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At least 415 records · Page 23

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NASA NTRS2018

A Blueprint for Demonstrating Quantum Supremacy with Superconducting Qubits

Long coherence times and high fidelity control recently achieved in scalable superconducting circuits paved the way for the growing number of experimental studies of many-qubit quantum coherent phenomena in these devices. Albeit full implementation of quantum error correction and fault tolerant quantum computation remains a challenge the near term pre-error correction devices could allow new fundamental experiments despite inevitable accumulation of errors. One such open question foundational for quantum computing is achieving the so called quantum supremacy, an experimental demonstration of a computational task that takes polynomial time on the quantum computer whereas the best classical algorithm would require exponential time and/or resources. It is possible to formulate such a task for a quantum computer consisting of less than a 100 qubits. The computational task we consider is to provide approximate samples from a non-trivial quantum distribution. This is a generalization for the case of superconducting circuits of ideas behind boson sampling protocol for quantum optics introduced by Arkhipov and Aaronson. In this presentation we discuss a proof-of-principle demonstration of such a sampling task on a 9-qubit chain of superconducting gmon qubits developed by Google. We discuss theoretical analysis of the driven evolution of the device resulting in output approximating samples from a uniform distribution in the Hilbert space, a quantum chaotic state. We analyze quantum chaotic characteristics of the output of the circuit and the time required to generate a sufficiently complex quantum distribution. We demonstrate that the classical simulation of the sampling output requires exponential resources by connecting the task of calculating the output amplitudes to the sign problem of the Quantum Monte Carlo method. We also discuss the detailed theoretical modeling required to achieve high fidelity control and calibration of the multi-qubit unitary evolution in the device. We use a novel cross-entropy statistical metric as a figure of merit to verify the output and calibrate the device controls. Finally, we demonstrate the statistics of the wave function amplitudes generated on the 9-gmon chain and verify the quantum chaotic nature of the generated quantum distribution. This verifies the implementation of the quantum supremacy protocol.

Kechedzhi, Kostyantyn↗

DOE OSTI2015

Entropic description of gas hydrate ice/liquid equilibrium via enhanced sampling of coexisting phases

Metastable β ice holds small guest molecules in stable gas hydrates, so its solid/liquid equilibrium is of interest. However, aqueous crystal/liquid transitions are very difficult to simulate. A new MD algorithm generates trajectories in a generalized NPT ensemble and equilibrates states of coexisting phases with a selectable enthalpy. Furthermore, with replicas spanning the range between β ice and liquid water we find the statistical temperature from the enthalpy histograms and characterize the transition by the entropy, introducing a general computational procedure for first-order transitions.

36 MATERIALS SCIENCE↗

DOE OSTI2020

In situ investigation of the deformation behaviors of Fe 20 Co 30 Cr 25 Ni 25 and Fe 20 Co 30 Cr 30 Ni 20 high entropy alloys by high-energy X-ray diffraction

In situ synchrotron-based high-energy X-ray diffraction (HE-XRD) technique was employed to investigate the mechanical behaviors and microstructural evolution of face-centered cubic (FCC) Fe 20 Co 30 Cr 25 Ni 25 and Fe 20 Co 30 Cr 30 Ni 20 high entropy alloys (HEAs) during tensile deformation. Fe 20 Co 30 Cr 30 Ni 20 HEA has a good combination of strength (ultimate tensile strength of 864 ± 35 MPa) and ductility (elongation of 0.627 ± 0.021). The HE-XRD investigation reveals that Fe 20 Co 30 Cr 30 Ni 20 HEA has the transformation-induced plasticity (TRIP) effect, which starts at a critical stress of ~555 MPa. Furthermore, transmission electron microscopy confirmed this deformation-induced new phase is hexagonal-close-packed structured ε-martensite, which follows an orientation relationship of {111} γ //(0001) ε , and (110) γ //[11 2 ¯ 0] ε with the FCC γ matrix. The observation of deformation twins in the deformed samples of the two studied HEAs proves that twinning-induced plasticity (TWIP) effect occurs in both HEAs. The combination of TRIP and TWIP effects lead to the high strength, large ductility and improved strain hardening behavior of Fe 20 Co 30 Cr 30 Ni 20 HEA.

36 MATERIALS SCIENCE↗

DOE OSTI2018

Corrosion Evaluation of CoCrFeMnNi High-Entropy Alloys (HEAs) for Corrosion Protection of Natural Gas Transmission Pipelines

High-entropy alloys (HEAs), are multicomponent alloys composed of at least five elements with compositions of 5-35 atomic % for each element. These alloys are being investigated for corrosion protection of natural gas transmission pipelines by studying their behavior under aqueous acidic conditions. Electrochemical and immersion experiments were carried out in 3.5 weight % NaCl solution at pH 4 and 40°C. Oxygen was purged out from the solution by using CO2 as stripping gas. The electrochemical experiments included potentiodynamic and electrochemical impedance spectroscopy tests, used to calculate corrosion rates. Potentiodynamic polarization curves, including cyclic voltammograms, were used to explain active, active-passive, and passive regions of these alloys and susceptibility to localized corrosion. Surface characterization of the corroded samples were performed using scanning electron microscopy (SEM) and x-ray diffraction (XRD). The results of the immersion and electrochemical testing indicate that some of the HEAs have better corrosion performance than commercial alloys UNS N10276, UNS K03014, and UNS 31600.

03 NATURAL GAS↗

DOE OSTI2014

Room temperature magnetocaloric effect, critical behavior, and magnetoresistance in Na-deficient manganite La{sub 0.8}Na{sub 0.1}MnO{sub 3}

The La{sub 0.8}Na{sub 0.1}MnO{sub 3} oxide was prepared by the solid-state reaction and annealed in air. The X-ray diffraction data reveal that the sample is crystallized in a rhombohedral structure with R3{sup ¯}c space group. Magnetic study shows a second-order magnetic phase transition from ferromagnetic to paramagnetic state at the Curie temperature T{sub C} = 295 K. In addition, the magnetizations as a function of temperature and the magnetic field is used to evaluate the magnetic entropy change ΔS{sub M}. Then, we have deduced that the La{sub 0.8}Na{sub 0.1}MnO{sub 3} oxide has a large magnetocaloric effect at room temperature. Such effect is given by the maximum of the magnetic entropy change ΔS{sub Mmax} = 5.56, and by the Relative cooling power (RCP) factor which is equal to 235 under a magnetic field of 5 T. Moreover, the magnetic field dependence of the magnetic entropy change is used to determine the critical exponents β, γ, and δ which are found to be β = 0.495, γ = 1.083, and δ = 3.18. These values are consistent with the prediction of the mean field theory (β = 0.5, γ = 1, and δ = 3). Above all, the temperature dependence of electrical resistivity shows a metal–insulator transition at T{sub ρ}. The electrical resistivity decrease when we apply a magnetic field giving a magnetoresistance effect in the order of 60% at room temperature.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2017

Enhanced spontaneous DNA twisting/bending fluctuations unveiled by fluorescence lifetime distributions promote mismatch recognition by the Rad4 nucleotide excision repair complex

Rad4/XPC recognizes diverse DNA lesions including ultraviolet-photolesions and carcinogen-DNA adducts, initiating nucleotide excision repair. Studies have suggested that Rad4/XPC senses lesion-induced helix-destabilization to flip out nucleotides from damaged DNA sites. However, characterizing how DNA deformability and/or distortions impact recognition has been challenging. Here, using fluorescence lifetime measurements empowered by a maximum entropy algorithm, we mapped the conformational heterogeneities of artificially destabilized mismatched DNA substrates of varying Rad4-binding specificities. The conformational distributions, as probed by FRET between a cytosine-analog pair exquisitely sensitive to DNA twisting/bending, reveal a direct connection between intrinsic DNA deformability and Rad4 recognition. High-specificity CCC/CCC mismatch, free in solution, sampled a strikingly broad range of conformations from B-DNA-like to highly distorted conformations that resembled those observed with Rad4 bound; the extent of these distortions increased with bound Rad4 and with temperature. Conversely, the non-specific TAT/TAT mismatch had a homogeneous, B-DNA-like conformation. Molecular dynamics simulations also revealed a wide distribution of conformations for CCC/CCC, complementing experimental findings. We propose that intrinsic deformability promotes Rad4 damage recognition, perhaps by stalling a diffusing protein and/or facilitating ‘conformational capture’ of pre-distorted damaged sites. Surprisingly, even mismatched DNA specifically bound to Rad4 remains highly dynamic, a feature that may reflect the versatility of Rad4/XPC to recognize many structurally dissimilar lesions

59 BASIC BIOLOGICAL SCIENCES↗

NASA NTRS2022

Using airborne and DESIS imaging spectroscopy to map plant diversity across the largest contiguous tract of tallgrass prairie on earth

Grassland ecosystems are under threat globally, primarily due to land-use and land-cover changes that have adversely affected their biodiversity. Given the negative ecological impacts of biodiversity loss in grasslands, there is an urgent need for developing an operational biodiversity monitoring system that functions in these ecosystems. In this paper, we assessed the capability of airborne and spaceborne imaging spectroscopy (also known as hyperspectral imaging) to capture plant α-diversity in a large naturally-assembled grassland while considering the impact of common management practices, specifically prescribed fire. We collected a robust in-situ plant diversity data set, including species composition and percent cover from 2500 sampling points with different burn ages, from recently-burned to transitional and pre-prescribed fire at the Joseph H. Williams Tallgrass Prairie Preserve in Oklahoma, USA. We expressed in-situ plant α-diversity using the first three Hill numbers, including species richness (number of observed species in a plant community), exponential Shannon entropy index (hereafter Shannon diversity; effective number of common species, where species are weighed proportional to their percent cover), and inverse Simpson concentration index (hereafter Simpson diversity; effective number of dominant species, where more weight is given to dominant species) at four different plot sizes, including 60 m × 60 m, 120 m × 120 m, 180 m × 180 m, and 240 m × 240 m. We collected full-range airborne hyperspectral data with fine spatial resolution (1 m) and visible and near-infrared spaceborne hyperspectral data from DESIS sensor with coarse spatial resolution (30 m), and used the spectral diversity hypothesis—i.e., that the variability in spectral data is largely driven by plant diversity—to estimate α-diversity remotely. In recently-burned plots and those at the transitional stage, both airborne and spaceborne data were capable of capturing Simpson diversity—a metric that calculates the effective number of dominant species by emphasizing abundant species and discounting rare species—but not species richness or Shannon diversity. Further, neither airborne nor spaceborne hyperspectral data sets were capable of capturing plant α-diversity of 60 m × 60 m or 120 m × 120 m plots. Based on these results, three main findings emerged: (1) management practices influence grassland biodiversity patterns that can be remotely detected, (2) both fine- and coarse-resolution remotely-sensed data can detect the effective number of dominant species (e.g., Simpson diversity), and (3) attention should be given to site-specific plant diversity field data collection to appropriately interpret remote sensing results. Findings of this study indicate the feasibility of estimating Simpson diversity in naturally-assembled grasslands using forthcoming spaceborne imagers such as National Aeronautics and Space Administration's Surface Biology and Geology mission.

Hamed Gholizadeh↗

DOE OSTI2013

ACTIVE GALACTIC NUCLEUS FEEDBACK AND ENTROPY INJECTION IN GALAXY CLUSTER CORES

We make the first estimate of non-gravitational energy profiles in galaxy cluster cores (and beyond) based on observational data. Comparing the observed entropy profiles within r{sub 500}, from the Representative XMM-Newton Cluster Structure Survey to simulated base entropy profiles without feedback from both adaptive mesh refinement (AMR) and smoothed particle hydrodynamic (SPH) non-radiative simulations, we estimate the amount of additional non-gravitational energy, E{sub ICM}, contained in the intracluster medium (ICM), as well as the total energy feedback, E{sub Feedback}, from active galactic nuclei (AGNs; the central AGNs in most cases) into the clusters. The total feedback energy scales with the mean spectroscopic temperature as E{sub Feedback}∝T{sub sp}{sup 2.52±0.08} and E{sub Feedback}∝T{sub sp}{sup 2.17±0.11} for the SPH and AMR baseline profiles. The mean non-gravitational energy per particle within r{sub 500} remaining in the ICM after energy lost during cooling is ε{sub ICM} = 2.8 ± 0.8 keV for the SPH theoretical relation and ε{sub ICM} = 1.7 ± 0.9 keV for the AMR theoretical relation. We use the NRAO/VLA Sky Survey source catalog to determine the radio luminosity, L{sub R} , at 1.4 GHz of the central source(s) of our sample. For T{sub sp} > 3 keV, the E{sub Feedback} correlates with L{sub R} , although with different normalization for cool-core and non-cool-core clusters. We show that AGNs could provide a significant portion of the feedback.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2020

Irradiation effects on Al 0.3 CoCrFeNi and CoCrMnFeNi high-entropy alloys, and 316H stainless steel at 500 °C

To evaluate the potential of high entropy alloys (HEAs) for nuclear applications, two HEAs, Al 0.3 CoCrFeNi and CoCrFeMnNi, and a conventional Type 316H stainless steel (SS) were irradiated with 1 MeV krypton ions at 500 degrees C up to 1 dpa, and examined in-situ with a transmission electron microscope (TEM). After irradiation, a high density of ordered L1 2 nanoparticles was observed in Al 0.3 CoCrFeNi. In contrast, no phase transformation was observed in CoCrFeMnNi and 316H SS. In the thin foil regions of TEM samples, stacking-fault tetrahedra were observed in the HEAs. In the thick foil regions, interstitial dislocation loops were observed for all alloys, and the areal loop density increased linearly with foil thickness. The Al 0.3 CoCrFeNi had the largest loop size (the lowest density), followed by the CoCrFeMnNi and then the 316H SS. The higher loop nucleation rate in the 316H SS was attributed to carbon content. Finally, the degree of irradiation hardening was slightly lower for the HEAs than for the 316H SS, which is a promising sign for the nuclear application of HEAs at high temperatures.

36 MATERIALS SCIENCE↗

NASA NTRS1994

Echo mapping of active galactic nuclei broad-line regions: Fundamental algorithms

We formulate and test a series of algorithms for echo mapping the emission-line regions near active galactic nuclei from measurements of correlated variability in their line and continuum light curves. The linear regularization method (LRM) employs a direct inversion of evenly spaced light-curve data, with a regularization parameter that can be used to control the trade-off between noise and resolution. Matrix formulas express the formal solution as well as its variance and covariance in terms of uncertainties in the measurements. Unlike the maximum-entropy method (MEM), LRM applies to kernels with both positive and negative values, but the results are somewhat limited by ringing effects. A positivity constraint proves effective in controlling the ringing. MEM combines regularization and positivity in a natural way, but similar results are also found using positivity constraints with nonentropic regularization functions. Direct inversions of unevenly sampled light curves require interpolating the noisy data. In this case better results are found by solving for both the continuum light curve and kernel function in a simultaneous fit to the data. Our conclusion is that while echo mapping currently gives ambiguous results, the algorithms are not the limiting factor. Progress depends on efforts to increase the accuracy and completeness of sampling of the observed light curves.

Vio, Roberto↗

DOE OSTI2022

A Computational Framework to Accelerate the Discovery of Perovskites for Solar Thermochemical Hydrogen Production: Identification of Gd Perovskite Oxide Redox Mediators

A high-throughput computational framework to identify novel multinary perovskite redox mediators is presented, and this framework is applied to discover the Gd-containing perovskite oxide compositions Gd 2 BB'O 6 , GdA'B 2 O 6 , and GdA'BB'O 6 that split water. The computational scheme uses a sequence of empirical approaches to evaluate the stabilities, electronic properties, and oxygen vacancy thermodynamics of these materials, including contributions to the enthalpies and entropies of reduction, ΔH TR and ΔS TR . This scheme uses the machine-learned descriptor τ to identify compositions that are likely stable as perovskites, the bond valence method to estimate the magnitude and phase of BO 6 octahedral tilting and provide accurate initial estimates of perovskite geometries, and density functional theory including magnetic- and defect-sampling to predict STCH-relevant properties. Eighty-three promising STCH candidate perovskite oxides down-selected from 4392 Gd-containing compositions are reported, three of which are referred to experimental collaborators for characterization and exhibit STCH activity. Our results demonstrate that the high-throughput computational scheme described herein—which is used to evaluate Gd-containing compositions but can be applied to any multinary perovskite oxide compositional space(s) of interest—accelerates the discovery of novel STCH active redox mediators with reasonable computational expense.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Signature of Many-Body Localization of Phonons in Strongly Disordered Superlattices

Many-body localization (MBL) has attracted significant research attention due to its immunity to thermalization, role in logarithmic entanglement entropy growth, and opportunities to reach exotic quantum orders. However, experimental realization of MBL in solid-state systems has remained challenging. Here we report evidence of a possible phonon MBL phase in disordered GaAs/AlAs superlattices. Through grazing-incidence inelastic X-ray scattering, we observe a strong deviation of the phonon population from equilibrium in disordered samples doped with ErAs nanodots at low temperature, signaling a departure from thermalization. This behavior occurs within finite phonon energy and wavevector windows, suggesting a localization-thermalization crossover. We support our observation by proposing a theoretical model for the effective phonon Hamiltonian in disordered superlattices, and showing that it can be mapped exactly to a disordered 1D Bose-Hubbard model with a known MBL phase. The large on-site repulsion qualitatively explains the experimental findings. Furthermore, our work provides mode-resolved experimental evidence of phonon localization, potentially extending the scope of MBL to disordered solid-state systems.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2011

AVERAGE HEATING RATE OF HOT ATMOSPHERES IN DISTANT CLUSTERS BY RADIO ACTIVE GALACTIC NUCLEUS: EVIDENCE FOR CONTINUOUS ACTIVE GALACTIC NUCLEUS HEATING

We examine atmospheric heating by radio active galactic nuclei (AGNs) in distant X-ray clusters by cross correlating clusters selected from the 400 Square Degree (400SD) X-ray Cluster survey with radio sources in the NRAO VLA Sky Survey. Roughly 30% of the clusters show radio emission above a flux threshold of 3 mJy within a projected radius of 250 kpc. The radio emission is presumably associated with the brightest cluster galaxy. The mechanical jet power for each radio source was determined using scaling relations between radio power and cavity (mechanical) power determined for nearby clusters, groups, and galaxies with hot atmospheres containing X-ray cavities. The average jet power of central radio AGNs is approximately 2 x 10{sup 44} erg s{sup -1}. We find no significant correlation between radio power, and hence mechanical jet power, and the X-ray luminosities of clusters in the redshift range 0.1-0.6. This implies that the mechanical heating rate per particle is higher in lower mass, lower X-ray luminosity clusters. The jet power averaged over the sample corresponds to an atmospheric heating of approximately 0.2 keV per particle within R{sub 500}. Assuming the current AGN heating rate does not evolve but remains constant to redshifts of 2, the heating rate per particle would rise by a factor of two. We find that the energy injected from radio AGNs contribute substantially to the excess entropy in hot atmospheres needed to break self-similarity in cluster scaling relations. The detection frequency of radio AGNs is inconsistent with the presence of strong cooling flows in 400SD clusters, but does not exclude weak cooling flows. It is unclear whether central AGNs in 400SD clusters are maintained by feedback at the base of a cooling flow. Atmospheric heating by radio AGNs may retard the development of strong cooling flows at early epochs.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2018

Multi-point nonequilibrium umbrella sampling and associated fluctuation relations

We describe a simple method of umbrella trajectory sampling for Markov chains. The method allows the estimation of large-deviation rate functions, for path-extensive dynamic observables, for an arbitrary number of models within a certain family. The general relationship between probability distributions of dynamic observables of members of this family is an extended fluctuation relation. When the dynamic observable is chosen to be entropy production, members of this family include the forward Markov chain and its time reverse, whose probability distributions are related by the expected simple fluctuation relation.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2021

Inverse Design of Two-Dimensional Airfoils Using Conditional Generative Models and Surrogate Log-Likelihoods

Abstract This paper shows how to use conditional generative models in two-dimensional (2D) airfoil optimization to probabilistically predict good initialization points within the vicinity of the optima given the input boundary conditions, thus warm starting and accelerating further optimization. We accommodate the possibility of multiple optimal designs corresponding to the same input boundary condition and take this inversion ambiguity into account when designing our prediction framework. To this end, we first employ the conditional formulation of our previous work BézierGAN–Conditional BézierGAN (CBGAN)—as a baseline, then introduce its sibling conditional entropic BézierGAN (CEBGAN), which is based on optimal transport regularized with entropy. Compared with CBGAN, CEBGAN overcomes mode collapse plaguing conventional GANs, improves the average lift-drag (Cl/Cd) efficiency of airfoil predictions from 80.8% of the optimal value to 95.8%, and meanwhile accelerates the training process by 30.7%. Furthermore, we investigate the unique ability of CEBGAN to produce a log-likelihood lower bound that may help select generated samples of higher performance (e.g., aerodynamic performance). In addition, we provide insights into the performance differences between these two models with low-dimensional toy problems and visualizations. These results and the probabilistic formulation of this inverse problem justify the extension of our GAN-based inverse design paradigm to other inverse design problems or broader inverse problems.

Engineering↗

DOE OSTI2024

Solid State Reduction Driven Synthesis of Mn Containing Multi-principal Component Alloys

In recent years, high entropy alloys (HEAs), also known as multi-principal component alloys (MPCAs) have emerged as a new and exciting class of materials. This paper reports on the solid state reduction synthesis of a series of CoFeNiMn-based MPCA compositions, starting from a mixture of the corresponding oxides. One of the aims of the study was to test whether the degree of reduction of MnO, a highly stable oxide, could be enhanced by tailoring the alloy composition. Specifically, the influence of Ni content was studied because Ni exhibits a significant negative enthalpy of mixing with Mn. High purity precursor powders of Co(OH) 2 , Fe 2 O 3 , MnO 2 , and NiO were milled and mixed using standard ceramic processing methods. Here, the nominal sample compositions (assuming complete oxide reduction) were (CoFeMn) x Ni (1-x) , for x = 0, 0.083, 0.166, and 0.25. The oxide samples were subjected to a series of isothermal reduction anneals in flowing 3 pct H 2 –Ar at 1100 °C. The resulting microstructures were characterized using scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The composition of the resulting MPCAs was determined quantitatively using wavelength dispersive spectroscopy (WDS) in the electron microprobe. The study revealed that for each of the initial oxide compositions studied, it was possible to achieve an MPCA with ~ 25 at. pct Mn. These results were found to be consistent with the predictions of a thermodynamic model whereby a negative enthalpy of mixing (ΔH mix ), combined with a contribution from configurational entropy, can offset a positive free energy of reduction (ΔG red ). The incorporation of vibrational entropy into first principles calculations was found to have a significant effect on the predicted crystal structure of the MPCAs.

36 MATERIALS SCIENCE↗

DOE OSTI2015

The generation of 68 Gbps quantum random number by measuring laser phase fluctuations

The speed of a quantum random number generator is essential for practical applications, such as high-speed quantum key distribution systems. Here, we push the speed of a quantum random number generator to 68 Gbps by operating a laser around its threshold level. To achieve the rate, not only high-speed photodetector and high sampling rate are needed but also a very stable interferometer is required. A practical interferometer with active feedback instead of common temperature control is developed to meet the requirement of stability. Phase fluctuations of the laser are measured by the interferometer with a photodetector and then digitalized to raw random numbers with a rate of 80 Gbps. The min-entropy of the raw data is evaluated by modeling the system and is used to quantify the quantum randomness of the raw data. The bias of the raw data caused by other signals, such as classical and detection noises, can be removed by Toeplitz-matrix hashing randomness extraction. The final random numbers can pass through the standard randomness tests. Our demonstration shows that high-speed quantum random number generators are ready for practical usage.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2026

Mechanistic Investigation of Co(II) Extraction by TODGA to Aid Nuclear Forensic Separations

Nuclear forensic (NF) analysis supports law enforcement inquiries by analyzing evidence tainted with radioactive substances. Separation techniques can be used to identify and quantify actinides and fission 15 products in post-detonation (PD) debris. Environmental transition metals, also present in PD residues, have been observed to impact critical isotope extractions. For example, radio stable cobalt (Co), ubiquitous in urban environments, particularly in corrosion-resistant alloys, paint-drying agents, dyes, and pigments, can impact the separation of important actinides and fission products. The presented work aims to elucidate the chemistry Q2 governing Co extraction in samples pertinent to PDNF. Chemistry between Co and N,N,N,‘N’-tetraoctyl diglyco- 20 lamide (TODGA), the ligand present in the commercial chromatographic resin diglycolamide (DGA), were studied via solvent and chromatographic extraction and spectroscopic analyses. These results indicate that a tetrahedral Co(II) species is extracted by TODGA from highly acidic (>5M HCl) solutions via a spontaneous entropy-driven reaction. Furthermore, extraction trends in varied acid concentrations are consistent between solvent extraction and chromatographic extraction methods.

activation product↗