The Effect of Ti-6Al-4V Alloy Surface Structure on the Adhesion and Morphology of Unidirectional Freeze-Coated Gelatin

Screen-printing of chitosan and cationised cellulose nanofibril coatings for integration into functional face masks with potential antiviral activity

Masks proved to be necessary protective measure during the COVID-19 pandemic, but they provided a physical barrier rather than inactivating viruses, increasing the risk of cross-infection. In this study, high-molecular weight chitosan and cationised cellulose nanofibrils were screen-printed individually or as a mixture onto the inner surface of the first polypropylene (PP) layer. First, biopolymers were evaluated by various physicochemical methods for their suitability for screen-printing and antiviral activity. Second, the effect of the coatings was evaluated by analysing the morphology, surface chemistry, charge of the modified PP layer, air permeability, water-vapour retention, add-on, contact angle, antiviral activity against the model virus phi6 and cytotoxicity. Finally, the functional PP layers were integrated into face masks, and resulting masks were tested for wettability, air permeability, and viral filtration efficiency (VFE). Air permeability was reduced for modified PP layers (43 % reduction for kat-CNF) and face masks (52 % reduction of kat-CNF layer). The antiviral potential of the modified PP layers against phi6 showed inhibition of 0.08 to 0.97 log (pH 7.5) and cytotoxicity assay showed cell viability above 70 %. VFE of the masks remained the same (~99.9 %), even after applying the biopolymers, confirming that these masks provided high level of protection against viruses.

Influence of Electrolyte Temperature on Morphology and Properties of Composite Anodic Film on Titanium Alloy Ti-10V-2Fe-3Al

In this study, we introduced a novel environmentally-friendly electrolyte consisting of polytetrafluoroethylene (PTFE) nanoparticles and malic acid solution to fabricate composite anodic film on Ti-10V-2Fe-3Al alloy at different electrolyte temperatures. The morphology revealed that the PTFE nanoparticles were successfully incorporated into composite anodic films and embedded preferentially in the pores and cracks. Their performances (wear, corrosion and hydrophobicity) were evaluated via electrochemical tests, ball on disc tests, and a contact angle (CA) meter. Compared to the substrate of titanium alloy Ti-10V-2Fe-3Al, the composite anodic films exhibited the low wear rates, high corrosion resistance and good hydrophobicity. However, the microstructure and morphology of the films were affected by the electrolyte temperature. As a result, their performances were changed greatly as a function of the temperature and the film fabricated at 20 °C exhibited better performances (CA = 131.95, icorr = 6.75 × 10−8 A·cm−2, friction coefficient = 0.14) than those at other electrolyte temperatures. In addition, the corresponding lubrication mechanism of the composite anodic films was discussed.