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  • 1
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    Theoretical study of deuteronated PAHs as carriers for IR emission features in the ISM (2015)
    Oxford University Press
    Details
    Publication Date: 2015-09-21
    Description: This work proposes deuteronated PAH (DPAH + ) molecules as a potential carrier of the 4.4 and 4.65 μm mid-infrared emission bands that have been observationally detected towards the Orion and M17 regions. Density Functional Theory calculations have been carried out on DPAH + molecules to see the variations in the spectral behaviour from that of a pure polycyclic aromatic hydrocarbon (PAH). DPAH + molecules show features that arise due to the stretching of the aliphatic C–D bond. Deuterated PAHs have been previously reported as carriers for such features. However, preferred conditions of ionization of PAHs in the interstellar medium (ISM) indicates the possibility of the formation of DPAH + molecules. Comparison of band positions of DPAH + s shows reasonable agreement with the observations. We report the effect of size of the DPAH + molecules on band positions and intensities. This study also reports a D/H ratio ([D/H] $\rm _{sc}$ ; the ratio of C–D stretch and C–H stretch bands per [D/H] $\rm _{num}$ ) that is decreasing with the increasing size of DPAH + s. It is noted that large DPAH + molecules (no. of C atoms ~50) match the D/H ratio that has been estimated from observations. This ratio offers prospects to study the deuterium abundance and depletion in the ISM.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 2
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    Theoretical study of deuteronated PAHs as carriers for IR emission features in the ISM (2015)
    Oxford University Press
    Details
    Publication Date: 2015-09-23
    Description: This work proposes deuteronated PAH (DPAH + ) molecules as a potential carrier of the 4.4 and 4.65 μm mid-infrared emission bands that have been observationally detected towards the Orion and M17 regions. Density Functional Theory calculations have been carried out on DPAH + molecules to see the variations in the spectral behaviour from that of a pure polycyclic aromatic hydrocarbon (PAH). DPAH + molecules show features that arise due to the stretching of the aliphatic C–D bond. Deuterated PAHs have been previously reported as carriers for such features. However, preferred conditions of ionization of PAHs in the interstellar medium (ISM) indicates the possibility of the formation of DPAH + molecules. Comparison of band positions of DPAH + s shows reasonable agreement with the observations. We report the effect of size of the DPAH + molecules on band positions and intensities. This study also reports a D/H ratio ([D/H] $\rm _{sc}$ ; the ratio of C–D stretch and C–H stretch bands per [D/H] $\rm _{num}$ ) that is decreasing with the increasing size of DPAH + s. It is noted that large DPAH + molecules (no. of C atoms ~50) match the D/H ratio that has been estimated from observations. This ratio offers prospects to study the deuterium abundance and depletion in the ISM.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 3
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    HIF-driven SF3B1 induces KHK-C to enforce fructolysis and heart disease (2015)
    Nature Publishing Group (NPG)
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    Publication Date: 2015-06-18
    Description: Fructose is a major component of dietary sugar and its overconsumption exacerbates key pathological features of metabolic syndrome. The central fructose-metabolising enzyme is ketohexokinase (KHK), which exists in two isoforms: KHK-A and KHK-C, generated through mutually exclusive alternative splicing of KHK pre-mRNAs. KHK-C displays superior affinity for fructose compared with KHK-A and is produced primarily in the liver, thus restricting fructose metabolism almost exclusively to this organ. Here we show that myocardial hypoxia actuates fructose metabolism in human and mouse models of pathological cardiac hypertrophy through hypoxia-inducible factor 1alpha (HIF1alpha) activation of SF3B1 and SF3B1-mediated splice switching of KHK-A to KHK-C. Heart-specific depletion of SF3B1 or genetic ablation of Khk, but not Khk-A alone, in mice, suppresses pathological stress-induced fructose metabolism, growth and contractile dysfunction, thus defining signalling components and molecular underpinnings of a fructose metabolism regulatory system crucial for pathological growth.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mirtschink, Peter -- Krishnan, Jaya -- Grimm, Fiona -- Sarre, Alexandre -- Horl, Manuel -- Kayikci, Melis -- Fankhauser, Niklaus -- Christinat, Yann -- Cortijo, Cedric -- Feehan, Owen -- Vukolic, Ana -- Sossalla, Samuel -- Stehr, Sebastian N -- Ule, Jernej -- Zamboni, Nicola -- Pedrazzini, Thierry -- Krek, Wilhelm -- England -- Nature. 2015 Jun 25;522(7557):444-9. doi: 10.1038/nature14508. Epub 2015 Jun 17.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Institute of Molecular Health Sciences, ETH Zurich, 8093 Zurich, Switzerland. ; Department of Medicine, University of Lausanne, 1011 Lausanne, Switzerland. ; Institute of Molecular Systems Biology, ETH Zurich, 8093 Zurich, Switzerland. ; MRC-Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK. ; Universitatsmedizin Gottingen, Klinik fur Kardiologie und Pneumologie, D-37075 Gottingen, and DZHK (German Centre for Cardiovascular Research), Partner Site Gottingen, Germany. ; Department of Anesthesiology and Critical Care Medicine, University Hospital Jena, 07747 Jena, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26083752" target="_blank"〉PubMed〈/a〉
    Keywords: Alternative Splicing ; Animals ; Cardiomyopathy, Hypertrophic/genetics/*metabolism/pathology/physiopathology ; Disease Models, Animal ; Fructokinases/deficiency/genetics/*metabolism ; Fructose/*metabolism ; Humans ; Hypoxia-Inducible Factor 1, alpha Subunit/genetics/*metabolism ; Isoenzymes/deficiency/genetics/metabolism ; Male ; Metabolic Syndrome X/metabolism ; Mice ; Phosphoproteins/deficiency/genetics/*metabolism ; Ribonucleoprotein, U2 Small Nuclear/deficiency/genetics/*metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 4
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    The 11.2 {mu}m emission of PAHs in astrophysical objects (2015)
    Oxford University Press
    Details
    Publication Date: 2015-03-10
    Description: The 11.2-μm emission band belongs to the family of the ‘unidentified’ infrared emission bands seen in many astronomical environments. In this work, we present a theoretical interpretation of the band characteristics and profile variation for a number of astrophysical sources in which the carriers are subject to a range of physical conditions. The results of Density Functional Theory calculations for the solo out-of-plane vibrational bending modes of large polycyclic aromatic hydrocarbon (PAH) molecules are used as input for a detailed emission model which includes the temperature and mass dependence of PAH band wavelength, and a PAH mass distribution that varies with object. Comparison of the model with astronomical spectra indicates that the 11.2-μm band asymmetry and profile variation can be explained principally in terms of the mass distribution of neutral PAHs with a small contribution from anharmonic effects.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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