The article presents an experimental investigation of the rheological properties of carbomer microgels. All of the tested fluids were made up from commercial polyacrylic acid, Carbopol Ultrez 30. In total, eighteen microgels were prepared, differing in concentration; 0.2, 0.4 and 0.6 wt%, with six levels of neutralisation for pH from 4.0 to 9.0. Based on the experimental flow curves it was found that all tested microgels are yield stress shear-thinning fluids. Therefore, the Herschel–Bulkley model was used and its rheological parameters were determined. It was found that both the concentration and the pH value significantly affected the yield stress. As the Carbopol concentration increased, the yield point also increased. With the increasing value of pH, the yield stress first increased until a certain maximum level and then decreased. The maximum values of yield stress were obtained for pH = 6 to 7, depending on polymer concentration. It was also found that flow curves of the tested microgels could be described using one universal master curve, thus they have common rheological behaviour.
One of the fundamental problems in evolutionary sciences is the direction of evolution at different levels of matter organization. According to traditional teleological interpretations, the evolving systems should develop toward a final state—a goal. However, in most cases such a goal is not determinable—scientists do not know it. However, they can reveal a general tendency or a series of changes in time: a teleonomy or a directness based mainly upon an internal pattern of the evolving system although modified also by external influences. Teleonomical processes are responsible for all evolutionary processes including transitions from one level of organization to another.
The article is devoted to the late Zygmunt Bauman (d. January 2017), a scholar who made an enormous impact on world humanities at the turn of the twentieth century. It briefly presents Bauman’s life and a number of the best known concepts from his works. The author first discusses Bauman’s attitude toward Marxist theory and explains his revision of it. He then introduces the main ideas of Bauman work Modernity and the Holocaust. The article ends with a review of Bauman’s reflections on globalisation and a discussion of his thesis concerning the crisis of the nation state.