Engineering: Journal Articles
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Item Open Access The Rationale for a Standardized Testing Protocol for Anion Exchange Membrane Water Electrolyzers(American Chemical Society (ACS), 2024) Titheridge , L. J.; Marshall, AaronHydrogen production by water electrolysis is an area of growing interest, especially when coupled to intermittent renewable energy generation. The green hydrogen produced is a versatile energy carrier and is essential for industrial decarbonization, playing a critical role in sectors where direct electrification is challenging. Among the different water electrolysis technologies, anion exchange membrane water electrolysis (AEMWE) is seen as especially attractive as it combines many of the positive features from both proton exchange membrane (PEM) and alkaline electrolysis. Specifically, by using an ion-conductive membrane as the electrode separator, AEMWE can be paired with variable renewable energy sources (similar to PEM).Item Open Access Indigenous people display lower mental illness stigma in Aotearoa(SAGE Publications, 2025) Jamieson , Isaac; Winter, Taylor; Mason , Andre; Fehoko , Edmond; Arahanga-Doyle , Hitaua; Fox , Ririwai; Scarf , DamianBackground: Mental illness stigma continues to be pervasive and problematic in society. Researchers have attempted to better understand this stigma through investigations into demographic factors that may predict stigma, focusing on factors such as age, ethnicity and education. Method: We investigated demographic factors in the context of Aotearoa New Zealand, with a particular focus on Māori, the Indigenous people of Aotearoa. We used data from the Health Promotion Agency, which collected representative samples from Aotearoa across three survey waves (total n = 3518). Assessment instruments were the Mental Health Knowledge Scale (MAKS), the Reported and Intended Behaviour Scale (RIBS) and the Community Mental Health Ideology subscale of the Community Attitudes towards the Mentally Ill (CAMI). Using linear mixed-effects model we controlled for several demographic variables (e.g. age, biological sex, education and socioeconomic status) and additional variables (e.g. having a psychological condition and whether participants knew someone with mental illness) across three models for each measure. Results: The results revealed that mental illness stigma was lower among both Māori and European participants. Additional variables and their associations with mental illness stigma are also discussed. Conclusion: Overall, this study illustrates mental illness stigma as lower among Indigenous people in Aotearoa, which prompts further research into ethnicity and mental illness stigma as well as non-Western understandings of mental illness.Item Open Access Jointly estimating epidemiological dynamics of Covid-19 from case and wastewater data in Aotearoa New Zealand(Springer Science and Business Media LLC, 2024) Watson, Leighton; Plank, Michael; Armstrong , Bridget A.; Chapman , Joanne R.; Hewitt , Joanne; Morris , Helen; Orsi , Alvaro; Bunce , Michael; Donnelly , Christl A.; Steyn , NicholasBackground: Timely and informed public health responses to infectious diseases such as COVID-19 necessitate reliable information about infection dynamics. The case ascertainment rate (CAR), the proportion of infections that are reported as cases, is typically much less than one and varies with testing practices and behaviours, making reported cases unreliable as the sole source of data. The concentration of viral RNA in wastewater samples provides an alternate measure of infection prevalence that is not affected by clinical testing, healthcare-seeking behaviour or access to care. Methods: We construct a state-space model with observed data of levels of SARS-CoV-2 in wastewater and reported case incidence and estimate the hidden states of the effective reproduction number, R, and CAR using sequential Monte Carlo methods. Results: We analyse data from 1 January 2022 to 31 March 2023 from Aotearoa New Zealand. Our model estimates that R peaks at 2.76 (95% CrI 2.20, 3.83) around 18 February 2022 and the CAR peaks around 12 March 2022. We calculate that New Zealand’s second Omicron wave in July 2022 is similar in size to the first, despite fewer reported cases. We estimate that the CAR in the BA.5 Omicron wave in July 2022 is approximately 50% lower than in the BA.1/BA.2 Omicron wave in March 2022. Conclusions: Estimating R, CAR, and cumulative number of infections provides useful information for planning public health responses and understanding the state of immunity in the population. This model is a useful disease surveillance tool, improving situational awareness of infectious disease dynamics in real-time.Item Open Access 3D Material Property Tomographic Reconstruction Using Near- Field Phase Retrieval for Dual-Energy Synchrotron X-ray Imaging(2024) Li, Heyang; Morgan, Kaye S.; Kitchen, Marcus J.Item Open Access Quantitative functional assessment of multidirectional upper limb strength for individuals in a seated position(Elsevier BV, 2023) Stilwell, George; Symons, Digby; Gooch, Shayne; Dunn, JenniferUnderstanding the limitations that are imposed by a disability is critical to ensure engineers develop designs that can be used by people with reduced function. Current literature lacks detail on this information for people with cervical spinal cord injuries. The purpose of this study was to investigate the reliability of a novel testing methodology to quantitatively assess the multi-directional upper limb strength of individuals in a seated position. Eleven non-disabled males and 10 males with a C4–C7 spinal cord injury completed isometric strength tests on parasagittal (XY) planes using a novel method. Multidirectional (XY) force measurements were taken at discrete points within the participant's reach envelope. Isometric force trends and analysis of the coefficients of variation were used to evaluate the novel methodology. The isometric force trends were consistent in showing a reduction in strength for people with higher injury levels. Analysis of the coefficient of variation showed that the methodology produces repeatable results with an average coefficient of variation of 18% and 19% for the right and left upper limbs, respectively. These results show that the novel testing methodology is a reliable way to gather quantitative multidirectional upper limb strength data for individuals in a seated position.Item Open Access Comparison of multidirectional upper limb strength for non-disabled individuals and individuals with C4–C7 spinal cord injury in a seated position(Informa UK Limited, 2024) Stilwell, George; Symons, Digby; Gooch , Shayne; Dunn , JenniferThis study investigates the multidirectional upper limb strength of individuals with a C4–C7 spinal cord injury (SCI) and non-disabled individuals in a seated position by measuring multidirectional force at the hand. Current literature lacks quantitative strength data to evaluate strength requirements for people who have reduced upper limb function due to a cervical SCI. Seated multidirectional force measurements were recorded for eleven non-disabled and ten males with a C4–C7 SCI. Collected data was displayed using detailed force polar plots. The resulting plots revealed a clear difference in polar plot shape for non-disabled participants and participants with a C4–C7 SCI. Namely that SCI participants had more elliptical polar plots due to reductions in circumferential strength compared to non-disabled participants. However, the polar plots for higher SCIs tended to have an increasingly more circular shape. The results provide insight into the differences in strength between people with cervical SCI and no disability.Item Open Access An improved collection method of high-resolution pavement images and deep learning models for pavement distress detection(2024) Li, Heyang; Todd, Zachary; van der Walt, Jacobus Daniel; Saleh, MofrehThe condition of roads is crucial for both user comfort and safety, and regular maintenance and inspections are necessary to identify and repair pavement distress. This paper presents a new approach to collect high-resolution pavement distress data and deep learning models to detect and classify pavement distress accurately. The study aims to achieve two main objectives. Firstly, to enhance image quality and consistency in collecting high-resolution pavement distress data a common limitation of previous research. Secondly, to develop and compare deep learning models that can accurately detect and classify pavement distress.To accomplish the first objective, a custom data collection apparatus is designed that captures only the relevant portion of the pavement surface and minimizes irrelevant details. The study utilizes two datasets to make a comparison, RDD2020, which is a publicly available dataset with pavement distress images, and EV22, a dataset collected using our own custom apparatus.To achieve the second objective, the study utilizes three state-of-the-art deep learning models, namely Mask R-CNN, Cascade Mask R-CNN, and Hybrid Task Cascade. These models are trainedand tested on both the RDD2020 and EV22 datasets, and their performance is evaluated using metrics such as precision, recall, F1 score, and IoU. The results indicate that the approach is effective. The EV22 dataset has higher image quality and consistency, with a larger proportion of relevant pavement area in the images compared to RDD2020. In terms of pavement distress detection, all three deep-learning models outperformed RDD2020.Item Open Access Overcoming Fundamental Limitations in Adsorbent Design: Alkene Adsorption by Non-porous Copper(I) Complexes(Wiley, 2020) Parasar D; Elashkar AH; Yakovenko AA; Jayaratna NB; Edwards BL; Telfer SG; Dias HVR; Cowan, Matthew GreigPurifying alkenes from alkanes requires cryogenic distillation. This consumes energy equivalent to countries of ca. 5 million people. Replacing distillation with adsorption processes would significantly increase energy efficiency. Trade-offs between kinetics, selectivity, capacity, and heat of adsorption have prevented production of an optimal adsorbent. We report adsorbents that overcome these trade-offs. [Cu-Br]3 and [Cu-H]3 are air-stable trinuclear complexes that undergo reversible solid-state inter-molecular rearrangements to produce dinuclear [Cu-Br⋅(alkene)]2 and [Cu-H⋅(alkene)]2. The reversible solid-state rearrangement, confirmed in situ using powder X-ray diffraction, allows adsorbent design trade-offs to be overcome, coupling low heat of adsorption (−10 to −17 kJ mol−1alkene), high alkene:alkane selectivity (47; 29), and uptake capacity (>2.5 molalkene mol−1Cu3). Most remarkably, [Cu-H]3 displays fast uptake and regenerates capacity within 10 minutes.Item Open Access Quantitative analysis using external standards with a benchtop NMR spectrometer(Elsevier BV, 2020) Lee Y; Matviychuk, Yevgen; Holland, DanielThis paper investigates the use of benchtop NMR spectrometers for quantitative analysis with external standards. Specifically, it focuses on the measurement of aqueous samples with analyte concentrations ranging from 30 mM to 1.7 M and electrical conductivity of up to 84mScm-1 using a 43 MHz instrument. It is demonstrated that measurements using the PULCON method cannot achieve an average error in quantification of <4% with the benchtop NMR tested here unless the standard and analyte are very similar. Our analysis indicates that this comparatively large error arises from the fixed tuning and matching of the benchtop spectrometer. We confirm that for moderately dilute samples (less than 0.2 M), the integral area of the solvent peak is suitable for use as an internal standard to mitigate this error. Furthermore, a round robin study demonstrates that the second major source of uncertainty in these measurements arises from the manual processing of the spectra by different analysts. Here we propose heuristics for manual baseline and phase correction to reduce this analyst-dependent error to about 3 %. We also demonstrate that semi-automated quantification using qGSD is able to achieve similar accuracy of integration, but with reduced sensitivity to the processing of the operator.Item Open Access The Brauer-Manin obstruction for nonisotrivial curves over global function fields(2023) Creutz, Brendan; Voloch, JoseWe prove that the set of rational points on a nonisotrivial curves of genus at least 2 over a global function field is equal to the set of adelic points cut out by the Brauer-Manin obstruction.Item Open Access Use of limit state loss versus intensity models for simplified estimation of expected annual loss(TAYLOR & FRANCIS LTD, 2016) SULLIVAN, TIMOTHYThe expected annual monetary loss (EAL) is a powerful seismic performance indicator for a building as it quantifies repair and replacement costs considering a wide range of possible earthquake scenarios. Existing methods for the estimation of EAL are admirably rigorous but also represent a significant departure from current code assessment methods. By introducing simple loss vs. intensity relationships that are anchored to engineering limit states (set considering both structural and non-structural elements) it is shown that one can predict EAL values quickly, through a closed form expression that could be implemented easily in practice. The validity of the approach is demonstrated by comparing predictions of EAL with those obtained using refined EAL assessments, for a number of case study buildings. The limitations with the accuracy of the approach are discussed and the possibility of developing empirical loss vs. intensity relationships as part of future research is proposed.Item Open Access A comparison of non-uniform sampling and model-based analysis of NMR spectra for reaction monitoring(Wiley, 2021) Steimers E; Matviychuk, Yevgen; Friebel A; Münnemann K; von Harbou E; Holland, DanielNuclear magnetic resonance (NMR) spectroscopy is widely used for applications in the field of reaction and process monitoring. When complex reaction mixtures are studied, NMR spectra often suffer from low resolution and overlapping peaks, which places high demands on the method used to acquire or to analyse the NMR spectra. This work presents two NMR methods that help overcome these challenges: 2D non-uniform sampling (NUS) and a recently proposed model-based fitting approach for the analysis of 1D NMR spectra. We use the reaction of glycerol with acetic acid as it produces five reaction products that are all chemically similar and, hence, challenging to distinguish. The reaction was measured on a high-field 400 MHz NMR spectrometer with a 2D NUS-heteronuclear single quantum coherence (HSQC) and a conventional 1D 1H NMR sequence. We show that comparable results can be obtained using both 2D and 1D methods, if the 2D volume integrals of the 2D NUS-HSQC NMR spectra are calibrated. Further, we monitor the same reaction on a low-field 43 MHz benchtop NMR spectrometer and analyse the acquired 1D 1H NMR spectra with the model-based approach and with partial least-squares regression (PLS-R), both trained using a single, calibrated data set. Both methods achieve results that are in good quantitative agreement with the high-field data. However, the model-based method was found to be less sensitive to the training data set used than PLS-R and, hence, was more robust when the reaction conditions differed from that of the training data.Item Open Access Electronic Failure of Small Implantable Devices due to Moisture Ingress Through a Medical Grade Epoxy(2023) Munro, Deborah; Blue SThis article discusses the evaluation of the hermeticity of polymeric/epoxy enclosures for long-term implantation. The aim was to determine the expected lifespan of biomedical devices inside the human body under accelerated conditions using two medical grade epoxies, Loctite Hysol M-31CL and Master Bond EP40 Med, to prevent moisture ingress. The results showed that the type of adhesive used to seal biomedical devices is a critical factor in determining their expected lifespan inside the human body, and the EP40 Med epoxy provided superior performance against moisture ingress compared to the M-31CL epoxy. A mathematical model was used to determine the lifetime of the polymer-metal-epoxy encapsulation based on internal relative humidity, which closely resembled the experimental results. The study's limitations included visual interpretation to determine the day the internal relative humidity reached 55%, and the experimental tests were conducted under accelerated conditions. Further research is necessary to confirm the generalizability of these results to real-world conditions and explore other factors that may influence the lifespan of biomedical devices. However, the study provides valuable information for the design and development of biomedical devices and highlights the critical role that adhesives play in determining their expected lifespan inside the human body.Item Open Access An integrated industrial risk assessment methodology for accident safety, chronic health, and chemical exposure(Victoria University of Wellington, online-publication-date) Pons, DirkContext – Industrial safety primarily uses ISO31000 risk assessment based on consequence and likelihood to anticipate and prevent accidents. The method focuses on avoiding the occurrence of temporally immediate biophysical harm. Chronic health conditions are more difficult to include, as the harm is not necessarily immediate and the consequences can remain long after the hazardous event is removed. Furthermore the consequence scales vary for the different hazards. In the case of chemical hazards, the Globally Harmonised System (GHS7) measures these by severity (dose required for death), but this metric is incompatible with the graduated harm scales used in ISO31000. Consequently it is difficult to include chemical hazards in the methods used for other workplace hazards. There is a need for a single integrated method that can accommodate all aspects of industrial safety. Approach – The GHS7 chemical exposure scale is reworked and extended to non-death outcomes to make it compatible with the ISO31000 Risk management approach. Originality – A set of three harmonised consequence scales are developed for safety (immediate accident consequences), health (long term & chronic ill-health), and chemical exposure (death as well as less severe outcomes). This allows a single ISO31000 compliant methodology to be used.Item Open Access Indigenous people in Aotearoa New Zealand are overrepresented in cannabis convictions(Springer Science and Business Media LLC, 2022) Rapana W; Winter, Taylor; Fox R; Riordan BC; Kulkarni R; Waitoki W; Scarf DBackground: Previous work has demonstrated that cannabis laws have had a disproportionate impact on Māori, the Indigenous people of Aotearoa New Zealand. In 2019, the New Zealand Government amended cannabis laws, providing police with the power to determine whether a therapeutic or health-centred approach would be more beneficial than a conviction. In the current study, we use population level data to assess whether this law change has ameliorated the bias in cannabis convictions for Māori. Methods: Data were drawn from the Integrated Data Infrastructure (IDI), a large government database hosted by Aotearoa New Zealand’s national statistics office. In the IDI, we selected individuals who (1) were between 18 and 65, (2) were Māori or Pākehā (New Zealanders of European descent) and, (3) had any cannabis charges that proceeded to the courts. Results: Māori ethnicity was a significant predictor of the odds of receiving a cannabis conviction for Māori males (Odds: 1.56), with a marginally significant effect for Māori females (Odds: 1.57). Further, for Māori, there was no reduction in the number of cannabis charges before vs. after the amendment to cannabis laws. Conclusion: The current study demonstrates that the bias in cannabis convictions for Māori remain. Given this, the New Zealand Government must follow other countries around the world and move forward on cannabis law reform.Item Open Access Left-wing support of authoritarian submission to protect against societal threat(Public Library of Science (PLoS), 2022) Winter, Taylor; Jose PE; Riordan BC; Bizumic B; Ruffman T; Hunter JA; Hartman TK; Scarf D; Jasny LSNew Zealand's Prime Minister, Jacinda Ardern, adopted a "go hard, go early"approach to eliminate COVID-19. Although Ardern and her Labour party are considered left-leaning, the policies implemented during the pandemic (e.g., police roadblocks) have the hallmarks of Right-Wing Authoritarianism (RWA). RWA is characterized by three attitudinal clusters (authoritarian aggression, submission, and conventionalism). The uniqueness of the clusters, and whether they react to environmental change, has been debated. Here, in the context of the pandemic, we investigate the relationship between political orientation and RWA. Specifically, we measured political orientation, support for New Zealand's major political parties, and RWA among 1,430 adult community members. A multivariate Bayesian model demonstrated that, in the middle of a pandemic, both left-leaning and right-leaning individuals endorsed items tapping authoritarian submission. In contrast to authoritarian submission, and demonstrating the multidimensional nature of RWA, we observed the typical relationships between political orientation and authoritarian aggression and conventionalism was observed.Item Open Access Methodological and conceptual complexities of assessing relationships between single-occasion CRP inflammation and daily affect(Elsevier BV, 2021) Winter, Taylor; Riordan BC; Conner TS; Jose PInflammation is commonly implicated in sustained levels of depressed mood, chiefly with concurrent measures. There is a dearth of research on understanding how mood-inflammation relationships change on a day-to-day timescale. Determining how inflammation and mood may fluctuate and interact with each other is imperative to determining which pathways may lead to a depressed mood due to inflammation, and, more broadly, which factors induce inflammation in the first place. Therefore, we explored a means of elucidating the nature of mood-inflammation relationships using daily measures of mood and a single time-point measure of inflammation, C-Reactive Protein (CRP). We predicted that the relationship between affect and this measure of inflammation would be time-invariant because of evidence suggesting factors contributing to inflammation are persistent over time, such as obesity or poor gut-microbiome health. Our sample consisted of 1397 young adult participants who completed daily surveys for thirteen days and provided a blood sample for CRP measurement once at the conclusion of the study. A Bayesian multivariate regression model was performed to determine how daily levels of positive and negative mood could be predicted by this single time-point measure of inflammation. As part of our analysis, we sought to control for two key moderators, BMI and physical activity. Results indicated that moderate levels of inflammation were not associated with poor mood when the individual exercised. We also determined that high BMI participants exhibited a greater impact of inflammation on their mood relative to low BMI participants. However, contrary to our primary prediction that this mood-inflammation relationship would be time-invariant, we did indeed find that the relationship was time-variant. This result indicated that research examining associations involving inflammation daily will be required to understand which causative factors may contribute to fluctuations of a mood-inflammation relationship on a daily basis.Item Open Access Mapping Guaranteed Positive Secret Key Rates for Continuous Variable Quantum Key Distribution(MDPI AG, 2024) Sayat MT; Thearle O; Shajilal B; Kish SP; Lam PK; Rattenbury NJ; Cater, JohnThe standard way to measure the performance of existing continuous variable quantum key distribution (CVQKD) protocols is by using the achievable secret key rate (SKR) with respect to one parameter while keeping all other parameters constant. However, this atomistic method requires many individual parameter analyses while overlooking the co-dependence of other parameters. In this work, a numerical tool is developed for comparing different CVQKD protocols while taking into account the simultaneous effects of multiple CVQKD parameters on the capability of protocols to produce positive SKRs. Using the transmittance, excess noise, and modulation amplitude parameter space, regions of positive SKR are identified to compare three discrete modulated (DM) CVQKD protocols. The results show that the M-QAM protocol outperforms the M-APSK and M-PSK protocols and that there is a non-linear increase in the capability to produce positive SKRs as the number of coherent states used for a protocol increases. The tool developed is beneficial for choosing the optimum protocol in unstable channels, such as free space, where the transmittance and excess noise fluctuate, providing a more holistic assessment of a protocol’s capability to produce positive SKRs.Item Open Access Generation of c-MycERTAM-transduced human late-adherent olfactory mucosa cells for potential regenerative applications(Springer Science and Business Media LLC, 2019) Santiago-Toledo , Gerardo; Georgiou , Melanie; dos Reis , Joana; Roberton , Victoria H.; Valinhas , Ana; Wood, Rachael; Phillips , James B.; Mason , Chris; Li , Daqing; Li , Ying; Sinden , John D.; Choi , David; Jat , Parmjit S.; Wall , Ivan B.Human olfactory mucosa cells (hOMCs) have been transplanted to the damaged spinal cord both pre-clinically and clinically. To date mainly autologous cells have been tested. However, inter-patient variability in cell recovery and quality, and the fact that the neuroprotective olfactory ensheathing cell (OEC) subset is difficult to isolate, means an allogeneic hOMC therapy would be an attractive “off-the-shelf” alternative. The aim of this study was to generate a candidate cell line from late-adherent hOMCs, thought to contain the OEC subset. Primary late-adherent hOMCs were transduced with a c-MycERTAM gene that enables cell proliferation in the presence of 4-hydroxytamoxifen (4-OHT). Two c-MycERTAM-derived polyclonal populations, PA5 and PA7, were generated and expanded. PA5 cells had a normal human karyotype (46, XY) and exhibited faster growth kinetics than PA7, and were therefore selected for further characterisation. PA5 hOMCs express glial markers (p75NTR, S100ß, GFAP and oligodendrocyte marker O4), neuronal markers (nestin and ß-III-tubulin) and fibroblast-associated markers (CD90/Thy1 and fibronectin). Co-culture of PA5 cells with a neuronal cell line (NG108-15) and with primary dorsal root ganglion (DRG) neurons resulted in significant neurite outgrowth after 5 days. Therefore, c-MycERTAM-derived PA5 hOMCs have potential as a regenerative therapy for neural cells.Item Open Access Zeolite membrane-based low-temperature dehydrogenation of a liquid organic hydrogen carrier: a key step in the development of a hydrogen economy(2024) Kim S; Lee S; Sung S; Gu S; Kim J; Lee G; Park J; Choi J; Yip, Alex