Division of Sciences Departmentshttp://hdl.handle.net/10523/872024-03-28T23:38:06Z2024-03-28T23:38:06ZTowards Antibacterial Mechanically Interlocked ArchitecturesFaulkner, Loganhttp://hdl.handle.net/10523/166632024-03-28T15:33:23Z2024-03-27T02:19:12ZTowards Antibacterial Mechanically Interlocked Architectures
2024
Faulkner, Logan
This thesis consists of four chapters.
Chapter 1 introduces bacteria and the growing problem of antibacterial resistance. Mechanically interlocked molecules (MIAs) and the many subtypes are then presented, with a particular focus on rotaxanes and catenanes. The origin, design and synthesis of these interlocked architectures are closely examined. The potential applications for these types of supramolecules are also explored, with a particular focus on catalysis and biology. Crown ether containing compounds are then examined, and their applications in biology are discussed, in particular their ability to incorporate different cations into their central cavity. The aims of this project are then laid out, first to synthesize and characterise a family of [2]catenanes and [2]rotaxanes, and then to test the antibacterial activity of these compounds.
Chapter 2 discusses the origins of rotaxanes, as well as the different approaches which can be used to synthesize these MIAs. With a particular focus on the template approach, using either metal atoms or hydrogen bonding. The synthetic approach to [2]rotaxane formation designed by the Leigh group is then discussed, as they developed a family of [2]rotaxanes using a 1o amine, a crown ether, and an electrophile in a one pot reaction. Building on this approach used by the Leigh group, our own approach to [2]rotaxanes is then explored, starting with the first generation of [2]rotaxanes, which followed closely to the work by the Leigh group. The synthesis of the second generation of [2]rotaxanes is then investigated, using electrophiles with additional methylene groups, which produced more interesting MIAs, but in more modest yields. Additionally, attempts to synthesize [3]rotaxanes were described, using double headed electrophiles and two equivalents of nucleophile and crown ether, the results proved unsuccessful however, and no amounts of [3]rotaxane were seen, with only trace amounts of [2]rotaxane observed via HR-ESIMS.
Chapter 3 details different metal ion templated approaches to synthesizing catenanes. First the ring closing metathesis (RCM) approach used by Leigh and coworkers, and then the imine condensation pathway used by Au-Yeung and coworkers. Catenation attempts are then described using the palladium trimer first designed by Nitschke and coworkers. The focus then shifts to the synthesis of the tridentate ligands and the subsequent attempts made to form [2]catenanes using the ligands and a preformed macrocycle. The synthetic pathway used by Au-Yeung and coworkers is then followed, forming copper(I) complexes which were confirmed by single crystal x-ray crystallography. Attempts where then investigated to form [2]catenanes from these complexes but were ultimately proven unsuccessful.
Chapter 4 discusses the potential future directions of this research, including the synthesis of a third generation of [2]rotaxanes as well as potential improvements to the synthesis of [3]rotaxanes. The formation of metal complex containing rotaxanes is also mentioned, along with the future directions for the attempts made for the synthesis of a family of [2]catenanes. The potential biological results are discussed, and the work performed in this research is concluded.
2024-03-27T02:19:12ZQuantum frequency conversion in rare earth ionsKing, Gavin Gordon Georgehttp://hdl.handle.net/10523/166582024-03-28T15:32:37Z2024-03-21T23:57:42ZQuantum frequency conversion in rare earth ions
2024
King, Gavin Gordon George
Recent advances in quantum technologies have seen quantum computers using superconducting qubits approach the ability of classical computers.
These superconducting qubits are naturally microwave devices, but microwave photons are all too easily swamped by thermal noise at room temperatures, limiting the ability to connect different quantum devices. Optical photons, on the other hand, have much higher energies and can be readily used at room temperature without being lost in thermal noise. Optical photons are also compatible with photonic memories, whereas microwave photons have few successful methods of long-term storage.
Therefore, it seems likely that quantum computers will be hybrid devices, with (microwave) superconducting qubits using (optical) photonic memories and interconnects to the outside world, and so there needs to be a way to coherently convert between the two frequency regimes.
This thesis investigates the use of rare earth ions for this quantum frequency conversion between microwave photons and optical photons. In the past, spin transitions in erbium-doped yttrium orthosilicate have been seen to convert microwave photons to optical photons, but with conversion efficiencies limited by thermal excitation and the presence of unwanted erbium isotopes. Using isotopically enhanced Er-170 at dilution fridge temperatures, these limitations were addressed.
Two measurements were made of this isotopically enhanced system, one using resonant enhancement of only the microwave fields in the erbium containing material, and one with resonant enhancement of both the microwave and optical fields. A maximum conversion efficiency of 10⁻⁶ was seem for conversion between microwave photons of around 5 GHz to optical photons in the 1550 nm telecommunications band, with the limitations being identified as not fundamental properties of the system, but as control over the effective spin temperatures and detector noise.
One previously identified trade off in using doped samples is between the density of ions and their inhomogeneous linewidth. Fully concentrated materials have the potential to greatly increase the spectral density of ions while maintaining narrow spectral lines with long-range order, and there have been theoretical predictions that using collective spin excitations (magnons) could improve conversion efficiency. These are a new class of materials, and to investigate them, measurements were made of anti-ferromagnetic resonances in gadolinium vanadate. The behaviour of the spin resonances is observed, and strong coupling between the spins and the microwave field is seen, which is one requirement for high efficiency frequency conversion.
2024-03-21T23:57:42ZDrivers of population dynamics and fishery status of blackfoot pāua (Haliotis iris)Ryder, Finn Joelhttp://hdl.handle.net/10523/166502024-03-18T14:40:31Z2024-03-17T20:06:43ZDrivers of population dynamics and fishery status of blackfoot pāua (Haliotis iris)
2024
Ryder, Finn Joel
Drivers of coastal fishery status and population dynamics are complex due to the broad range of stressors to which coastal species are subjected. For successful fisheries management it is essential to understand drivers of population variability so that management can be adjusted accordingly. The population dynamics, and individual traits of abalone (Haliotids) can vary on the scale of metres to kilometres. In New Zealand, the cultural keystone, pāua (Haliotis iris, blackfoot abalone) has undergone considerable stock declines, and stock enhancement efforts have had limited success. For fisheries managers, it is important to know how a population of interest has changed over time, what factors may influence a populations spatial distribution and if they can use this information to adjust management. Therefore, the aim of this thesis is to disentangle drivers of fishery status and population dynamics of H. iris. First, I examined how a H. iris population in Peraki Bay, Banks Peninsula changed after 45 years. Comprehensive historic population data from the 1970s provided a baseline of abundance, size structure, and population dynamics before exposure to a commercial fishery and a range of environmental stressors. Repeat monitoring of the H. iris population at a 45-year interval indicate that a large change in population size and structure had occurred. Since 1976, there has been an 84% decrease in estimated population size. The remaining population is restricted to where juveniles were found in the original survey. This chapter indicates that H. iris may be susceptible to multiple stressors including habitat loss, climate change, and low and inconsistent recruitment. I then examined spatial drivers of H. iris density and shell length using multiple regression modelling, and generalised linear modelling. Physical and biological habitat and fishing restrictions data were gathered across six Customary fishery Protection Areas (CPAs, Mātaitai Reserves and Taiāpure Local Fisheries) across the takiwā (tribal area) of the Te Waipounamu (South Island) iwi (tribe) Ngāi Tahu. Model averaging indicate that H. iris density and size are driven by different factors. Haliotis iris density was negatively correlated to time under fishing restrictions, and macroalgal density. Shell length of H. iris was larger in deep habitats and negatively related to the density of the gastropod, Cookia sulcata. Spatial drivers were then investigated further in the East Otago Taiāpure (EOT), a CPA in southern Te Waipounamu. In-situ and modelled wave data, and drift algae biomass were used to determine whether H. iris reach higher densities and larger shell lengths in more wave exposed environments. Principal component regression and bootstrapping indicate that H. iris density was positively related to wave bottom orbital velocity, but negatively related to days exposed to large wave events. No relationship was observed between drift algae biomass and density or mean shell length of H. iris. Lastly, I investigated the depth distribution of H. iris in the EOT in light of a proposal by the EOT Management Committee to harvest H. iris at wading depths. Wading-only harvest involves gathering in shallow waters (depths up to around knee deep) without the use of a mask and snorkel. The reasoning behind the proposal being that a wading-only fishery could keep the fishery open while providing protection for populations in deeper water. The abundance and shell length of H. iris were recorded at 0.1 m depth intervals using belt transects. Provided a wadable limit of 0.5 metres is set, 78% of the H. iris surveyed would be accessible to wading harvest at chart datum, although this percentage differed among sites from 55 – 99%. Shell length increased with depth, indicating that a depth refuge would provide protection to mature individuals. This study indicates that some sites may be suited to wading harvest while others may not, highlighting the need to consider the reef by reef implications of management decisions.
Overall, this thesis provides new insights on how H. iris populations can change on long timescales and small spatial scales. This information, can be used to make more informed management decisions for H. iris, on ecologically relevant scales, in New Zealand. The environmental drivers discussed throughout this thesis however, will likely apply to other abalone species, and may be useful to guide management decisions and restoration efforts in other abalone fisheries globally.
2024-03-17T20:06:43ZProfiling free amino acid pool in the muscles of triplefin-fish after being fed with chitosan and zein-based films containing heavy metals to identify the potential changes in amino acid metabolismZhao, Chunhttp://hdl.handle.net/10523/166492024-03-28T15:32:42Z2024-03-15T02:43:46ZProfiling free amino acid pool in the muscles of triplefin-fish after being fed with chitosan and zein-based films containing heavy metals to identify the potential changes in amino acid metabolism
2024
Zhao, Chun
Previous studies have demonstrated that plastic particles (PLA), degraded from food packaging waste, have high affinity with heavy metals (HM) that result in a worse combined marine plastic pollution than plastic pollution alone. Chitosan and zein-based edible food film (CZF) is biodegradable and environmentally friendly which could be considered as an alternative material to reduce the plastic pollution. On the other hand, the heavy metals bound to PLA could induce oxidative stress disrupting the amino acid metabolism of fish, hence there is a need to evaluate whether CZF can reduce the heavy metal complex formation as well as the resulting oxidative stress that affects the amino acid metabolism of fish. The heavy metals came from the contaminants originally present in the ingredients used in the film making.
For this study, Triplefin-fish (Forsterygion capito, TPN-fish), a local species found in New Zealand waters was selected as our model organism due to its integral role within marine ecosystems, particularly in contributing to the lower levels of marine food chains. We exposed them to PLA and CZF at similar dosage and frequency for the same predefined feeding time (39 days). The profile of amino acid pool was measured only in the muscle portion of the fish. Based on the literature review, analysis of the free amino acid (FAA) pool was selected as a key biomarker to evaluate the effects of CZF and PLA exposure on TPN-fish muscle. The FAA pool profiling was conducted using gas chromatography with flame ionization detector (GC- FID) as an analytical approach. Multivariate and univariate statistical approaches, namely principal component analysis (PCA) and orthogonal partial least squares–discriminant analysis (OPLS-DA), and Mann–Whitney U test and one-way analysis of variance (ANOVA), were used to identify FAA discriminators associated with exposure to CZF and PLA. The identified discriminators were further evaluated by pathway analysis to identify potentially affected areas of amino acid metabolism.
The FAA pool in the white muscle of TPN-fish exposed to CZF was found to be altered, including a decreased level of branched chain amino acids (BCAAs), serine, methionine, phenylalanine, histidine, tyrosine, tryptophan, ornithine, and an increased level of alanine and glutamine. In addition, specific impacted pathways were identified in relation to the change in the FAA pool, namely phenylalanine, tyrosine and tryptophan biosynthesis; alanine, aspartate, glutamic acid and glutamine metabolism; valine, leucine and isoleucine biosynthesis. Overall, the altered amino acid metabolism was attributed to abnormal energy metabolism, reduction of weight gain and a disturbed immune system in TPN-fish. Moreover, the decreased levels of phenylalanine, tryptophan and histidine were found to be associated with changes in fish behaviour and swimming performance. The present study has demonstrated that FAA pool profiling can be a robust and effective approach in monitoring the biophysical effects of exposing TPN-fish to CZF.
This study was the first to use GC-FID based FAA pool profiling to investigate the effect of an alternative food packaging material (CZF) in a New Zealand aquatic ecosystem. Evaluation of the FAA data indicated that this approach could specifically contribute to the evaluation of the safety of CZF in the environment. The results of the present study also provide a preliminary framework in relation to the application of FAA profiling to evaluate metabolic changes in a model organism, on exposure to an alternative food packaging material, and its potential effect on the environment.
2024-03-15T02:43:46ZFire & Ice Using ancient DNA to reconstruct the phylogeography of the extinct New Zealand Goose Cnemiornis spp. Te Ahi me te Hukapapa Te matai whenua ā-ira o te TarepoGreer, Liamhttp://hdl.handle.net/10523/166472024-03-18T14:40:17Z2024-03-15T01:17:48ZFire & Ice Using ancient DNA to reconstruct the phylogeography of the extinct New Zealand Goose Cnemiornis spp. Te Ahi me te Hukapapa Te matai whenua ā-ira o te Tarepo
2024
Greer, Liam
Changes in the physical environment over time has a sustained impact on the physical and genetic features of taxa and populations within a species. New Zealand has had a long and varied history in its 80-million-year existence which has shaped the endemic and native biota that call it home. The recent field of Palaeogenomics has shed light on the complex ways that the changes in the environment have impacted those species. The New Zealand goose Cnemiornis is a genus of recently extinct large and flightless waterfowl which was previously resident on both two main islands in the archipelago: Cnemiornis gracilis on the North Island, and Cnemiornis calcitrans on the South Island. In this thesis, palaeogenetic approaches were used to sample the DNA of Cnemiornis and construct the phylogeographic history and structure of the genus, examining whether the genus has been impacted by geologic events in patterns like those observed in cohabitant avifauna. Recovered partial mitogenomes confirmed the placement of Cnemiornis within the Anatidae family as the sister taxon to the extant Cape Barren goose Cereopsis novaehollandiae. Strong support for the existence of two species of Cnemiornis was shown through phylogenetic analysis, indicating that the two species diverged in the Mid Pleistocene as a result of the closure of the Manawatū strait. Within the South Island species C. calcitrans, phylogenetic analysis found strong support for two genetically distinct clades, called here C. calcitrans “northern” and C. calcitrans “southern”, with divergence attributed to the glacial-interglacial cycles of glacier expansion and contraction in the Southern Alps, and the Mid Pleistocene climate transition (MPCT). Within the North Island species, evidence thought limited was found to support two clades called here C. gracilis “eastern” and C. gracilis “western”, with divergence attributed to the intermittent volcanic events of the Taupō Volcanic Zone in central North Island. This study represents the first in-depth examination of a previously little known extinct New Zealand genus and furthers the evidence for palaeogenomics as a significant tool in the understanding of how a changing world impacts living organisms.
2024-03-15T01:17:48ZDynamic metamorphism within the Rakeahua batholith, Mason and Doughboy Bay region, Stewart IslandPeden, Rosshttp://hdl.handle.net/10523/166412024-03-28T15:33:18Z2024-03-13T01:57:36ZDynamic metamorphism within the Rakeahua batholith, Mason and Doughboy Bay region, Stewart Island
1989-12-14
Peden, Ross
A reconnaissance geological map at 1: 25 000 is presented for a previously unmapped Mason-Doughboy Bay area on the west coast of Stewart Island. Five granitoid plutons with faulted and intrusive contacts within the Rakeahua Batholith have been identified.
The Walkers Hill Fault (new name) separates the Hellfire granitoid complex (Allibone, 1986) to the north from the Mason-Doughboy suite (this study) to the south.
The Mason-Doughboy suite consists of four plutons and the Gutter High Strain Zone (new name). The youngest pluton is the Adams Hill Leucogranite (new name) which intrudes the other three, Doughboy Bay Granodiorite (new name), Ernest Island Diorite (new name) and the oldest, Walkers Hill Diorite (new name).
The Mason Bay Granodiorite (Allibone, 1987 and this study) to the north of the Walkers Hill Fault is younger than the post-emplacement tectonism, overprinted in the Mason-Doughboy suite. The Mason Bay Granodiorite is in faulted contact with the Walkers Hill Diorite.
The Adams Hill Leucogranite forms an intrusion breccia with both the Walkers Hill Diorite and Doughboy Bay Granodiorite. Adams Hill Leucogranite dykes, also intrude the Doughboy Bay Granodiorite. Intrusive contacts between the Ernest Island Diorite and the Adams Hill Leucogranite are complex, and concurrently folded within the Gutter High Strain Zone. Major and trace element chemistry of the five plutons indicates I-type affinities, but suggests S-type character for granite tectonites from the Gutter High Strain Zone.
The Gutter High Strain Zone is a localised narrow zone of predominantly ductile deformation, 1-2km wide. Development of the zone was accompanied by dynamic metamorphism, associated with movement, to greenschist facies conditions.
A progressive sequence of granite - granite tectonites - mylonites, and calc-silicate metasediment, garnet quartzites and amphibolites are found within the Gutter High Strain Zone. The zone has regionally inferred significance.
Syn-posttectonic deformation of the Gutter High Strain Zone is synchronous with post-emplacement tectonism of the Mason-Doughboy suite, these events are older than the Walkers Hill Fault. It is unclear if the intrusion of the Adams Hill Leucogranite is cause or symptomatic of the Gutter High Strain Zone, but is syn-posttectonic.
Magmatic Cu-sulphide textures in globules from host Adams Hill Leucogranite dykes indicate immiscibile melts.
Possible meteorite impact crater features proposed by Bishop et al. (1987 an unpublished preliminary report) are equally explained by natural geological and geomorphological phenomena.
There were no 'potential' economic resources discovered in the field.
2024-03-13T01:57:36ZThe importance of marine resource subsidies from diadromous fish in the diet of brown trout and shortfin eelKleyzen, Tylerhttp://hdl.handle.net/10523/166302024-03-18T14:40:45Z2024-03-07T00:25:22ZThe importance of marine resource subsidies from diadromous fish in the diet of brown trout and shortfin eel
2024
Kleyzen, Tyler
Marine to freshwater resource subsidies are characterised by the allochthonous transfer of energy and nutrients from the marine environment to a recipient freshwater system. These nutrients are known as marine derived nutrients, where this process of pulsed resource subsidies across ecosystem boundaries can generate ephemeral fluxes of energy that often enhance in situ productivity within the recipient ecosystem. Currently, the most comprehensively recognized process of marine resource transfer into freshwater systems involves the migrations of diadromous fish. These migrations and their effects have been studied globally, and the subsidies to riverine predators have been documented through the use of stomach content and stable isotope analyses. However, not many of these studies have focussed on Aotearoa’s (New Zealand) South Island lowland river systems, where these environments have been heavily degraded by continuous anthropogenic effects. In the present study, I aimed to further the knowledge on diadromous fish migrations and their importance to lowland river freshwater predators. In tandem, I aimed to conduct one of the first studies to use mucus as a non-lethal stable isotope “tissue” on wild salmonids and shortfin eels within Aotearoa, as recent reports indicate mucus is a potential substitute for lethally sampled tissues of wild fish.
The study was conducted along the lower Ōreti River, Southland, New Zealand, at three spatially separated sites during winter, spring, and summer. Brown trout (Salmo trutta) and shortfin eel (Anguilla australis) were used as the focal predators while migratory common smelt (Retropinna retropinna) were used as the seasonal prey. Fish were sampled at each site, during each season, where stomach contents and isotope samples of muscle, liver, and mucus were used to assess the importance of smelt to the diet of brown trout and shortfin eel while all tissues were compared against each other to observe isotopic differences.
Stomach content data revealed that brown trout and (to a lesser extent) shortfin eels changed their diet in response to a more seasonally abundant food source during the migratory smelt run. Results indicated that smelt were highly important to the diet of brown trout, but only moderately in shortfin eel during spring and summer, where importance was highest at the Estuary and decreasing towards the Upper Reach of the lower Ōreti River. Stable isotope data also indicated high proportional contribution of smelt to both brown trout and shortfin eel during spring while aligning with the stomach content data and revealing the assimilation of marine derived nutrients during the smelt migration. However, this was not observed in summer for brown trout where these results could be explained due to a change in the smelt’s isotopic values. Stable isotopes further revealed that brown trout δ15N increased at the Estuary and Middle Reach sites as the result of a seasonal shift, similarly for shortfin eel. Tissues were also comparable between each other, highlighting the potential use for mucus as a non-lethal bio tracer in substitution for traditional lethal tissues that are commonly used for dietary stable isotope studies. Furthermore, these results demonstrate how stomach content analysis and stable isotopes complement each other in producing accurate dietary patterns. In the present study, it was clear that smelt were an important dietary item to lowland predators during their migration. If estuaries continue to show declining trends in ecosystem health, this could have consequences for local communities and the surrounding biota.
2024-03-07T00:25:22ZSilver Linings: Understanding Kakaruai/South Island Robin Decline and Dispersal in a Fragmented LandscapePearmain-Fenton, Manaiahttp://hdl.handle.net/10523/166282024-03-28T15:32:46Z2024-03-06T20:55:24ZSilver Linings: Understanding Kakaruai/South Island Robin Decline and Dispersal in a Fragmented Landscape
2024
Pearmain-Fenton, Manaia
The fragmentation of forested environments in Aotearoa me Te Waipounamu/New Zealand has resulted in many small, geographically isolated local populations. These may be subjected to different limiting factors that influence a particular population's growth, distribution, or abundance. Limiting factors can include predation, food availability, and habitat availability. Predation alone is thought to be the primary driver of species decline in most forested areas nationwide. However, the complexity of interactions with other factors can be challenging to unravel. Movement is essential for facilitating population growth and gene flow, provided individuals can successfully establish themselves in these new habitats. Dispersal allows species to adapt to habitat changes, avoid competition, and escape from threats or adverse conditions in their juvenile habitats. Effective dispersal combines the physical act of moving from one place to another with the ability to find suitable resources such as food and shelter and successfully reproduce in these new areas.
I investigated the influence of predation, food availability, and functional habitat connectivity on a locally threatened, isolated insectivorous passerine that is highly sensitive to mammalian predators: the kakaruai (South Island robin; Petroica australis). I studied two populations within the wider Ōtepoti/Dunedin area: the remnant population persisting at Silver Stream, a reserve where no predator control has occurred since 2016, and the Orokonui Ecosanctuary population, translocated from Silver Stream (and the Silver Peaks) in 2010. Orokonui is a fenced mainland ecosanctuary, which excludes all invasive mammals except mice (Mus musculus). These two populations share the same gene pool but are geographically isolated from one another due to habitat fragmentation.
I firstly investigated the influence of predation and food availability on kakaruai. Initially, this involved a bifactorial experiment comparing interaction effects on nesting success between the two populations. However, upon discovering the impending collapse of the Silver Stream population, I instead compiled and evaluated key vital rates of the Silver Stream and Orokonui populations based on an extensive literature review alongside my own field observations during the 2022-23 breeding season. Only one female was located at Silver Stream during the 2022-23 season. Analysis of breeding behaviours and nesting outcomes at Silver Stream revealed a significantly male-biased sex ratio, likely a direct result of mammalian predators targeting incubating females on nests. My results emphasise the role of mammalian predation as a primary limiting factor and the proximate cause of an imminent local extinction. In contrast, the Orokonui population exhibited significantly different vital rates, including sex ratio, nest survival, and nest site selection, consistent with what would be expected from a predator-free environment.
I then examined whether the Orokonui kakaruai population was experiencing effective dispersal, also known as positive spillover, from inside the predator exclusion area and into surrounding habitats outside the fence. Incorporating data from surveys completed in 2018-2019, I carried out an additional survey season in 2022. I evaluated spillover through three key indicators: (1) detecting the presence of kakaruai at the same sites across multiple years, (2) assessing whether there is an increase in the number of birds within specific sites already occupied, and (3) identifying any newly colonised sites. I provided evidence for all three indicators suggesting spillover from Orokonui and effective dispersal of kakaruai. I found evidence that distance from the ecosanctuary, survey year, habitat type, and functional habitat connectivity all influenced kakaruai presence. The occurrence of kakaruai within the first 1,500 metres of the ecosanctuary increased significantly in the three years between 2019 and 2022. The effective dispersal of juveniles beyond the fence boundaries relies on whether sufficient habitat exists nearby. Functional connectivity, which integrates the quality of habitat with its connectivity to surrounding areas, was critical for kakaruai dispersal.
The major implication that emerges from my research is that the remnant Silver Stream population of kakaruai is in need of immediate conservation intervention due to the impact of mammalian predators. Additionally, my research can be used as a model for investigating effective dispersal at a population level, benefiting those seeking strategies for reinforcing biodiversity beyond ecosanctuary borders and at a landscape scale. My work also provides evidence for positive spillover from an ecosanctuary, provided habitat conditions are appropriate.
2024-03-06T20:55:24Z