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   https://doi.org/10.1039/D4JA00168K  

   Zheng, Xin-Yuan (August 2024, Journal of Analytical Atomic Spectrometry)

   A novel method for extracting small quantities of potassium (K) from highly sodium- and calcium-rich samples for high-precision stable K isotope analysis. 

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2. Stable potassium (K) isotope characteristics at mid-ocean ridge hydrothermal vents and its implications for the global K cycle

   https://doi.org/10.1016/j.epsl.2022.117653  

   Zheng, Xin-Yuan; Beard, Brian L.; Neuman, Mason; Fahnestock, Maria F.; Bryce, Julia G.; Johnson, Clark M. (September 2022, Earth and Planetary Science Letters)
3. High-Temperature Inter-Mineral Potassium Isotope Fractionation: Implications for K–Ca–Ar Chronology

   https://doi.org/10.1021/acsearthspacechem.1c00147  

   Kuhnel, W. Wilson; Jacobsen, Stein B.; Li, Yonghui; Ku, Yaray; Petaev, Michail I.; Huang, Shichun; Wu, Zhongqing; Wang, Kun (October 2021, ACS Earth and Space Chemistry)
4. Fast Exact Computation of the k Most Abundant Isotope Peaks with Layer-Ordered Heaps

   https://doi.org/10.1021/acs.analchem.0c01670  

   Kreitzberg, Patrick; Pennington, Jake; Lucke, Kyle; Serang, Oliver (July 2020, Analytical chemistry)

   null (Ed.)

   Computation of the isotopic distribution of compounds is crucial to applications of mass spectrometry, particularly as machine precision continues to improve. In the past decade, several tools have been created for doing so. In this paper we present a novel algorithm for calculating either the most abundant k isotopologue peaks of a compound or the minimal set of isotopologue peaks which have a combined total abundance of at least p. The algorithm uses Serang’s optimal method of selection on Cartesian products. The method is significantly faster than the state-of-the-art on large compounds (e.g., Titin protein) and on compounds whose elements have many isotopes (e.g., palladium alloys). 

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5. Carboniferous isotope stratigraphy

   https://doi.org/10.1144/SP512-2020-72  

   Chen, Jitao; Chen, Bo; Montañez, Isabel P. (April 2022, Geological Society, London, Special Publications)

   Abstract We present an updated set of Carboniferous Sr, C and O isotope stratigraphies based on the existing literature, given the importance of chemostratigraphy for stratigraphic correlation in the Carboniferous. The Carboniferous⁸⁷Sr/⁸⁶Sr record, constructed using brachiopods and conodonts, exhibits five first-order phases beginning with a rapid decline from a peak value ofc.0.70840 at the Devonian–Carboniferous boundary to a trough (0.70776–0.70771) in the Visean followed by a rise to a plateau (c.0.70827) in the upper Bashkirian. A decline toc.0.70804 follows from the lowermost Gzhelian to the close of the Carboniferous. Contemporaneous carbonate δ¹³C records exhibit considerable variability between materials analysed and by region, although pronounced excursions (e.g. the mid-Tournaisian positive excursion and the end-Kasimovian negative excursion) are present in most records. Bulk carbonate δ¹³C records from South China and Europe, however, are generally consistent with those of brachiopod calcite from North America in terms of both absolute values and trends. Both brachiopod calcite and conodont phosphate δ¹⁸O document large regional variability, confirming that Carboniferous δ¹⁸O records are invalid for precise stratigraphic correlation. Nevertheless, significant positive δ¹⁸O shifts in certain intervals (e.g. mid-Tournaisian and the Mississippian–Pennsylvanian transition) can be used for global correlation. 

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