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At least 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on AcNb3 by Materials Project

AcNb3 is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Ac is bonded in a distorted body-centered cubic geometry to fourteen Nb atoms. There are eight shorter (3.06 Å) and six longer (3.53 Å) Ac–Nb bond lengths. There are two inequivalent Nb sites. In the first Nb site, Nb is bonded to four equivalent Ac and four equivalent Nb atoms to form a mixture of distorted face, edge, and corner-sharing NbAc4Nb4 tetrahedra. All Nb–Nb bond lengths are 3.06 Å. In the second Nb site, Nb is bonded in a 8-coordinate geometry to six equivalent Ac and eight equivalent Nb atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AcCe3 by Materials Project

AcCe3 is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ac is bonded to twelve Ce atoms to form AcCe12 cuboctahedra that share corners with four equivalent AcCe12 cuboctahedra, corners with eight equivalent CeAc4Ce8 cuboctahedra, edges with eight equivalent AcCe12 cuboctahedra, edges with sixteen equivalent CeAc4Ce8 cuboctahedra, faces with four equivalent AcCe12 cuboctahedra, and faces with fourteen CeAc4Ce8 cuboctahedra. There are four shorter (3.53 Å) and eight longer (3.54 Å) Ac–Ce bond lengths. There are two inequivalent Ce sites. In the first Ce site, Ce is bonded to four equivalent Ac and eight Ce atoms to form CeAc4Ce8 cuboctahedra that share corners with twelve equivalent CeAc4Ce8 cuboctahedra, edges with eight equivalent AcCe12 cuboctahedra, edges with sixteen CeAc4Ce8 cuboctahedra, faces with four equivalent AcCe12 cuboctahedra, and faces with fourteen CeAc4Ce8 cuboctahedra. There are four shorter (3.53 Å) and four longer (3.54 Å) Ce–Ce bond lengths. In the second Ce site, Ce is bonded to four equivalent Ac and eight equivalent Ce atoms to form CeAc4Ce8 cuboctahedra that share corners with four equivalent CeAc4Ce8 cuboctahedra, corners with eight equivalent AcCe12 cuboctahedra, edges with twenty-four CeAc4Ce8 cuboctahedra, faces with six equivalent AcCe12 cuboctahedra, and faces with twelve CeAc4Ce8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AcPr3 by Materials Project

AcPr3 is alpha La-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ac is bonded to twelve Pr atoms to form AcPr12 cuboctahedra that share corners with four equivalent AcPr12 cuboctahedra, corners with eight equivalent PrAc4Pr8 cuboctahedra, edges with eight equivalent AcPr12 cuboctahedra, edges with sixteen equivalent PrAc4Pr8 cuboctahedra, faces with four equivalent AcPr12 cuboctahedra, and faces with fourteen PrAc4Pr8 cuboctahedra. There are four shorter (3.77 Å) and eight longer (3.78 Å) Ac–Pr bond lengths. There are two inequivalent Pr sites. In the first Pr site, Pr is bonded to four equivalent Ac and eight Pr atoms to form PrAc4Pr8 cuboctahedra that share corners with twelve equivalent PrAc4Pr8 cuboctahedra, edges with eight equivalent AcPr12 cuboctahedra, edges with sixteen PrAc4Pr8 cuboctahedra, faces with four equivalent AcPr12 cuboctahedra, and faces with fourteen PrAc4Pr8 cuboctahedra. There are four shorter (3.77 Å) and four longer (3.78 Å) Pr–Pr bond lengths. In the second Pr site, Pr is bonded to four equivalent Ac and eight equivalent Pr atoms to form PrAc4Pr8 cuboctahedra that share corners with four equivalent PrAc4Pr8 cuboctahedra, corners with eight equivalent AcPr12 cuboctahedra, edges with twenty-four PrAc4Pr8 cuboctahedra, faces with six equivalent AcPr12 cuboctahedra, and faces with twelve PrAc4Pr8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AcTb3 by Materials Project

AcTb3 is Copper-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ac is bonded to twelve Tb atoms to form AcTb12 cuboctahedra that share corners with four equivalent AcTb12 cuboctahedra, corners with eight equivalent TbAc4Tb8 cuboctahedra, edges with eight equivalent AcTb12 cuboctahedra, edges with sixteen equivalent TbAc4Tb8 cuboctahedra, faces with four equivalent AcTb12 cuboctahedra, and faces with fourteen TbAc4Tb8 cuboctahedra. There are eight shorter (3.67 Å) and four longer (3.68 Å) Ac–Tb bond lengths. There are two inequivalent Tb sites. In the first Tb site, Tb is bonded to four equivalent Ac and eight Tb atoms to form TbAc4Tb8 cuboctahedra that share corners with twelve equivalent TbAc4Tb8 cuboctahedra, edges with eight equivalent AcTb12 cuboctahedra, edges with sixteen TbAc4Tb8 cuboctahedra, faces with four equivalent AcTb12 cuboctahedra, and faces with fourteen TbAc4Tb8 cuboctahedra. There are four shorter (3.67 Å) and four longer (3.68 Å) Tb–Tb bond lengths. In the second Tb site, Tb is bonded to four equivalent Ac and eight equivalent Tb atoms to form TbAc4Tb8 cuboctahedra that share corners with four equivalent TbAc4Tb8 cuboctahedra, corners with eight equivalent AcTb12 cuboctahedra, edges with twenty-four TbAc4Tb8 cuboctahedra, faces with six equivalent AcTb12 cuboctahedra, and faces with twelve TbAc4Tb8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AcY3 by Materials Project

AcY3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ac is bonded to twelve Y atoms to form AcY12 cuboctahedra that share corners with four equivalent AcY12 cuboctahedra, corners with eight equivalent YAc4Y8 cuboctahedra, edges with eight equivalent AcY12 cuboctahedra, edges with sixteen equivalent YAc4Y8 cuboctahedra, faces with four equivalent AcY12 cuboctahedra, and faces with fourteen YAc4Y8 cuboctahedra. There are eight shorter (3.69 Å) and four longer (3.70 Å) Ac–Y bond lengths. There are two inequivalent Y sites. In the first Y site, Y is bonded to four equivalent Ac and eight Y atoms to form YAc4Y8 cuboctahedra that share corners with twelve equivalent YAc4Y8 cuboctahedra, edges with eight equivalent AcY12 cuboctahedra, edges with sixteen YAc4Y8 cuboctahedra, faces with four equivalent AcY12 cuboctahedra, and faces with fourteen YAc4Y8 cuboctahedra. There are four shorter (3.69 Å) and four longer (3.70 Å) Y–Y bond lengths. In the second Y site, Y is bonded to four equivalent Ac and eight equivalent Y atoms to form YAc4Y8 cuboctahedra that share corners with four equivalent YAc4Y8 cuboctahedra, corners with eight equivalent AcY12 cuboctahedra, edges with twenty-four YAc4Y8 cuboctahedra, faces with six equivalent AcY12 cuboctahedra, and faces with twelve YAc4Y8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Standardizing Performance Metrics for Building-Level Electrical Distribution Systems

Building-level electrical distribution systems comprise a myriad of current-carrying equipment, conversion devices, and protection devices that deliver power from the utility or local distributed energy resources to end-use building loads. Electric power has traditionally been generated, transmitted, and distributed in alternating current (AC). However, the last decade has seen a significant increase in the integration of native direct current (DC) equipment that has elevated the importance of DC distribution systems. Numerous studies have comparatively examined the performance of various electrical distribution systems in buildings but have failed to achieve uniform conclusions, primarily because of a lack of consistent and analogous performance evaluation methods. This paper aims to fill this gap by providing a standard set of metrics and measurement boundaries to consistently evaluate the performance of AC, DC, or hybrid AC/DC electrical distribution systems. The efficacy of the proposed approach is evaluated on a representative medium-sized commercial office building model with AC distribution and an equivalent hybrid AC/DC and DC distribution model, wherein the AC distribution model is concluded to be the most efficient. The simulation results show variation in computed metrics with different selected boundaries that verify the effectiveness of the proposed approach in ensuring consistent computation of the performance of building-level electrical distribution systems. This paper provides an initial set of guidelines for building energy system stakeholders to adopt appropriate solutions, thus leading to more efficient energy systems.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2021

Hydration‐Induced β‐Sheet Crosslinking of α‐Helical‐Rich Spider Prey‐Wrapping Silk

Abstract Due to its moderate strength (≈700 MPa) and impressive extensibility before breaking (≈60–80%), orb‐weaving spider aciniform (AC) prey‐wrapping silks are actually the toughest of the spider silks but are remarkably understudied. The previous results indicate that native AC silk fibers are an α‐helix rich coiled‐coil/β‐sheet hybrid nanofiber, and that conversion of disordered or helical domains to β‐sheet aggregates is surprisingly minimal and overall β‐sheet content is low (≈15%). In this work, it is demonstrated through scanning electron microscopy that native AC silk fibers undergo matted cross‐linking upon exposure to moisture that increases silk stiffness. The unique molecular mechanism of water‐induced cross‐linking is revealed with solid‐state NMR (SSNMR) methods; water‐induced morphological changes are correlated with an increase in AC silk protein β‐sheet content, and additionally a minor unfolding of coiled‐coil regions is observed. Continued and increased β‐sheet cross‐linking is observed upon application of mechanical shear. The size of these β‐sheet domains to be 4–6 nm using Wide‐Line Separation SSNMR is determined. The observation that merely water treatment can be used to convert a protein‐based material from a flexible/extensible α‐helix‐rich fiber to a rigid crossed‐linked β‐sheet mat is a novel observation that should provide new avenues in bioinspired materials design.

Stengel, Dillan↗
DOE OSTI2020

Performance Limits of an Alternating Current Electroluminescent Device

Abstract The use of an alternating current (AC) voltage is a simple, versatile method of producing electroluminescence from generic emissive materials without the need for contact engineering. Recently, it was shown that AC‐driven, capacitive electroluminescent devices with carbon nanotube network contacts can be used to generate and study electroluminescence from a variety of molecular materials emitting in the infrared‐to‐ultraviolet range. Here, performance trade‐offs in these devices are studied through comprehensive device simulations and illustrative experiments, enhancing understanding of the mechanism and capability of electroluminescent devices based on alternating as opposed to direct current (DC) schemes. AC‐driven electroluminescent devices can overcome several limitations of conventional DC‐driven electroluminescent devices, including the requirement for proper alignment of material energy levels and the need to process emitting materials into uniform thin films. By simultaneously optimizing device geometry, driving parameters, and material characteristics, the performance of these devices can be tuned. Importantly, the turn‐on voltage of AC‐driven electroluminescent devices approaches the bandgap of the emitting material as the gate oxide thickness is scaled, and internally efficient electroluminescence can be achieved using low‐mobility single‐layer emitter films with varying thicknesses and energy barrier heights relative to the contact.

Wang, Vivian↗
DOE OSTI2020

A Strategy for Constructing Pore‐Space‐Partitioned MOFs with High Uptake Capacity for C 2 Hydrocarbons and CO 2

Abstract Introduction of pore partition agents into hexagonal channels of MIL‐88 type (acs topology) endows materials with high tunability in gas sorption. Here, we report a strategy to partition acs framework into pacs (partitioned acs) crystalline porous materials (CPM). This strategy is based on insertion of in situ synthesized 4,4′‐dipyridylsulfide (dps) ligands. One third of open metal sites in the acs net are retained in pacs MOFs; two thirds are used for pore‐space partition. The Co 2 V‐pacs MOFs exhibit near or at record high uptake capacities for C 2 H 2 , C 2 H 4 , C 2 H 6 , and CO 2 among MOFs. The storage capacity of C 2 H 2 is 234 cm 3 g −1 (298 K) and 330 cm 3 g −1 (273 K) at 1 atm for CPM‐733‐dps (the Co 2 V‐BDC form, BDC=1,4‐benzenedicarboxylate). These high uptake capacities are accomplished with low heat of adsorption, a feature desirable for low‐energy‐cost adsorbent regeneration. CPM‐733‐dps is stable and shows no loss of C 2 H 2 adsorption capacity following multiple adsorption–desorption cycles.

Wang, Yong↗
DOE OSTI2020

A Strategy for Constructing Pore-Space-Partitioned MOFs with High Uptake Capacity for C 2 Hydrocarbons and CO 2

Introduction of pore partition agents into hexagonal channels of MIL-88 type (acs topology) endows materials with high tunability in gas sorption. Here, we report a strategy to partition acs framework into pacs (partitioned acs) crystalline porous materials (CPM). This strategy is based on insertion of in situ synthesized 4, 4'-dipyridylsulfide (dps) ligands. As a result, one third of open metal sites in the parent acs net are retained in pacs MOFs, while two thirds are used for pore space partition. The newly synthesized Co 2 V-pacs MOFs, with optimized pore space and open metal sites, exhibit near or at record high uptake capacities for C 2 H 2 , C 2 H 4 , C 2 H 6 , and CO 2 among MOFs. For example, the storage capacity of C 2 H 2 is 234 cm 3 /g -1 (298 K) and 330 cm 3 /g -1 (273K) at 1 atm for CPM-733-dps (the Co 2 V-BDC form, BDC=1,4-benzenedicarboxylate), higher than benchmark MOFs such as MOF-74 and all other pacs members. These high uptake capacities are accomplished with low heat of adsorption, a feature desirable for low-energy-cost adsorbent regeneration. CPM-733-dps is stable and shows no loss of C 2 H 2 adsorption capacity following multiple adsorption–desorption cycles.

25 ENERGY STORAGE↗
DOE OSTI2020

Highly efficient separation membrane based on cellulose acetate/chitosan fibrous composite substrate with activated carbon functional adsorption layer

Abstract BACKGROUND For improving the permeability and selectivity of adsorption separation membranes, membrane materials, structural morphology and separation technology must continue to be investigated. Development of a membrane that is environmentally friendly, cost‐effective and with high filter precision is an important direction in current research. RESULTS The air pressure spraying method was used to prepare an activated carbon (AC)–cellulose acetate/chitosan (CA/CS) composite membrane. The CA/CS fiber composite membrane was prepared as substrate layer, and AC was loaded on the surface of the CA/CS composite membrane as a functional adsorption layer. When the spraying pressure was 0.01 MPa and the mass ratio of AC/CS was 2:1, a composite membrane with even and compact morphology could be obtained. Both the compact AC functional layer and complete CA/CS substrate layer endowed the AC–CA/CS composite membrane with an excellent water filtration property. At low feeding pressure, the permeate flux and rejection rate of bisphenol A (BPA) could reach 9.27 × 10 3 L m −2 h −1 and 98.31%, respectively. Meanwhile, the adsorption capacities of the membrane were investigated. It tended to equilibrate quickly in 2 min for dyes and BPA. The equilibrium adsorption capacities of the membrane for acid blue, acid yellow and BPA were 175.80, 164.0815 and 79.58 mg g −1 , respectively. The adsorption process conformed to pseudo‐second‐order kinetics and the Langmuir monolayer adsorption model. CONCLUSIONS This work could provide a practical and effective feasibility for membrane separation technology. © 2020 Society of Chemical Industry (SCI)

Zhao, Xiaoyan↗
DOE OSTI2025

Cation exchange separation of radium and actinium using lactic acid DTPA buffer

The separation of actinium ( 228 Ac) from radium ( 223,228 Ra) on cation exchange resin with a diethylenetriaminpentaacetic acid-lactate buffer solution is demonstrated with series of columns. High yield, high radiopurity (~ 100%) separations of Ac from Ra are feasible with small columns in biologically compatible conditions and pHs. As Ac is eluted before Ra on these columns, further studies were performed to determine if this separation system could be applied to Ra/Ac isotope generators, but these were not successful. In conclusion, the separations presented in this work may be relevant for radiopharmaceutical purifications of 225 Ac which is typically obtained from its 225 Ra parent isotope.

and nuclear chemistry↗
DOE OSTI2025

An end-to-end deep learning method for solving nonlocal Allen–Cahn and Cahn–Hilliard phase-field models

Here, we propose an efficient end-to-end deep learning method for solving nonlocal Allen–Cahn (AC) and Cahn–Hilliard (CH) phase-field models. One motivation for this effort emanates from the fact that discretized partial differential equation-based AC or CH phase-field models result in diffuse interfaces between phases, with the only recourse for remediation is to severely refine the spatial grids in the vicinity of the true moving sharp interface whose width is determined by a grid-independent parameter that is substantially larger than the local grid size. In this work, we introduce non-mass conserving nonlocal AC or CH phase-field models with regular, logarithmic, or obstacle double-well potentials. Because of non-locality, some of these models feature totally sharp interfaces separating phases. The discretization of such models can lead to a transition between phases whose width is only a single grid cell wide. Another motivation is to use deep learning approaches to ameliorate the otherwise high cost of solving discretized nonlocal phase-field models. To this end, loss functions of the customized neural networks are defined using the residual of the fully discrete approximations of the AC or CH models, which results from applying a Fourier collocation method and a temporal semi-implicit approximation. To address the long-range interactions in the models, we tailor the architecture of the neural network by incorporating a nonlocal kernel as an input channel to the neural network model. We then provide the results of extensive computational experiments to illustrate the accuracy, predictive capabilities, and cost reductions of the proposed method.

42 ENGINEERING↗
DOE OSTI2020

Mechanical behavior and texture evolution of WE43 magnesium-rare earth alloy in Split-Hopkinson Pressure Bar and Taylor Impact Cylinder Testing

Mechanical behavior and texture evolution of Mg rare-earth alloy WE43 is investigated for strain-rates 10 -3 /s to upwards of 10 5 /s for the two material conditions - as-cast (AC) and T6 age hardened, rolled plate (RT6). The high strain-rate behavior is tested using both Taylor cylinder impact tests (TC) and split Hopkinson pressure bar tests (SHB) and bulk textures are obtained using neutron diffraction. Unlike the quasi-static strained material, AC and RT6 SHB retained high hardening rates throughout the test, even up to 30% true strain. Moreover, the high strain-rate data revealed that the RT6 material has a much higher strength than the AC material, but similar hardening rates despite significantly different initial texture. The flow stress near yield increased up to I 0% for RT6 and up to 30% for AC as the strain-rate increased six orders of magnitude from quasi-static rates 10 -3 /s to 10 3 /s. Neither material exhibited significant plastic anisotropy over the broad range of strain rates, despite the fact that the RT6 material had a moderately strong initial texture. In the TC tests, the geometric cross-sectional changes and texture along the cylinder from the cylindrical sample foot to head are measured and from the neutron diffraction texture analysis, upper-bound estimates of twin volume fraction are obtained as well as dislocation density from analyzing diffraction peak broadening. Recorded geometrical changes along several loading directions show that the material has deformed remarkably homogeneously under impact. Analysis of deformed textures indicates that {101¯2} extension deformation twinning occurred in the RT6 condition over the range of strain rates, with an upper bound estimate of 40% twin volume fraction for approximately 0.10-0.25 true strain. The peak texture components after the impact have their c-axes closely aligned with the impact direction. As a result, these observations are presented and rationalized in the paper.

42 ENGINEERING↗
DOE OSTI2023

Peptide Selenocysteine Substitutions Reveal Direct Substrate–Enzyme Interactions at Auxiliary Clusters in Radical S -Adenosyl- L -methionine Maturases

Radical S-adenosyl-l-methionine (SAM) enzymes leverage the properties of one or more iron- and sulfide-containing metallocenters to catalyze complex and radical-mediated transformations. By far the most populous superfamily of radical SAM enzymes are those that, in addition to a 4Fe–4S cluster that binds and activates the SAM cofactor, also bind one or more additional auxiliary clusters (ACs) of largely unknown catalytic significance. In this report we examine the role of ACs in two RS enzymes, PapB and Tte1186, that catalyze formation of thioether cross-links in ribosomally synthesized and post-translationally modified peptides (RiPPs). Both enzymes catalyze a sulfur-to-carbon cross-link in a reaction that entails H atom transfer from an unactivated C–H to initiate catalysis, followed by formation of a C–S bond to yield the thioether. We show that both enzymes tolerate substitution of SeCys instead of Cys at the cross-linking site, allowing the systems to be subjected to Se K-edge X-ray spectroscopy. The EXAFS data show a direct interaction with the Fe of one of the ACs in the Michaelis complex, which is replaced with a Se–C interaction under reducing conditions that lead to the product complex. Site-directed deletion of the clusters in Tte1186 provide evidence for the identity of the AC. The implications of these observations in the context of the mechanism of these thioether cross-linking enzymes are discussed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Mixed Valence {Ni 2+ Ni 1+ } Clusters as Models of Acetyl Coenzyme A Synthase Intermediates

Acetyl coenzyme A synthase (ACS) catalyzes the formation and deconstruction of the key biological metabolite, acetyl coenzyme A (acetyl-CoA). The active site of ACS features a {NiNi} cluster bridged to a [Fe4S4] n+ cubane known as the A-cluster. The mechanism by which the A-cluster functions is debated, with few model complexes able to replicate the oxidation states, coordination features, or reactivity proposed in the catalytic cycle. In this work, we isolate the first bimetallic models of two hypothesized intermediates on the paramagnetic pathway of the ACS function. The heteroligated {Ni 2+ Ni 1+ } cluster, [K(12-crown-4) 2 ][1], effectively replicates the coordination number and oxidation state of the proposed “A red ” state of the A-cluster. Addition of carbon monoxide to [1] - allows for isolation of a dinuclear {Ni 2+ Ni 1+ (CO)} complex, [K(12-crown-2) n ][2] (n = 1–2), which bears similarity to the “A NiFeC ” enzyme intermediate. Structural and electronic properties of each cluster are elucidated by X-ray diffraction, nuclear magnetic resonance, cyclic voltammetry, and UV/vis and electron paramagnetic resonance spectroscopies, which are supplemented by density functional theory (DFT) calculations. Calculations indicate that the pseudo-T-shaped geometry of the three-coordinate nickel in [1] – is more stable than the Y-conformation by 22 kcal mol –1 , and that binding of CO to Ni 1+ is barrierless and exergonic by 6 kcal mol –1 . UV/vis absorption spectroscopy on [2] - in conjunction with time-dependent DFT calculations indicates that the square-planar nickel site is involved in electron transfer to the CO π*-orbital. Further, we demonstrate that [2] - promotes thioester synthesis in a reaction analogous to the production of acetyl coenzyme A by ACS.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Air-conditioning adoption and electricity demand highlight climate change mitigation–adaptation tradeoffs

Abstract We elucidate mid-century climate change impacts on electricity demand accounting for endogenous adoption of residential air-conditioning (AC) in affluent, cooler countries in Europe, and in poorer, hotter states in India. By 2050, in a high-warming scenario (SSP585) AC prevalence grows twofold in Europe and fourfold in India, reaching around 40% in both regions. We document a mitigation-adaptation tradeoff: AC expansion reduces daily heat exposures by 150 million and 3.8 billion person degree-days (PDDs), but increases annual electricity demand by 34 TWh and 168 TWh in Europe and India, respectively (corresponding to 2% and 15% of today’s consumption). The increase in adoption and use of AC would result in an additional 130 MMTCO2, of which 120 MMTCO2 in India alone, if the additional electricity generated were produced with today’s power mix. The tradeoff varies geographically and across income groups: a one PDD reduction in heat exposure in Europe versus India necessitates five times more electricity (0.53 kWh vs 0.1 kWh) and two times more emissions (0.16 kgCO $$_2$$ 2 vs 0.09 kgCO $$_2$$ 2 ), on average. The decomposition of demand drivers offers important insights on how such tradeoff can be moderated through policies promoting technology-based and behavioral-based adaptation strategies.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Tumor targeted alpha particle therapy with an actinium-225 labelled antibody for carbonic anhydrase IX

Selective antibody targeted delivery of α particle emitting actinium-225 to tumors has significant therapeutic potential. This work highlights the design and synthesis of a new bifunctional macrocyclic diazacrown ether chelator, H 2 MacropaSqOEt, that can be conjugated to antibodies and forms stable complexes with actinium-225. The macrocyclic diazacrown ether chelator incorporates a linker comprised of a short polyethylene glycol fragment and a squaramide ester that allows selective reaction with lysine residues on antibodies to form stable vinylogous amide linkages. This new H 2 MacropaSqOEt chelator was used to modify a monoclonal antibody, girentuximab (hG250), that binds to carbonic anhydrase IX, an enzyme that is overexpressed on the surface of cancers such as clear cell renal cell carcinoma. This new antibody conjugate (H 2 MacropaSq-hG250) had an average chelator to antibody ratio of 4 : 1 and retained high affinity for carbonic anhydrase IX. H 2 MacropaSq-hG250 was radiolabeled quantitatively with [ 225 Ac]Ac III within one minute at room temperature with micromolar concentrations of antibody and the radioactive complex is stable in human serum for >7 days. Evaluation of [ 225 Ac]Ac(MacropaSq-hG250) in a mouse xenograft model, that overexpresses carbonic anhydrase IX, demonstrated a highly significant therapeutic response. It is likely that H 2 MacropaSqOEt could be used to modify other antibodies providing a readily adaptable platform for other actinium-225 based therapeutics.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗