The use of atomic force microscopy for imaging the surfaces of polyamide, 6

The surface morphologies of PA 6 resulting from the use of various processing methods were studied by tapping mode atomic force microscopy. Three PA 6 samples: (1) a thin film, spin coated on a silicon wafer, (2) a freestanding film, i.e. a foil and (3) a monofilament, show definite morphological differences revealing typical supramolecular structures. The thin film having thickness of app. 35 nm is a good example of the initial step of spherulite formation where the sheaf development is still prominent. In an area of 100 μm² 1-4 spherulites can be detected which are typical of crystallization from the solution. The annealing (vacuum, 195°C, 3.5h) causes additional crystallization, which leads to a radial coordination and enlargement of spherulites to app. 50% in diameter and up to 40% in height. The morphology of foil (thickness of 100 μm) can be interpreted as a system of spherulites formed from the melt, and a typical fibrillar structure is observed on the surface of monofilament.     

60 years of OR in Slovenia: development from a first conference to a vibrant community

The paper provides a short history of the operations research (OR) in Slovenia. Some major events and achievements are mentioned and briefly discussed. The period starts in the year 1964, with the first symposium on OR in Slovenia. In the following decades, there were several important milestones: (1) the start of master’s and Ph.D. studies in OR in 1974, (2) the establishment of SSI-SSOR in 1992 (SSI-SSOR stands for the Slovenian Section for Operational Research within the Slovenian Society of Informatics), and (3) the start of a series of symposia in operations research in 1993. All these activities resulted in an extensive list of publications, projects, and monographs and international connections, proving that OR is still a vibrant field, which facilitates knowledge transfer from pure research to business applications.