Can the incorporation of different concentrations of buriti (Mauritia flexuosa) oil change the rheological properties of filmogenic solutions? A factorial experimental design approach

Background: Buriti (Mauritia flexuosa) oil has high economic potential because it contains monounsaturated and polyunsaturated fatty acids with high antioxidant potential and high carotenoid content, making it an excellent source of pro-vitamin A. Objective: The objective of this work was to evaluate the rheological properties of filmogenic solutions incorporated with different buriti oil concentrations. Methods: Buriti oil (0.15 to 0.45 % w/v) and emulsifier (Tween®20) (0.02 to 0.04 % w/v) were combined using a factorial experimental design 22 with 3 central points for the preparation of filmogenic solutions with cassava starch (3%, w/v) and glycerol (0.06%, w/v). Rheological properties, static and centrifugation emulsion stabilities, and pH value of filmogenic solutions were evaluated. Results: Filmogenic solutions with lower emulsifier concentration showed increased flow resistance and non-Newtonian and pseudoplastic behavior (n<1). Central point formulation (E, F, and G) remained stable (no particle agglomeration) throughout the test period as well as pH value close to neutrality. In centrifugation stability index at 3500 rpm, only formulation C did not show phase separation. Conclusion: It was possible to develop a mixture of a filmogenic solution containing buriti oil that could be applied as an eco-friendly coating in food.

A computational fluid dynamics assessment of 3D printed ventilator splitters and restrictors for differential multi-patient ventilation

Background The global pandemic of novel coronavirus (SARS-CoV-2) has led to global shortages of ventilators and accessories. One solution to this problem is to split ventilators between multiple patients, which poses the difficulty of treating two patients with dissimilar ventilation needs. A proposed solution to this problem is the use of 3D-printed flow splitters and restrictors. There is little data available on the reliability of such devices and how the use of different 3D printing methods might affect their performance. Methods We performed flow resistance measurements on 30 different 3D-printed restrictor designs produced using a range of fused deposition modelling and stereolithography printers and materials, from consumer grade printers using polylactic acid filament to professional printers using surgical resin. We compared their performance to novel computational fluid dynamics models driven by empirical ventilator flow rate data. This indicates the ideal performance of a part that matches the computer model. Results The 3D-printed restrictors varied considerably between printers and materials to a sufficient degree that would make them unsafe for clinical use without individual testing. This occurs because the interior surface of the restrictor is rough and has a reduced nominal average diameter when compared to the computer model. However, we have also shown that with careful calibration it is possible to tune the end-inspiratory (tidal) volume by titrating the inspiratory time on the ventilator. Conclusions Computer simulations of differential multi patient ventilation indicate that the use of 3D-printed flow splitters is viable. However, in situ testing indicates that using 3D printers to produce flow restricting orifices is not recommended, as the flow resistance can deviate significantly from expected values depending on the type of printer used. Trial registration Not applicable.