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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Chameleon sequences in neurodegenerative diseases

Chameleon sequences can adopt either alpha helix sheet or a coil conformation. Defining chameleon sequences in PDB (Protein Data Bank) may yield to an insight on defining peptides and proteins responsible in neurodegeneration. In this research, we benefitted from the large PDB and performed a sequence analysis on Chameleons, where we developed an algorithm to extract peptide segments with identical sequences, but different structures. In order to find new chameleon sequences, we extracted a set of 8315 non-redundant protein sequences from the PDB with an identity less than 25%. Our data was classified to “helix to strand (HE)”, “helix to coil (HC)” and “strand to coil (CE)” alterations. We also analyzed the occurrence of singlet and doublet amino acids and the solvent accessibility in the chameleon sequences; we then sorted out the proteins with the most number of chameleon sequences and named them Chameleon Flexible Proteins (CFPs) in our dataset. Our data revealed that Gly, Val, Ile, Tyr and Phe, are the major amino acids in Chameleons. We also found that there are proteins such as Insulin Degrading Enzyme IDE and GTP-binding nuclear protein Ran (RAN) with the most number of chameleons (640 and 405 respectively). These proteins have known roles in neurodegenerative diseases. Therefore it can be inferred that other CFP's can serve as key proteins in neurodegeneration, and a study on them can shed light on curing and preventing neurodegenerative diseases.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

CD27{sup -}CD45{sup +} γδ T cells can be divided into two populations, CD27{sup -}CD45{sup int} and CD27{sup -}CD45{sup hi} with little proliferation potential

In addition to the majority of T cells which carry the αβ T cell receptor (TCR) for antigen, a distinct subset of about 1–5% of human peripheral blood T cells expressing the γδ TCR contributes to immune responses to infection, tissue damage and cancer. T cells with the Vδ2{sup +} TCR, usually paired with Vγ9, constitute the majority of these γδ T cells. Analogous to αβ T cells, they can be sorted into naive (CD27{sup +}CD45RA{sup +}), central memory (CD27{sup +}CD45RA{sup −}), effector memory (CD27{sup −}CD45RA{sup −}), and terminally-differentiated effector memory (CD27{sup −}CD45RA{sup +}) phenotypes. Here, we found that CD27{sup −}CD45RA{sup +} γδ T cells can be further divided into two populations based on the level of expression of CD45RA: CD27{sup −}CD45RA{sup int} and CD27{sup −}CD45RA{sup hi}. Those with the CD27{sup −}CD45RA{sup hi} phenotype lack extensive proliferative capacity, while those with the CD27{sup −}CD45RA{sup int} phenotype can be easily expanded by culture with zoledronate and IL-2. These CD27{sup -}CD45RA{sup hi} potentially exhausted γδ T cells were found predominantly in cancer patients but also in healthy subjects. We conclude that γδ T cells can be divided into at least 5 subsets enabling discrimination of γδ T cells with poor proliferative capacity. It was one of our goals to predict the feasibility of γδ T cell expansion to sufficient amounts for adoptive immunotherapy without the necessity for conducting small-scale culture tests. Fulfilling the ≥1.5% criterion for γδ T cells with phenotypes other than CD27{sup −}CD45RA{sup hi}, may help avoid small-scale culture testing and shorten the preparation period for adoptive γδ T cells by 10 days, which may be beneficial for patients with advanced cancer. - Highlights: • CD27{sup -}CD45{sup +} γδ T cells can be divided into two populations, CD27{sup -}CD45{sup hi} and CD27{sup -}CD45{sup int}. • CD27{sup -}CD45{sup hi} γδ T cells are detected in the peripheral blood of both cancer patients and healthy subjects. • CD27{sup -}CD45{sup hi} γδ T cells are distinct from so-called terminally differentiated CD27{sup -}CD45{sup int} γδ T cells. • CD27{sup -}CD45{sup hi} γδ T cells lack vigorous proliferative potential.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Integration of in silico approaches to determination of endocrine-disrupting perfluorinated chemicals binding potency with steroidogenic acute regulatory protein

A myriad of perfluorinated compounds (PFCs) have the ability to interfere with steroidogenic acute regulatory (StAR) protein. Consequently, PFCs breaches cholesterol biotransformation in mitochondria and cause fatal consequences in steroidogenesis, however, these were poorly characterized. In the present study, we have evaluated toxic potencies, nuclear mediated probabilities and interaction profiles with StAR of PFCs using computational system biology tools. Toxicity endpoints revealed that PFCs contain high carcinogenicity, developmental toxicity, skin sensitization effects with low mutagenic activity. Consensus qualitative nuclear receptor agonist models show higher probability rates towards ER and PPAR-γ receptor than AR and AhR models were observed. To poise the subtle fluctuations of actual predictions, balanced accuracy and MCC were computed, and they signify perfect correlation ranges in all models. Screening studies resulting protein-ligand interaction profiles showed that residues Asn148, Asn150, Glu169, Ala171, Arg182, Phe184, Arg188, Trp241, Thr263 and Phe267 were identified as novel hotspots, participated in halogen bonds, H-bonds, atomic π-stacking, π-cation interactions and salt-bridges formation. Thus, the additional bonds contribute conformer stability that holds the protein structure at flexible state, so that PFCs acts as a barrier to cholesterol binding. From docking outcomes, representation space was created, that specifies high and medium StAR binders were occupied in toxic endpoints space with active concern. PFCs restrain molecular features and mitochondrial membrane disruption functions were revealed by efficient toxicogenomics studies. These data indicate toxicity and StAR protein binding levels of PFCs, sorted pinpoints could be useful in a promising way to know the other environmental pollutants and health risks. - Highlights: • In this study, QSAR models were revealed that PFCs have greater adverse toxicity along with nuclear receptors interaction potencies. • Binding potencies of PFCs against the StAR protein revealed only potential novel residue hotspots showed various bond patterns, and they sustain stability and complexity of StAR. • Through that, PFCs acts as a barrier in cholesterol binding and leads fatal consequences in steroidogenesis.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Overexpression of SNX7 reduces Aβ production by enhancing lysosomal degradation of APP

Highlights: • SNX7 has been proposed to be linked with Alzheimer's disease. • Overexpression of SNX7 reduces the production of Aβ and sAPPβ. • It also reduces the cellular level of APP. • The reduction of APP is reversed by inhibitors of lysosomal degradation. • Our results suggest that SNX7 takes part in directing APP for degradation. Abnormal production of amyloid-β peptides (Aβ) by proteolytic processing of amyloid precursor protein (APP) is thought to be central to the pathogenesis of Alzheimer's disease (AD). Although many efforts have been made to investigate mechanisms that regulate APP processing, many details remain incompletely understood. Sorting nexins (SNXs) are a family of proteins which are involved in many intracellular trafficking events. Several SNXs have been implicated in APP processing and Aβ production. In this study, we extended the investigation to SNX7. We found that overexpression of SNX7 in HEK293T cells reduces the levels of secreted Aβ and β-cleaved N-terminal APP fragments (sAPPβ). Moreover, SNX7 overexpression caused a significant reduction of the steady-state levels of APP as well as of the cell surface APP levels. By using NH{sub 4}Cl and Bafilomycin A1 to inhibit the lysosomal degradative pathway, we found that the reduction of APP induced by SNX7 overexpression was prevented by such inhibition. No change in the cell surface distribution or steady-state levels of BACE1 was detected after overexpression of SNX7. Taken together, these results suggest that SNX7 regulates Aβ production by directing APP for degradation.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

High ALDH activity defines ovarian cancer stem-like cells with enhanced invasiveness and EMT progress which are responsible for tumor invasion

Highlights: • Pluripotent, invasive and EMT-related genes are positively correlated. • The definition of ovarian ALDH{sup high} CSCLs is verified by their higher colony-formation, multipotent-genes expression and tumorigenicity. • Ovarian ALDH{sup high} CSCLs display advanced invasiveness, EMT progress and apoptosis-resistance. • ALDH{sup high} CSCLs take chief charge of EOC invasion, due to their elevated stemness and metastatic features. Epithelial ovarian cancer (EOC) is highly metastatic and current therapeutics are unsatisfactory. Cancer stem/stem-like cells (CSCs/CSCLs) represent a rare population of undifferentiated oncogenic cells responsible for tumor initiation and maintenance. We identified ovarian cancer ALDH{sup high} (aldehyde dehydrogenase) population could perform not only strengthened CSCLs properties embodied in colony-formation, CSCs-markers expression, and tumorigenesis in vivo, but also a greater invasive capacity with advanced EMT progress and anti-apoptosis compared with ALDH{sup low} cells. Furthermore, both the stemness and aggressive features, along with ALDH{sup high} percentages were in positive association with the invasiveness of cell lines for sorting, indicating the promotive role of ALDH{sup high} CSCLs in EOC neoplasia and metastasis, since the whole tumor was derived from the CSCLs with hyperactive self-renewal and aggression. Collectively, this study illustrates the interplay between ALDH{sup high} CSCLs and EOC invasion, and offers a novel application target for the EOC oncotherapy.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Activation of TLR3 and its adaptor TICAM-1 increases miR-21 levels in extracellular vesicles released from human cells

Highlights: • Activation of TLR3 increases miR-21 levels in extracellular vesicles. • TLR3 requires TICAM-1 adaptor to increase miR-21 levels in extracellular vesicles. • YBX-1 is involved in TLR3-mediated increase of miR-21 levels. Pattern-recognition receptors (PRRs) recognizes viral RNAs and trigger the innate immune responses. Toll-like receptor 3 (TLR3), a PRR, recognizes viral double-stranded RNA (dsRNA) in endolysosomes, whereas cytoplasmic dsRNA is sensed by another PRR, MDA5. TLR3 and MDA5 utilize TICAM-1 and MAVS, respectively, to trigger the signal for inducing innate immune responses. Extracellular vesicles (EVs) include the exosomes and microvesicles; an accumulating body of evidence has shown that EVs delivers functional RNA, such as microRNAs (miRNAs), to other cells and thus mediate intercellular communications. Therefore, EVs carrying miRNAs affect innate immune responses in macrophages and dendritic cells. However, the mechanism underlying the regulation of miRNA levels in EVs remains unclear. To elucidate the mechanism, we sought to reveal the pathway that control miRNA expression levels in EVs. Here, we found that TLR3 stimulation increased miR-21 levels in EVs released from various types of human cells. Ectopic expression of the TLR3 adaptor, TICAM-1, increased miR-21 levels in EVs but not intracellular miR-21 levels, suggesting that TICAM-1 augmented sorting of miR-21 to EVs. In contrast, the MDA5 adaptor, MAVS, did not increase miR-21 levels in EVs. The siRNA for TICAM-1 reduced EV miR-21 levels after stimulation of TLR3. Collectively, our data indicate a novel role of the TLR3-TICAM-1 pathway in controlling miR-21 levels in EVs.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Effect of long non-coding RNA H19 on oxidative stress and chemotherapy resistance of CD133+ cancer stem cells via the MAPK/ERK signaling pathway in hepatocellular carcinoma

Highlights: • The H19 expression is higher in HCC tissues than in adjacent normal tissues. • CD133-positive Huh7 cells account for (99.4 ± 3.6)% by flow cytometry. • Inhibition of H19 induces OS in CD133 + cancer stem cells. • Inhibition of H19 reverses chemoresistance in CD133 + cancer stem cells. • Inhibition of H19 contributes to inactivation of MAPK/ERK signaling pathway. We explored the ability of a long non-coding RNA H19, to influence oxidative stress (OS) and chemotherapy resistance of CD133 + cancer stem cells via the MAPK/ERK signaling pathway in HCC. HCC tissues with corresponding adjacent normal tissues were collected. CD133 + HuH7 cells were sorted and assigned into five groups. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting were performed to determine expression levels mRNAs and proteins. Levels of reactive oxygen species (ROS) and malonaldehyde (MDA), and activity of superoxide dismutase (SOD) were measured. Cell viability was analyzed by MTT assay and cell apoptosis by flow cytometry. Compared with adjacent normal tissues, the H19 expression level was higher and MAPK and ERK protein levels were lower in HCC tissues. Compared with the blank group, in the pcDNA-H19 group, H19 expression level, MAPK and ERK protein levels, MDR1 and GST-π expression levels were increased, ROS and MDA levels were decreased, SOD activity was weakened, cell viability was promoted, and cell apoptosis was inhibited; in the siH19 group, H19 expression level, MAPK and ERK protein levels, MDR1 and GST-π expression levels were reduced, ROS and MDA levels were elevated, SOD activity was enhanced, cell viability was inhibited, and cell apoptosis was promoted. There was no significant difference among blank, NC and pcDNA-H19 + PD98059 groups. The study provides evidence that downregulation of H19 may induce OS and reverse chemotherapy resistance of CD133 + cancer stem cells by blocking the MAPK/ERK signaling pathway in HCC.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Mouse model of chorea-acanthocytosis exhibits male infertility caused by impaired sperm motility as a result of ultrastructural morphological abnormalities in the mitochondrial sheath in the sperm midpiece

Chorea-acanthocytosis (ChAc) is an autosomal recessive hereditary disease characterized by neurodegeneration in the striatum and acanthocytosis caused by loss-of-function mutations in the Vacuolar Protein Sorting 13 Homolog A (VPS13A) gene, which encodes chorein. We previously produced a ChAc-model mouse with a homozygous deletion of exons 60–61 in Vps13a, which corresponded to the human disease mutation. We found that male ChAc-model mice exhibited complete infertility as a result of severely diminished sperm motility. Immunocytochemical study revealed that chorein-like immunoreactivity is abundant only in the midpiece, mitochondria-rich region, of the sperm of wild type mice. They showed no significant differences from wild types in terms of the adenosine 5′-triphosphate (ATP) concentration of their sperm, sperm count, or sexual activity. Electron microscopy revealed abnormal ultrastructural morphology of the mitochondria in the midpiece of sperm from ChAc-model mice. These results suggest that chorein is essential in mouse sperm for the maintenance of ultrastructural mitochondrial morphology and sperm motility.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Effects of Icaritin on the physiological activities of esophageal cancer stem cells

Highlights: • CSCs were used instead of using cancer cells. • The effect of Icaritin on the Hedgehog and Wnt signaling pathway was investigated. • Our study found that Icaritin down-regulated the level of Hedgehog, Smo and Gli in Hedgehog pathway, up-regulated GSK3β and down-regulated Wnt and β-catenin in Wnt pathway, indicating that Icaritin may inhibit the activity of esophageal CSCs through regulating the expression of proteins in important pathways related to esophageal cancer. Icaritin is a compound extracted from herb, recent study have found it is able to influence the activity of various types of cancer. Our aim was to investigate the effects of Icaritin on the physiological activities of esophageal cancer stem cells (CSCs). In this study, esophageal cancer cells were cultured and CD133 positive esophageal CSCs were sorted by flow cytometry. Changes in the physiological activity of esophageal CSCs following treatment with different concentrations of Icaritin (0, 12.5, 25, 50, and 100 μmol/L) were evaluated. The CCK-8 method and Transwell assay were used to determine the effects of Icaritin on the proliferation, migration, and invasion of esophageal CSCs. Flow cytometery was used to investigate its effect on the apoptosis of CSCs. The effect of Icaritin on the expression of proteins in Wnt and Hedgehog signaling pathways were determined using western blot test. Consequently, Icaritin inhibited the proliferation, migration, and invasion of esophageal CSCs in a dose-dependent manner. It promoted cell apoptosis, and influenced the levels of proteins in Wnt and Hedgehog signaling pathways. It may act as a promising drug in the therapy of esophageal cancer.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Identification of human immunodeficiency virus type-1 Gag-TSG101 interaction inhibitors by high-throughput screening

Highlights: • Development of HTS system based on ELISA targeting Gag-TSG101 interaction. • Screening of 9600 compounds identified 11 compounds inhibiting Gag-TSG101 binding. • Hit compounds, HSM-9 and HSM-10 potently reduced HIV-1 replication. The interaction between viral protein Gag and cellular protein tumor susceptibility gene 101 (TSG101) is a crucial step in the HIV-1 replication cycle. This interaction initiates the viral assembly/budding via the cellular endosomal sorting complexes required for transport (ESCRT) pathway, making it a potential target for antiviral therapy. Here we developed a simple, robust, and reliable high-throughput screening (HTS) system based on enzyme-linked immunosorbent assay (ELISA) to identify compounds that inhibit HIV-1 replication by targeting Gag-TSG101 interaction. Through screening of the 9600-compound library using the established HTS system, several hit compounds, which inhibited Gag-TSG101 interaction, were identified. Subsequent assays revealed two hit compounds, HSM-9 and HSM-10, which have antiviral activity against CD4{sup +} T cell-tropic NL4-3 and macrophage-tropic JR-CSF HIV-1 strains. These results suggest that our established HTS system is an indispensable tool for the identification of HIV-1 Gag-TSG101 interaction inhibitors.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2020

Improving biomass and lipid yields of Desmodesmus armatus and Chlorella vulgaris through mutagenesis and high-throughput screening

Advancement of microalgae for use as biofuel feedstock depends on bioprospecting novel strains and then applying classical strain improvement techniques to enhance desirable traits. Here we successfully demonstrate this approach using two novel strains of green algae, identified as Desmodesmus armatus and Chlorella vulgaris, to improve biomass and lipid yields. UV irradiation was utilized to generate random mutations and the resulting populations were analyzed via flow cytometry to quantify lipid fluorescence while enriching for high lipid variants using fluorescence activated cell sorting. Secondary screening was performed via in situ fluorescence staining to identify the single highest lipid producing mutants from each strain. This approach produced a Desmodesmus armatus mutant that exhibited both increased biomass productivity and higher lipid content, which doubled lipid yield from the culture. The resulting Chlorella vulgaris mutant exhibited an increase in growth only, resulting in a 33% increase in lipid yield.

09 BIOMASS FUELS↗
DOE OSTI2021

The crystal and coordination chemistry of neptunium in all its oxidation states: An expanded structural hierarchy of neptunium compounds

We report structures of 388 neptunium-bearing crystal structures are sorted into an expanded structural hierarchy and examined. The majority of structures contain Np(V) (149), Np(VI) (99), or Np(IV) (91) whereas structures containing Np(II), Np(III), Np(VII), or more than one oxidation state are rare. Coordination geometry of Np(V) and Np(VI) compounds is dominated by the approximately linear neptunyl cation. Actinyl–actinyl interactions (AAIs) are most prevalent in Np(V) compounds and are observed in 48% of these extended structures. Prismatic coordination geometries are commonly observed in Np(IV) compounds. Np(III) organometallic complexes display a variety of coordination modes. Coordination chemistry of Np(VII) compounds is dominated by the tetra-oxido core. Updated average bond length values are provided for Np(IV), Np(V), Np(VI), and Np(VII) compounds and updated bond valence parameters for Np(IV) are reported. A graphical notation system for neptunyl structures coordinated by organic ligands was developed to facilitate discussion and identify similarities between neptunyl compounds coordinated by oxyanions and neptunyl compounds coordinated by organic ligands.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Vaccine-Induced Antibodies that Neutralize Group 1 and Group 2 Influenza A Viruses

Antibodies capable of neutralizing divergent influenza A viruses could form the basis of a universal vaccine. Here, from subjects enrolled in an H5N1 DNA/MIV-prime-boost influenza vaccine trial, we sorted hemagglutinin cross-reactive memory B cells and identified three antibody classes, each capable of neutralizing diverse subtypes of group 1 and group 2 influenza A viruses. Co-crystal structures with hemagglutinin revealed that each class utilized characteristic germline genes and convergent sequence motifs to recognize overlapping epitopes in the hemagglutinin stem. All six analyzed subjects had sequences from at least one multidonor class, and—in half the subjects—multidonor-class sequences were recovered from >40% of cross-reactive B cells. By contrast, these multidonor-class sequences were rare in published antibody datasets. Vaccination with a divergent hemagglutinin can thus increase the frequency of B cells encoding broad influenza A-neutralizing antibodies. We propose the sequence signature-quantified prevalence of these B cells as a metric to guide universal influenza A immunization strategies.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2022

Asymmetric and non-stoichiometric glycoprotein recognition by two distinct antibodies results in broad protection against ebolaviruses

Several ebolaviruses cause outbreaks of severe disease. Vaccines and monoclonal antibody cocktails are available to treat Ebola virus (EBOV) infections, but not Sudan virus (SUDV) or other ebolaviruses. Current cocktails contain antibodies that cross-react with the secreted soluble glycoprotein (sGP) that absorbs virus-neutralizing antibodies. By sorting memory B cells from EBOV infection survivors, we isolated two broadly reactive anti-GP monoclonal antibodies, 1C3 and 1C11, that potently neutralize, protect rodents from disease, and lack sGP cross-reactivity. Both antibodies recognize quaternary epitopes in trimeric ebolavirus GP. 1C11 bridges adjacent protomers via the fusion loop. 1C3 has a tripartite epitope in the center of the trimer apex. One 1C3 antigen-binding fragment anchors simultaneously to the three receptor-binding sites in the GP trimer, and separate 1C3 paratope regions interact differently with identical residues on the three protomers. A cocktail of both antibodies completely protected nonhuman primates from EBOV and SUDV infections, indicating their potential clinical value.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Development of a VRC01-class germline targeting immunogen derived from anti-idiotypic antibodies

An effective HIV-1 vaccine will likely need to elicit broadly neutralizing antibodies (bNAbs). Broad and potent VRC01-class bNAbs have been isolated from multiple infected individuals, suggesting that they could be reproducibly elicited by vaccination. Several HIV-1 envelope-derived germline-targeting immunogens have been designed to engage naive VRC01-class precursor B cells. However, they also present off-target epitopes that could hinder development of VRC01-class bNAbs. We characterize a panel of anti-idiotypic monoclonal antibodies (ai-mAbs) raised against inferred-germline (iGL) VRC01-class antibodies. By leveraging binding, structural, and B cell sorting data, we engineered a bispecific molecule derived from two aimAbs; one specific for VRC01-class heavy chains and one specific for VRC01-class light chains. The bispecific molecule preferentially activates iGL-VRC01 B cells in vitro and induces specific antibody responses in a murine adoptive transfer model with a diverse polyclonal B cell repertoire. This molecule represents an alternative non-envelope-derived germline-targeting immunogen that can selectively activate VRC01-class precursors in vivo.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

A Computational Framework to design 3D stiffness gradient acoustic metamaterials for impedance matching

Acoustic waves play a crucial role in various applications, including medical imaging, non-destructive testing, and sonar systems. One of the significant challenges in these applications is impedance matching, which is essential for minimizing reflections and maximizing the transfer of acoustic energy between different media. Acoustic metamaterials offer a promising solution to this challenge. In addition to impedance control, gradient stiffness can enhance structural efficiency and enable spatial control of wave propagation, making it a valuable feature in acoustic metamaterial design. In this pa- per, we present our developed computational method to design 3D stiffness gradient acoustic metamaterials for impedance matching. The key steps in our approach include generating initial designs using a periodic covariance function to provide unit cells that are both periodic on the boundaries and randomly formed inside the unit cell. Furthermore, we integrated manufacturing constraints into the design process, ensuring that the structures are interconnected for fabrication. We propose two computational optimization algorithms: GenUnit, based on a non-dominated sorting genetic algorithm (NSGA-II), and MLMatch, which leverages differentiable machine learning. The two approaches are not separate contributions but complementary com- ponents of a unified framework. GenUnit requires no training data and directly interfaces with physics-based simulations, making it highly accurate but slower for large-scale exploration. In contrast, MLMatch is data-hungry during training but, once trained, enables near-instantaneous inference and broad design-space coverage. Together, they form a hybrid strategy: ML- Match rapidly explores the global design space, and GenUnit provides local refinement with high-fidelity accuracy. This balance between training cost, inference time, and precision is the motivation for including both methods in the same study. We applied this dual-algorithm framework to generate two metallic-based metamaterial designs that match the acoustic impedance of water while exhibiting a controlled gradient in stiffness (from stiff to soft). The stiffness gradient is particularly advantageous in applications where one side of the structure must interface with soft or sensitive surfaces, such as human tissue or delicate components. Here, this work paves the way for improved materials in various acoustic applications, particularly in ultrasound devices, by providing better impedance.

Metamaterial↗
DOE OSTI2026

Computational methods in solution-based plastics purification

Plastic waste can be recycled into resins with near-virgin properties by solution-based purification processes that selectively dissolve polymers, remove contaminants, or detach printing residues. Here, in this review, we examine computational methods for predicting the behavior governing solution-based plastic purification, motivated by the vast polymer–solvent–contaminant compositional space. We discuss thermodynamic and machine learning methods for predicting polymer–solvent and polymer–contaminant interaction and review physics-based molecular dynamics simulations that resolve molecular-scale phenomena within polymer matrices inaccessible to screening methods. We highlight how these methods have informed experimental design for dissolution-based recycling and solvent-based contaminant removal. Finally, we discuss the prospective role of agentic AI in integrating these computational tools with real-time sorting data to adapt purification conditions to the compositional variability of real post-consumer feedstocks. This review charts a path toward computationally guided solution-based purification workflows that can respond to the complexity inherent in plastic waste streams.

Altamimi, Ali [Univ. of Wisconsin, Madison, WI (Un↗
DOE OSTI2017

The role of correlations in uncertainty quantification of transportation relevant fuel models

Large reaction mechanisms are often used to describe the combustion behavior of transportation-relevant fuels like gasoline, where these are typically represented by surrogate blends, e.g., n-heptane/iso-octane/toluene. We describe efforts to quantify the uncertainty in the predictions of such mechanisms at realistic engine conditions, seeking to better understand the robustness of the model as well as the important reaction pathways and their impacts on combustion behavior. In this work, we examine the importance of taking into account correlations among reactions that utilize the same rate rules and those with multiple product channels on forward propagation of uncertainty by Monte Carlo simulations. Automated means are developed to generate the uncertainty factor assignment for a detailed chemical kinetic mechanism, by first uniquely identifying each reacting species, then sorting each of the reactions based on the rate rule utilized. Simulation results reveal that in the low temperature combustion regime for iso-octane, the majority of the uncertainty in the model predictions can be attributed to low temperature reactions of the fuel sub-mechanism. The foundational, or small-molecule chemistry (C 0 -C 4 ) only contributes significantly to uncertainties in the predictions at the highest temperatures (Tc=900 K). Accounting for correlations between important reactions is shown to produce non-negligible differences in the estimates of uncertainty. Including correlations among reactions that use the same rate rules increases uncertainty in the model predictions, while accounting for correlations among reactions with multiple branches decreases uncertainty in some cases. Significant non-linear response is observed in the model predictions depending on how the probability distributions of the uncertain rate constants are defined.Finally, we concluded that care must be exercised in defining these probability distributions in order to reduce bias, and physically unrealistic estimates in the forward propagation of uncertainty for a range of UQ activities.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗