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1.
J Colloid Interface Sci ; 576: 109-118, 2020 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-32408160

RESUMO

In this study, a hyperbranched chelated hydrophilic swollen-layer was constructed on the surface of polyacrylonitrile (PAN) fiber with amino trimethylene phosphoric acid (ATMP) as a terminal group, which applied as an adsorbent for seawater uranium U(VI) extraction. This shows that U(VI) enter the gel-like swollen-layer to form a more complex body structure. The molecular chain conformational extension in the swollen-layer reduces the resistance of the uranyl ion to enter the swollen-layer, which is conducive to the adsorption behavior. The adsorption performance on the U(VI) by the adsorption experiment were found to be consistent with the Langmuir isotherm adsorption model and the pseudo-second-order kinetics, indicating that the adsorption of U(VI) by this material is uniform single-layer chemical adsorption. Ion competition experiments and cyclic adsorption experiments verify the practical application potential of the materials. In the dynamic simulation of seawater adsorption experiments, the adsorption capacity of the adsorbent reached 7.4 mg/g. Studies on the adsorption mechanism have found that a large number of hydroxyl groups in the swollen-layer and ATMP as an end machine have a chelation effect on U(VI).

2.
J Colloid Interface Sci ; 574: 355-363, 2020 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-32339818

RESUMO

The urgent demands of energy storage for wearable electronics necessitates the development of flexible supercapacitors (FSCs). However, the service environment of portable/wearable devices requires supercapacitors to possess excellent mechanical properties to withstand harsh straining conditions, such as bending, rolling, and twisting. Hence, to develop a high-performance flexible supercapacitor (FSC) that possesses both superior electrochemical properties and remarkable mechanical capacities is still a formidable challenge. In this paper, we successfully fabricate a 3D heterostructured electrode with bulge structured polypyrrole (PPy) wrapped NiMoO4 nanowires on carbon cloth (CC). Benefiting from the 3D heterostructure and the synergistic effect between NiMoO4 and PPy, the PPy/NiMoO4/CC electrode shows a high areal capacitance of 3.4 F cm-2 and cyclic stability (94% capacitance retention). Moreover, the assembled PPy/NiMoO4/CC//activated carbon (AC)/CC device exhibits a high energy density (0.5 mW cm-2 at a power density of 3.7 mWh cm-2). Furthermore, the CV curves of PPy/NiMoO4/CC//AC/CC show no obvious change under miscellaneous deformation conditions, indicating good flexibility. This work demonstrates that the assembled PPy/NiMoO4/CC//AC/CC FSC possesses notable electrochemical properties and exhibits great potential for application in future wearable energy-storage devices.

3.
J Microbiol Methods ; 173: 105934, 2020 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-32325159

RESUMO

Biological fouling has caused a lot of concern in marine industries due to the attachment of microorganisms on marine surfaces. Silver nanoparticles (AgNPs) have a great potential to inhibit and hold strong toxicity against microorganisms on artificial surfaces immersed in seawater. In this study, AgNPs are synthesized using extract of clove buds (CE) plant as a reducing and stabilizing agent by biological synthesis method. The obtained CE-AgNPs product was characterized by using different techniques. Ultraviolet-visible spectroscopy (UV-Vis) results confirmed the formation of CE-AgNPs with its surface plasmon resonance peak range. Fourier-transform infrared spectroscopy (FTIR) study showed the formation of functional groups responsible for the reduction of Ag+ into Ago. X-Ray Diffraction (XRD) results revealed face-centered cubic (fcc) silver crystals having four different diffraction peaks at 38.08, 44.21, 64.42 and 77.32 with corresponding lattice plane value recorded at (111), (200), (220) and (311), respectively. Structural characterization using scanning electron microscopy equipped with energy dispersive X-Ray Analyzer (SEM-EDX), Transmission electron microscopy (TEM) and atomic force microscopy (AFM) also confirmed the successful formation of CE-AgNPs with fcc structure. The histogram of particle size distribution through TEM image showed an average size of 9.42 nm of the synthesized product. Finally, the antibacterial and antidiatom activity of the synthesized product was analyzed. The CE-AgNPs synthesized using CE possesses good inhibitory activity against the marine bacterium community and Nitzschia closterium diatom. These results indicate that CE-AgNPs can be used as a novel material for antibacterial and antidiatoms means to inhibit the biofouling on marine surfaces.

4.
BMC Nephrol ; 21(1): 95, 2020 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-32160882

RESUMO

BACKGROUND: Acute kidney injury (AKI) is a common complication among human immunodeficiency virus (HIV)-infected patients resulting in increased morbidity and mortality. Continuous renal replacement therapy (CRRT) is a useful method and instrument in critically ill patients with fluid overload and metabolic disarray, especially in those who are unable to tolerate the intermittent hemodialysis. However, the epidemiology, influence factors of CRRT and mortality in patients with HIV/AIDS are still unclear in China. This study aims to study the HIV-infected patients admitted in Intensive Care Unit (ICU) and explore the influence factors correlated with CRRT and their prognosis. METHODS: We performed a retrospective case-control study in the ICU of the Beijing Ditan Hospital Capital Medical University. From June 1, 2005 to May 31, 2017, 225 cases were enrolled in this clinical study. RESULTS: 122 (54.2%) patients were diagnosed with AKI during their stay in ICU, the number and percentage of AKI stage 1, 2 and 3 were 38 (31.1%), 21(17.2%) and 63(51.7%), respectively. 26.2% of AKI patients received CRRT during the stay of ICU. 56.25% CRRT patients died in ICU. The 28-day mortality was 62.5%, and the 90-day mortality was 75%. By univariate logistics analysis, it showed that higher likelihood of diagnosis for respiratory failure (OR = 7.333,95% CI 1.467-36.664, p = 0.015), higher likelihood of diagnosis for septic shock (OR = 1.005,95% CI 1.001-1.01, p = 0.018), and higher likelihood to use vasoactive agents (OR = 10.667,95% CI 1.743-65.271, p = 0.001), longer mechanical ventilation duration (OR = 1.011,95% CI 1.002-1.019, p = 0.011), higher likelihood for diagnosis for PCP (OR = 7.50,95% CI 1.288-43.687, p = 0.025), higher SOFA score at ICU admission (OR = 1.183,95% CI 1.012-1.383, p = 0.035), longer duration of CRRT (OR = 1.014,95% CI 1.001-1.028, p = 0.034) contributed to a higher mortality at ICU. The Cox Analysis for the cumulative survival of AKI 3 patients between the CRRT and non-CRRT groups shows no significant differences (p = 0.595). CONCLUSIONS: There is a high incidence of AKI in HIV-infected patients admitted in our ICU. Patients with severe AKI were more prone to be admitted for CRRT and have a consequent poor prognosis.

5.
Cell Mol Biol Lett ; 25: 12, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32161621

RESUMO

Background: MicroRNA-125b (miR-125b) is downregulated in human cutaneous squamous cell carcinoma (CSCC). However, its function in CSCC has yet to be extensively explored. Here, we analyze the relationship between signal transducer and activator of transcription 3 (STAT3) and miR-125b in CSCC. Methods: Western blotting and quantitative RT-PCR were used to determine the expression of the miR-125b-STAT3 axis in human CSCC tissues and cell lines. The direct regulatory effect of miR-125b on STAT3 expression was assessed using a luciferase reporter gene assay and RNA immunoprecipitation assay. The MTT assay and flow cytometry were used to determine the role of the miR-125b-STAT3 axis in CSCC cell proliferation and apoptosis. Results: MiR-125b expression levels were significantly lower in CSCC cell lines and tissues than in normal cell lines and tissues. STAT3 was identified as the direct target of miR-125b. Upregulation of miR-125b and downregulation of STAT3 suppressed cell proliferation and promoted cell apoptosis. Cyclin D1 and Bcl2 were identified as the downstream targets of the miR-125-STAT3 axis. Conclusions: Our findings indicate that miR-125b acts as a tumor suppressor in CSCC by targeting the STAT3 pathway. This observation increases our understanding of the molecular mechanisms of CSCC. Therapies aimed at activating miR-125b or inhibiting STAT3 signaling should be explored as potential treatments for CSCC.

6.
Artigo em Inglês | MEDLINE | ID: mdl-32202404

RESUMO

Metal-organic frameworks (MOFs) are diffusely defined as a promising class of porous material for uranium extraction from seawater, but there are still challenges in their stability and anti-biofouling performance. Herein, a water-stable and anti-biofouling ZIF-67/SAP0.45 composite hydrogel was reported by the sequential processes of electrostatic interactions between the oppositely charged polymer, ionic gelation, and template growth of ZIF-67 crystals. Entanglement of positively charged polyethyleneimine (PEI) and negatively charged sodium alginate (SA) polymer chains provided external porosities, anti-biofouling properties, and mechanical support for the hydrogels and further reduced the possibility of ZIF-67 aggregation. The neutral composite hydrogel possessed the least Nitzschia on the surface after 7 days contact, which endows the adsorbent with a high uranium uptake capacity of 2107.87 ± 41.64 µg g-1 at 1 mg L-1 uranium-containing seawater with 8.6 × 105 mL-1 Nitzschia. Additionally, this adsorbent showed water stability with an uranium uptake capacity of 232.88 ± 8.02 mg g-1 even after five adsorption-desorption cycles because of the excellent preparation method. Benefitting from the distinctive hierarchical structure and large accessible surface area, the resultant adsorbent achieved a high uranium capacity of 6.99 ± 0.26 mg g-1 in real seawater. This flexible and scalable approach made the MOF/SAP composite hydrogel a highly desirable uranium adsorbent.

7.
Eur Radiol ; 30(5): 3023-3033, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32006174

RESUMO

OBJECTIVES: To develop a dual-modal neural network model to characterize ultrasound (US) images of breast masses. MATERIALS AND METHODS: A combined US B-mode and color Doppler neural network model was developed to classify US images of the breast. Three datasets with breast masses were originally detected and interpreted by 20 experienced radiologists according to Breast Imaging-Reporting and Data System (BI-RADS) lexicon ((1) training set, 103212 masses from 45,433 + 12,519 patients. (2) held-out validation set, 2748 masses from 1197 + 395 patients. (3) test set, 605 masses from 337 + 78 patients). The neural network was first trained on training set. Then, the trained model was tested on a held-out validation set to evaluate agreement on BI-RADS category between the model and the radiologists. In addition, the model and a reader study of 10 radiologists were applied to the test set with biopsy-proven results. To evaluate the performance of the model in benign or malignant classifications, the receiver operating characteristic curve, sensitivities, and specificities were compared. RESULTS: The trained dual-modal model showed favorable agreement with the assessment performed by the radiologists (κ = 0.73; 95% confidence interval, 0.71-0.75) in classifying breast masses into four BI-RADS categories in the validation set. For the binary categorization of benign or malignant breast masses in the test set, the dual-modal model achieved the area under the ROC curve (AUC) of 0.982, while the readers scored an AUC of 0.948 in terms of the ROC convex hull. CONCLUSION: The dual-modal model can be used to assess breast masses at a level comparable to that of an experienced radiologist. KEY POINTS: • A neural network model based on ultrasonic imaging can classify breast masses into different Breast Imaging-Reporting and Data System categories according to the probability of malignancy. • A combined ultrasonic B-mode and color Doppler neural network model achieved a high level of agreement with the readings of an experienced radiologist and has the potential to automate the routine characterization of breast masses.

8.
Talanta ; 209: 120515, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31892070

RESUMO

Ionic liquids are promising electrolytes for electrochemical gas sensors that have unique physicochemical properties such as negligible vapor pressure and high thermal stability. The modification of ionic liquid (IL) by combining metal oxide with reduced graphene oxide (rGO) is an effective method to improve its gas-sensing properties. In this study, the mesoporous structure of NiCo2O4/rGO is synthesized by simple one-step method, and the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) is mixed with it to form the composite material NiCo2O4/rGO/[BMIM][PF6]. Electrochemical test results indicate that the three electrolytes exhibit response current and long-term stability in the oxygen environment. The oxygen sensor based on NiCo2O4/rGO/[BMIM][PF6] significantly improves the response current and working stability of pure ionic liquid. The sensitivity of the sensor is 0.1087 µA/[%O2], and the linear regression coefficient of the reduction peak current calibration curve is 0.9995. After continuous cyclic voltammetry, the reduction peak current remains at 90% of the initial current value. The interaction of IL and NiCo2O4/rGO significantly enhances electrochemical oxygen sensing performance.

9.
Cell Prolif ; 53(1): e12670, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31568631

RESUMO

OBJECTIVES: To investigate the heterogeneous feature of actin filaments (ACFs) associated with the cellular membrane in HeLa and HCT-116 cells at the nanoscale level. MATERIALS AND METHODS: Fluorescence microscopy coupled with atomic force microscopy (AFM) was used to identify and characterize ACFs of cells. The distribution of ACFs was detected by Fluor-488-phalloidin-labelled actin. The morphology of the ACFs was probed by AFM images. The spatial correlation of the microvilli and ACFs was explored with different forces of AFM loading on cells. RESULTS: Intricate but ordered structures of the actin cytoskeletons associated with cellular membrane were characterized and revealed. Two different layers of ACFs with distinct structural organizations were directly observed in HCT-116 and HeLa cells. Bundle-shaped ACFs protruding the cellular membrane forming the microvilli, and the network ACFs underneath the cellular membrane were resolved with high resolution under near-physiological conditions. Approximately 14 nm lateral resolution was achieved when imaging single ACF beneath the cellular membrane. On the basis of the observed spatial distribution of the ultrastructure of the ACF organization, a model for this organization of ACFs was proposed. CONCLUSIONS: We revealed the two layers of the ACF organization in Hela and HCT-116 cells. The resolved heterogeneous structures at the nanoscale level provide a spatial view of the ACFs, which would contribute to the understanding of the essential biological functions of the actin cytoskeleton.


Assuntos
Citoesqueleto de Actina/metabolismo , Citoesqueleto de Actina/ultraestrutura , Microscopia de Força Atômica , Coloração e Rotulagem , Células HCT116 , Células HeLa , Humanos
10.
Talanta ; 208: 120452, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31816737

RESUMO

Plant cell walls represent enormous biomass resources for biofuels, and it thus becomes important to establish a sensitive and wide-applicable approach to visualize wall polymer distribution and destruction during plant growth and biomass process. Despite quantum dots (QDs) have been applied to label biological specimens, little is reported about its application in plant cell walls. Here, semiconductor QDs (CdSe/ZnS) were employed to label the secondary antibody directed to the epitopes of pectin or xylan, and sorted out the optimal conditions for visualizing two polysaccharides distribution in cell walls of rice stem. Meanwhile, the established QDs approach could simultaneously highlight wall polysaccharides and lignin co-localization in different cell types. Notably, this work demonstrated that the QDs labeling was sensitive to profile distinctive wall polymer destruction between alkali and acid pretreatments with stem tissues of rice. Hence, this study has provided a powerful tool to characterize wall polymer functions in plant growth and development in vivo, as well as their distinct roles during biomass process in vitro.

11.
J Hazard Mater ; 389: 121854, 2020 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-31848090

RESUMO

Herein, several novel composite films consisting of three-dimensional (3D) Bi5O7I flower-like shaped microsphere and zwitterionic fluorinated polymer (ZFP) were successfully fabricated with the aim of achieving high anti-fouling performance. The prepared Bi5O7I flower-like shaped microsphere particles with diameters in the range of 2∼3 µm were uniformly distributed on the surface and in the internal of ZFP. Benefiting from the hydration layer formed by the ZFP and the efficient photocatalytic performance of Bi5O7I flower-like microsphere, the resultant optimized Bi5O7I/ZFP composite film exhibited an excellent diatom anti-settling performance and a high antibacterial rate of 99.09% and 99.66% towards Escherichia coli and Staphylococcus aureus. In addition, the composite films possessed the strengthened visible light absorption, the effectively separation and transfer of the photo-induced electrons and holes, the large number of hydroxyl (OH) radicals and superoxide radicals (O2-) all in Bi5O7I/ZFP systems, all of which were beneficial for the photocatalytic antifouling activity. More importantly, the synergistic hydration-photocatalytic effect of the Bi5O7I/ZFP composite films are answerable for the improvement of the antifouling property compared to the control. Thus, the synergistic hydration-photocatalytic contribution of Bi5O7I/ZFP composite film will shows promise for potential application in marine antifouling.

12.
Chemosphere ; 239: 124793, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31726530

RESUMO

Developing an efficient and environmentally friendly strategy for oil-water separation is extremely important for practical application. In this study, a superhydrophobic and superoleophilic melamine sponge loaded with cross-linked and swellable polydivinylbenzene was successfully fabricated by a facile and effective one-step impregnation-curing method with adhesion of polydimethylsiloxane. The prepared sponge not only exhibited high oil absorption capacity, but it also enabled rapid oil collection in situ, which could be extended to practical application. Moreover, the modified superhydrophobic sponge showed excellent mechanical resistance and chemical stability. The surface morphology and chemical composition were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. This material has great development potential for large-scale oil spill clean-up and chemical spill accidents.


Assuntos
Dimetilpolisiloxanos/química , Recuperação e Remediação Ambiental/métodos , Óleos/química , Poluição por Petróleo/análise , Polivinil/química , Triazinas/química , Interações Hidrofóbicas e Hidrofílicas , Microscopia Eletrônica de Varredura , Nanoporos , Espectroscopia Fotoeletrônica , Polímeros/química , Água/química
13.
J Hazard Mater ; 381: 120984, 2020 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-31430638

RESUMO

A major challenge of uranium extraction from seawater (UES) is to effectively block the biofouling without destroying the ecological balance, especially prevent the attachment of macroalgae on the surface of the adsorbent. Herein, a robust montmorillonite-polydopamine/polyacrylamide nanocomposite hydrogel is reported by a two-step method, including PDA intercalation MMT and further free radical polymerization with AM monomers. The interpenetrating structure of hydrogel lead to high water permeability with the swelling ratio of 51, which could fully facilitate the internal accessible sites exposure and increase the uranium diffusion. As a result, a high adsorption capacity of 44 mg g-1 was achieved in lab-scale dynamic adsorption. Most importantly, the prepared anti-biofouling hydrogel adsorbents display excellent anti-adhesion ability towards Nitzschia after 8 days contact. The adsorption capacity of uranium can reach 2130 µg g-1 in algae-contained simulated seawater. This hydrogel also exhibited a long service life of acceptable mechanical strength and adsorption capacity after at least 6 adsorption-desorption cycles. This new anti-biofouling nanocomposite hydrogel shows great potential as a new generation adsorbent for UES.

14.
Nanomaterials (Basel) ; 9(12)2019 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-31795244

RESUMO

Nanocellulose (NC) has attracted attention in recent years for the advantages offered by its unique characteristics. In this study, the effects of the preparation method on the properties of starch films were investigated by preparing NC from cationic-modified microcrystalline cellulose (MD-MCC) using three methods: Acid hydrolysis (AH), high-pressure homogenization (HH), and high-intensity ultrasonication (US). When MD-MCC was used as the starting material, the yield of NC dramatically increased compared to the NC yield obtained from unmodified MCC and the increased zeta potential improved its suspension stability in water. The NC prepared by the different methods had a range of particle sizes and exhibited needle-like structures with high aspect ratios. Fourier transform infrared (FTIR) spectra indicated that trimethyl quaternary ammonium salt groups were introduced to the cellulose backbone during etherification. AH-NC had a much lower maximum decomposition temperature (Tmax) than HH-NC or US-NC. The starch/HH-NC film exhibited the best water vapor barrier properties because the HH-NC particles were well-dispersed in the starch matrix, as demonstrated by the surface morphology of the film. Our results suggest that cationic NC is a promising reinforcing agent for the development of starch-based biodegradable food-packaging materials.

15.
Materials (Basel) ; 12(24)2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31835697

RESUMO

In this study, two types of antibacterial montmorillonites (Mt) were prepared using a facile method. The Mt modified with ε-polylysine hydrochloride (ε-PL) was named PL-Mt, while the Mt dually modified with dioctadecyl dimethylammonium chloride (D1821) and ε-PL was named PL-OMt. The results of the X-ray diffraction, Fourier-transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA) of the PL-Mt indicated that 30% ε-PL was the most suitable amount for intercalating the Mt. The particle size and distribution of the ε-PL in the solution demonstrated that the Mt d-value could not be further increased owing to the increasing ε-PL diameter. The result of the X-ray diffraction of PL-OMt displayed that ultrasonic treatment at 600 W facilitated ε-PL to intercalate into the OMt interlayer space. The PL-OMt prepared with ultrasonic treatment at 600 W exhibited antibacterial activity against Escherichia coli and Bacillus subtilis superior to that of the PL-OMt prepared with higher-power ultrasonic treatment. Thus, the addition of 30% ε-PL based on the dry Mt mass is the most suitable ratio for preparing PL-Mt, while ultrasonic treatment at 600 W is the most suitable for preparing PL-OMt. These findings may expand the application fields of ε-PL.

16.
Stat Med ; 38(29): 5497-5511, 2019 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-31631355

RESUMO

Many treatments and drugs are intended to reduce the occurrence of negative events of interest, control the severity of the events, accelerate recovery from the events, or a combination of these effects. While assessing the clinical effect is typically the primary objective of a trial, testing the treatment effect on the health status of patients based on patient reported outcome (PRO) can be a useful component in determining the value of a treatment. Analysis of PROs in this setting, however, face the following challenges: the PRO value immediately after the event occurrence is often not captured, and the effect of the event on health status measured by the PRO is transient as subjects recover over time. Therefore, traditional statistical methods used to assess treatment effects suffer from low power for PROs. In this manuscript, we apply a kernel smoothing technique to estimate before- and after-event PRO values. We also propose new test outcomes based on observed and estimated PRO values and evaluate tests that focus on the tail distributions. We demonstrate that the tail distribution tests using the new outcomes can achieve high power under certain conditions.

17.
ACS Appl Mater Interfaces ; 11(46): 43681-43688, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31645098

RESUMO

Although strategies for smart control of droplets by utilizing slippery surfaces that are typically made by infusing lubricants into porous surfaces are booming, no surface can smartly control the start or stop of droplet sliding without external environmental stimuli. A strategy for how surfaces alone, if constituted by lubricant-infused porous hydrophobic sticky surfaces (LIPHSS) with a specific interface self-adjusting system, can achieve the target of smart control of a drop's slide is presented here. The continuous self-adjustment of the interface formed by droplets and LIPHSS leads to the occurrence of droplet sinking behavior. The droplet's sinking reduces its sliding angle (SA) and thus can trigger the sliding of the droplet deposited on LIPHSS with a tilt base angle between the SA after sinking and the SA before sinking. Furthermore, regulating lubricant layer thickness and tilt base angle is an important way to achieve smart control of the time required to initiate the sliding of the droplet. The uniqueness of the study is focused on the clever extension of the sinking behavior of droplets on LIPHSS to achieve a programmable time delay switch to smart control the sliding of droplets.

18.
J Colloid Interface Sci ; 557: 691-699, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31563059

RESUMO

Inkjet printing is an attractive technique in the field of flexible electronics due to the direct writing, digital controls and non-contact operation process. In this work, we successfully printed graphite oxide and Ag nanoparticles on the substrate of flexible carbon cloth to form a flexible, conductive and hydrophilic layer, which could be used as a new substrate with an electron transport layer of large surface area. In addition, Ni-Co LDH nanosheets as the main active materials were synthesized for improving the electrochemical activity via a convenient electrochemical deposition method. The binder-free Ni-Co LDH/Ag/rGO@CC electrode exhibits outstanding electrochemical performance along with a high capacity of 173 mA h g-1 at 1 A g-1. Moreover, an asymmetric supercapacitor (ASC) was assembled with Ni-Co LDH/Ag/rGO@CC electrode as the positive electrode materials and activated carbon coated CC as the negative electrode materials, showing a high capacity of 95 mA h g-1 at 0.6 A g-1, and maximum energy density of 76 Wh kg-1 at a power density of 480 W kg-1.

19.
J Colloid Interface Sci ; 557: 76-83, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31514095

RESUMO

Composite electrodes that possess both rational structures and appropriate integration are needed to deliver high electrochemical performance in energy storage devices. In this paper, a flexible and binder-free electrode material based on a heterogeneous core-shell structure of CuCo2O4@Ni(OH)2 nanosheets grown on carbon cloth was fabricated by a simple method. The unique three-dimensional hierarchical structure gives the electrode a large specific surface area, which enables rapid response and increases of specific capacitance. The CuCo2O4@Ni(OH)2/carbon fiber cloth (CFC) composite electrode exhibited a specific capacitance of 2160 F g-1 at 1 A g-1 and a good rate capability energy of 82.7% at 20 A g-1. A flexible all-solid-state asymmetric supercapacitor (FAASC) was assembled with the CuCo2O4@Ni(OH)2/CFC electrode as the positive electrode, and activated carbon (AC)/CFC as the negative electrode. This device showed both a high energy density and power density (58.9 W h kg-1 at a power density of 400 W kg-1), and good long-term cycling stability. Furthermore, the assembled CuCo2O4@Ni(OH)2/CFC//AC/CFC devices were capable of driving a blue light-emitting diode after a short charge. The remarkable performance of this CuCo2O4@Ni(OH)2/CFC electrode indicates that this heterogeneous structure has great potential for applications in flexible high-performance energy storage devices.

20.
Chemistry ; 25(51): 11892-11902, 2019 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-31309626

RESUMO

Semiconductor metal oxides (SMO)-based gas-sensing materials suffer from insufficient detection of a specific target gas. Reliable selectivity, high sensitivity, and rapid response-recovery times under various working conditions are the main requirements for optimal gas sensors. Chemical warfare agents (CWA) such as sarin are fatal inhibitors of acetylcholinesterase in the nerve system. So, sensing materials with high sensitivity and selectivity toward CWA are urgently needed. Herein, micro-nano octahedral Co3 O4 functionalized with hexafluoroisopropanol (HFIP) were deposited on a layer of reduced graphene oxide (rGO) as a double-layer sensing materials. The Co3 O4 micro-nano octahedra were synthesized by direct growth from electrospun fiber templates calcined in ambient air. The double-layer rGO/Co3 O4 -HFIP sensing materials presented high selectivity toward DMMP (sarin agent simulant, dimethyl methyl phosphonate) versus rGO/Co3 O4 and Co3 O4 sensors after the exposure to various gases owing to hydrogen bonding between the DMMP molecules and Co3 O4 -HFIP. The rGO/Co3 O4 -HFIP sensors showed high stability with a response signal around 11.8 toward 0.5 ppm DMMP at 125 °C, and more than 75 % of the initial response was maintained under a saturated humid environment (85 % relative humidity). These results prove that these double-layer inorganic-organic composite sensing materials are excellent candidates to serve as optimal gas-sensing materials.


Assuntos
Substâncias para a Guerra Química/análise , Óxidos/química , Propanóis/química , Substâncias para a Guerra Química/química , Gases , Grafite , Compostos Orgânicos
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