A complete method is presented for the evaluation of photoneutron spectra produced in linear accelerators for cancer radiotherapy. It consists of a computer simulation code based on the MCNP4B Monte Carlo code, in which the new routine GAMMAN was implemented, allowing the accurate study of photoneutron production in high Z elements. In addition an experimental method based on a passive bubble spectrometer allows direct measurements of the photoneutron spectrum at the patient plane, also under the photon beam. The results are presented both for a 15 MeV linac with a traditional collimator system and for an 18 MeV linac equipped with a multileaf collimator, used in conformational radiotherapy.

We present an accurate ab initio study of the structure and surface energy of the low-index (100), ( 111) and (110) diamond faces, by using the hybrid Hartree-Fock/Density Functional B3LYP Hamiltonian and a localized all-electron Gaussian-type basis set. A 2D periodic slab model has been adopted, for which convergence on both structural and energetic parameters has been thoroughly investigated. For all the three surfaces possible relaxations and reconstructions have been considered. A detailed geometrical characterization is provided for the most stable structure of each orientation; surface energy is discussed for all the investigated faces. All data show a very good agreement with previous pure Density Functional calculations.

Silver nanocluster silica composite coatings were deposited by radio frequency co-sputtering technique on several substrates. This versatile method allows tailoring of silver content and antibacterial behaviour of coatings deposited on glasses, ceramics, metals and polymers for several applications. Coating morphology and composition as well as nanocluster size were analyzed by means of UV-Visible absorption, X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), electron dispersive spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM). The antibacterial effect was verified through the inhibition halo test against standard bacterial strain, Staphylococcus aureus, before and after sterilization process. Tape test demonstrated a good adhesion of the coatings to the substrates.

No abstract