Electronic and optical hybrid materials via self-assembly and nanoimprint lithography

Polymer/nanoparticle hybrid materials organized at the local level by additive driven self-assembly and patterned at the device level using nanoimprint lithography offer versatile approaches to the solution-based fabrication of nanostructured devices. Block copolymers have long held promise for templating periodic functional materials, however the ability to fabricate well-ordered composites with high loadings of nanoparticles and with domain sizes large enough to be useful for the manipulation of visible light has remained challenging. We demonstrate the formation of well-ordered nanocomposites with tunable magnetic and optical characteristics containing up to 70 wt. % of metal, metal oxide and/or semiconducting nanoparticles through phase specific interactions of the particles with the block copolymer templates. In one example metallodielectric 1D photonic crystals with controlled domain spacings between 120 nm and 260 nm were prepared using amphiphilic (polynorbornene-g-polystyrene)-b-(polynorbornene-g-polyethylene oxide) brush BCPs as the templates and hydrogen bonding as a driving force for the selective incorporation of gold NPs into hydrophilic domains at gold core loadings of up to 50 wt.%. In a second example, we prepared composites with tunable magnetic permeability and high Verdet constants by phase selective incorporation of FePt and ZrO2 nanoparticles in poly(styrene-block-2-vinylpyridine) (PS-b-PVP) diblock copolymer templates in collaboration with the Norwood Group at the University of Arizona. The magnetic character of the composite was tuned by controlling the FePt particle size (2-12 nm) and loading within the PVP domains while the refractive index of the composite was tuned by controlling the loading of zirconia nanoparticles. The small size and excellent dispersion of the NPs in the block copolymer domains provide very good optical transmission. Applications include high performance magnetic field imaging sensors and optical isolators. Nanoimprint lithography (NIL) offers high precision patterning of structures as small as 50 nm using wafer-based or roll-to-roll process platforms, however current resist systems offer little functionality. We developed hybrid UV-NIL resists containing up to 90 wt. % nanoparticles with excellent optical transparency for direct patterning of device structures including a readily scalable print, lift, and stack approach for producing large-area, 3D photonic crystal (PC) structures and optical gratings. Grating structures composed of highly filled NP polymer composite resists with tunable refractive indices (RI) between 1.58 and 1.92 at 800 nm were prepared using hybrid resists composed of anatase titania (TiO2) NPs, between 5 and 30 nm in diameter, and a UV-curable acrylate host. The gratings were robust and upon release from a support substrate were oriented and stacked to yield 3D PCs. The grating structure dimensions, line width, depth, and pitch were easily varied by simply changing the imprint mold. A six-layer log-pile stack was prepared using a composite resist containing 50 wt. % TiO2 NPs with an RI of 1.72 and yielded up to 72% reflection at 840 nm. Extension of these approaches to other materials systems and applications will be discussed

Converging transnational financial reporting standards: Validating the joint FASB/IASB concept of information quality

Accelerating cross-border investing activity transformed global financial markets during the latter part of the 20th century. Due to lack of trans-cultural consistency comparability in financial reporting was compromised hindering multinational investment. In light thereof there is a movement afoot among international authorities to converge national financial reporting standards into a single international financial reporting system. In September 2010 Financial Accounting Standards Board and International Accounting Standards Board agreed on a concept of information quality to guide formulation of internationally acceptable financial reporting standards. The Boards\u27 goal is sustenance of local relevance while achieving transnational comparability. Toward that end, instead of trade-offs among qualities of information assumed by previous concepts, the new concept posits faithful representation working in concert with relevance in a sequential approach to information quality. Variously referred to as Framework 2010 the purpose of this dissertation was to determine its validity. The concept was tested using Partial Least Squares methodology over a survey of US accountants. Fundamental qualities of relevance and faithful representation were found to be significant predictors of decision usefulness as were enhancing qualities of verifiability and comparability. Faithful representation was found to be a significant, partial mediator of relationship between relevance (predictor) and decision usefulness (outcome). Final model predicted 43.1% of variance in decision usefulness

IT Outsourcing: Examined Under the Resource-Based View Lens

The proponents of the resource-based view (RBV) have long argued that a firm gains sustainable competitive advantage from those resources and capabilities it controls and which are valuable, rare, imperfectly imitable, and not substitutable. So, does information technology (IT) outsourcing strip companies of any competitive advantage that is attributed to IT? It has been said that information systems that cannot sustain competitive advantage are transient and are not expected to enhance firm valuation. In that case, does it imply that outsourcing of certain aspects of IT can lead to sustained competitive advantage? Therefore, this paper’s main research question is: Does IT outsourcing lead to sustained competitive advantage for a firm? In order to empirically examine this, it is proposed to study the impact of IT outsourcing announcements on firm valuation using the event study methodology

Diffusion-controlled spherulite growth in obsidian inferred from H2O concentration profiles

Spherulites are spherical clusters of radiating crystals that occur naturally in rhyolitic obsidian. The growth of spherulites requires diffusion and uptake of crystal forming components from the host rhyolite melt or glass, and rejection of non-crystal forming components from the crystallizing region. Water concentration profiles measured by synchrotron-source Fourier transform spectroscopy reveal that water is expelled into the surrounding matrix during spherulite growth, and that it diffuses outward ahead of the advancing crystalline front. We compare these profiles to models of water diffusion in rhyolite to estimate timescales for spherulite growth. Using a diffusion-controlled growth law, we find that spherulites can grow on the order of days to months at temperatures above the glass transition. The diffusion-controlled growth law also accounts for spherulite size distribution, spherulite growth below the glass transition, and why spherulitic glasses are not completely devitrified