The Seljuks, who came from the Central Asian prairies, invaded Asia Minor towards the end of the 11th century. The land had been settled by then mainly by the Christian Eastern Romans and Armenian peoples. Seljuks were Moslems; they built monumental structures, some of which have survived the natural disasters of several centuries to the present day. Most of these architectural marvels contain extraordinary decorations in the form of ornaments, friezes and rosettes. I have studied periodic ornaments and classified them into 17 mathematical wallpaper groups according to their symmetry properties that reveal their global structure. On the other hand, the local details of the ornaments, the motifs, show a clear variation from simple geometric patterns to complicated and refined forms. Seljuk art was originally influenced by Persian styles, later influenced by the Christian population in Asia Minor, and finally represents the impact of Islamic culture.

The paper presents the measured values of tensile forces acting on transmission idlers in the upper and lower run of a conveyor belt placed on a laboratory machine designed at the Department of Machine and Industrial Design, Faculty of Mechanical Engineering, VSB-Technical University of Ostrava). The tensile forces detected by two strain gauge load cells and recorded using DEWESoft software were used to calculate the friction coefficient which acts on the surface of the driving drum casing and the conveyor belt. The friction coefficient at the slip point, or during the slippage of the conveyor belt on the rubber or steel casing of the driving drum was determined for two states of the surfaces which are in contact. Experimental measurements on a laboratory machine determined four values of friction coefficients, for two types of drum surfaces and for two states of contact surfaces, which were compared with the recommended standard values. The measured values reached higher values in comparison with the values given by the CSN standards. The highest deviation of 273.3% is achieved using a steel wet surface, and the lowest deviation of 106.3% is achieved when using a rubber dry lining for the driving drum casing. On the presented laboratory machine, it is possible to measure tensile forces for different speeds of movement, different belt angles on the driving drum, various types of belt surfaces, different types of drum casing linings and different sizes of tension forces for the endless loop of the conveyor belt. For these characteristics of the conveyor belt, the magnitude of the friction coefficient, acting between the belt and the drum surfaces, can be determined.

This comprehensive review is devoted to an under-exploited family of phenolic compounds, the coumarins, and the most relevant strands in which they are involved in some spirit beverages – wine spirit, brandy, whiskey, sugar cane spirits (rum and cachaça) and grape marc spirit – with great importance worldwide in terms of production, trade and consumption. It gathers the key discoveries on the topic considering the production process of each spirit beverage, the related sources of coumarins (different kinds of wood used in the ageing stage) along with the factors that govern them and can influence the sensory properties of the aged beverages. An overview of the analytical methods available for their identification/quantification is also included, as well as the corresponding trends for the advancement of knowledge in this field. Moreover, the remarkable role of coumarins as nutraceuticals, their importance as chemical markers for authenticity purposes, and their relationship with food safety of these spirit beverages are also addressed, highlighting the current gaps and issues, and providing clues for future research.