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Effects of Metal Dopings on CuCr <sub/>2</sub> O <sub/>4</sub> Pigment for Use in Concentrated Solar Power Solar Selective Coatings
摘要： The process of fabricating the solar absorbing spinel-structured CuCr2O4 black oxide pigment doped with different metals (Mn, Ni, Co, Al, Zn, and Sn) was discovered to improve the solar selective property. Manganese stands out as an ideal dopant to Copper Chromite (CuCr2O4) for highly solar absorptive pigments compared to the other metal dopings. XRD analysis confirmed that various molar ratio of CuCr(2-x)MnxO4 spinel black oxides were successfully fabricated. Mn-doped black oxide has the highest absorptivity (the lowest band gap value of 1.35 eV) among other metal doping black oxides produced by the hydrothermal synthesis. Manganese is the only dopant that suppresses reflectance peaks exhibited by the copper chromium oxide at 1 μm and 1.5 μm in the light spectrum, raising the solar absorptivity of the pigment. Different manganese doping compositions are introduced to CuCr(2-x)MnxO4 where x = 0.1, 0.25, 0.5, 1, 1.5, 1.75, and 1.9. The high selective solar absorptivity appears after 100% (x=1) manganese doping with solar absorbance 0.9874 and a Figure of Merit (FOM) value of 0.9284.
关键词： Concentrated Solar Power,Solar selective coating,Solar-absorbing pigment,Black paint,Spinel black oxide.
更新于2025-09-23 15:23:52
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Tattoo Inks EM Characterization for MRI Interaction Evaluation
摘要： The lack of knowledge about the safety implications of tattooed individuals subjected to Magnetic Resonance Imaging (MRI) may, sometimes, lead to an exaggerate reaction from physicians such as the avoidance of the exam for tattooed patients. To explore the actual risks, in this work, the magnetic and electrical properties of five different tattoo inks have been measured to investigate their interaction with the MRI electromagnetic (EM) fields. Results highlight that the magnetic and electrical behaviour strongly depend on the type of analyzed ink. Magnetic measurements also reveal a different response between the ink solutions and the relative pigments.
关键词： Magnetic Resonance Imaging,electrochemical impedance,magnetization measurements,tattoo ink,Electrical conductivity,tattoo pigment
更新于2025-09-23 15:23:52
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Formation and Clearance of All- <i>Trans</i> -Retinol in Rods Investigated in the Living Primate Eye With Two-Photon Ophthalmoscopy
摘要： PURPOSE. Two-photon excited fluorescence (TPEF) imaging has potential as a functional tool for tracking visual pigment regeneration in the living eye. Previous studies have shown that all-trans-retinol is likely the chief source of time-varying TPEF from photoreceptors. Endogenous TPEF from retinol could provide the specificity desired for tracking the visual cycle. However, in vivo characterization of native retinol kinetics is complicated by visual stimulation from the imaging beam. We have developed an imaging scheme for overcoming these challenges and monitored the formation and clearance of retinol. METHODS. Three macaques were imaged by using an in vivo two-photon ophthalmoscope. Endogenous TPEF was excited at 730 nm and recorded through the eye’s pupil for more than 90 seconds. Two-photon excited fluorescence increased with onset of light and plateaued within 40 seconds, at which point, brief incremental stimuli were delivered at 561 nm. The responses of rods to stimulation were analyzed by using first-order kinetics. RESULTS. Two-photon excited fluorescence resulting from retinol production corresponded to the fraction of rhodopsin bleached. The photosensitivity of rhodopsin was estimated to be 6.88 ± 5.50 log scotopic troland. The rate of retinol clearance depended on intensity of incremental stimulation. Clearance was faster for stronger stimuli and time constants ranged from 50 to 300 seconds. CONCLUSIONS. This study demonstrates a method for rapidly measuring the rate of clearance of retinol in vivo. Moreover, TPEF generated due to retinol can be used as a measure of rhodopsin depletion, similar to densitometry. This enhances the utility of two-photon ophthalmoscopy as a technique for evaluating the visual cycle in the living eye.
关键词： photoreceptors,visual cycle,ophthalmic imaging,pigment regeneration
更新于2025-09-23 15:22:29
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The Evolution of the Plateau, an Optical Coherence Tomography Signature Seen in Geographic Atrophy
摘要： PURPOSE. Histologic details of progression routes to geographic atrophy (GA) in AMD are becoming available through optical coherence tomography (OCT). We studied the origins and evolution of an OCT signature called plateau in eyes with GA and suggested a histologic correlate. METHODS. Serial eye-tracked OCT scans and multimodal imaging were acquired from eight eyes of seven patients with GA and plateau signatures over a mean follow-up of 7.7 years (range, 3.7–11.6). The histology of unrelated donor eyes with AMD was reviewed. RESULTS. Drusenoid pigment epithelial detachment (PED) on OCT imaging progressed into wide-based mound-like signatures with flattened apices characterized by a hyporeflective yet heterogeneous interior and an overlying hyperreflective exterior, similar to outer retinal corrugations previously ascribed to persistent basal laminar deposit (BLamD) but larger. These new signatures are described as "plateaus." An initial increase of the PED volume and hyporeflectivity of its contents was followed by a decrease in PED volume and thinning of an overlying hyperreflective band attributable to the loss of the overlying RPE leaving persistent BLamD. Both imaging and histology revealed persistent BLamD with defects through which gliotic Müller cell processes pass. CONCLUSIONS. Plateaus can be traced back to drusenoid PEDs on OCT imaging. We hypothesize that during progressive RPE atrophy, Müller cell extension through focal defects in the residual persistent BLamD may contribute to the heterogeneous internal reflectivity of these entities. The role of Müller cell activation and extension in the pathogenesis of AMD should be explored in future studies.
关键词： geographic atrophy,multimodal imaging,optical coherence tomography,histology,drusenoid pigment epithelial detachment
更新于2025-09-23 15:22:29
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Reliability of Heterochromatic Flicker Photometry in Measuring Macular Pigment Optical Density among Preadolescent Children
摘要： Macular pigment optical density (MPOD)—assessed using customized heterochromatic flicker photometry (cHFP)—is related to better cognition and brain lutein among adults. However, the reliability of MPOD assessed by cHFP has not been investigated in children. We assessed inter-session reliability of MPOD using modified cHFP. 7–10-year-olds (n = 66) underwent cHFP over 2 visits using 11 examiners. Reliability was also assessed in a subsample (n = 46) with only 2 examiners. Among all participants, there was no significant difference between the two sessions (p = 0.59—session 1: 0.61 ± 0.28; session 2: 0.62 ± 0.27). There was no significant difference in the MPOD of boys vs. girls (p = 0.56). There was a significant correlation between sessions (Y = 0.52x + 0.31; R2 = 0.29, p ≤ 0.005), with a reliability of 0.70 (Cronbach’s α). Among the subsample with 2 examiners, there was a significant correlation between sessions (Y = 0.54x + 0.31; R2 = 0.32, p < 0.005), with a reliability of 0.72 (Cronbach’s α). In conclusion, there is moderate reliability for modified cHFP to measure MPOD in preadolescents. These findings provide support for future studies aiming to conduct noninvasive assessments of retinal xanthophylls and study their association with cognition during childhood.
关键词： retinal lutein,heterochromatic flicker photometry,macular pigment optical density
更新于2025-09-23 15:22:29
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Copper doped nickel aluminate: Synthesis, characterisation, optical and colour properties
摘要： Novel environment friendly inorganic nano green pigments, Ni1-xCuxAl2O4 (x = 0, 0.02, 0.04, 0.06, 0.08, 0.1) were successfully synthesized by simple, cost effective sol-gel method using citric acid as a gelling agent. Synthesized nano pigments were characterised by powder XRD, FT-IR, UV-DRS, SEM-EDX and TEM. Distribution of elements such as Ni, Cu, Al and O for the pigment Ni0.98Cu0.02Al2O4 was authenticated by elemental mapping analysis. The color parameters were studied using CIE-LAB parameters. It is evident from the DRS measurement that the band gap energy of NiAl2O4 (3.11eV) has been massively diminished to 2.63 eV when x = 0.02, unexpectedly changed the color of the pigment from cyan to green. While x = 0.1 the pigment color has turned into grey and the corresponding band gap condensed into 2.17 eV. Effect of mineralisers like NaF, CaF2, NH4H2PO4 and Li2CO3 on the color of Ni0.98Cu0.02Al2O4 was investigated.
关键词： chemical resistance,sol-gel,citric acid,Nickel aluminate,green pigment
更新于2025-09-23 15:22:29
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Expression of ABCA4 in the retinal pigment epithelium and its implications for Stargardt macular degeneration
摘要： Recessive Stargardt disease (STGD1) is an inherited blinding disorder caused by mutations in the Abca4 gene. ABCA4 is a flippase in photoreceptor outer segments (OS) that translocates retinaldehyde conjugated to phosphatidylethanolamine across OS disc membranes. Loss of ABCA4 in Abca4?/? mice and STGD1 patients causes buildup of lipofuscin in the retinal pigment epithelium (RPE) and degeneration of photoreceptors, leading to blindness. No effective treatment currently exists for STGD1. Here we show by several approaches that ABCA4 is additionally expressed in RPE cells. (i) By in situ hybridization analysis and by RNA-sequencing analysis, we show the Abca4 mRNA is expressed in human and mouse RPE cells. (ii) By quantitative immunoblotting, we show that the level of ABCA4 protein in homogenates of wild-type mouse RPE is about 1% of the level in neural retina homogenates. (iii) ABCA4 immunofluorescence is present in RPE cells of wild-type and Mertk?/? but not Abca4?/? mouse retina sections, where it colocalizes with endolysosomal proteins. To elucidate the role of ABCA4 in RPE cells, we generated a line of genetically modified mice that express ABCA4 in RPE cells but not in photoreceptors. Mice from this line on the Abca4?/? background showed partial rescue of photoreceptor degeneration and decreased lipofuscin accumulation compared with nontransgenic Abca4?/? mice. We propose that ABCA4 functions to recycle retinaldehyde released during proteolysis of rhodopsin in RPE endolysosomes following daily phagocytosis of distal photoreceptor OS. ABCA4 deficiency in the RPE may play a role in the pathogenesis of STGD1.
关键词： Stargardt disease,retinal pigment epithelium,lipofuscin,ABCA4,bisretinoid
更新于2025-09-23 15:21:21
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Fluorescence Microscopy of Single Liposomes with Incorporated Pigment–Proteins
摘要： Reconstitution of transmembrane proteins into liposomes is a widely used method to study their behavior under conditions closely resembling the natural ones. However, this approach does not allow precise control of the liposome size, reconstitution efficiency and the actual protein-to-lipid ratio in the formed proteoliposomes, which might be critical for some applications and/or interpretation of data acquired during the spectroscopic measurements. Here we present a novel strategy employing methods of proteoliposome preparation, fluorescent labelling, purification, and surface immobilization that allow us to quantify these properties using fluorescence microscopy at the single-liposome level and for the first time apply it to study photosynthetic pigment–protein complexes LHCII. We show that LHCII proteoliposome samples, even after purification with a density gradient, always contain a fraction of non-reconstituted protein and are extremely heterogeneous in both protein density and liposome sizes. This strategy enables quantitative analysis of the reconstitution efficiency of different protocols and precise fluorescence spectroscopic study of various transmembrane proteins in a controlled native-like environment.
关键词： Fluorescence Microscopy,Proteoliposomes,Pigment–Proteins,LHCII,Single Liposomes
更新于2025-09-23 15:21:01
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Laser Treatment of Accidental Tattoos: Experience at a Tertiary Referral Center
摘要： Background: To date, information on laser treatment of accidental tattoos is limited. Objectives: This study analyzes the efficacy and safety of quality-switched ruby, quality-switched Nd:YAG and picosecond lasers in the treatment of accidental hyperpigmentation in a larger patient cohort. To date, there is limited information on laser therapy of accidental hyperpigmentation. Methods: We conducted a retrospective systematic single-center analysis on 70 patients, which presented with accidental hyperpigmentation at the Dermatology Department of the University Hospital of Zurich between 2008 and 2017. Patients with accidental tattoos due to road injuries, explosives or other traumas and iatrogenic measures were included. We analyzed the data including laser parameters such as wavelength, energy density, spot size and intervals between the sessions. Also, the number of sessions performed and the overall success were registered. Results: We treated 38 patients by quality-switched nano- and/or picosecond laser therapy and completed the treatment in 28 cases within a mean number of 3–5 laser sessions. No complications occurred. Conclusion: We demonstrate the validity and safety of quality-switched and picosecond lasers in the treatment of accidental hyperpigmentation. Using a combination of different wavelengths and pulse lengths on the same lesion and gradually increasing the fluence in the course of the laser treatment is recommendable to increase efficacy. We observed a tendency towards faster elimination of facial accidental tattoos and/or originating from road injuries compared to tattoos located on the extremities and those caused by explosions, piercings or iatrogenic measures or consisting of metal pigment particles.
关键词： Laser treatment,Tattoo pigment,Surgical techniques,Dermatologic surgery
更新于2025-09-23 15:21:01
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Bisretinoids mediate light sensitivity resulting in photoreceptor cell degeneration in mice lacking the receptor tyrosine kinase Mer
摘要： The receptor tyrosine kinase Mer is expressed by retinal pigment epithelial (RPE) cells and participates in photoreceptor outer-segment phagocytosis, a process enabling membrane renewal. Mutations in the gene encoding MERTK cause blinding retinitis pigmentosa in humans. Targeted Mertk disruption in mice causes defective RPE-mediated phagocytosis of the outer segments, leading to deposition of autofluorescent debris at the RPE–photoreceptor cell interface, followed by photoreceptor cell degeneration. Here, we show that retinaldehyde adducts (bisretinoid fluorophores) that form in photoreceptor outer segments occupy the unphagocytosed outer segment debris that accumulates in Mertk-/- mice. Bisretinoids measured by HPLC were elevated in Mertk-/- mice compared with wild-type animals. Bisretinoids were also more abundant in albino Mertk-/- mice expressing leucine at position 450 of the isomerase RPE65 (Rpe65-Leu450) rather than the variant methionine (Rpe65-450Met) that yields lower bisretinoid levels. In Royal College of Surgeons rats having dysfunctional Mertk, bisretinoids were higher than in wild-type rats. Intensities of in vivo fundus autofluorescence were higher in Mertk-/- mice than in wild-type mice and peaked earlier in albino Mertk-/-/Rpe65-Leu450 mice than in albino Mertk-/-/Rpe65-450Met mice. Of note, the rate of photoreceptor cell degeneration was more rapid in albino Mertk-/- mice exposed to higher levels of intraocular light (albino versus pigmented mice) and in mice carrying Rpe65-Leu450 than in Rpe65-450Met mice, revealing a link between bisretinoid accumulation and light-mediated acceleration of photoreceptor cell degeneration. In conclusion, the light sensitivity of photoreceptor cell degeneration arising from Mertk deficiency is consistent with the known phototoxicity of bisretinoids.
关键词： Mertk-/-,Mertk,retinal pigment epithelium,lipofuscin,phagocytosis,retina,photodegradation,bisretinoid
更新于2025-09-23 15:21:01