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PFAS substances, which have been under investigation in recent years, are certainly some of the most critical emerging contaminants. Their presence in drinking water, correlated with diseases, is consistently being confirmed by scientific studies in the academic and health sectors. With the aim of developing new technologies to mitigate the water contamination problem, research activity based on advanced oxidation processes for PFAS dealkylation and subsequent mineralization is active. While UV radiation could be directly employed for decontamination, there are nevertheless considerable problems regarding its use, even from a large-scale perspective. In contrast, the use of cheap, robust, and green photocatalytic materials active under near UV-visible radiation shows interesting prospects. In this paper we take stock of the health problems related to PFAS, and then provide an update on strategies based on the use of photocatalysts and the latest findings regarding reaction mechanisms. Finally, we detail some brief considerations in relation to the economic aspects of possible solutions.

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This paper focuses on the development of computational procedures for the trajectory optimization of maneuvering rotorcraft vehicles. The flight mechanics models are based on classic blade element theory, and are applicable to both helicopters and tilt-rotors. Maneuvers are formulated here as optimal control problems, whose solution minimizes an appropriate cost function subjected to constraints that translate the flight envelope limitations of the aircraft and all the necessary safety and operational requirements. A finite element based transcription process is used for discretizing the problem, leading to a finite dimensional parameter optimization. Procedures are proposed for ensuring flyable solutions and realistic control time histories that are compatible with the hidden (unmodelled) actuator dynamics. The methodology is used for studying the take-off of helicopters and tilt-rotors in the one-engine failure case under Category-A certification requirements. Nomenclature

Fire risk in high-rise buildings is of special concern to the fire community, since it is crucial but still technically extremely challenging to significantly improve the current fire fighting capabilities when a calamity happens above the "seven story limit." In fact, at the moment, there is a lack of effective means for fire fighting in this rare but potentially deadly and costly accidents. To address this problem, in this work we provide a preliminary exploration of a new concept for fire suppression: the use of rotorcraft vehicles for aerial fire fighting in high-rise buildings. If available, such system could effectively support fire fighting efforts conducted with conventional means; moreover, it could provide for one of the very few alternatives to classic systems in certain critical cases such as postearthquake fires. At first, we analyze the operative context with the help of a few reference realistic scenarios which allow for the estimation of some key physical parameters. Next, we evaluate two alternative fire extinguishing technologies, and we identify in the water impulse cannon the solution which seems to be the most effective and compatible with the use on-board a rotorcraft for the scopes considered in this work. The analysis leads us to the identification of a target vehicle as a possible candidate platform for the development of a fire fighting helicopter. Finally, we propose a preliminary design of the fire fighting kit, and we evaluate the handling qualities of the vehicle during operations with reference to the ADS-33 normative

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