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Influence of thickness on the optical properties of Sb doped ZnO thin films
摘要： Sb doped ZnO thin films having various thicknesses have been prepared onto glass substrate by using thermal evaporation method. The atomic compositions of the grown films have been determined by Energy Dispersive Analysis of X-ray (EDAX) method. The optical properties were measured by using a UV-VIS-NIR spectrophotometer (300 to 2500 nm). The EDAX analysis revealed that Sb is doped into the ZnO films. Optical properties showed high absorption coefficient (~105/cm) that direct allowed transition band gap. The optical band gap of the ZnO thin films became reduced due to the doping of Sb.
关键词： Composition,Sb doped ZnO thin films,Optical properties,Thickness
更新于2025-09-23 15:22:29
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Relationship between Peripapillary Retinal Nerve Fiber Layer Thickness Measured by Optical Coherence Tomography and Visual Field Severity Indices
摘要： Purpose: Though there are many reports regarding the structure-function relationship in glaucoma, they are too complicated to apply to the routine clinical setting. The aim of this study was to investigate the direct relationship between peripapillary retinal nerve fiber layer (RNFL) thickness measured by optical coherence tomography (OCT) and visual field (VF) severity indices computed by standard automated perimetry. Methods: This cross-sectional comparative study included 104 glaucomatous patients and 59 healthy subjects. Peripapillary RNFL thickness was measured by spectral domain (SD) and time domain (TD) OCTs. Four glaucoma VF severity indices, including mean deviation (MD), pattern standard deviation (PSD), Collaborative Initial Glaucoma Treatment Study (CIGTS) VF score, and Advanced Glaucoma Intervention Study (AGIS) VF score, were calculated using standard automated perimetry. The Pearson’s correlation coefficients (r) between the average and quadrants of peripapillary RNFL thicknesses and the four VF severity indices were calculated. Results: In glaucomatous eyes, the r value between the average RNFL thickness measured by SD OCT and each VF severity index were 0.562, -0.514, -0.577, and -0.567 for the MD, PSD, CIGTS VF score, and AGIS VF score, respectively (all p < 0.001). Among each quadrant, the inferior RNFL thickness showed the largest r value; 0.587, -0.552, -0.613, and -0.598 for the MD, PSD, CIGTS VF score, and AGIS VF score, respectively (all p < 0.001). Measurements by TD OCT showed similar strengths of association with SD OCT. Conclusions: Moderate correlation was identified between peripapillary RNFL thicknesses measured by SD/TD OCT and glaucoma VF severity indices. Among each quadrant, the inferior RNFL thickness showed the greatest association with glaucoma VF severity indices. There was no significant difference according to the type of VF severity index or the type of OCTs.
关键词： Glaucoma,Retinal nerve fiber layer thickness,Optical coherence tomography,Visual fields
更新于2025-09-23 15:22:29
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Calculating the Minimum Thickness of Glass Fuse by Zr Kα Line for Phosphorus-Containing Zircon-Refractory Material
摘要： In this paper, we take Zr Kα line as the analysis object due to the existence of overlapping phenomenon, which the zirconium La line (0.607nm) and phosphorus Ka line (0.615nm), in phosphorus-containing zircon-refractory material. We discovered and calculated the critical thickness of glass fuse by the theoretical calculation method, and we verified the feasibility of the theory. By experiment we found that critical thickness of glass fuse can be reduced by adding additives in flux. Conventional thickness of glass fuse can reaches a critical thickness by adding 20% of calcium oxide (in the form of calcium carbonate was added) in flux. This method could also increase significantly the measurement sensitivity to guarantee good result.
关键词： Zircon-refractory material,Minimum thickness,Zr Kα line
更新于2025-09-23 15:22:29
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Quantification of uncertainty in aerosol optical thickness retrieval arising from aerosol microphysical model and other sources, applied to Ozone Monitoring Instrument (OMI) measurements
摘要： Satellite instruments are nowadays successfully utilised for measuring atmospheric aerosol in many applications as well as in research. Therefore, there is a growing need for rigorous error characterisation of the measurements. Here, we introduce a methodology for quantifying the uncertainty in the retrieval of aerosol optical thickness (AOT). In particular, we concentrate on two aspects: uncertainty due to aerosol microphysical model selection and uncertainty due to imperfect forward modelling. We apply the introduced methodology for aerosol optical thickness retrieval of the Ozone Monitoring Instrument (OMI) on board NASA's Earth Observing System (EOS) Aura satellite, launched in 2004. We apply statistical methodologies that improve the uncertainty estimates of the aerosol optical thickness retrieval by propagating aerosol microphysical model selection and forward model error more realistically. For the microphysical model selection problem, we utilise Bayesian model selection and model averaging methods. Gaussian processes are utilised to characterise the smooth systematic discrepancies between the measured and modelled reflectances (i.e. residuals). The spectral correlation is composed empirically by exploring a set of residuals. The operational OMI multi-wavelength aerosol retrieval algorithm OMAERO is used for cloud-free, over-land pixels of the OMI instrument with the additional Bayesian model selection and model discrepancy techniques introduced here. The method and improved uncertainty characterisation is demonstrated by several examples with different aerosol properties: weakly absorbing aerosols, forest fires over Greece and Russia, and Sahara desert dust. The statistical methodology presented is general; it is not restricted to this particular satellite retrieval application.
关键词： OMI,Gaussian processes,OMAERO,uncertainty quantification,Bayesian model selection,aerosol optical thickness
更新于2025-09-23 15:22:29
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Evaluation of choroidal and retinal thickness measurements in adult hemodialysis patients using spectral-domain optical coherence tomography
摘要： Purpose: To assess the effect of hemodialysis on retinal and choroidal thicknesses using spectral-domain optical coherence tomography (SD-OCT). Methods: In this prospective interventional study, 25 hemodialysis patients (17 male, 8 female) were enrolled. All participants underwent high-speed, high-resolution SD-OCT (λ=840 mm; 26.000 A-scans/s; 5 μm resolution) before and after hemodialysis. Choroidal thickness was measured perpendicularly from the outer edge of the retinal pigment epithelium to the choroid-sclera boundary at the fovea and at five additional points: 500 μm and 1000 μm nasal to the fovea and 500 μm, 1000 μm, and 1500 μm temporal to the fovea. Two masked physicians performed the measurements. Choroidal and retinal thicknesses before and after hemodialysis were compared. results: The median choroidal thicknesses before and after hemodialysis were 182 μm (range, 103-374 μm) and 161 μm (range, 90-353 μm), respectively (P<0.001). The median retinal thicknesses were 246 μm (range, 179-296 μm) before and 248 μm (range, 141-299 μm) after hemodialysis (P>0.05). Systolic arterial pressure, diastolic arterial pressure, mean arterial pressure, heart rate, and ocular perfusion pressure significantly decreased after hemodialysis (P<0.001). Intraocular pressure did not vary significantly (P=0.540). conclusion: Hemodialysis seems to cause a significant decrease in choroidal thickness, whereas it has no effect on retinal thickness. This significant decrease in choroidal thickness might be due to the extensive fluid absorption in hemodialysis, which could result in decreased ocular blood flow.
关键词： Choroidal thickness,Hemodialysis,Optical coherence tomography
更新于2025-09-23 15:22:29
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Comparison of ultrasonic pachymetry and Fourier-domain optical coherence tomography for measurement of corneal thickness in dogs with and without corneal disease
摘要： Several ultrasonic and Fourier-domain optical coherence tomography (FD-OCT) pachymeters are used to measure corneal thickness in canine patients and research subjects. This study assessed the reliability of and consistency between two ultrasonic pachymetry (USP) devices, Pachette 3 and Accupach VI, as well as automated and manual measurements obtained using FD-OCT in dogs with and without corneal disease. Corneal thickness measurements were compiled from 108 dogs and analyzed using mixed effects linear regression, with Bonferonni adjustments for post-hoc comparisons, to determine the effects of age, weight and disease state. Data are presented as predicted mean ± standard error. Canine corneal disease can result in marked increases in thickness that frequently exceed the upper limits of measurement of some pachymetry devices developed for human use. In this study, the corneas of dogs with endothelial disease or injury frequently exceeded the upper limits of quantitation of 999 and 800 μm, respectively. Using values <800 μm for the Accupach VI and automated FD-OCT pachymeters, respectively. Of the two devices where measurements >1000 μm were obtained, manual FD-OCT demonstrated less variability than the Pachette 3. Corneal thickness increased linearly with age and weight with an increase of 6.9 ± 0.8 μm/year and 1.6 ± 0.38 μm/kg body weight (P < 0.005 and P = 0.038, respectively).
关键词： Corneal thickness,Corneal endothelial dystrophy,Optical coherence tomography,Ultrasonic pachymetry,Canine
更新于2025-09-23 15:21:21
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Polar metals as electrodes to suppress the critical-thickness limit in ferroelectric nanocapacitors
摘要： Enhancing the performance of nanoscale ferroelectric (FE) field-effect transistors and FE capacitors for memory devices and logic relies on miniaturizing the metal electrode/ferroelectric area and reducing the thickness of the insulator. Although size reductions improve data retention, deliver lower voltage threshold switching, and increase areal density, they also degrade the functional electric polarization. There is a critical nanometer length t(cid:1) FE below which the polarization disappears owing to depolarizing field effects. Here, we show how to overcome the critical thickness limit imposed on ferroelectricity by utilizing electrodes formed from a novel class of materials known as polar metals. Electronic structure calculations on symmetric polar-metal electrode/FE capacitor structures demonstrate that electric polarizations persist to the sub-nanometer scale with t(cid:1) ! 0 FE when a component of the polar axis in the electrode is perpendicular to the electrode/insulator interface, i.e., aligned along the direction of the polar displacements in the ferroelectric. Our results reveal the importance of interfacial dipolar coherency in sustaining the polarization, which provides a platform for in reduced dimensions. Published by AIP Publishing. https://doi.org/10.1063/1.5049607
关键词： polar metals,depolarizing field,critical thickness,ferroelectric,nanocapacitors
更新于2025-09-23 15:21:21
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Choroidal imaging biomarkers
摘要： The choroid is the vascular coat of the eye,and its role has been studied in multiple chorioretinal disorders. The recent advancements in choroidal imaging techniques including enhanced depth imaging optical coherence tomography (EDI-OCT), swept source (SS-OCT), enface OCT and OCT angiography have facilitated an in-depth analysis of choroid. The gradual shift from manual to automated segmentation and binarization methods have led to precise and reproducible measurements of choroidal parameters. These qualitative and quantitative parameters, called choroidal imaging biomarkers, have evolved over the past decade from a simple linear subfoveal choroidal thickness to more complex 3 dimensional (3-D) choroidal reconstruction thus widening the spectrum encompassing multiple parameters. These biomarkers have provided a better understanding of the pathogenesis, are helpful in diagnostic dilemmas, and in future may also help to devise treatment options. The lack of normative data, absence of standardized parameters and limitations of the imaging techniques, however, have led to ambiguity and difficulty in the interpretation of these variables. We attempt to address these lacunae in the literature and provide a basic understanding of the choroid in both health and disease using these choroidal biomarkers.
关键词： Optical coherence tomography angiography (OCTA),En-face OCT,Swept source optical coherence tomography (SS-OCT),Choroidal thickness,Choroidal vascularity index (CVI),Choroidal imaging biomarkers,Choroidal volume
更新于2025-09-23 15:21:21
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On the reliability (repeatability) of single pachymetry measures taken with specular microscope-based assessments of the human corneal endothelium
摘要： Purpose: To assess agreement between 3 measures of central corneal thickness (CCT) taken over a few minutes from nominally normal eyes with a non-contact specular microscope. Methods: 100 eyes from 100 healthy adults (with an average age of 22 y) were assessed using the Topcon 3000 P instrument to obtain a high quality image of the endothelium and pachymetry. Results: The group mean CCT values from the 1st, 2nd and 3rd measures were 0.519, 0.520 and 0.520 mm, but the sets of values could di?er by between – 0.020 mm and + 0.029 mm, i.e. between - 4.0 and + 5.6% of the average values. Paired comparisons (e.g. 2nd vs. 1st set) indicated limits of agreement (LoA) to be between - 0.020 and + 0.020 mm of the averaged value. Across the 3 measures, the averaged SD was 0.005 mm to give an estimate of the intra-subject variability (as the coe?cient of variation, COV) of 0.91% (range 0 to 2.3%). The variability in the pachymetry measures was not predictably related to the averaged values of CCT (r = 0.022) or self-reported refractive error of the subjects (r = 0.012). Some repeat pachymetry assessments obviously in-cluded the same region of the endothelium. Conclusions: Single pachymetry measures with a non-contact specular microscope are only likely to be able to generate CCT estimates within +/? 4% of the expected average values. This repeatability is comparable to single image estimates of endothelial cell density and therefore acceptable in most cases.
关键词： Cornea,Pachymetry,Human,Repeat measures,Central corneal thickness
更新于2025-09-23 15:21:21
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Improving clinical diagnosis of early-stage cutaneous melanoma based on Raman spectroscopy
摘要： BACKGROUND: Clinical diagnosis of early melanoma (Breslow thickness less than 0.8 mm) is crucial to disease-free survival. However, it is subjective and can be exceedingly difficult, leading to missed melanomas, or unnecessary excision of benign pigmented skin lesions. An objective technique is needed to improve the diagnosis of early melanoma. METHODS: We have developed a method to improve diagnosis of (thin) melanoma, based on Raman spectroscopy. In an ex vivo study in a tertiary referral (pigmented lesions) centre, high-wavenumber Raman spectra were collected from 174 freshly excised melanocytic lesions suspicious for melanoma. Measurements were performed on multiple locations within the lesions. A diagnostic model was developed and validated on an independent data set of 96 lesions. RESULTS: Approximately 60% of the melanomas included in this study were melanomas in situ. The invasive melanomas had an average Breslow thickness of 0.89 mm. The diagnostic model correctly classified all melanomas (including in situ) with a specificity of 43.8%, and showed a potential improvement of the number needed to treat from 6.0 to 2.7, at a sensitivity of 100%. CONCLUSION: This work signifies an important step towards accurate and objective clinical diagnosis of melanoma and in particular melanoma with Breslow thickness <0.8 mm.
关键词： dermatology,Raman spectroscopy,early diagnosis,Breslow thickness,melanoma
更新于2025-09-23 15:21:21