45 results on '"Veronika Mocko"'
Search Results
2. Evaluation of 134Ce as a PET imaging surrogate for antibody drug conjugates incorporating 225Ac
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Tyler A. Bailey, Jennifer N. Wacker, Dahlia D. An, Korey P. Carter, Ryan C. Davis, Veronika Mocko, John Larrabee, Katherine M. Shield, Mila Nhu Lam, Corwin H. Booth, and Rebecca J. Abergel
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Cancer Research ,Molecular Medicine ,Radiology, Nuclear Medicine and imaging - Published
- 2022
3. Production of zirconium-88 via proton irradiation of metallic yttrium and preparation of target for neutron transmission measurements at DICER
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Artem V. Matyskin, Athanasios Stamatopoulos, Ellen M. O’Brien, Brad J. DiGiovine, Veronika Mocko, Michael E. Fassbender, C. Etienne Vermeulen, and Paul E. Koehler
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Multidisciplinary - Abstract
A process for the production of tens to hundreds of GBq amounts of zirconium-88 (88Zr) using proton beams on yttrium was developed. For this purpose, yttrium metal targets (≈20 g) were irradiated in a ~16 to 34 MeV proton beam at a beam current of 100–200 µA at the Los Alamos Isotope Production Facility (IPF). The 88Zr radionuclide was produced and separated from the yttrium targets using hydroxamate resin with an elution yield of 94(5)% (1σ). Liquid DCl solution in D2O was selected as a suitable 88Zr sample matrix due to the high neutron transmission of deuterium compared to hydrogen and an even distribution of 88Zr in the sample matrix. The separated 88Zr was dissolved in DCl and 8 µL of the obtained solution was transferred to a tungsten sample can with a 1.2 mm diameter hole using a syringe and automated filling station inside a hot cell. Neutron transmission of the obtained 88Zr sample was measured at the Device for Indirect Capture Experiments on Radionuclides (DICER).
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- 2023
4. Gamma and Decay Energy Spectroscopy Measurements of Trinitite
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Philip A. Hypes, David J. Mercer, Paul R. J. Saey, Daniel Schmidt, Andrew S. Hoover, Stosh A. Kozimor, Joel N. Ullom, Veronika Mocko, M. P. Croce, and Katrina Koehler
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Nuclear and High Energy Physics ,Materials science ,Nuclear Energy and Engineering ,Decay energy ,Trinitite ,Analytical chemistry ,Detonation ,Gamma spectroscopy ,Condensed Matter Physics ,Spectroscopy ,Article ,Isotopic composition - Abstract
We report gamma ray spectroscopy measurements of trinitite samples and analogous samples obtained from detonation sites in Nevada and Semipalatinsk, as well as in situ measurements of topsoil at the Trinity site. We also report the first isotopic composition measurements of trinitite using the novel forensics technique of decay energy spectroscopy (DES) as a complement to traditional forensics techniques. Our gamma spectroscopy and DES measurements are compared to other published results.
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- 2021
5. Characterizing Extraction Chromatography for Large-Scale Americium-241 Processing
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Stosh A. Kozimor, Sara L. Thiemann, Daniel L. Huber, Benjamin W. Stein, David Dan, Mila Nhu Lam, David B. Kimball, Sara L. Adelman, Veronika Mocko, Jenifer C. Shafer, and Brian T. Arko
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Chromatography ,Scale (ratio) ,Chemistry ,General Chemical Engineering ,Extraction (chemistry) ,chemistry.chemical_element ,Americium ,General Chemistry ,Industrial and Manufacturing Engineering - Published
- 2021
6. Photochemical separation of plutonium from uranium
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Ida M. DiMucci, Harrison D. Root, Zachary R. Jones, Stosh A. Kozimor, Molly M. MacInnes, Jeffrey L. Miller, Veronika Mocko, Warren J. Oldham, and Benjamin W. Stein
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Materials Chemistry ,Metals and Alloys ,Ceramics and Composites ,General Chemistry ,Catalysis ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials - Abstract
Plutonium-based technologies would benefit if chemical hazards for purifying plutonium were reduced. One critical processing step where improvements could be impactful is the adjustment of plutonium oxidation-states during separations. This transformation often requires addition of redox agents. Unfortunately, many of the redox agents used previously cannot be used today because their properties are deemed incompatible with modern day processing facilities and waste stream safety requirements. We demonstrated herein that photochemistry can be used as an alternative to those chemical agents. We observed that (1) Pu
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- 2022
7. Oxidizing Americium(III) with Sodium Bismuthate in Acidic Aqueous Solutions
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Natalie T. Rice, Elodie Dalodière, Sara L. Adelman, Zachary R. Jones, Stosh A. Kozimor, Veronika Mocko, Harrison D. Root, and Benjamin W. Stein
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Inorganic Chemistry ,Physical and Theoretical Chemistry - Abstract
Historic perspectives describing f-elements as being redox "inactive" are fading. Researchers continue to discover new oxidation states that are not as inaccessible as once assumed for actinides and lanthanides. Inspired by those contributions, we studied americium(III) oxidation in aqueous media under air using NaBiO
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- 2022
8. Advancing the Am Extractant Design through the Interplay among Planarity, Preorganization, and Substitution Effects
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Xiaobin Zhang, Sara L. Adelman, Brian T. Arko, Channa R. De Silva, Jing Su, Stosh A. Kozimor, Veronika Mocko, Jenifer C. Shafer, Benjamin W. Stein, Georg Schreckenbach, Enrique R. Batista, and Ping Yang
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Inorganic Chemistry ,Ions ,Americium ,Coordination Complexes ,Physical and Theoretical Chemistry - Abstract
Advancing the field of chemical separations is important for nearly every area of science and technology. Some of the most challenging separations are associated with the americium ion Am(III) for its extraction in the nuclear fuel cycle
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- 2022
9. Introduction to nuclear reactions and the new Device for Indirect Capture Experiments on Radionuclides [Slides]
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Athanasios Stamatopoulos, Paul Koehler, Evelyn Bond, Todd Bredeweg, Aaron Couture, Brad DiGiovine, Scott Essenmacher, Michael Fassbender, Anna Hayes-Sterbenz, August Keksis, Artem Matyskin, Veronika Mocko, Donald Parsons, Gencho Rusev, John Ullmann, and Christiaan Vermeulen
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- 2022
10. Synthesis, solid-state, solution, and theoretical characterization of an 'in-cage' scandium-NOTA complex
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Kelly E. Aldrich, Ivan A. Popov, Harrison D. Root, Enrique R. Batista, Samuel M. Greer, Stosh A. Kozimor, Laura M. Lilley, Maksim Y. Livshits, Veronika Mocko, Michael T. Janicke, Brian L. Scott, Benjamin W. Stein, and Ping Yang
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Inorganic Chemistry ,Heterocyclic Compounds, 1-Ring ,Ligands ,Scandium ,Chelating Agents - Abstract
Developing chelators that strongly and selectively bind rare-earth elements (Sc, Y, La, and lanthanides) represents a longstanding fundamental challenge in inorganic chemistry. Solving these challenges is becoming more important because of increasing use of rare-earth elements in numerous technologies, ranging from paramagnets to luminescent materials. Within this context, we interrogated the complexation chemistry of the scandium(III) (Sc
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- 2022
11. Advancing understanding of actinide(iii) (Ac, Am, Cm) aqueous complexation chemistry†
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Laura M. Lilley, Jennifer N. Wacker, Karah E. Knope, Veronika Mocko, Maryline G. Ferrier, Zachary R. Jones, Frankie D. White, Stosh A. Kozimor, David H. Woen, Maksim Y. Livshits, Benjamin W. Stein, Brian L. Scott, and Elodie Dalodière
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Aqueous solution ,Inorganic chemistry ,General Chemistry ,Actinide ,Inner sphere electron transfer ,Metal ,Acetic acid ,chemistry.chemical_compound ,Chemistry ,chemistry ,visual_art ,Chemical Sciences ,visual_art.visual_art_medium ,Chelation ,Reactivity (chemistry) ,Absorption (chemistry) - Abstract
The positive impact of having access to well-defined starting materials for applied actinide technologies – and for technologies based on other elements – cannot be overstated. Of numerous relevant 5f-element starting materials, those in complexing aqueous media find widespread use. Consider acetic acid/acetate buffered solutions as an example. These solutions provide entry into diverse technologies, from small-scale production of actinide metal to preparing radiolabeled chelates for medical applications. However, like so many aqueous solutions that contain actinides and complexing agents, 5f-element speciation in acetic acid/acetate cocktails is poorly defined. Herein, we address this problem and characterize Ac3+ and Cm3+ speciation as a function of increasing acetic acid/acetate concentrations (0.1 to 15 M, pH = 5.5). Results obtained via X-ray absorption and optical spectroscopy show the aquo ion dominated in dilute acetic acid/acetate solutions (0.1 M). Increasing acetic acid/acetate concentrations to 15 M increased complexation and revealed divergent reactivity between early and late actinides. A neutral Ac(H2O)6(1)(O2CMe)3(1) compound was the major species in solution for the large Ac3+. In contrast, smaller Cm3+ preferred forming an anion. There were approximately four bound O2CMe1− ligands and one to two inner sphere H2O ligands. The conclusion that increasing acetic acid/acetate concentrations increased acetate complexation was corroborated by characterizing (NH4)2M(O2CMe)5 (M = Eu3+, Am3+ and Cm3+) using single crystal X-ray diffraction and optical spectroscopy (absorption, emission, excitation, and excited state lifetime measurements)., Actinide complexation from aqueous acetic acid/acetate buffered solutions is described. The number of water ligands was directly correlated with the acetate concentration and characterized by X-ray absorption and optical spectroscopy.
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- 2021
12. Using molten salts to probe outer-coordination sphere effects on lanthanide(<scp>iii</scp>)/(<scp>ii</scp>) electron-transfer reactions
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Kristen A. Pace, Stosh A. Kozimor, Veronika Mocko, Ping Yang, Jennifer N. Wacker, Francisca R. Rocha, Cecilia Eiroa-Lledo, Molly M. MacInnes, Karah E. Knope, Nickolas H. Anderson, Enrique R. Batista, Ida M. DiMucci, Zachary R. Jones, Bo Li, Maksim Y. Livshits, and Benjamin W. Stein
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Inorganic Chemistry ,Metal ,Lanthanide ,Coordination sphere ,Absorption spectroscopy ,Oxidation state ,Chemistry ,visual_art ,visual_art.visual_art_medium ,Physical chemistry ,Molten salt ,Redox ,Ion - Abstract
Controlling structure and reactivity by manipulating the outer-coordination sphere around a given reagent represents a longstanding challenge in chemistry. Despite advances toward solving this problem, it remains difficult to experimentally interrogate and characterize outer-coordination sphere impact. This work describes an alternative approach that quantifies outer-coordination sphere effects. It shows how molten salt metal chlorides (MCln; M = K, Na, n = 1; M = Ca, n = 2) provided excellent platforms for experimentally characterizing the influence of the outer-coordination sphere cations (Mn+) on redox reactions accessible to lanthanide ions; Ln3+ + e1− → Ln2+ (Ln = Eu, Yb, Sm; e1− = electron). As a representative example, X-ray absorption spectroscopy and cyclic voltammetry results showed that Eu2+ instantaneously formed when Eu3+ dissolved in molten chloride salts that had strongly polarizing cations (like Ca2+ from CaCl2) via the Eu3+ + Cl1− → Eu2+ + ½Cl2 reaction. Conversely, molten salts with less polarizing outer-sphere M1+ cations (e.g., K1+ in KCl) stabilized Ln3+. For instance, the Eu3+/Eu2+ reduction potential was >0.5 V more positive in CaCl2 than in KCl. In accordance with first-principle molecular dynamics (FPMD) simulations, we postulated that hard Mn+ cations (high polarization power) inductively removed electron density from Lnn+ across Ln–Cl⋯Mn+ networks and stabilized electron-rich and low oxidation state Ln2+ ions. Conversely, less polarizing Mn+ cations (like K1+) left electron density on Lnn+ and stabilized electron-deficient and high-oxidation state Ln3+ ions.
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- 2021
13. Characterizing Polyoxovanadate‐Alkoxide Clusters Using Vanadium K‐Edge X‐Ray Absorption Spectroscopy
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Alexander S. Ditter, Samuel M. Greer, Stosh A. Kozimor, Samuel D. Weinstein, Scott R. Daly, Rachel L. Meyer, Feng Li, Veronika Mocko, Gerald T. Seidler, Samantha K. Cary, Benjamin W. Stein, Ellen M. Matson, and Anastasia V. Blake
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X-ray absorption spectroscopy ,Absorption spectroscopy ,010405 organic chemistry ,Organic Chemistry ,Vanadium ,chemistry.chemical_element ,General Chemistry ,Electronic structure ,010402 general chemistry ,01 natural sciences ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,Delocalized electron ,chemistry ,K-edge ,Alkoxide ,Physical chemistry ,Molecule - Abstract
A number of technologies would benefit from developing inorganic compounds and materials with specific electronic and magnetic exchange properties. Unfortunately, designing compounds with these properties is difficult because metal⋅⋅⋅metal coupling schemes are hard to predict and control. Fully characterizing communication between metals in existing compounds that exhibit interesting properties could provide valuable insight and advance those predictive capabilities. One such class of molecules are the series of Lindqvist iron-functionalized and hexavanadium polyoxovanadate-alkoxide clusters, which we characterized here using V K-edge X-ray absorption spectroscopy. Substantial changes in the pre-edge peak intensities were observed that tracked with the V 3d-electron count. The data also suggested substantial delocalization between the vanadium cations. Meanwhile, the FeIII cations were electronically isolated from the polyoxovanadate core.
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- 2020
14. A Solid-State Support for Separating Astatine-211 from Bismuth
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Eva R. Birnbaum, Yawen Li, Andrew C. Akin, David H. Woen, Kevin T. Bennett, Donald K. Hamlin, Veronika Mocko, Eric Dorman, D. Scott Wilbur, Stosh A. Kozimor, Nickolas H. Anderson, Frankie D. White, Elodie Dalodière, Cecilia Eiroa-Lledo, Mark Brugh, Laura M. Lilley, Sara L. Thiemann, Maryline G. Ferrier, and Anastasia V. Blake
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Inorganic Chemistry ,chemistry ,Radiochemistry ,Solid-state ,chemistry.chemical_element ,Physical and Theoretical Chemistry ,Astatine ,Bismuth - Abstract
Increasing access to the short-lived α-emitting radionuclide astatine-211 (211At) has the potential to advance targeted α-therapeutic treatment of disease and to solve challenges facing the medical...
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- 2020
15. Evaluation of
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Tyler A, Bailey, Jennifer N, Wacker, Dahlia D, An, Korey P, Carter, Ryan C, Davis, Veronika, Mocko, John, Larrabee, Katherine M, Shield, Mila Nhu, Lam, Corwin H, Booth, and Rebecca J, Abergel
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Mice ,Immunoconjugates ,Cell Line, Tumor ,Positron-Emission Tomography ,Animals ,Tissue Distribution ,Citrates ,Mice, SCID ,Trastuzumab - Abstract
The in vivo generatorThe in vivo biodistributions of [[These results demonstrate that
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- 2022
16. Rapid activation product separations from fission products and soil matrixes
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Kevin T. Bennett, Susan D. Pacheco, Benjamin T. Manard, Stosh A. Kozimor, Angela C. Olson, Ann R. Schake, Ruilian Wu, and Veronika Mocko
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Radionuclide ,Fission products ,Ion exchange ,Chemistry ,Health, Toxicology and Mutagenesis ,Radiochemistry ,Ion chromatography ,Public Health, Environmental and Occupational Health ,Contamination ,Pollution ,Analytical Chemistry ,Nuclear Energy and Engineering ,Activation product ,Radiology, Nuclear Medicine and imaging ,Spectroscopy ,Neutron activation - Abstract
A rapid method for the separation and qualitative analysis of several neutron activation products (198Au, 192Ir, 72Ga, 51Cr, 191/195m/197Pt, 54Mn, 57Co, and 59Fe) from fission products and soil matrixes has been developed. Analytes were isolated within 20 h using ion exchange chromatography. After separation, the activation products were characterized by γ-spectroscopy and inductively coupled plasma-optical emission spectroscopy. Validation experiments demonstrated versatility of the method, showing that the activation products could be isolated from fresh fission products and other contaminants associated with complex soil matrixes.
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- 2019
17. Large-Scale Production of 119mTe and 119Sb for Radiopharmaceutical Applications
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Scott R. Daly, Kevin T. Bennett, Francois M. Nortier, Sharon E. Bone, Laura M. Lilley, C. Vermeulen, Veronika Mocko, Anastasia V. Blake, Benjamin W. Stein, Eva R. Birnbaum, Sara L. Thiemann, Christopher A. Martinez, Michael E. Fassbender, Maryline G. Ferrier, Jonathan W. Engle, Mark Brugh, Andrew C. Akin, and Stosh A. Kozimor
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010405 organic chemistry ,business.industry ,Process development ,Computer science ,General Chemical Engineering ,Scale (chemistry) ,General Chemistry ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,High flux ,Chemistry ,Production (economics) ,Process engineering ,business ,QD1-999 ,Research Article - Abstract
Radionuclides find widespread use in medical technologies for treating and diagnosing disease. Among successful and emerging radiotherapeutics, 119Sb has unique potential in targeted therapeutic applications for low-energy electron-emitting isotopes. Unfortunately, developing 119Sb-based drugs has been slow in comparison to other radionuclides, primarily due to limited accessibility. Herein is a production method that overcomes this challenge and expands the available time for large-scale distribution and use. Our approach exploits high flux and fluence from high-energy proton sources to produce longer lived 119mTe. This parent isotope slowly decays to 119Sb, which in turn provides access to 119Sb for longer time periods (in comparison to direct 119Sb production routes). We contribute the target design, irradiation conditions, and a rapid procedure for isolating the 119mTe/119Sb pair. To guide process development and to understand why the procedure was successful, we characterized the Te/Sb separation using Te and Sb K-edge X-ray absorption spectroscopy. The procedure provides low-volume aqueous solutions that have high 119mTe—and consequently 119Sb—specific activity in a chemically pure form. This procedure has been demonstrated at large-scale (production-sized, Ci quantities), and the product has potential to meet stringent Food and Drug Administration requirements for a 119mTe/119Sb active pharmaceutical ingredient., A large-scale production method for 119mTe and 119Sb from an Sb target is described, with X-ray absorption spectroscopy measurements providing insight into the success of the chemical separations.
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- 2019
18. (Invited, Digital Presentation) Tuning the Electrodeposition of Actinides in Molten Alkali Halide Salts
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Molly M MacInnes, Kristen A Pace, Ida M DiMucci, Nickolas H Anderson, Benjamin W Stein, Stosh Kozimor, Francisca R Rocha, Zachary R Jones, Veronika Mocko, Enrique R Batista, Cecilia Eiroa-Lledo, Maksim Y Livshits, Jennifer N Wacker, Karah E Knope, and Ping Yang
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Molten salts have found use as solvents in numerous applications including nuclear reactors, batteries, and the extraction and purification of various metals. Unfortunately, understanding of the chemistry of molten salt solutions is limited. In this presentation we explore the use of molten salts as a testbed for understanding both outer and inner coordination sphere effects on dissolved metal ions. The electron transfer reactions available to lanthanides (Eu3+, Sm3+, and Yb3+) and actinides (U3+, U4+, and Th4+) were explored in a series of alkali and alkaline earth halide salts. We present electrochemical data that demonstrate significant shifts in the reduction potentials of these metal ions as a function of the anion and cation identities of the molten salt solvent. We hypothesize that effects on the reduction potential of these metals come from two sources: (1) the primary coordination sphere and (2) the secondary coordination sphere. The influence from the primary coordination sphere is dominated by the degree of covalency in the coordination bonds between the Lnn+ and Ann+ cations and the molten salt anions. The influence of the secondary coordination sphere is dominated by the electron-withdrawing character of the salt cations. EXAFS data and computational results that support these hypotheses are presented. Further, we provide insight into electrodeposition of the An0 metals under these conditions and highlight temperature and molten salt effects that influence these electrodepositions. Specifically, we propose that increased mobility of solid-state atoms at high temperature (> 800°C) influence the properties of electrodeposited metals.
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- 2022
19. Development and characterization of a two-phase cerium yttrium alloy: Effect of heat treatment and composition on microstructure in Ce–Y alloys
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Casey Shoemaker, Jason Cooley, Saryu Fensin, James Valdez, Eric Tegtmeier, Kevin Bohn, Veronika Mocko, Cody Miller, and Carl Osborn
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General Materials Science - Published
- 2022
20. Resonant inelastic X-ray scattering using a miniature dispersive Rowland refocusing spectrometer
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Samantha K. Cary, William M. Holden, Matthew J. Latimer, Alexander S. Ditter, Erik J. Nelson, Veronika Mocko, Gerald T. Seidler, and Stosh A. Kozimor
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Nuclear and High Energy Physics ,RIXS ,Wiggler ,Biophysics ,Optical Physics ,01 natural sciences ,010305 fluids & plasmas ,law.invention ,Optics ,law ,0103 physical sciences ,Emission spectrum ,010306 general physics ,Instrumentation ,Physics ,instrumentation ,X-ray spectroscopy ,Radiation ,Spectrometer ,business.industry ,Condensed Matter Physics ,Research Papers ,Synchrotron ,Resonant inelastic X-ray scattering ,Beamline ,XES ,business ,Emission Spectrometer ,Physical Chemistry (incl. Structural) - Abstract
X-ray absorption spectroscopy (XAS) beamlines worldwide are steadily increasing their emphasis on full photon-in/photon-out spectroscopies, such as resonant inelastic X-ray scattering (RIXS), resonant X-ray emission spectroscopy (RXES) and high energy resolution fluorescence detection XAS (HERFD-XAS). In such cases, each beamline must match the choice of emission spectrometer to the scientific mission of its users. Previous work has recently reported a miniature tender X-ray spectrometer using a dispersive Rowland refocusing (DRR) geometry that functions with high energy resolution even with a large X-ray spot size on the sample [Holden et al. (2017). Rev. Sci. Instrum. 88, 073904]. This instrument has been used in the laboratory in multiple studies of non-resonant X-ray emission spectroscopy using a conventional X-ray tube, though only for preliminary measurements at a low-intensity microfocus synchrotron beamline. This paper reports an extensive study of the performance of a miniature DRR spectrometer at an unfocused wiggler beamline, where the incident monochromatic flux allows for resonant studies which are impossible in the laboratory. The results support the broader use of the present design and also suggest that the DRR method with an unfocused beam could have important applications for materials with low radiation damage thresholds and that would not survive analysis on focused beamlines.
- Published
- 2020
21. Extraction chromatography of
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Mitchell T, Friend, T Gannon, Parker, Tara, Mastren, Veronika, Mocko, Mark, Brugh, Eva R, Birnbaum, and Michael E, Fassbender
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Actinium ,Spectrophotometry, Atomic ,Imidazoles ,Solvents ,Ionic Liquids ,Chromatography, Ion Exchange ,Lanthanoid Series Elements ,Porosity ,Glycolates - Abstract
The alpha-emitter
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- 2020
22. Preparation of an Actinium-228 Generator
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Laura M. Lilley, Benjamin W. Stein, Stosh A. Kozimor, Veronika Mocko, Kelly E. Aldrich, Cecilia Eiroa-Lledo, and Mila Nhu Lam
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Inorganic Chemistry ,Actinium ,Generator (computer programming) ,High specific activity ,Chemistry ,Radiochemistry ,Nuclear spectroscopy ,chemistry.chemical_element ,Physical and Theoretical Chemistry ,Volume concentration - Abstract
Advances in targeted α-therapies have increased the interest in actinium (Ac), whose chemistry is poorly defined due to scarcity and radiological hazards. Challenges associated with characterizing Ac3+ chemistry are magnified by its 5f06d0 electronic configuration, which precludes the use of many spectroscopic methods amenable to small amounts of material and low concentrations (like EPR, UV-vis, fluorescence). In terms of nuclear spectroscopy, many actinium isotopes (225Ac and 227Ac) are equally "unfriendly" because the actinium α-, β-, and γ-emissions are difficult to resolve from the actinium daughters. To address these issues, we developed a method for isolating an actinium isotope (228Ac) whose nuclear properties are well-suited for γ-spectroscopy. This four-step procedure isolates 228Ra from naturally occurring 232Th. The relatively long-lived 228Ra (t1/2 = 5.75(3) years) radioisotope subsequently decays to 228Ac. Because the 228Ac decay rate [t1/2 = 6.15(2) h] is fast, 228Ac rapidly regenerates after being harvested from the 228Ra parent. The resulting 228Ac generator provides frequent and long-term access (of many years) to the spectroscopically "friendly" 228Ac radionuclide. We have demonstrated that the 228Ac product can be routinely "milked" from this generator on a daily basis, in chemically pure form, with high specific activity and in excellent yield (∼95%). Hence, in the same way that developing synthesis routes to new starting materials has advanced coordination chemistry for many metals by broadening access, this 228Ac generator has the potential to broaden actinium access for the inorganic community, facilitating the characterization of actinium chemical behavior.
- Published
- 2020
23. Developing the
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Tyler A, Bailey, Veronika, Mocko, Katherine M, Shield, Dahlia D, An, Andrew C, Akin, Eva R, Birnbaum, Mark, Brugh, Jason C, Cooley, Jonathan W, Engle, Michael E, Fassbender, Stacey S, Gauny, Andrew L, Lakes, Francois M, Nortier, Ellen M, O'Brien, Sara L, Thiemann, Frankie D, White, Christiaan, Vermeulen, Stosh A, Kozimor, and Rebecca J, Abergel
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Lanthanum ,Positron-Emission Tomography ,Abdomen ,Cerium Radioisotopes ,Animals ,Tissue Distribution ,Cerium ,Radiopharmaceuticals ,Oxidation-Reduction - Abstract
Developing targeted α-therapies has the potential to transform how diseases are treated. In these interventions, targeting vectors are labelled with α-emitting radioisotopes that deliver destructive radiation discretely to diseased cells while simultaneously sparing the surrounding healthy tissue. Widespread implementation requires advances in non-invasive imaging technologies that rapidly assay therapeutics. Towards this end, positron emission tomography (PET) imaging has emerged as one of the most informative diagnostic techniques. Unfortunately, many promising α-emitting isotopes such as
- Published
- 2020
24. Advancing Chelation Chemistry for Actinium and Other +3 f-Elements, Am, Cm, and La
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Eva R. Birnbaum, Stosh A. Kozimor, Brian L. Scott, Veronika Mocko, Samantha K. Cary, Ping Yang, Kevin D. John, Amanda Morgenstern, Benjamin W. Stein, Maryline G. Ferrier, Enrique R. Batista, Sharon E. Bone, and Juan S. Lezama Pacheco
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Actinium ,Inorganic chemistry ,Binding pocket ,chemistry.chemical_element ,010402 general chemistry ,Ligands ,01 natural sciences ,Biochemistry ,Catalysis ,Coordination complex ,Colloid and Surface Chemistry ,Organophosphorus Compounds ,Coordination Complexes ,Lanthanum ,Molecule ,Chelation ,Chelating Agents ,chemistry.chemical_classification ,Americium ,Extended X-ray absorption fine structure ,Molecular Structure ,Extramural ,General Chemistry ,0104 chemical sciences ,chemistry ,Curium ,Radiopharmaceuticals - Abstract
A major chemical challenge facing implementation of 225Ac in targeted alpha therapy-an emerging technology that has potential for treatment of disease-is identifying an 225Ac chelator that is compatible with in vivo applications. It is unclear how to tailor a chelator for Ac binding because Ac coordination chemistry is poorly defined. Most Ac chemistry is inferred from radiochemical experiments carried out on microscopic scales. Of the few Ac compounds that have been characterized spectroscopically, success has only been reported for simple inorganic ligands. Toward advancing understanding in Ac chelation chemistry, we have developed a method for characterizing Ac complexes that contain highly complex chelating agents using small quantities (μg) of 227Ac. We successfully characterized the chelation of Ac3+ by DOTP8- using EXAFS, NMR, and DFT techniques. To develop confidence and credibility in the Ac results, comparisons with +3 cations (Am, Cm, and La) that could be handled on the mg scale were carried out. We discovered that all M3+ cations (M = Ac, Am, Cm, La) were completely encapsulated within the binding pocket of the DOTP8- macrocycle. The computational results highlighted the stability of the M(DOTP)5- complexes.
- Published
- 2019
25. Advancing Understanding of the +4 Metal Extractant Thenoyltrifluoroacetonate (TTA–); Synthesis and Structure of MIVTTA4 (MIV = Zr, Hf, Ce, Th, U, Np, Pu) and MIII(TTA)4– (MIII = Ce, Nd, Sm, Yb)
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Samantha K. Cary, Benjamin W. Stein, Maksim Y. Livshits, Brian L. Scott, Stosh A. Kozimor, Veronika Mocko, Jeffrey J. Rack, Justin N. Cross, and Maryline G. Ferrier
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Highly skilled ,010405 organic chemistry ,Extraction (chemistry) ,chemistry.chemical_element ,Actinide ,Uranium ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,Inorganic Chemistry ,Metal ,chemistry.chemical_compound ,chemistry ,visual_art ,visual_art.visual_art_medium ,Physical chemistry ,Physical and Theoretical Chemistry ,Thenoyltrifluoroacetone - Abstract
Thenoyltrifluoroacetone (HTTA)-based extractions represent popular methods for separating microscopic amounts of transuranic actinides (i.e., Np and Pu) from macroscopic actinide matrixes (e.g. bulk uranium). It is well-established that this procedure enables +4 actinides to be selectively removed from +3, + 5, and +6 f-elements. However, even highly skilled and well-trained researchers find this process complicated and (at times) unpredictable. It is difficult to improve the HTTA extraction—or find alternatives—because little is understood about why this separation works. Even the identities of the extracted species are unknown. In addressing this knowledge gap, we report here advances in fundamental understanding of the HTTA-based extraction. This effort included comparatively evaluating HTTA complexation with +4 and +3 metals (MIV = Zr, Hf, Ce, Th, U, Np, and Pu vs MIII = Ce, Nd, Sm, and Yb). We observed +4 metals formed neutral complexes of the general formula MIV(TTA)4. Meanwhile, +3 metals formed an...
- Published
- 2018
26. A series of F-Element chelators; diaza crown ethers functionalized with catecholate binding substituents
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Samantha K. Cary, Eva R. Birnbaum, Benjamin W. Stein, Stosh A. Kozimor, Brian L. Scott, Veronika Mocko, and John M. Berg
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Catechol ,Semiquinone ,010405 organic chemistry ,Chemistry ,Organic Chemistry ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Combinatorial chemistry ,Redox ,0104 chemical sciences ,Inorganic Chemistry ,chemistry.chemical_compound ,Elemental analysis ,Materials Chemistry ,Cluster (physics) ,Physical and Theoretical Chemistry ,Spectroscopy ,Single crystal ,Mannich reaction - Abstract
Reported here is the preparation of azacrown ethers functionalized with catechol groups. The synthetic approach was (1st) novel in that it made use of the Mannich reaction and (2nd) valuable in that it provided an improved synthesis (in terms of practical deployment) of the known N,N′-bis(2,3-dihydroxybenzyl)-4,13-diaza-18-crown-6, H4ChaCha. Moreover, it demonstrated potential application of the synthetic method for accommodating a wide range of catecholate functionalities by using the synthetic strategy to prepare N,N′-bis(2,3-dihydroxy-5-tert-butylbenzyl)-4,13-diaza-18-crown-6 (H4tBu2ChaCha) for the first time. These H4ChaCha and H4tBu2ChaCha macrocycles offer exciting opportunity to expand redox chemistry for the f-elements. As “proof-of-principle,” we isolated the unusual tetrameric cluster [La2(tBuChaCha)2]2 from reactions between H4tBu2ChaCha and La[N(SiMe3)2]3. Characterization of [La2(tBuChaCha)2]2 by elemental analysis, single crystal X-ray diffraction, IR, and UV–vis–NIR spectroscopy suggested that the complex represented a rare example of an f-element semiquinone. It further demonstrated that the combination of La3+ and H4tBu2ChaCha provided access to one-electron oxidation chemistry within redox potential windows that were amenable to mild reaction conditions.
- Published
- 2018
27. The coordination chemistry of CmIII, AmIII, and AcIIIin nitrate solutions: an actinide L3-edge EXAFS study
- Author
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Gerald T. Seidler, Stosh A. Kozimor, Veronika Mocko, Sharon E. Bone, Juan S. Lezama Pacheco, Maryline G. Ferrier, Alexander S. Ditter, Samantha K. Cary, and Benjamin W. Stein
- Subjects
chemistry.chemical_classification ,X-ray absorption spectroscopy ,Aqueous solution ,Extended X-ray absorption fine structure ,Absorption spectroscopy ,010405 organic chemistry ,Chemistry ,Analytical chemistry ,General Chemistry ,Actinide ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,Coordination complex ,chemistry.chemical_compound ,Nitric acid ,Stoichiometry - Abstract
Understanding actinide(III) (AnIII = CmIII, AmIII, AcIII) solution-phase speciation is critical for controlling many actinide processing schemes, ranging from medical applications to reprocessing of spent nuclear fuel. Unfortunately, in comparison to most elements in the periodic table, AnIII speciation is often poorly defined in complexing aqueous solutions and in organic media. This neglect – in large part – is a direct result of the radioactive properties of these elements, which make them difficult to handle and acquire. Herein, we surmounted some of the handling challenges associated with these exotic 5f-elements and characterized CmIII, AmIII, and AcIII using AnIII L3-edge X-ray absorption spectroscopy (XAS) as a function of increasing nitric acid (HNO3) concentration. Our results revealed that actinide aquo ions, An(H2O)x3+ (x = 9.6 ± 0.7, 8.9 ± 0.8, and 10.0 ± 0.9 for CmIII, AmIII, and AcIII), were the dominant species in dilute HNO3 (0.05 M). In concentrated HNO3 (16 M), shell-by-shell fitting of the extended X-ray fine structure (EXAFS) data showed the nitrate complexation increased, such that the average stoichiometries of Cm(NO3)4.1±0.7(H2O)5.7±1.3(1.1±0.2)−, Am(NO3)3.4±0.7(H2O)5.4±0.5(0.4±0.1)−, and Ac(NO3)2.3±1.7(H2O)8.3±5.2(0.7±0.5)+ were observed. Data obtained at the intermediate HNO3 concentration (4 M) were modeled as a linear combination of the 0.05 and 16 M spectra. For all three metals, the intermediate models showed larger contributions from the 0.05 M HNO3 spectra than from the 16 M HNO3 spectra. Additionally, these efforts enabled the Cm–NO3 and Ac–NO3 distances to be measured for the first time. Moreover, the AnIII L3-edge EXAFS results, contribute to the growing body of knowledge associated with CmIII, AmIII, and AcIII coordination chemistry, in particular toward advancing understanding of AnIII solution phase speciation.
- Published
- 2018
28. A series of dithiocarbamates for americium, curium, and californium
- Author
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Brian L. Scott, Shane S. Galley, Samantha K. Cary, Ping Yang, Cayla E. Van Alstine, Stosh A. Kozimor, Frankie D. White, Veronika Mocko, Thomas E. Albrecht-Schmitt, Jing Su, Maryline G. Ferrier, and Enrique R. Batista
- Subjects
Lanthanide ,Materials science ,Series (mathematics) ,Curium ,010405 organic chemistry ,Analytical chemistry ,chemistry.chemical_element ,Californium ,Americium ,Actinide ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,Inorganic Chemistry ,chemistry - Abstract
Characterizing how actinide properties change across the f-element series is critical for improving predictive capabilities and solving many nuclear problems facing our society. Unfortunately, it is difficult to make direct comparisons across the 5f-element series because so little is known about trans-plutonium elements. Results described herein help to address this issue through isolation of An(S2CNEt2)3(N2C12H8) (Am, Cm, and Cf). These findings included the first single crystal X-ray diffraction measurements of Cm-S (mean of 2.86 ± 0.04 Å) and Cf-S (mean of 2.84 ± 0.04 Å) bond distances. Furthermore, they highlight the potential of An(S2CNEt2)3(N2C12H8) for providing a test bed for comparative analyses of actinide versus lanthanide bonding interactions.
- Published
- 2018
29. A holistic approach to the optimization of neutron beam transport at the LANSCE facility
- Author
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D.J. Ballard, Brad DiGiovine, J.S. Marquis, D. Votaw, C. Vermeulen, Hye Young Lee, C. Eiroa-Lledo, A. Georgiadou, Lukas Zavorka, Michal Mocko, Veronika Mocko, and S. A. Kuvin
- Subjects
Physics ,Nuclear and High Energy Physics ,Neutron transport ,Shutter ,Nuclear engineering ,Ray tracing (graphics) ,Neutron ,Spallation ,Neutron radiation ,Instrumentation ,Beam (structure) ,Collimated light - Abstract
An advanced neutron beam collimation system has been developed as part of an effort to optimize neutron beam transport at the Weapons Neutron Research (WNR) Facility [1] , located within the Los Alamos Neutron Science Center (LANSCE). The goal of this work was to develop and demonstrate techniques to tailor neutron delivery in order to provide maximum available flux on sample with a specific beam profile, while simultaneously reducing unwanted background. A holistic approach was taken, upgrading the facility spallation target, facility metrology infrastructure, and flight path shutter insert to support the implementation of this advanced collimation system. Modern instruments and software were employed to conduct facility surveys, characterization of as-built geometry of critical components, 3D ray tracing and neutron transport calculations. Beam images and flux measurements were acquired after installation to evaluate the performance of the collimation system and to demonstrate consistent agreement with MCNP simulations which showed an 87% increase of flux on sample while providing suppression of background neutron impingement on the sample frame by 10 3 .
- Published
- 2021
30. Covalency in Americium(III) Hexachloride
- Author
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Stosh A. Kozimor, Justin N. Cross, Brian L. Scott, Samantha K. Cary, Ping Yang, Enrique R. Batista, Cory J. Windorff, Benjamin W. Stein, William J. Evans, Jing Su, and Veronika Mocko
- Subjects
X-ray absorption spectroscopy ,Americium ,Absorption spectroscopy ,010405 organic chemistry ,Chemistry ,Extramural ,chemistry.chemical_element ,General Chemistry ,Electronic structure ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Catalysis ,0104 chemical sciences ,Colloid and Surface Chemistry ,Chlorides ,Chemical physics ,Computational chemistry ,Mixing (physics) - Abstract
Developing a better understanding of covalency (or orbital mixing) is of fundamental importance. Covalency occupies a central role in directing chemical and physical properties for almost any given compound or material. Hence, the concept of covalency has potential to generate broad and substantial scientific advances, ranging from biological applications to condensed matter physics. Given the importance of orbital mixing combined with the difficultly in measuring covalency, estimating or inferring covalency often leads to fiery debate. Consider the 60-year controversy sparked by Seaborg and co-workers ( Diamond, R. M.; Street, K., Jr.; Seaborg, G. T. J. Am. Chem. Soc. 1954 , 76 , 1461 ) when it was proposed that covalency from 5f-orbitals contributed to the unique behavior of americium in chloride matrixes. Herein, we describe the use of ligand K-edge X-ray absorption spectroscopy (XAS) and electronic structure calculations to quantify the extent of covalent bonding in-arguably-one of the most difficult systems to study, the Am-Cl interaction within AmCl
- Published
- 2017
31. Coordination Chemistry of +3 Actinium
- Author
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Stosh Kozimor, Enrique Batista, Kevin John, Eva Birnbaum, Veronika Mocko, Laura Lilley, Amanda Morgenstern, and Benjamin Stein
- Subjects
Radiological and Ultrasound Technology ,Radiology, Nuclear Medicine and imaging - Published
- 2019
32. Energy-Degeneracy-Driven Covalency in Actinide Bonding
- Author
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Andrew Kerridge, Steven D. Conradson, Sharon E. Bone, Alex S. Ditter, Samantha K. Cary, Marianne P. Wilkerson, Enrique R. Batista, Richard L. Martin, Stefan G. Minasian, Stosh A. Kozimor, Henry S. La Pierre, Nikolas Kaltsoyannis, Kevin S. Boland, Matthias W. Löble, Veronika Mocko, Jason M. Keith, Laura E. Wolfsberg, David K. Shuh, David Clark, J. A. Bradley, Jing Su, Gerald T. Seidler, and Ping Yang
- Subjects
Chemical substance ,Absorption spectroscopy ,010405 organic chemistry ,Chemistry ,Actinide ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Catalysis ,0104 chemical sciences ,Metal ,ResearchInstitutes_Networks_Beacons/dalton_nuclear_institute ,Colloid and Surface Chemistry ,Chemical bond ,Covalent bond ,visual_art ,Chemical Sciences ,visual_art.visual_art_medium ,Physical chemistry ,Dalton Nuclear Institute ,Density functional theory ,Degeneracy (biology) - Abstract
Evaluating the nature of chemical bonding for actinide elements represents one of the most important and long-standing problems in actinide science. We directly address this challenge and contribute a Cl K-edge X-ray absorption spectroscopy and relativistic density functional theory study that quantitatively evaluates An-Cl covalency in AnCl62- (AnIV = Th, U, Np, Pu). The results showed significant mixing between Cl 3p- and AnIV 5f- and 6d-orbitals (t1u*/t2u* and t2 g*/eg *), with the 6d-orbitals showing more pronounced covalent bonding than the 5f-orbitals. Moving from Th to U, Np, and Pu markedly changed the amount of M-Cl orbital mixing, such that AnIV 6d - and Cl 3p-mixing decreased and metal 5f - and Cl 3p-orbital mixing increased across this series.
- Published
- 2018
33. Extraction chromatography of 225Ac and lanthanides on N,N-dioctyldiglycolamic acid /1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide solvent impregnated resin
- Author
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Mitchell T. Friend, Tara Mastren, T. Gannon Parker, Veronika Mocko, Mark Brugh, Michael E. Fassbender, and Eva R. Birnbaum
- Subjects
Lanthanide ,Nuclear fission product ,Chromatography ,010401 analytical chemistry ,Organic Chemistry ,Extraction (chemistry) ,Thorium ,chemistry.chemical_element ,General Medicine ,010402 general chemistry ,01 natural sciences ,Biochemistry ,0104 chemical sciences ,Analytical Chemistry ,chemistry.chemical_compound ,Adsorption ,chemistry ,Solvent impregnated resin ,Ionic liquid ,Imide - Abstract
The alpha-emitter 225Ac (t1/2 = 9.92 d) is currently under development for targeted alpha-particle therapy of cancer, and accelerator production of 225Ac via proton irradiation of thorium targets requires robust separations of 225Ac from chemically similar fission product lanthanides. Additionally, the lanthanide elements represent critical components in modern technologies, and radiolanthanides such as 140Nd (t1/2 = 3.37 d) also have potential application in the field of nuclear medicine. The ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bmim][NTf2]), combined with the diglycolamide extractant, N,N-dioctyldiglycolamic acid (DODGAA), was adsorbed on macroporous resin support to produce a solvent impregnated resin (SIR) that was investigated for separations of 225Ac and lanthanides. The equilibrium distribution coefficients (Kd) of the rare earth elements (Sc(III), Y(III), Ln(III)), 225Ac(III), Th(IV), and U(VI) on the prepared DODGAA/[Bmim][NTf2]-SIR were determined from batch adsorption experiments in HCl and HNO3 media. The DODGAA/[Bmim][NTf2]-SIR exhibited preferential uptake of the heavier lanthanide elements while allowing for the separation of the lighter lanthanides. Column separations utilizing the DODGAA/[Bmim][NTf2]-SIR were effective at separating the lighter lanthanides from each other, and separating 225Ac from a mixture of lanthanides, 213Bi, and 225Ra without the need for additional complexing agents.
- Published
- 2020
34. Ferromagnetic quantum critical point in CePd2P2 with Pd → Ni substitution
- Author
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David Graf, Alexander S. Ditter, Stosh A. Kozimor, Veronika Mocko, Sharon E. Bone, Stefan G. Minasian, W. Potter, You Lai, K. Huang, Thomas E. Albrecht-Schmitt, Yu-Che Chiu, Ryan Baumbach, M. G. Ferrier, Juan S. Lezama-Pacheco, Gerald T. Seidler, and W. L. Nelson
- Subjects
Physics ,Valence (chemistry) ,Absorption spectroscopy ,Condensed matter physics ,chemistry.chemical_element ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Cerium ,chemistry ,Ferromagnetism ,Quantum critical point ,0103 physical sciences ,010306 general physics ,0210 nano-technology ,Ferromagnetic order ,Quantum ,Phase diagram - Abstract
Author(s): Lai, Y; Bone, SE; Minasian, S; Ferrier, MG; Lezama-Pacheco, J; Mocko, V; Ditter, AS; Kozimor, SA; Seidler, GT; Nelson, WL; Chiu, YC; Huang, K; Potter, W; Graf, D; Albrecht-Schmitt, TE; Baumbach, RE | Abstract: An investigation of the structural, thermodynamic, and electronic transport properties of the isoelectronic chemical substitution series Ce(Pd1-xNix)2P2 is reported, where a possible ferromagnetic quantum critical point is uncovered in the temperature-concentration (T-x) phase diagram. This behavior results from the simultaneous contraction of the unit cell volume, which tunes the relative strengths of the Kondo and Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions, and the introduction of disorder through alloying. Near the critical region at xcr≈ 0.7, the rate of contraction of the unit cell volume strengthens, indicating that the cerium f valence crosses over from trivalent to a noninteger value. Consistent with this picture, x-ray absorption spectroscopy measurements reveal that while CePd2P2 has a purely trivalent cerium f state, CeNi2P2 has a small (l10 %) tetravalent contribution. In a broad region around xcr, there is a breakdown of Fermi-liquid temperature dependences, signaling the influence of quantum critical fluctuations and disorder effects. Measurements of clean CePd2P2 furthermore show that applied pressure has an initial effect similar to alloying on the ferromagnetic order. From these results, CePd2P2 emerges as a keystone system to test theories such as the Belitz-Kirkpatrick-Vojta model for ferromagnetic quantum criticality, where distinct behaviors are expected in the dirty and clean limits.
- Published
- 2018
35. Experimental and theoretical study of topology and electronic correlations in PuB4
- Author
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Stosh A. Kozimor, Ross D. McDonald, Laurel Winter, Zhoushen Huang, Eve Bauer, Samantha K. Cary, J. D. Thompson, Hong Chul Choi, Paul H. Tobash, Wei Zhu, Jian-Xin Zhu, Brian L. Scott, Filip Ronning, and Veronika Mocko
- Subjects
Physics ,Wilson loop ,Band gap ,02 engineering and technology ,Electronic structure ,021001 nanoscience & nanotechnology ,Topology ,01 natural sciences ,Heat capacity ,Magnetic susceptibility ,Topological insulator ,0103 physical sciences ,Density of states ,Density functional theory ,010306 general physics ,0210 nano-technology - Abstract
We synthesize single crystals of ${\mathrm{PuB}}_{4}$ using an Al-flux technique. Single-crystal diffraction data provide structural parameters for first-principles density functional theory (DFT) calculations. By computing the density of states, the ${Z}_{2}$ topological invariant using the Wilson loop method, and the surface electronic structure from slab calculations, we find that ${\mathrm{PuB}}_{4}$ is a nonmagnetic strong topological insulator with a band gap of 254 meV. Our magnetic susceptibility, heat capacity, and resistivity measurements are consistent with this analysis, albeit with a smaller gap of 35 meV. DFT plus dynamical mean-field theory calculations show that electronic correlations reduce the size of the band gap, and provide better agreement with the value determined by resistivity. These results demonstrate that ${\mathrm{PuB}}_{4}$ is a promising actinide material to investigate the interplay of electronic correlations and nontrivial topology.
- Published
- 2018
36. The coordination chemistry of Cm
- Author
-
Maryline G, Ferrier, Benjamin W, Stein, Sharon E, Bone, Samantha K, Cary, Alexander S, Ditter, Stosh A, Kozimor, Juan S, Lezama Pacheco, Veronika, Mocko, and Gerald T, Seidler
- Subjects
Chemistry - Abstract
CmIII, AmIII, and AcIII have been characterized by solution L3-edge X-ray absorption spectroscopy as a function of nitric acid concentration. This enabled the first experimental determination of Cm and Ac nitrate distances., Understanding actinide(iii) (AnIII = CmIII, AmIII, AcIII) solution-phase speciation is critical for controlling many actinide processing schemes, ranging from medical applications to reprocessing of spent nuclear fuel. Unfortunately, in comparison to most elements in the periodic table, AnIII speciation is often poorly defined in complexing aqueous solutions and in organic media. This neglect – in large part – is a direct result of the radioactive properties of these elements, which make them difficult to handle and acquire. Herein, we surmounted some of the handling challenges associated with these exotic 5f-elements and characterized CmIII, AmIII, and AcIII using AnIII L3-edge X-ray absorption spectroscopy (XAS) as a function of increasing nitric acid (HNO3) concentration. Our results revealed that actinide aquo ions, An(H2O)x3+ (x = 9.6 ± 0.7, 8.9 ± 0.8, and 10.0 ± 0.9 for CmIII, AmIII, and AcIII), were the dominant species in dilute HNO3 (0.05 M). In concentrated HNO3 (16 M), shell-by-shell fitting of the extended X-ray fine structure (EXAFS) data showed the nitrate complexation increased, such that the average stoichiometries of Cm(NO3)4.1±0.7(H2O)5.7±1.3(1.1±0.2)–, Am(NO3)3.4±0.7(H2O)5.4±0.5(0.4±0.1)–, and Ac(NO3)2.3±1.7(H2O)8.3±5.2(0.7±0.5)+ were observed. Data obtained at the intermediate HNO3 concentration (4 M) were modeled as a linear combination of the 0.05 and 16 M spectra. For all three metals, the intermediate models showed larger contributions from the 0.05 M HNO3 spectra than from the 16 M HNO3 spectra. Additionally, these efforts enabled the Cm–NO3 and Ac–NO3 distances to be measured for the first time. Moreover, the AnIII L3-edge EXAFS results, contribute to the growing body of knowledge associated with CmIII, AmIII, and AcIII coordination chemistry, in particular toward advancing understanding of AnIII solution phase speciation.
- Published
- 2018
37. Advancing Understanding of the +4 Metal Extractant Thenoyltrifluoroacetonate (TTA
- Author
-
Samantha K, Cary, Maksim, Livshits, Justin N, Cross, Maryline G, Ferrier, Veronika, Mocko, Benjamin W, Stein, Stosh A, Kozimor, Brian L, Scott, and Jeffrey J, Rack
- Abstract
Thenoyltrifluoroacetone (HTTA)-based extractions represent popular methods for separating microscopic amounts of transuranic actinides (i.e., Np and Pu) from macroscopic actinide matrixes (e.g. bulk uranium). It is well-established that this procedure enables +4 actinides to be selectively removed from +3, + 5, and +6 f-elements. However, even highly skilled and well-trained researchers find this process complicated and (at times) unpredictable. It is difficult to improve the HTTA extraction-or find alternatives-because little is understood about why this separation works. Even the identities of the extracted species are unknown. In addressing this knowledge gap, we report here advances in fundamental understanding of the HTTA-based extraction. This effort included comparatively evaluating HTTA complexation with +4 and +3 metals (M
- Published
- 2018
38. On buoyancy driven mixing by volumetric microwave energy deposition
- Author
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Malcolm J. Andrews, Veronika Mocko, Farzaneh F. Jebrail, and Adam J. Wachtor
- Subjects
Fluid Flow and Transfer Processes ,Materials science ,Buoyancy ,Volumetric flux ,Mechanical Engineering ,Mixing (process engineering) ,Thermodynamics ,engineering.material ,Condensed Matter Physics ,Thermal expansion ,Physics::Fluid Dynamics ,engineering ,Deposition (phase transition) ,Heat equation ,Inertial confinement fusion ,Microwave - Abstract
Investigation of buoyancy driven mixing by volumetric energy deposition is of particular interest to inertial confinement fusion research. This contribution describes a new microwave facility and an experiment to study buoyancy driven mixing of miscible fluids by volumetric energy deposition. A light weakly-polar fluid initially rested on top of a heavier and higher polarity fluid. As the fluid system was subjected to microwave radiation, less microwave energy was deposited into the weakly-polar fluid than the higher polarity fluid; thus, the bottom fluid was preferentially heated, and its density decreased due to thermal expansion. With continued microwave heating, the density of the bottom fluid dropped below the density of the upper fluid, creating a Rayleigh–Taylor unstable configuration, and, subsequently, buoyancy driven mixing. The miscible pair of toluene and tetrahydrofuran was chosen for the volumetric energy deposition experiments presented. Initially, single fluid microwave heating experiments, for which the source term in the heat equation was varied by variations in the fluid volume, were performed to provide calibration of a mathematical model. The model provided a prediction of the neutral stability point of the system, which facilitated experimental design and understanding. Measurements of the mixing layer width from this two-fluid mixing experiment are compared with results from a self-similar analysis of the governing equations.
- Published
- 2015
- Full Text
- View/download PDF
39. Isolation of 163Ho from dysprosium target material by HPLC for neutrino mass measurements
- Author
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W. A. Taylor, Todd E. Barnhart, Gerd Joachim Kunde, Michael W. Rabin, Francois M. Nortier, Robert J. Nickles, Jonathan W. Engle, Veronika Mocko, Anthony D. Pollington, and Eva R. Birnbaum
- Subjects
Matrix (chemical analysis) ,Aqueous solution ,chemistry ,Isotope ,Radiochemistry ,Dysprosium ,Analytical chemistry ,chemistry.chemical_element ,Fraction (chemistry) ,Physical and Theoretical Chemistry ,Holmium ,High-performance liquid chromatography ,Dissolution - Abstract
The rare earth isotope 163Ho is of interest for neutrino mass measurements. This report describes the isolation of 163Ho from a proton-irradiated dysprosium target and its purification. A Dy metal target was irradiated with 16 MeV protons for 10 h. After target dissolution, 163Ho was separated from the bulk Dy via cation-exchange high performance liquid chromatography using 70 mmol dm –3 α-hydroxyisobutyric acid as the mobile phase. Subsequent purification of the collected Ho fraction was performed to remove the α-hydroxyisobutyrate chelating agent and to concentrate the Ho in a low ionic strength aqueous matrix. The final solution was characterized by MC-ICP-MS to determine the 163Ho/165Ho ratio, 163Ho and the residual Dy content. The HPLC purification process resulted in a decontamination factor 1.4E5 for Dy. The isolated Ho fraction contained 24.8 ± 1.3 ng of 163Ho corresponding to holmium recovery of 72 ± 3%.
- Published
- 2015
40. High-resolution photon spectroscopy with a microwave-multiplexed 4-pixel transition edge sensor array
- Author
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David Schwellenbach, Sanjoy Mukhopadhyay, Craig Kruschwitz, M. P. Croce, Paul Guss, Michael W. Rabin, Veronika Mocko, and Nathan J Hoteling
- Subjects
Physics ,Physics::Instrumentation and Detectors ,010308 nuclear & particles physics ,business.industry ,Analytical chemistry ,01 natural sciences ,Noise (electronics) ,Multiplexer ,Multiplexing ,Particle detector ,Optics ,Modulation ,0103 physical sciences ,Radio frequency ,Transition edge sensor ,010306 general physics ,business ,Microwave - Abstract
We demonstrate very high–resolution photon spectroscopy with a microwave-multiplexed 4-pixel transition edge sensor (TES) array. The readout circuit consists of superconducting microwave resonators coupled to radio frequency superconducting-quantum-interference devices (RF-SQUIDs) and transduces changes in input current to changes in phase of a microwave signal. We used a flux-ramp modulation to linearize the response and avoid low-frequency noise. The result is a very high-resolution photon spectroscopy with a microwave-multiplexed 4-pixel transition edge sensor array. We performed and validated a small-scale demonstration and test of all the components of our concept system, which encompassed microcalorimetry, microwave multiplexing, RF-SQUIDs, and software-defined radio (SDR). We shall display data we acquired in the first simultaneous combination of all key innovations in a 4-pixel demonstration, including microcalorimetry, microwave multiplexing, RF-SQUIDs, and SDR. We present the energy spectrum of a gadolinium-153 ( 153 Gd) source we measured using our 4-pixel TES array and the RF-SQUID multiplexer. For each pixel, one can observe the two 97.4 and 103.2 keV photopeaks. We measured the 153 Gd photon source with an achieved energy resolution of 70 eV, full width half maximum (FWHM) at 100 keV, and an equivalent readout system noise of 90 pA/pHz at the TES. This demonstration establishes a path for the readout of cryogenic x-ray and gamma ray sensor arrays with more elements and spectral resolving powers. We believe this project has improved capabilities and substantively advanced the science useful for missions such as nuclear forensics, emergency response, and treaty verification through the explored TES developments.
- Published
- 2017
41. Coordination Chemistry of +3 Actinium
- Author
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Kevin D. John, Benjamin W. Stein, Amanda Morgenstern, Laura M. Lilley, Veronika Mocko, Enrique R. Batista, Stosh A. Kozimor, and Eva R. Birnbaum
- Subjects
chemistry.chemical_classification ,Actinium ,Radiological and Ultrasound Technology ,chemistry ,Computational chemistry ,chemistry.chemical_element ,Radiology, Nuclear Medicine and imaging ,Coordination complex - Published
- 2019
42. Sensor and Method Development for Analysis of Alpha- and Beta-Decaying Radioisotopes Embedded InsideMicrocalorimeter Detectors
- Author
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Nina R. Weisse-Bernstein, Laura E. Wolfsberg, Gerd Joachim Kunde, Douglas A. Bennett, Evelyn M. Bond, Michael W. Rabin, M. P. Croce, Joel N. Ullom, Veronika Mocko, Andrew S. Hoover, James P. Hays-Wehle, and Daniel Schmidt
- Subjects
Physics ,Nuclear reaction ,Isotope ,Q value ,Nuclear forensics ,Detector ,Actinide ,Condensed Matter Physics ,Spectral line ,Electronic, Optical and Magnetic Materials ,Nuclear physics ,Beta particle ,Electrical and Electronic Engineering ,Atomic physics - Abstract
We discuss sensor and method development for the analysis of alphaand beta-decaying radioisotopes encapsulated within superconducting transition-edge sensor microcalorimeter absorbers. For alpha-decaying isotopes, e.g., 238 Pu, 241 Am, and 210 Po, this is a measurement of the total nuclear reaction energy (Q) and the spectra consist of sharp, narrow peaks. The primary peak is at the Q value, with secondary peaks corresponding to gamma-ray-escape peaks. In contrast, for beta-decaying isotopes, e.g., 241 Pu, the spectrum is a low energy continuum ending at E=Q. We are developing transition edge-sensor (TES) microcalorimeters to measure these spectra simultaneously in a single sample, hence allowing quantitative analysis of all Pu isotopes from 238 to 242. We have developed and used TES microcalorimeter detectors for this purpose, and it represents a new quantitative analysis tool for nuclear forensics and safeguards. Due to the high efficiency of the embedded source geometry, measurement times can be minimized. The high dynamic range of our sensors creates the opportunity to measure the relatively low energy beta-decay spectrum of 241 Pu (Q = 20.78 keV) simultaneously with the Q ~ 5-6 MeV of alpha-decaying actinides. Finally, the technique could also be effective for determining the time since chemical purification of Pu using the 241 Pu/ 241 Am isotopic ratio via simultaneous measurement of the low-energy 241 Pu beta particles and the high-energy 241 Am Q-value.
- Published
- 2015
43. Development of holmium-163 electron-capture spectroscopy with transition-edge sensors
- Author
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Daniel Schmidt, Andrew S. Hoover, W. A. Taylor, Daniel S. Swetz, Evelyn M. Bond, Nina R. Weisse-Bernstein, Robert J. Nickles, Jonathan W. Engle, Gerd Joachim Kunde, M. P. Croce, Todd E. Barnhart, James P. Hays-Wehle, Michael W. Rabin, Anthony D. Pollington, Francois M. Nortier, Laura E. Wolfsberg, Veronika Mocko, Joel N. Ullom, and Eva R. Birnbaum
- Subjects
Physics ,Physics - Instrumentation and Detectors ,Isotope ,010308 nuclear & particles physics ,Electron capture ,Physics::Instrumentation and Detectors ,FOS: Physical sciences ,Instrumentation and Detectors (physics.ins-det) ,Radiation ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Nuclear physics ,Decay energy ,0103 physical sciences ,General Materials Science ,Neutrino ,Nuclear Experiment (nucl-ex) ,010306 general physics ,Spectroscopy ,Electron neutrino ,Nuclear Experiment ,Radioactive decay - Abstract
Calorimetric decay energy spectroscopy of electron-capture-decaying isotopes is a promising method to achieve the sensitivity required for electron neutrino mass measurement. The very low total nuclear decay energy (QEC < 3 keV) and short half-life (4570 y) of 163Ho make it attractive for high-precision electron capture spectroscopy (ECS) near the kinematic endpoint, where the neutrino momentum goes to zero. In the ECS approach, an electron-capture-decaying isotope is embedded inside a microcalorimeter designed to capture and measure the energy of all the decay radiation except that of the escaping neutrino. We have developed a complete process for proton-irradiation-based isotope production, isolation, and purification of 163Ho. We have developed transition-edge sensors for this measurement and methods for incorporating 163Ho into high-resolution microcalorimeters, and have measured the electron-capture spectrum of 163Ho. We present our work in these areas and discuss the measured spectrum and its comparison to current theory., Updated with corrected notation for atomic states
- Published
- 2015
44. CINT User Proposal - Description of Proposed Research
- Author
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Nina R. Weisse-Bernstein, M. P. Croce, and Veronika Mocko
- Subjects
Computer science ,Programming language ,computer.software_genre ,computer ,CINT - Published
- 2014
45. 6‐Hydroxydopamine treatment depletes norepinephrine but does not reduce other markers of sympathetic neurons in the heart
- Author
-
Erica A. Wehrwein, Martin Novotny, Veronika Mocko, Gregory M Swain, Joshua D Mastenbrook, Mohammad Esfahanian, Lindsay M. Parker, David L. Kreulen, and Anna A Wright
- Subjects
medicine.medical_specialty ,Hydroxydopamine ,business.industry ,Biochemistry ,Norepinephrine (medication) ,Endocrinology ,Internal medicine ,Anesthesia ,Genetics ,medicine ,business ,Molecular Biology ,Biotechnology ,medicine.drug - Published
- 2007
Catalog
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