The aim of this study is to perform detail experimental mapping of the lubricating film thickness of bovine serum (BS) within the contact between an artificial metal or ceramic femoral head and a glass disc and analyze effect of proteins on the film formation. Mapping of the lubricating film of various concentrations of BS solutions was carried out using an optical test rig. Chromatic interferograms were recorded with a high-speed digital camera and evaluated with thin film colorimetric interferometry. The film thickness was studied as a function of both time and mean speed. The results showed that film thickness increases with time for both the metal and ceramic heads. Films formed at the end of measurements with the metal head were found to be typically in the range of 60-100 nm for all BS solutions and were independent on the amount of proteins in tested fluids. At the beginning of the speed measurements, BS of all concentrations forms a very thin film (1-2 nm) and its thickness increases with increasing mean speed. However, when the speed was decreased, the film thickness did not reduce but increased with decreasing speeeds that supports the findings of other researchers. Moreover, it was found that BS supply is sensitive parameter. When the lubricant reservoir below tested head was used then the measured central film thicknesses achieved values only about 20 nm, whereas when the tests were realized without the reservoir, measured central film thicknesses achieved higher values about 100 nm. For both types of the experiments, distribution of the film thickness within the contact zone is not homogeneous and two different film thickness regions can be found; thicker protein film and thinner base film that both increase with time and speed. and Obsahuje seznam literatury
The paper is focused on the ethnographic and Slavonic works of Karel Vladislav Zap, Czech geographer, historian and topographer (1812-1872), and his wife, Polish noblewoman Honorata of Wiśniowski-Zap (1825—1856). К. V. Zap, who worked as a state officer in Polish Galicia in 1830s and 1840s, used his stay for collecting ethnographic facts, published in 1844 in the trilogy „The Mirror of Life in Eastern Europe“. His work was extremely critical towards the Polish society, especially nobility; in a part of Czech patriotic society it provoked a negative response and it aroused a discussion, from which Zap came out as a moral winner. After his return to his homeland, Zap founded the magazine Poutník (“Pilgrim”), in which he continued, for a short time, to publish popular texts with ethnographic and Slavistic topics. After that, his interests were driven to topography and archaeology. His wife published, besides some translations from Polish, several ethnographic studies from the region of Polish Galicia; most of them were accepted positively, but her last but one study Pictures from the Life of Huculs, in which she tried to compare folk Galician and Czech cultures, provoked a negative response, though the discussion was rather emotional. In the last years of her life, the author was interested especially in the education of girls.
An empirical research, conducted by the author among university students and the working population in Prague at the beginning of 1999, showed that second person singular address forms are gradually spreading at the expense of second person plural address forms among young Czechs, especially university students. The number of various social groups whose members use second person singular address forms as a mark of fellowship is growing. The confusion and uncertainty in choosing address forms which were observed in the interviewed Czech speakers can also be interpreted as a signal of oncoming changes in address forms usage in contemporary Czech.
Many respondents found it difficult to address persons of their age by second person plural address forms as well as use second person singular forms when addressing (significantly) older people, even when offered second person singular terms by the older speaker. Plural address forms between schoolmates or workmates of the same age are widely perceived as an unnecessary barrier between communication partners. On the other hand, the usage of reciprocal plural address forms in a formal, office environment is unanimously perceived as most appropriate.