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Abstract: Low temperature silicon dioxide layers (LTO), deposited on crystalline silicon substrates, and thermally densified at 750°C for 90min or 900°C for 30min, jointly with thermally grown silicon dioxide layers, were irradiated with low fluence 11MeV Ti ions. A selective chemical etch of the latent tracks generated by the passage of swift ions was performed by wet or vapour HF solution. The wet process produced conically shaped holes, while the vapour procedure generated almost cylindrical nanopores. In both cases thermal SiO2 showed a lower track etching velocity V t, but with increasing the densification temperature of the LTO samples, the V t differences reduced. LTO proved to be suitable for wet and vapour ion track formation, and, as expected, for higher densification temperatures, its etching behaviour approached that of thermal silicon dioxide. [Copyright &y& Elsevier]

Abstract: In this work x-cut Lithium Niobate crystals were implanted with 0.5MeV O ions (nuclear stopping regime), 5MeV O ions (sub-threshold electronic stopping regime) and 12.5MeV Ti ions (ion track regime) at the fluences required for the formation of a surface fully disordered layer. The damage depth profiles were determined by RBS-channeling. Wet etching was performed at room temperature in 50% HF:H2O solution. The data indicated an exponential dependence of the etching rate on the damage concentration. Independently of the damage regime, once random level in the RBS-channeling spectra was attained we measured the same etching rate (50–100nm/s) and the same volume expansion (∼10%) in all samples. These results indicate that the fully disordered layers obtained by electronic damage accumulation have the same chemical properties of those obtained by conventional nuclear damage accumulation and therefore they can be defined “amorphous”. The impressive etching selectivity of ion implanted regions makes this process suitable for sub-micro machining of Lithium Niobate. [Copyright &y& Elsevier]

Abstract: In this work latent ion tracks were produced in 0.5μm thermal SiO2/Si by Ti ion irradiation. The samples were subsequently etched both in aqueous and in vapor HF solution. As expected, the wet etching process resulted in conically shaped holes, whose superficial diameter increased linearly with the etching time, and was correlated to the track to bulk etching velocity ratio (v T/v B). A threshold for track development at about 3MeV (corresponding to an electronic stopping power of 192eV/Å) was obtained. The velocity ratio then increased with the energy to v T/v B ≅1.6 at 12.5MeV (440eV/Å). For the vapor etching process, cylindrical pores were obtained, with an almost constant diameter of 20–30nm, until the SiO2/Si interface was reached. Subsequently the pore diameter quickly increased, with a rate much higher than both v T and v B. The threshold for track development was again at 3MeV, and the velocity ratio increased with the energy to v T/v B ≅5.5 at 12.5MeV. The track yield was about 100% for all the energies above the threshold. [Copyright &y& Elsevier]

Swine dysentery is a mucohaemorrhagic colitis of pigs caused by infection with Brachyspira hyodysenteriae. The disease can be controlled by treatment with antimicrobial agents, with the pleuromutilins tiamulin and valnemulin being widely used. In recent years, the occurrence of B. hyodysenteriae with reduced susceptibility to these drugs has been increasing. The aim of this study was to determine temporal changes in genetic groups and pleuromutilin susceptibility amongst B. hyodysenteriae isolates from Italy. Multilocus sequence typing (MLST) was performed on 108 isolates recovered from 87 farms in different regions of Italy from 2003 to 2012, and their minimum inhibitory concentrations (MICs) for tiamulin and valnemulin were determined. Logistic regression was performed to assess associations between susceptibility to the two antimicrobial agents and genetic group, year and region of isolation. The isolates were allocated to 23 sequence types (STs), with five clonal clusters (Ccs) and seven singletons. More than 50% of isolates were resistant to both pleuromutilins (MIC >2.0 pg/mL for tiamulin and >1.0 gg/mL for valnemulin). All 10 isolates in ST 83 were resistant; these were first isolated in 2011 and came from nine farms, suggesting recent widespread dissemination of a resistant strain. Significant associations were found between the proportion of pleuromutilin susceptible isolates and the genetic group and year of isolation. Although resistant isolates were found in all Ccs, isolates in Ccs 2 and 7 were over five times more likely to be susceptible than those in the other Ccs. A significant trend in the reduction of susceptibility over time also was observed. [ABSTRACT FROM AUTHOR]

Abstract: High energy medium-light ion implantation was applied on both z-cut Er:LiNbO3 and Er3+–Yb3+ co-doped phosphate glasses, in order to fabricate optical waveguides on optically amplifying media. Preliminary results obtained with Er:LiNbO3, implanted with 3.9MeV Carbon ions, have demonstrated the possibility to fabricate good quality waveguides, the optical characteristics of which depend on implantation fluence and post-annealing process. Er3+–Yb3+ co-doped phosphate glass substrates were implanted with both 2.8MeV Carbon ions, at fluences ranging from 3×1014 ions/cm2 to 1×1015 ions/cm2, and with 3.4MeV Oxygen ions at a fluence of 1×1015 ions/cm2. Also in this case, planar optical waveguides were formed, but, under the as-reported implantation conditions, the possibility to tailor the refractive index profiles was very reduced. In this work, the optical properties of the integrated optical waveguides obtained on different doped substrates are examined. [Copyright &y& Elsevier]