We describe a prototype element for use in probing electro-optic retro-reflection in sensor applications, illuminating a planar-aligned nematic liquid crystal electro-optic cell with convergent light having a single, tunable angle of incidence (tunable conical illumination). This illumination is generated using a 100X, high numerical aperture, long working-distance microscope objective under conditions of extreme spherical aberration. The electro-optic effect observed is multiple-beam optical interference between polarized reflections from the two bounding plates of the cell, rendered tunable with voltage-controlled refractive index changes induced by molecular reorientation of the liquid crystal. Characterization of the reflectivity vs. angle of incidence and applied voltage enables identification of conditions of high-contrast, low power, electro-optic reflectivity control applicable to fiber optics.
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http://dx.doi.org/10.1364/OE.27.018383 | DOI Listing |
Anat Histol Embryol
January 2025
Laboratório de Morfologia e Atividade Física, São Paulo State University, Rio Claro, São Paulo, Brazil.
Collared Peccary (Pecari tajacu, Linnaeus, 1758) is a mammalian Tayassuidae species from tropical to semi-arid areas. The morphological features of the oral cavity in this species were identified and described. Tonsils are secondary lymphoid organs essential for contact with antigens due to food and air intake.
View Article and Find Full Text PDFJ Chem Theory Comput
January 2025
Department of Theoretical Physics, University of Debrecen, P.O. Box 400, Debrecen H-4002, Hungary.
The coupling of matter to the quantized electromagnetic field of a plasmonic or optical cavity can be harnessed to modify and control chemical and physical properties of molecules. In optical cavities, a term known as the dipole self-energy (DSE) appears in the Hamiltonian to ensure gauge invariance. The aim of this work is twofold.
View Article and Find Full Text PDFBiochemistry
January 2025
Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China.
Large Stokes shift red fluorescent proteins (LSS-RFPs) are of growing interest for multicolor bioimaging applications. However, their photochemical mechanisms are not fully understood. Here, we employed the QM(XDW-CASPT2//CASSCF)/MM method to investigate the excited-state proton transfer and photoisomerization processes of the LSS-RFP mKeima starting from its cis neutral isomer.
View Article and Find Full Text PDFJ Org Chem
January 2025
Department of Organic Chemistry and Biochemistry, Rud̵er Bošković Institute, Bijenička Cesta 54, Zagreb 10 000, Croatia.
BODIPY photocages (photocleavable protective groups) have stirred interest because they can release biologically active cargo upon visible light excitation. We conducted combined theoretical and experimental investigations on selected BODIPY photocages to elucidate the mechanism of the competing photocleavage at the boron and -position. Based on the computations, the former reaction involves elongation of the B-C bond, yielding a tight borenium cation and methyl anion.
View Article and Find Full Text PDFIt is well-known that both the phase velocity surface and the ray velocity surface of a biaxial crystal have two layers that touch each other at only four points. However, we show that the two layers of the group velocity surface of a biaxial crystal penetrate through each other and form four inverted zones. Inside an inverted zone, the slow and fast light pulses are carried by the fast and slow modes of rays, respectively.
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