Doubling of the magnetic energy product in ferromagnetic nanowires at ambient temperature by capping their tips with an antiferromagnet

We present an approach to prepare free-standing tips of micrometer-long nanowires electrodeposited in anodic aluminum oxide nanopores. Such open tips can be further processed, e.g. for vertical interconnects of functional layers or for tailoring the magnetization reversal of ferromagnetic nanowires. The magnetic switching of nanowires is usually initiated by vortex or domain formation at the nanowire tips. We show that coating the tips of Fe₃₀Co₇₀ nanowires (diameter 40 nm, length 16 μm) with thin antiferromagnetic Fe₅₀Mn₅₀ capping layers (thickness ≈10 nm) leads to magnetic hardening with a more than doubled energy product at ambient temperature.

Perspectives On: Criteria for Complex Evaluation of the Morphology and Alignment of Electrospun Polymer Nanofibers

Electrospinning is a promising method for producing polymer materials composed of micro- and nanosized fibers. This method allows the preparation of random and aligned fibers of different morphologies, such as cylindrical or ribbon-shapes, defect-free or with defects, and with or without pores or porous. The increasing number of studies on electrospinning requires a set of criteria for more complex evaluation of the fiber morphology and the topology of these polymer materials to be established. The main characteristics necessary for a complex evaluation of the morphology of electrospun micro- and nanofibers have been systematized in this paper. Examples of characterization of the morphology and of the alignment of various micro- and nanofibers are given.

Preparation of PLLA/PEG Nanofibers by Electrospinning and Potential Applications

Poly(L-lactide) (PLLA)/polyethylene glycol (PEG) mixed solutions were successfully electrospun into micro-or nanofibrous polymer mats. The fiber diameter was in the range 100nm-6μm. The effect of the concentration of the spinning solutions and the ratio of PLLA/PEG on the fiber diameter and morphology was investigated. The hydrophilicity was tuned by varying the PLLA/PEG ratio. The tissue compatibility of the electrospun nanofibrous scaffolds was screened using two different cell models of human dermal fibroblasts and the osteoblast-like cell line MG-63. Both types of cells attached uniformly and approximately equally to all PLLA/PEG nanofibers. In long-term cultures osteoblast-like cells tend to spatially organize in tissue-like structure, particularly within the scaffold with the highest PEG content (PLLA/PEG at weight ratio 70/30). These results indicate that PLLA mixed with hydrophilic PEG produces a promising new biocompatible material for engineering scaffolds.

A versatile large-scale and green process for synthesizing magnetic nanoparticles with tunable magnetic hyperthermia features

Production of functionalized nanoparticles for magnetic hyperthermia by an industrial-scale process.

Optimum nanoscale design in ferrite based nanoparticles for magnetic particle hyperthermia

The study demonstrates the multiplex enhancement of the magnetic hyperthermia response by nanoscale design and magnetism tuning without sparing the biocompatibility of iron-oxide.

Electrostatic doping as a source for robust ferromagnetism at the interface between antiferromagnetic cobalt oxides

Polar oxide interfaces are an important focus of research due to their novel functionality which is not available in the bulk constituents. So far, research has focused mainly on heterointerfaces derived from the perovskite structure. It is important to extend our understanding of electronic reconstruction phenomena to a broader class of materials and structure types. Here we report from high-resolution transmission electron microscopy and quantitative magnetometry a robust – above room temperature (Curie temperature T_C ≫ 300 K) – environmentally stable- ferromagnetically coupled interface layer between the antiferromagnetic rocksalt CoO core and a 2–4 nm thick antiferromagnetic spinel Co₃O₄ surface layer in octahedron-shaped nanocrystals. Density functional theory calculations with an on-site Coulomb repulsion parameter identify the origin of the experimentally observed ferromagnetic phase as a charge transfer process (partial reduction) of Co³⁺ to Co²⁺ at the CoO/Co₃O₄ interface, with Co²⁺ being in the low spin state, unlike the high spin state of its counterpart in CoO. This finding may serve as a guideline for designing new functional nanomagnets based on oxidation resistant antiferromagnetic transition metal oxides.

Multiple myeloma in association with second malignancy

PURPOSE

To look at the frequency of second primary malignancies (SECMAL) in patients with multiple myeloma (MM).

METHODS

The medical files of 332 patients with MM (whole group), diagnosed and treated at the University Multiprofile Hospital for Active Treatment "Sv. Georgi" and the Comprehensive Oncology Hospital (Plovdiv) for a 20-year period (1990-2010) were retrospectively analyzed. MM patients with SECMAL constituted the study group. A control group comprised patients with solid tumors associated with SECMAL. This group derived from a sample of 21768 patients with solid tumors.

RESULTS

In the study group, SECMAL was diagnosed in 4.52% (N=15) of the patients, while in the control group this figure was 5.09% (N=1108) (p>0.05). The diagnosis of MM preceded the occurrence of SECMAL in 35.71% of the study group patients, the median interval being 6.6 years (range 5-14). More frequently the diagnosis of the solid tumor preceded the occurrence of MM (66.67%). Breast cancer and gastric cancer were encountered with the highest frequency (26.67% each). The median survival (77.2 months, range 44-129) was significantly longer in the group with MM and SECMAL compared to the whole group with MM (median 38.6 months, range 10-58; p<0.05).

CONCLUSION

The rate of MM with other malignant diseases is comparable with the frequency of SECMAL in other lymphoproliferative disorders and solid tumors. The occurrence of SECMAL during the clinical course of MM is not a frequent event and is expected in the rare cases with longer survival.

In vitro differentiation of the immortalized mesencephalic progenitor cell line CSM14.1 occurs independently from haematopoietic cytokines

In vitro expanded neural precursor cells could provide a renewable source of dopaminergic (DAergic) neurons for cell replacement therapy. In the present study immortalized cell line CSM14.1 was investigated in vitro. Cells were derived from the ventral mesencephalic area of a 14-day-old rat embryo and immortalized retrovirally with the temperature-sensitive mutant of the SV40 Large T-antigen. We investigate the proliferation and differentiation of these cells under various culture conditions, at different temperatures and serum conditions. For differentiation were propagated cells at 39 degrees C in medium supplemented with 1% FCS with or without cytokines. At chosen time points cells were investigated for the expression of different markers by western blot and immunocytochemistry. As controls cells cultured at 33 degrees C with 10% FCS for 3 days were used. We have shown that serum reduction alone is not sufficient for CSM14.1-cells to stop proliferating and begin differentiation. Following serum reduction and elevation of the temperature cells changed their morphology began to express specific band of the neuronal marker NeuN. Following cytokines treatment the mean length of cellular processes increased from 319 to 385 microm per cell, whereas the expression of neuronal markers such as NeuN and TH was not markedly changed. In conclusion, the differentiation cocktail consisting of interleukin 1(Il-1), Il-11, leukaemia inhibitory factor (LIF) and GDNF, does influence the outgrowth of neuritis but does not change the expression of mature neuronal markers at the protein level in CSM14.1 cells.

Inhomogeneous alloying in FePt nanoparticles as a reason for reduced magnetic moments

The reduced magnetic moments of oxide-free FePt nanoparticles are discussed in terms of lattice expansion and local deviation from the averaged composition. By analyses of the extended x-ray absorption fine structure of FePt nanoparticles and bulk material measured both at the Fe K and Pt L(3) absorption edge, the composition within the single nanoparticles is found to be inhomogeneous, i.e. Pt is in a Pt-rich environment and, consequently, Fe is in an Fe-rich environment. The standard Fourier transformation-based analysis is complemented by a wavelet transformation method clearly visualizing the difference in the local composition. The dependence of the magnetic properties, i.e. the element-specific magnetic moments on the composition in chemically disordered Fe(x)Pt(1-x) alloys, is studied by fully relativistic SPR-KKR band structure calculations supported by experimental results determined from the x-ray magnetic circular dichroism of 50 nm thick films and bulk material.

Enhanced orbital magnetism in Fe(50)Pt(50) nanoparticles

X-ray absorption and magnetic circular dichroism spectra at both the Fe and Pt L(3,2) edges were measured on wet-chemically synthesized monodisperse Fe(50)Pt(50) particles with a mean diameter of 6.3 nm before and after complete removal of the organic ligands and the oxide shell covering the particles by soft hydrogen plasma resulting in a pure metallic state. After thermal treatment of the metallic particles, the coercive field increased by a factor of 6, the orbital magnetic moment at the Fe site increased by 330% and is reduced at the Pt site by 30%, while the effective spin moments did not change. A decrease of the frequency of oscillations in the extended x-ray absorption fine structure at the Pt L(3,2) edges provides evidence for crystallographic changes towards the L1(0) phase.

Thalassemia intermedia in an infant

We present a case of a two year old infant with jaundice in the neonatal period, anemia and splenohepatomegaly. Hemoglobin electrophoresis of the child and siblings revealed double heterozygosity of Lepore/beta thalassemia in the child and father, and heterozygous beta-thalassemia in the uncle. Structural variants giving rise to thalassemia phenotype are discussed.