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Research Commons is the University of Waikato's open access research repository, housing research publications and theses produced by the University's staff and students.
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Publication Designing with biobased composites: understanding digital material perception through semiotic attributes(Journal Article, Cambridge University Press, 2023-03-15)Biobased composites, which are considered a sustainable alternative to plastics, are yet to create a significant influence on product design and manufacturing. A key reason for this is perceptual handicaps associated with biobased composites and this study was aimed at understanding the mechanisms behind biocomposite perception, in the context of digital visuals. This study of digital biocomposite visuals demonstrated that material perception is influenced by the visual characteristics of the material. Data analysis of the perceptual attributes of the materials pointed towards clear ‘clustering’ of the materials against these attributes. Analysis shows that visual features like fibres and surface appearance may impact aesthetic and functional evaluation and there is no effect on age, gender or polymer type. We also propose a reference framework to categorise biobased composites based on visual order.Publication Visual–tactile perception of biobased composites(Journal Article, MDPI, 2023-02-23)Biobased composites offer unique properties in the context of sustainable material production as well as end-of-life disposal, which places them as viable alternatives to fossil-fuel-based materials. However, the large-scale application of these materials in product design is hindered by their perceptual handicaps and understanding the mechanism of biobased composite perception, and its constituents could pave the way to creating commercially successful biobased composites. This study examines the role of bimodal (visual and tactile) sensory evaluation in the formation of biobased composite perception through the Semantic Differential method. It is observed that the biobased composites could be grouped into different clusters based on the dominance and interplay of various senses in perception forming. Attributes such as Natural, Beautiful, and Valuable are seen to correlate with each other positively and are influenced by both visual and tactile characteristics of the biobased composites. Attributes such as Complex, Interesting, and Unusual are also positively correlated but dominated by visual stimuli. The perceptual relationships and components of beauty, naturality, and value and their constituent attributes are identified, along with the visual and tactile characteristics that influence these assessments. Material design leveraging these biobased composite characteristics could lead to the creation of sustainable materials that would be more attractive to designers and consumers.Publication Development of extrudable hydrogels based on carboxymethyl cellulose–gelatin complex coacervates(Journal Article, MDPI, 2025-01-08)This study investigates the 3D extrusion printing of a carboxymethyl cellulose (CMC)–gelatin complex coacervate system. Various CMC–gelatin coacervate hydrogels were prepared and analyzed to achieve this goal. The impact of the CMC–gelatin ratio, pH, and total biopolymer concentration on coacervation formation and rheological properties was evaluated to characterize the printability of the samples. Turbidity results indicated that the molecular interactions between gelatin and CMC biopolymers are significantly pH-dependent, occurring within the range of pH 3.7 to pH 5.6 for the tested compositions. Confocal Laser Scanning Microscopy (CLSM) confirmed the presence of coacervates as spherical particles within the optimal coacervation range. Scanning electron microscopy micrographs supported the CLSM findings, revealing greater porosity within this optimal pH range. Rheological characterization demonstrated that all CMC–gelatin hydrogels exhibited pseudoplastic behavior, with an inverse correlation between increased coacervation and decreased shear viscosity. Additionally, the coacervates displayed lower tackiness compared to gelatin hydrogels, with the maximum tackiness normal force for various CMC–gelatin ratios ranging from 1 to 15 N, notably lower than the 29 N observed for gelatin hydrogels. Mixtures with CMC–gelatin ratios of 1:15 and 1:20 exhibited the best shear recovery behavior, maintaining higher strength after shear load. The maximum strength of the CMC–gelatin coacervate system was found at a biopolymer concentration of 6%. However, lower biopolymer content allowed for consistent extrusion. Importantly, all tested samples were successfully extruded at 22 ± 2 °C, with the 1:15 biopolymer ratio yielding the most consistent printed quality. Our research highlights the promise of the CMC–gelatin coacervate system for 3D printing applications, particularly in areas that demand precise material deposition and adjustable properties.Item Reactive compatibilization of harakeke fiber-reinforced poly(lactic) acid/polybutylene succinate blend(Journal Article, Wiley, 2024-07-20)Different blends of poly(lactic acid) (PLA) and polybutylene succinate (PBS), and their harakeke fiber-reinforced composites were studied. Scanning electron microscopy showed that the PLA and PBS are incompatible and poorly miscible. Tensile strength and tensile modulus of the blends were found to reduce as the amount of PBS increased. Reinforcement alone was not able to significantly improve the mechanical performance of the blend, which is lower than that of neat PLA. Therefore, simultaneous reinforcement and reactive compatibilization were performed using harakeke fiber, and dicumyl peroxide as reinforcement and compatibilizer, respectively. This produced about 201% increase in the crystallinity of PLA. Compared with the PLA/PBS blend, the dual effect approach increased the tensile strength and tensile modulus by 31% and 148%, respectively. Likewise, dynamic mechanical analysis showed that the thermomechanical properties of the composite greatly improved.Item Māori medical student and physician exposure to racism, discrimination, harassment, and bullying(Journal Article, The American Medical Association, 0202-07-01)IMPORTANCE: Discrimination, bullying, and harassment in medicine have been reported internationally, but exposures for Indigenous medical students and physicians, and for racism specifically, remain less examined. OBJECTIVE: To examine the prevalence of racism, discrimination, bullying, and harassment for Māori medical students and physicians in New Zealand and associations with demographic and clinical characteristics. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional study used data from an anonymous national survey of Māori medical students and physicians in New Zealand in late 2021 and early 2022. Data were analyzed from March 2022 to April 2024. EXPOSURES: Age, gender, marginalized status (ie, in addition to being Māori, belonging to other groups traditionally marginalized or underrepresented in medicine), year of medical school, year of graduation, and main work role. MAIN OUTCOMES AND MEASURES: Direct and witnessed racism, discrimination, bullying, and harassment were measured as any experience in the last year and ever. Any exposure to negative comments about social groups and witnessing discriminatory treatment toward Māori patients or whānau (extended family). Considering leaving medicine, including because of mistreatment, was measured. RESULTS: Overall, 205 Māori medical students (median [IQR] age, 23.1 [21.6-24.3] years; 137 [67.2%] women) and 200 physicians (median [IQR] age, 36.6 [30.1-45.3] years; 123 [62.8%] women) responded. Direct and witnessed exposure to racism (184 students [91.5%]; 176 physicians [90.7%]) and discrimination (176 students [85.9%]; 179 physicians [89.5%]) ever in medical education, training, or work environments was common. Ever exposure to witnessed and direct bullying (123 students [66.5%]; 150 physicians [89.3%]) and harassment (73 students [39.5%]; 112 physicians [66.7%]) was also common. Most respondents reported witnessing Māori patients or their whānau being treated badly in clinical settings, in direct interactions (67 students [57.8%]; 112 physicians [58.9%]) or behind their backs (87 students [75.0%]; 138 physicians [72.6%]). One-quarter of Māori medical students (45 students), and 37.0%of physicians (61 physicians) had considered leaving or taken a break from medicine because of these experiences. Additional marginalized statuses were significantly associated with any direct experience of mistreatment in the last year for students and physicians. Exposure to some forms of mistreatment were also significantly associated with higher likelihood of thinking about leaving or taking a break from medicine for physicians. CONCLUSIONS AND RELEVANCE: In this study, Māori medical students and physicians reported high exposure to multiple forms of racism, discrimination, bullying, and harassment in medical education, training, and work environments, requiring an urgent response from medical institutions.
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