Meso, meso′-buta-1,3-diyne-bridged Ni (II) octaethylporphyrin dimer thin films have been deposited by the Langmuir–Blodgett method and, for the first time, have been considered as the active layer in resistive gas sensors. In particular, the electrical conductivities of these films undergo a remarkable variation due to exposure to small concentrations of NO in air at an operating temperature of 50 °C. To interpret the behavior of such organic films, a model has been built up and the conductivity variation as a function of test gas concentrations and time has been derived. The fitting of theoretical and experimental behavior allows us to determine the number of adsorbed gas molecules per porphyrin dimer, response and recovery times, adsorption and desorption coefficients. The reliability of the model is proved by obtained results. In particular, the determined adsorption and desorption coefficients depend only on test gas species but are unaffected by other experimental conditions such as gas concentration.
A detailed structural and morphological investigation has been carried out by conventional transmission electron microscopy, high resolution electron microscopy and nanodiffraction methods on vanadium oxide films obtained by reactive rf sputter at a high power discharge (1000 W) and different O2/Ar ratio. Electrical characterization has been also performed in controlled atmosphere in order to investigate the influence of NO2 oxidizing gas on the material conductance as a function of deposition parameters. A strict relation between structure, morphology and resistance variation in controlled atmosphere has been observed.
Environment hazards and risks of engineered NanoParticles (NPs) have been debated in recent years. In this paper, the effects of silver (Ag) and carbon (C) NPs were explored in sea urchin Paracentrotus lividus (P. lividus) development. Fertilization and development of P. lividus up to the pluteus stage were assayed in the presence of increasing amounts of NPs. The embryotoxicity test performed on sea urchin P. lividus, from fertilization until the larva stage, revealed that both AgNPs and CNPs were embryotoxic since they caused embryo malformations and alteration of the normal progression through the development stages. Embryonic development was slowed down by AgNPs and sped up by CNPs. Interestingly, AgNPs-induced malformations led embryos to die in a concentration-dependent manner; while embryos bearing CNPs-induced malformations survived for a longer time.
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