Together with impaired production of erythropoietin and iron deficiency, the decreased lifespan of red blood cells (RBCs) is a main factor contributing to the chronic anaemia observed in haemodialysis (HD) patients. Atomic force microscopy is employed in this work to thoroughly survey the membrane of intact RBCs (iRBCs) of HD patients in comparison to those of healthy donors, aiming to obtain direct information on the structural status of RBCs that can be related to their decreased lifespan. We observed that the iRBC membrane of the HD patients is overpopulated with extended circular defects, termed 'orifices', that have typical dimension ranging between 0.2 and 1.0 mu m. The 'orifice' index-that is, the mean population of 'orifices' per top membrane surface-exhibits a pronounced relative increase of order 54 +/- 12% for the HD patients as compared to healthy donors. Interestingly, for the HD patients, the 'orifice' index, which relates to the structural status of the RBC membrane, correlates strongly with urea concentration, which is a basic index of the uraemic milieu. Thus, these results indicate that the uraemic milieu downgrades the structural status of the RBC membrane, possibly triggering biochemical processes that result in their premature elimination from the circulation. This process could decrease the lifespan of RBCs, as observed in HD patients.

Dual-modality contrast agents, such as radiolabeled nanoparticles, are promising candidates for a number of diagnostic applications, since they combine the advantages of two different imaging modalities, namely SPECT or PET imaging with MR imaging. The benefit of such a combination is to more accurately interpret disease and abnormalities in vivo, by exploiting the advantages of each imaging technique, i.e. high sensitivity for SPECT/PET, high resolution anatomical information for MRI. In this review article, we provide an overview of recent findings in the synthesis, evaluation and application of radiolabeled iron oxide nanoparticles as dual-modality SPECT/MRI and PET/MRI imaging probes.

Core/shell particles were synthesized by assembling oppositely charged ferrite (Fe3O4 or NiFe2O4) nanoparticles on the surface of monodispersed silica core particles (having size similar to 0.4 mu m) prepared by hydrolysis and condensation of tetraethylortosilicate. Optimal conditions for synthesis of silica core/nano-Fe3O4 shell particles were found at pH similar to 5.4. The obtained particles have superparamagnetic behavior above a blocking temperature of approximate to 25 K, which make them very attractive for a broad range of biomedical and bioengineering applications. Incorporation of nickel into ferrite structure could not be achieved at lower pH value, so functionalization of core particles was required. Incorporation of nickel into ferrite structure was successful at pH above 7, however at higher pH the formation rate of nickel-ferrite particles becomes very fast and the self-aggregation dominates the competing formation of the nickel-ferrite shell. Because of that the self-aggregation was prevented by surface modification of nickel-ferrite nanoparticles with citric acid before their deposition on the functionalized silica core and homogenous and continuous NiFe2O4 shell was finally obtained. (C) 2012 Elsevier Ltd. All rights reserved.

We have studied the phase diagram of a Ba-1 xKxFe2As2 (T-c = 36.9 K) single crystal superconductor by employing ac-susceptibility measurements, both as a function of temperature for constant external magnetic field and of magnetic dc-field for constant temperature for angles Theta = (sic)(H, c-axis) = 0 degrees, 30 degrees, 45 degrees, 60 degrees, 75 degrees and 90 degrees, between the c-axis and the magnetic field. The irreversibility lines (H-irr(T, H)) are estimated from the onset of non-zero values of the amplitude of the third harmonic susceptibility. H-irr-lines for all the studied angles can be reproduced from the equation H-irr = H-0(Theta)(1 - T/T-c)(n), with n approximate to 4/3. From the angular dependence of H-0(Theta) parameter we estimated the anisotropy of the irreversibility lines. In the temperature interval [35, T-c] the anisotropy parameter was estimated gamma = H-irr(ab)/H-irr(c) = 2.2 +/- 0.1. The measurements of the real part of the fundamental (first harmonic) ac-susceptibility chi'(T) for constant temperature as a function of dc-magnetic field revealed, for high values of the ac-field amplitude, a second peak in the critical current. The second peak line is located far from H-irr-line and exists up to T-c. Although the particular sample has high critical densities, contrary to the predictions of the Bean's model, the maximum of the imaginary part of the fundamental ac-susceptibility chi '' exhibits lower values. This behavior could be explained by assuming a reversible motion of the flux lines around the pinning centers for low values of the ac-magnetic field amplitude. (C) 2012 Elsevier B. V. All rights reserved.

The structural and magnetic properties and spin dynamics of dextran coated and uncoated gamma-Fe2O3 (maghemite) nanoparticles have been investigated using high resolution transmission electron microscopy (HRTEM), Fe-57 nuclear magnetic resonance (NMR), Mossbauer spectroscopy and dc magnetization measurements. The HRTEM observations indicated a well-crystallized system of ellipsoid-shaped nanoparticles, with an average size of 10 nm. The combined Mossbauer and magnetic study suggested the existence of significant interparticle interactions not only in the uncoated but also in the dextran coated nanoparticle assemblies. The zero-field NMR spectra of the nanoparticles at low temperatures are very similar to those of the bulk material, indicating the same hyperfine field values at saturation in accord with the performed Mossbauer measurements. The T-2 NMR spin-spin relaxation time of the nanoparticles has also been measured as a function of temperature and found to be two orders of magnitude shorter than that of the bulk material. It is shown that the thermal fluctuations in the longitudinal magnetization of the nanoparticles in the low temperature limit may account for the shortening and the temperature dependence of the T-2 relaxation time. Thus, the low temperature NMR results are in accord with the mechanism of collective magnetic excitations, due to the precession of the magnetization around the easy direction of the magnetization at an energy minimum, a mechanism originally proposed to interpret Mossbauer experiments in magnetic nanoparticles. The effect of the surface spins on the NMR relaxation mechanisms is also discussed.

In this study the authors introduce the utilisation of ferrimagnetic compounds into an antenna design and investigate the capability of controlling the antenna properties by means of an external magnetic field. After intensive study of the material properties, the ferrimagnetic compound yttrium iron garnet (YIG) was found to be the best candidate for the proposed novel antenna design. The authors provide a patch antenna design with a part of the dielectric substrate replaced by YIG compound. They have investigated the influence of this compound on the antenna's polarisation properties under the application of an external magnetic field. The authors clearly demonstrate that the type and the sense of the antenna polarisation are strongly influenced by the YIG substrate, because they change with respect to the direction and the magnitude of the external magnetic field. Moreover, the authors have proved that the presence of this material induces non-reciprocal properties in the antenna's operation, changing the antenna properties with respect to receiving or transmitting mode.

High-resolution electron backscatter diffraction (EBSD) technique and DC magnetization were used to characterize a Cu-Nb reinforced bronze route Nb3Sn superconducting multifilamentary wire. The results of DC-magnetization show an extended regime of magnetic reversibility in the operational magnetic field-temperature phase diagram. This observation is discussed in terms of microstructure characteristics of the A15 phase such as grain size, grain boundary misorientation angle distribution, tin gradient across the filaments and residual strain, in connection to the literature. (C) 2012 Published by Elsevier B.V. Selection and/or peer-review under responsibility of the Guest Editors.