Highlights from
Techniques and Biological Applications Assessing Soſt -Tissue Shrinkage Estimates in Museum Specimens Imaged with Diff usible Iodine-Based Contrast-Enhanced Computed Tomography (diceCT) by BP Hedrick, L Yohe, AV Linden, LM Dávalos, K Sears, A Sadier, SJ Rossiter, KTJ Davies, and E Dumont, Microsc Microanl | doi:10.1017/S1431927618000399
Diff usible iodine-based contrast-enhanced micro-computed tomography (diceCT) allows visualization of organismal soſt -tissue cheaply and non-destructively, thus giving compar- ative biologists a new toolkit for assessing morphological variation. As it is impractical to collect fresh specimens, comparative morphologists primarily use museum collec- tions to visualize features across a wide range of species, but the consequences of preparation and storage are not well understood. We report soſt -tissue shrinkage in the brains and eyes of fi ve bat species from museum collections and compare this to shrinkage found in specimens of six freshly-collected species. Although the magnitude of shrinkage in the museum specimens did not increase over four weeks of stain time in iodine, the brains and eyes of museum specimens shrank considerably prior to placement in iodine in comparison with fi eld-collected specimens. While the cause of shrinkage in these specimens remains unknown, we caution against study designs that combine fresh and museum specimens. Future work is needed to generate a correction factor that will enable incorpo- ration of museum collections in these studies.
Mid-sagittal section of museum specimen of Glossophaga soricina (Pallas’s long-tongued bat) head after three weeks in I 2 KI stain, demonstrating complete penetration after only several weeks in stain. The black space surrounding the brain shows the degree of shrinkage present in the specimen. Anatomical structures are outlined to orient the specimen. Scale bar = 4 mm.
Techniques and Material Applications
Characterization of Lithium Ion Battery Materials with Valence Electron Energy Loss Spectroscopy by FC Castro and VP Dravid, Microsc Microanal | doi:10.1017/S1431927618000302
Electron Energy Loss Spectroscopy (EELS) is an excellent tool for studying lithium ion battery materials (LIB), providing direct information on lithium content, transition metal oxidation state, and oxygen bonding. However, practical EELS analysis can be challenging because of stringent constraints on sample thickness, carbon contamination, and sensitivity to the electron beam. T e valence EELS region (<15 eV) encompasses supplementary features
useful for ‘fi ngerprint’ analysis and spectrum imaging when facing such challenges. T e well-known LiCoO 2 cathode, for example, has a notable valence EELS feature from 8–9 eV. T is feature has a signifi cantly higher jump ratio than the Li-K edge, enabling analysis of noisy spectra due to a thick sample or minimized electron dosage. Spectrum imaging of this valence EELS feature also yields maps that more accurately represent the morphology and distribution of LiCoO 2 particles than mapping of the Li-K edge, especially in thick sample regions. T ese advantages may be useful for sample quality control, post-acquisition analysis of data, and further developments of LIBs and related energy storage systems.
EELS spectrum image of LiCoO 2 particles, using the 2 nd derivative of the 8–9 eV valence EELS feature. The morphology and distri- bution of LiCoO 2 is accurately shown, even in the center region where the sample thickness is > 200 nm. The spectrum image also distinguishes between LiCoO 2 and the underlying carbon support, which is useful when studying materials mixed with carbon compounds for cycling in a battery.
56 doi: 10.1017/S1551929518000639
www.microscopy-today.com • 2018 July
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