Tooth image credit: Martina Trocchi & Alessia Nava, Sapienza University of Rome, Italy
When: 9 December, 2024, 15:00 - 16:00 CET
Speaker: Joseph Jakes, USDA Forest Service, Forest Products Laboratory, USA
Title: Wood Sample Preparation Strategies for Synchrotron X-ray Research
Abstract
Wood is an anisotropic cellular material with a complex hierarchical structure and hygroscopic cell walls. The development of technologies to fully utilize wood resources is hindered by the lack of fundamental processing-structure-property-performance relationships across all relevant length scales, especially at the small length scales like individual cell wall layers. Synchrotron X-rays provide unique opportunities to study wood across these length scales and gain previously unattainable insights. The penetrating nature of X-rays also make it possible to study wood under different moisture conditions using custom-built relative humidity chambers. Techniques we have utilized include X-ray fluorescence microscopy (XFM), X-ray absorption near edge spectroscopy (XANES), micro X-ray computed tomography (μXCT), and X-ray scattering. Areas of wood science research advanced by synchrotron X-ray research include fungal decay, metal fastener corrosion, wood-adhesive bondlines, moisture-induced swelling/shrinking, and moisture-dependent diffusion through wood cell wall layers.
This seminar will focus on the innovative wood sample preparation techniques we have developed to study wood with synchrotron X-rays. For larger mm-scale experiments of wood cellular structure, we utilize fine-tooth saws, a sliding microtome, and a custom-built razor blade guillotine to prepare samples. For smaller µm-scale experiments on individual wood cell layers, we prepare thin wood sections that are typically only two µm thick. We have developed protocols to cut these thin sections from unembedded wood at room temperature using a diamond knife fit into an ultramicrotome. The thin sections are manipulated using eyelash tools. To hold the thin sections flat for experiments, they are either sandwiched between two SiN windows or stretched across a slot cut into a thin polyimide film with both ends held in place with small pieces of polyimide tape. Although the overall goal is to minimize artifacts caused by sample preparation, some artifacts persist and will also be dicusssed.
Bio
Since 2010 Joseph Jakes has been a Research Materials Engineer in the Forest Biopolymer Science and Engineering group at the USDA Forest Service, Forest Products Laboratory in Madison, WI, USA. He received a BS in Chemical and Biological Engineering from the University of Wisconsin-Madison in 2005. Also, in 2005 he was accepted into a USDA Forest Service student trainee position and began conducting nanoindentation research at the Forest Products Laboratory in pursuit of his PhD, which he received in 2010 from the Materials Science Program at the University of Wisconsin-Madison. His current research interests include developing fundamental wood cell wall processing-structure-property-performance relationships with an emphasis on mechanical behavior, moisture sorption, and diffusion. This research has required the development of advanced material characterization techniques to probe structures and properties at micrometer length scales and below in wood and forest products, which in addition to nanoindentation has led to the development of innovative X-ray and neutron characterization techniques. Joseph has authored over 105 research papers and his work has been recognized through numerous invited talks, an invitation to spend two years as a visiting scientist at the Advanced Photon Source at Argonne National Laboratory (2013-2015), and several awards including the 2012 Presidential Award for Early Career Award for Scientists and Engineers (PECASE), and 2018 TMS Young Leaders Award, and the 2024 Forest Products Society Fred W. Gottschalk Memorial Award.
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