On the 4f25d → 4f3 interconfigurational transitions of Nd3+ ions in K2YF5 and LiYF4 crystal hosts

The Laser Induced Fluorescence (LIF) spectrum of K2YF5:Nd3+ (PFYK:Nd) and LiYF4:Nd3+ (YLF:Nd) single crystals, pumped by the fluorine F2 pulsed discharge molecular laser at 157.6 nm, was obtained in the Vacuum Ultraviolet (VUV) region of the spectrum. The fluorescence peaks were assigned to the 4f25d → 4f3 dipole allowed transitions of the Nd3+ ion. The 180 nm band of the LIF spectrum from the crystals indicates that the 4f25d → 4f3 dipole transitions originate from the low Stark components of the 4K11/2 level of the 4f25d configuration. The absorption spectrum of the crystal samples in the VUV was obtained as well and spectroscopic assignment of the levels of the 4f25d configuration was made. The electric crystal field splits all the levels of single and mixed configuration. The energy of the Stark components of the 4f25d configuration in YLF:Nd was shifted by few hundred cm-1 relative to that of PFYK:Nd. We observed eleven and nine dipole transitions, between the 4I9/2 ground level of the 4f3 configuration and the Stark components of the levels of the 4f25d configuration of the Nd3+ ion, in YLF and PFYK crystal hosts, respectively. © 1998 Elsevier Science B.V

On the VUV and UV 4f7(8S)5d > 4f8 interconfigurational transitions of Tb3+ ions in LiLuF4 single crystal hosts

The laser induced fluorescence spectrum of Tb3+ ions in LiLuF4 single crystals, pumped by a fluorine pulsed discharge molecular laser at 157.6 nm, was obtained in the vacuum ultraviolet (VUV) and ultraviolet (UV) regions of the spectrum. The 4f75d > 4f8 dipole allowed transitions originate from the Stark components and the edge of the levels of the 4f7(8S)5d electronic configuration. The LIF spectra were interpreted on the basis of phonon trapping and phonon reabsorption within the levels of the 4f75d electronic configuration. The absorption spectrum of the crystal samples in the VUV was obtained as well. We observed eight transitions between the ground level 4f8(7F6) and the Stark components of the levels of the 4f7(8S)5d electronic configuration and five transitions between the ground level 4f8(7F6) and the Stark components of the levels of the 4f7(6P)5d electronic configuration. The edge of the levels of the 4f75d electronic configuration was found to be at 45.2 × 103 ± 0.2 × 103 cm-1 and the band gap of the crystal host was 77.6 × 103 ± 0.3 × 103 cm-1 wide. © 1998 Elsevier Science B.V. All rights reserved

Answering SPARQL queries over databases under OWL 2 QL entailment regime

We present an extension of the ontology-based data access platform Ontop that supports answering SPARQL queries under the OWL 2 QL direct semantics entailment regime for data instances stored in relational databases. On the theoretical side, we show how any input SPARQL query, OWL 2 QL ontology and R2RML mappings can be rewritten to an equivalent SQL query solely over the data. On the practical side, we present initial experimental results demonstrating that by applying the Ontop technologies—the tree-witness query rewriting, T-mappings compiling R2RML mappings with ontology hierarchies, and T-mapping optimisations using SQL expressivity and database integrity constraints—the system produces scalable SQL queries

Tiny Rare-Earth Fluoride Nanoparticles Activate Tumour Cell Growth via Electrical Polar Interactions

© 2018, The Author(s). Localised extracellular interactions between nanoparticles and transmembrane signal receptors may well activate cancer cell growth. Herein, tiny LaF3 and PrF3 nanoparticles in DMEM+FBS suspensions stimulated tumour cell growth in three different human cell lines (A549, SW837 and MCF7). Size distribution of nanoparticles, activation of AKT and ERK signalling pathways and viability tests pointed to mechanical stimulation of ligand adhesion binding sites of integrins and EGFR via a synergistic action of an ensemble of tiny size nanoparticles (< 10 nm). While tiny size nanoparticles may be well associated with the activation of EGFR, integrin interplay with nanoparticles remains a multifaceted issue. A theoretical motif shows that, within the requisite pN force scale, each ligand adhesion binding site can be activated by a tiny size dielectric nanoparticle via electrical dipole interaction. The size of the active nanoparticle stayed specified by the amount of the surface charges on the ligand adhesion binding site and the nanoparticle, and also by the separating distance between them. The polar component of the electrical dipole force remained inversely proportional to the second power of nanoparticle’s size, evincing that only tiny size dielectric nanoparticles might stimulate cancer cell growth via electrical dipole interactions. The work contributes towards recognising different cytoskeletal stressing modes of cancer cells

Vacuum-ultraviolet interconfigurational 4f3 → 4f 25d absorption and emission studies of the Nd3+ ion in KYF, YF, and YLF crystal hosts

The laser-induced vacuum-ultraviolet fluorescence spectra of KY 3F10:Nd3+ (KYF:Nd) and YF3:Nd 3+ (YF:Nd) single crystals pumped by a pulsed-discharge molecular F2 laser at 157 nm were obtained. A number of new fluorescence peaks were observed and were assigned to the 4f 25d → 4f3 dipole-allowed transitions of the Nd3+ ion. The absorption spectra of LiYF4:Nd3+ (YLF:Nd), KYF:Nd, and YF:Nd crystal samples in the vacuumultraviolet spectral regions were also obtained. Finally, the splitting of the states of the 4f25d configuration of the Nd 3+ ion, which is due to the crystal field, was observed in all the crystal samples. © 1995 Optical Society of America

Surface profile gradient in amorphous Ta<inf>2</inf>O<inf>5</inf> semi conductive layers regulates nanoscale electric current stability

© 2016 The Author(s)A link between the morphological characteristics and the electric properties of amorphous layers is established by means of atomic, conductive, electrostatic force and thermal scanning microscopy. Using amorphous Ta2O5 (a-Ta2O5) semiconductive layer, it is found that surface profile gradients (morphological gradient), are highly correlated to both the electron energy gradient of trapped electrons in interactive Coulombic sites and the thermal gradient along conductive paths and thus thermal and electric properties are correlated with surface morphology at the nanoscale. Furthermore, morphological and electron energy gradients along opposite conductive paths of electrons intrinsically impose a current stability anisotropy. For either long conductive paths (L > 1 μm) or along symmetric nanodomains, current stability for both positive and negative currents i is demonstrated. On the contrary, for short conductive paths along non-symmetric nanodomains, the set of independent variables (L, i) is spanned by two current stability/intability loci. One locus specifies a stable state for negative currents, while the other locus also describes a stable state for positive currents

Surface profile gradient in amorphous Ta<inf>2</inf>O<inf>5</inf> semi conductive layers regulates nanoscale electric current stability

© 2016 The Author(s)A link between the morphological characteristics and the electric properties of amorphous layers is established by means of atomic, conductive, electrostatic force and thermal scanning microscopy. Using amorphous Ta2O5 (a-Ta2O5) semiconductive layer, it is found that surface profile gradients (morphological gradient), are highly correlated to both the electron energy gradient of trapped electrons in interactive Coulombic sites and the thermal gradient along conductive paths and thus thermal and electric properties are correlated with surface morphology at the nanoscale. Furthermore, morphological and electron energy gradients along opposite conductive paths of electrons intrinsically impose a current stability anisotropy. For either long conductive paths (L > 1 μm) or along symmetric nanodomains, current stability for both positive and negative currents i is demonstrated. On the contrary, for short conductive paths along non-symmetric nanodomains, the set of independent variables (L, i) is spanned by two current stability/intability loci. One locus specifies a stable state for negative currents, while the other locus also describes a stable state for positive currents

VUV and UV fluorescence and absorption studies of tb3+ and tm3+ trivalent ions in liyf4 single crystal hosts

The laser induced fluorescence spectra of LiYF4: Tb3+ (YLF: Tb) and LiYF4:Tm3+ (YLF: Tm) single crystals, pumped by an F2 pulsed discharge molecular laser at 157 nm, were obtained in the vacuum ultraviolet (VUV) and ultraviolet (UV) regions of the spectrum, at room temperature. A number of new fluorescence peaks were observed for the first time. They were assigned to the dipole allowed transitions 4f75d→4f8 and 4f115d→4f12 of Tb3+ and Tm3+ ions respectively. The absorption spectra of the same crystal samples in the VUV and UV regions were taken as well. The edge (onset) and the energy of the states with 4fN-1 5d configuration were determined. © 1994 Taylor and Francis Ltd

Surface profile gradient in amorphous Ta<inf>2</inf>O<inf>5</inf> semi conductive layers regulates nanoscale electric current stability

© 2016 The Author(s).A link between the morphological characteristics and the electric properties of amorphous layers is established by means of atomic, conductive, electrostatic force and thermal scanning microscopy. Using amorphous Ta2O5 (a-Ta2O5) semiconductive layer, it is found that surface profile gradients (morphological gradient), are highly correlated to both the electron energy gradient of trapped electrons in interactive Coulombic sites and the thermal gradient along conductive paths and thus thermal and electric properties are correlated with surface morphology at the nanoscale.Furthermore, morphological and electron energy gradients along opposite conductive paths of electrons intrinsically impose a current stability anisotropy. For either long conductive paths (L .>. 1. μm) or along symmetric nanodomains, current stability for both positive and negative currents . i is demonstrated. On the contrary, for short conductive paths along non-symmetric nanodomains, the set of independent variables (L, i) is spanned by two current stability/intability loci. One locus specifies a stable state for negative currents, while the other locus also describes a stable state for positive currents