Results 91 to 100 of about 6,184 (250)

Cryogen‐Aided Chromatographic Purification of Millimole Quantities of Methane for Spectroscopic Clumped Isotope Analysis

Rapid Communications in Mass Spectrometry, Volume 40, Issue 18, 30 September 2026.
ABSTRACT Rationale Quantum cascade laser absorption spectroscopy (QCLAS) is a fast and reliable method for analyzing the bulk (𝛿13C‐CH4, 𝛿D‐CH4) and clumped isotopic (∆13CH3D and ∆12CH2D2) composition of methane. However, precise measurements of ∆12CH2D2 require 0.5 to 1.8 mmol of purified methane (equivalent to 15 to 40 mL at STP).
Nico Kueter, Jan G. C. Meissner, Naizhong Zhang, Léna Msonnereau, Lukas Emmenegger, Joachim Mohn, Stefano M. Bernasconi   +6 more
wiley   +1 more source

Reaffirming the Consistency of the Original Stock of NBS 19 Limestone and Its Byproduct With Finer Grain Size for δ13C and δ18O Calibrations—Both Distributed Internationally

Rapid Communications in Mass Spectrometry, Volume 40, Issue 18, 30 September 2026.
ABSTRACT Rationale Approximately 3–4 kg of NBS 19 limestone, prepared in 1982 by the U.S. Geological Survey (USGS), serves as a primary reference for the carbon isotope scales VPDB and VPDB‐LSVEC and the oxygen isotope scale VPDB. Its consensus values are +1.95‰ for δ13C and −2.2‰ for δ18O measurements.
Haiping Qi, Tyler B. Coplen, Lauren T. Reid, Stanley J. Mroczkowski   +3 more
wiley   +1 more source

Three New Calcium Formate Reference Materials for δ13C Measurements and a Redetermination of the R(13C/12C) Ratio for VPDB Based on Proton Nuclear Magnetic Resonance Measurements

Rapid Communications in Mass Spectrometry, Volume 40, Issue 18, 30 September 2026.
ABSTRACT Rationale Isotope ratio mass spectrometry (IRMS) and proton nuclear magnetic resonance (1H NMR) spectroscopy are independent techniques for determining the isotope ratio R(13C/12C) in organic compounds. However, the lack of suitable reference materials has limited intercalibration of results from these methods.
David W. Hoffman, Cornelia Rasmussen, Arndt Schimmelmann, Lauren T. Reid, Haiping Qi, Tyler B. Coplen   +5 more
wiley   +1 more source

Organic‐matter sources and stability in kettle‐hole sediments: A combined thermogravimetric and isotopic approach

Agrosystems, Geosciences &Environment, Volume 9, Issue 3, September 2026.
Abstract Kettle‐holes are small but biogeochemically active landscape elements that integrate terrestrial inputs and influence carbon and nitrogen cycling. However, the stability and sources of organic matter (OM) in kettle‐hole sediments remain poorly understood.
Safdar Bashir, Kai Nils Nitzsche, Zachary Kayler   +2 more
wiley   +1 more source

Multicontinuum Homogenization for Poroelasticity Model

International Journal for Numerical Methods in Fluids, Volume 98, Issue 9, Page 1035-1060, September 2026.
This work derives a generalized multicontinuum poroelasticity model using the multicontinuum homogenization method to enable accurate coarse‐grid simulations of coupled flow–mechanics processes in highly heterogeneous porous media. Coupled constraint cell problems are formulated, and the corresponding multicontinuum equations are rigorously derived ...
Dmitry Ammosov, Mohammed Al Kobaisi, Yalchin Efendiev   +2 more
wiley   +1 more source

Collisionless Shocks: Contemporary State After Three Quarters of a Century of Research

Reviews of Geophysics, Volume 64, Issue 3, September 2026.
Abstract The collisionless shock research started in the late 1950s. Since then, plenty of data have been accumulated due to the large number of missions in the heliosphere, providing in situ measurements of the fields and particles. The quality of these measurements has vastly improved, especially in the last two decades.
M. Gedalin, M. Balikhin, V. Krasnoselskikh   +2 more
wiley   +1 more source

Research Progress on Stable Isotope Online Testing Technology for Organic Contaminants

Yankuang ceshi, 2013
Compound-specific isotope analysis (CSIA) online is an indispensable key technique for identifying the sources of organic contaminants in the environment and characterizing their transformation processes, but there are still some problems in practical ...
FANG Jing-jing, ZHOU Ai-guo, LIU Cun-fu, GAN Yi-qun, ZHOU Jian-wei, CAI He-sheng, LIU Yun-de, ZHANG Yan-peng   +7 more
doaj  

An improved narrower-diameter EA/IRMS method with a built-in desulfurization reactor: optimization for nitrogen and carbon measurement without sulfur matrix interference

Progress in Earth and Planetary Science
Elemental analysis with isotope ratio mass spectrometry (EA/IRMS) is a widely used technique for stable isotope ratio analysis of nitrogen and carbon. Although the narrower-diameter EA/IRMS method developed to date has effectively enhanced sensitivity ...
Yohei Matsui, Wataru Fujisaki, Takahiro Aze, Toshihiro Miyajima, Shinsuke Kawagucci, Eiji Tasumi, Masahiro Yamamoto, Yoshinori Takano, Tomohiro Toki   +8 more
doaj   +1 more source

Development of CCMb: A Low‐Mg Calcite Reference Material for In Situ Measurement of δ18O, δ13C and Selected Trace Elements

Geostandards and Geoanalytical Research, Volume 50, Issue 3, Page 677-700, September 2026.
Key Points Low‐Mg calcite RM developed for in situ microanalysis applications in palaeoclimatology (δ18O, δ13C; Mg, Sr m/m). New data for calcite CRM IAEA‐603 (δ18O, δ13C by SIMS and GS‐IRMS; Mg m/m). No detectable IMF effect of Mg on SIMS δ18O determinations for mass fractions < 3650 μg g‐1.
Andreas T. Hertwig, Maciej G. Śliwiński, Irene Cantarero, Richard A. Stern, Carles Fàbrega, Jakub T. Śliwiński, Thomas Ludwig, František Majs, William Nachlas, John H. Fournelle, Xavier Llovet, Rachelle B. Turnier, David Parcerisa, Anna Travé   +13 more
wiley   +1 more source

The 3D genome of Gigaspora margarita unveils stable chromatin and nucleolar organization and symbiont‐dependent genome dynamics

New Phytologist, Volume 251, Issue 5, Page 2799-2817, September 2026.
Summary Arbuscular mycorrhizal fungi (AMF) are widespread plant symbionts that enhance nutrient acquisition and influence ecosystem productivity. Previous chromosome‐level assemblies of the model species Rhizophagus irregularis revealed a two‐compartment genome architecture (active A and repressed B chromatin compartments), yet its conservation across ...
Ken Mugambi, Jordana Oliveira, Franco Magurno, Alessandra Salvioli di Fossalunga, Mara Novero, Luisa Lanfranco, Stefano Ghignone, Gökalp Yildirir, Yan Wang, Paola Bonfante, Nicolas Corradi   +10 more
wiley   +1 more source