title: Biomass accessibility analysis using electron tomography.
abstract: BACKGROUND
  Substrate accessibility to catalysts has been a dominant theme in theories of biomass deconstruction. However, current methods of quantifying accessibility do not elucidate mechanisms for increased accessibility due to changes in microstructure following pretreatment.
  
  
  RESULTS
  We introduce methods for characterization of surface accessibility based on fine-scale microstructure of the plant cell wall as revealed by 3D electron tomography. These methods comprise a general framework, enabling analysis of image-based cell wall architecture using a flexible model of accessibility. We analyze corn stover cell walls, both native and after undergoing dilute acid pretreatment with and without a steam explosion process, as well as AFEX pretreatment.
  
  
  CONCLUSIONS
  Image-based measures provide useful information about how much pretreatments are able to increase biomass surface accessibility to a wide range of catalyst sizes. We find a strong dependence on probe size when measuring surface accessibility, with a substantial decrease in biomass surface accessibility to probe sizes above 5-10 nm radius compared to smaller probes.
authors.affiliation: Computational Science Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401 USA.
authors.forename: Jacob D
authors.initials: JD
authors.lastname: Hinkle
authors.affiliation: Biosciences Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401 USA.
authors.forename: Peter N
authors.initials: PN
authors.lastname: Ciesielski
authors.affiliation: Computational Science Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401 USA.
authors.forename: Kenny
authors.initials: K
authors.lastname: Gruchalla
authors.affiliation: Computational Science Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401 USA.
authors.forename: Kristin R
authors.initials: KR
authors.lastname: Munch
authors.affiliation: Biosciences Center, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401 USA.
authors.forename: Bryon S
authors.initials: BS
authors.lastname: Donohoe
keywords: Accessibility; Biomass; Cellulose; Porosimetry; Pretreatment; Tomography