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Abstract: Titanium and its alloys, as well as stainless steel, are commonly used materials for implants in the human body due to their excellent biocompatibility, corrosion resistance, and mechanical properties. However, the long-term performance of these materials in the oral cavity can be affected by the complex oral environment, including the ingestion of food, beverages, and oral hygiene products, leading to the presence of various ions, pH fluctuations, and inflammatory processes. In this study, the corrosion properties of two biocompatible materials, Ti6Al4V and AISI 316L stainless steel, are investigated under varying oral inflammatory conditions. Using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), SEM, and EDS analysis, the corrosion behaviour of both materials was analysed in environments simulating mild and severe inflammation. Results indicate that Ti6Al4V exhibits superior corrosion resistance at low H2O2 concentrations mimicking mild inflammation, with significantly lower corrosion rates compared to AISI 316L. However, at higher H2O2 concentrations, which correspond to severe inflammation, AISI 316L shows better resistance despite its susceptibility to pitting corrosion. Both alloys show reduced passivation after 72 h, with corrosion products accumulating on the surface after 96 h, contributing to repassivation. These results emphasise the need for individualized material selection in dental applications based on a patient’s susceptibility to oral inflammation.
Keywords: corrosion, EIS, inflammatory conditions, titanium, stainless steel, dental materials
Published in DKUM: 19.05.2025; Views: 0; Downloads: 0
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Abstract: The report shows the strong impact of fullerene C60 nanoparticles on phase transitions and complex dynamics of rod-like liquid crystal dodecylcyanobiphenyl (12CB), within the limit of small concentrations. Studies were carried out using broadband dielectric spectroscopy (BDS) via the analysis of temperature dependences of the dielectric constant, the maximum of the primary loss curve, and relaxation times. They revealed a strong impact of nanoparticles, leading to a ~20% change of dielectric constant even at x = 0.05% of C60 fullerene. The application of the derivative-based and distortion-sensitive analysis showed that pretransitional effects dominate in the isotropic liquid phase up to 65 K above the clearing temperature and in the whole Smectic A mesophase. The impact of nanoparticles on the pretransitional anomaly appearance is notable for the smectic–solid phase transition. The fragility-based analysis of relaxation times revealed the universal pattern of its temperature changes, associated with scaling via the “mixed” (“activated” and “critical”) relation. Phase behavior and dynamics of tested systems are discussed within the extended Landau–de Gennes–Ginzburg mesoscopic approach.
Keywords: nanoparticles, liquid crystals, soft materials, fullerenes, dielectric spectroscopy, phase transitions, dynamics
Published in DKUM: 10.03.2025; Views: 0; Downloads: 3
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Abstract: Namen študije je bil ugotoviti protimikrobno učinkovitost hitozanskih nanodelcev v primerjavi s hitozansko raztopino in sled temu njihovo učinkovito rabo na medicinskih tekstilnih materialih.
Keywords: chitosan, nanoparticles, antimicrobial activity, coatings, medical textile materials
Published in DKUM: 07.01.2025; Views: 0; Downloads: 24
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Abstract: Uniform lattices composed of one type of lattice structure repeated periodically have been extensively investigated in literature for their mechanical and physical properties. Their promising properties, which include a desirable combination of high strength, stiffness and toughness, suggest that hybrid structures made of two or more lattice types can exhibit even more advantageous and desired properties. In this work, the mechanical properties of hybrid cellular structures designed using implicit functions are investigated both experimentally and numerically. Two proposed samples are investigated comprised of a Gyroid and a Diamond unit cells hybridised linearly and radially. First, a finite element computational model was utilised in LS-DYNA to capture the mechanical properties of the additively manufactured constituent lattices (i.e., Gyroid and Diamond) made of stainless steel 316L and tested under dynamic and quasi-static loading conditions. The model was validated for three different relative densities. Then, the validated computational model was then tested to predict the mechanical behaviour of the proposed hybrid lattices. Finally, the proposed hybrid lattices were fabricated and mechanically tested to obtain their mechanical properties. A good agreement between experimental and computational results was achieved. The validated computational models will be used to evaluate other designs of TPMS lattices and their crashworthiness performance for protective equipment applications.
Keywords: cellular materials, triply periodical minimal surface, hybrid lattices, experimental testing, computational modelling, multi-morphology
Published in DKUM: 27.11.2024; Views: 3; Downloads: 11
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Abstract: External wall thermal insulation is one of the most effective solutions on the market to increase energy efficiency in the built environment. Off-Site Construction (OSC), through better control of the various parameters involved, can bring important advantages, such as the reduction of construction time, the improvement of product and process quality, etc. In the last years, the rapidly growing demand for thermal insulation systems, stimulated also by tax incentives, has generated a unique situation in Italy compared to the rest of Europe, also leading to a considerable fragmentation of the supply chain with several players involved (component and system manufacturers, distributors, and installers). The complexity of such context makes Italy an extremely challenging and insightful case study for a supply chain and sustainability study, also considering the fact that the energy efficiency of the Italian building stock represents a crucial challenge to achieve the country's energy saving goals since 40% of final energy consumption derives from buildings and 75% of the building stock presents a low energy performance (energy labels E, F and G). This article presents both an analysis of the Italian market of manufacturers of building envelope thermal insulation solutions, highlighting the different players in the supply chain in terms of number, type, and marketed products and solutions, and a focus on sustainable and recycled materials. The study also aims to define a methodology to investigate the state of play and opportunities for industrialisation of this market and its bottlenecks. In the article, a questionnaire is proposed to collect information and opinions on the spread of OSC and the perception of companies and professionals regarding the advantages and disadvantages of industrializing the sector. A first validation of the survey is presented in the form of industrial focus groups.
Keywords: supply chain sustainability, industrial energy efficiency, off-site construction, construction industrialisation, sustainable building materials, modular buildings
Published in DKUM: 01.10.2024; Views: 0; Downloads: 3
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