Crystal Structure and Magnetocaloric Effect of La0.80Ag0.15MnO3 Nanoparticles

Annealing of_ non stoichiometric La0.80Ag0.15MnO3 nanoparticles leads to the change of the crystal symmetry from Pnma to R3c and to almost doubling of its Curie temperature from 117 K to 317 K. This effect is due to the releasing of lattice distortions and strengthening of double exchange interaction. The large values of the magnetocaloric entropy of the order of ∆S = 6.19 J/(kg K) were observedat ∆µ0H = 5 T and T = 315 K.Proceedings of the 17th Czech and Slovak Conference on Magnetism, Košice, Slovakia, June 3–7, 2019

Magnetic Properties of NdFe0.9Mn0.1O3

In our paper we study effect of Mn for Fe substitution on magnetic properties of NdFex-1MnxO3 compounds for x = 0 and 0.1, which have been grown by the OFZ technique. The Neel temperature decreases from T-N1 = 691 K to T-N1 = 621 K, and the anomaly in AC susceptibility, related to spin reorientation, vanishes with Mn substitution. Low temperature heat capacity measurement for sample with x = 0.1 revealed that substitution of Mn for Fe shifts a Schottky-type anomaly at T-sh to higher temperatures. Another anomaly is generated by doping at T-max = 11 K. The anomaly is smeared out by magnetic field, confirming its magnetic origin.15th Czech and Slovak Conference on Magnetism (CSMAG), Jun 17-21, 2013, Kosice, Slovaki

Exchange Bias Effect in NdFeO3 System of Nanoparticles

We study the effect of nanometric size on the crystal structure, magnetic environment of iron and magnetization in NdFeO3 system of nanoparticles. The average particle size of NdFeO3 nanoparticles increases with annealing at 600 degrees C from about 15 nm to 40 nm, The smallest particles on annealed sample have size approximately 30 nm and typically have character of single crystalline samples. All samples adopt orthorhombic crystal structure, space group Prima with lattice parameters a = 5.5817 angstrom, b = 7.7663 angstrom and c = 5.456 angstrom for as prepared sample. The presence of superparamagnetic particles was indicated by the Mossbauer measurements. The reduction of dimensionality induces a decrease of T-N1 from 691 K to 544 K. The shift of magnetic hysteresis loop in vertical and horizontal direction was observed at low temperatures after cooling in magnetic field. We attribute such behaviour to exchange bias effect and discuss in the frame of core shellmodel.16th Czech and Slovak Conference on Magnetism (CSMAG), Jun 13-17, 2016, Kosice, Slovaki

Magnetic Properties and Mossbauer spectroscopy of NdFe(1-x)MnxO(3)

The effect of particle reduction to nanoscale size and substitution of Mn3+ ions for Fe3+ ions on the crystal structure, lattice dynamics, Mossbauer spectra and magnetic properties in NdFe(1-x)MnxO(3) compounds have been studied. X-ray powder diffraction and Raman spectroscopy revealed that the Jahn-Teller distortion of lattice dominates for samples with x GT 0.4. The average particle size of NdFeO3 nanoparticles (NAP) increases with annealing at 600 degrees C from about 15 nm to 25 nm. The presence of superparamagnetic particles was indicated by Mossbauer measurements in NdFeO3 NAP system. Sextets in NdFe(1-x)MnxO(3) Mssbauer spectra can be modelled with several local environments of Fe3+ induced by substitution. The reduction of dimensionality and the substitution induce a decrease of the Neel temperature T-Nl from 691 K to 544 K for NAP or to 356 K for x = 0.4, however the temperature of spin reorientation T-SR increases with substitution. The saturated magnetization obtained at 1.9 K increases and ferromagnetic component is removed below T-SR with the substitution.International Conference on Strongly Correlated Electron Systems (SCES), Jul 07-14, 2014, Univ Grenoble, Grenoble, Franc

Strain relaxation dynamics of multiferroic orthorhombic manganites

Abstract: Resonant ultrasound spectroscopy has been used to characterise strain coupling and relaxation behavior associated with magnetic/magnetoelectric phase transitions in GdMnO3, TbMnO3 and TbMn0.98Fe0.02O3 through their influence on elastic/anelastic properties. Acoustic attenuation ahead of the paramagnetic to colinear-sinusoidal incommensurate antiferromagnetic transition at ∼41 K correlates with anomalies in dielectric properties and is interpreted in terms of Debye-like freezing processes. A loss peak at ∼150 K is related to a steep increase in electrical conductivity with a polaron mechanism. The activation energy, E a, of ≳0.04 eV from a loss peak at ∼80 K is consistent with the existence of a well-defined temperature interval in which the paramagnetic structure is stabilised by local, dynamic correlations of electric and magnetic polarisation that couple with strain and have relaxation times in the vicinity of ∼10−6 s. Comparison with previously published data for Sm0.6Y0.4MnO3 confirms that this pattern may be typical for multiferroic orthorhombic RMnO3 perovskites (R = Gd, Tb, Dy). A frequency-dependent loss peak near 10 K observed for TbMnO3 and TbMn0.98Fe0.02O3, but not for GdMnO3, yielded E a ⩾ ∼0.002 eV and is interpreted as freezing of some magnetoelastic component of the cycloid structure. Small anomalies in elastic properties associated with the incommensurate and cycloidal magnetic transitions confirm results from thermal expansion data that the magnetic order parameters have weak but significant coupling with strain. Even at strain magnitudes of ∼0.1–1‰, polaron-like strain effects are clearly important in defining the development and evolution of magnetoelectric properties in these materials. Strains associated with the cubic–orthorhombic transition due to the combined Jahn–Teller/octahedral tilting transition in the vicinity of 1500 K are 2–3 orders of magnitude greater. It is inevitable that ferroelastic twin walls due to this transition would have significantly different magnetoelectric properties from homogeneous domains due to magnetoelastic coupling with steep strain gradients

Increased susceptibility of Huh7 cells to HCV replication does not require mutations in RIG-I

<p>Abstract</p> <p>Background</p> <p>The cytosolic retinoic acid-inducible gene I (RIG-I) is a pattern recognition receptor that senses HCV double-stranded RNA and triggers type I interferon pathways. The clone Huh7.5 of human hepatoma Huh7 cells contains a mutation in RIG-I that is believed to be responsible for the improved replication of HCV in these cells relative to the parental strain. We hypothesized that, in addition to RIG-I, other determinant(s) outside the RIG-I coding sequence are involved in limiting HCV replication in cell culture. To test our hypothesis, we analyzed Huh7 cell clones that support the efficient replication of HCV and analyzed the RIG-I gene.</p> <p>Results</p> <p>One clone, termed Huh7D, was more permissive for HCV replication and more efficient for HCV-neomycin and HCV-hygromycin based replicon colony formation than parental Huh7 cells. Nucleotide sequence analysis of the RIG-I mRNA coding region from Huh7D cells showed no mutations relative to Huh7 parental cells.</p> <p>Conclusions</p> <p>We derived a new Huh7 cell line, Huh7D, which is more permissive for HCV replication than parental Huh7 cells. The higher permissiveness of Huh7D cells is not due to mutations in the RIG-I protein, indicating that cellular determinants other than the RIG-I amino-acid sequence are responsible for controlling HCV replication. In addition, we have selected Huh7 cells resistant to hygromycin via newly generated HCV-replicons carrying the hygromycin resistant gene. Further studies on Huh7D cells will allow the identification of cellular factors that increased the susceptibility to HCV infection, which could be targeted for anti-HCV therapies.</p

Plasma acylcarnitine concentrations reflect the acylcarnitine profile in cardiac tissues

Funding Information: This study was supported by the Latvian National Research Program BIOMEDICINE. E. Liepinsh was supported by the FP7 project InnovaBalt [grant Nr. 316149]. We would like to thank Dr. Reinis Vilskersts and Gita Dambrova for help with the isolated skeletal muscle experiments. Publisher Copyright: © 2017 The Author(s).Increased plasma concentrations of acylcarnitines (ACs) are suggested as a marker of metabolism disorders. The aim of the present study was to clarify which tissues are responsible for changes in the AC pool in plasma. The concentrations of medium- and long-chain ACs were changing during the fed-fast cycle in rat heart, muscles and liver. After 60 min running exercise, AC content was increased in fasted mice muscles, but not in plasma or heart. After glucose bolus administration in fasted rats, the AC concentrations in plasma decreased after 30 min but then began to increase, while in the muscles and liver, the contents of medium- and long-chain ACs were unchanged or even increased. Only the heart showed a decrease in medium- and long-chain AC contents that was similar to that observed in plasma. In isolated rat heart, but not isolated-contracting mice muscles, the significant efflux of medium- and long-chain ACs was observed. The efflux was reduced by 40% after the addition of glucose and insulin to the perfusion solution. Overall, these results indicate that during fed-fast cycle shifting the heart determines the medium- and long-chain AC profile in plasma, due to a rapid response to the availability of circulating energy substrates.publishersversionPeer reviewe