Improvement of the shadow tracking setup as a method to measure the velocities values of dark dust in order to reduce the risks of radioactive releases or explosions.

The mobilisation of dust is a key security issue in nuclear and industrial plants because it can provoke both explosions (in particular temperature and pressure conditions) and dangerous radioactive releases. This work is focused on the tungsten dust resuspension inside small tank for aerosol removal and DUST (STARDUST)-Upgrade, an experimental facility used to reproduce different conditions typical of the loss of vacuum accidents. In this paper, the authors present the facility and the materials used to mount the experimental setup together with the methods and algorithms implemented to track the dust velocity vectors. Tungsten dust is also analyzed through scanning electron microscopy and X-ray diffraction to find some correlation between the variation of the dust morphology, due to the different experimental conditions, with the dust mobilisation paths. The materials and methods together with the experimental results are analyzed and discussed to demonstrate the implementation with the shadow tracking setup presented in the previous facility STARDUST.

Single walled carbon nanotube/Si heterojunctions for high responsivity photodetectors.

Single walled carbon nanotube/n-Si (SWCNT/n-Si) hetero-junctions have been obtained by depositing SWCNT ultra-thin films on the surface of an n-Si substrate by dry transfer method. The as obtained junctions are photo sensitive in the measured wavelength range (300-1000 nm) and show zero bias responsivity and detectivity values of the order of 1 A W-1 and 1014 Jones respectively, which are higher than those previously observed in carbon based devices. Moreover, under on-off light excitation, the junctions show response speed as fast as 1 µs or better and noise equivalent powers comparable to commercial Si photomultipliers. Current-voltage measurements in dark and under illumination suggest that the devices consist of Schottky and semiconductor/semiconductor junctions both contributing to the fast and high responses observed.

Diatom frustules decorated with zinc oxide nanoparticles for enhanced optical properties.

Zinc oxide (ZnO) nanoparticles were synthesized on diatomite (DE) surface by a low temperature sol gel technique, starting from zinc acetate dihydrate (Zn(CH3COO)2 · 2H2O) solution in water/ethyl alcohol, in presence of triethanolamine (TEA) with functions of Zn2+ chelating agent, catalyst and mediator of nanoparticle growth on DE surface. Microstructural features were investigated by field emission scanning electron microscopy and x-ray diffraction. ZnO crystalline nanoparticles, well distributed both on the surface and into the porous architecture of diatomite, were obtained just after the synthesis carried out at 80 °C without the need of calcination treatments. The optical properties of ZnO/DE hybrid powders were measured for the first time by means of photoacoustic spectroscopy (PAS). A new method to retrieve both the optical absorption and scattering coefficients from PAS is here discussed for powder aggregates. The fingerprint of the zinc oxide nanoparticles has been highlighted in the Mie scattering resonance in the UV-Vis range, and in the enhancement of the optical absorption with respect to diatomite.

Novel processing of bioglass ceramics from silicone resins containing micro- and nano-sized oxide particle fillers.

Highly porous scaffolds with composition similar to those of 45S5 and 58S bioglasses were successfully produced by an innovative processing method based on preceramic polymers containing micro- and nano-sized fillers. Silica from the decomposition of the silicone resins reacted with the oxides deriving from the fillers, yielding glass ceramic components after heating at 1000°C. Despite the limited mechanical strength, the obtained samples possessed suitable porous architecture and promising biocompatibility and bioactivity characteristics, as testified by preliminary in vitro tests.