نتایج جستجو برای: isotope

تعداد نتایج: 32576  

2000
NAN CRYSTAL ARENS

A 1.5‰ to 2‰ carbon isotope excursion immediately above the clay layer that defines the Cretaceous-Tertiary (K/ T) boundary has been reported in marine sediments world wide. This paper reports a similar 1.5‰ to 2.8‰ carbon isotope excursion recorded by C3 land plants from three temporally-controlled, stratigraphically-constrained terrestrial sections in the Western Interior of North America (Ga...

Journal: :Bioinformatics 2006
Jeanette E. Eckel-Passow Ann L. Oberg Terry M. Therneau C. J. Mason Douglas W. Mahoney K. L. Johnson J. E. Olson H. R. Bergen

MOTIVATION Using stable isotopes in global proteome scans, labeled molecules from one sample are pooled with unlabeled molecules from another sample and subsequently subjected to mass-spectral analysis. Stable-isotope methodologies make use of the fact that identical molecules of different stable-isotope compositions are differentiated in a mass spectrometer and are represented in a mass spectr...

Journal: :Rapid communications in mass spectrometry : RCM 2016
M Isaac-Renton L Schneider K Treydte

RATIONALE Isotope analysis of wood is an important tool in dendrochronology and ecophysiology. Prior to mass spectrometry analysis, wood must be homogenized, and a convenient method involves a ball mill capable of milling samples directly in sample tubes. However, sample-tube plastic can contaminate wood during milling, which could lead to biological misinterpretations. METHODS We tested poss...

2010
Lucy Stap Lucas Lourens Arnold van Dijk Stefan Schouten Ellen Thomas

[1] Eocene Thermal Maximum 2 (ETM2; ∼53.7 Ma) occurred approximately 2 Myr after the Paleocene‐ Eocene Thermal Maximum (∼55.5 Ma) and was characterized by a deep‐sea warming of >3°C, associated with massive release of carbon into the ocean‐atmosphere system. We performed single‐specimen stable isotope analyses of the planktic foraminiferal genera Acarinina (surface dweller) and Subbotina (therm...

2014
Yajun An Fang Huang

Application of multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) has led to big breakthrough of analytical methods for metal stable isotopes, resulting in rapid progresses in non-traditional stable isotope geochemistry. As a new geological tracer, Mg isotopes have been widely applied in studies of almost all important disciplines of geochemistry. High precision Mg isotope...

2014
Junjun Zhang Shichun Huang Andrew M. Davis Nicolas Dauphas Akihiko Hashimoto Stein B. Jacobsen

Isotope fractionations associated with high temperature evaporation provide important constraints on the physicochemical processes that affected planetary materials at the birth of the solar system. Previous evaporation experiments have focused on isotopic fractionation of moderately to highly volatile elements. Here, we investigate the isotope fractionation behavior of two highly refractory el...

Journal: :The Review of scientific instruments 2016
Hyunchang Jin Ji-Ho Jang Hyojae Jang In-Seok Hong

RAON (Rare isotope Accelerator Of Newness) heavy ion accelerator of the rare isotope science project in Daejeon, Korea, has been designed to accelerate multiple-charge-state beams to be used for various science programs. In the RAON accelerator, the rare isotope beams which are generated by an isotope separation on-line system with a wide range of nuclei and charges will be transported through ...

2008
M. G. Kozlov

We present an accurate ab initio method of calculating transition energies and isotope shifts in the 3d-transition metals. It extends previous work that combines the configuration-interaction calculation with many-body perturbation theory by including the effective three-body interaction and modification of the energy denominator. We show that these effects are of importance in Ti II. The need ...

Journal: :Ecology 2007
Kathryn A Harrison Roland Bol Richard D Bardgett

The growing awareness that plants might use a variety of nitrogen (N) forms, both organic and inorganic, has raised questions about the role of resource partitioning in plant communities. It has been proposed that coexisting plant species might be able to partition a limited N pool, thereby avoiding competition for resources, through the uptake of different chemical forms of N. In this study, w...

2014
David M. Doughty Michael Dieterle Alex L. Sessions Woodward W. Fischer Dianne K. Newman

The organization of lipids within biological membranes is poorly understood. Some studies have suggested lipids group into microdomains within cells, but the evidence remains controversial due to non-native imaging techniques. A recently developed NanoSIMS technique indicated that sphingolipids group into microdomains within membranes of human fibroblast cells. We extended this NanoSIMS approac...

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