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At least 559 records · Page 31
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on CsMg6Fe by Materials Project

CsMg6Fe crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Cs is bonded in a 12-coordinate geometry to eight Mg and two equivalent Fe atoms. There are a spread of Cs–Mg bond distances ranging from 4.18–4.28 Å. Both Cs–Fe bond lengths are 4.25 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded in a distorted single-bond geometry to one Cs, four Mg, and one Fe atom. There are two shorter (2.99 Å) and two longer (3.09 Å) Mg–Mg bond lengths. The Mg–Fe bond length is 2.63 Å. In the second Mg site, Mg is bonded in a distorted bent 120 degrees geometry to two equivalent Cs, one Mg, and two equivalent Fe atoms. The Mg–Mg bond length is 3.03 Å. Both Mg–Fe bond lengths are 2.87 Å. In the third Mg site, Mg is bonded in a distorted hexagonal planar geometry to six Mg atoms. Both Mg–Mg bond lengths are 3.09 Å. In the fourth Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent Cs and eight Mg atoms. Fe is bonded in a 6-coordinate geometry to two equivalent Cs and six Mg atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CsMg30SiO32 by Materials Project

CsMg30SiO32 is Caswellsilverite-derived structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Cs is bonded to six O atoms to form CsO6 octahedra that share corners with six MgO6 octahedra and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.48 Å) and four longer (2.49 Å) Cs–O bond lengths. There are eight inequivalent Mg sites. In the first Mg site, Mg is bonded to six O atoms to form distorted MgO6 octahedra that share corners with two equivalent CsO6 octahedra, corners with two equivalent MgO6 octahedra, corners with two equivalent SiO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Mg–O bond distances ranging from 1.85–2.48 Å. In the second Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with two equivalent SiO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.12 Å) and two longer (2.37 Å) Mg–O bond lengths. In the third Mg site, Mg is bonded to six O atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Mg–O bond distances ranging from 2.10–2.22 Å. In the fourth Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with two equivalent CsO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (1.87 Å) and four longer (2.24 Å) Mg–O bond lengths. In the fifth Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one CsO6 octahedra, an edgeedge with one SiO6 octahedra, and edges with ten MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–16°. There are four shorter (2.17 Å) and two longer (2.21 Å) Mg–O bond lengths. In the sixth Mg site, Mg is bonded to six O atoms to form a mixture of edge and corner-sharing MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. There are a spread of Mg–O bond distances ranging from 2.16–2.18 Å. In the seventh Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one SiO6 octahedra, and edges with eleven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 1–16°. There are a spread of Mg–O bond distances ranging from 2.15–2.23 Å. In the eighth Mg site, Mg is bonded to six O atoms to form MgO6 octahedra that share corners with six MgO6 octahedra, an edgeedge with one CsO6 octahedra, and edges with eleven MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–15°. There are a spread of Mg–O bond distances ranging from 2.12–2.25 Å. Si is bonded to six O atoms to form SiO6 octahedra that share corners with six MgO6 octahedra and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There is four shorter (1.86 Å) and two longer (1.98 Å) Si–O bond length. There are twelve inequivalent O sites. In the first O site, O is bonded to five Mg and one Si atom to form a mixture of edge and corner-sharing OMg5Si octahedra. The corner-sharing octahedra tilt angles range from 0–5°. In the second O site, O is bonded to six Mg atoms to form OMg6 octahedra that share corners with six OMg5Si octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–6°. In the third O site, O is bonded to one Cs and five Mg atoms to form a mixture of distorted edge and corner-sharing OCsMg5 octahedra. The corner-sharing octahedra tilt angles range from 0–6°. In the fourth O site, O is bonded to six Mg atoms to form OMg6 octahedra that share corners with six equivalent OMg6 octahedra and edges with twelve OMg5Si octahedra. The corner-sharing octahedra tilt angles range from 1–4°. In the fifth O site, O is bonded to five Mg and one Si atom to form a mixture of distorted edge and corner-sharing OMg5Si octahedra. The corner-sharing octahedra tilt angles range from 0–15°. In the sixth O site, O is bonded to one Cs and five Mg atoms to form distorted OCsMg5 octahedra that share corners with six OMg5Si octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–15°. The O–Mg bond length is 1.85 Å. In the seventh O site, O is bonded to one Cs and five Mg atoms to form distorted OCsMg5 octahedra that share corners with six OMg5Si octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–15°. There are a spread of O–Mg bond distances ranging from 1.85–2.25 Å. In the eighth O site, O is bonded to six Mg atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–10°. In the ninth O site, O is bonded to six Mg atoms to form a mixture of edge and corner-sharing OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–10°. There are two shorter (2.15 Å) and two longer (2.17 Å) O–Mg bond lengths. In the tenth O site, O is bonded to six Mg atoms to form OMg6 octahedra that share corners with six OCsMg5 octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–9°. In the eleventh O site, O is bonded to one Cs and five Mg atoms to form distorted OCsMg5 octahedra that share corners with six OMg5Si octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–15°. Both O–Mg bond lengths are 2.25 Å. In the twelfth O site, O is bonded to one Cs and five Mg atoms to form distorted OCsMg5 octahedra that share corners with six OMg5Si octahedra and edges with twelve OMg6 octahedra. The corner-sharing octahedra tilt angles range from 0–15°. There are two shorter (2.21 Å) and two longer (2.25 Å) O–Mg bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CsMg6Ga by Materials Project

CsMg6Ga crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Cs is bonded in a 12-coordinate geometry to eight Mg and two equivalent Ga atoms. There are a spread of Cs–Mg bond distances ranging from 4.06–4.30 Å. Both Cs–Ga bond lengths are 4.07 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded in a distorted single-bond geometry to one Cs, four Mg, and one Ga atom. There are two shorter (3.05 Å) and two longer (3.06 Å) Mg–Mg bond lengths. The Mg–Ga bond length is 2.80 Å. In the second Mg site, Mg is bonded in a 2-coordinate geometry to two equivalent Cs, two Mg, and two equivalent Ga atoms. There are one shorter (3.17 Å) and one longer (3.35 Å) Mg–Mg bond lengths. Both Mg–Ga bond lengths are 2.94 Å. In the third Mg site, Mg is bonded in a 10-coordinate geometry to two equivalent Cs and eight Mg atoms. Both Mg–Mg bond lengths are 3.15 Å. In the fourth Mg site, Mg is bonded in a 8-coordinate geometry to eight Mg atoms. Ga is bonded in a 8-coordinate geometry to two equivalent Cs and six Mg atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CsNaMg6 by Materials Project

CsNaMg6 crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Cs is bonded to two equivalent Na and ten Mg atoms to form CsNa2Mg10 cuboctahedra that share corners with four equivalent NaCs2Mg10 cuboctahedra, corners with six equivalent CsNa2Mg10 cuboctahedra, edges with two equivalent NaCs2Mg10 cuboctahedra, faces with two equivalent CsNa2Mg10 cuboctahedra, and faces with two equivalent NaCs2Mg10 cuboctahedra. Both Cs–Na bond lengths are 3.40 Å. There are a spread of Cs–Mg bond distances ranging from 3.49–3.60 Å. Na is bonded to two equivalent Cs and ten Mg atoms to form NaCs2Mg10 cuboctahedra that share corners with four equivalent CsNa2Mg10 cuboctahedra, corners with six equivalent NaCs2Mg10 cuboctahedra, edges with two equivalent CsNa2Mg10 cuboctahedra, faces with two equivalent CsNa2Mg10 cuboctahedra, and faces with two equivalent NaCs2Mg10 cuboctahedra. There are a spread of Na–Mg bond distances ranging from 3.47–3.55 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded in a 12-coordinate geometry to two equivalent Cs, two equivalent Na, and eight Mg atoms. There are a spread of Mg–Mg bond distances ranging from 3.36–3.52 Å. In the second Mg site, Mg is bonded in a 11-coordinate geometry to two equivalent Cs, two equivalent Na, and three Mg atoms. The Mg–Mg bond length is 3.29 Å. In the third Mg site, Mg is bonded in a 2-coordinate geometry to two equivalent Na and six Mg atoms. Both Mg–Mg bond lengths are 3.40 Å. In the fourth Mg site, Mg is bonded in a 2-coordinate geometry to two equivalent Cs and eight Mg atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CsMg6Si by Materials Project

CsMg6Si crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Cs is bonded in a 12-coordinate geometry to eight Mg and two equivalent Si atoms. There are a spread of Cs–Mg bond distances ranging from 3.66–3.84 Å. Both Cs–Si bond lengths are 3.72 Å. There are four inequivalent Mg sites. In the first Mg site, Mg is bonded in a distorted single-bond geometry to two equivalent Cs, five Mg, and one Si atom. There are a spread of Mg–Mg bond distances ranging from 2.94–3.23 Å. The Mg–Si bond length is 2.78 Å. In the second Mg site, Mg is bonded to six Mg atoms to form distorted face-sharing MgMg6 pentagonal pyramids. There are four shorter (3.17 Å) and two longer (3.35 Å) Mg–Mg bond lengths. In the third Mg site, Mg is bonded in a distorted water-like geometry to one Cs, four Mg, and two equivalent Si atoms. Both Mg–Si bond lengths are 2.70 Å. In the fourth Mg site, Mg is bonded to two equivalent Cs and six Mg atoms to form a mixture of distorted corner and face-sharing MgCs2Mg6 hexagonal bipyramids. Si is bonded in a 8-coordinate geometry to two equivalent Cs and six Mg atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CsCeMg14 by Materials Project

CsMg14Ce crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. Cs is bonded to ten Mg and two equivalent Ce atoms to form CsCe2Mg10 cuboctahedra that share corners with six equivalent CsCe2Mg10 cuboctahedra, corners with twelve MgMg12 cuboctahedra, edges with two equivalent CeCs2Mg10 cuboctahedra, faces with two equivalent MgMg12 cuboctahedra, and faces with two equivalent CeCs2Mg10 cuboctahedra. There are a spread of Cs–Mg bond distances ranging from 3.36–3.53 Å. Both Cs–Ce bond lengths are 3.15 Å. There are seven inequivalent Mg sites. In the first Mg site, Mg is bonded to twelve Mg atoms to form distorted MgMg12 cuboctahedra that share corners with four equivalent CsCe2Mg10 cuboctahedra, corners with six equivalent MgMg12 cuboctahedra, edges with six MgMg12 cuboctahedra, faces with two equivalent CeCs2Mg10 cuboctahedra, and faces with six MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.15–3.47 Å. In the second Mg site, Mg is bonded to twelve Mg atoms to form MgMg12 cuboctahedra that share corners with four equivalent CeCs2Mg10 cuboctahedra, corners with six equivalent MgMg12 cuboctahedra, edges with six MgMg12 cuboctahedra, faces with two equivalent CsCe2Mg10 cuboctahedra, and faces with six MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.17–3.42 Å. In the third Mg site, Mg is bonded in a 12-coordinate geometry to two equivalent Cs, eight Mg, and two equivalent Ce atoms. There are a spread of Mg–Mg bond distances ranging from 3.14–3.52 Å. There are one shorter (3.37 Å) and one longer (3.44 Å) Mg–Ce bond lengths. In the fourth Mg site, Mg is bonded to twelve Mg atoms to form distorted MgMg12 cuboctahedra that share corners with four equivalent CsCe2Mg10 cuboctahedra, corners with four equivalent CeCs2Mg10 cuboctahedra, corners with six equivalent MgMg12 cuboctahedra, edges with six MgMg12 cuboctahedra, and faces with six MgMg12 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.12–3.31 Å. In the fifth Mg site, Mg is bonded in a 12-coordinate geometry to one Cs, ten Mg, and one Ce atom. There are a spread of Mg–Mg bond distances ranging from 3.08–3.56 Å. The Mg–Ce bond length is 3.47 Å. In the sixth Mg site, Mg is bonded in a 12-coordinate geometry to eleven Mg and one Ce atom. Both Mg–Mg bond lengths are 3.16 Å. The Mg–Ce bond length is 3.37 Å. In the seventh Mg site, Mg is bonded in a 12-coordinate geometry to one Cs and eleven Mg atoms. Ce is bonded to two equivalent Cs and ten Mg atoms to form CeCs2Mg10 cuboctahedra that share corners with six equivalent CeCs2Mg10 cuboctahedra, corners with twelve MgMg12 cuboctahedra, edges with two equivalent CsCe2Mg10 cuboctahedra, faces with two equivalent CsCe2Mg10 cuboctahedra, and faces with two equivalent MgMg12 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Establishing a silica gel zone in well annulus and evaluating its performance in blocking vertical water flow

Wells are often constructed for monitoring purposes with relatively long screen lengths (e.g., >10 m). Vertical water flows can occur within the artificial or natural filterpack annulus that surrounds the screened interval, bypassing packer assemblies installed inside the wellbore. Attempts to isolate discrete vertical zones during groundwater sampling are unsuccessful when annular flow occurs and lead to remedy decisions based on biased or incorrect interpretations. Blocking vertical annular water flow and contaminant transport will help obtain more accurate concentrations of contaminants from sampling in targeted depth intervals. The application of silica gels formed from the injected colloidal silica CS suspensions is a novel approach to minimize or prevent movement of vertical movement of groundwater in the surrounding filterpack annulus. In this work, we tested the feasibility of injecting CS suspensions to target locations and developed a modified CS formulation that is injectable and prevents gravity sinking. We studied the distribution and penetration of silica gel at laboratory scale in mock well annulus with surrounding formations. We evaluated the performance of the silica gel in blocking vertical water flow in the annulus and in minimizing chemical transport through the gel zone. CS suspension formulations have been defined that are ready for injection, stay in target locations, and form gel within desired time frames. Injection of CS suspensions achieved uniform distribution in a well annulus filter pack, fully occupied the annulus pore space, and penetrated the formation surrounding the filter packer with a sufficient distance to create a hydraulic annular seal when the injection was applied at a sufficient rate. The depth of penetration into the formation was dependent on the permeability contrast between the filter pack and the surrounding formation. Silica gel that formed in the annulus blocked vertical water flow and stopped the chemical transport through the gel zone. In conclusion, this research reveals that using CS suspension injection and sequential gelation (CS-GEL) is a promising technology for blocking vertical water flow and chemical transport through the filter pack in targeted zones within the annulus of long-screened well systems.

Colloidal silica suspension↗
DOE OSTI2025

Mechanical properties and strengthening mechanisms of cold sprayed Al-Mg alloys

This paper investigates the mechanical properties and strengthening mechanisms of cold sprayed Al-Mg alloys as a function of Mg content. Cold spray (CS) is a solid-state deposition process that can be used as a repair technique for structural components. However, the limited ductility of cold sprayed materials is an unsettled issue in CS community. Herein, reproducible, and significantly increased elongation to failure (∼15%) in as-deposited conditions is reported in CS Al-Mg binary alloys with low Mg content (≤ 2.5 wt%). Furthermore, reducing Mg content down to 2.5 wt% in CS Al-Mg binary alloys demonstrated comparable mechanical strength to its wrought counterparts. Strengthening mechanisms were analyzed in wrought and CS Al-Mg alloys based upon microstructural characteristics, such as grain size, Mg solute concentration, and dislocation density. A quantitative evaluation of yield strength revealed that grain boundary strengthening is predominant in CS Al-Mg alloys as compared with their wrought counterparts. When comparing among CS Al-Mg binary alloys of different compositions, Mg solute concentration, and dislocation density governed mechanical strength. In conclusion, the underlying mechanism for the variation of mechanical properties and strengthening mechanisms is discussed in terms of these microstructural characteristics.

Additive manufacturing↗
DOE OSTI2021

Reducing Surface Recombination Velocity of Methylammonium-Free Mixed-Cation Mixed-Halide Perovskites via Surface Passivation

We control surface recombination in the mixed-cation, mixed-halide perovskite, FA0.83Cs0.17Pb(I0.85Br0.15)3, by passivating nonradiative defects with the polymerizable Lewis base (3-aminopropyl)trimethoxysilane (APTMS). We demonstrate average minority carrier lifetimes >4 µs, nearly single exponential monomolecular photoluminescence decays, and high external photoluminescence quantum efficiencies (>20%, corresponding to ~97% of the maximum theoretical quasi-Fermi-level splitting) at low excitation fluence. We confirm both the composition and valence band edge position of the FA0.83Cs0.17Pb(I0.85Br0.15)3 perovskite using multi-institutional, cross-validated, X-ray photoelectron spectroscopy and UV photoelectron spectroscopy measurements. We extend the APTMS surface passivation to higher bandgap double-cation (FA and Cs) compositions (1.7, 1.75, and 1.8 eV) as well as the widely used triple-cation (FA, MA, and Cs) composition. Finally, we demonstrate that the average surface recombination velocity decreases from ~1000 to ~10 cm/s post APTMS passivation for FA0.83Cs0.17Pb(I0.85Br0.15)3. Our results demonstrate that surface-mediated recombination is the primary nonradiative loss pathway in many methylammonium (MA)-free mixed-cation mixed-halide films with a range of different bandgaps, which is a problem observed for a wide range of perovskite active layers and reactive electrical contacts. Our study also provides insights to develop passivating molecules that help reduce surface recombination in MA-free mixed-cation mixed-halide films and indicates that surface passivation and contact engineering will enable near-theoretical device efficiencies with these materials.

14 SOLAR ENERGY↗
DOE OSTI2025

Data-Driven Mapping of the Cesium Cadmium Bromide Phase Space Utilizing a Soft-Chemistry Approach

Soft-chemistry techniques provide a versatile approach to synthesizing inorganic materials under mild conditions, enabling access to compositions and structures that are challenging to achieve through traditional thermodynamically driven solid-state methods. However, these solution-based routes often result in phase competition, requiring precise control over reaction conditions to achieve selective product formation. While one-variable-at-a-time (OVAT) approaches have traditionally been used for phase selection, data-driven strategies are emerging as more efficient methods for navigating complex synthetic spaces. Ternary metal halides, such as cesium cadmium bromides (Cs–Cd–Br), are of growing interest due to their potential in wide and ultrawide band gap applications. Unlike the well-studied cesium lead halide phases, the compositional diversity and solution-based synthesis of ternary Cs–Cd–Br phases remain largely unexplored. This study systematically investigates the synthetic phase space of the Cs–Cd–Br system by constructing a data-driven phase map. Using a common set of precursors and a standardized experimental procedure, we successfully synthesize all four known Cs–Cd–Br phases—CsCdBr 3 , Cs 2 CdBr 4 , Cs 3 CdBr 5 , and Cs 7 Cd 3 Br 13 —each exhibiting distinct structures, morphologies, and optical properties. Our findings highlight the potential of soft-chemistry methods for expanding the library of ternary metal halides and provide key insights into the thermodynamic and kinetic factors governing phase formation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Driving Force Dependent Photoinduced Charge Transfer Dynamics in Polymer-Wrapped Semiconducting Single-Walled Carbon Nanotubes

Here, we investigate the thermodynamic driving-force dependences of photoinduced charge separation (CS) and subsequent charge transfer dynamics in single-walled carbon nanotube (SWNT)–perylenediimide (PDI) donor–acceptor (D–A) superstructures. Pump–probe spectroscopy reveals that [SWNT (•+)n ]-(PDI –• ) n CS states form on an ∼100 fs time scale following photoexcitation; these dynamics are invariant across an ∼400 mV driving force range, indicating that SWNT hole polaron formation time scales are determined by nanotube lattice and solvent relaxation. These CS states feature SWNT hole polarons adjacent to (geminate) and nearby (nongeminate) PDI radical anions. Analysis of the free energy dependence for charge recombination (CR) of [SWNT •+ ] geminate -(PDI –• ) CS states highlights an ∼2 meV value for D–A electronic coupling (HAB) and ∼0.93 eV for the total reorganization energy (λ T ). A corresponding driving force dependence of the CR dynamics for [SWNT •+ ] nongeminate -(PDI –• ) CS states indicates a diminished H AB value (∼0.6 meV) and a larger λ T (∼1.1 eV), consistent with larger transfer distances. SWNT excitons that persist following photoinduced CS drive photooxidation of PDI –• components of [SWNT (•+)n ]-(PDI –• ) n CS states ( 1 SWNT* + PDI •– → PDI + SWNT •– ); this reaction manifests a significantly reduced λ T value (∼0.67 eV) as the initially prepared SWNT reduced state bears the character of a conduction band injected electron ([SWNT •– ] CB ). This reaction thus gives rise to relaxed, nongeminate SWNT electron and hole polarons on the same nanotube; these polarons react on a 10 2 ps time scale independent of the electronic structure of these SWNT-PDI superstructures.

anions↗
DOE OSTI2020

Discrepancy in the Critical State Void Ratio of Poorly Graded Sand due to Shear Strain Localization

The critical state (CS) concept is a theoretical framework that models the constitutive behavior of soils, including sand and other granular materials. It supports the notion of a unique postfailure state, where the soil ultimately experiences continuous shearing with no change in the plastic volumetric strain. However, the published literature has frequently noted the nonconvergence of sand specimens with different initial densities to a unique CS in the compression plane due to many factors such as specimen fabric, particle morphology, breakage, and grain size distribution. This paper examines the CS for poorly graded (uniform) glass beads and 3 different types of silica sands using 50 conventional triaxial compression (CTC) experiments, 12 oedometer tests, and in situ synchrotron microcomputed tomography (SMT) scans for 10 CTC experiments. The results of the 50 CTC experiments revealed a diffused CS zone in the compression plane, which was further examined using the in situ SMT scans. A thorough three-dimensional image analysis of the SMT scans accurately quantified the evolution of the local void ratio (elocal) versus axial compression within zones of intensive shearing toward the center of the specimen. The evolution of the void ratio was also measured using the entire volume of the specimen (eglobal). At the CS, the elocal/eglobal ratio was assessed to be ~1.25 when a single shear band developed within the scanned specimens and ~1.1-1.15 for specimens that failed via external bulging that was internally manifested by the development of multiple shear bands. This finding suggests that the CS zone in the compression plane can be attributed to the common wrong consideration of eglobal evolution in lieu of elocal within the developing shear bands. Furthermore, the lack of shear band development in uniaxial compression has made the results of the oedometer test reliable in quantifying the CS parameters in the compression plane.

58 GEOSCIENCES↗
DOE OSTI2025

Proteomic characterization of Mycobacterium tuberculosis subjected to carbon starvation

ABSTRACT Mycobacterium tuberculosis(Mtb) is the causative agent of tuberculosis (TB), the leading cause of infectious disease-related deaths worldwide. TB infections present on a spectrum from active to latent disease. In the human host,Mtbfaces hostile environments, such as nutrient deprivation, hypoxia, and low pH. Under these conditions,Mtbcan enter a dormant, but viable, state characterized by a lack of cell replication and increased resistance to antibiotics. DormantMtbposes a major challenge to curing infections and eradicating TB globally. We subjectedMtbmc 2 6020 (ΔlysAand ΔpanCD), a double auxotrophic strain, to carbon starvation (CS), a culture condition that induces growth stasis and mimics environmental conditions associated with dormancyin vivo. We provide a detailed analysis of the proteome in CS compared to replicating samples. We observed extensive proteomic reprogramming, with 36% of identified proteins significantly altered in CS. Many enzymes involved in oxidative phosphorylation and lipid metabolism were retained or more abundant in CS. The cell wall biosynthetic machinery was present in CS, although numerous changes in the abundance of peptidoglycan, arabinogalactan, and mycolic acid biosynthetic enzymes likely result in pronounced remodeling of the cell wall. Many clinically approved anti-TB drugs target cell wall biosynthesis, and we found that these enzymes were largely retained in CS. Lastly, we compared our results to those of other dormancy models and propose that CS produces a physiologically distinct state of stasis compared to hypoxia inMtb. IMPORTANCE Tuberculosis is a devastating human disease that kills over 1.2 million people a year. This disease is caused by the bacterial pathogenMycobacterium tuberculosis(Mtb).Mtbexcels at surviving in the human host by entering a non-replicating, dormant state. The current work investigated the proteomic changes thatMtbundergoes in response to carbon starvation, a culture condition that models dormancy. The authors found broad effects of carbon starvation on the proteome, with the relative abundance of 37% of proteins significantly altered. Protein changes related to cell wall biosynthesis, metabolism, and drug susceptibility are discussed. Proteins associated with a carbon starvation phenotype are identified, and results are compared to other dormancy models, including hypoxia.

Microbiology↗
DOE OSTI2021

Characterization of CST Post-Processing AP-105 Hanford Tank Waste

The primary goal of the Tank Side Cesium Removal (TSCR) system, under development by Washington River Protection Solutions, LLC (WRPS), is to remove entrained solids and 137 Cs from the Hanford tank waste supernate to expedite production of low-activity waste. Ion exchange (IX) testing of 10.9 L of waste from Hanford tank 241-AP-105 (AP-105), performed by Pacific Northwest National Laboratory, used a lead-lag-polish column format, with a bed volume of 10 mL per column, to decontaminate tank waste supernate using crystalline silicotitanate (CST) as the IX media. The AP-105 Cs IX processing test, discussed elsewhere, resulted in a shorter transition zone (i.e., steeper load curve) than those defined by wastes from tanks 241-AP-107 and 241-AW-102.1 The shorter transition zone was indicative of a matrix effect retarding Cs capacity. Therefore, aliquots of spent CST from the lead, lag, and polish columns were subjected to a digestion protocol to quantify analytes retained by the CST and extrapolate the impact on Cs capacity. The spent CST was digested using a combination of 5 M HNO 3 and H 2 O 2 with vigorous heating and stirring. Due to the radiation dose accompanying the 137 Cs on the CST columns, a secondary Cs separation by ammonium molybdophosphate embedded in polyacrylonitrile (AMP-PAN) was performed to separate the 137 Cs from the CST so the samples could be contact-handled for analysis outside of a shielded facility.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2021

Temperature Effect of Cesium Exchange onto Crystalline Silicotitanate in AP-107 and AP-105 Hanford Tank Wastes and Two Simulants

Washington River Protection Solutions, LLC (WRPS) is charged with the development of the Tank Side Cesium Removal (TSCR) system to process Hanford tank waste supernates in preparation for vitrification. In addition to a filtration step, TSCR will remove cesium (Cs) using ion exchange columns filled with crystalline silicotitanate (CST) ion exchange media. CST is produced by Honeywell UOP, LLC. The documented safety analysis (DSA) developed for the TSCR system limits a single column loading to 141,600 Ci 137 Cs. Given a 137 Cs isotopic mass fraction of 20% and the planned CST bed size of 596 L (157.5 gal) in a TSCR column, this equates to 0.10 mmole Cs per g CST (Cs distribution coefficient, K d , 1400 mL/g). Factors that influence Cs uptake by CST include (but are not limited to) (1) CST production (lot-to-lot variations), (2) contact temperature, (3) contact duration, (4) competitors in the tank waste feed, (5) anionic composition of the tank waste feed, and (6) the 137 Cs isotopic mass fraction (differs slightly among tank wastes and decreases with time).

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2023

High-Temperature Creep Behavior of Thin-Walled FeCrAl Alloy Tubes

This report summarizes measured creep properties for FeCrAl alloy C26M measured using subsized specimens machined from prototypic thin-walled tubes. A representative tube fabricated in a previous large batch production effort was machined into dual-gauge axial specimens using electrical-discharge machining. Creep tests, comprising strain-rate jump tests (SRJ), jump stress (JS) and constant-stress (CS) tests, were conducted at temperatures ranging from 600-900ºC to determine creep mechanisms (elucidated from stress exponents) and activation energies to compare with prior data available in the literature at temperatures up to 650ºC. It was found that the results from the SRJ tests indicated that the highest stress exponent of 5.8 occurred at 600ºC, which decreased to the lowest stress exponent of 2.5 at 700ºC. At higher temperatures, the stress exponents increased slightly to a range of 2.9 to 4.3 between 750ºC and 900ºC. The high stress exponent value of 5.8 suggested dislocation glide creep mechanisms dominated creep deformation at 600ºC since high stress values were measured. The low stress exponent of 2.5 at 700ºC suggested diffusional creep mechanisms start to occur that aid in dislocation cross-slip and climb mechanisms. The slightly higher stress exponents of 2.9 to 3.9 may suggest different contributions of creep deformation mechanisms based on diffusional processes associated with Nabarro-Herring and Coble creep and dislocation creep that involve thermally activated cross-slip and climb mechanisms. These deformation mechanisms could have also been affected by the development of recovery and/or recrystallization processes in the microstructure of the C26M2 specimens. From the SJ and single CS tests, two sets of creep activation energies were calculated. The steady state creep values obtained from the SJ tests showed several abnormalities especially with the data at 850ºC. The comparison of the creep activation energies between the data from the SJ and CS tests showed higher creep rates for the SJ tests than the CS tests, indicating microstructure softening occurred in the C26M2 specimens during the SJ tests that led to the higher creep rates at stresses above the initial stress of 10 MPa. For the CS tests, the results showed steady increases in MCR with increasing temperature at each stress. The best linear fit to the MCR values at each stress was with data obtained at 800ºC, 850ºC and 900ºC. The lowest Q c value of 130.8 KJ/mole was observed with the highest stress of 25 MPa. As stress was lowered, the Q c values increased continuously to the highest value of 188.2 KJ/mole at 10 MPa. This trend suggests that the dominant creep mechanism is diffusional based dislocation climb since the decreasing activation energies with increasing stress promotes easier dislocation climb around obstacles. The comparison between the SJ and CS tests indicates that the best type of creep test performed on FeCrAl alloys such as C26M2 is the single CS test.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Cesium Removal from SY-101 Tank Waste Using Crystalline Silicotitanate

The newly operational Tank Side Cesium Removal (TSCR) system removes radioactive cesium-137 ( 137 Cs) and solids from tank waste supernate in the 200 east area of the Hanford site. Efforts to expand the removal capabilities to the 200 west area are underway by a system anticipated to be called the West Area Risk Management (WARM) system. Laboratory-scale ion exchange processing using expected WARM unit operations were conducted to contribute toward Washington River Protection Solutions (WRPS) establishing accurate process flowsheets for the individual feed campaigns planned for the west area supernate pretreatment. This report describes the small-scale ion exchange testing with 8.0 L of filtered supernate from tank 241-SY-101 (referred to as SY-101) at 16 °C (62 °F) to demonstrate processing conditions that would be prototypic of what the WARM system may experience. One of the waste acceptance criteria (WAC) for the Waste Treatment Plant (WTP) Low-Activity Waste Facility is that the waste must contain less than 3.18×10 -5 Ci 137 Cs per mole of Na. For the SY-101 tank waste to meet this criterion, only 0.44% of the influent 137 Cs concentration may be delivered to the WTP; this requires a Cs decontamination factor of 227. Testing with SY-101 matched current TSCR prototypic operations where a lead-lag configuration is used until the lag column reached the WAC limit. Neither the lead nor lag columns reached the WAC, so a polish column was never utilized during this test. Feed was processed at 1.9 bed volumes (BVs) per hour; the flowrate, in terms of contact time with the crystalline silicotitate (CST) bed, matched the current flowrate at TSCR (an expected flowrate to be used at WARM). The lead column only reached 0.09% Cs breakthrough after processing ~1363 BVs of feed. Cesium breakthrough from the lag column was not observed during the entire processing. Table S.1 and Figure S.1 summarize the observed column performance and relevant Cs loading characteristics. Table S.1 and Figure S.1 also summarize the measured SY-101 Cs load performance.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2023

Influence of Mild Chronic Stress and Social Isolation on Acute Ozone-Induced Alterations in Stress Biomarkers and Brain-Region-Specific Gene Expression in Male Wistar–Kyoto Rats

Individuals with psychosocial stress often experience an exaggerated response to air pollutants. Ozone (O 3 ) exposure has been associated with the activation of the neuroendocrine stress-response system. We hypothesized that preexistent mild chronic stress plus social isolation (CS), or social isolation (SI) alone, would exacerbate the acute effects of O 3 exposure on the circulating adrenal-derived stress hormones, and the expression of the genes regulating glucocorticoid stress signaling via an altered stress adaptation in a brain-region-specific manner. Male Wistar–Kyoto rats (5 weeks old) were socially isolated, plus were subjected to either CS (noise, confinement, fear, uncomfortable living, hectic activity, and single housing), SI (single housing only, restricted handling and no enrichment) or no stress (NS; double housing, frequent handling and enrichment provided) for 8 weeks. The rats were then exposed to either air or O 3 (0.8 ppm for 4 h), and the samples were collected immediately after. The indicators of sympathetic and hypothalamic–pituitary axis (HPA) activation (i.e., epinephrine, corticosterone, and lymphopenia) increased with O 3 exposure, but there were no effects from CS or SI, except for the depletion of serum BDNF. CS and SI revealed small changes in brain-region-specific glucocorticoid-signaling-associated markers of gene expression in the air-exposed rats (hypothalamic Nr3c1, Nr3c2 Hsp90aa1, Hspa4 and Cnr1 inhibition in SI; hippocampal HSP90aa1 increase in SI; and inhibition of the bed nucleus of the stria terminalis (BNST) Cnr1 in CS). Gene expression across all brain regions was altered by O 3 , reflective of glucocorticoid signaling effects, such as Fkbp5 in NS, CS and SI. The SI effects on Fkbp5 were greatest for SI in BNST. O 3 increased Cnr2 expression in the hypothalamus and olfactory bulbs of the NS and SI groups. O 3 , in all stress conditions, generally inhibited the expression of Nr3c1 in all brain regions, Nr3c2 in the hippocampus and hypothalamus and Bdnf in the hippocampus. SI, in general, showed slightly greater O 3 -induced changes when compared to NS and CS. Serum metabolomics revealed increased sphingomyelins in the air-exposed SI and O 3 -exposed NS, with underlying SI dampening some of the O 3 -induced changes. These results suggest a potential link between preexistent SI and acute O 3 -induced increases in the circulating adrenal-derived stress hormones and brain-region-specific gene expression changes in glucocorticoid signaling, which may partly underlie the stress dynamic in those with long-term SI.

gene expression↗