University of Waterloo
200 University Avenue West
Waterloo, Ontario, Canada N2L 3G1
Phone: (519) 888-4567 ext 32215
Fax: (519) 746-8115
Dr. Scholz uses electron microscopy to determine the compositional and crystallographic structure of compounds. His facility houses a Philips CM20 Super Twin High Resolution Transmission Electron Microscope, and he invites researchers to make use of this modern, high voltage equipment.
The Philips CM20 HRTEM is fitted with a cold stage, EDX for chemical microanalysis and a CCD camera for ease of recording, analysis and distribution of digital images. My research has most recently focused on two exciting collaborations, results of which have already been presented in conferences and published. Moreover, these results have also stimulated specifically TEM oriented research of which interdisciplinary graduate student training will be a large component.
(A) Structure and high resolution images of protein aggregates, particularly SuperOxide Dismutase. The TEM analysis of SOD aggregates will form a key part of an interdisciplinary study that is based on strong evidence that a disease like ALS (Lou Gehrig's) may also be a conformational disorder caused by protein folding / misfolding. I have observed the formation SOD fibrils of diameters from about 3 to 25 nm that has already motivated us to propose a novel new mechanism for the formation of SOD aggregates in ALS. Moreover, our TEM results also revealed that the ultrasonication of proteins initiates aggregate formation, previously not realized, that may have far reaching consequences in view of its many uses, including medical. TEM research will expand on these novel findings via (i) low-dose cryo-SAED in an attempted to elucidate SOD's fine structure presently not known; (ii) further expand studies into the effects of sonication on protein aggregation.
(B) Nano-structured plastics are a developing area of significance. We are preparing novel, industrially relevant polyolefin nanocomposites by using in-situ, multi-step intercalation/exfoliation and polymerization reactions of ethylene with montmorillonite (a layered silicate) treated with bifunctional modifiers. Exfoliation transforms the silicate into a nanoparticle, and the proper intercalation of several chemicals and catalysts is fundamental to achieving exfoliation. The TEM will characterize the dispersed phases of montmorillonite via cryo- SAED, CBED and EDX during each stage of the intercalation/exfoliation and subsequent polymerization reactions to establish the 'quality' of each intercalation processes, particularly that of exfoliation, actually achieved.
Other interests include the physics of the intercalation reaction in low dimensional solids. Intercalation refers to the insertion of guest species in the lattice spaces provided by a host material, and is typically accompanied by a charge transfer from the guest to the host. Specifically, the effects of intercalation on:
Dana Pantea1, Sylvie Brochu1, Sonia Thiboutot1, Guy Ampleman1 and Günter Scholz2, "A morphological investigation of Soot coming from the detonation of Munitions". Chemosphere, 65, 821-831 (2006)
1Energetic Materials Section, Defence Research and Development Canada Valcartier 2459 Pie-XI Blvd. North Val-Bélair, Québec, G3J 1X5, Canada.
2Department of Physics, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada
P.B. Stathopulos, G.A. Scholz, J.A. Rumfeldt, J.R. Lepock and E.M. Meiring. "Sonication of Proteins causes formation of aggregates that resemble amyloid". Protein Science, 13 (2004) 3017-3027.
P.B. Stathopulos, J.A. Rumfeldt, G.A. Scholz, R.A. Irani, H.E. Frey, R.A. Hallewell, J.R. Lepock and E.M. Meiring. "Cu/Zn superoxide dismutase mutants associated with amythropic lateral sclerosis show enhaced formation of aggregates in vitro". Proc. Natl. Acad. Sci. USA 100, 7021 - 7026. (2003)
S.Y.A. Shin, L.C. Simon, J.B.P. Soares and G.A. Scholz. "Polyethylene-Clay hybrid nanocompsites; In-situ polymerization using bifunctional organic modifications". Polymer 44, 55317 - 5321 (2003)
G.A. Scholz. "Inducing a CDW ground state in Nb3Se4 by intercalation". Solid State Ionics 149, 131 - 138 (2002)