RESUMO

The replacement of bedding in compost dairy barns (CB) comprises a recurrent management practice, but bedding materials are often not readily available in all regions and the choice of alternative materials is necessary. The objective was to evaluate the thermal attributes of carnauba straw (CS) bedding in compost dairy barn facilities. Environmental monitoring operations were performed at a commercial farm located in Northeast Brazil. Mini weather stations were used to evaluate environmental variables. The THI was evaluated as one of the comfort parameters. Analysis of the spatial distribution of bed surface temperature (BST) in the CB was performed using geostatistical techniques. The cows remained out of the comfort zone according to THI results. The BST indicated satisfactory performance and from the thermal point of view can be used as alternative bedding material in CB facilities. However, it was observed that the CS showed fast biomass degradation compared to conventional materials, widely known. In addition, inadequate temperature values (< 45°C) were found in the deeper of the CS bed, signaling higher risks of pathogenic microbial activity. Additional studies are needed for searching the proper management plans that increase the life span of the bed formed by carnauba straw.(AU)

A reposição de cama na instalação Compost Barn (CB) compreende uma prática recorrente de manejo, porém os materiais de cama muitas vezes não estão facilmente disponíveis em todas as regiões, sendo necessária a adoção de materiais alternativos. Objetivou-se avaliar os atributos térmicos da cama à base de bagana de carnaúba (BC) para instalações CB. Foram realizadas operações de monitoramento ambiental em uma fazenda comercial situada no nordeste do Brasil. Miniestações meteorológicas foram utilizadas para avaliação de variáveis ambientais. O ITU foi avaliado como um dos parâmetros de conforto. A distribuição espacial da temperatura superficial da cama (TSC) no galpão foi analisada usando técnicas da geoestatística. As vacas mantiveram-se fora da zona de conforto, conforme resultados do ITU. A TSC indicou desempenho satisfatório e, do ponto de vista térmico, pode ser utilizada como material alternativo para cama em instalações CB. Entretanto, observou-se que a BC apresentou rápida degradação da biomassa em comparação a materiais convencionais, amplamente conhecidos. Além disso, valores inadequados de temperatura (< 45°C) foram encontrados nas camadas profundas da cama de BC, sinalizando maiores riscos de atividade microbiana patogênica. Estudos adicionais tornam-se necessários para a busca de planos de manejo que aumentem o tempo de vida útil da cama formada por bagana de carnaúba.(AU)

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RESUMO

We investigate the influence of the magnon-phonon relaxation processes in the magnon transport under thermal gradient in the ferrimagnetic insulator yttrium iron garnet (YIG). Based on the Boltzmann equation we calculate the magnon contribution in the thermal conductivity in YIG and the longitudinal spin Seebeck effect in YIG/Pt films, including the influence of the magnon relaxation to the lattice through a phenomenological damping parameter. Our results are in good agreement with reported experimental data showing that besides the magnon-magnon relaxation processes, the magnon-phonon relaxation plays an important role in the thermal properties in YIG films.

RESUMO

Many spintronics applications consist of ultrathin magnetic and nonmagnetic multilayers and require an in-depth understanding of interfacial magnetism and spin transport. Here, we study permalloy/copper/platinum multilayer systems. We find that magnetic damping, perpendicular anisotropy, and proximity magnetization exhibit correlated oscillations as a function of the copper thickness. We ascribe these observations to an oscillatory interlayer coupling between permalloy and platinum. Such interlayer coupling may have a significant impact on the performance of spintronics applications.

RESUMO

The quasi-two-dimensional deposition of ferromagnetic materials by electrochemical process under the influence of a magnetic field applied in the plane of the growth leads to a surprising symmetry breaking in the dendritic structures found. The reasons for these features are still not completely understood. The original dense circular envelope becomes rectangular, as well as the sparse figures have their shapes elongated. This paper reports the results of a diffusion-limited aggregation (DLA) -like simulation. The model proposed here, a modification of the original DLA model, can deal with ferromagnetic particles under the influence of an electric field and the dipolar interactions between particles, submitted to an applied magnetic field in the plane of growth of such structures. The results were produced varying the applied magnetic field and the magnetic moment of the particles and show that the balance between these interactions is an important mechanisms that can be responsible for the changes in shape of the aggregates observed in the experiments.

RESUMO

A high-resolution X-ray diffraction beamline at the Brazilian Synchrotron Light Laboratory (LNLS) has been commissioned for the study of crystalline magnetic materials. The beamline optics is based on a Rh-coated vertical-focusing X-ray mirror and a sagittal-focusing double-crystal monochromator. The primary instrument is a six-circle diffractometer equipped with energy and polarization analysers and a closed-cycle He cryostat. The beamline source is a bending magnet of the 1.37 GeV storage ring of the LNLS, delivering approximately 4 x 10(10) photons s(-1) at 8 keV at the sample position. Resonant and non-resonant scattering are the main techniques used to study charge, orbital and magnetic structures. Examples of magnetic scattering in Ho and NiO single crystals, as well as orbital ordering in manganites thin films, are presented.

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13C high-resolution solid-state nuclear magnetic resonance (NMR) was employed to study carbon materials prepared through the thermal decomposition of four different organic precursors (rice hulls, endocarp of babassu coconut, peat, and PVC). For heat treatment temperatures (HTTs) above about 600 C, all materials presented 13C NMR spectra composed of a unique resonance line associated with carbon atoms in aromatic planes. With increasing HTT a continuous broadening of this resonance and a diamagnetic shift in its central frequency were verified for all samples. The evolution of the magnitude and anisotropy of the magnetic susceptibility of the heat-treated carbon samples with HTT explains well these findings. It is shown that these results are better understood when a comparison is made with the features of the 13C NMR spectrum of polycrystalline graphite, for which the magnetic susceptibility effect is also present and is much more pronounced.

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The energy transport velocity v(E) and the diffusion constant D of electromagnetic waves in the presence of randomly distributed ferromagnetic scatterers are studied. v(E) presents a strong dependence on the relative magnetic permeability mu and, unlike the nonmagnetic case, exhibits sharp drops in the small-particle limit and never coincides with the phase velocity v(p). Both v(E) and D exhibit an oscillatory dependence on mu and vanish for certain values of mu. Since mu of ferromagnetic scatterers strongly depends on the temperature and applied magnetic field, we suggest that these facts can be explored in technological applications.

RESUMO

Ceftriaxone es una cefalosporina B-lactamasa resistente,de tercera generación y mucho uso en pediatría pr su amplio espectro de acción. El término pseudolitiasis biliar se debe a la naturaleza reversible de la anormalidad de la vesícula biliar cuando se suspende el ceftriaxone. Presentamos 3 pacientes pediátricos que recibieron ceftriaxone durante el posoperatorio, internados por cuadros clínicos de abdomen agudo y que desarrollaron pseudolitiasis biliar medicamentosa. La cefalosporinafue administrada por vía parental a 100mg/Kg/día, fraccionada en dos dosis a partir del primer día del posoperatorio en promedio durante 11,3 días, sólo un paciente tuvo un cambio del antibiótico por la sospecha precoz de una correlación entre la pseudolitiasis y el ceftriaxone. No hubo diferencia entre sexo, edad o duración de la terapéutica ni cuadro clínico sugestivo de patología biliar. Ningún paciente necesitó ser sometido a colecistectomía y desaparecieron los hallazgos ultrasonográficos al suspender el antibiótico. Las características de esta litiasis"iatrogénica" la transforma en una intidad clínica que necesita ser diagnosticada y evaluada precozmente para evitar intervenciones qurúrgicas innecesarias

Assuntos

RESUMO

Ceftriaxone es una cefalosporina B-lactamasa resistente,de tercera generación y mucho uso en pediatría pr su amplio espectro de acción. El término pseudolitiasis biliar se debe a la naturaleza reversible de la anormalidad de la vesícula biliar cuando se suspende el ceftriaxone. Presentamos 3 pacientes pediátricos que recibieron ceftriaxone durante el posoperatorio, internados por cuadros clínicos de abdomen agudo y que desarrollaron pseudolitiasis biliar medicamentosa. La cefalosporinafue administrada por vía parental a 100mg/Kg/día, fraccionada en dos dosis a partir del primer día del posoperatorio en promedio durante 11,3 días, sólo un paciente tuvo un cambio del antibiótico por la sospecha precoz de una correlación entre la pseudolitiasis y el ceftriaxone. No hubo diferencia entre sexo, edad o duración de la terapéutica ni cuadro clínico sugestivo de patología biliar. Ningún paciente necesitó ser sometido a colecistectomía y desaparecieron los hallazgos ultrasonográficos al suspender el antibiótico. Las características de esta litiasis"iatrogénica" la transforma en una intidad clínica que necesita ser diagnosticada y evaluada precozmente para evitar intervenciones qurúrgicas innecesarias

Assuntos