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Color Tunable Pigments with high NIR reflectance in Terbium doped Cerate systems for Sustainable Energy Saving Applications
摘要： Color tunable pigments from yellow to red hues were developed in Tb doped A2CeO4 (A = Sr and Ba) system by the conventional ceramic route. The developed pigments were analysed for their phase purity, chemical oxidation state, elemental analysis, morphology and optical properties by various advanced techniques. The Ba substitution in Sr2-xCe0.6Tb0.4O4 gently shifts the absorption edge to higher wavelengths producing bright yellows to reddish orange colors whereas, the Tb substitution in Ba2Ce1-xTbxO4 allows abrupt shift in the absorption edge to longer wavelengths leading to intense red hues. The chemical oxidation state analysis indicates the modifications of Tb3+ concentrations in both the environments due to metal to metal charge transfer transitions induced by lattice expansion. Typically the compositions SrBaCe0.6Tb0.4O4 (yellow; b* = 75.36, R = 91%) and Ba2Ce0.4Tb0.6O4 (red; a* = 30.09, R = 89%) exhibit brilliant coloristic and reflectance properties. The applicability studies revealed good coloring performance in the polymer matrix and on concrete slab with high solar reflectance. Further, the pigments are proven to be weather resistant in acid/alkali/moisture atmospheres with good thermal stability. These color characteristics with high solar reflectance of sustainable and eco-friendly compositions make them promising colorants for exterior coating formulations to mitigate the cooling energy consumption.
关键词： Yellow and Red pigments,Cerium,Terbium,Solar reflectance
更新于2025-11-21 11:18:25
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Black phosphorous sensitized TiO <sub/>2</sub> mesocrystals photocatalyst for hydrogen evolution with visible and near-infrared light irradiation
摘要： Wide absorption from ultraviolet (UV) to near-infrared (NIR) region and enhanced charge separation are two main requirements for promising semiconductor photocatalysts. Here, we studied visible-NIR driven photocatalytic hydrogen evolution over black phosphorus nanosheets/TiO2 mesocrystals loaded with Pt heterostructure (BP NS/ Pt (3 wt%)/TMC TMC). BP NS/Pt (3 wt%)/TMC can harvest photons from UV to NIR and simultaneously has enhanced charge separation to increase the generation of electrons for photocatalytic reduction of water. BP NS/Pt (3 wt%)/TMC exhibited photocatalytic H2 evolution rates of 1.9 and 0.41 μmol h-1 under visible (λ> 420 nm (420-1800 nm)) and NIR (λ> 780 nm (780-1800 nm) irradiation, respectively, compared with 0.3 and 0.10 μmol h-1 for BP NS/Pt (3 wt%)/P25. Moreover, a comparative study was made to examine the effect of thickness of BP NS on the photocatalytic H2 evolution. Femtosecond time-resolved diffused reflectance spectroscopy (fs-TRDRS) was integrated together with photoelectrochemical measurement to shed the light on the importance of charge transfer and separation, confirming that decreasing the thickness of BP NS enhances electron injection from BP NS to TMC to increase the photocatalytic activity.
关键词： hydrogen evolution,Black phosphorus,visible-light photocatalyst,charge carriers dynamics,TiO2 mesocrystals,femtosecond time-resolved diffuse reflectance
更新于2025-11-19 16:51:07
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Acceptance criteria for accelerated aging testing of silvered-glass mirrors for concentrated solar power technologies
摘要： Solar reflectors for Concentrating Solar Power (CSP) technologies are required to maintain their optical properties in demanding environments for more than 20 years of service-life. The durability of the commonly used silvered-glass reflectors is typically qualified by means of accelerated aging. Recently, the Spanish standardization committee UNE has published the first specific standard for this topic, which defines a set of accelerated aging tests for CSP reflectors. However, the standard does not contain pass/fail criteria. This paper proposes useful acceptance criteria for the accelerated tests defined by UNE, helping to interpret the obtained degradation results. The criteria have been determined by analyzing the collected accelerated aging data over the past 5 years in the OPAC laboratory, a joint research group of DLR and CIEMAT. Data from six different 4 mm silvered-glass manufacturers is presented, covering nearly the entire market of commercially available silvered-glass mirrors, and going way beyond the recommended testing times of the UNE standard. The data may be used to benchmark initial reflective properties (before aging) and the performance during accelerated durability testing. In addition, recommendations for improvements of the standard are given and an estimate of the acceleration factor of the Copper Accelerate Salt Spray (CASS) test with respect to a highly corrosive outdoor environment is presented.
关键词： Durability,Accelerated aging testing,Reflectance,Acceptance criteria,Solar reflector,Concentrated solar power
更新于2025-10-22 19:40:53
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On the Effect of Thin Film Growth Mechanisms on the Specular Reflectance of Aluminium Thin Films Deposited via Filtered Cathodic Vacuum Arc
摘要： The optimisation of the specular reflectance of solar collectors is a key parameter to increase the global yield of concentrated solar power (CSP) plants. In this work, the influence of filtered cathodic vacuum arc deposition parameters, particularly working pressure and deposition time, on the specular and diffuse reflectance of aluminium thin films, was studied. Changes in specular reflectance, measured by ultraviolet–visible and near-infrared spectroscopy (UV-vis-NIR) spectrophotometry, were directly correlated with thin film elemental concentration depth profiles, obtained by Rutherford backscattering spectrometry (RBS), and surface and cross-sectional morphologies as measured by scanning electron microscopy (SEM) and profilometry. Finally, atomic force microscopy (AFM) provided information on the roughness and growth mechanism of the films. The two contributions to the total reflectance of the films, namely diffuse and specular reflectance, were found to be deeply influenced by deposition conditions. It was proven that working pressure and deposition time directly determine the predominant factor. Specular reflectance varied from 12 to 99.8% of the total reflectance for films grown at the same working pressure of 0.1 Pa and with different deposition times. This transformation could not be attributed to an oxidation of the films as stated by RBS, but was correlated with a progressive modification of the roughness, surface, and bulk morphology of the samples over the deposition time. Hence, the evolution in the final optical properties of the films is driven by different growth mechanisms and the resulting microstructures. In addition to the originally addressed CSP applications the potential of the developed aluminium films for other application rather than CSP, such as, for example, reference material for spectroscopic diffuse reflectance measurements, is also discussed.
关键词： structural characterisation,total and specular reflectance,filtered cathodic vacuum arc,thin film deposition conditions
更新于2025-10-22 19:40:53
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Handling Electromagnetic Radiation beyond Terahertz using Chromophores to Transition from Visible Light to Petahertz Technology
摘要： An increase of the operating frequencies of electromagnetic waves leads from the well-established terahertz technology to the visual and reaches petahertz radiation. It is shown that electromagnetic radiation close to petahertz is attractive for technology where knowledge about radio waves can be applied. The dimensions of such radiation are still classically macroscopic; however, molecular components such as resonators were used where quantum mechanics rules have to be considered. Constructions of coupled resonators for energy transfer are as well demonstrated as molecular components for optical metamaterials.
关键词： Dyes,FRET,Energy transfer,Reflectance,Petahertz,Visible light,Resonators,Metamaterials,Terahertz,Electromagnetic radiation
更新于2025-09-23 15:23:52
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The bright side of PV production in snow-covered mountains
摘要： Our work explores the prospect of bringing the temporal production profile of solar photovoltaics (PV) into better correlation with typical electricity consumption patterns in the midlatitudes. To do so, we quantify the potential of three choices for PV installations that increase production during the winter months when electricity is most needed. These are placements that favor (i) high winter irradiance, (ii) high ground-reflected radiation, and (iii) steeper-than-usual panel tilt angles. In addition to spatial estimates of the production potential, we compare the performance of different PV placement scenarios in urban and mountain environments for the country of Switzerland. The results show that the energy deficit in a future fully renewable production from wind power, hydropower, and geothermal power could be significantly reduced when solar PV is installed at high elevations. Because the temporal production patterns match the typical demand more closely than the production in urban environments, electricity production could be shifted from summer to winter without reducing the annual total production. Such mountain installations require significantly less surface area and, combined with steeper panel tilt angles, up to 50% of the winter deficit in electricity production can be mediated.
关键词： panel tilt,seasonal energy gap,renewable energy,photovoltaic,surface reflectance
更新于2025-09-23 15:23:52
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The ablative fractional coagulation zone influences skin fluorescence intensities of topically applied test molecules-An in vitro study with fluorescence microscopy and fluorescence confocal microscopy
摘要： Background: Ablative fractional laser (AFL) increases uptake of topically applied skin agents. The coagulation zone (CZ) surrounding vertically ablated channels may influence uptake of drugs. Objectives: To investigate impact of CZ thickness on skin fluorescence intensities (FI) of a hydrophilic molecule by means of fluorescence microscopy (FM) and fluorescence confocal microscopy (FCM). Second, to compare FI of hydrophilic and lipophilic test molecules by FCM. Study Design/Methods and Materials: Microchannels with CZ thicknesses of 0, 20, and 80 μm were generated by microneedles or AFL (10,600 nm). Channels were 700 μm deep and number of channels kept constant per skin area. After 4 hours of incubation, FI induced by sodium fluorescein (NAF, hydrophilic, logarithmic partition-coefficient (logP) = -1.52, MW = 376.26) were quantified in both CZ and surrounding skin by FM (0–1,500 μm) and FCM (0–90 μm). FI of NAF and carboxyfluorescein (CAF, lipophilic, logP = 2.9, MW = 376.32) were compared by FCM. Results: By FM, NAF-induced FI were higher in CZ than in surrounding skin (P ≤ 0.001). Highest NAF-FI were induced in skin pretreated with a thin CZ (CZ–20 μm), assessed by both FM and FCM and in particular, FI were higher than in skin pretreated with no CZ (CZ–0 μm) (FM P ≤ 0.041, FCM P < 0.012). Skin FI remained constant to a depth of 500 μm, which corresponded to approximate depth of microchannels (CZ–0 μm, CZ–20 μm, CZ–80 μm: 0–500 μm P ≥ 0.107). In accordance with FM data, FCM showed higher FI within CZ than in surrounding skin, but gradually decreased to zero at a depth of 90 μm. NAF-FI were higher than CAF-FI (P ≤ 0.036), and highest CAF-FI were induced by CZ–0 μm and CZ–20 μm compared to CZ–80 μm (P ≤ 0.009). Conclusions: The influence of the CZ thickness on skin FI differs between small hydrophilic and lipophilic test molecules. Results may have clinical relevance for laser-assisted drug delivery.
关键词： sodium fluorescein,reflectance,carboxyfluorescein,dermatology,drug delivery,skin imaging
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 (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - LaSRC (Land Surface Reflectance Code): Overview, application and validation using MODIS, VIIRS, LANDSAT and Sentinel 2 data's
摘要： This paper presents a generic approach developed to derive surface reflectance over land from a variety of sensors. This technique builds on the extensive dataset acquired by the Terra platform by combining MODIS and MISR to derive an explicit and dynamic map of band ratio’s between blue and red channels and is a refinement of the operational approach used for MODIS and LANDSAT over the past 15 years. We will present the generic approach and the application to MODIS VIIRS, LANDSAT and Sentinel 2 data’s and its validation using the AERONET data [1].
关键词： aerosol,surface reflectance,validation
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 (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Using Reflectance Spectroscopy to Characterize Surface Landforms and Volcanic Deposits on Deception Island (Antarctica)
摘要： Deception Island is an active volcano in the Antarctic Peninsula region, affected by different geomorphological processes interacting to form a complex mosaic of landforms and deposits. The use of visible near infrared reflectance is an ideal tool for characterizing and monitoring surface covers and substrates. The objective of this work was to use reflectance spectroscopy to identify spectral characteristics of surface covers related to different volcanic deposits in ice-free areas of Deception Island, South-Shetland Islands. A site specific spectral library containing 220 reference spectra was compiled. Image-derived spectra from multispectral satellite data were easily labeled using the reference spectra. A preliminary distribution has distinguished five different deposit types over the entire area of Deception Island.
关键词： Reflectance spectra,spectral library,volcanic deposits,multispectral,geomorphology,South Shetland Islands
更新于2025-09-23 15:23:52
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Investigation of Sentinel-2 Bidirectional Reflectance Hot-Spot Sensing Conditions
摘要： Directional reflectance effects, often described by the bidirectional reflectance distribution function (BRDF), occur in Sentinel-2 multispectral instrument reflectance. The bidirectional hot-spot is a special case of the BRDF used to describe the increased backscatter reflectance that occurs over most surfaces when the solar and viewing directions coincide. A global year of Sentinel-2A metadata extracted using the Committee on Earth Observation Satellite Visualization Environment (COVE) tool and an established astronomical model were used to quantify the range of solar geometry and scattering angles expected in Sentinel-2A data. The established astronomical model was adapted to be Sentinel-2A specific and was parameterized as a function of the sensor acquisition date and nadir latitude. Solar zenith angles varied from 15.335° to 91.454°, and the scattering angles varied from 84.714° to 173.967°. To confirm the global COVE results, the scattering angles of a sample of Sentinel-2A data were examined and differed by less than 0.17° with respect to the COVE data. Given that hot-spots are only apparent when the scattering angle is close to 180°, we conclude that hot-spot will not occur in Sentinel-2A data. Equations and software to predict the scattering angle at the Sentinel-2A swath edge as a function of acquisition date and nadir latitude are provided so users may obtain data over a range of scattering angles in support of their BRDF studies.
关键词： bidirectional reflectance distribution function (BRDF),Bidirectional hot-spot,scattering angle,solar geometry,Sentinel-2
更新于2025-09-23 15:23:52