Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Ac”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Ac2YbMg by Materials Project

MgAc2Yb is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Mg is bonded in a body-centered cubic geometry to eight equivalent Ac atoms. All Mg–Ac bond lengths are 3.65 Å. Ac is bonded in a distorted body-centered cubic geometry to four equivalent Mg and four equivalent Yb atoms. All Ac–Yb bond lengths are 3.65 Å. Yb is bonded in a body-centered cubic geometry to eight equivalent Ac atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li2AcAl by Materials Project

Li2AcAl is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Li is bonded in a body-centered cubic geometry to four equivalent Ac and four equivalent Al atoms. All Li–Ac bond lengths are 3.12 Å. All Li–Al bond lengths are 3.12 Å. Ac is bonded in a distorted body-centered cubic geometry to eight equivalent Li and six equivalent Al atoms. All Ac–Al bond lengths are 3.60 Å. Al is bonded in a distorted body-centered cubic geometry to eight equivalent Li and six equivalent Ac atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AcSnPd2 by Materials Project

AcPd2Sn is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Ac is bonded in a body-centered cubic geometry to eight equivalent Pd and six equivalent Sn atoms. All Ac–Pd bond lengths are 3.12 Å. All Ac–Sn bond lengths are 3.60 Å. Pd is bonded in a body-centered cubic geometry to four equivalent Ac and four equivalent Sn atoms. All Pd–Sn bond lengths are 3.12 Å. Sn is bonded in a distorted body-centered cubic geometry to six equivalent Ac and eight equivalent Pd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ac2CuRu by Materials Project

Ac2RuCu is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Ac is bonded in a body-centered cubic geometry to four equivalent Ru and four equivalent Cu atoms. All Ac–Ru bond lengths are 3.23 Å. All Ac–Cu bond lengths are 3.23 Å. Ru is bonded in a body-centered cubic geometry to eight equivalent Ac atoms. Cu is bonded in a body-centered cubic geometry to eight equivalent Ac atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AcZn2Cd by Materials Project

AcCdZn2 is Heusler 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 six equivalent Cd and eight equivalent Zn atoms. All Ac–Cd bond lengths are 3.65 Å. All Ac–Zn bond lengths are 3.16 Å. Cd is bonded in a 8-coordinate geometry to six equivalent Ac and eight equivalent Zn atoms. All Cd–Zn bond lengths are 3.16 Å. Zn is bonded in a body-centered cubic geometry to four equivalent Ac and four equivalent Cd atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AcRh2Pb by Materials Project

AcRh2Pb is Heusler 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 eight equivalent Rh and six equivalent Pb atoms. All Ac–Rh bond lengths are 3.07 Å. All Ac–Pb bond lengths are 3.55 Å. Rh is bonded in a distorted body-centered cubic geometry to four equivalent Ac and four equivalent Pb atoms. All Rh–Pb bond lengths are 3.07 Å. Pb is bonded in a 8-coordinate geometry to six equivalent Ac and eight equivalent Rh atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AcSm3 by Materials Project

AcSm3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Ac is bonded to twelve Sm atoms to form AcSm12 cuboctahedra that share corners with six equivalent AcSm12 cuboctahedra, corners with twelve SmAc4Sm8 cuboctahedra, edges with eighteen SmAc4Sm8 cuboctahedra, faces with eight equivalent AcSm12 cuboctahedra, and faces with twelve SmAc4Sm8 cuboctahedra. There are six shorter (3.73 Å) and six longer (3.76 Å) Ac–Sm bond lengths. There are three inequivalent Sm sites. In the first Sm site, Sm is bonded to four equivalent Ac and eight Sm atoms to form SmAc4Sm8 cuboctahedra that share corners with four equivalent AcSm12 cuboctahedra, corners with fourteen SmAc4Sm8 cuboctahedra, edges with six equivalent AcSm12 cuboctahedra, edges with twelve SmAc4Sm8 cuboctahedra, faces with four equivalent AcSm12 cuboctahedra, and faces with sixteen SmAc4Sm8 cuboctahedra. There are a spread of Sm–Sm bond distances ranging from 3.63–3.82 Å. In the second Sm site, Sm is bonded to four equivalent Ac and eight Sm atoms to form SmAc4Sm8 cuboctahedra that share corners with four equivalent AcSm12 cuboctahedra, corners with fourteen SmAc4Sm8 cuboctahedra, edges with six equivalent AcSm12 cuboctahedra, edges with twelve SmAc4Sm8 cuboctahedra, faces with four equivalent AcSm12 cuboctahedra, and faces with sixteen SmAc4Sm8 cuboctahedra. There are a spread of Sm–Sm bond distances ranging from 3.63–3.82 Å. In the third Sm site, Sm is bonded to four equivalent Ac and eight Sm atoms to form SmAc4Sm8 cuboctahedra that share corners with four equivalent AcSm12 cuboctahedra, corners with fourteen SmAc4Sm8 cuboctahedra, edges with six equivalent AcSm12 cuboctahedra, edges with twelve SmAc4Sm8 cuboctahedra, faces with four equivalent AcSm12 cuboctahedra, and faces with sixteen SmAc4Sm8 cuboctahedra. There are one shorter (3.63 Å) and one longer (3.82 Å) Sm–Sm bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca3Ac by Materials Project

Ca3Ac is alpha bismuth trifluoride structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. there are two inequivalent Ca sites. In the first Ca site, Ca is bonded in a body-centered cubic geometry to four equivalent Ca and four equivalent Ac atoms. All Ca–Ca bond lengths are 3.80 Å. All Ca–Ac bond lengths are 3.80 Å. In the second Ca site, Ca is bonded in a 8-coordinate geometry to eight equivalent Ca and six equivalent Ac atoms. All Ca–Ac bond lengths are 4.38 Å. Ac is bonded in a distorted body-centered cubic geometry to fourteen Ca atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AcInAg2 by Materials Project

AcAg2In is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Ac is bonded in a body-centered cubic geometry to eight equivalent Ag and six equivalent In atoms. All Ac–Ag bond lengths are 3.22 Å. All Ac–In bond lengths are 3.72 Å. Ag is bonded in a body-centered cubic geometry to four equivalent Ac and four equivalent In atoms. All Ag–In bond lengths are 3.22 Å. In is bonded in a distorted body-centered cubic geometry to six equivalent Ac and eight equivalent Ag atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ac2MgTl by Materials Project

MgAc2Tl is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Mg is bonded in a body-centered cubic geometry to eight equivalent Ac atoms. All Mg–Ac bond lengths are 3.58 Å. Ac is bonded in a body-centered cubic geometry to four equivalent Mg and four equivalent Tl atoms. All Ac–Tl bond lengths are 3.58 Å. Tl is bonded in a body-centered cubic geometry to eight equivalent Ac atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba3Ac by Materials Project

Ba3Ac is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. there are two inequivalent Ba sites. In the first Ba site, Ba is bonded to eight Ba and four equivalent Ac atoms to form BaBa8Ac4 cuboctahedra that share corners with twelve equivalent BaBa8Ac4 cuboctahedra, edges with eight equivalent AcBa12 cuboctahedra, edges with sixteen BaBa8Ac4 cuboctahedra, faces with four equivalent AcBa12 cuboctahedra, and faces with fourteen BaBa8Ac4 cuboctahedra. There are four shorter (4.29 Å) and four longer (4.34 Å) Ba–Ba bond lengths. All Ba–Ac bond lengths are 4.34 Å. In the second Ba site, Ba is bonded to eight equivalent Ba and four equivalent Ac atoms to form BaBa8Ac4 cuboctahedra that share corners with four equivalent BaBa8Ac4 cuboctahedra, corners with eight equivalent AcBa12 cuboctahedra, edges with twenty-four BaBa8Ac4 cuboctahedra, faces with six equivalent AcBa12 cuboctahedra, and faces with twelve BaBa8Ac4 cuboctahedra. All Ba–Ac bond lengths are 4.29 Å. Ac is bonded to twelve Ba atoms to form AcBa12 cuboctahedra that share corners with four equivalent AcBa12 cuboctahedra, corners with eight equivalent BaBa8Ac4 cuboctahedra, edges with eight equivalent AcBa12 cuboctahedra, edges with sixteen equivalent BaBa8Ac4 cuboctahedra, faces with four equivalent AcBa12 cuboctahedra, and faces with fourteen BaBa8Ac4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ac2TlSn by Materials Project

Ac2TlSn is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Ac is bonded in a body-centered cubic geometry to four equivalent Tl and four equivalent Sn atoms. All Ac–Tl bond lengths are 3.56 Å. All Ac–Sn bond lengths are 3.56 Å. Tl is bonded in a body-centered cubic geometry to eight equivalent Ac atoms. Sn is bonded in a body-centered cubic geometry to eight equivalent Ac atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Unraveling the Molecular Origin of Prey-Wrapping Spider Silk's Unique Mechanical Properties and Assembly Process Using NMR

Prey wrapping spider silk's unique mechanical properties are investigated confirming the silk's high degree of extensibility and superior toughness compared to other types of spider silk. For the first time, the pre-spinning dope phase is studied in isotope-enriched intact aciniform (AC) silk glands using solution NMR that reveals a combination of α-helical domains linked by disordered random coil chains consistent with previously proposed “beads-on-a-string” models. The model is further refined through the AlphaFold2 protein structure prediction tool. Finally, extensive magic angle spinning (MAS) solid-state (SS) NMR data for isotopically-enriched fibers is used to refine the structural model for AC silk from two species, A. aurantia and A. argentata. The SSNMR data shows that the AC silk fibers are highly α-helical, coiled-coil in structure but, also exhibit significant β-sheet components that can be traced back to the Gly-rich disordered linker regions in the pre-spinning dope phase that are converted to β-sheet structures during fiber formation. This combination of mechanical and structural characterization enhances the understanding of AC silk's liquid-to-solid transition and structure-mechanics relationship. In conclusion, these prey wrap silk results and models will provide the basis for the design of biomimetic materials inspired by the AC spider silk system.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Non-premixed counterflow methane flames in DC/AC/NS electric fields

The response of counterflow diffusion flames to sub-breakdown DC and AC electric fields, as well as their superposition with ns pulse discharge waveforms, is studied in the plane-to-plane electrode geometry. Sub-breakdown DC and low-frequency AC electric fields cause the flame displacement toward the grounded electrode, in the direction of the applied field, indicating that the body force on the positive ions exceeds that on the electrons and negative ions. As the AC frequency increases, the flame response becomes less pronounced, due to the reduction of the electrohydrodynamic (EHD) body force impulse over the AC half-period. The electric field in the electrode gap is determined by ps Electric Field Induced Second Harmonic (E-FISH) generation, with absolute calibration using sub-breakdown ns pulses overlapped with the measured electric field waveform. The results show that the electric field distribution across the flame in the current saturation regime follows the Laplacian field. This indicates that the space charge density in the gap is too low to distort the applied DC or AC field, consistent with the kinetic modeling predictions. Combining a nanosecond pulse discharge with a sub-breakdown DC field generates a diffuse plasma across the entire gap. Time-resolved and spatially resolved measurements of the electric field in the discharge indicate the ionization wave propagation between the electrodes. The present results do not exhibit a detectable flame displacement enhancement by ns discharge pulses combined with a sub-breakdown field, observed previously. Kinetic modeling calculations show that the absence of this effect in the plane-to-plane geometry is due to the rapid plasma self-shielding. This indicates that alternative electrode geometries limiting the self-shielding would be more effective for the plasma / electric field enhanced flameholding and flame stabilization applications.

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

Hot, cold, or just right? An infrared biometric sensor to improve occupant comfort and reduce overcooling in buildings via closed-loop control

To improve occupant comfort and save energy in buildings, we have developed a closed-loop air conditioning (AC) sensor-controller that predicts occupant thermal sensation from the thermographic measurement of skin temperature distribution, then uses this information to reduce overcooling (cooling-energy overuse that discomforts occupants) by regulating AC output. Taking measures to protect privacy, it combines thermal-infrared (TIR) and color (visible spectrum) cameras with machine vision to measure the skin-surface temperature profile. Since the human thermoregulation system uses skin blood flow to maintain thermoneutrality, the distribution of skin temperature can be used to predict warm, neutral, and cool thermal states. We conducted a series of human-subject thermal-sensation trials in cold-to-hot environments, measuring skin temperatures and recording thermal sensation votes. We then trained random-forest classification machine-learning models (classifiers) to estimate thermal sensation from skin temperatures or skin-temperature differences. The estimated thermal sensation was input to a proportional integral (PI) control algorithm for the AC, targeting a sensation level between neutral and warm. Our sensor-controller includes a sensor assembly, server software, and client software. The server software orients the cameras and transmits images to the client software, which in turn assesses occupant skin temperature distribution, estimates occupant thermal sensation, and controls AC operation. A demonstration conducted in a conference room in an office building near Houston, TX showed that our system reduced overcooling, decreasing AC load by 42% when the room was occupied while improving occupant comfort (fraction of “comfortable” votes) by 15 percentage points.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2023

Probing lead acetate in solution using X-ray diffraction

Here, for the purpose of water purification involving toxic metal sensing and removal, high energy X-ray diffraction experiments have been performed on lead acetate Pb(Ac) 2 solutions, liquid and amorphous glutathione disulfide (GSSG), and their mixtures. The data have been interpreted using Empirical Potential Structure Refinement and pair distribution function analysis. At the highest concentration of 1 M Pb(Ac) 2 in water, the lead molecules are found to cluster and the second shell in the water structure becomes slightly more ordered as the water molecules become compressed. Liquid and amorphous GSSG are found to hydrogen bond primarily via OH-O interactions, while NH-O bonds are much more distorted. Aqueous solutions of Pb(Ac) 2 + GSSG show the closest Pb-O (carboxyl) and Pb-N (amine) bonds both at a distance of 2.5 ± 0.1 Å at a concentration of 1 M Pb(Ac) 2 in water. At 0.75 M Pb(Ac) 2 in water, strong Pb-S bonds are found at a distance of 2.8 ± 0.1 Å. The implications for lead removal using capacitive deionization are discussed.

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

Pr(H 3 BNMe 2 BH 3 ) 3 and Pr(thd) 3 as Volatile Carriers for Actinium-225. Deposition of Actinium-Doped Praseodymium Boride Thin Films for Potential Use in Brachytherapy

Here we show that the praseodymium N,N-dimethylaminodiboranate complex Pr(H 3 BNMe 2 BH 3 ) 3 and the 2,2,6,6-tetramethylheptane-3,5-dionate complex Pr(thd) 3 can serve as volatile carriers for 225 Ac. The actinium coordination complexes Ac(H 3 BNMe 2 BH 3 ) 3 and Ac(thd) 3 are the likely species subliming with the carrier material. A sample of 225 Ac-doped Pr(H 3 BNMe 2 BH 3 ) 3 was used to deposit amorphous 225 Ac-doped praseodymium boride films on glass and Si(100) at 300 °C. Furthermore, the α emission spectra of the refractory films are well-resolved, suggesting that they could be used as radioactive implants for brachytherapy and related treatments.

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

Bicarbonate-Carbonate Selectivity through Nanofiltration for Direct Air Capture of Carbon Dioxide

Direct air capture (DAC) of carbon dioxide is one approach among many proposed that is capable of offsetting hard-to-avoid emissions. In previous work, we developed the alkalinity concentration swing (ACS) method, which is driven through concentrating an alkaline solution that has been loaded with atmospheric CO 2 by desalination technologies, such as reverse osmosis or capacitive deionization. Though the ACS is promising in terms of energy usage and implementation, its absorption rate and water requirements are infeasible for a large-scale DAC process. Here, we propose an improvement on the ACS, the bicarbonate-enriched alkalinity concentration swing (BE-ACS), which selects bicarbonate ions from a stream of aqueous alkaline solution that has absorbed atmospheric CO 2 . The bicarbonate-rich stream is then concentrated, which greatly increases its CO 2 partial pressure, and then CO 2 is extracted from solution. We experimentally investigate the use of pressure-driven nanofiltration (NF) membrane-based separation to select bicarbonate ions over carbonate ions. We screen commercial membranes and select one high-performance membrane for detailed studies, quantifying its bicarbonate-carbonate selectivity factor and bicarbonate-passage factor. Feed pH, the combined concentration of aqueous CO 2 , bicarbonate, and carbonate species (or dissolved inorganic carbon), alkalinity, and permeation flux are systematically varied to study NF separation properties. We find that the selectivity factor, which exceeds 30 times in certain regimes, increases with higher feed pH and higher alkalinity. Lastly, the performance metrics of the selected NF membrane are input into a theoretical BE-ACS cycle analysis, and the required energy input and cycle capacity output are evaluated. Ideal cycle energy is found to be as low as around 250 kJ/mol, with opportunities identified for further decreases through process engineering and forward osmosis energy recovery.

animal feed↗