National Repository of Grey Literature 7 records found  Search took 0.00 seconds. 
Stability of the sodium content in selected botanical reference materials
Kameník, Jan ; Kučera, Jan ; Borovička, Jan ; Havránek, Vladimír
Sodium mass fractions in NIST standard reference materials (SRM) SRM 1547 Peach Leaves and SRM 1515 Apple leaves determined by INAA in our laboratory in recent years has been higher than the certified values. Similarly, increased values were published for SRM 1547 by several other laboratories. The increased Na mass fractions was found also for freshly opened SRM 1547 bottle and for material originating from a different lab. Increased Na mass fractions were confirmed by ICP-MS analysis of both materials. Analysis of archived samples revealed that sodium mass fraction in materials stored in polyethylene capsules is in agreement with the certified values. The sodium content in the glass of SRM 1547 bottle was roughly 10 %. Direct measurement of the Na depth profile by micro-PIXE was not indicative whether Na is released, i.g., by a glass corrosion due to residual humidity in the botanical material. However, a model experiment with freshly prepared and pulverized peach leaves demonstrated that such a scenario is possible for leaf-based materials. Although the study was focused on two NIST materials, the process is possible for any material with rather low Na content.
Geochemical and Ecological Aspects of Trace Elements Content in Macrofungi
Borovička, Jan ; Jelínek, Emil (advisor) ; Hofmeister, Jeňýk (referee) ; Kalač, Pavel (referee)
l.INTRODUCTION Fungi have important biogeochemical roles in the biosphere and are intimately involved in the cycling of elements and transformations of both organic and inorganic substrates (Gadd 2007, Fig. r). The research area of geomycology is focused on the interactions of fungi with geological environment. T^-:-. -'r | ě|ola I I K. <..'---tt-\ \ Organic acid anion Figure l. Proton- and organic acid ligand-mediated dissolution of metals of soils componets and minerals (Gadd 2004). proton release resurts in cation exchange with sorbed metal ions on clay particles, colloids etc. and metal displacement from mineral suďaces. Released metals can interact with biomass and also be taken up by other biota, and react with other environmental components. organic acids anions, e.g. citrate, may cause mineral dissolution or removal by complex formation. Metal complexes can interact with biota as well as environmental constituents. In some circumstances, complex formation may be followed by crystalization, e.g. metal oxalate formation. Many macrofungal species (macromycetes, mushrooms) are capable of accumulating high concentrations of certain trace elements (includini hear,y tr \ \ -=-r Hm Mgt- metals, noble metals and metalloids) in fruit-bodies and thereby affect elemental geochemical cycling. Many studies...
Comprehensive petrological and geochemical study of lunar mare-basalt meteorite Northeast Africa 003 - A
Haloda, Jakub ; Košler, Jan (advisor) ; Borovička, Jan (referee) ; Palme, Herbert (referee)
COMPREHENSIVE PETROLOGICAL AND GEOCHEMICAL STUDY OF LUNAR MARE-BASALT METEORITE NORTHEAST AFRICA 003-A Northeast Africa 003 (NEA 003) is a lunar meteorite found as a two paired stones (6 and 118 g) in Libya in 2000 and 2001. The main portion (~75 vol%) of the 118 g meteorite, used for this study, (NEA 003-A) consists of mare basalt and a smaller adjacent portion (~25 vol%) is a basaltic breccia (NEA 003-B). NEA 003-A has a coarse-grained magmatic texture consisting mainly of olivine, pyroxene and plagioclase. The late-stage mineral association is composed mainly of elongate plagioclase, ilmenite, troilite, fayalite, Si-K-rich glass, apatite and a rare SiO2 phase. Other accessory minerals include ulvöspinel, chromite, and trace Fe-Ni metal. Olivine and pyroxene contain shock-induced fractures, and plagioclase is completely converted into maskelynite. The Fe/Mn values of the whole rock, olivines and pyroxenes, and the bulk-rock oxygen isotopic composition provide evidence for the lunar origin of NEA 003-A meteorite. This is further supported by the presence of Fe-Ni metal and an anhydrous mineral association. NEA 003-A is geochemically and petrographically distinct from previously described mare-basalt meteorites and is not paired with any of them. The petrography and major element composition of NEA...
Interactions of macrofungi and trace elements in soils
Cejpková, Jaroslava ; Borovička, Jan (advisor) ; Gabriel, Jiří (referee) ; Drahota, Petr (referee)
This PhD thesis follows my master's thesis, which I focused on the problem of uranium determination and content in macrofungal fruit-bodies (the results have been published, Appendix 1). Macrofungi apparently do not accumulate uranium in fruit-bodies but as other studies suggested major roles of fungi in environmental geochemistry of uranium, I hypothesized possible accumulation of uranium and other elements in ectomycorrhizae. I therefore decided to continue the research and focus on investigation of trace elements in ectomycorrhizae. As I had opportunity to use a variety of analytical methods, I also participated in other studies in the field geomycology and the results are included in this thesis. In response to alarmist reports in Czech media, I focused on activity and distribution of radiocaesium in fruit-bodies of Boletus badius. As demonstrated in Appendix 2, the fruit- bodies of this species do not represent a health risk for mushroom consumers. Distribution of mycelium of saprotrophic Agaricus bernardii in a soil profile in Prague was investigated by use of molecular methods (PCR with specific primers). The results have shown that the mycelium reaches the depth of 30 cm. Lead isotopic composition of fruit- bodies suggests lead can be accumulated from soil depth of 13-17 cm (Appendix 3)....
Diversity and taxonomy of Steccherinum in the Czech Republic
Geigerová, Tereza ; Koukol, Ondřej (advisor) ; Borovička, Jan (referee)
This thesis deals with geographical distribution and taxonomy of Steccherinum genus in the Czech Republic. Members of this genus are corticioid fungi of Meruliaceae family, characterized by odontioid hymenophore, small spores and encrusted pseudocystidia. Presence of nine species was confirmed in Czech Republic on the basis of herbarium specimen revision and study of my own collections. Analysis of ITS and LSU nrDNA gene regions was used to create phylogenetic trees. These trees show relations in Steccherinum genus and related species. Selected traits in specimens of S. ochraceum s. l. (number of spines, their length, spore size and pseudocystidia size) were measured. This was followed by investigation of morphological variability in individual specimens and in relationship to ecological conditions (substrate and elevation). Morphology of selected individuals was compared with molecular data afterwards. Two clades were defined in S. ochraceum s. l. - existing differences between them are presumably caused by intraspecific genetic variability. S. rhois could not be separated as individual species on the basis of phylogenetic analysis. Dependence of fruiting body morphology on ecological conditions wasn't supported by results. Maps of geographic distribution of individual species of Steccherinum genus are...
Uranium content in macrofungi
Kubrová, Jaroslava ; Borovička, Jan (advisor) ; Řanda, Zdeněk (referee)
In the leading part of this work I presented general information on the kingdom of fungi and fungal ecology focused on marofungi (macromycetes). Furthermore, I reviewed the phenomenon of trace elements accumulation in macrofungal fruit-bodies, particularly focused on uranium and its biogeochemistry. In the experimental part, results of my own research are presented. I determined concentrations of uranium, thorium, silver and lead by use of HR- ICP-MS and ENAA. The macrofungal samples were collected 1/ in clean areas with diverse geological bedrock, 2/ in uranium-polluted area in vicinity of Příbram (Central Bohemia, Czech Republic). Furthermore, selected trace elements were determined also in underlying soils by use of the both analytical methods. For investigation of trace elements mobility, the BCR sequential extraction was applied.

See also: similar author names
1 Borovička, Jaroslav
2 Borovička, Jiří
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