1. Distinguishing highly-related outbreak-associated Clostridium botulinum type A(B) strains.

    BMC Microbiology 14:192 (2014) PMID 25031122 PMCID PMC4112988

    In the United States, most Clostridium botulinum type A strains isolated during laboratory investigations of human botulism demonstrate the presence of an expressed type A botulinum neurotoxin (BoNT/A) gene and an unexpressed BoNT/B gene. These strains are designated type A(B). The most common p...
  2. Distinguishing highly-related outbreak-associated Clostridium botulinum type A(B) strains.

    BMC Microbiology 14:192 (2014) PMID 25031122 PMCID PMC4112988

    In the United States, most Clostridium botulinum type A strains isolated during laboratory investigations of human botulism demonstrate the presence of an expressed type A botulinum neurotoxin (BoNT/A) gene and an unexpressed BoNT/B gene. These strains are designated type A(B). The most common p...
  3. Os[sbnd]Hf isotopic insight into mantle plume dynamics beneath the East African Rift System

    Chemical Geology 320-321:66 (2012)

    We report new Os and Hf isotopic data on mafic lavas from several key portions of the East African Rift System (EARS) with the goal of determining how contributions from various source domains influence volcanism in the evolving rift system. Our study uses picrites and basalts associat...
  4. Os, Nd, O and S isotope constraints on country rock contamination in the conduit-related Eagle Cu–Ni–(PGE) deposit, Midcontinent Rift System, Upper Michigan

    Geochimica et Cosmochimica Acta 89:10 (2012)

    The Eagle Cu–Ni–(PGE) deposit is hosted by mafic to ultramafic intrusive rocks associated with the Marquette–Baraga dike swarm in northern Michigan. Sulfide mineralization formed in a conduit system during early stages in the development of the ∼1.1Ga Midcontinent Rift System. The cond...
  5. A reduced organic carbon component in martian basalts.

    Science 337(6091):212 (2012) PMID 22628557

    The source and nature of carbon on Mars have been a subject of intense speculation. We report the results of confocal Raman imaging spectroscopy on 11 martian meteorites, spanning about 4.2 billion years of martian history. Ten of the meteorites contain abiotic macromolecular carbon (MMC) phases...
  6. Composition and stability of bacterial communities associated with granular activated carbon and anthracite filters in a pilot scale municipal drinking water treatment facility.

    Journal of Water and Health 10(2):244 (2012) PMID 22717749

    Granular activated carbon (GAC) is an alternative filter substrate for municipal water treatment as it provides a high surface area suitable for microbial colonization. The resulting microbial growth promotes biodegradation of organic materials and other contaminants from influent waters. Here, ...
  7. Deep mantle cycling of oceanic crust: evidence from diamonds and their mineral inclusions.

    Science 334(6052):54 (2011) PMID 21921159

    A primary consequence of plate tectonics is that basaltic oceanic crust subducts with lithospheric slabs into the mantle. Seismological studies extend this process to the lower mantle, and geochemical observations indicate return of oceanic crust to the upper mantle in plumes. There has been no ...
  8. Start of the Wilson cycle at 3 Ga shown by diamonds from subcontinental mantle.

    Science 333(6041):434 (2011) PMID 21778395

    Mineral inclusions encapsulated in diamonds are the oldest, deepest, and most pristine samples of Earth's mantle. They provide age and chemical information over a period of 3.5 billion years--a span that includes continental crustal growth, atmospheric evolution, and the initiation of plate tect...
  9. Re–Os isotope systematics in Samoan shield lavas and the use of Os-isotopes in olivine phenocrysts to determine primary magmatic compositions

    Earth and Planetary Science Letters 312(1):91 (2011)

    Samoan shield-stage lavas (from the islands of Ta'u, Savai'i, and Ofu and the seamounts of Vailulu'u and Malumalu) with Os concentrations > 30 ppt have 187Os/ 188Os ratios that exhibit a narrow range of values between 0.128 and 0.132. Lavas with ≤ 30 ppt...
  10. Osmium isotopes in Grande Comore lavas: A new extreme among a spectrum of EM-type mantle endmembers

    Earth and Planetary Science Letters 284(1):219 (2009)

    Osmium isotopes for volcanic rocks from Grande Comore, the youngest island of the Comores Archipelago, located between East Africa and Madagascar, show systematic differences between the two volcanoes of the island. 187Os/ 188Os ratios (0.15–0.16) in shield-stage alkali basalts...
  11. Boron isotopic variations in NW USA rhyolites: Yellowstone, Snake River Plain, Eastern Oregon

    Journal of Volcanology and Geothermal Research 188(1):162 (2009)

    The geochemistry of NW USA rhyolites correlates strongly with geography and the nature of the underlying basement terranes. Rhyolites from the Snake River Plain-Yellowstone (SRPY) province have higher 87Sr/ 86Sr, 207Pb/ 206Pb, and lower 143Nd/ 144Nd th...
  12. Discriminating assimilants and decoupling deep- vs. shallow-level crystal records at Mount Adams using238U–230Th disequilibria and Os isotopes

    Earth and Planetary Science Letters 277(1):38 (2009)

    A suite of 23 basaltic to dacitic lavas erupted over the last 350 kyr from the Mount Adams volcanic field has been analyzed for U–Th isotope compositions to evaluate the roles of mantle versus crustal components during magma genesis. All of the lavas have ( 230Th/ 238U) > ...
  13. Sulphide survival and diamond genesis during formation and evolution of Archaean subcontinental lithosphere: A comparison between the Slave and Kaapvaal cratons

    Lithos 112:747 (2009)

    Sulphide inclusions from 35 eclogitic and 7 peridotitic diamonds from the Diavik kimberlites in the central Slave craton have been characterized to address questions of diamond age and craton formation. Eclogitic sulphide inclusions occur in diamonds with mantle-like δ 13C (− ...
  14. Continental mantle signature of Bushveld magmas and coeval diamonds.

    Nature 453(7197):910 (2008) PMID 18548068

    The emplacement of the 2.05-billion-year-old Bushveld complex, the world's largest layered intrusion and platinum-group element (PGE) repository, is a singular event in the history of the Kaapvaal craton of southern Africa, one of Earth's earliest surviving continental nuclei. In the prevailing ...
  15. Lithium isotopes in global mid-ocean ridge basalts

    Geochimica et Cosmochimica Acta 72(6):1626 (2008)

    The lithium isotope compositions of 30 well-characterized samples of glassy lavas from the three major mid-ocean ridge segments of the world, spanning a wide range in radiogenic isotope and elemental content and sea floor physical parameters, have been measured. The overall data set shows a...
  16. Residual platinum-group minerals from highly depleted harzburgites of the Lherz massif (France) and their role in HSE fractionation of the mantle

    Geochimica et Cosmochimica Acta 71(12):3082 (2007)

    In order to constrain the highly siderophile elements (HSE: Re and platinum group elements (PGE: Os, Ir, Ru, Pt and Pd)) host mineral(s) in refractory, base metal sulfide-free mantle residues, four very depleted spinel–harzburgites from the Lherz massif (France) have been analyzed for HSE i...
  17. Osmium isotope evidence for uniform distribution ofs- andr-process components in the early solar system

    Earth and Planetary Science Letters 259(3):567 (2007)

    We have precisely measured Os isotopic ratios in bulk samples of five carbonaceous, two enstatite and two ordinary chondrites, as well as the acid-resistant residues of three carbonaceous chondrites. All bulk meteorite samples have uniform 186Os/ 188Os, 188Os/ 189O...
  18. The effects of variable sources, processes and contaminants on the composition of northern EPR MORB (8–10°N and 12–14°N): Evidence from volatiles (H2O, CO2, S) and halogens (F, Cl)

    Earth and Planetary Science Letters 251(3):209 (2006)

    New volatile (H 2O, CO 2, S), halogen (F, Cl) and trace-element data for selected fresh MORB glasses are reported from two geologically and geophysically well-studied regions on the East Pacific Rise (8–10°N and 12–14°N) with distinct differences in spreading rate and magma supp...
  19. Os–Hf–Sr–Nd isotope and PGE systematics of spinel peridotite xenoliths from Tok, SE Siberian craton: Effects of pervasive metasomatism in shallow refractory mantle

    Earth and Planetary Science Letters 241(1):47 (2006)

    Os–Hf–Sr–Nd isotopes and PGE were determined in peridotite xenoliths carried to the surface by Quaternary alkali basaltic magmas in the Tokinsky Stanovik Range on the Aldan shield. These data constrain the timing and nature of partial melting and metasomatism in the lithospheric mantle bene...
  20. Integrated models of diamond formation and craton evolution

    Lithos 77(1):923 (2004)

    Two decades of diamond research in southern Africa allow the age, average N content and carbon composition of diamonds, and the dominant paragenesis of their syngenetic silicate and sulfide inclusions to be integrated on a cratonwide scale with a model of craton formation. Individual eclogi...