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Towards identification of floc compounds in water using multi-frequency fluorescence lifetime analysis
(The University of Waikato, 2025) Dissanayake, S.A.D. Asanka Nilakshi; Cree, Michael J.; Lay, Mark C.; Streeter, Lee; Glasgow, Graeme D.E.
UV disinfection is commonly used in water treatment to inactivate pathogens such as Cryptosporidium and viruses to prevent diseases such as cryptosporidiosis and norovirus in communities. Disinfection typically follows water treatment steps, such as coagulation, flocculation, clarification, and filtration. However, particles in water, for example, flocs 0.1 to 100 μm in diameter, made from humic and inorganic substances present in the water, surrounding a Cryptosporidium oocyst or virus, can protect the pathogens from UV exposure. Although water treatment steps prior to disinfection remove 99% of the particulates, particles can still be present in the 1000s to 10,000’s per litre after filtration. While the chances of a floc particle carrying a virus or oocyst are typically low, in some regions, particularly during calving in the dairy industry, oocyst concentrations in the water might be high due to cryptosporidiosis in calves. Therefore, it is useful to test the properties of the floc compound for UV penetration to determine whether the disinfection method is appropriate. In this thesis, a technique that uses multi-frequency analysis to measure the fluorescence lifetime of a fluorophore to provide information on particle composition is presented. Frequency-domain fluorescence fluorometry was used to determine the fluorescence lifetime. This was achieved using an experimental setup that used a laser diode operating at 100 mW and modulated at 10–60 MHz to excite the fluorophores, optical elements to focus and filter the light, and detectors to collect the fluorescence emission signal via a storage oscilloscope. The signals were then processed using a MATLAB program to determine the fluorescence lifetime. Fluorescence lifetime measurements were challenged by the chemical and physical behaviour of the fluorophore and the adsorption of the fluorophore to the floc particles. Therefore, standard measurements such as turbidity, pH, particle size, and fluorescence were used to understand the absorption/adsorption of fluorescein to flocs. Fluorescence was observed at the 260–490 nm excitation wavelengths, with fluorescence emissions at approximately 510 nm. The particle size and turbidity measurements showed that fluorescein acted as a flocculant, with the particle size increasing with increasing fluorescein concentration. Fluorescence intensity measurements from a standard fluorescence spectrophotometer were used to calculate fluorescein adsorption on humic acid and kaolin to generate adsorption isotherms. Fluorescein was bonded to kaolin 10 times more than to humic acid. Adequate flocculation required a pH of 6.5 to produce reasonably flocculated particles in the sample. Surface charge analysis showed that the use of buffer to control pH required more alum to neutralise the surface charge of humic acid and kaolin. Multi frequency measurements and subsequent analysis showed that the fluorescence lifetime and contamination ratio were 4.2 ± 0.3 ns and 0.09 ± 0.05 for fluorescein. The fluorescence lifetime of fluorescein was compatible with the results of previous studies using different techniques. The samples with floc particles had a larger excitation light contamination ratio than those without particles; therefore, the contamination ratio could be used as a measure of particle contamination in the samples. The fluorescence lifetime of fluorescein did not change when fluorescein was attached to humic acid particles, but increased by 0.6 ns for kaolin floc particles.
Laying the tracks: Investigating the potential benefits for autistic children of a model railway initiative
(The University of Waikato, 2025) Gedye, Jacob; Anderson, Angelika
This study described a model railway programme in terms of its benefits for autistic children and their families/communities. A non-experimental mixed-method design was conducted, in which an observation schedule was designed to determine whether behaviours which are associated with language development were facilitated by the programme. Interviews with parents/caregivers were conducted to collect qualitative data about the programme, to better understand how it is perceived by visitors and what draws them to attend. Individual case studies with children and their parents/caregivers were done to build a clearer picture of what can be seen at an individual level. Finally, a focus group was arranged with members of the railway modeller’s club to find out their point of view and broaden the qualitative scope of the data. Findings suggest potential utility in this programme for autistic children and future research implications are discussed.
Studies toward an optimized synthesis of a Novel Imidazopyridinone DNA-PK Inhibitor
(The University of Waikato, 2025) Mora, Daniel A.; Dickson, Benjamin
Cancer is a disease of global significance, with cancer rates increasing year on year globally. A key challenge within the treatment of cancer is the cellular response to radiotherapy. When fractionated radiotherapy is targeted at cancerous cells DNA double strand breaks are promoted via free radical formation to induce cellular death. However, cellular responses activate the DNA double strand break repair mechanism to oppose these outcomes. Involved in this mechanism is the DNA-PK enzyme and the Auckland Cancer Society Research Centre (ACSRC) has developed an enzyme inhibitor SN39536 to inhibit the repair mechanism. Core aspects of the project surround the use and optimization of an alternative novel synthetic route to the drug as the original published route was developed allowing for structural diversity as opposed to efficiency. There are three novel reactions at the beginning of the alternative route leading to a point of convergence with the ACSRC route at an imidazopyridinone intermediate; a nucleophilic aromatic substitution, a base-catalyzed hydrolysis and a Curtius rearrangement. Analogous reactions were originally reported by Astra Zeneca (AZ) with pyrimidine analogues however in this work they have been adapted and optimized for pyridine variants. Post optimization the highest yield achieved for the pyridine substrates were; 85.3% for the nucleophilic aromatic substitution, 89.9% for the base-catalyzed hydrolysis and 69.5% for the Curtius rearrangement. These are comparable to the AZ yields with their pyrimidine analogues however in each case the addition of heat and/or increased reaction times were consistently required to match the AZ yields – highlighting that the novel pyridine substrates are not as activated for these reactions. The novel route generates the same imidazopyridinone intermediate as the ACSRC route in an overall yield of 53.3%. This is significantly lower than the 70.6% overall yield from the ACSRC route. Despite the novel route being viable for the synthesis of imidazopyridinones we propose it is currently an inferior alternative for the synthesis of SN39536. A rearrangement of the novel route steps was then attempted to explore if the altered electronics of the substrates aid or diminish the synthetic yield of the novel reactions. We placed the final Buchwald-Hartwig amination of the original syntheses after the initial novel nucleophilic aromatic substitution however, we were unable to optimize this novel cross-coupling beyond a yield of 19.0%. Investigation into the reaction conditions were unable to discern why the cross-coupling was consistently unsuccessful. The limited information from our substrate studies suggests that the substrate for this reaction does not have the correct electronics to undergo the proposed cross-coupling. The 19.0% yield of this reaction currently renders the rearranged novel route an unviable alternative to both previous syntheses.
Socially responsible and fair AI in healthcare applications in New Zealand
(2025) Yogarajan, Vithya
Issues that need to be considered, include: - Professional liability. - Labour market implications: Skills and expertise required of healthcare providers will change. - Ethical considerations. - Privacy concerns. - Regulatory compliance. - Provider–patient relationship: Empathy skills of healthcare providers have been shown to positively influence patient outcomes. Why is it a good idea? - AI to the rescue. - Productivity. - Workload. - Performance.
The use of microscopic traffic simulation model for the analysis of vehicle emission
(The University of Waikato, 2025) Kaushalya, Jani; Turner, Jessica Dawn
Road transport is a significant contributor to greenhouse gas emissions and urban air pollution in New Zealand, particularly in the rapidly growing Bay of Plenty region. The high vehicle density during peak hours and the reliance on petrol and diesel fuels in most fleets contribute significantly to vehicle emissions, which contribute to climate change and air quality degradation. This research investigates the use of a microscopic traffic simulation model to analyse vehicle emissions in order to identify practical measures to reduce transport-related emissions. SUMO (Simulation of Urban Mobility), an open-source software was used to construct the road network, generate realistic vehicle demand, and execute the simulation, while the HBEFA (Handbook Emission Factors for Road Transport) emission model was used to estimate vehicle emissions. This simulation utilised vehicle count data provided by the Tauranga City Council, and MongoDB was employed as the main database to facilitate effective storage, retrieval, and real-time querying of the simulation output. Three targeted emission reduction scenarios were developed and tested based on the simulation results: increasing electric vehicle ownership by 20%, introducing trackless trams on high-demand routes, and encouraging carpooling to reduce single-occupancy vehicle usage. As a result of the simulation, each measure resulted in significant reductions in vehicle emissions, and the effectiveness of each scenario was examined and compared. The findings of this study provide practical, data-driven insights for local councils, transport planners, and policymakers in implementing effective strategies to reduce vehicle emissions and contribute to New Zealand’s emission reduction targets.