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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 OSTI2025

Investigating the quaternary structure of a homomultimeric catechol 1,2-dioxygenase: An integrative structural biology study

The structural analysis of catechol 1,2 dioxygenase from Stutzerimonas frequens GOM2, SfC12DO, was conducted using various structural techniques. SEC-SAXS experiments revealed that SfC12DO, after lyophilization and reconstitution processes, can form multiple enzymatically active oligomers, including dimers, tetramers, and octamers. These findings differ from previous studies, which reported active dimers in homologous counterparts with available crystallographic structures, or trimers observed exclusively in solution for SfC12DO and its homologous isoA C12DO from Acinetobacter radioresistens under low ionic strength conditions. In some cases, tetramers were also reported, such as for the Rodococcus erythropolis C12DO. The combined results of Small-Angle X-ray Scattering, Dynamic Light Scattering, and Transmission Electron Microscopy experiments provided additional insights into these active oligomers’ shape and molecular organization in an aqueous solution. These results highlight the oligomeric structural plasticity of SfC12DO, proving that it can exist in different oligomeric forms depending on the physicochemical characteristics of the solutions in which the experiments were performed. Remarkably, regardless of its oligomeric state, SfC12DO maintains its enzymatic activity even after prior lyophilization. All these characteristics make SfC12DO a putative candidate for bioremediation applications in polluted soils or waters.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1974

Brain catechol synthesis - Control by brain tyrosine concentration

Brain catechol synthesis was estimated by measuring the rate at which brain dopa levels rose following decarboxylase inhibition. Dopa accumulation was accelerated by tyrosine administration, and decreased by treatments that lowered brain tyrosine concentrations (for example, intraperitoneal tryptophan, leucine, or parachlorophenylalanine). A low dose of phenylalanine elevated brain tyrosine without accelerating dopa synthesis. Our findings raise the possibility that nutritional and endocrine factors might influence brain catecholamine synthesis by controlling the availability of tyrosine.

Wurtman, R. J.↗
DOE OSTI2019

Mussel-Inspired Hydrogel Composite with Multi-Stimuli Responsive Behavior

A mussel-inspired adhesive hydrogel with pH, temperature, and near-infrared (NIR) light–responsive behavior is designed here. The hydrogel system is formulated by combining chitosan modified with catechol motifs, thermo-responsive poly(N-isopropylacrylamide) terminated with catechols, and light-absorbing polypyrrole nanoparticles (PpyNPs). The effects of catechol concentration, molar ratio of Fe 3+ to catechol units, pH, and the incorporation of the PpyNPs on the mechanical property of the formed hydrogel are investigated. The responsive behaviors of the resulting hydrogel composite to pH, temperature, and NIR light are also demonstrated. The obtained hydrogel also shows promising adhesive property to glass and steel substrates. It is anticipated that the fabricated adhesive hydrogel with multi-responsive behavior, especially NIR light response, can potentially be useful in a wide range of biomedical applications, such as remotely controlled release systems and removable sealant materials.

42 ENGINEERING↗
DOE OSTI2023

Bioconversion of Homogeneous Linear C-Lignin to Polyhydroxyalkanoates

Here, the bioconversion of homogeneous linear catechyl lignin (C-lignin) to polyhydroxyalkanoates (PHA) was examined for the first time in this study. C-lignins from vanilla, euphorbia, and candlenut seed coats (denoted as C1, C2, and C3, respectively) varied in their molecular structures, which showed different molecular weight distributions, etherification degrees, and contents of hydroxyl groups. A notable amount of nonetherified catechol units existed within C1 and C2 lignins, and these catechol units were consumed during fermentation. These results suggested that the nonetherified catechol structure was readily converted by Pseudomonas putida KT2440. Since the weight-average molecular weight of C2 raw lignin was 26.7% lower than that of C1, the bioconversion performance of C2 lignin was more outstanding. The P. putida KT2440 cell amount reached the maximum of 9.3 × 10 7 CFU/mL in the C2 medium, which was 37.9 and 82.4% higher than that in the C1 and C3 medium, respectively. Accordingly, PHA concentration reached 137 mg/L within the C2 medium, which was 41.2 and 149.1% higher than the C1 and C3 medium, respectively. Overall, C-lignin, with a nonetherified catechol structure and low molecular weight, benefits its microbial conversion significantly.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Rational Design of a Multifunctional Binder for High-Capacity Silicon-Based Anodes

Although several principles have been recognized to fabricate a nominal "better" binder, there continues to be a lack of a rational design and synthesis approach that would meet the robust criteria required for silicon (Si) anodes. Herein, we report a synthetic polymer binder, i.e., catechol-functionalized chitosan cross-linked by glutaraldehyde (CS-CG+GA), that serves dual functionalities: (a) wetness-resistant adhesion capability via catechol grafting and (b) mechanical robustness via in situ formation of a three-dimensional (3D) network. A SiNP-based anode with a designed functional polymer network (CS-CG10%+6%GA) exhibits a capacity retention of 91.5% after 100 cycles (2144 +/- 14 mAh/g). Properties that are traditionally considered to be advantageous, including stronger adhesion strength and higher mechanical robustness, do not always improve the binder performance. A clear relationship between these properties and ultimate electrochemical performance is established by assessing the rheological behavior, mechanical property, adhesion force, peel stress, morphology evolution, and semiquantitative evaluation. This study provides a clear path for the rational design of high-performance functional polymer binders for not only Si-based electrodes but also other types of alloy and conversion-based electrodes.

Cao, Peng-Fei↗
DOE OSTI2018

Nuclear Resonance Vibrational Spectroscopy Definition of O 2 Intermediates in an Extradiol Dioxygenase: Correlation to Crystallography and Reactivity

The extradiol dioxygenases are a large subclass of mononuclear nonheme Fe enzymes that catalyze the oxidative cleavage of catechols distal to their OH groups. These enzymes are important in bioremediation, and there has been significant interest in understanding how they activate O 2 . The extradiol dioxygenase homoprotocatechuate 2,3-dioxygenase (HPCD) provides an opportunity to study this process, as two O 2 intermediates have been trapped and crystallographically defined using the slow substrate 4-nitrocatechol (4NC): a side-on Fe–O 2 –4NC species and a Fe–O 2 –4NC peroxy bridged species. Also with 4NC, two solution intermediates have been trapped in the H200N variant, where H200 provides a second-sphere hydrogen bond in the wild-type enzyme. While the electronic structure of these solution intermediates has been defined previously as Fe III -superoxo-catecholate and Fe III -peroxy-semiquinone, their geometric structures are unknown. Nuclear resonance vibrational spectroscopy (NRVS) is an important tool for structural definition of nonheme Fe–O 2 intermediates, as all normal modes with Fe displacement have intensity in the NRVS spectrum. In this study, NRVS is used to define the geometric structure of the H200N–4NC solution intermediates in HPCD as an end-on Fe III -superoxo-catecholate and an end-on Fe III -hydroperoxo-semiquinone. Parallel calculations are performed to define the electronic structures and protonation states of the crystallographically defined wild-type HPCD–4NC intermediates, where the side-on intermediate is found to be a Fe III -hydroperoxo-semiquinone. The assignment of this crystallographic intermediate is validated by correlation to the NRVS data through computational removal of H200. While the side-on hydroperoxo semiquinone intermediate is computationally found to be nonreactive in peroxide bridge formation, it is isoenergetic with a superoxo catecholate species that is competent in performing this reaction. In conclusion, this study provides insight into the relative reactivities of Fe III -superoxo and Fe III -hydroperoxo intermediates in nonheme Fe enzymes and into the role H200 plays in facilitating extradiol catalysis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Interactive Materials for Bidirectional Redox-Based Communication

Emerging research indicates that biology routinely uses diffusible redox-active molecules to mediate communication that can span biological systems (e.g., nervous and immune) and even kingdoms (e.g., a microbiome and its plant/animal host). This redox modality also provides new opportunities to create interactive materials that can communicate with living systems. Here in this paper, it is reported that the fabrication of a redox-active hydrogel film can autonomously synthesize a H 2 O 2 signaling molecule for communication with a bacterial population. Specifically, a catechol-conjugated/crosslinked 4-armed thiolated poly(ethylene glycol) hydrogel film is electrochemically fabricated in which the added catechol moieties confer redox activity: the film can accept electrons from biological reductants (e.g., ascorbate) and donate electrons to O 2 to generate H 2 O 2 . Electron-transfer from an Escherichia coli culture poises this film to generate the H 2 O 2 signaling molecule that can induce bacterial gene expression from a redox-responsive operon. Overall, this work demonstrates that catecholic materials can participate in redox-based interactions that elicit specific biological responses, and also suggests the possibility that natural phenolics may be a ubiquitous biological example of interactive materials.

electrobiofabrication↗
DOE OSTI2023

Understanding the influence of solvents on the Pt-catalyzed hydrodeoxygenation of guaiacol

Bio-oil derived from fast pyrolysis of lignocellulosic biomass needs to be deoxygenated to become a substitute for petroleum fuels. Here, we study the hydrodeoxygenation mechanism of guaiacol, a bio-oil model compound derived from the lignin fraction of biomass, on Pt(1 1 1) terrace sites in the presence of water, diethyl ether, 1-butanol, and n-hexane as solvent. Using first-principles periodic density functional theory (DFT) calculations and mean-field microkinetic reactor modeling, a detailed reaction mechanism is investigated targeting various products such as catechol, phenol, anisole, benzene, cyclohexanone, and cyclohexanol. Solvent phase DFT outcomes are mostly similar to that of the vapor phase; however, microkinetic modeling results suggest that rate controlling species and transition states differ somewhat in the various reaction environments. Catechol was found to be the major aromatic product across all reaction environments. Over Pt(1 1 1), unsaturated monooxygenate production from catechol is unlikely.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Corrosion Susceptibility of Cr–Mo Steels and Ferritic Stainless Steels in Biomass-Derived Pyrolysis Oil Constituents

In this work, to better understand and evaluate the corrosion performance of candidate structural steels and ferritic stainless steels for production, transport, and storage of biomass pyrolysis oils, corrosion studies were conducted in selected organic constituents of bio-oils, including catechol, formic acid, and their mixtures as well as lactobionic acid, using electrochemical impedance spectroscopy. R 2 , the resistance against corrosion reaction, was obtained by fitting measured impedance spectra into an equivalent circuit. The values of R 2 were then used to assess corrosion resistance of the steels in each organic constituent and mixture. Type 410 and 430 stainless steels were resistant to corrosion in all tested organic constituents, while 2.25Cr-1Mo steel was not. 9Cr-1Mo steel was corrosion resistant in catechol but not in the other mixtures that contained organic acids. On the basis of the results of this work, it is suggested that the corrosion resistance against organic acids is attributed to formation of a Cr-rich passive film that requires stainless steels with critical Cr levels in excess of approximately 11 wt %. In catechol-only solution, lower levels of Cr intermediate between that of 2.25Cr-1Mo steel and 9Cr-1Mo steel appeared sufficient.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Tuning the zeolite acidity enables selectivity control by suppressing ketene formation in lignin catalytic pyrolysis

Unveiling catalytic mechanisms at a molecular level aids rational catalyst design and selectivity control for process optimization. In this study, we find that the Brønsted acid site density of the zeolite catalyst efficiently controls the guaiacol catalytic pyrolysis mechanism. Guaiacol demethylation to catechol initiates the reaction, as evidenced by the detected methyl radicals. The mechanism branches to form either fulvenone (c-C 5 H 4 = C = O), a reactive ketene intermediate, by catechol dehydration, or phenol by acid-catalyzed dehydroxylation. At high Brønsted acid site density, fulvenone formation is inhibited due to surface coordination configuration of its precursor, catechol. By quantifying reactive intermediates and products utilizing operando photoelectron photoion coincidence spectroscopy, we find evidence that ketene suppression is responsible for the fivefold phenol selectivity increase. Complementary fulvenone reaction pathway calculations, along with 29 Si NMR-MAS spectroscopy results corroborate the mechanism. The proposed, flexible operando approach is applicable to a broad variety of heterogeneous catalytic reactions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗