The aim of this study was to evaluate an efficiency of clay minerals (kaolinite, illite, Na- and Ca-montmorillonite) in alleviating the water repellency of stearic acid sand during the course of long-term hot and dry spell. This spell was simulated by prolonged drying (incubation) of the samples in oven at 50°C. It was found that the kaolinite addition resulted in a drop in the persistence of water repellency of the stearic acid sand. On the contrary, the Ca-montmorillonite addition increased markedly the persistence of water repellency of the stearic acid sand. In most cases, the illite addition resulted in an increase in the persistence of water repellency, even though not so markedly as it was in the case of Ca-montmorillonite addition. In the case of Na-montmorillonite addition, the striking drop in the persistence of water repellency of the stearic acid sand was registered only after lowering the moisture below 5 %. An increase in the persistence of water repellency of the sand-clay mixture with an increase in the clay amount is another interesting finding, observed in case of kaolinite and Ca-montmorillonite. and Cieľom tejto štúdie bolo zhodnotenie efektívnosti ílových minerálov (kaolinitu, illitu, Na- a Camontmorillonitu) pri znižovaní stálosti vodoodpudivosti piesku pokrytého kyselinou stearovou počas dlhého suchého a teplého obdobia, simulovaného inkubáciou vzoriek pri teplote 50 °C. Zistili sme, že pridanie kaolinitu výrazne znížilo stálosť vodoodpudivosti piesku pokrytého kyselinou stearovou prakticky počas celého cyklu sušenia. Pridanie Ca-montmorillonitu naopak stálosť vodoodpudivosti piesku pokrytého kyselinou stearovou výrazne zvýšilo. Pridanie illitu vo väčšine prípadov zvýšilo stálosť vodoodpudivosti piesku pokrytého kyselinou stearovou, aj keď nie tak výrazne ako pridanie Ca-montmorillonitu. V prípade pridania Na-montmorillonitu sme výrazné zníženie vodoodpudivosti piesku pokrytého kyselinou stearovou zaznamenali až po poklese vlhkosti vzorky pod 5 %. Ďalším zaujímavým poznatkom je vzrast vodoodpudivosti so zvyšujúcim se obsahom ílu, ktorý sme zaregistrovali v prípade kaolinitu a Ca-montmorillonitu.
The information contained in the measure of all shifts of two or three given points contained in an observed compact subset of $\mathbb{R}^d $ is studied. In particular, the connection of the first order directional derivatives of the described characteristic with the oriented and the unoriented normal measure of a set representable as a finite union of sets with positive reach is established. For smooth convex bodies with positive curvatures, the second and the third order directional derivatives of the characteristic is computed.
In morphological and biochemical studies we demonstrated that the development of eight-day old dark-grown beán seedlings was drastically influenced by prolonged irradiation with far red (FR) irradiation. The synthetic processes associated with leaf expansion were fiilly active, but the accumulation of chJorophyll (Chl) was very slow and the development of the photosynthetic apparatus was much prolonged. The capacity for oxygen evolution and photophosphorylation began at about the 2''‘* day. Low temperature spectroscopy showed the accumulation of three Chl a forms with absorption maxima at 670, 677 and 683 nm from the veiy beginning of the greening process and the appearance of two longer wavelength forms (with maxima at 690 and 698 nm) at the onset of photosynthetic activity. Electron microscopy showed unfiised stacks of primary thylakoids without grana formation. When the FR treated seedlings were subsequently placed in "white light", grana differentiated from these primary thylakoids.