Iron-Based Alloys as Catalysts for CO2 Hydrogenation

Use of CO2 as a chemical feedstock in a wide range of applications has been postulated as a method to reduce its concentrations in the atmosphere, in an effort to combat climate change. An especially attractive use of CO2 is its hydrogenation to hydrocarbon fuels. If coupled with a source of renewably generated H2, this reaction could provide a source of carbon neutral energy that can be readily integrated with current infrastructure. This study looked at the performance of a range of iron-based bimetallic catalysts in promoting CO2 hydrogenation. Specifically, iron-nickel, iron-cobalt and iron-copper supported on βsilicon carbide were studied. It had been reported that these materials were more active and selective towards long chain hydrocarbons than their pure metal counterparts, although the reason was unclear. It was hypothesized that alloy formation in these materials would supresses carbide formation, in turn enhancing CO2 activation and hence reaction performance. The catalysts were synthesized using an ammonium hydroxide modified benzyl alcohol technique, which yielded ferrite nanoparticles below 10 nm with narrow size distribution. These ferrites were supported on silicon carbide via a suspension-deposition technique. In total five catalysts were synthesized – two iron-cobalt, two iron-nickel and one iron-copper. All catalysts were synthesized with a molar ratio of two iron to one counter-metal. The catalysts generally had average particle diameters of 6 nm, with one of the iron-nickel catalysts and the ironcopper catalyst slightly smaller at 3 nm and 2 nm respectively. The supported ferrites were reduced in order to yield the active metallic phase. It was shown via in situ characterization that a body centred cubic (BCC) alloy formed in the iron-cobalt samples (final size of 15 nm), while the iron-nickel samples were comprised of two alloy allotropes, with BCC and face centred cubic (FCC) crystalline structures (final size of 10 nm). The iron-copper sample reduced into pure iron (final size 20 nm) and copper phases. The increased size of the metallic phases compared to the freshly synthesized catalysts was due to sintering of the nanoparticles during reduction. In situ reaction studies showed that the iron-cobalt alloys were remarkably stable, with almost no changes in metallic phase seen. The iron-nickel samples were more readily changed by the reactant gases, with the BCC iron-nickel alloy converted to nickel-containing Hägg carbide. The FCC iron-nickel alloy remained unchanged, however. The iron-copper sample, which demonstrated no alloy formation, had its iron phase completely converted to Hägg carbide. Alloying of iron was thus shown to supress carbide formation. Reaction performance of all catalysts to long-chain hydrocarbons was poor when compared to similar materials tested in the literature, with conversions in the range of 4% - 8%. The product distribution was also undesirable, with the majority of product carbon reporting to CO in all five catalysts. Of the hydrocarbons formed, 80% - 96% reported to undesirable methane, depending on the counter metal used. It seemed that iron carbide in the iron-copper catalyst favoured longer chain hydrocarbon production when compared to the more metallic cobalt- and nickel-containing samples (which produced far more methane), but struggled to activate CO2 past CO. While the iron-cobalt catalysts seemed to facilitate more activation of CO2 to hydrocarbons, they showed less potential in forming longer chain hydrocarbons. The two iron-nickel catalysts behaved differently; one catalyst had a stable FCC phase, while its BCC alloy phase was completely converted to carbides, and favoured mostly methane formation. The other catalyst had a similarly stable FCC phase, but also maintained an appreciable BCC alloy fraction, and showed far more propensity to form longer chain hydrocarbons. This catalyst was still not as successful in promoting chain growth as its ironcopper counterpart, however. When comparing performance of the iron-cobalt and -copper catalysts, it seemed that carbide formation was beneficial in encouraging hydrocarbon chain growth, but detrimental to CO2 activation. On the other hand, the iron-nickel catalysts demonstrated that the BCC alloy phase was required to encourage chain growth, while the carbide resulting from its conversion diminished this. These results indicated that an improvement in the activation of CO2 did not necessarily increase hydrocarbon chain length, and that while carbides may be desirable for encouraging longer chain molecules, the presence of nickel in the carbide spoils the effect, at least in the range of temperatures tested. These results led to rejection of the hypothesis that alloys resulted in bimetallic catalysts' improved performance. They indicated that iron carbides are required for stable conversion of CO2 to longer chain hydrocarbons, but that the carbides alone were not extremely active nor selective. It is therefore likely that the counter metal's role in enhancing activity and selectivity at more dilute concentrations is by modulating the carbide phase. It is thus suggested that the impacts of counter metals in more iron-rich systems be studied, where carbide formation would be more facile. Additionally, the difficulty which the catalysts had in activating CO2 could be mitigated by promotion and use of an active support

Gödel\u27s incompleteness theorem

This thesis gives a rigorous development of sentential logic and first-order logic as mathematical models of humanity\u27s deductive thought processes. Important properties of each of these models are stated and proved including Compactness results (the ability to prove a statement from a finite set of assumptions), Soundness results (a proof given a set of assumptions will always be true given that set of assumptions), and Completeness results (a statement that is true given a set of assumptions must have a proof from that set of assumptions). Mathematical theories and axiomatizations or theories are discussed in a first- order logical setting. The ultimate aim of the thesis is to state and prove Gödel\u27s Incompleteness Theorem for number theory --Document

An evaluation of interpretive media at the Dillon Nature Center

Master of ScienceHorticulture, Forestry, and Recreation ResourcesTed T. CableDillon Nature Center has a wide variety of exhibits that teach the public about the natural resources of Kansas. The purpose of my study was to conduct an exploratory study about the effectiveness of two key exhibits in the nature center (Underground Theater and Tornado), as well as evaluate the use of Quick Response Code or QR codes along one of the trails. A visitor survey was used to collect these data over 30 3- hour sampling periods. One hundred and ninety-five visitors were surveyed during the extent of my study. Fifty-four of those who were surveyed went into the Underground Theater exhibit and 47 went into the Tornado exhibit. I concluded that the Underground Theater exhibit was successful in providing useful information to the visitor, whereas the Tornado exhibit provided little useful information to the visitor. Visitors slightly preferred the use of QR codes along the trail even though the actual use was low. This study indicated that the type of exhibit greatly impacts what the visitor takes away from the exhibit. I also showed that it is likely people prefer newer technology to be available at the nature center. These findings provided the management and staff of Dillon Nature Center with information to guide their interpretive-planning efforts

“He Would Kill Me With His Penis”: Genocidal Rape in Rwanda as a State Crime

Only recently have critical criminologists begun a systematic exploration of genocide, war crimes and crimes against humanity as state crimes (Kramer and Michalowski 2005; Mullins and Rothe 2008; Haveman and Smeulers 2008). This paper contributes to that growing literature through examining the nature and dynamics of sexual violence as it occurred during the 1994 Rwandan genocide. It draws upon empirical examination of events depicted in transcripts of trials held before the International Criminal Tribunal for Rwanda. It qualitatively examines the role of leaders in producing mass sexual assaults. It explores how sexual mutilations were more intense expressions of what the genocide’s local leaders hoped to accomplish through the use of rape in the event. It also explores long-term results of victimization for survivors. Finally, this paper then uses an integrated theory of state crime (see Mullins and Rothe 2008; Rothe and Mullins 2006, 2008a) to illuminate the causal forces at play on multiple levels of analysis in producing the sexual violence specifically within the broader genocide

“We are going to rape you and taste Tutsi women”: Rape During the 1994 Rwandan Genocide

Over the past decades, scholars have paid greater attention to sexual violence, in both theorization and empirical analysis. One area which has been largely ignored, however, is the sexual violence during times of armed conflict. This paper examines the nature and dynamics of sexual violence as it occurred during the 1994 Rwandan genocide. Drawing upon testimonies given to the International Criminal Tribunal for Rwanda (ICTR), descriptions of rapes--both singular and mass—were qualitatively analyzed. In general, three broad types of assaults were identified: opportunistic, assaults which seemed to be a product of the disorder inherent within the conflict; episodes of sexual enslavement; and genocidal rapes, which were framed by the broader genocidal endeavors occurring at the time

Establishing Connections: Gender, Motor Vehicle Theft, and Disposal Networks

As with most other serious street crimes, motor vehicle theft is a male-dominated offense. Yet, women do engage in motor vehicle theft, albeit at a reduced rate of participation. Here we examine the gendered nature of motor vehicle theft through direct comparison of qualitative data obtained from 35 juvenile and adult men and women actively involved auto theft in St. Louis, Missouri. By tracing similarities and differences between men’s and women’s pathways of initial involvement, enactment strategies, and post-theft acts, we provide a contextual analysis of offender’s perceptions and behavior. Such an approach allows a more precise discussion on gender’s influence (or lack of) on motor vehicle theft. Analysis shows that initiation into auto theft and property disposal networks are governed by male gatekeepers, and this leads to some key similarities in techniques between men and women. The ways in which women negotiate male-dominated networks is also discussed with particular emphasis on the innovative strategies they draw upon to accomplish their crimes within these landscapes and when opportunities are constrained by male gatekeepers

Gendered Imprisonment in Japan: An Examination of Imprisonment for Stimulant Drug Offenses

Japan is well known as a society that has not only low crime rates but also for using incarceration sparingly, sending few convicted offenders to prison. Yet, certain crimes, such as drug offenses, receive little leniency in the Japanese criminal justice system. Johnson (1996b) found empirical support for both a chivalry and evil woman effect in the system’s treatment of female drug offenders. This paper reexamines and extends the core issues in Johnson’s (1996b) exploration of women’s imprisonment in Japan. It traces the patterns in female incarceration where data is available from the post-war period until 2004. It specifically examines the incidences of incarceration of women for stimulus drug offenses and identifies key correlates on the macro-level associated with changes in imprisonment practices

Beyond the Juristic Orientation of International Criminal Justice: The Relevance of Criminological Insight to International Criminal Law and its Control

This article draws attention to the relevance of criminological insight on issues of international criminal law and criminal justice. In particular, the ideology and theory of deterrence, legitimacy, and international criminal law are drawn from. After all, the deterrent effect has been touted as a solid empirical fact with the progression and development of \u27international criminal justice\u27, the international tribunals since the mid 1990s, and the International Criminal Court. Yet, the current rather blind belief in the deterrent impact of international criminal justice remains, regretfully, a bit premature. Additionally, beyond the concepts of deterrence and legitimacy, criminologists have much to contribute to international criminal justice. As noted, there are social, political, cultural, and geographical issues that play a role in not only crime commission, but in the hindrance of and/or facilitation of deterrence. Criminologists are well positioned to show how these connections may facilitate or hinder the broader goals of the legal community

The Death of State Sovereignty? An Empirical Exploration

As academics have become increasingly interested in globalization, scholars in many fields have turned their attention to theorizations of the state and state power. Admittedly, most criminologists have paid relatively attention to theories of the state, its function, role, or issues of sovereignty (save for Barak, 1991; Chambliss and Zatz, 1993; Friedrichs, 1992; Michalowski and Kramer, 1987; Mullins and Rothe, 2008; Rothe and Mullins, 2006, 2007, 2008). With the growing criminological interest in and focus on transnational crimes (Friedrichs, 2007), crimes of globalization (Friedrichs and Friedrichs, 2002; Rothe, Mullins, and Muzzatti, 2006; Rothe, Mullins and Sandstrom, 2008), and crime of the state (Kramer et. al., 2005; Michalowski and Kramer, 2006; Rothe and Mullins, 2008), there has been a corresponding shift in the view of the state: one in a ‘globalized’ framework. Many scholars have suggested that the state has been reduced to nothing more than a facilitator of global political, legal, and economic system. As criminologists of state crime, we find this position problematic for the conceptualization and study of governmental crime. We feel that proclaiming states and state sovereignty as eroding and/or dead is premature. In this paper we explore one area in which states seem to be voluntarily abdicating certain elements of sovereignty—the entering into of international treaties. Specifically, we examine how states protect their sovereignty through entering reservations to treaties being signed and ratified. Our findings suggest that despite greater attention in global consciousness amongst countries and economies, states intensely protect their right to self-determination while signing and ratifying treaties, compacts and other international agreements. After providing a detailed discussion of these findings, we conclude that state sovereignty is not eroding and is far from dead