The Effect of Iron Oxide Nanoparticles on the Fate and Transformation of Arsenic in Aquatic Environments

Iron oxides and arsenic are prevalent in the environment. With the increase interest in the use of iron oxide nanoparticles (IONPs) for contaminant remediation and the high toxicity of arsenic, it is crucial that we evaluate the interactions between IONPs and arsenic. The goal was to understand the environmental behavior of IONPs in regards to their particle size, aggregation and stability, and to determine how this behavior influences IONPs-arsenic interactions. A variety of dispersion techniques were investigated to disperse bare commercial IONPs. Vortex was able to disperse commercial hematite nanoparticles into unstable dispersions with particles in the micrometer size range while probe ultrasonication dispersed the particles into stable dispersions of nanometer size ranges for a prolonged period of time. Using probe ultrasonication and vortex to prepare IONPs suspensions of different particle sizes, the adsorption of arsenite and arsenate to bare hematite nanoparticles and hematite aggregates were investigated. To understand the difference in the adsorptive behavior, adsorption kinetics and isotherm parameters were determined. Both arsenite and arsenate were capable of adsorbing to hematite nanoparticles and hematite aggregates but the rate and capacity of adsorption is dependent upon the hematite particle size, the stability of the dispersion and the type of sorbed arsenic species. Once arsenic was adsorbed onto the hematite surface, both iron and arsenic can undergo redox transformation both microbially and photochemically and these processes can be intertwined. Arsenic speciation studies in the presence of hematite particles were performed and the effect of light on the redox process was preliminary quantified. The redox behavior of arsenite and arsenate were different depending on the hematite particle size, the stability of the suspension and the presence of environmental factors such as microbes and light. The results from this study are important and have significant environmental implications as arsenic mobility and bioavailability can be affected by its adsorption to hematite particles and by its surface mediated redox transformation. Moreover, this study furthers our understanding on how the particle size influences the interactions between IONPs and arsenic thereby clarifying the role of IONPs in the biogeochemical cycling of arsenic.

Identity, ideology, and cinema: Making sense of Japan's foreign and security policies in the 1950s and 2000s

Japan is an important ally of the United States–the world’s third biggest economy, and one of the regional great powers in Asia. Making sense of Japan’s foreign and security policies is crucial for the future of peace and stability in Northeast Asia, where the possible sources of conflict such as territorial disputes or the disputes over Japan’s war legacy issues are observed.^ This dissertation explored Japan’s foreign and security policies based on Japan’s identities and unconscious ideologies. It employed an analysis of selected Japanese films from the late 1940s to the late 1950s, as well as from the late 1990s to the mid-2000s. The analysis demonstrated that Japan’s foreign and security policies could be understood in terms of a broader social narrative that was visible in Japanese popular cultural products, including films and literatures. Narratives of Japanese families from the patriarch’s point of view, for example, had constantly shaped Japan’s foreign and security policies. As a result, the world was ordered hierarchically in the eyes of the Japan Self. In the 1950s, Japan tenaciously constructed close but asymmetrical security relations with the U.S. in which Japan willingly subjugated itself to the U.S. In the 2000s, Japan again constructed close relations with the U.S. by doing its best to support American responses to the 9/11 terrorist attacks by mobilizing Japan’s SDFs in the way Japan had never done in the past.^ The concepts of identity and unconscious ideology are helpful in understanding how Japan’s own understanding of self, of others, and of the world have shaped its own behaviors. These concepts also enable Japan to reevaluate its own behaviors reflexively, which departs from existing alternative approaches. This study provided a critical analytical explanation of the dynamics at work in Japan’s sense of identity, particularly with regard to its foreign and security policies.^