Activity and deactivation studies for direct dimethyl ether synthesis using CuO-ZnO-Al2O3 with NH(4)ZSM-5, HZSM-5 or gamma-Al2O3

Herein we investigate the use of CuO-ZnO-Al2O3 (CZA) with different solid acid catalysts (NH(4)ZSM-5. HZSM-5 or gamma-Al2O3) for the production of dimethyl ether from syngas. It was found that of the solid acids, which are necessary for the dehydration function of the admixed system, the CZA/HZSM-5 bifunctional catalyst with a 0.25 acid fraction showed high stability over a continuous period of 212 h.

As this particular system was observed to loose around 16.2% of its initial activity over this operating period this study further investigates the CZA/HZSM-5 bifunctional catalyst in terms of its deactivation mechanisms. TPO investigations showed that the catalyst deactivation was related to coke deposited on the metallic sites: interface between the metallic sites and the support near the metal-support: and on the support itself. 

Theoretical and photoemission studies of the band structure of CdI

The band structure of CdI has been calculated using a modified semi-empirical tight-binding method and the results obtained have been compared with both angularly averaged and angularly resolved photoemission spectra. The theoretically computed density of states distribution is in excellent agreement with angularly averaged results and all the main features observed experimentally are reproduced in the theory. Angularly resolved spectra have been used to draw up energy band dispersion curves directly and agreement with calculated bands in both the Gamma M and Gamma K directions of the Brillouin zone is good.

GENDER AND CLASS MOBILITY - EVIDENCE FROM THE REPUBLIC-OF-IRELAND

Gender has frequently been identified as the most controversial issue confronting class analysis. In this paper we make use of data from the Republic of Ireland to assess the extent to which the incorporation of women in class mobility analysis alters our understanding of the central processes of social mobility. We find that for married women their husband's class is a more powerful predictor of household poverty and life-style than their own 'class' as indicated by current or previous occupation. With regard to employment mobility we find that the sole source of gender variation in mobility chances relates to differences in the objective opportunity structures faced by men and women. Applying a measured variable model to 'men only' and 'complete' mobility tables reveals only modest differences in the patterns of social fluidity. The inclusion of women in class mobility tables requires little in the way of substantial modification of our understanding of the pattern of class relationships underlying the observed pattern of mobility.

Buckling and Postbuckling Structures: Experimental, Analytical and Numerical Studies

This book provides an in-depth treatment of the study of the stability of engineering structures. Contributions from internationally recognized leaders in the field ensure a wide coverage of engineering disciplines in which structural stability is of importance, in particular the analytical and numerical modelling of structural stability applied to aeronautical, civil, marine and offshore structures. The results from a number of comprehensive experimental test programs are also presented, thus enhancing our understanding of stability phenomena as well as validating the analytical and computational solution schemes presented. A variety of structural materials are investigated with special emphasis on carbon-fibre composites, which are being increasingly utilized in weight-critical structures. Instabilities at the meso- and micro-scales are also discussed. This book will be particularly relevant to professional engineers, graduate students and researchers interested in structural stability.

‘Reconsidering Dermot Bolger’s Grotesquery: Class and Sexuality in The Journey Home’

Dermot Bolger's The Journey Home (1990) narrates an often hyperbolic and overblown diatribe against a litany of social and political ills, which elicited frequently critical responses to the novel from reviewers. Yet Bolger's seminal work remains both popular and controversial because of its capacity to shock and upbraid the false morality of Irish society--a society that the author considered to be riven by class inequalities and official abuses. Bolger employs sexual abuse as a metonym for political corruption in the novel, and this essay explores The Journey Home's surreal story of youth in a working-class Dublin suburb in light of more recent revelations of Ireland's legacy of institutional sexual abuse.

Collaboration in academic medicine:Reflections on gender and advancement

Purpose: Collaboration in academic medicine is encouraged, yet no one has studied the environment in which faculty collaborate. The authors investigated how faculty experienced collaboration and the institutional atmosphere for collaboration. Method: In 2007, as part of a qualitative study of faculty in five disparate U.S. medical schools, the authors interviewed 96 medical faculty at different career stages and in diverse specialties, with an oversampling of women, minorities, and generalists, regarding their perceptions and experiences of collaboration in academic medicine. Data analysis was inductive and driven by the grounded theory tradition. Results: Female faculty expressed enthusiasm about the potential and process of collaboration; male faculty were more likely to focus on outcomes. Senior faculty experienced a more collaborative environment than early career faculty, who faced numerous barriers to collaboration: the hierarchy of medical academe, advancement criteria, and the lack of infrastructure supportive of collaboration. Research faculty appreciated shared ideas, knowledge, resources, and the increased productivity that could result from collaboration, but they were acutely aware that advancement requires an independent body of work, which was a major deterrent to collaboration among early career faculty. Conclusions: Academic medicine faculty have differing views on the impact and benefits of collaboration. Early career faculty face concerning obstacles to collaboration. Female faculty seemed more appreciative of the process of collaboration, which may be of importance for transitioning to a more collaborative academic environment. A reevaluation of effective benchmarks for promotion of faculty is warranted to address the often exclusive reliance on individualistic achievement. © 2009 The Association of American Medical Colleges.

Interstitial Nitrogen in Diamond – Optical and EPR Studies

Nitrogen is one of the most common impurities in diamond. On a substitutional site it acts as a deep donor, approximately 1.7 eV below the conduction band. Irradiation of nitrogen containing diamond and subsequent annealing creates the nitrogen vacancy centre, which has recently attracted much attention for quantum information processing application. Another possible product of irradiation and annealing of nitrogen containing diamond is interstitial nitrogen. Presumably, a mobile carbon interstitial migrates to a substitutional nitrogen to produce an interstitial nitrogen complex which may or may not be mobile. The configuration(s) of interstitial nitrogen related defects (e.g. bond centred, [001]-split) are not known. An infra-red (IR) absorption peak at 1450 cm-1 labelled H1a has been associated with an nitrogen interstitial complex. [1] Theoretical modelling suggested that this IR local mode is due to a bond centred nitrogen interstitial [2]. However, more recent modelling [3] suggests that this defect is mobile at temperatures were H1a is stable and instead assign H1a to two nitrogen atoms occupying a single lattice site in a [001]-split configuration. To date no electron paramagnetic resonance (EPR) spectra have been conclusively associated with an interstitial nitrogen defect.

In this study we present data from new EPR and optical absorption studies in combination with uniaxial stress of nitrogen interstitial related defects in electron irradiated and annealed nitrogen doped diamond. These measurements yield symmetry information about the defects allowing us to determine which of the proposed models are possible. EPR spectra of nitrogen interstitial related defects in samples isotopically enriched with 15N are reported and we show that these explain the lack of previous EPR data for these defects. Correlations between the IR absorbance and the integrated intensity of the new EPR defects are studied for varying irradiation doses and annealing temperatures.