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Increase of Belite Clinker Reactivity
Pekárková, Jana ; Fridrichová, Marcela (referee) ; Gazdič, Dominik (advisor)
Bachelor's thesis is focused on possible increase of belite clinker reactivity. Specfically a method of chemical activation was examinated. This method consists in disruption of belite structure due to substitution silicon ions with other ion. It also deals with effect of potassium ions from potassium sulfur and carbon on longterm hydration process of belite clinker, which was burnt in laboratory.
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Content of cesium-137 in forest ecosystem in selected locations
SEBEROVÁ, Pavlína
The human and the whole environment are irradiated from the different sources (natural or artificial). The natural sources of radiation are cosmic and sun rays or the natural radiation of the Earth. The artificial sources mean cyclotrons, X-rays, particle accelerators, nuclear reactors and others. Natural cesium is located very rarely on Earth, but it has many artificial isotopes (for example Cs-137 and Cs-134). The Cs-137 is an artificial isotope produced by human. The first source of the Cs-137 became the nuclear tests and attacks used in the World War Two. In the 1960s (related a study of nuclear weapons) there were found out storing of Cs-137 in the surface soil layers. Even the peaceful use of the nuclear energy could cause the nuclear crash accompanied by a leakage of radioactive substances. The most tragic crash was an explosion of the nuclear power station Chernobyl in Ukraine. That crash contaminated the whole Ukraine and close states, but also Scandinavia. The spread of the Cs-137 depended on the rainfall and the air flow. Human has been affected by the radioactive elements even after the long time since the crash. Forest ecosystem seems to be the place with the largest amount of Cs-137 located. The Cs-137 may get into the human body though food; it has a very long half-time (30ys), it is stored in the top soil layers and through the root system of plants gets into the plants or mushrooms. The aim of this thesis is to determine and compare the content of the Cs-137 in the selected commodities in the forest ecosystem of Šumava using semiconductor gamma spectrometry. The research question was specified: Is the content of the Cs-137 in the selected commodities of the Šumava forest area significantly different? Based on an analysis of literature and consultation with the State Office for Nuclear Safety there were chosen areas, where was the highest fallout of radioactive elements. Therefore I sampled the area called Kvilda, Zadov and Churáňov. Further locations with the commodities of the forest ecosystem are Bavorov, Svinětice and Baranaviči. There are samples of soil, moss, spruce bark, cones and lichen. Not all commodities could be collected in all locations because there were picked in a small area and not all commodities occurred there. To determine the mass activity of the Cs-137 samples I used a semiconductor gamma spectrometry. The obtained spectra were evaluated through software GAMAT. The range of the values of mass activity of the Cs-137 in all samples is between 3-700 Bq.kg-1. The highest activity was measured in soil, where values reached up to 700 Bq.kg-1. High activity was also measured in moss in Kvilda, 513 Bq.kg-1. Samples of spruce bark, cones and lichens have low values activity. It was not reached out the value of 300 Bq.kg-1. Answer to the research question is that contamination of Sumava Cs-137 in selected commodities forest ecosystem is significantly uneven.
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The methodics of plant nutrition and fertilization by potassium
Kunzová, Eva
The methodics inform about situation in plant nutrition and fertilization by potassium on arable soil in Czech Republic. Methodics is found on utilize analytical procedure for determination of content available potassium (Mehlich 3), whose it is possible subsequently use for calculation optimal fertilization.
Fulltext:  PDF
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