137 research outputs found

    Transport coefficients for electrolytes in arbitrarily shaped nano and micro-fluidic channels

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    We consider laminar flow of incompressible electrolytes in long, straight channels driven by pressure and electro-osmosis. We use a Hilbert space eigenfunction expansion to address the general problem of an arbitrary cross section and obtain general results in linear-response theory for the hydraulic and electrical transport coefficients which satisfy Onsager relations. In the limit of non-overlapping Debye layers the transport coefficients are simply expressed in terms of parameters of the electrolyte as well as the geometrical correction factor for the Hagen-Poiseuille part of the problem. In particular, we consider the limits of thin non-overlapping as well as strongly overlapping Debye layers, respectively, and calculate the corrections to the hydraulic resistance due to electro-hydrodynamic interactions.Comment: 13 pages including 4 figures and 1 table. Typos corrected. Accepted for NJ

    Adsorption of CO on a Platinum (111) surface - a study within a four-component relativistic density functional approach

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    We report on results of a theoretical study of the adsorption process of a single carbon oxide molecule on a Platinum (111) surface. A four-component relativistic density functional method was applied to account for a proper description of the strong relativistic effects. A limited number of atoms in the framework of a cluster approach is used to describe the surface. Different adsorption sites are investigated. We found that CO is preferably adsorbed at the top position.Comment: 23 Pages with 4 figure

    Molecular Mobility in a Poly(ethylene glycol)-Poly(vinyl pyrrolidone) Blends: Study by the Pulsed Gradient NMR Techniques

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    The molecular mobility in PEG-PVP blends as a function of the time of system storage and the PVP molecular mass is studied by the pulsed-field gradient NMR method. The distribution of PEG molecules over their mobilities is found in a blend containing 36 vol % of PEG with the molecular mass of 400 g/mol. As the storage time of the system increases, the spectrum of diffusion coefficient values varies, thereby indicating the redistribution of PEG400 molecules in the blend with PVP. An anomalous (partly restricted) diffusion of PEG400 molecules is discovered, reflecting the influence of PVP macromolecules on the motion of short PEG chains. It is shown that, during the redistribution of PEG molecules in the blend, they are involved in a complex with PVP, which is characterized by its own transport properties. The data obtained by the NMR relaxation technique are in agreement with the results of NMR diffusion measurements in the studied systems

    Compiling and using input-output frameworks through collaborative virtual laboratories

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    Compiling, deploying and utilising large-scale databases that integrate environmental and economic data have traditionally been labour- and cost-intensive processes, hindered by the large amount of disparate and misaligned data that must be collected and harmonised. The Australian Industrial Ecology Virtual Laboratory (IELab) is a novel, collaborative approach to compiling large-scale environmentally extended multi-region input-output (MRIO) models.The utility of the IELab product is greatly enhanced by avoiding the need to lock in an MRIO structure at the time the MRIO system is developed. The IELab advances the idea of the "mother-daughter" construction principle, whereby a regionally and sectorally very detailed "mother" table is set up, from which "daughter" tables are derived to suit specific research questions. By introducing a third tier - the "root classification" - IELab users are able to define their own mother-MRIO configuration, at no additional cost in terms of data handling. Customised mother-MRIOs can then be built, which maximise disaggregation in aspects that are useful to a family of research questions.The second innovation in the IELab system is to provide a highly automated collaborative research platform in a cloud-computing environment, greatly expediting workflows and making these computational benefits accessible to all users.Combining these two aspects realises many benefits. The collaborative nature of the IELab development project allows significant savings in resources. Timely deployment is possible by coupling automation procedures with the comprehensive input from multiple teams. User-defined MRIO tables, coupled with high performance computing, mean that MRIO analysis will be useful and accessible for a great many more research applications than would otherwise be possible. By ensuring that a common set of analytical tools such as for hybrid life-cycle assessment is adopted, the IELab will facilitate the harmonisation of fragmented, dispersed and misaligned raw data for the benefit of all interested parties. © 2014 Elsevier B.V

    Implementing the material footprint to measure progress towards Sustainable Development Goals 8 and 12

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    Sustainable development depends on decoupling economic growth from resource use. The material footprint indicator accounts for environmental pressure related to a country’s final demand. It measures material use across global supply-chain networks linking production and consumption. For this reason, it has been used as an indicator for two Sustainable Development Goals: 8.4 ‘resource efficiency improvements’ and 12.2 ‘sustainable management of natural resources’. Currently, no reporting facility exists that provides global, detailed and timely information on countries’ material footprints. We present a new collaborative research platform, based on multiregional input–output analysis, that enables countries to regularly produce, update and report detailed global material footprint accounts and monitor progress towards Sustainable Development Goals 8.4 and 12.2. We show that the global material footprint has quadrupled since 1970, driven mainly by emerging economies in the Asia-Pacific region, but with an indication of plateauing since 2014. Capital investments increasingly dominate over household consumption as the main driver. At current trends, absolute decoupling is unlikely to occur over the next few decades. The new collaborative research platform allows to elevate the material footprint to Tier I status in the SDG indicator framework and paves the way to broaden application of the platform to other environmental footprint indicators

    Science journalism and a multi-directional science-policy-society dialogue are needed to foster public awareness for biodiversity and its conservation

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    Biodiversity is the manifestation of life on our planet and provides manifold benefits for humans. Yet we destroy ecosystems and drive species to extinction. We submit that anthropogenic biodiversity loss does not yet receive sufficient public attention, although biodiversity conservation and its sustainable use are key to mitigate global crises. Effective communication of biodiversity-related knowledge with diverse audiences is therefore crucial and should contribute to ensuring that evidence guides environmental decision-making. In this context, it is essential to stimulate multi-directional dialogues between science, policy, and society. Here, we suggest Dos and Don’ts that can guide science communication for scientists working in biodiversity research and beyond. Moreover, we emphasize the role of science journalism and other institutions specialized in science communication in critically mediating the complexity of scientific knowledge

    Modular microfluidic system as a model of cystic fibrosis airways

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    A modular microfluidic airways model system that can simulate the changes in oxygen tension in different compartments of the cystic fibrosis (CF) airways was designed, developed, and tested. The fully reconfigurable system composed of modules with different functionalities: multichannel peristaltic pumps, bubble traps, gas exchange chip, and cell culture chambers. We have successfully applied this system for studying the antibiotic therapy of Pseudomonas aeruginosa, the bacteria mainly responsible for morbidity and mortality in cystic fibrosis, in different oxygen environments. Furthermore, we have mimicked the bacterial reinoculation of the aerobic compartments (lower respiratory tract) from the anaerobic compartments (cystic fibrosis sinuses) following an antibiotic treatment. This effect is hypothesised as the one on the main reasons for recurrent lung infections in cystic fibrosis patients

    Revival of the magnetar PSR J1622-4950: observations with MeerKAT, Parkes, XMM-Newton, Swift, Chandra, and NuSTAR

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    New radio (MeerKAT and Parkes) and X-ray (XMM-Newton, Swift, Chandra, and NuSTAR) observations of PSR J1622-4950 indicate that the magnetar, in a quiescent state since at least early 2015, reactivated between 2017 March 19 and April 5. The radio flux density, while variable, is approximately 100x larger than during its dormant state. The X-ray flux one month after reactivation was at least 800x larger than during quiescence, and has been decaying exponentially on a 111+/-19 day timescale. This high-flux state, together with a radio-derived rotational ephemeris, enabled for the first time the detection of X-ray pulsations for this magnetar. At 5%, the 0.3-6 keV pulsed fraction is comparable to the smallest observed for magnetars. The overall pulsar geometry inferred from polarized radio emission appears to be broadly consistent with that determined 6-8 years earlier. However, rotating vector model fits suggest that we are now seeing radio emission from a different location in the magnetosphere than previously. This indicates a novel way in which radio emission from magnetars can differ from that of ordinary pulsars. The torque on the neutron star is varying rapidly and unsteadily, as is common for magnetars following outburst, having changed by a factor of 7 within six months of reactivation.Comment: Published in ApJ (2018 April 5); 13 pages, 4 figure

    Chapter 1: Assessing a planet in transformation: Rationale and approach of the IPBES Global Assessment on Biodiversity and Ecosystem Services

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    The challenges of mitigating and adapting to climate change, achieving inclusive food, water, energy and health security, addressing urban vulnerabilities, and the unequal burdens of nature deterioration, are not only predicaments on their own right. Because they interact, often exacerbating each other, they create new risks and uncertainties for people and nature. It is now evident that the rapid deterioration of nature, including that of the global environmental commons on land, ocean, atmosphere and biosphere, upon which humanity as a whole depends, are interconnected and their cascading effects compromise societal goals and aspirations from local to global levels. Growing efforts to respond to these challenges and awareness of our dependence on nature have opened new opportunities for action and collaboration towards fairer and more sustainable futures.The global assessment on biodiversity and ecosystem services (GA) has been designed to be a comprehensive and ambitious intergovernmental integrated assessment of recent anthropogenic transformations of Earth?s living systems, the roots of such transformations, and their implications to society. In the chapters that follow, our mandate is to critically assess the state of knowledge on recent past (from the 1970s), present and possible future trends in multi-scale interactions between people and nature, taking into consideration different worldviews and knowledge systems, including those representing mainstream natural and social sciences and the humanities, and indigenous and local knowledge systems. In doing so, the GA also assesses where the world stands in relation to several international agreements related to biodiversity and sustainable development.Fil: Brondizio, Eduardo. No especifĂ­ca;Fil: DĂ­az, Sandra Myrna. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - CĂłrdoba. Instituto Multidisciplinario de BiologĂ­a Vegetal. Universidad Nacional de CĂłrdoba. Facultad de Ciencias Exactas FĂ­sicas y Naturales. Instituto Multidisciplinario de BiologĂ­a Vegetal; ArgentinaFil: Settele, Josef. No especifĂ­ca;Fil: Ngo, Hien. No especifĂ­ca;Fil: GuĂšze, Maximilien. No especifĂ­ca;Fil: Aumeeruddy-Thomas, Y. No especifĂ­ca;Fil: Bai, Xuemei. No especifĂ­ca;Fil: Geschke, Arne. No especifĂ­ca;Fil: MolnĂĄr, Zsolt. No especifĂ­ca;Fil: Niamir, Aidin. No especifĂ­ca;Fil: Pascual, Unai. No especifĂ­ca;Fil: Simcock, Alan. No especifĂ­ca;Fil: Jaureguiberry, Pedro. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro CientĂ­fico TecnolĂłgico Conicet - CĂłrdoba. Instituto Multidisciplinario de BiologĂ­a Vegetal. Universidad Nacional de CĂłrdoba. Facultad de Ciencias Exactas FĂ­sicas y Naturales. Instituto Multidisciplinario de BiologĂ­a Vegetal; ArgentinaFil: Hien, Ngo,. No especifĂ­ca;Fil: Brancalion, Pedro. No especifĂ­ca;Fil: Chan, Kai M. A.. No especifĂ­ca;Fil: Dubertret, Fabrice. No especifĂ­ca;Fil: Hendry, Andrew. No especifĂ­ca;Fil: Liu, Jianguo. No especifĂ­ca;Fil: Martin, Adrian. No especifĂ­ca;Fil: MartĂ­n LĂłpez, Berta. No especifĂ­ca;Fil: Midgley, Guy F.. No especifĂ­ca;Fil: Obura, David. No especifĂ­ca;Fil: Oliver, Tom. No especifĂ­ca;Fil: Scheffran, JĂŒrgen. No especifĂ­ca;Fil: Seppelt, Ralf. No especifĂ­ca;Fil: Strassburg, Bernardo. No especifĂ­ca;Fil: Spangenberg, Joachim H.. No especifĂ­ca;Fil: Stenseke, Marie. No especifĂ­ca;Fil: Turnhout, Esther. No especifĂ­ca;Fil: Williams, Meryl J.. No especifĂ­ca;Fil: Zayas, Cynthia. No especifĂ­ca

    Rethinking Land in the Anthropocene: from Separation to Integration

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    Nur wenn sich unser Umgang mit Land grundlegend Ă€ndert, können die Klimaschutzziele erreicht, der dramatische Verlust der biologischen Vielfalt abgewendet und das globale ErnĂ€hrungssystem nachhaltig gestaltet werden. Der WBGU schlĂ€gt fĂŒnf exemplarische Mehrgewinnstrategien vor, um Konkurrenzen zwischen NutzungsansprĂŒchen zu ĂŒberwinden. Diese sollten durch fĂŒnf Governance-Strategien vorangetrieben werden, darunter insbesondere die Setzung geeigneter Rahmenbedingungen, eine Neuorientierung der EUPolitik und die Errichtung von Gemeinschaften gleichgesinnter Staaten.Only if there is a fundamental change in the way we manage land can we reach the targets of climate-change mitigation, avert the dramatic loss of biodiversity and make the global food system sustainable. The WBGU proposes five multiple-benefit strategies illustrating ways of overcoming competition between rival claims to the use of land. These should be promoted by five governance strategies, especially by setting suitable framework conditions, reorienting EU policy and establishing alliances of like-minded states
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