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Determination of the Thin-Film Structure of Zwitterion-Doped Poly(3,4-ethylenedioxythiophene):Poly(styrenesulfonate): A Neutron Reflectivity Study
摘要： Doping poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is known to improve its conductivity, however little is known about the thin film structure of PEDOT:PSS when doped with an asymmetrically charged dopant. In this study, PEDOT:PSS was doped with different concentrations of the zwitterion 3-(N,N Dimethylmyristylammonio)propanesulfonate (DYMAP), and its effect on the bulk structure of the films characterized by neutron reflectivity. The results show that at low doping concentration, the film separates into a quasi bi-layer structure with lower roughness (10%), increased thickness (18%), and lower electrical conductivity compared to the un-doped sample. However when the doping concentration increases the film forms into a homogeneous layer and experiences an enhanced conductivity by more than an order of magnitude, a 20% smoother surface, and a 60% thickness increase relative to the pristine sample. Atomic force microscopy and profilometry measurements confirmed these findings, and AFM height and phase images showed the gradually increasing presence of DYMAP on the film surface as a function of the concentration. Neutron reflectivity also showed that the quasi bi-layer structure of the lowest concentration doped PEDOT:PSS is separated by a graded rather than a well defined interface. Our findings provide an understanding of the layer structure modification for doped PEDOT:PSS films that should be prove important for device applications.
关键词： neutron reflectivity,hole transporting layer,conductivity,film structure,zwitterion,PEDOT:PSS
更新于2025-11-14 15:19:41
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RefMoB, a Reflectivity Feature Model-Based Automated Method for Measuring Four Outer Retinal Hyperreflective Bands in Optical Coherence Tomography
摘要： PURPOSE. To validate a model-driven method (RefMoB) of automatically describing the four outer retinal hyperreflective bands revealed by spectral-domain optical coherence tomography (SDOCT), for comparison with histology of normal macula; to report thickness and position of bands, particularly band 2 (ellipsoid zone [EZ], commonly called IS/OS). METHODS. Foveal and superior perifoveal scans of seven SDOCT volumes of five individuals aged 28 to 69 years with healthy maculas were used (seven eyes for validation, five eyes for measurement). RefMoB determines band thickness and position by a multistage procedure that models reflectivities as a summation of Gaussians. Band thickness and positions were compared with those obtained by manual evaluators for the same scans, and compared with an independent published histological dataset. RESULTS. Agreement among manual evaluators was moderate. Relative to manual evaluation, RefMoB reported reduced thickness and vertical shifts in band positions in a band-specific manner for both simulated and empirical data. In foveal and perifoveal scans, band 1 was thick relative to the anatomical external limiting membrane, band 2 aligned with the outer one-third of the anatomical IS ellipsoid, and band 3 (IZ, interdigitation of retinal pigment epithelium and photoreceptors) was cleanly delineated. CONCLUSIONS. RefMoB is suitable for automatic description of the location and thickness of the four outer retinal hyperreflective bands. Initial results suggest that band 2 aligns with the outer ellipsoid, thus supporting its recent designation as EZ. Automated and objective delineation of band 3 will help investigations of structural biomarkers of dark-adaptation changes in aging.
关键词： age-related macular degeneration,retina,ellipsoid,segmentation,optical coherence tomography,photoreceptors,interdigitation,reflectivity,retinal pigment epithelium
更新于2025-09-23 15:23:52
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Night-Time Oxidation of a Monolayer Model for the Air–Water Interface of Marine Aerosols—A Study by Simultaneous Neutron Reflectometry and in Situ Infra-Red Reflection Absorption Spectroscopy (IRRAS)
摘要： This paper describes experiments on the ageing of a monolayer model for the air–water interface of marine aerosols composed of a typical glycolipid, galactocerebroside (GCB). Lipopolysaccharides have been observed in marine aerosols, and GCB is used as a proxy for these more complex lipopolysaccharides. GCB monolayers are investigated as pure films, as mixed films with palmitic acid, which is abundant in marine aerosols and forms a stable attractively mixed film with GCB, particularly with divalent salts present in the subphase, and as mixed films with palmitoleic acid, an unsaturated analogue of palmitic acid. Such mixed films are more realistic models of atmospheric aerosols than simpler single-component systems. Neutron reflectometry (NR) has been combined in situ with Fourier transform infra-red reflection absorption spectroscopy (IRRAS) in a pioneering analysis and reaction setup designed by us specifically to study mixed organic monolayers at the air–water interface. The two techniques in combination allow for more sophisticated observation of multi-component monolayers than has previously been possible. The structure at the air–water interface was also investigated by complementary Brewster angle microscopy (BAM). This study looks specifically at the oxidation of the organic films by nitrate radicals (NO3?), the key atmospheric oxidant present at night. We conclude that NO3? oxidation cannot fully remove a cerebroside monolayer from the surface on atmospherically relevant timescales, leaving its saturated tail at the interface. This is true for pure and salt water subphases, as well as for single- and two-component films. The behaviour of the unsaturated tail section of the molecule is more variable and is affected by interactions with co-deposited species. Most surprisingly, we found that the presence of CaCl2 in the subphase extends the lifetime of the unsaturated tail substantially—a new explanation for longer residence times of materials in the atmosphere compared to lifetimes based on laboratory studies of simplified model systems. It is thus likely that aerosols produced from the sea-surface microlayer at night will remain covered in surfactant molecules on atmospherically relevant timescales with impact on the droplet’s surface tension and on the transport of chemical species across the air–water interface.
关键词： palmitic acid,monolayer,neutron,nitrate radical,palmitoleic acid,reflectivity,aerosol,infra-red,cerebroside,Brewster angle microscopy
更新于2025-09-23 15:23:52
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Impact of the Elevation Angle on Cygnss GNSS-R Reflectivity over Different Scattering Media over Land and Ocean
摘要： Earth’s surface bistatic reflectivity LHCP,CyGNSS? profiles are obtained using Global Navigation Satellite Systems Reflectometry (GNSS-R) products from NASA’s Cyclone Global Navigation Satellite Systems (CyGNSS). The focus of this study is to evaluate the influence of the GNSS satellites’ elevation angle e? on LHCP,CyGNSS?. Specific target areas with differentiated scattering media are selected to characterize these profiles as a function of the land-cover type and the wind-speed regimes for ocean-surfaces. In the former case, the main interest is to further understand the function eLHCP,CyGNSS(,...)f??? in preparation of the potential application of the so-called Tau-Omega model to GNSS-R. In the latter case, the objective is to analyze the impact of the coherent scattering component in GNSS-R observables. Preliminary results show LHCP,CyGNSS? increases ~ 3.7 dB over land and ~ 5.3 dB ocean, as e? moves from ~ [70,90]o to ~ [20,40]o.
关键词： CyGNSS,GNSS-R,coherent and incoherent scattering,elevation angle,bistatic reflectivity
更新于2025-09-23 15:21:21
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Effect of low-energy ion impact on the structure of hexagonal boron nitride films studied in surface-wave plasma
摘要： A high‐density surface‐wave plasma source is used to deposit hexagonal boron nitride (hBN) films in a gas mixture of He, H2, N2, Ar, and BF3 under a high ion flux condition using low‐energy ion irradiation. The ion energy is controlled between around zero and 100 eV by applying a negative or positive bias voltage to a substrate, while the ion flux is increased by locating a substrate upstream in the diffusive plasma. For ion energies above ～37 eV, the structure of the films depends upon ion energy more than substrate temperature, typical of subplantation processes. As a result, the structural order and crystallinity of sp2‐bonded phase in the films characterized by Fourier transform infrared spectroscopy and X‐ray diffraction are increased with decreasing ion energy, while the mass density of the films characterized by X‐ray reflectivity is retained relatively high with a slight dependence upon ion energy.
关键词： surface‐wave plasma,Fourier transform infrared spectroscopy (FTIR),chemical vapor deposition (CVD),hexagonal boron nitride (hBN),X‐ray diffraction (XRD),X‐ray reflectivity (XRR)
更新于2025-09-23 15:21:21
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The mathematical and experimental analysis on the steady-state operating temperature of bifacial photovoltaic modules
摘要： The operating temperature of bifacial photovoltaic (PV) module affects its power generation and reliability. Combined with view factor model of ground reflectivity on module backside, a thermal steady-state model is established to analyze the thermal performance of bifacial module in this paper. The module operating temperatures under three different installation conditions of roof cement ground, water surface and grassland are calculated and simulated by ANSYS software, and the experiments are designed to analyze and verify it. Based on the difference of reflectivity and heat capacity of different ground for the PV module installation, the effects of ground type and module material on bifacial module temperature and its mechanism are analyzed quantitatively. According to the simulation and experiment results, the operating temperatures of the bifacial modules installed on the roof cement ground, water surface and grassland are 44.7 (cid:1)C, 41.5 (cid:1)C, 43.2 (cid:1)C respectively, under the setting environment condition with specific irradiance, wind speed and ambient temperature. The temperature difference of 1.7 (cid:1)C e3.2 (cid:1)C is caused by ground reflectivity and temperature. The operating temperature difference between glass-glass and glass-backsheet module is less than 0.4 (cid:1)C under the standard condition. The conductivity and emissivity of encapsulation material does not show strong influence on module operating temperature.
关键词： Bifacial PV module,Solar cell,Ground reflectivity,Operating temperature
更新于2025-09-23 15:21:01
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Analysis of the reflectivity in meteorological radars using data mining and neural networks
摘要： The aim of this work is show the analysis of the data measured by weather radar used in data mining and fuzzy logic. A decoding of the data measured by the meteorological radar was made, which was encrypted, then an analysis of this data was made using neural networks that are trained with 10 and 20 neurons, in each case the effectiveness of each one is checked. The results showed that neural networks are an excellent tool that allows eliminate erroneous information and then normalize it to the scale used according to the standard. This knowledge is essential for the aviation industry to operate properly and without risks for passengers, crew and aircraft, it is also important to anticipate and/or avoid, if possible, catastrophes generated by weather events related to rainfall.
关键词： Polarimetric Variables,Reflectivity,Weather Radar,Neural Networks,Data Mining
更新于2025-09-23 15:21:01
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Ultrafast energy absorption and photoexcitation of bulk plasmon in crystalline silicon subjected to intense near-infrared ultrashort laser pulses
摘要： We investigate the non-linear response and energy absorption in bulk silicon irradiated by intense 12-fs near-infrared laser pulses. Depending on the laser intensity, we distinguish two regimes of non-linear absorption of the laser energy: for low intensities, energy deposition and photoionization involve perturbative three-photon transition through the direct bandgap of silicon. For laser intensities near and above 1014 W/cm2, corresponding to photocarrier density of order 1022 cm?3, we find that absorption at near-infrared wavelengths is greatly enhanced due to excitation of bulk plasmon resonance. In this regime, the energy transfer to electrons exceeds a few times the thermal melting threshold of Si. The optical reflectivity of the photoexcited solid is found in good qualitative agreement with existing experimental data. In particular, the model predicts that the main features of the reflectivity curve of photoexcited Si as a function of the laser fluence are determined by the competition between state and band filling associated with Pauli exclusion principle and Drude free-carrier response. The non-linear response of the photoexcited solid is also investigated for irradiation of silicon with a sequence of two strong and temporary non-overlapping pulses. The cumulative effect of the two pulses is non-additive in terms of deposited energy. Photoionization and energy absorption on the leading edge of the second pulse is greatly enhanced due to free carrier absorption.
关键词： bulk silicon,optical reflectivity,photoexcited solid,near-infrared laser pulses,Drude free-carrier response,non-linear response,energy absorption,plasmon resonance
更新于2025-09-23 15:21:01
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A Phase Sensitivity-Enhanced Surface Plasmon Resonance Biosensor Based on ITO-Graphene Hybrid Structure
摘要： In this paper, a surface plasmon resonance (SPR) sensor based on the hybrid structure of silver (Ag)-indium tin oxide (ITO)-graphene is proposed and investigated. SPR biosensors are subdivided into three kinds of structures Ag, Ag-graphene, and Ag-ITO-graphene, when carried out using their respective optimized structure parameters. According to our analysis and comparison, the ITO-assisted SPR biosensor has an optimal reflectivity of 3.587 × 10?8 and a maximum phase sensitivity of 1.707 × 106°/RIU, which shows that ITO can be employed to further enhance the SPR sensing performance even with the existence of graphene.
关键词： Surface-plasmon-resonance,Hybrid structure,Phase sensitivity,Reflectivity
更新于2025-09-23 15:21:01
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Clinically Relevant Outcome Measures for the I307N Rhodopsin Mouse: A Model of Inducible Autosomal Dominant Retinitis Pigmentosa
摘要： PURPOSE. The I307N rhodopsin (Rho) mouse is a light-inducible model of autosomal dominant retinitis pigmentosa (adRP) that may be useful in testing therapies. We investigated the time-course of retinal changes of the I307N Rho mouse with spectral-domain optical coherence tomography (SD-OCT). METHODS. SD-OCT was performed up to day 30 after light damage; electroretinography (ERG) was employed to evaluate photoreceptor function. We utilized ImageJ to analyze reflectivity of the retina. We used light and electron microscopy to assess retinal organization. We stained synaptophysin and zonula occludins-1 with immunohistochemistry to determine injury to the plexiform layers and retinal pigment epithelium (RPE). We performed lectin staining to evaluate retinal blood vessels. RESULTS. Retinal degeneration increased with longer exposures to light. An increase in retinal thickness was detected by SD-OCT on day 1 after light challenge followed by loss of the outer nuclear layer (ONL) by day 8. Degeneration was most severe in the nasal and inferior retina. Hyper-reflectivity on SD-OCT developed as early as 1 day after light exposure. Disorganization of the ONL, condensation of photoreceptor chromatin, disruption of the outer limiting membrane, and disarray of outer segments were associated with the hyper-reflectivity. Retraction of the outer plexiform synapses and resorption of the subretinal detachment contributed to retinal thinning. The RPE remained intact, whereas atrophied major retinal vessels were evident after light damage. CONCLUSIONS. Our time-course analysis of retinal degeneration in the I307N Rho mouse with SD-OCT and other outcome measures should enable the use of the mouse model in preclinical efficacy studies and mechanistic studies.
关键词： SD-OCT,rhodopsin,electroretinography,retinitis pigmentosa,hyper-reflectivity
更新于2025-09-23 15:21:01