Search NASA⌕ Search

SEARCH · Search NASA

Results for “Transforms”

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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Phase transformations, microstructural refinement and defect evolution mechanisms in Al-Si alloys under non-hydrostatic diamond anvil cell compression

Non-hydrostatic compression of materials using a diamond anvil cell (DAC) can transform equilibrium microstructure of an alloy to novel, potentially metastable states. In this study, in situ synchrotron X-ray diffraction (XRD) during compression up to 24 GPa and subsequent ex situ, high resolution analytical electron microscopy (AEM) after decompression of an Al-Si alloy provided insight into the crystallographic changes during the compression as well as microstructural refinement, and defect structures caused by such a high pressure compression-decompression process. Pressure resolved in-situ synchrotron XRD was used to detail the phase transformation pathway of the eutectic Si phase in Al-Si alloy, from Si-I → Si-XI → Si-V during compression, and a final transformation predominantly to Si-III after decompression. Using scanning and transmission electron microscopy (S/TEM), site specific analysis of the alloy immediately underneath the anvil contact surface demonstrated a highly complex microstructure. A narrow region of thick amorphous Al oxide interspersed with nanocrystalline grains was found at the top surface. Underneath this Al oxide, while the majority the eutectic Si was transformed into highly-deformed, polycrystalline (PC) Si-III, a complex intermediate layer was discovered at the interface between Al and Si, comprised of a small fraction of Al nanocrystals and a majority of nanocrystalline Si-I. This combination of pressure resolved in-situ synchrotron XRD coupled with subsequent high resolution, electron microscopy resolved the phase transformation as well as non-equilibrium microstructures in a metallic alloy induced by a non-hydrostatic high pressure compression followed by decompression.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Protection from Cr(VI)-induced malignant cell transformation and tumorigenesis of Cr(VI)-transformed cells by luteolin through Nrf2 signaling

Cr(VI) is a well known environmental carcinogen, but its mechanism of action and the measures required to mitigate its effects remain to be investigated. Our previous studies showed that exposure of human bronchial epithelial (BEAS-2B) cells to Cr(VI) caused malignant transformation, that these transformed cells progressed through tumorigenesis, and that luteolin, a natural compound, inhibited both of these processes. The present study investigates the underlying mechanisms by which luteolin protects cells against Cr(VI)-induced transformation and tumorigenesis. The present study shows that luteolin activates inducible Nrf2 to inhibit Cr(VI)-generated reactive oxygen species (ROS) in normal BEAS-2B cells. The decreased ROS level is likely responsible for the protective effect of luteolin against Cr(VI)-induced malignant cell transformation in normal cells. By contrast, in cells that have been transformed by Cr(VI), Nrf2 is constitutively activated, and its target proteins, heme oxygenase 1 (HO-1), NAD(P)H:quinone oxidoreductase 1 (NQO1), and superoxide dismutase 1/2 (SOD1/SOD2) are all constitutively activated, and ROS levels are low. Bcl-2, an anti-apoptotic protein and target protein of Nrf2 is elevated. Cr(VI)-transformed BEAS-2B cells develop apoptosis resistance, increasing the survival of these transformed cells. Luteolin decreases interactions between Nrf2 and the antioxidant response element sites of its target anti-apoptotic and antioxidant proteins, Bcl-2, Bcl-XL, and HO-1, which results in decreased constitutive Nrf2 activation. The decreased constitutive Nrf2 activation, decrease in Nrf2 target proteins and consequent apoptosis resistance by luteolin are possible mechanisms that mediate the protective effect of luteolin in Cr(VI)-transformed cells. - Highlights: • Constitutive Nrf2 activation in Cr(VI)-transformed cells is oncogenic. • Constitutive Nrf2 activation decreases ROS with development of apoptosis resistance. • Luteolin inhibits constitutive Nrf2 activation in Cr(VI)-transformed cell. • Dietary strategies using luteolin may prevent Cr(VI)-induced carcinogenesis.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

A complex guided spectral transform Lanczos method for studying quantum resonance states

A complex guided spectral transform Lanczos (cGSTL) algorithm is proposed to compute both bound and resonance states including energies, widths, and wavefunctions. The algorithm comprises of two layers of complex-symmetric Lanczos iterations. A short inner layer iteration produces a set of complex formally orthogonal Lanczos polynomials. They are used to span the guided spectral transform function determined by a retarded Green operator. An outer layer iteration is then carried out with the transform function to compute the eigen-pairs of the system. The guided spectral transform function is designed to have the same wavefunctions as the eigenstates of the original Hamiltonian in the spectral range of interest. Therefore, the energies and/or widths of bound or resonance states can be easily computed with their wavefunctions or by using a root-searching method from the guided spectral transform surface. The new cGSTL algorithm is applied to bound and resonance states of HO{sub 2}, and compared to previous calculations.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2026

Miscanthus giganteus Biolistic Transformation Using the Visible RUBY Red Marker Gene to Monitor Transformation Efficiency

Miscanthus × giganteus ( M × g ) is a high-yielding perennial C4 bioenergy crop, but genetic improvement by breeding is constrained by triploid sterility and clonal propagation. Improving genetic transformation methods for M × g would provide opportunities for advantageous trait introgression. Use of an easy to phenotype reporter gene is a promising strategy to improve transformation processes and efficiency. This study presents an efficient novel method for biolistic transformation of inflorescence-derived callus in M × g and demonstrates its efficacy using RUBY, a betalain-based noninvasive reporter that is visible throughout the transformation process. RUBY expression ( Zea mays codon optimized) was visible from callus stage through plantlet development into maturity. RUBY expressing independently transformed plants were confirmed by hygromycin phosphotransferase ELISA and by genomic PCR demonstrating that the RUBY phenotype is sufficient for screening transformants. The Zea mays codon optimized hygromycin selection marker was driven by previously established promoters for Miscanthus, ZmUBI and 2×35S, while the RUBY gene expression was controlled by a known Zea mays C4 promoter, Brachypodium UBI10, newly employed in Miscanthus. The construct containing the 2×35S promoter for hygromycin had a 15.1% transformation efficiency while the ZmUBI promoter had a 20.5% transformation efficiency. This study provides a novel, highly efficient protocol for successful biolistic transformation of M × g for stable expression. This study also demonstrates that RUBY expression can be used as a convenient and powerful monitor of transformation in ongoing and future work to engineer M × g into an improved bioproduct feedstock.

RUBY↗
DOE OSTI2026

Data for Miscanthus giganteus Biolistic Transformation Using the Visible RUBY Red Marker Gene to Monitor Transformation Efficiency

Miscanthus × giganteus ( M × g ) is a high- yielding perennial C4 bioenergy crop, but genetic improvement by breeding is constrained by triploid sterility and clonal propagation. Improving genetic transformation methods for M × g would provide opportunities for advantageous trait introgression. Use of an easy to phenotype reporter gene is a promising strategy to improve transformation processes and efficiency. This study presents an efficient novel method for biolistic transformation of inflorescence- derived callus in M × g and demonstrates its efficacy using RUBY, a betalain-based noninvasive reporter that is visible throughout the transformation process. RUBY expression ( Zea mays codon optimized) was visible from callus stage through plantlet development into maturity. RUBY expressing independently transformed plants were confirmed by hygromycin phosphotransferase ELISA and by genomic PCR demonstrating that the RUBY phenotype is sufficient for screening transformants. The Zea mays codon optimized hygromycin selection marker was driven by previously established promoters for Miscanthus, ZmUBI and 2×35S, while the RUBY gene expression was controlled by a known Zea mays C4 promoter, Brachypodium UBI10, newly employed in Miscanthus. The construct containing the 2×35S promoter for hygromycin had a 15.1% transformation efficiency while the ZmUBI promoter had a 20.5% transformation efficiency. This study provides a novel, highly efficient protocol for successful biolistic transformation of M × g for stable expression. This study also demonstrates that RUBY expression can be used as a convenient and powerful monitor of transformation in ongoing and future work to engineer M × g into an improved bioproduct feedstock. **NOTE: in "TableS2_ProtocolComparison.csv", the data from row 665 to 971 should be removed.

Gene Editing↗
DOE OSTI2023

Transformer power management controllers and transformer power management methods

Transformer power management controllers and transformer power management methods are described. According to one aspect, a transformer power management controller includes processing circuitry configured to monitor an electrical characteristic of electrical energy which is received from a secondary of a transformer of an electric power system, use the monitored electrical characteristic to determine transformer loading information which is indicative of an amount of power which is being supplied by the secondary of the transformer to a plurality of loads which are coupled with the secondary of the transformer, and use the transformer loading information to adjust an amount of the electrical energy which is supplied by the secondary of the transformer to at least one of the loads which is coupled with the secondary of the transformer.

Pratt, Richard M.↗
DOE OSTI2016

Correlated structural and electronic phase transformations in transition metal chalcogenide under high pressure

Here, we report comprehensive studies on the high-pressure structural and electrical transport properties of the layered transition metal chalcogenide (Cr{sub 2}S{sub 3}) up to 36.3 GPa. A structural phase transition was observed in the rhombohedral Cr{sub 2}S{sub 3} near 16.5 GPa by the synchrotron angle dispersive X-ray diffraction measurement using a diamond anvil cell. Through in situ resistance measurement, the electric resistance value was detected to decrease by an order of three over the pressure range of 7–15 GPa coincided with the structural phase transition. Measurements on the temperature dependence of resistivity indicate that it is a semiconductor-to-metal transition in nature. The results were also confirmed by the electronic energy band calculations. Above results may shed a light on optimizing the performance of Cr{sub 2}S{sub 3} based applications under extreme conditions.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2017

In situ Raman spectroscopy of pressure-induced phase transformations in polycrystalline TbPO 4 , DyPO 4 , and Gd x Dy (1– x ) PO 4 [ In situ Raman spectroscopy of pressure-induced phase transformations in DyPO 4 and Gd x Dy (1– x ) PO 4 ]

Xenotime DyPO 4 and Gd x Dy (1–x) PO 4 (x = 0.4, 0.5, 0.6) (tetragonal I41amd zircon structure) have been studied at ambient temperature under high pressures inside a diamond anvil cell with in situ Raman spectroscopy. The typical Raman–active modes of the xenotime structure were observed at low pressures and the appearance of new Raman peaks at higher pressures indicated a phase transformation to a lower symmetry structure—likely monoclinic. Raman mode softening was observed, resulting in a line crossing at approximately 7–8 GPa for each material and preceding the phase transformation. The onset of phase transformation for DyPO 4 occurred at a pressure of 15.3 GPa. DyPO 4 underwent a reversible phase transformation and returned to the xenotime phase after decompression. The transformation pressures of the solid solutions (Gd x Dy (1–x) PO 4 ) were in the range 10–12 GPa. The GdxDy(1–x)PO 4 solid solutions yielded partially reversible phase transformations, retaining some of the high–pressure phase spectrum while reforming xenotime peaks during decompression. The substitution of Gd into DyPO 4 decreased the transformation pressure relative to pure DyPO 4 . In conclusion, the ability to modify the phase transformation pressures of xenotime rare–earth orthophosphates by chemical variations of solid solutions may provide additional methods to improve the performance of ceramic matrix composites.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Transition from the twinning induced plasticity to the γ-ε transformation induced plasticity in a high manganese steel

Neutron-diffraction investigation on the deformation of a Fe-18Mn-3Si-0.6C-0.4Al steel reveals that the twinning is mainly dominant at a stress below 900 MPa, above which the twinning behavior is largely outweighed by phase transformation from the face-centered-cubic (FCC) γ-austenite to the hexagonal-close-packed (HCP) ε-martensite. In the deformed grains, the distribution of ε-martensite is parallel with the twin boundary. Both the well-known {111} γ //{0001} ε relationship and an additional {111} γ //{11–21} ε orientation relation were identified. After the phase transformation, both phases deformed further with the lattice rotating around an axis perpendicular to the tensile direction. Transition from the twinning dominant behavior to the phase transformation induced plasticity effect is explained by the grain orientation dependence of the effective stacking fault energy (ESFE). An asymmetric and inverse relationship between the width of stacking faults (SF) and the ESFE is obtained from the density functional theory (DFT). The tensile stress always increases proportionally with the SF width in the twinning favorable grains and thus a decreasing ESFE. The replacement of twinning activities by phase transformation could be due to both the nucleation site of ε-martensite at the SF of the twin boundary and the decrease of the ESFE in grains which originally favors the twinning.

Materials Science↗
DOE OSTI2015

Morphology-dependent phase transformation of y-Al2O3

The phase transformations of platelet- and rod-shaped ?-Al2O3 were investigated and compared to that of a commercial sample by XRD, BET surface area measurements, Transmission Electron Microscopy (TEM), solid state 27Al-NMR and ethanol temperature programmed desorption (TPD) after sequential annealing in air up to 1100 oC. After annealing at 1100 oC, commercial ?-Al2O3 mostly transformed into a-Al2O3 with drastic surface area reduction (from 200 m2/g to 25 m2/g). Interestingly, platelet- and rod-shaped ?-Al2O3 which showed exactly the same XRD patterns transformed into different phases upon the high temperature calcinations. Platelet-shaped ?-Al2O3 transformed into ?-phase while the rod-shaped ?-Al2O3 transformed into the d-phase and not to the a-polymorph. Both platelet- and rod-shaped aluminas retained significantly higher surface area (~60 m2/g) than the commercial one after the same treatment at 1100 oC. These results suggest that the phase transformation in ?-Al2O3 is strongly affected by not only the crystal structure of the starting material, but its morphology as well. Ethanol TPD from platelet- and rod-shaped alumina after 1100 oC annealing, showed significantly different desorption profiles which suggest different surface characteristics even though they had almost the same surface areas. These different phase transformations were also supported by solid state 27Al-NMR. After 1100oC annealing commercial alumina showed the presence of mostly octahedral Al3+ ions, but the other two samples displayed even higher number of tetrahedral Al3+ ions than the initial ?-Al2O3. Morphological changes were also confirmed by TEM. All these results consistently suggest the morphology-dependent phase transformations of ?-Al2O3 and the improved thermal stability of platelet- and rod- shaped ?-Al2O3 in comparison to a commercial ?-Al2O3. J.Sz. acknowledges the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences (BES), Division of Chemical Sciences, Geosciences & Biosciences for the support of this work.

Lee, Jaekyoung↗
DOE OSTI2020

Shape-preserving amorphous-to-crystalline transformation of CaCO3 revealed by in situ TEM

Organisms use inorganic ions and macromolecules to regulate crystallization from amorphous- precursors, endowing natural biominerals with complex morphologies and enhanced properties. The mechanisms by which modifiers enable these shape preserving transformations are poorly understood. We used in situ liquid-phase transmission electron microscopy to follow the evolution from amorphous calcium carbonate to calcite in the presence of additives. A combination of contrast analysis and infrared spectroscopy shows that Mg ions, which are widely present in seawater and biological fluids, alter the transformation pathway in a concentration-dependent manner. The ions bring excess (structural) water into the amorphous bulk so that a direct transformation is triggered by dehydration in the absence of morphological changes. Molecular dynamics simulations suggest Mg-incorporated water induces structural fluctuations, allowing transformation without the need to nucleate a separate crystal. Thus, the obtained calcite retains the original morphology of the amorphous state, biomimetically achieving the morphological control of crystals seen in biominerals

crystallization, biomineralization, calcium carbon↗
DOE OSTI2026

Laplace Transform–Based Quantum Eigenvalue Transformation via Linear Combination of Hamiltonian Simulation

Eigenvalue transformations, which include solving time-dependent differential equations as a special case, have a wide range of applications in scientific and engineering computation. While quantum algorithms for singular value transformations are well studied, eigenvalue transformations are distinct, especially for nonnormal matrices. Here, we propose an efficient quantum algorithm for performing a class of eigenvalue transformations that can be expressed as a certain type of matrix Laplace transformation. This allows us to significantly extend the recently developed linear combination of Hamiltonian simulation method [D. An, J.-P. Liu, and L. Lin, Phys. Rev. Lett., 131 (2023), 150603; D. An, A. M. Childs, and L. Lin, Commun. Math. Phys. 407, 19 (2026)] to represent a wider class of eigenvalue transformations, such as powers of the matrix inverse, 𝐴 −𝑘 , and the exponential of the matrix inverse, 𝑒 −𝐴 −1 . The latter can be interpreted as the solution of a mass-matrix differential equation of the form form 𝐴⁢𝑢′⁡⁡(𝑡) =−𝑢⁡(𝑡). We demonstrate that our eigenvalue transformation approach can solve this problem without explicitly inverting 𝐴, thereby reducing the computational complexity.

Laplace transform↗
DOE OSTI2018

Coupled Kinetics of Ferrihydrite Transformation and As(V) Sequestration under the Effect of Humic Acids: A Mechanistic and Quantitative Study

In natural environments, kinetics of As(V) sequestration/release is usually coupled with the dynamic iron mineral transformation, which is further influenced by the presence of the natural organic matter (NOM). However, both quantitative and mechanistic understanding of this process is still lacking. In this study, we investigated the effect of humic acids (HA), a major component of NOM, on the coupled kinetics of ferrihydrite transformation into hematite/goethite and sequestration of As(V) in iron minerals. Time-resolved As(V) and HA interactions with iron minerals were studied in stirred-flow kinetic experiments, using aberration-corrected scanning transmission electron microscopy (STEM), and X-ray adsorption spectroscopy. Based on the experimental results, we developed a mechanistic kinetics model for As(V) reactions with iron minerals with varying iron mineral compositions and solution chemistry. Our results showed that HA slowed ferrihydrite transformation and the rates of As(V) speciation changes within iron minerals, while HA did not incorporate into iron minerals. Our kinetics model is able to account for the variations of iron mineral compositions, solution chemistry, and As(V) speciation, which has significant environmental implications on predicting the As(V) behavior in the environment.

ferrihydrite, humic acid↗
DOE OSTI2023

Shock-induced transformation of nitinol shape memory alloy: Effect of stress state on transformation

Due to its numerous practical applications and intriguing phase transformation behavior, shape memory alloys (SMAs) have garnered significant research and development interests. In the past, most studies on the mechanical behavior of SMAs have been conducted under uniaxial stress loadings. Limited research on SMAs under shock loading has not provided conclusive results regarding their transformation behavior and transformation stress under such loading. Additionally, there is a lack of comprehensive understanding regarding the effects of different stress states on transformation behavior. The main objectives of this study are to address these issues. To achieve these objectives, a series of shock wave experiments were designed and conducted. Additionally, quasi-static and dynamic uniaxial stress experiments were carried out to establish a baseline for comparison. The results revealed that the transformation stress under dynamic uniaxial strain shock loading was approximately 1.92 GPa in contrast to 0.5 GPa (quasi-static) to 0.8 GPa (dynamic) observed in uniaxial stress loading. The transformation behavior exhibited noticeable rate sensitivity for both types of loading. There appeared to be a critical strain rate above which the austenite phase was driven to a metastable state. This estimated critical axial strain rate along the loading direction was approximately 2 × 10 3 /s–4 × 10 3 /s for uniaxial stress loading and approximately 2 × 10 6 /s for uniaxial strain loading. The apparent high transformation stress for uniaxial strain loading can likely be attributed to a combination of high-pressure confinement and high strain rate. Furthermore, determining their relative contributions remains an open issue.

36 MATERIALS SCIENCE↗
DOE OSTI2022

New Hybrid Model for Evaluating the Frequency-Dependent Leakage Inductance of a Variable Inductance Transformer (VIT)

Skin and proximity effects can cause a significant drop in the effective leakage inductance of a transformer when the operating frequency is increased. Although the magnetic image method-based double-2-D model can calculate the lowfrequency leakage inductance with sufficient accuracy, it is inherently a frequency-independent model. While Dowell’s 1-D model uses frequency-dependent relations to account for both skin and proximity effects, its accuracy is severely affected by the assumed winding geometry. In this paper, a hybrid model is proposed that uses superposition to combine a modified Dowell’s model with the double-2-D model. The proposed model is investigated on a variable inductance transformer (VIT)—a partially-filled transformer whose leakage inductance can be varied by moving one of the windings mechanically. The frequency-dependent leakage inductances of the VIT evaluated using the hybrid model are in excellent agreement with the corresponding finite element method (FEM) simulated and experimentally measured values, thereby validating the proposed hybrid model.

24 POWER TRANSMISSION AND DISTRIBUTION↗