CoPt and FePt compound films with L1(0) ordered structure have been intensively studied,due to their extremely high uniaxial magnetocrystalline anisotropy which makes them suitable for application in ultra high density magnetic recording media. A basic requirement in these type of media is the development of strong perpendicular magnetic anisotropy. The role of Ag underlayers in promoting strong (001) crystallographic texture and perpendicular magnetic anisotropy in post-annealed Ag/CoPt and Ag/FePt bilayers (BLs) has already been reported, along with a possible correlation between L1(0) formation and development of (001) crystallographic texture. In this work we present new data, which provide further evidence that there is indeed such a correlation during the annealing process of Ag/CoPt BLs. The most obvious manifestation of this correlation is the fact that the X-ray intensity ratios I-001/I-002 (used as a measure of the degree of L1(0)-ordering) and I-002/I-111 (used as a measure of the crystallographic texture) and the coercivity H-c and relative remnant magnetization m(r) (for field H normal to the surface of the films) exhibit the same kind of dependence from the thickness of the Ag underlayer. Comparison with respective crystallographic data from post-annealed Ag/CoPt nanocomposites (NCs) shows that in the case of NCs the (001) texture starts to degrade for lower total film thickness, compared to the case of BLs. This difference can be attributed to the structural incoherence in the growth of the CoPt grains imposed by the presence of Ag inside the Ag/CoPt NCs, while in BLs Ag is only used as an underlayer. Based on the above data and on detailed Heavy Ion Elastic Rutherford Back Scattering (HIRBS) measurements, performed on post-annealed Ag/CoPt NCs, we propose a possible mechanism for the interpretation of the observed correlation. The proposed mechanism is based on the reduction of total strain (residual strain of as-deposited film and transformation strain due to deformation of the unit cell as L1(0)-CoPt is formed) throughout the annealing process.

Background/Aims: Cell membranes facilitate the transport of water, ions, and necessary nutrients by hosting a great variety of transport channels that have either a 'simple' pore-like structure or more complex architecture that is based on the utilization of specific receptors. The present study reveals the impact of AgNO3, a well-known inhibitor of water channel activity, on transport channels that emerge at the membrane of intact red blood cells (iRBCs). Methods: Atomic force microscopy is employed to survey the morphological modification of all transport channels by directly comparing the respective images obtained on the exact same iRBCs prior to and after spraying the AgNO3 solution. Results: Small pores of mean size 50 nm that were assigned to water channels, and extended orifices of mean size 300 nm that exhibit a neck-like extracellular segment were observed at the iRBC membrane. Conclusion: Our results reveal that AgNO3 exerts noticeable influence on all transport channels so that its selective water channel inhibitory action should be reconsidered. For low AgNO3 concentrations extended recovery of the small pore network was observed upon waiting, giving strong evidence that iRBCs have a recovery potential upon simply removing the inhibition cause without the need for specific reducing agents. Copyright (C) 2009 S. Karger AG, Basel

In this paper we introduce the utilization of novel compounds that can be magnetoelectric, namely Al(2-x)FexO(3) and Ga2-xFexO3, or ferrimagnetic, namely Y3Fe5O12, as effective constituents in patch antennas. Owing to their coupled dielectric and magnetic properties these constituents can probably tune the radiation characteristics of the patch antenna by means of an externally controlled parameter such as a magnetic and/or electric field. We clearly demonstrate that using Y3Fe5O12 in the antenna substrate, the type and the sense of the antenna polarization is strongly influenced by applying an external magnetic field.

In this paper we introduce the incorporation of magneto-electric materials into antenna design and the potential of controlling the behavior of the antenna by means of an external magnetic field. After an intensive study of magneto-electric material properties, a ferrimagnetic compound called Yttrium Iron Garnet (YIG) was found to be the best candidate for the novel antenna design. We provide a metamaterial patch antenna design where a part of the substrate is replaced by the YIG compound. After several design modifications the final model includes a circular-shaped YIG substrate just under the metallic patch and offers sufficient performance in terms of resonance, bandwidth and radiation efficiency. Additionally, in the presence of an external magnetic field the polarization becomes elliptical and the sense of the polarization (left or right) can be controlled through the direction of the magnetic field. That latter characteristic confirms the metamaterial-nature of the antenna.

A commercially available powder of MgB2 is used as starting material for the examination of the influence of the annealing temperature on the properties of this intermediate-T-c superconductor. We performed scanning electron microscopy (SEM) and Hall ac-susceptibility measurements as a function of temperature and ac-field amplitude on samples annealed at 650, 750, 850 and 950 degrees C. The imaginary part of ac-susceptibility measurements is used to calculate both the inter-granular critical current density, J(c)(T-p) and density of pinning force, alpha(j)(0). It was observed that all T-c, J(c)(T-p) and alpha(j)(0) exhibit a non-monotonic behavior on the annealing temperature range studied in this work. T-c is measured to be 39.85 +/- 0.02 K and J(c)(T-p) is estimated to be as high as 60 A/cm(2) at 39.2 K for the sample annealed at 850 degrees C. The peak temperature, T-p, in the imaginary part of the ac-susceptibility curves shifts to lower temperatures with both decreasing the annealing temperature and increasing the amplitude of the ac-magnetic fields. A comparison of the experimental ac-susceptibility data with theoretical critical-state models that are currently available is performed. SEM investigations showed that the grain size increases, and the grain connectivity improves when the annealing temperature increases up to 850 degrees C. The possible reasons for the observed changes in transport, microstructure and magnetic properties due to annealing temperature are discussed. (C) 2009 Elsevier B.V. All rights reserved.

By means of magnetic measurements we have studied the magnetic properties of the NdFeAsO0.82F0.18 superconductor. We estimated the upper critical field H-c2(ab) (T) from the temperature at which the inverse magnetization deviates from linear behavior. Low field magnetic measurements revealed that a external magnetic induction of B = 0.01 T destroys the superconducting path between grains (weak-link behavior). Nd ions behave as isolated paramagnetic centers. This is evident since for magnetic inductions larger than 0.5 T a paramagnetic moment arises from the Nd that overcomes the superconducting diamagnetic signal. Hysteresis loops at several temperatures revealed that the critical current falls rapidly with temperature. The temperature variation of the reversible magnetization shows a behavior that is reminiscent of high-T-c cuprates, indicating the important role of thermal fluctuations.

Iron oxide Ferromagnetic Nanoparticles (FNs) such as magnetite (Fe3O4) and maghemite (gamma-Fe2O3) are currently employed in biomedical applications owing to their relatively high biocompatibility. Recently, we have introduced a novel application of Fe3O4 FNs in the so-called Magnetically Assisted Haemodialysis (MAHD), a promising concept that can be employed for the treatment of End-Stage Renal Disease. The key characteristic of MAHD is the selective removal of toxins that cannot be removed by current low-and high-flux dialysers that are extendedly used during conventional Haemodialysis (HD). In addition, MAHD could enable the more efficient removal of all toxins when compared to conventional HD so that the duration of dialysis session could be decreased. This is an important benefit that could significantly improve the quality of life of patient. The present work focuses on the in vitro evaluation of the biocompatibility of both bare Fe3O4 FNs and Fe3O4-Bovine Serum Albumin Conjugates (Fe3O4-BSA Cs) with blood cells, namely Red Blood Cells (RBCs), White Blood Cells (WBCs) and Platelets (Plts). Their solubility in whole human blood medium is also carefully evaluated. Both issues are fundamental for the MAHD application since the latter is based on the intravenous injection of FN Cs into the bloodstream of the patient. Atomic force microscopy and optical microscopy were employed for the investigation of both surface characteristics and overall morphology of blood cells, respectively. Samples of donated blood, where bare Fe3O4 FNs or Fe3O4-BSA Cs were added, were maturated under mild incubation for durations up to 120 min. We investigated two representative temperatures, T=20 degrees C owing to easy experimental realization, and T=37 degrees C trying to simulate human body conditions. We did not observe noticeable interference of either bare Fe3O4 FNs or Fe3O4-BSA Cs with RBCs, WBCs and Plts. More importantly we did not observe any degradation of the surface of RBCs and WBCs that were maturated under the presence of bare FNs or Cs in concentrations that strongly exceed the ones used for the treatment of iron-deficiency anaemia. Incidents where either bare FNs or Cs were bound onto the surface of RBCs or internalised by WBCs were very rare. Our observations suggest high biocompatibility of both bare Fe3O4 FNs and Fe3O4-BSA Cs with blood cells, while the solubility depends on the BSA content of the Fe3O4-BSA Cs.

Dialysis-related amyloidosis is related to the inefficient removal of beta(2)-microglobulin (beta(2)-m) that is mainly responsible for the formation of amyloid fibrils deposited on the joints and in the heart, blood vessels and digestive system. Magnetically assisted hemodialysis (MAHD) can be used for the prevention of dialysis-related amyloidosis. MAHD is based on ferromagnetic nanoparticle-targeted binding substance conjugates (FN-TBS Cs) that should be administered to the patient before the dialysis session. The TBS should have a high affinity for beta(2)-m so that the conjugates bind with the beta(2)-m in the bloodstream. The complex FN-TBS-beta(2)-m will be selectively removed during dialysis by means of a "magnetic dialyzer" that is installed at the dialysis machine in series to the conventional dialyzer. We have examined the in vitro applicability of MAHD by employing biocompatible Fe3O4 and bovine serum albumin (BSA) as constituents of the FN-TBS Cs. We evaluated the binding capacity of both bare Fe3O4 FNs and Fe3O4-BSA Cs for beta(2)-m concentrations ranging from mild to severe conditions. Finally, we conducted mock-dialysis experiments for the evaluation of several technical issues related to MAHD. beta(2)-m is adsorbed onto the Fe3O4-BSA Cs not only almost instantly, but also very efficiently. The employed Cs do not chemically interact with the materials used in standard dialyzers, as agglomerates were not observed in the capillaries of the conventional dialyzers. MAHD may become an efficient modality for the prevention of dialysis-related amyloidosis because beta(2)-m concentrations ranging from mild to severe conditions can be adequately handled.