In presented work natural expanded vermiculite was used as a starting material for synthesis of Fe-doped catalysts. Material was modified with increasing amount of Fe by ion-exchange and precipitation of iron oxide. Composite materials were characterized with respect to their structure (X-ray diffraction, Infrared spectra using Diffuse Reflectance), agglomeration state of Fe (Ultraviolet-Visible spectra using Diffuse Reflectance) and chemical composition. Activity in H2O2 decomposition as well as in phenol oxidation was studied in liquid phase at atmospheric pressure and temperature up to 70 °C. It was shown that doping with Fe increases catalytic activity. However, excess of iron resulted in formation of undesired side-products., Agnieszka Węgrzyn, Lucjan Chmielarz, Paweł Zjeżdżalka, Magdalena Jabłońska, Andrzej Kowalczyk, Agata Żelazny, Manuel Vázquez Sulleiro and Marek Michalik., and Obsahuje bibliografii
The West Bohemia earthquake swarm foci are approximated by a circular seismic source model, which radius is assumed to depend only on magnitude of the event. We consider two different models of average slip (i) a constant slip and (ii) a slip exponentially scaled to the magnitude of the event. Based on these assumptions, we stacked the contributions of individual events into representative final fault slip. We processed in such a way four significant swarms recorded during the last three decades in 1986, 1997, 2000 and 2008. Constant slip model indicates final slip was composed of 2 or 3 principal asperities located on one or two different planes. On the contrary, scaled slip model indicates that one big asperity prevails. It is not possible yet to select the preferred slip model. Analysis of the temporal activity of all swarms generally shows three principal phases: starting phase, main phase and fading phase; the upwards trend of activity spreading was observed (slip animation is presented in www supplement http://www.ig.cas.cz/kolar/StopPhase/Asperity). The maximal possible cumulative slip value may have reached the order of meters., Petr Kolář, Bohuslav Růžek, Alena Boušková and Josef Horálek., and Obsahuje bibliografii
The purpose of this work was to detect groundwater pollution and to identify the conditions of soil and groundwater near the coal waste disposal "Panewniki" Halemba-Wirek Coal Mine using geoelectrical measurements. The firs t applied method was the VLF (Very Low Frequency) technique. This method, using military signals, allowed to perform the in-phase and the quadrature maps. Data were collected from four study areas located near the coal waste dump. Observed anomalies on both maps for each area showed places with different conductivity al lowed to detect the contaminated and uncontaminated zones. The VLF survey indicated that the contamination occurs in the eastern part of study area and is characterized by positive values of both measured electrical fields (the in-phase and the quadrature components). After preliminary contaminated zones were recognized using VLF met hod, an electrical imaging meth od was applied. Two electrical imaging profiles were carried out near the waste dump. The measurements a llowed to create the geoele ctrical model of surrounding area and to investigate the leachate plume. The electrical imaging showed that the greatest pollution occur in the area immediately adjacent to the coal waste what is confirmed by VL F survey. Based on the geological and ge ophysical knowledge from archives and on present researches, the contaminated aquifer with electrical resistivity of 5 to 15 Ω m deposited at depths of 3 to 7 m was found., Arlena Kowalska, Marta Kondracka and Maciej Jan Mendecki., and Obsahuje bibliografické odkazy
V článku jsou popsány různé moderní techniky, které lze využít pro studium biologických objektů v jantaru. Jde především o digitální fotografii v denním a infračerveném světle, skenování ve stolních skenerech, optickou a elektronovou mikroskopii, konfokální mikroskopii, mikroradiografii a rentgenovou mikrotomografii. Kombinace těchto technik může přispět k hlubšímu poznání fosilních inkluzí v jantaru., This paper describes various modern techniques used to study biological objects in amber. Those techniques include digital photography in daylight and in near-infrared light, scanning in desktop scanners, optical and electron microscopy, confocal microscopy, microradiography and X-ray microtomography. A combination of these techniques could contribute to a deeper understanding of fossil inclusions in amber., and František Weyda ... [et al.].
This paper presents the results of the application of wavelet decomposition to processing data from the GGP sites (The Global Geodynamics Project). The GGP is an international project within which the Earth's gravity field changes are recorded with high accuracy at a number of stations worldwide using superconducting gravimeters. Data with a 5-second sampling interval from Wettzell and Bad Homburg were used for the research. The wavelet transform enables the investigation of the temporal changes of the oscillation amplitudes or the decomposition of the time series for the analysis of the required frequencies. The wavelet decomposition was performed using the regular orthogonal symmetric Meyer wavelet. The research concerned data from an earthquake period recorded at various locations and a quiet period when the gravimeters worked without any disturbances. The decomposition was followed by the Fast Fourier Transform for signal frequency components and then by correlation analyses of corresponding frequency components (for periods from 10 to 60 000 seconds) for all sensor combinations, for the quiet and the earthquake periods separately. Frequency components defining long term changes for all sensor combinations, as well as combinations between two sensors at the same site for the quiet days are characterised by high correlation coefficients. For the time of the earthquake, the Wettzell site data proved strong correlation for all frequency components, while the Bad Homburg site data showed an unexpected decrease of correlation for the majority of frequency components. The authors also showed that wavelet decomposition can be a good method of data interpolation, especially from the time of earthquakes. Moreover, it is a very useful tool for filtering the data and removing the noises., Janusz Bogusz, Anna Klos and Wieslaw Kosek., and Obsahuje bibliografii
Karst landforms can result from a single stage process in which chemical dissolution and mechanical erosion proceed simultaneously or from a two stage process in which chemical dissolution precedes mechanical erosion. During the second of these processes, chemical dissolution leads to the creation of karst features hosting a residual weathering product, here referred to as alterite. An example of one such feature is the enclosed mass of altered rock at Červený Quarry near Klukovice which represents one of the richest localities for exceptionally preserved echinoderm ossicles in the Prague Synform. In this study the processes responsible for the formation of this feature have been investigated. Nineteen samples were obtained from the bioclastic Slivenec Limestone and from these it has been possible to calculate the carbonate volume content, which defines the weathering intensity, and the carbonate rock weathering index, which defines the weathering state. The results demonstrate that carbonate dissolution has not been accompanied by gravitational compaction or the incorporation of mineral inputs. Thin sections analysed under polarised light and under cathodoluminescence emphasise heterogeneous dolomitisation of the limestone. As the weathering grade intensifies, empty rhomboidal pores become increasingly common until, ultimately, the rhomboidal forms are lost due to corrosion and enlargement. In contrast it is rare to find evidence of calcite dissolution and, therefore, the altered mass still hosts almost all of its post dolomitisation micrite, sparite, and bioclasts. Negligible calcite dissolution helps to explain the exceptional nature of the fossil preservation at the site while the dolomite dissolution accounts for the ease with which it is possible to extract the fossils. Further research should focus on better understanding the role of dolomite dissolution in the formation of other important palaeontological localities in the Prague Synform., Matt Rowberry, Caroline Dubois, Olivier Kaufmann, Jean-Marc Baele and Jan Blahůt., and Obsahuje bibliografii
Empirical Mode Decomposition (EMD) is suitable to process the nonlinear and non-stationary time series for filtering noise out to extract the signals. The formal errors are provided along with Global Navigation Satellite System (GNSS) position time series, however, not being considered by the traditional EMD. In this contribution, we proposed a modified approach that called weighted Empirical Mode Decomposition (weighted EMD) to extract signals from GNSS position time series, by constructing the weight factors based on the formal errors. The position time series over the period from 2011 to 2018 of six permanent stations (SCBZ, SCJU, SCMN, HLFY, FJPT, SNXY) were analyzed by weighted EMD, as well as the traditional EMD. The results show that weighted EMD can extract more signals than traditional EMD from original GNSS position time series. Additionally, the fitting errors were reduced 14.52 %, 12.25 % and 8.06 % for North, East and Up components for weighted EMD relative to traditional EMD, respectively. Moreover, 100 simulations of four stations are further carried out to validate the performances of weighted EMD and traditional EMD. The mean Root Mean Squared Errors (RMSEs) are reduced from traditional EMD to weighted EMD with the reductions of 9.08 %, 9.63 % and 6.84 % for East, North and Up components, respectively, which highlights the necessity of considering the formal errors. Therefore, it reasonable to conclude that weighted EMD can extract the signals more than traditional EMD, which can be suggested to analyze GNSS position time series with formal errors., Xiaomeng Qiu, Fengwei Wang, Yunqi Zhou and Shijian Zhou., and Obsahuje bibliografii
Our long-term palaeoecological research on plant and mollusc assemblages in more than 170 isolated fen sites in the Western Carpathians proved a sharp gradient of species turnover spans from west to east, mainly in the distribution of so-called re - lict species, independent of any ecological difference among sites. Fossil evidence and radiocarbon dating evidenced that sites in the outer flysch part (e.g. border area between the Czech and the Slovak Republics) are much younger than those located in the Inner Western Carpathians, host many relict species and have a Holocene continuity. We also confirmed that se - veral presumable relict species are signifi - cantly related to old sites originating from the Pleistocene/Holocene boundary. and Michal Horsák a kol.
The trans-border area of the Sudetes between Žďarky and Pstrążna has attracted Prussian/German, Austrian, Czech and Polish geologists since the middle of the 19th century. The history of mapping of this area reflects the scientific development of geological centres in Berlin, Vienna, Prague and Wrocław. This paper presents a description of the oldest geological maps of Lower Silesia in the context of changing knowledge on the Carboniferous and Cretaceous stratigraphy and on the tectonics of the region. On the basis of DEM and field studies the author presents his own geological map of the area of the Pstrążna Elevation together with a description of the local structural geology. A regional structural model is suggested, that explains all the local elevations as having developed in response to a dextral strike-slip activity of the Žďarky-Jakubowice Fault during late Tertiary to Recent times, at an eastern extension of the Poříčí-Hronov Fault Zone., Jurand Wojewoda., and Obsahuje bibliografii