This paper addresses the energy a s s d t e d with the trapping of hydrogen to defects in a nickel lattice. Several dislocations and grain boundaries which occur in nickel are studied. The dislocations include an edge, a screw, and a Lomer dislocation in the locked configuration, i.e. a Lome-CottreU lock (m). For both the edge and screw dislocations, the maximum trap site energy is approxlmately 0.1 eV occuning in the region where the lattice is in tension approrim3tely 3-4 hgstrilms from the dislocasion core. For the Lomer-CottreU lock, the maximum binding energy is 0.33 eV and is located at the core of the n/6(110) dislocation. Several low-index coincident site lattice grain boundaries are investigated, specifically the E3(112), E9(221) and Ell(113) tilt boundaries The boundaries all show a maximum binding energy of approximately 0.25 eV at the tilt boundary. Relaxation of the boundary structures produces an asymmetric atomic structure for both the E 3 and E9 boundaries and a symmetnc structure for the E l l tilt boundary. The results of this study can be compared to recent experimental studies showing that the activation energy for hydrogen-initiated failure is approximately 0.M0.4 eV in the Fe-based superalloy IN903. From the results of this comparison it can be concluded that the embrittlement process is likely associated with the trapping of hydrogen to grain boundaries and Lomer-Comell Iocks.
Health disparity refers to systematic differences in health outcomes between groups and communities based on socioeconomic isolation. In the USA, health disparities among minority groups, especially African Americans, limit their access to quality medical care and other beneficial resources and services. Presently, the novel coronavirus (COVID-19) highlights the extreme healthcare challenges that exist in the African American and other minority communities in the USA. African Americans are dying at a rate nearly four times higher than the national average. With inadequate access to quality healthcare, viable resources, and information, COVID-19 will continue to have a disastrous effect on African American communities. This communication provides a brief overview of the health inequalities resulting in African Americans dying disproportionately during the COVID-19 pandemic.
The modified embedded atom method (MWM), an empirical extension of the embedded atom method (w) that includes angular forces. has been used to examine the interface between a silicon substrate and a thin overlayer of nickel. A brief review of the MEAM is given and parameters are determined for the Si-Ni system. As verification of the reliability of the model, the geometry, energy and elastic constants of a number of ideal Si-Ni wmpounds are calculated and are found Lo agee reasonably well With experiment and first-principles calculations. Planar defect energies are also presented. Calculations of the relaxed energy and geometry of a coherent IO A overlayer of Ni on Si(00t) yield two similar Ftlllctms, both of which were typified by a slightly rippled Ni structnre relative to psfect FCC Ni. The lower-energy interface also contained rows of slightly shifted Ni atoms. It is found that significant differences occur between the energetics of a rigid or relaxed separation of the overlayer. Separation of the overlayer with a monolayer of Si atoms attached to the Ni yields a significantly lowerenergy StIUchue than separatjon exactly at the interface. The relaxed brittle fracture energy of this interface is found to be 1.5 J m-l, which is significantly lower than the unrelaxed fracture energy of 4.8 1 m-2,
The local Zn/Se relative concentration at the interface in ZnSe-GaAs(001) heterostructures synthesized by molecular beam epitaxy was found to be controlled by the Zn/Se Aux ratio employed during the early growth stage of ZnSe on GaAs. Correspondingly, the valence band discontinuity varies from 1.20 eV (Zn-rich interface) to 0.58 eV (Se-rich interface). Comparison with the results of firstprinciples calculations suggests that the observed trend in band offsets is related to the establishment of neutral interfaces with different atomic configurations.
Digital elevation models (DEMs) derived from airborne lidar are traditionally unreliable in coastal salt marshes due to the inability of the laser to penetrate the dense grasses and reach the underlying soil. To that end, we present a novel processing methodology that uses ASTER Band 2 (visible red), an interferometric SAR (IfSAR) digital surface model, and lidar-derived canopy height to classify biomass density using both a three-class scheme (high, medium and low) and a two-class scheme (high and low). Elevation adjustments associated with these classes using both median and quartile approaches were applied to adjust lidar-derived elevation values closer to true bare earth elevation. The performance of the method was tested on 229 elevation points in the lower Apalachicola River Marsh. The two-class quartile-based adjusted DEM produced the best results, reducing the RMS error in elevation from 0.65 m to 0.40 m, a 38% improvement. The raw mean errors for the lidar DEM and the adjusted DEM were 0.61 ± 0.24 m and 0.32 ± 0.24 m, respectively, thereby reducing the high bias by approximately 49%.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.