301 research outputs found
X-ray Diffraction Study of Superstructure in GdBaCo2O5.5
A single crystal of GdBaCo2O5.47(2) has been studied by means of X-ray
diffraction. Appearance of superstructure reflections at T = 341.5(7) K gives
an evidence of continuous transition to the phase with unit cell doubled along
the shortest edge a1. Critical exponent for the order parameter is found to be
beta=0.33(1). The superstructure reflections are about 2-4 orders of magnitude
weaker than the basic ones. Their systematic extinction indicates the crystal
symmetry change from Pmmm to Pmma. The integrated intensities allow to
calculate displacements of atoms from the positions in the high-temperature
phase. The cobalt-ligand distances in the ordered phase are discussed in terms
of the spin-state/orbital ordering of Co3+ ions.Comment: 4 page
The alternatively spliced fibronectin CS1 isoform regulates IL-17A levels and mechanical allodynia after peripheral nerve injury.
BackgroundMechanical pain hypersensitivity associated with physical trauma to peripheral nerve depends on T-helper (Th) cells expressing the algesic cytokine, interleukin (IL)-17A. Fibronectin (FN) isoform alternatively spliced within the IIICS region encoding the 25-residue-long connecting segment 1 (CS1) regulates T cell recruitment to the sites of inflammation. Herein, we analyzed the role of CS1-containing FN (FN-CS1) in IL-17A expression and pain after peripheral nerve damage.MethodsMass spectrometry, immunoblotting, and FN-CS1-specific immunofluorescence analyses were employed to examine FN expression after chronic constriction injury (CCI) in rat sciatic nerves. The acute intra-sciatic nerve injection of the synthetic CS1 peptide (a competitive inhibitor of the FN-CS1/α4 integrin binding) was used to elucidate the functional significance of FN-CS1 in mechanical and thermal pain hypersensitivity and IL-17A expression (by quantitative Taqman RT-PCR) after CCI. The CS1 peptide effects were analyzed in cultured primary Schwann cells, the major source of FN-CS1 in CCI nerves.ResultsFollowing CCI, FN expression in sciatic nerve increased with the dominant FN-CS1 deposition in endothelial cells, Schwann cells, and macrophages. Acute CS1 therapy attenuated mechanical allodynia (pain from innocuous stimulation) but not thermal hyperalgesia and reduced the levels of IL-17A expression in the injured nerve. CS1 peptide inhibited the LPS- or starvation-stimulated activation of the stress ERK/MAPK pathway in cultured Schwann cells.ConclusionsAfter physical trauma to the peripheral nerve, FN-CS1 contributes to mechanical pain hypersensitivity by increasing the number of IL-17A-expressing (presumably, Th17) cells. CS1 peptide therapy can be developed for pharmacological control of neuropathic pain
Influence of Co spin-state on optical properties of LaCoO and HoCoO
Optical properties of the isoelectronic compounds LaCoO and HoCoO has
been experimentally and theoretically investigated. We've measured the real
and imaginary parts of the dielectric
function, reflectance and optical conductivity at room temperature.
The shift of the most pronounced spectral features to the high energy region on
0.3 eV associated with larger distortions due to the smaller rare earth ionic
radii in HoCoO in comparison with LaCoO was observed. Also there was
found an enhancement of absorption intensity in the range 1.3-2.3 eV in all
kinds of spectra in HoCoO, which can be attributed basing on the results of
LDA+U calculations to the different spin-states of Co ion in these
compounds. The shift of the onset of the absorption from less than 0.1 eV in
LaCoO to 0.7 eV in HoCoO and an absorption intensity enhancement in a
narrow spectral range 1.2-2.6 eV in HoCoO are clearly seen from the
calculated convolution of partial densities of states obtained in the LDA+U
approach. Such changes are assumed to be induced by the different Co
spin-state in these compounds at room temperature.Comment: 10 pages, 3 figure
On finite-difference approximations for normalized Bellman equations
A class of stochastic optimal control problems involving optimal stopping is
considered. Methods of Krylov are adapted to investigate the numerical
solutions of the corresponding normalized Bellman equations and to estimate the
rate of convergence of finite difference approximations for the optimal reward
functions.Comment: 36 pages, ArXiv version updated to the version accepted in Appl.
Math. Opti
The Hitting Times with Taboo for a Random Walk on an Integer Lattice
For a symmetric, homogeneous and irreducible random walk on d-dimensional
integer lattice Z^d, having zero mean and a finite variance of jumps, we study
the passage times (with possible infinite values) determined by the starting
point x, the hitting state y and the taboo state z. We find the probability
that these passages times are finite and analyze the tails of their cumulative
distribution functions. In particular, it turns out that for the random walk on
Z^d, except for a simple (nearest neighbor) random walk on Z, the order of the
tail decrease is specified by dimension d only. In contrast, for a simple
random walk on Z, the asymptotic properties of hitting times with taboo
essentially depend on the mutual location of the points x, y and z. These
problems originated in our recent study of branching random walk on Z^d with a
single source of branching
Structural effects in UO2 thin films irradiated with fission-energy Xe ions
Uranium dioxide thin films have been successfully grown on LSAT (Al10La3O51Sr14Ta7) substrates by reactive magnetron sputtering. Irradiation by 92 MeV 129Xe23+ ions to simulate fission damage that occurs within nuclear fuels caused microstructural and crystallographic changes. Initially flat and continuous thin films were produced by magnetron sputtering with a root mean square roughness of 0.35 nm determined by AFM. After irradiation, this roughness increased to 60–70 nm, with the films developing discrete microstructural features: small grains (∼3 μm), along with larger circular (up to 40 μm) and linear formations with non-uniform composition according to the SEM, AFM and EDX results. The irradiation caused significant restructuring of the UO2 films that was manifested in significant film-substrate mixing, observed through EDX analysis. Diffusion of Al from the substrate into the film in unirradiated samples was also observed
Soft and hard wall in a stochastic reaction diffusion equation
We consider a stochastically perturbed reaction diffusion equation in a
bounded interval, with boundary conditions imposing the two stable phases at
the endpoints. We investigate the asymptotic behavior of the front separating
the two stable phases, as the intensity of the noise vanishes and the size of
the interval diverges. In particular, we prove that, in a suitable scaling
limit, the front evolves according to a one-dimensional diffusion process with
a non-linear drift accounting for a "soft" repulsion from the boundary. We
finally show how a "hard" repulsion can be obtained by an extra diffusive
scaling.Comment: 33 page
Редокс-реакции у Hydrocharis morsus-ranae L. в условиях техногенной нагрузки
Aquatic ecosystems are very sensitive to industrial impacts, and, therefore, it is increasingly important to study the mechanisms underlying the tolerance of aquatic organisms to water pollution. Heavy metals (HMs) are among the most common and toxic pollutants of aquatic ecosystems. They have a particularly strong effect on macrophytes, which are in close contact with the aquatic environment and can accumulate metals in considerable quantities. Hydrocharis morsus-ranae L. is a floating macrophyte (pleistophyte) with a high capacity for accumulation of HMs. The aim of the present study was to assess the effect of industrial pollution on the redox reactions in H. morsus-ranae and to identify the role of low molecular weight antioxidants in adaptation of this macrophyte to unfavorable conditions. A comparative analysis of the physiological and biochemical characteristics of H. morsus-ranae from two (reference and impacted) water bodies was carried out. The study revealed an increased level of lipid peroxidation products in the leaves of H. morsus-ranae under industrial impact, which indicates oxidative stress. Nevertheless, this floating plant demonstrated fairly high resistance to adverse conditions, due to the synthesis of non-enzymatic antioxidants such as proline and soluble protein thiols. Revealing the response of macrophytes to pollution of water bodies will help predict the state of aquatic ecosystems with an increase in anthropogenic pressure. © Siberian Federal University. All rights reserved.Acknowledgements. The reported study was partly funded by RFBR and the Government of the Sverdlovsk Region, project number 20–45–660014. The authors are grateful to the reviewer, Prof., D. Sc. Golovko T. K. (Institute of Biology of Komi Scientific Centre of the Ural Branch of RAS, Syktyvkar) for valuable comments that helped improve this paper and to Dr. Tripti (Ural Federal University, Ekaterinburg, Russia) for editing the English language
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