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In this investigation, the Fe-doped CuO system was prepared by freeze-drying an aqueous solution of copper and iron acetates, followed by a heat treatment. The synthesized samples, which were previously identified as monophasic and nanostructured, were then characterized by Mössbauer spectroscopy and magnetization techniques. These nanoparticles revealed a complex magnetic behavior, which can be attributed to the presence of two different magnetic regions: the particle core, characterized by antiferromagnetic fluctuations, and the particle shell, in which uncompensated spins are responsible for the superparamagnetic character and, eventually, the ferromagnetic interaction among the nanoparticles at low temperatures. The ferromagnetism observed for this system shows that antiferromagnetic oxide matrixes can be used for diluted magnetic semiconductor applications, if suitably doped. [ABSTRACT FROM AUTHOR]

In this investigation, we synthesized monophasic and nanostructured (Zn1-x-yFexCoy)O samples, with x + y = 0.05. These nanophases were characterized by X-ray diffraction, magnetization techniques, and Mössbauer spectroscopy. The analyzes revealed that doping ZnO with iron or cobalt induced a morphological change for the crystallites. The presence of cobalt in the matrix showed to enhance clustering of iron atoms and two different groups of ferric cations were identifyed diluted in the wurtzite matrix. (Zn1-x-yFexCoy)O has no magnetic order at RT but makes a transition from the paramagnetic to the spin-glass state with decreasing temperature, passing through three different magnetic regimes. The unit cell volume, remanence and coercive field of the (Zn1-x-yFexCoy)O solid system reached a maximum for co-doped samples. [ABSTRACT FROM AUTHOR]

We have investigated exchange-spring magnets made from powders prepared by high-energy milling Nd2Fe14B mixed with 10%wt. Fe, milled for 6 h in a planetary mill, varying the rotation velocity and the starting grain refinement of the soft phase. The samples were characterized by X-ray diffraction, magnetization techniques and 57Fe Mössbauer spectroscopy. The diffractometric and Mössbauer analyses revealed that the Nd2Fe14B compound was partially decomposed in the milling process, increasing the amount of free iron and reducing the grain size of both. Indicative for the Fe2B and Nd1-εFe4B4 phase separation was also found. The magnetization versus applied magnetic field curves showed that both the remanence and coercive field for the 500 rpm milled samples reached values higher than those earlier obtained for un-milled or similarly milled single Nd2Fe14B. However, milling with 600 rpm showed to be deleterious to the same magnetic parameters. It was also demonstrated that milling using iron with less refined grains is more effective to improve the magnetic properties of the composite system. [ABSTRACT FROM AUTHOR]

A young male developed hearing loss, vertigo, headache and facial palsy. Neurological examination did not show any abnormalities. Two years later, cervical lymphadenopathy, hepatosplenomegaly and atypical lymphocytes in peripheral blood revealed leukemia. At the same time, acquired ichthyosis was observed. Subsequently, neurological abnormalities revealed myelopathy associated with HTLV-1, due to vertical transmission.Um jovem do sexo masculino desenvolveu perda auditiva, vertigem, cefaléia e paralisia facial. Exame neurológico sem alterações. Dois anos mais tarde, linfadenopatia cervical, hepatoesplenomegalia e linfócitos atípicos no sangue periférico divulgado leucemia. Concomitante, observou-se ictiose adquirida e, posteriormente, anormalidades neurológicas revelaram mielopatia associada ao HTLV-1, transmitido verticalmente.