906 resultados para Electrical bias


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Objectives To evaluate the presence of fungi on contact electrodes and ultrasound transducers from physiotherapy clinics.Design Quantitative study conducted at the Laboratory of Microbiology and Immunology, Faculty of Health Sciences and Technology of Piaui - NOVAFAPI, Teresina, Brazil.Setting Sample collection was performed in 10 clinics ( 20 ultrasound transducers and 20 contact electrodes).Main outcome measures Swabs were soaked with saline solution, inoculated in culture and incubated for filamentous fungi and yeast growth.Results Fourteen taxons were identified: Acremomium hyalinulum (Sacc.), Aspergillus terreus, Candida albicans, Cladosporium cladosporioides, Cladosporium elatum, Cladosporium oxysporum, Cladosporium sphaerospermum, Cladosphialophora bantiana, Curvularia clavata, Curvularia senegalensis, Fusarium oxysporum, Penicillium decumbens, Scopulariopsis candida and Sporothrix schenckii. Aspergillus terreus, Cladosporium oxysporum, Sporothrix shenckii and Candida albicans were found most often on contact electrodes, and Penicillium decumbens and Cladosporium cladosporioides were found most often on ultrasound transducers.Conclusion Fungi were found on all of the contact electrodes and ultrasound transducers. Physiotherapy professionals need to improve the disinfection procedures for this equipment. (C) 2010 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Lead calcium titanate (Pb1-xCaxTiO3 or PCT) thin films have been thermally treated under different oxygen pressures, 10, 40 and 80 bar, by using the so-called chemical solution deposition method. The structural, morphological, dielectric and ferroelectric properties were characterized by x-ray diffraction, FT-infrared and Raman spectroscopy, atomic force microscopy and polarization-electric-field hysteresis loop measurements. By annealing at a controlled pressure of around 10 and 40 bar, well-crystallized PCT thin films were successfully prepared. For the sample submitted to 80 bar, the x-ray diffraction, Fourier transformed-infrared and Raman data indicated deviation from the tetragonal symmetry. The most interesting feature in the Raman spectra is the occurrence of intense vibrational modes at frequencies of around 747 and 820 cm(-1), whose presence depends strongly on the amount of the pyrochlore phase. In addition, the Raman spectrum indicates the presence of symmetry-breaking disorder, which would be expected for an amorphous (disorder) and mixed pyrochlore-perovskite phase. During the high-pressure annealing process, the crystallinity and the grain size of the annealed film decreased. This process effectively suppressed both the dielectric and ferroelectric behaviour. Ferroelectric hysteresis loop measurements performed on these PCT films exhibited a clear decrease in the remanent polarization with increasing oxygen pressure.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The paper describes a novel neural model to electrical load forecasting in transformers. The network acts as identifier of structural features to forecast process. So that output parameters can be estimated and generalized from an input parameter set. The model was trained and assessed through load data extracted from a Brazilian Electric Utility taking into account time, current, tension, active power in the three phases of the system. The results obtained in the simulations show that the developed technique can be used as an alternative tool to become more appropriate for planning of electric power systems.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Recent studies have demonstrated that sheath dynamics in plasma immersion ion implantation (PIII) is significantly affected by an external magnetic field, especially in the case when the magnetic field is parallel to the workpiece surface or intersects it at small angles. In this work we report the results from two-dimensional, particle-in-cell (PIC) computer simulations of magnetic field enhanced plasma immersion implantation system at different bias voltages. The simulations begin with initial low-density nitrogen plasma, which extends with uniform density through a grounded cylindrical chamber. Negative bias voltage is applied to a cylindrical target located on the axis of the vacuum chamber. An axial magnetic field is created by a solenoid installed inside the target holder. A set of simulations at a fixed magnetic field of 0.0025 T at the target surface is performed. Secondary electron emission from the target subjected to ion bombardment is also included. It is found that the plasma density around the cylindrical target increases because of intense background gas ionization by the electrons drifting in the crossed E x B fields. Suppression of the sheath expansion and increase of the implantation current density in front of the high-density plasma region are observed. The effect of target bias on the sheath dynamics and implantation current of the magnetic field enhanced PIII is discussed. (C) 2007 Elsevier B.V. All rights reserved.

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Plasmas generated in de discharges in aromatic compounds have been used for several years in polymerization processes. The chemical kinetics developed in such a plasma environment are extremely complicated. Therefore it is extremely important to set up optical and electrical diagnostics in order to establish the kinetics of the film growth, In this work we studied de plasmas generated ill low-pressure atmospheres of benzene for different values of gas pressure and power coupled to the discharge. The pressure range varied from 0.2 to 1.0 mbar for electric power running from 4 to 25 W, the main chemical species observed within the discharge were CH, H and C. It was observed that the CH relative concentration increases continuously with the power in the range investigated. The electron temperature varied from 0.5 to 2.0 eV with the increase of the power, for a fixed value of gas pressure. The relative dielectric constant of the plasma polymerized benzene was kept around 4.8 from 100 Hz to 10 kHz, presenting a resonance near 25 kHz. This electric behaviour of the film was the same fur different conditions of polymeric film deposition, (C) 1997 Elsevier B.V. S.A.

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Thin films of SrBi4Ti4O15 (SBTi), a prototype of the Bi-layered-ferroelectric oxide family, were obtained by a soft chemical method and crystallized in a domestic microwave oven. For comparison, films were also crystallized in a conventional method at 700 degrees C for 2 h. Structural and morphological characterization of the SBTi thin films were investigated by Xray diffraction (XRD) and atomic force microscopy (AFM), respectively. Using platinum coated silicon substrates, the ferroelectric properties of the films were determined. Remanent polarization P-r and a coercive field E-c values of 5.1 mu C/cm(2) and 135 kV/cm for the film thermally treated in the microwave oven and 5.4 mu C/cm(2) and 85 kv/cm for the film thermally treated in conventional furnace were found. The films thermally treated in the conventional furnace exhibited excellent fatigue-free characteristics up to 10(10) switching cycles indicating that SBTi thin films are a promising material for use in non-volatile memories. (C) 2007 Elsevier B.V. All rights reserved.