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National Repository of Grey Literature 3 records found  Search took 0.01 seconds. 
Rozšíření české dubové standardní chronologie o letokruhové křivky ze subfosilních dubových kmenů z Polabí
 Jelínek, Michal
Subfossil trunks are unfossilized woods which are discovered rarely in the Czech Republic. The aim of this work was to find, sampled and dated subfossil trunks from the Polabí region. Available Czech and foreign standard chronologies were used for dendrochronological dating of tree-ring series. Simultaneously, earlier sampled subfossil trunks from the study area were assembled. The chosen tree-ring series were used to extension and improvement of the Czech oak standard chronology. Selected samples, which were not possible to dendochronologically date, were sent for radiocarbon dating. For a purpose of this work, 122 new subfossil findings were dendrochronologically processed from the Polabí region and three samples were prepared and sent for radiocarbon dating. The major part of subfossil trunks was identified as an oak and only 5 samples as an elm. In total, 96 samples were successfully dated mostly into two periods: 3500 - 3200 BC and 133 BC - 155 AD. In Kostomlátky location, the oldest oak subfossil trunk in the Czech republic was found the tree-ring series covers the period 8181 7971 BC. Thanks to these subfossil findings, the Czech oak standard chronology could be extended.
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Srovnání přirozené trvanlivosti a vybraných vlhkostních vlastností dřeva subfosilního dubu s dřevem dubu recentního
 Nevrlý, Ondřej
This work should be used to determine differences between the properties of recent subfossil and oak wood. For this work, there are available samples of four historical periods. The first period is the present, and therefore, these data should be consistent with the literature and serve as well as verifying the accuracy of the procedure and methodology for the acquisition of data. Then there are available subfossil oak samples from three periods, 1131-804 BC., 208 BC. - 137 and after the year 1018th. It was investigated experimentally durability of wood. Samples were subjected to the test of durability against wood--destroying fungi according to EN 113. Used decaying fungi are Trametes versicolor, Laetiporus sulphureus and Poria placenta. Further samples were devided into durability classes according to EN 350--1. It was found that subfossil oak wood resistance to wood--destroying fungi decreased. Furthermore there was investigated selected moisture characteristics and also some other physical properties of oak. Oak wood contains a high amount of tannins, which gives it extremely high durability and resistance. So now we are finding an oak tree trunks which are up to 8,500 years old.
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Analýza variability plochy makrocév na příčném řezu kmenem subfosilního dubu
 Petráš, Michal
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