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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Accelerating Hydrogen Absorption and Desorption Rates in Palladium Nanocubes with an Ultrathin Surface Modification

Exploiting the high surface-area-to-volume ratio of nanomaterials to store energy in the form of electrochemical alloys is an exceptionally promising route for achieving high-rate energy storage and delivery. Nanoscale palladium hydride is an excellent model system for understanding how nanoscale-specific properties affect the absorption and desorption of energy carrying equivalents. Hydrogen absorption and desorption in shape-controlled Pd nanostructures does not occur uniformly across the entire nanoparticle surface. Instead, hydrogen absorption and desorption proceed selectively through high-activity sites at the corners and edges. Such a mechanism hinders the hydrogen absorption rates and greatly reduces the benefit of nanoscaling the dimensions of the palladium. To solve this, we modify the surface of palladium with an ultrathin platinum shell. This modification nearly removes the barrier for hydrogen absorption (89 kJ/mol without a Pt shell and 1.8 kJ/mol with a Pt shell) and enables diffusion through the entire Pd/Pt surface.

25 ENERGY STORAGE↗
DOE OSTI2018

Distinct progression pattern of susceptibility MRI in the substantia nigra of Parkinson's patients

Abstract Background: Susceptibility MRI may capture Parkinson's disease‐related pathology. This study delineated longitudinal changes in different substantia nigra regions. Methods: Seventy‐two PD patients and 62 controls were studied at both baseline and after 18 months with MRI. R2* and quantitative susceptibility mapping values from the substantia nigra pars compacta and substantia nigra pars reticulata were calculated. Mixed‐effects models compared controls with PD or PD subgroups having different disease durations: early (<1 year), middle (<5 years, middle‐stage PD), and late (>5 years, late‐stage PD). Pearson's correlation assessed associations between imaging and clinical measures. Results: At baseline, R2* and quantitative susceptibility mapping were higher in both the substantia nigra pars compacta and substantia nigra pars reticulata in all PD patients (group effect, P ≤ 0.003). Longitudinally, the substantia nigra pars compacta R2* showed a faster increase in PD compared with controls (time × group, P = 0.002), whereas quantitative susceptibility mapping did not ( P = 0.668). The substantia nigra pars reticulata R2* and quantitative susceptibility mapping did not differ between PD and controls (time × group, P ≥ 0.084), although both decreased longitudinally (time effect, P ≤ 0.004). Baseline substantia nigra pars compacta R2* was higher in all PD subgroups (group, P ≤ 0.006), but showed a significantly faster increase only in later‐stage PD (time × group, P < 0.0001) that correlated with changes in nonmotor symptoms ( r = 0.746, P = 0.002). Baseline substantia nigra pars reticulata quantitative susceptibility mapping was higher in middle‐stage PD and later‐stage PD (group, P ≤ 0.002), but showed a longitudinal decrease (time × group, P = 0.004) only in later‐stage PD that correlated with changes in motor signs ( r = 0.837, P < 0.001). Conclusion: Susceptibility MRI revealed distinct patterns of PD progression in the substantia nigra pars compacta and substantia nigra pars reticulata. The different patterns are particularly clear in later‐stage patients. These findings may resolve past controversies and have implications in the pathophysiological processes during PD progression. © 2018 International Parkinson and Movement Disorder Society

Du, Guangwei↗
DOE OSTI2018

Improved Overall Survival and Locoregional Disease Control With Concurrent PD-1 Pathway Inhibitors and Stereotactic Radiosurgery for Lung Cancer Patients With Brain Metastases

Despite the emerging role of programmed cell death-1 (PD-1) pathway inhibitors for patients with advanced lung cancer, a paucity of data are available on the activity of these agents among patients with brain metastases. We investigated the outcomes of PD-1 pathway inhibitors and stereotactic radiosurgery (SRS) for the treatment of patients with brain metastases from lung cancer.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

Shape-Controlled CO 2 Electrochemical Reduction on Nanosized Pd Hydride Cubes and Octahedra

Electrochemical CO 2 reduction reaction (CO 2 RR) provides a potential pathway to mitigate challenges related to CO 2 emissions. Pd nanoparticles have shown interesting properties as CO 2 RR electrocatalysts, while how different facets of Pd affect its performance in CO 2 reduction to synthesis gas with controlled H 2 to CO ratios has not been studied. Herein, we synthesized nano-sized Pd cubes and octahedra particles dominated by Pd(100) and Pd(111) facets, respectively. Here, the Pd octahedra particles show higher CO selectivity (up to 95%) and better activity than Pd cubes and commercial particles. For both Pd octahedra and cubes, the ratio of H 2 /CO products was tunable between 1 and 2, a desirable ratio for methanol production and the Fischer-Tropsch processes. Further studies of Pd octahedra in a 25-cm 2 flow cell showed a total CO current of 5.47 A was achieved at a potential of 3.4 V, corresponding to a CO partial current density of 220 mA/cm -2 . In situ X-ray absorption spectroscopy studies showed that regardless of facet Pd transformed into Pd hydride (PdH) under reaction conditions. DFT calculations show that the reduced binding energies of CO and HOCO intermediates on PdH(111) are key parameters to the high current density and Faradaic efficiency in CO 2 to CO conversion.

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

Dual blockade of IL-10 and PD-1 leads to control of SIV viral rebound following analytical treatment interruption

Human immunodeficiency virus (HIV) persistence during antiretroviral therapy (ART) is associated with heightened plasma interleukin-10 (IL-10) levels and PD-1 expression. We hypothesized that IL-10 and PD-1 blockade would lead to control of viral rebound following analytical treatment interruption (ATI). Twenty-eight ART-treated, simian immunodeficiency virus (SIV)mac 239 -infected rhesus macaques (RMs) were treated with anti-IL-10, anti-IL-10 plus anti-PD-1 (combo) or vehicle. ART was interrupted 12 weeks after introduction of immunotherapy. Durable control of viral rebound was observed in nine out of ten combo-treated RMs for >24 weeks post-ATI. Induction of inflammatory cytokines, proliferation of effector CD8 + T cells in lymph nodes and reduced expression of BCL-2 in CD4 + T cells pre-ATI predicted control of viral rebound. Twenty-four weeks post-ATI, lower viral load was associated with higher frequencies of memory T cells expressing TCF-1 and of SIV-specific CD4 + and CD8 + T cells in blood and lymph nodes of combo-treated RMs. These results map a path to achieve long-lasting control of HIV and/or SIV following discontinuation of ART.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2020

Electrocardiographic changes predate Parkinson’s disease onset

Autonomic nervous system involvement precedes the motor features of Parkinson’s disease (PD). Our goal was to develop a proof-of-concept model for identifying subjects at high risk of developing PD by analysis of cardiac electrical activity. We used standard 10-s electrocardiogram (ECG) recordings of 60 subjects from the Honolulu Asia Aging Study including 10 with prevalent PD, 25 with prodromal PD, and 25 controls who never developed PD. Various methods were implemented to extract features from ECGs including simple heart rate variability (HRV) metrics, commonly used signal processing methods, and a Probabilistic Symbolic Pattern Recognition (PSPR) method. Extracted features were analyzed via stepwise logistic regression to distinguish between prodromal cases and controls. Stepwise logistic regression selected four features from PSPR as predictors of PD. The final regression model built on the entire dataset provided an area under receiver operating characteristics curve (AUC) with 95% confidence interval of 0.90 [0.80, 0.99]. The five-fold cross-validation process produced an average AUC of 0.835 [0.831, 0.839]. We conclude that cardiac electrical activity provides important information about the likelihood of future PD not captured by classical HRV metrics. Machine learning applied to ECGs may help identify subjects at high risk of having prodromal PD.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Self-regulated growth of candidate topological superconducting parkerite by molecular beam epitaxy

Ternary chalcogenides, such as parkerites and shandites, are a broad class of materials exhibiting a rich diversity of transport and magnetic behavior and an array of topological phases, including Weyl and Dirac nodes. However, they remain largely unexplored as high-quality epitaxial thin films. Here, we report the self-regulated growth of thin films of the strong spin–orbit coupled superconductor Pd 3 Bi 2 Se 2 on SrTiO 3 by molecular beam epitaxy. Films are found to grow in a self-regulated fashion, where, in excess Se, the temperature and relative flux ratio of Pd to Bi control the formation of Pd 3 Bi 2 Se 2 due to the combined volatility of Bi, Se, and Bi–Se bonded phases. The resulting films are shown to be of high structural quality, and the stoichiometry is independent of the Pd:Bi and Se flux ratio and exhibits a superconducting transition temperature of 800 mK and a critical field of 17.7 ± 0.5 mT, as probed by transport and magnetometry. Understanding and navigating the growth of the chemically and structurally diverse classes of ternary chalcogenides open a vast space for discovering new phenomena and enabling new applications.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

The NINDS Parkinson's disease biomarkers program: The Ninds Parkinson's Disease Biomarkers Program

Background: Neuroprotection for Parkinson Disease (PD) remains elusive. Biomarkers hold the promise of removing roadblocks to therapy development. The National Institute of Neurological Disorders and Stroke (NINDS) has therefore established the Parkinson’s Disease Biomarkers Program (PDBP) to promote discovery of biomarkers for use in phase II-III clinical trials in PD. Methods: The PDBP facilitates biomarker development to improve neuroprotective clinical trial design, essential for advancing therapeutics for PD. To date, eleven consortium projects in the PDBP are focused on the development of clinical and laboratory-based PD biomarkers for diagnosis, progression tracking, and/or the prediction of prognosis. Seven of these projects also provide detailed longitudinal data and biospecimens from PD patients and controls, as a resource for all PD researchers. Standardized operating procedures and pooled reference samples have been created in order to allow cross-project comparisons and assessment of batch effects. A web-based Data Management Resource facilitates rapid sharing of data and biosamples across the entire PD research community for additional biomarker projects. Results: Here we describe the PDBP, highlight standard operating procedures for the collection of biospecimens and data, and provide an interim report with quality control analysis on the first 1082 participants and 1033 samples with quality control analysis collected as of October 2014. Conclusions: By making samples and data available to academics and industry, encouraging the adoption of existing standards, and providing a resource which complements existing programs, the PDBP will accelerate the pace of PD biomarker research, with the goal of improving diagnostic methods and treatment.

biofluids↗
DOE OSTI2025

Pd–Methyl Bond Energy─Property Correlations, Noncorrelations, Machine Learning Models, and Application to Polymerization Catalysis

Metal–carbon bonds are a key intermediate in a variety of homogeneous organometallic transformations and often determine the critical thermodynamics and kinetics of catalytic processes. Surprisingly, the influence of different ligands on metal–carbon bond strengths has been largely overlooked. Here, in this study, we evaluated nearly 700 experimental Pd–methyl complexes by calculating their bond dissociation energies using density functional theory (DFT) and compared these bond strengths to several fundamental molecular properties, and this revealed several surprising correlations and noncorrelations. Most surprising was that several fundamental properties, such as the bond length, bond force constant, and bond electron density, have no correlation with bond strength, despite these correlations often holding for main-group compounds. We were indeed able to identify key ligand-dependent chemical features/descriptors that provided a highly accurate machine learning model and provided insight into the general factors that control the Pd–carbon bond strength, such as radical delocalization and nucleophilicity. Insights gained from the Pd–Me bond energy analysis were then applied to CO migratory insertion steps that are part of copolymerization reactions.

binding energy↗
DOE OSTI2025

Mechanistic Insights into Adsorptive and Catalytic Reactions from Controllable Distributions of Metal Cations (Pd, Pt, Ni, Cr, Cu) as [M‐OH] +1 /1Al or M +2 /2Al in Zeolites

Anchoring divalent metal ions in the same zeolite framework with similar Si/Al ratio selectively as zeolite-bound M +2 or [M +2 -OH] +1 cationic species enables critical comparison of the species’ intrinsic reactivity for industrially and fundamentally relevant reactions. H-BEA zeolites with similar Si/Al ratios but differing framework Al siting were used to anchored multiple divalent metal cations (Ni, Pd, Pt, Cr, Cu) in the zeolite micropores. State-of-the-art infrared (IR) spectroscopy, electron paramagnetic resonance (EPR) measurements, including two-dimensional pulsed HYSCORE EPR, extended X-ray absorption fine structure (EXAFS), and density functional theory (DFT) calculations together provide unambiguous evidence for the selective formation of divalent metal cations as M +2 /2Al species (for H-BEA prepared in the conventional hydroxide media), and [M +2 OH] +1 /1Al species for H-BEA prepared in HF. Solid-state proton-decoupled triple-quantum magic-angle spinning (3Q MAS) NMR measurements confirmed contrasting Al distributions in the two H-BEA zeolites, which led to a contrasting divalent cation speciation. The reactivities of the two cationic species were explored for catalytic and adsorptive applications in both organometallic homogeneous and heterogeneous catalysis. This work demonstrates their divergent reactivity in ethylene dimerization, ethylene oxidation (Wacker process), selective catalytic reduction (SCR) of NO, NO adsorption, and methane oxidation. Both M +2 /2Al and [M +2 OH] +1 /1Al cations are both active for ethylene dimerization, but [M +2 OH] +1 /1Al species show higher reaction rates for each Pd, Ni, Pt. [M +2 OH] +1 /1Al is active for acetaldehyde formation in Wacker ethylene oxidation. A new active site for ethylene oligomerization is proposed that possesses a terminal OH group (Cr-OH) in Phillips catalysts evident by a nearly inactive isolated Cr +2 /2Al species that contrast an active Cr─OH motif.

Divalent metal cations in a zeolite↗
DOE OSTI2016

Ru nanoframes with an fcc structure and enhanced catalytic properties

Noble-metal nanoframes are of great interest to many applications due to their unique open structures. Among various noble metals, Ru has never been made into nanoframes. In this study, we report for the first time an effective method based on seeded growth and chemical etching for the facile synthesis of Ru nanoframes with high purity. The essence of this approach is to induce the preferential growth of Ru on the corners and edges of Pd truncated octahedra as the seeds by kinetic control. The resultant Pd–Ru core–frame octahedra could be easily converted to Ru octahedral nanoframes of ~2 nm in thickness by selectively removing the Pd cores through chemical etching. Most importantly, in this approach the face-centered cubic (fcc) crystal structure of Pd seeds was faithfully replicated by Ru that usually takes an hcp structure. Furthermore, the fcc Ru nanoframes showed higher catalytic activities toward the reduction of p-nitrophenol by NaBH 4 and the dehydrogenation of ammonia borane compared with hcp Ru nanowires with roughly the same thickness.

36 MATERIALS SCIENCE↗