A combined imaging, deformation and registration methodology for predicting respirator fitting.

N95/FFP3 respirators have been critical to protect healthcare workers and their patients from the transmission of COVID-19. However, these respirators are characterised by a limited range of size and geometry, which are often associated with fitting issues in particular sub-groups of gender and ethnicities. This study describes a novel methodology which combines magnetic resonance imaging (MRI) of a cohort of individuals (n = 8), with and without a respirator in-situ, and 3D registration algorithm which predicted the goodness of fit of the respirator. Sensitivity analysis was used to optimise a deformation value for the respirator-face interactions and corroborate with the soft tissue displacements estimated from the MRI images. An association between predicted respirator fitting and facial anthropometrics was then assessed for the cohort.

Review of high energy x-ray computed tomography for non-destructive dimensional metrology of large metallic advanced manufactured components.

Advanced manufacturing technologies, led by additive manufacturing, have undergone significant growth in recent years. These technologies enable engineers to design parts with reduced weight while maintaining structural and functional integrity. In particular, metal additive manufacturing parts are increasingly used in application areas such as aerospace, where a failure of a mission-critical part can have dire safety consequences. Therefore, the quality of these components is extremely important. A critical aspect of quality control is dimensional evaluation, where measurements provide quantitative results that are traceable to the standard unit of length, the metre. Dimensional measurements allow designers, manufacturers and users to check product conformity against engineering drawings and enable the same quality standard to be used across the supply chain nationally and internationally. However, there is a lack of development of measurement techniques that provide non-destructive dimensional measurements beyond common non-destructive evaluation focused on defect detection. X-ray computed tomography (XCT) technology has great potential to be used as a non-destructive dimensional evaluation technology. However, technology development is behind the demand and growth for advanced manufactured parts. Both the size and the value of advanced manufactured parts have grown significantly in recent years, leading to new requirements of dimensional measurement technologies. This paper is a cross-disciplinary review of state-of-the-art non-destructive dimensional measuring techniques relevant to advanced manufacturing of metallic parts at larger length scales, especially the use of high energy XCT with source energy of greater than 400 kV to address the need in measuring large advanced manufactured parts. Technologies considered as potential high energy x-ray generators include both conventional x-ray tubes, linear accelerators, and alternative technologies such as inverse Compton scattering sources, synchrotron sources and laser-driven plasma sources. Their technology advances and challenges are elaborated on. The paper also outlines the development of XCT for dimensional metrology and future needs.

A Personal Respirator to Improve Protection for Healthcare Workers Treating COVID-19 (PeRSo).

Introduction: SARS-CoV-2 infection is a global pandemic. Personal Protective Equipment (PPE) to protect healthcare workers has been a recurrent challenge in terms of global stocks, supply logistics and suitability. In some settings, around 20% of healthcare workers treating COVID-19 cases have become infected, which leads to staff absence at peaks of the pandemic, and in some cases mortality. Methods: To address shortcomings in PPE, we developed a simple powered air purifying respirator, made from inexpensive and widely available components. The prototype was designed to minimize manufacturing complexity so that derivative versions could be developed in low resource settings with minor modification. Results: The "Personal Respirator - Southampton" (PeRSo) delivers High-Efficiency Particulate Air (HEPA) filtered air from a battery powered fan-filter assembly into a lightweight hood with a clear visor that can be comfortably worn for several hours. Validation testing demonstrates that the prototype removes microbes, avoids excessive CO2 build-up in normal use, and passes fit test protocols widely used to evaluate standard N95/FFP2 and N99/FFP3 face masks. Feedback from doctors and nurses indicate the PeRSo prototype was preferred to standard FFP2 and FFP3 masks, being more comfortable and reducing the time and risk of recurrently changing PPE. Patients report better communication and reassurance as the entire face is visible. Conclusion: Rapid upscale of production of cheaply produced powered air purifying respirators, designed to achieve regulatory approval in the country of production, could protect healthcare workers from infection and improve healthcare delivery during the COVID-19 pandemic.

Development of X-ray micro-focus computed tomography to image and quantify biofilms in central venous catheter models in vitro.

Bacterial infections of central venous catheters (CVCs) cause much morbidity and mortality, and are usually diagnosed by concordant culture of blood and catheter tip. However, studies suggest that culture often fails to detect biofilm bacteria. This study optimizes X-ray micro-focus computed tomography (X-ray µCT) for the quantification and determination of distribution and heterogeneity of biofilms in in vitro CVC model systems.Bacterial culture and scanning electron microscopy (SEM) were used to detect Staphylococcus epidermidis ATCC 35984 biofilms grown on catheters in vitro in both flow and static biofilm models. Alongside this, X-ray µCT techniques were developed in order to detect biofilms inside CVCs. Various contrast agent stains were evaluated using energy-dispersive X-ray spectroscopy (EDS) to further optimize these methods. Catheter material and biofilm were segmented using a semi-automated matlab script and quantified using the Avizo Fire software package. X-ray µCT was capable of distinguishing between the degree of biofilm formation across different segments of a CVC flow model. EDS screening of single- and dual-compound contrast stains identified 10 nm gold and silver nitrate as the optimum contrast agent for X-ray µCT. This optimized method was then demonstrated to be capable of quantifying biofilms in an in vitro static biofilm formation model, with a strong correlation between biofilm detection via SEM and culture. X-ray µCT has good potential as a direct, non-invasive, non-destructive technology to image biofilms in CVCs, as well as other in vivo medical components in which biofilms accumulate in concealed areas.

High-resolution computed tomography reconstructions of invertebrate burrow systems.

The architecture of biogenic structures can be highly influential in determining species contributions to major soil and sediment processes, but detailed 3-D characterisations are rare and descriptors of form and complexity are lacking. Here we provide replicate high-resolution micro-focus computed tomography (µ-CT) data for the complete burrow systems of three co-occurring, but functionally contrasting, sediment-dwelling inter-tidal invertebrates assembled alone, and in combination, in representative model aquaria. These data (≤ 2,000 raw image slices aquarium(-1), isotropic voxel resolution, 81 µm) provide reference models that can be used for the development of novel structural analysis routines that will be of value within the fields of ecology, pedology, geomorphology, palaeobiology, ichnology and mechanical engineering. We also envisage opportunity for those investigating transport networks, vascular systems, plant rooting systems, neuron connectivity patterns, or those developing image analysis or statistics related to pattern or shape recognition. The dataset will allow investigators to develop or test novel methodology and ideas without the need to generate a complete three-dimensional computation of exemplar architecture.

Adaptations to Hydrothermal Vent Life in Kiwa tyleri, a New Species of Yeti Crab from the East Scotia Ridge, Antarctica.

Hydrothermal vents in the Southern Ocean are the physiologically most isolated chemosynthetic environments known. Here, we describe Kiwa tyleri sp. nov., the first species of yeti crab known from the Southern Ocean. Kiwa tyleri belongs to the family Kiwaidae and is the visually dominant macrofauna of two known vent sites situated on the northern and southern segments of the East Scotia Ridge (ESR). The species is known to depend on primary productivity by chemosynthetic bacteria and resides at the warm-eurythermal vent environment for most of its life; its short-range distribution away from vents (few metres) is physiologically constrained by the stable, cold waters of the surrounding Southern Ocean. Kiwa tylerihas been shown to present differential life history adaptations in response to this contrasting thermal environment. Morphological adaptations specific to life in warm-eurythermal waters, as found on - or in close proximity of - vent chimneys, are discussed in comparison with adaptations seen in the other two known members of the family (K. hirsuta, K. puravida), which show a preference for low temperature chemosynthetic environments.

Three dimensional imaging of paraffin embedded human lung tissue samples by micro-computed tomography.

BACKGROUND: Understanding the three-dimensional (3-D) micro-architecture of lung tissue can provide insights into the pathology of lung disease. Micro computed tomography (µCT) has previously been used to elucidate lung 3D histology and morphometry in fixed samples that have been stained with contrast agents or air inflated and dried. However, non-destructive microstructural 3D imaging of formalin-fixed paraffin embedded (FFPE) tissues would facilitate retrospective analysis of extensive tissue archives of lung FFPE lung samples with linked clinical data. METHODS: FFPE human lung tissue samples (n = 4) were scanned using a Nikon metrology µCT scanner. Semi-automatic techniques were used to segment the 3D structure of airways and blood vessels. Airspace size (mean linear intercept, Lm) was measured on µCT images and on matched histological sections from the same FFPE samples imaged by light microscopy to validate µCT imaging. RESULTS: The µCT imaging protocol provided contrast between tissue and paraffin in FFPE samples (15 mm x 7 mm). Resolution (voxel size 6.7 µm) in the reconstructed images was sufficient for semi-automatic image segmentation of airways and blood vessels as well as quantitative airspace analysis. The scans were also used to scout for regions of interest, enabling time-efficient preparation of conventional histological sections. The Lm measurements from µCT images were not significantly different to those from matched histological sections. CONCLUSION: We demonstrated how non-destructive imaging of routinely prepared FFPE samples by laboratory µCT can be used to visualize and assess the 3D morphology of the lung including by morphometric analysis.

Functional anatomy and feeding biomechanics of a giant Upper Jurassic pliosaur (Reptilia: Sauropterygia) from Weymouth Bay, Dorset, UK.

Pliosaurs were among the largest predators in Mesozoic seas, and yet their functional anatomy and feeding biomechanics are poorly understood. A new, well-preserved pliosaur from the Kimmeridgian of Weymouth Bay (UK) revealed cranial adaptations related to feeding. Digital modelling of computed tomography scans allowed reconstruction of missing, distorted regions of the skull and of the adductor musculature, which indicated high bite forces. Size-corrected beam theory modelling showed that the snout was poorly optimised against bending and torsional stresses compared with other aquatic and terrestrial predators, suggesting that pliosaurs did not twist or shake their prey during feeding and that seizing was better performed with post-symphyseal bites. Finite element analysis identified biting-induced stress patterns in both the rostrum and lower jaws, highlighting weak areas in the rostral maxillary-premaxillary contact and the caudal mandibular symphysis. A comparatively weak skull coupled with musculature that was able to produce high forces, is explained as a trade-off between agility, hydrodynamics and strength. In the Kimmeridgian ecosystem, we conclude that Late Jurassic pliosaurs were generalist predators at the top of the food chain, able to prey on reptiles and fishes up to half their own length.

Complex rostral neurovascular system in a giant pliosaur.

Pliosaurs were a long-lived, ubiquitous group of Mesozoic marine predators attaining large body sizes (up to 12 m). Despite much being known about their ecology and behaviour, the mechanisms they adopted for prey detection have been poorly investigated and represent a mystery to date. Complex neurovascular systems in many vertebrate rostra have evolved for prey detection. However, information on the occurrence of such systems in fossil taxa is extremely limited because of poor preservation potential. The neurovascular complex from the snout of an exceptionally well-preserved pliosaur from the Kimmeridgian (Late Jurassic, c. 170 Myr ago) of Weymouth Bay (Dorset, UK) is described here for the first time. Using computed tomography (CT) scans, the extensive bifurcating neurovascular channels could be traced through the rostrum to both the teeth and the foramina on the dorsal and lateral surface of the snout. The structures on the surface of the skull and the high concentrations of peripheral rami suggest that this could be a sensory system, perhaps similar to crocodile pressure receptors or shark electroreceptors.