Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “TC”

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 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on TcC5IO5 by Materials Project

TcC5O5I is alpha U structured and crystallizes in the orthorhombic Cmcm space group. The structure is zero-dimensional and consists of four TcC5O5I clusters. Tc1- is bonded in a distorted square pyramidal geometry to five C+2.40+ and one I1- atom. There is one shorter (1.94 Å) and four longer (2.01 Å) Tc–C bond length. The Tc–I bond length is 2.86 Å. There are two inequivalent C+2.40+ sites. In the first C+2.40+ site, C+2.40+ is bonded in a linear geometry to one Tc1- and one O2- atom. The C–O bond length is 1.16 Å. In the second C+2.40+ site, C+2.40+ is bonded in a linear geometry to one Tc1- and one O2- atom. The C–O bond length is 1.15 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one C+2.40+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one C+2.40+ atom. I1- is bonded in a single-bond geometry to one Tc1- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MnTc2W by Materials Project

WTc2Mn crystallizes in the orthorhombic Immm space group. The structure is one-dimensional and consists of two WTc2Mn ribbons oriented in the (1, 0, 0) direction. W2+ is bonded in a linear geometry to two equivalent Tc2- atoms. Both W–Tc bond lengths are 2.24 Å. Tc2- is bonded in a linear geometry to one W2+ and one Mn2+ atom. The Tc–Mn bond length is 2.70 Å. Mn2+ is bonded in a linear geometry to two equivalent Tc2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HoPaTc2 by Materials Project

PaHoTc2 is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Pa3+ is bonded in a body-centered cubic geometry to eight equivalent Tc3- atoms. All Pa–Tc bond lengths are 2.96 Å. Ho3+ is bonded in a body-centered cubic geometry to eight equivalent Tc3- atoms. All Ho–Tc bond lengths are 2.96 Å. Tc3- is bonded in a body-centered cubic geometry to four equivalent Pa3+ and four equivalent Ho3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GaSiTc2 by Materials Project

Tc2GaSi crystallizes in the orthorhombic Immm space group. The structure is one-dimensional and consists of two Tc2GaSi ribbons oriented in the (1, 0, 0) direction. Tc3- is bonded in a linear geometry to one Ga2+ and one Si4+ atom. The Tc–Ga bond length is 2.54 Å. The Tc–Si bond length is 2.28 Å. Ga2+ is bonded in a linear geometry to two equivalent Tc3- atoms. Si4+ is bonded in a linear geometry to two equivalent Tc3- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ScVTc2 by Materials Project

ScVTc2 crystallizes in the orthorhombic Immm space group. The structure is one-dimensional and consists of two ScVTc2 ribbons oriented in the (1, 0, 0) direction. Sc3+ is bonded in a linear geometry to two equivalent Tc3- atoms. Both Sc–Tc bond lengths are 2.48 Å. V3+ is bonded in a linear geometry to two equivalent Tc3- atoms. Both V–Tc bond lengths are 2.15 Å. Tc3- is bonded in a linear geometry to one Sc3+ and one V3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TaTc2Ge by Materials Project

TaTc2Ge is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Ta4+ is bonded in a body-centered cubic geometry to eight equivalent Tc3- atoms. All Ta–Tc bond lengths are 2.71 Å. Tc3- is bonded in a body-centered cubic geometry to four equivalent Ta4+ and four equivalent Ge2+ atoms. All Tc–Ge bond lengths are 2.71 Å. Ge2+ is bonded in a body-centered cubic geometry to eight equivalent Tc3- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YZrTc2 by Materials Project

YZrTc2 crystallizes in the orthorhombic Immm space group. The structure is one-dimensional and consists of two YZrTc2 ribbons oriented in the (1, 0, 0) direction. Y3+ is bonded in a linear geometry to two equivalent Tc3- atoms. Both Y–Tc bond lengths are 2.49 Å. Zr3+ is bonded in a linear geometry to two equivalent Tc3- atoms. Both Zr–Tc bond lengths are 2.28 Å. Tc3- is bonded in a linear geometry to one Y3+ and one Zr3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PaInTc2 by Materials Project

PaTc2In is Heusler structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Pa3+ is bonded in a body-centered cubic geometry to eight equivalent Tc3- atoms. All Pa–Tc bond lengths are 2.90 Å. Tc3- is bonded in a body-centered cubic geometry to four equivalent Pa3+ and four equivalent In3+ atoms. All Tc–In bond lengths are 2.90 Å. In3+ is bonded in a body-centered cubic geometry to eight equivalent Tc3- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ZrTiTc2 by Materials Project

ZrTiTc2 crystallizes in the orthorhombic Immm space group. The structure is one-dimensional and consists of two ZrTiTc2 ribbons oriented in the (1, 0, 0) direction. Zr2+ is bonded in a linear geometry to two equivalent Tc3- atoms. Both Zr–Tc bond lengths are 2.31 Å. Ti4+ is bonded in a linear geometry to two equivalent Tc3- atoms. Both Ti–Tc bond lengths are 2.17 Å. Tc3- is bonded in a linear geometry to one Zr2+ and one Ti4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfTiTc2 by Materials Project

HfTiTc2 crystallizes in the orthorhombic Immm space group. The structure is one-dimensional and consists of two HfTiTc2 ribbons oriented in the (1, 0, 0) direction. Hf4+ is bonded in a linear geometry to two equivalent Tc3- atoms. Both Hf–Tc bond lengths are 2.34 Å. Ti2+ is bonded in a linear geometry to two equivalent Tc3- atoms. Both Ti–Tc bond lengths are 2.17 Å. Tc3- is bonded in a linear geometry to one Hf4+ and one Ti2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Prognostic importance of the preoperative New‐Naples prognostic score for patients with gastric cancer

Abstract Background The wide applicability of the Naples prognostic score (NPS) is still worthy of further study in gastric cancer (GC). This study aimed to construct a New‐NPS based on the differences in immunity and nutrition in patients with upper and lower gastrointestinal tumors to help obtain an individualized prediction of prognosis. Methods This study retrospectively analyzed patients who underwent radical gastrectomy from April 2014 to September 2016. The cutoff values of the preoperative neutrophil‐to‐lymphocyte ratio (NLR), lymphocyte‐to‐monocyte ratio (LMR), serum albumin (Alb), and total cholesterol (TC) were calculated by ROC curve analysis. ROC and t‐ROC were used to evaluate the accuracy of the prognostic markers. The Kaplan–Meier method and log‐rank test were used to analyze the overall survival probability. Univariate and multivariate analyses based on Cox risk regression were used to show the independent predictors. The nomogram was made by R studio. The predictive accuracy of nomogram was assessed using a calibration plot, concordance index (C‐index), and decision curve. Results A total of 737 patients were included in training cohort, 411 patients were included in validation cohort. ROC showed that the New‐NPS was more suitable for predicting the prognosis of GC patients. NPS = 2 indicated a poor prognosis. Multivariate analysis showed that CEA ( P = 0.026), Borrmann type ( P = 0.001), pTNM ( P < 0.001), New‐NPS ( P < 0.001), and nerve infiltration ( P = 0.035) were independent risk factors for prognosis. Conclusion The New‐NPS based on the cutoff values of NLR, LMR, Alb, and TC is not only suitable for predicting prognosis but can also be combined with clinicopathological characteristics to construct a nomogram model for GC patients.

Wang, Hao↗
DOE OSTI2023

Pertechnetate/perrhenate–capped Zr/Hf–Dihydroxide Dimers: Elucidating Zr–TcO 4 Co–Mobility in the Nuclear Fuel Cycle

Spent nuclear fuel contains heavy element fission products that must be separated for effective reprocessing for a safe and sustainable nuclear fuel cycle. 93 Zr and 99 Tc are high-yield fission products that co-transport in liquid-liquid extraction processes. Here we seek atomic-level information of this co-extraction process, as well as fundamental knowledge about Zr IV (and Hf IV ) aqueous speciation in the presence of topology-directing ligands such as pertechnetate (TcO 4 – ) and non-radioactive surrogate perrhenate (ReO 4 – ). In this context, we show that the flat tetrameric oxyhydroxyl-cluster [M IV 4 (OH) 8 (H 2 O) 16 ] 8+ (and related polymers) is dissociated by perrhenate/pertechnetate to yield isostructural dimers, M 2 (OH) 2 (XO 4 – ) 6 (H 2 O) 6 • 3H 2 O (M=Zr/Hf IV ; X=Re/Tc VII ), elucidated by single-crystal X-ray diffraction. We used these model compounds to understand the pervasive 93 Zr- 99 Tc coextraction with further speciation studies in water, nitric acid, and tetrabutylphosphate (TBP) -kerosene; where the latter two media are relevant to nuclear fuel reprocessing. SAXS (small angle X-ray scattering), compositional evaluation, and where experimentally feasible, ESI-MS (electrospray ionization mass spectrometry) showed that perrhenate/pertechnetate influence Zr/Hf IV -speciation in water. Here, in Zr-XO 4 solvent extraction studies to simulate fuel reprocessing, we provide evidence that TcO 4 – enhances extraction of Zr IV , and compositional analysis of the extracted metal-complexes (Zr-ReO 4 study) is consistent with the crystallized Zr IV 2 (OH) 2 (Re VII O 4 – ) 6 (H 2 O) 6 •dimer.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2025

Unusual Ferromagnetic Band Evolution and High Curie Temperature in Monolayer 1T‐CrTe2 on Bilayer Graphene

2D van der Waals ferromagnets hold immense promise for spintronic applications due to their controllability and versatility. Despite their significance, the realization and in-depth characterization of ferromagnetic materials in atomically thin single layers, close to the true 2D limit, has been scarce. Here, a successful synthesis of monolayer (ML) 1T-CrTe2 is reported on a bilayer graphene (BLG) substrate via molecular beam epitaxy. Using angle-resolved photoemission spectroscopy and magneto-optical Kerr effect measurements, that the ferromagnetic transition is observed at the Curie temperature (TC) of 150 K in ML 1T-CrTe2 on BLG, accompanied by unconventional temperature-dependent band evolutions. The spectroscopic analysis and first-principle calculations reveal that the ferromagnetism may arise from Goodenough-Kanamori super-exchange and double-exchange interactions, enhanced by the lattice distortion and the electron doping from the BLG substrate. These findings provide pivotal insight into the fundamental understanding of mechanisms governing 2D ferromagnetism and offer a pathway for engineering higher TC in 2D materials for future spintronic devices.

Park, Kyoungree↗
DOE OSTI2023

Accelerated Stress Testing of Perovskite Photovoltaic Modules: Differentiating Degradation Modes with Electroluminescence Imaging

Herein, electroluminescence (EL) and thermal imaging are used to examine p–i–n metal halide perovskite (MHP) photovoltaic (PV) mini-modules (MA0.6FA0.4PbI3, 20 cells, 78 cm2) before and after indoor-accelerated stress testing or outdoor deployment. Distinct spatial patterns in the EL images emerge, which depend on the external stress conditions experienced by the mini-module. Imaging results highlight a distribution of dark speckle features that dominate after UV stress, attributed to widespread interfacial contact degradation. Lateral intensity gradients across cells dominate after thermal cycling (TC) stress, attributed to current crowding near scribe defects. While current–voltage analysis alone does not give full insight on the degradation process, this study shows that distinct degradation modes can be further defined by multimodal electro-optical imaging (i.e., EL combined with photoluminescence and dark lock-in thermography). Neither UV exposure nor TC-accelerated stress testing alone replicates the same degradation signatures observed after outdoor deployment, suggesting that multiple degradation modes occur under concurrent stressors outdoors. Finally, spatial characterization of degradation modes in MHP PV mini-modules before and after accelerated stress testing lays the groundwork for developing targeted accelerated stress testing procedures through comparison with outdoor aging.

14 SOLAR ENERGY↗
DOE OSTI2023

Search for heavy Higgs bosons with flavour-violating couplings in multi-lepton plus b-jets final states in pp collisions at 13 TeV with the ATLAS detector

A search for new heavy scalars with flavour-violating decays in final states with multiple leptons and b-tagged jets is presented. The results are interpreted in terms of a general two-Higgs-doublet model involving an additional scalar with couplings to the top-quark and the three up-type quarks (ρ tt , ρ tc , and ρ tu ). The targeted signals lead to final states with either a same-sign top-quark pair, three top-quarks, or four top-quarks. The search is based on a data sample of proton-proton collisions at $\sqrt{s}$ = 13 TeV recorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb –1 . Events are categorised depending on the multiplicity of light charged leptons (electrons or muons), total lepton charge, and a deep-neural-network output to enhance the purity of each of the signals. Masses of an additional scalar boson m H between 200 – 630 GeV with couplings ρ tt = 0.4, ρ tc = 0.2, and ρ tu = 0.2 are excluded at 95% confidence level. Additional interpretations are provided in models of R-parity violating supersymmetry, motivated by the recent flavour and (g – 2) μ anomalies.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Unraveling the role of EGR olefins at advanced combustion conditions in the presence of nitric oxide: Ethylene, propene and isobutene

We report the role of EGR (exhaust gas recirculation) olefinic constituents at advanced combustion conditions in the presence of nitric oxide is unraveled in this study through experimental and modeling efforts using a twin-piston rapid compression machine operating at a stochiometric fuel loading with 20% EGR by mass, pressures of 20 and 40 bar, and temperatures from 680 to 950 K. Five different levels of olefin addition, focusing on ethylene, propene and isobutene, with a fixed amount of NO at 70 ppm are doped into test mixtures of PACE-20, a multi-component gasoline surrogate, where olefin addition effects are characterized through changes in ignition times and heat release rates. Experiments indicate that all three EGR olefins inhibit autoignition reactivity and low-temperature heat release at Tc < 850 K, with isobutene exhibiting the greatest impact, while at Tc > 850 K, low ethylene and propene additions promote reactivity. A recently updated chemical kinetic model, with detailed gasoline/NO x interacting and olefin/NO x interacting chemistry incorporated, is adopted to simulate the experiments. Simulation results are somewhat inconsistent with the experiments, where the model captures the inhibiting effects of all olefins on first-stage ignition reactivity, while consistently predicting a promoting effect on main ignition reactivity. Sensitivity and rate of production analyses reveal that adding olefins greatly alters the role of the consuming pathways for the olefins and their primary derivatives at the initial stage of the oxidation process, particularly with the presence of NO, where the olefins and their derivatives interact with both NO x species such as NO 2 and other species such as OH and HO 2 . The olefin/NO x interactions are particularly pronounced with propene and isobutene addition, where these lead to increased ignition reactivity by facilitating NO production and are mostly responsible for the disagreement between the model and experiments. Further investigations of olefin interacting chemistry, particularly those with NOx species, are needed for chemistry models to accurately predict the complicated effects of EGR.

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

A combined experimental and computational analysis of failure mechanisms in open-hole cross-ply laminates under flexural loading

In this work, integrated experimental tests and computational modeling are proposed to investigate the failure mechanisms of open-hole cross-ply carbon fiber reinforced polymer (CFRP) laminated composites. In particular, we propose two effective methods, which include width-tapered double cantilever beam (WTDCB) and fixed-ratio mixed-mode end load split (FRMMELS) tests, to obtain the experimental data more reliably. We then calibrate the traction-separation laws of cohesive zone model (CZM) used among laminas of the composites by leveraging these two methods. The experimental results of fracture energy, i.e. G Ic and G Tc , obtained from WTDCB and FRMMELS tests are generally insensitive to the crack length thus requiring no effort to accurately measure the crack tip. Moreover, FRMMELS sample contains a fixed mixed-mode ratio of G IIc /G Tc depending on the width taper ratio. Examining comparisons between experimental results of FRMMELS tests and failure surface of B–K failure criterion predicted from a curve fitting, good agreement between the predictions and experimental data has been found, indicating that FRMMELS tests are an effective method to determine mixed-mode fracture criterion. In addition, a coupled experimental-computational modeling of WTDCB, edge notched flexure, and FRMMELS tests are adopted to calibrate and validate the interfacial strengths. Finally, failure mechanisms of open-hole cross-ply CFRP laminates under flexural loading have been studied systematically using experimental and multi-scale computational analyses based on the developed CZM model. The initiation and propagation of delamination, the failure of laminated layers as well as load-displacement curves predicted from computational analyses are in good agreement with what we have observed experimentally.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Mechanical behavior and texture evolution of WE43 magnesium-rare earth alloy in Split-Hopkinson Pressure Bar and Taylor Impact Cylinder Testing

Mechanical behavior and texture evolution of Mg rare-earth alloy WE43 is investigated for strain-rates 10 -3 /s to upwards of 10 5 /s for the two material conditions - as-cast (AC) and T6 age hardened, rolled plate (RT6). The high strain-rate behavior is tested using both Taylor cylinder impact tests (TC) and split Hopkinson pressure bar tests (SHB) and bulk textures are obtained using neutron diffraction. Unlike the quasi-static strained material, AC and RT6 SHB retained high hardening rates throughout the test, even up to 30% true strain. Moreover, the high strain-rate data revealed that the RT6 material has a much higher strength than the AC material, but similar hardening rates despite significantly different initial texture. The flow stress near yield increased up to I 0% for RT6 and up to 30% for AC as the strain-rate increased six orders of magnitude from quasi-static rates 10 -3 /s to 10 3 /s. Neither material exhibited significant plastic anisotropy over the broad range of strain rates, despite the fact that the RT6 material had a moderately strong initial texture. In the TC tests, the geometric cross-sectional changes and texture along the cylinder from the cylindrical sample foot to head are measured and from the neutron diffraction texture analysis, upper-bound estimates of twin volume fraction are obtained as well as dislocation density from analyzing diffraction peak broadening. Recorded geometrical changes along several loading directions show that the material has deformed remarkably homogeneously under impact. Analysis of deformed textures indicates that {101¯2} extension deformation twinning occurred in the RT6 condition over the range of strain rates, with an upper bound estimate of 40% twin volume fraction for approximately 0.10-0.25 true strain. The peak texture components after the impact have their c-axes closely aligned with the impact direction. As a result, these observations are presented and rationalized in the paper.

42 ENGINEERING↗