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  • Author: Ivan Novotný x
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Ecology and distribution of the rare copper moss Streptocolea atrata (Bryopsida, Grimmiaceae) in the Czech Republic

Abstract

The current distribution of the moss Streptocolea atrata (Hornsch.) Ochyra & Żarnowiec (Bryopsida, Grimmiaceae) in the Czech Republic is reviewed. This species is known to occur only in the Giant Mountains and Bohemian Forest in this country. The history of its discovery is presented and all the available specimens are listed and their distribution is indicated in a map. The global distribution of S. atrata is briefly commented.

Open access
Comparison of two methods of erosive rains determination

Abstract

Number of erosive rains, kinetic energy of erosive rains and factor of erosive efficiency of rains according to the USLE methodology were assessed by two methods of erosive rains determination. The first method (VAR1) defined erosive rains by intensity ≥ 0.4 mm· min-1; total ≥ 12.5 mm and the second method (VAR2) by intensity ≥ 6 mm· 15 min-1; total ≥ 12.5 mm. Database contained one minute precipitation data from four automatic stations in the Czech Republic for the period of 2000-2005. Two-way analysis of variance (ANOVA) showed a statistically highly significant difference between the annual number of erosive rains determined by the two methods. The rains simultaneously complying with two following criteria (30 min intensity lower than 15 mm·h−1 and sum of 40 mm) were not generally classified as erosive rains according to VAR2. The number of erosive rains determined by VAR2 most often reached 40 to 50% of VAR1 results. Two-way ANOVA proved highly significant differences between the kinetic energy values for the erosive rains determined by VAR1 a VAR2. According to VAR2 the rains with kinetic energy lower than 3 MJ·ha −1 are generally not considered as erosive rains. The results of kinetic energy of the erosive rains determined by VAR2 most often reached 60 to 70% of VAR1 results. Two-way ANOVA has not proved a statistical difference between annual values of R factor of erosive rains determined by the two methods. According to VAR2 the rains with R factor lower than 5 are in general not included into annual R factor value. The results of annual R factor values of erosive rains determined by VAR2 are about 25% lower than the results of VAR1. Correlation between number of erosive rains, kinetic energy of erosive rains and annual R factor value assessed by both methods showed a statistically significant relationship. The conversion formulas between results of the two methods (VAR1 and VAR2) were derived by linear regression. As conclusion we can state that when using present automatic stations in R factor analyses, we have to be aware of overestimating the erosivities compared to historical data based on ombrograms, where only low temporal resolution data were available.

Open access
Land Consolidations as an Effective Instrument in Soil Conservation

Abstract

Kadlec V., Žížala D., Novotný I., Heřmanovská D., Kapička J., Tippl M.: Land consolidations as an effective instrument in soil conservation. Ekológia (Bratislava), Vol. 33, No. 2, p. 188-200, 2014.

In the Czech Republic, more than 50% of agricultural land is threatened by water erosion, which is tremendously increasing during last couple of years. Therefore, it is necessary to deal with soil conservation as soon as possible. Land consolidations (LCs) are thus an important tool for implementation of soil, water and landscape conservation measures. It is possible to arrange land ownerships by them. They also arrange land spatially and functionally, provide availability of parcels and their land use in public interest. Besides that, environmental improvement, soil conservation, water management and increase in landscape ecological stability supplement the use of LCs. The results of soil consolidations serve for renewal of cadastral records and for the backgrounds for landscape planning. The aim of the research was to evaluate the selected site (district Plzeň - South) with regard to the amounts and limits of proposed and implemented measures in LC process. The research was processed on the basis of detailed analysis regarding erosion risk and runoff conditions in GIS compared with the previous data (before LC).

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Fabrication and characterization of Si/SiO2/TiO2/ZnO heterostructures from sputtered and oxidized Ti-film

Abstract

The present work reports the fabrication of p-Si/SiO2 /TiO2 and p-Si/SiO2 /TiO2 /ZnO heterostructures deposited by RF sputtering on p-Si substrate. The structural properties of the heterostructures were characterized by X-ray reflectivity and SIMS depth profiling. The electrical and optical properties of the heterostructures were investigated by I − V, C-V measurements and VIS spectroscopy, respectively. The measurements reveal that I − V characteristics in dark show semiconductor-insulator-semiconductor (SIS) structure properties. The I − V characteristics under illumination exhibit changes with significant increase of photocurrent due to photoassisted tunnelling and injection through SiO2 /TiO2 interlayer.

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Fabrication and Characterization of N-Type Zinc Oxide/P-Type Boron Doped Diamond Heterojunction

Abstract

Diamond and ZnO are very promising wide-bandgap materials for electronic, photovoltaic and sensor applications because of their excellent electrical, optical, physical and electrochemical properties and biocompatibility. In this contribution we show that the combination of these two materials opens up the potential for fabrication of bipolar heterojunctions. Semiconducting boron doped diamond (BDD) thin films were grown on Si and UV grade silica glass substrates by HFCVD method with various boron concentration in the gas mixture. Doped zinc oxide (ZnO:Al, ZnO:Ge) thin layers were deposited by diode sputtering and pulsed lased deposition as the second semiconducting layer on the diamond films. The amount of dopants within the films was varied to obtain optimal semiconducting properties to form a bipolar p-n junction. Finally, different ZnO/BDD heterostructures were prepared and analyzed. Raman spectroscopy, SEM, Hall constant and I-V measurements were used to investigate the quality, structural and electrical properties of deposited heterostructures, respectively. I-V measurements of ZnO/BDD diodes show a rectifying ratio of 55 at ±4 V. We found that only very low dopant concentrations for both semiconducting materials enabled us to fabricate a functional p-n junction. Obtained results are promising for fabrication of optically transparent ZnO/BDD bipolar heterojunction.

Open access