P.C. Chaves

High airborne PM2.5 chlorine concentrations link to diabetes surge in Portugal.

Since 1995 airborne particles have been sampled near Lisbon and analysed by PIXE at ITN. On the Summer of 2004 extremely high concentrations of 14 microg/m(3) of chlorine in PM2.5 were determined in a week average sample. Later in 2004 and in 2005 similar events occurred. A 12 year database of PIXE data on airborne elemental concentrations (1995 to 2006) compiled on 2007 was then analysed for PM2.5 chlorine concentrations above 1 microg/m(3), and showed that the number of this type of events per year is increasing since 1995 up until the present. A quest for time coincident abnormal health data reports was carried out and revealed a 30% raise in diabetes mellitus incidence from 2003 to 2004 followed by a 20% raise from 2004 to 2005. After a first short publication at the XIth Int. PIXE Conference in 2007 (Reis et al., 2007a) the problem remained live. Taking into account new insights into the problem, recently published data, and biomonitoring data that were previously not considered, it was possible to establish a highly probable link between the abnormally high values of PM2.5 chlorine measured in the Lisbon area and the surge in diabetes mellitus incidence in Portugal in 2004 and 2005. Data, reasoning, possible mechanisms and conclusions regarding this link are reported in the present paper.

Combination of IBA Techniques for Composition Analysis of GaInAsSb Films

Quaternary GaInAsSb films alloys were grown by MOVPE technique on GaSb substrates with different growth conditions such as substrate orientation and thickness. The composition of the films determines their bandgap, and also how well they are lattice matched to the substrate. It is thus essential to determine it accurately, which is not a trivial task in this system. The composition of the samples was studied with a combination of Particle Induced Xray Emission (PIXE) and Rutherford Backscattering Spectrometry (RBS) experiments. The RBS experiments were done with a 2 MeV 4He+ or H+ ion beam, according to the thickness of the films, and were used to determine the thickness of the samples. The PIXE experiments were performed at grazing angle conditions and provided accurate elemental composition information. It was found that for thin layers (300 nm) there is a dependence of In incorporation into the matrix according to the substrate orientation, although this tendency was not found for thicker films (24m).

IBIXFIT: A Tool For The Analysis Of Microcalorimeter PIXE Spectra

PIXE analysis software has been for long mainly tuned to the needs of Si(Li) detector based spectra analysis and quantification methods based on Kα or Lα X‐ray lines. Still, recent evidences related to the study of relative line intensities and new developments in detection equipment, namely the emergence of commercial microcalorimeter based X‐ray detectors, have brought up the possibility that in the near future PIXE will become more than just major lines quantification. A main issue that became evident as a consequence of this was the need to be able to fit PIXE spectra without prior knowledge of relative line intensities. Considering new developments it may be necessary to generalize PIXE to a wider notion of ion beam induced X‐ray (IBIX) emission, to include the quantification of processes such as Radiative Auger Emission. In order to answer to this need, the IBIXFIT code was created based much on the Bayesian Inference and Simulated Annealing routines implemented in the Datafurnace code [1]. In this ...