Magnetic interactions in graphene decorated with iron oxide nanoparticles.

We present the studies of structural and magnetic properties of graphene composites prepared with several quantities ofα-Fe2O3dopant of 5%, 25% and 50% made with either ethanol or acetone. Our studies showed the presence of a weak magnetic order up to room temperature and saturation magnetization close to 0.2 emu g-1in pure commercial graphene. With regard to magnetic properties of our graphene + iron oxide samples, the solvent used during the preparation of the composite had a significant influence on them. For graphene + Fe2O3samples made with acetone the magnetic properties of pure graphene played a major role in the overall magnetic susceptibility and magnetization. On the other hand, for graphene + iron oxide samples made with ethanol we observed the presence of superparamagnetic blocking atT < 110 K which was due to the additional appearance ofγ-Fe3O4nanoparticles. Changes in the synthesis solvent played a major role in the magnetic properties of our graphene + Fe2O3nanocomposite samples resulting in much higher saturation magnetization for the samples made with ethanol. Both the shape and the parameters characterizing magnetization hysteresis loops depend strongly on the amount of iron oxide and changes in the preparation method.

Physical properties of the layered oxypnictide Sr2ScFeAsO3: a Mössbauer study down to 1.7 K.

A polycrystalline sample of Sr2ScFeAsO3 was studied by 57Fe Mössbauer spectroscopy down to 1.7 K. In contrast to the earlier Mössbauer data, the obtained in this work results indicate that Sr2ScFeAsO3 is in paramagnetic state down to 10 K, while the spectra recorded at 4.6 K and 1.7 K show a weak magnetic order of Fe moments in the Fe2As2 layers. Temperature dependences of isomer shift and quadrupole splitting/shift are compared with specific heat and electrical resistivity data from earlier investigations revealing different local Debye temperatures for the Fe2As2 and perovskite-related Sr2ScO3 layers. Finally, a fast decrease of the carrier density was observed below 80 K and this effect seems to be responsible for the absence of superconductivity in the studied compound.

Correction to: Iron oxides nanoparticles (IOs) exposed to magnetic field promote expression of osteogenic markers in osteoblasts through integrin alpha-3 (INTa-3) activation, inhibits osteoclasts activity and exerts anti-inflammatory action.

An amendment to this paper has been published and can be accessed via the original article.

Iron oxides nanoparticles (IOs) exposed to magnetic field promote expression of osteogenic markers in osteoblasts through integrin alpha-3 (INTa-3) activation, inhibits osteoclasts activity and exerts anti-inflammatory action.

BACKGROUND: Prevalence of osteoporosis is rapidly growing and so searching for novel therapeutics. Yet, there is no drug on the market available to modulate osteoclasts and osteoblasts activity simultaneously. Thus in presented research we decided to fabricate nanocomposite able to: (i) enhance osteogenic differentiation of osteoblast, (i) reduce osteoclasts activity and (iii) reduce pro-inflammatory microenvironment. As a consequence we expect that fabricated material will be able to inhibit bone loss during osteoporosis. RESULTS: The α-Fe2O3/γ-Fe2O3 nanocomposite (IOs) was prepared using the modified sol-gel method. The structural properties, size, morphology and Zeta-potential of the particles were studied by means of XRPD (X-ray powder diffraction), SEM (Scanning Electron Microscopy), PALS and DLS techniques. The identification of both phases was checked by the use of Raman spectroscopy and Mössbauer measurement. Moreover, the magnetic properties of the obtained IOs nanoparticles were determined. Then biological properties of material were investigated with osteoblast (MC3T3), osteoclasts (4B12) and macrophages (RAW 264.7) in the presence or absence of magnetic field, using confocal microscope, RT-qPCR, western blot and cell analyser. Here we have found that fabricated IOs: (i) do not elicit immune response; (ii) reduce inflammation; (iii) enhance osteogenic differentiation of osteoblasts; (iv) modulates integrin expression and (v) triggers apoptosis of osteoclasts. CONCLUSION: Fabricated by our group α-Fe2O3/γ-Fe2O3 nanocomposite may become an justified and effective therapeutic intervention during osteoporosis treatment.

57Fe Mössbauer and magnetic studies of Th7Co2.5 57Fe0.5 and Th7Ni2.5 57Fe0.5 superconductors.

The noncentrosymmetric Th7Co2.5 57Fe0.5 and Th7Ni2.5 57Fe0.5 superconductors were studied by means of 57Fe transmission Mössbauer spectroscopy (TMS), ac-magnetic susceptibility and magnetization measurements. The low-temperature data showed that both compounds are type-II superconductors with transition temperature close to [Formula: see text] K. The collected Mössbauer spectra of the studied samples consist of one well-resolved doublet over the temperature range measured. Neither abnormal behaviour of the hyperfine parameters at or near [Formula: see text] nor phonon softening were found. A comparison of 57Fe Mössbauer data of Ni- and Co-based superconductors with those of Th7Fe3 indicated that with decreasing 3d-electron numbers across the series Th7Ni2.5 57Fe0.5 [Formula: see text] Th7Co2.5 57Fe0.5 [Formula: see text] Th7Fe3, the s-electron density around the Fe nucleus and as well as the electric field gradient strength increases. The latter finding is associated with increasing asymmetricity of 3d-electron distribution and this fact presumably gives arise to an exotic superconductivity in the Co- and Fe-based compounds.

Superconducting-state properties and electronic band structure calculations of a noncentrosymmetric Th7Ni3 compound.

Superconducting-state properties of a noncentrosymmetric Th7Ni3 compound have been investigated using magnetic, electrical resistivity and specific heat measurements as well as by electronic band structure calculations. The study reveals that the studied compound is a dirty type-II superconductor with [Formula: see text] K and a weak electron-phonon coupling [Formula: see text]. Moreover, in contrast to an exotic superconductivity observed previously in Th7Fe3 and Th7Co3, data reported in this paper give clear evidence that Th7Ni3 is a conventional single-gap superconductor. The experimental results are supported by DFT calculations of the electronic band structure, density of states, electron localization functions and Fermi surfaces which were performed using the full-potential linear muffin-tin-orbital and full-potential linearized augmented plane wave methods. Theoretical data show that asymmetric spin-orbit coupling in Th7Ni3 is quite small; hence the electronic band structure of this compound is weakly affected by the spin-orbit effects. We have determined fundamental parameters of Th7Ni3 and compared the superconducting properties with other Th7T3 (T = Fe, Co and Ru) compounds.