1,721,381 research outputs found
Designing order–disorder transformation in high-entropy ferritic steels.
Full text linkOrder–disorder transformations hold an essential place in chemically complex high-entropy ferritic steels (HEFSs) due to their critical technological application. The chemical inhomogeneity arising from mixing of multi-principal elements of varying chemistry can drive property altering changes at the atomic scale, in particular short-range order. Using density-functional theory-based linear-response theory, we predict the effect of compositional tuning on the order–disorder transformation in ferritic steels—focusing on Cr–Ni–Al–Ti–Fe HEFSs. We show that Ti content in Cr–Ni–Al–Ti–Fe solid solutions can be tuned to modify short-range order that changes the order–disorder path from BCC-B2 (Ti atomic-fraction = 0) to BCC-B2-L21 (Ti atomic-fraction > 0) consistent with existing experiments. Our study suggests that tuning degree of SRO through compositional variation can be used as an effective means to optimize phase selection in technologically useful alloys.This article is published as Singh, Prashant, and Duane D. Johnson. "Designing order–disorder transformation in high-entropy ferritic steels." Journal of Materials Research 27 (2022): 136-144. DOI: 10.1557/s43578-021-00336-w. Copyright 2021 The Author(s). Attribution 4.0 International (CC BY 4.0). DOE Contract Number(s): AC02-07CH11358. Posted with permission
Density-functional theory of material design: fundamentals and applications-I
No full textThis article is part-I of a review of density-functional theory (DFT) that is the most widely used method for calculating electronic structure of materials. The accuracy and ease of numerical implementation of DFT methods has resulted in its extensive use for materials design and discovery and has thus ushered in the new field of computational material science. In this article, we start with an introduction to Schrödinger equation and methods of its solutions. After presenting exact results for some well-known systems, difficulties encountered in solving the equation for interacting electrons are described. How these difficulties are handled using the variational principle for the energy to obtain approximate solutions of the Schrödinger equation is discussed. The resulting Hartree and Hartree–Fock theories are presented along with results they give for atomic and solid-state systems. We then describe Thomas–Fermi theory and its extensions which were the initial attempts to formulate many-electron problem in terms of electronic density of a system. Having described these theories, we introduce modern DFT by discussing Hohenberg–Kohn theorems that form its foundations. We then go on to discuss Kohn–Sham (KS) formulation of DFT in its exact form. Next, local density approximation (LDA) is introduced and solutions of KS equation for some representative systems, obtained using the LDA, are presented. We end part-I of the review describing the contents of part-II.This article is published as Singh, Prashant, and Manoj K. Harbola. "Density-functional theory of material design: fundamentals and applications-I." Oxford Open Materials Science 1, no. 1 (2021): itab018.
DOI: 10.1093/oxfmat/itab018.
Copyright 2021 The Author(s).
Attribution 4.0 International (CC BY 4.0).
DOE Contract Number(s): AC02-07CH11358.
Posted with permission
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Effect of disorder on thermodynamic instability of binary Rare-earth – Nickel – Palladium compounds
Full text linkWe have investigated the thermodynamic stability of disordered rare-earth phases SmX2 and Sm10X21 (X=Ni, Pd) using machine-learning based analytical descriptor and first-principles density functional theory methods. The absence of Laves phase compounds in R-Pd binary systems is a longstanding problem of rare earth science: even though Ni and Pd belong to the same group of the periodic table and have similar electronic structure, the Pd compound crystallizes in a monoclinic (C2/m) phase with 10:21 stoichiometry, i.e., Sm10Pd21, while the Ni compound adopts a cubic Laves phase (MgCu2) structure. To understand this contrasting phase stability, we performed thermodynamic convex hull analysis of SmxNi1-x and SmxPd1-x binary systems, which is experimentally validated using powder X-ray diffraction (PXRD) analyzes of polycrystalline Sm(NixPd1-x)2 samples with x=0, 0.5, and 1. A detailed electronic-structure (band-structure, charge density, and Fermi-surface) analysis of the differences between SmNi2/SmPd2 and Sm10Ni21/Sm10Pd21 compounds provides the quantum mechanical origin of the unfavorable mixing of Pd with Ni in cubic Laves phase. We show that the stability of Sm-Pd in 10:21 stoichiometry arises from improved intra-/inter-layer 5d-4d bonding compared to the 1:2 stoichiometry. Our work emphasizes the importance of ab-initio methods and computationally inexpensive analytical descriptors for the detailed analysis of thermodynamic and electronic properties of hard-to-prepare rare-earth compounds.This is a manuscript of an article published as Singh, Prashant, Tyler Del Rose, and Yaroslav Mudryk. "Effect of disorder on thermodynamic instability of binary Rare-earth–Nickel–Palladium compounds." Acta Materialia 238 (2022): 118205.
DOI: 10.1016/j.actamat.2022.118205.
Copyright 2022 Acta Materialia Inc.
Posted with permission.
DOE Contract Number(s): AC02-07CH11358
Rising burden of overweight and obesity among Indian adults: empirical insights for public health preparedness
No full textAbstract
With simultaneous efforts to address a huge burden of malnutrition, especially among children and younger women, India also encounters a mushrooming prevalence of overweight and obesity among the adult population. This study analysed data from two consecutive rounds of the National Family Health Survey (NFHS) conducted in 2005–06 and 2015–16, to present the burden of overweight and obesity among adult men and women in India. The findings highlight a rising burden of overweight and obesity, although the level and the extent of change over the study period varied across states. The district-wise analysis revealed geographical clusters of overweight and obesity. Further investigation suggests that overweight or obesity are not exclusive to urban areas, and economically well-off populations are more inclined to be overweight or obese. The trends and patterns of overweight and obesity in India argue for timely public health preparedness and interventions to avoid the rising incidence of non-communicable diseases in India
Incidence of Prehypertension and Hypertension in Rural India, 2012–2018: A Sex-Stratified Population-Based Prospective Cohort Study
No full text
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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