Layer Thickness Research Articles

Magneto-optical Goos–Hänchen shift in uniaxial anisotropic epsilon-near-zero metamaterials

Abstract We theoretically investigate the enhancement of the magneto-optical Goos-Hänchen (MOGH) shift in multilayer structure combining uniaxially anisotropic epsilon-near-zero (ENZ) metamaterials with magneto-optical (MO) materials. The structure enables the excitation of magneto-optical surface plasmon resonance (MOSPR) without the need for a prism or grating coupler, thereby achieving a significant enhancement of the MOGH shift. The effect of the thickness of the ENZ layer and the type of magnetic metal in this structure on the MOGH shift is also discussed. Based on the above structure, we design a high-sensitivity miniature biosensor that is used for the detection of hemoglobin concentration in human blood. The maximum sensitivity achievable with this sensor is 1.4×106 λ/RIU. The results of this investigation contribute to the development of biosensors towards miniaturization and integration.

Large-scale high purity and brightness structural color generation in layered thin film structures via coupled cavity resonance

Abstract Structural colors, resulting from the interaction of light with nanostructured materials rather than pigments, present a promising avenue for diverse applications ranging from ink-free printing to optical anti-counterfeiting. Achieving structural colors with high purity and brightness over large areas and at low costs is beneficial for many practical applications, but still remains a challenge for current designs. Here, we introduce a novel approach to realizing large-scale structural colors in layered thin film structures that are characterized by both high brightness and purity. Unlike conventional designs relying on single Fabry–Pérot cavity resonance, our method leverages coupled resonance between adjacent cavities to achieve sharp and intense transmission peaks with significantly suppressed sideband intensity. We demonstrate this approach by designing and experimentally validating transmission-type red, green, and blue colors using an Ag/SiO2/Ag/SiO2/Ag configuration on fused silica substrate. The measured spectra exhibit narrow resonant linewidths (full width at half maximum ∼60 nm), high peak efficiencies (>40 %), and well-suppressed sideband intensities (∼0 %). In addition, the generated color can be easily tuned by adjusting the thickness of SiO2 layer, and the associated color gamut coverage shows a wider range than many existing standards. Moreover, the proposed design method is versatile and compatible with various choices of dielectric and metallic layers. For instance, we demonstrate the production of angle-robust structural colors by utilizing high-index Ta2O5 as the dielectric layer. Finally, we showcase a series of printed color images based on the proposed structures. The coupled-cavity-resonance architecture presented here successfully mitigates the trade-off between color brightness and purity in conventional layered thin film structures and provides a novel and cost-effective route towards the realization of large-scale and high-performance structural colors.

Geoelectrical resistivity mapping for sustainable groundwater management in Umuahia South: Insights from vertical electrical sounding

The study of geoelectrical resistivity provides critical insights into subsurface characteristics and aquifer dynamics, particularly in regions with varying geological formations. This research investigates the geoelectrical properties of the aquifer system in Umuahia South, highlighting its significance for sustainable groundwater management. The primary aim of this study is to characterize the geoelectrical layers, assess aquifer thickness and resistivity, and evaluate the implications for groundwater resource management. Vertical Electrical Sounding (VES) was conducted across ten locations to measure the resistivity and thickness of subsurface layers. The data collected were analyzed to identify distinct geoelectrical layers, their respective resistivity values, and thicknesses. The study reveals significant variations in aquifer properties across the region, with VES 1 showcasing the largest thickness of 69.2 m and VES 9 the smallest at 5.2 m. Aquifer thickness decreases from the Benin Formation toward the Ameki and Ogwashi-Asaba Formations. Hydraulic conductivity ranges from 0.207 to 0.954 m/day, indicating varying groundwater flow potential, while transmissivity values vary from 4.965 to 30.441 m²/day, with 60% of aquifers classified as intermediate. Groundwater Potential Index (GWPI) highlights approximately 70% of the area as high potential, underscoring the need for targeted management strategies to optimize water resource extraction and sustainability. The variability in resistivity and thickness across the study area suggests significant subsurface heterogeneity. High resistivity values indicate favorable conditions for groundwater flow, particularly in areas like VES 6. Conversely, lower resistivity in locations such as VES 9 indicates potential challenges for groundwater storage. This study provides vital information on the aquifer system in Umuahia South, emphasizing the need for targeted groundwater management strategies based on the geoelectrical characteristics identified. The research contributes to a deeper understanding of the aquifer dynamics in the region and offers a framework for sustainable groundwater resource management, highlighting the importance of geoelectrical assessments.

Adopting Buffer Layer for Improving Signal‐to‐Noise Ratio of Broadband Photomultiplication Type Organic Photodetectors

AbstractThe photomultiplication type organic photodetectors (PM‐OPDs) are prepared with structure of ITO/PNDIT‐F3N/F8BT/Y6‐1O:P3HT (100:3, wt/wt)/Al, containing hole traps formed with P3HT surrounded by Y6‐1O in active layers. The PM‐OPDs exhibit external quantum efficiency (EQE)>100% in the spectral response range from 310 to 910 nm, resulting from electron tunneling injection assisted by trapped hole near ITO electrode. The incorporation of F8BT buffer layers can induce the markedly decreased dark current density (JD) due to the large electron injection barrier. The light current density (JL) of PM‐OPDs exhibits slightly decreased by inserting F8BT buffer layers due to the enhanced electron tunneling injection assisted by the more trapped holes near ITO electrode. The signal‐to‐noise ratio (SNR) of PM‐OPDs achieves over 40‐fold increment by inserting appropriate thickness of F8BT buffer layers, resulting from the markedly decreased JD and reasonably high JL. The optimal PM‐OPDs exhibit excellent photodetection capability with EQE of 4200% at 360 nm and 6600% at 850 nm, associated with the specific detectivity of 3.9 × 1011 Jones at 360 nm and 9.7 × 1011 Jones at 850 nm.

Method for Extracting Optical Element Information Using Optical Coherence Tomography

This study examines the measurement of film thickness, curvature, and defects on the surface or inside of an optical element using a highly accurate and efficient method. This is essential to ensure their quality and performance. Existing methods are unable to simultaneously extract the three types of information: thickness, curvature, and defects. Spectral-domain optical coherence tomography (SD-OCT), a non-invasive imaging technique with imaging depths down to the millimeter scale, provides the possibility of detecting the optical element components’ parameters. In this paper, we propose an error correction model for compensating delay differences in A-scan, field curvature, and aberration to improve the accuracy of system fitting measurements using SD-OCT. During data processing, we use the histogram-equalized gray stretching (IAH-GS) method to deal with strong reflections in the thin film layers inside the optics using individual A-scan averages. In addition, we propose a window threshold cutoff algorithm to accurately identify defects and boundaries in OCT images. Finally, the system is capable of rapidly detecting the thickness and curvature of film layers in optical elements with a maximum measurement depth of 4.508 mm, a diameter of 15 × 15 mm, a resolution of 5.69 microns, and a sampling rate of 70 kHz. Measurements were performed on different standard optical elements to verify the accuracy and reliability of the proposed method. To the best of our knowledge, this is the first time that thickness, curvature, and defects of an optical film have been measured simultaneously, with a thickness measurement accuracy of 1.924 µm, and with a difference between the calibrated and nominal curvature measurements consistently within 1%. We believe that this research will greatly advance the use of OCT technology in the testing of optical thin films, thereby improving productivity and product quality.

Asymmetric Glaucoma and Corresponding Hearing Impairment

Background/Objectives: This study aims to explore the potential relationship between unilateral or asymmetric glaucoma and ipsilateral hearing impairment. Methods: In this retrospective study, visual and hearing functions were assessed in patients with unilateral or asymmetric glaucoma. Correlations between retinal nerve fiber layer (RNFL) thickness, visual field mean deviation (MD) values, and pure tone audiometry (PTA) measurements across various frequencies were analyzed to explore potential associations between visual and ipsilateral hearing functions. Differences in PTA values between ears ipsilateral to the more affected glaucomatous eyes and the contralateral ears were studied for statistical significance. Results: Twenty-six patients with unilateral or asymmetric glaucoma were included in the study. Significant differences in hearing thresholds between the ears corresponding to the more severely glaucomatous eyes and the contralateral ears were found at 0.7, 1, 1.5, and 3 kHz (p < 0.05). Additionally, a statistically significant difference was observed in the speech frequencies (0.5, 0.7, 1, 1.5, 2, 3, and 4 kHz) between ears corresponding to glaucomatous or more affected glaucomatous eyes and the contralateral ears (p = 0.016). Furthermore, a moderately positive correlation was found between differences in MD and PTA values at 0.125 kHz (r = 0.50; p = 0.01). Conclusions: This study highlights a potential association between unilateral or asymmetric glaucoma and ipsilateral hearing impairment, particularly at speech-relevant frequencies. These findings underscore the importance of integrated sensory assessment in the management of glaucoma patients, suggesting that early detection and intervention for concurrent hearing loss could enhance overall quality of life.

An integrated dataset of ground hydrothermal regimes and soil nutrients monitored in some previously burned areas in hemiboreal forests in Northeast China during 2016–2022

Abstract. Under a warming climate, the occurrence of wildfires has been becoming increasingly more frequent in boreal forests and Arctic tundra over the last few decades. Wildfires can cause radical changes in forest ecosystems and the permafrost environment, such as the irreversible degradation of permafrost, succession of boreal forests, rapid and massive losses of soil carbon stock, and increased periglacial geohazards. Since 2016, we have gradually and more systematically established a network for studying soil nutrients and monitoring the hydrothermal state of the active layer and near-surface permafrost in the northern Da Xing'anling Mountains in Northeast China. Soil moisture content (depth of 0–9.4 m), soil organic carbon content (0–3.6 m), total nitrogen content (0–3.6 m), and total phosphorus and potassium content (0–3.6 m) datasets were obtained in 2016 via field sampling and subsequent laboratory tests. Ground temperature (0–20 m) and active layer thickness (2017–2022) datasets were obtained using thermistor cables that were permanently installed in boreholes or interpolated with these temperatures. The present data can be used to simulate changes in permafrost features under a changing climate and wildfire disturbances and to explore the changing interactive mechanisms of the fire–permafrost–carbon system in hemiboreal forests. Furthermore, they can provide baseline data for studies and action plans to support the carbon neutralization initiative and assessment of the ecological safety and management of the permafrost environment. These datasets can be easily accessed via the National Tibetan Plateau/Third Pole Environment Data Center (https://doi.org/10.11888/Cryos.tpdc.300933, Li and Jin, 2024).

Data-driven AI for the automated classification of the isothermal heat-treated thermal barrier coatings using pulsed infrared thermography

Abstract Thermal barrier coating (TBC) is a multilayer coating applied to metallic structures exposed to high temperatures, such as aero-engine parts and gas turbine blades. These thermally insulating materials are used to extend the component life by minimizing the high-temperature exposure of structural components. As a result of the high-temperature oxidation tests, a thermally grown oxide (TGO) layer formed at the interface between the ceramic topcoat layer and the bond coat layer. The primary cause of TBC performance decline and structure failure is the growth of the oxide layer. Hence, it is crucial to regularly monitor the formation of the oxide layer and the degradation of coatings. This can be achieved by developing coating-life prediction models, which are vital for quality control, health monitoring of TBCs, maintenance decision-making, and the prevention of catastrophic failures. Existing methods for life estimation, which are dependent on empirical methods and microstructural analysis, often fail due to various material compositions and service conditions. This study proposes an automated classification of iso-thermal heat-treated TBC samples using temperature data, which helps in predicting the TBC life and monitoring the TBC degradation. TBC-coated samples are isothermal heat-treated at 1000 °C, and the initial growth of TGO is monitored using a non-destructive thermal imaging technique. Identifying distinctive features in each class corresponding to layer thickness measurement and service hours is challenging and time-consuming. So, we integrate data-driven AI models and feature extraction techniques to interpret complex thermal patterns. The performance of deep learning models and classical machine learning models demonstrates that our method can achieve maximum classification accuracy and F1-score of 89.2% and 89.0%, respectively. This automated classification framework promises a powerful tool for predictive maintenance and remaining useful lifetime estimation of hot section components reliant on TBCs.

Thin film lithium niobate electro-optic modulator with reduced half-wave voltage length product through design

This paper aims at shortening electrode spacing in a thin film lithium niobate (TFLN) electro-optic modulator (EOM) while avoiding an increase in metal absorption loss, thereby reducing the half-wave voltage length product (V π ⋅L). Through numerical simulations, we find that metal absorption loss reaches its peak values when the optical modes of the metal-clad dielectric waveguide and ridged waveguide hybridize. This negative effect can be mitigated by adjusting the electrode width to modify the optical mode of the metal-clad dielectric waveguide. In addition, we raise the vertical position of the electrodes to further mitigate metal absorption loss and reduce the electrode spacing. By calculating the optimal buffer layer thickness for two crystal axis orientations, our findings reveal a 19% reduction in V π ⋅L at conventional crystal axis orientation (θ=±90∘) and a 16% decrease at unconventional crystal axis orientation (θ=54∘). Notably, V π ⋅L at unconventional crystal axis orientation is 5% lower than at conventional crystal axis orientation. These findings demonstrate the effectiveness of geometric configuration optimization toward enhancing the efficiency and performance of the TFLN EOM.

Three-dimensional numerical study on reservoir sediment flushing through an initially covered bottom tunnel

Sediment flushing through bottom tunnels has been widely applied in engineering practice to alleviate reservoir sedimentation. However, there is limited understanding of whether flushing can be accomplished once the tunnel intake is covered by deposited sediment. Here, a three-dimensional model is used to resolve the hydro-sediment-morphodynamic processes and reveal the physical mechanism for the occurrence of reservoir sediment flushing through an initially covered bottom tunnel. The results demonstrate that the reservoir water level and initial cover layer thickness have a significant impact on the pressure difference between tunnel inlet and outlet and the resistance of tunnel walls, determining the momentum of the water-sediment mixture. If water level is low or cover layer is thick, the pressure is not sufficient to overcome the resistance. The momentum tends to zero, and tunnel blockage occurs. If water level is high or cover layer thickness is small, the scour hole depth will exceed the cover layer thickness and the sediment concentration in tunnel decreases. The resistance is reduced significantly, and sediment flushing is accomplished. The present work facilitates enhanced understanding of sediment flushing, thereby informing reservoir engineers and managers of potential approaches to benefit maximization and sustainable sediment management.

Research of Dynamic Processes in a Layer During Collision With an Impactor

Abstract The article concerns the modeling of the transverse impact of an impactor (test sample) on the surface of an infinite elastic layer. The Laplace transform with respect to time and the Hankel transform with respect to the radius for the axisymmetric case were applied. The propagation of elastic waves in the layer and local deformations in the contact zone are taken into account. Impact force, impact time and the coefficient of restitution were examined. The results are compared with the elastic half-space. The calculations carried out showed that for layer thicknesses of more than five impactor diameters, the layer can be considered as a half-space.

Design and performance exploration of Pb-free low-cost all-inorganic perovskite-inspired CuAgBi2I8 solar cells: theoretical approach

Abstract Organic–inorganic halide perovskites have demonstrated great potential for photovoltaic applications owing to their unprecedented optoelectronic properties and low manufacturing costs. However, the commercialization of this technology is hindered by its thermal instability and inherent toxicity. In this study, SCAPS-1D simulation software was used to study the performance of solar cell based on CuAgBi2I8, which is a novel inorganic non-toxic lead-free perovskite-inspired material. Different electron transport layers (TiO2, In2S3, ZnO, Zn0.75Mg0.25O,SnO2 and SrTiO3) and hole transport layers (CuI, PEDOT:PSS, CuSCN and Cu2O) were studied, our research indicated that SnO2 and NiO formed the optimal combination. Further analysis revealed that the optimal absorption layer thickness was 900 nm, the absorption layer doping concentration should be less than 1 × 1013 cm−3 and the defect density should be less than 1 × 1014 cm−3. The optimal thickness of SnO2 and NiO was 30 nm, the optimal doping concentration of SnO2 and NiO was 1 × 1020 cm−3, the defect density of absorber layer/SnO2 and absorber layer/NiO interfaces should be less than 1 × 1012 cm−3, C was the optimal back electrode material. Consequently, the optimal device configuration was identified as FTO/SnO2/CuAgBi2I8/NiO/C, the efficiency was improved from original 2.76% to 19.10% after above optimization. These results indicate that solar cell with CuAgBi2I8 as the absorber layer is a potential alternative to organic–inorganic lead halide perovskite solar cells.

Retinal and Macular Changes in Pregnant Women of Advanced Maternal Age: A Retrospective Study.

Aims/Background Pregnancy may cause physiological and pathological changes in multiple organs in a woman's body, including the heart, liver, and eyes. With rapid advances in societies and economies, the proportion of advanced maternal age (AMA) women has significantly increased. Here, we aimed to investigate the changes in arteriole retinal diameter, venule diameter, macular layer thickness, and arteriole to venule ratio (AVR) in this population. Methods This retrospective case-control study included 523 pregnant women (1046 eyes) and was performed on both eyes. In total, 318 subjects were included in the AMA group, and 205 subjects were included in the non-AMA group. Nonmydriatic fundus photography and optical coherence tomography (OCT) were performed on the same day, and the results were analyzed for the central retinal arteriolar equivalent (CRAE), central retinal venular equivalent (CRVE), AVR, and macular thickness (9 subfields) by integrative vessel analysis and automatic OCT software. Results In both eyes, the CRAE was significantly lower in the AMA group than that in the non-AMA group (p < 0.05; respectively). The CRVE in the AMA group was higher than that in the non-AMA group (p < 0.001; respectively). Compared to the non-AMA group, the AMA group exhibited a significant reduction in macular thickness within the inner nasal, outer nasal, and inner temporal subfields of both eyes (p < 0.05; respectively). Age was significantly correlated with CRVE and AVR in both eyes of pregnant women (CRVE: p < 0.0001; AVR: p < 0.01). Conclusion This study reports variations in the diameter of the retinal vasculature and the thickness of the macula in women of AMA. It is important to consider these changes when interpreting the adverse eye outcomes experienced by women of AMA.

Investigation of a Hydrophobic Sputtered Cu Electrode to Electrocatalyze CO2 Towards a C2+ Product: The Effect of Substrate and Catalyst Thickness

The overuse of fossil fuels has resulted in massive CO2 emissions, causing global environmental problems. Renewable energy-driven electrocatalysis, which can convert CO2 into fuels and chemicals, is considered an emerging technology for carbon resource recycling. Cu-based catalysts sputtered on hydrophobic carbon paper and a polytetrafluoroethylene (PTFE) membrane were comparatively investigated, while the effect of the thickness of the Cu sputtering layer on the electrocatalytic CO2 reduction performance was investigated. Additionally, the effect of substrate properties on the distribution and morphology of sputtered Cu metal was investigated by SEM and XRD. With carbon paper as the substrate, the highest FEC2+ achieved was 70% at 200 mA/cm2, while the maximum value of FEC2+ on the Cu/PTFE electrode was realized with a Cu thickness of 400 nm (72%). Additionally, the PTFE substrate demonstrated a better inhibiting effect on HER, with a lower FEH2 and high FEC2+ over different applied current densities.

Development of craquelure patterns in paintings on canvas

Canvas paintings are layered structures composed of canvas support sized with animal glue, a preparatory layer of the ground, and paint and varnish layers on the top. Preventing or limiting humidity-induced stresses in these structures requires an understanding of the relevant processes and risks. A three-dimensional model of a canvas painting was used to analyse stresses and crack development in the two-layer structure comprised of a glue-sized canvas on a wooden stretcher with a layer of stiff chalk-glue ground representing a pictorial layer in historic canvas paintings. The model was subjected to a large relative humidity fall which induced shrinkage of the glue-sized canvas. The modelling revealed that when a stretcher with flexible wooden bars is considered, high tensile stresses arise in the ground layer at the corners of the painting, and cracks are formed in these areas in the direction perpendicular to the painting’s diagonal. Ratios of critical distances between cracks to the ground layer thickness for which stresses in the midpoints between the cracks dropped to below the level inducing fracture in the material were estimated for various magnitudes of the relative humidity drop and thicknesses of the ground layer. Increasing ground layer thickness limits the hygric response of the sized canvas and makes the paintings less vulnerable to humidity variations. The ratio of stress along the diagonal calculated for painting with one crack to the solution without cracks was described by the double Lorentz function. A simple procedure of calculating stress variations along the diagonal—using the function—on a sequential addition of cracks was developed. Cracks in central parts of canvas painting were found to be induced by permanent cumulative drying shrinkage of the oil-based paints and grounds due to the evolution of the molecular composition of the oil binder. The outcome of the modelling indicated that the risk of cracking of the pictorial layers in canvas paintings due to drops in ambient relative humidity was small.

Novel Structures for PV Solar Cells: Fabrication of Cu/Cu2S-MWCNTs 1D-Hybrid Nanocomposite

The production of cost-effective novel materials for PV solar cells with long-term stability, high energy conversion efficiency, enhanced photon absorption, and easy electron transport has stimulated great interest in the research community over the last decades. In the presented work, Cu/Cu2S-MWCNTs nanocomposites were produced and analyzed in the framework of potential applications for PV solar cells. Firstly, the surface of the produced one-dimensional Cu was covered by Cu2S nanoflake. XRD data prove the formation of both Cu and Cu2S structures. The length and diameter of the one-dimensional Cu wire were 5–15 µm and 80–200 nm, respectively. The thickness of the Cu2S nanoflake layer on the surface of the Cu was up to 100 nm. In addition, the Cu/Cu2S system was enriched with MWCNTs. MWCNs with a diameter of 50 nm interact by forming a conductive network around the Cu/Cu2S system and facilitate quick electron transport. Raman spectra also prove good interfacial coupling between the Cu/Cu2S system and MWCNTs, which is crucial for charge separation and electron transfer in PV solar cells. Furthermore, UV studies show that Cu/Cu2S-MWCNTs nanocomposites have a wide absorption band. Thus, MWCNTs, Cu, and Cu2S exhibit an intense absorption spectrum at 260 nm, 590 nm, and 972 nm, respectively. With a broad absorption band spanning the visible–infrared spectrum, the Cu/Cu2S-MWCNTs combination can significantly boost PV solar cells’ power conversion efficiency. Furthermore, UV research demonstrates that the plasmonic character of the material is altered fundamentally when CuS covers the Cu surface. Additionally, MWCN-Cu/Cu2S nanocomposite exhibits hybrid plasmonic phenomena. The bandgap of Cu/Cu2S NWs was found to be approximately 1.3 eV. Regarding electron transfer and electromagnetic radiation absorption, the collective oscillations in plasmonic metal-p-type semiconductor–conductor MWCNT contacts can thus greatly increase energy conversion efficiency. The Cu/Cu2S-MWCNTs nanocomposite is therefore a promising new material for PV solar cell application.

Macular Alterations in a Cohort of Caucasian Patients Affected by Retinitis Pigmentosa

Objectives: Our objective was to investigate the prevalence of macular complications detected by spectral-domain optical coherence tomography (SD-OCT) in a large Caucasian cohort of RP patients, highlight the major alterations in chorioretinal structure, and compare the macular structural changes in eyes affected by retinal dystrophies with those in healthy controls. Methods: This was an observational, retrospective, and cross-sectional study. Three hundred and seven patients with RP were consecutively enrolled and underwent clinical assessment. In particular, SD-OCT images were used to ascertain the morphology of the posterior pole of patients with RP by evaluating the residual ellipsoid zone (EZ), the volume and thickness of the outer nuclear layer (ONLT), and subfoveal choroid thickness (SCT). At the same time, the pathological finding that the patients’ vision was reduced under treatment was analyzed. Results: A total of 436 eyes of 218 patients with RP were studied. Considering all of the eyes studied, 103 had cystoid macular edema (CME) (23.62%), 123 (28.21%) had vitreomacular traction (VMT), and 199 (45.75%) had epiretinal membranes (ERMs). There were also 12 (2.75%) cases of lamellar macular holes (LMHs), of which 3 (1.38% of all patients) cases were bilateral. Only 137 eyes (31.42%) did not have the above-mentioned alterations. SCT was significantly reduced compared to that of the control group (193.03 µm ± 67.90 SD vs. 295 µm ± 69.04 SD), while the foveal central macular thickness (FCMT) was greater (270.91 μm ± 74.04 SD vs. 221 µm ± 37.25 SD). Conclusions: This research highlights the high incidence of macular complications. The results of our study indicate the importance of regular monitoring of RP patients and early intervention to avoid further complications in this group of subjects with severe visual field impairment to avoid further central vision loss.

Optical coherence tomography angiography of peripapillary vessel density in non-arteritic anterior ischemic optic neuropathy and demyelinating optic neuritis

BackgroundIn cases of optic disc edema or a pale optic disc, distinguishing an episode of optic neuritis (ON) from that of non-arteritic anterior ischemic optic neuropathy (NAION) during a clinical examination is challenging. Optical coherence tomography angiography (OCTA) can reveal differences in peripapillary vascular network structures and provide biomarkers for differential diagnosis.MethodsA total of 23 eyes with NAION, 22 eyes with demyelinating ON (DON), and 27 eyes from healthy participants were imaged using OCTA to observe the radial peripapillary capillaries (RPCs). Optical coherence tomography was used to measure peripapillary retinal nerve fiber layer (RNFL) thickness and the macular ganglion cell complex (mGCC). Data for all patients were recorded at 2–3 weeks and more than 3 months after the symptom onset.ResultsA total of 23 affected eyes from 23 patients with NAION (average age 52.17 ± 7.92 years), 22 eyes from 22 patients with demyelinating optic neuritis (DON) (average age 47.88 ± 19.24 years), and 27 eyes from 27 healthy individuals (average age 46.43 ± 14.08 years) were included in the study. There were no significant differences in sex, age, and eye laterality between any two groups (F = 0.968, 0.475, 0.870; p &amp;gt; 0.05). Throughout the course of NAION and DON, the superior RPC, superior mGCC, and peripapillary RNFL decreased with time (p &amp;lt; 0.05). In contrast, the inferotemporal RPC and inferior mGCC did not decrease from the acute to chronic stage in NAION (t = 1.639, 0.834, p = 0.117, 0.413). Compared with the normal group, patients with NAION and DON exhibited a sharp reduction in the average RPC, RNFL, and GCC from the acute to the chronic stage (p &amp;lt; 0.05). Patients with DON exhibited a significant decrease in the inferotemporal RPC and inferior mGCC compared with the patients with NAION (p &amp;lt; 0.05). In contrast, there were no significant differences in the inferior mGCC at the chronic stage between the patients with NAION and those with ON (t = 2.547, p = 0.093).ConclusionVarious structural and microvascular changes were observed in patients with NAION and ON, indicating distinct features of the optic nerve during the different stages of NAION and ON. Peripapillary vascular density, measured using spectral domain OCT (SD-OCT), may be a biomarker to distinguish NAION from ON.

Optimization of MBE-grown GaSb buffer on GaAs substrates for infrared detectors

The aim of this work was to improve the quality of the GaSb buffer layers on GaAs substrates using the molecular beam epitaxy (MBE) technology. The high quality of the GaSb buffer layers is one of the most important elements enabling the synthesis of good quality of type II superlattices (T2SL) structures for infrared applications. The main challenges in this regard are: compensation of the difference in lattice constants between GaAs and GaSb and obtaining the highest achievable surface quality of the final GaSb layer. In the literature, many authors describe different techniques to obtain the best quality of a GaSb buffer layer. In this work, we present the results of HRXRD, AFM, TOF-SIMS, SEM, and Nomarski optical microscope measurements obtained for 2 μm thick GaSb buffer layers. The GaSb layers are made according to different techniques and these results are compared with a GaSb buffer construction technique according to our own technology. During the processes, we also obtained an unintentional structure of one of the buffer layers, which allowed us to obtain very good results in terms of surface structure and crystallographic quality where FWHM in ωRC scan was equal to 138 arcsec and RMS 0.20 nm proving that there is still a lot of work to be done in this area.

Controlled Spalling of 4H Silicon Carbide with Investigated Spin Coherence for Quantum Engineering Integration.

We detail scientific and engineering advances which enable the controlled spalling and layer transfer of single crystal 4H silicon carbide (4H-SiC) from bulk substrates. 4H-SiC's properties, including high thermal conductivity and a wide bandgap, make it an ideal semiconductor for power electronics. Moreover, 4H-SiC is an excellent host of solid-state atomic defect qubits for quantum computing and quantum networking. Because 4H-SiC substrates are expensive (due to long growth times and limited yield), techniques for removal and transfer of bulk-quality films are desirable for substrate reuse and integration of the separated films. In this work, we utilize updated approaches for stressor layer thickness control and spalling crack initiation to demonstrate controlled spalling of 4H-SiC, the highest fracture toughness crystal spalled to date. We achieve coherent spin control of neutral divacancy (VV0) qubit ensembles and measure a quasi-bulk spin T2 of 79.7 μs in the spalled films.