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1. Singlet Oxygen Quenching by Resveratrol Derivatives ^†

   https://doi.org/10.1111/php.13704  

   Monsour, Charlotte G.; Tadle, Abegail C.; Tafolla‐Aguirre, Bliss J.; Lakshmanan, Nidhi; Yoon, Jin Hyeok; Sabio, Rhemrose B.; Selke, Matthias (March 2023, Photochemistry and Photobiology)
2. “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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3. Fine-structure Transitions of Ne ⁺ , Ar ⁺ , Ne ²⁺ , and Ar ²⁺ Induced by Collisions with Atomic Hydrogen

   https://doi.org/10.3847/1538-4357/ad0e77  

   Yan, Pei-Gen; Babb, James F (January 2024, The Astrophysical Journal)

   Abstract We calculate cross sections for fine-structure transitions of Ne⁺, Ar⁺, Ne²⁺, and Ar²⁺in collisions with atomic hydrogen by using quantum-mechanical methods. Relaxation rate coefficients are calculated for temperatures up to 10,000 K. The temperature-dependent critical densities for the relaxation of Ne⁺, Ar⁺, Ne²⁺, and Ar²⁺in collisions with H have been determined and compared to the critical densities for collisions with electrons. The present calculations will be useful for studies utilizing the infrared lines [Neii] 12.8, [Neiii] 15.6, [Neiii] 36.0, [Arii] 6.99, [Ariii] 8.99, and [Ariii] 21.8μm as diagnostics of, for example, planetary nebulae and star formation. 

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4. Selective Capture of Ba ²⁺ , Ni ²⁺ , and Co ²⁺ by a Robust Layered Metal Sulfide

   https://doi.org/10.1021/acs.chemmater.9b04831  

   Gao, Yu-Jie; Sun, Hai-Yan; Li, Ji-Long; Qi, Xing-Hui; Du, Ke-Zhao; Liao, Yi-Yu; Huang, Xiao-Ying; Feng, Mei-Ling; Kanatzidis, Mercouri G. (March 2020, Chemistry of Materials)
5. ² H/ ¹ H variation in microbial lipids is controlled by NADPH metabolism

   https://doi.org/10.1073/pnas.1818372116  

   Wijker, Reto S.; Sessions, Alex L.; Fuhrer, Tobias; Phan, Michelle (June 2019, Proceedings of the National Academy of Sciences)

   null (Ed.)

   The hydrogen-isotopic compositions ( 2 H/ 1 H ratios) of lipids in microbial heterotrophs are known to vary enormously, by at least 40% (400‰) relative. This is particularly surprising, given that most C-bound H in their lipids appear to derive from the growth medium water, rather than from organic substrates, implying that the isotopic fractionation between lipids and water is itself highly variable. Changes in the lipid/water fractionation are also strongly correlated with the type of energy metabolism operating in the host. Because lipids are well preserved in the geologic record, there is thus significant potential for using lipid 2 H/ 1 H ratios to decipher the metabolism of uncultured microorganisms in both modern and ancient ecosystems. But despite over a decade of research, the precise mechanisms underlying this isotopic variability remain unclear. Differences in the kinetic isotope effects (KIEs) accompanying NADP + reduction by dehydrogenases and transhydrogenases have been hypothesized as a plausible mechanism. However, this relationship has been difficult to prove because multiple oxidoreductases affect the NADPH pool simultaneously. Here, we cultured five diverse aerobic heterotrophs, plus five Escherichia coli mutants, and used metabolic flux analysis to show that 2 H/ 1 H fractionations are highly correlated with fluxes through NADP + -reducing and NADPH-balancing reactions. Mass-balance calculations indicate that the full range of 2 H/ 1 H variability in the investigated organisms can be quantitatively explained by varying fluxes, i.e., with constant KIEs for each involved oxidoreductase across all species. This proves that lipid 2 H/ 1 H ratios of heterotrophic microbes are quantitatively related to central metabolism and provides a foundation for interpreting 2 H/ 1 H ratios of environmental lipids and sedimentary hydrocarbons. 

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