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1.
Lancet ; 395(10240): 1835-1844, 2020 06 13.
Artigo em Inglês | MEDLINE | ID: mdl-32534646

RESUMO

BACKGROUND: IMspire150 aimed to evaluate first-line combination treatment with BRAF plus MEK inhibitors and immune checkpoint therapy in BRAFV600 mutation-positive advanced or metastatic melanoma. METHODS: IMspire150 was a randomised, double-blind, placebo-controlled phase 3 study done at 112 institutes in 20 countries. Patients with unresectable stage IIIc-IV, BRAFV600 mutation-positive melanoma were randomly assigned 1:1 to 28-day cycles of atezolizumab, vemurafenib, and cobimetinib (atezolizumab group) or atezolizumab placebo, vemurafenib, and cobimetinib (control group). In cycle 1, all patients received vemurafenib and cobimetinib only; atezolizumab placebo was added from cycle 2 onward. Randomisation was stratified by lactate dehydrogenase concentration and geographical region. Blinding for atezolizumab was achieved by means of an identical intravenous placebo, and blinding for vemurafenib was achieved by means of a placebo tablet. The primary outcome was investigator-assessed progression-free survival. This trial (ClinicalTrials.gov, NCT02908672) is ongoing but no longer recruiting patients. FINDINGS: Between Jan 13, 2017, and April 26, 2018, 777 patients were screened and 514 were enrolled and randomly assigned to the atezolizumab group (n=256) or control group (n=258). At a median follow-up of 18·9 months (IQR 10·4-23·8), progression-free survival as assessed by the study investigator was significantly prolonged with atezolizumab versus control (15·1 vs 10·6 months; hazard ratio [HR] 0·78; 95% CI 0·63-0·97; p=0·025). Common treatment-related adverse events (>30%) in the atezolizumab and control groups were blood creatinine phosphokinase increased (51·3% vs 44·8%), diarrhoea (42·2% vs 46·6%), rash (40·9%, both groups), arthralgia (39·1% vs 28·1%), pyrexia (38·7% vs 26·0%), alanine aminotransferase increased (33·9% vs 22·8%), and lipase increased (32·2% vs 27·4%); 13% of patients in the atezolizumab group and 16% in the control group stopped all treatment because of adverse events. INTERPRETATION: The addition of atezolizumab to targeted therapy with vemurafenib and cobimetinib was safe and tolerable and significantly increased progression-free survival in patients with BRAFV600 mutation-positive advanced melanoma. FUNDING: F Hoffmann-La Roche and Genentech.


Assuntos
Anticorpos Monoclonais Humanizados/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Azetidinas/uso terapêutico , Melanoma/tratamento farmacológico , Piperidinas/uso terapêutico , Vemurafenib/uso terapêutico , Adulto , Idoso , Anticorpos Monoclonais Humanizados/efeitos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Azetidinas/efeitos adversos , Método Duplo-Cego , Esquema de Medicação , Feminino , Humanos , Estimativa de Kaplan-Meier , Masculino , Melanoma/genética , Melanoma/patologia , Pessoa de Meia-Idade , Mutação , Metástase Neoplásica , Estadiamento de Neoplasias , Piperidinas/efeitos adversos , Intervalo Livre de Progressão , Proteínas Proto-Oncogênicas B-raf/genética , Vemurafenib/efeitos adversos
2.
Genet Epidemiol ; 40(4): 333-40, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-27061717

RESUMO

DNA methylation is a key epigenetic mark involved in both normal development and disease progression. Recent advances in high-throughput technologies have enabled genome-wide profiling of DNA methylation. However, DNA methylation profiling often employs different designs and platforms with varying resolution, which hinders joint analysis of methylation data from multiple platforms. In this study, we propose a penalized functional regression model to impute missing methylation data. By incorporating functional predictors, our model utilizes information from nonlocal probes to improve imputation quality. Here, we compared the performance of our functional model to linear regression and the best single probe surrogate in real data and via simulations. Specifically, we applied different imputation approaches to an acute myeloid leukemia dataset consisting of 194 samples and our method showed higher imputation accuracy, manifested, for example, by a 94% relative increase in information content and up to 86% more CpG sites passing post-imputation filtering. Our simulated association study further demonstrated that our method substantially improves the statistical power to identify trait-associated methylation loci. These findings indicate that the penalized functional regression model is a convenient and valuable imputation tool for methylation data, and it can boost statistical power in downstream epigenome-wide association study (EWAS).


Assuntos
Metilação de DNA , Estudos de Associação Genética/métodos , Leucemia Mieloide Aguda/genética , Ilhas de CpG/genética , Epigênese Genética , Humanos , Modelos Lineares , Modelos Genéticos
3.
Bioinformatics ; 29(6): 799-801, 2013 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-23357921

RESUMO

Recent advances in sequencing technologies have revolutionized genetic studies. Although high-coverage sequencing can uncover most variants present in the sequenced sample, low-coverage sequencing is appealing for its cost effectiveness. Here, we present AbCD (arbitrary coverage design) to aid the design of sequencing-based studies. AbCD is a user-friendly interface providing pre-estimated effective sample sizes, specific to each minor allele frequency category, for designs with arbitrary coverage (0.5-30×) and sample size (20-10 000), and for four major ethnic groups (Europeans, Africans, Asians and African Americans). In addition, we also present two software tools: ShotGun and DesignPlanner, which were used to generate the estimates behind AbCD. ShotGun is a flexible short-read simulator for arbitrary user-specified read length and average depth, allowing cycle-specific sequencing error rates and realistic read depth distributions. DesignPlanner is a full pipeline that uses ShotGun to generate sequence data and performs initial SNP discovery, uses our previously presented linkage disequilibrium-aware method to call genotypes, and, finally, provides minor allele frequency-specific effective sample sizes. ShotGun plus DesignPlanner can accommodate effective sample size estimate for any combination of high-depth and low-depth data (for example, whole-genome low-depth plus exonic high-depth) or combination of sequence and genotype data [for example, whole-exome sequencing plus genotyping from existing Genomewide Association Study (GWAS)].


Assuntos
Sequenciamento de Nucleotídeos em Larga Escala/métodos , Software , Frequência do Gene , Genômica , Técnicas de Genotipagem , Desequilíbrio de Ligação , Polimorfismo de Nucleotídeo Único , Análise de Sequência de DNA/métodos
4.
Appl Opt ; 52(30): 7376-81, 2013 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-24216593

RESUMO

The light distribution of a light-emitting diode (LED), using remote phosphor with a patterned sapphire substrate, is evaluated in this study. Three kinds of substrates of the remote phosphors, including planar sapphire (PS), partially patterned sapphire (PPS), and fully patterned sapphire (FPS) are prepared. The LED with the remote phosphor of FPS delivers much better uniformity of the correlated color temperature (CCT) in a far-field pattern than the CCT obtained in the cases of PS and PPS. The results are majorly attributed to the improvement in the scattering ability of the blue light in the FPS; thereby increasing the excitation of the phosphor particles in comparison to the ability of the device assembled with the remote phosphor of PS or PPS.

5.
Clin Cancer Res ; 29(17): 3292-3300, 2023 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-37339186

RESUMO

PURPOSE: To report the safety and efficacy of ipatasertib (AKT inhibitor) combined with rucaparib (PARP inhibitor) in patients with metastatic castration-resistant prostate cancer (mCRPC) previously treated with second-generation androgen receptor inhibitors. PATIENTS AND METHODS: In this two-part phase Ib trial (NCT03840200), patients with advanced prostate, breast, or ovarian cancer received ipatasertib (300 or 400 mg daily) plus rucaparib (400 or 600 mg twice daily) to assess safety and identify a recommended phase II dose (RP2D). A part 1 dose-escalation phase was followed by a part 2 dose-expansion phase in which only patients with mCRPC received the RP2D. The primary efficacy endpoint was prostate-specific antigen (PSA) response (≥50% reduction) in patients with mCRPC. Patients were not selected on the basis of tumor mutational status. RESULTS: Fifty-one patients were enrolled (part 1 = 21; part 2 = 30). Ipatasertib 400 mg daily plus rucaparib 400 mg twice daily was the selected RP2D, received by 37 patients with mCRPC. Grade 3/4 adverse events occurred in 46% (17/37) of patients, with one grade 4 adverse event (anemia, deemed related to rucaparib) and no deaths. Adverse events leading to treatment modification occurred in 70% (26/37). The PSA response rate was 26% (9/35), and the objective response rate per Response Criteria in Solid Tumors (RECIST) 1.1 was 10% (2/21). Median radiographic progression-free survival per Prostate Cancer Working Group 3 criteria was 5.8 months [95% confidence interval (CI), 4.0-8.1], and median overall survival was 13.3 months (95% CI, 10.9-not evaluable). CONCLUSIONS: Ipatasertib plus rucaparib was manageable with dose modification but did not demonstrate synergistic or additive antitumor activity in previously treated patients with mCRPC.


Assuntos
Antineoplásicos , Neoplasias de Próstata Resistentes à Castração , Masculino , Humanos , Neoplasias de Próstata Resistentes à Castração/patologia , Antígeno Prostático Específico , Antineoplásicos/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos
6.
Clin Transl Sci ; 15(12): 2989-2999, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36197694

RESUMO

Ipatasertib, an AKT inhibitor, in combination with prednisone and abiraterone, is under evaluation for the treatment of metastatic castration-resistant prostate cancer (mCRPC). Hyperglycemia is an on-target effect of ipatasertib. An open-label, single-arm, single-sequence, signal-seeking study (n = 25 mCRPC patients) was conducted to evaluate the glucose changes across four different treatment periods: ipatasertib alone, ipatasertib-prednisone combination, ipatasertib-prednisone-abiraterone combination (morning dose), and ipatasertib-prednisone-abiraterone combination (evening dose). Continuous glucose monitoring (CGM) was used in this study to compare the dynamic glucose changes across the different treatment periods. Four key parameters: average glucose, peak glucose and % time in range (70-180 and >180 mg/dl) were evaluated for this comparison. Ipatasertib-prednisone-abiraterone combination when administered in the morning after an overnight fast significantly increased average glucose, peak glucose and % time in range >180 mg/dl compared to ipatasertib monotherapy. Ipatasertib, when co-administered with abiraterone, increased ipatasertib and M1 (G-037720) metabolite exposures by approximately 1.5- and 2.2-fold, respectively. Exposure-response analysis results show that increased exposures of ipatasertib in combination with abiraterone are associated with increased glucose levels. When ipatasertib-prednisone-abiraterone combination was administered as an evening dose compared to a morning dose, lowered peak glucose and improved % time in range was observed. The results from this study suggest that dosing ipatasertib after an evening meal followed by overnight fasting can be an effective strategy for managing increased glucose levels.


Assuntos
Neoplasias de Próstata Resistentes à Castração , Humanos , Masculino , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Glicemia , Automonitorização da Glicemia , Glucose/uso terapêutico , Prednisona/uso terapêutico , Neoplasias de Próstata Resistentes à Castração/tratamento farmacológico , Neoplasias de Próstata Resistentes à Castração/metabolismo , Neoplasias de Próstata Resistentes à Castração/patologia , Resultado do Tratamento
7.
Diagnostics (Basel) ; 12(3)2022 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-35328245

RESUMO

A midline shift (MLS) is an important clinical indicator for intracranial hemorrhage. In this study, we proposed a robust, fully automatic neural network-based model for the detection of MLS and compared it with MLSs drawn by clinicians; we also evaluated the clinical applications of the fully automatic model. We recruited 300 consecutive non-contrast CT scans consisting of 7269 slices in this study. Six different types of hemorrhage were included. The automatic detection of MLS was based on modified Keypoint R-CNN with keypoint detection followed by training on the ResNet-FPN-50 backbone. The results were further compared with manually drawn outcomes and manually defined keypoint calculations. Clinical parameters, including Glasgow coma scale (GCS), Glasgow outcome scale (GOS), and 30-day mortality, were also analyzed. The mean absolute error for the automatic detection of an MLS was 0.936 mm compared with the ground truth. The interclass correlation was 0.9899 between the automatic method and MLS drawn by different clinicians. There was high sensitivity and specificity in the detection of MLS at 2 mm (91.7%, 80%) and 5 mm (87.5%, 96.7%) and MLSs greater than 10 mm (85.7%, 97.7%). MLS showed a significant association with initial poor GCS and GCS on day 7 and was inversely correlated with poor 30-day GOS (p < 0.001). In conclusion, automatic detection and calculation of MLS can provide an accurate, robust method for MLS measurement that is clinically comparable to the manually drawn method.

8.
J Clin Med ; 10(19)2021 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-34640449

RESUMO

BACKGROUND: The performance of chest radiography-based age and sex prediction has not been well validated. We used a deep learning model to predict the age and sex of healthy adults based on chest radiographs (CXRs). METHODS: In this retrospective study, 66,643 CXRs of 47,060 healthy adults were used for model training and testing. In total, 47,060 individuals (mean age ± standard deviation, 38.7 ± 11.9 years; 22,144 males) were included. By using chronological ages as references, mean absolute error (MAE), root mean square error (RMSE), and Pearson's correlation coefficient were used to assess the model performance. Summarized class activation maps were used to highlight the activated anatomical regions. The area under the curve (AUC) was used to examine the validity for sex prediction. RESULTS: When model predictions were compared with the chronological ages, the MAE was 2.1 years, RMSE was 2.8 years, and Pearson's correlation coefficient was 0.97 (p < 0.001). Cervical, thoracic spines, first ribs, aortic arch, heart, rib cage, and soft tissue of thorax and flank seemed to be the most crucial activated regions in the age prediction model. The sex prediction model demonstrated an AUC of >0.99. CONCLUSION: Deep learning can accurately estimate age and sex based on CXRs.

9.
J Biosci Bioeng ; 130(2): 187-194, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32334990

RESUMO

Carotenoids serve as one of the most important group of naturally-occurring lipid-soluble pigments which exhibit great biological activities such as antioxidant, anti-inflammatory and provitamin A activities. Owing to their advantageous health effects, carotenoids are widely applied in various industries. Microbial carotenoids synthesis therefore has attracted increasing attention in recent years. In the present study, a marine microorganism originally isolated from seawater in northern Taiwan was determined to be a strain of Gordonia terrae based on its 16S rRNA gene sequence. The strain G. terrae TWRH01 has the ability to synthesize and accumulate the intracellular pigments was identified by gas chromatography-mass spectrometry (GC-MS). The biochemical production characteristics of this strain were studied by employing different fermentation strategies. Findings suggested that G. terrae TWRH01 can actively grow and efficiently synthesize carotenoids in medium adjusted to pH 7 containing 16 g L-1 sucrose as the carbon source, 16 g L-1 yeast extract as the nitrogen source, 0.6 M NaCl concentration, and supplemented with 0.45% (v/v) 1 M CaCl2. Results revealed that the optimization of fermentation yielded 15.29 g L-1 dry biomass and 10.58 µmol L-1 relative ß-carotene concentration. According to GC-MS analysis, the orange-red colored pigments produced were identified as carotenoid derivatives, mainly echinenone and adonixanthin 3'-ß-d-glucoside. Therefore, the new bacterial strain showed a highly potential bioresource for the commercial production of natural carotenoids.


Assuntos
Actinobacteria/metabolismo , Carotenoides/metabolismo , Fermentação , Microbiologia Industrial , Actinobacteria/genética , Biomassa , Nitrogênio/metabolismo , RNA Ribossômico 16S/genética , Taiwan
10.
J Mol Neurosci ; 70(10): 1461-1470, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32472393

RESUMO

Glioblastoma multiforme (GBM) is the most common type of malignant brain tumor. The present standard treatment for GBM has not been effective; therefore, the prognosis remains dramatically poor and prolonged survival after treatment is still limited. The new therapeutic strategies are urgently needed to improve the treatment efficiency. Doxorubicin (Dox) has been widely used in the treatment of many cancers for decades. In recent years, with the advancement of delivery technology, more and more research indicates that Dox has the opportunity to be used in the treatment of GBM. Amphiregulin (AREG), a ligand of the epidermal growth factor receptor (EGFR), has been reported to have oncogenic effects in many cancer cell types and is implicated in drug resistance. However, the biological function and molecular mechanism of AREG in Dox treatment of GBM are still unclear. Here, we demonstrate that knockdown of AREG can boost Dox-induced endoplasmic reticulum (ER) stress to trigger activation in both autophagy and apoptosis in GBM cells, ultimately leading to cell death. To explore the importance of AREG in the clinic, we used available bioinformatics tools and found AREG is highly expressed in GBM tumor tissues that are associated with poor survival. In addition, we also used antibody array analysis to dissect pathways that are likely to be activated by AREG. Taken together, our results revealed AREG can serve as a potential therapeutic target and a promising biomarker in GBM.


Assuntos
Anfirregulina/genética , Apoptose , Autofagia , Neoplasias Encefálicas/metabolismo , Estresse do Retículo Endoplasmático , Glioblastoma/metabolismo , Anfirregulina/metabolismo , Antineoplásicos/toxicidade , Biomarcadores Tumorais/genética , Biomarcadores Tumorais/metabolismo , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/patologia , Linhagem Celular Tumoral , Doxorrubicina/toxicidade , Glioblastoma/genética , Glioblastoma/patologia , Humanos , Neurônios/efeitos dos fármacos , Neurônios/metabolismo
11.
J Thorac Oncol ; 15(8): 1351-1360, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32302702

RESUMO

INTRODUCTION: Cytotoxic agents have immunomodulatory effects, providing a rationale for combining atezolizumab (anti-programmed death-ligand 1 [anti-PD-L1]) with chemotherapy. The randomized phase III IMpower131 study (NCT02367794) evaluated atezolizumab with platinum-based chemotherapy in stage IV squamous NSCLC. METHODS: A total of 1021 patients were randomized 1:1:1 to receive atezolizumab+carboplatin+paclitaxel (A+CP) (n = 338), atezolizumab+carboplatin+nab-paclitaxel (A+CnP) (n = 343), or carboplatin+nab-paclitaxel (CnP) (n = 340) for four or six 21-day cycles; patients randomized to the A+CP or A+CnP arms received atezolizumab maintenance therapy until progressive disease or loss of clinical benefit. The coprimary end points were investigator-assessed progression-free survival (PFS) and overall survival (OS) in the intention-to-treat (ITT) population. The secondary end points included PFS and OS in PD-L1 subgroups and safety. The primary PFS (January 22, 2018) and final OS (October 3, 2018) for A+CnP versus CnP are reported. RESULTS: PFS improvement with A+CnP versus CnP was seen in the ITT population (median, 6.3 versus 5.6 mo; hazard ratio [HR] = 0.71, 95% confidence interval [CI]: 0.60-0.85; p = 0.0001). Median OS in the ITT population was 14.2 and 13.5 months in the A+CnP and CnP arms (HR = 0.88, 95% CI: 0.73-1.05; p = 0.16), not reaching statistical significance. OS improvement with A+CnP versus CnP was observed in the PD-L1-high subgroup (HR = 0.48, 95% CI: 0.29-0.81), despite not being formally tested. Treatment-related grade 3 and 4 adverse events and serious adverse events occurred in 68.0% and 47.9% (A+CnP) and 57.5% and 28.7% (CnP) of patients, respectively. CONCLUSIONS: Adding atezolizumab to platinum-based chemotherapy significantly improved PFS in patients with first-line squamous NSCLC; OS was similar between the arms.


Assuntos
Carcinoma de Células Escamosas , Neoplasias Pulmonares , Albuminas , Anticorpos Monoclonais Humanizados , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Carboplatina , Carcinoma de Células Escamosas/tratamento farmacológico , Humanos , Neoplasias Pulmonares/tratamento farmacológico , Paclitaxel/uso terapêutico
12.
J Biosci Bioeng ; 126(3): 322-329, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29784541

RESUMO

This first-attempt study tended to decipher synergistic interactions of model redox mediators (RMs) to echinenone production for electrochemically-steered fermentation (ESF). The findings indicated that supplement of RMs could significantly stimulate the production performance of fermentation (e.g., 36% for 4-aminophenol) which was parallel with stimulation of bioelectricity generation in microbial fuel cells (MFCs) as prior studies mentioned. Although redox mediators could usually enhance electron transport extracellular compartment, the mechanisms of bioelectricity generation in MFCs and echinenone production in ESF were very likely functioned in the extracellular and the intracellular compartment, respectively. In MFCs, electron transfer towards biofilm anode for bioelectricity generation must be taken place. However, for ESF echinenone accumulation was very likely occurred in the intracellular compartment, thus electron transfer was predominantly implemented in the intracellular, not the extracellular compartment.


Assuntos
Fontes de Energia Bioelétrica , Carotenoides/metabolismo , Técnicas Eletroquímicas/métodos , Bactéria Gordonia/metabolismo , Biofilmes , Reatores Biológicos/microbiologia , Eletrodos , Transporte de Elétrons , Elétrons , Fermentação , Oxirredução , Microbiologia do Solo
13.
Beilstein J Nanotechnol ; 9: 1602-1612, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29977694

RESUMO

We produced an anodic aluminum oxide (AAO) structure with periodic nanopores on the surface of flip-chip blue light-emitting diodes (FC-BLEDs). The nanopores had diameters ranging from 73 to 85 nm and were separated by distances ranging from approximately 10 to 15 nm. The light extraction efficiency enhancement of the FC-BLEDs subjected to different durations of the second pore-widening process was approximately 1.6-2.9%. The efficiency enhancement may be attributed to the following mechanism: periodic nanopores on the surface of FC-BLEDs reduce the critical angle of total reflection and effective energy transfer from a light emitter into a surface plasmon mode produced by AAO.

14.
PLoS One ; 9(11): e110679, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25383782

RESUMO

Genotype imputation has become standard practice in modern genetic studies. As sequencing-based reference panels continue to grow, increasingly more markers are being well or better imputed but at the same time, even more markers with relatively low minor allele frequency are being imputed with low imputation quality. Here, we propose new methods that incorporate imputation uncertainty for downstream association analysis, with improved power and/or computational efficiency. We consider two scenarios: I) when posterior probabilities of all potential genotypes are estimated; and II) when only the one-dimensional summary statistic, imputed dosage, is available. For scenario I, we have developed an expectation-maximization likelihood-ratio test for association based on posterior probabilities. When only imputed dosages are available (scenario II), we first sample the genotype probabilities from its posterior distribution given the dosages, and then apply the EM-LRT on the sampled probabilities. Our simulations show that type I error of the proposed EM-LRT methods under both scenarios are protected. Compared with existing methods, EM-LRT-Prob (for scenario I) offers optimal statistical power across a wide spectrum of MAF and imputation quality. EM-LRT-Dose (for scenario II) achieves a similar level of statistical power as EM-LRT-Prob and, outperforms the standard Dosage method, especially for markers with relatively low MAF or imputation quality. Applications to two real data sets, the Cebu Longitudinal Health and Nutrition Survey study and the Women's Health Initiative Study, provide further support to the validity and efficiency of our proposed methods.


Assuntos
Estudos de Associação Genética/métodos , Marcadores Genéticos/genética , Variação Genética , Genótipo , Modelos Genéticos , Simulação por Computador , Humanos , Funções Verossimilhança
15.
ACS Appl Mater Interfaces ; 4(3): 1449-55, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22301712

RESUMO

Flexible polymer films with high electrical conductivity were prepared through a simple coating of well-dispersed silver nanoparticle (AgNP) and multiwalled carbon nanotube (CNT) solution. The hybrid film with surface resistance as low as 1 × 10(-2) Ω/sq was prepared by controlling the annealing temperature in air and by using a suitable composition of silver nitrate/CNT/poly(oxyethylene)-oligo(imide) (POE-imide) in the ratio 20:1:20 by weight. During the heating, color of the film surface changed from black to golden to milky white, indicating the accumulation of AgNPs through surface migration and melting into CNT-connected networks. Thermogravimetric measurements showed that the transition temperature of 170 °C was responsible for the POE-imide degeneration and the subsequent Ag melting with a decrease in the surface resistance from 2.1 × 10(5) to 2.0 × 10(-1) Ω/sq, which was able to illuminate light-emitting diode lamps because of the formation of a continuous Ag network.

16.
ACS Nano ; 6(8): 7016-25, 2012 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-22747428

RESUMO

One-dimensional cobalt sulfide (CoS) acicular nanorod arrays (ANRAs) were obtained on a fluorine-doped tin oxide (FTO) substrate by a two-step approach. First, Co(3)O(4) ANRAs were synthesized, and then they were converted to CoS ANRAs for various periods. The compositions of the films obtained after various conversion periods were verified by X-ray diffraction, UV-visible spectrophotometry, and X-ray photoelectron spectroscopy; their morphologies were examined at different periods by scanning electron microscopic and transmission electron microscopic images. Electrocatalytic abilities of the films toward I(-)/I(3)(-) were verified through cyclic voltammetry (CV) and Tafel polarization curves. Long-term stability of the films in I(-)/I(3)(-) electrolyte was studied by CV. The FTO substrates with CoS ANRAs were used as the counter electrodes for dye-sensitized solar cells; a maximum power conversion efficiency of 7.67% was achieved for a cell with CoS ANRAs, under 100 mW/cm(2), which is nearly the same as that of a cell with a sputtered Pt counter electrode (7.70%). Electrochemical impedance spectroscopy was used to substantiate the photovoltaic parameters.


Assuntos
Cobalto/química , Corantes/química , Fontes de Energia Elétrica , Nanoestruturas/química , Nanoestruturas/efeitos da radiação , Silício/química , Energia Solar , Desenho de Equipamento , Análise de Falha de Equipamento , Teste de Materiais , Microeletrodos , Nanoestruturas/ultraestrutura , Tamanho da Partícula
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