ABSTRACT
A vitrectome is a commonly used instrument in eye surgery, which is used to cut and aspirate the vitreous body out of the eye. The mechanism of the vitrectome consists of miniature components that need to be assembled by hand due to their size. Non-assembly 3D printing, in which fully functional mechanisms can be produced in a single production step, can help create a more streamlined production process. We propose a vitrectome design based on a dual-diaphragm mechanism, which can be produced with minimal assembly steps using PolyJet printing. Two different diaphragm designs were tested to fulfill the requirements of the mechanism: a homogenous design based on 'digital' materials and a design using an ortho-planar spring. Both designs were able to fulfill the required displacement for the mechanism of 0.8 mm, as well as cutting forces of at least 8 N. The requirements for the cutting speed of the mechanism of 8000 RPM were not fulfilled by both designs, since the viscoelastic nature of the PolyJet materials resulted in a slow response time. The proposed mechanism does show promise to be used in vitrectomy; however, we suggest that more research into different design directions is required.
ABSTRACT
In this study the potential of employing CO2 drying as an alternative to conventional drying techniques of basil was evaluated, with the aim of preservation of native bioactive and sensory properties of basil. For that purpose, optimal CO2 processing conditions were established and compared to air-dried and freeze dried basil samples. The contents of bioactive compounds (polyphenols, chlorophylls, ascorbic acid) and antioxidant capacity were determined spectrophotometrically and using high performance liquid chromatography (HPLC-PDA) analysis. Color analysis and essential oil content were also determined, while consumer evaluation of sensory properties was conducted using hedonic scale preference analysis. According to the obtained results, freeze drying was recognized as the most suitable technique for preservation of color, essential oil content, bioactive compounds and antioxidant capacity of basil. The essential oil content of basil ranged from 0.21 to 0.96%, and decreased upon prolongation of CO2 drying time. Among 4 identified phenolic acids (rosmarinic, chicoric, caftaric and caffeic), rosmarinic acid was the most abundant in all samples. Longer CO2 drying duration (4h) also exhibited the most detrimental effect on the polyphenolic compound content and antioxidant capacity of basil. The taste and appearance of CO2 dried basil were scored higher in comparison to air-dried basil, but further optimization of CO2 drying is needed to improve its aroma properties. Based on the obtained results, employing shorter CO2 drying time (2, 3h) and pressures of 80-100bar at 40°C might be a good alternative to freeze drying of basil.