SEARCH · Engineering Papers
Results for “resistivity”
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.
Hepatic leukemia factor promotes resistance to cell death: Implications for therapeutics and chronotherapy
Physiological variation related to circadian rhythms and aberrant gene expression patterns are believed to modulate therapeutic efficacy, but the precise molecular determinants remain unclear. Here we examine the regulation of cell death by hepatic leukemia factor (HLF), which is an output regulator of circadian rhythms and is aberrantly expressed in human cancers, using an ectopic expression strategy in JB6 mouse epidermal cells and human keratinocytes. Ectopic HLF expression inhibited cell death in both JB6 cells and human keratinocytes, as induced by serum-starvation, tumor necrosis factor alpha and ionizing radiation. Microarray analysis indicates that HLF regulates a complex multi-gene transcriptional program encompassing upregulation of anti-apoptotic genes, downregulation of pro-apoptotic genes, and many additional changes that are consistent with an anti-death program. Collectively, our results demonstrate that ectopic expression of HLF, an established transcription factor that cycles with circadian rhythms, can recapitulate many features associated with circadian-dependent physiological variation. - Highlights: ► Circadian-dependent physiological variation impacts therapeutic efficacy. ► Hepatic leukemia factor inhibits cell death and is a candidate circadian factor. ► Hepatic leukemia factor anti-death program is conserved in murine and human cells. ► Transcriptomics indicates the anti-death program results from a systems response.
Fatigue resistant carbon coatings for rolling/sliding contacts
Not Available
Improving corrosion resistance of AZ31B magnesium alloy via a conversion coating produced by a protic ammonium-phosphate ionic liquid
Not Available
Integration of an Oxidation Catalyst with Pd/Zeolite-Based Passive NOx Adsorbers: Impacts on Degradation Resistance and Desorption Characteristics
Explore the source record for details and available documents.
Anion Resistant Oxygen Reduction Electrocatalyst in Phosphoric Acid Fuel Cell
Explore the source record for details and available documents.
Antimicrobial Peptide Resistance of Vibrio cholerae Results from an LPS Modification Pathway Related to Nonribosomal Peptide Synthetases
Abstract not provided
Sintering-resistant Single-Site Nickel Catalyst Supported by Metal-Organic Framework
Developing supported single-site catalysts is an important goal in heterogeneous catalysis, since the well-defined active sites afford opportunities for detailed mechanistic studies, thereby facilitating the design of improved catalysts. We present herein a method for installing Ni ions uniformly and precisely on the node of a Zr-based MOF, NU-1000, in high density and large quantity (denoted as Ni-AIM) using atomic layer deposition (ALD) in a metal–organic framework (MOF) (AIM). Ni-AIM is demonstrated to be an efficient gas-phase hydrogenation catalyst upon activation. The structure of the active sites in Ni-AIM is proposed, revealing its single-site nature. More importantly, due to the organic linker used to construct the MOF support, the Ni ions stay isolated throughout the hydrogenation catalysis, in accord with its long-term stability. A quantum chemical characterization of the catalyst and the catalytic process complements the experimental results. With validation of computational modeling protocols, we further targeted ethylene oligomerization catalysis by Ni-AIM guided by theoretical prediction. Given the generality of the AIM methodology, this emerging class of materials should prove ripe for the discovery of new catalysts for the transformation of volatile substrates.
Electrochemical charge-transfer resistance in carbon nanotube composites
Explore the source record for details and available documents.
High temperature oxidation of corrosion resistant alloys from machine learning
Parabolic rate constants, k p , were collected from published reports and calculated from corrosion product data (sample mass gain or corrosion product thickness) and tabulated for 75 alloys exposed to temperatures between ~800 and 2000 K (~500–1700 °C; 900–3000°F). Data were collected for environments including lab air, ambient and supercritical carbon dioxide, supercritical water, and steam. Materials studied include low- and high-Cr ferritic and austenitic steels, nickel superalloys, and aluminide materials. A combination of Arrhenius analysis, simple linear regression, supervised and unsupervised machine learning methods were used to investigate the relations between composition and oxidation kinetics. The supervised machine learning techniques produced the lowest mean standard errors. The most significant elements controlling oxidation kinetics were Ni, Cr, Al, and Fe, with Mo and Co composition also found to be significant features. The activation energies produced from the machine learning analysis were in the correct distributions for the diffusion constants for the oxide scales expected to dominate in each class.
High resolution resistive thermometry for micro/nanoscale measurements
Explore the source record for details and available documents.
Extensive domain wall motion and deaging resistance in morphotropic 0.55Bi(Ni{sub 1/2}Ti{sub 1/2})O{sub 3}–0.45PbTiO{sub 3} polycrystalline ferroelectrics
Domain wall motion is known as a major source of extrinsic contributions to the dielectric and piezoelectric properties of ferroelectric materials. In the present work, we report the extent of non-180° domain wall motion during strong and weak electric field amplitudes in situ using time-resolved, high-energy X-ray diffraction in the ferroelectric morphotropic phase boundary composition 0.55Bi(Ni{sub 1/2}Ti{sub 1/2})O{sub 3}–0.45PbTiO{sub 3} (BNT-45PT). After application of strong electric fields, two phases are shown to coexist. In the tetragonal phase of this material, the extent of 90° domain wall motion is significant and the domain alignment is nearly saturated. Weak (subswitching) cyclic electric fields are then also shown to induce domain wall motion. Deaging, or the progressive loss of preferred domain orientation during sequentially increasing field amplitudes, is notably low in these materials, showing that the initial domain alignment is strongly stabilized. Overall, the in situ measurements reveal that domain wall motion significantly impacts the structure and properties of BNT-45PT and reinforces the importance of understanding domain wall motion contributions to the physical properties of ferroelectrics.
Publisher's Note: “Bipolar resistive switching characteristics in tantalum nitride-based resistive random access memory devices” [Appl. Phys. Lett. 106, 203101 (2015)]
No abstract prepared.