Low-energy electron diffraction effects at complex interfaces

Low-energy electron scattering was used as a tool to study electron-stimulated processes at complex interfaces. The electron diffraction in each complex interface is theoretically treated by a multiple scattering formalism for quantitative analysis. Mathematical descriptions of electron-stimulated processes and a multiple scattering expansion extended from the single-scattering case are presented. This analysis method was applied in three research topics: These are 1) electron-stimulated desorption of Cl+ from Si surfaces, 2) characterization of epitaxial graphene on Si-terminated SiC(0001), and 3) low-energy electron induced DNA damage. Zone-specific desorption of Cl+ from Si(111)- 7X7:Cl surfaces was demonstrated. Graphene epitaxially grown on SiC(0001) surfaces was analyzed using Auger electron diffraction and Raman scattering spectroscopy. Finally, the roles of interfacial water and dissociative electron attachment resonances in low-energy electron-induced DNA damage were revealed. Electron scattering calculations using the "path approach" were applied in all of the above mentioned studies. The combination of theory and experiment has lead to insight regarding electron scattering with complex targets.Ph.D.Committee Chair: Thomas Orlando; Committee Member: Joseph Perry; Committee Member: Nicholas Hud; Committee Member: Phillip First; Committee Member: Rigoberto Hernande

Phosphoinositide 3-Kinase Regulates Glycolysis through Mobilization of Aldolase from the Actin Cytoskeleton

The phosphoinositide 3-kinase (PI3K) pathway regulates multiple steps in glucose metabolism and also cytoskeletal functions, such as cell movement and attachment. Here, we show that PI3K directly coordinates glycolysis with cytoskeletal dynamics in an AKT-independent manner. Growth factors or insulin stimulate the PI3K-dependent activation of Rac, leading to disruption of the actin cytoskeleton, release of filamentous actin-bound aldolase A, and an increase in aldolase activity. Consistently, PI3K inhibitors, but not AKT, SGK, or mTOR inhibitors, cause a significant decrease in glycolysis at the step catalyzed by aldolase, while activating PIK3CA mutations have the opposite effect. These results point toward a master regulatory function of PI3K that integrates an epithelial cell's metabolism and its form, shape, and function, coordinating glycolysis with the energy-intensive dynamics of actin remodeling