1,256 research outputs found

    Study of pyridine-mediated electrochemical reduction of CO2 to methanol at high CO2 pressure

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    © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim The recently proposed highly efficient route of pyridine-catalyzed CO 2 reduction to methanol was explored on platinum electrodes at high CO 2 pressure. At 55 bar (5.5 MPa) of CO 2 , the bulk electrolysis in both potentiostatic and galvanostatic regimes resulted in methanol production with Faradaic yields of up to 10 % for the first 5–10 C cm −2 of charge passed. For longer electrolysis, the methanol concentration failed to increase proportionally and was limited to sub-ppm levels irrespective of biasing conditions and pyridine concentration. This limitation cannot be removed by electrode reactivation and/or pre-electrolysis and appears to be an inherent feature of the reduction process. In agreement with bulk electrolysis findings, the CV analysis supported by simulation indicated that hydrogen evolution is still the dominant electrode reaction in pyridine-containing electrolyte solution, even with an excess CO 2 concentration in the solution. No prominent contribution from either a direct or coupled CO 2 reduction was found. The results obtained suggest that the reduction of CO 2 to methanol is a transient process that is largely decoupled from the electrode charge transfer

    Xe films on a decagonal Al-Ni-Co quasicrystal surface

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    The grand canonical Monte Carlo method is employed to study the adsorption of Xe on a quasicrystalline Al-Ni-Co surface. The calculation uses a semiempirical gas-surface interaction, based on conventional combining rules and the usual Lennard-Jones Xe-Xe interaction. The resulting adsorption isotherms and calculated structures are consistent with the results of LEED experimental data. In this paper we focus on five features not discussed earlier (Phys. Rev. Lett. 95, 136104 (2005)): the range of the average density of the adsorbate, the order of the transition, the orientational degeneracy of the ground state, the isosteric heat of adsorption of the system, and the effect of the vertical cell dimension.Comment: 6 pages, 5 pic

    Role of livestock in human nutrition and health for poverty reduction in developing countries

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    Livestock keeping is critical for many of the poor in the developing world, often contributing to multiple livelihood objectives and offering pathways out of poverty. Livestock keeping also affects an indispensable asset of the poor, their human capital, through its impact on their own nutrition and health. This paper outlines the linkages between livestock keeping and the physical well-being of the poor, and examines a number of commonly held beliefs that misrepresent livestock development issues related to these linkages. These beliefs limit the scope of intervention programs to promote livestock and limit their potential contribution to poverty reduction. Recognition of the complexity of the role livestock play in household decision-making and of the opportunities foregone due to these misconceptions can enhance the ability of livestock to contribute to human well-being in the developing world

    A new purple sulfur bacterium from saline littoral sediments, Thiorhodotvibrio winogradskyi gen. nov. and sp. nov.

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    Two strains of a new purple sulfur bacterium were isolated in pure culture from the littoral sediment of a saline lake (Mahoney Lake, Canada) and a marine microbial mat from the North Sea island of Mellum, respectively. Single cells were vibrioid-to spirilloid-shaped and motile by means of single polar flagella. Intracellular photosynthetic membranes were of the vesicular type. As photosynthetic pigments, bacteriochlorophyll a and the carotenoids lycopene, rhodopin, anhydrorhodovibrin, rhodovibrin and spirilloxanthin were present. Hydrogen sulfide and elemental sulfur were used under anoxic conditions for phototrophic growth. In addition one strain (06511) used thiosulfate. Carbon dioxide, acetate and pyruvate were utilized by both strains as carbon sources. Depending on the strain propionate, succinate, fumarate, malate, tartrate, malonate, glycerol or peptone may additionally serve as carbon sources in the light. Optimum growth rates were obtained at pH 7.2, 33 °C, 50 mol m-2 s-1 intensity of daylight fluorescent tubes and a salinity of 2.2–3.2% NaCl. During growth on sulfide, up to ten small sulfur globules were formed inside the cells. The strains grew microaerophilic in the dark and exhibited high specific respiration rates. No vitamins were required for growth. The DNA base composition was 61.0–62.4 mol% G+C. The newly isolated bacterium belongs to the family chromatiaceae and is described as a member of a new genus and species, Thiorhodovibrio winogradskyi gen. nov. and sp. nov. with the type strain SSP1, DSM No. 6702

    Methodological criteria for the assessment of moderators in systematic reviews of randomised controlled trials : a consensus study

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    Background: Current methodological guidelines provide advice about the assessment of sub-group analysis within RCTs, but do not specify explicit criteria for assessment. Our objective was to provide researchers with a set of criteria that will facilitate the grading of evidence for moderators, in systematic reviews. Method: We developed a set of criteria from methodological manuscripts (n = 18) using snowballing technique, and electronic database searches. Criteria were reviewed by an international Delphi panel (n = 21), comprising authors who have published methodological papers in this area, and researchers who have been active in the study of sub-group analysis in RCTs. We used the Research ANd Development/University of California Los Angeles appropriateness method to assess consensus on the quantitative data. Free responses were coded for consensus and disagreement. In a subsequent round additional criteria were extracted from the Cochrane Reviewers’ Handbook, and the process was repeated. Results: The recommendations are that meta-analysts report both confirmatory and exploratory findings for subgroups analysis. Confirmatory findings must only come from studies in which a specific theory/evidence based apriori statement is made. Exploratory findings may be used to inform future/subsequent trials. However, for inclusion in the meta-analysis of moderators, the following additional criteria should be applied to each study: Baseline factors should be measured prior to randomisation, measurement of baseline factors should be of adequate reliability and validity, and a specific test of the interaction between baseline factors and interventions must be presented. Conclusions: There is consensus from a group of 21 international experts that methodological criteria to assess moderators within systematic reviews of RCTs is both timely and necessary. The consensus from the experts resulted in five criteria divided into two groups when synthesising evidence: confirmatory findings to support hypotheses about moderators and exploratory findings to inform future research. These recommendations are discussed in reference to previous recommendations for evaluating and reporting moderator studies

    Explaining the human resource management preferences of employees: A study of Chinese workers

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    The forces of globalization, technology and the differences or similarities in institutional systems place substantial pressure on convergence and divergence in HRM practices. Moreover, local customs and the responses from employees also pose serious constraints on the degree of convergence or divergence (Rowley and Benson 2002). In other words, there is what might be termed an upward influence coming from the employees. Although companies may benchmark HRM ‘best practices’, the actual adoption and success of these practices depends, to a large extent, on perceptions and acceptance from employees. However, the opinions of non-managerial employees have been largely neglected in the studies of HRM (Cooke 2009; Legge 1995; Guest 2002; Edgar and Geare 2005; Qiao, Khilji and Wang 2009). Cooke (2009), after reviewing studies on HRM in China published between 1998 and 2007 in major business and management journals, reported that two-thirds of the studies had collected data from managers and most of them relied on managers as the sole source for information. Since the information has mainly been provided by managers, there is the potential for bias because feedback from the managers probably reflects the ideal or ‘best practices’ of HRM that those managers want to implement, rather than the actual HR policies or practices being used in the organization. Thus Cooke (2009, p.19) argued that ‘unless we can broaden our research catchment to include views from the widest range of stakeholders, particularly the employees, our understanding of HRM in China remains partial, from management’s lens’. This study explores the HR preferences of Chinese employees, both non-managerial and managerial ones, based on a sample of 2852 questionnaires from companies in China. A number of questions are explored. For example, what do they think of a ‘promotion-from-within’ policy? Do they prefer an individual-based bonus or a group-based bonus? Do they prefer a ‘downward performance appraisal method’ or a ‘multi-source performance appraisal method’? The research findings shows a strong ‘group orientation’ and a great emphasis on ‘soft factors’ such as seniority, loyalty and connections in many HRM areas. The debate on whether Chinese HRM will converge or diverge towards the Western models is still ongoing. Many argue that there could be further convergence towards the Western practices because globalization may place substantial pressure on firms to standardize practices and policies (see Chen, Lawler and Bae 2005). Others argue that HRM is highly context specific in which institutional and cultural forces have enduring influences (see Rowley and Cooke 2010), which indicates a divergent perspective. The third group supports a ‘cross-vergence’ view which argues that there will be signs of convergence in certain areas but Chinese HRM will keep its ‘Chinese characteristics’ (Cooke 2005, 2010; Yeung, Warner and Rowley 2008; Warner 2009a, b). This study supports the ‘cross-vergence’ perspective. It is argued that certain areas of Chinese HRM are converging to the Western model, but the influence of traditional Chinese personnel practices remains strong. A ‘group orientation’, a major emphasis on ‘soft factors’ and a trade union presence is likely to remain as the three main features of Chinese HRM in the long-term

    Wetting transitions of Ne

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    We report studies of the wetting behavior of Ne on very weakly attractive surfaces, carried out with the Grand Canonical Monte Carlo method. The Ne-Ne interaction was taken to be of Lennard-Jones form, while the Ne-surface interaction was derived from an ab initio calculation of Chizmeshya et al. Nonwetting behavior was found for Li, Rb, and Cs in the temperature regime explored (i.e., T < 42 K). Drying behavior was manifested in a depleted fluid density near the Cs surface. In contrast, for the case of Mg (a more attractive potential) a prewetting transition was found near T= 28 K. This temperature was found to shift slightly when a corrugated potential was used instead of a uniform potential. The isotherm shape and the density profiles did not differ qualitatively between these cases.Comment: 22 pages, 12 figures, submitted to Phys. Rev.

    The Psychosocial Work Environment, Employee Mental Health and Organizational Interventions: Improving Research and Practice by Taking a Multilevel Approach

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    Although there have been several calls for incorporating multiple levels of analysis in employee health and wellbeing research, studies examining the interplay between individual, workgroup, organizational and broader societal factors in relation to employee mental health outcomes remain an exception rather than the norm. At the same time, organizational intervention research and practice also tends to be limited by a single-level focus, omitting potentially important influences at multiple levels of analysis. The aims of this conceptual paper are to help progress our understanding of work-related determinants of employee mental health by: (i) providing a rationale for routine multilevel assessment of the psychosocial work environment; (ii) discussing how a multilevel perspective can improve related organizational interventions and (iii) highlighting key theoretical and methodological considerations relevant to these aims. We present five recommendations for future research, relating to using appropriate multilevel research designs, justifying group level constructs, developing group-level measures, expanding investigations to the organizational level, and developing multilevel approaches to intervention design, implementation and evaluation
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