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  • Journal article
    Montgomery W, Lerch P, Sephton MA, 2014,

    In-situ vibrational optical rotatory dispersion of molecular organic crystals at high pressures

    , Analytica Chimica Acta, Vol: 842, Pages: 51-56, ISSN: 0003-2670
  • Journal article
    Court RW, Sims MR, Cullen DC, Sephton MAet al., 2014,

    Searching for Life on Mars: Degradation of Surfactant Solutions Used in Organic Extraction Experiments

    , Astrobiology, Vol: 14, Pages: 733-752, ISSN: 1531-1074
  • Conference paper
    Verchovsky AB, Hunt SA, Montgomery W, Sephton MAet al., 2014,

    REACTION OF Q TO THERMAL METAMORPHISM IN THE PARENT BODIES: HIGH-PRESSURE EXPERIMENTS

    , 77th Annual Meeting of the Meteoritical-Society, Publisher: WILEY-BLACKWELL, Pages: A421-A421, ISSN: 1086-9379
  • Journal article
    Luong D, Court RW, Sims MR, Cullen DC, Sephton MAet al., 2014,

    Extracting organic matter on Mars: A comparison of methods involving subcritical water, surfactant solutions and organic solvents

    , Planetary and Space Science, Vol: 99, Pages: 19-27, ISSN: 0032-0633
  • Journal article
    Sephton MA, 2014,

    Astrobiology can help space science, education and the economy

    , Space Policy, Vol: 30, Pages: 146-148, ISSN: 0265-9646
  • Journal article
    Sephton MA, Carter JN, 2014,

    Statistics Provide Guidance for Indigenous Organic Carbon Detection on Mars Missions

    , Astrobiology, Vol: 14, Pages: 706-713, ISSN: 1531-1074

    <jats:p>Data from the Viking and Mars Science Laboratory missions indicate the presence of organic compounds that are not definitively martian in origin. Both contamination and confounding mineralogies have been suggested as alternatives to indigenous organic carbon. Intuitive thought suggests that we are repeatedly obtaining data that confirms the same level of uncertainty. Bayesian statistics may suggest otherwise. If an organic detection method has a true positive to false positive ratio greater than one, then repeated organic matter detection progressively increases the probability of indigeneity. Bayesian statistics also reveal that methods with higher ratios of true positives to false positives give higher overall probabilities and that detection of organic matter in a sample with a higher prior probability of indigenous organic carbon produces greater confidence. Bayesian statistics, therefore, provide guidance for the planning and operation of organic carbon detection activities on Mars. Suggestions for future organic carbon detection missions and instruments are as follows: (i) On Earth, instruments should be tested with analog samples of known organic content to determine their true positive to false positive ratios. (ii) On the mission, for an instrument with a true positive to false positive ratio above one, it should be recognized that each positive detection of organic carbon will result in a progressive increase in the probability of indigenous organic carbon being present; repeated measurements, therefore, can overcome some of the deficiencies of a less-than-definitive test. (iii) For a fixed number of analyses, the highest true positive to false positive ratio method or instrument will provide the greatest probability that indigenous organic carbon is present. (iv) On Mars, analyses should concentrate on samples with highest prior probability of indigenous organic carbon; intuitive desires to contrast samples of high prior probability and low
  • Journal article
    Montgomery W, Watson JS, Sephton MA, 2014,

    An organic cosmo-barometer: Distinct pressure and temperature effects for methyl substituted polycyclic aromatic hydrocarbons

    , The Astrophysical Journal: an international review of astronomy and astronomical physics, Vol: 784, ISSN: 0004-637X

    There are a number of key structures that can be used to reveal the formation and modification history of organic matter in the cosmos. For instance, the susceptibility of organic matter to heat is well documented and the relative thermal stabilities of different isomers can be used as cosmothermometers. Yet despite being an important variable, no previously recognized organic marker of pressure exists. The absence of a pressure marker is unfortunate considering our ability to effectively recognize extraterrestrial organic structures both remotely and in the laboratory. There are a wide variety of pressures in cosmic settings that could potentially be reflected by organic structures. Therefore, to develop an organic cosmic pressure marker, we have used state-of-the-art diamond anvil cell (DAC) and synchrotron-source Fourier transform infrared (FTIR) spectroscopy to reveal the effects of pressure on the substitution patterns for representatives of the commonly encountered methyl substituted naphthalenes, specifically the dimethylnaphthalenes. Interestingly, although temperature and pressure effects are concordant for many isomers, pressure appears to have the opposite effect to heat on the final molecular architecture of the 1,5-dimethylnaphthalene isomer. Our data suggest the possibility of the first pressure parameter or "cosmo-barometer" (1,5-dimethylnaphthalene/total dimethylnaphthalenes) that can distinguish pressure from thermal effects. Information can be obtained from the new pressure marker either remotely by instrumentation on landers or rovers or directly by laboratory measurement, and its use has relevance for all cases where organic matter, temperature, and pressure interplay in the cosmos.
  • Journal article
    Fraser WT, Watson JS, Sephton MA, Lomax BH, Harrington G, Gosling WD, Self Set al., 2014,

    Changes in spore chemistry and appearance with increasing maturity

    , Review of Palaeobotany and Palynology, Vol: 201, Pages: 41-46, ISSN: 0034-6667
  • Conference paper
    Montgomery W, Sephton MA, Watson J, Zeng Het al., 2014,

    The Effects Of Minerals On Heavy Oil And Bitumen Chemistry When Recovered Using Steam-assisted Methods

    , SPE Heavy Oil Conference-Canada

    The production of gaseous sulfur-containing species during the steam-assisted recovery of heavy oil and bitumen have important consequences for both economics and safety. Factors such as the effects of mineral matrices require laboratory data to produce accurate models. To study mineral effects on gas production we studied a well-characterized oil-containing core and the isolated crude oil from that core. The samples were run at 250-300°C in the continued presence of liquid water for 24 hours. The reaction products of all experiments include gases, oil flotate, oil sinkate, water-soluble products, and water- insoluble residues. All reaction products were studied with a variety of analytical techniques, including FTIR spectroscopy, chromatographic fractionation (SARA analysis), GC-MS, pyrolysis GCMS and GC-FPD/TCD. These techniques were applied to whole oil, maltenes and asphaltene fractions. Physical properties including viscosity and density were also measured. Our data provide insights into the physical and chemical consequences of steam assisted recovery of heavy oils and bituments from sedimentary rock reservoirs and reveal that geological and geochemical context is an essential consideration.
  • Book chapter
    Sephton MA, 2014,

    Organic Geochemistry of Meteorites

    , Treatise on Geochemistry, Editors: Turekian, Publisher: Elsevier Science, Pages: 1-31
  • Journal article
    Fraser WT, Lomax BH, Jardine PE, Gosling WD, Sephton MAet al., 2014,

    Pollen and spores as a passive monitor of ultraviolet radiation

    , Frontiers in Ecology and Evolution, Vol: 2

    Sporopollenin is the primary component of the outer walls of pollen and spores. The chemical composition of sporopollenin is responsive to levels of ultraviolet (UV) radiation exposure, via a concomitant change in the concentration of phenolic compounds. This relationship offers the possibility of using fossil pollen and spore chemistry as a novel proxy for past UV flux. Phenolic compounds in sporopollenin can be quantified using Fourier Transform infrared spectroscopy. The high potential for preservation of pollen and spores in the geologic record, and the conservative nature of sporopollenin chemistry across the land plant phylogeny, means that this new proxy has the potential to reconstruct UV flux over much longer timescales than has previously been possible. This new tool has important implications for understanding the relationship between UV flux, solar insolation and climate in the past, as well as providing a possible means of assessing paleoaltitude, and ozone thickness.
  • Journal article
    Martins Z, Price MC, Goldman N, Sephton MA, Burchell MJet al., 2013,

    Shock synthesis of amino acids from impacting cometary and icy planet surface analogues

    , Nature Geoscience, Vol: 6, Pages: 1045-1049, ISSN: 1752-0894
  • Journal article
    Howard K, Bailey MJ, Berhanu D, Bland PA, Cressey G, Howard LE, Jeynes C, Matthewman R, Martins Z, Sephton MA, Stolojan V, Verchovsky Set al., 2013,

    Biomass preservation in impact melt ejecta

    , Nature Geoscience
  • Journal article
    Olsson-Francis K, Watson JS, Cockell CS, 2013,

    Cyanobacteria isolated from the high-intertidal zone: a model for studying the physiological prerequisites for survival in low Earth orbit

    , International Journal of Astrobiology, Vol: 12, Pages: 292-303, ISSN: 1473-5504

    <jats:title>Abstract</jats:title><jats:p>Cyanobacteria are capable of surviving the adverse conditions of low Earth orbit (LEO). We have previously demonstrated that<jats:italic>Gloeocapsa</jats:italic>strain OU_20,<jats:italic>Chroococcidiopsis</jats:italic>and akinetes of<jats:italic>Anabaena cylindrica</jats:italic>were able to survive 548 days of exposure to LEO. Motivated by an interest to understand how cyanobacteria can survive in LEO, we studied the strategies that<jats:italic>Gloeocapsa</jats:italic>strain OU_20 employs to survive in its natural environment, the upper region of the intertidal zone. Here, cyanobacteria are exposed to fluctuations in temperature, UV radiation, desiccation and salinity. We demonstrated that an increase in salinity from 6.5‰ (BG-11 medium) to 35.7‰ (similar to that of seawater), resulted in increased resistance to UV radiation (254 nm), vacuum (0.7×10<jats:sup>−3</jats:sup>±0.01 kPa) and cold temperatures (–20 °C). Concomitantly, biochemical analyses demonstrated that the amount of fatty acids and mycosporine-like amino acids (a UV absorbing pigment) were higher in the stressed cells. Morphological analysis demonstrated that the electron density and thickness of the mucilaginous sheath were also greater than in the control cells. Yet, the control and stressed cells both formed aggregates. As a result of studying the physiological adaptation of<jats:italic>Gloeocapsa</jats:italic>strain OU_20 in response to salinity, we postulate that survival in the high-intertidal zone and LEO involves a dense extracellular mucilaginous sheath and the formation of aggregates. We conclude that studying the physiological adaptation of cyanobacteria in the intertidal zone provides insight into understanding survival in LEO.</jats:p>
  • Journal article
    Emmerton S, Muxworthy AR, Sephton MA, 2013,

    A magnetic solution to the Mupe Bay mystery

    , Marine and Petroleum Geology, Vol: 46, Pages: 165-172, ISSN: 0264-8172
  • Conference paper
    Martins Z, Modica P, Sephton MA, Zanda B, d'Hendecourt Let al., 2013,

    THE SOLUBLE ORGANIC CONTENT OF THE PARIS METEORITE THE MOST PRIMITIVE CM CHONDRITE

    , 76th Annual Meeting of the Meteoritical-Society, Publisher: WILEY, Pages: A236-A236, ISSN: 1086-9379
  • Journal article
    Emmerton S, Muxworthy AR, Sephton MA, Aldana M, Costanzo-Alvarez V, Bayona G, Williams Wet al., 2013,

    Correlating biodegradation to magnetization in oil bearing sedimentary rocks

    , Geochimica et Cosmochimica Acta, Vol: 112, Pages: 146-165, ISSN: 0016-7037
  • Journal article
    Carter JN, Sephton MA, 2013,

    A Bayesian statistical assessment of representative samples for asteroidal or meteoritical material

    , Meteoritics &amp; Planetary Science, Vol: 48, Pages: 976-996, ISSN: 1086-9379

    <jats:title>Abstract</jats:title><jats:p>Primitive substances in asteroid and meteorite materials represent a record of early solar system evolution. To allow the study of these materials, they must be collected and transferred to the laboratory. Collection during sample return missions requires an assessment of the size of samples needed. Meteorite falls or finds must be subdivided into appropriate subsamples for analysis by successive generations of scientists. It is essential, therefore, to determine a representative mass or volume at which the collected or allocated sample is representative of the whole. For the first time, we have used a Bayesian statistical approach and a selected meteorite sample, Murchison, to identify a recommended smallest sample mass that can be used without interferences from sampling bias. Enhancing background knowledge to inform sample selection and analysis is an effective means of increasing the probability of obtaining a positive scientific outcome. The influence of the subdivision mechanism when preparing samples for distribution has also been examined. Assuming a similar size distribution of fragments to that of the Murchison meteorite, cubes can be similarly representative as fragments, but at orders of magnitude smaller sizes. We find that: (1) at all defined probabilities (90%, 95%, and 99%), nanometer‐sized particles (where the axes of a three‐dimensional sample are less that a nanometer in length) are never representative of the whole; (2) at the intermediate and highest defined probabilities (95% and 99%), micrometer‐sized particles are never representative of the whole; and (3) for micrometer‐sized samples, the only sample that is representative of the whole is a cube and then only at a 90% probability. The difference between cubes and fragments becomes less important as sample size increases and any &gt;0.5 mm‐sized sample will be representative of the whole with a probability of 99.9%. The resul
  • Journal article
    Gilmour I, Gilmour M, Jolley D, Kelley S, Kemp D, Daly R, Watson Jet al., 2013,

    A high-resolution nonmarine record of an early Danian hyperthermal event, Boltysh crater, Ukraine

    , Geology
  • Journal article
    Sephton MA, 2013,

    Aromatic units from the macromolecular material in meteorites: Molecular probes of cosmic environments

    , Geochimica et Cosmochimica Acta, Vol: 107, Pages: 231-241, ISSN: 0016-7037

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