Stellar population gradients in Seyfert 2 galaxies. Northern sample

We use high signal-to-noise ratio long-slit spectra in the 3600-4700A range of the twenty brightest northern Seyfert 2 galaxies to study the variation of the stellar population properties as a function of distance from the nucleus. In order to characterize the stellar population and other continuum sources (e.g. featureless continuum FC) we have measured equivalent widths Ws of six absorption features, four continuum colours and their radial variations, and performed spectral population synthesis as a function of distance from the nucleus. About half the sample has CaIIK and G-band W values smaller at the nucleus than at 1 kpc from it, due to a younger population and/or FC. The stellar population synthesis shows that, while at the nucleus, 75% of the galaxies present contribution > 20% of ages younger or equal than 100Myr and/or of a FC, this proportion decreases to 45% at 3 kpc. In particular, 55% of the galaxies have contribution > 10% of the 3 Myr/FC component (a degenerate component in which one cannot separate what is due to a FC or to a 3 Myr stellar population) at the nucleus, but only 25% of them have this contribution at 3 kpc. As reference, the stellar population of 10 non-Seyfert galaxies, spanning the Hubble types of the Seyfert (from S0 to Sc) was also studied. A comparison between the stellar population of the Seyferts and that of the non-Seyferts shows systematic differences: the contribution of ages younger than 1 Gyr is in most cases larger in the Seyfert galaxies than in non-Seyferts, not only at the nucleus but up to 1 kpc from it.Comment: 23 pages, 18 figures, MNRAS in pres

Modified electrodes for electrochemical reduction of carbon dioxide

The efforts to constrain greenhouse gas emissions and concerns over security of fossil fuels have led to increased attention for renewable energy for the past decade. Renewable energy is one of the key solutions to the actual energy challenges. Omnidea in collaboration with Research Institutes is developing a technology based upon a regenerative energy storage cycle that could be a contribution to a low-carbon energy future. In this cycle the recharge system, which is composed of an electrochemical cell, converts CO2 into fuel (hydrocarbons and hydrogen) using an external source of power (e.g. solar power). The discharge system produces electric energy when hydrocarbons and oxygen from the recharge system are directly supplied to a Solid Oxide Fuel Cell (SOFC). Currently state of the art systems for direct electrochemical reduction of CO2 exhibit low current densities and or low Faradaic efficiencies. Thus considerable research activity is still needed to develop electrodes with a performance suitable for an industrial application. This paper describes the progress to date and the work carried out with the aim of achieving this goal. It addresses particularly the modification of electrodes for electrochemical conversion of CO2 and reports voltammetric studies as a tool for screening and optimizing electrodes for CO2 conversio

Conversion of carbon dioxide into fuel by electrochemical reduction in aqueous solvents

he mission of Omnidea, a Portuguese SME is to perform leading edge R&D in innovative energy concepts. In collaboration with Research Institutes Omnidea is developing a technology based upon a regenerative energy storage cycle. In this cycle the recharge system converts CO2 into hydrocarbons using a renewable source of power. The discharge system produces electrical energy when hydrocarbons and oxygen from the recharge system are directly supplied to a device such as a Solid Oxide Fuel Cell (SOFC). This work focuses on the challenges involved in the task of bringing this technology closer to the market. A key feature of this technology is the use of copper which is known to have unique properties for converting CO2 electrochemically into hydrocarbons. The modification of copper electrodes with copper deposits to improve the catalytic activity and selectivity of the cathodes in the production of hydrocarbons in aqueous solvents is also described

Research and Consultancy Services in the Mining Industry in Zimbabwe: A Coordinated Approach Through the Mineral Resources Centre

IMR Report.Education in the engineering fields can be considerably enhanced if it is designed to address the immediate and long-term needs of society. In this context education not only comprises the provision of basic training, but also includes the careful planning and execution of applied and fundamental research. This paper focuses on education and research institutions that provide services to the mining sector in Zimbabwe and describes a new approach to meeting high-quality teaching, research and consultancy requirements against a background of diminishing government funding. Key units within the University of Zimbabwe providing services to the mining industry include the Institute of Mining Research, The Departments of Geology and Physics in the Faculty of Science and Mining Engineering and Metallurgy in the Faculty of Engineering. Within government, services are provided principally by the Departments of Geological Survey, Metallurgy and Mining Engineering, and the Scientific and Industrial Research and Development Centre. The major source of funding for all of these institutions is Government. There is a degree of overlap between these institutions, some of which were established more than 30 years ago with terms of reference appropriate for the time. With decreasing funding exacerbated by a harsh economic climate in Zimbabwe there is need to revisit the charters of these organizations and to review the provision of services to the mining sector. Recognition of this situation has led the Department of Geology to spearhead a new initiative to establish an alternative structure through which consultancy and research in mining related topics can be coordinated at the University of Zimbabwe. The Mineral Resources Centre (MRC) was established to facilitate fund-raising activities through consultancy services, research, postgraduate training and capital investment. By representing a group of like-minded stakeholders, the MRC can address larger projects, and thus secure more funding than individual entities will be able to obtain. The MRC is designed to be a lightweight structure that will not replace any of the existing teaching and research departments. The MRC is not be bound to any particular faculty within the university, and may even include stakeholders from outside the university. Interested parties are invited to participate on a voluntary basis in accordance with the management and quality- control guidelines laid out by the MRC. Participation is on a contract basis and will be determined for each project. Service providers that participate in the MRC agree to use their resources in the best possible way, so that services can be presented in unison. In combining forces between various departments with expertise in Earth Sciences, it is envisaged that a wider audience can be reached, a better service can be provided and a larger resource base can be tapped both within the private and the public sectors. The MRC may help coordinate capital investment, and human resource development in the various participating entities. Considering the limited availability of financial and human resources in Zimbabwe, coordination and prevention of unnecessary overlap is in itself a valuable exercise

Possible unconventional superconductivity in substituted BaFe2_{2}As2_{2} revealed by magnetic pair-breaking studies

The possible existence of a sign-changing gap symmetry in BaFe$_{2}$As$_{2}$-derived superconductors (SC) has been an exciting topic of research in the last few years. To further investigate this subject we combine Electron Spin Resonance (ESR) and pressure-dependent transport measurements to investigate magnetic pair-breaking effects on BaFe$_{1.9}M_{0.1}$As$_{2}$ ($M=$ Mn, Co, Cu, and Ni) single crystals. An ESR signal, indicative of the presence of localized magnetic moments, is observed only for $M=$ Cu and Mn compounds, which display very low SC transition temperature ($T_{c}$) and no SC, respectively. From the ESR analysis assuming the absence of bottleneck effects, the microscopic parameters are extracted to show that this reduction of $T_{c}$ cannot be accounted by the Abrikosov-Gorkov pair-breaking expression for a sign-preserving gap function. Our results reveal an unconventional spin- and pressure-dependent pair-breaking effect and impose strong constraints on the pairing symmetry of these materials