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- 实验方案
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Study of oil-particle-aggregation by digital inline holograph
摘要： This study was performed to visually analyse the relationship between particles and oil in seawater by digital holograph technology. Two types of particles with different sizes were chosen to form oil-particle aggregates (OPAs) in the laboratory to determine whether these particles may be a good approach to safely and harmoniously recover marine environment after an oil spill. The processes were recorded by a digital inline holographic system, which could facilitate a continuous real-time three-dimensional in situ observation of oil droplets and OPAs without touching these particles. The visual results showed that, in the micro scale, the particles formed two different types of OPA after breaking the oil film and transported oil into the bottom of the water, while some OPAs could be resuspended.
关键词： spatial distribution,oil droplet,oil particle aggregation,marine oil spill,digital holographic,digital generated hologram
更新于2025-09-23 15:23:52
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Nearest Centroid Neighbor Based Sparse Representation Classification for Finger vein Recognition
摘要： In this paper, an efficient finger vein recognition algorithm based on the combination of the nearest centroid neighbor and sparse representation classification techniques (kNCN-SRC) is presented. The previously proposed recognition algorithms are mainly based on distance computation. In the proposed method, the distance, as well as the spatial distribution, are considered to achieve a better recognition rate. The proposed method consists of two stages: first, the k nearest neighbors of the test sample are selected based on the nearest centroid neighbor and then in the second stage based on the selected number of closest nearest centroid neighbors (k) the test sample is classified by sparse representation. Findings from the proposed method kNCN-SRC demonstrated an increased recognition rate. This improvement can be attributed to the selection of the train samples, where the train samples are selected by considering the spatial and distance distribution. In addition, the complexity of SRC is reduced by reducing the number of train samples for classification of the test sample by sparse representation and the processing speed of the proposed algorithm is significantly improved in comparison to the conventional SRC which is due to the reduced number of training samples. It can be concluded that the kNCN-SRC classification method is efficient for finger vein recognition. An increase in the recognition rate of 3.35%, 9.07%, 20.23%, and 0.81% is obtained for the proposed kNCN-SRC method in comparison with the conventional SRC for the four tested public finger vein databases.
关键词： Finger vein recognition,Distance criterion,k-Nearest Centroid Neighbor,Spatial distribution,Sparse Representation Classification
更新于2025-09-23 15:22:29
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Preliminary analysis of the relationship between serum lutein and zeaxanthin levels and macular pigment optical density
摘要： Purpose: To assess the relationship between combined serum lutein and zeaxanthin (L+Z) concentration and macular pigment optical density (MPOD), and to investigate the effect of L+Z+docosahexaenoic acid (DHA) dietary supplementation on the spatial distribution of MPOD. Methods: Twenty healthy fellow eyes with unilateral wet age-related macular degeneration or chronic central serous chorioretinopathy were included. All participants received a dietary supplement for 6 months that contained 20 mg L, 1 mg Z, and 200 mg DHA. The best-corrected visual acuity and contrast sensitivity (CS) were measured at baseline and at 1, 3, and 6 months. Serum L+Z concentrations were measured at baseline and at 3 months. MPOD was calculated at each time point using fundus autofluorescent images. Results: Serum L+Z concentration was correlated with MPOD at 1°–2° eccentricity at baseline (r=0.63, P=0.003) and 3 months (r=0.53, P=0.015). Serum L+Z concentration increased by a factor of 2.3±1.0 (P<0.0001). At 6 months, MPOD was significantly higher compared to the baseline level at 0°–0.25° (P=0.034) and 0.25°–0.5° (P=0.032) eccentricity. CS improved after 3 or 6 months of L+Z+DHA supplementation (P<0.05). Conclusion: Juxtafoveal MPOD was associated with serum L+Z concentration. Foveal MPOD was increased by L+Z+DHA dietary supplementation.
关键词： fundus autofluorescence,spatial distribution,supplement
更新于2025-09-23 15:22:29
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Resolving spatial and energetic distributions of trap states in metal halide perovskite solar cells
摘要： We report the profiling of spatial and energetic distributions of trap states in metal halide perovskite single-crystalline and polycrystalline solar cells. The trap densities in single crystals varied by five orders of magnitude, with a lowest value of 2 × 1011 per cubic centimeter and most of the deep traps located at crystal surfaces. The charge trap densities of all depths of the interfaces of the polycrystalline films were one to two orders of magnitude greater than that of the film interior, and the trap density at the film interior was still two to three orders of magnitude greater than that in high-quality single crystals. Suprisingly, after surface passivation, most deep traps were detected near the interface of perovskites and hole transport layers, where a large density of nanocrystals were embedded, limiting the efficiency of solar cells.
关键词： spatial distribution,solar cells,metal halide perovskite,energetic distribution,trap states
更新于2025-09-23 15:19:57
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Analysis of the beam waist on spatial emission characteristics from an electron driven by intense linearly polarized laser pulses
摘要： This paper establishes a low-energy single-electron acceleration model based on the Lorentz equation and an energy equation, simulates the trajectories of electrons in laser pulses with different beam waist radii with the help of MATLAB software and analyzes the influence of linearly polarized laser intensity on the dynamic law of high-energy electrons. With the beam waist radius increasing, we find that the longitude drifting distance and the maximum transverse quivering amplitude are growing differently at each part at first (when the beam waist radius <4λ0) and then decreasing differently as well. Furthermore, when the beam waist radius is small enough, the ramifications are found first; increasing the radius of the beam will make the radiated power go up by orders of magnitude and the ramification of the location and number found in the asymmetric bifoliate radiation pattern change throughout.
关键词： relativistic motion,beam waist radius,radiation pattern,spatial distribution of emission,linearly polarized femtosecond Gaussian laser pulse,ramification
更新于2025-09-23 15:19:57
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Spatial distribution measurement of acoustic cavitation bubbles by laser backscattering with confocal optics
摘要： A three-dimensional measurement method for the spatial distribution of acoustic cavitation bubbles employing laser backscattering and confocal optics is proposed. A numerical simulation of the proposed method shows that the measurement system has FWHM resolutions of 26.5 mm perpendicular to the laser axis and 1.02 mm along the laser axis. The frequency components of the output that are integer multiples of the incident ultrasound frequency can be indicators of the existence of bubbles. The experimental evaluation shows that the proposed method has three-dimensional resolution. Although the proposed method can measure the three-dimensional distribution of bubbles, it cannot decompose the quantity and activity of bubbles. Both a large number of bubbles and violent bubble oscillation enlarge the frequency components. To decompose these parameters, further study of the relationship between the bubble oscillation and the frequency spectrum is required.
关键词： Bubble oscillation,Multibubble,Laser backscattering,Spatial distribution,Acoustic cavitation
更新于2025-09-16 10:30:52
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Nanoscale chemical mapping of oxygen functional groups on graphene oxide using atomic force microscopy-coupled infrared spectroscopy
摘要： The unambiguous determination of the chemical functionality over graphene oxide (GO) is important to unleash its potential applications. However, the mapping of oxygen functionalities distribution remains to be unequivocally determined because of highly inhomogeneous non-stoichiometric structures and ultra-thin layers of GO. In this study, we report an experimental observation of the spatial distribution of oxygen functional groups on monolayer and multilayer GO using AFM-IR, atomic force microscopy coupled with infrared spectroscopy. Overcoming conventional IR diffraction limit for several micrometers, the novel AFM-IR reaches high spatial resolution (cid:1)20 nm and could detect IR absorption on (cid:1)1 nm thickness of monolayer GO. With nanoscale chemical mapping, the distribution of different oxygen functional groups is distinguished with AFM-IR over the GO surface. It allows us to observe that these oxygen functional groups prefer to sit on the fold areas, in discrete domains and on the edges of GO, which gave more insights into its chemical nature. The determination of the position of functional groups through precise imaging contributes to our understanding of GO structure-properties relations and paves the way for targeted tethering of polymers, biomaterials, and other nanostructures.
关键词： Chemical functionality,AFM-IR,Spatial distribution,Graphene
更新于2025-09-16 10:30:52
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Laser-induced breakdown spectroscopy as a promising tool in the elemental bioimaging of plant tissues
摘要： Laser-Induced Breakdown Spectroscopy (LIBS) is an optical analytical technique with a multi-element capability for element bioimaging in plants. During the years of LIBS development, the major application field has been in industry. However, during the last two decades, LIBS became a useful imaging tool in various biologic matrices, e.g. bones, mammals’ organs, and in the plant science. In this work, we present an overview of LIBS achievements in plant bioimaging which started in 2006. The progress in the assessment of spatial element distribution in plants is documented here with respect to the applications in phytotoxicity testing for the following reason: the information on the spatial distribution of elements can reveal a relationship between the exact location of an element and its toxic effect. This review discusses the state of the art of various elements’ bioimaging in plants using LIBS with a spatial resolution at micrometer scale.
关键词： crop plants,macronutrients,laser ablation,nanoparticles,element spatial distribution,micronutrients,2D-mapping,heavy metals,plants,model organisms,phytotoxicity,elemental imaging
更新于2025-09-12 10:27:22
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A Nondestructive Detection Method for Mixed Veterinary Drugs in Pork Using Line-Scan Raman Chemical Imaging Technology
摘要： This study reports a nondestructive detection method using Raman chemical imaging (RCI) technology for the simultaneous determination of multiple veterinary drugs, such as ofloxacin, chloramphenicol, and sulfadimidine, in pork. A line-scan Raman imaging system was employed to acquire images of pure veterinary drugs and pork samples containing single and mixed drugs. Raman characteristic peaks at 1623, 1353, and 1147 cm?1 were identified for ofloxacin, chloramphenicol, and sulfadimidine, respectively. An image processing method was proposed to calculate the Bpixel-ratio^ values in each feature image, and linear regression models for a single veterinary drug were then established between the Bpixel-ratio^ values and the actual concentrations. By applying the models to samples with mixed veterinary drugs, the concentrations of the three drugs were predicted with correlation coefficients of 0.978, 0.986, and 0.984. The satisfactory results indicated that along with the proposed Bpixel-ratio^ method, RCI technology enables the nondestructive quantitation and spatial distribution visualization of multiple veterinary drug residues.
关键词： Raman chemical imaging,Spatial distribution,Pork,Veterinary drugs,Pixel-ratio,Quantitative analysis
更新于2025-09-10 09:29:36
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Integrated spectral and spatial information extraction in Raman spectroscopy
摘要： Raman spectroscopy has been widely used to analyze various substances quantitatively. Conventional studies are primarily focused on the spectral characteristics of Raman scattering. The spatial distribution is always ignored, which can be used to observe the physical properties, such as the particle size. In this article, the spatial information has been extracted from the Raman spectra of barium nitrate, demonstrating that the evident spatial width broadening varied with the particle size. The numerical result shows that the spatial width has a better linear correlation with the particle size, while the Raman intensity has a poor linear correlation. The integrated spectral and spatial information extracted in Raman spectroscopy has a potential application in the quantitative analysis of physical properties.
关键词： spatial distribution,Raman spectroscopy,Particle size
更新于2025-09-04 15:30:14