The absorption coefficient of Bi12TiO20:Rh single crystals is measured in the spectral region 600-950 nm. The oscillator strength f and the transition moment of the impurity band Q are calculated in the near infrared spectral region. The effective mass of doped single crystal has been determined also.
Nikolay Natchev, Zahari Petkov, Georgi Dashev, Ivanka Atanasova and Nesho Chipev
Within the scope of the present study a field survey in the area of “Strandzha” Natural Park in south-east Bulgaria was carried out. The main goal of the investigation was to gain more detailed information on the diet of the European otters (Lutra lutra) that inhabit the park. As indicators for the presence of the mustelids a set of standard procedures, such as footprints tracking and inspecting the terrain for otter spraints were used. A total of 204 excrements were found, measured, documented and then disintegrated in water. The food rests in the faeces were investigated and the diet of the local population was documented. On the base of the results we separated the excrements into six groups and analysed the relations between the contents of the spraints and the characteristics of the habitat where they were found. We discovered a clear tendency toward piscivory in the middle and down streams of the studied rivers in the Natural Park. In the upper streams, otters relied almost exclusively on invertebrates like bivalves and crayfish as food source. The fact, that even suboptimal habitats, which offered invariable menu, were exploited by the otters is an indication for the stability of the local population.
Bulgaria is one of the European countries with the greatest biodiversity, including biodiversity of medicinal plants. The object of this study is Chepan Mountain. It is located in Western Bulgaria and it is part of Balkan Mountain. On the territory of the Chepan Mountain (only 80 km2) we found 344 species of medicinal plants from 237 genera and 83 families. The floristic analysis indicates, that the most of the families and the genera are represented by a small number of inferior taxa. The hemicryptophytes dominate among the life forms with 49.71%. The biological types are represented mainly by perennial herbaceous plants (60.47%). There are 7 types of floristic elements divided in 27 groups. The largest percentage of species are of the European type (58.43%). Among the medicinal plants, there are two Balkan endemic species and 18 relic species. We described 23 species with protection statute. The anthropophytes among the medicinal plants are 220 species (63.95%).
The Frangensko Plateau is located in the northeastern part of Bulgaria and covers an area of 360 km2. On the territory of the plateau there are two protected areas, as well as two areas of the European ecological network NATURA 2000. The study of the medicinal plants on the territory of the Frangensko Plateau is made for the first time. As a result of our research we found 362 species of vascular plants from 242 genera and 80 families. The most of the families and the genera are represented by a small number of inferior taxa. The analysis of their life form indicates that the hemicryptophytes dominate with 39.50%, followed by the phanerophytes (22.10%). The biological types are represented mainly by perennial herbaceous plants (52.21%), annual herbaceous plants (14.09%) and trees (10.50%). There are 8 types of floristic elements divided in 32 groups. The largest percentage of species is of European type (51.93%). Among the medicinal plants, there are two Balkan endemic species, one Bulgarian endemic species and 30 relic species. Thirty four species with protection statute are described. The anthropophytes among the medicinal plants are 242 species (66.85%).
Zheni Nanova, Asya Dragoeva, Vanya Koleva, Nesho Chipev, Borislav Georgiev, Irina Yotova and Milen Ivanov
In contemporary society various demographic factors lead to changes of people habits to use medicinal plants. A matter of interest is to establish how specific demographic features of people influence the use of herbs. The present survey aimed at determining the current trends regarding the use of four valuable medicinal Lamiaceae species in Bulgaria: thyme, mint, lemon balm and oregano. In the survey, 220 people were interviewed. Demographic profiles of the respondents were evaluated. Then the participants were questioned for the following item: “Do you use any of these herbs: thyme, mint, lemon balm and oregano.” In order to disclose correlations between demographic features of the participants and their answers cross-relationships were analyzed. The majority of respondents reported to use these plants. Mint and thyme were more commonly used herbs. We identified that age of respondents had sufficient influence on the answer to the questionary. Level of education and living regions had moderate impact on the use of relatively lesser utilized herbs – oregano and lemon balm. The analysis showed the persistence of traditional knowledge for these plants. At the same time, the results revealed better knowledge on medicinal plants in groups of better educated people and in urban population.
Peatland cores provide us with the potential to research aspects of atmospheric cycling of elements, such as metal pollutants, on timescales. Our study provides a better understanding of basic peat properties and their effects on trace and major element distributions in peat and its humic substances (HS). Humic substances isolated from an ombrotrophic bog peat profiles (Latvia) were used as study objects. Relations among peat depth, properties of peat and its HS (elemental composition), as well as element content, were studied.