Browsing by Author "Phillip Russell, Committee Member"

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    Bio-Related Noble Metal Nanoparticle Structure Property Realtionships
    (2007-07-29) Leonard, Donovan Nicholas; Stefan Franzen, Committee Co-Chair; Phillip Russell, Committee Member; Don Brenner, Committee Member; John Mackenzie, Committee Member; Gerd Duscher, Committee Chair
    Structure property relationships of noble metal nanoparticles (NPs) can be drastically different than bulk properties of the same metals. This research study used state-of-the-art analytical electron microscopy and scanned probe microscopy to determine material properties on the nanoscale of bio-related Au and Pd NPs. Recently, it has been demonstrated the self-assembly of Au NPs on functionalized silica surfaces creates a conductive surface. Determination of the aggregate morphology responsible for electron conduction was studied by atomic force microscopy (AFM) and scanning electron microscopy (SEM). In addition, changes in the electrical properties of the substrates after low temperature (<350°C) annealing was also studied. It was found that coalescence and densification of the Au NP aggregates disrupted the interconnected network which subsequently created a loss of conductivity. Investigation of bio-related Au⁄SiO2 core-shell NPs determined why published experimental results showed the sol-gel silica shell improved, by almost an order of magnitude, the detection efficiency of a DNA detection assay. Novel 360° rotation scanning TEM (STEM) imaging allowed study of individual NP surface morphology and internal structure. Electron energy loss spectroscopy (EELS) spectrum imaging determined optoelectronic properties and chemical composition of the silica shell used to encapsulate Au NPs. Results indicated the sol-gel deposited SiO2 had a band gap energy of ˜8.9eV, bulk plasmon-peak energy of ˜25.5eV and chemical composition of stoichiometric SiO2. Lastly, an attempt to elicit structure property relationships of novel RNA mediated Pd hexagon NPs was performed. Selected area electron diffraction (SAD), low voltage scanning transmission electron microscopy (LV-STEM), electron energy loss spectroscopy (EELS) and energy dispersive spectroscopy (EDS) were chosen for characterization of atomic ordering, chemical composition and optoelectronic properties of the novel nanostructures. Data from control experiments found the hexagons could be made without RNA and confirmed the presence of nanocrystalline Pd metal NPs in unpurified Pd2(DBA)3 reagent powder. Furthermore, the study determined the hexagon platelets to have a chemical composition of ˜90at% carbon and ˜10at% Pd and a lattice parameter corresponding to molecular crystals of Pd2(DBA)3 precursor, not Pd metal.
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    The Disinfection and Protection of Microorganisms in Complex Water Systems.
    (2010-06-11) Berecz, Michael; Michael Stoskopf, Committee Chair; Thomas Losordo, Committee Member; Jay Levine, Committee Member; Joseph Hightower, Committee Member; Phillip Russell, Committee Member; Michael Stoskopf, Committee Member
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    Electronic Defect Characterization of Strained-Si/SiGe/Si Heterostructure
    (2007-08-22) Zhang, Renhua; George A. Rozgonyi, Committee Chair; Carl M. Osburn, Committee Member; Phillip Russell, Committee Member; Gerd Duscher, Committee Member
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    Fibrous Scaffolds for Tissue Engineering Applications.
    (2010-07-27) Chung, Sangwon; Martin King, Committee Chair; Michael Gamcsik, Committee Chair; Nancy Monteiro, Committee Member; Samuel Hudson, Committee Member; Stephen Michielsen, Committee Member; Phillip Russell, Committee Member
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    Quartz Crystal Microbalance Measurements of Sliding Friction of Inert Gas Films on Lead, Copper, Nickel, and Graphene Surfaces
    (2003-10-30) Winder, Steven Mason; Phillip Russell, Committee Member; Jacqueline Krim, Committee Chair; Christopher Roland, Committee Member; Donald Brenner, Committee Member
    The Quartz Crystal Microbalance (QCM) has been used to record adsorption and sliding friction data for molecularly thin inert gas films, at 77K, on metal surfaces prepared under Ultra High Vacuum (UHV). Adsorption of xenon was studied on nickel, carbonized nickel, copper and lead. Adsorption of krypton was studied on carbonized and clean nickel. Even sub-monolayer quantities of inert gas produce changes in QCM mechanical properties that may be used to estimate coefficients of sliding friction. At 77K, these inert gases are known to adsorb on various surfaces, forming two-dimensional phases analogous to the solid and gas phases exhibited by bulk substances. While previous QCM studies have emphasized the role of two-dimensional solid and liquid phases in damping QCM motion, this work examines the possibility that the two-dimensional gas phase may be the dominant cause of damping at low coverage. QCM data suggest that the sliding motion of the two-dimensional gas phase of inert gases tends to decay within a characteristic time approaching 10 nanoseconds. The 2D solid phase routinely cited as a low friction phase has an order of magnitude higher friction than the 2D gas phase.