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RGB color coded images in scanning electron microscopy of biological surfaces
摘要： We present here a methodological approach for the creation of color images in scanning electron microscopy by processing grayscale images taken simultaneously from at least three different detectors in a scanning electron microscope. The final color images are then produced by merging together those grayscale images in RGB color space. We show the images from non-conductive standard sample together with those obtained from real microbiological samples. The first one represents a microbial biofilm naturally grown on fiber glass filter. The other shows individual Bacillus subtilis cells from batch culture. All the image handling was done in open source image processing software ImageJ or GNU Image Manipulation Program (Gimp) or, alternatively, in proprietary AnalySis 3.2 Pro software processing suite.
关键词： high resolution,color images,scanning electron microscopy,biological surfaces
更新于2025-09-23 15:22:29
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Interferometric surface mapping of a spherical proof mass for ultra precise inertial reference sensors
摘要： In the context of our investigations on novel inertial reference sensors for space applications, we have explored a design utilizing an optical readout of a spherical proof mass. This concept enables full drag-free operations, hence reducing proof mass residual acceleration noise to a minimum. The main limitations of this sensor are errors in position determination of the center of mass of the proof mass due to the surface topography and the involved path length changes upon rotation. One solution is to apply a surface map for correction of the measurement data, thus improving the precision of position determination. This article presents the results of our one-dimensional interferometric surface topography measurements of a sphere, achieving uncertainties of ≈10 nm, as a first step to realize a complete surface map. The measurement setup consists of two heterodyne interferometers positioned in an opposing configuration, which measure the surface topography while the sphere is continuously rotated by a rotation stage.
关键词： figure,roughness,Surfaces,Roughness,Interferometry,Surface measurements
更新于2025-09-23 15:22:29
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Multi-band Polarimetry of the Lunar Surface. II. Grain Size Evolutionary Pathway
摘要： To understand grain size evolution on the lunar surface in detail, we analyze the distribution of the average grain size dá ? for the lunar near side obtained by Jeong et al. Furthermore, we analyze the polarimetric properties of the regolith simulants SiC and JSC-1A in a laboratory. We ?nd two characteristics of grain size evolution on the Moon. First, the lunar regolith has evolved on a speci?c evolutionary pathway in dá ? F– space. Here, Φ is de?ned as the ratio of the perpendicular (I^) and parallel (I?) components of the re?ectance. Second, we also ?nd that the evolutionary pathway depends on the FeO abundance and selenographic latitude of the surface. The dependence on the FeO content seems to result from the different resistance to comminution of regolith materials, and the dependence on the latitude seems to result from differences in the resurfacing environment. We present the probable causes of these characteristics of grain size evolution on the lunar surface.
关键词： Moon,techniques: polarimetric,methods: laboratory: solid state,methods: observational,polarization,planets and satellites: surfaces
更新于2025-09-23 15:22:29
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Exploring Potential Energy Surfaces for Aggregation‐Induced Emission ‐ from Solution to Crystal
摘要： Aggregation-induced emission (AIE) is a phenomenon where non-luminescent compounds in solution become strongly luminescent in aggregate and solid phase. It provides a fertile ground for luminescent applications that has rapidly developed in the last 15 years. In this review, we focus on the contributions of theory and computations to understanding the molecular mechanism behind it. Starting from initial models, such as restriction of intramolecular rotations (RIR), and the calculation of non-radiative rates with Fermi’s golden rule (FGR), we center on studies of the global excited-state potential energy surfaces that have provided the basis for the restricted access to a conical intersection (RACI) model. In this model, which has been shown to apply for a diverse group of AIEgens, the lack of fluorescence in solution comes from radiationless decay at a CI in solution that is hindered in the aggregate state. We also highlight how intermolecular interactions modulate the photophysics in the aggregate phase, in terms of fluorescence quantum yield and emission color.
关键词： intermolecular interactions,aggregation-induced emission,conical intersections,potential energy surfaces
更新于2025-09-23 15:22:29
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Adsorption Dynamics of Redox Active Species onto Polarized Surfaces of Sensitized NiO
摘要： Mesoporous NiO films were deposited by means of a screen printing technique onto fluorine-doped tin oxide transparent electrodes and consequently sensitized with Erythrosin B (EryB) dye. The obtained colored NiO material was used as a working electrode in a three-electrode cell to study the evolution of the triple semiconductor/dye/electrolyte interface upon electrochemical polarization in dark conditions. The electrolyte was a solution of I3?/I? in acetonitrile, with the redox couple representing the typical redox shuttle of dye-sensitized solar cells (DSCs). The adopted electrochemical conditions were devised in order to simulate the actual electrical environment of the NiO/dye photocathode in a light-soaked DSC. The use of a benchmark sensitizer EryB and of the most widely used redox mediator I3?/I? is particularly meaningful for the study of the adsorption dynamics and the determination of possible degradative phenomena on the basis of the behavior of numerous analogue systems. Therefore, for the first time, the evolution of the NiO/EryB/I3?/I? multiple interface was investigated combining the electrochemical characterization with ex situ spectroscopic analysis by means of X-ray photoelectron spectroscopy. The resulting picture shows that EryB in the immobilized state promotes the redox processes based on the I3?/I? couple. Moreover, the EryB sensitizer inhibits the phenomena of recombination between the metal oxide semiconductor and the redox couple.
关键词： X-ray photoelectron spectroscopy,Sensitized NiO,Dye-sensitized solar cells,Redox active species,Adsorption dynamics,Polarized surfaces
更新于2025-09-23 15:22:29
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[Springer Series in Materials Science] Biomimetics Volume 279 (Bioinspired Hierarchical-Structured Surfaces for Green Science and Technology) || Structural Coloration
摘要： In living nature, flora and fauna produce color through pigments, bioluminescence, or structural coloration (Booth 1990). Biological pigments, or simply pigments, are substances produced by living organisms, which produce color resulting from selective light adsorption and reflection of a specific light wavelength. These include plant and flower pigments, such as green pigment chlorophyll used by plants for photosynthesis. Many biological structures contain pigments such as melanin in skin, eyes, fur, and hair. Bioluminescence is the production and emission of visible light by a living organism. It occurs widely in marine organisms, as well as in some fungi, bacteria, and terrestrial invertebrates, such as fireflies. Structural coloration is the production of color by selective light reflection by nanostructured surfaces with features of the same scale as incident visible light wavelengths (Fox 1976; Kinoshita 2008; Kinoshita et al. 2008; Sun et al. 2013; Yu et al. 2013). While pigments degrade and their colors fade over time, structural coloration can persist for long periods, even after the death of the organism.
关键词： iridescent,nanostructured surfaces,bioluminescence,pigments,structural coloration
更新于2025-09-23 15:21:21
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Improved Models for Metallic Nanoparticle Cores From Atomic Pair Distribution Function (PDF) Analysis
摘要： X-ray atomic pair distribution functions (PDFs) were collected from a range of canonical metallic nanomaterials, both elemental and alloyed, prepared using different synthesis methods and exhibiting drastically different morphological properties. Widely applied shape-tuned attenuated crystal (AC) fcc models proved inadequate, yielding structured, coherent, and correlated fit residuals. However, equally simple discrete cluster models could account for the largest amplitude features in these difference signals. A hypothesis testing based approach to nanoparticle structure modelling systematically ruled out effects from crystallite size, composition, shape, and surface faceting as primary factors contributing to the AC misfit. On the other hand, decahedrally twinned cluster cores were found to be the origin of the AC structure misfits for a majority of the nanomaterials reported here. It is further motivated that the PDF can readily differentiate between the arrangement of domains in these multiply-twinned motifs. Most of the nanomaterials surveyed also fall within the sub-5 nm size regime where traditional electron microscopy cannot easily detect and quantify domain structures, with sampling representative of the average nanocrystal synthesized. The results demonstrate that PDF analysis is a powerful method for understanding internal atomic interfaces in small noble metallic nanomaterials. Such core cluster models, easily built algorithmically, should serve as starting structures for more advanced models able to capture atomic positional disorder, ligand induced or otherwise, near nanocrystal surfaces.
关键词： decahedrally twinned cluster cores,PDF analysis,metallic nanomaterials,nanocrystal surfaces,X-ray atomic pair distribution functions
更新于2025-09-23 15:21:21
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Perovskites fabricated on textured silicon surfaces for tandem solar cells
摘要： The silicon surface texture significantly affects the current density and efficiency of perovskite/silicon tandem solar cells. However, only a few studies have explored fabricating perovskite on textured silicon and the effect of texture on perovskite films because of the limitations of solution processes. Here we produce conformal perovskite on textured silicon with a dry two-step conversion process that incorporates lead oxide sputtering and direct contact with methyl ammonium iodide. To separately analyze the influence of each texture structure on perovskite films, patterned texture, high-resolution photoluminescence (μ-PL), and light beam-induced current (μ-LBIC), 3D mapping is used. This work elucidates conformal perovskite on textured surfaces and shows the effects of textured silicon on the perovskite layers with high-resolution 3D mapping. This approach can potentially be applied to any type of layer on any type of substrate.
关键词： tandem solar cells,dry two-step conversion process,perovskite,textured surfaces,silicon
更新于2025-09-23 15:21:01
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Anti-Biofouling Properties of Femtosecond Laser-Induced Submicron Topographies on Elastomeric Surfaces
摘要： Anti-bacterial coatings are often employed to elastomer surfaces to inhibit bacterial attachment. However, such approaches could lead to increased antibiotic resistance. Surface micro/nano texturing is gaining significant attention recently, as it is a passive approach to reduce bacterial adhesion to surfaces. To this end, this work aims to assess the anti-biofouling functionality of femtosecond laser-induced sub-micron topographies on biomedical elastomer surfaces. Femtosecond laser processing was employed to produce two types of topographies on stainless steel substrates. The first one was highly regular and single scale sub-micron laser-induced periodic surface structures (LIPSS) while the second one was multi-scale structures (MS) containing both sub-micron and micron-scale features. Subsequently, these topographies were replicated on Polydimethylsiloxane (PDMS) and Polyurethane (PU) elastomers to evaluate their bacterial retention characteristics. The sub-micron textured PDMS and PU surfaces exhibited long term hydrophobic durability up to 100 hours under the immersed conditions. Both LIPSS and MS topographies on PDMS and PU elastomeric surfaces were shown to substantially reduce (> 89%) the adhesion of gram-negative Escherichia coli bacteria. At the same time, the anti-biofouling performance of LIPSS and MS topographies was found to be comparable with that of lubricant-impregnated surfaces. The influence of physical defects on textured surfaces on the adhesion behaviour of bacteria was also elucidated. The results presented here are significant because the polymeric biomedical components that can be produced by replication cost-effectively, while their biocompatibility can be improved through femtosecond surface modification of the respective replication masters.
关键词： anti-biofouling,polyurethane,biomedical elastomers,PDMS,femtosecond,lubricant-impregnated surfaces,laser induced periodic surface structures
更新于2025-09-23 15:21:01
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[IEEE GLOBECOM 2019 - 2019 IEEE Global Communications Conference - Waikoloa, HI, USA (2019.12.9-2019.12.13)] 2019 IEEE Global Communications Conference (GLOBECOM) - Intelligent Reflecting Surfaces for Free Space Optical Communications
摘要： In this paper, we investigate the use of intelligent reflecting surfaces (IRSs) (i.e., smart mirrors) to relax the line-of-sight requirement of free space optical (FSO) systems. We characterize the impact of the physical parameters of the IRS, such as its size, position, and orientation, on the quality of the end-to-end FSO channel. In addition, we develop a statistical channel model for the geometric and the misalignment losses which accounts for the random movements of the IRS, transmitter, and receiver due to building sway. This model can be used for performance analysis of IRS-based FSO systems. Our analytical results shows that depending on the angle between the beam direction and the IRS plane, building sway for the IRS has either a smaller or larger impact on the quality of the end-to-end FSO channel than building sway for the transmitter and receiver. Furthermore, our simulation results validate the accuracy of the developed channel model and offer insight for system design.
关键词： Smart mirrors,Channel model,Free space optical communications,Intelligent reflecting surfaces,Building sway
更新于2025-09-23 15:21:01