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Thickness-modulated thermochromism of vanadium dioxide thin films grown by magnetron sputtering
摘要： Vanadium dioxide (VO2) films were prepared on soda-lime glass by direct current magnetron sputtering at 320 °C. Effects of film thickness on the microstructure, surface morphology and thermochromic performance of VO2 films were investigated. X-ray diffraction showed that the deposited films have strong preferred orientation of VO2 (011) lattice when the film thickness higher than 102 nm. The calculated grain sizes of VO2 films increased from 16.05 nm to 34.56 nm continuously with the increasing of film thickness. UV/VIS/NIR spectrophotometer showed that the visible transmittance deceased while the infrared transmittance switching efficiency increased as the film thickness increased from 79 nm to 264 nm. Additionally, the optical band gaps of VO2 films were in a range of 1.15 eV–1.40 eV, and the thicker film exhibited the smaller value. Moreover, the results of measured temperature-dependent electrical resistivity of these VO2 films showed that the phase-transition temperature is in a range of 53–60 °C, which is much lower than that of single-crystal VO2 (68 °C). With the film thickness increasing, the metal–semiconductor phase transition becomes more obvious. Overall, films with thickness in the range of 80–100 nm showed comparatively relatively balanced combination of visible transmittance and solar switching efficiency.
关键词： Thermochromic performance,Film thickness,Vanadium dioxide,Magnetron sputtering
更新于2025-09-23 15:23:52
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An improved algorithm for retrieving the fine-mode fraction of aerosol optical thickness. Part 2: Application and validation in Asia
摘要： Since small aerosol particles are mostly anthropogenic, the fine-mode aerosol optical thickness (fAOT) can be used to infer PM2.5 amounts. However, satellite-based fAOT products such as those from the Moderate Resolution Imaging Spectroradiometer (MODIS) are highly uncertain over land. An improved fAOT retrieval method called the look-up table–spectral deconvolution algorithm (LUT-SDA) was tested and improved using data from Asia. The improvement is achieved by accounting for seasonal changes instead of using constant annual mean values of the aerosol parameters used in the LUT-SDA derived from the Aerosol Robotic Network (AERONET) data from 2010 to 2014. Compared with the previous version of the LUT-SDA developed for Beijing, Hong Kong, and Osaka, the updated LUT-SDA generates more accurate fine-mode fractions (FMFs) with the total mean root-mean-square error (RMSE) decreasing from 0.24 to 0.18. The updated LUT-SDA was then applied to retrieve fAOT and was validated by retrievals from 45 AERONET sites over the period 2015 to 2016. A good accuracy was achieved by this method with 31% of the validation sites having > 50% of retrievals falling within the estimated error (EE) envelope ± (0.05 + 0.15 × AERONET fAOT) and 42% of the validation sites having 40–50% of retrievals falling within the EE envelope. In the total validation and comparison with the MODIS Collection 6 fAOT, the fAOT retrievals from the LUT-SDA agreed more closely with AERONET retrievals, showing a low bias. About 48% of the LUT-SDA-based fAOT retrievals fell within the EE envelope (RMSE = 0.29), while ~22% of the MODIS-based fAOT retrievals fell within the EE envelope (RMSE = 0.42). The fAOT was significantly underestimated by the MODIS algorithm in most areas of Asia with many values of zero. This study demonstrates that the refined LUT-SDA method is valid for the large-scale estimation of fAOT from satellite images.
关键词： MODIS,Aerosol optical thickness,Fine-mode fraction
更新于2025-09-23 15:23:52
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Repeatability and reproducibility of retinal nerve fibre layer thickness measurements with the iVue-100 optical coherence tomographer
摘要： Background: Accurate and repeatable measurements of the retinal nerve fibre layer (RNFL) thickness are important in the diagnosis and management of glaucoma and other disorders. Objective: To assess the repeatability and reproducibility of the iVue-100 optical coherence tomographer (OCT). Methods: The thickness of the RNFL was measured for 50 healthy participants using the iVue-100 OCT. Although both eyes per participant were measured, only right eyes were analysed here. Repeatability and reproducibility of the iVue-100 OCT were assessed using the intraclass correlation coefficient (ICC), coefficient of variation (CoV), paired t-tests and Bland-Altman analysis. Results: Good intra-observer repeatability was obtained as indicated by the ICC of observer 1 (range: 0.941 - 0.976) and observer 2 (range: 0.829 – 0.953) as well by the CoV of observer 1 (range: 0.098 – 0.137) and observer 2 (0.091 – 0.132). In terms of inter-observer reproducibility, significant differences (p< 0.05) in mean measurements between the observers were noted for the average RNFL readings and in the superior and inferior quadrants as assessed with paired t-tests. Even though significant inter-session differences were found for the average RNFL thickness and the superior quadrant (p = 0.003 and p = 0.013, respectively), excellent ICCs were obtained for inter-session reproducibility (range: 0.914 – 0.979). Conclusion: The iVue-100 OCT demonstrated good repeatability and reproducibility for RNFL thickness measurements.
关键词： Retinal nerve fibre layer thickness,optical coherence tomography,repeatability,iVue-100 OCT,reproducibility
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Symposium on Medical Measurements and Applications (MeMeA) - Rome, Italy (2018.6.11-2018.6.13)] 2018 IEEE International Symposium on Medical Measurements and Applications (MeMeA) - Extracting Features from Optical Coherence Tomography for Measuring Optical Nerve Thickness
摘要： Neurological pathologies, especially optical neuropathologies, can be studied by means of OCT (optical coherence tomography). Tomography generally allows to investigate inner structures of a tissue such as mass, and profiles of liquid flow. OCT is intended as an interferometry-based imaging technique that provides cross-sectional views of substrates. It allows to measure micro-scale cross-sectional imaging of biological tissue. While ultrasound uses sound waves, it acts like it but with a low coherence light. Optical nerve thickness has an impact on different neurological pathologies, and in particular as an indicator of epilepsy. We propose a dedicated technique for measuring optical nerve thickness and identifying its quality by means of processing front eye image in nanoscale. Experimental measurements have been performed, and a database of 10 teenagers has been used for that.
关键词： Micro and Nanotechnology,Optical nerve thickness measurement,Optical coherence Tomography,Neuro-disorders,Epilepsy,Atomic Force Microscopy,EEG
更新于2025-09-23 15:22:29
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Static and dynamic effective thickness in five-layered glass plates
摘要： In the last years, the effective thickness concept has been used to calculate deflections, stresses and modal parameters in laminated glass beams and plates, which consists of using a monolithic element with equivalent bending properties to a laminated element, i.e. the thickness of the equivalent monolithic model is time and temperature dependent because the interlayers show a viscoelastic behavior. Multi-layered laminated glass panels are those with at least three monolithic glass layers and two viscoelastic interlayers which are commonly used in floors, roofs and other applications where a high level of security is required. In this paper, a static deflection effective stiffness for a laminated glass plate consisting of three glass layers and two polymeric interlayers is derived. This static effective thickness is then extended to the frequency domain using the correspondence principle. The models are validated by static experimental tests and operational modal tests carried out on a rectangular multi-layered laminated glass plate pinned supported at the four corners.
关键词： B. Operational Modal Analysis,A. Laminated glass,C. Effective Thickness,D. Viscoelasticity
更新于2025-09-23 15:22:29
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Quartz force-sensitive resonator cluster using energy trapping theory
摘要： The quartz resonator can be used as a force-sensitive element for sensors. The resonance energy distribution of thickness-shear quartz crystal is derived and calculated using the energy trapping theory. To reduce temperature and other interference factors as well as improve force-sensitivity, a multi-electrode force-sensitive resonator cluster is designed based on resonance energy distribution results. The output frequency signals of the resonator cluster are subtracted from each other to form beat frequency signals to suppress the temperature and other interference factors using the common mode rejection principle. Next, the beat frequency signals are superimposed to improve the overall force-sensitivity of the quartz crystal resonator cluster. The experimental results show that the temperature characteristics of the quartz resonator cluster are better than the traditional single electrode resonator and that the frequency stability reaches 10?10 orders of magnitude. The overall force-frequency coef?cient of the resonator cluster increases to 9992 Hz/N.
关键词： Quartz force-sensitive resonator cluster,thickness-shear quartz crystal,energy trapping
更新于2025-09-23 15:22:29
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Swept source optical coherence tomography analysis of choroidal thickness in macular telangiectasia type 2: a case-control study
摘要： Purpose There has been a recent interest in the association of macular telangiectasia (MacTel) type 2 with central serous choroidopathy and other pachychoroid disorders. This study was performed to assess the subfoveal choroidal thickness (SFCT) in patients with MacTel type 2 and compare it with healthy controls using swept source optical coherence tomography (SS-OCT). Methods It was a retrospective case-control study performed at a tertiary eye care center. The cases constituted patients with MacTel type 2 detected over the last 2 years (April 2016 to March 2018). The controls were healthy adults with no posterior segment pathology. The patients were evaluated with color fundus photography, SS-OCT (Triton, Topcon Inc., Oakland, New Jersey, USA) and fundus fluorescein angiography. The cases were staged based on Gass and Blodi classification. SFCT was compared between the two groups. Results Sixty-five eyes of 33 patients with MacTel were included. The controls consisted of 61 eyes of 33 healthy age-matched (p = 0.81) and sex-matched (p = 0.31) adults. The mean SFCT in cases (353.0 ± 91.2 μm) was higher than controls (289.2 ± 69.0 μm), and this difference was statistically significant (p = 0.0001). The mean SFCT was different in various stages: 346.6 ± 86.3 μm (stage 2), 334.6 ± 90.2 μm (stage 3), 374.6 ± 94.0 μm (stage 4), and 294.8 ± 68.8 μm (stage 5), though this was not statistically significant (p = 0.28). Conclusions The choroid in MacTel type 2 patients was significantly thickened as compared to controls. SFCT may vary as the structural changes worsen over time.
关键词： Macular telangiectasia type 2,Swept source optical coherence tomography,Subfoveal choroidal thickness,Enhanced depth imaging
更新于2025-09-23 15:22:29
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Thickness dependence of structural, morphological and optical properties of Mn-Co-Ni-O thin films grown by chemical solution deposition on SiO2/Si(100) substrate
摘要： Mn1.56Co0.96Ni0.48O4 (MCNO) thin film with different thicknesses ranging from 180 nm to 600 nm were deposited onto a SiO2/Si(100) substrate at 600 °C by using the chemical solution deposition method. The thickness dependent structural and optical properties of the MCNO films were investigated in this study. As identified by the SEM pictures and X-ray diffraction (XRD) spectra, all samples showed polycrystalline cubic spinel structure, and the stoichiometric status is improved with growing thickness according to XRD results. Spectroscopic ellipsometry spectra were measured in this study to investigate the thickness dependent optical properties of MCNO film in the range of 300-1000 nm. The samples showed three absorption structures locating at 1.6-1.9 eV, 2.6 eV, and above 3.5 eV, corresponding to the charge transfer transition involving 2p orbitals of O2- and 3d orbitals of Mn and Co ions, respectively. The absorption structure at above 3.5 eV decreases gradually as the thickness grows, while the peak around 1.6-1.9 eV weakens slightly before it enhances again with film thickness above 430 nm, which can be explained by a combined effect of crystallinity improvement and increase in Mn4+/Mn3+ ratio.
关键词： optical properties,Mn1.56Co0.96Ni0.48O4 thin film,thickness dependence,chemical solution deposition,absorption structures
更新于2025-09-23 15:22:29
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Unusual Electronic States and Superconducting Proximity Effect of Bi Films Modulated by NbSe2 Substrate
摘要： Heterostructures of two-dimensional layered materials can be functionalized with exotic phenomena that are unpresented with each constituting component. The interface effect plays a key role in determining the electronic properties of the heterostructure, whose characterization requires a correlation with the morphology with atomic-scale precision. Here, we report an investigation on the electronic properties of few-layer Bi(110) films mediated by NbSe2 substrate. By utilizing scanning tunneling microscopy and spectroscopy, we show a significant variation of the density of states at different Bi film thicknesses, resulting in an unusual superconducting proximity effect that deviates from the conventional monotonous decay behavior. Moreover, the electronic states of the Bi films are also prominently modulated by the Moiré pattern spatially. With first-principles calculations, we illuminate these findings as the results of covalent-like quasi-bonds formed at the Bi/NbSe2 interface, which profoundly alter the charge distributions in the Bi films. Our study indicates a viable way of modulating the electronic properties of ultrathin films by quasi-covalent interfacial couplings beyond conventional van der Waals interactions.
关键词： few-layers bismuth(110),two-dimensional heterostructures,thickness dependence,scanning tunneling microscopy,density functional theory calculations,covalent-like quasi-bonds,proximity effect
更新于2025-09-23 15:22:29
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Sex-Related Variations of Retinal and Choroidal Thickness and Foveal Avascular Zone in Healthy and Diabetic Children Assessed by Optical Coherence Tomography Imaging
摘要： Purpose of the Study: The aim of this study was to investigate the presence of gender differences in the chorioretinal microvasculature of children with and without vascular pathology. Methods: Healthy and type 1 diabetic children without diabetic retinopathy underwent optical coherence tomography angiography (OCTA) and structural OCT. We measured the foveal avascular zone (FAZ) area in the superficial capillary plexus (SCP) and deep CP (DCP), central retina, and choroid thickness. Results: OCTA examination was conducted in 112 diabetic and 30 healthy children, and structural OCT in 121 diabetic children and 32 controls. DCP FAZ area in boys was significantly smaller than in girls both in diabetics (p = 0.0010) and healthy children (p = 0.0302). In diabetics, SCP FAZ area was significantly smaller in boys (p = 0.0006), analogically to controls (p = 0.0870). Central retinal thickness was significantly greater in boys compared with girls in diabetics (p = 0.0001) and controls (p = 0.1008). Conclusion: Significant differences exist in the FAZ area and retinal thickness between sexes, likely representing physiological differences. Different norms must be used for boys and girls regardless of diabetic status.
关键词： Foveal avascular zone,Diabetic status,Gender differences,Retinal thickness
更新于2025-09-23 15:22:29