Catalytic Water Formation on Platinum: A First-Principles Study

The study of catalytic behavior begins with one seemingly simple process, namely the hydrogenation of O to H2O on platinum. Despite the apparent simplicity its mechanism has been much debated. We have used density functional theory with,gradient corrections to examine microscopic reaction pathways for several elementary steps implicated in this fundamental catalytic process. We find that H2O formation from chemisorbed O and H atoms is a highly activated process. The largest barrier along this route, with a value of similar to1 eV, is the addition of the first H to O to produce OH. Once formed, however, OH groups are easily hydrogenated to H2O with a barrier of similar to0.2 eV. Disproportionation reactions with 1:1 and 2:1 stoichiometries of H2O and O have been examined as alternative routes for OH formation. Both stoichiometries of reaction produce OH groups with barriers that are much lower than that associated with the O + H reaction. H2O, therefore, acts as an autocatalyst in the overall H O formation process. Disproportionation with a 2:1 stoichiometry is thermodynamically and kinetically favored over disproportionation with a l:I stoichiometry. This highlights an additional (promotional) role of the second H2O molecule in this process. In support of our previous suggestion that the key intermediate in the low-temperature H2O formation reaction is a mixed OH and H2O overlayer we find that then is a very large barrier for the dissociation of the second H2O molecule in the 2:1 disproportionation process. We suggest that the proposed intermediate is then hydrogenated to H2O through a very facile proton transfer mechanism.

La ruptura de una economía moral y las deslegitimación de las deudas hipotecarias

In Spain, during the recent housing bubble, purchasing a home seemed the most advantageous strategy to access housing, and there was a wide social consensus about the unavoidability of mortgage indebtedness. However, such consensus has been challenged by the financial and real-estate crisis. The victims of home repossessions have been affected by the transgression of several principles, such as the fair compensation for effort and sacrifice, the prioritisation of basic needs over financial commitments, the possibility of a second chance for over-indebted people, or the State's responsibility to guarantee its citizens' livelihood. Such principles may be understood as part of a moral economy, and their transgression has resulted in the emergence of a social movement, the Plataforma de Afectados por la Hipoteca (PAH), that is questioning the legitimacy of mortgage debts. The article reflects on the extent to which the perception of over-indebtedness and evictions as unfair situations can have an effect on the reproduction of the political-economic system, insofar the latter is perceived as able or unable to repair injustice.

Legitimising Quality Principles through Critical Incidents in Organisational Development

Purpose – The aim of this paper is to analyse how critical incidents or organisational crises can be used to check and legitimise quality management change efforts in relation to the fundamental principles of quality. Design/methodology/approach – Multiple case studies analyse critical incidents that demonstrate the importance of legitimisation, normative evaluation and conflict constructs in this process. A theoretical framework composed of these constructs is used to guide the analysis. Findings – The cases show that the critical incidents leading to the legitimisation of continuous improvement (CI) were diverse. However all resulted in the need for significant ongoing cost reduction to achieve or retain competitiveness. In addition, attempts at legitimising CI were coupled with attempts at destabilising the existing normative practice. This destabilisation process, in some cases, advocated supplementing the existing approaches and in others replacing them. In all cases, significant conflict arose in these legitimising and normative evaluation processes. Research limitations/implications – It is suggested that further research could involve a critical analysis of existing quality models, tools and techniques in relation to how they incorporate, and are built upon, fundamental quality management principles. Furthermore, such studies could probe the dangers of quality curriculum becoming divorced from business and market reality and thus creating a parallel existence. Practical implications – As demonstrated by the case studies, models, tools and techniques are not valued for their intrinsic value but rather for what they will contribute to addressing the business needs. Thus, in addition to being an opportunity for quality management, critical incidents present a challenge to the field. Quality management must be shown to make a contribution in these circumstances. Originality/value – This paper is of value to both academics and practitioners.