نتایج جستجو برای: isotopic

تعداد نتایج: 18280  

Journal: :iranian journal of earth science 0
s. saadat department of geological sciences, university of colorado, boulder, co, usa, and islamic azad university, mashhad branch, iran m. h. karimpour research center for ore deposit of eastern iran, ferdowsi university of mashhad, iran ch. stern department of geological sciences, university of colorado, boulder, co, 80309-0399 usa

the nayband strike-slip fault forms the western margin of the micro-continental lut block in eastern iran. neogene and quaternary mafic volcanic rocks collected near tabas, along the northern part of the fault (nnf; 15 ma), and further to the south, along the middle part of the fault (mnf; 2 ma), are within-plate sodic-series alkali olivine basalts with high tio2 and up to >16% normative nephel...

2016
Justin D. Yeakel Uttam Bhat Emma A. Elliott Smith Seth D. Newsome

Consumer foraging behaviors are dynamic, changing in response to prey availability, seasonality, competition, and even the consumer’s physiological state. The isotopic composition of a consumer is a product of these factors as well as the isotopic “landscape” of its prey, i.e., the isotopic mixing space. Stable isotope mixing models are used to back-calculate the most likely proportional contri...

2006
Christine Floss Frank J. Stadermann John P. Bradley Rong Dai Sasa Bajt Giles Graham A. Scott Lea

We have carried out a comprehensive survey of the isotopic compositions (H, B, C, N, O, and S) of a suite of interplanetary dust particles (IDPs), including both cluster and individual particles. Isotopic imaging with the NanoSIMS shows the presence of numerous discrete hotspots that are strongly enriched in N, up to 1300&. A number of the IDPs also contain larger regions with more modest enric...

Journal: :Metallomics : integrated biometal science 2015
Fiona Larner Laura N Woodley Sami Shousha Ashley Moyes Emma Humphreys-Williams Stanislav Strekopytov Alex N Halliday Mark Rehkämper R Charles Coombes

An early diagnostic biomarker for breast cancer is essential to improve outcome. High precision isotopic analysis, originating in Earth sciences, can detect very small shifts in metal pathways. For the first time, the natural intrinsic Zn isotopic compositions of various tissues in breast cancer patients and controls were determined. Breast cancer tumours were found to have a significantly ligh...

2003
Miriam E. Katz David R. Katz James D. Wright Kenneth G. Miller Dorothy K. Pak Nicholas J. Shackleton Ellen Thomas

[1] Oxygen and carbon isotope records are important tools used to reconstruct past ocean and climate conditions, with those of benthic foraminifera providing information on the deep oceans. Reconstructions are complicated by interspecies isotopic offsets that result from microhabitat preferences (carbonate precipitation in isotopically distinct environments) and vital effects (species-specific ...

فضلی, سمانه, شفیعی, بهنام , شمعانیان, غلامحسین,

The Emarat and Muchan zinc-lead ore deposits are located in southwest of Arak within the middle part of the Malayer-Esfahan belt. These deposits have formed as stratabound within carbonate strata of Lower Cretaceous. Mineralization in these deposits is mainly open space filling, which consists of sphalerite, galena, pyrite and minor quantities of chalcopyrite associated with host rock silicific...

یاجم , ساناز ,

The Qalaylan pluton of Late Jurassic age is composed of intermediate and felsic rocks that crop out in the northern Sanandaj-Sirjan Zone. A body is comprising alkaline, high K, Ferroan A1-type rocks with contrasting aspects; whiles, Nd-Sr primitive isotopic composition consistent with a mantle source. On the other hand, inherited zircon cores (with a range of 230 – 2700 Ma) and elevated Nd mode...

2003
David R. Bowling Diane E. Pataki James R. Ehleringer

Isotopic net ecosystem exchange (isofluxes, or flux densities of CO2) can be combined with standard eddy covariance methods to partition net ecosystem exchange of carbon dioxide (F) into its component one-way fluxes, photosynthesis and respiration. At present, the approaches used to estimate isotopic fluxes are labor-intensive and dependent on several assumptions. To assess the relative utility...

2015
M. Bolot B. Legras E. J. Moyer

The isotopic compositions of water vapour and its condensates have long been used as tracers of the global hydrological cycle, but may also be useful for understanding processes within individual convective clouds. We review here the representation of processes that alter water isotopic compositions during processing of air in convective updrafts and present a unified model for water vapour iso...

Journal: :Journal of the American Society for Mass Spectrometry 2008
Dirk Valkenborg Ivy Jansen Tomasz Burzykowski

The process of monoisotopic mass determination, i.e., nomination of the correct peak of an isotopically resolved group of peptide peaks as a monoisotopic peak, requires prior information about the isotopic distribution of the peptide. This points immediately to the difficulty of monoisotopic mass determination, whereas a single mass spectrum does not contain information about the atomic composi...

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