Metabolic Physiology of Euthermic and Torpid Lesser Long-Eared Bats, Nyctophilus geoffroyi (Chiroptera: Vespertilionidae)

Thermal and metabolic physiology of the Australian lesser long-eared bat, Nyctophilias geojfroyi, a small (ca. 8 g) gleaning insectivore, was studied using flow-through respirometry. Basal metabolic rate of N. geojfroyi (1.42 ml O2 g−1 h−1) was 70% of that predicted for an 8-g mammal but fell within the range for vespertilionid bats. N. geoffroyi was thermally labile, like other vespertilionid bats from the temperate zone, with clear patterns of euthermy (body temperature >32°C) and torpor. It was torpid at temperatures ≤25°C, and spontaneously aroused from torpor at ambient temperatures ≥5°C. Torpor provided significant savings of energy and water, with substantially reduced rates of oxygen consumption and evaporative water loss. Minimum wet conductance (0.39 ml O2 g−1 h−1 °C−1) of euthermic bats was 108% of predicted, and euthermic dry conductance was 7.2 J g−1 h−1 °C−1 from 5-25°C. Minimum wet and dry conductances of bats that were torpid at an ambient temperature of 15-20°C (0.06 ml O2 g−1 h−1 °C−1 and 0.60 J g−1 h−1 °C−1) were substantially less than euthermic values, but conductance of some torpid bats increased at lower ambient temperatures and approached values for euthermic bats. Metabolic rates of bats torpid at ambient temperatures >10°C and bats euthermic in the thermoneutral zone indicated a metabolic Q10 of 3.9. That high Q10 suggested that there may have been an intrinsic reduction in metabolic rate during torpor, in addition to down-regulation of thermoregulation (which accounted for most of the reduction in metabolic rate) and the normal Q10 effec

A study of the of ytterbium disilicates undergoing water vapour corrosion for environmental barrier coating applications

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Piezomorphic materials

The development of stress-induced morphing materials which are described as piezomorphic materials is reported. The development of a piezomorphic material is achieved by introducing spatial dependency into the compliance matrix describing the elastic response of a material capable of undergoing large strain deformation. In other words, it is necessary to produce an elastically gradient material. This is achieved through modification of the microstructure of the compliant material to display gradient topology. Examples of polymeric (polyurethane) foam and microporous polymer (expanded polytetrafluoroethylene) piezomorphic materials are presented here. These materials open up new morphing applications where dramatic shape changes can be triggered by mechanical stress

3D imaging by serial block face scanning electron microscopy for materials science using ultramicrotomy

AbstractMechanical serial block face scanning electron microscopy (SBFSEM) has emerged as a means of obtaining three dimensional (3D) electron images over volumes much larger than possible by focused ion beam (FIB) serial sectioning and at higher spatial resolution than achievable with conventional X-ray computed tomography (CT). Such high resolution 3D electron images can be employed for precisely determining the shape, volume fraction, distribution and connectivity of important microstructural features. While soft (fixed or frozen) biological samples are particularly well suited for nanoscale sectioning using an ultramicrotome, the technique can also produce excellent 3D images at electron microscope resolution in a time and resource-efficient manner for engineering materials. Currently, a lack of appreciation of the capabilities of ultramicrotomy and the operational challenges associated with minimising artefacts for different materials is limiting its wider application to engineering materials. Consequently, this paper outlines the current state of the art for SBFSEM examining in detail how damage is introduced during slicing and highlighting strategies for minimising such damage. A particular focus of the study is the acquisition of 3D images for a variety of metallic and coated systems

Effect of sparsity and exposure on total variation regularized X-ray tomography from few projections

We address effects of exposure and image gradient sparsity for total variation-regularized reconstruction: is it better to collect many low-quality or few high-quality projections, and can gradient sparsity predict how many projections are necessary? Preliminary results suggest collecting many low-quality projections is favorable, and that a link may exist between gradient sparsity level and successful reconstruction

Characterisation of an Advanced Nickel Based Superalloy Post Cold Work by Swaging

Cylindrical bars of the advanced nickel based superalloy RR1000 were subjected to swaging to induce approximately 30% cold work. Grain size analysis demonstrated a distinct modification to the microstructure whilst electron back scattered diffraction (EBSD) measurements confirmed the evolution of a relatively strong texture parallel with the longitudinal bar axis. Intragranular strain damage was identified. The effects of the swaging on bulk mechanical properties are illustrated across a range of test temperatures