Using the coupled wave approach (CWA), we introduce the analytical theory for alternate multilayer grating (AMG) operating in the single-order regime, in which only one diffraction order is excited. Differing from previous study analogizing AMG to crystals, we conclude that symmetrical structure, or equal thickness of the two multilayer materials, is not the optimal design for AMG and may result in significant reduction in diffraction efficiency. The peculiarities of AMG compared with other multilayer gratings are analyzed. An influence of multilayer structure materials on diffraction efficiency is considered. The validity conditions of analytical theory are also discussed.
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http://dx.doi.org/10.1364/OE.25.015987 | DOI Listing |
Chemistry
January 2025
TU Chemnitz: Technische Universitat Chemnitz, Insitut für Chemie, Straße der Nationen 62, 09111, Chemnitz, GERMANY.
The intramolecular migration of three hydrogen atoms from one moiety of a gaseous radical cation to the other prior to fragmentation is an extremely rare type of redox reaction. Within the scope of this investigation, this scenario requires an ionized but electron-rich arene acceptor bearing a para-(3-hydroxyalkyl) residue. The precise mechanism of such unidirectional 3H transfer processes, including the order of the individual H transfer steps, has remained unclear in spite of previous isotope labelling and recent infrared ion spectroscopy (IRIS) studies.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006, P. R. China.
Electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) is a promising alternative for oxygen evolution reactions. The search for efficient catalysts has been attracting increasing scientific attention. This work explores the performance of nitrogen-doped graphene-supported single-atom catalysts (M-NC SACs) for the reaction.
View Article and Find Full Text PDFBiochem Soc Trans
January 2025
Centre for Plant Molecular Biology, University of Tübingen, Tübingen 72076, Germany.
Primary axis formation is the first step of embryonic patterning in flowering plants and recent findings highlight the importance of parent-of-origin effects in this process. Apical-basal patterning has a strong influence on suspensor development, an extra-embryonic organ involved in nutrient transport to the embryo at an early stage of seed development. The endosperm, a second fertilization product, nourishes the embryo at later stages of seed development.
View Article and Find Full Text PDFSoc Sci Med
January 2025
Health Economics Unit, Institute of Applied Health Research, University of Birmingham, UK. Electronic address:
Recent years have seen an emphasis on delivering mental health and wellbeing support in school settings. However, the process by which schools meet this resource allocation challenge is largely undocumented. Our study used theory-building process tracing to develop a mechanistic understanding of the process of mental health investment in schools.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
January 2025
Department of Biology, University of Oxford, Oxford OX1 3SZ, United Kingdom.
Experiments have shown that when one plant is attacked by a pathogen or herbivore, this can lead to other plants connected to the same mycorrhizal network up-regulating their defense mechanisms. It has been hypothesized that this represents signaling, with attacked plants producing a signal to warn other plants of impending harm. We examined the evolutionary plausibility of this and other hypotheses theoretically.
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