6,035 research outputs found
Location of the Energy Levels of the Rare-Earth Ion in BaF2 and CdF2
The location of the energy levels of rare-earth (RE) elements in the energy
band diagram of BaF2 and CdF2 crystals is determined. The role of RE3+ and RE2+
ions in the capture of charge carriers, luminescence, and the formation of
radiation defects is evaluated. It is shown that the substantial difference in
the luminescence properties of BaF2:RE and CdF2:RE is associated with the
location of the excited energy levels in the band diagram of the crystals
NMR and dc-susceptibility studies of NaVGe2O6
We report the results of measurements of the dc magnetic susceptibility
chi(T) and of the 23Na nuclear magnetic resonance (NMR) response of NaVGe2O6, a
material in which the V ions form a network of interacting one-dimensional spin
S=1 chains. The experiments were made at temperatures between 2.5 and 300 K.
The chi(T) data suggest that the formation of the expected low-temperature
Haldane phase is intercepted by an antiferromagnetic phase transition at 18 K.
The transition is also reflected in the 23Na NMR spectra and the corresponding
spin-lattice relaxation rate 1/T1(T). In the ordered phase, 1/T1(T) decreases
by orders of magnitude with decreasing temperature, indicating the formation of
a gap of the order of 12 K in the magnetic excitation spectrum.Comment: 10 pages, 15 figures; v2 with minor revisions of the tex
Genetic models of osteochondroma onset and neoplastic progression: evidence for mechanisms alternative to EXT genes inactivation
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Noise minimised high resolution digital holographic microscopy applied to surface topography
The topography of surface relief gratings was studied by digital holographic microscopy. The applicability of the method for quantitative measurements of surface microstructure at nanoscale was demonstrated. The method for wavefront reconstruction of surface relief from a digital hologram recorded in off-axis configuration was also applied. The main feature is noise filtration due to the presence of noise in the recorded intensity distribution and the use of all orders of the hologram. Reconstruction results proved a better effectiveness of our approach for topography studying of relief grating patterned on a ChG As2S3 – Se nanomultilayers in comparison with standard Fourier Transform and Atom Force Microscope methods.We express our gratitude to the Materials for Photovoltaic and Photonics Laboratory of the Institute of Applied Physics of the Academy of Sciences of Moldova for the samples preparing. Funding of work: the H2020-TWINN-2015 HOLO-project (687328); the Academy of Finland project 287150, 2015-2019
A real-world study on unmet medical needs in triptan-treated migraine: Prevalence, preventive therapies and triptan use modification from a large Italian population along two years
Although migraine is a disabling neurological condition that causes important disability, it remains an area of underdiagnosis and undertreatment worldwide. The aim of this study was to depict the burden of the unmet medical needs in migraine treated with triptans in a large Italian population
From Freudenthal’s spectral theorem to projectable hulls of unital Archimedean lattice-groups, through compactifications of minimal spectra
We use a landmark result in the theory of Riesz spaces \u2013 Freudenthal\u2019s 1936 spectral theorem \u2013 to canonically represent any Archimedean lattice-ordered group G with a strong unit as a (non-separating) lattice-group of real-valued continuous functions on an appropriate G-indexed zero-dimensional compactification w_G(Z_G)) of its space Z_G of minimal prime ideals. The two further ingredients needed to establish this representation are the Yosida representation of G on its space X_G of maximal ideals, and the well-known continuous surjection of Z_G onto X_G. We then establish our main result by showing that the inclusion-minimal extension of this representation of G that separates the points of Z_G \u2013 namely, the sublattice subgroup of C(Z_G) generated by the image of G along with all characteristic functions of clopen (closed and open) subsets of Z_G which are determined by elements of G \u2013 is precisely the classical projectable hull of G. Our main result thus reveals a fundamental relationship between projectable hulls and minimal spectra, and provides the most direct and explicit construction of projectable hulls to date. Our techniques do require the presence of a strong unit
Ce-doped Li6Ln(BO3)3 (Ln = Y, Gd) Single crystals fibers grown by micro-pulling down method and luminescence properties
Ce3+-doped borate crystal fibers of Li6Gd(BO 3)3 (LGBO) and Li6Y(BO3)3 (LYBO) compositions are grown by the micro-pulling down (μ-PD) method for potential application in developing new neutron detectors. The ternary equilibrium diagram of Li2O-Gd2O3-B 2O3 is drawn and the preparations of homogeneous mixed LGBO and LYBO powders and growth conditions for single crystal fibers are discussed. Absorption, excitation and X-ray luminescence spectra are investigated. Absolute light yield derived from energy spectra and kinetic decay curves measured under α- and γ-scintillations of Ce 3+-doped LGBO and LYBO single crystal fibers is provided. © 2012 Elsevier B.V. All rights reserved
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