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- Author or Editor: M. Varga x
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Abstract
Electrodeposited 226Ra sources were prepared and measured in order to perform a detailed study of the energy resolutions attained with two recent electrodeposition procedures for preparing spectrometric radium sources. The values of the energy resolution for the high-energy emission of 226Ra and for the single-emissions of 210Poand 222Rn were calculated by fitting the data with a curve formed by the convolution of two left-handed exponentials with a Gaussian function. Significant differences between the energy resolutions for the aforementioned radionuclides were observed. The 210Po energy resolutions were, in general, somewhat better than those obtained for 226Ra. On the contrary, the energy resolutions found for 222Rn were notably poorer than those obtained for 226Ra and 210Po. These discrepancies can be satisfactorily explained by taking into consideration the distribution of these nuclides in the sources and the effect of radon diffusion involved in this type of thin deposit.
The present study was carried out at a dune slack meadow near Mórahalom town in the Southern part of the Great Hungarian Plain. The area of the grassland is approximately 840,000 m 2 . The vegetation is mosaic-like in accordance with the variable microrelief and water content. The lower part of the grassland consists of various types of saltmarshes and wet meadows and at the upper microrelief, Pannonic sand steppe patches occur. True bug assemblages were sampled at 16 patches using 5×50 sweeps at each sampling site. The sampling was repeated three times in both 2007 and 2008. The area, the perimeter, the shape index of the sampled patches as well as the diversity of the surrounding patches were assessed as “landscape parameters”. The plant species number and diversity of the sampled patches were estimated from the data of 5×5 m coenological quadrats. Altogether 66,087 adult individuals belonging to 153 species were collected. The ordination methods showed that the true bug assemblages of the sampling patches differ from each other in accordance with the vegetation type. These assemblages differed in their species composition and diversity as well as in their assemblage structure. The results suggested that the vegetation type based on plant species composition determined the true bug assemblages.
Abstract
The energy distribution of the alpha particles emitted from a source is in general complex. Only under particular circumstances, as in the case of very thin sources measured at large distances from the detector, can the energy distribution be approximated theoretically. In this work, we used the well-known code SRIM to simulate the interaction of alpha particles within a thin radioactive source and within the entrance window of a typical Si semiconductor detector. We considered several thin alpha particle sources measured at a large source-to-detector distance (small solid angle), in order to compare the distributions obtained by simulation with those determined by the theoretical model applied to this case. The study was performed for a variety of realistic alpha particle sources: UF4, UO2, U3O8, Gd2O3, and BaSO4, considering as alpha emitters 235U, 233U, 148Gd and 226Ra. For all these cases, we obtained the distributions due to the source and due to the entrance window of the detector, and also the final distribution given by the convolution of these two distributions. All the energy distributions obtained by simulation showed, in general, good agreement with the predictions given by the theoretical model, which includes corrections for Bohr straggling.
Abstract
A method has been developed for determining silicon in aluminium by fast neutron activation. It is based on the separation of two gamma lines by a Ge(Li) detector: the 1.73 MeV line from the product of27Al(n, α)24Na and the 1.78 MeV line from the28Si(n, p)28Al reaction. In the case of aluminium-silicon alloys 100 μg silicon can be determined, with an error of 10% in an aluminium sample of 1 g.
Fermented milk products, for example yoghurts contain less lactose than the ordinary milk, however, this quantity of lactose can cause lactose intolerance. The aim of the work was to produce lactose free fermented milk products based on the lactose hydrolysed milk. Products were fermented with Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus (N 71) and Bifidobacterium bifidum (N 1), Lactobacillus helveticus (N 43), Lactobacillus acidophilus (N 42).The growth characteristics, the acidity, the most important aroma productivity and the lactose content were measured. Products were evaluated with organoleptical test. Products were lactose free, so they are suitable for people suffering from lactose intolerance. There were differences among the acid content at the end of fermentation. In case of normal yoghurt culture acid content was 29.6 SH° and in case of probiotic cultures 30.4 SH° and 37.5 SH°, respectively. According to the results of sensory evaluation, the product made with traditional yoghurt bacteria (Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus)was better than products made with probiotic species because of the higher alcohol and lower acetic acid content.
