This thesis explores mechanisms of photovoltaic action, bulk current conduction and electric-field-enhanced and chemically catalyzed water dissociation in bipolar membranes, polymeric devices that, when exposed to water and when pretreated to have only H+ and OH‒ as the mobile species, abide by the physics and mimic the behavior of semiconductor pn-junctions. The first study entails the fabrication of a protonic solar cell consisting of a polymeric bipolar membrane sensitized to visible light with covalently bound photoacid dye molecules. Electrodes were applied to either face of the membrane and fed with humidified H2 to form RHEs as part of MEAs that allowed interconversion of electronic and protonic signals. Photon absorption by photoacids covalently bound within the bipolar MEA resulted in proton transfer to water and/or hydroxide. Classical solar cell current-voltage curves and Mott-Schottky analyses in the dark and under illumination showed “reverse” photovoltaic action, consistent with a light-induced loss of protonic mobile charge carriers or dynamic processes in these new polymeric materials. The second study concerns similar bipolar membrane-electrode assemblies (MEAs) but rather than containing photoacidic dyes, the junction is coated with an intermediate polymer that contains organic proton-transfer catalysts, specifically phosphonic acid groups, that are akin to Shockley‒Read‒Hall recombination centers in traditional semiconductors and can enhance the rate of water dissociation at small applied potentials. The report described herein is the first to utilize a polymer scaffold, poly(2,6-dimethyl-1,4-phenylene oxide), to anchor organic functional groups with controlled pKa values in the bipolar membrane. The champion bipolar membrane in the study yielded a two order of magnitude enhancement in the rate of water dissociation compared to the state-of-the-art commercial metal oxide-containing bipolar membrane. A thickness dependence study was performed by varying the dimensions of the phosphonic acid catalyst layer, and insight into the mechanism of water dissociation current and current conduction in the BPM was gained. A numerical model was also developed using the Law of Mass Balance and Poisson-Nernst-Planck transport physics to rationalize experimental trends. The third study utilizes finite-element modeling to identify design principles for a floating reactor capable of direct oceanic carbon capture. A thermodynamically rigorous model was developed to include a web of 13 chemical reactions at play in the system, namely proton-transfer processes between water, dissolved inorganic carbon species, and catalyst species that we propose to functionalize the reactor with to enhance the rate of CO2 capture. Analyses have identified the range of liquid flow rates and vacuum levels at which the system should operate to achieve substantial carbon capture and means to enhance performance using catalysts for specific reaction steps.

This comparative article investigates the different views of the internet—what it could do and what it was for—as they emerged in news media, popular culture, and policy in the United State and Europe before the year 2000. In the United States, the internet was imagined as an inevitability, as the domain of private corporations, and as a new frontier that would usher the United States into an era of global economic dominance. In Europe, the internet was imagined as a technological choice, as a technology subordinate to national institutions, and as a public utility that the state should provide citizens through national telecommunications corporations. Despite these differences, this article shows how, as the century concluded, the political imaginings of the internet in the two locations converged. While EU policymakers increasingly envisioned the internet as a free market and a means for global economic power, U.S. policymakers envisaged it more and more as a requirement for competent democratic citizenship. Europe "Americanized" its internet policies by increasing competition through cuts in state support for national telecommunications corporations, and the United States "Europeanized" theirs by promoting policies designed to bridge the "digital divide." Ultimately, this article shows how the internet served both as an agent of change and a discursive construction through which varying imaginings were contested. In particular, Europe's adoption of the eEurope 2005 project—an endorsement of American-style unsubsidized corporations instead of European-style statist traditions—suggests that the internet functioned as a transatlantic cultural carrier of advanced capitalism.

Exposure to elevated concentrations of vehicle emitted pollutants is associated with negative health effects. Elevated concentrations are typically found within several hundred meters of high traffic roads, where atmospheric dispersion has not sufficiently diluted pollutants. Tall buildings next to roads reduce dispersion, thereby creating pollutant hot spots and increasing exposure to vehicle emissions for city residents. Roadside barriers enhance dispersion of roadway emissions and thus can be used to mitigate elevated concentrations next to large roads. The work in this thesis develops semi-empirical dispersion models that are useful for estimating near road concentrations of vehicle emissions when there are buildings or barriers next to the road.

Dispersion models that account for the effect of near road barriers on concentrations are developed and evaluated with data from a wind tunnel and a field tracer study. The model evaluation shows that the primary effect of roadside barriers is enhancement of the vertical mixing by an amount proportional to the barrier height. Additionally, turbulence is enhanced in the barrier's wake, resulting in more rapid growth of the pollutant plume. The models perform well during neutral and stable atmospheric conditions. During unstable conditions the models overestimate concentrations. A model that accounts for reduction of the mean wind speed in the barrier wake is unbiased for all stabilities.

Models of the impact of tall buildings next to the road on near road concentrations of vehicle emissions are developed. The models are evaluated with data from field measurements conducted in Los Angeles and Riverside counties, CA, and with data from an urban area in Hannover, Germany. The study specifically investigates dispersion in cities with significant building height variability. Model evaluation shows that vertical turbulent transport dominates dispersion in cities. The primary variables governing near road concentrations of vehicle emissions in cities are the ratio of area weighted building height to street width and the vertical averaged standard deviation of vertical velocity fluctuations. The model informs design of transit oriented developments, dense residential areas located in close proximity to transportation infrastructure, which are used to reduce pollution and greenhouse gas emissions due to transportation.