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Conference paperMuxworthy AR, Heslop D, 2007,
Revisiting hysteresis quantification and representation (poster)
, EGU -
Conference paperMuxworthy AR, Williams W, 2007,
Critical single-domain/multidomain grain-sizes in non-interacting and interacting elongated magnetite particles: implications for magnetosomes
, EGU -
Journal articleMorgan J, Christeson G, Gulick S, et al., 2007,
Joint IODP/ICDP scientific drilling of the Chicxulub impact crater
, Scientific Drilling, Vol: 4, Pages: 42-44, ISSN: 1816-8957 -
Journal articleRipperger S, Rehkaemper M, 2007,
Precise determination of cadmium isotope fractionation in seawater by double spike MC-ICPMS
, GEOCHIMICA ET COSMOCHIMICA ACTA, Vol: 71, Pages: 631-642, ISSN: 0016-7037- Author Web Link
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- Citations: 113
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Conference paperMuxworthy AR, Williams W, 2007,
Magnetostatic Interactions:Palaeomagnetic signals and magnetotactic bacteria
, Magnetic Interactions -
Journal articleParbhakar A, Cuadros J, Sephton MA, et al., 2007,
Adsorption of L-lysine on montmorillonite
, COLLOID SURFACE A, Vol: 307, Pages: 142-149, ISSN: 0927-7757Amino acid adsorption on smectite is relevant to prebiotic processes involving possible catalytic reactions in the early Solar System, as implied by the clay-organic correlation found in meteorites, and the generation and modification of organic components essential for the origin of life. Here we report the results of a study investigating the adsorption of l-lysine (0.025–0.4 M) onto montmorillonite. The reaction products were studied using X-ray diffraction, chemical analysis and infrared spectroscopy.We find that lysine adsorption is first dominated by cation exchange and then by adsorption of electrically neutral lysine (as a zwitterion), as indicated by chemical and FTIR evidence. At the maximum concentration, lysine displaces only ∼1/3 of the original interlayer cations. The d-spacing of the smectite–lysine complex increases from 1.2 to 2.1 nm as more lysine enters the interlayer space, and water is expelled. We propose a structural model of lysine sorption in the interlayer in which lysine is oriented at >45–90◦ to the plane of siloxane O atoms.
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Journal articleWignall PB, Zonneveld J-P, Newton RJ, et al., 2007,
The end Triassic mass extinction record of Williston Lake, British Columbia
, PALAEOGEOGR PALAEOCL, Vol: 253, Pages: 385-406, ISSN: 0031-0182 -
Journal articleRipperger S, Rehkaemper M, 2007,
A highly sensitive MC-ICPMS method for Cd/Ca analyses of foraminiferal tests
, JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, Vol: 22, Pages: 1275-1283, ISSN: 0267-9477- Author Web Link
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- Citations: 7
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Journal articleSiegert MJ, Behar A, Bentley M, et al., 2007,
Exploration of Ellsworth Subglacial Lake: a concept paper on the development, organisation and execution of an experiment to explore, measure and sample the environment of a West Antarctic subglacial lake
, Reviews in Environmental Science and Biotechnology, Vol: 6, Pages: 161-179, ISSN: 1569-1705 -
Journal articlePearson VK, Kearsley AT, Sephton MA, et al., 2007,
The labelling of meteoritic organic material using osmium tetroxide vapour impregnation
, PLANET SPACE SCI, Vol: 55, Pages: 1310-1318, ISSN: 0032-0633 -
Journal articlePerry RS, Mcloughlin N, Lynne BY, et al., 2007,
Defining biominerals and organominerals: Direct and indirect indicators of life
, SED GEOL, Vol: 201, Pages: 157-179, ISSN: 0037-0738 -
Journal articlePerry RS, Sephton MA, 2007,
Baking black opal in the desert sun: The importance of silica in desert varnish: comment and reply
, GEOLOGY, Vol: 35, Pages: e123-e123, ISSN: 0091-7613 -
Book chapterMuxworthy A R, Roberts A P, 2007,
First-order reversal curve (FORC) diagrams
, Encyclopedia of Geomagnetism and Paleomagnetism, Editors: Gubbins, Herrero-Bervera, Publisher: Springer, Pages: 266-272, ISBN: 9781402044236 -
Journal articleParnell J, Cullen D, Sims MR, et al., 2007,
Searching for Life on Mars: Selection of Molecular Targets for ESA’s Aurora ExoMars Mission
, Astrobiology, Vol: 7, Pages: 578-604, ISSN: 1531-1074The European Space Agency’s ExoMars mission will seek evidence of organic compounds of biological and non-biological origin at the martian surface. One of the instruments in the Pasteur payload may be a Life Marker Chip that utilizes an immunoassay approach to detect specific organic molecules or classes of molecules. Therefore, it is necessary to define and prioritize specific molecular targets for antibody development. Target compounds have been selected to represent meteoritic input, fossil organic matter, extant (living, recently dead) organic matter, and contamination. Once organic molecules are detected on Mars, further information is likely to derive from the detailed distribution of compounds rather than from single molecular identification. This will include concentration gradients beneath the surface and gradients from generic to specific compounds. The choice of biomarkers is informed by terrestrial biology but is wide ranging, and nonterrestrial biology may be evident from unexpected molecular distributions. One of the most important requirements is to sample where irradiation and oxidation are minimized, either by drilling or by using naturally excavated exposures. Analyzing regolith samples will allow for the search of both extant and fossil biomarkers, but sequential extraction would be required to optimize the analysis of each of these in turn.
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Journal articleCourt RW, Sephton MA, Parnell J, et al., 2007,
Raman spectroscopy of irradiated organic matter
, GEOCHIM COSMOCHIM AC, Vol: 71, Pages: 2547-2568, ISSN: 0016-7037Raman spectroscopy of a range of irradiated and nonirradiated natural terrestrial bitumens has revealed that radiolytic alteration is generally associated with an increase in structural disorganisation. An interpretational methodology designed to overcome the considerable difficulties in obtaining reproducible, meaningful parameters of structural disorganisation is also presented, and should prove useful for future Raman applications. Raman investigation of a set of bitumens reported to have formed by the radiolytic polymerisation of light hydrocarbons, such as methane, has revealed excessive structural disorganisation, relative to biogenic complex-hydrocarbon-derived bitumens of similar radioelement concentrations, which may indicate the importance of precursor materials on the organic products of irradiation. Variations in the R1 ratio (D1/G band intensity) are found to be the best guide to variations in structural organisation. Comparisons of Raman spectra of the same sample, but produced by different exciting wavelengths, reveal the importance of the selection of a suitable laser wavelength. The results are discussed in terms of analyses of irradiated organic matter in the solar system, especially cometary nuclei and carbonaceous chondrites.
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Journal articleZolensky ME, Zega TJ, Yano H, et al., 2006,
Report - Mineralogy and petrology of comet 81P/Wild 2 nucleus samples
, SCIENCE, Vol: 314, Pages: 1735-1739, ISSN: 0036-8075- Author Web Link
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- Citations: 577
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Journal articleBrownlee D, Tsou P, Aleon J, et al., 2006,
Comet 81P/Wild 2 under a microscope
, SCIENCE, Vol: 314, Pages: 1711-1716, ISSN: 0036-8075- Author Web Link
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- Citations: 816
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Journal articleGoldin TJ, Wunnemann K, Melosh HJ, et al., 2006,
Hydrocode modeling of the Sierra Madera impact structure
, METEORIT PLANET SCI, Vol: 41, Pages: 1947-1958, ISSN: 1086-9379 -
Journal articleMuxworthy AR, Williams W, 2006,
Critical single-domain/multidomain grain sizes in noninteracting and interacting elongated magnetite particles: Implications for magnetosomes
, JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, Vol: 111, ISSN: 2169-9313- Author Web Link
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- Citations: 89
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Journal articleWilliams W, Muxworthy AR, Paterson GA, 2006,
Configurational anisotropy in single-domain and pseudosingle-domain grains of magnetite
, JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, Vol: 111, ISSN: 2169-9313- Author Web Link
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- Citations: 21
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