| 1. |
- Martin, P., et al.
(författare)
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Overview of the RFX-mod fusion science programme
- 2013
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 53:10, s. 104018-
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Forskningsöversikt (refereegranskat)abstract
- This paper reports the highlights of the RFX-mod fusion science programme since the last 2010 IAEA Fusion Energy Conference. The RFX-mod fusion science programme focused on two main goals: exploring the fusion potential of the reversed field pinch (RFP) magnetic configuration and contributing to the solution of key science and technology problems in the roadmap to ITER. Active control of several plasma parameters has been a key tool in this endeavour. New upgrades on the system for active control of magnetohydrodynamic (MHD) stability are underway and will be presented in this paper. Unique among the existing fusion devices, RFX-mod has been operated both as an RFP and as a tokamak. The latter operation has allowed the exploration of edge safety factor q edge < 2 with active control of MHD stability and studies concerning basic energy and flow transport mechanisms. Strong interaction has continued with the stellarator community in particular on the physics of helical states and on three-dimensional codes.
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| 2. |
- Martin, P., et al.
(författare)
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Overview of the RFX fusion science program
- 2011
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 51:9, s. 094023-
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Tidskriftsartikel (refereegranskat)abstract
- This paper summarizes the main achievements of the RFX fusion science program in the period between the 2008 and 2010 IAEA Fusion Energy Conferences. RFX-mod is the largest reversed field pinch in the world, equipped with a system of 192 coils for active control of MHD stability. The discovery and understanding of helical states with electron internal transport barriers and core electron temperature >1.5 keV significantly advances the perspectives of the configuration. Optimized experiments with plasma current up to 1.8 MA have been realized, confirming positive scaling. The first evidence of edge transport barriers is presented. Progress has been made also in the control of first-wall properties and of density profiles, with initial first-wall lithization experiments. Micro-turbulence mechanisms such as ion temperature gradient and micro-tearing are discussed in the framework of understanding gradient-driven transport in low magnetic chaos helical regimes. Both tearing mode and resistive wall mode active control have been optimized and experimental data have been used to benchmark numerical codes. The RFX programme also provides important results for the fusion community and in particular for tokamaks and stellarators on feedback control of MHD stability and on three-dimensional physics. On the latter topic, the result of the application of stellarator codes to describe three-dimensional reversed field pinch physics will be presented.
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| 3. |
- Terranova, D., et al.
(författare)
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A 3D approach to equilibrium, stability and transport studies in RFX-mod improved regimes
- 2010
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 0741-3335 .- 1361-6587. ; 52:12, s. 124023-
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Tidskriftsartikel (refereegranskat)abstract
- The full three-dimensional (3D) approach is now becoming an important issue for all magnetic confinement configurations. It is a necessary condition for the stellarator but also the tokamak and the reversed field pinch (RFP) now cannot be completely described in an axisymmetric framework. For the RFP the observation of self-sustained helical configurations with improved plasma performances require a better description in order to assess a new view on this configuration. In this new framework plasma configuration studies for RFX-mod have been considered both with tools developed for the RFP as well as considering codes originally developed for the stellarator and adapted to the RFP. These helical states are reached through a transition to a very low/reversed shear configuration leading to internal electron transport barriers. These states are interrupted by MHD reconnection events and the large Te gradients at the barriers indicate that both current and pressure driven modes are to be considered. Furthermore the typically flat Te profiles in the helical core have raised the issue of the role of electrostatic and electromagnetic turbulence in these reduced chaos regions, so that a stability analysis in the correct 3D geometry is required to address an optimization of the plasma setup. In this viewtheVMECcode proved to be an effectiveway to obtain helical equilibria to be studied in terms of stability and transport with a suite of well tested codes. In this work, the equilibrium reconstruction technique as well as the experimental evidence of 3D effects and their first interpretation in terms of stability and transport are presented using both RFP and stellarator tools.
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| 4. |
- Puiatti, M. E., et al.
(författare)
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Internal and external electron transport barriers in the RFX-mod reversed field pinch
- 2011
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 51:7, s. 073038-
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Tidskriftsartikel (refereegranskat)abstract
- An interesting result of magnetic chaos reduction in RFX-mod high current discharges is the development of strong electron transport barriers. An internal heat and particle transport barrier is formed when a bifurcation process changes the magnetic configuration into a helical equilibrium and chaos reduction follows, together with the formation of a null in the q shear. Strong temperature gradients develop, corresponding to a decreased thermal and particle transport. Turbulence analysis shows that the large electron temperature gradients are limited by the onset of micro-tearing modes, in addition to residual magnetic chaos. A new type of electron transport barrier with strong temperature gradients develops more externally (r/a = 0.8) accompanied by a 30% improvement of the global confinement time. The mechanism responsible for the formation of such a barrier is still unknown but it is likely associated with a local reduction of magnetic chaos. These external barriers develop primarily in situations of well-conditioned walls so that they might be regarded as attempts towards an L-H transition. Both types of barriers occur in high-current low-collisionality regimes. Analogies with tokamak and stellarators are discussed.
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| 5. |
- Leclercq, R, et al.
(författare)
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EUCAST expert rules in antimicrobial susceptibility testing
- 2013
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Ingår i: Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases. - : Elsevier BV. - 1469-0691. ; 19:2, s. 141-160
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Tidskriftsartikel (refereegranskat)
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| 6. |
- Uhlig, Jens, et al.
(författare)
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Table-Top Ultrafast X-Ray Microcalorimeter Spectrometry for Molecular Structure
- 2013
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Ingår i: Physical Review Letters. - 1079-7114. ; 110:13
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Tidskriftsartikel (refereegranskat)abstract
- This work presents an x-ray absorption measurement by use of ionizing radiation generated by a femtosecond pulsed laser source. The spectrometer was a microcalorimetric array whose pixels are capable of accurately measuring energies of individual radiation quanta. An isotropic continuum x-ray spectrum in the few-keV range was generated from a laser plasma source with a water-jet target. X rays were transmitted through a ferrocene powder sample to the detector, whose pixels have average photon energy resolution Delta E = 3.14 eV full-width-at-half-maximum at 5.9 keV. The bond distance of ferrocene was retrieved from this first hard-x-ray absorption fine-structure spectrum collected with an energy-dispersive detector. This technique will be broadly enabling for time-resolved observations of structural dynamics in photoactive systems. DOI: 10.1103/PhysRevLett.110.138302
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| 7. |
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| 8. |
- Fernández-Pozo, Noé, et al.
(författare)
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EuroPineDB : a high-coverage web database for maritime pine transcriptome
- 2011
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Ingår i: BMC Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 12, s. 366-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Pinus pinaster is an economically and ecologically important species that is becoming a woody gymnosperm model. Its enormous genome size makes whole-genome sequencing approaches are hard to apply. Therefore, the expressed portion of the genome has to be characterised and the results and annotations have to be stored in dedicated databases. DESCRIPTION: EuroPineDB is the largest sequence collection available for a single pine species, Pinus pinaster (maritime pine), since it comprises 951 641 raw sequence reads obtained from non-normalised cDNA libraries and high-throughput sequencing from adult (xylem, phloem, roots, stem, needles, cones, strobili) and embryonic (germinated embryos, buds, callus) maritime pine tissues. Using open-source tools, sequences were optimally pre-processed, assembled, and extensively annotated (GO, EC and KEGG terms, descriptions, SNPs, SSRs, ORFs and InterPro codes). As a result, a 10.5× P. pinaster genome was covered and assembled in 55 322 UniGenes. A total of 32 919 (59.5%) of P. pinaster UniGenes were annotated with at least one description, revealing at least 18 466 different genes. The complete database, which is designed to be scalable, maintainable, and expandable, is freely available at: http://www.scbi.uma.es/pindb/. It can be retrieved by gene libraries, pine species, annotations, UniGenes and microarrays (i.e., the sequences are distributed in two-colour microarrays; this is the only conifer database that provides this information) and will be periodically updated. Small assemblies can be viewed using a dedicated visualisation tool that connects them with SNPs. Any sequence or annotation set shown on-screen can be downloaded. Retrieval mechanisms for sequences and gene annotations are provided. CONCLUSIONS: The EuroPineDB with its integrated information can be used to reveal new knowledge, offers an easy-to-use collection of information to directly support experimental work (including microarray hybridisation), and provides deeper knowledge on the maritime pine transcriptome.
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| 9. |
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| 10. |
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| 11. |
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| 12. |
- Ruiz-Camacho, B., et al.
(författare)
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Electrochemical and XAS investigation of oxygen reduction reaction on Pt-TiO2-C catalysts
- 2013
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Ingår i: International Journal of Hydrogen Energy. - : Elsevier BV. - 1879-3487 .- 0360-3199. ; 38:28, s. 12648-12656
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Tidskriftsartikel (refereegranskat)abstract
- Pt-TiO2-C composites with different titanium oxide loading were synthesized by photo-deposition and chemical vapor deposition methods. The changes in their electronic properties improve the electrochemical activity toward the oxygen reduction reaction (ORR) compared to the Pt-C catalyst synthesized at the same conditions. The platinum samples were physically characterized by means of Transmission Electron Microscopy (TEM), Small Angle X-ray Scattering (SAXS), X-ray Absorption Spectroscopy (XAS) and X-ray Photo-electron Spectroscopy (XPS). Their electrochemical activity was also investigated by cyclic and linear voltammetry techniques. TEM analysis shows homogeneously dispersed platinum nanoparticles with an average particle size of 2 nm in all the synthesized samples. Form factor (morphology model) and particle size were determined by SAXS, the data adjusted to spherical Pt nanoparticles in both synthesis methods. XAS studies at the Pt L-3-edge shows a close interaction of Pt with the support material, i.e. C or TiO2. XPS analysis reveals surface modifications that induce electronic changes on Pt-TiO2-C. Significant differences in the ORR electrochemical activity were correlated to the TiO2 loading and the synthesis procedure. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
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| 13. |
- Suarez Alcantara, Karina, et al.
(författare)
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Synchrotron-based structural and spectroscopic studies of ball milled RuSeMo and RuSnMo particles as oxygen reduction electrocatalyst for PEM fuel cells
- 2014
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Ingår i: International Journal of Hydrogen Energy. - : Elsevier BV. - 1879-3487 .- 0360-3199. ; 39:29, s. 16715-16721
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Tidskriftsartikel (refereegranskat)abstract
- Particles of RuSeMo and RuSnMo have been produced by ball milling; they present catalytic activity towards the oxygen reduction reaction (ORR) in acid media. A Tafel slope close to 120 mV/dec was found for both materials. Their morphology was first characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM and TEM images reveal particles in the sub-micrometer range. The structure of the materials was further probed with synchrotron radiation powder X-ray diffraction (SR-PXD) and X-ray absorption spectroscopy (XAS). SR-PXD reveals the existence of metallic Ru as the main phase and the formation of phases such as RuSe2 in RuSeMo and Ru3Sn7 in RuSnMo. Mo was found to form solid solution into the RuSe2 phase in ball milled RuSeMo. Finally, The Ru L-3-edge and Mo L-3-edge XAS fingerprints were correlated with the catalytic activity towards ORR. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
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| 14. |
- Villalobos, David P., et al.
(författare)
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Reprogramming of gene expression during compression wood formation in pine : Coordinated modulation of S-adenosylmethionine, lignin and lignan related genes
- 2012
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Ingår i: BMC Plant Biology. - : Springer Science and Business Media LLC. - 1471-2229. ; 12, s. 100-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Transcript profiling of differentiating secondary xylem has allowed us to draw a general picture of the genes involved in wood formation. However, our knowledge is still limited about the regulatory mechanisms that coordinate and modulate the different pathways providing substrates during xylogenesis. The development of compression wood in conifers constitutes an exceptional model for these studies. Although differential expression of a few genes in differentiating compression wood compared to normal or opposite wood has been reported, the broad range of features that distinguish this reaction wood suggest that the expression of a larger set of genes would be modified. Results: By combining the construction of different cDNA libraries with microarray analyses we have identified a total of 496 genes in maritime pine (Pinus pinaster, Ait.) that change in expression during differentiation of compression wood (331 up-regulated and 165 down-regulated compared to opposite wood). Samples from different provenances collected in different years and geographic locations were integrated into the analyses to mitigate the effects of multiple sources of variability. This strategy allowed us to define a group of genes that are consistently associated with compression wood formation. Correlating with the deposition of a thicker secondary cell wall that characterizes compression wood development, the expression of a number of genes involved in synthesis of cellulose, hemicellulose, lignin and lignans was up-regulated. Further analysis of a set of these genes involved in S-adenosylmethionine metabolism, ammonium recycling, and lignin and lignans biosynthesis showed changes in expression levels in parallel to the levels of lignin accumulation in cells undergoing xylogenesis in vivo and in vitro. Conclusions: The comparative transcriptomic analysis reported here have revealed a broad spectrum of coordinated transcriptional modulation of genes involved in biosynthesis of different cell wall polymers associated with within-tree variations in pine wood structure and composition. In particular, we demonstrate the coordinated modulation at transcriptional level of a gene set involved in S-adenosylmethionine synthesis and ammonium assimilation with increased demand for coniferyl alcohol for lignin and lignan synthesis, enabling a better understanding of the metabolic requirements in cells undergoing lignification.
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