Joao M. B. Pereira

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Neste estudo, a cromatografia por exclusão de tamanho (SEC) com detecção online ultravioleta (UV), espectrometria de absorção atômica em forno de grafite (GF AAS) e a espectrometria de massa por tempo de voo com dessorção/ionização de matriz assistida por laser (MALDI-TOF-MS) foram usadas para estudar a associação de selênio com macromoléculas e compostos(More)
AIMS This study aimed to determine the association between the reduction in the number of Clostridium difficile infection (CDI) cases reported by the English National Health Service (NHS) hospitals and concurrent antimicrobial use. METHODS A retrospective ecological study for January 2005 to December 2008 was conducted using data from 26 of the 29 NHS(More)
In this paper we discuss the results obtained with an in-fiber Fabry-Perot interferometer (FPI) used in strain and magnetic field (or force) sensing. The intrinsic FPI was constructed by splicing a small section of a capillary optical fiber between two pieces of standard telecommunication fiber. The sensor was built by attaching the FPI to a(More)
The determination of Ba, Ca, Cu, Fe, Mg, Mn, P, Pb, and Zn by inductively coupled plasma optical emission spectrometry (ICP OES), and Se by graphite furnace atomic absorption spectrometry (GF AAS), has been carried out in dry matter and teas from 11 samples of the cat's claw plant. The accuracy and precision values were verified against GBW 07604 (Poplar(More)
A versatile Hall magnetometer has been developed, manufactured, calibrated, and turned operational for measurements of the magnetic properties of bulk materials and magnetic microand nanoparticles. The magnetometer was constructed from the combination of various equipments, which was usually available in most laboratories, such as a Hall effect sensor, an(More)
We study the creation and erasure of the linear electrooptical effect in silicate fibers by optical poling. Carriers are released by exposure to green light and displaced with simultaneous application of an internal dc field. The second order nonlinear coefficient induced grows with poling bias. The field recorded (~10⁸ V/m) is comparable to that obtained(More)
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