- 标题
- 摘要
- 关键词
- 实验方案
- 产品
过滤筛选
- 2018
- ac-dc difference
- Thermal transfer standard
- inductive voltage
- uncertainty budget
- pulse-driven ac Josephson voltage standard
- Measurement and Control Technology and Instruments
- National Institute of Metrology
-
Self-electrochemiluminescence of poly[9,9-bis(3‘-(N,N- dimethyl amino)propyl)-2,7-fluorene]-alt- 2,7-(9,9- dioctylfluorene)] and resonance energy transfer to aluminum tris(8-quinolinolate)
摘要： In this paper, the electrochemiluminescence (ECL) behavior of a hole-transport polymer, poly [9,9-bis(3'-(N,N-dimethylamino) propyl)-2,7-fluorene]-alt-2,7-(9,9-dioctylfluorene)] (PFN) was examined with the purpose of finding a novel organic ECL emitter. It was found that the PFN exhibits self-electrochemiluminescence (self-ECL) without any exogenous co-reactants. Quite different from the traditional ECL, the addition of tripropyl amine (TPA) quenched the self-ECL of PFN. PFN ECL intensity reaches a peak during electrochemical oxidation process due to the superposition of self-enhanced ECL, and aggregation quenching of excited state by PFN excimer formation. Aluminum tris(8-quinolinolate) (AlQ3) doped with PFN recovers luminescence intensity with restraining quenching effect via ECL resonance energy transfer from PFN to AlQ3, giving rise to a stable luminescence signal, and hence sensory detection of nitroaromatics. The limits of detections for nitroaromatics can reach down to a level of 10^-22 M. This work sets the stage for a novel organic polymer-based ECL emitter without using any toxic exogenous co-reactant, and presents a practical avenue for a prototype of realising sensory detection through signal stabilization via energy resonance energy transfer (ERET).
关键词： poly[9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene]-alt-2,7-(9,9-dioctylfluorene),Sensor,Resonance energy transfer,Self-electrochemiluminescence
更新于2025-09-23 15:23:52
-
Influence of the intramolecular donor-acceptor distance on the performance of double-cable polymers
摘要： A series of double-cable polymers PFT-C4-PDI, PFT-C6-PDI and PFT-C8-PDI, composed of the poly(fluorene-alt-thiophene) (PFT) backbone, the perylene diimide (PDI) pendants and the length-various (four-, six- and eight-carbon) covalent alkoxy linkers, were presented. The backbone polymer chain created the hole-transporting channel and the inner-chain aggregation of PDI units created the electron-transporting channel, but the aggregation became weaker along with the longer linker, as proven by the UV-Vis absorption and fluorescence quenching. The polymers were non-conducting, but functioned as efficient compatibilizers. The doping of the polymers induced the formation of the bi-continuous networks inside P3HT:PCBM blends, facilitated photo-generated exciton dissociation and charge transporting. PFT-C4-PDI more efficiently increased the absorption coefficient and the charge-carrier mobility of the P3HT:PCBM film. The power conversation efficiency (PCE) of the P3HT:PCBM bulk-heterojunction solar cells with 3 wt% PFT-C4-PDI, PFT-C6-PDI and PFT-C8-PDI doping were improved by 16.9%, 9.2% and 8.0%, respectively, relative to the non-doped reference device.
关键词： Structure-property relationships,Energy transfer,Double-cable polymer,Polymer solar cells,Bi-continuous networks
更新于2025-09-23 15:23:52
-
3D graphene/AgBr/Ag cascade aerogel for efficient photocatalytic disinfection
摘要： To design semiconductor-based photocatalysts with efficient charge carriers separation and transfer remains an enduring goal of artificial photosynthesis toward target redox reactions. Herein, we report a cascade monolith composite of ternary reduced graphene oxide aerogel/silver bromide/silver (RGA/AgBr/Ag) with efficient charge carriers separation, which exhibits much higher activity than bare AgBr toward photocatalytic bacteria inactivation. Mechanistic studies reveal that the reduced graphene oxide aerogel (RGA) scaffold and Ag nanoparticles serve as electron relay mediators to promote the charge carriers separation and transfer. In addition, the metallic Ag nanoparticles derived from the photoreduction of AgBr during the photocatalytic disinfection can further boost the separation of charge carriers. Control experiments demonstrate that the surface plasmon resonance (SPR)-excited hot electrons of Ag nanoparticles also contributes to enhancing the photoactivity of RGA/AgBr/Ag. As such, the synergy of multiple electron transfer behavior integratively leads to the boosted photocatalytic performance of such RGA/AgBr/Ag aerogel for bacteria inactivation with convenient recyclable operability.
关键词： charge transfer,aerogel,silver bromide,Ag nanoparticles,reduced graphene oxide
更新于2025-09-23 15:23:52
-
Optically active polyaniline film based on cellulose nanocrystals
摘要： Chiral transfer from cellulose nanocrystals (CNCs) chiral nematic liquid crystal to polyaniline (PANI) is successfully achieved through co-assembly method for the first time, affording the PANI film based on CNCs optical activity. Meanwhile, the CNCs/PANI composite film displays notable Cotton effect ascribed to the polaron band transitions of PANI in circular dichroism (CD) spectrum. Hydrogen bond and electrostatic attraction favor the combination of two molecular chains in the mixed aqueous suspension and will lead to the chiral assembly of the PANI in the host chiral nematic film. However, the CD signal disappears when cholesteric phase collapse by acid protonation, and which demonstrates the chiral nematic ordering of the CNCs is essential to the chiral transfer. With the assistance of CNCs, PANI chains form a helically stacked structure. Thus, the optical activity of PANI originates from its long range organization.
关键词： co-assembly,chiral transfer,polaron transition,optical activity,Cotton effect
更新于2025-09-23 15:23:52
-
LESS: LargE-Scale remote sensing data and image simulation framework over heterogeneous 3D scenes
摘要： Three-dimensional (3D) radiative transfer modeling of the transport and interaction of radiation through earth surfaces is challenging due to the complexity of the landscapes as well as the intensive computational cost of 3D radiative transfer simulations. To reduce computation time, current models work with schematic landscapes or with small-scale realistic scenes. The computer graphics community provides the most accurate and efficient models (known as renderers) but they were not designed specifically for performing scientific radiative transfer simulations. In this study, we propose LESS, a new 3D radiative transfer modeling framework. LESS employs a weighted forward photon tracing method to simulate multispectral bidirectional reflectance factor (BRF) or flux-related data (e.g., downwelling radiation) and a backward path tracing method to generate sensor images (e.g., fisheye images) or large-scale (e.g. 1 km2) spectral images. The backward path tracing also has been extended to simulate thermal infrared radiation by using an on-the-fly computation of the sunlit and shaded scene components. This framework is achieved through the development of a user-friendly graphic user interface (GUI) and a set of tools to help construct the landscape and set parameters. The accuracy of LESS is evaluated with other models as well as field measurements in terms of directional BRFs and pixel-wise simulated image comparisons, which shows very good agreement. LESS has the potential in simulating datasets of realistically reconstructed landscapes. Such simulated datasets can be used as benchmarks for various applications in remote sensing, forestry investigation and photogrammetry.
关键词： Landscape modeling,Image simulation,Radiative transfer
更新于2025-09-23 15:23:52
-
[Zn(OOCH)2(4,4′-bipyridine)] : A metal-organic-framework (MOF) with x-ray-induced photochromic behaviour at room temperature
摘要： Materials that may show photochromism under X-rays have higher spatial resolution for visual low-energy X-rays detection over the commercial instruments and greater X-ray sensitivity than silver salt-based radiographic films. In this work, we discovered that the known MOF, [Zn(OOCH)2(Bpy)]n (Bpy = 4,4′-bipyridine), showed rare photochromic behaviour upon irradiation of hard and soft X-rays at room temperature.
关键词： Metalloviologen,MOF,Photochromic,Radical,X-ray detection,Electron transfer
更新于2025-09-23 15:23:52
-
Direct utilization of solar linear Fresnel reflector on multi-effect eccentric horizontal tubular still with falling film
摘要： The paper presents a multi-eccentric tubular desalination system heated directly by a linear Fresnel reflector (LFR) field to enhance the productivity. In this novel system, the solar radiation is sent directly into desalination unit. The configuration and working processes of the proposed design are described in details. The tube inner wall with absorbing coating were used as a receiver by placing in the cylindrical cavity to absorb concentrated solar energy and transfer it to a falling water film. To verify the performance of the system in different effects, an indoor experimental eccentric tubular still was fabricated and tested under different heating conditions from 400 to 1600 W respectively. The experimental results showed that the maximum accumulated yield of the 1st and 2nd effect are about 28.27 kg and 21.37 kg, respectively. The outdoor experimental results show that the cumulative output of the unit is about 11.35 kg, the maximum performance ratio (PR) is about 2.88 with an evacuated tube solar collector. A two-effect tubular desalination system for linear Fresnel reflector with a capacity of 63.68 kg/d was proposed according to the presented theoretical and experimental work. By taking solar linear Fresnel reflector heating mode, the cost of water production reaching about $6.16/ton.
关键词： Falling water film,Heat and mass transfer,Solar distillation,Horizontal tubular still,Multi-eccentric
更新于2025-09-23 15:23:52
-
Multi-arm polymers prepared by atom transfer radical polymerization (ATRP) and their electrospun films as oxygen sensors and pressure sensitive paints
摘要： New oxygen and pressure sensitive paints (PSPs) with four-arm polymeric structures were prepared by using a kind of controlled living polymerizations - atom transfer radical polymerization (ATRP). The polymers composing of poly(isobutyl methacrylate)-co-poly(trifluoroethyl methacrylate)s (PolyIBMA-co-PolyTFEM)s act as the matrices for the platinum porphyrin-based phosphorescence probes, which were copolymerized in the matrices. The polymers were characterized by using 1H-NMR, 19F-NMR, and GPC to demonstrate their successful preparation. The influence of polymer structures on sensing activity including the sensitivity and response time to oxygen and/or pressure was investigated. Results showed that copolymers with suitable compositions (herein P3) can have highest sensitivity. Polymer structure's influence on response time to oxygen was also investigated. For increasing the polymer's surface area for further improving sensing sensitivity, electrospinning method was used for preparing films with micro-spherical or fibrous structures. The morphologies of electrospinning coated films were observed by SEM. Results showed that electrospinning coated films can respond much better to oxygen and pressure than their corresponding sprayed plates. This is the first time to apply the controlled living polymerization approach to prepare PSPs with multi-arm structures, which will broaden the PSP functional materials' design strategy.
关键词： oxygen sensing,pressure sensitive paints,electrospinning,multi-arm polymers,atom transfer radical polymerization
更新于2025-09-23 15:23:52
-
A New Biscarbazole-Based Metal-Organic Framework for Efficient Host-Guest Energy Transfer
摘要： A new metal–organic framework (MOF), [Zn6L4(Me2NH2+)4·3 H2O] (1) was constructed based on [9,9’-biscarbazole]-3,3’,6,6’-tetracarboxylic acid (H4L) and Zn2+ ions. The porous framework and intense blue fluorescence of the MOF based on the biscarbazole moiety of the ligand could facilitate efficient host to guest energy transfer, which makes it an ideal platform for the tuning of luminescence.
关键词： in situ encapsulation,metal–organic frameworks,energy transfer,host–guest systems,fluorescence
更新于2025-09-23 15:23:52
-
Excited State Dynamics of [Ru(bpy)3]2+ Thin Films on Sensitized TiO2 and ZrO2
摘要： The excited state dynamics of Tris(2,2'-bipyridine)ruthenium(II) hexafluorophosphate, [Ru(bpy)3(PF6)2], was investigated on the surface of bare and sensitized TiO2 and ZrO2 films. The organic dyes LEG4 and MKA253 were selected as sensitizers. A Stern-Volmer plot of LEG4-sensitized TiO2 substrates with a spin-coated [Ru(bpy)3(PF6)2] layer on top shows considerable quenching of the emission of the latter. Time-resolved emission spectroscopy interestingly reveals the presence of a fast-decay time component (25±5 ns), which is absent when the anatase TiO2 semiconductor is replaced by ZrO2. It should be specified that the positive redox potential of the ruthenium complex prevents electron transfer from the [Ru(bpy)3(PF6)2] ground state into the oxidized sensitizer. Therefore, we speculate that the fast-decaying time component observed may be identified with excited-state electron transfer from [Ru(bpy)3(PF6)2] to the oxidized sensitizer. Solid-state dye sensitized solar cells (ssDSSCs) employing MKA253 and LEG4 dyes, with [Ru(bpy)3(PF6)2] employed as a hole-transporting material (HTM), exhibit 1.2% and 1.1% power conversion efficiency, respectively. This result illustrates the possibility of the hypothesized excited-state electron transfer.
关键词： Photochemistry,Excited-state electron transfer,DSSCs,Ru(bpy)3,Solid state
更新于2025-09-23 15:23:52