2,826 research outputs found

    Phylogeny and evolution of flower symmetry of Posoqueria (Rubiaceae)

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    he genus Posoqueria is a phylogenetically poorly understood Neotropical group of roughly 20-25 species of shrubs and trees in the coffee family Rubiaceae, which presents several intemal taxonomic difficulties. Here, we used samples from 15 species and a high-throughput sequencing strategy to target-capture 353 nuclear loci, from which 177 genes were chosen to generate a phylogeny of Posoqueria using the multispecies coalescent (MSC) method. Our study confirms the monophyly of most Posoqueria taxa, providing evidence of phylogenomic distinctiveness of species such as P. mutisii, P. longiflora, P. maxima, P. grandiflora, and P. wiUiamsii, but questions the current circumscription of P. chocoana and P costaricensis. The phylogeny also supports the re-circumscription of P. latifolia, suggesting that populations from Central America and Colombia belong to an undescribed species in the genus. Moreover, our phylogenomic study indicates that flower symmetry and the unique catapult mechanism linked to zygomorphic flowers in Posoqueria is the product of several evolutionary transitions. On the other hand, some phylogenetic relationships in our study were only recovered with weak to moderate support, indicating further investigation is required that could include designing a customised bait panel that allows to resolve recent diversification events in Posoqueria

    Production and characterization of activated carbon from wood wastes

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    Cedarwood (Cedrela Angustifolia) and teak (Tectona Grandis) woods are typically used for furniture manufacture because they have high durability, are light and easy to work. During these manufacturing process, large amount of these wastes is generated causing disposal environmental problems. In this paper, the residual wastes (sawdust) of Cedar (C) and Teak (T) are transformed into an activated material. The chemical composition of both biomass (C and T) was determinate by TGA (Thermogravimetric Analysis). Activated materials were characterized in surface area following the BET (Brunauer, Emmett and Teller) method, morphology using SEM (Scanning Electron Microscopy) and to know their functional groups a FTIR (Fourier Transform Infrared Spectroscopy) analysis was done. Their adsorption capacity was evaluated by removal of Methylene Blue (MB) and Congo Red (CR) from aqueous solutions. © Published under licence by IOP Publishing Ltd

    Black Holes in the 3D Higher Spin Theory and Their Quasi Normal Modes

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    We present a class of 3D Black Holes based on flat connections which are polynomials in the BTZ hs(λ)×hs(λ)hs(\lambda) \times hs(\lambda)-valued connection. We solve analytically the fluctuation equations of matter in their background and find the spectrum of their Quasi Normal Modes. We analyze the bulk to boundary two-point functions. We also relate our results and those arising in other backgrounds discussed recently in the literature on the subject.Comment: v3: typo corrected in first line of Eq (4.2), improved presentatio

    Dyes removal from water using low cost absorbents

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    In this study, the removal capacity of low cost adsorbents during the adsorption of Methylene Blue (MB) and Congo Red (CR) at different concentrations (50 and 100mg•L-1) was evaluated. These adsorbents were produced from wood wastes (cedar and teak) by chemical activation (ZnCl2). Both studied materials, Activated Cedar (AC) and activated teak (AT) showed a good fit of their experimental data to the pseudo second order kinetic model and Langmuir isotherms. The maximum adsorption capacities for AC were 2000.0 and 444.4mg•g-1 for MB and CR, respectively, while for AT, maximum adsorption capacities of 1052.6 and 86.4mg•g-1 were found for MB and CR, respectively. © Published under licence by IOP Publishing Ltd

    Partition Function of N=2N=2 Gauge Theories on a Squashed S4S^4 with SU(2)×U(1)SU(2)\times U(1) Isometry

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    We study N=2N=2 supersymmetric gauge theories on a large family of squashed 4-spheres preserving SU(2)×U(1)SO(4)SU(2)\times U(1)\subset SO(4) isometry and determine the conditions under which this background is supersymmetric. We then compute the partition function of the theories by using localization technique. The results indicate that for N=2N=2 SUSY, including both vector-multiplets and hypermultiplets, the partition function is independent of the arbitrary squashing functions as well as of the other supergravity background fields.Comment: version to appear in Nuclear Physics

    Removal of H2S and CO2 from Biogas by Amine Absorption

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    The neutron time-of-flight facility n-TOF at CERN: Phase II

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    Neutron-induced reactions are studied at the neutron time-of-flight facility n-TOF at CERN. The facility uses 6∼ns wide pulses of 20 GeV/c protons impinging on a lead spallation target. The large neutron energy range and the high instantaneous neutron flux combined with high resolution are among the key characteristics of the facility. After a first phase of data taking during the period 2001-2004, the facility has been refurbished with an upgraded spallation target and cooling system for a second phase of data taking which started in 2009. Since 2010, the experimental area at 185 m where the neutron beam arrives, has been modified into a worksector of type A, allowing the extension of the physics program to include neutron-induced reactions on radioactive isotopes

    Silicon-based three-dimensional microstructures for radiation dosimetry in hadrontherapy

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    In this work, we propose a solid-state-detector for use in radiation microdosimetry. This device improves the performance of existing dosimeters using customized 3D-cylindrical microstructures etched inside silicon. The microdosimeter consists of an array of micro-sensors that have 3D-cylindrical electrodes of 15 μm diameter and a depth of 5 μm within a silicon membrane, resulting in a well-defined micrometric radiation sensitive volume. These microdetectors have been characterized using an 241Am source to assess their performance as radiation detectors in a high-LET environment. This letter demonstrates the capability of this microdetector to be used to measure dose and LET in hadrontherapy centers for treatment plan verification as part of their patient-specific quality control program
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