Examining the redox and formate mechanisms for water-gas shift reaction on Au/CeO2 using density functional theory

We perform DFT calculations to investigate the redox and formate mechanisms of water-gas-shift (WGS) reaction on Au/CeO2 catalysts. In the redox mechanism, we analyze all the key elementary steps and find that the OH cleavage is the key step. Three possible pathways of OH cleavage are calculated: (1) OHad '' + *'--> H-ad' + O-ad"; (2) H-ad' + OHad '' --> H-2(g) + O-ad '' + *'; and (3) OHad" + OHad '' --> 2O(ad '') + H-2(g) (*': the free adsorption sites on the oxides; ad': adsorption on the metal; ad": adsorption on the oxide, respectively). In the formate mechanism, we identify all the possible pathways for the formation and decomposition of surface formates in the WGS reaction. It is found that there is a shortcoming in the redox and formate mechanisms which is related to surface oxygen reproduction. Four possible pathways for producing surface oxygen are studied, and all the barriers of the four pathways are more than 1 eV. Our results suggest that the processes to reproduce surface oxygen in the reaction circle are not kinetically easy. (C) 2008 Elsevier B.V. All rights reserved.

Emotions & social change in Ireland:Exploring habitus shift in liquid modernity

Drawing on insights from a range of disciplines, including philosophy, psychology, history, politics, but particularly sociology and sociological theory, this thesis explores the relationship between emotions and social change in late or 'liquid' modernity. It deploys the Republic of Ireland in the twentieth century as a case study. It argues that the Irish case in an ideal site for this research given the speed and scale of changes that have occurred there, particularly since the 1950's. The primary research question guiding the study is: What has been the effect of 'social change' in Ireland on the emotional lives of Irish people? The thesis is structured in three parts. Part one (chapters one to three) is primarily theoretical. It aims to develop a distinctive theoretical framework, process-relational realism, and argues that three concepts, properly treated, are central to answering the research question. These are emotion, power and (emotional) habitus. Part two is a bridging chapter, in which the empirical portion of the study, its design and method, are outlined. This study is based on a series of qualitative life-history interviews conducted using the Biographical Narrative Research Method. Part three is primarily empirical. The first chapter critically explores Bauman's concept of liquid modernity in relation to the Irish case and offers a short social history of the Irish twentieth century, which focuses on emotions and power. The second deploys two (ideal-type) interview cases to support the argument that Ireland experienced a habitus shift, from a relatively homogeneous to a heterogeneous habitus, and a corresponding shift from a relatively repressive emotional regime to a more expressive one, with significant effects on the emotional habitus. The final chapter takes a broader view of these changes, suggests that social change has been ambivalent, and outlines a new typology of emotional pathologies that the study suggests are characteristic of contemporary emotional life.

Energy versus data integrity trade-offs in embedded high-density logic compatible dynamic memories

Current variation aware design methodologies, tuned for worst-case scenarios, are becoming increasingly pessimistic from the perspective of power and performance. A good example of such pessimism is setting the refresh rate of DRAMs according to the worst-case access statistics, thereby resulting in very frequent refresh cycles, which are responsible for the majority of the standby power consumption of these memories. However, such a high refresh rate may not be required, either due to extremely low probability of the actual occurrence of such a worst-case, or due to the inherent error resilient nature of many applications that can tolerate a certain number of potential failures. In this paper, we exploit and quantify the possibilities that exist in dynamic memory design by shifting to the so-called approximate computing paradigm in order to save power and enhance yield at no cost. The statistical characteristics of the retention time in dynamic memories were revealed by studying a fabricated 2kb CMOS compatible embedded DRAM (eDRAM) memory array based on gain-cells. Measurements show that up to 73% of the retention power can be saved by altering the refresh time and setting it such that a small number of failures is allowed. We show that these savings can be further increased by utilizing known circuit techniques, such as body biasing, which can help, not only in extending, but also in preferably shaping the retention time distribution. Our approach is one of the first attempts to access the data integrity and energy tradeoffs achieved in eDRAMs for utilizing them in error resilient applications and can prove helpful in the anticipated shift to approximate computing.