Perfect polarization vortices (PPVs) are a type of vector beam with a diameter independent of the polarization order. In this paper, an experimental method is proposed to generate PPVs with an anisotropic polarization distribution. First, a specially designed hologram is generated on a liquid-crystal spatial light modulator (SLM) to obtain Bessel-Gaussian (BG) beams. Second, the BG beams are transformed into PPVs in the Bessel region by an interferometer, which includes a polarized beam splitter, two reflectors, and several lenses. In our experiment, PPVs with adjustable polarization orders and diameters are obtained by generating various combined holograms on the SLM.
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http://dx.doi.org/10.1364/AO.56.007567 | DOI Listing |
Chemphyschem
January 2025
Southern Methodist University, Chemistry, 3251 Daniel Ave, 75275, Dallas, UNITED STATES.
We analyzed the intrinsic strength of distal and proximal FeN bonds and the stiffness of the axial NFeN bond angle in a series of cytochrome b5 proteins isolated from various species, including bacteria, animals, and humans. Ferric and ferrous oxidation states were considered. As assess- ment tool, we employed local vibrational stretching force constants ka(FeN) and bending force constants ka(NFeN) derived from our local mode theory.
View Article and Find Full Text PDFNeuroscientist
January 2025
Neurology Service, Lille Catholic Institute Hospital Group, (Groupe Hospitalier de l'Institut Catholique de Lille), GHICL, Lomme cedex, France.
The legacy of Santiago Ramón y Cajal, Spain's first Nobel laureate neuroscientist recognized as the founding father of modern neuroscience, is to be preserved in a new museum in Madrid: the National Museum of Natural Sciences (MNCN), one of the most important scientific research institutes in the country sciences in the scope of natural sciences of the Spanish National Research Council. For a boy who dreamed of being an artist but started his career apprenticed to first a barber and then a cobbler, Santiago Ramón y Cajal made a distinguished mark in science. One of Cajal's most important contributions to our understanding of the brain was his discovery of the direction of the information flow within neurons and in neural circuits, which he called the "dynamic polarization law," without a doubt the founding principle of neurosciences.
View Article and Find Full Text PDFNature
January 2025
Manchester Institute of Biotechnology, The University of Manchester, Manchester, UK.
Nucleophilic aromatic substitutions (SAr) are amongst the most widely used processes in the pharmaceutical and agrochemical industries, allowing convergent assembly of complex molecules through C-C and C-X (X = O, N, S) bond formation. SAr reactions are typically carried out using forcing conditions, involving polar aprotic solvents, stoichiometric bases and elevated temperatures, which do not allow for control over reaction selectivity. Despite the importance of SAr chemistry, there are only a handful of selective catalytic methods reported that rely on small organic hydrogen-bonding or phase-transfer catalysts.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
School of Electronics and IoT, Chongqing Polytechnic University of Electronic Technology, Chongqing, China.
This study proposes a spin-valley electron beam splitter based on the inner-edge states in a topological-insulator junction, which can allocate different ratios of spin-valley current outputs. Since the inner-edge states are associated with the "nearest path selection" mechanism, this device is referred to as the interface-modulating spin-valley electron beam splitter. Additionally, two perfect spin-valley filters in similar topological-insulator junctions are established in this study.
View Article and Find Full Text PDFSci Rep
December 2024
Department of Electronics, Carleton University, Ottawa, ON, K1S 5B6, Canada.
In this paper, we propose a novel structure of anisotropic graphene-based hyperbolic metamaterial (AGHMM) sandwiched as a defect between two one-dimensional photonic crystals (PCs) in the terahertz (THz) region. The proposed structure is numerically simulated and analyzed using the transfer matrix method, effective medium theory and three-dimensional finite-difference time-domain. The defect layer of AGHMM consists of graphene sheets separated by subwavelength dielectric spacers.
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