1,721,177 research outputs found
Incorporating microstructural and mechanical heterogeneity to Ti-Zr-Nb alloy by partial high-energy ball milling
No full textThis study introduced a novel method for incorporating microstructural and mechanical heterogeneity into Ti-Zr-Nb alloy to improve its strength without significantly affecting the elastic modulus. Ti-Zr-Nb alloy powder was milled at different ball-milling energies using a planetary ball mill, mixed with parent pristine powder in equal weight fractions using a horizontal ball mill, and sintered using spark plasma sintering. The resulting bimodal-like microstructure showed an increase in tensile yield strength (up to 410 MPa) without significant changes in the elastic modulus (<6 GPa). Milling followed by sintering caused grain refinement and precipitation in the relevant zones of the sintered samples, resulting in a heterogeneous structure due to the unique spread of alpha-precipitates. The strength of the heterogeneity-incorporated alloys was improved as a function of milling while maintaining high plasticity and a low elastic modulus.
TiZrNbMoTa High Entropy Alloys for Biomedical Implants Prepared By Powder Metallurgy Route
No full textGradient-controlled interfaces in medium/high entropy alloy composites for enhanced mechanical and biocompatibility performance
No full textA critical challenge in developing orthopedic implants is tuning them to achieve high yield strength, low modulus, and enhanced wear resistance. A key strategy involves optimizing matrix-reinforcement interfaces in metal matrix composites. In this study, we incorporated MoNbTaTiZr-based high-entropy alloy (HEA) particles within a Ti-Zr-Nb (TZN) medium entropy alloy matrix. Using powder metallurgy and spark plasma sintering, we developed a graded core-shell structure around the HEA particles, which refines interfacial bonding and optimizes the load transfer mechanism. The resulting heterogeneous alloy exhibited up to a 50 % enhancement in yield strength (>750 MPa), a low elastic modulus (similar to 65 GPa), and a significant reduction in the wear rate to the order of 10(-4) to 10(-5) mm(3)/Nm, while retaining substantial tensile ductility (>8 %). Molecular dynamics simulations revealed that the HEA particles act as impenetrable obstacles to dislocation motion, inducing partial wrapping and pile-up at the particle-matrix interface. This leads to localized stress accumulation and the generation of back-stress, which corroborates experimental observations of increased yield strength and interface-driven plasticity reduction. Critically, post-sintering annealing of 10 wt% HEA-TZN samples resulted in an optimized interface thickness via Mo and Ta interdiffusion, restoring ductility to levels comparable to pristine TZN without compromising strength. This compositional gradient inhibited crack propagation and promoted dislocation pile-up while ensuring strong interfacial bonding. Additionally, the sintered heterogeneous alloys showed excellent corrosion resistance in simulated body fluid and enhanced cellular adhesion and proliferation compared to conventional biomaterials. The present approach advances orthopedic implant design by combining wear resistance with low modulus to alleviate stress shielding.
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
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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