The paper deals with identification and factor analysis in relationship to aluminium surface topography created by abrasive waterjet. By means of design of experiments has been evaluated the influence of abrasive waterjet factors to surface irregularities of aluminium. Surface roughness has been quantified by means of surface profile paremeters Ra, Rq and Rz obtained from 24 depth trace lines. Information about surface topography of experimentally created samples has been achieved by means of 3D measurement of surfaces. and Práca sa zaoberá identifikáciou a analýzou faktorov vo vzťahu k topografii povrchov hliníka vytvorených hydroabrazívnym delením. Pomocou plánovaných experimentov sa sledoval vplyv faktorov na nerovnosti povrchu hliníka v iniciačnej, hladkej, prechodovej a zdrsnenej zóne. Drsnosť povrchu hliníka bola kvantifikovaná pomocou parametrov profilu Ra, Rq a Rz, ktoré boli zisťované v 24 hĺbkových líniách. Informácie o topografii povrchu experimentálne vyrobených vzoriek boli dosiahnuté 3D optickým meraním povrchu.
Recent studies have shown interest in the evolution to steady nonlinear pulsation in stellar models. The simplest description is nonresonant interaction between the fundamental and one of its overtones, if one is only interested in the behaviour of a few longlived modes. The generic forni of coupled-mode equations is not dependent upon a particular stellar model, although
the precise determination of the coupling constants for a given stellar model will ultimately be very involved. Qualitative
ideas about the eventual evolution of the mode energies give different scenarios, depending mainly on the nonlinear coupling
constants and the linear growth rates, if the latter are both positive. According to one scenario, a double-mode pulsator is possible. It is not necessary that all coupling constants be negative, if only the model is well behaved enough in excludinq unbounded solutions. With a linearly stable fundamental and a stable overtone another scenario shovys a further possibility for a double-mode pulsator, if one of the cross coupling constants is positive, so that the overtone nonlinearly grows before saturating. Such findings show the need for additional theoretical and numerical modelling and a cautious discussion thereof.
High irradiance (HI) effects on xanthophyll cycle pigments (XCP) and activity of violaxanthin de-epoxidase (VDE) in terms of de-epoxidation index (DEI) were studied in soybean calli. The calli from the hypocotyl segments of 5-d seedlings were induced on a solid (1.1 % agar) MS medium (pH 5.8) supplemented with 4.52 μM 2,4-dichloro-phenoxyacetic acid, 2.32 μM kinetin, and 3 % sucrose. After a 30 d cultivation, the green calli were irradiated for 24 h with "white light" (HI, 1 300 μmol m-2 s-1) and VDE was isolated from the photosystem 2 (PS2) particles. In the control (0 h irradiation) callus, the reaction of PS2 particles with VDE in the presence or absence of Tween 20 resulted in the decrease of VIO content and the increase of ZEA content. In the 24 h HI-callus, the reaction of PS2 particles in the absence of VDE led to the decrease of VIO and ANT contents and increase of ZEA content. In the control, DEIs in the presence of VDE with or without 0.1 %Tween 20 (1.04 and 1.06, respectively) were significantly higher than the DEI (0.76) in the absence of VDE. In the HI-callus, DEIs in the presence of VDE with or without 0.1 %Tween 20 (0.98 and 0.96, respectively) were similar to that (1.03) in the absence of VDE. and D. M. Pandey ... [et al.].
Sodium chloride salinity had enhanced the photosynthetic rate, photosystem 2 activity and chlorophyll synthesis in isolated leaf cells of Ipomoea pescaprae up to 200 mM NaCl. The salt treated plants did not show any shift in the mode of photosynthesis.
Aging induced loss of chlorophyll (Chl), carotenoids (Car) and proteins was studied in suspensions of isolated wheat chloroplasts incubated in the light or dark. Faster rate of pigment loss in the light was due to photodestruction of pigments. Compared to Chl, a greater loss of Car in the light was due to photoprotective action of Car towards Chl resulting in its own destruction. The total protein content was lowered more in the light than in dark. Soluble proteins of chloroplasts declined by 36 %, whereas membrane proteins showed a loss of only 8 % after 6 d of light incubation.
Quaternary ammonium salts, besides having an inhibitory effect which was studied by Králová eí al. (1992), exhibited at low concentrations a stimulating effect upon the oxygen evolution rate in spinách chloroplasts. The stimulation is caused by changes in arrangement of thylakoid membranes due to a detergent-like effect of the compoimds.