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Context: In this study, single-nucleotide polymorphisms (SNPs) were used to investigate kinship for the green sawfish (Pristis zijsron). Aims: To examine the relatedness of P. zijsron across an expansive coastline in Western Australia. Methods: Sampling was conducted between the Fitzroy River estuary and Bay of Rest in the eastern Indian Ocean (north-western Australia) between 2003 and 2022. SNPs were generated from tissues collected from 137 live and 1 recently deceased P. zijsron. Key results: Overall, 62 individual P. zijsron were assigned to 25 litters of full siblings, with litter sizes ranging from 2 to 5 pups, and 76 P. zijsron individuals were assigned to 96 half sibling pairwise relationships. Four pairs of half siblings were captured more than 500 km and born at least 6 years apart, including one pair of neonates captured ~870 km and 8 years apart, in the Ashburton River estuary (Pilbara) and Cable Beach (Broome). Furthermore, a pair of full-sibling pups (i.e. young of the year) caught at Cape Keraudren (Pilbara) in 2008 were half siblings of a pup caught in the Ashburton River in 2014. Conclusions: This study provides evidence of long-distance, likely parental, movement of P. zijsron. Implications: Dispersal of P. zijsron over large spatial scales indicates that populations could be replenished from elsewhere should they experience a decline, thereby reducing the risk of localised extinction for this species. Kinship for green sawfish was inferred from single-nucleotide polymorphisms. We identified four pairs of half siblings that were captured at least 500 km apart, including one pair of neonates captured ~860 km and 8 years apart, providing evidence of long-distance movement. [ABSTRACT FROM AUTHOR]

Soft robots and wearable technologies benefit significantly from stretchable batteries, yet the rigid nature of high‐capacity electrodes creates large trade‐offs in battery performance and stretchability. This study introduces a new approach for realizing stretchable batteries by allowing the electrodes to slide along a stretchable electrolyte. When the sliding‐electrodes battery is stretched, the forces are transmitted through the hydrogel electrolyte and elastomeric enclosure, while the rigid electrodes slide relative to the hydrogel to maintain interfacial contact. The sliding‐electrodes approach allows 100% of the unstretched battery area to be covered by thick electrodes so that the battery areal capacity and power are improved by up to 10X of prior stretchable designs. Three metal‐air batteries achieve areal capacities of up to 104 mWh cm−2. Further mechanical testing, electrochemical characterization, and integration into soft robotic systems demonstrate the potential of these stretchable batteries in practical applications. The sliding‐electrodes battery can stably power multiple servo motors and sensing circuits under stretching, twisting, bending, and after impact. [ABSTRACT FROM AUTHOR]

High energy density, long cyclability, and enhanced stability in a small footprint achieved through microfabrication are crucial for micro lithium‐ion batteries. Herein, a 3D Si‐clad NiSn anode characterized by a dendritic NiSn network and silicon nanoparticles is proposed. The dendritic network facilitates fast ion/electron transfer and provides expansion space for the silicon, while the uniformly distributed silicon enhances capacity and stability. The anode, scalable to the hundred‐micron scale, is fabricated via one‐step electrodeposition incorporating the dynamic template technique. This technique generates interconnected pores extending from the inner to the outer surface of the anode, facilitating electrolyte penetration and ion transport. As a result, the anodes in the Swagelok cells exhibit an ultrahigh areal capacity of up to 28.2 mAh cm−2 and an enhanced stability of 91% capacity retention after 300 cycles. The dendritic Si‐clad NiSn anode, based on microfabrication, presents an excellent opportunity to advance micro energy systems. [ABSTRACT FROM AUTHOR]

Portable and autonomous microdevices often require on-board power sources such as thin film microbatteries. Air microbatteries are an attractive power source for such devices due to their high specific energy density. One particularly appropriate air chemistry is based on Zn, due to the multiple microfabrication approaches compatible with Zn anode formation. We demonstrate fabrication approaches to realize Zn film anodes in different thickness regimes using microelectromechanical systems based fabrication techniques—evaporation, electrodeposition, and laser micromachining; and evaluate their relative performance as power sources in a primary battery configuration. These fabrication techniques enable films in thickness regimes ranging from the micron scale to hundreds of microns. The fabricated films have been characterized using scanning electron microscopy and energy dispersive x-ray spectroscopy, and were found to be dense and reasonably free from impurities. The electrochemical and discharge properties of the fabricated films were studied in an air battery configuration comprising a Zn anode-alkaline hydrogel electrolyte-metal catalyst stack, in which the anode had a surface area of 0.78 cm2. Evaporated Zn anodes (1–10 µ ms) yielded Zn utilizations of 96.5% and 82% at 10 and 1 mA discharge rates, respectively. The specific capacity of the evaporated Zn anodes was 791 mAh g−1 when discharged at 10 mA, close to the Zn theoretical specific capacity of 820 mAh g−1. Electrodeposited Zn anodes (10–100 µ ms) yielded utilizations of 90.2% and 75.6% at 10 and 1 mA discharge rates, respectively. Laser micromachined Zn anodes (250 µ ms) yielded Zn utilization of 90% when discharged at 10 mA. These fabrication techniques offer the potential to realize high energy density Zn anodes of different thickness ranges for thin film microbatteries, which can be tailored to microdevice-based applications of interest. [ABSTRACT FROM AUTHOR]

We investigate the ac magnetic behavior of solution processable, non-stoichiometric zinc ferrite nanocrystals with a series of sizes and zinc concentrations. Nearly monodisperse ZnxFe3-xO4 nanocrystals (x = 0-0.25) with an average size ranging from 7.4 nm to 13.8 nm are synthesized by using a solvothermal method. All the nanocrystals are in a superparamagnetic state at 300 K, which is confirmed by Superconductive Quantum Interference Device magnetometry. Due to the doping of non-magnetic Zn2+ into A site of ferrite, the saturation magnetization of nanocrystals increases as the size and Zn concentration increases. The ac magnetic permeability measurements at radio frequencies reveal that the real part of the magnetic permeability of similarly sized ferrite nanocrystals can be enhanced by almost twofold as the Zn2+ doping level increases from 0 to 0.25. The integration of 12.3 nm Zn0.25Fe2.75O4 nanocrystals into a toroidal inductor and a solenoid inductor prepared via a simple solution cast process yields a higher quality factors than air core inductors with the same geometries up to 5MHz and 9MHz, respectively, which is in the regime of the switching frequencies for the advanced integrated power converters. [ABSTRACT FROM AUTHOR]

Gambusia holbrooki is arguably the most widely introduced and ecologically damaging freshwater fish in the world. Although aspects of its aggressive behaviour have been studied in lentic environments and ex situ experiments, the physical damage to native freshwater fishes in riverine systems caused by this behaviour remains relatively unknown.This study quantified the spatial and temporal patterns of abundance of G. holbrooki and the prevalence of fin‐nipping damage on freshwater fishes in river systems of south‐western Australia, a globally endemic hotspot with a high proportion of threatened species. It then determined the environmental factors influencing the abundance of G. holbrooki and the prevalence of fin‐nipping damage on native fishes.Caudal fin damage differed significantly among four endemic native fishes, with damage being most prevalent in the percichthyid Nannoperca vittata, which has a similar size and ecological niche to G. holbrooki. Fin‐nipping damage of native species also showed significant seasonal variation; occurring most commonly during summer and autumn when many rivers in this region cease to flow and contract to refuge pools, probably increasing interactions between G. holbrooki and the native fishes. Moreover, the environmental variables that best explained both the density of G. holbrooki and the prevalence of fin‐nipping were broadly similar and were characteristic of more degraded habitats.We anticipate that habitat degradation, river regulation and severe declines in surface flows resulting from climate change will benefit G. holbrooki to the detriment of native fishes. Restoration of riverine environments along with public education campaigns to prevent the further spread of G. holbrooki or the introduction of additional species is crucial to mitigate their effects on aquatic ecosystems. [ABSTRACT FROM AUTHOR]

The brain's small-world network utilizes its short-range and long-range synaptic connections to process information in a complex and energy-efficient manner. To emulate the former, neuromorphic hardware typically leverages the conductance switching properties of thin-film dielectrics and semiconductors. Because these materials offer low ion mobilities, long-range connections built from thicker dielectrics require impractically-large forming voltages. To overcome this intrinsic shortcoming of solid-state active media, we present in this paper a simple Ag–H2O–Au cell that takes advantage of the relatively high ion mobility offered by deionized water to enable programmable connectivity switches between neurons separated by large gaps (∼40 µm). We introduce dual voltage programming schemes that allow the switch conductance to be modulated in analog and digital steps. When operating in the analog mode, the switch conductance could be potentiated and depressed over a relatively large (3.5×) range. In the digital mode, the Ag–H2O–Au switch delivered a high ON/OFF current ratio of ∼600 and sustained this margin over 200 switching cycles. Additionally, both switch states could be maintained for at least 3 h without external power. We show that unlike their solid-state counterparts, the water-gap in the Ag–H2O–Au cell can be easily refreshed without compromising the switching functionality. These attributes of Ag–H2O–Au switches in addition to their biocompatibility and simple design make them attractive for neuromorphic wetware implementations. [ABSTRACT FROM AUTHOR]

Composite materials comprising multilayers of metal and conductive polymer can have applications in sensing, biomedical, and energy storage/conversion scenarios. One attribute of such metal/polymer composites is that they typically display highly anisotropic electrical properties, which makes them useful as materials for microelectronic or magnetic devices. However, incorporating the deposition of conductive polymers into scalable and manufacturable fabrication processes can be challenging, as the mechanisms for electropolymerization are complex. We previously demonstrated an additive approach to fabricate metal/polymer multilayer structures, using soft magnetic alloys as the metal component and polypyrrole (PPy) as the polymer component. To extend the utility of these composites, the deposition of many multiples of alternating metal/polymer pairs within specifically defined lithographic molds is highly desirable. However, since the lateral growth of electrodeposited PPy is typically faster than vertical growth, non-uniform layer geometry and growth of the polymer on and above the patterned molds are often observed. In this work, we achieve suppression of lateral PPy growth by control of electropolymerization bath counter-anions and passivation of underlying metal layers during deposition. The lateral-to-vertical growth rate uniformity ratio is reduced by a factor of six (to approximately unity) through polymerization parameter optimization and exploiting a continuous five-bath electrodeposition approach. The reduction in lateral growth rate enhances the scalability of multilayer structures that are fabricated using this additive electrodeposition-based approach and provides a manufacturable route to additive, lithographically patterned metal/polymer composites with tunable volume and geometry, without sacrificing the microstructure and properties of the composite. [ABSTRACT FROM AUTHOR]

MEMS-enabled multilayer composites, in which microfabrication is used to create micron-scale thickness layers within the volume of meso-scale thickness structures, can be exploited to create materials with highly anisotropic electromagnetic properties. Such materials have utility in both sensing and energy applications, including electrostatic and magnetic energy storage and conversion. A fabrication challenge in realizing these classes of materials lies in the size-scale disparity between the thickness of an individual layer and the desired thickness of the final anisotropic material. We demonstrate a fully additive sequential electrochemical deposition approach for such structures, which enables scalable composite volume while maintaining micron-scale individual layer thicknesses. Alternating metal and polymer layers, which exhibit very different electrical conductivities, are continuously electrodeposited in batch-scale. Individual layer thicknesses are controlled by deposition currents and times, while lateral extents are defined by lithographically defined molds. The fabrication process is illustrated using electrodeposited NiFe alloys and polypyrrole, and the anisotropy of electrical conductivity is assessed for potential use of these structures as magnetic cores for high frequency switching converters. Due to the relatively resistive polypyrrole layers, electrical anisotropy of lateral to vertical conductivity exceeding 106 was achieved. This approach offers a solution-based, microfabrication compatible, and manufacturable route to functional composite materials that exhibit high electrical anisotropies. [2020-0256] [ABSTRACT FROM AUTHOR]

We report a biodegradable, self-powered sensor for measurement of dissolved oxygen in the body. The principle of operation is the competition of an oxygen reduction reaction against the ordinarily dominant hydrogen reduction reaction at the cathode of a corroding electrochemical couple. Because the relative contribution of the oxygen reduction reaction to the overall electrochemical reaction depends on the local oxygen concentration, the output voltage of the couple is also dependent on local oxygen concentration. The sensor is formed by embedding the biodegradable metals magnesium and molybdenum within a biodegradable poly(lactic acid) substrate using lamination; external physiological solution is utilized as the electrolyte. The output voltage of the sensor (i.e., the voltage generated across the corroding couple) was measured as a function of oxygen concentration over typical physiological oxygen concentration ranges of 0–60% that of atmospheric oxygen. A linear output voltage response of approximately 6 mV per percentage point oxygen concentration was observed; oxygen concentrations above this range resulted in sensor saturation. [2020-0192] [ABSTRACT FROM AUTHOR]