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1. Solvent Effects in Hyperpolarization of ¹⁵ N Nuclei in [ ¹⁵ N ₃ ]Metronidazole and [ ¹⁵ N ₃ ]Nimorazole Antibiotics via SABRE‐SHEATH**

   https://doi.org/10.1002/anse.202400045  

   Yi, Anna P; Salnikov, Oleg G; Burueva, Dudari B; Chukanov, Nikita V; Chekmenev, Eduard Y; Koptyug, Igor V (August 2024, Analysis & Sensing)

   Abstract Metronidazole and nimorazole are antibiotics of a nitroimidazole group which also may be potentially utilized as hypoxia radiosensitizers for the treatment of cancerous tumors. Hyperpolarization of¹⁵N nuclei in these compounds using SABRE‐SHEATH (Signal Amplification By Reversible Exchange in SHield Enables Alignment Transfer to Heteronuclei) approach provides dramatic enhancement of detection sensitivity of these analytes using magnetic resonance spectroscopy and imaging. Methanol‐d₄is conventionally employed as a solvent in SABRE hyperpolarization process. Herein, we investigate SABRE‐SHEATH hyperpolarization of isotopically labeled [¹⁵N₃]metronidazole and [¹⁵N₃]nimorazole in nondeuterated methanol and ethanol solvents. Optimization of such hyperpolarization parameters as polarization transfer magnetic field, temperature, parahydrogen flow rate and pressure allowed us to obtain an average¹⁵N polarization of up to 7.2–7.4 % for both substrates. The highest¹⁵N polarizations were observed in methanol‐d₄for [¹⁵N₃]metronidazole and in ethanol for [¹⁵N₃]nimorazole. At a clinically relevant magnetic field of 1.4 T the¹⁵N nuclei of these substrates possess long characteristic hyperpolarization lifetimes (T₁) of ca. 1 to ca. 7 min. This study represents a major step toward SABRE in more biocompatible solvents, such as ethanol, and also paves the way for future utilization of these hyperpolarized nitroimidazoles as molecular contrast agents for MRI visualization of tumors. 

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2. Extreme enrichment in atmospheric ¹⁵ N ¹⁵ N

   https://doi.org/10.1126/sciadv.aao6741  

   Yeung, Laurence Y.; Li, Shuning; Kohl, Issaku E.; Haslun, Joshua A.; Ostrom, Nathaniel E.; Hu, Huanting; Fischer, Tobias P.; Schauble, Edwin A.; Young, Edward D. (November 2017, Science Advances)
3. The ⁴¹ Ar(n,y) ⁴² Ar reaction

   https://doi.org/10.1051/epjconf/202328401037  

   Sahoo, R. N.; Paul, M.; Köster, U.; Scott, R.; Tessler, M.; Zylstra, A.; Avila, M. L.; Dickerson, C.; Jayatissa, H.; Kohen, M.S.; et al (January 2023, EPJ Web of Conferences)

   Mattoon, C.M.; Vogt, R.; Escher, J.; Thompson, I. (Ed.)

   The cross-section of the thermal neutron capture⁴¹Ar(n,γ)⁴²Ar(t_1/2=32.9 y) reaction was measured by irradiating a⁴⁰Ar sample at the high-flux reactor of Institut Laue-Langevin (ILL) Grenoble, France. The signature of the two-neutron capture has been observed by measuring the growth curve and identifying the 1524.6 keV γ-lines of the shorter-lived⁴²K(12.4 h) β⁻daughter of⁴²Ar. Our preliminary value of the⁴¹Ar(n,γ)⁴²Ar thermal cross section is 240(80) mb at 25.3 meV. For the first time, direct counting of⁴²Ar was performed using the ultra-high sensitivity technique of noble gas accelerator mass spectrometry (NOGAMS) at Argonne National Laboratory, USA. 

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4. Cross sections for the ⁵⁴ Fe(n, n′) ⁵⁴ Fe and ⁵⁴ Fe(n, p′) ⁵⁴ Mn reactions deduced from the detection of de-excitation γ rays

   https://doi.org/10.1051/epjconf/202532905001  

   Hicks, S F; Pecha, R L; Howard, T J; French, A J; Santonil, Z C; Vanhoy, J R; Ramirez, A_P D; Peters, E E; Liu, S H; Prados-Estevez, F M; et al (January 2025, EPJ Web of Conferences)

   Jentschel, M (Ed.)

   γ-ray production cross sections have been deduced for reactions with incident neutrons having energies from 1.5 - 4.7 MeV. Similar measurements were made on a natural Ti sample to establish an absolute normalization. The resulting γ-ray production cross sections are compared to TENDL and TALYS calculations, as well as data from previous measurements. The models are found to describe the production cross sections for mostγrays observed from⁵⁴Mn and⁵⁴Fe rather well. 

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5. In Situ Quantification of Biological N ₂ Production Using Naturally Occurring ¹⁵ N ¹⁵ N

   https://doi.org/10.1021/acs.est.9b00812  

   Yeung, Laurence Y.; Haslun, Joshua A.; Ostrom, Nathaniel E.; Sun, Tao; Young, Edward D.; van Kessel, Maartje A.; Lücker, Sebastian; Jetten, Mike S. (April 2019, Environmental Science & Technology)