fiber-in-tube and filled structures and the commercial TiO2 nanopowders were 231, 134, and 223 mA h g(-1) , respectively, and their corresponding charge capacities were 170, 100, and 169 mA h g(-1) , respectively. The 1000th discharge capacities of the TiO2 nanofibers with the fiber-in-tube and filled structures and the commercial TiO2 nanopowders were 177, 64, and 101 mA h g(-1) , respectively, and their capacity retentions measured from the second cycle were 89, 82, and 52 %, respectively. The TiO2 nanofibers with the fiber-in-tube structure exhibited low charge transfer resistance and structural stability during cycling and better cycling and rate performances than the TiO2 nanofibers with filled structures and the commercial TiO2 nanopowders.

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