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Investigations of properties of opal-like photonic crystals using combined methods
摘要： We propose a technique that combines atomic force microscopy, optical spectrophotometry and di?raction method for characterization of photonic crystals. These materials are promising for the creation of various devices, as well as for the observation of new e?ects due to their unique properties. Photonic crystals were synthesized by self-assembly of colloidal silica particles with low deviation in size. It is shown that the developed technique allows to increase the accuracy of determining the parameters of the photonic crystal.
关键词： diffraction method,photonic crystals,self-assembly,colloidal silica particles,atomic force microscopy,optical spectrophotometry
更新于2025-09-09 09:28:46
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[IEEE 2018 International Symposium ELMAR - Zadar, Croatia (2018.9.16-2018.9.19)] 2018 International Symposium ELMAR - 3D Localization of Neurons in Bright-Field Histological Images
摘要： In this paper, we present a method for inferring the depth of neurons found in a bright-field microscopic image of a histological section of a human brain, digitized at high resolution in multiple planes along the z-axis. Individual neuron bodies are segmented and tracked throughout the depth of the whole image stack and placed at the appropriate z-level in the stack based on variations in image sharpness.
关键词： Digital Microscopy,Immunohistochemistry,High-resolution Imaging
更新于2025-09-09 09:28:46
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Nonlinear optical susceptibility of atomically thin WX2 crystals
摘要： We have studied tungsten diselenide (WSe2) and tungsten disulfide (WS2) monolayer materials in second harmonic generation spectroscopy and microscopy experiments. Ultra-broadband continuum pulses served as the fundamental beam while its second harmonic spectrum in the visible and ultraviolet (UV) range was detected and analyzed with a better than 0.3 nm spectral resolution (< 2 meV). We provide dispersion data and absolute values for χ(2) for the materials within a photon energy range of 2.3–3.2 eV. Fine spectral features that were detected within the dispersion data for the optical nonlinearities indicate the impact of near bandgap exciton transitions. The fundamental bandgap of 2.35 eV and exciton binding energy of 0.38 eV were determined from the measurements for WS2 monolayers while the corresponding values in WSe2 monolayers were 2.22 eV and 0.71 eV. Ranges for the absolute values of the sheet nonlinearity for WS2 and WSe2 are shown to be 0.58–1.65 × 10?18 m2/V and 0.21–0.92 × 10?18 m2/V, correspondingly.
关键词： Nonlinear spectroscopy and microscopy,Transition metal dichalcogenides,Two-dimensional semiconductors,Second harmonic generation,Optical nonlinearity in semiconductors,Monolayer crystals,Optics at interfaces
更新于2025-09-09 09:28:46
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Shining New Light on the Structural Determinants of Cardiac Couplon Function: Insights From Ten Years of Nanoscale Microscopy
摘要： Remodelling of the membranes and protein clustering patterns during the pathogenesis of cardiomyopathies has renewed the interest in spatial visualisation of these structures in cardiomyocytes. Coincidental emergence of single molecule (super-resolution) imaging and tomographic electron microscopy tools in the last decade have led to a number of new observations on the structural features of the couplons, the primary sites of excitation-contraction coupling in the heart. In particular, super-resolution and tomographic electron micrographs have revised and refined the classical views of the nanoscale geometries of couplons, t-tubules and the organisation of the principal calcium handling proteins in both healthy and failing hearts. These methods have also allowed the visualisation of some features which were too small to be detected with conventional microscopy tools. With new analytical capabilities such as single-protein mapping, in situ protein quantification, correlative and live cell imaging we are now observing an unprecedented interest in adapting these research tools across the cardiac biophysical research discipline. In this article, we review the depth of the new insights that have been enabled by these tools toward understanding the structure and function of the cardiac couplon. We outline the major challenges that remain in these experiments and emerging avenues of research which will be enabled by these technologies.
关键词： couplons,localization microscopy,super-resolution,ryanodine receptors,cardiac muscle
更新于2025-09-09 09:28:46
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Efficient excitation of dye molecules for single photon generation
摘要： A reliable single photon source is required for many aspects of quantum technology. Organic molecules are attractive for this application because they can have high quantum yield and can be photostable, even at room temperature. To generate a photon with high probability, a laser must excite the molecule efficiently. We develop a simple model for that efficiency and discuss how to optimise it. We demonstrate the validity of our model through experiments on a single dibenzoterrylene (DBT) molecule in an anthracene crystal. We show that the excitation probability cannot exceed 75% at room temperature, but can increase to over 99% if the sample is cooled to liquid nitrogen temperature. The possibility of high photon generation efficiency with only modest cooling is a significant step towards a reliable photon source that is simple and practical.
关键词： single molecules,photon anti-bunching,single photon source,quantum optics,confocal microscopy
更新于2025-09-09 09:28:46
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4H-SiC 1200 V Junction Barrier Schottky Diodes with High Avalanche Ruggedness
摘要： A state-of-the art family of 1200 V junction barrier Schottky (JBS) diodes was developed. These devices are highly competitive in switching applications thanks to low specific series resistance (1.8 mΩ.cm2 at current rating) and low capacitive charge (1420 nC.cm-2 at 800 V). A uniform avalanche distribution over the active area combined with an optimized high-voltage termination provides industry-leading UIS capabilities. Stringent reliability tests were performed to meet the qualification requirements for the industrial market.
关键词： junction barrier Schottky diode,4H-SiC,emission microscopy,TCAD,unclamped inductive switching
更新于2025-09-09 09:28:46
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Classification of Limbal Stem Cell Deficiency Using Clinical and Confocal Grading
摘要： To grade the severity of limbal stem cell deficiency (LSCD) based on the extent of clinical presentation and central corneal basal epithelial cell density (BCD). This is a retrospective observational comparative study of 48 eyes of 35 patients with LSCD and 9 eyes of 7 normal subjects (controls). Confocal images of the central cornea were acquired. A clinical scoring system was created based on the extent of limbal and corneal surface involvement. LSCD was graded as mild, moderate, and severe stages based on the clinical scores. The degree of BCD reduction was given a score of 0 to 3. Compared with BCD in controls, BCD decreased by 23.0%, 40.4%, and 69.5% in the mild, moderate, and severe stages of LSCD classified by the clinical scoring system, respectively. The degree of BCD reduction was positively correlated with larger limbal and corneal surface involvement and when the central visual axis was affected (all P # 0.0005). Mean corrected distance visual acuity logarithm of the minimum angle of resolution was 0.0 6 0.0 in control eyes, 0.2 6 0.5 in mild LSCD, 0.6 6 0.4 in moderate LSCD, and 1.6 6 1.1 in severe LSCD (P , 0.0001). There was a significant correlation between a higher clinical score and corrected distance visual acuity logarithm of the minimum angle of resolution (rho = 0.82; P , 0.0001) and a greater decrease in BCD (rho = 20.78; P , 0.0001). A clinical scoring system was developed to assess the extent of clinical presentation of LSCD. A classification system to grade the severity of LSCD can be established by combining the BCD score with the clinical score.
关键词： diagnosis,classification system,limbal stem cell,in vivo confocal microscopy,limbal stem cell deficiency
更新于2025-09-09 09:28:46
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Characteristics of krypton ion emission from a gas field ionization source with a single atom tip
摘要： A scanning ion beam instrument equipped with a gas ?eld ionization source (GFIS) has been commercialized, but only helium and neon are currently available as GFISs. The characteristics of krypton ion emission from a single atom tip (SAT) have not been reported yet. In this study, the characteristics of krypton ion emission were investigated by ?eld ion microscopy. At 65 K, the krypton ion emission current reached approximately 40 pA, which is 1 order of magnitude higher than that at 130 K. As the krypton gas pressure was increased, the krypton ion current increased. At a pressure of 0.3 Pa, the emission current was anticipated to reach 200 pA, which may be high enough for nanofabrication. The variation of the krypton ion current was as low as 5% in one hour. We concluded that a krypton ion beam instrument equipped with a GFIS will be a powerful tool for nanofabrication.
关键词： gas field ionization source,field ion microscopy,nanofabrication,single atom tip,krypton ion emission
更新于2025-09-09 09:28:46
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Faster, sharper, and deeper: structured illumination microscopy for biological imaging
摘要： Structured illumination microscopy (SIM) allows rapid, super-resolution (SR) imaging in live specimens. We review recent technical advances in SR-SIM, with emphasis on imaging speed, resolution, and depth. Since its introduction decades ago, the technique has grown to offer myriad implementations, each with its own strengths and weaknesses. We discuss these, aiming to provide a practical guide for biologists and to highlight which approach is best suited to a given application.
关键词： Structured illumination microscopy,resolution,biological imaging,super-resolution imaging,imaging speed,depth
更新于2025-09-09 09:28:46
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Content-aware image restoration: pushing the limits of fluorescence microscopy
摘要： Fluorescence microscopy is a key driver of discoveries in the life sciences, with observable phenomena being limited by the optics of the microscope, the chemistry of the fluorophores, and the maximum photon exposure tolerated by the sample. These limits necessitate trade-offs between imaging speed, spatial resolution, light exposure, and imaging depth. In this work we show how content-aware image restoration based on deep learning extends the range of biological phenomena observable by microscopy. We demonstrate on eight concrete examples how microscopy images can be restored even if 60-fold fewer photons are used during acquisition, how near isotropic resolution can be achieved with up to tenfold under-sampling along the axial direction, and how tubular and granular structures smaller than the diffraction limit can be resolved at 20-times-higher frame rates compared to state-of-the-art methods. All developed image restoration methods are freely available as open source software in Python, FIJI, and KNIME.
关键词： isotropic resolution,image restoration,sub-diffraction structures,deep learning,content-aware,fluorescence microscopy
更新于2025-09-09 09:28:46