Doc. dr. Andraž Kocjan with his departmental colleague, Dr. Nataša Drnovšek, who has joined the programme group in 2018, and in collaboration with Ustna Medicina d.o.o. (Dr. Sebastjan Perko), biggest private Slovenian dental clinic, have developed a novel, next generation bioactive sealer for endodontic treatment of teeth, described in technical innovation. They improved bioactive, rheological (handling) and chemical properties of the sealer that is based on mineral trioxide aggregate (MTA) and that has been in use for over 20 years but has according to clinicians still many deficiencies. Close collaboration between the dental clinic (company) and scientists conducting the translational medicine and, thus, implementing knowledge from both, materials science and dental medicine, that resulted in improved technology and more efficient implementation. Better flowability, bioactivity and shorter setting time together with radio-opacity were achieved by studying the influence of particle size, composition, and by the addition of submicron sized bioactive component, clay-like material and zirconia radio-opaque filler. We are now in the final stages of establishing a spin-out company, Genuine Technologies, that will be based on the licensed knowledge from Jožef Stefan Institute. Technology that provides more successful treatment will be therefore opened for pacients.
F.19 Knowledge that leads to a company spin off
COBISS.SI-ID: 30665255Low-temperature degradation is a major limiting factor in wider implementation of zirconia ceramics-based biomaterials in medicine and dentistry. In this doctoral dissertation, uncertainties regarding proper handling and preparation were assessed using a combination of rigorous, accelerated ageing procedures and clinical trials of ageing 'in vivo'. By manipulating sintering temperatures and airborne-particle abrasion protocols, crucial new information on the mechanistic principles of vulnerability towards ageing was uncovered. Grain size and microstructural changes in the immediate subsurface were shown to affect the interplay between moisture- and stress-induced phase transformation, indicating that caution is needed when preparing novel, fine-grained materials with improved translucency. A groundbreaking clinical trial exposed zirconia ceramics to the adverse environment of the oral cavity and was the first to demonstrate the extent of ageing of polished and airborn-particle abraded surfaces. The results received widespread attention at international meetings and resulted in two publications in a leading journal for dental materials, i.e., Dental Materials.
F.02 Acquisition of new scientific knowledge
COBISS.SI-ID: 33350105We report on an alternative high heat flux ceramic material capable of withstanding the demanding environment in a fusion reactor. The focus was on the development of a fine-grained cemented carbide with a low-activation binder phase as a possible armour material for high thermally loaded parts in the fusion reactor, e.g. in divertor. Special effort is taken to replace Co and Ni in the binder alloy with low-activation alloying elements (Cr, Fe, W, V, Ta), or with high entropy alloys, while carefully controlling the carbon balance to retain desired stoichiometry of the carbide phase. We showed that binderless tungsten carbide (WC) can be prepared by spark plasma sintering (SPS) at 1900 °C, 5 min of holding time and applied pressure of 60 MPa. To prevent the formation of undesired W2C phase, at least 2 vol% of graphene flakes have to be added to the starting WC powder. If using nanosized WC powders densities higher than 95 % of theoretical density can be achieved. Such material also exhibits high hardness (HV/100 is 24.3 GPa).
F.09 Development of a new technological process or technology
COBISS.SI-ID: 31078183In an invited lecture, Asst. prof. Andraž Kocjan has presented knowledge attained through several years of interdiscplinary programme research about the complexity of the relationships between microstructure, ageing and mechanical properties of 3Y-TZP ceramics. He showed that t–m transformation not only depends on factors such as grain size and yttrium concentration but also on the internal residual stresses that evolve during sintering-related phase-partitioning and during mechanical (airborne-particle abrasion) and thermal (annealing) handling procedures, as encountered in everyday dental laboratory processing of 3Y-TZP. He also showed how unique microstructures, addressing the conflicting demand for fabricating ageing resistant, but still, mechanically robust 3Y-TZP ceramics can be obtained by colloidal processing and (rapid) sintering of mesoporous 3Y-TZP powder or by co-doping of commercially available, CAD/CAM machinable 3Y-TZP pre-sintered blanks.
B.04 Guest lecture
COBISS.SI-ID: 30884903The authors of the exhibition presented insight into micro and nano world through explaination of the various techniques and image formation in electron microscopes. The exhibition presented graphic aspects of electron microscopy through combination of analytical techniques, using most advanced and sophisticated state-of-the-art equipment. Through this exhibition we would like to try to present years of experience in the field of electron microscopy, arising from a number of research institutes in city of Ljubljana. A series of images from biological, technical and industrial fields is overcoming the utilitarian and documentary function of microscopy, allowing the viewer an insight into the world, unnoticeable with only naked eye. The inconspicuous world is built by seemingly chaotic, but logical and geometric elements with its breath-taking aesthetic appearance.
F.28 Organising an exhibition
COBISS.SI-ID: 30786599