Nanoengineered Core-Shell Structures Using Tubile Halloysite Clay

Halloysite nanotubes are a versatile nanomaterial that can be used in a wide variety of applications. They have a unique structure which could be described as a flat material that consists of silica on one side and alumina on the other; this structure is rolled up in a way naturally forming an internal 10-15 nm lumen and interlayer spacing. This could lead to many potential applications for example incorporating halloysite as a template material or as a support structure. They are an inexpensive clay material that is available in large quantities (thousands of tons), so they may be practically used in industrial applications. In this work, they were used as a support structure for catalysts, gas sensors, as well as lithium sulfur batteries. In catalysis it is essential to minimize aggregation of catalytic nanoparticles as aggregation leads to a reduction of surface area used for conducting chemical reactions. Support structures are used to minimize this aggregation. Halloysite nanotubes were used as a support structure to chemically attach two different catalytic metal nanoparticles: cobalt and ruthenium. There are a variety of techniques to synthesize catalytic nanoparticles onto/inside halloysite. To enhance inner-wall and lumen metal cluster formation for ruthenium, we intercalated the tube with furfuraldehyde and then converted it to tetradentate ligands which have shown specific binding to Ru3+ ions from ethanol solution at elevated temperatures. One of the purposes of the ligands is to increase the amount of ruthenium loaded inside the halloysite. The other purpose is to firmly hold the ruthenium inside the halloysite to prevent leakage of Ru. Metal particles of 2-5 nm diameters were formed both in the central lumen and in the interlayer spaces of the tube walls. This core-shell engineered catalyst was tested in hydrogenation of aromatics. Maximum turnover frequency (TOF) achieved was 17282 h-1 in terms of hydrogen uptake per surface area of Ru-atoms. For halloysite-based ruthenium catalysts some metal leaching was observed after the 1st reaction cycle, which may be attributed to poorly retained nanoparticles located outside of the nanotubes, but these Ru-core-shell nanocatalysts were recycled up to ten times without loss of catalytic activity. Halloysite was also used to load cobalt for catalytic purposes. Active cobalt mesocatalysts were prepared using four main methods: Wet impregnation of cobalt chloride into halloysite, adsorption of cobalt (II, III) oxide onto halloysite, and cobalt chloride linkage onto/into halloysite using azines as well as APTES. It turned out that the most efficient catalyst was the halloysite loaded with cobalt chloride using the azine acetone as a ligand with an R value (L/min x g(cat)) of three, which is higher than other previously made cobalt mesocatalysts which typically range from 0.9-2.9. In addition to supporting metal catalytic nanoparticles, halloysite was used to load zirconia nanoparticles for gas sensor applications. We synthesized Y2O3-ZrO2 on halloysite clay nanotubes, an example of an external metal oxide – internal ceramic coreshell system. This produced 5-10 nm diameter particles on the nanotubes. This system should limit the particle agglomeration at working temperatures of 500 ºC. Halloysite nanotubes were also used as a nanoconfinement structure to load sulfur particles for increasing lithium-sulfur battery efficiency. The available nanoscale space in the lumen of halloysites nanotubes and between assembled halloysites clusters help suppress the dissolution and migration of polysulfides in liquid electrolyte solution. The halloysite-sulfur cathode composite was incorporated into coin batteries, and the halloysite/sulfur composites successfully improve the cycling stability, retaining ~84% of the starting capacity for over 250 cycles

Examining consumers\u27 cognitive and behavioral responses to belief disconfirmation

This study explores possible reasons for why consumers persist in their beliefs despite being exposed to substantial disconfirming evidence. The theory of cognitive dissonance (Festinger 1957) provides an important foundation for the pervasiveness of the confirmation bias and belief perseverance. Four main research paradigms of cognitive dissonance theory are discussed: free choice, induced or forced compliance, belief disconfirmation, and hypocrisy. Confirmation bias and belief perseverance are positioned in the belief disconfirmation paradigm. Confirmation bias refers to the general tendency to readily accept evidence that supports one\u27s beliefs and to reject or avoid evidence that goes against such beliefs. Belief perseverance, a phenomenon attributed to the confirmation bias, is the tendency to continue believing what we do in the face of disconfirming evidence. This study assesses whether contrary evidence has an effect on consumer beliefs regarding the perceived benefits of organic food consumption. Dissonance research in marketing has primarily focused on consumer decision making and post-purchase regret. For this reason, the study examines the impact of prepurchase cognitive dissonance using a mixed methods approach. Subjects are exposed to considerable disconfirming evidence, and subsequent belief perseverance (or change) is examined. These effects on cognitive dissonance and purchase behavior are tested. A qualitative assessment of open-ended responses regarding instances of belief perseverance is also conducted; results and key managerial implications are discussed

The influence of consumer freeloading behavior on an observer\u27s and perpetrator\u27s affective commitment

The dissertation explores the relationship between customer affective commitment and freeloading behavior. Consumer freeloading results when a consumer takes advantage of a system or market procedures in a way that allows him or her to obtain benefits from a value proposition with no or reduced monetary costs. Thus, the freeloading consumer works the value equation in his/her favor at the expense of the marketer and/or other consumers. In addition to examining the point of view of the consumer performing the unethical behavior, the dissertation also examines the impact of such behavior on a third party observer. How do loyal consumers (versus not so loyal consumers) react in the face of obvious opportunism against the firm they identify with (or do not identify with)? Justice sensitivity, a personality variable that predicts when and how people react to witnessed or experienced injustice, is hypothesized to moderate the relationship between self-conscious emotions, namely guilt and empathy, and observer\u27s and perpetrator\u27s affective commitment

On the integrated behaviour of non-stationary volatility in stock markets

This paper analyses the behaviour of volatility for several international stock market indexes, namely the SP 500 (USA), the Nikkei (Japan), the PSI 20 (Portugal), the CAC 40 (France), the DAX 30 (Germany), the FTSE 100 (UK), the IBEX 35 (Spain) and the MIB 30 (Italy), in the context of non-stationarity. Our empirical results point to the evidence of the existence of integrated behaviour among several of those stock market indexes of different dimensions. It seems, therefore, that the behaviour of these markets tends to some uniformity, which can be interpreted as the existence of a similar behaviour facing to shocks that may affect the worldwide economy. Whether this is a cause or a consequence of market globalization is an issue that may be stressed in future work.Comment: 10 pages, 3 figures. Paper presented in the APFA 5 conferenc

On the integrated behaviour of non-stationary volatility in stock markets

This paper analyses the behaviour of volatility for several international stock market indexes, namely the SP 500 (USA), the Nikkei (Japan), the PSI 20 (Portugal), the CAC 40 (France), the DAX 30 (Germany), the FTSE 100 (UK), the IBEX 35 (Spain) and the MIB 30 (Italy), in the context of non-stationarity. Our empirical results point to the evidence of the existence of integrated behaviour among several of those stock market indexes of different dimensions. It seems, therefore, that the behaviour of these markets tends to some uniformity, which can be interpreted as the existence of a similar behaviour facing to shocks that may affect the worldwide economy. Whether this is a cause or a consequence of market globalization is an issue that may be stressed in future work.Comment: 10 pages, 3 figures. Paper presented in the APFA 5 conferenc

Cardiomyopathy Secondary to Thyroid and Parathyroid Dysfunction: Case Report and Literature Review

Heart failure due to metabolic derangements is not common in clinical practice. However, outcome is usually positive given that the precipitating factor is recognized and treatment is initiated in a timely fashion. We report an unusual case of reduced left ventricular systolic function as a result of hypocalcemia and long standing untreated primary hypothyroidism in a patient without structural heart disease. Delay in seeking appropriate medical attention for both disorders has culminated in cardiac dysfunction that was favorably altered with correction of underlying etiologies. Therefore, early recognition and expedient management of hypocalcemia and hypothyroidism can result in an imminent improvement of cardiac function

Islamic Monetary Economics: Insights from the Literature

This chapter reviews critical early literature of Islamic monetary economics. The prohibition of Riba has imposed challenges on Islamic economists to come up with the viable alternatives to achieve Islamic monetary policy goals. Our extensive review of theoretical and empirical literature indicates that equity based profit- and loss-sharing instruments have been proposed for conducting open market operations in an interest-free economy. Theoretically, the central bank can achieve desired goals by controlling money supply and profit-sharing ratios. The findings from empirical literature suggest that money demand tend to be more stable in an interest-free economy. Whether monetary transmission works through Islamic banking channel is controversial, but the literature is growing. These findings are not surprising as majority Muslim countries lack sustainable and equitable economic growth. Moreover, these countries suffer from higher inflation and unemployment with little or no monetary freedom due to fixed exchange rate regime, shallow financial markets and strict capital control