We present chemical beam vapor deposition (CBVD) as a valuable technique for the fabrication of good quality HfO2-based memristors. This deposition technique gives the opportunity to rapidly screen material properties in combinatorial mode and to reproduce the optimized conditions homogenously on large substrates. Cu/HfO2/Pt memory devices with three different oxide thicknesses were fabricated and electrically characterized. A bipolar resistive switching and forming free behavior was seen in all the tested devices. Lower switching voltages than similar devices fabricated by employing different deposition techniques were observed. The conduction mechanism in the low resistance state can be ascribed to filamentary copper, while a trap-controlled space charge limited current conduction was observed in the high resistance state. The comparative evaluation of devices with different oxide thicknesses allows to infer that devices with thicker HfO2 film (25 nm) are more performing in terms of ROFF/RON ratio (106), and reproducible resistive switching over more than 100 cycles in both low and high resistance states. Thinner oxide devices (20 nm and 16 nm), despite similar long retention time (104 s), and lower SET/RESET voltages show instead a smaller memory window and a switching instability. These results, compared also with other reported in literature for similar memristive structures realized with other deposition techniques, show that CBVD can be considered as a promising technique for realizing HfO2-based non-volatile memory devices with good performance.

In the EU, the Water-Cooled Lithium Lead (WCLL) Breeding Blanket (BB) concept is one of the candidates for the design of the DEMO reactor. From the past campaign of analysis emerged that the thermal-induced stress led to the failure in the verification of the RCC-MRx structural criteria. Hence, in this paper the classic conceptual design approach, based on a pure FEM thermal and structural analysis, is compared to a coupled thermofluid-dynamic/structural one. Even though the coupled approach requires tremendous modelling effort and computational burden, it surely allows determining the thermal field with a higher level of detail than the FEM analysis. Therefore, in this work, the focus is put on the impact of a more detailed thermal field on the DEMO WCLL BB global structural performances, focusing on the Top Cap region of its Central Outboard Blanket segment. The obtained results have allowed confirming the soundness of the design solution of the Top Cap region, except for concerns arising on the mass flow rate distribution. Moreover, results have shown that, globally, the pure FEM approach allows for obtaining more conservative results than the coupled one. This is a positive outcome in sight of the follow-up of the DEMO WCLL BB design, as it will be still possible adopting the pure FEM approach to quickly down-select design alternatives, using the most onerous coupled approach to finalise the most promising.

A series of measurements of particulate samples collected on paper filters in Palermo (Italy) during 1995–2005 has been performed to detect ${}^{210}$Pb air activity concentration and, along with previous similar data on ${}^7$Be, to evaluate their activity ratio. Average values for the daily activity concentrations of ${}^7$Be and ${}^{210}$Pb are found to be 4.7 and 0.6 mBq m ${}^{-3}$, respectively, 9.8 being the average activity ratio. Data confirm a seasonal behavior for both radionuclides. A correlation between ${}^7$Be and ${}^{210}$Pb air activity concentrations seems to exist, despite their different origins. The time behaviors of both ${}^7$Be and ${}^{210}$Pb air concentrations and ${}^7$Be/ ${}^{210}$Pb activity ratio have been compared with some meteorological parameter time series. The analysis of the data shows a weak correlation with rainfall, while no correlation can be established with other parameters. Monthly and weekly average values have been reconstructed taking into account missing data, in order to carry out homogeneous comparisons with available data from other geographical areas. Data series correlations and the frequency analysis show the importance of atmospheric transport processes and the influence of meteorological and climatic parameters (in particular rainfall) in determining the concentrations in air of both radionuclides.