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A new theory suggests that flammable gases generated by heated vegetation, in particular the volatile organic compounds (VOC) common to Mediterranean plants, may, under certain topographic and wind conditions, accumulate in locations where, after the arrival of the ignition source, they rapidly burst into flames as explosions. Hence, there is a need for the development of a system that can monitor the development of these compounds. In this work, a sensor's array is proposed as a method for monitoring the amount of eucalyptol and α-pinene, the major VOC compounds of the Eucalyptus and Pine trees. The detection of the target compounds was assessed using the impedance spectroscopy response of thin films. Combinations of layers of polyelectrolytes, such as poly(allylamine hydrochloride) (PAH), polyethyleneimine (PEI), poly(sodium 4-sytrenesulfonate) (PSS) graphene oxide (GO), and non/functionalized multiwall nanotubes (MWCNT-COOH or MWCNT), namely, PAH/GO, PEI/PSS, PEI/GO, PAH/MWCNT, PAH/MWCNT-COOH, films, and TiO 2 and ZnO sputtered films, were deposited onto ceramic supports coated with gold interdigitated electrodes. The results showed that concentrations of the target VOCs, within the range of 68 to 999 ppm v , can be easily distinguished by analyzing the impedance spectra, particularly in the case of the ZnO- and PAH/GO-film-based sensors, which showed the best results in the detection of the target compounds. Through principal component analysis (PCA), the best set of features attained for the ZnO and PAH/GO based sensor devices revealed a linear trend of the PCA's first principal component with the concentration within the range 109 and 807 ppm v . Thus, the values of sensitivity to eucalyptol and α-pinene concentrations, which were (2.2 ± 0.3) × 10 -4 and (5.0 ± 0.7) × 10 -5 per decade, respectively, as well as resolutions of 118 and 136 ppb v , respectively, were identified.

The coffee cultivation has historically had great importance in Rio de Janeiro's social-spatial organization, and it is once again in the spotlight of the state's economic scenario. The novelty is that the local production has been renewed, and, now, the state surpasses the old status of 'low-quality coffee producer' and achieves the 'specialty coffee' market which, in addition to quality, also values environmental, social and economic sustainabilities . This change has caused a series of transformations in the social-spatial and economic realities of some municipalities in the state of Rio de Janeiro. This article analyses the possible sustainabilities existing in the production process of this new coffee profile, based on the reality of the municipality of Varre-Sai, located in the northwest of Rio de Janeiro state. The objective is to find out the main actors and to elucidate the political network involved in this process., (© 2021 The Authors.)