High Pressure phase transitions in BaWO4

Using in-situ angle dispersive x-ray diffraction, we have shown that barium tungstate, which exists in scheelite phase at ambient conditions, transforms to a new phase about seven giga pascal. Analysis of our data based on Le bail refinement suggests that this phase could be fergusonite and not mercuric molybdate type, which was proposed earlier from the Raman investigations. Beyond fourteen giga pascal this compound undergoes another phase transformation to a significantly disordered structure. Both the phase transitions are found to be reversible.Comment: 14 pages with 4 figures and 1 tabl

Vacuum-Ultraviolet and Ultraviolet Fluorescence and Absorption Studies of Er(3+)-Doped Liluf4 Single-Crystals

Journal URL: http://apl.aip.org/apl/top.js

Long-term oxidization and phase transition of InN nanotextures

The long-term (6 months) oxidization of hcp-InN (wurtzite, InN-w) nanostructures (crystalline/amorphous) synthesized on Si [100] substrates is analyzed. The densely packed layers of InN-w nanostructures (5-40 nm) are shown to be oxidized by atmospheric oxygen via the formation of an intermediate amorphous In-Ox-Ny (indium oxynitride) phase to a final bi-phase hcp-InN/bcc-In2O3 nanotexture. High-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, electron energy loss spectroscopy and selected area electron diffraction are used to identify amorphous In-Ox-Ny oxynitride phase. When the oxidized area exceeds the critical size of 5 nm, the amorphous In-Ox-Ny phase eventually undergoes phase transition via a slow chemical reaction of atomic oxygen with the indium atoms, forming a single bcc In2O3 phase

On the interconfigurational 4f25d-4f3 VUV and UV fluorescence features of Nd3+ in LiYF4 (YLF) single crystals under F2 laser pumping

Fluorescence spectra and kinetics of LiYF4(YLF):Nd3+ single crystals pumped by an F2 pulsed discharge molecular laser at 157 nm have been obtained in the VUV and UV regions of the spectrum between 150-300 nm. With this pumping scheme some new fluorescence peaks have been observed. The high photochemical stability of this material under the above pumping scheme suggests that it can be used as an active medium for VUV tunable laser sources. ft]1|Permanent address: Kazan State University, 18 Lenin Str., 420008 Kazan, Russian Federation. © 1992

Effect of Advanced Glycation End Products on Human Thyroglobulin's Antigenicity as Identified by the Use of Sera from Patients with Hashimoto's Thyroiditis and Gestational Diabetes Mellitus

Advanced glycation end products (AGEs) are formed on proteins after exposure to high concentrations of glucose and modify protein's immunogenicity. Herein, we investigated whether the modification of thyroglobulin (Tg) by AGEs influences its antigenicity and immunogenicity. Human Tg was incubated in vitro with increasing concentrations of D-glucose-6-phosphate in order to produce Tgs with different AGE content (AGE-Tg). Native Tg and AGE-Tgs were used in ELISA to assess the serum antibody reactivity of two patient groups, pregnant women with gestational diabetes (GDM), and patients with Hashimoto's thyroiditis (HT). We produced in vitro AGE-Tg with low and high AGE content, 13 and 49 AGE units/mg Tg, respectively. All HT patients' sera presented the same antibody reactivity profile against native Tg and AGE-Tgs, indicating that the modification of Tg by AGEs did not alter its antigenicity. Similarly, the GDM patients' sera did not discriminate among the two forms of Tg, native or artificially glycated, suggesting that the modification of Tg by AGEs might not alter its immunogenicity. The modification of Tg by AGEs has no obvious effect on neither its antigenicity nor, most likely, its immunogenicity. It seems that other Tg modifications might account for the production of aTgAbs in patients with GDM

VUV and UV fluorescence and absorption studies of Nd3+ and Ho3+ ions in LiYF4 single crystals

The laser induced fluorescence spectra of LiYF4:ND3+ (YLF:Nd) and LiYF4:Ho3+ (YLF:Ho) 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. With this pumping arrangement a number of new fluorescence peaks were observed for the first time. They are assigned to the dipole allowed transitions 4f25d→4f3 and 4f95d→4f10 of the Nd3+ and Ho3+ ions, respectively. The absorption spectra of the same crystal samples in the VUV and UV spectral regions were taken as well. © 1994

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

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

Effects of pressure on the local atomic structure of CaWO4 and YLiF4: Mechanism of the scheelite-to-wolframite and scheelite-to-fergusonite transitions

The pressure response of the scheelite phase of CaWO4 (YLiF4) and the occurrence of the pressure induced scheelite-to-wolframite (M-fergusonite) transition are reviewed and discussed. It is shown that the change of the axial parameters under compression is related with the different pressure dependence of the W-O (Li-F) and Ca-O (Y-F) interatomic bonds. Phase transition mechanisms for both compounds are proposed. Furthermore, a systematic study of the phase transition in 16 different scheelite ABX4 compounds indicates that the transition pressure increases as the packing ratio of the anionic BX4 units around the A cations increases.Comment: 38 pages, 10 figures (Figure 5 corrected), accepted for publication in Journal of Solid State Chemistr