@article {35953,
	title = {The effects of aminium and ammonium cations on the ice nucleation activity of K-feldspar},
	journal = {JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES},
	volume = {128},
	year = {2023},
	month = {DEC 2023},
	pages = {e2023JD039971},
	abstract = {<p>Mineral dust is one of the most abundant types of ice nucleating particles in the atmosphere. During atmospheric transport, mineral dust particles can become coated with inorganic and organic solutes, which can impact their ice nucleation activity. Aminium cations formed from amines are one type of organic solute that can coat mineral dust particles in the atmosphere, but their effects on the ice nucleation activity of mineral dust have not been studied. We investigated the effects of primary, secondary, and tertiary aminium cations with methyl and ethyl groups, as well as ammonium cations, on the ice nucleation activity of K-feldspar, an important type of mineral dust, in the immersion freezing mode at low cation concentrations (0.2\&ndash;20\&nbsp;mM) using a droplet-freezing apparatus. Ammonium cations substantially increased the ice nucleation activity of K-feldspar, consistent with previous studies. In contrast, primary aminium cations significantly reduced K-feldspar ice nucleation activity, and secondary and tertiary aminium cations had no significant effect (the effect was less than the uncertainty of our measurements). Our combined results are consistent with the following mechanisms: ammonium cations undergo ion exchange with K-feldspar, providing exposed N\&ndash;H groups for hydrogen bonding with ice; primary aminium cations undergo ion exchange with K-feldspar, exposing a hydrophobic tail that is not effective at nucleating ice; secondary and tertiary aminium cations do not undergo ion exchange with K-feldspar due to steric effects caused by the multiple hydrophobic groups on the cation.</p>},
	keywords = {aminium, ammonium, ice nucleation, Ion exchange, MINERAL DUST},
	doi = {10.1029/2023JD039971},
	url = {https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2023JD039971},
	author = {Chen, L. and Worthy, S. E. and Gu, W. and Bertram, A. K. and Tang, M.}
}
@article {RADCHENKO201555,
	title = {Application of ion exchange and extraction chromatography to the separation of actinium from proton-irradiated thorium metal for analytical purposes},
	journal = {Journal of Chromatography A},
	volume = {1380},
	year = {2015},
	pages = {55 - 63},
	abstract = {Actinium-225 (t1/2=9.92d) is an α-emitting radionuclide with nuclear properties well-suited for use in targeted alpha therapy (TAT), a powerful treatment method for malignant tumors. Actinium-225 can also be utilized as a generator for 213Bi (t1/2 45.6min), which is another valuable candidate for TAT. Actinium-225 can be produced via proton irradiation of thorium metal; however, long-lived 227Ac (t1/2=21.8a, 99\% β-, 1\% α) is co-produced during this process and will impact the quality of the final product. Thus, accurate assays are needed to determine the 225Ac/227Ac ratio, which is dependent on beam energy, irradiation time and target design. Accurate actinium assays, in turn, require efficient separation of actinium isotopes from both the Th matrix and highly radioactive activation by-products, especially radiolanthanides formed from proton-induced fission. In this study, we introduce a novel, selective chromatographic technique for the recovery and purification of actinium isotopes from irradiated Th matrices. A two-step sequence of cation exchange and extraction chromatography was implemented. Radiolanthanides were quantitatively removed from Ac, and no non-Ac radionuclidic impurities were detected in the final Ac fraction. An 225Ac spike added prior to separation was recovered at >=98\%, and Ac decontamination from Th was found to be >=106. The purified actinium fraction allowed for highly accurate 227Ac determination at analytical scales, i.e., at 227Ac activities of 1{\textendash}100kBq (27nCi to 2.7μCi).},
	keywords = {Actinium isotopes, Extraction chromatography, Ion exchange, Lanthanide separation, Thorium chelation, Thorium metal},
	issn = {0021-9673},
	doi = {https://doi.org/10.1016/j.chroma.2014.12.045},
	url = {http://www.sciencedirect.com/science/article/pii/S0021967314019645},
	author = {V. Radchenko and J.W. Engle and J.J. Wilson and J.R. Maassen and F.M. Nortier and W.A. Taylor and E.R. Birnbaum and L.A. Hudston and K.D. John and M.E. Fassbender}
}
