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1. Calibration of the carbon isotope composition (δ ¹³ C) of benthic foraminifera: Benthic δ ¹³ C Calibration

   https://doi.org/10.1002/2016PA003072  

   Schmittner, Andreas; Bostock, Helen C.; Cartapanis, Olivier; Curry, William B.; Filipsson, Helena L.; Galbraith, Eric D.; Gottschalk, Julia; Herguera, Juan Carlos; Hoogakker, Babette; Jaccard, Samuel L.; et al (June 2017, Paleoceanography)
2. Temperature Cycling Enables Efficient ¹³ C SABRE-SHEATH Hyperpolarization and Imaging of [1- ¹³ C]-Pyruvate

   https://doi.org/10.1021/jacs.1c09581  

   TomHon, Patrick; Abdulmojeed, Mustapha; Adelabu, Isaiah; Nantogma, Shiraz; Kabir, Mohammad Shah; Lehmkuhl, Sören; Chekmenev, Eduard Y.; Theis, Thomas (January 2022, Journal of the American Chemical Society)
3. “Direct” ¹³ C Hyperpolarization of ¹³ C‐Acetate by MicroTesla NMR Signal Amplification by Reversible Exchange (SABRE)

   https://doi.org/10.1002/anie.201910506  

   Gemeinhardt, Max E.; Limbach, Miranda N.; Gebhardt, Thomas R.; Eriksson, Clark W.; Eriksson, Shannon L.; Lindale, Jacob R.; Goodson, Elysia A.; Warren, Warren S.; Chekmenev, Eduard Y.; Goodson, Boyd M. (November 2019, Angewandte Chemie International Edition)

   Abstract Herein, we demonstrate “direct”¹³C hyperpolarization of¹³C‐acetate via signal amplification by reversible exchange (SABRE). The standard SABRE homogeneous catalyst [Ir‐IMes; [IrCl(COD)(IMes)], (IMes=1,3‐bis(2,4,6‐trimethylphenyl), imidazole‐2‐ylidene; COD=cyclooctadiene)] was first activated in the presence of an auxiliary substrate (pyridine) in alcohol. Following addition of sodium 1‐¹³C‐acetate, parahydrogen bubbling within a microtesla magnetic field (i.e. under conditions of SABRE in shield enables alignment transfer to heteronuclei, SABRE‐SHEATH) resulted in positive enhancements of up to ≈100‐fold in the¹³C NMR signal compared to thermal equilibrium at 9.4 T. The present results are consistent with a mechanism of “direct” transfer of spin order from parahydrogen to¹³C spins of acetate weakly bound to the catalyst, under conditions of fast exchange with respect to the¹³C acetate resonance, but we find that relaxation dynamics at microtesla fields alter the optimal matching from the traditional SABRE‐SHEATH picture. Further development of this approach could lead to new ways to rapidly, cheaply, and simply hyperpolarize a broad range of substrates (e.g. metabolites with carboxyl groups) for various applications, including biomedical NMR and MRI of cellular and in vivo metabolism. 

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4. Order‐Unity ¹³ C Nuclear Polarization of [1‐ ¹³ C]Pyruvate in Seconds and the Interplay of Water and SABRE Enhancement

   https://doi.org/10.1002/cphc.202100839  

   Adelabu, Isaiah; TomHon, Patrick; Kabir, Mohammad_S_H; Nantogma, Shiraz; Abdulmojeed, Mustapha; Mandzhieva, Iuliia; Ettedgui, Jessica; Swenson, Rolf_E; Krishna, Murali_C; Theis, Thomas; et al (December 2021, ChemPhysChem)

   Abstract Signal Amplification By Reversible Exchange in SHield Enabled Alignment Transfer (SABRE‐SHEATH) is investigated to achieve rapid hyperpolarization of¹³C₁spins of [1‐¹³C]pyruvate, using parahydrogen as the source of nuclear spin order. Pyruvate exchange with an iridium polarization transfer complex can be modulated via a sensitive interplay between temperature and co‐ligation of DMSO and H₂O. Order‐unity¹³C (>50 %) polarization of catalyst‐bound [1‐¹³C]pyruvate is achieved in less than 30 s by restricting the chemical exchange of [1‐¹³C]pyruvate at lower temperatures. On the catalyst bound pyruvate, 39 % polarization is measured using a 1.4 T NMR spectrometer, and extrapolated to >50 % at the end of build‐up in situ. The highest measured polarization of a 30‐mM pyruvate sample, including free and bound pyruvate is 13 % when using 20 mM DMSO and 0.5 M water in CD₃OD. Efficient¹³C polarization is also enabled by favorable relaxation dynamics in sub‐microtesla magnetic fields, as indicated by fast polarization buildup rates compared to theT₁spin‐relaxation rates (e. g., ∼0.2 s⁻¹versus ∼0.1 s⁻¹, respectively, for a 6 mM catalyst‐[1‐¹³C]pyruvate sample). Finally, the catalyst‐bound hyperpolarized [1‐¹³C]pyruvate can be released rapidly by cycling the temperature and/or by optimizing the amount of water, paving the way to future biomedical applications of hyperpolarized [1‐¹³C]pyruvate produced via comparatively fast and simple SABRE‐SHEATH‐based approaches. 

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5. Perfect and Defective ¹³ C-Furan-Derived Nanothreads from Modest-Pressure Synthesis Analyzed by ¹³ C NMR

   https://doi.org/10.1021/jacs.1c03671  

   Matsuura, Bryan S.; Huss, Steven; Zheng, Zhaoxi; Yuan, Shichen; Wang, Tao; Chen, Bo; Badding, John V.; Trauner, Dirk; Elacqua, Elizabeth; van Duin, Adri C.; et al (June 2021, Journal of the American Chemical Society)

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