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[IEEE 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - Kiev (2018.4.24-2018.4.26)] 2018 IEEE 38th International Conference on Electronics and Nanotechnology (ELNANO) - Polymer/Ag Nanoparticles Composite for Chloroform Detection
摘要： In this paper we report on changes in the extinction spectra of a nanocomposite consisting of Ag nanoparticles arranged into poly(glycidyl methacrylate) host matrix. Two collective surface plasmon modes denoted as P and T were identified in the spectrum. They associated with electric dipoles perpendicular and parallel to the plane of the array respectively. It was found experimentally that intensity and bandwidth of corresponding bands decrease when the nanocomposite is exposed to chloroform vapor. At the same time, both plasmon bands shift toward shorter wavelength. Those dependences can be explained by weakening of the electrodynamic coupling between LSPR in neighboring nanoparticles due to the increase of the distance between particles caused by swelling of the polymer matrix. The spectral changes are fully reversible. It was found that sensitivity of the nanocomposite sensor to chloroform vapor is 0.02 nm/ppm with the response time t=25 s.
关键词： composite,localized surface plasmon resonanse,silver nanoparticles,vapor sensor
更新于2025-09-09 09:28:46
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A Modified Photoactivation Protocol Using Two Simultaneous Light-Curing Units for Bonding Brackets to Enamel
摘要： This study investigated the effect of a modified photoactivation protocol using two simultaneous light-curing units on the shear bond strength (SBS) of brackets to enamel. Metal brackets were bonded to bovine incisors using the resin-based orthodontic cement Transbond XT (3M Unitek). Four photoactivation protocols of the orthodontic cement were tested (n=15): Control: photoactivation for 10 s on each proximal face of the bracket at a time; Simultaneous: photoactivation for 10 s on both proximal faces of the bracket at the same time; One side-20s: photoactivation for 20 s at one proximal face of the bracket only; and One side-10s: photoactivation for 10 s only at one proximal face of the bracket. SBS was tested immediately or after 1000 thermal cycles. Adhesive remnant index (ARI) was classified. Data were subjected to two-way ANOVA and Student-Newman-Keuls’ test (α=0.05). Pooled means ± standard deviations for SBS to enamel (MPa) were: 10.2±4.2 (Control), 9.7±4.5 (Simultaneous), 5.6±3.1 (One side-20s), and 4.6±1.9 (One side-10s). Pooled SBS data for immediate and thermal cycled groups were 6.3±2.6 and 8.8±5.2. A predominance of ARI scores 1-2 and 0-1 was observed for the immediate and thermally cycled groups, respectively. In conclusion, simultaneous photoactivation of the orthodontic cement using two light-curing units, one positioned at each proximal face of the bracket, yielded similar bonding ability compared to the conventional light-curing method. Photoactivation of the orthodontic cement at one proximal face of the bracket only is not recommended, irrespective of the light-curing time used.
关键词： composite,polymerization,aging,Orthodontics,shear bond strength
更新于2025-09-04 15:30:14
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Moisture absorption and hydrothermal aging of phenylethynyl-terminated pyromellitic dianhydride-type asymmetric polyimide and composites
摘要： The effects of moisture on a polymerized monomeric reactant (PMR)-type polyimide (TriA X) and associated composites were investigated. Water uptake tests were performed on the polyimide at various temperatures and relative humidity levels to investigate moisture absorption behavior. Two-stage moisture absorption was observed, in which the first stage was diffusion controlled, whereas the second stage was moisture plasticization controlled. As exposure temperature increased, the equilibrium moisture content of the polyimide decreased, indicating an exothermic absorption process. The Arrhenius temperature dependence and moisture saturation as functions of temperature and humidity in the neat polymer were determined using curve fitting based on the published mathematical models. Long-term hydrothermal aging at 95°C was conducted on the neat polyimide and associated carbon fiber composites. Reversible hydrolytic reactions and a trace of irreversible hydrolysis were observed in the long-term exposure. The tensile ductility of the neat polyimide and the short-beam shear strength of the composites decreased with increasing aging time, while the tensile strength and modulus and thermal properties of the polyimide exhibited little change after 2000-h aging, demonstrating hydrothermal stability. The decrease in the ductility of the neat polymer after long-term moisture exposure was attributed to the network structure change, driven by hydrolysis and moisture plasticization.
关键词： β-relaxation,hydrothermal aging,moisture absorption,thermal properties,hydrolysis,Polyimide,composite,mechanical properties,plasticization
更新于2025-09-04 15:30:14
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Preparation and Characterization of Zeolite/TiO2 Cement-Based Composites with Excellent Photocatalytic Performance
摘要： A zeolite/TiO2 composite (ZTC) was applied to prepare a high-quality photocatalytic cement-based material (PCM). The acetone degradation experiment and micro measurements including XRD(X-Ray Diffractometer), SEM-EDS(Scanning Electron Microscope-Energy Dispersive Spectrometer), BET(BET Speci?c Surface Area Tester), FTIR(Fourier Transform Infrared Spectrometer) were conducted to characterize the photocatalytic ef?ciency and physicochemical properties of PCM, respectively. Results show that TiO2 particles disperse on the surface of a PCM homogeneously and provide abundant active sites for photocatalytic reactions. Compared to a normal photocatalytic cement-based material (NPCM), the TiO2 content of a PCM is lower and its photocatalytic ef?ciency is higher. The ZTC frees TiO2 particles from the impacts of cement hydration products and increases the adsorption volume of acetone. The photocatalytic performance of the PCM was stable after repeated tests. Using the ZTC as a photocatalyst has a prominent effect on the photocatalytic performance of the PCM.
关键词： photocatalytic cement-based material,photocatalytic ef?ciency,Zeolite/TiO2 composite
更新于2025-09-04 15:30:14
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Preparation, Characterization, and Photocatalytic Activity of LaMnO3 Nanorods-reduced Graphene Oxide Composite
摘要： Background: A new type of photocatalyst with a perovskite structure is recently utilized. The one-dimensional nanostructure of photocatalysts holds great charge mobility along the crystal longitudinal dimension and can hence provide the direct pathways of charge carriers. Graphene holds a superior electrical conductivity and high specific surface area. The aims of this paper are to make LaMnO3 nanorods disperse on the graphene surface. The synergistic effect between graphene and LaMnO3 nanorods enhances the photocatalytic performance. Method: LaMnO3 nanorods–graphene is fabricated using cetyltrimethyl ammonium bromide as template by a simple hydrothermal reaction followed by heat treatment. Results: XRD result indicates that the appropriate calcination temperature for the perovskite structure formation is 650°C. Electron microscopy reveals the LaMnO3 nanorods exhibit a good dispersion behavior on the surface of graphene and the specific surface area of LaMnO3 nanorods-graphene is higher than that of LaMnO3 nanorods. The activities of LaMnO3 nanorods–graphene and TiO2 are compared for degradation of Direct Green BE, the decolorizing rates are 99.93% and 79.45%, respectively. Conclusion: The photocatalytic results for Direct Green BE degradation showed that LaMnO3 nanorods–reduced graphene oxide exhibit a superior photocatalytic performance than that of LaMnO3 nanorods and TiO2 powders. The one-dimensional nanorod structure of LaMnO3 can provide a direct pathway for electronic transmission, and the increased aspect ratio is favorable for reducing the recombination probability of the electron and hole. Meanwhile, the photoelectron transport along the graphene sheets can promote the separation of the e?–h+ pairs.
关键词： Perovskite,nanorods,hydrothermal reaction,composite,photocatalysis,graphene
更新于2025-09-04 15:30:14
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Photodegradation of Methyl Orange Over CdS–TiO2/L-zeolite Composite Photocatalyst
摘要： A stable and active composite photocatalyst CdS–TiO2/L-zeolite has been synthesized through sol–gel method. The composite photocatalyst exhibits enhanced light harvesting in visible region indicating the improved photoresponsive ability because of CdS dopant. Photocatalytic conditions, such as the doping quantity of CdS, the concentration of photocatalyst, initial pH values and concentrations of methyl orange solutions have been systematically studied to obtain the highest photocatalytic efficiency. Photocatalytic kinetics of the composite photocatalyst is proved to conform to the first-order equation. The mechanism of the photocatalytic process is proposed in this work. L-zeolite support and CdS dopant could prevent the undesired electron/hole recombination and promote charge separation aiding for the continuous generation of active radicals. The novel composite photocatalyst shows good promise for applications in degrading environmental pollutants.
关键词： TiO2,Composite photocatalyst,Stability,CdS doping,L-zeolite
更新于2025-09-04 15:30:14
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European Microscopy Congress 2016: Proceedings || A micro-combinatorial TEM method for phase mapping of thin two-component films
摘要： The aim is to introduce a new method for the preparation and investigation of thin films of composite materials, specifically focusing on the synthesis and characterization of two-component thin films for optoelectronic applications. The study explores the potential of these materials in enhancing the performance of optoelectronic devices, such as solar cells and LEDs, by improving their efficiency and stability under various environmental conditions.
关键词： LEDs,optoelectronics,solar cells,composite materials,thin films
更新于2025-09-04 15:30:14
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Specific electron-transfer and surface plasmon resonance integrated boosting visible-light photoelectrochemical sensor for 4-chlorophenol
摘要： Emerging analytical technologies are being developed to provide advanced methods for monitoring 4-chlorophenol (4-CP) in the environment. Herein, a label-free, sensitive, and rapid photoelectrochemical (PEC) 4-CP detection system was constructed based on ternary composites of Ag nanoparticles, graphitic carbon nitride (GCN) and carbon spheres (CS) (Ag/GCN/CS). The proposed ternary composites were synthesized by a simple hydrothermal method. In this process, ascorbic acid (AA) played a crucial role in reducing Ag+ to metallic Ag, and provided a carbon source for CS. Due to synergistic promotion by the surface plasmon resonance (SPR) effect of Ag nanoparticles and electron-transfer behavior of CS, the ternary composites exhibited a broad visible light response and fast charge transfer, leading to a tremendously enhanced PEC response. Based on the promotion of the PEC response, a PEC sensor for 4-CP was designed by detecting the photocurrent signals of the PEC electrode after adding 4-CP to solution. Under optimal conditions, the PEC sensor exhibited a wide linear range for 4-CP from 16 to 1104 ng mL–1, with a limit of detection (LOD) of 5.33 ng mL–1. In particular, the present work may provide assist in better understanding the synergistic effect between the SPR effect of Ag nanoparticles and electron-transfer properties of CS. The results can also be applied to other PEC and photocatalytic systems in conjunction with high-performance photoactive materials.
关键词： PEC sensor,Carbon materials,Electron-transfer,SPR,Ternary composite
更新于2025-09-04 15:30:14
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A specifically-exposed cobalt oxide/carbon nitride 2D heterostructure for carbon dioxide photoreduction
摘要： Photocatalytic reduction of CO2 provides an opportunity to reach carbon neutrality, by which CO2 emissions from fuel consumption can be converted back to fuels. The challenge is to explore materials with high charge separation efficiency and effective CO2 adsorption capacity to boost the photoreduction of CO2. Here we report that 2D heterostructure comprised of Co3O4/2D g-C3N4 (COCN) can provide enhanced photocatalytic performance of reducing CO2 to CO, yielding a CO production rate of 419 μmol g-1 h-1 with selectivity of 89.4%, which is 13.5 and 2.6 times higher than that of pure 2D g-C3N4 and Co3O4. The enhanced photocatalytic performance arises from: (i) enhanced light absorption ability and charge separation efficiency originated from the unique 2D heterostructure connected through specifically-exposed facet interface and (ii) favorable CO2 adsorption capacity. The study may provide insight for the establishment of heterostructure-based photocatalytic system toward CO2 reduction.
关键词： g-C3N4,Co3O4,Composite photocatalysts,CO2 conversion
更新于2025-09-04 15:30:14
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Super compact and ultra-wideband bandpass filter with a wide upper stopband based on a SCRLH transmission-line unit-cell and two lumped capacitors
摘要： This paper presents a simplified composite right/left-handed transmission-line (SCRLH-TL) unit-cell, which is primarily consisted of a rectangular ring with two grounded vias. Superposing this unit-cell onto a high–low–high step-impedance resonator (SIR) leads to a novel SCRLH-TL multiple-mode resonator (SCRLH-TL MMR). By combining the SCRLH-TL MMR with a cross-shaped defected ground structure (DGS) and using a broadside coupling approach with two lumped capacitors, a highly compact and ultra-wideband bandpass filter was carefully designed and fully investigated. The filter was fabricated by using a conventional PCB process with the substrate of FR4. The measured 3-dB passband ranges from 2.55 through 11.75 GHz with the fractional bandwidth (FBW) of about 129%. The filter exhibits a high selectivity with steep skirt property, and has a wide upper stopband. Its total dimension, including the rectangular substrate with feed lines, occupies only 13.5 mm × 6.0 mm, which is found with the smallest size in comparison to those recently published in the literature.
关键词： lumped capacitors,Ultra-wideband bandpass filter,defected ground structure,simplified composite right/left-handed transmission-line,equivalent circuits
更新于2025-09-04 15:30:14