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114 results on '"Houška, J."'

33. Controlled reactive HiPIMS – effective technique for lowtemperature deposition of VO2-based multilayer coatings for smart window applications

Author

Kolenatý, D., Vlček, J., Houška, J., Kozák, T., and Rendl, Jan

Subjects
aplikace chytrých oken, thin films, tenké vrstvy, smart window applications, depozice, deposition
Abstract

Studentská vědecká konference je pořádána s podporou prostředků na specifický vysokoškolský výzkum SVK1-2018-024. Vanadium dioxide (VO2) is a technologically important thin film material of a high current world wide interest due to its reversible first-order thermochromic transition relatively near room temperature (approximately 68°C). Magnetron sputtering is probably the most important preparation technique of VO2 films, and numerous deposition pathways have been reported in recent years. The research in this area is focused on (at least) the following three challenges. First, doping of VO2 by other metals in order to decrease the transition temperature (Ttr) from 68 °C (bulk materials) or e.g. 50 °C (thin films) to the room temperature. Second, decreasing the deposition temperature (Tdep) of crystalline VO2 at least below 300 °C, ideally without any substrate bias and without any crystalline interlayer, in order (i) to facilitate the large-scale production by reducing the energy consumption and minimizing problems with temperature uniformity over large substrate surfaces, (ii) to limit the diffusion of harmful elements from substrates such as soda-lime glass and (iii) to allow deposition on temperaturesensitive plastic substrates. Third, improving the luminous transmittance (Tlum) and the modulation of the solar transmittance (Tsol) of the coatings by antireflection (AR) layers. (J. Houška et al. (2017))

Published
2018

42. Long-term forest soil acidification, nutrient leaching and vegetation development: Linking modelling and surveys of a primeval spruce forest in the Ukrainian Transcarpathian Mts.

Author

Hruška, J., Oulehle, F., Šamonil, P., Šebesta, J., Tahovská, K., Hleb, R., Houška, J., Šikl, J., Hruška, J., Oulehle, F., Šamonil, P., Šebesta, J., Tahovská, K., Hleb, R., Houška, J., and Šikl, J.

Abstract

The biogeochemical model MAGIC was applied to simulate long-term (1880–2050) soil and stratified soil solution (30 and 90 cm depth) chemistry at a spruce dominated site in the western Ukraine (Pop Ivan, 1480 m a.s.l.) to evaluate the effects of acid deposition on soil acidification in a less polluted region of Europe. Since 2008, sulphur (S) deposition of 9 kg ha−1 year−1 and nitrogen (N) deposition of 8.5 kg ha−1 year−1 have been measured at Pop Ivan. The recent deposition of S and N is about 30% and 50% of those values estimated for the early 1980s, respectively. Acidic deposition caused the depletion of base cations (Ca, Mg, Na, K) from the soil cation exchange complex, which resulted in a decrease of calcium and magnesium saturation between 1935 and 2008 in the top mineral soil (0–30 cm) and deeper mineral soil (30–80 cm) by 67% and 88%, respectively. Base cation leaching acted as the major buffer mechanism against incoming acidity, therefore the measured inorganic aluminium (Al) concentration in soil solutions is ca. 10 μmol L−1 and the subsequent molar (Ca + Mg + K)/Al ratio above 1. Recovery of the soil solution pH and Al is expected within the next 40 years, whereas the soil base saturation will only increase slowly, from 6% to 9.8% in the top soil and from 5.5% to 11% in the deeper mineral soil. Since the 1960s, modelled inorganic N leaching (as NO3) has started to increase following the trend in N deposition. Modelling and experimental evidence suggest that N availability from mineralization and deposition exceeds the rate of microbial and plant immobilization. Thus, soil N accumulation since the 1960s has been limited. A significant increase in nitrophilous species as well as a decrease of herb layer diversity was observed between 1936 and 1997.

Published
2012

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