Probing functional groups at the gas-aerosol interface using heterogeneous titration reactions: a tool for predicting aerosol health effects?

The complex chemical and physical nature of combustion and secondary organic aerosols (SOAs) in general precludes the complete characterization of both bulk and interfacial components. The bulk composition reveals the history of the growth process and therefore the source region, whereas the interface controls--to a large extent--the interaction with gases, biological membranes, and solid supports. We summarize the development of a soft interrogation technique, using heterogeneous chemistry, for the interfacial functional groups of selected probe gases [N(CH(3))(3), NH(2)OH, CF(3)COOH, HCl, O(3), NO(2)] of different reactivity. The technique reveals the identity and density of surface functional groups. Examples include acidic and basic sites, olefinic and polycyclic aromatic hydrocarbon (PAH) sites, and partially and completely oxidized surface sites. We report on the surface composition and oxidation states of laboratory-generated aerosols and of aerosols sampled in several bus depots. In the latter case, the biomarker 8-hydroxy-2'-deoxyguanosine, signaling oxidative stress caused by aerosol exposure, was isolated. The increase in biomarker levels over a working day is correlated with the surface density N(i)(O3) of olefinic and/or PAH sites obtained from O(3) uptakes as well as with the initial uptake coefficient, γ(0), of five probe gases used in the field. This correlation with γ(0) suggests the idea of competing pathways occurring at the interface of the aerosol particles between the generation of reactive oxygen species (ROS) responsible for oxidative stress and cellular antioxidants.

La humanización de las imágenens emitidas por la publicidad de los destinos monumentales: el caso de Girona

This article is based on the presentation of the results of a study on the humanisation of the image of cultural destinations, applied to the case of the city of Girona. According to the theories raised by different authors, we were interested in analyzing if the tourist images shown by the tourists publicity are influenced by romantic references typical of the dynamics of individual consumption. That is to say, if these images project a vision of an empty city, a museum.city, an individual panoramic or an individual consumption experience. The results of the analysis allow us to affirm that a mythical image of the city exists and it has a clearly romantic origin. Nevertheless, on the other hand, a specific glance exists where the tension between the indivudual freedom and the social conventionalism is demonstrated