Giuseppe Pezzotti

Abstract The Raman spectrum of living cells and microorganisms contains highly specific fingerprint‐like signatures, useful in unequivocally identifying different species and interpreting physiological and metabolic responses to environmental stressors. In situ Raman imaging with dedicated highly sensitive instruments can translate selected spectroscopic fingerprints into vivid snapshots of molecular species or specific physiological reactions. Time‐lapse experiments, crucial in characterizing g

Confocal Raman piezo-spectroscopy has been used for the quantitative assessments of phase transformation and residual stresses in zirconia made artificial hip joints. This work can be considered to be a first step towards the development of a fully quantitative technique for the spectroscopic characterization of zirconia femoral heads and other zirconia parts for biomedical applications. After establishing reliable calibration procedures, Raman microprobe spectroscopy could be extended to provid

In the closing decades of the 20th century, silicon nitride (Si₃N₄) was extensively developed for high-temperature gas turbine applications. Technologists attempted to take advantage of its superior thermal and mechanical properties to improve engine reliability and fuel economy. Yet, this promise was never realized in spite of the worldwide research, which was conducted at that time. Notwithstanding this disappointment, its use in medical applications in the early 21st cen

While the reciprocity between bioceramics and living cells is complex, it is principally governed by the implant's surface chemistry. Consequently, a deeper understanding of the chemical interactions of bioceramics with living tissue could ultimately lead to new therapeutic strategies. However, the physical and chemical principles that govern these interactions remain unclear. The intricacies of this biological synergy are explored within this paper by examining the peculiar surface chemistry of

A procedure is described for the evaluation of the fracture behaviour of polycyrstalline ceramics using an in-situ stress analysis involving either fluorescence or Raman microprobe spectroscopy. The full details of the experimental set-up, calibration procedures and stress calculations are shown, and their reliability discussed in some detail. Stress maps were obtained along the wake of cracks stably propagated in six selected polycrystalline ceramics with representative microstructures. A conve

Organisms of Gram-negative phylum bacteroidetes, Porphyromonas gingivalis, underwent lysis on polished surfaces of silicon nitride (Si3N4) bioceramics. The antibacterial activity of Si3N4 was mainly the result of chemically driven principles. The lytic activity, although not osmotic in nature, was related to the peculiar pH-dependent surface chemistry of Si3N4. A buffering effect via the formation of ammonium ions (NH4(+)) (and their modifications) was experimentally observed by pH microscopy. L

Abstract A quantitative assessment of the Raman spectrum emitted from a coarse‐grained polycrystal of multiferroic BiFeO 3 has been carried out by means of a polarized Raman microprobe. The dependence of the intensity of Raman phonon modes has been first theoretically modeled as a function of crystal rotation. Then, the Raman tensor elements have been experimentally determined from the analysis of the A g and E g vibrational modes. Copyright © 2009 John Wiley & Sons, Ltd.

A dense and isotropic Si 3 N 4 composite body containing 25 vol% of α‐SiC platelets, with average particle size of 24μm and aspect ratio of 8 to 10, was fabricated by hot isostatic pressing without any addition of sintering aids. In this composite, desirable properties for structural ceramics to be used in long‐term high‐temperature applications are conveniently combined: a fracture resistance comparable with that of Si 3 N 4 sintered with conspicuous amounts of additives, as well as a superior

The hypothesis that a synergistic effect by fine SiC dispersoids operating on the submicrometer scale is capable of enhancing the deformation and fracture properties of Si 3 N 4 ceramics has been examined. In order to single out the effect of the SiC dispersion from other microstructural factors affecting the material properties, experiments were conducted on a highly pure and dense Si 3 N 4 material, suitable for basic investigations. Fracture mechanics and creep characterizations were performe