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5,897 result(s) for "Polarized light"
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Biomimetic Polarized Light Navigation Sensor: A Review
A polarized light sensor is applied to the front-end detection of a biomimetic polarized light navigation system, which is an important part of analyzing the atmospheric polarization mode and realizing biomimetic polarized light navigation, having received extensive attention in recent years. In this paper, biomimetic polarized light navigation in nature, the mechanism of polarized light navigation, point source sensor, imaging sensor, and a sensor based on micro nano machining technology are compared and analyzed, which provides a basis for the optimal selection of different polarized light sensors. The comparison results show that the point source sensor can be divided into basic point source sensor with simple structure and a point source sensor applied to integrated navigation. The imaging sensor can be divided into a simple time-sharing imaging sensor, a real-time amplitude splitting sensor that can detect images of multi-directional polarization angles, a real-time aperture splitting sensor that uses a light field camera, and a real-time focal plane light splitting sensor with high integration. In recent years, with the development of micro and nano machining technology, polarized light sensors are developing towards miniaturization and integration. In view of this, this paper also summarizes the latest progress of polarized light sensors based on micro and nano machining technology. Finally, this paper summarizes the possible future prospects and current challenges of polarized light sensor design, providing a reference for the feasibility selection of different polarized light sensors.
Circularly Polarized Light-Enabled Chiral Nanomaterials: From Fabrication to Application
HighlightsThis review summarized the fabrication strategy using circularly polarized light as a chiral source to construct chiral materials.The potential applications of chiral nanomaterials driven by circularly polarized light in different fields are summarized, explained by representative examples.The potential challenges of circularly polarized light-enabled chiral materials are outlined and future research directions are outlooked.For decades, chiral nanomaterials have been extensively studied because of their extraordinary properties. Chiral nanostructures have attracted a lot of interest because of their potential applications including biosensing, asymmetric catalysis, optical devices, and negative index materials. Circularly polarized light (CPL) is the most attractive source for chirality owing to its high availability, and now it has been used as a chiral source for the preparation of chiral matter. In this review, the recent progress in the field of CPL-enabled chiral nanomaterials is summarized. Firstly, the recent advancements in the fabrication of chiral materials using circularly polarized light are described, focusing on the unique strategies. Secondly, an overview of the potential applications of chiral nanomaterials driven by CPL is provided, with a particular emphasis on biosensing, catalysis, and phototherapy. Finally, a perspective on the challenges in the field of CPL-enabled chiral nanomaterials is given.
Chiral templating of self-assembling nanostructures by circularly polarized light
It is shown that circularly polarized light produces enantiomeric excesses, above 30%, of twisted nanoribbons self-assembled from racemic dispersions of CdTe nanoparticles. The high optical and chemical activity of nanoparticles (NPs) signifies the possibility of converting the spin angular momenta of photons into structural changes in matter. Here, we demonstrate that illumination of dispersions of racemic CdTe NPs with right- (left-)handed circularly polarized light (CPL) induces the formation of right- (left-)handed twisted nanoribbons with an enantiomeric excess exceeding 30%, which is ∼10 times higher than that of typical CPL-induced reactions. Linearly polarized light or dark conditions led instead to straight nanoribbons. CPL ‘templating’ of NP assemblies is based on the enantio-selective photoactivation of chiral NPs and clusters, followed by their photooxidation and self-assembly into nanoribbons with specific helicity as a result of chirality-sensitive interactions between the NPs. The ability of NPs to retain the polarization information of incident photons should open pathways for the synthesis of chiral photonic materials and allow a better understanding of the origins of biomolecular homochirality.
Evaluating fibre orientation dispersion in white matter: Comparison of diffusion MRI, histology and polarized light imaging
Diffusion MRI is an exquisitely sensitive probe of tissue microstructure, and is currently the only non-invasive measure of the brain's fibre architecture. As this technique becomes more sophisticated and microstructurally informative, there is increasing value in comparing diffusion MRI with microscopic imaging in the same tissue samples. This study compared estimates of fibre orientation dispersion in white matter derived from diffusion MRI to reference measures of dispersion obtained from polarized light imaging and histology. Three post-mortem brain specimens were scanned with diffusion MRI and analyzed with a two-compartment dispersion model. The specimens were then sectioned for microscopy, including polarized light imaging estimates of fibre orientation and histological quantitative estimates of myelin and astrocytes. Dispersion estimates were correlated on region – and voxel-wise levels in the corpus callosum, the centrum semiovale and the corticospinal tract. The region-wise analysis yielded correlation coefficients of r = 0.79 for the diffusion MRI and histology comparison, while r = 0.60 was reported for the comparison with polarized light imaging. In the corpus callosum, we observed a pattern of higher dispersion at the midline compared to its lateral aspects. This pattern was present in all modalities and the dispersion profiles from microscopy and diffusion MRI were highly correlated. The astrocytes appeared to have minor contribution to dispersion observed with diffusion MRI. These results demonstrate that fibre orientation dispersion estimates from diffusion MRI represents the tissue architecture well. Dispersion models might be improved by more faithfully incorporating an informed mapping based on microscopy data.
Light-modulated 8-Pmmn borophene-based pure crossed Andreev reflection
We investigate the off-resonant circularly polarized light-modulated crossed Andreev reflection (CAR) in an 8-Pmmn borophene-based normal conductor/superconductor/normal conductor junction. When the signs of Fermi energies in two normal regions are opposite, the pure CAR without the local Andreev reflection and the elastic cotunneling occurs. By using the Dirac–Bogoliubov–de Gennes equation and the Blonder–Tinkham–Klapwijk formula, the pure CAR conductance and its oscillation as a function of the junction length and the Fermi energy in the superconducting regions are discussed. It is found that the value of pure CAR conductance peak value and its corresponding value of light-induced gap increase with the increase of incident energy of electron. Furthermore, the valley splitting for the transmitted hole is found due to the presence of tilted velocity of borophene. Our findings are beneficial for designing the high efficiency 8-Pmmn borophene-based nonlocal transistor and nonlocal valley splitter without local and non-entangled processes.
Identification of microplastics in wastewater samples by means of polarized light optical microscopy
Many reports state the potential hazards of microplastics (MPs) and their implications to wildlife and human health. The presence of MP in the aquatic environment is related to several origins but particularly associated to their occurrence in wastewater effluents. The determination of MP in these complex samples is a challenge. Current analytical procedures for MP monitoring are based on separation and counting by visual observation or mediated with some type of microscopy with further identification by techniques such as Raman or Fourier-transform infrared (FTIR) spectroscopy. In this work, a simple alternative for the separation, counting and identification of MP in wastewater samples is reported. The presented sample preparation technique with further polarized light optical microscopy (PLOM) observation positively identified the vast majority of MP particles occurring in wastewater samples of Montevideo, Uruguay, in the 70–600 μm range. MPs with different shapes and chemical composition were identified by PLOM and confirmed by confocal Raman microscopy. Rapid identification of polyethylene (PE), polypropylene (PP) and polyethylene terephthalate (PET) were evidenced. A major limitation was found in the identification of MP from non-birefringent polymers such as PVC (polyvinylchloride). The proposed procedure for MP analysis in wastewater is easy to be implemented at any analytical laboratory. A pilot monitoring of Montevideo WWTP effluents was carried out over 3-month period identifying MP from different chemical identities in the range 5.3–8.2 × 10 3 MP items/m 3 .
A novel approach to the human connectome: Ultra-high resolution mapping of fiber tracts in the brain
Signal transmission between different brain regions requires connecting fiber tracts, the structural basis of the human connectome. In contrast to animal brains, where a multitude of tract tracing methods can be used, magnetic resonance (MR)-based diffusion imaging is presently the only promising approach to study fiber tracts between specific human brain regions. However, this procedure has various inherent restrictions caused by its relatively low spatial resolution. Here, we introduce 3D-polarized light imaging (3D-PLI) to map the three-dimensional course of fiber tracts in the human brain with a resolution at a submillimeter scale based on a voxel size of 100μm isotropic or less. 3D-PLI demonstrates nerve fibers by utilizing their intrinsic birefringence of myelin sheaths surrounding axons. This optical method enables the demonstration of 3D fiber orientations in serial microtome sections of entire human brains. Examples for the feasibility of this novel approach are given here. 3D-PLI enables the study of brain regions of intense fiber crossing in unprecedented detail, and provides an independent evaluation of fiber tracts derived from diffusion imaging data. ►Novel approach to map the 3D courses of fiber tracts in the human brain. ►3D-polarized light imaging (3D-PLI) provides resolution at a submillimeter scale. ►Fiber models were successfully reconstructed in the pontine region. ►3D-PLI provides an independent evaluation of MR-based diffusion imaging data.
Polarized hyperspectral and polarized light microscopic imaging for enhanced visualization of white blood cells
White blood cells (WBC) are hematopoietic cells of the immune system that protect the body by recognizing and eliminating infectious agents. Abnormalities in WBC production, maturation, or function can lead to disease and associated morphologic changes that, when systematically characterized, support diagnostic classification and clinical decision-making. We aim to investigate polarized hyperspectral imaging (PHSI) and polarized light imaging (PLI) microscopy for the visualization of WBCs. We developed a dual-modality microscopic imaging system that performs both polarized hyperspectral imaging and polarized light imaging. In the dual imaging setup, we used a snapscan hyperspectral camera and an RGB camera to acquire images separately and further calculate four Stokes parameters (S0, S1, S2, and S3) as well as three Stokes vector-derived parameters, namely, the degree of polarization, degree of linear polarization, and degree of circular polarization. Synthetic RGB images of Stokes vectors and Stokes vector-derived parameters were generated for the visualization of cellular components with PHSI images. The spectral signatures of representative WBCs, e.g., granulocytes and lymphocytes, were extracted for qualitative comparison. The preliminary results demonstrate that Stokes vector parameters can enhance the visualization of granules in granulocytes, the visualization of surface structures of lymphocytes, and the morphologic visualization of the monocyte nucleus. Furthermore, the results also reveal that the measured spectra of Stokes vector parameters could enhance the differentiation of WBCs in the spectral dimension, represented by the qualitative comparison between granulocytes and lymphocytes. Utilizing the spatial and spectral information from the Stokes vector data, our customized polarized hyperspectral microscopic imaging system enhances the visualization of WBCs and may provide a tool for the diagnosis of disorders related to white blood cells.
Widely targeted metabolomic and transcriptomic analyses of the effects of blue polarized light and ordinary light on Dendrobium officinale
, an orchid native to China, benefits the stomach, moistens the lungs, and enhances immunity. Light affects the synthesis of functional metabolites in . The luminescence mechanism of polarized light differs from that of ordinary light sources and has different effects on plants. In this study, different light treatments-white (W), blue (B), and blue polarized (BP) light-were applied to . In comparison to ordinary light sources, blue polarized light significantly altered the stem color, making it reddish. RNA-seq and targeted metabolomics analysis were used to investigate the mechanisms underlying the effects of the different light treatments on . The results revealed that 2448, 2065, and 2763 genes and 1190, 812, and 958 metabolites were differentially expressed in the BP-B, BP-W and W-B comparisons, respectively. GO and KEGG analyses of the DEGs revealed that the most significant differences between under polarized light and ordinary light sources were in pathways related to microtubules, UDP-glycosyltransferase activity and microtubule binding. Metabolome analysis revealed that the expression of melanoside A, 1-methyl-L-histidine, and rhapontigenin 3'-O-glucoside were the SCMs most strongly affected by blue polarized light. The use of bidirectional orthogonal partial least squares analysis revealed a significant transcriptome-metabolome correlation in the BP-W and BP-B comparisons. Joint analysis of DEGs and SCMs revealed significant differences between polarized and ordinary light sources, mainly in terms of plant hormone signal transduction, zeatin biosynthesis, phenylpropanoid biosynthesis, and flavonoid biosynthesis. These results highlight that blue polarized light enhances flavonoid and phenylpropanoid metabolism, offering a strategy for improved secondary metabolite yield in cultivation.
Host molecule enhanced aggregation induced emission of chiral silver nanoclusters for achieving highly efficient circularly polarized electroluminescence
Chiral metal nanoclusters (MNCs) are competitive candidates for fabricating circularly polarized light-emitting diodes (CPLEDs), but the device performance is greatly limited by the poor emission of MNCs in solid thin films. Herein, host molecule enhanced aggregation induced emission (AIE) of MNCs is demonstrated for fabricating highly efficient CPLEDs. Namely, on the basis of the AIE effect of atomically precise enantiomeric ( R / S )-4-phenylthiazolidine-2-thione capped silver ( R / S -Ag 6 (PTLT) 6 ) NCs in solid thin films, 1,3-bis(carbazol-9-yl) benzene (mCP) is introduced as a host molecule to control the orientation and packing arrangements of R / S -Ag 6 (PTLT) 6 NCs through π—π interactions with the R / S -Ag 6 (PTLT) 6 NCs and further enhance the AIE. The as-fabricated Ag 6 (PTLT) 6 NC/mCP hybrid solid thin film shows a high photoluminescence quantum yield of 71.0% close to that of Ag 6 (PTLT) 6 NC single crystal. As the hybrid films are employed as the active emission layers of CPLEDs, mCP also suppresses the triplet-triplet annihilation and balances the charge transport. Thus, the CPLEDs exhibit a maximum brightness of 3,906 cd/m 2 , peak external quantum efficiency of 10.0%, and electroluminescence dissymmetry factors of −5.3 × 10 −3 and 4.7 × 10 −3 .