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  • Journal article
    Ham DA, Farrell PE, Gorman GJ, Maddison JR, Wilson CR, Kramer SC, Shipton J, Collins GS, Cotter CJ, Piggott MDet al., 2009,

    Spud 1.0: generalising and automating the user interfaces of scientific computer models

    , GEOSCIENTIFIC MODEL DEVELOPMENT, Vol: 2, Pages: 33-42, ISSN: 1991-959X
  • Conference paper
    Barron LL, Wiliams W, Muxworthy AR, 2009,

    Effect of Nanoscale Intergrowths on Palaeomagnetic Interpretations (poster)

    , Magnetic Exchanges
  • Conference paper
    Muxworthy AR, Heslop D, Paterson GA, Emmerton Set al., 2009,

    Deriving absolute palaeointensities from FORC diagrams

    , Magnetic Exchanges
  • Conference paper
    Paterson GA, Muxworthy AR, Roberts AP, Mac Niocaill Cet al., 2009,

    Investigating the use of Pyroclastics for Palaeointensity Determinations (poster)

    , Magnetic Exchanges
  • Book chapter
    Martins Z, Sephton MA, 2009,

    Extraterrestrial amino acids

    , Origins and Synthesis of Amino Acids., Editors: Hughes, Hughes, Weinheim, Publisher: Wiley-VCH, Pages: 3-42, ISBN: 9789783527324
  • Journal article
    Perry RS, Sephton MA, 2009,

    Reply to comments on defining biominerals and organominerals: Direct and indirect indicators of life [Perry et al., Sedimentary Geology, 201, 157-179]

    , SED GEOL, Vol: 213, Pages: 156-156, ISSN: 0037-0738
  • Journal article
    Peeters Z, Quinn R, Martins Z, Sephton MA, Becker L, van Loosdrecht MCM, Brucato J, Grunthaner F, Ehrenfreund Pet al., 2009,

    Habitability on planetary surfaces: interdisciplinary preparation phase for future Mars missions

    , INT J ASTROBIOL, Vol: 8, Pages: 301-315, ISSN: 1473-5504

    Life on Earth is one of the outcomes of the formation and evolution of our solar system and has adapted to every explored environment on planet Earth. Recent discoveries have shown that life can exist in extreme environments, such as hydrothermal vents, in deserts and in ice lakes in Antarctica. These findings challenge the definition of the ‘planetary habitable zone’. The objective of future international planetary exploration programmes is to implement a long-term plan for the robotic and human exploration of solar system bodies. Mars has been a central object of interest in the context of extraterrestrial life. The search for extinct or extant life on Mars is one of the main goals of space missions to the Red Planet during the next decade. In this paper we describe the investigation of the physical and chemical properties of Mars soil analogues collected in arid deserts. We measure the pH, redox potential and ion concentrations, as well as carbon and amino acid abundances of soils collected from the Atacama desert (Chile and Peru) and the Salten Skov sediment from Denmark. The samples show large differences in their measured properties, even when taken only several meters apart. A desert sample and the Salten Skov sediment were exposed to a simulated Mars environment to test the stability of amino acids in the soils. The presented laboratory and field studies provide limits to exobiological models, evidence on the effects of subsurface mineral matrices, support current and planned space missions and address planetary protection issues.
  • Journal article
    Court RW, Sephton MA, 2009,

    Investigating the contribution of methane produced by ablating micrometeorites to the atmosphere of Mars

    , EARTH PLAN SCI LETT, Vol: 288, Pages: 382-385, ISSN: 0012-821X

    The presence of methane in the atmosphere of Mars has been suggested as evidence of life, as methane has a short lifetime in the atmosphere of Mars of just a few hundred years, requiring replacement by mechanisms, continuous or episodic, such as biology, volcanism, serpentinization of ultramafic crust or large cometary or asteroidal impacts. The potential of meteoritic infall to deliver significant quantities of methane is restricted by the low abundance of free methane in carbonaceous meteorites. However, the delivery of meteoritic material to the surface of a planet is an energetic process, and the ability of carbonaceous meteorites to generate methane upon ablation during atmospheric entry has not been previously considered. Here, we use analytical pyrolysis to simulate the ablation and pyrolysis of carbonaceous micrometeorites upon atmospheric entry, and Fourier-transform infrared spectroscopy to quantify the subsequent yield of methane. We show that ablation produces a yield of methane that is approximately two orders of magnitude greater than the measured free methane present in the CM2 carbonaceous chondrite, Murchison, but that this previously overlooked source of methane can only account for less than 10 kg of methane annually, a mass far below that required to maintain the abundance of methane observed in the atmosphere of Mars. Our data support attempts to search for life and explore subsurface chemical processes on the Red Planet.
  • Journal article
    Court RW, Sephton MA, 2009,

    Meteorite ablation products and their contribution to the atmospheres of terrestrial planets: An experimental study using pyrolysis-FTIR

    , GEOCHIM COSMOCHIM AC, Vol: 73, Pages: 3512-3521, ISSN: 0016-7037
  • Journal article
    Court RW, Sephton MA, 2009,

    Quantitative flash pyrolysis Fourier transform infrared spectroscopy of organic materials

    , Analytica Chimica Acta, Vol: 639, Pages: 62-66, ISSN: 0003-2670

    Thermal degradation is a common technique used to investigate the nature of organic materials. However, existing methods for the Fourier transform infrared (FTIR) identification and quantification of volatile products from the thermal degradation of organic materials are limited to the technique of thermogravimetric analysis (TGA)–FTIR, which utilizes relatively low heating rates. However, the thermal degradation products of organic materials are known to vary depending on the rate of heating, with lower heating rates of biomass associated with increased yields of solid char and decreased yields of volatiles, as well as a greater opportunity for secondary reactions between the residue and the pyrolysis products. Hence, it is difficult to relate the products of organic matter thermally degraded at <100 °C min−1 in TGA to the products of flash pyrolysis at up to 20,000 °C s−1. We have developed and applied a novel methodology for quantitative flash pyrolysis–FTIR analysis of the volatile pyrolysis products of organic-rich materials. Calibration curves of water, carbon dioxide and methane have been constructed and used to determine absolute volatile release from wood (ash, Lat. Fraxinus). This technique is quicker and simpler than comparable pyrolysis–gas chromatography–mass spectrometry techniques, and avoids errors associated with the lower rates of temperature increase associated with techniques such as thermogravimetric analysis.
  • Journal article
    Gomes RL, Meredith W, Snape CE, Sephton MAet al., 2009,

    Analysis of conjugated steroid androgens: Deconjugation, derivatisation and associated issues

    , Journal of Pharmaceutical and Biomedical Analysis, Vol: 49, Pages: 1133-1140, ISSN: 0731-7085

    Gas chromatography/mass spectrometry (GC/MS) is the preferred technique for the detection of urinary steroid androgens for drug testing in athletics. Excreted in either the glucuronide or sulfated conjugated form, steroids must first undergo deconjugation followed by derivatisation to render them suitable for GC analysis. Discussed herein are the deconjugation and the derivatisation preparative options. The analytical challenges surrounding these preparatory approaches, in particular the inability to cleave the sulfate moiety have led to a focus on testing protocols that reply on glucuronide conjugates. Other approaches which alleviate the need for deconjugation and derivatisation are also highlighted.
  • Journal article
    Sephton MA, Visscher H, Looy CV, Verchovsky AB, Watson JSet al., 2009,

    Chemical constitution of a Permian-Triassic disaster species

    , GEOLOGY, Vol: 37, Pages: 875-878, ISSN: 0091-7613

    One of the most controversial biological proxies of environmental crisis at the close of the Permian is the organic microfossil Reduviasporonites. The proliferation of this disaster species coincides with the mass extinction and numerous geochemical disturbances. Originally Reduviasporonites was assigned to fungi, opportunistically exploiting dying end-Permian forests, but subsequentgeochemical data have been used to suggest an algal origin. We have used high-sensitivity equipment, partly designed to detect interstellar grains in meteorites, to reexamine the geochemical signature of Reduviasporonites. Organic chemistry, carbon and nitrogen isotopes, and carbon/nitrogen ratios are consistent with a fungal origin. The use of this microfossil as a marker of terrestrial ecosystem collapse should not be merely discounted. Unequivocally diagnostic data, however, may have been precluded by post-burial replacement of its organic constituents.
  • Journal article
    Christeson GL, Collins GS, Morgan JV, Gulick SPS, Barton PJ, Warner MRet al., 2009,

    Mantle deformation beneath the Chicxulub impact crater

    , Earth and Planetary Science Letters, Vol: 284, Pages: 249-257, ISSN: 0012-821X
  • Journal article
    Muxworthy AR, Heslop D, Michalk DM, 2009,

    Thermal fluctuation fields in basalts

    , Earth, Planets and Space, Vol: 61, Pages: 111-117
  • Journal article
    Gomes RL, Meredith W, Snape CE, Sephton MAet al., 2009,

    Conjugated steroids: analytical approaches and applications

    , ANAL BIOANAL CHEM, Vol: 393, Pages: 453-458, ISSN: 1618-2642

    An introduction to conjugated steroids and the justification for their analysis is provided covering both environmental and biological samples. Determining conjugated steroids or indeed any organic chemical which is conjugated upon excretion from the body has relevance in diagnostic monitoring, forensic screening and environmental analysis (from the endocrine disrupter perspective). The various analytical approaches and the accompanying issues are application-dependent. There are numerous options at each stage of analysis, from extraction, hydrolysis, derivatisation, and detection, and advances can be confined to the specific application for which it was developed. Emphasis is placed on the choice of separation and how gas or liquid chromatography necessitates different preparative stages to enable conjugated steroid determination. Possible future directions and research for conjugated steroid analysis are discussed.
  • Journal article
    Hendry KR, Rickaby REM, de Hoog JCM, Weston K, Rehkamper Met al., 2008,

    Cadmium and phosphate in coastal Antarctic seawater: Implications for Southern Ocean nutrient cycling

    , MARINE CHEMISTRY, Vol: 112, Pages: 149-157, ISSN: 0304-4203
  • Journal article
    Bray VJ, Collins GS, Morgan JV, Schenk PMet al., 2008,

    The effect of target properties on crater morphology: Comparison of central peak craters on the Moon and Ganymede.

    , Meteoritics and Planetary Science, Vol: 43, Pages: 1979-1992
  • Journal article
    Collins GS, Kenkmann T, Osinski GR, Wunnemann Ket al., 2008,

    Mid-sized complex crater formation in mixed crystalline-sedimentary targets: Insight from modeling and observation

    , METEORITICS & PLANETARY SCIENCE, Vol: 43, Pages: 1955-1977, ISSN: 1086-9379
  • Conference paper
    Muxworthy AR, Heslop D, Paterson GA, Emmerton Set al., 2008,

    Toward a new non-heating method of determining absolute paleointensities

    , AGU Fall
  • Conference paper
    Barron LL, Williams W, Muxworthy AR, harrison RJet al., 2008,

    The Effect of Nanoscale Intergrowths on Palaeomagnetic Interpretations (poster)

    , AGU Fall

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