Colloquium: Lorna Gibson, The Hierarchical Structure and Mechanics of Plants
264 MacQuigg Labs
105 W Woodruff Ave
Columbus, OH 43210
United States
Abstract
The cell walls in plant tissues are made up of just four basic building blocks: cellulose, the main structural fiber of the plant kingdom, hemicellulose, lignin and pectin. Although the microstructure of plant cell walls varies in different types of plants, broadly speaking, cellulose fibers reinforce a matrix of hemicellulose and either pectin or lignin. The cellular structure of plants varies, too, from the honeycomb-like cells of wood to the closed-cell, liquid-filled foam-like parenchyma cells of apples and potatoes. The arrangement of the four basic building blocks of plant cell walls and the variations in cellular structure give rise to a remarkably wide range of mechanical properties: the Young’s moduli of parenchyma tissue are roughly 1-6 MPa while those of the densest woods are 28 GPa; and the compressive strengths of parenchyma are about 0.2-1 MPa while those of the densest woods are over 120 MPa. This talk reviews the microstructure of both the cell wall and the cellular structure in three plant materials (wood, arborescent palm stems and parenchyma) to explain the wide range in mechanical properties in plants and the mechanical efficiency of plants.
Bio
Professor Lorna Gibson graduated in Civil Engineering from the University of Toronto and obtained her Ph.D. from the University of Cambridge. She was an Assistant Professor in Civil Engineering at the University of British Columbia for two years before moving to MIT where she is currently the Matoula S. Salapatas Professor of Materials Science and Engineering. Her research interests focus on the mechanics of materials with a cellular structure such as engineering honeycombs and foams, natural materials such as wood, palm and bamboo and medical materials such as trabecular bone and tissue engineering scaffolds. She is the co-author of Cellular Solids: Structure and Properties (with MF Ashby) and of Cellular Materials in Nature and Medicine (with MF Ashby and BA Harley). Recent projects include aerogels for thermal insulation; nanofibrillar cellulose foams; the mechanics of plant materials; the mechanics of porous scaffolds for tissue engineering and the mechanical interactions of biological cells in tissue engineering scaffolds. At MIT, she has served as Chair of the Committee on Women Faculty in the School of Engineering, Chair of the Faculty and Associate Provost.