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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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
NASA NTRS1996

Identification of Ser-543 as the major regulatory phosphorylation site in spinach leaf nitrate reductase

Spinach leaf NADH:nitrate reductase (NR) responds to light/dark signals and photosynthetic activity in part as a result of rapid regulation by reversible protein phosphorylation. We have identified the major regulatory phosphorylation site as Ser-543, which is located in the hinge 1 region connecting the cytochrome b domain with the molybdenum-pterin cofactor binding domain of NR, using recombinant NR fragments containing or lacking the phosphorylation site sequence. Studies with NR partial reactions indicated that the block in electron flow caused by phosphorylation also could be localized to the hinge 1 region. A synthetic peptide (NR6) based on the phosphorylation site sequence was phosphorylated readily by NR kinase (NRk) in vitro. NR6 kinase activity tracked the ATP-dependent inactivation of NR during several chromatographic steps and completely inhibited inactivation/phosphorylation of native NR in vitro. Two forms of NRk were resolved by using anion exchange chromatography. Studies with synthetic peptide analogs indicated that both forms of NRk had similar specificity determinants, requiring a basic residue at P-3 (i.e., three amino acids N-terminal to the phosphorylated serine) and a hydrophobic residue at P-5. Both forms are strictly calcium dependent but belong to distinct families of protein kinases because they are distinct immunochemically.

NASA Discipline Plant Biology↗
NASA NTRS1997

The Quantum Yield of NO3 from Peroxyacetyl Nitrate Photolysis

Peroxyacetyl nitrate (PAN) vapor was photolyzed at 248nm and the NO3 photoproduct was detected by laser induced fluorescence. The excited state flourescence contributions were investigated and a data analysis methodology was established to minimize their effects.

Peroxyacetyl Nitrate Photolysis↗
NASA NTRS1994

Profiles of Stratospheric Chlorine Nitrate from ATMOS/ATLAS 1 Infrared Solar Occultation Spectra

Stratospheric volume mixing ration profiles of chlorine nitrate have been retrieved from 0.01-cm(sub -1) resolution infrared solar occutation spectra recorded at latitudes between 14 degrees N and 54 degrees S by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer during the ATLAS 1 shuttle mission (March 24 to April 2, 1992).

chlorine nitrate ATMOS/ATLAS spectroscopic paramet↗
NASA NTRS2014

Determination of Ammonia Oxidizing Bacteria and Nitrate Oxidizing Bacteria in Wastewater and Bioreactors

The process of water purification has many different physical, chemical, and biological processes. One part of the biological process is the task of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB). Both play critical roles in the treatment of wastewater by oxidizing toxic compounds. The broad term is nitrification, a naturally occurring process that is carried out by AOB and NOB by using oxidation to convert ammonia to nitrite and nitrite to nitrate. To monitor this biological activity, bacterial staining was performed on wastewater contained in inoculum tanks and biofilm samples from bioreactors. Using microscopy and qPCR, the purpose of this experiment was to determine if the population of AOB and NOB in wastewater and membrane bioreactors changed depending on temperature and hibernation conditions to determine the optimal parameters for AOB/NOB culture to effectively clean wastewater.

Bioreactors↗
DOE OSTI2023

Supramolecular Enhancement of Electrochemical Nitrate Reduction Catalyzed by Cobalt Porphyrin Organic Cages for Ammonia Electrosynthesis in Water**

Abstract The electrochemical nitrate (NO 3 − ) reduction reaction (NO 3 RR) to ammonia (NH 3 ) represents a sustainable approach for denitrification to balance global nitrogen cycles and an alternative to traditional thermal Haber‐Bosch processes. Here, we present a supramolecular strategy for promoting NH 3 production in water from NO 3 RR by integrating two‐dimensional (2D) molecular cobalt porphyrin ( CoTPP ) units into a three‐dimensional (3D) porous organic cage architecture. The porphyrin box CoPB‐C8 enhances electrochemical active site exposure, facilitates substrate–catalyst interactions, and improves catalyst stability, leading to turnover numbers and frequencies for NH 3 production exceeding 200,000 and 56 s −1 , respectively. These values represent a 15‐fold increase in NO 3 RR activity and 200‐mV improvement in overpotential for the 3D CoPB‐C8 box structure compared to its 2D CoTPP counterpart. Synthetic tuning of peripheral alkyl substituents highlights the importance of supramolecular porosity and cavity size on electrochemical NO 3 RR activity. These findings establish the incorporation of 2D molecular units into 3D confined space microenvironments as an effective supramolecular design strategy for enhancing electrocatalysis.

An, Lun↗
DOE OSTI2023

Supramolecular Enhancement of Electrochemical Nitrate Reduction Catalyzed by Cobalt Porphyrin Organic Cages for Ammonia Electrosynthesis in Water**

Abstract The electrochemical nitrate (NO 3 − ) reduction reaction (NO 3 RR) to ammonia (NH 3 ) represents a sustainable approach for denitrification to balance global nitrogen cycles and an alternative to traditional thermal Haber‐Bosch processes. Here, we present a supramolecular strategy for promoting NH 3 production in water from NO 3 RR by integrating two‐dimensional (2D) molecular cobalt porphyrin ( CoTPP ) units into a three‐dimensional (3D) porous organic cage architecture. The porphyrin box CoPB‐C8 enhances electrochemical active site exposure, facilitates substrate–catalyst interactions, and improves catalyst stability, leading to turnover numbers and frequencies for NH 3 production exceeding 200,000 and 56 s −1 , respectively. These values represent a 15‐fold increase in NO 3 RR activity and 200‐mV improvement in overpotential for the 3D CoPB‐C8 box structure compared to its 2D CoTPP counterpart. Synthetic tuning of peripheral alkyl substituents highlights the importance of supramolecular porosity and cavity size on electrochemical NO 3 RR activity. These findings establish the incorporation of 2D molecular units into 3D confined space microenvironments as an effective supramolecular design strategy for enhancing electrocatalysis.

An, Lun↗
DOE OSTI2020

Evidence of Alpha Radiolysis in the Formation of a Californium Nitrate Complex

Well-characterized complexes of transplutonium elements are scarce because of the experimental challenges of working with these elements and the rarity of the isotopes. This leads to a lack of structural and spectroscopic data needed to understand the nature of chemical bonds in these compounds. In this work, the synthesis of Cf(DOPO q ) 2 (NO 3 )(py) (DOPO q =2,4,6,8-tetra-tert-butyl-1-oxo-1H-phenoxazin-9-olate; py=pyridine) is reported, in which the nitrate anion is hypothesized to form through the α-radiolysis-induced reaction of pyridine and/or the ligand. Here, computational analysis of the electronic structure of the complex reveals that the Cf III –ligand interactions are largely ionic.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

In‐operando crystallization study of zinc nitrate hexahydrate using zinc oxide nucleators

Abstract Supercooling (∆T Sup ) is one of the crucial problems in utilizing a phase change material (PCM), which has been attempted to overcome using nucleators possessing small lattice disregistry without comprehensive understanding of the nucleation phenomenon. Here, this work studies the interactions between nucleators and PCM via in‐operando direct visualization for the first time, to the best of our knowledge, to better understand the crystallization process during freezing of a PCM using zinc nitrate hexahydrate (ZNH) and a zinc oxide (ZnO) nucleator. According to our in‐operando study, freezing was randomly initiated by only a fraction of the nucleator particles during each thermal cycling. However, previously unresponsive nucleators also suddenly crystalized PCM when the propagating crystal encountered them, improving the crystal initiation and thereby ∆T Sup . Consequently, for equal wt% of ZnO, better nucleation behavior was obtained using uniformly distributed small nucleator particles throughout the PCM, as compared to either large or poorly distributed aggregated nucleators. DSC results using ZnO‐needle as nucleator confirmed a 38% and 33.3% lower ∆T Sup upon employing 5 wt% small (individual) particles (~4 μm on average), as compared to using equal wt% of small (aggregated) particle clusters (~200 μm) and large particles (~46 μm), respectively. Crystallization of ZNH caused additional hair‐like ZnO growth preferentially decorated along lateral faces of the original nucleator particles. The in‐operando studies are valuable tools to correlate inherent crystallization phenomena to the practical thermal energy storage properties of the system.

Chakraborty, Anirban↗
DOE OSTI2022

Unveiling real‐time crystallization with nucleators and thickeners for zinc nitrate hexahydrate as a phase change material

Abstract The primary challenge of salt hydrates as phase change materials (PCMs) is their high degree of supercooling (∆ T Sup ). Past studies have attempted to alleviate ∆ T Sup by incorporating nucleators possessing similar lattice structure, without a thorough analysis of the nucleator/PCM interactions. This work presents a novel in‐operando study to visually observe the crystallization process of zinc nitrate hexahydrate (ZNH) in real‐time using suitable nucleators and a thickener. We have introduced a new dataset where zinc acetate dihydrate (ZnAc.2H) has been employed as an additive to ZNH for thermal energy storage (TES). According to our in‐operando study, ZnAc.2H underwent hydrolysis in molten ZNH to precipitate needle‐like ZnO particles, which acted as nucleators for the PCM. In the absence of a thickener, the crystal propagation of ZNH exhibited a preferential directional tendency, whereas incorporation of thickener made the phase change process uniform along all directions. Self‐hydrolysis of ZnAc.2H generated excess water which caused the undesirable effect of broadening the endothermic peak. The addition of carboxymethyl cellulose (CMC) thickener could restrict the activity of excess water and reduce the broadening of the endothermic peak. Differential scanning calorimetry (DSC) revealed that 5 wt% ZnAc.2H additive and 2 wt% CMC thickener added to ZNH can considerably improve the TES properties of ZNH PCM (∆ H Fusion 125.9 J·g −1 , ∆ T Sup 3.0°C, melting point [M.P.] 29.0°C). Our in‐operando studies can unveil real‐time phase change behaviors to better design PCM systems with desired characteristics.

Chakraborty, Anirban↗
DOE OSTI2023

Electric field gradients at rubidium sites in rubidium uranyl nitrate and quadrupole moments of 85 Rb and 87 Rb

The electronic structure along the axial direction of the uranyl ion in rubidium uranyl nitrate (RbUO 2 (NO 3 ) 3 ) has been studied by nuclear quadrupole resonance and nuclear magnetic resonance measurements of 85 Rb and 87 Rb quadrupole couplings. Here, the parameter of interest in these experiments is the electric field gradient at the Rb sites, which may be compared with values com- puted by various theoretical approaches. From this analysis an accurate ratio of the quadrupole moments of 85 Rb and 87 Rb has also been obtained.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Periodic Trends within Actinyl(VI) Nitrates and Their Structures, Vibrational Spectra, and Electronic Properties

In this work, a series of actinyl(VI) nitrate salts of the form MAnO 2 (NO 3 ) 3 , where M = NH 4 + K + , Rb + , Cs + , and Me 4 N + and AnO 2 2+ = U, Np, Pu, and AnO 2 (NO 3 ) 2 (H 2 O) 2 ·H 2 O, and the uranyl tetranitrates M 2 UO 2 (NO 3 ) 4 have been synthesized from aqueous solution and their structures determined using single-crystal X-ray diffraction. Together, these complexes represent an isostructural series of actinide complexes among the salts crystallized with the same charge-compensating cation and have been studied using vibrational spectroscopy including Raman and Fourier-transform infrared. Periodic trends in both the structural properties of these complexes and their vibrational spectra are presented and discussed, in particular the invariant nature of the O≡An≡O asymmetric stretching frequencies observed across the actinyl series. Electronic structure calculations were performed at a variety of levels of theory to aid in the interpretation of the vibrational data and to correlate trends in the data with the underlying electronic properties of these molecules.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Synthesis of an Isostructural Series of 12-Coordinate Lanthanide Nitrate Hybrid Double Perovskites with Cubic Symmetry

In efforts to study the periodic chemical properties of the rare earth elements and their structural chemistry, a hybrid double perovskite phase A 2 B'BX 6 with the formula ((CH 3 ) 4 N) 2 KLn(NO 3 ) 6 (Ln = La–Lu, Y ex. Pm) was synthesized that crystallizes in the cubic space group, $Fm$$\bar{3}$$m$. This series was obtained via evaporative crystallization from a mixture of Ln(NO 3 ) 3 , KNO 3 , and (CH 3 ) 4 N·NO 3 in a 1:1:2 ratio from either H 2 O or 4.0 M HNO 3 . In this double perovskite structure, the B site containing the lanthanide ion is coordinated by six bidentate nitrate ligands, with the distal N$=$O oxygen atoms coordinating the potassium on the B' site in an octahedral six-coordinate environment. The two-remaining charge-compensating (CH 3 ) 4 N + cations occupy the interstitial voids in the lattice on the A site. This periodic series was characterized via single-crystal X-ray diffraction, powder X-ray diffraction, IR, and Raman spectroscopy. Emission spectra of the Eu complex indicate a phase transition to trigonal symmetry upon cooling. In conclusion, this series is unique as it represents a rare isostructural series spanning the entirety of the rare earth elements excluding promethium with homoleptic 12-coordinate rare earth metal ions.

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

Rare Earth Nitrate Hybrid Double Perovskites [Me 4 N] 2 [MLn(NO 3 ) 6 ] (M = Na–Cs; Ln = La–Gd, ex. Pm)

An exploration of the synthetic and structural phase space of rare earth hybrid double perovskites A 2 B'BX 6 (A = organocation, B' = M + , B = M 3+ , X = molecular bridging anion) that include X = NO 3 – and B' = alkali metal is reported, complementing earlier studies of the [Me 4 N] 2 [KB(NO 3 ) 6 ] (B = Am, Cm, La–Nd, Sm–Lu, Y) (Me 4 N = (CH 3 ) 4 N + ) compounds. In the present efforts, the synthetic phase space of these systems is explored by varying the identity of the alkali metal ion at the B'-site. Herein, we report three new series of the form [Me 4 N] 2 [B'B(NO 3 ) 6 ] (B = La–Nd, Sm–Gd; B' = Na, Rb, Cs). The early members of the Na-series crystallize in the trigonal space group R3̅ from La to Nd where a phase transition occurs in the phase between 273 and 300 K, going from R3̅ to the high-symmetry, cubic space group Fm3̅m. The preceding trigonal members of the Na-series also undergo phase transitions to cubic symmetry at temperatures above 300 K, establishing a decreasing trend in the phase-transition temperature. The remainder of the Na-series, as well as the Rb- and Cs-series, all crystallize in Fm3̅m at 300 K. The temperature-dependent phase behavior of the synthesized phases is studied via variable-temperature spectroscopic methods and high-resolution powder X-ray diffractometry. All phases were characterized via single-crystal and powder X-ray diffraction and Fourier transform infrared (FT-IR) and Raman spectroscopic methods. These results demonstrate the versatility of the perovskite structure type to include rare earth ions, nitrate ions, and a suite of alkali metal ions and serve as a foundation for the design of functional rare earth hybrid double perovskite materials such as those possessing useful multiferroic, optical, and magnetic properties.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Thermal and Catalytic Decomposition of 2-Hydroxyethylhydrazine and 2-Hydroxyethylhydrazinium Nitrate Ionic Liquid

To develop chemical kinetics models for the combustion of ionic liquid-based monopropellants, identification of the elementary steps in the thermal and catalytic decomposition of components such as 2-hydroxyethylhydrazinium nitrate (HEHN) is needed but is currently not well understood. The first decomposition step in protic ionic liquids such as HEHN is typically the proton transfer from the cation to the anion, resulting in the formation of 2-hydroxyethylhydrazine (HEH) and HNO 3 . In the first part of this investigation, the high-temperature thermal decomposition of HEH is probed with flash pyrolysis (<1400 K) and vacuum ultraviolet (10.45 eV) photoionization time-of-flight mass spectrometry (VUV-PI-TOFMS). Next, the investigation into the thermal and catalytic decomposition of HEHN includes two mass spectrometric techniques: (1) tunable VUV-PI-TOFMS (7.4-15 eV) and (2) ambient ionization mass spectrometry utilizing both plasma and laser ionization techniques whereby HEHN is introduced onto a heated inert or iridium catalytic surface and the products are probed. The products can be identified by their masses, their ionization energies, and their collision-induced fragmentation patterns. Further, formation of product species indicates that catalytic surface recombination is an important reaction process in the decomposition mechanism of HEHN. The products and their possible elementary reaction mechanisms are discussed.

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

DFT Analysis of the Binding of Rare Earth Nitrates at Internal and External Surfaces of MCM-22

MCM-22-type zeolites constitute a well-characterized tunable class of aluminosilicates suitable for elucidating the fundamental aspects of the binding of rare earth elements (REEs) in layered materials. Starting from the pure silica version ITQ-1 with a unit cell of Si 72 O 144 , a model for periodic bulk crystalline MCM-22 with a finite Al concentration is provided by replacing a Si atom with an Al atom in the unit cell at suitable tetrahedral sites near an internal pore surface. Then, a H atom is added to an O atom bridging Si and Al atoms to create a Brønsted acid site (BAS). There are no internal silanol groups in this bulk model. To generate a model for an external surface, we adopt the fully hydroxylated surface structure of a layer within the ITQ-1 precursor with two silanols per lateral unit cell. A BAS on the external surface can be generated by replacing a near-surface Si atom with an Al atom and adding a H atom, as above. The strength of binding at a BAS of REE, X, taken to be present in the solution phase as nitrates, is determined from the energy change in the reaction X(NO 3 ) 3 + ≡Si–{OH}–Al≡ → ≡Si–{OX(NO 3 ) 2 }–Al≡+ HNO 3 . The strength of binding at the silanols is determined similarly. Binding energies are determined from two approaches. The first performs periodic plane-wave density functional theory (DFT) total energy analysis for an entire unit cell of MCM-22. The second utilizes cluster models capturing the local environment of REE binding sites and performs DFT analysis with localized basis sets. The two approaches yield consistent results for Nd, revealing similarly strong binding at either an external or internal BAS, but much weaker binding at a silanol site. This is consistent with the picture deduced from recent experiments. Here, we also comment on binding at Al-bridged siloxane sites, which have been suggested as alternative binding sites to BAS.

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

Understanding Trigger Linkage Dynamics in Energetic Materials Using Mixed Picramide Nitrate Ester Explosives

The ability to predict the handling sensitivity of new organic energetic materials has been a longstanding goal. We report the synthesis and characterization of six new nitropicramide energetic materials with mixed functional groups that mimic known explosives such as nitroglycerin, erythritol tetranitrate (ETN), and pentaerythritol tetranitrate (PETN). The molecules have been studied theoretically using quantum molecular dynamics (QMD) simulations and density functional theory (DFT) calculations to identify the weakest bond in the reactants - the trigger-linkages - which control handling sensitivity, and to quantify their specific enthalpies of explosion. In good accord with the drop weight impact sensitivity data, our calculations predict that the sensitivities of the molecules are very similar owing to the small variations of the energy output and rates of trigger linkage rupture. In addition, both the QMD and DFT calculations point to the nitropicramide N–NO 2 bonds as the trigger linkages rather than the more typical O–NO 2 bonds. We propose that the switch of the trigger linkage from the nitrate esters to the nitramine groups arises from the strongly electron withdrawing character of the adjacent trinitrobenzene groups.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗