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The 15 species of small carnivorous marsupials that comprise the genus Antechinus exhibit semelparity, a rare life-history strategy in mammals where synchronized death occurs after one breeding season. Antechinus males, but not females, age rapidly (demonstrate organismal senescence) during the breeding season and show promise as new animal models of ageing. Some antechinus species are also threatened or endangered. Here, we report a chromosome-level genome of a male yellow-footed antechinus Antechinus flavipes. The genome assembly has a total length of 3.2 Gb with a contig N50 of 51.8 Mb and a scaffold N50 of 636.7 Mb. We anchored and oriented 99.7% of the assembly on seven pseudochromosomes and found that repetitive DNA sequences occupy 51.8% of the genome. Draft genome assemblies of three related species in the subfamily Phascogalinae, two additional antechinus species (Antechinus argentus and A. arktos) and the iteroparous sister species Murexia melanurus, were also generated. Preliminary demographic analysis supports the hypothesis that climate change during the Pleistocene isolated species in Phascogalinae and shaped their population size. A transcriptomic profile across the A. flavipes breeding season allowed us to identify genes associated with aspects of the male die-off. The chromosome-level A. flavipes genome provides a steppingstone to understanding an enigmatic life-history strategy and a resource to assist the conservation of antechinuses.

Taxonomic distinction of species forms the foundation of biodiversity assessments and conservation priorities. However, traditional morphological and/or genetics-based taxonomic assessments frequently miss the opportunity of elaborating on the ecological and functional context of species diversification. Here, we used 3D geometric morphometrics of the cranium to improve taxonomic differentiation and add ecomorphological characterization of a young cryptic divergence within the carnivorous marsupial genus Antechinus. Specifically, we used 168 museum specimens to characterize the recently proposed clades A. stuartii ‘south’, A. stuartii ‘north’ and A. subtropicus. Beyond slight differences attributable to overall size (and, therefore, not necessarily diagnostic), we also found clear allometry-independent shape variation. This allowed us to define new, easily measured diagnostic traits in the palate, which differentiate the three clades. Contrary to previous suggestions, we found no support for a latitudinal gradient as causing the differentiation between the clades. However, skull shape co-varied with temperature and precipitation seasonality, suggesting that the clades may be adapted to environmental variables that are likely to be impacted by climate change. Our study demonstrates the use of 3D geometric morphometrics to improve taxonomic diagnosis of cryptic mammalian species, while providing perspectives on the adaptive origins and potential future threats of mammalian diversity.

Although the overall suicide rate worldwide has changed minimally over the past 100 years, different trends have been observed over time in the USA, Australia, and New Zealand (NZ). However, few studies have focused on suicides in children ( 80% of cases in South Australia and Auckland and 56% in Hennepin County. Hennepin County had a greater proportion of suicides using firearms (28%), compared to 1.9% in Auckland and 5.1% in South Australia. Unusual means of suicide were used less frequently by youth than previously.

Fentanyl is now the primary driver of the current opioid crisis. Fentanyl and its analogues are subject to the Controlled Substances Act of 1970, the Controlled Substances Analogue Enforcement Act of 1986 (Federal Analogue Act), state laws, international treaties, and the laws of foreign countries. The appearance of novel psychoactive substances led to further legislative developments in scheduling. New fentanyl analogues proliferated in a manner previously unseen since about 2016. Overdose deaths of these fentanyl analogues prompted the Drug Enforcement Administration to reactively emergency schedule each new fentanyl analogue as it appeared. The international community also acted. Finally, on February 6, 2018, a proactive temporary (emergency) class‐wide scheduling of fentanyl‐related substances was implemented based upon the fentanyl core structure to save lives. This action spurred a similar action in China. Fentanyl analogues fell dramatically in the marketplace, despite further increases in fentanyl itself. Congress temporarily extended this scheduling, but it will soon expire. Opposition to permanent class‐wide was lodged due to concerns over law enforcement overreach, inadequate Health and Human Services input, and hindrance of research. This paper reaffirms the importance of a class‐based scheduling strategy while also arguing for increased research of schedule I controlled substances.

Autoerotic death is defined as an accidental death that occurs when some type of apparatus is used to enhance sexual stimulation and causes an unintended death. We present the case of an atypical autoerotic death of a 23-year-old man found deceased in a bathroom. An electrical cord with a standard wall plug on one end and exposed wires twisted into loops on the other end was on the floor near his body. Minute black burns were present on each nipple. The outlet was protected by a ground fault circuit interrupter that was demonstrated to be in working order. An electrical consultant concluded that the cause of death could not be electrocution. Ground fault circuit interrupters work by detecting differences in current within a circuit. If a ground fault occurs, the circuit is broken to prevent a fatal electrocution. In the present case, the ground fault circuit interrupter did not shut off because the decedent had wired himself in parallel with the circuit. This, with the other scene findings, indicated this to be a case of atypical autoerotic death. Autoerotic deaths by means other than asphyxiation are rare. This case serves to illustrate the circumstances of an atypical autoerotic death by means of electrocution.

The eastern barn owl (Tyto delicatula) is a significant native predator of small mammals in Australia. Regurgitated pellets can provide important data on species presence, current or historical changes in mammal fauna over time, or data on cryptic or threatened species. We collected 125 pellets from Cravens Peak reserve, Simpson Desert, Queensland, and examined the contents, including changes in diet over time (using age of pellet as a proxy) and the relative importance of different prey. In total, 642 unique prey items were recorded, 92% of which were mammals. Small rodents were the dominant prey – Mus musculus and Pseudomys hermannsburgensis, and the presence of Notomys cf. fuscus, Pseudantechinus cf. mimulus and Dasycercus blythi were all significant, being range extensions. Such data add to more traditional or novel techniques to record community changes over time.

The black‐tailed dusky antechinus (Antechinus arktos) is a recently discovered, endangered, carnivorous marsupial mammal endemic to the Tweed Shield Volcano caldera, straddling the border between Queensland and New South Wales in eastern Australia. The species' preference for cool, high‐altitude habitats makes it particularly vulnerable to a shifting climate as these habitats recede. Aside from basic breeding and dietary patterns, the species' ecology is largely unknown. Understanding fine‐scale habitat attributes preferred by this endangered mammal is critical to employ successful conservation management. Here, we assess vegetation attributes of known habitats over three sites at Springbrook and Border Ranges National Parks, including detailed structure data and broad floristic assessment. Floristic compositional assessment of the high‐altitude cloud rainforest indicated broad similarities. However, only 22% of plant species were shared between all sites indicating a high level of local endemism. This suggests a diverse assemblage of vegetation across A. arktos habitats. Habitat characteristics were related to capture records of A. arktos to determine potential fine‐scale structural habitat requirements. Percentage of rock cover and leaf litter were the strongest predictors of A. arktos captures across survey sites, suggesting a need for foraging substrate and cover. Habitat characteristics described here will inform predictive species distribution models of this federally endangered species and are applicable to other mammal conservation programs., The black‐tailed dusky antechinus (Antechinus arktos) is a recently discovered, endangered carnivorous marsupial mammal endemic to the border between Queensland and New South Wales in eastern Australia. The species' preference for cool, high‐altitude habitats makes it particularly vulnerable to a shifting climate. Here, we assess vegetation attributes of known habitats over three sites at Springbrook and Border Ranges National Parks, including detailed structure data and broad floristic assessment.

Plantar plate tears are a common cause of forefoot pain and digital deformity. Repair of the plantar plate has been described from both a dorsal and plantar approach, each with its own benefits and drawbacks. Many of the approaches use costly devices. Our innovative repair method uses low-cost materials available in most operating room settings. We undertook a retrospective case series study to evaluate outcomes in patients who had undergone plantar plate repair with our method of repair. A review was performed to identify patients with plantar plate disruptions treated with this approach by a single surgeon. Clinical position and patient satisfaction of the involved joints were evaluated. Six patients (9 joints) underwent plantar plate repair using this innovative method and were evaluated at a median follow-up time of 19 (range 19 to 39) months. The mean visual analog scale pain score at final follow up was 0.8 ± 2.0. The median sagittal plane position of the toe was 2 mm (range 0 to 6) from the plantar skin of the digit to the ground. Five of the 6 patients (83%) stated that they would have the procedure again. We were able to obtain satisfactory outcomes with good alignment by repairing the plantar plate with this innovative method. Our data suggest that the described method of plantar plate repair can be used as an effective way to treat metatarsal phalangeal joint instability.

There are more than 100 species of American didelphid marsupials (opossums and mouse opossums). Limited genomic resources for didelphids exists, with only two publicly available genome assemblies compared with dozens in the case of their Australasian counterparts. This discrepancy impedes evolutionary and ecological research. To address this gap, we assembled a high-quality chromosome-level genome of the agile gracile mouse opossum (Gracilinanus agilis) using a combination of stLFR sequencing, polishing with mate-pair data, and anchoring onto pseudochromosomes using Hi-C. This species employs a rare life-history strategy, semelparity, and all G. agilis males and most females die at the end of their first breeding season after succumbing to stress and exhaustion. The 3.7-Gb chromosome-level assembly, with 92.6% anchored onto pseudochromosomes, has a scaffold N50 of 683.5 Mb and a contig N50 of 56.9 kb. The genome assembly shows high completeness, with a mammalian BUSCO score of 88.1%. Around 49.7% of the genome contains repetitive elements. Gene annotation yielded 24,425 genes, of which 83.9% were functionally annotated. The G. agilis genome is an important resource for future studies of marsupial biology, evolution, and conservation.

The 15 species of small carnivorous marsupials that comprise the genus Antechinus exhibit semelparity, a rare life-history strategy where death occurs after one breeding season. Antechinus males, but not females, age rapidly (demonstrate organismal senescence) during the breeding season and show promise as new animal models of ageing. Some antechinus species are also threatened or endangered. Here, we report chromosome-level genomes of the yellow-footed antechinus Antechinus flavipes. The genome assembly has a total length of 3.2 Gb with a contig N50 of 51.8 Mb and a scaffold N50 of 636.7 Mb. We anchored and oriented 99.7% of the assembly on seven pseudochromosomes and found that repetitive DNA sequences occupy 51.8% of the genome. Draft genome assemblies of three related species in the subfamily Phascogalinae, two additional antechinus species (A. argentus and A. arktos) and the iteroparous sister species Murexia melanurus were also generated. Preliminary demographic analysis supports the hypothesis that climate change during the Pleistocene isolated species in Phascogalinae and shaped their population size. A transcriptomic profile across the A. flavipes breeding season allowed us to identify genes associated with aspects of the male die-off. The chromosome-level A. flavipes genome provides a steppingstone to understanding an enigmatic life-history strategy and a resource to assist the conservation of antechinuses.

In this study, we report the mitochondrial genome of the black-tailed antechinus (Antechinus arktos), a recently-discovered, endangered carnivorous marsupial inhabiting a caldera that straddles the...

Cerium enhances the durability of polymer electrolyte membrane (PEM) fuel cells by scavenging reactive radical species which are generated during operation. However, during cell fabrication, conditioning, discharge, and during fuel cell operation, Ce dissolves and is transported within the membrane-electrode-assembly (MEA) due to gradients in ionic potential (migration),1–3 ionic concentration (diffusivity),1,4 and ionomer hydration (convection).5,6 Ce migration is detrimental because (i) its accumulation in the CL ionomer can diminish the electrode’s proton conductivity, which results in sub-optimal performance, especially at high current density7,8; and (ii) its depletion may leave an ionomer region more susceptible to radical attack. Therefore, it is necessary to quantify these transport mechanisms under a range of operating conditions in order to understand their effects on cell performance/durability and determine the necessity of further Ce stabilization. To understand the effects of potential gradients and relative humidity (RH) on Ce migration, ex situ experiments were performed using Nafion™ NR-211 (Ion Power, Inc.) which was doped in-house using Ce(III) nitrate to ~5% ion-exchanged Ce. PEM specimens were operated in 4-electrode H2 pump mode in a standard conductivity cell (Scribner Associates) under a range of temperatures and RHs. The evolution of Ce profiles as a function of charge transfer was quantified using X-ray fluorescence, which were fit using our previously-developed transient, 1-D transport model in order to decouple the competing effects of migration and diffusion.1 The model was updated to capture convection due to hydration gradients, as well as variations in λ (defined as nH2O/nSO3 -) and conductivity as a function of Ce exchange fraction. As shown in Figure 1a, diffusion experiments performed in the absence of potential gradients showed excellent agreement with simultaneous 2-parameter migration and diffusivity fitting of a single migration experiment, validating the efficiency and effectiveness of this technique. Figure 1 shows modeled values for (a) diffusivity and (b) migration over a range of temperatures and λs. Convection experiments were also conducted using a differential RH cell, adapted from the GM/Giner design.9 Since no potential gradient is present here, the convection coefficients were fit by employing the isothermal diffusivity-λ relations determined from the H2 pump experiments. Results of all three transport coefficients will be presented over a range of relevant operating conditions and 2-D cell model results demonstrating the impact on cell performance will be discussed. The findings of these studies may also be analogously applied to Co and Fe cations, which dissolve from Pt-Co electrocatalysts and system balance of plant components, respectively, and are expected show transport characteristics in PFSA. Acknowledgement: This research is supported by the U.S. Department of Energy Fuel Cell Technologies Office, through the Fuel Cell Performance and Durability (FC-PAD) Consortium (Fuel Cells Program Manager: Dimitrios Papageorgopoulos and Technical Development Manager: Greg Kleen). References A. M. Baker, S. K. Babu, R. Mukundan, S. G. Advani, A. K. Prasad, D. Spernjak, and R. L. Borup, J. Electrochem. Soc., 164, 1272–1278 (2017). A. M. Baker, D. Torraco, E. J. Judge, D. Spernjak, R. Mukundan, R. L. Borup, S. G. Advani, and A. K. Prasad, ECS Trans., 69, 1009–1015 (2015). Y. Cai, J. M. Ziegelbauer, A. M. Baker, W. Gu, R. S. Kukreja, A. Kongkanand, M. F. Mathias, R. Mukundan, and R. L. Borup, J. Electrochem. Soc., 165, F3132–F3138 (2018). F. D. Coms and A. B. McQuarters, ECS Trans., 86, 395–405 (2018). A. M. Baker, R. Mukundan, D. Spernjak, E. J. Judge, S. G. Advani, A. K. Prasad, and R. L. Borup, J. Electrochem. Soc., 163, F1023–F1031 (2016). Y.-H. Lai, K. M. Rahmoeller, J. H. Hurst, R. S. Kukreja, M. Atwan, A. J. Maslyn, and C. S. Gittleman, J. Electrochem. Soc., 165, F3217–F3229 (2018). D. Banham, S. Y. Ye, T. Cheng, S. Knights, S. M. Stewart, M. Wilson, and F. Garzon, J. Electrochem. Soc., 161, F1075–F1080 (2014). E. L. Redmond, S. M. Wriston, and J. L. Szarka III, ECS Trans., 80, 633–641 (2017). S. Kumaraguru, "Durable High Power Membrane Electrode Assembly with Low Pt Loading," Fuel Cell R&D Annual Merit Review Proceedings, (2018). Figure 1

Abstract Fuel cells have potential for small power applications that require long periods, as much as several decades, of uninterrupted power. Small microwatt fuel cell stacks of varying membrane thickness were designed to allow for passive water management. The passive water management system was incorporated into the stack design by use of exposed Nafion membrane for lateral water transport. 1 An experimental and theoretical study of water management across the operating temperature range was conduction, including operando neutron imaging and the development of a multiphysics two-dimensional model. Stack testing was done between -55 °C to 85 °C using a baseline output current of 10 µA and periodic pulses of 4.5 mA lasting 100 ms, every 100 s, or an average current of 16 µA. The stack spatial water concentration was monitored during various operating conditions through in situ neutron imaging. Figure 1 shows the main points of interest on the stack. Operating temperatures ranged from -55 °C to 85 °C to analyze water formation and subsequent water removal. Freezing and below-freezing temperatures were controlled by use of a liquid nitrogen cooled series of insulated boxes to prevent external water condensation during imaging. These measurements suggest successful water transport laterally, enabling operation from the sub-freezing environment to temperatures near the boiling point of water. Figure 2a depicts a constant operation for two hours at 16 µA and -20 ºC and the subsequent drying process in Figure 2b. Water production due to gas crossover in the stacks was quantified at below-freezing temperatures. At temperatures at and below -20 °C, the water production due to gas crossover was greater than the amount of water removal via the passive water management strategy with the current turned off, rather than a drying of the cell as expected. With the gases turned off as well, drying occurs. This indicates that the cell design must allow for water (ice) build-up during operation at these sub-freezing temperatures for successful operation. To avoid large amounts of hydrogen loss due to membrane crossover, we employ multiple layers of membrane to make a thick, mechanically reinforced and chemically stabilized membrane. A two-dimensional multiphysics model for evaluation of water management was also developed to further describe and explore the passive water management system under different conditions. The fundamental model in its present form shows a similar shape but indicates faster water build-up than experimental data. This discrepancy is currently being resolved to allow for a more accurate representation. Acknowledgments: This work was supported by the U.S. Department of Energy. References: Chintam, M. S. Wilson, T. Rockward, S. Stariha, A. M. Baker, E. L. Brosha, D. S. Hussey, J. M. LaManna, D. L. Jacobson, J. Rau, R. L. Borup, ECS Transactions 86 (13), 233-244. Figure 1

Since 2012 the number of recognized taxa in the Australian carnivorous marsupial genus Antechinus has increased from 10 to 15 species. The systematic relationships among these species and others in the genus are not well resolved. We undertook the first comprehensive, molecular systematic analysis of the genus, incorporating all known species and subspecies of Antechinus. Two mitochondrial (mtDNA) and four autosomal nuclear genes were sequenced. Four clades of Antechinus were consistently reconstructed in the concatenated and mtDNA analyses: (1) dusky antechinuses (A. arktos, A. swainsonii, A. vandycki and A. mimetes) and A. minimus; (2) A. godmani; (3) A. agilis, A. stuartii and A. subtropicus; (4) A. argentus, A. mysticus, A. adustus, A. flavipes, A. leo and A. bellus. The inclusion of A. adustus in clade 4 is surprising, because previous morphology-based studies suggested it was a member of clade 3. However, analysis of the nuclear dataset and multi-species coalescence analysis did not separate clades 3 and 4. Within clade 3, A. stuartii is not monophyletic and may be more appropriately classified as two species. Timing of cladogenesis is estimated for all 15 species of Antechinus, permitting us to posit an evolutionary scenario for the group. BEAST analysis dated the divergence of Antechinus from extant congeners to the Late Miocene and cladogenesis among all extant Antechinus to the Plio-Pleistocene. Wet, closed habitat was reconstructed as the most probable ancestral state for the genus Antechinus and the four main Antechinus clades. Overall, increasing aridity from the Miocene to the Pleistocene and a number of well-known biogeographic barriers to mesic species, appear to have driven speciation in Antechinus.

Taxonomic distinction of species forms the foundation of biodiversity assessments and conservation priorities. However, traditional morphological and/or genetics-based taxonomic assessments frequently miss the opportunity of elaborating on the ecological and functional context of species diversification. Here, we used 3D geometric morphometrics of the cranium to improve taxonomic differentiation and add eco-morphological characterisation of a young cryptic divergence within the marsupial carnivorous genusAntechinus. Specifically, we used 168 museum specimens to characterise the recently proposed cladesA. stuartii“south”,A. stuartii“north” andA. subtropicus. Beyond slight differences attributable to overall size (and therefore not necessarily diagnostic), we also found clear allometry-independent shape variation. This allowed us to define new, easily measured diagnostic traits in the palate, which differentiate the three clades. Contrary to previous suggestions, we found no support for a latitudinal gradient as causing the differentiation between the clades. However, skull shape co-varied with temperature and precipitation seasonality, suggesting that the clades may be adapted to environmental variables that are likely to be impacted by climate change. Our study demonstrates the use of 3D geometric morphometrics to improve taxonomic diagnosis of cryptic mammalian species, while providing perspectives on the adaptive origins and potential future threats of mammalian diversity.

The diversity and endemism of Australian Tanypodinae (Diptera: Chironomidae) has been unclear from morphological comparisons with well-grounded northern hemisphere taxonomy. As part of a comprehensive study, here we focus on one of the few described endemic genera, Yarrhpelopia Cranston. Extensive and intensive new sampling and newly-acquired molecular data provides clarity for the type species, Yarrhpelopia norrisi Cranston and allows recognition of congeners and potential sister group(s). We describe Yarrhpelopia acorona Cranston & Krosch sp. n., and we recognise a third species from Western Australia, retaining an informal code ‘V20’ due to inadequate reared / associated material for formal description. We recognise a robust clade Coronapelopia Cranston & Krosch gen. n., treated as a genus new to science for two new species, Coronapelopia valedon Cranston & Krosch sp. n. and Coronapelopia quadridentata Cranston & Krosch sp. n., from eastern Australia, each described in their larval and pupal stages and partial imaginal stages. Interleaved between the independent new Australian clades Yarrhpelopia and Coronapelopia are New World Pentaneura and relatives, that allow a tentative inference of a dated gondwanan (austral) connection. Expanded sampling indicates that Y. norrisi, although near predictably present in mine-polluted waters, is not obligate but generally indicates acidic waters, including natural swamps and Sphagnum bogs. The inferred acidophily, including in drainages of mine adits, applies to many taxa under consideration here.

In this study, we report the mitochondrial genome of the black-tailed antechinus (Antechinus arktos), a recently-discovered, endangered carnivorous marsupial inhabiting a caldera that straddles the border of Australia’s mid-east coast. The circular A. arktos genome is 17,334 bp in length and has an AT content of 63.3%. Its gene content and arrangement are consistent with reported marsupial mitogenome assemblies.

Perfluorosulfonic acids (PFSAs) are commonly used as solid polymer electrolyte membranes (PEMs) in electrochemical energy devices, where they are vulnerable to attack by radical species during operation. A popular strategy to combat this problem is to introduce radical scavengers like cerium (Ce) ions that neutralize these species before they attack the PFSA. Such cation doping creates a multi-ion system, in which understanding the mechanisms of cation solvation and transport becomes important for the effective design and utilization of PFSA-cation systems. Ce ions also provide a representative model system for multication-exchanged ionomers in electrochemical systems. In this study, hydration and conductivity measurements, along with X-ray fluorescence and scattering, are employed to elucidate how Ce ion exchange alters PFSA's ionic solvation, as well as nano- and mesoscale morphologies, which ultimately control its ion transport properties. A molecular transport model is used to deconvolute the impact of Ce ions on the local solvation structure of water in the membrane from mesoscale changes of the transport pathways. The combined experimental and theoretical analysis reveals a nonlinear decrease in conductivity driven by cation solvation at the molecular level and morphological changes at longer length scales. Migration-diffusion coupling, its nonlinear dependence on ion exchange and hydration, and its overall implications for ionomer performance are also discussed. These findings have the potential to be translated into other mixed cation-ionomer systems for a wide range of energy and environmental devices.

The non-biting midge subfamily Tanypodinae (Diptera: Chironomidae) is species-rich, ecologically diverse, and near-globally distributed. Within the subfamily, aspects of generic and species-level taxonomy remain poorly understood, in particular the validity of assignment of Australian and New Zealand taxa to genera erected for northern hemisphere (Holarctic) fauna. Here, we place the austral diversity within this global context by extensive geographical and taxonomic sampling in concert with a multilocus phylogenetic approach. We incorporated sequence data for mitochondrial COI, and nuclear 28S and CAD, and conducted Bayesian and maximum likelihood phylogenetic inferences and Bayesian divergence time estimation. The resolved phylogeny supported many associations of Australian taxa with their proposed Holarctic congeners, with the exception of Apsectrotanypus Fittkau, and validates several taxa as endemic. Three of four New Zealand sampled taxa had their sister groups in Australia; New Zealand Monopelopia Fittkau was sister to a German congener. This included the first record of Procladius Kieffer from New Zealand. Most nodes connecting austral and Holarctic taxa clustered around the Cretaceous-Tertiary boundary (60-80 mya), whereas New Zealand-Australia nodes were generally slightly younger (53-57 mya). Together, these data contribute substantially to our understanding of the taxonomy, systematics and biogeography of the Australian Tanypodinae and more broadly to knowledge of Australia’s aquatic insect biodiversity.

Five new species within the Australian carnivorous marsupial genus Antechinus have recently been named, at least two of which are threatened. Important facets of the habitat use and extinction risk of one of these new species, the buff‐footed antechinus, A. mysticus, are not well understood. Previous research has suggested that the species utilizes a broad range of inter‐connected forest habitats in southeast Queensland (Qld), Australia. Based on this potentially connected habitat, we predicted that A. mysticus should have low population genetic structure, particularly in relation to its congener, the spatially restricted, high altitude, closed‐forest A. subtropicus. We genotyped nine microsatellite loci for six populations of A. mysticus, sampled throughout their known range in eastern Australia, and compared them with four proximate populations of A. subtropicus. Surprisingly, genetic structuring among southeast Qld populations of A. mysticus was moderate to high and similar to that between A. subtropicus populations. We postulate that all A. mysticus populations have declined recently (

Micro- to milli-watt fuel cell stacks and systems are designed and tested for applications that require continuous operation for multiple decades and at very wide ambient temperature ranges. Development presumes generic load profiles consisting of small baseline currents with frequent, periodic excursions to higher currents, both delivered at the 3.3 V standard integrated circuit voltage level. Stack design and testing was done between -55˚C to 80˚C using a baseline output current of 10 uA and periodic pulses of 4.5 mA lasting 100 ms, every 100 s. To simplify testing, the stacks are paired with 3.3V output miniature dc-dc converters to supply the respective 33 uW and 15 mW power requirements, with the stack then initially providing about 40 uW and 17 mW reflecting the converter efficiencies at the two sets of output currents/input voltages. Since maximum cell power tends to occur at >0.5 V/cell, 8-cell stacks were chosen so that, if called upon, the maximum power point still exceeds the ~4 V minimum buck converter input. Concerns about air availability and purity impel the use of H2 & O2 reactants; accommodating the fittings and other design constraints lead to a 13x19mm footprint (active area = 0.2 cm2), as shown in Figure 1. Since the stack reactant supplies are “dead-ended”, provision needs to be made to remove product water. In contrast to typical (higher power) fuel cell applications, the primary system challenges with the microwatt system are reactant cross-over and leakage current. As an example of the severity of the issue, a 2020 technical target1 for membrane leakage current is an equivalent DC resistance of 1000 Wcm2. A similar value in this case would yield a cumulative leakage current of about 1.4 mA, causing an otherwise 30 y reactant supply for this system to last less than a year. Moreover, cross-over losses are generally hand-in-hand with leakage. The simple straightforward solution is to use thick membranes, done here primarily by stacking multiple layers of DuPont XL, which provides the benefits of radical scavengers and PTFE reinforcement scrims to enhance long-term chemical and dimensional stability. Other loss mitigation configurations and strategies are being pursued in tandem. The need to provide 17 mW pulses not only limits the maximum membrane thicknesses (and stack resistances), but subjects the individual cells to voltage cycles between about 0.6V and OCV, similar to a catalyst durability AST (accelerated stress test). These issues can be alleviated by pairing the stack with a supercapacitor to minimize the voltage swings during the 17 mW pulses, thus allowing the stack to supply a fairly constant 65 uW (accounting for converter efficiency). Consequently, life and environmental testing are underway to demonstrate the utility of the configuration, but the preferred goal is to achieve the desired results without introducing additional components with potential lifetime and temperature range issues. Long-term room temperature life-testing is underway on stacks with and without supercaps. As of March 2018, a stack subjected to the full 17 mW pulses is approaching 5000 h of operation and has shown little if any drop in performance beyond an initial modest decline. A second stack paired with supercaps has been in operation nearly as long and likewise shows minimal sustained losses, even though it is being subjected to 10x the standard pulse rate. Environmental chamber testing has demonstrated prolonged operation at temperatures ranging from -40˚ to 80˚C. Stack resistance decreases between room and high (80˚C) temperatures, overtly because the proton transport kinetics are enhanced in the already extremely dry membranes. While such dry operation was believed warranted to avoid product water freezing in the catalyst layer causing transport issues, the ability of the stacks to provide 17 mW pulses is challenged by the high stack resistance. Consequently, we have begun investigating the degree to which we can allow water content to increase while maintaining reactant access. Additional future efforts include environmental testing down to -55˚C and further stack design evolution to improve performance and functionality. Figure 1. An 8-cell stack with nitrided titanium bipolar and endplates. Reference 1 DOE Technical Targets for Polymer Electrolyte Membrane Fuel Cell Components. https://www.energy.gov/eere/fuelcells/doe-technical-targets-polymer-electrolyte-membrane-fuel-cell-components Figure 1

The effect of film thickness on water uptake and structure in ultra-thin Nafion is probed via in situ neutron reflectometry for a series of 10 films with thicknesses ranging from 5 to 153 nm. Observed interfacial lamellae are used to understand anomalous transport limitations in such films. Results show three distinct thickness regimes: (i) in the truncated regime (

In this study, we report the mitochondrial genome of the black-tailed dasyure (Murexia melanurus) of New Guinea. The circular genome is 17,736 bp in length and has an AT content of 60.5%. Its gene content – 13 protein-coding genes (PCGs), 2 ribosomal (rRNA) genes, 21 transfer RNA (tRNA) genes, a tRNA pseudogene (tRNALys), and a non-coding control region (CR) – and gene arrangement are consistent with previous marsupial mitogenome assemblies.

Antechinus are one of just a few mammal genera worldwide which exhibit semelparous reproduction. Consequently, the life history of many antechinus has been well studied. However, in the last few years, several new species have been described in the genus and their ecology is little known. Here, the first multi-year ecological study of breeding, growth and movement in one of these species, the buff-footed antechinus, Antechinus mysticus, was undertaken. Over a 2-year period, monthly capture-mark-recapture data from two geographically close sites (~2.5 km apart) in south-east Queensland, Australia, were collected. At one site, the subtropical antechinus, Antechinus subtropicus, also occurred. This allowed the investigation of possible competitive effects between this larger Antechinus species and A. mysticus. Intensive trapping across the breeding season of A. mysticus also allowed the growth rates of pouch young of a wild antechinus population to be calculated for the first time. Results showed that A. mysticus followed the synchronous, semelparous breeding strategy seen in all congeners. Male A. mysticus were last caught in August, and females gave birth in September. Average distance moved by A. mysticus was comparable with congeners. Competition with A. subtropicus may affect A. mysticus because A. mysticus weighed more and males moved further when not in sympatry with A. subtropicus. However, female A. mysticus moved further when in sympatry with A. subtropicus, confounding clear interpretation. Overall, the life history information obtained for A. mysticus provides a foundation for further research and will aid the conservation management of this new species.

Doped ceria compounds demonstrate excellent radical scavenging abilities and are promising additives to improve the chemical durability of polymer electrolyte membrane (PEM) fuel cells. In this work, Ce0.85Zr0.15O2 (CZO) nanoparticles were incorporated into the cathode catalyst layers (CLs) of PEM fuel cells (based on Nafion XL membranes containing 6.0 μg cm−2 ion-exchanged Ce) at loadings of 10 and 55 μg cm−2. When compared to a CZO-free baseline, CZO-containing membrane electrode assemblies (MEAs) demonstrated extended lifetimes during PEM chemical stability accelerated stress tests (ASTs), exhibiting reduced electrochemical gas crossover, open circuit voltage decay, and fluoride emission rates. The MEA with high CZO loading (55 μg cm−2) demonstrated performance losses, which are attributed to Ce poisoning of the PEM and CL ionomer regions, which is supported by X-ray fluorescence (XRF) analysis. In the MEA with the low CZO loading (10 μg cm−2), both the beginning of life (BOL) performance and the performance after 500 hours of ASTs were nearly identical to the BOL performance of the CZO-free baseline MEA. XRF analysis of the MEA with low CZO loading reveals that the BOL PEM Ce concentrations are preserved after 1408 hours of ASTs and that Ce contents in the cathode CL are not significant enough to reduce performance. Therefore, employing a highly effective radical scavenger such as CZO, at a loading of 10 μg cm−2 in the cathode CL, dramatically mitigates degradation effects, which improves MEA chemical durability and minimizes performance losses.

The silver-headed antechinus, A. argentus, is a recently-discovered, threatened carnivorous marsupial known from only two small, isolated montane populations within central-eastern Queensland, Australia. Here, we present the first study of the species’ life-history characteristics. Antechinuses are well-known for their spectacular annual male die-off at the close of a one- to three-week mating period. The genus also displays sexual dimorphism for size—with males up to three times heavier than females. The A. argentus population we studied at Kroombit Tops National Park over 2 years fitted the norm for the genus, with strong evidence of both a synchronised male die-off (in June/July) and significantly larger males than females. We surveyed two proximate sites at Kroombit Tops where A. argentus was previously known to occur. Unexpectedly, there was a marked difference in A. argentus numbers between years and sites. We hypothesise that the disparate capture rates between sites may be at least in part linked to the effects of fire on vegetation. The marked fluctuation in capture numbers between years, coupled with annual male die-off raises concerns over the future of the Kroombit Tops population of this threatened mammal.

To increase the commercialization of fuel cell electric vehicles, it is imperative to improve the activity and performance of electrocatalysts through combined efforts focused on material characterization and device-level integration. Obtaining fundamental insights into the ongoing structural and compositional changes of electrocatalysts is crucial for not only transitioning an electrode from its as-prepared to functional state, also known as "conditioning", but also for establishing intrinsic electrochemical performances. Here, we investigated several oxygen reduction reaction (ORR) electrocatalysts via in situ and ex situ characterization techniques to provide fundamental insights into the interfacial phenomena that enable peak ORR mass activity and high current density performance. A mechanistic understanding of a fuel cell conditioning procedure is described, which encompasses voltage cycling and subsequent voltage recovery (VR) steps at low potential. In particular, ex situ membrane electrode assembly characterization using transmission electron microscopy and ultra-small angle X-ray scattering were performed to determine changes in carbon and Pt particle size and morphology, while in situ electrochemical diagnostics were performed either during or after specific points in the testing protocol to determine the electrochemical and interfacial changes occurring on the catalyst surface responsible for oxygen transport resistances through ionomer films. The results demonstrate that the voltage cycling (break-in) step aids in the removal of sulfate and fluoride and concomitantly reduces non-Fickian oxygen transport resistances, especially for catalysts where Pt is located within the pores of the carbon support. Subsequent low voltage holds at low temperature and oversaturated conditions, i.e., VR cycles, serve to improve mass activities by a factor of two to three, through a combined removal of contaminants, surface-blocking species (e.g., oxides), and rearrangement of the catalyst atomic structure (e.g., Pt-Pt and Pt-Co coordination).

Although mammalian tail length relative to body length is considered indicative of locomotor mode, this association has been difficult to quantify. This could be because the counterweight function of the tail might associate it more with body weight than body length. Alternatively, relative tail length might not be evolutionarily flexible owing to its integration with the remaining skeleton, particularly the spine. Using comparative analyses of morphological means and ranges in Australian marsupials, including the first co-assessment with body weight, our study supports the second hypothesis, i.e. tail length ranges within species, and tail lengths among species are explained better by body length than by body weight. However, all three variables do not differ in phylogenetic signal or rates of evolution. Associations of tail lengths with locomotion are limited, but suggest that scaling slopes, rather than intercepts, are responsible for limited divergence between relative tail lengths at different locomotor modes. This complicates (palaeo-)ecological interpretations of tail length further. We conclude that relative tail length is not a strong predictor of locomotor mode, probably owing to strong integration of tail and body length. The many well-documented bony and soft-tissue adaptations of tails are likely to be better suited to interpretations of locomotor adaptations.

Ceria nanoparticles (NPs) have unique catalytic properties which make them suited to scavenge degrading radical species and their precursor peroxides during PEM fuel cell operation. However, in the acidic environment of the fuel cell, ceria dissolves and the resulting cations migrate within the MEA, causing performance and durability losses. In this work, ex situ testing was used to evaluate the peroxide decomposition, selectivity towards radical generation, and solubility of Gd, Pr, and Zr-doped ceria NPs over a range of crystallite sizes and dopant levels. These doped materials exhibit better peroxide scavenging activity and dissolution resistance than undoped ceria. In these materials, activity is largely governed by increased surface area due to high internal porosity at smaller crystallite sizes compared to undoped ceria. Of the compounds tested, ceria NPs doped with 15 at% Zr (10 nm) and 5 at% Pr (17 nm) exhibited greater dissolution resistance than undoped ceria. Stabilization of the former doped NPs is attributed to crystallite agglomeration, while the increased stability of the latter is proposed to be due to its internally-porous, mesoscale structure suggested by its sorption isotherm. Both materials are more dissolution-resistant and active peroxide decomposers compared to undoped ceria but exhibit increased byproduct radical generation.

The carnivorous marsupial Antechinus are one of the few mammal genera known to exhibit the phenomenon of semelparous reproduction, where all males die at the end of a frenetic annual mating period. The genus Antechinus has recently been revised, seeing four new species named and one existing subspecies raised to species status. Here, we present the first ecological assessment of one new species, the endangered black-tailed dusky antechinus (Antechinus arktos), based on a 2-year mark-recapture study of two proximate sites within the cloud forest of Springbrook National Park, south-east Queensland, Australia. We also present comparative ecological data from a sympatric congener, Antechinus stuartii. In total, 103 A. arktos (49 male; 54 female) and 2125 A. stuartii (1229 male; 896 female) captures were made over 16,630 trap nights at the two sites. The occurrence and synchrony of reproductive events observed in A. arktos closely parallel the semelparous reproductive strategy exhibited by all congeners studied to date. The A. arktos populations mate during mid-September, with birth of up to six young occurring during mid-October. The low abundance and fecundity, together with a limited and apparently retracting distribution, suggest A. arktos is under threat of climate-induced extinction in the coming decades.

Cerium is a radical scavenger which improves polymer electrolyte membrane (PEM) fuel cell durability. During operation, however, cerium rapidly migrates in the PEM and into the catalyst layers (CLs). In this work, membrane electrode assemblies (MEAs) were subjected to accelerated stress tests (ASTs) under different humidity conditions. Cerium migration was characterized in the MEAs after ASTs using X-ray fluorescence. During fully humidified operation, water flux from cell inlet to outlet generated in-plane cerium gradients. Conversely, cerium profiles were flat during low humidity operation, where in-plane water flux was negligible, however, migration from the PEM into the CLs was enhanced. Humidity cycling resulted in both in-plane cerium gradients due to water flux during the hydration component of the cycle, and significant migration into the CLs. Fluoride and cerium emissions into effluent cell waters were measured during ASTs and correlated, which signifies that ionomer degradation products serve as possible counter-ions for cerium emissions. Fluoride emission rates were also correlated to final PEM cerium contents, which indicates that PEM degradation and cerium migration are coupled. Lastly, it is proposed that cerium migrates from the PEM due to humidification conditions and degradation, and is subsequently stabilized in the CLs by carbon catalyst supports.

Variation in life-history strategies has usually been characterized as a single fast–slow continuum of life-history variation, in which mean lifespan increases with age at maturity as reproductive output at each breeding event declines. Analyses of plants and animals suggest that strategies of reproductive timing can vary on an independent axis, with iteroparous species at one extreme and semelparous species at the other. Insectivorous marsupials in the Family Dasyuridae have an unusually wide range of life-history strategies on both purported axes. We test and confirm that reproductive output and degree of iteroparity are independent in females across species. Variation in reproductive output per episode is associated with mean annual rainfall, which predicts food availability. Position on the iteroparity-semelparity axis is not associated with annual rainfall, but species in regions of unpredictable rainfall have longer maximum lifespans, more potential reproductive events per year, and longer breeding seasons. We suggest that these two axes of life-history variation arise because reproductive output is limited by overall food availability, and selection for high offspring survival favours concentrated breeding in seasonal environments. Longer lifespans are favoured when reproductive opportunities are dispersed over longer periods in environments with less predictable food schedules.

Author(s): Mukundan, R; Baker, AM; Kusoglu, A; Beattie, P; Knights, S; Weber, AZ; Borup, RL | Abstract: A combined chemical/mechanical accelerated stress test (AST) was developed for proton exchange membrane (PEM) fuel cells based on relative humidity cycling (RHC) between dry and saturated gases at open circuit voltage (OCV). Membrane degradation and failure were investigated using scanning electron microscopy and small- and wide-angle X-ray scattering. Changes to membrane thickness, hydrophilic domain spacing, and crystallinity were observed to be most similar between field-operated cells and OCV RHC ASTs, where local thinning and divot-type defects are the primary failure modes. While RHC in air also reproduces these failure modes, it is not aggressive enough to differentiate between different membrane types in g1,333 hours (55 days) of testing. Conversely, steady-state OCV tests result in significant ionomer morphology changes and global thinning, which do not replicate field degradation and failure modes. It is inferred that during the OCV RHC AST, the decay of the membrane’s mechanical properties is accelerated such that materials can be evaluated in hundreds, instead of thousands, of hours, while replicating the degradation and failure modes of field operation; associated AST protocols are recommended as OCV RHC at 90◦C for 500 hours with wet/dry cycle durations of 30s/45s and 2m/2m for automotive and bus operation, respectively.