Search or filter publications

Filter by type:

Filter by publication type

Filter by year:

to

Results

  • Showing results for:
  • Reset all filters

Search results

  • Book chapter
    Emmerton S, Muxworthy AR, Sephton MA, 2012,

    Magnetic characterization of oil sands at Osmington Mills and Mupe Bay, Wessex Basin, UK

    , Remagnetization and Chemical Alteration of Sedimentary Rocks, Editors: Elmore, Muxworthy, Aldana, Mena, Elmore, Muxworthy, Aldana, Mena, London, Publisher: Geological Society, Pages: 189-198
  • Journal article
    Rehkämper M, Schönbächler M, Andreasen R, 2012,

    Application of Multiple-Collector Inductively Coupled Plasma Mass Spectrometry to Isotopic Analysis in Cosmochemistry

    , Pages: 275-315
  • Journal article
    Christeson GL, Morgan JV, Warner MR, 2012,

    Shallow oceanic crust: Full waveform tomographic images of the seismic layer 2A/2B boundary

    , Journal of Geophysical Research, Vol: 117

    We present results of full-waveform tomographic inversions of four profiles acquired over young intermediate- and fast spreading rate oceanic crust. The mean velocity-depth functions from our study include a 0.25–0.30 km-thick low-velocity, low-gradient region beneath the seafloor overlying a 0.24–0.28-km-thick high-gradient region; together these regions compose seismic layer 2A. Mean layer 2A interval velocities are 3.0–3.2 km/s. The mean depth to the layer 2A/2B boundary is 0.49–0.54 km, and mean velocities within the upper 0.25 km of layer 2B are 4.7–4.9 km/s. Previous velocity analyses of the study areas using 1-D ray tracing underestimate the thickness of the high-gradient region at the base of layer 2A. We observe differences in the waveform inversion velocity models that correspond to imaging of the layer 2A event; regions with a layer 2A event have higher velocity gradients at the base of layer 2A. Intermittent high velocities, which we interpret as massive flows, are observed in the waveform inversion velocity models at 0.05–0.10 km below the seafloor (bsf) over 10–25% of the intermediate-spreading profiles and 20–45% of the fast spreading profiles. The high-gradient region located 0.25–0.54 km bsf at the base of layer 2A may be associated with an increased prevalence of massive flows, the first appearance of dikes (lava-dike transition zone), or with increased crack sealing by hydrothermal products. The upper portion of layer 2B, which begins at 0.49–0.54 km bsf, may correspond to sheeted dikes or the top of the transition zone of lavas and dikes.

  • Journal article
    Larner F, Rehkaemper M, 2012,

    Evaluation of Stable Isotope Tracing for ZnO Nanomaterials-New Constraints from High Precision Isotope Analyses and Modeling

    , ENVIRONMENTAL SCIENCE & TECHNOLOGY, Vol: 46, Pages: 4149-4158, ISSN: 0013-936X
  • Conference paper
    Biggin AJ, Badejo S, Shaw J, Dekkers MJ, Muxworthy ARet al., 2012,

    How does cooling rate affect the intensity of thermoremanent magnetisation in samples containing multidomain and interacting single domain ferrimagnetic grains? (poster)

    , EGU
  • Conference paper
    Harrison RJ, Muxworthy AR, Lappe SCLL, 2012,

    FORCintense: A graphical implementation of the Preisach method of paleointensity estimation within FORCinel

    , EGU
  • Journal article
    Collins GS, 2012,

    Moonstruck magnetism

    , Science, Vol: 335, Pages: 1176-1177
  • Journal article
    Voldman GG, Genge MJ, Albanesi GL, Barnes CR, Ortega Get al., 2013,

    Cosmic spherules from the Ordovician of Argentina

    , GEOLOGICAL JOURNAL, Vol: 48, Pages: 222-235, ISSN: 0072-1050
  • Journal article
    Spurny P, Bland PA, Shrbeny L, Borovicka J, Ceplecha Z, Singelton A, Bevan AWR, Vaughan D, Towner MC, McClafferty TP, Toumi R, Deacon Get al., 2012,

    The Bunburra Rockhole meteorite fall in SW Australia: fireball trajectory, luminosity, dynamics, orbit, and impact position from photographic and photoelectric records

    , METEORITICS & PLANETARY SCIENCE, Vol: 47, Pages: 163-185, ISSN: 1086-9379
  • Journal article
    Collins GS, Melosh HJ, Osinski GR, 2012,

    The Impact-Cratering Process

    , ELEMENTS, Vol: 8, Pages: 25-30, ISSN: 1811-5209
  • Conference paper
    Almeida T, Muxworthy AR, Williams W, Dunin-Borkowski Ret al., 2012,

    Dynamic chemical processes examined by in situ TEM and the implications for investigating palaeomagnetism

    , Magnetic Relaxation
  • Conference paper
    Emmerton S, Muxworthy AR, Sephton MA, Williams Wet al., 2012,

    A relationship between biodegradation and magnetisation in oil sands

    , Magnetic Relaxation
  • Conference paper
    Muxworthy AR, Evans ME, 2012,

    How well can “single crystals” record the geomagnetic field?

    , Magnetic Relaxation
  • Journal article
    Xue Z, Rehkaemper M, Schoenbaechler M, Statham PJ, Coles BJet al., 2012,

    A new methodology for precise cadmium isotope analyses of seawater

    , ANALYTICAL AND BIOANALYTICAL CHEMISTRY, Vol: 402, Pages: 883-893, ISSN: 1618-2642
  • Conference paper
    Montgomery WB, Court RW, Watson JS, Sephton MA, Rees ACet al., 2012,

    Quantitative laboratory assessment of aquathermolysis chemistry during steam-assisted recovery of heavy oils and bitumen

    , World Heavy Oil Congress Paper WHOC12-402

    In order to quantitatively study aquathermolysis chemistry during the thermal (steam-assisted) recovery of heavy oils & bitumen we have subjected a well-characterized heavy oil sample to 325°C and 2000 psi (13.8 MPa) in the continued presence of liquid water for 24 hours. The reaction products include gases, oil flotate, water-soluble products, and water-insoluble residues. All have been studied with a variety of analytical techniques, including FTIR spectroscopy, chromatographic fractionation (SARA analysis), and GC-MS. Results suggests that some in-situ upgrading of the oil occurs under these conditions. The methods discussed will be useful for the measurement of data to support model development for use in the engineering design of facilities for the thermal recovery of heavy oils and bitumen.

  • Journal article
    Chan HS, Martins Z, Sephton MA, 2012,

    Fluorescence spectroscopy for the detection of life in the Salten Skov Mars regolith analogue

    , Planetary and Space Science, Vol: 68, Pages: 42-47
  • Conference paper
    Miljkovic K, Collins GS, Chapman DJ, Patel MR, Proud WGet al., 2012,

    HIGH-VELOCITY IMPACTS IN POROUS SOLAR SYSTEM MATERIALS

    , 7th Biennial Conference of the American-Physical-Society-Topical-Group on Shock Compression of Condensed Matter, Publisher: AMER INST PHYSICS, ISSN: 0094-243X
  • Journal article
    Sims MR, Cullen DC, Rix CS, Buckley A, Derveni M, Evans D, Garcia-Con LM, Miguel García-Con L, Rhodes A, Rato CC, Stefinovic M, Sephton MA, Court RW, Bulloch C, Kitchingman I, Ali Z, Pullan D, Holt J, Blake O, Sykes J, Samara-Ratna P, Canali M, Borst G, Leeuwis H, Prak A, Norfini A, Geraci E, Tavanti M, Brucato N, Holm Net al., 2012,

    Development Status of the Life Marker Chip Instrument for ExoMars

    , Planetary and Space Science, ISSN: 0032-0633

    The Life Marker Chip (LMC) is one of the instruments being developed for possible flight on the 2018 ExoMars mission. The instrument uses solvents to extract organic compounds from samples of martian regolith and to transfer the extracts to dedicated detectors based around the use of antibodies. The scientific aims of the instrument are to detect organics in the form of biomarkers that might be associated with extinct life, extant life or abiotic sources of organics. The instrument relies on a novel surfactant-based solvent system and bespoke, commercial and research-developed antibodies against a number of distinct biomarkers or molecular types. The LMC comprises a number of subsystems designed to accept up to four discrete samples of martian regolith or crushed rock, implement the solvent extraction, perform microfluidic-based multiplexed antibody-assays for biomarkers and other targets, optically detect the fluorescent output of the assays, control the internal instrument pressure and temperature, in addition to the associated instrument control electronics and software. The principle of operation, the design and the instrument development status as of December 2011 are reported here. The instrument principle can be extended to other configurations and missions as needed.

  • Journal article
    Court RW, Sims MR, Cullen DC, Sephton MAet al., 2012,

    Potential failure of life detection experiments on Mars resulting from adsorption of organic compounds on to common instrument materials

    , Planetary and Space Science, Vol: 73, Pages: 262-270, ISSN: 0032-0633

    Some life detection instruments under development for operation on Mars use solvents to extract organic compounds from samples of martian regolith and rock and to transfer the extracts to dedicated detectors. However, it is possible that organic compounds extracted from martian samples and dissolved in the solvent could adsorb to instrument surfaces, potentially resulting in a failure to detect organic matter that could have been avoided by using more appropriate instrument materials. If successful detection and characterisation is to take place it is therefore essential to understand the interactions between dissolved organic targets and the surfaces of space instrument components. One such life detection instrument is the Life Marker Chip (LMC) being developed for the ExoMars mission, which relies on a novel surfactant-based solvent system and antibody-based detectors. We have tested the ability of a range of materials, including titanium, stainless steel, aluminium, the fluoropolymer Viton™, polytetrafluoroethylene (PTFE), nylon, polypropylene, polyethersulfone and cellulose acetate to adsorb a range of organic standards from the surfactant solution intended to be used by the LMC. Results indicate that aromatic hydrocarbons, specifically anthracene, are more prone to adsorption than straight chain, branched and cyclic aliphatic species. Titanium, aluminium and stainless steel show little adsorption ability and are suitable for larger-area applications. PTFE and Viton™ are suitable for use in small-area applications such as seals and filters. Nylon, polypropylene, polyethersulfone and cellulose acetate show stronger adsorption characteristics and should be avoided in the forms employed here. The ability of some materials to selectively adsorb organic compounds from solvent extracts can lower the sensitivity of life detection instruments. In future, it would be prudent to test all space instrument materials for their ability to adsorb target organic com

  • Journal article
    Lomax BH, Fraser WT, Harrington G, Blackmore S, Sephton MA, Harris NBWet al., 2012,

    A novel palaeoaltimetry proxy based on spore and pollen wall chemistry

    , Earth and Planetary Science Letters, Vol: 353-354, Pages: 22-28, ISSN: 0012-821X

    Understanding the uplift history and the evolution of high altitude plateaux is of major interest to a wide range of geoscientists and has implications for many disparate fields. Currently the majority of palaeoaltimetry proxies are based on detecting a physical change in climate in response to uplift, making the relationship between uplift and climate difficult to decipher. Furthermore, current palaeoaltimetry proxies have a low degree of precision with errors typically greater than 1 km. This makes the calculation of uplift histories and the identification of the mechanisms responsible for uplift difficult to determine. Here we report on advances in both instrumentation and our understanding of the biogeochemical structure of sporopollenin that are leading to the establishment of a new proxy to track changes in the flux of UV-B radiation over geological time. The UV-B proxy is based on quantifying changes in the concentration of UV-B absorbing compounds (UACs) found in the spores and pollen grains of land plants, with the relative abundances of UACs increasing on exposure to elevated UV-B radiation. Given the physical relationship between altitude and UV-B radiation, we suggest that the analysis of sporopollenin chemistry, specifically changes in the concentration of UACs, may offer the basis for the first climate independent palaeoaltimetry proxy. Owing to the ubiquity of spores and pollen in the fossil record, our proposed proxy has the potential to enable the reconstruction of the uplift history of high altitude plateaux at unprecedented levels of fidelity, both spatially and temporally.

This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.

Request URL: http://www.imperial.ac.uk:80/respub/WEB-INF/jsp/search-t4-html.jsp Request URI: /respub/WEB-INF/jsp/search-t4-html.jsp Query String: id=416&limit=20&page=9&respub-action=search.html Current Millis: 1713342732308 Current Time: Wed Apr 17 09:32:12 BST 2024