This integrated experimental and computational study elucidates the mechanisms that contribute to the novel properties of Al/a-Si CSNs and characterizes the tribological properties of surface composed of these nanostructures, which provides a foundation for the rational design of novel technologies based on CSNs. In comparison, (100) Si has substantially higher adhesion and COF (~10 μN and ~0.062, respectively), while the Al nanodots have both higher friction (COF ~0.044) and are deformed when subjected to contact loads as low as 250 μN. NSTSs have a coefficient of friction (COF) as low as 0.015, exhibit low adhesion with adhesion forces on the order of less than 1 μN, and are highly deformation resistant, with no apparent surface deformation after nanoscratch testing, even at contact forces up to 8000 μN. Nanostructure-textured surfaces (NSTSs) composed of Al/a-Si CSNs have improved tribological properties compared surfaces patterned with Al nanodots and a flat (100) Si surface. Furthermore, dislocations nucleated in the core of core-shell nanorods are not as effectively removed as compared to CSNs. Smaller core diameters correlate with the development of a larger back-stress within the core during unloading, which further correlates with improved dislocation annihilation after unloading. The lattice strain interface between SrTiO 3 and BaTiO 3 phase was identified in these coreshell nanoparticles and maintained in the following prepared bulk ceramics. BaTiO 3 layer epitaxially grown on the SrTiO 3 core and formed a per - fect coreshell structure. As the core confinement is reduced, either through an increase in confined core volume or a change in the geometrical confinement, the indentation signatures and deformation resistance are significantly reduced.Ĭomplimentary molecular dynamics simulations show that a substantial amount of dislocation egression occurs in the core of CSNs during unloading as dislocations annihilate at the core/shell interface. coreshell nanoparticles were synthesized by a two-step synthesis process.

This behavior is attributed to dislocation nucleation and annihilation events enabled by the 3-dimensional confinement of the Al core. In conjunction with the indentation signatures, nearly complete deformation recovery is observed. Nanoindentation measurements revealed a unique mechanical response characterized by discontinuous signatures in the load-displacement data. Most notably, these nanostructures exhibit substantial deformation recovery, even when loaded much beyond the elastic limit.

Antibacterial study clearly shows that C-S CuSiNP is more effective than insoluble Cu hydroxide particles and copper sulfate at equivalent metallic Cu concentration, suggesting more soluble Cu in C-S CuSiNP material due to its coreshell design.Al/a-Si core-shell nanostructures (CSNs), consisting of a hemispherical Al core surrounded by a hard shell of a-Si, have been shown to display unusual mechanical behavior in response to compression loading. Bac-light fluorescence microscopy based assay was used to count relative population of the live and dead bacteria cells. THE SYNTHESIS OF CORE-SHELL IRONGOLD NANOPARTICLES AND THEIR CHARACTERIZATION A Thesis Submitted to the Graduate Faculty of the University of New Orleans in partial fulfillment of the requirements for the degree of Master of Science in The Department of Chemistry by Zhihui Ban B.S. The MIC value of C-S CuSiNP against both E.coli and B.subtilis was estimated to be 4.9 ppm. A Thesis Submitted to the Graduate Faculty of the University of New Orleans in partial fulfillment of the requirements for the degree of Master of Science in The Department of Chemistry by Zhihui Ban B.S. Minimum Inhibitory Concentration (MIC) of C-S CuSiNP was evaluated by measuring the fluorescent intensity of resorufin to determine the decrease in viable cells with increase in copper concentration in C-S CuSiNP. THE SYNTHESIS OF CORE-SHELL IRONGOLD NANOPARTICLES AND THEIR CHARACTERIZATION. Antibacterial efficacy of C-S CuSiNP was evaluated against E.coli and B.subtilis using Cu hydroxide (“Insoluble” Cu compound) and copper sulfate as positive control and silica “seed” particles (without Cu loading) as negative control. Loading of Cu to nanoparticles was confirmed by the SEM-Energy Dispersive X-Ray Spectroscopy (EDS) and Atomic Absorption Spectroscopy (AAS). Characterization of particle size distribution in solution by the Dynamic Light Scattering (DLS) technique was fairly consistent with the electron microscopy results. Scanning electron microscopy and transmission electron microscopy showed monodispersed, spherical shaped nanoparticles with smooth surface morphology. Synthesis of the core-shell Cu-silica nanoparticle (C-S CuSiNP) involves preparation of base-hydrolyzed Stöber silica “seed” particles first, followed by the acid-catalyzed seeded growth of the Cu-silica shell layer around the core.

The Stöber silica shell has been engineered to accommodate copper.

A novel core-shell silica based antimicrobial nanoparticle was synthesized.

Core shell nanoparticles thesis