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.

Arrangement at the nanoscale: Effect on magnetic particle hyperthermia.

In this work, we present the arrangement of Fe3O4 magnetic nanoparticles into 3D linear chains and its effect on magnetic particle hyperthermia efficiency. The alignment has been performed under a 40 mT magnetic field in an agarose gel matrix. Two different sizes of magnetite nanoparticles, 10 and 40 nm, have been examined, exhibiting room temperature superparamagnetic and ferromagnetic behavior, in terms of DC magnetic field, respectively. The chain formation is experimentally visualized by scanning electron microscopy images. A molecular Dynamics anisotropic diffusion model that outlines the role of intrinsic particle properties and inter-particle distances on dipolar interactions has been used to simulate the chain formation process. The anisotropic character of the aligned samples is also reflected to ferromagnetic resonance and static magnetometry measurements. Compared to the non-aligned samples, magnetically aligned ones present enhanced heating efficiency increasing specific loss power value by a factor of two. Dipolar interactions are responsible for the chain formation of controllable density and thickness inducing shape anisotropy, which in turn enhances magnetic particle hyperthermia efficiency.

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 TC ≫ 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 Co(3+) to Co(2+) at the CoO/Co3O4 interface, with Co(2+) 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.

Risk index score for bacteremia in febrile neutropenic episodes in children with malignancies.

PURPOSE: To prospectively determine risk factors for bacteremia in febrile neutropenic children with malignancies. PATIENTS AND METHODS: We studied 199 episodes of febrile neutropenia in 80 children with malignancies, treated by conventional chemotherapy for a 4-year period (2000 - 2004). A standardized computer database with a set of variables for each febrile neutropenic episode was used. C-reactive protein (CRP) was measured at the first febrile episode and on the 3rd and 5th day from the beginning of antibiotic therapy by immunoturbidimetric method. Blood cultures were taken at the onset of fever and before initiation of antibiotic therapy. RESULTS: Multivariate logistic regression analysis determined 5 variables as independent risk factors for bacteremia: the underlying malignant disease (leukemia, non - Hodgkin's lymphoma / NHL, stage IV), chills, perianal cellulitis, presence of central venous catheter and CRP rise >or=34.5 mg/L between the onset of fever and the 3rd day of empiric antibiotic therapy. Thus we identified a low-risk group for bacteremia of 19.1%. CONCLUSION: Serial measurement of CRP allows for definite risk stratification of febrile neutropenic episodes on the 3rd day from the onset of fever. The low-risk group could be eligible for sequential empiric antibiotic therapy.

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.

Acute hemolytic anemia as an initial clinical manifestation of Wilson's disease.

Wilson's disease is an inherited disorder of copper transport in the organism, transmitted in autosomal recessive fashion. It is caused by dysfunction in homologous copper-transporting adenosine triphosphatases. The main clinical symptoms are usually due to hepatic (42%) or/and neurologic (34%) involvement, which is the reason for the name hepatolenticular degeneration. Described in this report are four cases--the first three demonstrate an unusual form of manifestation of Wilson's disease in clinical practice--glucose-6-phosphate dehydrogenase deficiency hemolytic anemia. The fourth case concerns acute intravascular hemolysis that was provoked by the disease and presented without erythrocyte enzyme disturbances. Hemolytic anemia is a recognized but rare (10-15%) complication of the disease. Most often Coombs' negative acute intravascular hemolysis occurs as a consequence of oxidative damage to the erythrocytes by the higher copper concentration. A literature review with discussion of the possible mechanisms for the development of this phenomenon is done.

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.