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. Valachoviˆ, M. (2002): The syntaxonomical revision of the riparian plant communities dominated by Petasites hybridus in Slovakia. - Biologia , Bratislava, 57 (4): 471-492. The syntaxonomical revision of the riparian plant

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Mali, V. R. (2000): Serodiagnosis of viruses transmitted through the seeds of broadbean ( Vicia faba L.). Proc. XVth Czech and Slovak Plant Prot. Conf., Brno., Sept. 12-14, 2000. pp. 64-65. Serodiagnosis of viruses transmitted

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Demographic, Temporal and Environmental Effects on the Frequency of cribra orbitalia in Three Early Medieval Populations from Western Slovakia . HOMO – Journal of Comparative Human Biology 61 , 178 – 190

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keramiky. In: Praehistorica 22. Varia Archaeologic a 7. Praha 1997, 9–40. Hovorka 2005 = D. Hovorka : Metamorphosis of industrial and postindustrial age — Technometamorphosis. (in Slovak with English abstract). 1

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Abstract

Resorcinol–formaldehyde aerogels (five samples, three of them with addition of nitrogen containing precursors—3-hydroxypyridine, 3-aminophenol and melamine) have been prepared by sol–gel polycondensation, subcritical drying and pyrolysis. The pyrolysis of prepared organic aerogels has been studied by non-isothermal TG at constant heating rate. The process of pyrolysis has been found to consist of three steps with the total mass loss 40.2–61.7% (room temperature—1,000 °C). The resulted carbon aerogels have been tested as sorbents of Ni(II), Pb(II) and Cu(II) ions from aqueous solutions. Various relations have been found among the results obtained from the pyrolysis experiments and properties affecting adsorption. Besides the expected correlation between the mass loss gained from TG (isothermal step at 500 °C was applied) and from heating in the laboratory oven, the relationship between the mass loss during pyrolysis and sorption capacities for all three metal ions has been found. Other relations among pyrolysis behaviour, surface area and content of nitrogen have been also examined. Batch adsorption experiments show (with an exception of one sample) that N-doped samples have higher adsorption capacity for metal ions. In addition, changing of nitrogen functionalities during the pyrolysis has been considered and pyridinic-N (N-6) functionality has been contemplated as a suitable structure for the adsorption process.

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The process of oxygen chemisorption on coal in the temperature range ≈150–300 °C was studied under different experimental conditions using TG-DSC apparatus. As changing experimental conditions, oxygen flow (20 or 200 cm3 min−1), material of crucible (α-Al2O3 or Pt–Rh alloy), and initial sample mass (2–13 mg) were examined with respect to reliability and reproducibility of the parameters derived from TA curves. As parameters quantifying coal oxidation, temperatures of minimal T min and maximal T max sample mass, mass changes (mass loss W H below T min and mass increase W O above T min), heat evolution during oxygen chemisorption Q O (related to the coal mass increase), and kinetic parameters (activation energy E and frequency factor A) were evaluated. Values of T max, E, and A were found to lie in very close intervals independently on experimental conditions (95% confidence intervals were T max = 270.2 ± 0.7 °C, E = 81 ± 3 kJ mol−1, log10 A = 5.9 ± 0.3 s−1). Thus, these parameters can be used as actual characteristics of oxygen chemisorption stage of coal oxidation irrespective on conditions of TA measurements. Opposite, parameter Q O was confirmed to depend clearly on initial sample mass. The dependence is different for crucible materials used; however, it tends to the same value (≈50 kJ g−1) with increasing sample mass. Further, precision of values W H, W O, and T min determined from TG was found to be poor. This fact complicates evaluation of the effect of experimental conditions. Finally, the effect of oxygen flow on all above parameters was found to be negligible. Its influence (if any) was hidden by common experimental errors.

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events of the S. Slovakia depressions in the light of the stress-field analyses). - Mineralia slovaca, 25, pp. 79-92. Sled paleogénnych a neogénnych tektonických udalosti v juhoslovenských kotlinách vo svetle napätových analýz

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Abstract  

An influence of inorganic compounds (Fe2O3, ZnO, PbO, CaCO3 and K2CO3) on the blast furnace coke thermal oxidation in the air and in the CO2atmosphere was investigated by means of thermal analysis. A catalytic effect showed itself at the oxidation in the air, especially with PbO and K2CO3. These compounds bring the oxidation starting temperature and activation energy down and increase the reaction rate constant most distinctly. The PbO and K2CO3 actions differ in their mechanisms. K2CO3 accelerates particularly the amorphous coke fractions oxidation. In the CO2 atmosphere an important catalytic effect occurred only with K2CO3. The PbO catalytic influence is less distinct.

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