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Noncontact Imaging of Ion Dynamics in Polymer Electrolytes with Time-Resolved Electrostatic Force Microscopy
摘要： Ionic transport processes govern performance in many classic and emerging devices, ranging from battery storage to modern mixed-conduction electrochemical transistors. Here, we study local ion transport dynamics in polymer films using time-resolved electrostatic force microscopy (trEFM). We establish a correspondence between local and macroscopic measurements using local trEFM and macroscopic electrical impedance spectroscopy (EIS). We use polymer films doped with lithium bis(trifluoromethane)sulfonimide (LiTFSI) as a model system where the polymer backbone has oxanorbornenedicarboximide repeat units with an oligomeric ethylene oxide side chain of length n. Our results show that the local polymer response measured in the time domain with trEFM follows stretched exponential relaxation kinetics, consistent with the Havriliak-Negami relaxation we measure in the frequency-domain EIS data for macroscopic samples of the same polymers. Furthermore, we show that the trEFM results capture the same trends as the EIS results — changes in ion dynamics with increasing temperature, increasing salt concentration, and increasing volume fraction of ethylene oxide side chains in the polymer matrix evolve with the same trends in both measurement techniques. We conclude from this correlation that trEFM data reflect, at the nanoscale, the same ionic processes probed in conventional EIS at the device level. Finally, as an example application for emerging materials syntheses, we use trEFM and infrared photoinduced force microscopy (PiFM) to image a diblock copolymer electrolyte for next-generation solid-state energy storage applications.
关键词： scanning probe microscopy,ion dynamics,polymer electrolyte,diblock imaging,non-contact AFM
更新于2025-09-04 15:30:14
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Nanoapertures without nanolithography
摘要： We propose and experimentally demonstrate the implementation of lithography-free nano-apertures on optical fibers. By sputtering metallic nanofilms onto the end face of step index fibers that contain central nano-channels, fiber-integrated nano-apertures are instantaneously implemented without the use of any kind of lithographic step. In accordance with simulations, the experiments show diffraction-limited nano-spots in the far-field at the location of the nano-aperture for sufficiently thick films. We reproducibly implement a series of devices by sputtering Al and Pt nano-films, reaching aperture diameters as small as 40 nm and showing spectrally broadband operation. Due to its simplicity, scalability and potential for large-scale production the nano-aperture enhanced fiber concept will be highly relevant for lab-on-a-fiber applications and for the development of future fiber-based nano-probes with high spatial resolutions.
关键词： lab-on-a-fiber,hybrid fibers,nanofabrication,scanning near-field optical microscopy (SNOM),nanoapertures
更新于2025-09-04 15:30:14
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Label-free detection of brain invasion in meningiomas by multiphoton microscopy
摘要： Brain invasion in meningiomas relates to the poor prognosis. Therefore, accurate detection and treatment of brain invasion are of particular importance. In this study, multiphoton microscopy (MPM) was introduced for label-free detection of brain invasion in meningiomas by the combination of the two-photon excited fluorescence imaging, second-harmonic generation imaging and spectral imaging. Results show that MPM has the ability to morphologically and spectrally identify brain invasion in meningiomas. What is more, the intensity ratios of the cerebral cortex over meningiomas at 475 nm, 511 nm and 540 nm were extracted as quantitative indicators for differentiating meningioma from surrounding normal cerebral cortex tissue. Together with custom-developed image processing algorithms, MPM could further identify the tumor boundary. With miniaturization and optimization of probes and optical fiber for in vivo imaging, combined with a laser ablation system, MPM would be used in an operating room for both the diagnosis and treatment of brain invasion in meningiomas.
关键词： brain invasion,two-photon excited fluorescence,multiphoton microscopy,second harmonic generation
更新于2025-09-04 15:30:14
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Polymorph-specific distribution of binding sites determines thioflavin-T fluorescence intensity in α-synuclein fibrils
摘要： Thioflavin-T (ThT) is the most commonly used fluorescent dye for following amyloid formation semi-quantitatively in vitro, specifically probing the fibrillar cross-b-sheet content. In recent years, structural polymorphism of amyloid fibrils has been shown to be an important aspect of amyloid formation, both in vitro and in neurodegenerative diseases. Therefore, understanding ThT–amyloid interactions in the context of structural polymorphism of amyloids is necessary for correct interpretation of ThT fluorescence data. Here we study the influence of fibril morphology on ThT fluorescence and ThT binding sites, with two morphologically distinct but chemically identical a-synuclein polymorphs. In ThT fluorescence assays the two polymorphs show type-specific fluorescence intensity behaviour although their b-sheet content has been shown to be similar. Further, fluorescence lifetime measurements of fibril-bound ThT reveal the presence of at least two qualitatively different ThT binding sites on the polymorphs. The relative distributions of the binding sites on the fibril surfaces appear to be morphology dependent, thus determining the observed polymorph-specific ThT fluorescence intensities. These results, highlighting the role of fibril morphology in ThT-based amyloid studies, underline the relevance of polymorphs in ThT–amyloid interaction and can explain the variability often observed in ThT amyloid binding assays.
关键词： thioflavin-T,polymorphism,Amyloid,atomic force microscopy,a-synuclein
更新于2025-09-04 15:30:14
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Optical Sectioning Microscopy For Multilayer Structure With Micro-Scale Air Gaps Measurement
摘要： In this letter, we propose a new method based on the optical sectioning microscopy to characterize the multilayer structure with micro-scale air gaps. With this technique, sinusoidal fringe patterns having a predefined shifted phase produced by digital micro-mirror devices are illuminated onto the sample. The contrast response curve (CRC) of the reflected patterns along the scanning direction is determined by the phase-shifting algorithm while the object is scanned through the focus of the microscope. The maximum contrast value of the CRC occurs at the position where the sample is on the focal plane. The peak positions of the CRC are extracted through the Gaussian fitting and then implemented to achieve the surface topography and gap thickness distribution. To suppress the noise influence caused by the environment fluctuations or other factors, the frequency domain analysis (FDA) has been introduced in this work. The simulations and experiments are conducted to verify the feasibility of this technique, demonstrating the potential to be applied in such fields as semiconductor and biochip, where the air gap may play crucial roles.
关键词： thickness measurement,microscopy,surface topography
更新于2025-09-04 15:30:14
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[IEEE 2018 25th IEEE International Conference on Image Processing (ICIP) - Athens, Greece (2018.10.7-2018.10.10)] 2018 25th IEEE International Conference on Image Processing (ICIP) - Detection and Tracking of Astral Microtubules in Fluorescence Microscopy Images
摘要： In this paper we explore detection and tracking of astral micro-tubules, a sub-population of microtubules which only exists during and immediately before mitosis and aids in the spindle orientation by connecting it to the cell cortex. Its analysis can be useful to deter-mine the presence of certain diseases, such as brain pathologies and cancer. The proposed algorithm focuses on overcoming the prob-lems regarding fluorescence microscopy images and microtubule behaviour by using various image processing techniques and is then compared with three existing algorithms, tested on consistent sets of images.
关键词： image segmentation,Medical diagnostic imaging,kalman filter,fluorescence microscopy,microtubules
更新于2025-09-04 15:30:14
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Asymmetry of the Defect Structure of Semipolar GaN Grown on Si(001)
摘要： The defect structure of a thick (~15 μ m) semipolar gallium nitride (GaN) layer grown by hydride–chloride vapor phase epitaxy on a Si(001) substrate with buffer layers has been studied by transmission electron microscopy. The asymmetry of the defect structure of GaN epilayer has been revealed and analyzed. The influence of this asymmetry on the rate of decrease in the density of threading dislocations in the growing epitaxial layer is discussed.
关键词： transmission electron microscopy,semipolar GaN,threading dislocations,hydride–chloride vapor phase epitaxy,defect structure
更新于2025-09-04 15:30:14
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Corneal Fibroblast Migration Patterns During Intrastromal Wound Healing Correlate With ECM Structure and Alignment
摘要： PURPOSE. To assess keratocyte backscattering, alignment, morphology, and connectivity in vivo following a full-thickness corneal injury using the Heidelberg Retina Tomograph Rostock Cornea Module (HRT-RCM), and to correlate these findings with en bloc three-dimensional (3-D) confocal fluorescence and second harmonic generation (SHG) imaging. METHODS. Rabbit corneas were scanned in vivo both before and 3, 7, 14, and 28 days after transcorneal freeze injury (FI), which damages all corneal cell layers. Corneal tissue was also fixed and labeled for f-actin and nuclei en bloc, and imaged using 3-D confocal fluorescence microscopy and SHG imaging. RESULTS. Using the modified HRT-RCM, full-thickness scans of all cell layers were consistently obtained. Following FI, stromal cells repopulating the damaged tissue assumed an elongated fibroblastic morphology, and a significant increase in cellular light scattering was measured. This stromal haze gradually decreased as wound healing progressed. Parallel, interconnected streams of aligned corneal fibroblasts were observed both in vivo (from HRT-RCM reflection images) and ex vivo (from f-actin and nuclear labeling) during wound healing, particularly in the posterior cornea. Second harmonic generation imaging demonstrated that these cells were aligned parallel to the collagen lamellae. CONCLUSIONS. The modified HRT-RCM allows in vivo measurements of sublayer thickness, assessment of cell morphology, alignment and connectivity, and estimation of stromal backscatter during wound healing. In this study, these in vivo observations led to the novel finding that the pattern of corneal fibroblast alignment is highly correlated with lamellar organization, suggesting contact guidance of intrastromal migration that may facilitate more rapid wound repopulation.
关键词： SHG imaging,confocal microscopy,corneal wound healing,extracellular matrix
更新于2025-09-04 15:30:14
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Confocal Fluorescence Microscopy and Kinetics of the Cr3+-Chromate Ion Oxidation Equilibria at the Solid Liquid Interface
摘要： Silica-borax pearl samples impregnated with 0.17 and 0.64% Cr3+ were characterized by specific surface area measurements, UV-Vis spectroscopy, energy-dispersive X-ray fluorescence and laser-scanning confocal microscopy. Pearl stability against oxidizing conditions was tested by adding samples to an aqueous hydrogen peroxide solution. The reaction was examined by UV-Vis spectroscopic measurements of the supernatant and laser-scanning confocal microscopy images of the substrate. Overall, hydrogen peroxide-induced Cr3+ to Cr6+ oxidation across the solid-liquid interface promoted solid matrix cleavage pearl degradation and concomitant formation of multiple scattering centers was observed. A dual-detection scheme was employed in the confocal microscopy measurements allowing us to separate scattering and absorptive contributions to the observed signals. The confocal microscopy images indicate that Cr3+ oxidation induced by hydrogen peroxide solutions occurs throughout the entire pearl sample and indicate that oxidation reactions induce leakage of chromate ion into aqueous solutions.
关键词： energy dispersive X-ray fluorescence,confocal fluorescence microscopy,chromium mobility,H2O2 oxidation equilibria,mass transfer phenomena,solid liquid interfaces
更新于2025-09-04 15:30:14