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A semiclassical model for Schottky contacts to be applied to nanosized polycrystalline n-type semiconductors was developed. To this purpose we determined the density of surface states as a function of the mean grain radius, which establishes the Schottky barrier height. The intergranular potential shape was investigated in depletion approximation under spherical geometry and a critical revision of this method was proposed. The model was then extended to also include nanostructured materials, which could not be considered in the previous approach. Thus we were able to explain the flattening of the band bending and the decrease in the surface state density, which are experimentally observed when the granulometry is very fine.

Household air pollution is ranked the 9(th) largest Global Burden of Disease risk (Forouzanfar et al., The Lancet 2015). People, particularly urban dwellers, typically spend over 90% of their daily time indoors, where levels of air pollution often surpass those of outdoor environments. Indoor air quality (IAQ) standards and approaches for assessment and control of indoor air require measurements of pollutant concentrations and thermal comfort using conventional instruments. However, the outcomes of such measurements are usually averages over long integrated time periods, which become available after the exposure has already occurred. Moreover, conventional monitoring is generally incapable of addressing temporal and spatial heterogeneity of indoor air pollution, or providing information on peak exposures that occur when specific indoor sources are in operation. This article provides a review of new air pollution sensing methods to determine IAQ and discusses how real-time sensing could bring a paradigm shift in controlling the concentration of key air pollutants in billions of urban houses worldwide. We also show that besides the opportunities, challenges still remain in terms of maturing technologies, or data mining and their interpretation. Moreover, we discuss further research and essential development needed to close gaps between what is available today and needed tomorrow. In particular, we demonstrate that awareness of IAQ risks and availability of appropriate regulation are lagging behind the technologies.