Jožef Stefan Institute

About: Jožef Stefan Institute is a facility organization based out in Ljubljana, Slovenia. It is known for research contribution in the topics: Liquid crystal & Dielectric. The organization has 3828 authors who have published 12614 publications receiving 291025 citations.

Microstructure and mechanical properties of nanostructured Ti–Al–Si–N coatings deposited by magnetron sputtering

Abstract: Reduction of wear and corrosion, along with increasing thermal stability of tools and mechanical components presents industrial challenges which demand continuous development of new coating materials and coating design concepts. Recently, the main attention has been placed on research and application of multilayer and nanocomposite coatings. In this study, TiAlN and TiSiN layers were alternatively deposited to produce a nanolayered nanocomposite TiAlSiN coating. Single-layer TiAlN and TiSiN coatings were deposited along with the nanolayered coating for better understanding of its properties. All coatings were prepared by sputtering in an industrial unit equipped with four unbalanced magnetron sources (two TiAl and two TiSi). Coating microstructure was analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Chemical and phase compositions were determined by X-ray photoelectron spectroscopy (XPS). Mechanical properties were measured by nanoindentation technique. According to XRD and XPS measurements, nanolayered TiAlSiN coating consists of crystalline fcc-TiN like and amorphous Si3N4 phases. TEM analysis revealed that TiSiN layers block the growth of TiAlN crystallites which are equiaxed and size around 5 nm. As a result, TiAlSiN coating exhibits high hardness (H = 39 GPa) which is attributed to limited dislocation activity in small crystals and suppression of grain boundary sliding.

Arsenic Compounds in Higher Fungi

Abstract: In 50 mushroom species (56 samples) from Slovenia, Switzerland, Brazil, Sweden, The Netherlands and USA, total arsenic was determined by radiochemical neutron activation analysis (RNAA). Arsenic concentrations ranged from 0.1 to 30 μg g−1 (dry mass). Arsenic compounds were determined in methanol extracts from the mushrooms by HPLC–ICP–MS. The aim of the study was not only to quantify arsenic compounds in mushrooms but also to uncover trends relating the methylating ability of a mushroom to its taxonomic or evolutionary status. The main arsenic compound found in many mushrooms (various puffballs, Agaricales and Aphyllophorales) was arsenobetaine. Arsenate [As(V)] was the main arsenic species in Laccaria fraterna and Entoloma rhodopolium and arsenite [As(III)] in Tricholoma sulphureum. A mixture of arsenite and arsenate was present in Amanita caesarea. Dimethylarsinic acid (DMA) and methylarsonic acid were present in many mushrooms, but generally as minor components. In Laccaria laccata, Leucocoprinus badhamii and Volvariella volvacea, DMA was the major metabolite. Arsenocholine (AC) and the tetramethylarsonium ion were present in a few species, generally at low concentrations, except for Sparassis crispa, in which AC was the main compound. Tri- methylarsine oxide was not found in any of the mushrooms. In some species small amounts of unknown compounds were also present. The possible taxonomic significance of the metabolite patterns and the predominance of arsenobetaine in more advanced fungal types are discussed. © 1997 John Wiley & Sons, Ltd.