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1.
Mikrochim Acta ; 190(11): 439, 2023 10 16.
Artigo em Inglês | MEDLINE | ID: mdl-37845383

RESUMO

A novel nanocomposite material, ferric vanadate intertwined multi-walled carbon nanotubes (FeV/MWCNTs), has been designed which was drop-coated onto a glassy carbon electrode (GCE). The constructed sensor was used for the sensitive determination of uric acid (UA) in fetal bovine serum (FBS) and human serum (HS). A series of characterization and electrochemical tests showed that the ultrasound-assisted assembly of FeV with MWCNTs not only overcame the disadvantages of low conductivity and easy (unwanted) aggregation, but also avoided the decrease in effective surface area due to the severe aggregation of each individual raw material. The fabricated FeV/MWCNTs nanocomposites exhibited higher conductivity, larger effective surface area, and better electrocatalytic activity. In addition, under optimized conditions, the developed electrochemical sensor FeV/MWCNTs/GCE has a lower limit of detection (LOD, 0.05 µM; Ep = 0.268 V vs. Ag/AgCl) and wider linear range (0.20-100 µM), which can satisfy the criteria of trace UA detection. The results of UA determination in FBS (recovery = 95.5-103%; RSD ≤ 3.1%) and HS (recovery = 95.5-103%; RSD ≤ 4.3%) further validated the feasibility of FeV/MWCNTs-based electrochemical sensors for the determination of UA in biological fluids.


Assuntos
Nanocompostos , Nanotubos de Carbono , Humanos , Nanotubos de Carbono/química , Soroalbumina Bovina , Ácido Úrico , Vanadatos , Técnicas Eletroquímicas/métodos , Limite de Detecção , Nanocompostos/química , Ferro
2.
Molecules ; 28(8)2023 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-37110588

RESUMO

The design and preparation of cheaper, greener and more efficient adsorbents is essential for the removal of pollutants by adsorption. In this study, biochar was prepared from peel of Brassica juncea var. gemmifera Lee et Lin (PoBJ) using a facile, low-temperature and vacuum pyrolysis, and the adsorption mechanism toward organic dyes in aqueous solution was elucidated. The adsorbent was characterized by XPS, FT-IR and SEM, and zeta potential techniques. The adsorption ability of PoBJ biochar for cationic dyes (methylene blue, brilliant green, calcein-safranine, azure I, rhodamine B), anionic dyes (alizarin yellow R), and neutral dyes (neutral red) revealed that the biochar exhibited adsorption selectivity toward cationic dyes. The effects of different factors on the adsorption performance of PoBJ biochar, as well as the adsorption kinetics and thermodynamics, were further investigated by using methylene blue as the model adsorbate. These factors included temperature, pH, contact time and dye concentration. The experimental results showed that BJ280 and BJ160 (prepared at 280 °C and 160 °C, respectively) possessed relatively higher adsorption capacity of 192.8 and 167.40 mg g-1 for methylene blue (MB), respectively, demonstrating the possibility of utilization of PoBJ biochar as a superior bio-adsorbent. The experimental data of BJ160 toward MB were correlated with various kinetic and isothermal models. The results indicated that the adsorption process was consistent with the Langmuir isotherm model and nonlinear pseudo-second-order kinetic model. Thermodynamic parameters indicated that the adsorption of MB onto BJ160 was exothermic. Thus, the low-temperature prepared PoBJ biochar was an environmentally friendly, economic and efficient cationic dye adsorbent.

3.
Molecules ; 28(2)2023 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-36677697

RESUMO

Emerging chromium (Cr) species have attracted increasing concern. A majority of Cr species, especially hexavalent chromium (Cr(VI)), could lead to lethal effects on human beings, animals, and aquatic lives even at low concentrations. One of the conventional water-treatment methodologies, adsorption, could remove these toxic Cr species efficiently. Additionally, adsorption possesses many advantages, such as being cost-saving, easy to implement, highly efficient and facile to design. Previous research has shown that the application of different adsorbents, such as carbon nanotubes (carbon nanotubes (CNTs) and graphene oxide (GO) and its derivatives), activated carbons (ACs), biochars (BCs), metal-based composites, polymers and others, is being used for Cr species removal from contaminated water and wastewater. The research progress and application of adsorption for Cr removal in recent years are reviewed, the mechanisms of adsorption are also discussed and the development trend of Cr treatment by adsorption is proposed.

4.
Molecules ; 27(13)2022 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-35807253

RESUMO

Nickel-coated graphite (Ni/C) powder has many applications in diverse areas such as paint, print ink, adhesive, conductive rubber, and so on. To increase its stability in harsh environmental conditions, the electroless plating of silver film on Ni/C via ascorbic acid was studied. A silver layer with a thickness of 2.5 µm was successfully plated on Ni/C powder's surface with an Ag loading of 44.35 wt.%. Silica gel blended with the Ag/Ni/C powder exhibited much higher conductivity under aging conditions of 85 °C and 85% RH for 1000 h than that with pristine Ni/C powder. Further tests showed that the conductivity of Ag/Ni/C powder remained almost unchanged even in an extremely humid and hot condition for 1000 h. Aging tests were carried out for Ag/Ni/C and Ni/C powders under long-term humid and hot conditions (85 °C, 85% RH), in which Ag/Ni/C samples showed much better electromagnetic shielding performance. Due to the excellent properties and reasonable price, the potential applications of Ag/Ni/C in conductive glue and electromagnetic shielding glue could be expected.


Assuntos
Grafite , Prata , Temperatura Alta , Umidade , Níquel , Pós
5.
Molecules ; 27(10)2022 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-35630583

RESUMO

In this study, a new electrolyte additive 1,3,5-tri-2-propenyl-1,3,5-triazine-2,4,6-(1H, 3H, 5H)-trione (TAIC) for lithium-ion batteries is reported. The additive is introduced as a novel electrolyte additive to enhance electrochemical performances of layered lithium nickel cobalt manganese oxide (NCM) and lithium cobalt oxide (LiCoO2) cathodes, especially under a higher working voltage. Encouragingly, we found protective films would be formed on the cathode surface by the electrochemical oxidation, and the stability of the cathode material-electrolyte interface was greatly promoted. By adding 0.5 wt.% of TAIC into the electrolyte, the battery exhibited outstanding performances. The thickness swelling decreased to about 6% after storage at 85 °C for 24 h, while the capacity retention of cycle-life performances under high temperature of 45 °C after the 600th cycle increased 10% in comparison with the batteries without TAIC. Due to its specific function, the additive can be used in high energy density and high voltage lithium-ion battery systems.

6.
Molecules ; 27(16)2022 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-36014402

RESUMO

In order to properly reuse food waste and remove various contaminants from wastewater, the development of green, sustainable and clean technologies has demonstrated potential in the efficient inhibition of secondary pollution to the environment. In this study, an economical and green method was used to prepare biochar from crisp persimmon peel (CPP) using flash-vacuum pyrolysis at different temperatures (200-700 °C; referred to as CPP200-CPP700). CPP200 has high polarity, low aromaticity and high oxygen-containing functional groups that exhibit superior MB adsorption capabilities. CPP200 that was prepared at a relatively low temperature of 200 °C exhibited a high adsorption capacity of 59.72 mg/g toward methylene blue (MB), which was relatively higher than that for alizarin yellow R (4.05 mg/g) and neutral red (39.08 mg/g), indicating that CPP200 possesses a higher adsorption selectivity for cationic dyes. Kinetics investigation revealed that the kinetic data of CPP200 for the adsorption of MB was better fitted by a linear pseudo-second-order model. Isothermal studies indicated that the linear Langmuir model was more suitable for describing the adsorption process. The adsorption thermodynamics illustrated that the adsorption of MB onto CPP200 was spontaneous and endothermic. EDS and IR analyses of CPP200 for both pre- and post-adsorption of MB showed that electrostatic interactions between oxygen-containing groups on biochar and target MB dominated the adsorption procedure, in addition to hydrogen bonding interactions. Reusability tests confirmed the excellent regeneration characteristics of CPP200, indicating that CPP200 may be used as a green, sustainable, highly efficient and recyclable adsorbent for the selective removal of cationic organic dyes.


Assuntos
Diospyros , Eliminação de Resíduos , Poluentes Químicos da Água , Adsorção , Corantes , Alimentos , Concentração de Íons de Hidrogênio , Cinética , Azul de Metileno , Oxigênio , Pirólise , Temperatura
7.
Small ; 17(49): e2102155, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34309180

RESUMO

Energy shortages and greenhouse effects are two unavoidable problems that need to be solved. Photocatalytically converting CO2 into a series of valuable chemicals is considered to be an effective means of solving the above dilemmas. Among these photocatalysts, the utilization of black phosphorus for CO2 photocatalytic reduction deserves a lightspot not only for its excellent catalytic activity through different reaction routes, but also on account of the great preponderance of this relatively cheap catalyst. Herein, this review offers a summary of the recent advances in synthesis, structure, properties, and application for CO2 photocatalytic reduction. In detail, the review starts from the basic principle of CO2 photocatalytic reduction. In the following section, the synthesis, structure, and properties, as well as CO2 photocatalytic reduction process of black phosphorus-based photocatalyst are discussed. In addition, some possible influencing factors and reaction mechanism are also summarized. Finally, a summary and the possible future perspectives of black phosphorus-based photocatalyst for CO2 reduction are established.

8.
Sensors (Basel) ; 21(10)2021 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-34067559

RESUMO

Weakly supervised instance segmentation (WSIS) provides a promising way to address instance segmentation in the absence of sufficient labeled data for training. Previous attempts on WSIS usually follow a proposal-based paradigm, critical to which is the proposal scoring strategy. These works mostly rely on certain heuristic strategies for proposal scoring, which largely hampers the sustainable advances concerning WSIS. Towards this end, this paper introduces a novel framework for weakly supervised instance segmentation, called Weakly Supervised R-CNN (WS-RCNN). The basic idea is to deploy a deep network to learn to score proposals, under the special setting of weak supervision. To tackle the key issue of acquiring proposal-level pseudo labels for model training, we propose a so-called Attention-Guided Pseudo Labeling (AGPL) strategy, which leverages the local maximal (peaks) in image-level attention maps and the spatial relationship among peaks and proposals to infer pseudo labels. We also suggest a novel training loss, called Entropic OpenSet Loss, to handle background proposals more effectively so as to further improve the robustness. Comprehensive experiments on two standard benchmarking datasets demonstrate that the proposed WS-RCNN can outperform the state-of-the-art by a large margin, with an improvement of 11.6% on PASCAL VOC 2012 and 10.7% on MS COCO 2014 in terms of mAP50, which indicates that learning-based proposal scoring and the proposed WS-RCNN framework might be a promising way towards WSIS.

9.
Anal Bioanal Chem ; 412(11): 2551-2564, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32162086

RESUMO

A novel electrochemical sensor, platinum nanoparticles/graphene nanoplatelets/multi-walled carbon nanotubes/ß-cyclodextrin composite (PtNPs-GNPs-MWCNTs-ß-CD) modified carbon glass electrode (GCE), was fabricated and used for the sensitive detection of folic acid (FA). The PtNPs-GNPs-MWCNTs-ß-CD nanocomposite was easily prepared with an ultrasound-assisted assembly method, and it was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical behavior of FA at PtNPs-GNPs-MWCNTs-ß-CD/GCE was investigated in detail. Some key experimental parameters such as pH, amount of PtNPs-GNPs-MWCNTs-ß-CD composite, and scan rate were optimized. A good linear relationship (R2 = 0.9942) between peak current of cyclic voltammetry (CV) and FA concentration in the range 0.02-0.50 mmol L-1 was observed at PtNPs-GNPs-MWCNTs-ß-CD/GCE. The detection limit was 0.48 µmol L-1 (signal-to-noise ratio = 3). A recovery of 97.55-102.96% was obtained for the determination of FA in FA pills (containing 0.4 mg FA per pill) at PtNPs-GNPs-MWCNTs-ß-CD/GCE, indicating that the modified electrode possessed relatively high sensitivity and stability for the determination of FA in real samples.


Assuntos
Técnicas Eletroquímicas/métodos , Ácido Fólico/análise , Nanocompostos/química , Nanotubos de Carbono/química , Platina/química , Complexo Vitamínico B/análise , Grafite/química , Limite de Detecção , Nanopartículas Metálicas/química , Comprimidos , beta-Ciclodextrinas/química
10.
Ecotoxicol Environ Saf ; 201: 110862, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32559691

RESUMO

In this study, a novel electrochemical sensor based on self-assembled rod-like lanthanum hydroxide-oxidized multi-walled carbon nanotubes (La(OH)3-OxMWCNTs) nanocomposite was developed for sensitive determination of p-nitrophenol (p-NP). The La(OH)3-OxMWCNTs nanocomposite with an interpenetrating networks structure was characterized by field emission electron microscope (FE-SEM), Fourier transform infrared (FT-IR) spectroscopy, Raman spectra and X-ray photoelectron spectroscopy (XPS). The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements were performed to study the electrochemical behaviors of La(OH)3-OxMWCNTs modified glassy carbon electrode (La(OH)3-OxMWCNTs/GCE). The La(OH)3-OxMWCNTs/GCE was used for sensitive determination of p-NP by CV and linear sweep voltammetry (LSV). Under the optimum conditions, the peak currents of LSV versus the concentrations of p-NP in the range 1.0-30.0 µmol L-1 showed a good linear relationship (R2=0.9971), and the limit of detection (LOD) was calculated to be 0.27 µmol L-1 (signal-to-noise ratio of 3, S/N=3). The recoveries of p-NP in real samples of industrial wastewater and Xiangjiang water at La(OH)3-OxMWCNTs/GCE were in the range of 95.62-110.75% with relative standard deviation (RSD) in the range of 1.65-3.85%. The intra-day and inter-day precisions were estimated to be less than 2.76% (n= 5), indicating that La(OH)3-OxMWCNTs/GCE possessed highly stability. In addition, La(OH)3-OxMWCNTs/GCE sensor showed good anti-interference ability for determination of p-NP in aqueous mixtures containing high concentrations of inorganic and organic interferents, and a decrease of oxidation peak currents by less than 3.57% relative to the initial levels indicated it possessed excellent selectivity. Therefore, La(OH)3-OxMWCNTs/GCE could be used as a fast, selective and sensitive electrochemical sensor platform for the selective determination and quantification of aqueous p-NP.


Assuntos
Técnicas Eletroquímicas/métodos , Lantânio/química , Nanocompostos/química , Nanotubos de Carbono/química , Nitrofenóis/análise , Eletrodos , Limite de Detecção , Oxirredução
11.
Ecotoxicol Environ Saf ; 201: 110872, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32559693

RESUMO

Based on a hybrid carbon nanotube composite, a novel electrochemical sensor with high sensitivity and selectivity was designed for the simultaneous determination of dopamine (DA) and uric acid (UA). The hybrid carbon nanotube composite was prepared by ultrasonic assembly of carboxylated multi-walled carbon nanotube (MWCNT-COOH) and hydroxylated single-walled carbon nanotube (SWCNT-OH). And the hybrid (MWCNT-COOH/SWCNT-OH) composite was characterized by field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared (FT-IR) spectroscopy. The electrochemical performances of MWCNT-COOH/SWCNT-OH composite modified glassy carbon electrode (MWCNT-COOH/SWCNT-OH/GCE) were analyzed by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). Under the optimum experimental conditions, the as-prepared sensor showed high sensitivity and selectivity for DA and UA. The calibration curves obtained were linear for the currents versus DA and UA concentrations in the range 2-150 µM, and limits of detection (LODs) were calculated to be 0.37 µM and 0.61 µM (signal-to-noise ratio of 3, S/N = 3), respectively. The recoveries of DA and UA in bovine serum samples at MWCNT-COOH/SWCNT-OH/GCE were in the range 96.18-105.02%, and relative standard deviations (RSDs) were 3.34-7.27%. The proposed electrochemical sensor showed good anti-interference ability, excellent reproducibility and stability, as well as high selectivity, which might provide a promising platform for determination of DA and UA.


Assuntos
Dopamina/análise , Técnicas Eletroquímicas/métodos , Nanotubos de Carbono/química , Ácido Úrico/análise , Animais , Carbono , Bovinos , Dopamina/sangue , Eletrodos , Limite de Detecção , Nanotubos de Carbono/ultraestrutura , Reprodutibilidade dos Testes , Ácido Úrico/sangue
12.
Ecotoxicol Environ Saf ; 190: 110123, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31891837

RESUMO

In this work, a novel manganese dioxide-graphene nanosheets (MnO2-GNSs) composite was synthesized by a facile one-step hydrothermal method, in which manganese dioxide (MnO2) was fabricated by hydrothermal reduction of KMnO4 with GNSs. The structure and morphology of MnO2-GNSs composite were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) analysis and X-ray photoelectron spectroscopy (XPS). A sensitive non-enzymatic electrochemical sensor based on MnO2-GNSs composite for the detection of low concentration hydrogen peroxide (H2O2) was fabricated. The electrochemical properties of MnO2-GNSs composite modified glassy carbon electrode (MnO2-GNSs/GCE) were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and amperometry. The observations confirmed that the fabricated sensor exhibited high electrocatalytic activity for oxidation of H2O2 owing to the catalytic ability of MnO2 particles and the conductivity of GNSs. Under the optimum conditions, the calibration curve was linear for the amperometric response versus H2O2 concentration over the range 0.5-350 µM with a low detection limit of 0.19 µM (S/N = 3) and high sensitivity of 422.10 µA mM-1 cm-2. The determination and quantitative analysis of H2O2 in antiseptic solution on MnO2-GNSs/GCE exhibited percent recovery of 96.50%-101.22% with relative standard deviation (RSD) of 1.48%-4.47%. The developed MnO2-GNSs/GCE might be a promising platform for the practical detection of H2O2 due to its prominent properties including excellent reproducibility, good anti-interference and repeatability.


Assuntos
Técnicas Eletroquímicas/métodos , Grafite/química , Peróxido de Hidrogênio/análise , Compostos de Manganês/química , Modelos Químicos , Óxidos/química , Carbono/química , Catálise , Espectroscopia Dielétrica , Eletrodos , Limite de Detecção , Reprodutibilidade dos Testes
13.
Mikrochim Acta ; 187(11): 636, 2020 11 03.
Artigo em Inglês | MEDLINE | ID: mdl-33141322

RESUMO

A novel chiral sensing platform, 6-O-α-maltosyl-ß-cyclodextrin (Mal-ßCD)-based film, is proposed for selective electrochemical recognition of tyrosine (Tyr) enantiomers. Black phosphorus nanosheets (BP NSs) and Mal-ßCD modified glassy carbon electrode (Mal-ßCD/BP NSs/GCE) were prepared by a layer-to-layer drop-casting method, and the platform was easy to fabricate and facile to operate. It is proposed that the amino and hydroxyl groups of the Tyr enantiomers and the chiral hydroxyl groups of Mal-ßCD selectively form intermolecular hydrogen bonds to dominate effective chiral recognition. Two linear equations of Ip (µA) = 11.40 CL-Tyr (mM) + 0.28 (R2 = 0.99147) and Ip (µA) = 7.96 CD-Tyr (mM) + 0.22 (R2 = 0.99583) in the concentration range 0.01-1.00 mM have been obtained. The limits of detection (S/N=3) for L-Tyr and D-Tyr were 4.81 and 6.89 µM, respectively. An interesting phenomenon was that the value of IL-Tyr/ID-Tyr (1.51) in this work was slightly higher than the value of IL-Trp/ID-Trp (1.49) reported in our previous study, where tryptophan (Trp) enantiomers were electrochemically recognized by Nafion (NF)-stabilized BPNSs-G2-ß-CD composite. The two similar sensors fabricated by different methods showed different recognition ability toward either Tyr or Trp enantiomers, and the underlying mechanism was discussed in detail. More importantly, the proposed chiral sensor enables prediction of the percentages of D-Tyr in racemic Tyr mixtures. The chiral sensor may provide a novel approach for the fabrication of novel chiral platforms in the practical detection of L- or D-enantiomer in racemic Tyr mixtures.Graphical abstract.


Assuntos
Nanoestruturas/química , Fósforo/química , Tirosina/química , beta-Ciclodextrinas/química , Técnicas Eletroquímicas/métodos , Limite de Detecção , Estereoisomerismo
14.
Ecotoxicol Environ Saf ; 176: 11-19, 2019 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-30909000

RESUMO

Three-dimensional (3D) porous graphene oxide-maize amylopectin (GO-MA) composites with controllable pore-sizes composites in the range of 6-40 nm were prepared by facile hydrothermal-assisted assembly approaches. The morphologies, pore sizes, specific surface area (SSA) and compositions of GO-MAx:y composites with and different GO-to-MA mass ratios (x:y) were characterized by scanning electron microscopy (SEM), N2 adsorption-desorption isotherms, Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). To reveal the adsorption-desorption mechanism, effects of contact time, temperature, initial adsorbate concentration, pH value of the solution on the adsorption process were studied in detail. The adsorption capacities of 3D GO-MA20:1 composite for organic contaminants including tert-butyl hydroquinone (TBHQ), p-aminophenol (PAP), p-nitrophenol (PNP), o-nitrophenol (MNP), hydroquinone (HQ), alizarin red S (ARS) and neutral red (NR) were 22.17, 116.4, 44.78, 36.96, 16.10, 39.92 and 24.23 mg g-1, respectively. The adsorption capacities of GO-MA30:1 composite for inorganic substances including Pb2+, Mn2+, Cr2O72-, Cd2+, Cu2+, Nd3+, La3+, Y3+, Yb3+ and Er3+ were 84.76, 7.92, 13.6, 17.64, 30.56, 25.52, 12.48, 16.96, 23.32 and 30.32 mg g-1, respectively. In addition, GO-MAx:y composites also exhibited high mechanical properties and good reusability. Consequently, GO-MAx:y composites could be used as reusable adsorbents for removal/enrichment inorganic/organic substances in aqueous solutions.


Assuntos
Amilopectina/química , Grafite/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Amilopectina/isolamento & purificação , Compostos Orgânicos , Óxidos/química , Espectroscopia Fotoeletrônica , Porosidade , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Água/química , Poluentes Químicos da Água/química , Zea mays/química
15.
Ecotoxicol Environ Saf ; 172: 167-175, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-30708228

RESUMO

In this study, platinum nanochains (PtNCs), multi-walled carbon nanotubes (MWCNTs) and graphene nanoparticles (GNPs) were assembled together to form a novel nanocomposite by a facile ultrasonic-assisted blending process. The PtNCs-MWCNTs-GNPs nanocomposite was characterized by high resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The nanocomposite was used for the modification of glass carbon electrode (GCE) and simultaneous determination of dopamine (DA) and ascorbic acid (AA) by differential pulse voltammetry (DPV) and cycle voltammetry (CV). Under the optimum conditions, the calibration curves obtained are linear for the currents versus DA and AA concentrations over the range 2.00-50.0 µM and 100-1200 µM, respectively. And the detection limits for DA and AA are 0.500 µM and 10.0 µM, respectively. The detection and quantitative analysis of DA and AA in human serum and vitamin C tablets on PtNCs-MWCNTs-GNPs/GCE gave the recoveries of 104-110% and 101-108% with relative standard deviations (RSD) of 4.36-7.48% and 0.620-2.90%, respectively. The proposed PtNCs-MWCNTs-GNPs composite could provide a new platform for the routine analysis of DA and AA in terms of its good anti-interference ability, excellent reproducibility and repeatability, and feasibility of use.


Assuntos
Ácido Ascórbico/análise , Dopamina/análise , Platina/química , Ácido Ascórbico/sangue , Técnicas Biossensoriais , Dopamina/sangue , Técnicas Eletroquímicas , Eletrodos , Grafite/química , Humanos , Limite de Detecção , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Nanocompostos/química , Nanopartículas/química , Nanotubos de Carbono/química , Reprodutibilidade dos Testes
16.
Sensors (Basel) ; 19(18)2019 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-31500196

RESUMO

Most existing person re-identification methods focus on matching still person images across non-overlapping camera views. Despite their excellent performance in some circumstances, these methods still suffer from occlusion and the changes of pose, viewpoint or lighting. Video-based re-id is a natural way to overcome these problems, by exploiting space-time information from videos. One of the most challenging problems in video-based person re-identification is temporal alignment, in addition to spatial alignment. To address the problem, we propose an effective superpixel-based temporally aligned representation for video-based person re-identification, which represents a video sequence only using one walking cycle. Particularly, we first build a candidate set of walking cycles by extracting motion information at superpixel level, which is more robust than that at the pixel level. Then, from the candidate set, we propose an effective criterion to select the walking cycle most matching the intrinsic periodicity property of walking persons. Finally, we propose a temporally aligned pooling scheme to describe the video data in the selected walking cycle. In addition, to characterize the individual still images in the cycle, we propose a superpixel-based representation to improve spatial alignment. Extensive experimental results on three public datasets demonstrate the effectiveness of the proposed method compared with the state-of-the-art approaches.

17.
Ecotoxicol Environ Saf ; 166: 1-10, 2018 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-30240929

RESUMO

Graphene oxide (GO) nanosheets were immobilized and cross-linked by high-gluten flour (HGF), and a series of biomass-GO composites with various HGF-to-GO mass ratios were fabricated through a one-step hydrothermal method. The HGF-GO composites were used as novel adsorbents to adsorb rare earth ions (REE3+: La3+, Yb3+, Y3+, Er3+ and Nd3+) from aqueous solutions, and their adsorption properties were also investigated detailly. To evaluate the physicochemical properties of HGF-GO composites and further understand the mechanisms of adsorption of REE3+ onto HGF-GO composites, the HGF-GO composites were characterized by scanning electron microscopy (SEM), thermal gravimetric analyzer (TGA), Raman spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. Several important condition parameters including contact time, initial REE3+concentrations, solution pH values and temperature that might affect the adsorption process were studied in detail. The maximum adsorption capacities of HGF-GO1:1 composite toward La3+, Yb3+, Y3+, Er3+ and Nd3+ were 30.32, 36.64, 32.84, 42.36 and 48.68 mg g-1, respectively. The experimental data indicated that the adsorption of REE3+ onto HGF-GO1:1 was well fitted by the pseudo-second order kinetic model and the Langmuir isotherm model, and the adsorption process was a spontaneous and endothermic reaction. The HGF-GO1:1 composite could be well regenerated and reused after five adsorption-desorption cycles, and its removal efficiency for Yb3+ remained as a constant of 100%.


Assuntos
Glutens/química , Óxidos/química , Adsorção , Farinha , Grafite/química , Concentração de Íons de Hidrogênio , Íons/química , Cinética , Metais Terras Raras , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Poluentes Químicos da Água/análise , Purificação da Água/métodos
18.
J Opt Soc Am A Opt Image Sci Vis ; 33(3): 404-15, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26974910

RESUMO

Salient object detection is very useful in a large variety of image and vision-related applications. A recent trend in salient object detection is to explore novel top-down visual cues and combine them with bottom-up saliency to improve the performance. However, a basic and important problem, i.e., how to effectively fuse multiple visual cues, has rarely been addressed in previous works. To this end, the paper presents a multicue fusion method using the cross-diffusion process (CDP) for salient object detection. The CDP algorithm is deployed to combine the affinity matrices constructed over individual visual cue channels, which is then embedded into a saliency propagation framework to accomplish salient object detection. Different from other multicue fusion strategies, our proposed approach allows for collaborative fusion, that is, the individual visual cues to be fused are able to interact and exchange information with each other during the fusion procedure, which can possibly correct the noise or corruption included in the individual visual cue channels, leading to more robust and effective fusion results. Intensive experiments on publicly available datasets demonstrate the effectiveness and superior performance of our proposed method.

19.
J Opt Soc Am A Opt Image Sci Vis ; 33(7): 1313-22, 2016 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-27409688

RESUMO

In this paper, we propose a novel formulation for building pixelwise alignments between remote sensing images under nonrigid transformation based on matching both sparsely and densely sampled features. Our formulation contains two coupling variables: the nonrigid geometric transformation and the discrete dense flow field. To match sparse features, we fit a geometric transformation specified in a reproducing kernel Hilbert space and impose a locally linear constraint to regularize the transformation. To match dense features, we compute a dense flow field by using a formulation analogous to scale invariant feature transform (SIFT) flow which allows nonrigid matching across different scene appearances. An additional term is introduced to ensure the coherence between the two variables, and we alternatively solve for one variable under the assumption that the other is known. Extensive experiments on both synthetic and real remote sensing images demonstrate that our approach greatly outperforms state-of-the-art methods, particularly when the data contain severe degradations.

20.
J Opt Soc Am A Opt Image Sci Vis ; 33(5): 887-98, 2016 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-27140886

RESUMO

Salient object detection has been a rather hot research topic recently, due to its potential applications in image compression, scene classification, image registration, and so forth. The overwhelming majority of existing computational models are designed based on computer vision techniques by using lots of image cues and priors. Actually, salient object detection is derived from the biological perceptual mechanism, and biological evidence shows that the spread of the spatial attention generates the object attention. Inspired by this, we attempt to utilize the emerging spread mechanism of object attention to construct a new computational model. A novel Cauchy graph embedding based diffusion (CGED) model is proposed to fulfill the spread process. Combining the diffusion model and attention prediction model, a salient object detection approach is presented through perceptually grouping the multiscale diffused attention maps. The effectiveness of the proposed approach is validated on the salient object dataset. The experimental results show that the CGED process can obviously improve the performance of salient object detection compared with the input spatial attention map, and the proposed approach can achieve performance comparable to that of state-of-the-art approaches.


Assuntos
Diagnóstico por Imagem/métodos , Reconhecimento Automatizado de Padrão/métodos , Algoritmos , Animais , Simulação por Computador , Difusão , Humanos , Processamento de Imagem Assistida por Computador/métodos , Informática Médica , Modelos Estatísticos , Óptica e Fotônica
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