The melting behaviors of silver nanowires (AgNWs) were investigated by molecular dynamics (MD) simulations using the 2nn-modified embedded-atom method potential (2nn-MEAM) during a temperature elevation process from 0 to 1500 K. Four AgNWs with diameters of 1.6, 2.4, 4.8, and 10 nm were considered, and these nanowire structures with 5-fold twinned boundaries were constructed according to the experimental observations. The melting point of bulk Ag predicted by the two-phase method is about 1280 K, which is very close to the experimental result of 1234 K, indicating the 2nn-MEAM potential can accurately reflect the thermal behavior of Ag material. For AgNWs, the melting points will significantly decrease from 1250 to 790 K as the AgNW diameters decrease from 10 to 1.6 nm. According to the variations of surface atom square displacement (SD) profiles at different temperatures, it is found that the premelting behaviors could be efficiently investigated for all 5-fold twinned AgNWs before their melting temperatures. In addition, this phenomenon is very different from those of Ag single-crystal nanoparticles with diameters smaller than 8 nm, which melt at their melting temperatures without passing a surface premelting stage. The difference in thermal behaviors between the AgNWs and Ag single-crystal nanoparticles can be attributed to the twinned boundaries (TBs) within AgNWs.
In the article entitled "Influential factors of surgical decompression for ulnar nerve neuropathy in Guyon's canal," the author's name was incorrectly listed as "Cheng-Yu Yi." The correct spelling of the author's last name is "Yin." This has been corrected in the online version of the article.
South Africa’s Department of Higher Education and Training (DHET)has put forward ‘open learning’ as an educational approach to addressing issues ofaccess and success in the post-school education and training sector. This chapterinvestigates the possibilities and limitations of online assessment to advance DHET’sopen learning agenda in the technical and vocational education and training (TVET)sector. Adopting a social justice lens, this chapter explores how online assessmenthas the potential to encourage as well as constrain ‘parity of participation’ (Fraser,1995) from an economic, cultural and political perspective. A small empirical studyinvolving interviews with four staff members from Tshwane North TVET College’s OpenLearning Unit and four students is employed to illuminate the themes of social justice.The findings indicate that online assessment has the potential to aid economic justiceby creating the conditions for working individuals to improve their qualifications whilstworking, but lack of access to material resources, such as suitable technologies anddata, can be a deterrent. Culturally, in relation to pedagogy, the findings illustrate thepotential for online assessment to support learning by providing immediate feedbackand creating opportunities for self-assessment, although academic integrity surfacesas a major concern. Politically, the findings indicate how a lack of national policycan hinder the successful operationalisation of online assessment at the course andinstitutional level. The chapter highlights the need to develop policies that correspondwith the philosophies and practices of online assessment and open learning. Itproposes that principles of open learning, combined with the affordances of onlineassessment, allows for an opportunity to explore different modes of assessments fromthe fit-for-purpose perspective.
Every interaction between an educator and a student has the potential to be pedagogically rich. Yet many interactions feel minimal and limited because they are designed to achieve a singular, one-dimensional goal. This is especially true when it comes to assessments. In most cases, assessments provide information to an educator about a student’s understanding of materials that were covered in a course. However, because assessments are often summative (covering knowledge shared up to a given point) and evaluative (aimed at providing information about a student to the educator rather than the student themselves), students rarely learn as much as they could from assessment activities.
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