71 research outputs found
dimer paramagnetic centers in lead germanate crystals doped with iron and halogen (Cl-, Br-, F-) ions
The dimer complexes Fe3+-Cl-, Fe3+-Br-, and Fe3+-O2- in ferroelectric lead germanate crystals doped with iron and annealed in chlorine-, bromine-, and fluorine-containing atmospheres have been studied using the electron paramagnetic resonance method. These complexes are formed by Fe3+ ions in the trigonal position of lead and their associated anions located in the interstitial channel of the structure. The positions of the charge-compensating anions in the channel have been discussed based on the analysis of the parameters of the spin Hamiltonian and their temperature dependence. © 2013 Pleiades Publishing, Ltd
Electron paramagnetic resonance of Gd3+ ions in Ca1-x-yYxGdyF2+x+y crystals
Electron paramagnetic resonance of Ca1-x-yYxGdyF2+x+y single crystals has revealed spectra that are not typical of gadolinium-doped CaF2 crystals. These spectra have a nearly tetragonal symmetry and are most probably caused by Gd3+ ions localized in yttrium clusters. Weak spectra of tetragonal Gd3+ centers, whose parameters are close to those of a cubic gadolinium center caused by an isolated Gd3+ ion, have been also detected. These centers are attributed to isolated Gd3+ ions localized near octahedral rare-earth clusters or their associations. © 2013 Pleiades Publishing, Ltd
Specific features of the electron paramagnetic resonance spectrum in the vicinity of the convergence of the transitions of gadolinium centers in Pb5(Ge1 - xSix)3O11
An anomalous electron paramagnetic resonance spectrum of the transitions -1/2 ↔ +1/2 of four Gd3+-Si dimer clusters in the Pb5(Ge1 - xSix)3O11 crystals doped with gadolinium has been found in the vicinity of the orientation of the magnetic field along the optic axis of the crystal. It has been assumed that this spectrum is caused by rapid transitions between the spin packets of the initial resonances due to the crossrelaxation. A computer simulation of the spectrum has been carried out. The results obtained adequately describe the experiment. © 2013 Pleiades Publishing, Ltd
Thermodynamics and Phase Transitions of Electrolytes on Lattices with Different Discretization Parameters
Lattice models are crucial for studying thermodynamic properties in many
physical, biological and chemical systems. We investigate Lattice Restricted
Primitive Model (LRPM) of electrolytes with different discretization parameters
in order to understand thermodynamics and the nature of phase transitions in
the systems with charged particles. A discretization parameter is defined as a
number of lattice sites that can be occupied by each particle, and it allows to
study the transition from the discrete picture to the continuum-space
description. Explicit analytic and numerical calculations are performed using
lattice Debye-H\"{u}ckel approach, which takes into account the formation of
dipoles, the dipole-ion interactions and correct lattice Coulomb potentials.
The gas-liquid phase separation is found at low densities of charged particles
for different types of lattices. The increase in the discretization parameter
lowers the critical temperature and the critical density, in agreement with
Monte Carlo computer simulations results. In the limit of infinitely large
discretization our results approach the predictions from the continuum model of
electrolytes. However, for the very fine discretization, where each particle
can only occupy one lattice site, the gas-liquid phase transitions are
suppressed by order-disorder phase transformations.Comment: Submitted to Molecular Physic
Paramagnetic resonance of LaGaO3: Mn single crystals grown by floating zone melting
© 2016, Pleiades Publishing, Ltd. The EPR spectrum of Mn-doped lanthanum gallate single crystals grown by floating zone melting with optical heating has been studied. In contrast to the crystals grown according to the Czochralski method, no manganese is found in these crystals even after high-temperature annealing in air. The spectral characteristics of Fe3+ and Gd3+ centers in crystals prepared by various methods have been compared in the rhombohedral phase, and the fourth-rank nondiagonal parameters of the Fe3+ trigonal centers have been determined, as well
Network integration of parallel metabolomics and transcirptional data reveals metabolic modules that regulate macrophage polarization
Macrophage polarization involves a coordinated metabolic and transcriptional rewiring that is only partially understood. By using an integrated high-throughput transcriptional-metabolic profiling and analysis pipeline, we characterized systemic changes during murine macrophage M1 and M2 polarization. M2 polarization was found to activate glutamine catabolism and UDP-GlcNAc-associated modules. Correspondingly, glutamine deprivation or inhibition of N-glycosylation decreased M2 polarization and production of chemokine CCL22. In M1 macrophages, we identified a metabolic break at Idh, the enzyme that converts isocitrate to alpha-ketoglutarate, providing mechanistic explanation for TCA cycle fragmentation. 13C-tracer studies suggested the presence of an active variant of the aspartate-arginosuccinate shunt that compensated for this break. Consistently, inhibition of aspartate-aminotransferase, a key enzyme of the shunt, inhibited nitric oxide and interleukin-6 production in M1 macrophages, while promoting mitochondrial respiration. This systems approach provides a highly integrated picture of the physiological modules supporting macrophage polarization, identifying potential pharmacologic control points for both macrophage phenotypes
Aproximación integral a la evaluación del progreso hacia la sostenibilidad
Traducción: Patricia M. Bartol de lmbachVersión en inglés disponible en la Biblioteca Digital del IDRC: Community-based indicators : a guide for field workers carrying out monitoring and assessment at the community levelVersión en francés disponible en la Biblioteca Digital del IDRC: Indicateurs communautaires : guide à l'intention des travailleurs sur le terrain faisant des travaux de contrôle et d'évaluation communautaire
The Initial Stage of Neck Formation in an Х-Pinch
A model is proposed to describe the initial stage of neck formation in an X-pinch that proceeds in three stages: the electrical explosion of metal wires that generates the X-pinch; the expansion of the wire material that occurs due to an excess of the gas-kinetic pressure over the pressure of the magnetic field. The model allows one to predict the minimum rate of current rise at which the formation of a "hot spot" in an X-pinch is possible. The minimum current rise rate is determined by the thermodynamic parameters of the wires at a critical point; it is of the order of 1 kA/ns
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