58 research outputs found
Molecular evidence of Late Archean archaea and the presence of a subsurface hydrothermal biosphere
Author Posting. © National Academy of Sciences of the USA, 2007. This is the author's version of the work. It is posted here by permission of National Academy of Sciences of the USA for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences 104 (2007): 14260-14265, doi:10.1073/pnas.0610903104.Highly cracked and isomerized archaeal lipids and bacterial lipids, structurally changed
by thermal stress, are present in solvent extracts of 2,707-2,685 million year old (Ma)
metasedimentary rocks from Timmins, Ontario, Canada. These lipids appear in
conventional gas chromatograms as unresolved complex mixtures (UCMs) and include
cyclic and acyclic biphytanes, C36-C39 derivatives of the biphytanes, and C31-C35
extended hopanes. Biphytane and extended hopanes are also found in high pressure
catalytic hydrogenation (HPCH) products released from solvent-extracted sediments,indicating that archaea and bacteria were present in Late Archean sedimentary
environments. Post-depositional, hydrothermal gold mineralization and graphite
precipitation occurred prior to metamorphism (~2,665 Ma). Late Archean metamorphism
significantly reduced the kerogen’s adsorptive capacity and severely restricted sediment
porosity, limiting the potential for post-Archean additions of organic matter to the
samples. Argillites exposed to hydrothermal gold mineralization have disproportionately
high concentrations of extractable archaeal and bacterial lipids relative to what is
releasable from their respective HPCH product and what is observed for argillites
deposited away from these hydrothermal settings. The addition of these lipids to the
sediments likely results from a Late Archean subsurface hydrothermal biosphere of
archaea and bacteria.This project was supported by NASA Exobiology grant #NAG5-13446 to Fabien Kenig.
SEM analysis was supported by NSF grant EAR 0318769 to Juergen Schieber. GC×GC
analysis was supported by NSF grant IIS-0430835 and the Seaver Foundation to
Christopher M. Reddy
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Evaluation of medical isotope production with the accelerator production of tritium (APT) facility
The accelerator production of tritium (APT) facility, with its high beam current and high beam energy, would be an ideal supplier of radioisotopes for medical research, imaging, and therapy. By-product radioisotopes will be produced in the APT window and target cooling systems and in the tungsten target through spallation, neutron, and proton interactions. High intensity proton fluxes are potentially available at three different energies for the production of proton- rich radioisotopes. Isotope production targets can be inserted into the blanket for production of neutron-rich isotopes. Currently, the major production sources of radioisotopes are either aging or abroad, or both. The use of radionuclides in nuclear medicine is growing and changing, both in terms of the number of nuclear medicine procedures being performed and in the rapidly expanding range of procedures and radioisotopes used. A large and varied demand is forecast, and the APT would be an ideal facility to satisfy that demand
Advances in structure elucidation of small molecules using mass spectrometry
The structural elucidation of small molecules using mass spectrometry plays an important role in modern life sciences and bioanalytical approaches. This review covers different soft and hard ionization techniques and figures of merit for modern mass spectrometers, such as mass resolving power, mass accuracy, isotopic abundance accuracy, accurate mass multiple-stage MS(n) capability, as well as hybrid mass spectrometric and orthogonal chromatographic approaches. The latter part discusses mass spectral data handling strategies, which includes background and noise subtraction, adduct formation and detection, charge state determination, accurate mass measurements, elemental composition determinations, and complex data-dependent setups with ion maps and ion trees. The importance of mass spectral library search algorithms for tandem mass spectra and multiple-stage MS(n) mass spectra as well as mass spectral tree libraries that combine multiple-stage mass spectra are outlined. The successive chapter discusses mass spectral fragmentation pathways, biotransformation reactions and drug metabolism studies, the mass spectral simulation and generation of in silico mass spectra, expert systems for mass spectral interpretation, and the use of computational chemistry to explain gas-phase phenomena. A single chapter discusses data handling for hyphenated approaches including mass spectral deconvolution for clean mass spectra, cheminformatics approaches and structure retention relationships, and retention index predictions for gas and liquid chromatography. The last section reviews the current state of electronic data sharing of mass spectra and discusses the importance of software development for the advancement of structure elucidation of small molecules
Decision making and strategic planning for disaster preparedness with a multi-criteria-analysis decision support system
In the context of the CRISMA FP7 project we have developed a seamless decision support concept to connect simulated crisis scenarios and aggregated performance indicators of impact scenarios with state of the art Multi- Criteria Decision Analysis (MCDA) methods. To prove the practicality of the approach we have developed a decision support tool realising the important aspects of the method. The tool is a highly interactive and user-friendly decision support system (DSS) that effectively helps the decision maker and strategic planner to perform multi-criteria ranking of scenarios. The tool is based on state-of-the-art web technologies
An Architecture for the Semantic Enhancement of Environmental Resources
Part 4: Semantics and EnvironmentInternational audienceThe vision of a Single Information Space in Europe for the Environment (SISE) requires seamless access to environmental resources, including data, models and services. Standardization organizations like OGC and OASIS have laid the foundations for interoperability on a syntactic level for many aspects of distributed environmental information systems (e.g. OGC SWE for sensor information). At the same time, the EC has undertaken a considerable effort to commit European stakeholders to offering their environmental information in such a way that it is accessible by interested parties, both on the scientific level by supporting research projects, like ORCHESTRA and SANY, and on the legal level by introducing directives (such as the INSPIRE directive). This development, amongst others, has led to the present situation in which a large number of environmental information sources are available. However, to implement the vision of the SISE it is not enough to publish resources. Environmental information must be discoverable, and it must be ‘understandable’ in different contexts in order to be used effectively by parties of various thematic domains. Therefore, in order to foster the implementation of SISE, semantic interoperability is a necessary element. Key to semantic interoperability is the presence of meta-information which describes the concepts of the environmental resources. Producing this meta-information puts a heavy technological burden on the individual resource providers such that it seems unlikely that enough semantic meta-information will ever be made available to reach semantic interoperability and thus accomplish the vision of SISE unless other ways to provide this essential meta-information are found. In this paper we introduce an architecture, developed in the FP7 project TaToo (247893), which tries to overcome the aforementioned obstacles by providing the possibility to easily annotate and rate environmental information resources, even by parties which do not own the resource, and transparently equipping this information with domain knowledge and thus enhancing discoverability and usability of resources with semantic technologies. The objective of the architecture is to seamlessly blend in with existing infrastructures by making use of de facto standards while offering support for discovery, annotation and validation of environmental resources through open interfaces
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