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The teaching of medical pathology has undergone significant change in the last 30-40 years, especially in the context of employing bottled specimens or 'pots' in classroom settings. The reduction in post-mortem based teaching in medical training programs has resulted in less focus being placed on the ability of students to describe the gross anatomical pathology of specimens. Financial considerations involved in employing staff to maintain bottled specimens, space constraints and concerns with health and safety of staff and student laboratories have meant that many institutions have decommissioned their pathology collections. This report details how full-colour surface scanning coupled with CT scanning and 3 D printing allows the digital archiving of gross pathological specimens and the production of reproductions or replicas of preserved human anatomical pathology specimens that obviates many of the above issues. With modern UV curable resin printing technology, it is possible to achieve photographic quality accurate replicas comparable to the original specimens in many aspects except haptic quality. Accurate 3 D reproductions of human pathology specimens offer many advantages over traditional bottled specimens including the capacity to generate multiple copies and their use in any educational setting giving access to a broader range of potential learners and users.

Neutron imaging provides high sensitivity to liquid water while being able to penetrate materials typically used to construct fuel cells. Water distribution measurements in operating fuel cells are typically performed using neutron radiography as the neutron fluence rate of the beam requires long acquisition times for high resolution making tomography difficult. Radiography only provides a two-dimensional look at the water distribution with an operating fuel cell making tomography preferable to understand three-dimensional distribution of water. NIST developed a fuel cell hardware design to allow for simultaneous neutron and X-ray tomography and as first reported in 2017 [1], initial efforts for tomography required acquisition times of 18 hours while the cell continuously operated at steady state conditions. Progress was made to improve acquisition settings and reconstruction methods to reduce the time required. These improvements were presented in 2019 [2] and demonstrated that scan times could be reduced to 8 hours and provided ground work for reducing acquisition times down to 1 hour to 2 hours. Since 2019, further progress has been made in applying dose reduction iterative reconstruction algorithms to the fuel cell datasets to allow faster acquisition times. Faster acquisition scans were simulated by reducing the number of projection angles from the high-resolution datasets from the 2019 work. The high-resolution scan was acquired with 851 projections from 0° to 360° and the fast scan consisted of only 51 projections. Reducing the number of projections from 851 to 51 simulates a scan that requires only 29 minutes to acquire, which is close to the typical length of time for acquiring high resolution radiography images. Figure 1 shows the comparison of a single slice from the 3D volumes with (A) representing the 8 hour, 851 projection scan, (C) the iteratively reconstructed 51 projection scan, and (E) the 51 projection scan reconstructed with filtered back projection algorithm used for the 851 projection scan. The iterative reconstruction gives favorable results when compared to the 851 projection reconstruction and shows that flux limitations on speed can be overcome to achieve high-speed tomography at high resolution on a neutron beam. This talk will describe the methodology for acquiring neutron tomography scans of operating fuel cells in under 30 minutes and give insights into how this can be used towards solving water management issues. It will be possible to combine radiography and tomography into a hybrid scan at each operating condition that can be acquired in 1 hour that will provide highly quantifiable water content measurements with 3-dimensional distribution information. The short scan times are beneficial for materials sets that are sensitive to long constant current hold durations such as new non-platinum catalysts. Additionally, new cameras are being commissioned that will improve resolution and push X-ray resolution to the point of resolving the fiber and macropore distribution of the gas diffusion layer (GDL) that can be coupled with the water content information. Figure 1

Wolter optics promise to radically transform neutron imaging by improving the time resolution of the method by at least a factor 1,000 while providing spatial resolution of order a few micrometers [1]. These optics will enable neutron tomography of operating fuel cells with a time resolution of about a few minutes, which will provide unique insight into the water transport phenomena in membrane electrode assemblies of fuel cells and electrolyzers. Neutron imaging has played a critical role in understanding water transport in proton exchange membrane fuel cells and electrolyzers [2]. The primary limitation of the method is the inherent neutron source strength, which is about a billion times weaker than X-ray synchrotron sources. Additionally, neutrons are difficult to focus using refractive lenses so that neutron imaging beamlines heretofore can be described as pinhole cameras. In a pinhole camera, the best achievable spatial resolution (λg) is determined by the diameter of the pinhole (D ~1 cm), the pinhole-to-detector distance (L ~10 m), and the sample-to-detector distance (Z ~1 cm): λg = Z D / (L – Z) ~ Z D / L Returning to the source strength, the neutron fluence rate at the sample position scales as (D / L)2. This means that higher spatial resolution for finite sized objects requires sacrificing neutron intensity and incurring long exposure times. Typical measurements require about 20 minutes for a single two-dimension image of the water content in fuel cell for a spatial resolution of about 10 µm. Such time requirements preclude the use of tomography, which is required to understand the water content in real fuel cell components since the MEA cannot be considered to be planar at the few micrometer level. We will describe Wolter optics, and the optical system that will be first available in 2022. After the NCNR cold source upgrade is anticipated to yield a time resolution gain of about 10,000 compared to a pinhole camera. We will discuss our expected image acquisition and analysis procedures guided by ray tracing simulations. Figure 1. Proof of concept Wolter optics image of a fuel cell test section. [1] D. S. Hussey et al., “Design of a neutron microscope based on Wolter mirrors,” Nucl. Instruments Methods Phys. Res. Sect. A Accel. Spectrometers, Detect. Assoc. Equip., vol. 987, no. October 2020, p. 164813, 2021. [2] T. A. Trabold, J. P. Owejan, J. J. Gagliardo, D. L. Jacobson, D. S. Hussey, and M. Arif, “Use of neutron imaging for proton exchange membrane fuel cell (PEMFC) performance analysis and design,” Handb. fuel cells, vol. 6, no. Table 1, 2010. Figure 1

Demand for high purity hydrogen production using renewable energy sources is growing to meet the clean energy demands. Polymer electrolyte membrane water electrolyzer (PEMWE) is one of the viable options for H2 production, but its high capital cost and operational expenditures increase the cost of H2. Improving the interface between the catalyst layer (CL) and the porous transport layer (PTL) is critical to increasing the efficiency of PEMWEs and thereby lowering the cost of H2. Increased contact between the CL and PTL improves catalyst utilization, and the optimal structure of the PTL reduces the mass transport issues related to O2 bubble removal.(1-3) Improved understanding of the PTL microstructure is necessary to improve the performance and efficiency of the PEMWE. This work presents a systematic study to elucidate the effect of PTL properties (morphology, thickness, and porosity) and their impact on PEMWE performance under different operating conditions. Polarization curves with different anode PTL (felt, sinter and pore graded hierarchical PTL) are presented in Figure 1a. The separation of mass transport resistance and the contract resistance for the different PTLs will be elucidated to show the impact of water management and interfacial contact. Mass transport in an operating electrolyzer is also studied by estimating the water content using neutron imaging. Figure 1b shows water thickness across a membrane electrode assembly (MEA) with a pore graded hierarchical PTL in anode at different current densities. Water content across the MEA with different PTL is also studied. The cells with these PTLs were evaluated in operando using micro x-ray computed tomography (CT) and x-ray radiography. The x-ray techniques revealed oxygen distribution within the PTLs on the pore-scale at varied current densities, complementing neutron imaging water thickness studies and providing micro-scale insight into transport. Acknowledgment This research is supported by the U.S. Department of Energy (DOE) Hydrogen and Fuel Cell Technologies Office, through the H2NEW consortium. References J. K. Lee, C. Lee, K. F. Fahy, B. Zhao, J. M. LaManna, E. Baltic, D. L. Jacobson, D. S. Hussey and A. Bazylak, Cell Reports Physical Science, 1, 100147 (2020). T. Schuler, J. M. Ciccone, B. Krentscher, F. Marone, C. Peter, T. J. Schmidt and F. N. Büchi, Advanced Energy Materials, 10, 1903216 (2020). P. Lettenmeier, S. Kolb, F. Burggraf, A. S. Gago and K. A. Friedrich, Journal of Power Sources, 311, 153 (2016). Figure 1

Water management in a fuel cell is an essential prerequisite for achieving high cell performance, where sufficient water is required for membrane hydration while excess liquid water leads to undesired mass transport losses. Existing heterogeneity within the fuel cell, such as those created by flow-field lands and channels create three-dimensional (3-D) heterogeneity in water distribution within the fuel cell components, which may have long term effect on the durability of fuel cell components, such as the membrane (1). 3-D visualization techniques such as X-ray (1-4) and neutron (5) tomography are powerful in revealing the effect of the existing heterogeneity on water distributions in 3-D. However, there is an opportunity to combine neutron and X-ray tomography (6) to probe into the details of these heterogenous water distributions even further and clarify their impacts on 3-D membrane hydration. In this study, we investigate the effect of heterogeneity in fuel cells (primarily land-channel heterogeneity) on 3-D membrane hydration and membrane morphology changes during fuel cell operation using simultaneous neutron and X-ray tomography (NeXT). The fuel cell is tested at varying gas humidity conditions in a serpentine flow-field configuration. A simultaneous coupling of neutron and X-ray imaging provides high contrast across various components of the fuel cell. Specifically, neutrons are highly attenuated by hydrogen atoms; hence neutron imaging is used to accurately locate and quantify operando water distribution. X-rays are sensitive to metals; hence simultaneous X-rays imaging is used to track metal-containing components (metal flow-field) and interfaces (such as interface between Pt-containing catalyst layer and membrane). This study demonstrates how heterogeneity in fuel cells plays a role in 3-D membrane hydration and needs to be tailored to enhance cell performance. References Y. Singh, R. T. White, M. Najm, T. Haddow, V. Pan, F. P. Orfino, M. Dutta, and E. Kjeang, J. Power Sources., 412 (2019): 224-237. Y. Nagai, J. Eller, T. Hatanaka, S. Yamaguchi, S. Kato, A. Kato, F. Marone, H. Xu and F. N. Büchi, J. Power Sources., 435 (2019). S. J. Normile, D. C. Sabarirajan, O. Calzada, V. De Andrade, X. Xiao, P. Mandal, D. Y. Parkinson, A. Serov, P. Atanassov and I. V. Zenyuk, Meter. Today Energy., 9 (2018). S. S. Alrwashdeh, I. Manke, H. Markötter, M. Klages, M. Göbel, J. Haußmann, J. Scholta and J. Banhart, ACS Nano., 11, 6 (2017). J. M. LaManna, Y. Yue, T. A. Trabold, J. D. Fairweather, D. S. Hussey, E. Baltic and D. L. Jacobson, Meet. Abstr. - Electrochem. Soc., 32 (2017). J. M. LaManna, D. S. Hussey, E. Baltic and D. L. Jacobson, Rev. Sci. Instrum., 88, 11 (2017).

Head and neck anatomy is complex for students to learn and educators to teach. Instructing students on anatomy using radiological imaging can aid comprehension and prepare them for future clinical practice. Computer-aided anatomy instruction is accessible to diverse learners and avoids barriers identified with face-to-face teaching.We designed a self-guided PowerPoint tutorial with multiple medical imaging modalities, clinical correlations, and self-review questions incorporated throughout. The tutorial was evaluated with a group of 178 Australian preclinical medical students who had prior teaching related to head and neck anatomy. Student participants were divided into experimental and control groups. Participants completed two knowledge assessments: experimental group before and after tutorial engagement and control group before tutorial engagement. All participants were invited to provide feedback on their experiences with the tutorial via questionnaires.Engagement with the tutorial improved overall head and neck anatomy knowledge (Given the improved outcomes following tutorial exposure, our results suggest that this tutorial is efficacious when used in concert with existing anatomy curricula. Participants' perceived value of the tutorial additionally suggests that it would be taken up well by medical students and is an effective addition to the existing tutorial series. Further research is needed to assess the tutorial's use as a stand-alone addition to the anatomy curriculum.

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