School of Science

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https://hdl.handle.net/10292/1333
Research at AUT's School of Science is focused on key scientific issues with regional and global significance. The common theme connecting all research areas is sustainability – in the broadest sense as it relates to environmental and human health. Our research is closely allied to teaching and learning opportunities at undergraduate and postgraduate level within the school. Research is organised in three thematic areas:

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Now showing 1 - 5 of 266
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    Geometric Implications of Photodiode Arrays on Received Power Distribution in Mobile Underwater Optical Wireless Communication
    (MDPI AG, 2024-05-28) Govinda Waduge, Tharuka; Seet, Boon-Chong; Vopel, Kay
    Underwater optical wireless communication (UOWC) has gained interest in recent years with the introduction of autonomous and remotely operated mobile systems in blue economic ventures such as offshore food production and energy generation. Here, we devised a model for estimating the received power distribution of diffused line-of-sight mobile optical links, accommodating irregular intensity distributions beyond the beam-spread angle of the emitter. We then used this model to conduct a spatial analysis investigating the parametric influence of the placement, orientation, and angular spread of photodiodes in array-based receivers on the mobile UOWC links in different Jerlov seawater types. It revealed that flat arrays were best for links where strict alignment could be maintained, whereas curved arrays performed better spatially but were not always optimal. Furthermore, utilizing two or more spectrally distinct wavelengths and more bandwidth-efficient modulation may be preferred for received-signal intensity-based localization and improving link range in clearer oceans, respectively. Considering the geometric implications of the array of receiver photodiodes for mobile UOWCs, we recommend the use of dynamically shape-shifting array geometries.
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    Carry-Over Effects of Broodstock Conditioning on the Salinity Tolerance of Embryos of the New Zealand Geoduck (Panopea zelandica)
    (Hindawi Limited, 2024-01-01) Sharma, SS; Alfaro, AC; Ragg, NLC; Zamora, LN
    The New Zealand geoduck (Panopea zelandica) has seen considerable interest from the NZ aquaculture industry. A major bottleneck in culturing P. zelandica is early life stages mortality (e.g., embryo). Therefore, in this study, we investigated the embryonic performance and their transition to the first feeding larval stage (D-veliger) under different salinities (26, 30, 32, and 35 ppt) of four different offspring groups generated from broodstock being fed different ratios (25: 75, 50: 50, 60: 40, and 75: 25) of the haptophyte Tisochrysis lutea (formerly Isochrysis galbana) (ISO) and the diatom Chaetoceros muelleri (CM) during gametogenesis. Broodstock within all diet ratio treatments successfully conditioned, producing viable embryos. Average egg size ranged between 75 and 80 μm and was not affected by the diet ratios of the broodstock. Survival 48 hr postfertilization, D-veliger larvae yield, and incidence of abnormalities depended on both the embryo rearing salinity and broodstock feeding ratios. The combined salinity of 32-35 ppt and a feeding ratio of 50: 50 and 60: 40 (ISO:CM) had the highest survival of embryos (56.0%-77.5%), highest production of D-veliger larvae (>65%), and lowest incidence of abnormalities within D-Veliger (<47%). The size of the larvae decreased with decreasing salinities, with the largest found at 35 ppt (101.22 ± 0.49 μm in shell length). Embryos and larvae did not survive at salinity 26 ppt. These results suggest that diet during gametogenesis can play a role on the offspring ability to cope with environmental stressors at least during the critical first few days after fertilization. These findings provide important information on transgenerational effects due to broodstock diet, especially during the early life stages.
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    Investigation of the In Vitro Immunomodulatory Effects of Extracts from Green-Lipped Mussels (Perna canaliculus)
    (MDPI AG, 2024-03-15) Lessa, Roberta Cardim; Ebrahimi, Belgheis; Li, Hui; Guan, Xiao; Li, Yan; Lu, Jun
    The immune system plays a crucial role in defending the body against foreign invaders, and the balance of various polyunsaturated fatty acids, such as alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), can impact immune cell functions and overall immune responses. This study aimed to assess the effectiveness of mussel oil extracts in modulating inflammatory responses by analysing their effects on immune cell lines and cytokine expression. Four different mussel oil extracts were obtained using two extraction methods (organic solvent and supercritical CO2 extraction) from two tissue sources (fresh and commercial). These extracts were then tested at various concentrations on T lymphocyte (Jurkat) cells, monocytes, and macrophages (THP-1 and U-937). Cytokine levels were quantified using ELISA. The results showed that the solvent-extracted samples had a dose-dependent effect on tumour necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β) cytokine secretion in THP-1 and U937 cells, with the extract from a commercial mussel powder being more efficient than the extract from fresh powder. However, supercritical CO2 samples showed elevated cytokine secretion levels despite their high omega-3 content. Furthermore, 100 ug/mL extract from fresh powder successfully reduced interleukin-2 (IL-2) secretion while maintaining cell viability after stimulation. The study demonstrated that solvent-extracted mussel oil can effectively regulate cytokine secretion, modulate immune cell activation, and alleviate inflammation. These findings offer valuable insights into using mussel oil extracts to treat inflammatory disorders and enhance immune responses.
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    Soil Conditions Are a More Important Determinant of Microbial Community Composition and Functional Potential Than Neighboring Plant Diversity
    (Elsevier BV, 2024-06) Louisson, Ziva; Gutiérrez-Ginés, Maria J; Taylor, Matthew; Buckley, Hannah L; Hermans, Syrie M; Lear, Gavin
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    Pulsed Electric Field Pretreatments Affect the Metabolite Profile and Antioxidant Activities of Freeze-and Air-Dried New Zealand Apricots
    (MDPI AG, 2024-06-04) Liu, Ye; Oey, Indrawati; Leong, Sze Ying; Kam, Rothman; Kantono, Kevin; Hamid, Nazimah
    Pulsed electric field (PEF) pretreatment has been shown to improve the quality of dried fruits in terms of antioxidant activity and bioactive compounds. In this study, apricots were pretreated with PEF at different field strengths (0.7 kV/cm; 1.2 kV/cm and 1.8 kv/cm) at a frequency of 50 Hz, and electric pulses coming in every 20 µs for 30 s, prior to freeze−drying and air−drying treatments. PEF treatments were carried out at different field strengths. The impact of different pretreatments on the quality of dried apricot was determined in terms of physical properties, antioxidant activity, total phenolic content, and metabolite profile. PEF pretreatments significantly (p < 0.05) increased firmness of all the air−dried samples the most by 4–7−fold and most freeze−dried apricot samples (44.2% to 98.64%) compared to the control group. However, PEF treatment at 1.2 kV/cm did not have any effect on hardness of the freeze−dried sample. The moisture content and water activity of freeze−dried samples were found to be significantly lower than those of air−dried samples. Scanning electron microscopy results revealed that air drying caused the loss of fruit structure due to significant moisture loss, while freeze drying preserved the honeycomb structure of the apricot flesh, with increased pore sizes observed at higher PEF intensities. PEF pretreatment also significantly increased the antioxidant activity and total phenol content of both air−dried and freeze−dried apricots. PEF treatment also significantly (p < 0.05) increased amino acid and fatty acid content of air−dried samples but significantly (p < 0.05) decreased sugar content. Almost all amino acids (except tyrosine, alanine, and threonine) significantly increased with increasing PEF intensity. The results of this study suggest that PEF pretreatment can influence the quality of air−dried and freeze−dried apricots in terms antioxidant activity and metabolites such as amino acids, fatty acids, sugar, organic acids, and phenolic compounds. The most effective treatment for preserving the quality of dried apricots is freeze drying combined with high−intensity (1.8 kv/cm) PEF treatment.
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