Title: Cleaning Techniques and Mechanical Properties of Diatom Frustules

Speaker: Trent Lynch, NECIS Student, University of Colorado

Location: Building 940 Auditorium (Sandia CA), Building 980 Room 95 (Sandia NM)

Brief Abstract: The diatom outer shell, or frustule, is composed primarily of silica nanospheres and a complex matrix of proteins (silaffins) that initiate and control the production of silica within the cell and construct the frustules during cellular division.  Because of the frustules' porous framework and multi-scale silica composition, they possess a strong and lightweight structure and therefore the diatom frustule has been found as a favorable system to utilize as a model system in the realization of similar silicified materials in a labroatory setting.  Self-assembling silica nanospheres like these would be immensely useful, especially in further developments/innovation of thin-films and microscopic frameworks.  Before a synthetic system can be produced and understood, the model system of the frustule must be thoroughly studied to learn more about the mechanisms used to produce and assemble the silica frame and its resulting strength.  To further understand the capabilities of the frustule, a thorough processing technique must first be administered to remove the extra-polymeric substance, which coats certain species, and other organic materials, to leave the silica structure in a pristine condition.  Once this is accomplished, mechanical property tests, such as indentation and lithography, can be conducted to gain knowledge of the hardness and elastic modulus of the frustule without having tainted results from organic matter covering the frustule surface.  This presentation will compare several different acid-based cleaning techniques and their efficacy in cleaning diatoms, followed up with a comparison of the mechanical properties of the frustules as a function of species as measured with nanoindentation.

CSRI POC: Blake Simmons, (925) 294-2288