1,806 research outputs found

    Hydrogenic Transitions in Multiply Charged Fe and Ni Ions

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    Ten lines in the range 3880≊λ≊5666 Å in the beam-foil spectrum of iron have been identified with specific hydrogenic transitions in Fe iv-viii. The same transitions were observed from Ni and Ar beams. Deviations from the hydrogenic wavelengths are shown to be consistent with that expected from core polarization. The absence of these lines in astrophysical sources is discussed. A wavelength table is presented for identification of hydrogenic transitions to be expected in beam-foil spectra

    Visualising substrate-fingermark interactions: Solid-state NMR spectroscopy of amino acid reagent development on cellulose substrates

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    © 2015 Elsevier Ireland Ltd. Most spectroscopic studies of the reaction products formed by ninhydrin, 1,2-indanedione-zinc (Ind-Zn) and 1,8-diazafluoren-9-one (DFO) when reacted with amino acids or latent fingermarks on paper substrates are focused on visible absorption or luminescence spectroscopy. In addition, structural elucidation studies are typically limited to solution-based mass spectrometry or liquid nuclear magnetic resonance (NMR) spectroscopy, which does not provide an accurate representation of the fingermark development process on common paper substrates. The research presented in this article demonstrates that solid-state carbon-13 magic angle spinning NMR (13C-MAS-NMR) is a technique that can not only be utilised for structural studies of fingermark enhancement reagents, but is a promising technique for characterising the effect of paper chemistry on fingermark deposition and enhancement. The latter opens up a research area that has been under-explored to date but has the potential to improve our understanding of how fingermark secretions and enhancement reagents interact with paper substrates

    Risk of climate-induced damage in historical textiles

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    Eleven wool and silk historic textiles and two modern artist's canvases were examined to determine their water vapour adsorption, moisture dimensional response and tensile behaviour. All the textiles showed a similar general pattern of moisture response. A rise in ambient relative humidity (RH) from dry conditions produced expansion of a textile until a certain critical RH level after which a contraction occurred to a greater or lesser degree depending on the yarn crimp and the weave geometry. The largest expansion recorded between the dry state and 80% RH was 1.2 and 0.9% for wool and silk textiles, respectively. The largest shrinkage of 0.8% at high RH range was experienced by a modern linen canvas. Two potential damage mechanisms related to the moisture response of the textiles—stress building as a result of shrinkage of the textile restrained in its dimensional response and the fretting fatigue when yarns move with friction one against another—were found insignificant in typical textile display environments unless the textiles are severely degraded or excessively strained in their mounting

    Driven Morse Oscillator: Model for Multi-photon Dissociation of Nitrogen Oxide

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    Within a one-dimensional semi-classical model with a Morse potential the possibility of infrared multi-photon dissociation of vibrationally excited nitrogen oxide was studied. The dissociation thresholds of typical driving forces and couplings were found to be similar, which indicates that the results were robust to variations of the potential and of the definition of dissociation rate. PACS: 42.50.Hz, 33.80.WzComment: old paper, 8 pages 6 eps file

    Slowing Down of Positrons and Applications to Solid Surfaces

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    When monoenergetic positrons enter a solid they scatter and lose energy via processes similar to those for electrons. Theoretical details of these processes have been well established for decades, but experimental results using low energy positron beams are only now becoming available for comparison. We review the theoretical results for elastic and inelastic scattering of positrons and the predictions that follow for backscattering, inner-shell ionization, energy loss and stopping profiles. In this presentation, emphasis is given to specific comparisons with calculations for electrons. We discuss recent experimental results in each of these areas, and conclude with two examples of applications of positron beam techniques to near-surface research

    Heliospheric Magnetic Field Configuration at Solar Maximum Conditions: Consequences for Galactic Cosmic Rays

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    During solar maximum conditions, the heliosphere is highly structured on all spatial scales. It is the purpose of this paper to summarize our current understanding of these structures from global scales to mesoscale, a fraction of 1 AU. We use theoretical considerations, in situ observations near Earth and the Ulysses spacecraft, and global heliosphere calculations to discuss the effects on both global and mesoscales on the three‐dimensional structure of the heliospheric magnetic field and their effects on galactic cosmic rays. These conclusions are in contrast to near‐solar‐minimum‐like heliospheric conditions that are currently assumed in modulation and transport calculations even during solar maximum. The expected complex heliospheric properties should be of major importance for the interpretation of the heliospheric boundary events observed by Voyager 1 since 2002. A companion paper by L. A. Fisk will explore the effects of the mesoscale structures on particle acceleration in the heliospheric boundary region. © 2004 American Institute of PhysicsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87301/2/70_1.pd

    Applications of polymer optical fibre grating sensors to condition monitoring of textiles

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    Fibre Bragg gratings (FBGs) in polymer optical fibres (POFs) have been used to measure the strain in a woven textile. FBGs in both POFs and silica optical fibres were attached to a woven textile specimen, and their performance characterised. It was demonstrated that the POF FBGs provide improved strain transfer coefficients and reduce local structural reinforcement compared to silica FBGs and therefore make a more suitable proposition for textile monitoring

    An implementation plan for priorities in solar-system space physics

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    The scientific objectives and implementation plans and priorities of the Space Science Board in areas of solar physics, heliospheric physics, magnetospheric physics, upper atmosphere physics, solar-terrestrial coupling, and comparative planetary studies are discussed and recommended programs are summarized. Accomplishments of Skylab, Solar Maximum Mission, Nimbus-7, and 11 other programs are highlighted. Detailed mission plans in areas of solar and heliospheric physics, plasma physics, and upper atmospheric physics are also described
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