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Biomedical subjects

R Fantoni

Publications and source records attributed to R Fantoni.

6 recordsLinked to original sources
PubMed2006

Influence of laser wavelength on LIBS diagnostics applied to the analysis of ancient bronzes.

In this work the influence of laser wavelength upon the analytical results obtained from applying LIBS diagnostics to bronzes was investigated theoretically and experimentally at 1,064 nm and 355 nm. The laser ablation process was modeled for a set of reference samples of quaternary Cu/Sn/Pb/Zn alloys and the difference between plume composition and known target stoichiometry was estimated for both of the wavelengths considered. LIBS measurements were performed on the same set of reference samples and under the same experimental conditions to validate the model at different wavelengths. Results from the application of the model to calculate sample optical properties during laser irradiation, absorption in the plasma and plasma temperature are also presented.

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PubMed2004

Computer simulation study of the closure relations in hard sphere fluids.

We study, using Monte Carlo simulations, the cavity and the bridge functions of various hard sphere fluids: one component system, equimolar additive, and nonadditive binary mixtures. In particular, we numerically check the assumption of local dependency of the bridge functions from the indirect correlation functions, on which most of the existing integral equation theories hinge. We find that this condition can be violated either in the region around the first and second neighbors shell, or inside the hard core, for the systems here considered. The violations manifest themselves clearly in the so-called Duh-Haymet plots of the bridge functions versus the indirect correlation functions and become amplified as the coupling of the system increases.

Journal Article↗
PubMed2003

Stability of the iterative solutions of integral equations as one phase freezing criterion.

A recently proposed connection between the threshold for the stability of the iterative solution of integral equations for the pair correlation functions of a classical fluid and the structural instability of the corresponding real fluid is carefully analyzed. Direct calculation of the Lyapunov exponent of the standard iterative solution of hypernetted chain and Percus-Yevick integral equations for the one-dimensional (1D) hard rods fluid shows the same behavior observed in 3D systems. Since no phase transition is allowed in such 1D system, our analysis shows that the proposed one phase criterion, at least in this case, fails. We argue that the observed proximity between the numerical and the structural instability in 3D originates from the enhanced structure present in the fluid but, in view of the arbitrary dependence on the iteration scheme, it seems uneasy to relate the numerical stability analysis to a robust one-phase criterion for predicting a thermodynamic phase transition.

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