Polarization gating is a popular technique in biomedical optics. It is widely used to inspect the surface of the tissues (under colinear or cocircular detection) or instead to probe the volume (cross-linear detection), without information on the probed depth. Elliptical polarization is introduced to explore the possibility of probing diffuse tissues at selective depths. A thorough Monte Carlo simulation study shows complete correlation between the probed depths and the ellipticity of the polarized light, for a medium with known optical properties. Within a wide range of optical parameters, a linear relation between the backscattered intensity and the depth extension of the probed volume was found whatever the polarization used, but with a controlled extension depending on the ellipticity.
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http://dx.doi.org/10.1117/1.JBO.18.1.016007 | DOI Listing |
Proc Natl Acad Sci U S A
January 2025
Department of Chemical Engineering, Stanford University, Stanford, CA 94305.
The crowded bacterial cytoplasm is composed of biomolecules that span several orders of magnitude in size and electrical charge. This complexity has been proposed as the source of the rich spatial organization and apparent anomalous diffusion of intracellular components, although this has not been tested directly. Here, we use biplane microscopy to track the 3D motion of self-assembled bacterial genetically encoded multimeric nanoparticles (bGEMs) with tunable size (20 to 50 nm) and charge (-3,240 to +2,700 e) in live cells.
View Article and Find Full Text PDFSmall Methods
January 2025
Forschungszentrum Juelich GmbH, Institute of Energy Technologies, IET-4, Electrochemical Process Engineering, 52425, Juelich, Germany.
Understanding the sheet resistance of porous electrodes is essential for improving the performance of polymer electrolyte membrane (PEM) water electrolyzers and related technologies. Despite its importance, existing methods often fail to provide reliable and comprehensive data, especially for porous materials with complex morphologies and non-uniform thicknesses. This study introduces a robust and straightforward method for determining the sheet resistance of porous electrodes using a novel probe concept based on industrial printed circuit board (PCB) technology.
View Article and Find Full Text PDFJ Phys Chem B
January 2025
Chemical Sciences Department, Homi Bhabha National Institute, Mumbai 400094, India.
This study delves into the interplay of temperature, composition, tortuosity, and electrostatic interactions on ion diffusion within cation exchange membranes. It explores the temperature dependence (16-60 °C) of the self-diffusion coefficients (SDCs) of Ba and Eu ions within the Nafion 117 cation exchange membrane, particularly in the presence of Na ions. Radiotracer techniques and electrochemical impedance spectroscopy were employed to investigate these SDCs.
View Article and Find Full Text PDFCarbohydr Polym
March 2025
Biophysics and Medical Technology, Department of Physics, NTNU Norwegian University of Science and Technology, Trondheim, Norway.
Schizophyllan (SPG) is a semi-flexible, triple-helical polysaccharide with attractive properties as an efficient viscosifying compound and biological response modifier. We report microrheological characterization of schizophyllan as dispersed in solution and the changes associated when crosslinked with chitosan over an extended frequency range using diffusing wave spectroscopy (DWS). A SPG with high molecular weight (M = 1.
View Article and Find Full Text PDFCell Struct Funct
January 2025
Department of Pathology and Biology of Diseases, Graduate School of Medicine, Kyoto University.
Live imaging techniques have revolutionized our understanding of paracrine signaling, a crucial form of cell-to-cell communication in biological processes. This review examines recent advances in visualizing and tracking paracrine factors through four key stages: secretion from producing cells, diffusion through extracellular space, binding to target cells, and activation of intracellular signaling within target cells. Paracrine factor secretion can be directly visualized by fluorescent protein tagging to ligand, or indirectly by visualizing the cleavage of the transmembrane pro-ligands or plasma membrane fusion of endosomes comprising the paracrine factors.
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